RESUMEN
The Cenozoic retreat of the Paratethys Sea, as well as uplift of the Tibet plateau and global cooling, have been considered as the main mechanisms for the onset of the Asian monsoon. However, due to the weak constraints on the time and path of the Paratethys Sea, the relative contribution of each of the three factors to the onset of the Asian monsoon remains debatable. Previous studies on the retreat process of the Paratethys suggested that its east coastline had already withdrawn from the Chinese Tianshan area to the west by the Oligocene. Here, we provide a new perspective on this discussion through the study of the Oligocene Anjihaihe dolomite from the northern Chinese Tianshan. Through the comparisons of carbon, oxygen, magnesium, and strontium isotope compositions between the dolomite beds and their interlayered precursor lacustrine limestone beds, we show that the Anjihaihe dolomites were formed at the end of the Oligocene from dolomitization by a fluid characterized by high δ18O, low δ26Mg, low temperature, relatively poor in carbon and Sr. This fluid was likely derived from seawater from the close-by Paratethys Sea at the time. This discovery suggests a larger Paratethys Sea during the Oligocene than previously thought and may have important implications to understand the evolution of the palaeogeography in the Chinese Tianshan region and the onset of the Asian monsoon.
RESUMEN
Eight-week-old male Kunming mice were administered either melamine (MA, 30, 140, or 700 mg/kg/day), a melamine and cyanuric acid mixture (MC, each at 15, 70, or 350 mg/kg/day), or vehicle (control) for 3 consecutive days. Testicular toxicity was evaluated on days 1 and 5 after the final exposure. The testicular and epididymal weights and serum testosterone level were significantly decreased in the highest MC group (350 mg/kg/day). Histopathologically, both MA and MC caused obvious lesions in the testis and epididymis, with significant increases in sperm abnormalities. By TEM, the blood-testis barrier was damaged dose dependently. TUNEL staining showed that both MA and MC induced increases in germ cell apoptosis. The Sertoli cell vimentin was collapsed in the treated animals as detected by immunohistochemical staining and Western blotting. This study demonstrated that both MA and MC treatments could disrupt the blood-testis barrier and cause a clear testicular toxicity.
Asunto(s)
Enfermedades Testiculares/inducido químicamente , Triazinas/toxicidad , Animales , Apoptosis/efectos de los fármacos , Barrera Hematotesticular/efectos de los fármacos , Barrera Hematotesticular/ultraestructura , Peso Corporal/efectos de los fármacos , Epidídimo/patología , Masculino , Ratones , Tamaño de los Órganos/efectos de los fármacos , Células de Sertoli/patología , Espermatozoides/anomalías , Espermatozoides/efectos de los fármacos , Enfermedades Testiculares/patología , Testículo/patología , Testosterona/sangreRESUMEN
Rabbit hepatitis E virus (HEV) is a novel genotype of HEV, and is considered to pose a risk of zoonotic transmission. Research into the systemic distribution of rabbit HEV in rabbits during different periods of infection has rarely been reported. To better understand this virus, we infected rabbits with second-passage rabbit HEV via an intraperitoneal route. After inoculation, the infection showed two types, temporary and constant infection. The detection of HEV RNA in the feces varied with time, and serum antigen correlated with fecal HEV RNA. Viremia only appeared 72 days after inoculation. The rabbits remained antibody negative throughout the experimental period. When HEV was localized, several organs besides the liver were HEV RNA positive. Tissue antigen was observed immunohistochemically in the different cells of various organs, especially in parts of the small intestine and the characteristic rabbit gut-associated lymphoid tissue. These data provide valuable information for future research into the pathogenesis of HEV.