Xiangquan Liu

Shanghai Ocean University, Shanghai, Shanghai Shi, China

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Publications (9)21.33 Total impact

  • 01/2014; 13(1).
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    ABSTRACT: Lipopolysaccharide-induced TNF-α factor (LITAF) is one of the most important transcription factors mediating TNF-α transcription. In the present study, a LITAF gene (designated as SgLITAF) was identified from razor clams Solen grandis. The full-length cDNA of SgLITAF was of 1476 bp, encoding a polypeptide of 130 amino acids showed high similarity to other known LITAFs. SgLITAF encoded a LITAF domain and the Zn(2+)-binding motifs in the domain were well conserved. The mRNA transcripts of SgLITAF were detected in all tested tissues of healthy razor clams, including mantle, gill, gonad, hemocytes, muscle and hepatopancreas, and with the highest expression level in hepatopancreas. The expression level of SgLITAF in hemocytes was significantly up-regulated (P < 0.01) after razor clams were stimulated by LPS or β-1, 3-glucan, but no obvious fluctuation of SgLITAF mRNA expression was observed after PGN stimulation. All the results indicated that there might be a LITAF-regulated TNF-α signaling pathway existing in S. grandis, which involved in the immune response not only against gram-negative bacteria but also towards fungi.
    Fish &amp Shellfish Immunology 07/2013; · 2.96 Impact Factor
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    ABSTRACT: Serine proteinase inhibitor (SPI) serves as a negative regulator in immune signal pathway by restraining the activities of serine proteinase (SP) and plays an essential role in the innate immunity. In the present study, a Kunitz-type SPI was identified from the mollusk razor clam Solen grandis (designated as SgKunitz). The full-length cDNA of SgKunitz was of 1284 bp, containing an open reading frame (ORF) of 768 bp. The ORF encoded four Kunitz domains, and their amino acids were well conserved when compared with those in other Kunitz-type SPIs, especially the six cysteines involved in forming of three disulfide bridges in each domain. In addition, the tertiary structure of all the four domains adopted a typical model of Kunitz-type SPI family, indicating SgKunitz was a new member of Kunitz-type SPI superfamily. The mRNA transcripts of SgKunitz were detected in all tested tissues of razor clam, including muscle, mantle, gonad, gill, hepatopancreas and hemocytes, and with the highest expression level in gill. When the razor clams were stimulated by LPS, PGN or β-1, 3-glucan, the expression level of SgKunitz mRNA in hemocytes was significantly up-regulated (P < 0.01), suggesting SgKunitz might involved in the processes of inhibiting the activity of SPs during the immune responses triggered by various pathogens. Furthermore, the recombinant protein of SgKunitz could effectively inhibit the activities of SP trypsin and chymotrypsin in vitro. The present results suggested SgKunitz could serve as an inhibitor of SP involving in the immune response of S. grandis, and provided helpful evidences to understand the regulation mechanism of immune signal pathway in mollusk.
    Fish &amp Shellfish Immunology 09/2012; · 2.96 Impact Factor
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    ABSTRACT: C-type lectin and galectin are two types of animal carbohydrate-binding proteins which serve as pathogen recognition molecules and play crucial roles in the innate immunity of invertebrates. In the present study, a C-type lectin (designated as SgCTL-1) and galectin (designated as SgGal-1) were identified from mollusk Solen grandis, and their expression patterns, both in tissues and toward three pathogen-associated molecular patterns (PAMPs) stimulation were characterized. The full-length cDNA of SgCTL-1 and SgGal-1 was 1280 and 1466 bp, containing an open reading frame (ORF) of 519 and 1218 bp, respectively. Their deduced amino acid sequences showed high similarity to other members of C-type lectin and galectin superfamily, respectively. SgCTL-1 encoded a single carbohydrate-recognition domain (CRD), and the motif of Ca(2+)-binding site 2 was EPN (Glu(135)-Pro(136)-Asn(137)). While SgGal-1 encoded two CRDs, and the amino acid residues constituted the carbohydrate-binding motifs were well conserved in CRD1 but partially conserved in CRD2. Although SgCTL-1 and SgGal-1 exhibited different tissue expression pattern, they were both constitutively expressed in all tested tissues, including hemocytes, gonad, mantle, muscle, gill and hepatopancreas, and they were both highly expressed in hepatopancreas and gill. Furthermore, the mRNA expression of two lectins in hemocytes was significantly (P < 0.01) up-regulated with different levels after S. grandis were stimulated by lipopolysaccharide (LPS), peptidoglycan (PGN) or β-1,3-glucan. Our results suggested that SgCTL-1 and SgGal-1 from razor clam were two novel members of animal lectins, and they might function as pattern recognition receptors (PRRs) taking part in the process of pathogen recognition.
    Fish &amp Shellfish Immunology 04/2012; 33(2):204-12. · 2.96 Impact Factor
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    ABSTRACT: Sialic acid-binding lectin (SABL) plays crucial role in both innate and adaptive immune responses benefiting from its predominant affinity toward glycan. In the present study, two SABLs from razor clam Solen grandis (designated as SgSABL-1 and SgSABL-2) were identified, and their expression patterns, both in tissues and towards microorganism glycan stimulation, were then characterized. The cDNA of SgSABL-1 and SgSABL-2 was 988 and 1281 bp, containing an open reading frame (ORF) of 744 and 570 bp, respectively, and deduced amino acid sequences showed high similarity to other invertebrates SABLs. Both SgSABL-1 and SgSABL-2 encoded a C1q domain. SgSABL-1 and SgSABL-2 were found to be constitutively expressed in a wide range of tissues with different levels, including mantle, gill, gonad, hemocyte, muscle, and hepatopancreas, and both of them were highly expressed in hepatopancreas. SgSABL-1 and SgSABL-2 could be significantly induced after razor clams were stimulated by acetylated subunits-containing glycan LPS and PGN, suggesting the two SgSABLs might perform potential function of glycan recognition. In addition, SgSABL-2 could also be induced by β-1,3-glucan. All these results indicated that SgSABL-1 and SgSABL-2 might be involved in the immune response against microbe infection and contributed to the pathogens recognition.
    Fish &amp Shellfish Immunology 04/2012; 32(4):578-85. · 2.96 Impact Factor
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    ABSTRACT: Glutathione S-transferases (GSTs) are a superfamily of antioxidant enzymes, which play crucial roles in detoxification and protection of tissues from oxidative damage caused by reactive oxygen species (ROS). In this study, a sigma-class GST was identified from razor clam Solen grandis (designated as SgGST-S1), and its expression patterns, both in tissues and toward microorganism glycan as well as organic contaminants stimulation, were then characterized. The full-length cDNA of SgGST-S1 was of 1291 bp, containing a 5' untranslated region (UTR) of 27 bp, and a 3' UTR of 619 bp with a poly (A) tail. The open reading frame (ORF) was of 645 bp, encoding a polypeptide of 214 amino acids with the predicted molecular weight of 24.8 kDa, which shared 47% identity with GST from Ruditapes philippinarum. The analysis of conserved domain and phylogenetic relationship strongly suggested that SgGST-S1 was a member of sigma-class GST. The mRNA of SgGST-S1 was constitutively expressed in all tested tissues of healthy razor clam, including mantle, gill, gonad, hemocytes, muscle, and hepatopancreas, and it was highly expressed in hepatopancreas. The mRNA expression of SgGST-S1 in hemocytes was significantly up-regulated (P < 0.01) after razor clam was stimulated by peptidoglycan (PGN) or β-1, 3-glucan, but not LPS. In addition, the SgGST-S1 transcript level was also significantly (P < 0.01) induced by exposure of benzo[a]pyrene (B[a]P) or Polybrominated Diphenyl Ethers (PBDE). All the results indicated that SgGST-S1 might serve as an antioxidant enzyme involving in the detoxification cause by both microorganism glycan and organic contaminants.
    Fish &amp Shellfish Immunology 03/2012; 32(6):1198-204. · 2.96 Impact Factor
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    ABSTRACT: Peptidoglycan recognition proteins (PGRPs) play crucial role in innate immunity for both invertebrates and vertebrates, owing to their prominent ability in detecting and eliminating invading bacteria. In the present study, two short PGRPs from mollusk Solen grandis (designated as SgPGRP-S1 and SgPGRP-S2) were identified, and their expression patterns, both in tissues and toward three PAMPs stimulation, were then characterized. The full-length cDNA of SgPGRP-S1 and SgPGRP-S2 was 1672 and 1285 bp, containing an open reading frame (ORF) of 813 and 426 bp, respectively, and deduced amino acid sequences showed high similarity to other members of PGRP superfamily. Both SgPGRP-S1 and SgPGRP-S2 encoded a PGRP domain. The motif of Zn(2+) binding sites and amidase catalytic sites were well conserved in SgPGRP-S1, but partially conserved in SgPGRP-S2. The two PGRPs exhibited different tissue expression pattern. SgPGRP-S1 was highly expressed in muscle and hepatopancreas, while SgPGRP-S2 was highly in gill and mantle. The mRNA expression of SgPGRP-S1 could be induced acutely by stimulation of PGN, and also moderately by β-1,3-glucan, but not by LPS, while expression of SgPGRP-S2 was significantly up-regulated (P < 0.01) when S. grandis was stimulated by all the three PAMPs, though the expression levels were relatively lower than SgPGRP-S1. Our results suggested SgPGRP-S1 and SgPGRP-S2 could serve as pattern recognition receptors (PRRs) involved in the immune recognition of S. grandis, and they might perform different functions in the immune defense against invaders.
    Fish &amp Shellfish Immunology 11/2011; 32(1):178-85. · 2.96 Impact Factor
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    ABSTRACT: C-type lectins play crucial roles in innate immunity to recognize and eliminate pathogens efficiently. In the present study, two C-type lectins from shrimp Litopenaeus vannamei (designated as LvLectin-1 and LvLectin-2) were identified, and their expression patterns, both in tissues and toward pathogen stimulation, were then characterized. The full-length cDNA of LvLectin-1 and LvLectin-2 was 567 and 625 bp, containing an open reading frame (ORF) of 471 and 489 bp, respectively, and deduced amino acid sequences showed high similarity to other members of C-type lectin superfamily. Both two C-type lectins encoded a single carbohydrate-recognition domain (CRD). The motif of Ca(2+) binding site 2 in CRD, which determined carbohydrate-binding specificity, was QPN (Gln(122)-Pro(123)-Asn(124)) in LvLectin-1, but QPD (Gln(128)-Pro(129)-Asp(130)) in LvLectin-2. Two C-type lectins exhibited similar tissue expression pattern, for their mRNA were both constitutively expressed in all tested tissues, including hepatopancreas, muscle, gill, hemocytes, gonad and heart, furthermore they were both mostly expressed in hepatopancreas, though the expression level of LvLectin-2 was much higher than LvLectin-1. The expression level of two C-type lectins mRNA in hemocytes varied greatly after the challenge of Listonella anguillarum or WSSV. After L. anguillarum challenge, the expression of both C-type lectins were significantly (P<0.01) up-regulated compared with blank group, and LvLectin-1 exhibited higher level than LvLectin-2; while after the stimulation of WSSV, the expression of LvLectin-2 was significantly up-regulated at 6 h (P<0.01) and 12 h (P<0.05), but the expression level of LvLectin-1 down-regulated significantly (P<0.01) to 0.4-fold at 6 and 12 h post-stimulation. The results indicated that the two C-type lectins might be involved in immune response toward pathogen infection, and they might perform different recognition specificity toward bacteria or virus.
    Fish &amp Shellfish Immunology 11/2011; 32(1):132-40. · 2.96 Impact Factor
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    ABSTRACT: Morphology of the spermatozoon of Octopus ocellatus was studied by light, scanning electron, and transmission electron microscopes. Sperm are 600–700 μm long, with a large number of granules in diameter about 130 nm. Each spermatozoon is composed of a head, neck, and tail. The head is made up of an acrosomal complex anterior to the nucleus. The spiral acrosomal complex consists of an electron-lucent vesicle, lacuna, and an electron-dense acrosomal vesicle. Additionally, the spiral acrosomal vesicle has numerous equidistant striations, and is surrounded by many small granules (20 nm diameter). A long straight nucleus, which is electron-densed, has a deep posterior concavity, the nuclear vacuole. At the terminal end of the nucleus is a sleeve-like structure with a concave posterior nuclear fossa (PNF). The neck is short connecting the PNF. The basal body is located in the PNF and gives rise to the axoneme. This structure connects the head, neck, and tail. The tail is divided into a middle piece and a principal piece. The middle piece, having a 9+9+2 arrangement, is surrounded by a mitochondrial sheath and terminates by an electron-dense fibrous sheath. The principal piece is the longest part of the sperm with coarse fibers tapering posteriorly. The results of this study shall provide some useful information for artificial breeding of this species. Keywordsperm length–structure–acrosomal complex–nucleus
    Chinese Journal of Oceanology and Limnology 01/2011; 29(1):199-205. · 0.58 Impact Factor

Publication Stats

25 Citations
21.33 Total Impact Points

Institutions

  • 2013
    • Shanghai Ocean University
      Shanghai, Shanghai Shi, China
  • 2012
    • Chinese Academy of Sciences
      Peping, Beijing, China
  • 2011–2012
    • South China Sea Fisheries Research Institute
      Shengcheng, Guangdong, China