Redclaw crayfish (Cherax quadricarinatus) responds to Vibrio parahaemolyticus infection by activating toll and immune deficiency signaling pathways and transcription of associated immune response genes

Genetic and Population Diversity of Temnocephalids Associated with the Invasive Crayfish Cherax quadricarinatus in Malaysia

PURPOSE

A previous study revealed that temnocephalids Diceratocephala boschmai, Craspedella pedum, and Decadidymus sp. were highly prevalent in Cheraq quadricarinatus in Melaka and Johor, Malaysia.

METHODS

Herein, study was conducted to extract temnocephalids from C. quadricarinatus and identified using a molecular approach via two DNA markers: 28S ribosomal DNA and mitochondrial cytochrome c oxidase subunit I (CO1). Thereafter, the population diversity of D. boschmai in Malaysia using the CO1 DNA marker was analysed to visualize the genetic associations among populations.

RESULTS

The analysis of 16 variable (segregating) sites in the CO1 gene alignment of sequence from D. boschmai revealed a calculated haplotype diversity of 0.1266 among populations which indicates genetic variation within the studied groups. Additionally, the determination of nucleotide diversity (II) yielded a value of 0.0035, and Tajima's D neutrality test yielded a negative value for all populations, suggesting no significant departure from neutral evolution.

CONCLUSION

AMOVA analysis indicated that the genetic variation or polymorphism is primarily contributed within populations (95%) compared to between populations (4%).

Comparative transcriptomic and molecular biology analyses to explore potential immune responses to Vibrio parahaemolyticus challenge in Eriocheir sinensis

Vibrio parahaemolyticus is a significant pathogen affecting shrimp and crab farming, particularly strains carrying genes associated with acute hepatopancreatic necrosis syndrome. However, the immune response of Eriocheir sinensis to V. parahaemolyticus infection remains unclear. To address this knowledge gap, an experiment was conducted to establish a V. parahaemolyticus infection model. This model aimed to compare pathological damage and enzyme activity changes in E. sinensis hepatopancreas tissue at various infection time points, and to examine transcriptome changes in individuals exhibiting different clinical symptoms of infection. The results showed that intramuscular injection of 1.78 × 106 CFU/mL of V. parahaemolyticus for 24 hours resulted in a 50% mortality rate among the experimental animals. Pathological findings revealed that the infection led to a change in color of the hepatopancreas tissue from bright yellow to white, diffuse tissue cell distribution, and hepatopancreatic necrosis. Additionally, there was a significant increase in the activities of alanine aminotransferase and aspartate aminotransferase in the hepatopancreas (P < 0.01). Furthermore, the activities of superoxide dismutase, total antioxidant capacity, phenoloxidase, alkaline phosphatase, and acid phosphatase initially increased and then decreased. RNA-seq analysis revealed 11,662 differentially expressed genes compared to the susceptible group and control group, with 6,266 genes up-regulated and 5,396 genes down-regulated. When comparing the susceptible group to the disease-resistant group, 13,515 differentially expressed genes were identified, with 7,694 genes up-regulated and 5,821 genes down-regulated. Finally, comparison between the disease-resistant group and control group yielded 13,515 differentially expressed genes, with 7,631 genes up-regulated and 3,111 genes down-regulated. Differential gene enrichment analysis revealed pathways such as phagosomes, cancer pathways, proteoglycans in cancer, ribosomes, protein processing in the endoplasmic reticulum, starch and sucrose metabolism, and lysosome signaling pathways. Furthermore, 342 immune-related genes with differential expression were identified, primarily enriched in 22 pathways linked to cell signaling. These genes play a crucial role in defense against bacterial invasion and immune response regulation through various signaling pathways. Overall, this study provides valuable insights into the defense mechanisms and understanding of Chinese mitten crab immunity against bacterial infection by examining changes in mRNA, enzyme activity, and hepatopancreatic damage during infection.

Identification of toll-like receptor family and the immune function of new Sptlr-6 gene of Scylla paramamosain

As a crucial member of pattern-recognition receptors (PRRs), the Tolls/Toll-like receptors (TLRs) gene family has been proven to be involved in innate immunity in crustaceans. In this study, nine members of TLR gene family were identified from the mud crab (Scylla paramamosain) transcriptome, and the structure and phylogeny of different SpTLRs were analyzed. It was found that different SpTLRs possessed three conserved structures in the TIR domain. Meanwhile, the expression patterns of different Sptlr genes in examined tissues detected by qRT-PCR had wide differences. Compared with other Sptlr genes, Sptlr-6 gene was significantly highly expressed in the hepatopancreas and less expressed in other tissues. Therefore, the function of Sptlr-6 was further investigated. The expression of the Sptlr-6 gene was up-regulated by Poly I: C, PGN stimulation and Vibrio parahaemolyticus infection. In addition, the silencing of Sptlr-6 in hepatopancreas mediated by RNAi technology resulted in the significant decrease of several conserved genes involved in innate immunity in mud crab after V. parahaemolyticus infection, including relish, myd88, dorsal, anti-lipopolysaccharide factor (ALF), anti-lipopolysaccharide factor 2 (ALF-2) and glycine-rich antimicrobial peptide (glyamp). This study provided new knowledge for the role of the Sptlr-6 gene in defense against V. parahaemolyticus infection in S. paramamosain.

Characterization of a novel immune deficiency gene of Macrobrachium rosenbergii reveals antibacterial and antiviral defenses

OBJECTIVE

We sought to identify and characterize an immune deficiency (IMD) homolog from the giant freshwater prawn (also known as the giant river prawn) Macrobrachium rosenbergii. The IMD is a death-domain-containing protein that plays a crucial role as an adaptor protein in the IMD pathway-one of the most important response mechanisms to viral and bacterial invasion of invertebrates.

METHODS

An IMD homolog gene from M. rosenbergii (MrIMD) was isolated using rapid amplification of complementary DNA ends. The tissue distribution and response to immune challenge of MrIMD were analyzed by real-time reverse transcription polymerase chain reaction to understand the regulatory mechanism of MrIMD messenger RNA (mRNA) expression in M. rosenbergii.

RESULT

The open reading frame of MrIMD comprised 555 nucleotides encoding a protein consisting of 184 amino acids, with a conserved death domain at the C-terminus. The MrIMD protein demonstrated 53-74% similarity with IMDs from other crustaceans; the highest similarity was with the IMD from the oriental river prawn M. nipponense. Gene expression analysis revealed that MrIMD mRNA levels were highest in gill tissues. After Aeromonas hydrophila stimulation, MrIMD was significantly upregulated in the muscle, gills, and intestine, whereas there was no significant difference in the hemocytes and hepatopancreas. In the case of Macrobrachium rosenbergii nodavirus stimulation, MrIMD was dramatically upregulated in the muscle and hepatopancreas, whereas downregulation was observed in the gills.

CONCLUSION

These results suggest that the MrIMD gene may play different roles in response to gram-negative bacteria and viral infection and plays a crucial role in innate immunity as an important key molecule in the defense against bacterial and viral infections.

Integrated microbiota and multi-omics analysis reveal the differential responses of earthworm to conventional and biodegradable microplastics in soil under biogas slurry irrigation

As one of the promising alternatives of conventional plastic mulching film (C-PMF), biodegradable plastic mulching films (B-PMF) were employed in agronomy production to alleviate the environmental burden of C-PMF. However, information regarding the potential toxicity effects of biodegradable microplastics (MPs) in soil still in scarcity, and the available findings were found to be controversial. Additionally, little is known about the molecular toxicity effects of conventional and biodegradable MPs on terrestrial organisms. Thus, 5 % (w/w) biodegradable (polylactic acid, PLA) and conventional (polyvinylchloride, PVC; low-density polyvinylchloride, LDPE) MPs were employed to assess the toxicity effects on Eisenia fetida in agricultural soil with biogas slurry irrigation. In the present study, transcriptomic, metabolomic profiles and individual indexes were selected to reveal the toxicity mechanisms from molecular level to the individual response. Furthermore, dysbiosis of bacterial community in gut was also investigated for obtaining comprehensive knowledge on the MPs toxicity. At the end of the exposure, the number of survival earthworms after MPs exposure was significantly reduced. Compared with the initial body weight, PLA and LDPE increased the biomass of earthworms after MPs exposure, while no significant influence on the biomass was observed in PVC treatment. Microbacterium, Klebsiella and Chryseobacterium were significantly enriched in earthworm gut after PLA, PVC and LDPE exposure, respectively (p < 0.05). Transcriptomic and metabolomic analysis revealed that PLA exposure induced neurotransmission disorder and high energetic expenditure in earthworms. However, PVC and LDPE inhibited the nutrient absorption efficiency and activated the innate immunity responses of earthworms. The PLS-SEM results showed that the effects of MPs were dominated by the polymer types, and hence, significantly and directly influence the gut bacterial community of earthworms. This study provides a better understanding of the similarities and discrepancies in toxicity effects of biodegradable and conventional MPs from the perspectives of individual, gut bacterial community, transcriptome and metabolome.

Genome-wide investigation of toll-like receptor genes (TLRs) in Procambarus clarkia and their expression pattern in response to black may disease

As a crucial component of pattern-recognition receptors (PRRs) that recognizing pathogen-associated molecular patterns (PAMPs) and defending against invading pathogens, the Toll-like receptors (TLRs) have been paid extensive attention. While the identification and functional roles of TLRs in innate immunity have been reported in a plenty of organisms, the systematic knowledge of TLRs is still lacking in the red swamp crayfish (Procambarus clarkia). In current study, a total of 7 tlr genes were identified in P. clarkia based on the published transcriptome and genome data. The PcTLRs length varied from 939 to 1517aa and contain typical domains of TLR protein, including transmembrane region, varied LRR and TIR domains. 7 Pctlr genes were distributed in 5 chromosomes and 2 scaffolds. The expression pattern of different Pctlr genes in different tissues (hepatopancreas, gill and muscle) and in response to black may disease (BMD) showed significant difference. In addition, 5 proteins that might interact with PcTLR-2 were predicted, among them the expression pattern of dorsal and relish was consistent with Pctlr-2 in three tissues, while the other genes were not. The PcTLR-2-Dorsal/Relish pathway might play crucial roles in response to BMD infection. The results provided a theoretical foundation for further studies on the molecular mechanisms of TLRs in BMD infection in the red swamp crayfish and provided reference for the research of other crustacean species.