Transcriptomic Analysis Of The Expression And Regulation Of Antimicrobial Peptides In The Skin Of Black Spotted Frog

Amphibians have bare skin,lack of stratum corneum and,and are highly permeable.A large number of studies have revealed the process and mechanism of amphibian synthesis and secretion of antimicrobial peptides(AMPs)under the stress of pathogenic microorganisms.However,in the normal environment in which amphibians live,microorganisms are usually not pathogenic.Do these microorganisms have an impact on the synthesis of AMPs?If so,what is the mechanism?Answering these questions is important for understanding physiological adaptation and the evolutionary mechanisms of AMPs.In order to answer these two questions,this study selected black spotted frog(Pelophylax nigromaculata)as the object,and obtained a general picture of the microbial community in the main habitat water body and a complete transcript of its skin tissue in the wild state through high-throughput sequencing.Firstly,the frogs were injected with norepinephrine to empty most of the AMPs stored in the granular glands,and then the frogs were placed in water with different microbial abundance,and the recovery process of skin granular glands in the environment with different microbial abundance was observed histologically.Using high-throughput sequencing for different groups of whole transcriptome analysis of differentially expressed genes,of TLR2,TLR4,TLR5,NOD1,NOD2,TAK1,NF-?B1,I?B?,pelophylaxin-HB1,ranacyclin,brevinin,pleurain-E,and temporin-lgene expression by quantitative detection,such as environmental microbial abundance and various signal molecule of skin tissue and AMP mRNA expression changes.The main results were as follows:1.At histological and molecular levels,all microorganisms in the environment are antigens of amphibians and jointly regulate the immune response and level of amphibians.2.In the environment with high microbial abundance,the frog has a high demand for immunity,faster synthesis of antimicrobial peptides,more secretion,large pellet glands and low filling degree.However,in the environment with low microbial abundance,the immune requirements of frogs were low,the synthesis rate of antibacterial peptides was slow and the secretion was low,and the pellet glands of frogs were small and the filling degree was high.3.Microbial stimulation regulates the synthesis of antimicrobial peptides through TLR4 recognition and reception of antigenic signals through NF-?B1 and I?B?.These results indicate that the abundance of microorganisms in the environment is a stimulus to the synthesis of AMPs and a determinant of the immune cost of AMPs.