Immune response to acute heat stress in the intestine of the red swamp crayfish, Procambarus clarkii.

High temperature is an important environmental factor that affects the survival and immunity of aquatic animals. The intestine of crustaceans is their first line of defense, and the physiological homeostasis of this organ can be influenced by high temperature stress. The red swamp crayfish Procambarus clarkii is an important commercial aquaculture species in China, but little is known about its intestinal immune response to acute heat stress. In this study, we investigated the intestinal immune response of P. clarkii individuals that were assigned to the control (25 °C) and heat stress (35 °C) groups. Biochemical assays were conducted for the oxidative stress parameters ·O2- generation capacity, lipid peroxide content, and malondialdehyde content; the activities of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase; and the activities of the immunity-related enzymes alkaline phosphatase, acid phosphatase, and lysozyme. The relative expression level of the antioxidant genes heat shock protein 70 (hsp70), ferritin (fer), and metallothione (met) was examined by RT-PCR. Based on the data obtained, all the parameters tended to increase, peak and then decrease with time, and were significantly different between the two groups (P < 0.05). These findings reveal that acute heat stress adversely affects the antioxidant status and immune function in the P. clarkii intestine. They lay the groundwork for future studies on the effect of rising water temperatures on immune function and survival of this species.

The regulation roles of miR-125b, miR-221 and miR-27b in porcine Salmonella infection signalling pathway.

miRNAs are non-coding RNA molecules typically 18-22 nucleotides long that can suppress the expression of their target genes. Several laboratories have attempted to identify miRNAs from the pig that are involved in Salmonella infection. These bioinformatics strategies using the newly available genomic sequence are generally successful. Here, we report an in silico identification of miRNAs in pig focusing on the Salmonella infection pathway, and further investigated the differential expression of those miRNAs by quantitative real-time PCR during pre- and post-natal stage of Salmonella inoculation from the peripheral blood of commercially breed pigs. We identified 29 miRNAs that have predicted targets in the Salmonella infection pathway and nine of them were not yet described in pig. In addition, the expression of nine selected miRNAs was validated in the peripheral blood by northern blotting. Through expression analyses, differences were found between pre- and post-natal stages of Salmonella inoculation for miR-221, miR-125b and miR-27b-all of them were suppressed 2 days after Salmonella inoculation. The predicted targets of those three miRNAs were validated by luciferase reporter assays. We show that FOS is a direct target of miR-221, miR-125b can suppress MAPK14, and miR-27b can target IFNG. These findings will be helpful in understanding the function and processing of these miRNAs in Salmonella infection. The miRNA differentially expressed in the peripheral blood of commercial breed pigs suggest that it can be used as genetic markers for salmonella infection resistance in pigs.