ArticlePDF Available

A Novel Organic Selenium Compound Exerts Unique Regulation of Selenium Speciation, Selenogenome, and Selenoproteins in Broiler Chicks

Authors:

Abstract and Figures

Background: A new organic selenium compound, 2-hydroxy-4-methylselenobutanoic acid (SeO), displayed a greater bioavailability than sodium selenite (SeNa) or seleno-yeast (SeY) in several species. Objective: This study sought to determine the regulation of the speciation of selenium, expression of selenogenome and selenocysteine biosynthesis and degradation-related genes, and production of selenoproteins by the 3 forms of selenium in the tissues of broiler chicks. Methods: Day-old male chicks (n = 6 cages/diet, 6 chicks/cage) were fed a selenium-deficient, corn and soy–based diet [base diet (BD), 0.05 mg Se/kg] or the BD + SeNa, SeY, or SeO at 0.2 mg Se/kg for 6 wk. Plasma, livers, and pectoral and thigh muscles were collected at weeks 3 and 6 to assay for total selenium, selenomethionine, selenocysteine, redox status, and selected genes, proteins, and enzymes. Results: Although both SeY and SeO produced greater concentrations (P < 0.05) of total selenium (20–172%) and of selenomethionine (≤15-fold) in the liver, pectoral muscle, and thigh than those of SeNa, SeO further raised (P < 0.05) these concentrations by 13–37% and 43–87%, respectively, compared with SeY. Compared with the BD, only SeO enhanced (P < 0.05) the mRNA of selenoprotein (Seleno) s and methionine sulfoxide reductase B1 (Msrb1) in the liver and thigh (62–98%) and thioredoxin reductase (TXRND) activity in the pectoral and thigh muscles (20–37%) at week 3. Furthermore, SeO increased (P < 0.05) the expression of glutathione peroxidase (Gpx) 3, GPX4, SELENOP, and SELENOU relative to the SeNa group by 26–207%, and the expression of Selenop, O-phosphoseryl-transfer RNA (tRNA):selenocysteinyl-tRNA synthase, GPX4, and SELENOP relative to the SeY group by 23–55% in various tissues. Conclusions: Compared with SeNa or SeY, SeO demonstrated a unique ability to enrich selenomethionine and total selenium depositions, to induce the early expression of Selenos and Mrsb1 mRNA and TXRND activity, and to enhance the protein production of GPX4, SELENOP, and SELENOU in the tissues of chicks.
Content may be subject to copyright.
The Journal of Nutrition
Nutrient Physiology, Metabolism, and Nutrient-Nutrient Interactions
A Novel Organic Selenium Compound Exerts
Unique Regulation of Selenium Speciation,
Selenogenome, and Selenoproteins in
Broiler Chicks
1–3
Ling Zhao,
4,9
Lv-Hui Sun,
4,9
* Jia-Qiang Huang,
5
Mickael Briens,
6
De-Sheng Qi,
4
Shi-Wen Xu,
7
and Xin Gen Lei
5,8
*
4
Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University,
Wuhan, Hubei, China;
5
Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University,
Beijing, China;
6
Adisseo France S.A.S., Antony, France;
7
Department of Veterinary Medicine, Northeast Agricultural University, Harbin,
China; and
8
Department of Animal Science, Cornell University, Ithaca, NY
Abstract
Background: A new organic selenium compound, 2-hydroxy-4-methylselenobutanoic acid (SeO), displayed a greater
bioavailability than sodium selenite (SeNa) or seleno-yeast (SeY) in several species.
Objective: This study sought to determine the regulation of the speciation of selenium, expression of selenogenome and
selenocysteine biosynthesis and degradation-related genes, and production of selenoproteins by the 3 forms of selenium
in the tissues of broiler chicks.
Methods: Day-old male chicks (n= 6 cages/diet, 6 chicks/cage) were fed a selenium-deficient, corn and soy–based diet
[base diet (BD), 0.05 mg Se/kg] or the BD + SeNa, SeY, or SeO at 0.2 mg Se/kg for 6 wk. Plasma, livers, and pectoral and
thigh muscles were collected at weeks 3 and 6 to assay for total selenium, selenomethionine, selenocysteine, redox
status, and selected genes, proteins, and enzymes.
Results: Although both SeY and SeO produced greater concentrations (P< 0.05) of total selenium (20–172%) and of
selenomethionine (#15-fold) in the liver, pectoral muscle, and thigh than those of SeNa, SeO further raised (P< 0.05)
these concentrations by 13–37% and 43–87%, respectively, compared with SeY. Compared with the BD, only SeO
enhanced (P<0.05) the mRNA of selenoprotein (Seleno)sand methionine sulfoxide reductase B1 (Msrb1) in the liver and
thigh (62–98%) and thioredoxin reductase (TXRND) activity in the pectoral and thigh muscles (20–37%) at week 3.
Furthermore, SeO increased (P<0.05) the expression of glutathione peroxidase (Gpx)3, GPX4, SELENOP, and SELENOU
relative to the SeNa group by 26–207%, and the expression of Selenop, O-phosphoseryl-transfer RNA (tRNA):
selenocysteinyl-tRNA synthase, GPX4, and SELENOP relative to the SeY group by 23–55% in various tissues.
Conclusions: Compared with SeNa or SeY, SeO demonstrated a unique ability to enrich selenomethionine and total
selenium depositions, to induce the early expression of Selenos and Mrsb1 mRNA and TXRND activity, and to enhance the
protein production of GPX4, SELENOP, and SELENOU in the tissues of chicks. J Nutr 2017;147:789–97.
Keywords: chick, gene expression, selenium, selenoprotein, speciation
Introduction
Selenium is an essential nutrient for humans and animals, with
potential functions in antioxidant defense, immunity, antitu-
morigenesis, and detoxification (1–6). These metabolic func-
tions of selenium have been attributed mainly to its presence in
selenoproteins as the 21st amino acid, selenocysteine (7). There
are 25–26 selenoprotein genes identified in mammal and avian
species (8–10). The effects of dietary selenium concentrations
2
Author disclosures: L Zhao, L-H Sun, J-Q Huang, D-S Qi, S-W Xu, and XG Lei,
no conflicts of interest. M Briens is an employee of Adisseo.
3
Supplemental Tables 1–7 and Supplemental Figure 1 are available from the
‘‘Online Supporting Material’’ link in the online posting of the article and from the
same link in the online table of contents at http://jn.nutrition.org.
9
These authors contributed equally to this work.
*To whom correspondence should be addressed. E-mail: lvhuisun@mail.hzau.edu.cn
(L-H Sun), xl20@cornell.edu (XG Lei).
1
Supported in part by the Chinese Natural Science Foundation Projects
31501987 and 31320103920; the National Science and Technology Supporting
Program of China Project 2013BAD20B04; the Integration and Demonstrati on for
the Science and Technology Service Mode and Technology of the University
Agriculture in the Modern Great Agricultural Region of Northern Cold Region;
and a research gift by Adisseo France S.A.S.
ã2017 American Society for Nutrition.
Manuscript received January 3, 2017. Initial review completed January 23, 2017. Revision accepted March 2, 2017. 789
First published online March 29, 2017; doi:10.3945/jn.116.247338.
at Huazhong Agricultural University on May 6, 2017jn.nutrition.orgDownloaded from
8.DCSupplemental.html
http://jn.nutrition.org/content/suppl/2017/03/29/jn.116.24733
Supplemental Material can be found at:
on the expression of these genes have been studied in mice (11),
rats (12), pigs (13, 14), chicks (9, 10, 15), and turkeys (16). An
upregulation of 7 selenoprotein genes [glutathione peroxidase
(Gpx)
10
1,Gpx4,selenoprotein (Seleno) k,Selenon,Selenoo,
Selenop, and Selenow] was associated with the protection by
dietary selenium against the occurrence of exudative diathesis in
chicks (9), whereas 6 selenoproteins, namely GPX1, GPX4,
SELENOF, SELENON, SELENOP, and SELENOW, served as
metabolic mediators of body selenium to protect against the
onset of dietary selenium deficiency–induced nutritional mus-
cular dystrophy in chicks (10).
Although forms of both inorganic selenium, such as sodium
selenite (SeNa), and organic selenium, such as seleno-yeast
(SeY), are often used as feed additives in animal diets, the
organic form is the preferred source because of the better
bioavailability (17–22) and lower toxicity (23, 24). A new
organic selenium compound, 2-hydroxy-4-methylselenobutanoic
acid (SeO), has been shown to be more bioavailable than SeNa
or SeY to broilers (25, 26), layers (27, 28), and pigs (29).
Because our previous study demonstrated differential regula-
tion of the selenogenome expression in human cancer cell lines
by various forms of selenium compounds (30), it was fasci-
nating to determine if SeO exerted unique effects on the
expression of the whole selenogenome and selected selenopro-
teins in tissues of chicks compared with the effects of SeNa
and SeY.
Notably, the new form of selenium, SeO, also resulted in greater
enrichment of selenocysteine in the muscles of broilers than did SeY
(22). It is well known that selenocysteine is biosynthesized on
its cognate transfer RNA (tRNA) during selenoprotein synthesis
(31). Briefly, the first step in the selenocysteine formation in-
volves the misacylation of tRNA
Sec
by seryl-tRNA synthetase to
give Ser-tRNA
Sec
. Then, the g-hydroxyl group of Ser-tRNA
Sec
is
subsequently phosphorylated by O-phosphoseryl-tRNA kinase to
give O-phosphoseryl-tRNA
Sec
(Sep-tRNA
Sec
). Finally, O-phosphoseryl-
tRNA:selenocysteinyl-tRNA synthase (SepSecS) catalyzes Sep-tRNA
Sec
into Sec-tRNA
Sec
by using selenophosphate as the selenium donor,
which is the product of selenophosphate synthetases (31, 32).
Meanwhile, selenocysteine insertion sequence–binding protein 2
(SECISBP2) is thought to increase the mRNA of the tRNA
Sec
(32)
and selenocysteine lyase (SCLY) is a selenocysteine degradation
enzyme (33), which play important roles in selenocysteine
metabolism. However, comparative effects of SeO with those
of SeNa and SeY on the expression of these selenocysteine
metabolism-related genes were not studied.
Therefore, this experiment was conducted to determine how
SeO, compared with SeNa and SeY, regulated 1) the deposition of
total selenium, selenomethionine, and selenocysteine; 2) the expres-
sion of the whole selenogenome and 5 key genes related to the
selenocysteine biosynthesis and degradation; and 3) the production
of selected selenoproteins and/or their activity and redox status in
the plasma, liver, and pectoral and thigh muscles of broiler chicks.
Methods
Chickens, treatments, and samples collection. Our animal protocol
was approved by the Institutional Animal Care and Use Committee of
Huazhong Agricultural University, China. In total, 144-d-old male Avian
broilers were randomly allocated to 4 treatment groups with 6 replicates
of 6 birds/cage. The base diet (BD) (Supplemental Table 1) was
composed of corn and soybean produced in the selenium-deficient area
of Sichuan, China, and was not supplemented with selenium. The
other 3 experimental diets were prepared by supplementing the same
BD with 0.2 mg Se/kg as SeNa (Retosel 1% selenium; Retorte GmbH),
SeY (0.2% selenium and 64.9% of selenium as selenomethionine
by analysis; Alkosel and Lallemand), or SeO (Selisseo 2% selenium
and $95% of selenium as SeO by analysis; Adisseo). The analyzed
selenium concentrations in the BD and diets with added SeNa, SeY,
and SeO were 0.048, 0.26, 0.24, and 0.25 mg/kg, respectively. All
birds were allowed free access to the designated diets and distilled
water.Theexperimentlastedfor6wk.Themortalityofbirdswas
monitored daily, whereas body weight and feed intake were measured
weekly. Meanwhile, 6 birds from each treatment group (1 bird/cage)
were killed at weeks 3 and 6 to collect blood, liver, and pectoral and
thigh muscle samples. The samples were washed with ice-cold isotonic
saline before being cut with surgical scissors. The samples were
divided into aliquots, snap-frozen in liquid nitrogen, and stored at
280°C until use (9). Aliquots of liver and pectoral muscle samples
were freeze-dried for analyses of total selenium, selenomethionine,
and selenocysteine.
Antioxidant enzyme activities and selenium, selenomethionine,
and selenocysteine concentrations. As previously described (9),
activities of glutathione peroxidase (GPX) and superoxide dismutase
and concentrations of glutathione and malondialdehyde were mea-
sured by a colorimetric method with the use of specific assay kits
(A005, A001, A006–1, and A003) from the Nanjing Jiancheng
Bioengineering Institute of China. The activity of thioredoxin reduc-
tase (TXNRD) was measured by the NAD(P)H-dependent reduction
of 5,5-dithiobis-(2-nitrobenzoicacid) (6) with the use of a specific
assay kit (BW11) from the Suzhou Comin Biotechnology Co., Ltd. of
China. Protein concentrations were measured by the bicinchoninic
acid assay (14). The concentrations of total selenium in the feed,
plasma, liver, and muscles were measured by the inductively coupled
plasma MS (ICP MS; Agilent 7500cx) (25). Speciation of selenome-
thionine and selenocysteine was carried out as previously described
(25, 34).
Real-time q-PCR and Western blot analyses. Total RNA was
extracted from the liver and muscles (50 mg tissue) of 6 chicks from
each group, and the relative RNA abundance qualification was
conducted as previously described (10, 13). Primers (Supplemental
Table 2) for the assayed genes and the reference gene GAPDH were the
same as those used in our previous study (6). The 22
2ddCt
method was
used for the quantification with GAPDH as a reference gene, and the
relative abundance was normalized to the BD control (as 1). Western
blot analyses of the pertaining samples were performed as previously
described (14). The primary antibodies used for the analyses are
presented in Supplemental Table 3 (10, 35). The specificity and
reliability of individual antibodies against the selected selenoproteins
were validated (Supplemental Figure 1). The abundance of SELENOP
in tissues was estimated based on the intensity of the long band
(57 kDa).
Statistical analysis. Statistical analysis was performed by using SPSS,
version 13. Data are presented as means 6SEs. Dietary effects
were determined by one-factor ANOVA with a significance level of
P< 0.05, and the Tukey-Kramer method was used for multiple mean
comparisons.
Results
Growth performance and deposition of total selenium,
selenomethionine, and selenocysteine. The 4 diets had
similar effects on body-weight gain, feed intake, and the ratio of
gain to feed at week 3 or 6 or overall (Table 1,Supplemental
10
Abbreviations used: BD, base diet; GPX, glutathione peroxidase; Msrb1,
methionine sulfoxide reductase B1; PSTK, O-phosphoseryl-tRNA kinase; SCLY,
selenocysteine lyase; SECISBP2, selenocysteine insertion sequence-binding
protein 2; SELENO, selenoprotein; SeNa sodium selenite; SeO, 2-hydroxy-4-
methylselenobutanoic acid; SepSecS, O-phosphoseryl-tRNA:selenocysteinyl-tRNA
synthase; SeY, seleno-yeast; tRNA, transfer RNA; TXNRD, thioredoxin reductase.
790 Zhao et al.
at Huazhong Agricultural University on May 6, 2017jn.nutrition.orgDownloaded from
Table 4). Compared with the BD, the 3 forms of selenium
enhanced (P< 0.05) selenium concentrations by 73% to 10-fold
in the plasma, liver, and pectoral and thigh muscles at weeks 3
and 6 (Table 1). Compared with SeNa, the 2 organic selenium
compounds SeY and SeO did not further enhance the selenium
concentrations in plasma, but they elevated the selenium concen-
tration by 20–25% (P= 0.06 or 0.08), 1.3- to 1.7-fold (P<0.05)
and 33–95% (P< 0.05) in the liver and pectoral and thigh
muscles, respectively, at week 3 and/or 6. Notably, SeO further
raised the selenium concentrations in the pectoral and thigh
muscles by 15–37% (P< 0.05) compared with SeY.
Compared with the BD, the 2 organic selenium forms SeY
and SeO led to greater (P< 0.05) selenomethionine concentra-
tions in the liver (3.5–7.3-fold) and pectoral muscle (12–19-fold)
at weeks 3 and 6 (Figure 1). Furthermore, SeO resulted in 87%
and 43% greater (P< 0.05) selenomethionine concentrations
in the liver at week 6 and in the pectoral muscle at week 3,
respectively, than did SeY. While all 3 forms of selenium (SeNa,
SeY, and SeO) elevated (P< 0.05) selenocysteine concentrations
in the liver (5.5–9.3-fold) and pectoral muscle (4.5–7.0-fold)
compared with the BD, the elevations by SeNa were 29–46%
and 16–41% greater (P< 0.05) in the liver and pectoral muscle,
respectively, than those by SeY and/or SeO. The concentration
of selenocysteine accounted for >95% in the liver and 84–97%
in the pectoral muscle of the total selenium concentration at
week 3 and/or 6 in the SeNa group but only 64–77% and 30–31%
in the SeY group and 66–74% and 25–29% in the SeO group,
respectively.
Enzyme activity and redox status. Compared with the BD,
the 3 forms of selenium enhanced (P< 0.05) GPX activities in the
plasma and liver by 38–60% and 3.9–7.3-fold, respectively
(Table 2). Notably, the enhancement by the 2 organic selenium
forms SeY and SeO was 11–28% greater (P< 0.05) in the liver
than that by SeNa. Only SeO elevated (P< 0.05) the TXNRD
activities by 37% and 20% in the pectoral and thigh muscles at
week 3, respectively, compared with the BD. Although SeNa
decreased (P< 0.05) glutathione concentration by 36–48% only
in the pectoral muscle compared with the BD, SeO caused
consistent decreases (P< 0.05) in glutathione concentrations in
the plasma, liver, and both muscles. The 4 diets exerted similar
effects on superoxide dismutase activity or malondialdehyde
concentration in the plasma, liver, or muscles (Supplemental
Table 4).
Expression of the selenogenome and selenocysteine
biosynthesis and degradation-related genes. In the liver,
compared with the BD, the 3 forms of selenium enhanced (P<0.05)
mRNA abundance of 11 selenoprotein genes [Gpx1,Gpx3,
Gpx4,methionine sulfoxide reductase B1 (Msrb1),Selenok,
Selenon,Selenop,Selenop2,Selenos,Selenou, and Selenow] and
2 selenocysteine biosynthesis-related genes (Pstk, SepSecS)at
week 3 and/or 6 (Figure 2A, B). Compared with SeNa, SeY
and/or SeO elevated (P< 0.05) mRNA abundance of 6
selenoproteins (Gpx1,Gpx3,Msrb1,Selenop,Selenop2, and
Selenos). Only SeO upregulated (P< 0.05) the hepatic mRNA
abundance of Msrb1 and Selenos compared with the BD at
week3andGpx3 and Selenop2 compared with SeNa and SeY
at week 6.
In the pectoral muscle, compared with the BD, the 3 forms
of selenium enhanced (P< 0.05) mRNA abundance of 8
selenoprotein genes (Gpx1,Gpx3,Gpx4,Selenoh,Selenok,
Selenop,Selenou,andSelenow) and 2 selenocysteine biosynthesis-
related genes (Pstk and SepSecS) at week 3 and/or 6 but
decreased (P< 0.05) Txrnd1 mRNA abundance at week 6
(Figure 3A, B). Compared with SeNa, SeY and/or SeO elevated
(P< 0.05) mRNA abundance of 4 selenoproteins (Gpx3,
Selenop,Selenou, and Selenow) and SepSecS in the pectoral
muscle. Compared with SeY, SeO upregulated (P< 0.05) mRNA
abundance of Selenop at weeks 3 and 6 and SepSecS at week 6 in
the pectoral muscle.
In the thigh muscle, compared with the BD, the 3 forms
of selenium enhanced (P< 0.05) mRNA abundance of 7
selenoprotein genes (Gpx1,Gpx3,Selenoh,Selenom,Selenop,
Selenou,and Selenow) and 2 selenocysteine biosynthesis-related
genes (Pstk and SepSecS) at week 3 and/or 6 but decreased
(P< 0.05) Txrnd1 mRNA abundance at week 6 (Figure 4A, B).
Compared with SeNa, SeY and/or SeO elevated (P< 0.05)
TABLE 1 Effects of 3 selenium forms on growth performances and selenium concentrations in the
plasma, liver, and muscle of chicks
1
BD SeNa SeY SeO
Weeks 1–6
Body-weight gain, kg/bird 2.10 60.08 2.15 60.02 2.16 60.04 2.21 60.07
Feed intake, kg/bird 3.45 60.10 3.57 60.09 3.57 60.06 3.58 60.01
Ratio of gain to feed, g/kg 608 612 603 611 606 612 617 621
Week 3 selenium concentration
Plasma,
2
μg/L 110 66
a
190 619
b
210 622
b
230 621
b
Liver,
3
mg/kg 0.23 60.01
a
1.7 60.07
b
1.5 60.10
b
1.7 60.14
b
Pectoral muscle,
3
μg/kg 67 62
a
270 613
b
610 620
c
740 634
d
Thigh muscle,
2
μg/kg 61 66
a
210 614
b
280 617
c
350 620
d
Week 6 selenium concentration
Plasma,
2
μg/L 130 610
a
250 618
b
270 621
b
290 618
b
Liver,
3
mg/kg 0.32 60.02
a
2.0 60.14
b,
*
,#
2.4 60.15
b,
* 2.5 60.21
b,#
Pectoral muscle,
3
μg/kg 60 62
a
270 68
b
620 622
c
710 613
d
Thigh muscle,
2
μg/kg 86 66
a
210 618
b
300 618
c
410 640
d
1
Values are means 6SEs, n= 6. Labeled means in a row without a common superscript letter differ, P,0.05. *
,#
Different: *P= 0.08,
#
P= 0.06. BD, base diet; SeNa, BD supplemented with 0.2 mg Se/kg as sodium selenite; SeO, BD supplemented with 0.2 mg Se/kg as
2-hydroxy-4-methylselenobutanoic acid; SeY, BD supplemented with 0.2 mg Se/kg as seleno-yeast.
2
Selenium concentration was measured in fresh tissues.
3
Selenium concentration was measured in freeze-dried tissues.
Regulation by an organic selenium compound 791
at Huazhong Agricultural University on May 6, 2017jn.nutrition.orgDownloaded from
mRNA abundance of 7 selenoproteins (Gpx3,Msrb1,Selenoh,
Selenom,Selenop,Selenos, and Selenou) and SepSecS in the
thigh muscle at week 3 and/or 6. Compared with SeY, SeO
upregulated (P< 0.05) mRNA abundance of 3 selenoproteins
(Selenoh,Selenop, and Selenos) at week 3 and/or 6 and SepSecS
at week 3 in the thigh muscle. In contrast, mRNA abundance of
the other 3 selenocysteine biosynthesis and degradation-related
genes (Secisbp2,selenophosphate synthetase 1, and Scly) and
the rest of selenoproteins were not affected by the diets or
selenium forms in any of the assayed tissues (Supplemental
Tables 5–7).
Production of selected selenoproteins. Compared with the
BD, the 3 forms of selenium enhanced (P< 0.05) production of
hepatic SELENOP, GPX1, GPX4, SELENOU, and SELENOW
at weeks 3 and 6 (Figure 5A, B). Compared with SeNa, SeY and
SeO enhanced (P< 0.05) production of hepatic SELENOP,
GPX4, and SELENOU at both time points. Compared with SeY,
SeO elevated (P< 0.05) production of hepatic SELENOP and
GPX4 at weeks 3 and 6. Impacts of the 3 forms of selenium on
the production of these 5 selenoproteins in the pectoral (Figure
6A, B) and thigh (Figure 7A, B) muscles at the 2 time points were
very similar to those shown in the liver, with the exception that
SeO resulted in a greater production (P< 0.05) of SELENOU in
the thigh muscle than did SeY at week 3.
Discussion
Our study has demonstrated the unique capacity of SeO, in
comparison with SeNa and SeY, to regulate selenoproteins at the
mRNA, protein, and enzyme activity levels. At both weeks 3 and
6, SeO led to a greater upregulation of Gpx1,Gpx3,Selenop,
Selenoh, and Selenou mRNA; production of GPX4, SELENOP,
FIGURE 1 Effect of 3 Se forms on total Se, SeMet, and SeCys
concentrations in the liver at weeks 3 (A) and 6 (B) and the pectoral
muscle at weeks 3 (C) and 6 (D) in chicks. Values are means 6SEs,
n= 6 for total Se concentrations and n= 3 (pools of 2 chicks) for
SeMet and SeCys concentrations. Means within the same plot
without a common letter differ, P,0.05. A given 2 means within the
same plot labeled with *,
#
,or
+
differ at P= 0.06–0.1. BD, base diet;
DM, dry matter; SeCys, selenocysteine; SeMet, selenomethionine;
SeNa, BD supplemented with 0.2 mg Se/kg as sodium selenite; SeO,
BD supplemented with 0.2 mg Se/kg as 2-hydroxy-4-methylseleno-
butanoic acid; SeY, BD supplemented with 0.2 mg Se/kg as seleno-
yeast.
TABLE 2 Effect of 3 selenium forms on the redox status in the
plasma, liver, and muscles of chicks
1
BD SeNa SeY SeO
Week 3
Plasma
GPX, U/mg 3.4 60.2
a
4.8 60.6
b
4.8 60.4
b
4.7 60.5
b
GSH, μmol/g 2.8 60.4
a
3.2 60.4
a
1.2 60.1
b
1.0 60.2
b
Liver
GPX, U/mg 47 610
a
230 66.7
b
290 614
c
290 622
c
Pectoral muscle
TXNRD, U/mg 7.1 60.4
a
6.9 60.3
a
7.6 60.7
a
9.7 60.4
b
GSH, μmol/g 9.6 60.9
a
6.1 60.6
b
6.1 60.4
b
6.8 61.0
b
Thigh muscle
TXNRD, U/mg 10 60.8
a
9.8 60.4
a
10 61.0
a
12 60.6
b
GSH, μmol/g 17 61.3
a
14 62.1
ab
12 60.2
b
13 60.5
b
Week 6
Plasma
GPX, U/mg 3.5 60.4
a
5.3 60.7
b
5.2 60.7
b
5.6 60.9
b
GSH, U/mg 0.62 60.09
a
0.58 60.05
a
0.52 60.08
a,b
0.41 60.05
b
Liver
GPX, U/mg 49 65.6
a
340 67.6
b
410 69.7
c
380 68.1
c
GSH, μmol/g 71 62.5
a
61 66.1
a,b
68 64.2
a,b
57 63.5
b
Pectoral muscle
GSH, μmol/g 13 60.8
a
6.8 60.7
b
8.6 60.4
b
8.4 60.9
b
Thigh muscle
GSH, μmol/g 15 60.9
a
13 60.4
ab
12 60.5
b
13 60.9
b
1
Values are means 6SEs, n= 6. Labeled means in a row without a common
superscript letter differ, P,0.05. Measures without significant changes were shown
in Supplemental Table 4. BD, BD; GPX, glutathione peroxidase; GSH, glutathione; SeNa,
BD supplemented with 0.2 mg Se/kg as sodium selenite; SeO, BD supplemented with
0.2 mg Se/kg as 2-hydroxy-4-methylselenobutanoic acid; SeY, BD supplemented with
0.2 mg Se/kg as seleno-yeast; TXNRD, thioredoxin reductase.
792 Zhao et al.
at Huazhong Agricultural University on May 6, 2017jn.nutrition.orgDownloaded from
and SELENOU; and GPX activity in the liver, pectoral muscle,
and/or thigh muscle than that by SeNa and/or SeY. At week 3,
only SeO and not SeNa or SeY was able to elevate the expression
of Selenos and Msrb1 mRNA in the liver and thigh muscle and
TXNRD activity in the pectoral and thigh muscles compared
with the BD control. Seemingly, SeO might serve as a novel
selenium supplier or donor that not only shared similar efficacy
with SeNa and SeY in supporting the ‘‘general’’ expression of the
selenogenome but also possessed unique potential in promoting
the functional expression of selected selenoproteins. Previously,
we observed a similar unique upregulation of Gpx1,Gpx4,
Selenof,Selenop,Selenos, and Selenom in human prostate
cancer cells (DU145) by selenium from the selenium-biofortified
porcine serum and methylseleninic acid compared with seleno-
methionine or SeNa (30). Different regulations of selenoprotein
mRNA and protein expression were also produced by SeNa and
SeY in the present study. Although both mRNA and protein
concentrations of GPX1 and SELENOW were upregulated
across the 3 tissues by all the selenium supplements, 11 of the 26
selenoprotein genes were not affected by any form of selenium in
any tissue. This outcome largely resembles the responses of
selenogenome expression to dietary selenium supplementation
in previous studies (9, 10, 15, 16). Indeed, no simple or universal
mechanism has been revealed to explain or predict the global or
specific regulation of selenogenome or selenoprotein expres-
sion in a given tissue by dietary selenium (9, 10, 12–16). Thus,
the mechanism for the unique capacities of SeO in regulating
the identified selenoprotein gene expression, protein produc-
tion, and enzyme activity remains a future research endeavor.
From the biochemical standpoint, those uniquely upregulated
selenoproteins by SeO are involved in antioxidation, anti-
inflammation, and detoxification (7, 8, 36–39). Although this
FIGURE 2 Effect of 3 Se forms
on mRNA abundances of seleno-
protein and SeCys biosynthesis–
related genes relative to the BD
(set at 1.0) in the liver of chicks at
weeks 3 (A) and 6 (B). Values are
means 6SEs, n=6.Means
without a common letter differ,
P,0.05. BD, base diet; Gpx,
glutathione peroxidase; Msrb1,
methionine sulfoxide reductase
B1; Pstk, O-phosphoseryl-transfer
RNA kinase; SeCys, selenocysteine;
Seleno, selenoprotein; SeNa, BD
supplemented with 0.2 mg Se/kg
as sodium selenite; SeO, BD sup-
plemented with 0.2 mg Se/kg as
2-hydroxy-4-methylselenobutanoic
acid; SepSecS, O-phosphoseryl-
transfer RNA:selenocysteinyl–transfer
RNA synthase; SeY, BD supple-
mented with 0.2 mg Se/kg as
seleno-yeast.
FIGURE 3 Effect of 3 Se forms
on mRNA abundances of Seleno
and selenocysteine biosynthesis–
related genes relative to the BD
(set at 1.0) in the pectoral muscle
of chicks at weeks 3 (A) and 6 (B).
Values are means 6SEs, n=6.
Labeled means without a common
letter differ, P,0.05. BD, base
diet; Gpx, glutathione peroxidase;
Pstk, O-phosphoseryl-transfer RNA
kinase; Seleno, selenoprotein; SeNa,
BD supplement with 0.2 mg Se/kg
as sodium selenite; SeO, BD sup-
plement with 0.2 mg Se/kg as
2-hydroxy-4-methylselenobutanoic
acid; SepSecS, O-phosphoseryl-
transfer RNA:selenocysteinyl-
transf er RNA synthase; SeY, base
diet supplement with 0.2 mg Se/kg
as seleno-yeast; Txnrd, thioredoxin
reductase.
Regulation by an organic selenium compound 793
at Huazhong Agricultural University on May 6, 2017jn.nutrition.orgDownloaded from
type of upregulation resulted in no substantial improvement in
growth performance or redox status of chicks reared at the
conditions of the present study, it may offer extra protection or
benefit to chicks under oxidative, environmental (e.g., heat and
density), and metabolic stresses. Despite no consistent changes
at week 6, the SeO-induced expression of Selenos and Msrb1
mRNA and TXNRD activity in the tissues of chicks at week 3
should not be ignored. Because broiler chicks represent one of
the fastest growing animals during early life, an upregulation of
antioxidant genes or protein can be viewed as the metabolic
needsorgrowthbenets.
With effects on the chick-growth performance similar to
SeNa or SeY (18, 22, 25, 29), SeO seemed to be more effective in
delivering selenium to enrich tissue selenium after meeting the
need for selenoprotein biosynthesis. First, this hydroxy analogue
of selenomethionine enhanced mRNA, protein, and activity of
selected selenoproteins more than SeNa and SeY did, which is
outlined above. Second, SeO produced the highest selenium
concentrations in both muscles at both time points and the
highest selenomethionine concentrations in the pectoral muscle
at week 3 and in the liver at week 6. These superior efficacies are
consistent with previous reports with broilers, pigs, and cattle
(22, 25, 29, 40). It is well known that selenomethionine
metabolism is closely related to its sulfur homolog and can be
incorporated into proteins in the place of methionine nonspe-
cifically (41). Technically, selenomethionine represents a sele-
nium storage form that could compete with methionine for
absorption and protein synthesis. However, the total methionine
concentration was 0.69% in the BD, whereas the dietary
incorporation of SeY and SeO was at 0.01% and 0.001%,
respectively, to supply the required selenium (0.2 mg/kg). The
extremely low molar ratios of selenomethionine to methionine
(1:21,200 and 1:14,500 for SeY and SeO, respectively) in the
diets probably precluded a major effect of selenomethionine on
methionine metabolism. Because SeO caused no further in-
creases in the plasma total selenium concentrations compared
with those caused by SeNa and SeY at either time point, the
resultant differences in total selenium and selenomethionine
FIGURE 4 Effectof3Seforms
on mRNA abundances of Seleno
and selenocysteine biosynthesis–
related genes relative to the BD
(set at 1.0) in the thigh muscle of
chicks at weeks 3 (A) and 6 (B).
Values are means 6SEs, n=6.
Means without a common letter
differ, P,0.05. BD, base diet; Gpx,
glutathione peroxidase; Msrb1,me-
thionine sulfoxide reductase B1;
Pstk, O-phosphoseryl-transfer RNA
kinase; Seleno, selenoprotein;
SeNa, BD supplement with 0.2 mg
Se/kg as sodium selenite; SeO, BD
supplement with 0.2 mg Se/kg as
2-hydroxy-4-methylselenobutanoic
acid; SepSecS, O-phosphoseryl-
transfer RNA:selenocysteinyl-transfer
RNA synthase; SeY, base diet sup-
plement with 0.2 mg Se/kg as seleno-
yeast; Txnrd, thioredoxin reductase.
FIGURE 5 Effectof3Seforms
on protein production of SELENOP,
GPX1, GPX4, SELENOW, and
SELENOU relative to the BD (set
at 100) in the liver of chicks at
weeks 3 (A) and 6 (B). Values are
means 6SEs, n= 3–4. The relative
density values under respective
bands without a common letter
differ, P,0.05. ACTB, b-actin;
BD, base diet; GPX, glutathione
peroxidase; SELENO, selenoprotein;
SeNa, BD supplement with 0.2 mg
Se/kg as sodium selenite; SeO, BD
supplement with 0.2 mg Se/kg as
2-hydroxy-4-methylselenobutanoic
acid; SeY, BD supplement with
0.2 mg Se/kg as seleno-yeast.
794 Zhao et al.
at Huazhong Agricultural University on May 6, 2017jn.nutrition.orgDownloaded from
concentrations in the muscles and liver were indicative of a pool-
specific and time-dependent distribution and saturation of se-
lenium. From the metabolic modeling standpoint (42, 43),
plasma selenium represents the mobile pool of body selenium
that circulates selenium to meet various metabolic needs in
tissues and is often maintained at a steady state with an adequate
selenium supply. Clearly, the 3 forms of selenium shared similar
efficacy in maintaining the plasma selenium pool. The liver has
the tissue that synthesizes SELENOP that is supposed to carry
selenium to other tissues, which serves as the major selenium
metabolism pool (43–45). The dynamic nature of this selenium
pool and the metabolic priority of selenium partitioning may
help to explain why the difference in total selenium and se-
lenomethionine concentrations between the SeY and SeO groups
appeared only at the later time point. Obviously, muscle
functions as the largest deposit pool of selenium (44, 45) and
showed the highest enrichment of selenium and/or selenomethi-
onine at the earlier time point.
The superior efficacy of the organic selenium (SeY and SeO)
to the inorganic selenium (SeNa) in enriching total selenium and
selenomethionine in the liver and muscles (21, 22) may be
associated with the mode of intestinal absorption (46, 47) and
the ability to be incorporated into proteins in the place of
methionine (22, 41). Additional evidence that SeO is a better
selenium supplier was the lower relative percentage of seleno-
cysteine to the higher total selenium in the liver and pectoral
muscle compared with that of SeNa. Although SeNa produced
slightly higher concentrations of selenocysteine in both tissues
than SeO did, the relative percentages of selenocysteine to the
total selenium were >95% in the liver and 84–97% in the
muscles for SeNa, but only 66–74% and 25–29% for SeO,
respectively. If selenocysteine is considered to be more a
functional form and selenomethionine to be more a storage
form, the higher percentages of selenocysteine to the lower
total selenium concentration in the SeNa group than the in SeO
group may be interpreted as less saturation of the functional
selenium for the biosynthesis of selenoproteins. In fact, SeO
resulted in greater protein productions of GPX4, SELENOP,
and/or SELENOU and TXNRD activity than did SeNa or SeY.
The moderately elevated selenocysteine concentrations by
SeNa compared with SeO may be paradoxically unutilized as
free selenocysteine or ‘‘selenocysteine-containing proteins,’
which are not incorporated into selenoproteins or an acceler-
ated selenoprotein degradation (48–50). New antibodies will
be required to determine if the elevated selenocysteine by SeNa
promotes the production of other selenoproteins not assayed in
the presented study. However, our results were inconsistent
with previous studies in which higher muscle selenocysteine
FIGURE 6 Effect of 3 Se forms
on protein production of SELENOP,
GPX1, GPX4, SELENOW, and
SELENOU relative to the BD (set
at 100) in the pectoral muscle of
chicks at weeks 3 (A) and 6 (B).
Values are means 6SEs, n= 3–4.
The relative density values under
respective bands without a com-
mon letter differ, P,0.05. ACTB,
b-actin; BD, base diet; GPX, glu-
tathione peroxidase; SELENO,
selenoprotein; SeNa, BD supple-
ment with 0.2 mg Se/kg as sodium
selenite; SeO, BD supplement
with 0.2 mg Se/kg as 2-hydroxy-4-
methylselenobutanoic acid; SeY,
BD supplement with 0.2 mg Se/kg
as seleno-yeast.
FIGURE 7 Effect of 3 Se forms
on protein production of SELENOP,
GPX1, GPX4, SELENOW, and
SELENOU relative to the BD (set
at 100) in the thigh muscle of
chicks at weeks 3 (A) and 6 (B).
Values are means 6SEs, n= 3–4.
The relative density values under
respective bands without a com-
mon letter differ, P,0.05. ACTB,
b-actin; BD, base diet; GPX, gluta-
thione peroxidase; SELENO, seleno-
protein; SeNa, BD supplement with
0.2 mg Se/kg as sodium selenite; SeO,
BD supplement with 0.2 mg Se/kg as
2-hydroxy-4-methylselenobutanoic
acid; SeY, BD supplement with 0.2 mg
Se/kg as seleno-yeast.
Regulation by an organic selenium compound 795
at Huazhong Agricultural University on May 6, 2017jn.nutrition.orgDownloaded from
concentrations were produced by SeY than by SeNa in lambs,
as well as by SeO than by SeY in broilers (21, 22). These divergences
remain to be explained.
It is novel, to the best of our knowledge, to reveal the elevated
mRNA expression of 2 selenocysteine biosynthesis–related
genes, Pstk and SepSecS, by all 3 forms of selenium in the 3
tissues. This upregulation was largely consistent with their
positive effects on the selenocysteine concentrations and the
functional expression of selenoproteins at the mRNA, protein,
and activity levels. However, there were 2 subtle discrepancies
associated with this finding. Although SeO or SeY led to slightly
lower concentrations of selenocysteine in the liver and/or pectoral
muscle than SeNa, the 2 organic forms of selenium actually induced
similar or greater expression of Pstk and SepSecS. This may imply
a complex feedback mechanism in regulating selenocysteine
biosynthesis (51). It is intriguing that the other 3 selenocysteine
biosynthesis–related genes, selenophosphate synthetase 1,Sephs2,
and Secisbp2, and the selenocysteine-degrading enzyme gene Scly
failed to respond to the selenium supplementation of any form. It
warrants future research to find out if these proteins are regulated
by dietary selenium at the posttranscriptional sites.
In contrast to those upregulated selenoprotein genes, the
Txrnd1 mRNA abundances in the muscles were decreased by the
3 forms of selenium compared with the BD at week 6. This type
of downregulation was shown in previous studies (9, 13).
Furthermore, concentrations of glutathione in plasma, the liver,
and/or muscle were actually inversely related to the elevated
TXRND activity in the muscle by SeO at week 3 and GPX
activity in the liver by SeO and SeY at weeks 3 and 6. Because
selenium deficiency stimulated hepatic glutathione synthesis and
release to blood (52), the decreased glutathione in the SeO or
SeY group may be interpreted as an adaptation or coordination
to the elevated production of GPX and other antioxidant
selenoproteins.
Acknowledgments
We thank Rong-Wei Tang, Xuan Fang, Zeng-Quan Wei,
Zhi-Yuan Zhao, Guan-Jun Ma, and Shahid Ali Rajput for
technical assistance. L-HS, J-QH, and XGL designed the
research; LZ, L-HS, MB, S-WX, and D-SQ conducted the
experiments and analyzed the data; LZ, L-HS, J-QH, and XGL
wrote the manuscript; and L-HS and XGL had primary respon-
sibility for the final content. All authors read and approved the
final manuscript.
References
1. Rotruck JT, Pope AL, Ganther HE, Swanson AB, Hafeman DG,
Hoekstra WG. Selenium: biochemical role as a component of gluta-
thione peroxidase. Science 1973;179:588–90.
2. Tinggi U. Selenium: its role as antioxidant in human health. Environ
Health Prev Med 2008;13:102–8.
3. Clark LC, Combs GF Jr., Turnbull BW, Slate EH, Chalker DK, Chow J,
Davis LS, Glover RA, Graham GF, Gross EG, et al. Effects of selenium
supplementation for cancer prevention in patients with carcinoma of the
skin. A randomized controlled trial. JAMA 1996;276:1957–63.
4. Hoffmann PR, Berry MJ. The influence of selenium on immune re-
sponses. Mol Nutr Food Res 2008;52:1273–80.
5. Nuttall KL, Allen FS. Selenium detoxification of heavy metals: a possible
mechanism for the blood plasma. Inorg Chim Acta 1984;92:187–9.
6. Sun LH, Zhang NY, Zhu MK, Zhao L, Zhou JC, Qi DS. Prevention of
aflatoxin B1 hepatoxicity by dietary selenium is associated with inhi-
bition of cytochrome P450 isozymes and up-regulation of 6 seleno-
protein genes in chick liver. J Nutr 2016;146:655–61.
7. Gladyshev VN, Arn ´
er ES, Berry MJ, Brigelius-Floh´
e R, Bruford EA,
Burk RF, Carlson BA, Castellano S, Chavatte L, Conrad M, et al. Se-
lenoprotein gene nomenclature. J Biol Chem 2016;291:24036–40.
8. Kryukov GV, Castellano S, Novoselov SV, Lobanov AV, Zehtab O,
Guig ´
o R, Gladyshev VN, Gladyshev VN. Characterization of mam-
malian selenoproteomes. Science 2003;300:1439–43.
9. Huang JQ, Li DL, Zhao H, Sun LH, Xia XJ, Wang KN, Luo X, Lei XG.
The selenium deficiency disease exudative diathesis in chicks is associ-
ated with downregulation of seven common selenoprotein genes in liver
and muscle. J Nutr 2011;141:1605–10.
10. Huang JQ, Ren FZ, Jiang YY, Xiao C, Lei XG. Selenoproteins protect
against avian nutritional muscular dystrophy by metabolizing peroxides and
regulating redox/apoptotic signaling. Free Radic Biol Med 2015;83:129–38.
11. Sunde RA, Raines AM, Barnes KM, Evenson JK. Selenium status highly
regulates selenoprotein mRNA levels for only a subset of the seleno-
proteins in the selenoproteome. Biosci Rep 2009;29:329–38.
12. Barnes KM, Evenson JK, Raines AM, Sunde RA. Transcript analysis of
the selenoproteome indicates that dietary selenium requirements of
rats based on selenium-regulated selenoprotein mRNA levels are
uniformly less than those based on glutathione peroxidase activity.
J Nutr 2009;139:199–206.
13. Zhou JC, Zhao H, Li JG, Xia XJ, Wang KN, Zhang YJ, Liu Y, Zhao Y,
Lei XG. Selenoprotein gene expression in thyroid and pituitary of young
pigs is not affected by dietary selenium deficiency or excess. J Nutr
2009;139:1061–6.
14. Liu Y, Zhao H, Zhang Q, Tang J, Li K, Xia XJ, Wang KN, Li K, Lei XG.
Prolonged dietary selenium deficiency or excess does not globally affect
selenoprotein gene expression and/or protein production in various
tissues of pigs. J Nutr 2012;142:1410–6.
15. Li JL, Sunde RA. Selenoprotein transcript level and enzyme activity as
biomarkers for selenium status and selenium requirements of chickens
(Gallus gallus). PLoS One 2016;11:e0152392.
16. Taylor RM, Sunde RA. Selenoprotein transcript level and enzyme ac-
tivity as biomarkers for selenium status and selenium requirements in
the turkey (Meleagris gallopavo). PLoS One 2016;11:e0151665.
17. Yuan D, Zhan XA, Wang YX. Effect of selenium sources on the ex-
pression of cellular glutathione peroxidase and cytoplasmic thioredoxin
reductase in the liver and kidney of broiler breeders and their offspring.
Poult Sci 2012;91:936–42.
18. Payne RL, Southern LL. Comparison of inorganic and organic selenium
sources for broilers. Poult Sci 2005;84:898–902.
19. Pan C, Huang K, Zhao Y, Qin S, Chen F, Hu Q. Effect of selenium
source and level in henÕs diet on tissue selenium deposition and egg
selenium concentrations. J Agric Food Chem 2007;55:1027–32.
20. Phipps RH, Grandison AS, Jones AK, Juniper DT, Ramos-Morales E,
Bertin G. Selenium supplementation of lactating dairy cows: effects on
milk production and total selenium content and speciation in blood,
milk and cheese. Animal 2008;2:1610–8.
21. Vignola G, Lambertini L, Mazzone G, Giammarco M, Tassinari M,
Martelli G, Bertin G. Effects of selenium source and level of supple-
mentation on the performance and meat quality of lambs. Meat Sci
2009;81:678–85.
22. Briens M, Mercier Y, Rouffineau F, Vacchina V, Geraert PA. Compar-
ative study of a new organic selenium source v. seleno-yeast and mineral
selenium sources on muscle selenium enrichment and selenium digest-
ibility in broiler chickens. Br J Nutr 2013;110:617–24.
23. Kim YY, Mahan DC. Comparative effects of high dietary levels of or-
ganic and inorganic selenium on selenium toxicity of growing-finishing
pigs. J Anim Sci 2001;79:942–8.
24. Wang YB, Xu BH. Effect of different selenium source (sodium selenite
and selenium yeast) on broiler chickens. Anim Feed Sci Technol
2008;144:306–14.
25. Briens M, Mercier Y, Rouffineau F, Mercerand F, Geraert PA. 2-Hydroxy-
4-methylselenobutanoic acid induces additional tissue selenium enrich-
ment in broiler chickens compared with other selenium sources. Poult Sci
2014;93:85–93.
26. Couloigner F, Jlali M, Briens M, Rouffineau F, Geraert PA, Mercier Y.
Selenium deposition kinetics of different selenium sources in muscle and
feathers of broilers. Poult Sci 2015;94:2708–14.
27. Jlali M, Briens M, Rouffineau F, Mercerand F, Geraert PA, Mercier Y.
Effect of 2-hydroxy-4-methylselenobutanoic acid as a dietary selenium
supplement to improve the selenium concentration of table eggs. J Anim
Sci 2013;91:1745–52.
796 Zhao et al.
at Huazhong Agricultural University on May 6, 2017jn.nutrition.orgDownloaded from
28. Tufarelli V, Ceci E, Laudadio V. 2-Hydroxy-4-Methylselenobutanoic
acid as new organic selenium dietary supplement to produce selenium-
enriched eggs. Biol Trace Elem Res 2016;171:453–8.
29. Jlali M, Briens M, Rouffineau F, Geraert PA, Mercier Y. Evaluation of the
efficacy of 2-hydroxy-4-methylselenobutanoic acid on growth performance
and tissue selenium retention in growing pigs. J Anim Sci 2014;92:182–8.
30. Sun LH, Li JG, Zhao H, Shi J, Huang JQ, Wang KN, Xia XJ, Li L,
Lei XG. Porcine serum can be biofortified with selenium to inhibit pro-
liferation of three types of human cancer cells. J Nutr 2013;143:1115–22.
31. Palioura S, Sherrer RL, Steitz TA, So
¨ll D, Simonovic M. The human
SepSecS-tRNASec complex reveals the mechanism of selenocysteine
formation. Science 2009;325:321–5.
32. Allmang C, Krol A. Selenoprotein synthesis: UGA does not end the
story. Biochimie 2006;88:1561–71.
33. Mihara H, Kurihara T, Watanabe T, Yoshimura T, Esaki N. cDNA
cloning, purification, and characterization of mouse liver selenocysteine
lyase. Candidate for selenium delivery protein in selenoprotein synthe-
sis. J Biol Chem 2000;275:6195–200.
34. Bierla K, Dernovics M, Vacchina V, Szpunar J, Bertin G, Lobinski R.
Determination of selenocysteine and selenomethionine in edible animal
tissues by 2D size-exclusion reversed-phase HPLC-ICP MS following
carbamidomethylation and proteolytic extraction. Anal Bioanal Chem
2008;390:1789–98.
35. Jiang YY, Huang JQ, Lin GC, Guo HY, Ren FZ, Zhang H. Character-
ization and expression of chicken selenoprotein U. Biol Trace Elem Res
2015;166:216–24.
36. Imai H, Nakagawa Y. Biological significance of phospholipid hydro-
peroxide glutathione peroxidase (PHGPx, GPx4) in mammalian cells.
Free Radic Biol Med 2003;34:145–69.
37. Kryukov GV, Kumar RA, Koc A, Sun Z, Gladyshev VN. Selenoprotein
R is a zinc-containing stereo-specific methionine sulfoxide reductase.
Proc Natl Acad Sci USA 2002;99:4245–50.
38. Steinbrenner H, Alili L, Bilgic E, Sies H, Brenneisen P. Involvement of
selenoprotein P in protection of human astrocytes from oxidative
damage. Free Radic Biol Med 2006;40:1513–23.
39. Panee J, Stoytcheva ZR, Liu W, Berry MJ. Selenoprotein H is a redox-sensing
high mobility group family DNA-binding protein that up-regulates genes
involved in glutathione synthesis and phase II detoxification. J Biol Chem
2007;282:23759–65.
40. Juniper DT, Phipps RH, Ramos-Morales E, Bertin G. Effect of dietary
supplementation with selenium-enriched yeast or sodium selenite on
selenium tissue distribution and meat quality in beef cattle. J Anim Sci
2008;86:3100–9.
41. Schrauzer GN. The nutritional significance, metabolism and toxicology
of selenomethionine. Adv Food Nutr Res 2003;47:73–112.
42. Maehira F, Luyo GA, Miyagi I, Oshiro M, Yamane N, Kuba M,
Nakazato Y. Alterations of serum selenium concentrations in the acute
phase of pathological conditions. Clin Chim Acta 2002;316:137–46.
43. Burk RF, Hill KE. Regulation of selenium metabolism and transport.
Annu Rev Nutr 2015;35:109–34.
44. Hill KE, Wu S, Motley AK, Stevenson TD, Winfrey VP, Capecchi MR,
Atkins JF, Burk RF. Production of selenoprotein P (Sepp1) by hepato-
cytes is central to selenium homeostasis. J Biol Chem 2012;287:40414–
24.
45. Burk RF, Hill KE. Selenoprotein P-expression, functions, and roles
in mammals. Biochim Biophys Acta 2009;1790:1441–7.
46. Wolffram S, Ardu
¨ser F, Scharrer E. In vivo intestinal absorption of
selenate and selenite by rats. J Nutr 1985;115:454–9.
47. Wolffram S, Berger B, Grenacher B, Scharrer E. Transport of selenoamino
acids and their sulfur analogues across the intestinal brush border mem-
brane of pigs. J Nutr 1989;119:706–12.
48. Mizutani T, Hitaka T. The conversion of phosphoserine residues to
selenocysteine residues on an opal suppressor tRNA and casein. FEBS
Lett 1988;232:243–8.
49. Weekley CM, Harris HH. Which form is that? The importance of se-
lenium speciation and metabolism in the prevention and treatment of
disease. Chem Soc Rev 2013;42:8870–94.
50. Bierla K, Bianga J, Ouerdane L, Szpunar J, Yiannikouris A, Lobinski R.
A comparative study of the Se/S substitution in methionine and cysteine
in Se-enriched yeast using an inductively coupled plasma mass spec-
trometry (ICP MS)-assisted proteomics approach. J Proteomics
2013;87:26–39.
51. Pepper MP, Vatamaniuk MZ, Yan X, Roneker CA, Lei XG. Impacts of
dietary selenium deficiency on metabolic phenotypes of diet-restricted
GPX1-overexpressing mice. Antioxid Redox Signal 2011;14:383–90.
52. Hill KE, Burk RF. Effect of selenium deficiency and vitamin E deficiency
on glutathione metabolism in isolated rat hepatocytes. J Biol Chem
1982;257:10668–72.
Regulation by an organic selenium compound 797
at Huazhong Agricultural University on May 6, 2017jn.nutrition.orgDownloaded from
... Briefly, the thigh muscle was microscopically analyzed after fixation in 10% neutral buffered formalin, embedded in paraffin, sectioned to a thickness of 5 μm, and then stained with haematoxylin and eosin. The Se concentration in feed and muscle was determined as previously described [27]. Briefly, after the sample was digested with a nitric acid-perchloric acid mixture, a hydride generation atomic fluorescence spectrometer (AF-610B; Beijing Rayleigh Analytical Instrument Corporation) was used to measure the Se concentration. ...
... Primers for the assayed genes and the reference gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH) are presented in Supplemental Table 2. Relative RNA expression was calculated using the 2 -ΔΔCt method, and the relative abundance was normalized to the control (set as 1). Total proteins were extracted from thigh muscle using radioimmunoprecipitation assay buffer with 1.0% phenylmethylsulphonyl fluoride (Beyotime Biotechnology, China), and western blotting analysis of the pertinent samples was conducted as previously described [27]. The primary antibodies used for the analyses are presented in Supplemental Table 3. ...
... Specifically, dietary Se deficiency reduced the final body weight and thigh muscle size and induced loose organization of muscle fibers and a reduced number and cross-sectional area of fibers, which agrees with previous reports [32][33][34]. The Se deficiency-induced NMD in the present study was associated with decreased Se deposition and selenogenome expression in the thigh muscle, which agreed with previous studies in pigs [35] and broilers [27]. However, only GPX1 and SELENOW proteins correlated well with their mRNA abundance; the GPX3 and 4 and SELENO N and P proteins did not correlate well with their mRNA abundance in the thigh muscle. ...
... Increased tissue reserves of Se can enhance the resistance of livestock to stress and diseases, and therefore represent a key strategy to help fight commercially relevant forms of stress, such as heat stress and aging. Studies have shown that OH-SeMet increases the tissue deposition of Se in farm animals more than SS and SY Jlali et al., 2013;Zhao et al., 2017;Marco et al., 2021). Moreover, it has been shown that this higher storage capacity is translated into a higher gene expression and activity of several selenoproteins that play pivotal roles in antioxidant defense (Zhao et al., 2017;Sun et al., 2021). ...
... Studies have shown that OH-SeMet increases the tissue deposition of Se in farm animals more than SS and SY Jlali et al., 2013;Zhao et al., 2017;Marco et al., 2021). Moreover, it has been shown that this higher storage capacity is translated into a higher gene expression and activity of several selenoproteins that play pivotal roles in antioxidant defense (Zhao et al., 2017;Sun et al., 2021). ...
... Furthermore, the efficacy of Se sources is correlated with the upregulation of Selenoprotein mRNA, protein and activity. Organic Se sources, and OH-SeMet in particular, serve not only as Se suppliers, just like SS, that is, in supporting the basal expression of the selenogenome, but also possess a unique potential for promoting the functional expression of selected selenoproteins (Zhao et al., 2017). ...
Article
Oxidative stress significantly compromises the production efficiency of laying hens. It has been reported in literature that selenium (Se) in poultry diets has a positive effect on mitigating these effects. This study has been carried out to evaluate the effects of Se supplementation in feeds, from either an inorganic or a hydroxy-selenomethionine (OH-SeMet) source, on the performance and physiological traits of 50- to 70-week-old Dekalb Brown laying hens under heat stress, and on their egg quality after different storage durations. The treatments consisted in supplementing 0.3 ppm of Se as sodium selenite (SS; 45% - 0.7g/ton) or OH-SeMet (2% - 15g/ton) in twelve 16-bird replicates. Supplementation with OH-SeMet resulted in a better performance of the laying hens than with SS: -5% feed conversion ratio and +3.6% of egg mass. A reduction in egg quality was observed with prolonged egg storage, which was mitigated with the use of OH-SeMet in laying hen diets. The use of OH-SeMet increased the antioxidant capacity of the birds, which showed higher glutathione peroxidase levels in the blood, kidneys, liver, and intestinal mucosa, in addition to a higher Se content in the eggs and a greater bone resistance. Thus, supplementing feeds with 0.3 ppm of OH-SeMet to 50- to 70-week-old semi-heavy laying hens enhances their antioxidant capacity and leads to a higher egg quality and productivity than SS supplementation.
... The evidence for an effect of selenium supplementation on increased selenoenzymes activity exists, although any association with physiological and clinical effects is not well defined [13]. The effect of a selenium-rich diet on selenoprotein gene expression has been determined in various animals and in different tissues [14][15][16][17][18], and has been proven to depend on supplemented forms of Se [16]; investigation of chicken tissues has demonstrated that 2-hydroxy-4-methylselenobutanoic acid takes part in the regulation of selenoprotein gene expression (SELENOP, SELENOU and GPX4) when compared to other selenium forms, such as sodium selenate and selenised yeast. Several studies have confirmed that Se may predominantly affect the genes encoding proteins and plays a role in protein biosynthesis, e.g., increased Se consumption caused the growth of selenoproteins production and strengthened lymphocyte function, which is related to the upregulation of ribosomal protein and translation factor genes [19]. ...
... The evidence for an effect of selenium supplementation on increased selenoenzymes activity exists, although any association with physiological and clinical effects is not well defined [13]. The effect of a selenium-rich diet on selenoprotein gene expression has been determined in various animals and in different tissues [14][15][16][17][18], and has been proven to depend on supplemented forms of Se [16]; investigation of chicken tissues has demonstrated that 2-hydroxy-4-methylselenobutanoic acid takes part in the regulation of selenoprotein gene expression (SELENOP, SELENOU and GPX4) when compared to other selenium forms, such as sodium selenate and selenised yeast. Several studies have confirmed that Se may predominantly affect the genes encoding proteins and plays a role in protein biosynthesis, e.g., increased Se consumption caused the growth of selenoproteins production and strengthened lymphocyte function, which is related to the upregulation of ribosomal protein and translation factor genes [19]. ...
... Welfare guidelines and animal handling dealing were carefully adhered to throughout the whole period of our investigations conducted on animals. All nutritional studies on sheep and heart collections were performed in professional farm animal laboratory rooms located at the Kielanowski Institute of Animal Physiology and Nutrition (Polish Academy of Sciences) in Jabłonna near Warsaw (Poland) [14,16,37]. ...
Article
Full-text available
Selenium is an essential nutrient, building twenty five identified selenoproteins in humans known to perform several important biological functions. The small amount of selenium in the earth’s crust in certain regions along with the risk of deficiency in organisms have resulted in increasingly popular dietary supplementation in animals, implemented via, e.g., inorganic selenium compounds. Even though selenium is included in selenoproteins in the form of selenocysteine, the dietary effect of selenium may result in the expression of other proteins or genes. Very little is known about the expression effects modulated by selenium. The present study aimed to examine the significance of protein expression in lamb tissues obtained after dietary supplementation with selenium (sodium selenate) and two other feed additives, fish oil and carnosic acid. Label-free mass spectrometry-based proteomic analysis was successfully applied to examine the animal tissues. Protein-protein interaction network analysis of forty differently-expressed proteins following inorganic selenium supplementation indicated two significant clusters which are involved in cell adhesion, heart development, actin filament-based movement, plasma membrane repair, and establishment of organelle localization.
... Recently, and to achieve cost-effective production, feed additives in different forms (various sources, forms, formulations, etc.) is aimed for improving poultry growth and conversion ratios, and obtaining better quality and value-added products (Gangadoo et al., 2016). Also, dietary supplementation with these mineral additives has a vital role in rapid growth and refining the feed conversion ratio (FCR), so lowering the amount of needed feed to attain market weight (Zhao et al., 2017). These elements are vital to the health of poultry since they play important roles in the function of coenzymes (Peters et al., 2016). ...
... For this reason, relatively high non-toxic OH-SeMet concentrations have been used. In addition, pure organic forms of Se such as selenomethionine and OH-SeMet have a greater capacity to modulate selenoprotein gene expression than selenized yeasts or inorganic Se sources such as sodium selenite in different tissues [9,24,[31][32][33]. In this context, it has previously been reported that OH-SeMet supplementation increased GPX1 and SELENOP gene expression in intestinal Caco-2 cells [9], consistent with the results obtained here in macrophages. ...
Article
The role of 2-hydroxy-(4-methylseleno)butanoic acid (OH-SeMet), a form of organic selenium (Se), in selenoprotein synthesis and inflammatory response of THP1-derived macrophages stimulated with lipopolysaccharide (LPS) has been investigated. Glutathione peroxidase (GPX) activity, GPX1 gene expression, selenoprotein P (SELENOP) protein and gene expression, and reactive oxygen species (ROS) production were studied in Se-deprived conditions (6 and 24 h). Then, macrophages were supplemented with OH-SeMet for 72 h and GPX1 and SELENOP gene expression were determined. The protective effect of OH-SeMet against oxidative stress was studied in H2O2-stimulated macrophages, as well as the effect on GPX1 gene expression, oxidative stress, cytokine production (TNFα, IL-1β and IL-10), and phagocytic and killing capacities after LPS stimulation. Se deprivation induced a reduction in GPX activity, GPX1 gene expression, and SELENOP protein and gene expression at 24 h. OH-SeMet upregulated GPX1 and SELENOP gene expression and decreased ROS production after H2O2 treatment. In LPS-stimulated macrophages, OH-SeMet upregulated GPX1 gene expression, enhanced phagocytic and killing capacities, and reduced ROS and cytokine production. Therefore, OH-SeMet supplementation supports selenoprotein expression and controls oxidative burst and cytokine production while enhancing phagocytic and killing capacities, modulating the inflammatory response, and avoiding the potentially toxic insult produced by highly activated macrophages.
... Abbreviations: SeNa, sodium selenite; SeO, 2-hydroxy-4-methyl selenobutanoic acid; SeY, seleno-yeast. Figure adapted from References 90,159,and 225. have 10 Secs in the peptide and two SECIS elements in the 3 UTR. The Sec located in the middle of the sequence may have peroxidase activity. ...
Article
Full-text available
This review traces the discoveries that led to the recognition of selenium (Se) as an essential nutrient and discusses Se-responsive diseases in animals and humans in the context of current understanding of the molecular mechanisms of their pathogeneses. The article includes a comprehensive analysis of dietary sources, nutritional utilization, metabolic functions, and dietary requirements of Se across various species. We also compare the function and regulation of selenogenomes and selenoproteomes among rodents, food animals, and humans. The review addresses the metabolic impacts of high dietary Se intakes in different species and recent revelations of Se metabo-lites, means of increasing Se status, and the recycling of Se in food systems and ecosystems. Finally, research needs are identified for supporting basic science and practical applications of dietary Se in food, nutrition, and health across species. 337 Annu. Rev. Nutr. 2022.42:337-375. Downloaded from www.annualreviews.org Access provided by Cornell University on 09/04/22. For personal use only.
Article
The effect of 25-hydroxyvitamin D (25OHD) on the immune response of laying hens is not well elucidated. This study investigated the effects of 25OHD on egg production, egg quality, immune response, and intestinal health of laying hens challenged with Escherichia coli lipopolysaccharide (LPS). One hundred and sixty laying hens at 45 wk of age were randomly divided into 4 dietary treatments with 10 replicates of 4 birds. Hens were fed the corn-soybean based diets contained either 0 or 80 µg/kg 25OHD for 8 wks. At wk of 53 wk, birds of each dietary treatment were injected into the abdomen with 1.5 mg/kg body weight of either LPS or saline a day at 24-h intervals for continuous 7 d. LPS injection significantly decreased (PLPS<0.05) egg laying rate, feed intake and feed efficiency; while the supplementation of 25OHD increased (PInteraction<0.05) egg laying rate, feed efficiency and decreased (PInteraction<0.05) the broken egg rate in layers under LPS injection. LPS challenge decreased (PLPS<0.05) eggshell strength, eggshell thickness, albumen height and Haugh unit, while dietary 25OHD supplementation increased eggshell strength and eggshell thickness (P25OHD<0.05). The serum proinflammatory factors [tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6)], endotoxin and diamine oxidase (DAO) levels were higher in layers under LPS challenge (PLPS<0.05); whereas the dietary addition of 25OHD were shown to decrease (P25OHD<0.05) serum IL-1β and IL-6 concentration irrespective of LPS challenge and led to a higher serum 25OHD level and a reduction in endotoxin concentration in layers under LPS challenge (PInteraction<0.05). The layers under LPS challenge had higher crypt depth and lower villus height/crypt depth (V/C) ratio in duodenum and jejunum (PLPS<0.05), while feeding 25OHD were shown to have decreasing effect on crypt depth and increasing effect V/C ratio in layers under LPS challenge (PInteraction<0.05). Layers under LPS challenge had lower mRNA expression of intestinal barrier associated proteins (claudin-1 and mucin-1) (PLPS<0.05), while the addition of 25OHD up-regulated claudin-1 and mucin-1 expression (Pinteraction<0.05). Lower antioxidant enzymes activities, including superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (T-AOC), glutathione peroxidase (GPx) and higher malondialdehyde (MDA) content in jejunum were found in layers challenged with LPS (P25OHD < 0.05). The effect of 25OHD reversed the effect of LPS on SOD, T-AOC and MDA content (PInteraction< 0.05). These results suggest that supplementing 80 µg/kg 25OHD in diets may elevate laying performance and egg quality through the improvement of intestinal barrier function, antioxidant capacity, and decreased the proinflammatory cytokines levels in laying hens with Escherichia coli LPS challenge.
Article
Thirty-two male Hu lambs (32.31 ± 3.31 kg; 4-months-old) were randomly assigned to four treatments: (1) control (CON), (2) selenium-enriched yeast (SeY, 0.8 mg/kg), (3) selenized glucose (SeGlu, 0.8 mg/kg), and (4) sodium selenite (SS, 0.8 mg/kg) to evaluate their effects on Hu lamb production and slaughter performance, antioxidant capacity, hematological parameters, meat quality and shelf-life. The production and slaughter performances were not different (P > 0.05) among treatments. SeGlu and SeY increased (P < 0.05) the total antioxidant capacity in serum and muscle selenium content while decreasing (P < 0.05) the malondialdehyde (MDA) contents both in serum and muscle. SeGlu extended muscle shelf-life by 7.7 h compared with CON and decreased (P < 0.05) yellowness (b*) and lightness (L*) in meat stored for 24 h. In summary, the effects of SeGlu were similar to those of SeY and better than those of SS in improving serum and muscle antioxidant status, prolonging muscle shelf-life, and increasing selenium deposition in muscle.
Article
Background Superanutriton of selenium (Se) in an effort to produce Se-enriched meat may inadvertently cause lipid accumulation. Se-enriched Cardamine violifolia (SeCv) contains over 80% of Se in organic forms. Objective This study was to determine whether feeding chickens a high dose of SeCv could produce Se-biofortified muscle without altering their lipid metabolism. Methods Day-old male broilers were allocated to 4 groups (6 cages/group and 6 chicks/cage), and were fed either a corn-soy base diet (BD, 0.13–0.15 mg Se/kg), the BD plus 0.5 mg Se/kg as sodium selenite (SeNa) or as SeCv, or the BD plus a low-Se Cardamine violifolia (Cv, 0.21 mg Se/kg). At week 6, concentrations of Se and lipid and expression of selenoprotein and lipid metabolism-related genes were determined in the pectoral muscle and liver. Results The 4 diets showed no effects on growth performance of broilers. Compared with the other 3 diets, SeCv elevated (P < 0.05) Se concentrations in the pectoral muscle and liver by 14.4 to 127%, and decreased (P < 0.05) total cholesterol concentrations by 12.5 to 46.7%, and(or) triglyceride concentrations by 28.8 to 31.1% in the pectoral muscle and(or) liver, respectively. Meanwhile, SeCv enhanced (P < 0.05) muscular α-linolenic acid (80.0%) and hepatic arachidonic acid (58.3%) concentrations compared with SeNa and BD, respectively. SeCv downregulated (P < 0.05) the cholesterol and triglyceride synthesis-related proteins (SREBF2 and DGAT2) and upregulated (P < 0.05) hydrolysis and β-oxidation of fatty acid-related proteins (LPL, FABP1, and CPT1A), SELENOP1 and TXRND activity in the pectoral muscle and(or) liver compared with SeNa. Conclusions Compared with SeNa, SeCv effectively raised Se and reduced lipids in the liver and muscle of broilers. The effect was mediated through the regulation of the cholesterol and triglyceride biosynthesis and utilization-related genes.
Article
This review traces the discoveries that led to the recognition of selenium (Se) as an essential nutrient and discusses Se-responsive diseases in animals and humans in the context of current understanding of the molecular mechanisms of their pathogeneses. The article includes a comprehensive analysis of dietary sources, nutritional utilization, metabolic functions, and dietary requirements of Se across various species. We also compare the function and regulation of selenogenomes and selenoproteomes among rodents, food animals, and humans. The review addresses the metabolic impacts of high dietary Se intakes in different species and recent revelations of Se-metabolites, means of increasing Se status, and the recycling of Se in food systems and ecosystems. Finally, research needs are identified for supporting basic science and practical applications of dietary Se in food, nutrition, and health across species. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Article
Full-text available
Making Selenocysteine In humans, selenocysteine is the only amino acid that lacks its own transfer RNA (tRNA) synthetase and is synthesized on its cognate tRNA. The process involves mischarging of tRNA sec with serine, phosphorylation of the serine, and then conversion of the phosphoserine into selenocysteine by the enzyme SepSecS using selenophosphate as the selenium donor. Palioura et al. (p. 321 ) now provide insight into the mechanism of selenocysteine formation, based on the crystal structure of human tRNA sec complexed with SepSecS, phosphoserine, and thiophosphate, together with in vivo and in vitro activity assays. Binding of tRNA sec to SepSecS is required to properly orient phosphoserine attached to tRNA sec for pyroxidal phosphate–based catalysis.
Article
Full-text available
The human genome contains 25 genes coding for selenocysteine-containing proteins (selenoproteins). These proteins are involved in a variety of functions, most notably redox homeostasis. Selenoprotein enzymes with known functions are designated according to these functions: TXNRD1, TXNRD2, and TXNRD3 (thioredoxin reductases), GPX1, GPX2, GPX3, GPX4 and GPX6 (glutathione peroxidases), DIO1, DIO2, and DIO3 (iodothyronine deiodinases), MSRB1 (methionine-R-sulfoxide reductase 1) and SEPHS2 (selenophosphate synthetase 2). Selenoproteins without known functions have traditionally been denoted by SEL or SEP symbols. However, these symbols are sometimes ambiguous and conflict with the approved nomenclature for several other genes. Therefore, there is a need to implement a rational and coherent nomenclature system for selenoprotein-encoding genes. Our solution is to use the root symbol SELENO followed by a letter. This nomenclature applies to SELENOF (selenoprotein F, the 15 kDa selenoprotein, SEP15), SELENOH (selenoprotein H, SELH, C11orf31), SELENOI (selenoprotein I, SELI, EPT1), SELENOK (selenoprotein K, SELK), SELENOM (selenoprotein M, SELM), SELENON (selenoprotein N, SEPN1, SELN), SELENOO (selenoprotein O, SELO), SELENOP (selenoprotein P, SeP, SEPP1, SELP), SELENOS (selenoprotein S, SELS, SEPS1, VIMP), SELENOT (selenoprotein T, SELT), SELENOV (selenoprotein V, SELV) and SELENOW (selenoprotein W, SELW, SEPW1). This system, approved by the HUGO Gene Nomenclature Committee, also resolves conflicting, missing and ambiguous designations for selenoprotein genes and is applicable to selenoproteins across vertebrates.
Article
Full-text available
The NRC selenium (Se) requirement for broiler chicks is 0.15 μg Se/g diet, based primarily on weight gain and feed intake studies reported in 1986. To determine Se requirements in today's rapidly growing broiler chick, day-old male chicks were fed Se-deficient basal diets supplemented with graded levels of Se (0, 0.025, 0.05, 0.075, 0.1, 0.2, 0.3, 0.5, 0.75, and 1.0 μg Se/g) as Na2SeO3 (5/treatment). Diets contained 15X the vitamin E requirement, and there were no gross signs of Se-deficiency. At 29 d, Se-deficient chicks weighed 62% of Se-supplemented chicks; 0.025 μg Se/g reversed this effect, indicating a minimum Se requirement of 0.025 μg Se/g diet for growth for male broiler chicks. Enzyme activities in Se-deficient chicks for plasma GPX3, liver and gizzard GPX1, and liver and gizzard GPX4 decreased dramatically to 3, 2, 5, 10 and 5%, respectively, of Se-adequate levels, with minimum Se requirements of 0.10-0.13 μg Se/g, and with defined plateaus above these levels. Pancreas GPX1 and GPX4 activities, however, lacked defined plateaus, with breakpoints at 0.3 μg Se/g. qPCR measurement of all 24 chicken selenoprotein transcripts, plus SEPHS1, found that SEPP1 in liver, GPX3 in gizzard, and SEPP1, GPX3 and SELK in pancreas were expressed at levels comparable to housekeeping transcripts. Only 33%, 25% and 50% of selenoprotein transcripts were down-regulated significantly by Se deficiency in liver, gizzard and pancreas, respectively. No transcripts could be used as biomarkers for supernutritional Se status. For export selenoproteins SEPP1 and GPX3, tissue distribution, high expression and Se-regulation clearly indicate unique Se metabolism, which may underlie tissues targeted by Se deficiency. Based on enzyme activities in liver, gizzard, and plasma, the minimum Se requirement in today's broiler chick is 0.15 μg Se/g diet; pancreas data indicate that the Se requirement should be raised to 0.2 μg Se/g diet to provide a margin of safety.
Article
Full-text available
The current National Research Council (NRC) selenium (Se) requirement for the turkey is 0.2 μg Se/g diet. The sequencing of the turkey selenoproteome offers additional molecular biomarkers for assessment of Se status. To determine dietary Se requirements using selenoprotein transcript levels and enzyme activities, day-old male turkey poults were fed a Se-deficient diet supplemented with graded levels of Se (0, 0.025, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1.0 μg Se/g diet) as selenite, and 12.5X the vitamin E requirement. Poults fed less than 0.05 μg Se/g diet had a significantly reduced rate of growth, indicating the Se requirement for growth in young male poults is 0.05 μg Se/g diet. Se deficiency decreased plasma GPX3 (glutathione peroxidase), liver GPX1, and liver GPX4 activities to 2, 3, and 7%, respectively, of Se-adequate levels. Increasing Se supplementation resulted in well-defined plateaus for all blood, liver and gizzard enzyme activities and mRNA levels, showing that these selenoprotein biomarkers could not be used as biomarkers for supernutritional-Se status. Using selenoenzyme activity, minimum Se requirements based on red blood cell GPX1, plasma GPX3, and pancreas and liver GPX1 activities were 0.29-0.33 μg Se/g diet. qPCR analyses using all 10 dietary Se treatments for all 24 selenoprotein transcripts (plus SEPHS1) in liver, gizzard, and pancreas found that only 4, 4, and 3 transcripts, respectively, were significantly down-regulated by Se deficiency and could be used as Se biomarkers. Only GPX3 and SELH mRNA were down regulated in all 3 tissues. For these transcripts, minimum Se requirements were 0.07-0.09 μg Se/g for liver, 0.06-0.15 μg Se/g for gizzard, and 0.13-0.18 μg Se/g for pancreas, all less than enzyme-based requirements. Panels based on multiple Se-regulated transcripts were effective in identifying Se deficiency. These results show that the NRC turkey dietary Se requirement should be raised to 0.3 μg Se/g diet.
Article
Full-text available
Background: The involvement of cytochrome P450 (CYP450) isozymes and the selenogenome in selenium-mediated protection against aflatoxin B1 (AFB1)-induced adverse effects in broilers remains unclear. Objective: This study was designed first to determine whether selenium could reduce AFB1-induced hepatotoxic effects and then to determine whether these effects were due to changes in the CYP450 isozymes and selenogenome expression in the liver of chicks. Methods: Male avian broilers (aged 120 d) were allocated to 4 groups with 5 replicates of 6 birds to be included in a 2-by-2 factorial trial in which the main factors included supplementation of AFB1 (<5 compared with 100 μg/kg) and selenium (0.2 compared with 0.5 mg/kg) in a corn/soybean-based diet for 4 wk. Serum biochemistry, hepatic histology, and mRNA and/or activities of hepatic antioxidant enzymes, CYP450 isozymes, and 26 selenoproteins were analyzed at week 2 and/or 4. Results: Administration of AFB1 induced liver injury, decreasing (P < 0.05) total protein and albumin concentrations by 33.3-43.8% and increasing (P < 0.05) alanine aminotransferase and aspartate aminotransferase activities by 26.0-33.8% in serum, and induced hepatic necrosis and bile duct hyperplasia at week 2. AFB1 also decreased (P < 0.05) hepatic activities of glutathione peroxidase (GPX), thioredoxin reductase (TXNRD), and catalase, and the glutathione concentration by 13.1-59.9% and increased (P < 0.05) malondialdehyde, 8-hydroxydeoxyguanosine and exo-AFB1-8,9-epoxide (AFBO) DNA concentrations by 17.9-1200%. In addition, the mRNA and activity of enzymes responsible for the bioactivation of AFB1 into AFBO, which included CYP450 A1, 1A2, 2A6, and 3A4, were significantly induced (P < 0.05) by 29.2-271% in liver microsomes after 2-wk exposure to AFB1. These alterations induced by AFB1 were prevented by selenium supplementation. Dietary selenium supplementation increased (P < 0.05) mRNA and/or activities of 6 selenoprotein genes (Gpx3, Txnrd1, Txnrd2, Txnrd3, iodothyronine deiodinase 2, and selenoprotein N) in the liver of AFB1-treated groups at week 2. Conclusions: Dietary selenium protected chicks from AFB1-induced liver injury, potentially through the synergistic actions of inhibition of the pivotal CYP450 isozyme-mediated activation of AFB1 to toxic AFBO, and increased antioxidant capacities by upregulation of selenoprotein genes coding for antioxidant proteins.
Article
Full-text available
Food-based strategies need to be developed to improve the selenium (Se) status of individuals. The aim of this study was to evaluate the effects of a new organic Se [2-hydroxy-4-methylselenobutanoic acid (HMSeBA)] on selected performance criteria and Se deposition in egg of laying hens. Isa Brown laying hens, 18 weeks of age were randomly allocated to two dietary treatments and fed for 10 weeks. The hens were fed two corn-soybean meal-based diets comprising a control basal diet without Se supplementation and a test diet supplemented with Se at 0.2 mg/kg from HMSeBA. No difference was observed among dietary treatments on feed intake, egg weight and laying rate, whereas egg yolk fatty acid profile and vitamin E content were positively influenced by HMSeBA supplementation. Hens fed Se-supplemented diet exhibited greater (P < 0.001) egg yolk total Se contents, which averaged 21.2 mg/100 g dry matter (DM) compared to control diet (11.7 mg/100 g DM). Our results suggested that HMSeBA as Se supplement influences positively egg yolk quality without affecting hens' productive traits. Moreover, HMSeBA offers an efficient alternative to fortify eggs with Se, which can consequently lead to greater supply of Se for humans.
Article
Full-text available
The objective of this study was to determine selenium (Se) deposition kinetics in muscles and feathers of broilers in order to develop a rapid method to compare bioavailability of selenium sources. Different Se sources such as 2-hydroxy-4-methylselenobutanoic acid (HMSeBA, SO), sodium selenite (SS) and seleno-yeast (SY) were compared for their kinetics on Se deposition in muscles and feathers in broiler chicks from 0 to 21 d of age. A total of 576 day-old broilers were divided into four treatments with 8 replicates of 18 birds per pen. The diets used in the experiment were a negative control (NC) not supplemented with Se and 3 diets supplemented with 0.2 mg Se/kg as SS, SY or SO. Total Se content in breast muscle and feathers were assessed on days 0, 7, 14 and 21. At 7 d of age, SO increased muscle Se content compared to D0 (P < 0.05), whereas with the other treatments, muscle Se concentration decreased (P < 0.05). After 21 days, organic Se sources maintained (SY) or increased (SO) (P < 0.05) breast muscle Se concentration compared to hatch value whereas inorganic source (SS) or non-supplemented group (NC) showed a significant decrease in tissue Se concentration (P < 0.05). At D21, Se contents of muscle and feathers were highly correlated (R2 = 0.927; P < 0.0001). To conclude, these results indicate that efficiency of different Se sources can be discriminated through a 7 d using muscle Se content in broiler chickens. Muscle and feathers Se contents were highly correlated after 21 days. Also feather sampling at 21 days of age represents a reliable and non-invasive procedure for Se bioefficacy comparison.
Article
Transport of selenomethionine (Se-Met) and its sulfur analogue, methionine (Met), across the pig jejunal brush border membrane (BBM) was investigated using isolated BBM vesicles. Experiments were also performed to gain insight into the transport mechanism(s) for selenocystine. Se-Met as well as Met were transported by a single, Na⁺-dependent, carrier-mediated process common for both amino acids. Evaluation of the kinetic parameters revealed no differences between Se-Met and Met in the maximal transport velocity (Vmax) or in the Michaelis constant (Km). Furthermore, transport of Se-Met and Met showed similar characteristics with respect to electrogenicity and substrate specificity. In addition, evidence was obtained for a competitive inhibition of cystine transport across the BBM by selenocystine and basic amino acids.
Article
Selenium is regulated in the body to maintain vital selenoproteins and to avoid toxicity. When selenium is limiting, cells utilize it to synthesize the selenoproteins most important to them, creating a selenoprotein hierarchy in the cell. The liver is the central organ for selenium regulation and produces excretory selenium forms to regulate whole-body selenium. It responds to selenium deficiency by curtailing excretion and secreting selenoprotein P (Sepp1) into the plasma at the expense of its intracellular selenoproteins. Plasma Sepp1 is distributed to tissues in relation to their expression of the Sepp1 receptor apolipoprotein E receptor-2, creating a tissue selenium hierarchy. N-terminal Sepp1 forms are taken up in the renal proximal tubule by another receptor, megalin. Thus, the regulated whole-body pool of selenium is shifted to needy cells and then to vital selenoproteins in them to supply selenium where it is needed, creating a whole-body selenoprotein hierarchy. Expected final online publication date for the Annual Review of Nutrition Volume 35 is July 17, 2015. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
Article
Selenoprotein U (SelU) may regulate a myriad of biological processes through its redox function. In chicks, neither the nucleotide sequence nor the amino acid sequence is known. The main objectives of this study were to clone and characterize the chicken Selu gene and investigate Selu messenger RNA (mRNA) and protein expression in chicken tissues. The coding sequence (CDS) of Selu contained 387 bases with a typical mammalian selenocysteine insertion sequence (SECIS) located in the 3'-untranslated region. The deduced amino acid sequence of chicken SelU contains 224 amino acids with UAA as the stop codon. Like all SelU genes identified in different species, chicken SelU contains one well-conserved selenocysteine (Sec) at the 85th position encoded by the UGA codon. The SECIS element was with the conserved denosine (--AAA--) rather than the motif cytidine (--CC--) motif. Moreover, the expression pattern of Selu mRNA in muscle, liver, kidney, heart, spleen, lung, testis, and brain was analyzed with real-time quantitative PCR in young male chickens fed a Se-deficient corn-soybean meal basal diet supplemented with 0.0 and 0.3 mg Se/kg in the form of sodium selenite. We found that the abundance of Selu mRNA in muscle, liver, kidney, heart, spleen, and lung was downregulated (P < 0.05) by Se deficiency. However, it was not affected by dietary Se concentrations in testis and brain. Furthermore, protein abundance of SelU in these seven tissues was consistent with the mRNA abundance. Hence, we suggest that Selu might play an important role in the biochemical function of Se in birds.