Candidate Genes For Growth Research Articles

Cis-eQTLs in seven duck tissues identify novel candidate genes for growth and carcass traits

BackgroundExpression quantitative trait loci (eQTL) studies aim to understand the influence of genetic variants on gene expression. The colocalization of eQTL mapping and GWAS strategy could help identify essential candidate genes and causal DNA variants vital to complex traits in human and many farm animals. However, eQTL mapping has not been conducted in ducks. It is desirable to know whether eQTLs within GWAS signals contributed to duck economic traits.ResultsIn this study, we conducted an eQTL analysis using publicly available RNA sequencing data from 820 samples, focusing on liver, muscle, blood, adipose, ovary, spleen, and lung tissues. We identified 113,374 cis-eQTLs for 12,266 genes, a substantial fraction 39.1% of which were discovered in at least two tissues. The cis-eQTLs of blood were less conserved across tissues, while cis-eQTLs from any tissue exhibit a strong sharing pattern to liver tissue. Colocalization between cis-eQTLs and genome-wide association studies (GWAS) of 50 traits uncovered new associations between gene expression and potential loci influencing growth and carcass traits. SRSF4, GSS, and IGF2BP1 in liver, NDUFC2 in muscle, ELF3 in adipose, and RUNDC1 in blood could serve as the candidate genes for duck growth and carcass traits.ConclusionsOur findings highlight substantial differences in genetic regulation of gene expression across duck primary tissues, shedding light on potential mechanisms through which candidate genes may impact growth and carcass traits. Furthermore, this availability of eQTL data offers a valuable resource for deciphering further genetic association signals that may arise from ongoing extensive endeavors aimed at enhancing duck production traits.

Performance, heritability, and candidate genes for growth in dusky kob (Argyrosomus japonicus): Implications for genetic improvement during early phase domestication

Dusky kob, is a Sciaenid finfish that has a global distribution and is indigenous to South Africa. Historically, the species was a prime target for fisheries, but is currently an emerging candidate for aquaculture due to declining wild populations. Aquaculture breeding pose challenges to conventional genetic selection methods, especially when species are new (essentially wild), and industries are small: Founder populations are limited, and sexual maturity is often late; mass spawning leads to large variances in broodstock contributions and pedigree records are difficult to keep; and production environments are often highly variable. To overcome such challenges, this study consolidated inferred pedigree and phenotypic data across three aquaculture facilities and was able to estimate robust heritability values for the correlated growth traits, wet weight (0.46 ± 0.29) and standard length (0.41 ± 0.27). We further suggest that conventional phenotypic selection be combined with marker assisted selection to improve potential genetic gains. To this aim a case-control association analysis was done using a candidate gene approach, prioritising, and validating genetic variants from a previously developed exome resource for dusky kob. Three genes with large effect sizes on phenotypes were identified: tankyrase [Haplotypic Odd Ratio (OR) = 22.98]; myoblast determination protein 1 (highest individual SNP OR = 5.28); and bone morphogenetic protein 2 (Haplotypic OR = 13.33). If a cooperative model for genetic improvement was to be implemented across farms, using a combinational approach, it could facilitate making genetic gains during the early phases of domestication.

Transcriptome analyses reveal differentially expressed genes associated with development of the palatal organ in bighead carp (Hypophthalmichthys nobilis)

The palatal organ is a filter-feeding related organ and occupies a considerable proportion of the head of bighead carp (Hypophthalmichthys nobilis), a large cyprinid fish intensive aquaculture in Asia. In this study, we performed RNA-seq of the palatal organ during growth periods of two (M2), six (M6) and 15 (M15) months of age after hatching. The numbers of differentially expressed genes (DEGs) were 1384, 481 and 1837 for M2 VS M6, M6 VS M15 and M2 VS M15 respectively. The following signaling pathways of energy metabolism and cytoskeleton function were enriched, including ECM-receptor interaction, Cardiac muscle contraction, Steroid biosynthesis and PPAR signaling pathway. Several members of collagen family (col1a1, col2a1, col6a2, col6a3, col9a2), Laminin gamma 1 (lamc1), integrin alpha 1 (itga1), Fatty acid binding protein 2 (fads2) and lipoprotein lipase (lpl), and Protein tyrosine kinase 7 (Ptk7) are candidate genes for growth and development of basic tissues of the palatal organ. Furthermore, taste-related genes such as fgfrl1, fgf8a, fsta and notch1a were also identified, which may be involved in the development of taste buds of the palatal organ. The transcriptome data obtained in this study provide insights into the understanding functions and development mechanisms of palatal organ, and potential candidate genes that may be related to the genetic modulation of head size of bighead carp.

Candidate Genes and Gene Networks Change with Age in Japanese Black Cattle by Blood Transcriptome Analysis.

Age is an important physiological factor that affects the metabolism and immune function of beef cattle. While there have been many studies using the blood transcriptome to study the effects of age on gene expression, few have been reported on beef cattle. To this end, we used the blood transcriptomes of Japanese black cattle at different ages as the study subjects and screened 1055, 345, and 1058 differential expressed genes (DEGs) in the calf vs. adult, adult vs. old, and calf vs. old comparison groups, respectively. The weighted co-expression network consisted of 1731 genes. Finally, blue, brown, and yellow age-specific modules were obtained, in which genes were enriched in signaling pathways related to growth and development and immune metabolic dysfunction, respectively. Protein-protein interaction (PPI) analysis showed gene interactions in each specific module, and 20 of the highest connectivity genes were chosen as potential hub genes. Finally, we identified 495, 244, and 1007 genes by exon-wide selection signature (EWSS) analysis of different comparison groups. Combining the results of hub genes, we found that VWF, PARVB, PRKCA, and TGFB1I1 could be used as candidate genes for growth and development stages of beef cattle. CORO2B and SDK1 could be used as candidate marker genes associated with aging. In conclusion, by comparing the blood transcriptome of calves, adult cattle, and old cattle, the candidate genes related to immunity and metabolism affected by age were identified, and the gene co-expression network of different age stages was constructed. It provides a data basis for exploring the growth, development, and aging of beef cattle.

Genome wide association study identifies novel candidate genes for growth and body conformation traits in goats

Pakistan is third largest country in term of goat population with distinct characteristics of breeds and estimated population of 78.2 million. Punjab province has 37% of country’s total population with seven important documented goat breeds namely Beetal, Daira Din Pannah, Nachi, Barbari, Teddi, Pahari and Pothwari. There is paucity of literature on GWAS for economically important traits i.e., body weight and morphometric measurements. Therefore, we performed GWAS using 50 K SNP Chip for growth in term of age adjusted body weight and morphometric measurements in order to identify genomic regions influencing these traits among Punjab goat breeds. Blood samples were collected from 879 unrelated animals of seven goat breeds along with data for body weight and morphometric measurements including body length, body height, pubic bone length, heart girth and chest length. Genomic DNA was extracted and genotyped using 50 K SNP bead chip. Association of genotypic data with the phenotypic data was performed using Plink 1.9 software. Linear mixed model was used for the association study. Genes were annotated from Capra hircus genome using assembly ARS1. We have identified a number of highly significant SNPs and respective candidate genes associated with growth and body conformation traits. The functional aspects of these candidate genes suggested their potential role in body growth. Moreover, pleiotropic effects were observed for some SNPs for body weight and conformation traits. The results of current study contributed to a better understanding of genes influencing growth and body conformation traits in goat.

Genetic variability in GH and IGFBP-3 genes and their association with growth performance in Egyptian sheep

The polymorphisms in Insulin-like Growth Factor Binding Protein-3 (IGFBP-3) and Growth Hormone (GH) have an effect on mammalian growth control, development and reproduction activity. This investigation aimed to study the polymorphism in IGFBP-3 and GH genes, and detect their association with body weights and growth performance of several sheep breeds (Ovis aries) namely; Rahmani, Barki, Rahmani x Barki cross, Awassi/Awassi x Suffolk cross and Ossimi. Digestion of 654 bp for IGFBP-3/HaeIII yielded only one restriction pattern of 8 fragments in all studied breeds revealing the absence of polymorphism and this agrees with gene sequencing. While, sequencing analysis of the amplified fragment of GH gene revealed polymorphism in nucleotide sequencing. 4 SNPs out of 11 (C1776G, T1772A, G1769C and C1765A) in Rahmani, while 1 SNPs out of 2 (A1544G) in Barki, whilst 3 SNPs out of 4 (A1678G, A1558G and A1544G) in Rahmani x Barki cross, whereas 2 SNPs out of 4 (C1765A and G1550A) in Awassi /Awassi x Suffolk cross and 3 SNPs out of 8 (T1772A, G1769C and G1756C) in Ossimi were very important. The amino acid sequence for GH gene of Rahmani was different from those of other breeds in 4 amino acids, while, each of Rahmani x Barki cross and Ossimi amino acid sequences were different in 3 amino acids. The current results suggest that body weights and growth performance of tested sheep breeds at different stages of growth are statistically affected by GH gene which could be considered as a candidate gene for growth in breeding programs.

Association analysis of IGF2 gene polymorphisms with growth traits of Dezhou donkey

IGF2 is an insulin-like growth factor that plays an important role in the development of animal embryos. In order to determine whether IGF2 gene is associated with important economic characteristics of donkeys, we investigated the association between single nucleotide polymorphisms (SNPs) of IGF2 gene and body size traits of Chinese Dezhou donkeys and analyzed the expression level of IGF2 gene in different tissues of juvenile and adult Dezhou donkeys. In this study, two SNPs (g.281766 G > A and g.291322 C > T) were detected in IGF2 gene, both of which were in Hardy-Weinberg equilibrium (P > 0.05) and were moderately polymorphic (0.25 < PIC < 0.50). Association analysis showed that the two SNP loci were significantly correlated with body length and rump height (p < 0.05) of female Dezhou donkeys. Quantitative results showed that the expression of IGF2 gene was higher in heart, liver, spleen, lung, kidney, stomach and muscle tissues of juvenile donkeys than that of adult donkeys. Together, IGF2 can be considered as a candidate gene for growth and development of female Dezhou donkey, and its polymorphism can be used as a molecular marker for the Dezhou donkey breeding.

Association of SNP loci and candidate genes for growth and wood density in Eucalyptus urophylla × E. tereticornis

Association of SNP loci and candidate genes for growth and wood density in Eucalyptus urophylla × E. tereticornis

Identification of QTL regions and candidate genes for growth and feed efficiency in broilers

BackgroundFeed accounts for about 70% of the total cost of poultry meat production. Residual feed intake (RFI) has become the preferred measure of feed efficiency because it is phenotypically independent of growth rate and body weight. In this study, our aim was to estimate genetic parameters and identify quantitative trait loci (QTL) for feed efficiency in 3314 purebred broilers using a genome-wide association study. Broilers were genotyped using a custom 55 K single nucleotide polymorphism (SNP) array.ResultsEstimates of genomic heritability for seven growth and feed efficiency traits, including body weight at 28 days of age (BW28), BW42, average daily feed intake (ADFI), RFI, and RFI adjusted for weight of abdominal fat (RFIa), ranged from 0.12 to 0.26. Eleven genome-wide significant SNPs and 15 suggestively significant SNPs were detected, of which 19 clustered around two genomic regions. A region on chromosome 16 (2.34–2.66 Mb) was associated with both BW28 and BW42, and the most significant SNP in this region, AX_101003762, accounted for 7.6% of the genetic variance of BW28. The other region, on chromosome 1 (91.27–92.43 Mb) was associated with RFI and ADFI, and contains the NSUN3 and EPHA6 as candidate genes. The most significant SNP in this region, AX_172588157, accounted for 4.4% of the genetic variance of RFI. In addition, a genomic region containing the gene AGK on chromosome 1 was found to be associated with RFIa. The NSUN3 and AGK genes were found to be differentially expressed in breast muscle, thigh muscle, and abdominal fat between male broilers with high and low RFI.ConclusionsWe identified QTL regions for BW28 and BW42 (spanning 0.32 Mb) and RFI (spanning 1.16 Mb). The NSUN3, EPHA6, and AGK were identified as the most likely candidate genes for these QTL. These genes are involved in mitochondrial function and behavioral regulation. These results contribute to the identification of candidate genes and variants for growth and feed efficiency in poultry.

Sequence analyses of insulin-like growth factor 1 gene in Nigerian indigenous and arbor acre chickens

Alpha % Indigenous chicken % Gene % Sequence KR nema The chicken Insulin-like growth factor 1 (IGF1) is a candidate gene for growth, body composition and metabolism, skeletal characteristics and growth of adipose tissue and fat deposition in chickens. It is mapped to 165.95 cM on chromosome 1 and composed of four exons and three introns, spanning more than 50 kb. Genomic DNA was extracted from blood samples collected from the experimental birds using Qiagen DNA extraction kits. Polymersae chain reaction (PCR) was carried out using established primers. The PCR amplicon involving 5?untranslated region were sequenced. The sequences were analysed to identify polymorphisms, their genetic diversities and evolutionary relationships among three strains of Nigerian indigenous chickens [Frizzle Feathered (7), Normal Feathered (19) and Naked Neck (19), and the Arbor Acre broiler chicken (17)]. Nucleotide sequences generated were edited and aligned using Codon Code Aligner. Diversity analysis was done using DnaSp while MEGA6 software was used to plot phylogenetic tree using maximum likelihood method. A total of nineteen single nucleotide polymorphisms (SNPs) were detected from 560 bp portions of the 5?UTR among the four chicken populations studied with none detected in the Frizzle feathered chicken. The Naked neck chicken had the highest number of SNP?s (13), haplotypes (6), haplotype diversity (0.778), nucleotide diversity (0.00487), average number of nucleotide differences (2.725), highest number of polymorphic (segregating) sites (13), parsimony informative site (5) and singleton variable site (8). The Naked neck chicken therefore had the highest rate of mutation and degree of allelic variation compared to other chicken strains used in this study. The phylogenetic tree showed that small genetic differentiation exists among the chicken populations studied. Some of the SNPs are newly discovered; hence, association between these alleles and productive traits in Nigerian native chickens is desirable in future studies.

Molecular Cloning and Polymorphism Analysis of PmFGF18 from Pinctada fucata martensii

Fibroblast growth factor 18 (FGF18) plays an important functional role in skeletal growth and development. The FGF18 gene was characterized in pearl oyster Pinctada fucata martensii (PmFGF18) with the full-length sequence containing an open reading frame of 714 bp encoding 237 amino acids. The domain analysis of PmFGF18 showed a distinctive FGF domain, with a high similarity to FGF18 protein sequences from Crassostrea gigas (43.35%) and C. virginica (37.43%). PmFGF18 expression was revealed in all analyzed tissues with a significantly higher expression level in the fast-growing group than the slow-growing group. The analysis of PmFGF18 polymorphism demonstrated 33 SNPs (single nucleotide polymorphisms) in the CDS and promoter region of PmFGF18 sequence. Association analysis revealed 19 SNPs (2 SNPs from CDS and 17 SNPs from the promoter region) associating significantly with growth traits. Among the associated SNPs, one SNP g.50918198 A &gt; C was verified in the other breeding line. Therefore, PmFGF18 can be utilized as a candidate gene for growth, and its related SNPs could be used in selective breeding of P. f. martensii for the improvement of growth traits.

Tissue expression profile, polymorphism of IGF1 gene and its effect on body size traits of Dezhou donkey

Insulin-like growth factor 1 (IGF1) is a multifunctional cell proliferation regulator that plays a critical role in regulating animal growth and development. In this study, the expression level of IGF1 gene in different tissues of Dezhou donkey in different periods was investigated by RT-qPCR. Meanwhile, two mutation sites were identified within the IGF1 gene and its effect on body size traits of Dezhou donkey was analysed. The results showed that the expression level of the adult donkey IGF1 gene in heart, liver, spleen, lung, renal and gastric tissues is higher than that of the young donkeys, but the young donkeys are significantly higher in muscle tissues than the adult donkeys. The IGF1-1 and IGF1-2 loci showed a trend that the GG mutant was larger than other genotypes in the growth traits of both male and female donkeys, among which the IGF1-1 loci had a significant association with the chest circumference and chest depth of male donkeys (P < 0.05), and the IGF1-2 loci had a significant association with the chest circumference of female donkeys. Haplotype combination Hap1Hap1 (GG-GG) showed a greater tendency than Hap2Hap2 (AA-GG) combination in terms of growth traits, reflecting that the results were consistent with the analysis results of genotypes, which also proved the analysis results of genotypes and growth traits had certain reliability. In summary, the IGF1 gene is a candidate gene for growth and development, and its polymorphisms can be used as the molecular markers for Dezhou donkey breeding.

Genome-wide association studies and meta-analysis uncovers new candidate genes for growth and carcass traits in pigs.

Genome-wide association studies (GWAS) have been widely used in the genetic dissection of complex traits. As more genomic data is being generated within different commercial or resource pig populations, the challenge which arises is how to collectively investigate the data with the purpose to increase sample size and implicitly the statistical power. This study performs an individual population GWAS, a joint population GWAS and a meta-analysis in three pig F2 populations. D1 is derived from European type breeds (Piétrain, Large White and Landrace), D2 is obtained from an Asian breed (Meishan) and Piétrain, and D3 stems from a European Wild Boar and Piétrain, which is the common founder breed. The traits investigated are average daily gain, backfat thickness, meat to fat ratio and carcass length. The joint and the meta-analysis did not identify additional genomic clusters besides the ones discovered via the individual population GWAS. However, the benefit was an increased mapping resolution which pinpointed to narrower clusters harboring causative variants. The joint analysis identified a higher number of clusters as compared to the meta-analysis; nevertheless, the significance levels and the number of significant variants in the meta-analysis were generally higher. Both types of analysis had similar outputs suggesting that the two strategies can complement each other and that the meta-analysis approach can be a valuable tool whenever access to raw datasets is limited. Overall, a total of 20 genomic clusters that predominantly overlapped at various extents, were identified on chromosomes 2, 7 and 17, many confirming previously identified quantitative trait loci. Several new candidate genes are being proposed and, among them, a strong candidate gene to be taken into account for subsequent analysis is BMP2 (bone morphogenetic protein 2).

Construction of a high-density genetic map and fine QTL mapping for growth and nutritional traits of Crassostrea gigas

BackgroundBoth growth and nutritional traits are important economic traits of Crassostrea gigas (C. gigas) in industry. But few work has been done to study the genetic architecture of nutritional traits of the oyster. In this study, we constructed a high-density genetic map of C. gigas to help assemble the genome sequence onto chromosomes, meanwhile explore the genetic basis for nutritional traits via quantitative trait loci (QTL) mapping.ResultsThe constructed genetic map contained 5024 evenly distributed markers, with an average marker interval of 0.68 cM, thus representing the densest genetic map produced for the oyster. According to the high collinearity between the consensus map and the oyster genome, 1574 scaffold (about 70%) of the genome sequence of C. gigas were successfully anchored to 10 linkage groups (LGs) of the consensus map. Using this high-qualified genetic map, we then conducted QTL analysis for growth and nutritional traits, the latter of which includes glycogen, amino acid (AA), and fatty acid (FA). Overall, 41 QTLs were detected for 17 traits. In addition, six candidate genes identified in the QTL interval showed significant correlation with the traits on transcriptional levels. These genes include growth-related genes AMY and BMP1, AA metabolism related genes PLSCR and GR, and FA metabolism regulation genes DYRK and ADAMTS.ConclusionUsing the constructed high-qualified linkage map, this study not only assembled nearly 70% of the oyster genome sequence onto chromosomes, but also identified valuable markers and candidate genes for growth and nutritional traits, especially for AA and FA that undergone few studies before. These findings will facilitate genome assembly and molecular breeding of important economic traits in C. gigas.

Detection of candidate genes for growth and carcass traits using genome-wide association strategy in Chinese Simmental beef cattle

In Chinese beef cattle industry, there are more than 60 million livestock, nearly half of which are Chinese Simmental beef cattle or Simmental crossbreds. Over the past decades, numerous quantitative trait loci for economic traits in cattle have been identified, while few studies for growth and carcass traits have been reported in Simmental beef cattle. In the present study, we conducted genome-wide association study based on BovineHD BeadChip and identified 41, 15, 3, 22 and 16 single-nucleotide polymorphisms significantly associated with average daily gain, liveweight before slaughter, carcass weight, dressing percentage and pure meat percentage respectively. In total, 18 candidate genes were found for growth and carcass traits, and four haplotype blocks for growth and carcass traits were discovered. These findings will facilitate detection of major genes and genetic variants involved in growth and carcass traits of beef cattle in further studies.

QTL fine mapping and identification of candidate genes for growth-related traits in bighead carp (Hypophthalmichehys nobilis)

Bighead carp (Hypophthalmichthys nobilis) is a popular Asian aquaculture species, but its genetic improvement is still in infancy. Marker-assisted selection (MAS) can improve the selection efficiency of breeding programs in fish. In this study, we constructed a genetic linkage map in a F1 family of bighead carp using microsatellite markers. A total of 905 microsatellites were assigned onto 24 linkage groups (LGs) of a consensus map, which spanned 1631.7cM of bighead carp genome with an average interval of 1.8cM. Comparative genomics revealed a high level of genomic synteny between bighead carp and zebrafish. QTL mapping for growth traits was performed based on this linkage map, and three significant and 8 suggestive QTL associated with four growth traits (body length, body height, head length, body weight) were detected on LG9 and LG17, with 18.6–25.5% of phenotypic variance explained. Three candidate genes for growth were identified in or near the QTL intervals, and a SNP in one of the three genes, TP53BP2, was significantly associated with growth traits in different populations of bighead carp. These results of the high-density SSR genetic map and genome scan for QTL provide a basis for MAS and breeding programs for growth in bighead carp.

Novel single nucleotide polymorphisms in candidate genes for growth in tilapia ( Oreochromis niloticus )

The objective of the present work was to identify and validate single nucleotide variations located in candidate genes to growth traits in tilapia (Oreochromis niloticus). Two transitions were identified in the promoter region of the growth hormone gene (GH); eight nucleotide changes were identified in introns and promoter region of the IGF-I gene; and a transition (T/C) was identified in the Myogenin gene (MyoG). The highest genotypic frequency (0.8) for GHpA1 and MyoG was found in the GG and TT homozygous individuals, while the highest frequency (0.9) for GHpB1 was observed in the CT heterozygous fish. There was no genotypic frequency in the CC homozygous tilapia for the GHpB1 and MyoG markers. Based on their allelic frequencies, validation as novel single nucleotide polymorphisms (SNP) of those variations located at O. niloticus GH and MyoG genes was possible. These new markers will allow their association with growth traits in tilapia to be exploited in order to determine their potential use as assisted-selection markers.

Expression Profiles of IGF-1R Gene and Polymorphisms of its Regulatory Regions in Different Pig Breeds.

Insulin like growth factor 1 receptor (IGF-1R) is a candidate gene for growth and carcass traits in regulating animal growth, metabolism and endocrine. It is widely expressed in liver, muscle, bone tissues where the IGF-1R functions as a factor that promotes cell growth. In this study, the protein expression level of IGF-1R gene in liver and muscle tissues of three periods (birth, weaning and adult) of three pig breeds (BamaXiang pigs (BM), Tibetan pigs (TM) and Junmu No.1 pigs (JM)) were tested by western blot. SNPs within the regulatory region of pig IGF-1R gene were detected using direct sequencing and then the genotypes were identified through AS-PCR approach. Results showed expression profiles of IGF-1R gene between liver and muscle tissues were different and significant differences were also found among pig breeds. In the same time, four SNPs were detected in the regulatory region of IGF-1R gene, among which the genotype frequency of three (g.-1468G>C, g.-1192 C>T and g.330,424 C>T) were significantly different among the pig breeds. BM tended to heterozygous (GC/CT) of the anterior two loci, while TM and JM preferred the other two homozygotes respectively. For the g.330,424 C>T, all pig breeds were tended to be the heterozygous. In conclusion, the SNPs with different genotype distribution among the three pig breeds may explain the gene expression difference between the different pig breeds.

Distribution and linkage disequilibrium analysis of polymorphisms of GH1 gene in different populations of pigs associated with body size.

Growth hormone (GH) has been considered as a candidate gene for growth and body size in pigs. In this study, polymorphisms of the GH1 gene were evaluated for associations with body size traits in 190 pig individuals. Seventeen single-nucleotide polymorphisms (SNPs) were identified in GH1 gene of the large pig breeds and miniature pig breeds using direct sequencing and genotyped by allele-specific PCR approach. Notably, six (g.237A>G, g.283T>C, g.309A>G, g.318A>G, g.540A>G and g.544A>G) of them were significantly associated with body size, of which three loci (g.283T>C, g.309A>G, g.318A>G) located in the signal-peptide coding region of GH1 gene compose a CGG haplotype for large pigs and TAA haplotype for miniature pigs (P <0.001), two loci (g.540A>G and g.544A>G) located in the second intron of GH1 gene compose a GG haplotype for large pigs and AA haplotype for miniature pigs (P < 0.001). Our results demonstrate that these SNPs in GH1 gene are associated with the body size of pigs providing genetic basis for pig breeding with the improved economic benefits.

Co-localization of growth QTL with differentially expressed candidate genes in rainbow trout.

We tested whether genes differentially expressed between large and small rainbow trout co-localized with familial QTL regions for body size. Eleven chromosomes, known from previous work to house QTL for weight and length in rainbow trout, were examined for QTL in half-sibling families produced in September (1 XY male and 1 XX neomale) and December (1 XY male). In previous studies, we identified 108 candidate genes for growth expressed in the liver and white muscle in a subset of the fish used in this study. These gene sequences were BLASTN aligned against the rainbow trout and stickleback genomes to determine their location (rainbow trout) and inferred location based on synteny with the stickleback genome. Across the progeny of all three males used in the study, 63.9% of the genes with differential expression appear to co-localize with the QTL regions on 6 of the 11 chromosomes tested in these males. Genes that co-localized with QTL in the mixed-sex offspring of the two XY males primarily showed up-regulation in the muscle of large fish and were related to muscle growth, metabolism, and the stress response.