Identification of the Rice Vacuolar ATPase B Subunit Gene and Its Expression Pattern Analysis Under Phosphorus Deficiency

A vacuolar ATPase (V-ATPase.) B subunit gene has been cloned and characterized front a phosphorus starvation induced rice root subtractive cDNA library by suppression subtractive hybridization (SSH) method and RT-PCR amplification. This gene encodes a polypeptide of 487 amino acid residues, containing a conservative ATP binding site and with a molecular weight of 54.06 kD and an isoelectric point of 4.99, southern analysis of the. genomic DNA indicates that V-ATPase B subunit is encoded by a single gene in rice genome. The amino acid homologies of V-ATPase B subunits among different organisms range from 76% to 97% and reveals that the evolution of V-ATPase B subunit is accompanied with the biological evolution. Expression pattern analysis indicated that the maximal expression of V-ATPase B subunit gene occurred at an early stage (6 - 12 h) after phosphorus starvation in roots, and lately stage (24 - 48 It) in leaves. Under phosphorus deficiency, the up-regulated expression of V-ATPase gene was presumed to strengthen the proton transport and provide the required energy to maintain an electrochemical gradient across the tonoplast to facilitate Phosphorus transport.

Serotonin type 3 receptor subunit gene polymorphisms associated with psychosomatic symptoms in irritable bowel syndrome:A multicenter retrospective study

BACKGROUND Single-nucleotide polymorphisms(SNPs)of the serotonin type 3 receptor subunit(HTR3)genes have been associated with psychosomatic symptoms,but it is not clear whether these associations exist in irritable bowel syndrome(IBS).AIM To assess the association of HTR3 polymorphisms with depressive,anxiety,and somatization symptoms in individuals with IBS.METHODS In this retrospective study,623 participants with IBS were recruited from five specialty centers in Germany,Sweden,the United States,the United Kingdom,and Ireland.Depressive,anxiety,and somatization symptoms and sociodemographic characteristics were collected.Four functional SNPs—HTR3A c.-42C>T,HTR3B c.386A>C,HTR3C c.489C>A,and HTR3E c.*76G>A—were genotyped and analyzed using the dominant and recessive models.We also performed separate analyses for sex and IBS subtypes.SNP scores were calculated as the number of minor alleles of the SNPs above.The impact of HTR3C c.489C>A was tested by radioligand-binding and calcium influx assays.RESULTS Depressive and anxiety symptoms significantly worsened with increasing numbers of minor HTR3C c.489C>A alleles in the dominant model(F_(depressive)=7.475,P_(depressive)=0.006;F_(anxiety)=6.535,P_(anxiety)=0.011).A higher SNP score(range 0-6)was linked to a worsened depressive symptoms score(F=7.710,P-linear trend=0.006)in IBS.The potential relevance of the HTR3C SNP was corroborated,showing changes in the expression level of 5-HT3AC variant receptors.CONCLUSION We have provided the first evidence that HTR3C c.489C>A is involved in depressive and anxiety symptoms in individuals with IBS.The SNP score indicated that an increasing number of minor alleles is linked to the worsening of depressive symptoms in IBS.

A novel mutation in the sodium channel α1 subunit gene in a child with Dravet syndrome in Turkey

Dravet syndrome is a rare epileptic encephalopathy characterized by frequent seizures beginning in the first year of life and behavioral disorders. Mutations in the sodium channel α1 subunit gene are the main cause of this disease. We report two patients with refractory seizures and psychomotor retardation in whom the final diagnosis was Dravet syndrome with confirmed mutations in the sodium channel α1 subunit gene. The mutation identified in the second patient was a novel frame shift mutation, which resulted from the deletion of five nucleotides in exon 24.

Association between G-protein β3 subunit gene and isolated systolic blood pressure elevation of greater than 130 mmHg: A large-scale cross-sectional study in the Japanese population

AIM To investigate whether GNB3 C825 T single nucleotide polymorphism(SNP) contributes to systolic blood pressure(SBP) ≥ 130 mmH g in a large-scale cross-sectional study among the Japanese population with diastolic blood pressure(DBP) < 85 mmH g. METHODS We analyzed 11008 Japanese subjects, including 2797 cases(SBP ≥ 130 and DBP < 85 mmH g) who were not taking anti-hypertensive medication and 8211 controls(SBP < 130 and DBP < 85 mmH g), all of whom enrolled in the genome banking project of the 21 st Century COE(Center of Excellence) Program at Jichi Medical University. Subjects were divided into four groups according to gender(male and female) and age(≤ 49 years and ≥ 50 years). GNB3 gene polymorphism was determined using the TaqM an probe method. We compared the frequencies of alleles and genotypes between cases and controls by chi-squared test. The strength of the associations was estimated by odds ratios(ORs) and 95%CI by using logistic regression analysis. The ORs were adjusted for age and body mass index. RESULTS Allele and genotype distributions significantly differed between cases and controls only in males aged ≤ 49 years. Compared to the CC genotype, a significant OR was obtained in the TT genotype among males aged ≤ 49 years.CONCLUSION This study indicates that the TT genotype of the GNB3 C825 T SNP may contribute to SBP elevation of greater than 130 mmH g compared to the CC genotype in Japanese males aged ≤ 49 years.

Telomerase activity and expression of the telomerase catalytic subunit gene in non small cell lung cancer: correlation with decreased apoptosis and clinical prognosis

To investigate the level of telomerase activation (TA) and telomerase catalytic subunit (hEST 2) gene mRNA in patients with non small cell lung cancer, and determine whether they are associated with tumor cell apoptosis, stage, and clinical outcome Methods Primary tumor specimens from 58 patients untreated with chemotherapy and 10 cases of histologically benign and adjacent lung tissue were analyzed TA and hEST 2 were measured by means of a modified telomerase repeat amplification protocol (TRAP) assay and in situ hybridization (ISH), respectively Terminal deoxynucleotidyl transferase (TdT) mediated biotin dUTP nick end labeling (TUNEL) was used to evaluate apoptotic cells Reverse transcription polymerase chain reaction (RT PCR) was used to detect bcl 2 mRNA expression Results TA and hEST 2 were detected in 45 (77 6%) and 43 (74 1%) of 58 tumor specimens, respectively, and not detected in specimens of adjacent and benign lung tissue One case expressed hEST 2 as a weak positive Statistically significant positive association was found between the level of TA and hEST 2( r =0 85, P =0 001) TA and hEST 2 were associated with tumor stage, but not associated with tumor grade, gender and patient age Positive rate of bcl 2 mRNA was 38 (65 5%) of 58 tumor specimens The mean apoptotic index in the bcl 2 positive group (9 5±1 3) was lower than that in the bcl 2 negative one (19 8±2 1, P <0.05), suggesting that apoptotic index may be inversely associated with bcl 2 expression ( r =-0 48, P =0 041) Bcl 2 expression in the TA and hEST 2 positive group (92 1% and 89 4%) was higher than that in the negative one (50 0% and 45 0%, P =0 043 and P =0 032, respectively) The apoptotic index was lower in the TA or hEST 2 positive group (8 2±1 4, 10 7±1 1) than in the negative one (20 5±1 6, 24 2±2 1, P <0 05) A statistically significant inverse association was found between TA or hEST 2 and apoptotic index ( r =-0 45, P =0 02 and r = -0 51, P =0 001, respectively) Positive correlation was also detected between TA or hEST 2 and bcl 2 expression ( r =0 86, P =0 01 and r =0 73, P =0 024, respectively) The level of hEST 2 mRNA and apoptotic index were associated with clinical outcome in a multivariate cox regression analysis Conclusions High TA and hEST 2 were frequently detected in primary non small cell lung cancer untreated with chemotherapy, having high bcl 2 expression and a low tumor cell apoptotic rate This suggests that both TA and hEST 2 are correlated with the deregulation of apoptosis hEST 2 and apoptotic index have prognostic significance in patients with non small cell lung cancer

Cloning and Overexpressing Apo-phycoerythrocyanin α-subunit Gene of Mastigocladus laminosus in E.coli

By PCR method, apo phycoerythrocyanin α subunit gene (pecA) of Mastigocladus laminosus (M. laminosus) was amplified from its genomic DNA, and then cloned in pBluescript. The pecA gene was subcloned into the expression vector pGEMD, and then transformed into E.coli BL21 (DE3). After induction, a new protein of molecular weight 19×10 3 existing in inclusion body was overexpressed. The expressed product was confirmed to be apo phycoerythrocyanin α subunit by Dot ELISA.

FSHβsubunit gene is associated with major gene controlling litter size in commercial pig breeds

An insertion fragment in porcine FSHβ subunit gene was cloned by PCR. Sequencing data show that the insertion is a retroposon of 292 bp siting in intronⅠ at the site between +809 and +810 base. Based on these results, a PCR programme was created to genotype animal individuals in different pig breeds at FSHβ locus and polymorphism of FSHβ gene was analyzed. With the combination of genotype and litter size of sows, it was demonstrated that FSHβ locus is closely associated with major gene controlling litter size in commercial pig breeds, such as Yorkshire, Landrace, Durco. Averagely the AA sows give more 1.5 piglets than BB sows do per litter.

Gene Cloning and Expression Analysis of G Protein αq Subunit from Helicoverpa assulta (Guenée)

The cDNA encoding the G protein αq subunit was isolated from the antennae of Helicoverpa assulta （Guen6e） by reverse transcription polymerase chain reaction （RT-PCR） and named as HassGαq. Sequencing analysis showed that the fulllength of HassGαq open reading frame （ORF） is 1 062 bp, 353 amino acid residues are encoded. The predicted molecular weights （MW） and isoelectric point （PI） are 41.5 kD and 5.15, respectively. HassGαq gene was then constructed into expression vector pGEX-4T-2 for over expression in prokaryotic cells. The SDS-PAGE and Western blot analysis showed that induced by Isopropyl-β-D-Thiogalactoside （IPTG）, the GST-HassGαq fusion protein is expressed in Escherichia coil BL21, and its MW was found to be about 66 kD nearly equal to the predicted. In addition, RT-PCR analysis showed that the expressions of HassGαq are not tissue specific.

Cloning and Characterization of a Tau Glutathione S-transferase Subunit Encoding Gene in Gossypium hirsutum

A predicted tau glutathione S-transferase(GST) subunit encoding gene,named GhGST,was isolated from Gossypium hirsutum with RACE method from SSH library based on Verticillium

A Novel Approach to Functional Analysis of the Ribulose Bisphosphate Carboxylase Small Subunit Gene by Agrobacterium-Mediated Gene Silencing

A novel approach to virus-induced post-transcriptional gene silencing for studying the function of the ribulose bisphosphate carboxylase small subunit （rbcS） gene was established and optimized using potato virus X vector and Nicotiana benthamiana as experimental material. The analysis of silencing phenomena, transcriptional level, protein expression, and pigment measurement showed that the expression of the rbcS endogenous gene was inactivated by the expression of a 500-bp homologous cDNA fragment carried in the virus vector.

Cloning of the Gene Encoding Urease Subunit A in Helicobacter Pylori

The gene encoding urease subunit A (ureA) of Helicobacter pylori (H.pylori) was cloned from H.pylori isolate by polymerase chain reaction (PCR). Sterile distilled water instead of DNA served as negative control. The nucleotide sequence of the amplified product was determined. Homologous analysis of the ureA against that reported by Clayton CL and the GenBank and SwissProt databases were performed with the BLAST program at the Genome Net through the Internet. 0.8 kb PCR product was amplified from all H.pylori clinical isolators. The nucleotide sequence of the ureA was determined. The nucleotide sequence of the ureA began with ATG as the initiation codon and terminated in TAA as stop codon. The coding regions had a 44 % G+C content. The DNA sequence was 98 % homologous to that reported by Clayton CL (688 out of 702 residues were identical). The derived amino acid sequences of the ureA were 99 % homologous to that reported by Clayton CL (232 out of 234 residues were identical). The nucleotide sequence and the predicted protein showed significant homology to ureA of H.pylori in the NCBI Entrez database.

Submicroscopic 11p13 deletion including the elongator acetyltransferase complex subunit 4 gene in a girl with language failure, intellectual disability and congenital malformations: A case report

BACKGROUND We described the main features of an infant diagnosed with facial dysmorphic,language failure,intellectual disability and congenital malformations to strengthen our understanding of the disease.Currently,treatment is only rehabilitation and surgery for cleft lip and palate.CASE SUMMARY The proband was a 2-years-8-months-old girl.Familial history was negative for congenital malformations or intellectual disability.The patient had microcephaly,upward-slanting palpebral fissures,depressed nasal bridge,bulbous nose and bilateral cleft lip and palate.Brain magnetic resonance imaging showed cortical atrophy and band heterotopia.Her motor and intellectual development is delayed.A submicroscopic deletion in 11p13 involving the elongator acetyltransferase complex subunit 4 gene(ELP4)and a loss of heterozygosity in Xq25-q26.3 were detected.CONCLUSION There is no treatment for the ELP4 deletion caused by a submicroscopic 11p3 deletion.We describe a second case of deletion of the ELP4 gene without aniridia,which confirms the association between ELP4 gene with several defects and absence of this ocular defect.Additional clinical data in the deletion of the ELP4 gene as cleft palate,facial dysmorphism,and changes at level brain could be associated to this gene or be part of the effect of the recessives genes involved in the loss of heterozygosity region of Xq25-26.3.

Controlling N-methyl-D-aspartate receptor subunit 1 with calcitonin gene related peptide after cerebral ischemic injury

BACKGROUND: Activation of N-methyl-D-aspartate receptor (NMDAR) is a key link of exitotoxicity at the phase of cerebral ischemic injury. Because NMDAR is a main way to mediate internal flow of Ca2+ among glutamic acid receptors, over-excitation can cause neuronal apoptosis. Calcitonin gene related peptide has a strongly biological activity. On one hand, it can protect ischemic neurons through inhibiting the expression of NMDAR1 mRNA; on the other hand, it can play the protective effect through down-regulating the expression of NMDAR1 mRNA by exogenous calcitonin gene related peptide. OBJECTIVE: To observe the expression of NMDAR1 and the regulatory effect of calcitonin gene related peptide on the expression of NMDAR1 mRNA and protein in the cerebral cortex of rats with focal cerebral ischemia/reperfusion (I/R). DESIGN: Randomized controlled animal study. SETTING: China Medical University. MATERIALS: A total of 216 healthy male Wistar rats, general grade, weighing 250-280 g, were selected in this study. Twelve rats were randomly selected to regard as control group; meanwhile, other 204 rats were used to establish middle cerebral artery occlusion/reperfusion (MACO) models. The main reagents were detailed as follows: calcitonin gene related peptide (Sigma Company); calcitonin gene related peptide kit (Boster Company); antibody Ⅰ, Ⅱ and antibody β-actin Ⅰ, Ⅱ of NMDAR1 mRNA and chemiluminescence reagent (Santa Cruz Company, USA). METHODS: The experiment was carried out in the Laboratory of Neurobiology of China Medical University from August 2005 to June 2006. ① Right MCAO models of rats were established to cause focal ischemia and scored based on Zea Longa five-grade scale. If the scores were 1, 2 and 3 after wakefulness, the MACO models were established successfully and involved in the experiment. A total of 120 rats with successful modeling were randomly divided into I/R group and administration group with 60 in each group. All rats in the both groups were observed at five time points, including 6, 12, 24, 48 and 72 hours after reperfusion and after 2-hour ischemia, with 12 experimental animals at each time point. Six rats were prepared for detection of hybridization in situ, and the other 6 were used for Western blotting histochemical detection. Rats in the control group were opened their skin to separate common carotid artery and not treated with line and drugs. In addition, rats in the I/R group were treated with 1 mL saline at 2 hours after focal cerebral ischemia, and then, rats in the administration group were treated with 1 mL (1 g/L) calcitonin gene related peptide at 2 hours after focal cerebral ischemia. ② The expression of NMDAR1 mRNA was detected with hybridization in situ at various time points; moreover, the expression of NMDAR1 protein was measured with Western blotting method at various time points. The results were analyzed with Metamoph imaging analytical system. MAIN OUTCOME MEASURES: The expression of NMDAR1 mRNA and its protein in cortical neurons of rats at various time points. RESULTS: A total of 84 rats were excluded because of non-symptoms, exanimation or death; and then, 132 rats were involved in the final analysis. The expression of NMDAR1 mRNA and its protein in cortical neurons of rats in the control group was 0.205±0.001 and 0.184±0.001, respectively; after I/R, expression of NMDAR1 mRNA and its protein was up-regulated, especially, expression of mRNA at 6, 12, 24, 48 and 72 hours was 0.245±0.003, 0.287±0.004, 0.354±0.008, 0.284±0.002 and 0.217±0.006, respectively; moreover, expression of protein at 6, 12, 24, 48 and 72 hours was 0.222±0.003, 0.261±0.028, 0.311±0.004, 0.259±0.013 and 0.210±0.008, respectively. There was significant difference between the two groups (0.205±0.001, P < 0.01). The expression was up-related in the former 24 hours, reached peak at 24 hours, down-regulated, and decreased to the level of control group at 72 hours. Except 72 hours, the expression of NMDAR1 mRNA and its protein was lower in administration group than that in I/R group at other four time points. In addition, the expression of mRNA at 6, 12, 24, 48 and 72 hours was 0.223±0.005, 0.243±0.001, 0.292±0.002, 0.250±0.003 and 0.213±0.003, respectively; moreover, the expression of protein at 6, 12, 24, 48 and 72 hours was 0.216±0.006, 0.245±0.025, 0.276±0.003, 0.241±0.045 and 0.202±0.013, respectively. There was significant difference at various time points (P < 0.05). CONCLUSION: The expressions of NMDAR1 mRNA and its protein of peripheral cortical neurons are up-related in ischemic area after focal cerebral I/R. Meanwhile, exogenous calcitonin gene related peptide can protect cortical neurons through inhibiting expression of NMDAR1 mRNA and its protein after focal cerebral I/R.

G-protein beta 3 subunit polymorphisms and essential hypertension： a case-control association study in northern Han Chinese

Objective To explore the association between the three polymorphisms [ C825T, C1429T and G（-350）A] of the gene encoding the G protein beta 3 subunit （GNB3） and hypertension by performing a case-control study in the northern Han Chinese population. Methods We recnaited 731 hypertensive patients and 673 control subjects （the calculated power value was 〉 0.8）. Genotyping was performed to identify C825T, C1429T and G（-350）A polymorphisms using the TaqMan assay. Comparisons of allelic and genotypic frequencies between cases and controls were made by using the chi-square test. Logistic regression analyses were performed to investigate the relationships between the three polymorphisms of GNB3 gene under different genetic models （additive, dominant and recessive models）. Results The genotype dis- tribution and allele frequencies of C825T, C1429T and G（-350）A polymorphisms did not differ significantly between hypertensive patients and control subjects, either when the full sample was assessed, or when the sample was stratified by gender. No significant association was observed between C825T, C 1429T and G（-350）A polymorphisms and the risk of essential hypertension in any genetic model. Linkage dis- equilibrium was only detected between C825T and C 1429T polymorphisms. Haplotype analyses observed that none of the three estimated haplotypes significantly increased the risk of hypertension. Conclusions Our study suggested that the GNB3 gene polymorphisms [C825T, C 1429T and G（-350）A] were not significantly associated with essential hypertension in northern Han Chinese population.

Gene cloning and prokaryotic expression of recombinant flagellin A from Vibrio parahaemolyticus

The Gram-negative Vibrio parahaemolyticus is a common pathogen in humans and marine animals. Bacteria flagellins play an important role during infection and induction of the host immune response. Thus, flagellin proteins are an ideal target for vaccines. We amplified the complete flagellin subunit gene （tTaA） from V. parahaemolyticus ATCC 17802. We then cloned and expressed the gene into Escherichia coli BL21 （DE3） cells. The gene coded for a protein that was 62.78 kDa. We purified and characterized the protein using Ni-NTA affinity chromatography and Anti-His antibody Western blotting, respectively. Our results provide a basis for further studies into the utility of the FlaA protein as a vaccine candidate against infection by Vibrio parahaemolyticus. In addition, the purified FlaA protein can he used for further functional and structural studies.

Genetic diversity and its seasonal variation of Jiaozhou Bay phytoplankton determined by rbcL gene sequencing

Ribulose-1, 5-bisphosphate carboxynase/oxygenase large subunit gene (rbcL) of Jiaozhou Bay phytoplankton was amplified from spring, summer and autumn surface seawater DNAs and cloned respectively. About 50 clones were randomly selected from each library and sequenced. If identical amino acid sequences are considered as the same operational taxonomy unit (OTU), 61 OTUs are identified according to inferred amino acid sequences, among them, 21 from spring seawater, 15 from summer seawater and 25 from autumn seawater. Shannon index calculated from OTU abundances reflects the genetic diversity of a community. The indexes of spring, summer and autumn surface seawater phytoplankton are 2.69, 2.44 and 2.76 respectively, indicating that phytoplankton genetic diversity of autumn seawater is the richest. Seasonal variation ofphytoplankton community is significant; the community compositions of three seasons are almost completely different except for the two OTUs shared by summer and autumn. Surface seawater phytoplankton communities are possibly metacommunities different spatially and temporally.

Contruction of the Genetic Engineering Strain Expressed Nontoxic ST_1-LT_B Fusion Protein Against Enterotoxigenic Eschenichia coli

Thermostable enterotoxinⅠ(ST1) mutant genes and thermolabile enterotoxin B subunit (LTB)genes were amplified by PCR from plasmids of Eschenichia coli C83902. The recombinantexpression plasmid pZST3LTB containing ST1-LTB fusion gene was constructed by recombinantDNA technique and then transformed into Escherichia coli BL21(DE3). The ST1-LTB fusionprotein was highly expressed in recombinant strain BL21(DE3)(pZST3LTB) and the fusionprotein was about 38.53% of total cellular protein by SDS-PAGE and thin-layer gelscanning analysis. More important, mice immunized with crude preparation containing thefusion protein inclusion bodies or inactivated recombinant strain produced antibodiesthat were able to recognize ST1 in vitro. These sera antibodies were able to neutralizethe biological activity of native ST1 in the suckling mouse assay. Hence the ST1-LTBfusion protein was nontoxic and immunogenic, the constructed recombinant strain BL21(DE3)(pZST3LTB) could be used as a candidate of vaccine strain.

Progress of CACNA1S Gene and Hypokalemic Periodic Paralysis

CACNA1 S gene is the gene encoding L-type calcium channel αa-subunit. CACNA1 S gene mutations can cause hypokalemic periodic pa- ralysis （HOKPP）. The related research speculated that CACNA1 S gene was the candidate genes which affect meat quality traits. In the present ar- ticle, the biological characteristics of CACNA1 S gene, structure, genetic diseases and the research development were respectively reviewed so as to provide a reference for further research.

Effects of p75 neurotrophin receptor knockout on axonal regeneration in a mouse model of facial nerve injury

BACKGROUND： Previous studies have shown that p75 neurotrophin receptor plays an important role in peripheral nerve injury. However, the role of p75 neurotrophin receptor in the regeneration of peripheral nerves remains poorly understood. OBJECTIVE： To study the effect of p75 neurotrophin receptor on facial nerve regeneration. DESIGN, TIME AND SETTING： A randomized controlled experiment was performed in the Regeneration Laboratory of Flinders University, Australia and the Biomedical Laboratory of Dentistry School, Shandong University from March 2005 to February 2006. MATERIALS： Cholera toxin B subunit, fast blue, and biotin rabbit-anti goat IgG were provided by Sigma, USA; goat-anti choleratoxin B subunit ant/body was provided by List Biologicals, USA. METHODS： In p75 neurotrophin receptor knockout and wild type 129/sv mice, the facial nerves on one side were crushed. At days 2 and 4 following injury, regenerating motor neurons in the facial nuclei were labeled by fast blue, and the regenerating axon was labeled by the anterograde tracer choleratoxin B subunit. MAIN OUTCOME MEASURES： Axonal regenerative velocity and number were detected by immunohistochemical staining of choleratoxin B subunit, growth-associated protein, protein gene product 9.5, and calcitonin-gene-related peptide; survival of motor neurons in the facial nuclei was detected by retrograde fast blue. RESULTS： Axonal growth in the facial nerve of p75 neurotrophin receptor knockout mice was significantly less than in wild type mice. At day 7 after injury, the number of regenerating motor neurons in p75 neurotrophin receptor knockout mice remained significantly less than in wild type mice （P 〈 0.05）. The number of positively stained fibers for growth-associated protein-43, protein gene product 9.5, and calcitonin-gene-related peptide in p75 neurotrophin receptor knockout mice was significantly less than in wild type mice （P 〈 0.01）. CONCLUSION： p75 neurotrophin receptor promoted axonal regeneration and enhanced the survival rate of motor neurons following facial nerve injury.

Genetic difference of Chinese horseshoe crab(Tachypleus tridentatus) in southeast coast of China based on mitochondrial COI gene analysis

Population genetic structure and historical demography of Chinese horseshoe crab (T.tridentatus)along southeast coast of China were inferred from the sequence data of mitochondrial cytochrome c oxidase subunit Ⅰ (COI) fragment.The sequence analysis for 964 bp COI fragment was conducted in 28 individuals collected from five localities:Ninghai in Zhejiang Province,Meizhou and Zhangpu in Fujian Province,Beihai of Guangxi Zhuang Autonomous Region and Danzhou of Hainan Province.Sequence variation was relatively low with a total of seven transitions observed.In all localities,Haplotype H3 was the dominant type observed among eight haplotypes defined previously,and was at the center of radiation in Median-Joining network.The prolonged star-like network suggests a signature of population expansions.The level of diversity was low in total,with haplotype diversity ( Hd) being equal to 0.765 and nucleotide diversity (π) being equal to 0.00118,respectively.The genetic structure analysis revealed the significant genetic difference between Ninghai and Danzhou populations.Both mismatch distribution analysis and Fu's Fs test provided consistent inference of historic population expansion.The low genetic diversity of horseshoe crab observed along China coast indicated that urgent measures should be taken to protect this rare marine animal.