Insulin-like growth factor 2 (IGF2) is considered to be a regulator of post-natal growth and differentiation of the mammary gland. In the present work, associations of two single nucleotide polymorphisms in the bovine IGF2 gene with milk production traits were studied in dairy Holstein-Friesian cows: the already described g.8656C>T transition in exon 2 (RFLP-BsrI) and the newly found g.24507G>T transversion in exon 10 (RFLP-HaeIII), found by sequencing 273-bp exon 10 of the IGF2 gene in six individuals. Associations were analysed individually and in combination with the multi-trait repeatability test-day animal model. The CT/GT haplotype appeared to be associated with most of the milk traits studied (differences were significant at P < or = 0.001). The most frequent CT/GG haplotype seemed inferior to others in fat and protein content and daily yield of fat and protein but superior (together with the TT/GG genotype) when the daily milk yield is considered.

Myostatin (GDF-8) is a key protein responsible for skeletal muscle growth and development, thus mutations in the mstn gene can have major economic and breeding consequences. The aim of the present study was to investigate myostatin gene expression and transcriptional profile in skeletal muscle of Holstein-Friesian (Black-and-White) bulls carrying a polymorphism in the 5'-flanking region of the mstn gene (G/C transversion at position -7828). Real-time qRT-PCR and cDNA microarray revealed significantly lower mstn expression in muscle of bulls with the CC genotype, as compared to GG and GC genotypes. The direct comparison of skeletal muscle transcriptional profiles between the CC genotype and GG and GC genotypes resulted in identification of genes, of which at least some can be putative targets for myostatin. Using cDNA microarray, we identified 43 common genes (including mstn) with significantly different expression in skeletal muscle of bulls with the CC genotype, as compared to GG and GC genotypes, 15 of which were upregulated and 28 were downregulated in the CC genotype. Classification of molecular function of differentially expressed genes revealed the highest number of genes involved in the expression of cytoskeleton proteins (9), extracellular matrix proteins (4), nucleic acid-binding proteins (4), calcium-binding proteins (4), and transcription factors (4). The biological functions of the largest number of genes involved: protein metabolism and modification (10), signal transduction (10), cell structure (8), and developmental processes (8). The main identified signaling pathways were: Wnt (4), chemokines and cytokines (4), integrin (4), nicotine receptor for acetylocholine (3), TGF-beta (2), and cytoskeleton regulation by Rho GTPase (2). We identified previously unrecognized putatively myostatin-dependent genes, encoding transcription factors (EGR1, Nf1b, ILF1), components of the proteasomal complex (PSMB7, PSMD13) and proteins with some other molecular function in skeletal muscle (ITGB1BP3, Pla2g1b, ISYNA1, TNFAIP6, MST1, TNNT1, CALB3, CACYBP, and CTNNA1).

ABSTRACT:The effect of the insulin-like growth factor 2 (IGF2) gene polymorphism -a g.292C>T transition in exon 2 on feed uptake and conversion, growth rates, and meat production traits in Polish HolsteinFriesian cattle was investigated. A total of 291 young bulls were genotyped using restriction fragment length polymorphism (RFLP-BsrI). Animals were slaughtered at the age of 11 or 15 months and carcass traits were examined. At the age of 11 months the association was shown of the CC genotype with higher cold carcass weight, daily gain and meat content (%) in valuable cuts. At 15 months of age the CC genotype bulls showed higher live body weight, whereas those with the CT genotype had more fat in valuable cuts. The TT genotype bulls appeared to consume more feed (dry matter and protein) and used more feed for maintenance and meat production as compared to the CC genotype. The imprinting status of the IGF2 gene was analysed using cDNA sequencing and RFLP-BsrI. In 15-months-old animals and in foetuses older than two months both IGF2 alleles, maternal and paternal, were equally expressed in liver. In a 2-months-old male foetus the IGF2 mRNA was primarily expressed from the paternal allele.

The 5'-flanking regions (promoters) of the bovine α s1-, α s2-and β-casein genes were analysed for DNA sequence variants using PCR/RFLP in Polish Red (PR) and Black-and-White (BW) cattle. The polymorphic sites occurred at positions-1084 and-186 in the promoter region of the α s2-casein gene and at-728 and-109 in the α s1-and β-casein genes, respectively. These polymorphic sites were located within known potential regulatory sequences, suggesting an influence on the binding of transcription factors and expression of the bovine casein genes. Associations were found between various genotypes in the promoter region of the α s2-casein gene and α s1-and β-casein genotypes, thus showing the existence of intergenic haplotypes within the bovine casein locus. Milk proteins derived from cows of varying genotypes in the casein gene promoters were analysed using SDS-PAGE and HPLC techniques. It was shown that nucleotide sequence polymorphism in the promoter region of the bovine α s2-casein gene was associated with various contents of α s2-and β-casein in the milk. Bovine casein gene / 5'-flanking region / gene polymorphism / milk protein Résumé-Effet du polymorphisme de la séquence nucléotidique dans les régions 5'-noncodantes des gènes de la caséine bovine sur la teneur en caséine du lait de vache. Les variants de la séquence ADN dans les régions 5'-non codantes des gènes de caséines α s1 , α s2 et β des vaches de races pie-noir et rouge polonaises ont été analysés à l'aide de la méthode PCR/RFLP. Des polymorphismes ont été constatés dans les positions-1084 et-186 de la région promotrice du gène de la caséine α s2 et dans les positions-728 et-109 des gènes de la caséine α s1 et β, respectivement. Ces sites polymorphiques ont été localisés dans les séquences régulatrices potentielles, ce qui suggére leur influence sur la liaison des facteurs de transcription et l'expression des gènes de la caséine bovine. Des associations parmi les différents génotypes dans la région promotrice du gène de la caséine α s2 et les génotypes de la caséine α s1 et β ont été établies. Cela signifie que les haplotypes préférés existent dans le locus des caséines bovines. Les protéines du lait de vache de génotypes différents dans les promoteurs du gène de la caséine ont été analysées à l'aide de la technique SDS-PAGE et HPLC. Il y a été demontré que le polymorphisme de la séquence de nucléotides dans la région de promoteur du gène bovin de la caséine est lié avec les différentes teneurs en caséines α s2 et β dans le lait. Gène de la caséine bovine / région 5'-non codante / polymorphisme / protéine du lait

Allelic expression imbalance (AEI) is an important genetic factor being the cause of differences in phenotypic traits that can be heritable. Studying AEI can be useful in searching for factors that modulate gene expression and help to understand molecular mechanisms underlying phenotypic changes. Although it was commonly recognized in many species and we know many genes show allelic expression imbalance, this phenomena was not studied on a larger scale in cattle. Using the pyrosequencing method we analyzed a set of 29 bovine genes in order to find those that have preferential allelic expression. The study was conducted in three tissues: liver, pituitary and kindey. Out of the studied group of genes 3 of them—LEP (leptin), IGF2 (insulin-like growth factor 2), CCL2 (chemokine C–C motif ligand 2) showed allelic expression imbalance.Electronic supplementary materialThe online version of this article (doi:10.1007/s11033-012-2161-3) contains supplementary material, which is available to authorized users.

The objective of the study reported in this Research Communication was to investigate the association of polymorphisms in the insulin-like growth factor receptor 2 (IGF2R) gene with milk traits in 283 Polish Holstein-Friesian (PHF) cows from the IGAB PAS farm in Jastrzębiec. IGF2R regulates the availability of biologically active IGF2 which is considered as a genetic marker for milk or meat production in farm animals. Two novel genetic polymorphisms were identified in the bovine IGF2R gene: a polymorphic TG-repeat in intron 23 (g.72389 (TG)15-67), and a g.72479 G > A SNP RFLP-StyI in exon 24. The following milk traits were investigated: milk yield, protein and fat yield, SCC and lactose content. To determine the influence of the IGF2R STR and SNP genotypes on the milk traits, we used the AI-REML (average information restricted maximum likelihood) method with repeatability, multi-trait animal model based on test-day information using DMU package. Statistical analysis revealed that the G/A genotype (P ≤ 0·01) was associated with milk and protein yield, lactose content and somatic cell count (SCC) in Polish HF cows. TGn (29/22, 28/29, 28/22, 28/28) genotypes were associated with high values for milk, (28/22, 28/23) with protein and fat yield, (25/20) with lactose content, and (29/33, 28/28) with low SCC. We suggest that the IGF2R gene polymorphisms could be useful genetic markers for dairy production traits in cattle.

Myostatin (GDF-8) is a key protein responsible for skeletal muscle growth and development so mutations in the mstn gene can have major economic and breeding consequences. The aim of the present study was to investigate polymorphism in the 5'flanking region of the mstn gene and its possible influence on the myostatin level in skeletal muscles of Polish Black-and-White bulls. The relation between expression of myostatin and another member of the TGF-β superfamily, TGF-β 1 , was also examined. We uncovered polymorphism in the 5'flanking region of the mstn gene: G/C substitution at position -7828 (relative to translation start codon ATG). The most frequent genotype was GC (43.6%), followed by genotypes CC (34.2%) and GG (22.2%). The concentration of the active form of myostatin (26 kDa) in M. semitendinosus of homozygotes (CC) was the lowest, whereas the expression of this cytokine in heterozygotes was the highest. The changes in mstn expression did not, however, influence average carcass traits (weight of valuable cuts and weight of lean in valuable cuts). The pattern of differences in the TGF-β 1 concentration corresponded to that observed for myostatin.