Abnormal meiosis in fertile and sterile triploid cyprinid fish

Meiosis is the key process for producing mature gametes. A natural fertile triploid Carassius auratus population(3nDTCC) and an artificially derived sterile triploid crucian carp(3nCC) have been previously observed, providing suitable model organisms for investigating meiosis characteristics in triploid fish. In the present study, the microstructures and ultrastructures of spermatogenesis were studied in these fishes. Td T-mediated d UTP nick end labeling detection was performed to investigate the apoptosis of spermatocytes. Fluorescence in situ hybridization was employed to trace chromatin pairing. In addition, the m RNA expressions of cell cycle-related genes(i.e., cell division control 2 and cell cycle protein B) were determined by quantitative realtime polymerase chain reaction to illustrate the molecular mechanism of abnormal meiosis in the 3nCC. The results showed that the 3nCC undergoes an irregular prophase I, with the chromosomes distributed in a unipolar radial manner and exhibiting partial pairing, hindered metaphase I, and degenerated cells in the subsequent stages. Meanwhile, the 3nDTCC presented a relatively regular meiotic prophase I with complete conjugate chromosome pairs and chromosomes distributed along the karyotheca,which were presented as a ring structure by slicing. Only the spreads with 130–150 irregular chromosomes can be easily detected in the 3nDTCC, suggesting that it may undergo an abnormal metaphase I. This study provides new insights into the meiosis of fertile and sterile triploid cyprinid fish.

Clinical and immune response characteristics among vaccinated persons infected with SARS-CoV-2 delta variant:a retrospective study

Objective:This study aimed to observe the clinical and immune response characteristics of vaccinated persons infected with the delta variant of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)in Yangzhou,China.Methods:We extracted the medical data of 129 patients with delta-variant infection who were admitted to Northern Jiangsu People’s Hospital(Yangzhou,China)between August and September,2021.The patients were grouped according to the number of vaccine doses received into an unvaccinated group:a one-dose group and a two-dose group.The vaccine used was SARS-CoV-2-inactivated vaccine developed by Sinovac.We retrospectively analyzed the patients’epidemiological,clinical,laboratory,and imaging data.Results:Almost all patients with delta-variant infection in Yangzhou were elderly,and patients with severe/critical illness were over 70 years of age.The rates of severe/critical illness(P=0.006),fever(P=0.025),and dyspnea(P=0.045)were lower in the two-dose group than in the unvaccinated group.Compared to the unvaccinated group,the two-dose group showed significantly higher lymphocyte counts and significantly lower levels of C-reactive protein(CRP),interleukin-6(IL-6),and D-dimer during hospitalization and a significantly higher positive rate of immunoglobulin G(IgG)antibodies at admission(all P<0.05).The cumulative probabilities of hospital discharge and negative virus conversion were also higher in the two-dose group than in the unvaccinated group(P<0.05).Conclusions:Two doses of the SARS-CoV-2-inactivated vaccine were highly effective at limiting symptomatic disease and reducing immune response,while a single dose did not seem to be effective.