Interactions between the gut micro-community and transcriptome of Culex pipiens pallens under low-temperature stress.

BACKGROUND: Culex pipiens pallens (Diptera: Culicidae) can survive at low temperature for long periods. Understanding the effects of low-temperature stress on the gut microflora and gene expression levels in Cx. pipiens pallens, as well as their correlation, will contribute to the study of the overwintering mechanism of Cx. pipiens pallens. METHODS: The gut bacteria were removed by antibiotic treatment, and the survival of Cx. pipiens pallens under low-temperature stress was observed and compared with the control group. Then, full-length 16S rRNA sequencing and the Illumina HiSeq X Ten sequencing platform were used to evaluate the gut microflora and gene expression levels in Cx. pipiens pallens under low-temperature stress. RESULTS: Under the low-temperature stress of 7 °C, the median survival time of Cx. pipiens pallens in the antibiotic treatment group was significantly shortened by approximately 70% compared to that in the control group. The species diversity index (Shannon, Simpson, Ace, Chao1) of Cx. pipiens pallens decreased under low-temperature stress (7 °C). Non-metric multidimensional scaling (NMDS) analysis divided all the gut samples into two groups: control group and treatment group. Pseudomonas was the dominant taxon identified in the control group, followed by Elizabethkingia and Dyadobacter; in the treatment group, Pseudomonas was the dominant taxon, followed by Aeromonas and Comamonas. Of the 2417 differentially expressed genes (DEGs), 1316 were upregulated, and 1101 were downregulated. Functional GO terms were enriched in 23 biological processes, 20 cellular components and 21 molecular functions. KEGG annotation results showed that most of these genes were related to energy metabolism-related pathways. The results of Pearson's correlation analysis showed a significant correlation between the gut microcommunity at the genus level and several DEGs. CONCLUSIONS: These results suggest that the mechanism of adaptation of Cx. pipiens pallens to low-temperature stress may be the result of interactions between the gut bacterial community and transcriptome.

Research progress on the structure of crystal protein of Bacillus thuringiensis and its mechanism / 中国热带医学

@#Abstract: Mosquitoes are involved in the transmission of serious diseases such as malaria, dengue, chikungunya, yellow fever, Zika virus disease, and filariasis, and their prevention and control have always been a research hotspot. Currently, mosquito control methods mainly include physical control, chemical control and biological control. Physical control methods are environmentally friendly, but they are slow to take effect and have unsatisfactory control effects; although chemical control can quickly eliminate mosquitoes, it has been eliminated due to its high pollution, high residual, and easy drug resistance; biological control uses natural enemies or pathogens to kill mosquitoes and reduce their ability to transmit disease. Therefore, environmentally friendly biological control has become the main measure for controlling and preventing mosquitoes. In recent years, significant progress has been made in bacterial mosquito control agents, among which Bacillus thuringiensis has been the most extensively studied. Bacillus thuringiensis is a Gram-positive soil microorganism, which is the pathogenic bacterium of a variety of agricultural pests such as Lepidoptera, Coleoptera and Diptera. During the sporulation process, its strains produce a variety of insecticidal crystal proteins (ICPs) or δ-endotoxins with insecticidal activity against mosquito larvae. This review firstly introduces the crystal proteins of Bacillus thuringiensis, describes in detail the types and structures of crystal proteins in detail, and also reveals the mechanism of action of crystal proteins related to receptors.