Molecular variations of the gill of <i>Thamnaconus septentrionalis</i> in responses to density stress

In order to understand the molecular response mechanism of Thamnaconus septentrionalis gill tissue under density stress, we analyzed differentially expressed genes (DEGs) and their regulatory mechanisms. This study aims to provide valuable insights for artificial and molecular breeding of T. septentrionalis . We set up two breeding density groups: a low-density group (100 individuals/m 3 ) and a high-density group (500 individuals/m 3 ). Gill tissues of T. septentrionalis were collected at the 25th and 50th day, followed by transcriptome sequencing using the Illumina platform. After rigorous quality control and data analysis, including Difference Analysis (DA), Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and Trend Analysis(TA), we obtained the following results: 1. In CG-vs-D1G, 390 genes were up-regulated and 723 genes were down-regulated; In CG-vs-D2G, 128 genes were up-regulated and 384 genes were down-regulated; In CG-vs-d1G, 794 genes were up-regulated and 2940 genes were down-regulated; In CG-vs-d2G, 851 genes were up-regulated and 3745 genes were down-regulated. 2. GO analysis revealed significant entries such as cellular process, single-organism process, metabolic process, and biological regulation. 3. KEGG analysis showed that DEGs were primarily enriched in pathways like oxidative phosphorylation, thermogenesis, hematopoietic cell lineage, ribosome, legionellosis, and folate biosynthesis. Key genes, including cyp1b1, rpl22l1, tnf, pla2g10, uqcr11, atp5mc3, cox5b , and ndufb5 , exhibited differential expressed in the gill tissue of T. septentrionalis . These DEGs are likely to play crucial roles in regulating the synthesis rate of T. Septentrionalis body and the synthesis and development of red blood cells, providing a foundation for studying the formation of gene expression control related to density stress.