Expression of microRNAs and their target genes and pathways associated with ovarian follicle development in cattle.

Development of ovarian follicles is controlled at the molecular level by several gene products whose precise expression leads to regression or ovulation of follicles. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression through sequence-specific base pairing with target messenger RNAs (mRNAs) causing translation repression or mRNA degradation. The aim of this study was to identify miRNAs expressed in theca and/or granulosa layers and their putative target genes/pathways that are involved in bovine ovarian follicle development. By using miRCURY microarray (Exiqon) we identified 14 and 49 differentially expressed miRNAs (P < 0.01) between dominant and subordinate follicles in theca and granulosa cells, respectively. The expression levels of four selected miRNAs were confirmed by qRT-PCR. To identify target prediction and pathways of differentially expressed miRNAs we used Union of Genes option in DIANA miRPath v.2.0 software. The predicted targets for these miRNAs were enriched for pathways involving oocyte meiosis, Wnt, TGF-beta, ErbB, insulin, P13K-Akt, and MAPK signaling pathways. This study identified differentially expressed miRNAs in the theca and granulosa cells of dominant and subordinate follicles and implicates them in having important roles in regulating known molecular pathways that determine the fate of ovarian follicle development.

Frequencies of alleles and genotypes of the PRNP gene in Polish Red, Czech Pied and Czech Black-and-White cattle.

Frequencies of alleles and genotypes of the PRNP gene in 65 Polish Red cows kept under a conservation programme and 52 randomly chosen cows of two Czech breeds: Czech Pied (42) and Black-and-White (10) were studied. All cows were at the age of 4 years or older. It was found that the frequency of allele 5 (5 copies of the octapeptide repeat) ranged from 0.11 (Polish Red) to 0.00 (Czech Black-and-White) whereas the frequency of allele 6 (6 copies of the octapeptide repeat) ranged from 1.00 (Czech Black and White) to 0.89 (Polish Red). The highest frequency was found for the homozygous genotype 6/6 (1.00 in Czech Black-and-White) and the lowest frequency was detected for the heterozygous genotype 6/5 (0.143). In the studied cows the genotype 5/5 was not found. The higher frequency of allele 5 in the native breeds and its lower frequency or lack of this allele in the populations intensively selected for high milk production may suggest that alleles of the PRNP gene may be associated with milk production.

[Biochemical and morphological changes in blood during growth of heifer during the 1st pregnancy and lactation in cows]. / Zmiany biochemiczne i morfologiczne krwi w okresie wzrostu u jalówek oraz pierwszej ciazy i laktacji u krów

The investigations were conducted on 18 heifers from the birth to conception, and on 16 cows from the conception to the end of the first lactation. The levels of some blood indices (total protein, protein fractions, urea, erythrocytes, leucocytes, haemoglobin, haematocrit) were examined every month. There was obtained a high agreement between the data collected by the present writer and those published by other authors. Significant changes in the level of total protein and of protein fractions in blood serum were observed mainly at the beginning of the growth period, at the end of pregnancy and in the first months of lactation. The morphological appearance of peripheral blood showed high variability during the growth period in heifers, but more stability during pregnancy and lactation in cows. The variability of the urea levels in blood serum depended more upon feed rations than on the stage of growth, on pregnancy or lactation.