An understanding of what effects particular genes can have on body parameters in productive animals is particularly significant for the process of marker-assisted selection. The gene of transcriptional factor CCAAT/enhancer-binding protein delta (CEBPD gene) is involved in the process of growth in animals and is known to be a promising candidate for use as a genomic marker. The structure of the CEBPD gene locus was determined using NimbleGen sequencing technology (Roche, USA). The effect of polymorphisms, which were identified using the aforementioned technology, was investigated in 30 rams of the Manych Merino sheep breed. Twenty-two single nucleotide polymorphisms (SNP) were detected in the CEBPD gene locus. Significantly, two SNPs, namely, g.315T>G and g.327C>T, have been identified for the first time. It was demonstrated that the complex of linked SNPs, consisting of g.301A>T, g.426T>C, and g.1226T>C, had a negligible effect on body parameters in Manych Merino sheep. Animals with the heterozygous type of SNP g.1142C>T exhibited changes solely in the chest and croup width. The newly discovered SNP g.327C>T was proven to have a negative effect on live weight and body size (p < 0.05) in Manych Merino sheep. Sheep with the heterozygous type of g.562G>A and g.3112C>G SNP complex showed an increase in live weight and dimensions (p < 0.05) compared with those of wild homozygous type. Consequently, SNPs g.327C>T, g.562G>A, and g.3112C>G in the CEBPD gene locus can be successfully used as markers in sheep breeding. Future research will evaluate the influence of the aforementioned SNPs on slaughter indicators for sheep meat production.
Candidate genes associated with meat productivity often affect the performance of myostatin and muscle development in general. The MyoD1 gene is a member of the myogenic regulatory factor (MRF) family and plays a key role in the differentiation of skeletal muscle cells in vertebrates. We investigated the structure of the MyoD1 gene. The effect of polymorphisms on meat production was studied in the Russian sheep breed Manych Merino. To detect alleles, we used NimbleGen sequencing technology (Roche, USA). In the Manych Merino breed, we found 14 single nucleotide polymorphisms (SNPs) associated with substitutions, all in the second exon, namely, c.244C>T, c.246G>T, c.253G>T, c.259G>C, c.261C>T, c.269C>G, c.274C>A, c.276C>G, c.277C>A, c.279C>T, c.281C>A, c.287C>A, c.325T>C, and c.483C>T. All of these SNPs, except from c.325T>C, were detected here for the first time. The Manych Merino breed had 13 substitutions that were present as homozygous type. Only SNP c.325T>C occurred as the wild type of homozygotes and heterozygotes in the ratio 2:1. We found that SNP c.325T>C was associated with some vital body parameters, including parameters of height and croup measurement. Thus, the determination of allelic variants of the MyoD1 gene may be used in marker assisted genetic selection schemes.
The aim of the research was to study the dynamics of thyroid hormones and thyroid-stimulating hormone of the pituitary gland in Stavropol breed sheep in postnatal ontogenesis and the establishment of thyroid status in animals before insemination, during pregnancy and after childbirth. Determination of concentration of total triiodothyronine, free thyroxine and thyroid stimulating hormone in serum was performed by solid-phase enzyme immunoassay (ELISA) using standard test systems. As a result of the studies, the level of thyroid hormones and thyroid-stimulating hormone in the blood of sheep of Stavropol breed in postnatal ontogenesis was determined. It was established that at the birth of lambs, the lowest level of triiodothyronine (2.55 ± 0.04 nmol/l), thyroxine (19.47 ± 0.45 pmol/l) and thyrotropic (0.31 ± 0.05 Mme/ml) hormone was observed in the blood, compared with other age periods. By the age of three months, the levels of triiodothyronine and thyroxine increased significantly by 7.7% and 24.8%, respectively. When comparing the data in six monthly young ewes, the concentration of all studied hormones was the highest in comparison with other age groups (triiodothyronine – 3.11 ± 0.21 nmol/l; thyroxine – 26.29 ± 0.97 pmol/l; thyrotropic hormone – 0.81 ± 0.09 Mme/ml). In the age of nine months, a significant decrease in triiodothyronine by 16.8%, thyroxine - by 13.2% and thyroid-stimulating hormone - by 34.6% was observed, compared with ewes of 6 month old. By the age of 12 months, only free thyroxine was significantly changed, its serum concentration increased by 9.5% and amounted to 25.21 ± 0.31 pmol/l, compared with the data of nine-month-old sheep. It was found that the concentration of triiodothyronine changes significantly in sheep after childbirth and is 2.53 ± 0.03 nmol/l, which is 6.3% more than in pregnant ewes. The level of thyroxine on the 90th day of pregnancy decreases by 5.3%, and by the 135th day by 16%, compared with the previous period of the study. Thyroid-stimulating hormone in the blood serum of sheep on the 90th day of pregnancy becomes significantly lower by 29% (p ⩽ 0.05) than its concentration in non-pregnant ones. After childbirth, thyroid-stimulating hormone significantly increased by 26.66% (p ⩽ 0.05). As a result of the studies, in sheep of Stavropol breed, standard sizes of the level of thyroid gland hormones (triiodothyronine, thyroxine) and thyroid-stimulating hormone were established.
The purpose of the study was to research the activity of nucleolar organizers of blood lymphocytes in large white breed pigs in postnatal ontogenesis and during pregnancy. The prepared blood smears were stained with silver nitrate (AgNO3) and additionally stained with azur and eosin. By measuring the parameters of the nucleus and nucleolar organizers’ activity (AgNORs), the changes in the morphological and functional state of the protein synthesizing apparatus of blood lymphocytes in large white breed pigs in postnatal ontogenesis were evaluated. It was found that the area of lymphocyte nuclei in newborn piglets was 83.72±3.37 mm2. By the age of three months, the area of the lymphocyte nuclei of pigs significantly increased by 13.41% (p⩽0.05) and amounted to 96.69±2.57 mm2, at the age of six months this indicator was 15.78% more than at the age of three months (114.80±3.69), by the age of nine months the number of AgNORs significantly (p⩽0.05) decreased by 11.32% compared to six-month-old animals (101.80±2.97). From 1 to 4 units of AgNORs are detected in the lymphocyte nuclei. By the age of three months, the total area of nucleolar organizers’ zones decreased by 29.30% (p⩽0.05), and by the age of twelve months increased by 16.72% (p⩽0.05) compared to the previous age period. A slight increase in the area of the lymphocyte nucleus was observed in pigs after delivery by 9.15% (p⩽0.05). After delivery, the number of AgNORs in pigs significantly increased by 11.26% (p⩽0.05). During pregnancy, from 1 to 3 AgNORs were detected in pigs with a total area of 4.29±0.27 to 4.33±0.30 microns. Based on the conducted research, it can be concluded that the functional state of lymphocytes undergoes obvious changes in postnatal ontogenesis and during pregnancy, this can be seen in alterations in the area of their nuclei, the number and total area of AgNORs.
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