The role of insect gut microbiota in host fitness, detoxification and nutrient supplementation.

Insects are incredibly diverse, ubiquitous and have successfully flourished out of the dynamic and often unpredictable nature of evolutionary processes. The resident microbiome has accompanied the physical and biological adaptations that enable their continued survival and proliferation in a wide array of environments. The host insect and microbiome's bidirectional relationship exhibits their capability to influence each other's physiology, behavior and characteristics. Insects are reported to rely directly on the microbial community to break down complex food, adapt to nutrient-deficit environments, protect themselves from natural adversaries and control the expression of social behavior. High-throughput metagenomic approaches have enhanced the potential for determining the abundance, composition, diversity and functional activities of microbial fauna associated with insect hosts, enabling in-depth investigation into insect-microbe interactions. We undertook a review of some of the major advances in the field of metagenomics, focusing on insect-microbe interaction, diversity and composition of resident microbiota, the functional capability of endosymbionts and discussions on different symbiotic relationships. The review aims to be a valuable resource on insect gut symbiotic microbiota by providing a comprehensive understanding of how insect gut symbionts systematically perform a range of functions, viz., insecticide degradation, nutritional support and immune fitness. A thorough understanding of manipulating specific gut symbionts may aid in developing advanced insect-associated research to attain health and design strategies for pest management.

Reference genes for qPCR expression in black tiger shrimp, Penaeus monodon.

BACKGROUND: Gene expression profiling via qPCR is an essential tool for unraveling the intricate molecular mechanisms underlying growth and development. Identifying and validating the most appropriate reference genes is essential for qPCR experiments. Nevertheless, there exists a deficiency in a thorough assessment of reference genes concerning the expression of the genes in the research in the context of the growth and development of the Black Tiger Shrimp, P. monodon. This popular marine crustacean is extensively raised for human consumption. In this study, we assessed the expression stability of seven reference genes (ACTB, 18S, EF-1α, AK, PK, cox1, and CLTC) in adult tissues (hepatopancreas, gills, and stomach) of small and large polymorphs of P. monodon. METHODS AND RESULTS: The stability of gene expressions was assessed utilizing NormFinder, BestKeeper, and geNorm, and a comprehensive ranking of these genes was conducted through the online tool RefFinder. In the overall ranking, 18S and CLTC emerged as the most stable genes in the hepatopancreas and stomach, while CLTC and AK exhibited significant statistical reliability in the gills of adult P. monodon. The validation of these identified stable genes was carried out using a growth-associated gene, insr-1. CONCLUSION: The results indicated that 18S and CLTC stand out as the most versatile reference genes for conducting qPCR analysis focused on the growth of P. monodon. This study represents the first comprehensive exploration that identifies and assesses reference genes for qPCR analysis in P. monodon, providing valuable tools for research involving similar crustaceans.

Transcriptome analysis of Corvus splendens reveals a repertoire of antimicrobial peptides.

Multidrug resistance has become a global health problem associated with high morbidity and mortality. Antimicrobial peptides have been acknowledged as potential leads for prospective anti-infectives. Owing to their scavenging lifestyle, Corvus splendens is thought to have developed robust immunity to pathogens found in their diet, implying that they have evolved mechanisms to resist infection. In the current study, the transcriptome of C. splendens was sequenced, and de novo assembled to identify the presence of antimicrobial peptide genes. 72.09 million high-quality clean reads were obtained which were then de novo assembled into 3,43,503 transcripts and 74,958 unigenes. About 37,559 unigenes were successfully annotated using SwissProt, Pfam, GO, and KEGG databases. A search against APD3, CAMPR3 and LAMP databases identified 63 AMP candidates belonging to more than 20 diverse families and functional classes. mRNA of AvBD-2, AvBD-13 and CATH-2 were found to be differentially expressed between the three tested crows as well as among the tissues. We also characterized Corvus Cathelicidin 2 (CATH-2) to gain knowledge of its antimicrobial mechanisms. The CD spectroscopy of synthesized mature Corvus CATH-2 peptide displayed an amphipathic α-helical structure. Though the synthetic CATH-2 caused hemolysis of human RBC, it also exhibited antimicrobial activity against E. coli, S. aureus, and B. cereus. Docking simulation results revealed that this peptide could bind to the LPS binding site of MD-2, which may prevent LPS from entering the MD-2 binding pocket, and trigger TLR4 signaling pathway. The Corvus CATH-2 characterized in this study could aid in the development of novel therapeutics.