Abstract
BackgroundMud crab Scylla paramamosain is an economically important marine species in China. However, frequent outbreaks of infectious diseases caused by marine bacteria, such as Vibrio parahaemolyticus, result in great economic losses.Methodology/Principal FindingsComparative de novo transcriptome analysis of S. paramamosain infected with V. parahaemolyticus was carried out to investigate the molecular mechanisms underlying the immune response to pathogenic bacteria by using the Illumina paired-end sequencing platform. A total of 52,934,042 clean reads from the hemocytes of V. parahaemolyticus-infected mud crabs and controls were obtained and assembled into 186,193 contigs. 59,120 unigenes were identified from 81,709 consensus sequences of mud crabs and 48,934 unigenes were matched proteins in the Nr or Swissprot databases. Among these, 10,566 unigenes belong to 3 categories of Gene Ontology, 25,349 to 30 categories of KEGG, and 15,191 to 25 categories of COG database, covering almost all functional categories. By using the Solexa/Illumina's DGE platform, 1213 differentially expressed genes (P<0.05), including 538 significantly up-regulated and 675 down-regulated, were detected in V. parahaemolyticus-infected crabs as compared to that in the controls. Transcript levels of randomly-chosen genes were further measured by quantitative real-time PCR to confirm the expression profiles. Many differentially expressed genes are involved in various immune processes, including stimulation of the Toll pathway, Immune Deficiency (IMD) pathway, Ras-regulated endocytosis, and proPO-activating system.Conclusions/SignificanceAnalysis of the expression profile of crabs under infection provides invaluable new data for biological research in S. paramamosain, such as the identification of novel genes in the hemocytes during V. parahaemolyticus infection. These results will facilitate our comprehensive understanding of the mechanisms involved in the immune response to bacterial infection and will be helpful for diseases prevention in crab aquaculture.
Highlights
Scylla paramamosain (Crustacea: Decapods: Brachyura), an economically important mariculture commonly known as mud crab, is widely distributed in China and several parts of the world
Much has been reported on the investigations of the innate immunity [4] and the characterization of immune-related genes in mud crab [5,6,7,8,9], little is known about the global molecular mechanisms underlying the immune response to such a pathogenic bacterial infection in this species
Total RNA was extracted from the hemocytes of crabs at several time points, including 0, 12, 24, and 48 h after V. parahaemolyticus infection
Summary
Scylla paramamosain (Crustacea: Decapods: Brachyura), an economically important mariculture commonly known as mud crab, is widely distributed in China and several parts of the world. The ‘‘milky disease’’ of mud crab, caused by pathogenic infection of bacteria V. parahaemolyticus in the last few years in Southern China, had resulted in more than 60% of mortality and brought in great economic losses [2,3]. Methodology/Principal Findings: Comparative de novo transcriptome analysis of S. paramamosain infected with V. parahaemolyticus was carried out to investigate the molecular mechanisms underlying the immune response to pathogenic bacteria by using the Illumina paired-end sequencing platform. By using the Solexa/Illumina’s DGE platform, 1213 differentially expressed genes (P,0.05), including 538 significantly up-regulated and 675 down-regulated, were detected in V. parahaemolyticus-infected crabs as compared to that in the controls. Many differentially expressed genes are involved in various immune processes, PLOS ONE | DOI:10.1371/journal.pone.0114500 December 8, 2014
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