Zhi Liao

Molecular characterization of a novel antimicrobial peptide from Mytilus coruscus.

Antimicrobial peptides (AMPs) are components of the innate immune responses that form the first line of host defense against pathogens. Marine mussels can produce a surprising abundance of cysteine-rich AMPs pertaining to the defensin, myticin, mytilin and mytimycin families, particularly in the circulating hemocytes. In the current study, we purified and characterized a novel cysteine-rich peptide with remarkable antibacterial activity from Mytilus coruscus and designated with myticusin-1, a 104-amino acid long polypeptide including 10 cysteine residues forming an unusual cysteine pattern. Antimicrobial assays demonstrated that myticusin-1 exhibited stronger anti-microbial properties against Gram-positive bacteria more than Gram-negative bacteria and fungus. Furthermore, myticusin-1 caused significant morphological alterations in both Sarcina luteus and Escherichia coli as shown by transmission electron microscopy (TEM). The cDNA of myticusin-1 was cloned and sequenced from the hemocytes cDNA library of M. coruscus. The mRNA transcripts of myticusin-1 are mainly detected in hemocyte, which indicates that myticusin-1 are specifically synthesized and stored in circulating hemocytes. The expression level of myticusin-1 in hemocytes was up-regulated and reached the highest level at 36 h after S. luteus challenge, which was 20-fold increase compared to that of the control group. These results indicated that myticusin-1 was involved in the host immune response against bacterial infection and might contribute to the clearance of invading bacteria.

In-depth proteomic analysis of nacre, prism, and myostracum of Mytilus shell.

UNLABELLED Mytilus is an economically important bivalve and its shell is a biomineralized tissue with various microstructures/layers. In the present study, the shell of marine mussel, Mytilus coruscus, was analyzed and three shell layers with different morphologies and polymorphs were observed, which includes nacre, fibrous prism, and myostracum strongly attached by adductor muscles to the interior of the shell surface. In order to understand whether these different shell layers contain different shell matrix proteins (SMPs), the transcriptome sequencing of M. coruscus mantle and a parallel proteomic analysis of SMPs in the three shell layers were performed. A combination of LC-MS/MS analysis with the mantle transcriptome dataset search resulted in the identification of a total of 63 proteins from M. coruscus shell. From this protein set, fifteen, fourteen, and eight proteins were found to be unique to nacre, fibrous prism, and myostracum layers, respectively. In addition, many novel shell proteins were also identified. The data in this study could be used as a background to explore the roles of SMPs in the deposition of different shell layers (nacre vs. fibrous prism vs. myostracum), the different polymorphisms of calcium carbonate (aragonite vs. calcite); and further, the identified proteins from the myostracum could provide candidates for studying the mechanism of adductor muscle-shell attachment. BIOLOGICAL SIGNIFICANCE In this paper, we characterized for the first time the protein set from different shell layers in Mytilus. Shell matrix proteins are the major component that controls different aspects of the shell formation process and thus a source of bioactive molecules that would offer interesting perspectives in biomaterials and biomedical fields. Our data can be used as a resource for further exploring the roles of shell matrix proteins in the deposition of different shell layers (nacre vs. fibrous prism vs. myostracum) or different polymorphisms of calcium carbonate (aragonite vs. calcite), and the identified protein set of myostracum provided candidates for studying the mechanism of adductor muscle-shell attachment.

Characterization of a novel antimicrobial peptide with chiting-biding domain from Mytilus coruscus

Using reverse phase high performance liquid chromatography (RP-HPLC), a novel antimicrobial peptide with 55 amino acid residues was isolated from the hemolymph of Mytilus coruscus. This new antimicrobial peptide displays predominant antimicrobial activity against fungi and Gram-positive bacteria. The molecular mass and the N-terminal sequence of this peptide were analyzed by Mass Spectrometry and Edman degradation, respectively. This antimicrobial peptide, with molecular mass of 6621.55 Da, is characterized by a chitin-biding domain and by 6 Cysteine residues engaged in three intra-molecular disulfide bridges. The full-length of cDNA sequence of this new peptide was obtained by rapid amplification of cDNA ends (RACE) and the encoded precursor was turn out to be a chitotriosidase-like protein. Therefore, we named the precursor with mytichitin-1 and the new antimicrobial peptide (designated as mytichitin-CB) is the carboxyl-terminal part of mytichitin-1. The mRNA transcripts of mytichitin-1 are mainly detected in gonad and the expression level of mytichitin-1 in gonad was up-regulated and reached the highest level at 12 h after bacterial challenge, which was 9-fold increase compared to that of the control group. These results indicated that mytichitin-1 was involved in the host immune response against bacterial infection and might contribute to the clearance of invading bacteria.

Layer-by-Layer Proteomic Analysis of Mytilus galloprovincialis Shell.

Bivalve shell is a biomineralized tissue with various layers/microstructures and excellent mechanical properties. Shell matrix proteins (SMPs) pervade and envelop the mineral crystals and play essential roles in biomineralization. Despite that Mytilus is an economically important bivalve, only few proteomic studies have been performed for the shell, and current knowledge of the SMP set responsible for different shell layers of Mytilus remains largely patchy. In this study, we observed that Mytilus galloprovincialis shell contained three layers, including nacre, fibrous prism, and myostracum that is involved in shell-muscle attachment. A parallel proteomic analysis was performed for these three layers. By combining LC-MS/MS analysis with Mytilus EST database interrogations, a whole set of 113 proteins was identified, and the distribution of these proteins in different shell layers followed a mosaic pattern. For each layer, about a half of identified proteins are unique and the others are shared by two or all of three layers. This is the first description of the protein set exclusive to nacre, myostracum, and fibrous prism in Mytilus shell. Moreover, most of identified proteins in the present study are novel SMPs, which greatly extended biomineralization-related protein data of Mytilus. These results are useful, on one hand, for understanding the roles of SMPs in the deposition of different shell layers. On the other hand, the identified protein set of myostracum provides candidates for further exploring the mechanism of adductor muscle-shell attachment.

In-depth proteomic analysis of the byssus from marine mussel Mytilus coruscus.

UNLABELLED Mussels attach to various submerged surfaces by using the byssus, which contains different proteins and is a promising source of water-resistant bio-adhesives for potential use in biotechnological and medical applications. The protein composition of the byssus has not yet been fully understood although at least eleven byssal proteins were characterized previously. In order to increase genomic resources and identify new byssal proteins from mussel Mytilus coruscus, high-throughput Illumina sequencing was undertaken on the foot, and 79,997,776 paired-ends reads were generated, yielding a library containing 88,825ft unigenes. The M. coruscus byssus was divided into three parts, the proximal thread, the distal thread, and the plaque. Byssal proteins from each part of the byssus were analyzed by shotgun-LTQ analysis. The MS/MS spectra were searched against the foot unigenes dataset and 48 byssal proteins were identified from the M. coruscus byssus. From the whole set, 17, 5, and 11 proteins were exclusive to the proximal thread, the distal thread, and the plaque, respectively. These data can be used as a resource for further studies on the roles of byssal proteins in the deposition of different byssus parts (thread vs. plaque) or in the different mechanical properties (tenacity vs. adhesion). BIOLOGICAL SIGNIFICANCE Byssal proteins are the major component that controls different aspects of the byssal formation process and thus a source of bioactive molecules that would offer interesting perspectives in biomaterials and bio-adhesive fields. In this paper, we characterized the protein set from different partsof Mytilus coruscus byssus by a combination of transcriptome/proteome technical. A whole set of 48 byssal proteins were described here, including proteins of collagen-like, C1q domain-containing, protease inhibitor-like, tyrosinase-like, SOD, and others. Thread (the distal portion and the proximal portion) and plaque showed distinct protein composition. Of the whole byssal protein set, 11 are exclusive to the plaque, 17 are exclusive to the proximal thread, and 5 are exclusive to the distal thread. Only four proteins are shared by all the three parts of the byssus. The new byssal proteins reported here represent a significant expansion of the knowledge base of Mytilus byssal proteins, and are important for further exploring the mechanism of adhesion in mussel.

Isolation and antibacterial activity of anabaena phycocyanin

The isolation and antibacterial activity of anabaena phycocyanin were investigated. The result indicates that three kinds of protein ingredients: PC-A, PC-B and PC-C were obtained using high performance liquid chromatography. The estimated molecular masses of PC-A and PC-B were 14 to 18 kD. PC-B and PC-C had certain antibacterial activity on Bibrio parahemolyticus , Bacillus mucilaginosus and Sarcina lutea . In addition, PC-C had certain antibacterial activity on Vibrio harveyi. PC-A did not possess antibacterial activity in the study. Keywords: Anabaena, phycocyanin, liquid chromatogram, antibacterial African Journal of Biotechnology Vol. 12(15), pp. 1869-1873

The expression of superoxide dismutase in Mytilus coruscus under various stressors

ABSTRACT Superoxide dismutases (SODs), a by‐product of antioxidative defence system, protects organisms for eliminating excess reactive oxygen species (ROS) and maintaining the redox balance of immune system. The complete open reading frames (ORFs) of Cu/Zn‐SOD and Mn‐SOD were identified from Mytilus coruscus (designated as McSOD and MnSOD) by homologous cloning. The sequence lengths were 474bp and 687bp, encoding 157 and 228 amino acids respectively. The deduced amino acid sequences of McSOD and MnSOD shared high identities with Cu/Zn‐SOD and Mn‐SOD from other mollusca. The distributions of McSOD and MnSOD were detected in six tissues including adductor, hemocyte, gill, gonad, mantle and hepatopancreas, and the highest expressions were both in gills. The temporal expression of McSOD and MnSOD were up‐regulated in gills under a variety of stress factors, including Vibrio parahemolyticus, Aeromonas hydrophila, Cu2+ and Pb2+. After being challenged with V. Parahemolyticus, the expressions of McSOD and MnSOD were increased rapidly at the initial hours, reaching the peaks of 4.9‐fold and 15.3‐fold respectively, and got to the highest levels of 43.5‐fold and 7.1‐fold after being challenged with A. hydrophila. The highest point of McSOD mRNA appeared at 15 d after being exposed to copper (7‐fold at 0.5 mg/L and 13.2‐fold at 1.5 mg/L), except for 0.1 mg/L group of Cu2+ maintaining to the normal level, but plumbum at 1 d (2.4‐fold at 1.0 mg/L and 4.4‐fold at 3.0 mg/L) and at 15 d (2.1‐fold at 0.2 mg/L). The temporal expression peaks of MnSOD appeared differently after exposing to copper of various concentrations (0.1 mg/L at 10 d with 4.7‐fold, 0.5 mg/L at 1 d with 17.9‐fold and 1.5 mg/L at 3 d with 13.2‐fold). Whereas in plumbum exposing treatments, the 3.0 mg/L group jumped to the peak at 1 d (18.2‐fold), the 0.2 mg/L and 1.0 mg/L groups had little change and maintained at the normal level throughout the experiment. The results provided several new evidences for further understanding of the regulatory mechanism of SOD on the innate immune system in bivalve. HighlightsIntracellular Cu/Zn SOD and Mn SOD were identified from Mytilus coruscus.The functional domains and some crucial amino acids in two SODs were conserved.They were constitutively expressed in different tissues but highest in gill.Their temporal expression were up‐regulated under various stressors.The results might be helpful to comprehend immune response of SOD in bivalve.

Correction: Layer-by-Layer Proteomic Analysis of Mytilus galloprovincialis Shell

There is an error in affiliation 1 for authors Peng Gao and Shu-wei Xia. Affiliation 1 should be: College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, China.

Genomic structure and promoter functional analysis of GnRH3 gene in large yellow croaker (Larimichthys crocea)

Gonadotropin-releasing hormone III (GnRH3) is considered to be a key neurohormone in fish reproduction control. In the present study, the cDNA and genomic sequences of GnRH3 were cloned and characterized from large yellow croaker Larimichthys crocea. The cDNA encoded a protein of 99 amino acids with four functional motifs. The full-length genome sequence was composed of 3797 nucleotides, including four exons and three introns. Higher identities of amino acid sequences and conserved exon-intron organizations were found between LcGnRH3 and other GnRH3 genes. In addition, some special features of the sequences were detected in partial species. For example, two specific residues (V and A) were found in the family Sciaenidae, and the unique 75-72 bp type of the open reading frame 2 and 3 existed in the family Cyprinidae. Analysis of the 2576 bp promoter fragment of LcGnRH3 showed a number of transcription factor binding sites, such as AP1, CREB, GATA-1, HSF, FOXA2, and FOXL1. Promoter functional analysis using an EGFP reporter fusion in zebrafish larvae presented positive signals in the brain, including the olfactory region, the terminal nerve ganglion, the telencephalon, and the hypothalamus. The expression pattern was generally consistent with the endogenous GnRH3 GFP-expressing transgenic zebrafish lines, but the details were different. These results indicate that the structure and function of LcGnRH3 are generally similar to the other teleost GnRH3 genes, but there exist some distinctions among them.

A novel interleukin-1 receptor-associated kinase-4 from thick shell mussel Mytilus coruscus is involved in inflammatory response

Interleukin-1 receptor-associated kinase-4 (IRAK4) is considered as the most upstream kinase of IRAKs and plays a vital role in Toll-like receptor/Interleukin-1 receptor (TLR/IL-1R) signal transduction. In the present study, IRAK4 from thick shell mussel Mytilus coruscus (McIRAK4) was identified and characterized. McIRAK4 showed the most similarity to its counterparts in bivalves. The conserved death domain (DD) and catalytic domain of serine/threonine kinases (STKc) were predicted in all examined IRAK4s. McIRAK4 transcripts were constitutively expressed in all examined tissues with the higher expression level in immune related tissues, and were significantly induced in haemocytes upon lipopolysaccharide (LPS) and polyinosinic-polycytidylic acid (poly I:C) challenge. Further, the expression of McIRAK4 was obviously repressed by dsRNA mediated RNA interference (RNAi), meanwhile the proinflammatory cytokines TNF-alpha and IL17 were down-regulated while the antiinflammatory cytokine TGF-β was up-regulated. Additionally, McIRAK4 showed a global cytoplasmic localization in HEK293T cells through fluorescence microscopy. These results collectively indicated that McIRAK4 is one member of IRAK4 subfamily and might play the potential signal transducer role in inflammatory response. The present study provides supplement for TLR-mediated signaling pathway triggered by pathogenic invasions in thick shell mussel, and contributes to the clarification of the innate immune response in molluscs.