Project description:World aquaculture production of the Pacific white shrimp (Litopenaeus vannamei) is estimated to account for 80% of the total shrimp produce worldwide. The global demand for shrimp has driven the industry to utilize and rely on semi-intensive and intensive shrimp systems. In the United States, Pacific white shrimp production can take place in semi-intensive earthen ponds, recirculating aquaculture systems (RAS), biofloc technology and green water. In this study, the effects of lowering dissolved oxygen conditions in outdoor green water tanks on global gene expression is examined. Tissue samples from the gill and intestine were collected for gene expression analysis via RNA sequencing. Among all comparisons, RNA sequencing revealed the up-regulation of a single gene: hydroxyacid oxidase 1 gene. The HOA1 gene was found to be 7-fold higher in the intestine sample at the medium aeration level compare to that of the high (control) level. The HAO1 gene, also known as glycolate oxidase 1 (GOX1) is a gene related to the 2-hydroxyacid oxidase enzyme that is part of the oxidoreductase family and plays a role in glyoxylate and dicarboxylate metabolism. The identification of a single differentially expressed gene across all analyzed samples suggests that Pacific white shrimp exposed to lowering dissolved oxygen set points does not induce global changes in gene expression at these levels.
Project description:With the global increase in the use of carbapenems, several gram-negative bacteria have acquired carbapenem resistance, thereby limiting treatment options. Klebsiella pneumoniae is one of such notorious pathogen that is being widely studied to find novel resistance mechanisms and drug targets. These antibiotic-resistant clinical isolates generally harbor many genetic alterations, and identification of causal mutations will provide insights into the molecular mechanisms of antibiotic resistance. We propose a method to prioritize mutated genes responsible for antibiotic resistance, in which mutated genes that also show significant expression changes among their functionally coupled genes become more likely candidates. For network-based analyses, we developed a genome-scale co-functional network of K. pneumoniae genes, KlebNet (www.inetbio.org/klebnet). Using KlebNet, we could reconstruct functional modules for antibiotic-resistance, and virulence, and retrieved functional association between them. With complementation assays with top candidate genes, we could validate a gene for negative regulation of meropenem resistance and four genes for positive regulation of virulence in Galleria mellonella larvae. Therefore, our study demonstrated the feasibility of network-based identification of genes required for antimicrobial resistance and virulence of human pathogenic bacteria with genomic and transcriptomic profiles from antibiotic-resistant clinical isolates.
Project description:Acute hepatopancreatic necrosis disease (AHPND) is a shrimp farming disease, caused by a pathogenic Vibrio parahaemolyticus carrying a plasmid encoding Vp_PirAB-like toxin (VpAHPND). Whiteleg shrimp, Litopenaeus vannamei were fed food pellets containing formalin-killed VpAHPND (FKC-VpAHPND) to select for toxin resistance. To identify genes associated with Vp_PirAB-like toxin resistance, total RNA was sequenced to identify differentially expressed genes (DEGs) in the stomach and hepatopancreas among surviving shrimp (sur-FKC), AHPND-infected shrimp (Vp-inf) and normal shrimp (control). From a total of 79,591 genes, 194 and 224 DEGs were identified in the stomach and hepatopancreas transcriptomes, respectfully. The expressions of DEGs were validated by qPCR of ten genes. Only one gene, a gene homologous to L vannamei anti-lipopolysaccharide factor AV-R isoform (LvALF AV-R), was expressed significantly more strongly in sur-FKC than in the other groups. The association of LvALF AV-R expression and toxin resistance was affirmed from the surviving shrimp in a second-trial of FKC-VpAHPND feeding. These results suggest that LvALF AV-R may be involved in shrimp defense mechanisms against Vp_PirAB-like toxin virulence.