Expression of Macrobrachium rosenbergii lipopolysaccharide- and β-1,3-glucan-binding protein (LGBP) in Saccharomyces cerevisiae and evaluation of its immune function

Characterization of a Lipopolysaccharide- and Beta-1,3-Glucan Binding Protein (LGBP) from the Hepatopancreas of Freshwater Prawn, Macrobrachium rosenbergii, Possessing Lectin-Like Activity

The study focuses on the isolation, characterization, and expression analysis of a lectin from the hepatopancreas of Macrobrachium rosenbergii. The protein was isolated by affinity chromatography on a melibiose-agarose column. The molecular weight of the native protein was found to be ~120 kDa which consists of a single polypeptide of ~39.5 kDa. On mass spectrometric analysis, the protein was identified as lipopolysaccharide- and beta-1,3-glucan binding protein (LGBP). LGBP showed hemagglutination with rabbit RBC like a lectin and its carbohydrate-binding specificity was determined by the hemagglutination inhibition test. The protein also showed antibacterial activity against two Gram-negative bacteria Vibrio harveyi and Aeromonas sobria, and one Gram positive bacteria Bacillus cereus in the disc diffusion test. Rabbit antiserum was raised against the purified LGBP and used to develop a sandwich ELISA system for quantitation of the protein in hepatopancreas and serum samples of M. rosenbergii. The expression of the LGBP transcripts in muscle, hepatopancreas, and gill tissues from M. rosenbergii juveniles at 72 h post-challenge of V. harveyi was not modulated as noticed in qPCR analysis. However, significant increases in the concentrations of LGBP protein in hepatopancreas (5.23 ± 0.45 against 3.43 ± 0.43 mg/g tissue in control) and serum (1.08 ± 0.14 against 0.61 ± 0.08 µg/ml in control) were observed in the challenged group of prawns in ELISA suggesting its putative role against bacterial infections. The study for the first time characterized the native LGBP of M. rosenbergii showing a multifunctional role in immunity.

Identification of Potential Gene Targets for Suppressing Oviposition in Holotrichia parallela Using Comparative Transcriptome Analysis

Holotrichia parallela is an important plant pest. Comparative feeding experiments showed that the egg production, oviposition duration and survival rate of H. parallela beetles were significantly higher when they fed on elm leaves than when they fed on willow or purpus privet leaves. RNA sequencing was used to determine transcriptomic changes associated with oviposition. Comparative transcriptome analysis revealed that the beetles that fed on elm and willow had a total of 171 genes with differential expression. When the beetles fed on elm and purpus privet, 3568 genes had differential expression. The vitellogenesis, ovarian serine protease, odorant-binding proteins, acyl-CoA synthetase and follicle cell proteins were commonly upregulated genes in elm-fed beetles compared with those fed on willow/purpus privet leaves. The involvement of the follicle cell protein 3C gene in the regulation of oviposition was confirmed using RNA interference. The results provide insights into the molecular mechanisms underlying oviposition in H. parallela feeding on different host plants. This study also describes a method for identifying potentially effective genes for pest control.

Silencing β-1,3-glucan binding protein enhances the susceptibility of Plutella xylostella to entomopathogenic fungus Isaria cicadae

BACKGROUND

The diamondback moth, Plutella xylostella is a notorious pest of brassicaceae crops globally and has developed serious resistance to insecticide. Insects primarily rely on their innate immunity to defense against various pathogens. In this study, we investigated the immunological functions of a β-1,3-glucan binding protein from P. xylostella (PxβGBP) and evaluated its potential for biocontrolling P. xylostella.

RESULTS

The open reading frame of PxβGBP is 1422 bp encoding 473 amino acids residues. PxβGBP contained a CBM39 domain, a PAC domain and a GH16 domain and shared evolutionary conservation with other lepidoptera βGRPs. PxβGBP was strongly expressed in the third instar larvae and fat body. PxβGBP transcript levels increased significantly after the challenge with microbes, including Isaria cicadae, Escherichia coli and Staphylococcus aureus. PxβGBP was identified in P. xylostella larvae challenged by I cicadae, but not in the naïve insects. Recombinant PxβGBP can directly bind fungal and bacterial cells, and also agglutinate the cells of I cicadae, S. aureus and E coli in a zinc-dependent manner. Knockdown of PxβGBP via RNA interference significantly down-regulated the expression of antimicrobial peptide gene gloverin, and enhanced the susceptibility of P. xylostella to I. cicadae infection, leading to high mortality.

CONCLUSION

These results indicated that PxβGBP plays an important role in the immune response of P. xylostella against I. cicadae infection, and could serve as a potential novel target for pest control. © 2022 Society of Chemical Industry.

A proteomics investigation of 'immune priming' in Penaeus vannamei as shown by isobaric tags for relative and absolute quantification

Invertebrates are considered completely dependent on their innate immunity to defend themselves against pathogens as they lack an adaptive immunity. However, a growing body of evidence has indicated a specific acquired immunity called 'immune priming' may exist. The Pacific white shrimp, Penaeus vannamei is one of the most economically important shrimp species in the world. In the previous research, we investigated the hepatopancreas immune response of shrimp immunized with trans -vp28 gene Synechocystis sp. PCC6803 at the protein level. In this study, on the basis of the previous research, the shrimp were then challenged with WSSV, and hepatopancreas analyzed using isobaric tags for relative and absolute quantification (i TRAQ) labeling. In total, 308 differentially expressed proteins (DEPs) were identified including 84 upregulated and 224 downregulated. Upregulated proteins such as calmodulin B and calreticulin, and downregulated proteins such as calnexin, and signaling pathways like Ras, mTOR were differentially expressed in both studies. Data from this study are more significant than previous work and indicate increased sensitivity to WSSV after immunization with trans-vp28 gene Synechocystis sp. PCC6803. In addition, selected DEPs (upregulated: A0A3R7QHH6 and downregulated: A0A3R7PEF6, A0A3R7MGX8, A0A423TPJ4, and A0A3R7QCC2) were randomly analyzed using parallel reaction monitoring (PRM). These data preliminarily confirm immune priming in P. vannamei, and show that the initial stimulation with trans -vp28 gene Synechocystis sp. PCC6803 regulate P. vannamei immune responses and they provide shrimp with enhanced immune protection against secondary stimulation.

A Kruppel-like factor from Macrobrachium rosenbergii (MrKLF) involved in innate immunity against pathogen infection

Kruppel-like factors (KLFs) belong to a family of zinc finger-containing transcription factors that are widely present in eukaryotes. In the present study, a novel KLF from the giant river prawn Macrobrachium rosenbergii (designated as MrKLF) was successfully cloned and characterized. The full-length cDNA of MrKLF was 1799 bp with an open reading frame of 1332 bp that encodes a putative protein of 444 amino acids, including three conserved ZnF_C2H2 domains at the C-terminus. Multiple alignment analysis showed that MrKLF and other crustacean KLFs shared high similarity. Quantitative real-time PCR analysis revealed that MrKLF mRNA was found in different tissues of prawns and detected in the gills, hepatopancreas, and intestines. After the challenge with Vibrio parahaemolyticus and Aeromonas hydrophila, different expression patterns of MrKLF in the gills, intestines, and hepatopancreas were observed. RNA interference analysis indicated that MrKLF was involved in regulating the expression of four antimicrobial peptides, namely, Crustin (Crus) 2, Crus8, anti-lipopolysaccharide factor (ALF) 1, and ALF3. These results help promote research on M. rosenbergii innate immunity.

Macrobrachium rosenbergii Cu/Zn superoxide dismutase (Cu/Zn SOD) expressed in Saccharomyces cerevisiae and evaluation of the immune function to Vibrio parahaemolyticus

Superoxide dismutases (SODs) are important antioxidant enzymes that occur in virtually all oxygen-respiring organisms, and copper/zinc SOD (Cu/ZnSOD) is one of the most important SODs. In the present study, Macrobrachium rosenbergii Cu/Zn-SOD was expressed in a yeast eukaryotic system. The open reading frame (ORF) of MrCu/ZnSOD was cloned into the plasmid vector pHAC181, and the recombinant plasmid was integrated into the downstream region of the GAL1 promoter in Saccharomyces cerevisiae strain GAL1-ScRCH1 via homologous recombination. The resulting recombinant MrCu/ZnSOD consisted of a 3 × HA-tag at its C-terminal. Via western blot, the molecular weight of the recombinant MrCu/ZnSOD was estimated at about 30 kDa. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of this recombinant MrCu/ZnSOD ranged from 0.556 to 0.840 μM, and from 0.967 to 2.015 μM, respectively. The recombinant MrCu/ZnSOD protein was able to agglutinate four Gram-negative bacterial strains, as well as two of three Gram-positive strains (except Staphylococcus aureus). This demonstrated that the recombinant protein possessed some antimicrobial activity against certain Gram-positive and Gram-negative bacteria. M. rosenbergii were fed with the recombinant yeast strain MrCu/ZnSOD for 4 weeks and then challenged with the most common crustacean pathogen, Vibrio parahaemolyticus. This group of prawns presented lower mortality, higher enzymatic activity, and higher expression of the mRNA of immune-related genes than that in the control groups. Taken together, these results suggest that MrCu/ZnSOD is an antioxidant enzyme and antimicrobial peptide involved in the crustacean innate immune system and offers protection to the host against pathogenic bacteria.