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ABSTRACT: NADH dehydrogenase (complex I) catalyzes the transfer of electrons from NADH to ubiquinone with pumping protons across the mitochondrial inner membrane and produces reactive oxygen species as a major source in mitochondria. A missense mutation in the mitochondrially encoded NADH dehydrogenase 2 (MT-ND2) gene, which could produce a change in the protein's secondary structure, has been found in the Tibet chicken breed. In this study, breeding eggs of the Tibet chicken breed with the two genotypes were divided into two groups. One group was incubated in normoxia (20.9% oxygen concentration) and the other in simulated hypoxia (14.5% oxygen concentration). On the 16th day of incubation, complex I activity and mitochondrial reactive oxygen species production in the Tibet chicken embryonic liver with different genotypes in each group were measured. Results showed that: (1) hypoxia reduced complex I activity standardized and mitochondrial reactive oxygen species production significantly compared with normoxia and (2) the missense mutation in the MT-ND2 gene was significantly associated with the production of reactive oxygen species in mitochondria while not associated with the standardized or unstandardized activity of complex I.
Animal Genetics 01/2013; · 2.40 Impact Factor
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ABSTRACT: Chicken is considered to be an excellent model for genetic studies of phenotypic and genomic evolution, with large effective population size, specialized commercial lines, and strong human-driven selection. High-density chicken SNP chips can help to achieve a better understanding of the selection mechanisms in artificially selected populations. We performed the genome-wide tests for the selection signature in 385 White Leghorn hens and mapped positively selected regions to the genome annotations. Ten QTL related to egg production, egg quality, growth, and disease resistance traits were selected for extended haplotype homozygosity tests to give a brief overview of recent selection signatures in chicken QTL. We also reported 185 candidate genes/CDSs showing top P-values and slower decay of haplotype homozygosities. Some of these genes seemed to have significant effects on important economical traits, and most of them have not been reported in chickens. The current study provides a genome-wide map of linkage disequilibrium extents and distributions and selection footprints in the chicken genome. A panel of genes, including PRL, NCKX1, NRF1, LHX2, and SFRP1 associated with egg production, metabolism traits, and response to illumination were identified. In addition, there were more genes identified that have not yet been reported in chickens, and our results provide new clues for further study.
Poultry Science 08/2012; 91(8):1804-12. · 1.73 Impact Factor
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ABSTRACT: Some members of the low-density lipoprotein receptor (LDLR) family play important roles in the regulation of lipoprotein metabolism and egg quality traits. Low-density lipoprotein receptor-related protein 2 (LRP2) gene belongs to the LDLR super family, and widely expresses in many tissues. This work identified and genotyped 1 single-nucleotide polymorphism (SNP), T14347C, at 3'-UTR of the LRP2 using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS), and analyzed the effects of the SNP (T14347C) on egg-quality traits in 544 dwarf hens from 44 sire families. Frequencies of this SNP in the studied population did not agree with the Hardy-Weinberg equilibrium (P < 0.0001). Egg weight, albumen weight, albumen height, and albumen ratio of the TT genotype were significantly higher than those of the CC genotype (P < 0.05), whereas eggshell ratio of the TT genotype was significantly lower than that of the CC genotype (P < 0.05). The relative expression level of the LRP2 gene in the magnum was determined by real-time quantitative PCR. The gene expression of genotype CC individuals was significantly higher than that of TT and CT birds (P < 0.05). By combining both genetic effects and expression analyses results, we propose that the LRP2 gene is a good candidate gene, exhibiting a key role in albumen formation processes.
Poultry Science 12/2011; 90(12):2718-22. · 1.73 Impact Factor
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ABSTRACT: Biliverdin is responsible for the coloration of blue eggs and is secreted onto the eggshell by the shell gland. Previous studies confirmed that a significant difference exists in biliverdin content between blue eggs and brown eggs, although the reasons are still unknown. Because the pigment is derived from oxidative degradation of heme catalyzed by heme oxygenase (HO), this study compared heme oxygenase (decycling) 1 (HMOX1), the gene encoding HO expression and HO activity, in the shell glands of the Dongxiang blue-shelled chicken (n = 12) and the Dongxiang brown-shelled chicken (n = 12). Results showed that HMOX1 was highly expressed at the mRNA (1.58-fold; P < 0.05) and protein levels in blue-shelled chickens compared with brown-shelled chickens. At the functional level, blue-shelled chickens also showed 1.40-fold (P < 0.05) higher HO activity than brown-shelled chickens. To explore the reasons for the differential expression of HMOX1, an association study of 6 SNP capturing the majority of HMOX1 variants with the blue egg coloration was performed. Results showed no significant association between SNP and the blue egg coloration in HMOX1 (P > 0.05). Taken together, these results show that blue egg formation is associated with high expression of HMOX1 in the shell gland of Dongxiang blue-shelled chickens, and suggest that differential expression of HMOX1 in the 2 groups of chickens is most likely to arise from an alteration in the trans-acting factor.
Poultry Science 04/2011; 90(4):836-41. · 1.73 Impact Factor
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ABSTRACT: The Tibet chicken originates from the Qinghai-Tibet Plateau and has adapted well to hypoxia, whereas the Silky chicken is a lowland chicken breed from an area with an altitude of 750 m. The objective of the present study was to investigate whether differences exist in glutathione and related metabolism between the Tibet chicken and the Silky chicken when birds were housed in a normoxic or hypoxic chamber for 20 h. Activities of glutathione peroxidase, glutathione S-transferase, and glutathione reductase and levels of glutathione were determined spectrophotometrically. Under normoxia conditions and moderate hypoxia (14% oxygen concentration) conditions, no differences were found in levels of total glutathione, reduced glutathione (GSH), disulfide-oxidized glutathione (GSSG), the GSH:GSSG ratio, and activities of glutathione peroxidase and glutathione S-transferase between the Tibet chicken and the Silky chicken. Under extreme hypoxia conditions (14% oxygen concentration for 14 h and then 10.5% oxygen concentration for 6 h), values for the GSH content, the GSH:GSSG ratio, and the activity of glutathione reductase in the liver of the Tibet chicken were higher than those of the Silky chicken. The results indicate that the Tibet chicken responded better than the Silky chicken to oxidative stress in extreme hypoxia through glutathione enzymes of detoxification. This work provides reference for future studies on the association of glutathione metabolism with the adaptation to hypoxia.
Poultry Science 03/2011; 90(3):648-52. · 1.73 Impact Factor
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Poultry Science 10/2010; 89(10):2304. · 1.73 Impact Factor
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ABSTRACT: Monocytes-macrophages play an indispensable role in the immune system. The current study investigated the effect of selection for monocytes-macrophages phagocytosis on disease resistance in generation 1 (G1) of dwarf chickens. Five hundred dwarf chickens of generation 0 (G0) were divided into high and low phagocytic index (PI) groups (HPIG and LPIG, respectively) based on their PI of monocytes-macrophages at 290 d of age. Then, 2 x 2 mating combinations were conducted. Sixty G0 chickens from another dwarf chicken group were used to measure the levels of monocytes-macrophages phagocytosis at different developmental stages. Among a total of 2,500 randomly selected G1 chickens, 2,100 individuals were used for a surviving and growing test under adverse feeding circumstances, and the other 400 individuals were tested for Salmonella Pullorum challenge. The results showed that progenies of HPIG hens (female symbol) were more resistant to Salmonella Pullorum. After challenge, the death rate of progeny from HPIG female symbol (28.9%) was only 58% that of progeny from LPIG female symbol (49.4%, P < 0.001). In addition, the natural infection rate of Salmonella Pullorum before 207 d for offspring from HPIG female symbol (35.0%) was significantly lower than that for offspring from LPIG female symbol (48.3%, P < 0.001). The natural mortality before 56 d in progeny of HPIG female symbol (22.6%) was significantly lower than that in progeny of LPIG female symbol (29.1%) with a P-value of 0.001. The G1 chickens of HPIG G0 female symbol weighed more than those born to LPIG G0 female symbol at 28 and 42 d of age, whereas the difference was not statistically significant at 56 d of age. The heritability of monocytes-macrophages phagocytosis was 0.40, which was moderate. The PI values were at a low level before 126 d and increased dramatically until they declined significantly after 294 d. It could be concluded that phagocytosis of monocytes-macrophages is a marker for breeding excellent progeny with strong disease resistance.
Poultry Science 09/2010; 89(9):2022-9. · 1.73 Impact Factor
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ABSTRACT: 1. In order to identify the molecular interval containing the blue shell gene (O locus), linkage analysis was conducted with three microsatellite markers, (TTA)(n), (TG)(n) and (tg)(n), and a SNP in intron 1 of SLCO1C1 (solute carrier organic anion transporter family, member 1C1; A locus) to map the O locus in an F2 resource population of Dongxiang chickens. 2. Linkage analysis based on 98 F2 hens resulted in estimation of the best map order of the O locus with other linked markers as: (TTA)(n)-(TG)(n)-A-O-(tg)(n). 3. Based on these results, we inferred that the O locus was located between the A and (tg)(n) loci, that is, Chr1:67,296,991-69,140,571, which is the first genomic sequence interval to be established for the blue eggshell gene.
British Poultry Science 08/2010; 51(4):507-9. · 1.00 Impact Factor
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ABSTRACT: The objective of the present study was to evaluate the role of myofiber characteristics and the thickness of 2 major muscle membranes, perimysium and endomysium, in determining the breast meat tenderness of chickens. Birds from 2 breeds (White Leghorn and a line of broiler) were chosen. Chicks were sexed and wing-banded at hatch and were grown in separate cages in a single house. Sixty broilers and 60 White Leghorns were harvested at 6 wk of age, respectively, whereas another 60 White Leghorns were slaughtered at 18 wk of age. An equal number of males and females was maintained for each group. Body weight, breast muscle weight, pH, drip loss, cooking loss, Warner-Bratzler shear force value (SFV), total energy of shear force, fiber diameter, sarcomere length, myofiber density, and the thickness of endomysium and perimysium of the breast were determined for each bird. At 6 wk of age, histological examination indicated that the size of myofiber and thickness of endomysium and perimysium of broilers were larger than that those of White Leghorns (P < 0.01), whereas the SFV, drip loss, and cooking loss of broilers were smaller (P < 0.01). A comparison between the White Leghorns at 18 wk and the broilers at 6 wk, which were at similar BW but different ages, showed that the breast muscle weight of broilers was larger (P < 0.01) than that of White Leghorns. For breast muscle, the endomysium of broilers at 6 wk was thicker than that of White Leghorns at 18 wk (P < 0.01), whereas the perimysium was thinner (P < 0.01). The SFV, drip loss, and the cooking loss of broilers were smaller than those of White Leghorns at similar BW (P < 0.01). Meat tenderness was negatively correlated with myofiber density (-0.27) and the thickness of endomysium (-0.29) and positively correlated with the thickness of perimysium (0.20). It is suggested that muscle membrane should be considered in evaluating meat tenderness of the chicken.
Poultry Science 08/2010; 89(8):1750-4. · 1.73 Impact Factor
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ABSTRACT: Based on the knowledge of the heme bio-synthetic and metabolic pathway and the structures of biliverdin and protoporphyrin, experiments were carried out to compare the difference between the total quality of eggshell pigments in blue-shelled eggs and brown-shelled eggs from the same population (Dongxiang, China) and to analyze the correlation between the quantity of protoporphyrin and biliverdin in the 2 kinds of eggshells. It was found that there was no significant difference between the total quantity of eggshell pigments in Dongxiang blue-shelled eggs and Dongxiang brown-shelled eggs (P = 0.9006), and a highly significant positive correlation between the quantity of protoporphyrin and biliverdin in blue eggshells (P < 0.01) and a significant positive correlation between the quantity of protoporphyrin and biliverdin in brown eggshells (P < 0.05). These results suggested that eggshell protoporphyrin and eggshell biliverdin probably derived from common precursor material.
Poultry Science 08/2009; 88(8):1735-9. · 1.73 Impact Factor
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S F Sun,
Q Z Pan,
X Hui,
B L Zhang,
H M Wu,
H Li,
W Xu,
Q Zhang, J Y Li,
X M Deng,
J W Chen,
Z X Lian,
N Li
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ABSTRACT: Monocytes-macrophages are crucial players in specific and nonspecific immune responses to protect organisms from invasion of bacteria or viruses. In this study, monocytes in circulation from 2 lines of Silky and Starbro chickens with different disease resistance were separated and cultured in vitro. After identification with acridine orange (AO), Giemsa staining, and CD14 immunostaining, monocytes-macrophages were used for adherence and phagocytosis test. The overall percentages of adherence of Silky monocytes was 1.5 times greater than that of Starbro (P < 0.01), which were 26.85% +/- 8.24% and 18.34% +/- 8.15%, respectively (mean +/- SD). The monocytes-macrophages phagocytic index, phagocytic product, and percentage of phagocytosis in Silkies were greater than in Star-bros, respectively. The difference of phagocytic index was significant (P < 0.05), that is, 3.70 +/- 1.75 and 1.97 +/- 0.31, respectively (mean +/- SD). Then, 20 Silkies were divided into 2 groups according to phagocytic index: high phagocytic index (HPI) group and low phagocytic index (LPI) group, to study the relationship between phagocytic activity in vitro and pathogen clearance. After being challenged against Salmonella Pullorum C79-13, the Silky birds with HPI produced a 3-fold greater level of specific antibodies compared with those with LPI (P < 0.01), 50.21 +/- 6.67 and 16.85 +/- 4.52, respectively (mean +/- SD). In contrast to LPI birds, HPI birds shed less Salmonella Pullorum bacteria (P < 0.05), that is, 168.98 x 10(8) +/- 294.74 x 10(8) compared to 385.40 x 10(8) +/- 399.94 x 10(8) (mean +/- SD), and the shedding peak of Salmonella Pullorum in the test span appeared 4 d earlier. These results indicated that phagocytosis of monocytes-macrophages had strong effects on antibody titer and bacteria shedding postchallenge, which could be used to predict the disease resistance in animals.
Poultry Science 10/2008; 87(9):1725-33. · 1.73 Impact Factor
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ABSTRACT: The problem of hypoxia adaptation in high altitudes is an unsolved brainteaser in the field of the life sciences. As one of the best chicken breeds with adaptability to highland environment, the Tibet chicken, is genetically different from lowland chicken breeds. It is well known that hypoxia has significant impact on growth by inducing the expression of the alpha subunit of the heterodimeric transcription factor, hypoxia-inducible factor 1 (HIF1α). In the present study, HIF1α expression in brain, heart and liver tissues of the Tibet and Dwarf Recessive White chicken embryos were investigated at the different development stages of days 10, 17 and 20 by real-time PCR, and the expression pattern of HIF1α in chicken embryos of the two chicken breeds incubated under conditions of hypoxia (13% O2) and normoxia (21% O2) was studied. The incubation mortality of the Tibet chicken was lower than the Dwarf Recessive White chicken during the whole incubation in hypoxia, and the mRNA expression of HIF1α had presented the differences in three tissues. The results implied that the hypoxia adaptability of the Tibet chicken embryo was higher than the Dwarf Recessive White chicken, especially in the early stage (day 10) and at a later time (day 20) during the incubation period, but the mechanism of the oxygen transfer of embryos of mountain species is not completely understood, and hypoxia adaptability of the Tibetan chicken remains to be studied further.
animal 11/2007; 1(10):1467-71. · 1.74 Impact Factor
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ABSTRACT: An improved dissolution method called layer-by-layer dissolution was adopted to study the process of eggshell deposition, which is opposite to the process of eggshell dissolution. In the present study, blue and brown eggshells from 2 Chinese indigenous chicken breeds, Dongxing and Shouguang, respectively, were analyzed with layer-by-layer dissolution. The results showed that the deposition velocity of the eggshell pigments in the top (first) eggshell layer was the highest compared with other layers, which were biliverdin and protoporphyrin in blue eggshell or primarily protoporphyrin in brown eggshell. It was also revealed that the deposition processes of biliverdin and protoporphyrin were synchronous in the blue eggshell of the Dongxiang chicken in the present study.
Poultry Science 11/2007; 86(10):2236-8. · 1.73 Impact Factor
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ABSTRACT: NADH dehydrogenase (complex I) couples the oxidation of NADH for the reduction of ubiquinone with the generation of a proton gradient that can be used for the synthesis of ATP. We have found a missense mutation in the MT-ND5 subunit of NADH dehydrogenase in the Tibet chicken breed. In the present study, the mitochondrial respiratory control ratio (RCR) and NADH dehydrogenase activity in Tibet chicken embryonic brain with different genotypes were measured. Significant differences between animals carrying mitochondria with the EF493865.1:m.1627A vs. EF493865.1:m.1627C alleles were observed for RCR and enzyme activity.
Animal Genetics 11/2007; 38(5):514-6. · 2.40 Impact Factor
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ABSTRACT: The Tibet chicken lives in high altitude and has adapted itself well to hypoxia. The Silky chicken is a lowland chicken from Jiangxi province of China. The objective of the present study was to investigate whether there were any differences in brain mitochondrial respiratory function between Tibet chicken and Silky chicken embryos incubated in a normoxic (21% oxygen concentration) or simulated hypoxic (13% O(2)) hatchibator. Brain mitochondria of chicken embryos were prepared by differential centrifugation on d 16 of incubation. The respiratory control ratio (RCR) and the adenosine 5'-diphosphate: oxygen ratio (ADP/O) were determined polarographically. The complex I activity was measured with an ultraviolet spectrophotometer by following the oxidation of the reduced state of beta-nicotinamide adenine dinucleotide. Under the normoxic incubation condition, there were no significant differences in the RCR, the ADP/O, and the activity of complex I between embryonic brain mitochondria of the 2 breeds. Under the hypoxic incubation condition, the ADP/O in brain mitochondria of embryos from the 2 breeds were identical. Also under hypoxic conditions the RCR in brain mitochondria of Tibet chicken embryos was higher (P < 0.05) than in Silky chicken embryos when brain mitochondria were provided with glutamate-malate, but no significant difference was found in the RCR with succinate as an energy substrate. The complex I activity of Silky chicken embryos was higher than that of Tibet chicken embryos when they were incubated in the hypoxic hatchibator (P < 0.01). In conclusion, the results show that under simulated hypoxic incubation conditions electron transport in brain mitochondria of Tibet chicken embryos was more tightly coupled than that of lowland chicken (Silky chicken) embryos with glutamate-malate as energy substrate, which was associated with the difference in the activity of complex I between embryonic brains of the 2 breeds. This work will provide reference for future studies on the association of mitochondrial respiratory function with the adaptation to hypoxia.
Poultry Science 10/2007; 86(10):2210-5. · 1.73 Impact Factor
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ABSTRACT: The peroxisome proliferators-activated receptor-gamma coactivator-1alpha (PGC-1alpha) was investigated as a candidate gene for growth and fatness traits in chicken because of its prominent role in muscle fiber specialization and adipogenesis. A single nucleotide polymorphism (SNP) from G to A at position 646 of the open reading frame of chicken PGC-1alpha gene causing an Asp216Asn amino acid substitution was identified. The frequencies of alleles and genotypes were significantly different among 6 chicken breeds (P < 0.01). The White Plymouth Rock had the highest frequency (0.67) of allele G, whereas the White Leghorn had the lowest (0.18). The associations of the SNP with the growth and fatness traits were evaluated in 332 F(2) birds from an experimental cross of White Plymouth Rock x Silkies. No association was found between the SNP and growth-related traits. However, abdominal fat weight at 12 wk of age for birds with genotype GG was 34.26 and 28.71% higher than those with genotypes AA and AG, respectively (P < 0.01), indicating that the Asp216Asn polymorphism of the PGC-1alpha gene could be used as a novel potential molecular marker for selection against abdominal fatness without interfering in regular breeding for growth rate of chickens.
Poultry Science 12/2006; 85(11):1896-9. · 1.73 Impact Factor
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ABSTRACT: Biliverdin is an important pigment in the eggshell of chickens and other avian species. Determination of the biosynthesis site for biliverdin is essential for understanding the biochemical process and genetic basis of eggshell pigmentation. Either blood or the shell gland could be the biosynthesis site of eggshell biliverdin. A segregation population with full-sib sisters genotyped Oo and oo, which laid blue-shelled eggs and light brown eggs, respectively, was constructed in a native Chinese chicken breed. Ultraviolet spectrophotometry and HPLC were used to determine the biliverdin concentration in eggshells, blood, bile, excreta, and shell gland of both groups of chickens. Biliverdin content was significantly different between egg shells of blue-shelled and brown-shelled chickens (P < 0.01). Blood and bile were tested 3 to 4 h before oviposition, and excreta was tested randomly. Results showed no significant difference in biliverdin concentration in blood, bile, and excreta between the 2 groups. In the shell gland, the biliverdin contents for the blue-shelled and brown-shelled chickens were 8.25 +/- 2.55 and 1.29 +/- 0.12 nmol/g, respectively, which showed a significant difference (P < 0.01). Our results demonstrated that blood is not the biosynthesis site of the shell biliverdin. Biliverdin is most likely synthesized in the shell gland and then deposited onto the eggshell of chickens.
Poultry Science 03/2006; 85(3):546-9. · 1.73 Impact Factor
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ABSTRACT: A three-generation of chicken population is being constructed for mapping multi-economical trait loci where three extremely divergent breeds, including a broiler breed(A), a layer breed(B) and white-silk chicken(C) were employed for reciprocal cross. Four cross combinations of A Male x C Female, C Male x A Female; B Male x C Female, C Male x B Female were performed with 277 individuals in total parental population. According to the statistic analysis for growth trait, difference between parental lines is significant, F2 generation attains great variation. Correlations among body weight and daily gain traits are significant and relative coefficient are moderate or high. The number at QTL loci is expected to be no more than 10, and based on the theoretical computation the sample size of this resource population is sufficient for QTL mapping.
Acta Genetica Sinica 02/2001; 28(9):801-7.
