Involvement of the Macrobrachium nipponense rhodanese homologue 2, MnRDH2 in innate immunity and antioxidant defense

RNA-seq Provides Novel Insights into Response to Acute Salinity Stress in Oriental River Prawn Macrobrachium nipponense

The oriental river prawn Macrobrachium nipponense is an important aquaculture species in China, Vietnam, and Japan. This species could survive in the salinity ranging from 7 to 20 ppt and accelerate growth in the salinity of 7 ppt. To identify the genes and pathways in response to acute high salinity stress, M. nipponense was exposed to the acute high salinity of 25 ppt. Total RNA from hepatopancreas, gills, and muscle tissues was isolated and then sequenced using high-throughput sequencing method. Differentially expressed genes (DGEs) were identified, and a total of 632, 836, and 1246 DEGs with a cutoff of significant twofold change were differentially expressed in the hepatopancreas, gills, and muscle tissues, respectively. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genome pathway enrichment analyses were conducted. These DEGs were involved in the GO terms of cellular process, metabolic process, membrane, organelle, binding, and catalytic activity. The DEGs of hepatopancreas and gill tissues were mainly enriched in PPAR signaling pathway, longevity regulating pathway, protein digestion and absorption, and the DEGs of muscle tissue in arginine biosynthesis, adrenergic signaling in cardiomyocytes, cardiac muscle contraction, and cGMP-PKG signaling pathway. Real-time PCR conducted with fifteen selected DEGs indicated high reliability of digital analysis using RNA-Seq. The results indicated that the M. nipponense may regulate essential mechanisms such as metabolism, oxidative stress, and ion exchange to adapt the alternation of environment, when exposed to acute high salinity stress. This work reveals the numbers of genes modified by salinity stress and some important pathways, which could provide a comprehensive insight into the molecular responses to high salinity stress in M. nipponense and further boost the understanding of the potential molecular mechanisms of adaptation to salinity stress for euryhaline crustaceans.

Sulfur Administration in Fe-S Cluster Homeostasis

Mitochondria are the key organelles of Fe–S cluster synthesis. They contain the enzyme cysteine desulfurase, a scaffold protein, iron and electron donors, and specific chaperons all required for the formation of Fe–S clusters. The newly formed cluster can be utilized by mitochondrial Fe–S protein synthesis or undergo further transformation. Mitochondrial Fe–S cluster biogenesis components are required in the cytosolic iron–sulfur cluster assembly machinery for cytosolic and nuclear cluster supplies. Clusters that are the key components of Fe–S proteins are vulnerable and prone to degradation whenever exposed to oxidative stress. However, once degraded, the Fe–S cluster can be resynthesized or repaired. It has been proposed that sulfurtransferases, rhodanese, and 3-mercaptopyruvate sulfurtransferase, responsible for sulfur transfer from donor to nucleophilic acceptor, are involved in the Fe–S cluster formation, maturation, or reconstitution. In the present paper, we attempt to sum up our knowledge on the involvement of sulfurtransferases not only in sulfur administration but also in the Fe–S cluster formation in mammals and yeasts, and on reconstitution-damaged cluster or restoration of enzyme’s attenuated activity.

Characterization of a rhodanese homologue from Haemonchus contortus and its immune-modulatory effects on goat immune cells in vitro

BACKGROUND

Modulation of the host immune response by nematode parasites has been widely reported. Rhodaneses (thiosulfate: cyanide sulfurtransferases) are present in a wide range of organisms, such as archaea, bacteria, fungi, plants and animals. Previously, it was reported that a rhodanese homologue could be bound by goat peripheral blood mononuclear cells (PBMCs) in vivo.

METHODS

In the present study, we cloned and produced a recombinant rhodanese protein originating from Haemonchus contortus (rHCRD), a parasitic nematode of small ruminants. rHCRD was co-incubated with goat PBMCs to assess its immunomodulatory effects on proliferation, apoptosis and cytokine secretion.

RESULTS

We verified that the natural HCRD protein localized predominantly to the bowel wall and body surface of the parasite. We further demonstrated that serum produced by goats artificially infected with H. contortus successfully recognized rHCRD, which bound to goat PBMCs. rHCRD suppressed proliferation of goat PBMCs stimulated by concanavalin A but did not induce apoptosis in goat PBMCs. The production of TNF-α and IFN-γ decreased significantly, whereas secretion of IL-10 and TGF-β1 increased, in goat PBMCs after exposure to rHCRD. rHCRD also inhibited phagocytosis by goat monocytes. Moreover, rHCRD downregulated the expression of major histocompatibility complex (MHC)-II on goat monocytes in a dose-dependent manner, but did not alter MHC-I expression.

CONCLUSIONS

These results propose a possible immunomodulatory target that may help illuminate the interactions between parasites and their hosts at the molecular level and reveal innovative protein species as candidate drug and vaccine targets.

mRNA profile provides novel insights into stress adaptation in mud crab megalopa, Scylla paramamosain after salinity stress

Background

Mud crab, Scylla paramamosain, a euryhaline crustacean species, mainly inhabits the Indo-Western Pacific region. Wild mud crab spawn in high-salt condition and the salinity reduced with the growth of the hatching larvae. When the larvae grow up to megalopa, they migrate back to estuaries and coasts in virtue of the flood tide, settle and recruit adult habitats and metamorphose into the crablet stage. Adult crab can even survive in a wide salinity of 0–35 ppt. To investigate the mRNA profile after salinity stress, S. paramamosain megalopa were exposed to different salinity seawater (low, 14 ppt; control, 25 ppt; high, 39 ppt).

Results

Firstly, from the expression profiles of Na+/K+/2Cl- cotransporter, chloride channel protein 2, and ABC transporter, it turned out that the 24 h might be the most influenced duration in the short-term stress. We collected megalopa under different salinity for 24 h and then submitted to mRNA profiling. Totally, 57.87 Gb Clean Data were obtained. The comparative genomic analysis detected 342 differentially expressed genes (DEGs). The most significantly DEGs include gamma-butyrobetaine dioxygenase-like, facilitated trehalose transporter Tret1, sodium/potassium-transporting ATPase subunit alpha, rhodanese 1-like protein, etc. And the significantly enriched pathways were lysine degradation, choline metabolism in cancer, phospholipase D signaling pathway, Fc gamma R-mediated phagocytosis, and sphingolipid signaling pathway. The results indicate that in the short-term salinity stress, the megalopa might regulate some mechanism such as metabolism, immunity responses, osmoregulation to adapt to the alteration of the environment.

Conclusions

This study represents the first genome-wide transcriptome analysis of S. paramamosain megalopa for studying its stress adaption mechanisms under different salinity. The results reveal numbers of genes modified by salinity stress and some important pathways, which will provide valuable resources for discovering the molecular basis of salinity stress adaptation of S. paramamosain larvae and further boost the understanding of the potential molecular mechanisms of salinity stress adaptation for crustacean species.

A single von Willebrand factor C-domain protein acts as an extracellular pattern-recognition receptor in the river prawn Macrobrachium nipponense

The single von Willebrand factor C-domain proteins (SVWCs) are mainly found in arthropods. Their expression may be regulated by several environmental stresses, including nutritional status and bacterial and viral infections. However, the underlying regulatory mechanism is unclear. In the present study, we identified a member of the SVWC family from the river prawn Macrobrachium nipponense as a soluble and bacteria-inducible pattern-recognition receptor (designated MnSVWC). In vitro, recombinant MnSVWC exhibited pronounced binding and Ca²⁺-dependent agglutinating abilities against diverse microbes, including Gram-negative bacteria (i.e. Escherichia coli and Aeromonas victoria), Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), and yeast (Pichia pastoris). ELISA assays revealed that recombinant MnSVWC recognizes a broad range of various pathogen-associated molecular patterns (PAMPs) and has high affinity to lipopolysaccharide and lysine-type and diaminopimelic acid-type peptidylglycan and d-galactose and low affinity to d-mannan and β-1,3-glucan. Mutant MnSVWC^P57A with an impaired Glu-Pro-Asn (EPN) motif displayed reduced affinity to all these PAMPs to varying extent. Moreover, MnSVWC bound to the surface of hemocytes and promoted their phagocytic activity and clearance of invasive bacteria. RNAi-mediated MnSVWC knockdown in prawn reduced the ability to clear invading bacteria, but did not block the activities of the Toll pathway or the arthropod immune deficiency (IMD) pathway, or the expression of antimicrobial peptide genes. These results indicate that MnSVWC functions as an extracellular pattern-recognition receptor in M. nipponense that mediates cellular immune responses by recognizing PAMPs, agglutinating invasive microbes, and promoting phagocytosis in hemocytes.

Evaluation of the expression stability of β-actin under bacterial infection in Macrobrachium nipponense

The selection of a suitable reference gene is an important prerequisite for the precise analysis of target gene expression by real-time quantitative PCR (qPCR). The present study aims to explore the expression pattern of the Macrobrachium nipponense (M. nipponense) β-actin gene under Aeromonas hydrophila bacterial infection conditions. The complete sequence of the β-actin gene from M. nipponense was cloned by PCR. Identified and named β-actin genes were searched in the NCBI database, and the characteristics of the β-actin gene were analyzed using bioinformatics methods. The expression profiles of β-actin under stresses challenged by bacteria after 3, 6, 12, 24 and 48 h were investigated by measuring Ct values by qPCR. The prokaryotic expression vector pET-30a-actin was constructed by PCR and recombinant DNA techniques. Fused protein was induced by IPTG in the transformed Escherichia coli BL21 (DE3). Recombinant rActin was purified by nickel column. The bioinformatics analysis result revealed that the deduced protein encoded by the β-actin gene from M. nipponense had the highest homology with other prawns in the homologous assay (99%). The phylogenetic tree indicates that the β-actin from M. nipponense and other crustaceans have a single cluster. The qPCR results revealed that a stable expression of β-actin was observed in response to the A. hydrophila challenge for 3-48 h, and the Ct value was 22 ± 1.5. β-actin was ranked as a stable gene after the bacterial challenge, which was selected as the appropriate reference gene in M. nipponense.

Molecular identification and characterization of rhodaneses from the insect herbivore Pieris rapae

The association of cabbage white butterflies (Pieris spec., Lepidoptera: Pieridae) with their glucosinolate-containing host plants represents a well-investigated example of the sequential evolution of plant defenses and insect herbivore counteradaptations. The defensive potential of glucosinolates, a group of amino acid-derived thioglucosides present in plants of the Brassicales order, arises mainly from their rapid breakdown upon tissue disruption resulting in formation of toxic isothiocyanates. Larvae of P. rapae are able to feed exclusively on glucosinolate-containing plants due to expression of a nitrile-specifier protein in their gut which redirects glucosinolate breakdown to the formation of nitriles. The release of equimolar amounts of cyanide upon further metabolism of the benzylglucosinolate-derived nitrile suggests that the larvae are also equipped with efficient means of cyanide detoxification such as β-cyanoalanine synthases or rhodaneses. While insect β-cyanoalanine synthases have recently been identified at the molecular level, no sequence information was available of characterized insect rhodaneses. Here, we identify and characterize two single-domain rhodaneses from P. rapae, PrTST1 and PrTST2. The enzymes differ in their kinetic properties, predicted subcellular localization and expression in P. rapae indicating different physiological roles. Phylogenetic analysis together with putative lepidopteran rhodanese sequences indicates an expansion of the rhodanese family in Pieridae.