摘要: High fish predation pressure can trigger induced defense in Daphnia species, resulting in phenotypic plasticity in morphology, behavior, or life-history traits. The molecular mechanisms of defense morphogenesis (e.g., the tail spine and helmet) in Daphnia remain unclear. In the present study, the tail spine, helmet, and body of Daphnia galeata under fish and non-fish kairomones conditions were collected for transcriptome analysis. A total of 24 candidate genes related to the morphological defense of D. galeata were identified, including 2 trypsin, one cuticle protein, 1 C1qDC protein, and 2 ferritin genes. The function of the Dagcut gene (D. galeata cuticle protein gene) in relation to tail spine morphology was assessed using RNA interference (RNAi). Compared with the EGFP (Enhanced green fluorescent protein) treatment, after RNAi, the expression levels of the Dagcut gene (D. galeata cuticle protein gene) showed a significant decrease. Correspondingly, the tail spines of the offspring produced by D. galeata after RNAi of the Dagcut gene appeared curved during the experiment. In whole-mount in situ hybridization, a clear signal site was detected on the tail spine of D. galeata before RNAi which disappeared after RNAi. Our results suggest that the Dagcut gene may play an important role in tail spine formation of D. galeata, and will provide a theoretical basis for studying the molecular mechanisms of the morphological plasticity in cladocera in the future.

摘要: As a copper (Cu) transport ATPase, ATP7A plays an important role in maintaining Cu homeostasis in the body, but the developmental and physiological roles of atp7a in zebrafish embryogenesis are rarely studied. In this study, normal morphological phenotypes of atp7a-7-homozygous zebrafish were observed at both embryonic and adult stages, however, atp7a-/- larvae exhibited delayed touch response and obvious transcriptome changes. Compared with the WT (wild type), differentially expressed genes (DEGs) in atp7a-7-larvae showed the enrichment in gene ontology (GO) terms related to several processes including ATPase activity, oxidoreductase activity, active transmembrane transporter activity, ion binding, and the citrate cycle. Furthermore, decreases in both ATP content and Na+/K+-ATPase activity in atp7a-/- embryos and larvae were unveiled. 57 overlapping DEGs were found both in WT stressed with Cu and in WT mutated with atp7a, and GO term analysis indicated the enrichment in the genes related to neurexin family protein binding and neuronal cell-cell adhesion. Moreover, 42 overlapping DEGs in Cu stressed WT and Cu stressed atp7a-/- were identified. GO term analysis showed an enrichment in the genes related to heme binding, implying that Cu was independent of the integral function of atp7a to affect heme binding. In addition, genes involved in the negative regulation of angiogenesis were down-regulated in atp7a-/- mutants with and without Cu stress, which failed to occur in WT, implying that the integral function of atp7a is required for maintaining the normal expression of angiogenesis genes. The integrative data in this study demonstrated that atp7a is required for ion transport and angiogenesis, and for Cu-induced neurexin family protein binding defects, rather than for Cu-induced heme binding defects, during zebrafish embryogenesis. These findings provide possible clues for human diseases with ATP7A dysfunction and imbalanced Cu homeostasis.

摘要: SOCS8, also known as CISHb, is a fish-specific type II SOCS. Because CISH binds to cytokine receptors and may inhibit STAT5 activation (a substrate of the insulin receptor), SOCS8 may be involved in the control of meta-flammation. The socs8-/- zebrafish were created, and both longer trunks and intestinal villi were observed in 1-month-old (mo) fish. Altered mucosal immunity and gut-liver metabolism were also found in socs8-/- fish. Increased intestinal neutrophils and macrophages, together with overexpression of cytokines and T cell markers in this mutant fish, suggested SOCS8's immunoregulating role. During modeling of soybean-induced enteritis using the 3 mo zebrafish, lower expression levels of inflammatory genes but more mucosa barrier disruption were discovered in socs8-/- zebrafish, compared with wide type counterparts. Furthermore, the shrunk villi at 6 mo in socs8-/- fish suggested that the mucosa might have been protected by SOCS8. This is also consistent with the assertion that metaflammation eventually leads to tissue degeneration and premature death. The fact that socs8-/ -fish had more hepatic oil droplets compared to their wild-type counterparts suggested SOCS8's role in inhibiting hepatic metaflammation. Transcriptomic analysis as well as 16S rRNA gene sequencing were done on 3 mo socs8-/- fish to methodically reveal the altered immunity and metabolic reprogramming in the gut and liver caused by socs8-/-. The enriched GO terms for the intestinal tract, such as cytokine-mediated signaling pathway and response to external biotic stimulus, as well as KEGG pathways in both gut and liver like carbon metabolism and glycolysis/gluconeogenesis, were consistent with previously revealed pathological clues and improved growth performance at early age, respectively. In addition, the microbiota in the socs8-/- strain had adapted to the host's increased carbohydrate metabolism, as evidenced by higher levels of Bacteroidota. Furthermore, Verrucomicrobiota associated with immunoregulation were found in lower abundance in socs8-/- fish. As a result, current findings indicate that SOCS8 plays immunoregulatory and mucosa-protective roles in the fish gut and liver by inhibiting carbohydrate metabolism.

摘要: In recent years, pollution caused by the discharge of industrial wastewater into Bohai Bay has posed a potential threat to the health of surrounding residents. Sludge was collected from the outlet of a factory that discharges effluent into Bohai Bay, and alcohol extracts of sludge (SE) were prepared. We confirmed by UPLC-MS/MS analysis that the SE contained PAHs, including fluorene, pyrene, and phenanthrene. Zebrafish embryos as animal models were exposed to 0.1, 0.3, 0.5, 1 and 5 mg/mL SE from 2 to 4 h post-fertilization (hpf) until 120 hpf. The results showed that SE caused a concentration-dependent increase in mortality and a decrease in hatchability. We found that SE significantly reduced eye pigmentation and decreased the movement of embryos and larvae. In addition, SE decreased triiodothyronine (T3) content and down-regulated the mRNA expression of some thyroid hormone-related genes including TPO and Thr beta, and caused the up-regulation of Dio2 and Dio3 at 120 hpf. Exposure to three individual PAHs found in SE, namely fluorene, pyrene, and phenanthrene, caused morphological and transcriptional changes that were similar to those caused by SE exposure. These findings indicate that PAHs in SE can reduce the pigmentation of zebrafish, which may be related to the genetic changes associated with thyroid hormones, and that zebrafish eye pigmentation can be used as an indicator of PAHs exposure.

摘要: Polymeric immunoglobulin (Ig) receptor-like (pIgRL) molecules have been identified in teleost fish. However, compared to functional studies of their related genes (e.g., mammalian CD300 family) in eliminating pathogen invasion while preserving homeostasis, the roles of pIgRL in teleost fish remain unclear. In this study, we demonstrated that a pair of pIgRL molecules in zebrafish, pIgRL3.5 and pIgRL4.2, were highly expressed in the intestine and immune cells. Moreover, we constructed an Edwardsiella piscicida infection model, which induced strong inflammatory responses in the zebrafish intestine. Interestingly, pIgRL3.5 and pIgRL4.2 exhibited opposite inducible expression patterns in response to bacterial infection, suggesting that they perform different roles. More importantly, by conducting overexpression and knockdown experiments, our findings demonstrated that zebrafish pIgRL3.5 played a protective role in host defense against E. piscicida infection by inhibiting excessive inflammatory responses. In contrast, pIgRL4.2 facilitated pathogen growth and dissemination in zebrafish intestine. Collectively, our findings are the first to demonstrate that a pair of pIgRL molecules in teleost fish play opposite roles in mucosal immune response to bacterial infection. Therefore, our results provide crucial insights into the conserved role of pIgRL molecules in immune regulatory functions throughout vertebrate evolution.