The genome-wide characterisation of cold shock proteins and prominent roles involved in cold response by configuring metabolic pathways in Haemaphysalis longicornis.

Cold shock proteins are relatively conserved in evolution and are involved in regulating various life activities, including cell proliferation, nutritional stress and cold adaptation. However, information about the function and regulation of cold shock proteins in ticks during cold response remains meagre. In the present study, six cold shock protein genes were identified from the important vector tick Haemaphysalis longicornis, which were named as HlY-box1, HlY-box2, HlY-box3, HlY-box4, HlY-box5 and HlY-box6. Spatiotemporal expression dynamics revealed dynamic expressions varied significantly after low-temperature treatment, with different expression patterns observed over prolonged exposure periods. Then the function and regulation of cold shock protein genes during the cold response of H. longicornis were explored. RNA interference (RNAi) efficiently knocked down these genes, significantly increasing tick mortality under cold stress. Transcriptomic analysis following HlY-box4 knockdown identified 336 differentially expressed genes (DEGs), which were mainly annotated in the MAPK signalling pathway and metabolism pathway. Proteomic analysis identified 632 differentially expressed proteins associated with ATP-dependent chromatin remodelling, metabolic pathway, spliceosome, ribosome and nucleoplasmic transport pathways. The results highlight the critical roles of cold shock proteins (CSPs) in tick cold responses, primarily through regulating metabolic pathways, and provide a foundation for further exploration of their molecular mechanisms.