Publications (22)95.63 Total impact
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Article: The evolution and regulation of the mucosal immune complexity in the basal chordate amphioxus.
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ABSTRACT: Both amphioxus and the sea urchin encode a complex innate immune gene repertoire in their genomes, but the composition and mechanisms of their innate immune systems, as well as the fundamental differences between two systems, remain largely unexplored. In this study, we dissect the mucosal immune complexity of amphioxus into different evolutionary-functional modes and regulatory patterns by integrating information from phylogenetic inferences, genome-wide digital expression profiles, time course expression dynamics, and functional analyses. With these rich data, we reconstruct several major immune subsystems in amphioxus and analyze their regulation during mucosal infection. These include the TNF/IL-1R network, TLR and NLR networks, complement system, apoptosis network, oxidative pathways, and other effector genes (e.g., peptidoglycan recognition proteins, Gram-negative binding proteins, and chitin-binding proteins). We show that beneath the superficial similarity to that of the sea urchin, the amphioxus innate system, despite preserving critical invertebrate components, is more similar to that of the vertebrates in terms of composition, expression regulation, and functional strategies. For example, major effectors in amphioxus gut mucous tissue are the well-developed complement and oxidative-burst systems, and the signaling network in amphioxus seems to emphasize signal transduction/modulation more than initiation. In conclusion, we suggest that the innate immune systems of amphioxus and the sea urchin are strategically different, possibly representing two successful cases among many expanded immune systems that arose at the age of the Cambrian explosion. We further suggest that the vertebrate innate immune system should be derived from one of these expanded systems, most likely from the same one that was shared by amphioxus.The Journal of Immunology 02/2011; 186(4):2042-55. · 5.79 Impact Factor -
Article: Genomic and functional uniqueness of the TNF receptor-associated factor gene family in amphioxus, the basal chordate.
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ABSTRACT: The TNF-associated factor (TRAF) family, the crucial adaptor group in innate immune signaling, increased to 24 in amphioxus, the oldest lineage of the Chordata. To address how these expanded molecules evolved to adapt to the changing TRAF mediated signaling pathways, here we conducted genomic and functional comparisons of four distinct amphioxus TRAF groups with their human counterparts. We showed that lineage-specific duplication and rearrangement were responsible for the expansion of amphioxus TRAF1/2 and 3 lineages, whereas TRAF4 and 6 maintained a relatively stable genome and protein structure. Amphioxus TRAF1/2 and 3 molecules displayed various expression patterns in response to microbial infection, and some of them can attenuate the NF-kappaB activation mediated by human TRAF2 and 6. Amphioxus TRAF4 presented two unique functions: activation of the NF-kappaB pathway and involvement in somite formation. Although amphioxus TRAF6 was conserved in activating NF-kappaB pathway for antibacterial defense, the mechanism was not the same as that observed in humans. In summary, our findings reveal the evolutionary uniqueness of the TRAF family in this basal chordate, and suggest that genomic duplication and functional divergence of the TRAF family are important for the current form of the TRAF-mediated signaling pathways in humans.The Journal of Immunology 10/2009; 183(7):4560-8. · 5.79 Impact Factor -
Article: An amphioxus TLR with dynamic embryonic expression pattern responses to pathogens and activates NF-kappaB pathway via MyD88.
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ABSTRACT: A big bang expansion of the Vertebrate-type (V-type) TLRs was reported in amphioxus. To shed lights on its implications, a unique TLR which is reversely inserted into an intron of amphioxus PSMB7-10 by retrotransposition in the highly polymorphic proto-MHC region was cloned from Chinese amphioxus (Branchiostoma belcheri tsingtauense) and named as bbtTLR1. In situ assays showed that bbtTLR1 was predominantly expressed in pharynx and gut from larva to adult stages, which are considered as the first frontlines of amphioxus defense system. Acute immune challenges revealed that the expression of bbtTLR1 was stimulated by bacteria and their cell wall components, while suppressed by Glucan and Poly I:C in the digestive system. Amphioxus also had dozens of TIR adaptors from which we cloned bbtMyD88. BbtMyD88 expressed in 293T cells led to the activation of NF-kappaB pathway through its DEATH and middle domains. Moreover, this activation could be enhanced by bbtTLR1 through the direct association with bbtMyD88. In summary, this study provides evidence for the immune-relation of amphioxus V-type TLRs, and suggests that amphioxus TLR1 and MyD88 represent a basic evolutionary pathway.Molecular Immunology 05/2009; 46(11-12):2348-56. · 2.90 Impact Factor -
Article: Genomic analysis of the immune gene repertoire of amphioxus reveals extraordinary innate complexity and diversity.
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ABSTRACT: It has been speculated that before vertebrates evolved somatic diversity-based adaptive immunity, the germline-encoded diversity of innate immunity may have been more developed. Amphioxus occupies the basal position of the chordate phylum and hence is an important reference to the evolution of vertebrate immunity. Here we report the first comprehensive genomic survey of the immune gene repertoire of the amphioxus Branchiostoma floridae. It has been reported that the purple sea urchin has a vastly expanded innate receptor repertoire not previously seen in other species, which includes 222 toll-like receptors (TLRs), 203 NOD/NALP-like receptors (NLRs), and 218 scavenger receptors (SRs). We discovered that the amphioxus genome contains comparable expansion with 71 TLR gene models, 118 NLR models, and 270 SR models. Amphioxus also expands other receptor-like families, including 1215 C-type lectin models, 240 LRR and IGcam-containing models, 1363 other LRR-containing models, 75 C1q-like models, 98 ficolin-like models, and hundreds of models containing complement-related domains. The expansion is not restricted to receptors but is likely to extend to intermediate signal transducers because there are 58 TIR adapter-like models, 36 TRAF models, 44 initiator caspase models, and 541 death-fold domain-containing models in the genome. Amphioxus also has a sophisticated TNF system and a complicated complement system not previously seen in other invertebrates. Besides the increase of gene number, domain combinations of immune proteins are also increased. Altogether, this survey suggests that the amphioxus, a species without vertebrate-type adaptive immunity, holds extraordinary innate complexity and diversity.Genome Research 08/2008; 18(7):1112-26. · 13.61 Impact Factor -
Article: A short-form C-type lectin from amphioxus acts as a direct microbial killing protein via interaction with peptidoglycan and glucan.
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ABSTRACT: To investigate the evolution and immune function of C-type lectin in amphioxus, the primitive representative of the chordate phylum, we identified three C-type lectins consisting solely of a carbohydrate recognition domain and N-terminal signal peptide and found that they had distinct express patterns in special tissues and immune response to stimulations analyzed by quantitative real-time PCR. We characterized the biochemical and biological properties of AmphiCTL1, which was dramatically up-regulated in amphioxus challenged with Staphylococcus aureus, Saccharomyces cerevisiae, and zymosan. Immunohistochemistry demonstrated that the localization of AmphiCTL1 protein was exclusively detected in the inner folding tissues of the hepatic diverticulum. Recombinant AmphiCTL1 was characterized as a typical Ca2+-dependent carbohydrate-binding protein possessing hemagglutinating activity, preferentially bound to all examined four Gram-positive bacteria and two yeast strains, but had little binding activity toward four Gram-negative bacteria we tested. It aggregated S. aureus and S. cerevisiae in a Ca2+-dependent manner and specifically bound to insoluble peptidoglycan and glucan, but not to LPS, lipoteichoic acid, and mannan. Calcium increased the intensity of the interaction between AmphiCTL1 and those components, but was not essential. This lectin directly killed S. aureus and S. cerevisiae in a Ca2+-independent fashion, and its binding to microorganism cell wall polysaccharides such as peptidoglycan and glucan preceded microbial killing activity. These findings suggested that AmphiCTL1 acted as a direct microbial killing C-type lectin through binding microbial targets via interaction with peptidoglycan and glucan. Thus, AmphiCTL1 may be an evolutionarily primitive form of antimicrobial protein involved in lectin-mediated innate immunity.The Journal of Immunology 01/2008; 179(12):8425-34. · 5.79 Impact Factor -
Article: Molecular and biochemical characterization of galectin from amphioxus: primitive galectin of chordates participated in the infection processes.
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ABSTRACT: A novel F4-carbohydrate recognition domain (CRD)-linker-F3-CRD-type bi-CRD Branchiostoma belcheri tsingtauense galectin (BbtGal)-L together with its alternatively spliced mono-CRD isoform BbtGal-S from amphioxus intestine was encoded by a 9488-bp unique gene with eight exons and seven introns. The recombinant proteins of BbtGal were found to have beta-galactoside-binding activity, indicating that BbtGal was a member of the galectin family. Phylogenetic analysis of this gene along with its splicing form and genome structure suggested that the BbtGal gene was the primitive form of the chordate galectin family. Real-time polymerase chain reaction analyses (PCR) indicated that BbtGal mRNA was expressed during all stages of embryonic development. In terms of tissue distribution, BbtGal-L mRNA was mainly expressed in the immunity-related organs, such as hepatic diverticulum, intestine, and gill, but BbtGal-S was ubiquitously expressed in all tissues. The expression of BbtGal-L mRNA was elevated after acute challenge with various microorganisms, but BbtGal-L only bound to specific bacteria. The immune function of BbtGal was consistent with its localization both outside and inside the cell. Our study on amphioxus galectin may help further understanding of the evolution of chordate galectin in terms of host-pathogen interaction in the immune system.Glycobiology 08/2007; 17(7):774-83. · 3.58 Impact Factor -
Article: Bbt-TNFR1 and Bbt-TNFR2, two tumor necrosis factor receptors from Chinese amphioxus involve in host defense.
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ABSTRACT: Two novel tumor necrosis factor receptors, Bbt-TNFR1 and Bbt-TNFR2, were isolated from Chinese amphioxus, the closest relative to vertebrate. The mRNA of Bbt-TNFR1 encoded a type I membrane protein of 452 amino acids, including four cysteine-rich domains in the extracellular region and a putative TRAF6-binding site at its 154aa long cytoplasmic tail. Bbt-TNFR2 was a 304aa long type I membrane protein, featuring three cysteine-rich domains and a short cytoplasmic tail of just 13 amino acids. Southern blot revealed that Bbt-TNFR1 was a single copy gene, while Bbt-TNFR2 was presented in multiple copies. Sequence comparison indicated that both Bbt-TNFR1 and Bbt-TNFR2 were weakly similar to LT-bR, HVEM, TNFR2, CD40, OX40 and DcR3. Real-time PCR showed that Bbt-TNFR1 and Bbt-TNFR2 were regulated during development and finally had high expression in mucosa-rich tissues in adult stage. Furthermore, up-regulated expression of both genes was also observed in guts after Gram-positive bacteria challenge. However, not like Bbt-TNFR2's slowly and gradually augmentation in the following 48 h, expression of Bbt-TNFR1 dramatically surged up within 4 h and then subsided rapidly. Taking together, Bbt-TNFR1 and Bbt-TNFR2 may involve in the host defense of Chinese amphioxus via distinct fashions.Molecular Immunology 03/2007; 44(5):756-62. · 2.90 Impact Factor -
Article: Acute phase response in zebrafish upon Aeromonas salmonicida and Staphylococcus aureus infection: striking similarities and obvious differences with mammals.
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ABSTRACT: Zebrafish has emerged as a valuable model for immunological studies. However, little is known about the overall picture of its immune response to infectious pathogens. Here we present the first systematic study of its immune response to Aeromonas salmonicida and Staphylococcus aureus, a Gram-negative and a Gram-positive bacteria, respectively. Genes induced upon infection were identified with suppression subtractive hybridization, with many of them encoding acute phase proteins (APPs). When compared with mammals, striking similarities and obvious differences have been observed. Both similar APPs (SAA, hepcidin and haptoglobin, etc.) and a similar system for the induction of APPs (which involves the TLRs, pro-inflammatory cytokines and C/EBPs) were identified, implying evolutionary conserved mechanisms among fish and mammals. Some novel APPs were also discovered, suggesting different immune strategies adopted by fish species. Among which, LECT2 was induced by up to 1000-fold upon infection, shedding new lights on the function of this gene. Our results constitute the first demonstration of a similar while different immune response in zebrafish and open new avenues for the investigation of evolutionary conserved and fish specific mechanisms of innate immunity.Molecular Immunology 02/2007; 44(4):295-301. · 2.90 Impact Factor -
Article: The identification of lymphocyte-like cells and lymphoid-related genes in amphioxus indicates the twilight for the emergence of adaptive immune system.
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ABSTRACT: To seek evidence of a primitive adaptive immune system (AIS) before vertebrate, we examined whether lymphocytes or lymphocyte-like cells and the related molecules participating in the lymphocyte function existed in amphioxus. Anatomical analysis by electron microscopy revealed the presence of lymphocyte-like cells in gills, and these cells underwent morphological changes in response to microbial pathogens that are reminiscent of those of mammalian lymphocytes executing immune response to microbial challenge. In addition, a systematic comparative analysis of our cDNA database of amphioxus identified a large number of genes whose vertebrate counterparts are involved in lymphocyte function. Among these genes, several genes were found to be expressed in the vicinity of the lymphocyte-like cells by in situ hybridization and up-regulated after exposure to microbial pathogens. Our findings in the amphioxus indicate the twilight for the emergence of AIS before the invertebrate-vertebrate transition during evolution.PLoS ONE 02/2007; 2(2):e206. · 4.09 Impact Factor -
Article: Profile of acute immune response in Chinese amphioxus upon Staphylococcus aureus and Vibrio parahaemolyticus infection.
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ABSTRACT: Amphioxus is traditionally considered as the living invertebrate most closely related to vertebrate. However, no systematic study was performed about how the amphioxus defends against the microbial invasion. Here we reported a profile of gene transcription after Staphylococcus aureus (S.c) and Vibrio parahaemolyticus (V.p) challenged by suppression subtractive hybridization (SSH). When compared with mammals, amphioxus has the same acute immune defense genes (lectins, metalloproteinase, lysozymes and antimicrobial peptide, etc.) as well as a similar pattern and level of temporal gene expression. In contrast, amphioxus was demonstrated to have some novel acute immune response genes in response to the microbial challenge, such as apextrin and dermatopontin, which have a 3500-fold and 900-fold induction after the V.p infection, respectively, suggesting new functions in early immune system for these two genes. Our results reported for the first time a profile of primitive immune system defense against infection in protochordate.Developmental & Comparative Immunology 02/2007; 31(10):1013-23. · 3.27 Impact Factor -
Article: Diversity and evolution of conotoxins based on gene expression profiling of Conus litteratus.
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ABSTRACT: Cone snails are attracting increasing scientific attention due to their unprecedented diversity of invaluable channel-targeted peptides. As arguably the largest and most successful evolutionary genus of invertebrates, Conus also may become the model system to study the evolution of multigene families and biodiversity. Here, a set of 897 expressed sequence tags (ESTs) derived from a Conus litteratus venom duct was analyzed to illuminate the diversity and evolution mechanism of conotoxins. Nearly half of these ESTs represent the coding sequences of conotoxins, which were grouped into 42 novel conotoxin cDNA sequences (seven superfamilies), with T-superfamily conotoxins being the dominant component. The gene expression profile of conotoxin revealed that transcripts are expressed with order-of-magnitude differences, sequence divergence within a superfamily increases from the N to the C terminus of the open reading frame, and even multiple scaffold-different mature peptides exist in a conotoxin gene superfamily. Most excitingly, we identified a novel conotoxin superfamily and three novel cysteine scaffolds. These results give an initial insight into the C. litteratus transcriptome that will contribute to a better understanding of conotoxin evolution and the study of the cone snail genome in the near future.Genomics 01/2007; 88(6):809-19. · 3.02 Impact Factor -
Article: Molecular cloning and characterization of CD9 cDNA from cartilaginous fish, red stingray, Dasyatis akajei.
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ABSTRACT: CD9 is a glycoprotein of the transmembrane 4 superfamily (TM4SF) and is involved in various cellular processes. In this study, we describe the isolation of the full-length cDNA encoding for CD9 molecule (daCD9) of red stingray, Dasyatis akajei. This 1252 bp cDNA was isolated from leukocyte cDNA library and contains 681 bp open reading frame encoding 226 amino acid residues. Amino acid sequences analysis and structure prediction display approximately 50% identity to higher vertebrates with the presence of conserved structures, including the four transmembrane domains and certain characteristic residues. Southern blot analysis shows that daCD9 exists as a single copy gene. Northern blot analysis reveals that daCD9 is highly expressed in gill and spleen although its expression can be found in other tissues suggesting daCD9 might play an important role in immune defense in this fish.Molecular Immunology 05/2006; 43(10):1534-40. · 2.90 Impact Factor -
Article: An ancient balanced polymorphism in a regulatory region of human major histocompatibility complex is retained in Chinese minorities but lost worldwide.
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ABSTRACT: The coding regions of many of the major histocompatibility complex (MHC) (human leukocyte antigen [HLA] in humans) molecules are believed to be subject to balancing selection. But it is less certain whether the regulatory regions of such coding sequences are also subject to the same type of selection. Here, we studied the polymorphism of the regulatory regions of the HLA-DPA1 and HLA-DPB1 genes among ethnic minorities in southwestern China. Phylogenetic analysis revealed two deep clades >10 million years old. There is almost complete linkage disequilibrium between the regulatory and coding regions of HLA-DPA1, which hints at coadaptive balancing selection on the entire region. Thus, the molecular mechanism of balancing selection in MHC may involve expression modulation in addition to coding-region polymorphisms. Although the frequency of clade II is >30% in some ethnic minorities, it decreases to <5% among southern Han Chinese and vanishes among Europeans. As suspected, some ancient balanced polymorphisms, lost in major populations, still exist in isolated ethnicities. These isolated populations may thus contribute disproportionately to the total diversity of modern humans.The American Journal of Human Genetics 04/2006; 78(3):393-400. · 10.60 Impact Factor -
Article: Analysis of expressed sequence tags from the venom ducts of Conus striatus: focusing on the expression profile of conotoxins.
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ABSTRACT: Cone snails (genus Conus) are predatory marine gastropods that use venom peptides for interacting with prey, predators and competitors. A majority of these peptides, generally known as conotoxins demonstrate striking selectivity in targeting specific subtypes of ion channels and neurotransmitter receptors. So they are not only useful tools in neuroscience to characterize receptors and receptor subtypes, but offer great potential in new drug research and development as well. Here, a cDNA library from the venom ducts of a fish-hunting cone snail species, Conus striatus is described for the generation of expressed sequence tags (ESTs). A total of 429 ESTs were grouped into 137 clusters or singletons. Among these sequences, 221 were toxin sequences, accounting for 52.1% (corresponding to 19 clusters) of all transcripts. A-superfamily (132 ESTs) and O-superfamily conotoxins (80 ESTs) constitute the predominant toxin components. Some non-disulfide-rich Conus peptides were also found. The expression profile of conotoxins also explained to some extent the pharmacological and physiological reactions elicited by this typical piscivorous species. For the first time, a nonstop transcript of conotoxin was identified, which is suggestive that alternative polyadenylation may be a means of post-transcriptional regulation of conotoxin production. A comparison analysis of these conotoxins reveals the different variation and divergence patterns in these two superfamilies. Our investigations indicate that focal hyper-mutation, block substitution and exon shuffling are three main mechanisms leading to the conotoxin diversity in a species. The comprehensive set of Conus gene sequences allowed the identification of the representative classes of conotoxins and related components, which may lay the foundation for further research and development of conotoxins.Biochimie 03/2006; 88(2):131-40. · 3.02 Impact Factor -
Article: The phylogenetic analysis of tetraspanins projects the evolution of cell-cell interactions from unicellular to multicellular organisms.
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ABSTRACT: In animals, the tetraspanins are a large superfamily of membrane proteins that play important roles in organizing various cell-cell and matrix-cell interactions and signal pathways based on such interactions. However, their origin and evolution largely remain elusive and most of the family's members are functionally unknown or less known due to difficulties of study, such as functional redundancy. In this study, we rebuilt the family's phylogeny with sequences retrieved from online databases and our cDNA library of amphioxus. We reveal that, in addition to in metazoans, various tetraspanins are extensively expressed in protozoan amoebae, fungi, and plants. We also discuss the structural evolution of tetraspanin's major extracellular domain and the relation between tetraspanin's duplication and functional redundancy. Finally, we elucidate the coevolution of tetraspanins and eukaryotes and suggest that tetraspanins play important roles in the unicell-to-multicell transition. In short, the study of tetraspanin in a phylogenetic context helps us understand the evolution of intercellular interactions.Genomics 01/2006; 86(6):674-84. · 3.02 Impact Factor -
Article: Identification and characterisation of a homolog of an activation gene for the recombination activating gene 1 (RAG 1) in amphioxus.
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ABSTRACT: Expression of recombination activating genes (RAG) involved in the V (D) J recombination is regulated by the RAG1 gene activator (RGA) in mammals. The sequence of a cDNA clone from an amphioxus cDNA library was found to be homologous to that of RGA from mouse stromal cells with 45% identity. The full-length cDNA sequence comprises 1119 bp and encodes a putative protein of 210 amino acid residues. Characterisation of the amino acid sequence revealed that two MtN3 domains and seven transmembrane spans are present in this protein, indicating a potential role as a plasma membrane protein. This gene is expressed in many tissues and at differential developmental stages. A high expression level of RGA is detected in gonad tissues, and gastrula embryo and adult stages. The presence of the RGA gene in amphioxus suggests that the signal pathway required for the expression of RAG could exist in this primitive protochordate. It also implies that in the related molecules, primitive adaptive immunity may have existed in cephalochordate although the complete machinery of VDJ rearrangement may not be formed.Fish & Shellfish Immunology 09/2005; 19(2):165-74. · 3.32 Impact Factor -
Article: Genes "waiting" for recruitment by the adaptive immune system: the insights from amphioxus.
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ABSTRACT: In seeking evidence of the existence of adaptive immune system (AIS) in ancient chordate, cDNA clones of six libraries from a protochordate, the Chinese amphioxus, were sequenced. Although the key molecules such as TCR, MHC, Ig, and RAG in AIS have not been identified from our database, we demonstrated in this study the extensive molecular evidence for the presence of genes homologous to many genes that are involved in AIS directly or indirectly, including some of which may represent the putative precursors of vertebrate AIS-related genes. The comparative analyses of these genes in different model organisms revealed the different fates of these genes during evolution. Their gene expression pattern suggested that the primitive digestive system is the pivotal place of the origin and evolution of the AIS. Our studies support the general statement that AIS appears after the jawless/jawed vertebrate split. However our study further reveals the fact that AIS is in its twilight in amphioxus and the evolution of the molecules in amphioxus are waiting for recruitment by the emergence of AIS.The Journal of Immunology 04/2005; 174(6):3493-500. · 5.79 Impact Factor -
Article: Secretion, purification, and characterization of a recombinant Aspergillus oryzae tannase in Pichia pastoris.
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ABSTRACT: Tannase (tannin acyl hydrolase) is an industrially important enzyme produced by a large number of fungi, which hydrolyzes the ester and depside bonds of gallotannins and gallic acid esters. In the present work, a tannase from Aspergillus oryzae has been cloned and expressed in Pichia pastoris. The catalytic activity of the recombinant enzyme was assayed. A secretory form of enzyme was made with the aid of Saccharomyces cerevisiae alpha-factor, and a simple procedure purification protocol yielded tannase in pure form. The productivity of secreted tannase achieved 7000 IU/L by fed-batch culture. Recombinant tannase had a molecular mass of 90 kDa, which consisted of two kinds of subunits linked by a disulfide bond(s). Our study is the first report on the heterologous expression of tannase suggesting that the P. pastoris system represents an attractive means of generating large quantities of tannase for both research and industrial purpose.Protein Expression and Purification 09/2004; 36(2):165-9. · 1.59 Impact Factor -
Article: Macrophage migration inhibitory factor (MIF) in chinese amphioxus as a molecular marker of immune evolution during the transition of invertebrate/vertebrate.
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ABSTRACT: Macrophage migration inhibitory factor (MIF) is an important cytokine related to host defenses and autoimmune diseases. Here, we reported two full-length cDNA clones isolated from Chinese amphioxus (Branchiostoma belcheri tsingtaunese). Amino acid sequences analysis and structure prediction of these two molecules, called Bbt-MIF-I and Bbt-MIF-II, respectively, indicated that several conservative domains existed in the two amphioxus MIFs and their sequences were highly homologous to their counterparts of other species. Intriguingly, the Bbt-MIFs gene is present in multi-copy per haploid genome, which is very unusual compared with vertebrate's MIF gene given the known genome duplication theory. The genomic copy number, expression pattern of MIF gene and phylogenetic analysis of MIF proteins all suggested that a leap forward happened for MIF gene during the evolution from invertebrate to vertebrate. Considering the crucial role of MIF in innate immunity, MIF might serve as one of key molecular markers of evolution of immune system.Developmental & Comparative Immunology 09/2004; 28(10):961-71. · 3.27 Impact Factor -
Article: Functional expression and characterization of four novel neurotoxins from sea anemone Anthopleura sp.
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ABSTRACT: The genes of four novel neurotoxins, named Hk2a, Hk7a, Hk8a, and Hk16a, were obtained from sea anemone Anthopleura sp. All four neurotoxins were composed of 47 amino acid residues and the variable residues among them were found in positions 14, 22, 25, and 37. To study their activities, the four toxins fused to the Escherichia coli thioredoxin were overexpressed by BL21 (DE3), cleaved off from the fusion partner, purified, and characterized with MALDI-TOF and CD assays. Contractile force studies of isolated SD atria indicated that rHk2a had the strongest and rHk7a the longest heart stimulation effect. Consequently, the Arg14, a highly conserved residue in various sea anemone neurotoxins, can be inferred to contribute to the duration but not the intensity of contraction-stimulating activity. Our work renders useful information to studies of sea anemone neurotoxins, especially to the clarification of the function of the disputative Arg14.Biochemical and Biophysical Research Communications 02/2004; 313(1):163-70. · 2.48 Impact Factor
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Institutions
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2003–2011
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Sun Yat-Sen University
- • Department of Biochemistry
- • State Key Laboratory of Biocontrol
Guangzhou, Guangdong Sheng, China
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