Abstract
BackgroundManila clam (Ruditapes philippinarum) is a worldwide commercially important marine bivalve species. In recent years, however, microbial diseases caused high economic losses and have received increasing attention. To understand the molecular basis of the immune response to pathogen-associated molecular patterns (PAMPs) in R. philippinarum, transcriptome libraries of clam hepatopancreas were constructed at 24 h post-injection with Lipopolysaccharide (LPS), peptidoglycan (PGN), and polyinosinic-polycytidylic acid (poly(I:C)) and phosphate-buffered saline (PBS) control by using RNA sequencing technology (RNA-seq).ResultsA total of 832, 839, and 188 differentially expressed genes (DEGs) were found in LPS, PGN, and poly(I:C) challenge group compared with PBS control, respectively. Several immune-related genes and pathways were activated in response to the different PAMPs, suggesting these genes and pathways might specifically participate in the immune response to pathogens. Besides, the analyses provided useful complementary data to compare different PAMPs challenges in vivo. Functional enrichment analysis of DEGs demonstrated that PAMPs responsive signal pathways were related to apoptosis, signal transduction, immune system, and signaling molecules and interaction. Several shared or specific DEGs response to different PAMPs were revealed in R. philippinarum, including pattern recognition receptors (PRRs), antimicrobial peptides (AMPs), interferon-induced proteins (IFI), and some other immune-related genes were found in the present work.ConclusionsThis is the first study employing high throughput transcriptomic sequencing to provide valuable genomic resources and investigate Manila clam response to different PAMPs through in vivo challenges with LPS, PGN, and poly(I:C). The results obtained here provide new insights to understanding the immune characteristics of R. philippinarum response to different PAMPs. This information is critical to elucidate the molecular basis of R. philippinarum response to different pathogens invasion, which potentially can be used to develop effective control strategies for different pathogens.
Highlights
Manila clam (Ruditapes philippinarum) is a worldwide commercially important marine bivalve species
Density distribution of expression level based on log10 (FPKM) in each library was exhibited in Additional file 2, which showed that LPS, PGN, and poly(I:C) groups were similar, while the phosphatebuffered saline (PBS) control group library was different with others three groups
Several pattern recognition molecules (PRMs) that are important in detecting pathogen-associated molecular patterns (PAMPs) were identified, including the fibrinogen-like protein (FREP), c1q-like protein (C1qL), FCN, toll-like receptor (TLR), peptidoglycan recognition protein (PGRP), Perlucin, macrophage mannose receptor 1 (MMR1), C-type lectin (CTL), CL, L-type lectin (LTL), scavenger receptor cysteine-rich (SRCR), and sialic acid-binding lectin (Siglec) (Table 1), most of which could activate innate immune response
Summary
Manila clam (Ruditapes philippinarum) is a worldwide commercially important marine bivalve species. Microbial diseases caused high economic losses and have received increasing attention. Ruditapes philippinarum, is one of the most commercially important bivalves and reached over 4.2 million tons in 2017, which is widely distributed along the coast of China, Japan, and Korea [1]. R. philippinarum possesses many advantages as an aquaculture species, including wide salinity and temperature resistance, rapid growth, and pollution tolerance [2]. The majority of diseases in Manila clam are associated with Vibrio [7, 8] and Perkinsus [9, 10]. Diseases affecting R. philippinarum can result in mass mortality in aquaculture and cause large economic losses [11]
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