New polymorphism in the 5' flanking region of IGF-1 gene and its association with wool traits in Egyptian Barki sheep

Influence of single nucleotide polymorphism in the IGF-1 gene on performance and conformation traits in Munjal sheep

Genetic polymorphism research in livestock species aims to assess genetic differences within and among breeds, primarily for conservation and development objectives. The aim of the present study was to determine the point mutation in the IGF-1 gene (g.855G>C and g.857G>A) and its association with performance traits in Munjal sheep. In total, 50 Munjal sheep were selected and the genomic DNA was isolated using the Automated Maxell RSC DNA/RNA purification system and the Maxwell RSC whole blood DNA kit. A reported set of primers was used to amplify the 294-bp fragment encompassing the targeted region, i.e. the 5' flanking region of the IGF-1 gene. The polymerase chain reaction product of 294-bp size harbouring the g.857G>A mutation in the 5' flanking region of the IGF-1 gene was digested with HaeII enzyme. Three possible genotypes were defined by distinct banding patterns, i.e. GG (194, 100 bp), GA (294, 194, 100 bp) and AA (294 bp) in the studied population of Munjal sheep. The genotypic and allelic frequencies of g.857G>A single nucleotide polymorphism of the IGF-1 gene indicated that the frequency of the A allele was higher in the studied population, i.e. 0.59 and the GA genotype was found to be the predominant genotype (0.66). Allele A of the IGF-1 gene was found to be associated with higher body weights and can be used in selection criteria for improving the performance of Munjal sheep. The positive effect of the IGF-1 gene on several conformational traits as observed in this study suggests that this area of the ovine IGF-I gene is particularly important and warrants further investigation on a larger population size.

Genomic Regions Associated with Wool, Growth and Reproduction Traits in Uruguayan Merino Sheep

The aim of this study was to identify genomic regions and genes associated with the fiber diameter (FD), clean fleece weight (CFW), live weight (LW), body condition score (BCS), pregnancy rate (PR) and lambing potential (LP) of Uruguayan Merino sheep. Phenotypic records of approximately 2000 mixed-age ewes were obtained from a Merino nucleus flock. Genome-wide association studies were performed utilizing single-step Bayesian analysis. For wool traits, a total of 35 genomic windows surpassed the significance threshold (PVE ≥ 0.25%). The proportion of the total additive genetic variance explained by those windows was 4.85 and 9.06% for FD and CFW, respectively. There were 42 windows significantly associated with LWM, which collectively explained 43.2% of the additive genetic variance. For BCS, 22 relevant windows accounted for more than 40% of the additive genetic variance, whereas for the reproduction traits, 53 genomic windows (24 and 29 for PR and LP, respectively) reached the suggestive threshold of 0.25% of the PVE. Within the top 10 windows for each trait, we identified several genes showing potential associations with the wool (e.g., IGF-1, TGFB2R, PRKCA), live weight (e.g., CAST, LAP3, MED28, HERC6), body condition score (e.g., CDH10, TMC2, SIRPA, CPXM1) or reproduction traits (e.g., ADCY1, LEPR, GHR, LPAR2) of the mixed-age ewes.

Association of single nucleotide polymorphisms in the CAPN, CAST, LEP, GH, and IGF-1 genes with growth parameters and ultrasound characteristics of the Longissimus dorsi muscle in Colombian hair sheep

Recognition of the genes that influence livestock production characteristics has allowed researchers to identify single nucleotide polymorphisms (SNPs) associated with phenotypic traits that contribute to higher productivity. The objective of this research was to associate SNPs in the genes calpain (CAPN), calpastatin (CAST), leptin (LEP), growth hormone (GH), and insulin-like growth factor 1 (IGF-1) with the growth characteristics birth weight (BW), weaning weight adjusted at 120 days (WW), daily pre-weaning gain (PRADG), adjusted weight at 210 days (AW210), and daily post-weaning gain (POADG), and the measures of the Longissimus dorsi muscle based on ultrasound, namely loin eye area (LEA), loin depth (LD), and back fat thickness (BFT), in Colombian hair sheep (OPC). The association between phenotypic and genotypic characteristics was made using the PLINK v.1.9 program using linear regression analysis. There was a statistically significant association (p < 0.05) between the CAST polymorphism (M/N) and BW, a tendency (p = 0.07) for an association between the T → C SNP of the CAPN gene and AW210, and a trend (p = 0.07) for an association between the A → G SNP of the IGF-1 locus and POADG. The LEA and BFT characteristics were not associated with a SNP, while PL was significantly affected by SNPs in the GH and IGF-1 genes. In conclusion, all the genes evaluated were polymorphic, the CAST gene significantly influenced BW, and the GH and IGF-1 genes were associated with LD characteristics. These results could be used to identify individuals with favorable genotypes to implement a marker-assisted selection method.

A variant associated to IGF-1 mRNA and protein expression in sheep

The insulin-like growth factor-1 (IGF-1), a key hormone in muscle development was investigated for single-nucleotide polymorphisms (SNPs) upstream of the IGF-1 gene and their effects upon its cognate mRNA and hormone levels in sheep. A 70 d feeding trial was conducted with 22 F1 (Dorper × Pelibuey) lambs, individually allocated and fed a diet with a forage-to-concentrate ratio of 36:64 and 17% crude protein. Sequence analyses of 265 bp upstream the IGF-1 gene revealed the variant NC_040254.1:g.[184028491G > C;184028493G > A]. These SNPs generate alleles A and B, with frequencies of 0.66 and 0.34 in F1 lambs and of 0.73 and 0.27 in 81 pure Dorper lambs, respectively. Females were grouped by genotype AA, AB and BB (n = 3). IGF-1 hormone concentrations at 14, 42 and 70 d were higher (p < 0.05) in AA lambs compared to AB + BB lambs. The IGF-1 mRNA level was 2.6-fold higher in AA animals (n = 5, p < 0.05) than in AB + BB lambs (n = 7). A DNA binding site for the Inhibitor of Growth family member 4 (ING4) was found in allele B but not in allele A, which could explain the lower mRNA and hormone expression levels for AB + BB animals. The variant reported here appears to function as an eQTL with a negative effect on the level of IGF-1.

Nucleotide Sequence Variation in the Insulin-Like Growth Factor 1 Gene Affects Growth and Carcass Traits in New Zealand Romney Sheep

Insulin-like growth factor 1 (IGF1) is a mediator of the effects of growth hormone and polymorphism in the IGF1 gene (IGF1) is reported to affect fat deposition in some livestock species. In this study, nucleotide sequence variation in three regions of ovine IGF1 (part of the 5′ flanking region, the exon 3 region, and the exon 4 region) was investigated in 848 New Zealand Romney lambs using PCR-single strand conformation polymorphism (SSCP) analyses to ascertain if single nucleotide polymorphisms (SNPs) existed. Six SNPs were identified across these three regions. The effect of the sequence variation in the exon 3 and exon 4 regions on growth and carcass traits were investigated. One of the PCR-SSCP sequence variants in the exon 3 region was associated with variation in hot carcass weight, carcass fat depth at the 12th rib measured using video imaging and the percentage proportion of leg lean meat, whereas the other was associated with variation in growth rate to weaning. No associations were detected for the other gene regions analyzed. The results suggest that polymorphism in exon 3 of ovine IGF1 has potential for use as a gene-marker for some carcass and growth traits.

Polymorphism of insulin-like growth factor 1 gene and its relationship with reproductive performances and milk yield in Sarda dairy sheep

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IGF-1 gene plays an important role in regulating reproduction in ruminants.

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Here three SNPs were found in the IGF-I gene in Sarda sheep.

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The found SNPs were related to reproductive performance and milk yield.

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This results could be used to improve the reproductive performances and milk yield in Sarda sheep.

The aim of this research was to detect polymorphisms within the IGF-I gene in dairy sheep and to verify their influence on milk yield and reproductive performances. Four hundred Sarda ewes in their second lactation were selected from 2 farms. Their reproductive traits (fertility rate, interval in days from ram introduction to lambing and litter size) and milk yield were recorded, from the second to the fourth lactation. DNA was extracted from individual blood samples and subjected to amplification and sequencing of the IGF-I gene 5′ UTR and Exon 3 regions. Three polymorphic sites were recorded at positions g184028491C>G and g184028489C>T of the 5′UTR, and g184023223G>A of the Exon 3. The C allele at position g184028491 showed a significant association with higher fertility rate (P < 0.05) and a shorter interval in days from ram introduction to lambing (P < 0.01). In addition, a significant effect of the CC genotype was found with higher milk yield for P < 0.05 in the second and third lactation, and P < 0.01 in the fourth lactation compared to the other genotypes. Even, AA genotype at position g184023223 of the exon 3 showed a positive significant effect on milk yield for P < 0.05, in the second and third lactation, and for P < 0.01 in fourth lactation compared to the other genotypes. In conclusion the found SNPs showed a significant influence on reproductive performances and milk yield in Sarda sheep breed suggesting a possible application in sheep selection plans.

Comparative analysis of IGFBP-3 gene sequence in Egyptian sheep, cattle, and buffalo

OBJECTIVE

A total of 205 animals from four Egyptian livestock species; cattle (n = 18), buffaloes (n = 12), sheep (n = 150) and goats (n = 25) were used in this study to detect polymorphism and perform comparative analysis for IGFBP-3 gene using DNA sequencing and (PCR-RFLP).

RESULTS

The amplified fragments were found to be of length 654 bp in sheep, 651 bp in cattle and 655 bp in buffalo. For Falahy goats, PCR was performed to amplify a 316 bp fragment from exon 2 of the IGFBP-3 gene. The digestion of 654 bp with HaeIII restriction enzyme yielded a single restriction pattern for goats, while for cattle, 3 genotypes were identified; (AA), (AB), and (BB). Moreover, for buffalo one genotype (AA) only was found with HaeIII and TaqI restriction enzymes, separately. Also, the digestion profile for goats with HaeIII revealed one pattern only. Nucleotide sequencing of the amplified fragments of IGFBP-3 gene in sheep, cattle, buffalo, and goat was submitted to the NCBI GenBank (Accession no. MG738671.1, MG738673.1, MG738674.1, and MG738672.1, respectively). The nucleotide sequencing analysis indicated similarity percentages in IGFBP-3 gene fragments of 88.54, 89.63 and 95.06% between "sheep and cattle", "sheep and buffalo", and "cattle and buffalo", respectively.