The Levels of Genetic Differentiation of Small-Tailed Han Sheep and Tan Sheep Populations Using Structural Loci

Using the method of ＂random sampling in typical colonies of the central area of the habitat＂ and several electrophoresis techniques, the variations of 17 structural loci encoding blood proteins in 60 Small-Tailed Han sheep and 73 Tan sheep were examined and compared with those of 14 other sheep populations in China and other countries to investigate their levels of genetic differentiation. The average heterozygosities of Small-Tailed Han sheep and Tan sheep were 0.2360 and 0.2587, respectively. The average polymorphic information content values were 0.1974 and 0.2102, respectively. The average effective numbers of alleles were 1.5723 and 1.5751, respectively. The coefficients of gene differentiation in the four groups （including 4, 6, 13, and 16 sheep populations, respectively） were 0.049323, 0.059987, 0.1728, and 0.201256, respectively, indicating that the degree of gene differentiation at the structural loci was the least in Hu sheep, Tong sheep, Small-Tailed Hart sheep, and Tan sheep; followed by the above-mentioned four sheep populations and two Mongolian sheep populations; and was the highest in sheep populations belonging to the Mongolian sheep group, South Asian sheep, and European sheep. The earlier researchers＇ conclusions that both Small-Tailed Han sheep and Tan sheep evolved from Mongolian sheep were further verified by the results of this study. Hu sheep, Tong sheep, Small-Tailed Han sheep, and Tan sheep were decreasingly affected by the bloodline of Mongolian sheep to different degrees. The relationships among sheep populations were not closely related to the geographical distances among sheep populations.

Histopathological Analysis of Liver During Pregnancy Toxemia in Small-tailed Han Sheep

The present work aimed to investigate the microscopic and ultramicro- scopic structure of the liver to assess the level of hepatic impairment during preg- nancy toxemia. Seven pregnant small-tailed Han sheep of negative urine ketone bodies were assessed in this study. Toxemia was induced by limiting food and movement tate in pregnancy. Three sheep developed obvious clinical symptoms with motor weakness, depression, anorexia, locomotion disturbances, blindness and lan- guishment. We harvested their liver tissues as pathological material, and used rou- tine histological and electronic microscopy methods to observe the histopathological changes in small-tailed Han sheep induced by pregnancy toxemia. Autopsy of the livers of the sheep revealed deep yellow coloration, intumescence and hemorrhage on the surface. Microstructural features indicated fatty degeneration, which is a main characteristic of fatty liver. Hepatocellular ultrastructural changes were observed un- der an electronic microscope. The characteristic findings were nucieolus concentra- tion, vacuolation of mitochondria and excessive glycogen granules in the cytoplasm. Via this experimental protocol, pregnancy toxemia of sheep was successfully in- duced, providing a pathological model for the study of this disease. After the experi- mental induction of pregnancy toxemia, the clinical symptoms of pathogenic sheep and pathological changes to their livers exhibited obvious characteristics of pregnan- cy toxemia.