摘要: Hibernation is one of the fundamental strategies in response to cold environmental temperatures. During hibernation, the endocrine and circadian systems ensure minimal expenditure of energy for survival. The circadian rhythms of key hormones, melatonin (MT), corticosterone (CORT), triiodothyronine (T-3), and thyroxine (T-4), and the underlying molecular regulatory mechanisms of hibernation have been well determined in mammals but not in ectotherms. Here, a terrestrial hibernating species, Asiatic toad (Bufo gargarizans), was employed to investigate the plasma CORT, MT, T-3, and T-4; and the retina, brain, and liver mRNA expression of the core clock genes, including circadian locomotor output cycles kaput (Clock), brain and muscle ARNT-like 1 (Bmal1), cryptochrome (Cry) 1 and 2, and period (Per) 1 and 2, at 7-time points over a 24-h period under acute cold (1 day at 4 degrees C), and hibernation (45 days at 4 degrees C). Our results showed that the circadian rhythms of the core clock genes were rather unaffected by acute cold exposure in the retina, unlike the brain and liver. In contrast, during hibernation, the liver clock genes displayed significant circadian oscillations, while those in the retina and brain stopped ticking. Furthermore, plasma CORT expressed circadian oscillations in both groups, and T-3 in acute cold exposure group, whereas T-4 and MT did not. Our results reveal that the plasma CORT and the liver sustain rhythmicity when the brain was not, indicating that the liver clock along with the adrenal clock synergistically maintains the metabolic requirements to ensure basic survival in hibernating Asiatic toads.

摘要: Mucosal vaccination, which has the potential to induce both mucosal and systemic immune responses, is considered the most suitable method of preventing infectious diseases in farmed fish. Aeromonas veronii and Edwardsiella ictaluri are two pathogenic bacteria found in yellow catfish and often infect the fish through mucosal surfaces. Delivery of a bivalent inactivated vaccine by injection has been shown to induce a strong systemic immune response against both bacterial infections. However, mucosal immune responses and protective efficiency induced by this inactivated vaccine administrated via immersion are yet to be investigated. We developed a bivalent vaccine containing formalin-inactivated A. veronii and E. ictaluri and evaluated the immune response in yellow catfish after immersion vaccination using body fluids biochemistry indices, agglutinating antibody titers, and the expression level of immune-related genes in the skin, gills, spleen, and head kidney. The activities of innate immune-related enzymes and specific agglutination antibody titers in body fluids, as well as the expression of innate and adaptive immune-related genes in both the mucosal and systemic tissues of vaccinated fish, were significantly higher than that in control fish. Next, we assessed the protective efficacy by a challenge model of virulent strains of E. ictaluri and A. veronii. The relative survival percent of vaccinated fish was 80% and 87% after challenging fish with E. ictaluri and A. veronii, respectively, which was higher than unvaccinated control fish (43% and 57%). These results confirm that the bivalent inactivated vaccine administered via immersion induces a strong mucosal immune response and confers good protection against both E. ictaluri and A. veronii. Our results also reinforce the notion that immersion vaccination could stimulate both mucosal and systemic immunity contributing to protection against pathogens.

摘要: No studies have systematically compared time-resolved and multi-tissue innate immune responses for European eels (Anguilla anguilla) with Aeromonas hydrophila infection by a high throughput method. Here, we challenged European eels with A. hydrophila (infected) or PBS (control). A low fatality rate (16.1%) was observed for the infected group at 2 d post-infection (dpi). Then we examined transcriptional profiles of intestines, livers and spleens from 12 European eels with/without infection by A. hydrophila at 6, 18 and 36 h post-infection (hpi). The results showed that the most differentially expressed genes (DEGs) were found in the spleen at 6 hpi (7569 DEGs), followed by the intestine at 6 hpi (3129 DEGs) and the liver at 18 hpi (2722 DEGs). Only 540, 41 and 130 DEGs were found in the spleen, liver, and intestine at 36 hpi, respectively. The comparison of DEG numbers and enriched KEGG pathways suggested a consistent time-course immune response in these tissues. A similar enrichment of pattern recognition receptors-related pathways including Toll-like receptors, NOD-like receptors and RIG-I-like receptors was found in the liver and spleen, but not in the intestine. Among immune-related DEGs, 62 paralogue pairs were found, and the expression trends of most paralogues were consistent. Some paralogues of immune-related DEGs had unique domains. Furthermore, large clusters representing similar tissue were shown for the intestine and spleen. A different co-expression network involved in cytokine signal transduction and inter-action existed between the liver and spleen. This study has provided time-resolved and multi-tissue transcriptome characteristics of A. anguilla in response to A. hydrophila infection.

摘要: Zebrafish (Danio rerio) has been used as a promising animal model to study gonadal development and gametogenesis. Although previous studies have identified critical molecules participating in zebrafish gonad differentiation, a landscape view of the biological processes involved in this process is still lacking. Here we isolated intact zebrafish differentiating gonads, at 25 days post-fertilization (dpf) and 30 dpf and conducted RNA-seq analyses on the juvenile gonads that tended to develop into ovaries or testes. Our study demonstrates that the juvenile ovary and testis at 25 dpf and 30 dpf are different at the biological process level. During ovary differentiation, the biological processes related to metabolic activities in the production of energy and maternal substances, RNA degradation, and DNA repair were enriched. During testis differentiation, the biological processes related to cell proliferation, differentiation, and morphogenesis were enriched, with a total of 15 signaling pathways. Notably, we reveal that the immune-related processes are extensively involved in the regulation of testis development. Overall, this study provides a landscape of differentiated biological processes and novel insights into the initiation of sex differentiation in zebrafish.