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Association of growth hormone (GH) and Prolactin (PRL) genes polymorphism with milk production trait in Polish Black-and-White cattle
Abstract and Figures
Associations were analysed between polymorphisms localized in intron 3 of the growth hormone gene (GH-MspI) and exon 3 of the prolactin gene (PRL-RsaI) and milk production traits of Black-and-White (Polish Friesian) cattle, including a total of 1086 cows. PCR-RFLP method was used for identification of genotypes. The following frequencies of genotypes and alleles were found: GH 0.766, 0.215 and 0.019 for +/+, +/-and-/-, respectively, and 0.873 and 0.127 for GH + and GH-, respectively; PRL 0.734, 0.257 and 0.009 for AA, AB and BB, respectively, and 0.862 and 0,138 for PRL A and PRL B , respectively. Significant differences between the herds were observed in the frequencies of both genotypes and alleles. In all three lactations the GH +/+ cows yielded most milk, whereas +/-cows showed higher milk fat content than +/+ individuals. AA cows of the PRL gene showed higher milk protein content than AB individuals. KEY WORDS: cattle / growth hormone / PCR-RFLP / polymorphism / prolactin / milk production Bovine growth hormone (bGH) is a single peptide of about 22-kDa molecular weight [23]. It is composed of 190 or 191 amino acids, containing Ala or Phe at the N-terminus, due to alternative processing of bGH precursors [18, 24]. Moreover, Leu or Val amino acid substitutions at residue 127 exist due to the allelic polymorphism [21].
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... As reviewed up to now, the bovine PRL gene is located in the 23 rd chromosome. It spans about 10 kb (9.4 kb), including here five exons and four introns (Dybus 2002;Wojdak-Maksymiec et al 2008;Sodhi et al 2011;Alfonso et al 2012;Sonmez & Ozdemir 2017;Thuy et al 2018;Oğuzkan & Bozkurt 2019). It was firstly mapped by Hallerman et al (1988), as reviewed by Alipanah et al (2007b) and He et al (2006), its content in exons and introns being reported by Camper et al (1984), as reviewed by Dybus (2002). ...
... It spans about 10 kb (9.4 kb), including here five exons and four introns (Dybus 2002;Wojdak-Maksymiec et al 2008;Sodhi et al 2011;Alfonso et al 2012;Sonmez & Ozdemir 2017;Thuy et al 2018;Oğuzkan & Bozkurt 2019). It was firstly mapped by Hallerman et al (1988), as reviewed by Alipanah et al (2007b) and He et al (2006), its content in exons and introns being reported by Camper et al (1984), as reviewed by Dybus (2002). Moreover, Patel & Chauhan (2017) reported the location of the bovine PRL gene at 43 cM close to the chromosomal QTL. ...
... Similarly, in Red Pied Russian cattle, the BB genotype yielded more protein than the AA genotype and the latter yielded more than the AB genotype. The AA genotype was associated with higher milk protein content than AB in Black and White cattle (Polish Friesian) (Dybus 2002), while the BB genotype had the highest somatic cell count and AA the lowest in a study performed in Red and White Holstein Friesian cattle by Wojdak-Maksymiec et al (2008). ...
The prolactin (PRL) gene, mapped on chromosome 23 in cattle, is usually considered in association studies with various milk traits. Although contradictory results of genotypes associations can be reported, they are generally justified if taking into account the variability of individuals (differences in investigated breeds), the number of individuals, and the investigated milk trait. The PRL gene is not a part of any Quantitative Trait Locus (QTL), but the gene of its receptor (PRLR) is. This fact is important, considering the role of PRLR protein in some steps of PRL action. This study is a review that debates important and updated aspects of PRL and PRLR genes' location and structure, physiological mechanisms of action of PRL hormone, and some associations of a well-studied polymorphism (a point mutation) with some milk traits.
... The meta-analysis for LMT trait indicated the superiority trend of genotypes may be in following order: AB = AA > BB. The superiority of AB and AA genotype over BB genotype for LMY was also reported by Dybus (2002) in Polish Black and White cattle, and Alipanah et al. (2008) in Black Pied cattle. Additionally, Ghasemi et al. (2009), Alfonso et al. (2012 and Oguzkan and Bozkurt (2019) reported AA as favorable genotype for milk production in Montebeliard, American Swiss and Holstein cattle, respectively. ...
... Our finding was in agreement with reports of Alipanah et al. (2008) in Black Pied and Red Pied cattle and Dybus et al. (2005) in Jersey cattle. However, this finding was contrary to reports of Dybus (2002) in Polish Black and White cattle, who reported non-significant difference between SNPs for this trait. On the basis of our finding, it may be suggested that B allele may be promoted in order to improve Fat% in dairy cows, but at the cost of reduction in milk yield. ...
The present meta-analysis was carried to provide the more reliable estimates of gene frequency and association of Rsa 1 generated candidate genotype of prolactin gene within exon-3 with performance traits in 1198 Indian dairy cows using data from 15 published studies. Six genetic models viz., codominant (AA vs. AB, AA vs. BB and AB vs. BB), dominant (AA+AB vs. BB), completely over dominant (AA+BB vs. AB) and recessive (AA vs. AB+BB) were used to obtain standardized mean difference (SMD) between genotypes. Meta-analysis showed that the gene frequency of A allele (156 bp) was 0.60 (95% confidence interval (CI) 0.54, 0.65). In association analysis, cows with AB genotype [SMD = 0.65, 95% CI 0.00, 1.30] had significantly (P < 0.05) higher lactation milk yield (LMY) as compared to BB genotype, whereas AA and AB genotypes had similar trend. Likewise, AA + AB also had larger effect [SMD = 2.31, 95% CI 0.21, 4.10] on LMY as compared to BB. Cows with AB genotype had significantly lower age at first calving (AFC) with small effect [SMD (AA vs. AB) = 1.38, 95% CI 0.06, 2.70] and medium effect [SMD (AB vs. BB) = − 3.83, 95% CI − 6.41, − 1.24] as compared to cows with AA and BB genotypes, respectively. This finding was confirmed under dominant and completely over dominant models. In case of fat%, AA genotype showed negative effect (SMD = − 0.51, 95% CI − 0.84, − 0.17) under recessive model. It was concluded that the propagation of allele A is promising to help dairy farmers to improve the genetic quality of their dairy cows.
... Fourth, it is common for genes regulating the expression of milk yield to have a negative or positive correlation with milk composition (protein, fat, lactose and somatic cell count, among others). In this context, the Prolactin gene (PRL), which encodes for a physiological multi-function hormone, whose specific actions occur at the reproductive and lactation levels, and, hence, influences milk yield and milk protein and fat percentages [120]. In the same way, the Prolactin Receptor gene (PRLR), which encodes for a receptor associated with a wide range of endocrine functions, such as mammalian lactation and body growth, is one of the most frequently addressed candidate genes for milk traits in the literature, given its regulation of the expression of milk yield and lactose, protein and fat percentages [121]. ...
Despite their pivotal position as relevant sources for high-quality proteins in particularly hard environmental contexts, the domestic goat has not benefited from the advances made in ge-nomics compared to other livestock species. Genetic analysis based on the study of candidate genes is considered an appropriate approach to elucidate the physiological mechanisms involved in the regulation of the expression of functional traits. This is especially relevant when such functional traits are linked to economic interest. The knowledge of candidate genes, their location on the goat genetic map and the specific phenotypic outcomes that may arise due to the regulation of their expression act as a catalyzer for the efficiency and accuracy of goat-breeding policies, which in turn translates into a greater competitiveness and sustainable profit for goats worldwide. To this aim, this review presents a chronological comprehensive analysis of caprine genetics and genomics through the evaluation of the available literature regarding the main candidate genes involved in meat and milk production and quality in the domestic goat. Additionally, this review aims to serve as a guide for future research, given that the assessment, determination and characterization of the genes associated with desirable phenotypes may provide information that may, in turn, enhance the implementation of goat-breeding programs in future and ensure their sustainability.
... Growth hormone axis governs the important functions related with regulation of metabolism, lactation and reproduction in farm animals. Growth hormone gene codes a 22 KDa single chain polypeptide protein primarily produced and secreted by the somatotrophs of the anterior pituitary gland in circadian and pulsatile manner (Dybus et al. 2002). Camel growth hormone gene is of size 1.9 kb, and found similar with other mammalian species consisting of 5 exons and 4 introns (Maniou et al. 2003). ...
The present study was aimed to assess the genetic polymorphism of growth hormone (GH) gene in Jaisalmeri and Sindhi camels using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Genomic DNA were isolated from venous blood samples collected from 93 Indian camels (Jaisalmeri-38 and Sindhi-55 camels) and 613-base pair fragment of GH gene was amplified from each genomic DNA sample by polymerase chain reaction. The PCR-RFLP was done using restriction enzyme MspI which revealed three genotypes, viz. CC, CT and TT in both the breeds. Our result indicated that both the breeds were polymorphic in nature. The corresponding genotype frequency in Jaisalmeri and Sindhi breeds were 0.474 and 0.345 for the CC, 0.395 and 0.564 for CT, 0.131 and 0.091 for TT genotypes and the corresponding C allele frequency was 0.671 and 0.627 and T allele frequency was 0.329 and 0.373. The CT genotype was found predominant in the Sindhi breed, whereas CC genotype was predominant in Jaisalmeri breed. The frequency of C allele was higher than the T allele in both of the breeds. These camel populations were in Hardy-Weinberg Equilibrium indicating that the populations meet the HWE assumptions and genetic variations were conserved. It could be concluded that Jaisalmeri and Sindhi camels having different genetic variants of GH gene might be investigated for production a DNA marker for growth and production traits in Indian camels.
... Many researchers (Alipanah et al., 2008;Maksymiec et al., 2008;Ghasemi et al., 2009) reported that the PRL gene is highly polymorphic and had an association with milk production traits. Particularly, PRL-Rsa1 locus had a significant effect on milk production and fat percentage in dairy cattle (Chung et al., 1996;Mitra et al., 1995;Chrenek et al., 1998;Udina et al., 2001;Dybus, 2001;Sacravarty et al., 2008;Wojdak et al., 2008). The genetic evaluations incorporating genomic information of late have been adopted in many countries in dairy animals. ...
Background: The selection of genetically superior animals at an early stage of life, the molecular markers are used along with traditional selection. The study was carried out to identify the genetic polymorphism in the exon3 region of the Prolactin and enumerate its effect on milk production performance in Sahiwal cattle. Prolactin plays an imperative regulatory role in mammary gland development, milk emission and lactogenesis. Analysed the sequence of this gene to explore whether mutations in this sequence and it could be accountable for quantitative variations in milk production and its composition traits.Methods: Total DNA was isolated from the blood samples of 98 pedigreed Sahiwal population. Using PCR-RFLP method and direct sequencing, noticed a single-nucleotide polymorphism in exon3 region of the Prolactin gene in 156bp and also the effect of non- genetic factors on each trait was assessed by least-squares analysis for non-orthogonal data by a fixed model.Result: PCR-RFLP was done with RsaI restriction endonuclease for the identification of different genotypes. The frequency of G and A alleles of the Prolactin gene was evaluated as 0.575 and 0.425, whereas the frequencies of GG, GA and AA genotypes for the Prolactin gene were 0.45, 0.25 and 0.30, respectively. SNP (G55A) conferred an increase in test-day milk yield around 321.5g, in test day fat yield around 13.9g and in test day SNF yield increase was 19.4g, respectively. High correlation was perceived from test day (TD2) onwards between test day traits and lactation milk yield indicating that selection based on identified SNP in TD2 increased test day milk yield, fat yield and SNF yield by 1.1472 kg, 29.6gm and 45.4gm, respectively.
... It is necessary to select genotypes with high growth and meat quality for more contribution of camels to the agricultural economy (Ramadan and Inoue-Murayama, 2017). Growth hormone (GH) is an anabolic hormone which plays an important role in postnatal longitudinal growth, tissue growth, lactation, reproduction as well as protein, lipid and carbohydrate metabolism (Dybus, 2002;Daverio et al, 2012). Among the several candidate genes, growth hormone (GH) gene structure and its role in farm animals like cattle, buffalo, sheep and goat production is widely studied. ...
Molecular characterisation of 613 bp long growth hormone (GH) gene fragment spanning partial exon-1, intron-1, exon-2 and partial intron-2 was done in Indian (one humped) dromedary and Indian (double humped) bactrian camel through PCR amplification, sequencing and bioinformatics analysis. The sequence variations within and between single and double humped Indian camels were observed. In the Indian single humped camels of Mewari, Kachchhi and Bikaneri breed at position 264 C>T variation was seen. At this particular locus animals with single and double peaks in the sequence chromatograms were observed. Accordingly, two allele (C, T) and three genotype (CC, CT, and TT) were identified in the Indian dromedary camels. In Indian Bactrian camel at position 264 only C allele and CC genotype was identified. In double humped camel at position 242, A>G and at position 469 G>A transition variation was observed compared to single humped camel. The different sequences obtained were submitted to NCBI and Gen Bank Accession No. MT478653 for C allele Indian Dromedary, MT478654 for T allele Indian Dromedary and MT478655 for Indian Bactrian camel were obtained. Similarity ranging from 98% to 100 % was observed with available GH Sequences of camel at GenBank. Camel sequence was found to have close similarity with other Camelidae family members like Lama pacos (97.07%) and Lama glama (96.58%). The evolutionary relationship between sequences showed close relationship between dromedary and bactrian camel followed by vicugna and llama. The domesticated species like cattle, buffalo, sheep, goat, yak and mithun were distantly related to camel. The present study showed close similarity between GH gene sequence pattern of Indian one and double humped camel except transition variation at two positions in bactrian camel.
... One of the most significant associations on chromosome 1 at 79 Mb was close to SST (somatostatin) and BCL6 (BCL6 transcription repressor). Since SST regulates the secretion of pituitary hormones including prolactin (Eigler and Ben-Shlomo, 2014), it may contribute to the regulation of milk production (Dybus, 2002;Alipanah et al., 2007). And BCL6 was found to be expressed in mammary epithelium and also in breast cancer (Logarajah et al., 2003). ...
German Black Pied cattle (DSN) is an endangered population of about 2,550 dual-purpose cattle in Germany. Having a milk yield of about 2,500 kg less than the predominant dairy breed Holstein, the preservation of DSN is supported by the German government and the EU. The identification of the genomic loci affecting milk production in DSN can provide a basis for selection decisions for genetic improvement of DSN in order to increase market chances through the improvement of milk yield. A genome-wide association analysis of 30 milk traits was conducted in different lactation periods and numbers. Association using multiple linear regression models in R was performed on 1,490 DSN cattle genotyped with BovineSNP50 SNP-chip. 41 significant and 20 suggestive SNPs affecting milk production traits in DSN were identified, as well as 15 additional SNPs for protein content which are less reliable due to high inflation. The most significant effects on milk yield in DSN were detected on chromosomes 1, 6, and 20. The region on chromosome 6 was located nearby the casein gene cluster and the corresponding haplotype overlapped the CSN3 gene (casein kappa). Associations for fat and protein yield and content were also detected. High correlation between traits of the same lactation period or number led to some SNPs being significant for multiple investigated traits. Half of all identified SNPs have been reported in other studies, previously. 15 SNPs were associated with the same traits in other breeds. The other associated SNPs have been reported previously for traits such as exterior, health, meat and carcass, production, and reproduction traits. No association could be detected between DGAT1 and other known milk genes with milk production traits despite the close relationship between DSN and Holstein. The results of this study confirmed that many SNPs identified in other breeds as associated with milk traits also affect milk traits in dual-purpose DSN cattle and can be used for further genetic analysis to identify genes and causal variants that affect milk production in DSN cattle.
Objective
The present work aimed to obtain common effect sizes for the gene frequency and association of MspI derived variants of growth hormone (GH) gene with milk yield in dairy cows.
Methods
We performed a systematic review and meta-analysis of 35 published studies identified in literature search from 2000 to 2020 (n = 4164). These studies were specific to fragment size (329) for genotypes viz., CC (224, 105 bp), CD (329, 224, 105 bp) and DD (329 bp). Pooled standard mean differences (SMDs) as effect sizes between allele pairs were derived using different genetic models. The heterogeneity between effects sizes across studies was estimated using I² Index (%).
Results
The common effect size for gene frequency of allele C (224, 105 bp) was significantly (P < 0.05) higher in 2881 Bos taurus/cross cows (0.82; 95% CI: 0.74, 0.89; I² = 97.81%) than 1283 Bos indicus cows (0.15; 95% CI: 0.12, 0.18; I² = 71.90%), with overall gene frequency was 0.33 (95% CI: 0.21, 0.46; I² = 99.29%). Additive (CC vs. DD) and dominant (CC + CD vs. DD) did not revealed significant (P > 0.05) association with milk yield. However, completely over dominant (CC + DD vs. CD) and recessive (CC vs. CD + DD) models showed significant (P < 0.05) and positive SMDs with milk yield specially at early lactations. There was no evidence of heterogeneity (I² = 0.00%) between SMDs across studies.
Conclusions
This meta-analysis suggested potential association of C allele for enhancing milk production of dairy cows.
Growth hormone (GH) is a major regulator of postnatal growth and metabolism in mammals and plays a critical role in growth, production and fertility in cattle. The present study was conducted in dairy cattle to find the association of g.48769565 C>T mutation with growth, production and reproduction traits in Sahiwal and Hardhenu cattle. PCR‐RFLP was performed to genotype g.48769565 C>T mutation using the MspI restriction enzyme in our resource cattle population. In Hardhenu cattle, the frequencies of C and T alleles were 0.59 and 0.41 respectively while genotypic frequencies were 0.06, 0.36 and 0.58 for CC,CT and TT respectively. The frequencies of the C and T allele were 0.24 and 0.76 respectively in Sahiwal cattle and it was observed that highest frequency was forTT genotype (0.58) and lowest for CC genotype (0.06). Chi‐square analysis showed that g.48769565C>T SNP loci did not meet with the Hardy–Weinberg equilibrium (p< 0.01) in Sahiwal cattle. From the least‐squares analysis, it was observed that CC genotype was significantly associated with total Milk Yield (TMY), 300 days milk yield (300D MY), lactation length (LL), Dry period (DP) and Artificial insemination (AI)/conception (p<0.05). We also observed a significant association (p<0.05) of genotype CT with 3‐month calves body weight. Cows with TT genotype revealed comparatively revealed favourable service period (SP) and calving interval (CI) in both Hardhenu and Sahiwal. These observed differences in their allelic and genotypic frequencies in association with the traitsunderlying production and fertility can be utilized for genetic improvement in dairy cattle.
Understanding the genetic factors influencing the growth traits of animal is very important for an accurate selection and genetic improvement of these quantitative traits. Therefore, the aim of this study was to identify polymorphisms in growth hormone (GH), insulin-like growth factor-I (IGF-I), melanocortin-4 receptor (MC4R) and diacylglycerol O-acyltransferase 1 (DGAT1) genes and their association with body weight and daily gain in dromedary camels. Blood samples were collected from seventy camels using vacutainer tube containing EDTA as an anticoagulant for DNA extraction. PCR-DNA sequencing approach was performed to investigate polymorphisms in fragments for 5’ UTR of GH (286-bp) and part of coding sequence (CDS) of IGF-I (462-bp), MC4R (512-bp), and DGAT1 (390-bp) genes. Results revealed that there were single nucleotide polymorphisms (SNPs) in the investigated genes between the enrolled camels except for IGF-I gene that elicited a monomorphic pattern. The identified SNPs allocated camels into different groups according to which animal harbored the explored SNPs. Using multiple linear regression analysis (MLR), identified SNPs had a significant effect on body weight and weight gain at different age stages. Determination coefficients (R²) value indicated that variability in the phenotypic measurements of growth performance might be correlated with the identified SNPs in growth related genes. The area under the ROC curves was higher in the case of DGAT (0.793-1.0), followed by GH (0.736-0.866) and then MCR (0.410-0.545). DGAT anticipates body weight and weight gain traits better than GH and MCR. As a pilot study, single nucleotide polymorphisms in the investigated genes could be used as proxy predictors and genetic markers that permit a marker assisted selection for growth traits in dromedary camels.
A cattle genetic linkage map was constructed which covers more than 95 percent of the bovine genome at medium density. Seven hundred and forty six DNA polymorphisms were genotyped in cattle families which comprise 347 individuals in full sibling pedigrees. Seven hundred and three of the loci are linked to at least one other locus. All linkage groups are assigned to chromosomes, and all are orientated with regards to the centromere. There is little overall difference in the lengths of the bull and cow linkage maps although there are individual differences between maps of chromosomes. One hundred and sixty polymorphisms are in or near genes, and the resultant genome-wide comparative analyses indicate that while there is greater conservation of synteny between cattle and humans compared with mice, the conservation of gene order between cattle and humans is much less than would be expected from the conservation of synteny. This map provides a basis for high-resolution mapping of the bovine genome with physical resources such as Yeast and Bacterial Artificial Chromosomes as well as providing the underpinning for the interpolation of information from the Human Genome Project.
USDA-MARC family and data for validating this family. P. Creighton, C. Skidmore, T. Holm, and A. Georgoudis provided some validation data for the BOVMAP families. R. Fries, S. Johnson, S. Solinas Toldo, and A. Mezzelani kindly made some of their FISH assignments available before publication. We wish to thank all those researchers who kindly sent us probes and DNA primers.
A simplified method of simultaneous genotyping of bovine growth hormone (bGH) and prolactin (bPRL) has been developed. The method is based on simultaneous amplification of fragments of the two genes by multiplex PCR, and subsequent digestion of the products by two restriction enzymes (Alu I and Rsa I). Digestion with Alu I distinguished growth hormone L and V alleles and did not cut within the prolactin fragment, while digestion with Rsa I allowed the differentiation between the A and B alleles of bovine prolactin. All combinations of the known alleles could be detected by electrophoretic separation on the same agarose gel. Frequency of the allele L of the bovine growth hormone gene in Slovak Pied, Slovak Pinzgauer and Holstein was 0.55, 0.55 and 0.72, respectively. Frequency of the allele A of the bovine prolactin gene in the same breeds was 0.87, 0.68 and 0.95, respectively.
A library of cloned bovine DNA fragments was constructed and screened for growth hormone sequences. The growth hormone gene was isolated from this library and its nucleotide sequence determined. The likely transcription initiation site was located using the S1 nuclease protection procedure. The bovine growth hormone gene contains approximately 1793 nucleotides and consists of five exons separated by four intervening sequences. The sequence TATAAA is found in the 5' flanking region and probably is involved in facilitating transcription initiation. Comparison of the bovine growth hormone gene to the known sequence of the rat and human genes reveals that the coding regions of the three genes are highly conserved. In general the intervening sequences are much less similar than the coding regions. Interestingly, all three growth hormone genes share a conserved (but nonidentical) 40 base pair region within the 5' flanking region. This conserved region may be an important sequence involved in the hormonal regulation of growth hormone gene transcription. Analysis of GH sequences present in total bovine DNA suggests that the bovine genome contains a gene similar to the cloned gene as well as a different, but related, gene. The functional significance of the two genes remains to be explored. Analysis of nuclear species of growth hormone mRNA has demonstrated the presence of RNAs of 2100, 1400 and 1000 nucleotides containing growth hormone sequences. These likely correspond to a polyadenylated primary transcript, a processing intermediate and mature growth hormone mRNA, respectively.
Gene and genotype frequencies of alleles, identified by PCR/RFLP technology, at leucine 127/valine127 (L/V) ana C/D loci of the growth hormone gene of Ayrshire, Holstein and Jersey breeds were determined. The frequency of the V allele at the L/V mutation locus was 0.29, 0.09 and 0.24 for the Ayrshire, Holstein and Jersey breeds, respectively. The frequencies of the D allele at the C/D mutation locus were 0.00, 0.13 and 0.30 for the three breeds, respectively. Different growth hormone genotypes of Holstein AI bulls were compared for their estimated transmitting abilities (ETA) of milk, fat and protein yields using the samples of unrelated bulls and samples of the top, medium and bottom groups of ETA. The L/V locus was significantly (p < 0.05) associated with fat and protein ETAs of the selected groups and approached significance (p = 0.06) for milk ETA, with the V allele being more frequent in the top than in the bottom group of bulls. The C/D polymorphic locus was significantly (p = 0.02) associated with differences among the top, middle and bottom groups of bulls for milk ETA, but not significantly (p > 0.05) associated with fat and protein ETAs. The results suggest a possible association of growth hormone gene polymorphism with milk production traits in Holstein bulls. However, the results were not conclusive due to the small sample size and low frequencies of the V and D alleles. Much larger sample sizes are needed to obtain a reasonable number of W and DD genotypes for a critical comparison.
Major translation products of bovine pituitary RNA in a wheat germ cell-free system were identified as larger forms (prehormones) of growth hormone and prolactin containing amino-terminal extensions of 26 or 27 and 30 amino acid residues, respectively. However, translation of bovine pituitary RNA in the wheat germ cell-free system in the presence of microsomal membranes prepared from canine pancreas or bovine pituitary yielded products that were of the same size as authentic growth hormone and prolactin; by partial amino-terminal sequence analysis they were shown to contain the correct unique amino-terminal sequence of prolactin and the two correct amino termini of authentic growth hormone; moreover, they were found to be segregated within the microsomal vesicles in that they were largely inaccessible to degradation by proteolytic enzymes. When microsomal membranes were present after rather than during translation, prehormones were neither cleaved nor segregated. These results strongly suggest that the synthesis and segregation of the authentic hormone observed in the presence of membranes proceeds via a nascent prehormone rather than a completed prehormone.
The major histocompatibility complex and prolactin (PRL) genes are syntenic in humans and cattle but the genetic distance between these loci has not been determined for either species. In this study, the sperm typing technique was used to measure the recombination frequency between the bovine lymphocyte antigen (BoLA)-DRB3 and PRL loci. A total of 300 sperm were typed from one doubly heterozygous bull for segregation of DRB3 and PRL alleles. Sperm typing was performed using the polymerase chain reaction (PCR) and restriction enzyme cleavage of the PCR products, followed by resolution of the restriction fragments in polyacrylamide gels. Digestion with the restriction endonuclease RsaI allowed the unambiguous discrimination of alleles for both loci. The maximum likelihood estimation of the recombination fraction theta = 0.04, with a 95% confidence interval of 0.01 to 0.07. Close linkage between PRL and DRB3 has important implications for marker-assisted selection in animal breeding since PRL has been shown to be closely linked to a locus that affects milk yield, and BoLA loci influence susceptibility to a number of infectious diseases. Our results demonstrate the general applicability of the sperm typing procedure for gene mapping in species other than humans and provide an example of how parallel efforts to map the genomes of agriculturally important species of animals can have a positive impact on the development of a primary human linkage map.
The growth hormone gene locus (GH) of cattle and sheep was mapped to a chromosomal region in each species by using in situ hybridization. The probe employed was an 830-bp cDNA sequence from the ovine growth hormone gene. Based on QFQ chromosome preparations, our results show that the GH locus is on cattle chromosome 19 in the region of bands q26-qter and in sheep on chromosome region 11q25-qter. The GH assignments together with previous localizations of type I cytokeratin genes (KRTA) and one homeobox (HOX2) gene in cattle and one type I cytokeratin gene (KRTA) in sheep identify a strongly conserved chromosomal segment on human chromosome 17, bovine chromosome 19, and sheep chromosome 11.
New DNA sequence polymorphisms were identified at four bovine autosomal loci: growth hormone, low density lipoprotein receptor, alpha-subunit of glycoprotein hormones and thyroglobulin. Assuming independent assortment between these polymorphisms, the probabilities to be heterozygous at these four loci are 0.48, 0.36, 0.10 and 0.77 respectively, within the Belgian Blue Cattle breed (BBCB). Nucleotide diversity was estimated, showing that animals from the BBCB are heterozygous for 1/1450 nucleotides, a value significantly lower than the 1/500 value found in man. Moreover, we have estimated that the mutation rate at the cytosines of CG dinucleotides is about 10 times higher than that for other nucleotides.
Sperm DNA isolated from sons of three extensively used US Holstein bulls was screened for differences associated with the primary gene structure of the bovine growth hormone (bGH) and prolactin (bPrl) genes. Southern blot analysis of DNA digested with 10 restriction enzymes revealed that offspring from two of the three bull families exhibited polymorphisms around the bGH and bPrl genes. Restriction fragment length polymorphisms (RFLPs) around the bGH gene were detected with five enzymes, whereas three enzymes revealed RFLPs around the bPrl gene. At least three structural differences were predicted around the bGH gene. The most common variant hybridization pattern appeared to involve an insertion/deletion located downstream of the conserved 3' EcoRI site. The presence of RFLPs in the genes coding for these pituitary hormones within a familial line may provide the basis for genetic markers associated with lactation and mammary development.