Use of high‐density SNP data to identify patterns of diversity and signatures of selection in broiler chickens

The development of broiler chickens over the last 70 years has been accompanied by large phenotypic changes, so that the resulting genomic signatures of selection should be detectable by current statistical techniques with sufficiently dense genetic markers. Using two approaches, this study analysed high‐density SNP data from a broiler chicken line to detect low‐diversity genomic regions characteristic of past selection. Seven regions with zero diversity were identified across the genome. Most of these were very small and did not contain many genes. In addition, fifteen regions were identified with diversity increasing asymptotically from a low level. These regions were larger and thus generally included more genes. Several candidate genes for broiler traits were found within these ‘regression regions’, including IGF1, GPD2 and MTNR1AI. The results suggest that the identification of zero‐diversity regions is too restrictive for characterizing regions under selection, but that regions showing patterns of diversity along the chromosome that are consistent with selective sweeps contain a number of genes that are functional candidates for involvement in broiler development. Many regions identified in this study overlap or are close to regions identified in layer chicken populations, possibly due to their shared precommercialization history or to shared selection pressures between broilers and layers.     

Prostaglandins F2α and E2 Secretion by Porcine Epithelial and Stromal Endometrial Cells on Different Days of the Oestrous Cycle

The endometrial tissue of the uterus plays a key role in reproduction and is a source of hormones and factors responsible for the proper physiological function of reproductive tract during the oestrous cycle and pregnancy. In this study, we investigated the pattern of PGF(2alpha) and PGE(2) secretion from cultured porcine endometrial cells at different days of the oestrous cycle. Epithelial and stromal cells were isolated by differential enzymatic digestion on days 6-8, 10-12 and 14-16. After attachment cells were incubated for 3 and 24 h to estimate PGF(2alpha) and PGE(2) output. The purity of culture was 85-90% for epithelial and 95-98% for stromal cells as determined by immunofluorescent staining. Release of PGF(2alpha) and PGE(2) was affected by cell type, days of the oestrous cycle and the time of incubation. After 3 h of incubation epithelial cells secreted more PGF(2alpha) than PGE(2) during all studied periods of the oestrous cycle (p < 0.01 and p < 0.001, respectively), whereas stromal cells released more PGE(2) (p < 0.01) on days 10-12 and 14-16. Longer incubation of stromal cells revealed that PGF(2alpha) output tended to overcome PGE(2) on days 10-16. The lowest secretion of prostaglandins was observed on days 6-8 in both cell types. The highest secretion of PGF(2alpha) from epithelium was measured on days 10-12 after 24 h of incubation when compared with other days studied (p < 0.001). In stromal cells, PGE(2) output increased on consecutive days studied (p < 0.001) after 3 h of incubation. The differential properties of endometrial cell types seem to play an important role in the profile of PGF(2alpha) and PGE(2) release before and during luteolysis. Described endometrial cells culture might serve as the model for further studies on the hormonal regulation of prostaglandin production in the pig.     

Bromsulphthalein and indocyanine green elimination from plasma, and urinary bromsulphthalein excretion, in normal cats

The elimination of bromsulphthalein (BSP) and indocyanine green (ICG) from plasma and urinary excretion of BSP were investigated in healthy cats. At 5 mg kg-1, BSP elimination fitted a two-compartment open model, with mean t1/2 beta of 7.1 (SD 2.5) minutes. A tendency for slower elimination of BSP at 10 mg kg-1 suggested saturation of excretory mechanisms, while at 2 mg kg-1 accurate dosing and assay of low BSP concentrations were difficult. Urinary recovery of BSP at 5 mg kg-1 was 0.01 to 0.13 per cent of the total dose. Plasma ICG (0.5 mg kg-1) data fitted a one-compartment open model, with mean t1/2 2.7 (SD 1.0) minutes. In cats, retention tests are more attractive than clearance tests because fewer blood collections are necessary. Proposed reference values are under 3.6 per cent retention of BSP (5 mg kg-1) at 30 minutes and under 17.5 per cent retention of ICG (0.5 mg kg-1) at 15 minutes. At present economic and technical factors favour BSP over ICG.