鳜鱼Mx蛋白全长cDNA的克隆和序列分析

Mx蛋白是一类由I型干扰素诱导表达的抗病毒蛋白。本研究以感染了鳜传染性脾肾坏死病毒(Infectious spleen and kidney necrosis virus,ISKNV)的鳜鱼为材料,提取肝脏总RNA,通过逆转录一聚合酶链式反应(RT-PCR)扩增出Mx蛋白基因的核心片段序列,再应用3’和5’快速扩增cDNA末端(RACE)方法PCR扩增Mx蛋白cDNA末端,最终获得鳜鱼Mx蛋白cDNA序列(GenBank登陆号：AY392097)。序列分析表明：鳜鱼Mx蛋白cDNA含有2391bp,其中编码区长1881bp,编码627个氨基酸残基,推测蛋白质分子量大小为7．15kDa。鳜鱼Mx蛋白具有脊椎动物Mx蛋白共有的结构特征：一个三联体GTP结合区域(GXXXSGKS/T、DXXG、T／NKXD)一个发动蛋白家族的典型结构特征序列(LPRGS／KGIVTR);以及C端高度保守的Leu拉链结构域。鳜鱼Mx蛋白全基因的获得为下一步研究鱼类Mx蛋白的抗病毒活性、作用机制,以及干扰素的检测奠定了基础。     

云南五个不同地区烟草花叶病毒外壳蛋白基因的序列比较

Five Tobacco mosaic virus isolates, obtained from tobacco leaves showing typical symptom in Qujing, Honghe, Dali, Chuxiong and Yuxi in Yunnan province, were selected and studied from 637 TMV samples. Using a pair of primers specific for TMV-U1 strain, a specific fragment of 530bp including the TMV coat protein gene was amplified using IC-PCR. The products of PCR were cloned and sequenced. The nucleotide and amino acid sequences of the coat protein of the five isolates were found to be very similar each other and have more than 90% sequence identity with TMV-U1, TMV-B,TMV-P, TMV-FUJIAN, although minor differences existed among them. The results showed that the five isolates from Yunnan province belong toTMV-U1 strain.     

Structure and Evolution of the Mitochondrial Control Region of Leaf Beetles (Coleoptera: Chrysomelidae): A Hierarchical Analysis of Nucleotide Sequence Variation

Abstract To assess the levels of variation at different evolutionary scales in the mitochondrial (mt) control region of leaf beetles, we sequenced and compared the full mt control region in two genera (Chrysomela and Gonioctena), in two species within a genus (Gonioctena olivacea and G. pallida), in individuals from distant populations of these species in Europe, and in individuals from populations separated by moderate (10- to 100-km) to short (<5-km) distances. In all individuals, a highly repetitive section consisting of the tandem repetition of 12 to 17 imperfect copies of a 107- to 159-bp-long core sequence was observed. This repetitive fragment accounts for roughly 50% of the full control-region length. The sequence variability among repeated elements within the control region of a given individual depends on the species considered: the variability within any G. olivacea individual is much higher than that within G. pallida individuals. Comparisons of the repeated elements, in a phylogenetic framework, within and among individuals of G. olivacea and G. pallida suggests that the repetitive section of the control region experienced recurrent duplications/deletions, leading to some degree of concerted evolution. Comparisons between Chrysomela and Gonioctena control regions revealed virtually no significant sequence similarity, except for two long stretches of A's and several [T(T)A(A)] repeats, all found in the control region of other insect orders. Our analyses allowed us to identify portions of the control region with enough variation for population genetic or phylogeographic studies.     

The adenylate cyclase catalytic domain of Streptomyces coelicolor is carboxy-terminal

Abstract A DNA fragment of Streptomyces coelicolor encoding the carboxy-terminal catalytic domain of adenylate cyclase was cloned, sequenced and expressed in an Escherichia coli cya -defective strain where it produced nanomole levels of cAMP. The amino acid sequence of the enzyme displays similarities with the Brevibacterium liquefaciens pyruvate regulated adenylate cyclase.     

Sequence Variation in the Gpl20 region of SHIV-CN97001 during in vivo Passage

SHIV-CN97001 played an important role in assessing the immune effect and strategy of the AIDS vaccine which included genes of the predominant prevalent HIV-1 strain in China. In this study, SHIV-CN97001 was in vivo passaged serially to construct pathogenic SHIV-CN97001/rhesus macaques model. To identify variation in the gp120 region of SHIV-CN97001 during passage, the fragments of gp120 gene were amplified by RT-PCR from the plasma of SHIV-CN97001 infected animals at the peak viral load time point and the gene distances （divergence, diversity） were calculated using DISTANCE. The analysis revealed that the genetic distances of SHIV-CN97001 in the third passage animals were the highest during in vivo passage. It had a relationship between viral divergence from the founder strain and viral replication ability. The nucleic acid sequence of the V3 region was highly conservative. All of the SHIV-CN97001 strains had V3 loop central motif （GPGQ） and were predicted to be using CCR5 co-receptor on the basis of the critical amino acids within V3 loop. These results show that there was no significant increase in the genetic distance during serial passage, and SHIV-CN97001 gp120 gene evolved toward ancestral states upon transmission to a new host. This could partly explain why there was no pathogenic viral strain obtained during in vivo passage.     

Purification and Chemical Characterization of Peptide G1, an Invertebrate Neuropeptide That Stimulates Cyclic GMP Metabolism

Bioassay analysis of extracts of the major neurosecretory structures of the American lobster have revealed several different agents with stimulatory effects on the cyclic GMP metabolism of various lobster tissues. The most potent of these is a peptide extracted from the sinus gland, a neurohemal organ found in the animal's eyestalk. This molecule, called peptide G1 (for its effects on cyclic GMP metabolism), can increase the cyclic GMP content of every lobster tissue tested, sometimes by as much as 200-fold. In this article, we describe the purification and some of the chemical properties of peptide G1. Purification was accomplished by sequential anion exchange and reverse-phase HPLC. The purified peptide is a large, extremely hydrophobic molecule. Its apparent molecular mass on a reducing sodium dodecyl sulfate-containing gel is 6.4 kDa, and its calculated molecular mass (based on an amino acid analysis of the purified material) is 8.2 kDa. Amino acid analysis reveals a high proportion of leucine and valine residues. The amino terminus of the molecule is not susceptible to Edman degradation, but sequencing studies were successfully carried out on tryptic fragments. Based on the estimated size of the molecule, these studies provide approximately 60% of the total sequence. No homologies with any previously sequenced peptide were observed, but biochemical similarities to as yet unsequenced peptides found in extracts of sinus glands from other crustaceans (hyperglycemic hormone and moult-inhibiting hormone) are described.     

DNA polymorphism in the conserved 190 kDa antigen gene repeat region among spotted fever group Rickettsiae

The 190 kDa protein gene of R. rickettsii (R strain) contains region of tandemly arranged repeats. Homologous sequences were discovered within the genomes of all but one species of spotted fever group Rickettsiae. Southern blots showed restriction fragment lenght polymorphisms between species of Rickettsiae indicating structural differences among repeat regions. Further analysis using polymorase chain reaction techniques indicated the repeat regions vary in size among Rickettsiae. In addition, strains of R. rickettsii that vary in virulence were found to contain polymorphisms in this region.     

Relationships among amino acid sequences of animal,microbial and plant peroxidases

Summary Relationships among 18 peroxidases amino acid sequences of animal, microbial and plant origin were examined using optimum alignment of all pairwise sequence combinations to generate a total distance matrix. The matrix was used to cluster the sequences with complete linkage (farthest neighbour) procedures. Specific distances were calculated from the total distances matrix. The patterns of specific distances for each sequence were compared to evaluate the relationships between sequences, check their significance and construct subgroups of related sequences. The results were compared with those from clustering and its resultant dendrogram; good agreement was achieved. The 18 sequences fell into two principal groups, plant peroxidases and animal/microbial peroxidases. Within the plant peroxidases four subgroups were detected; the animal/microbial peroxidases formed a fifth subgroup. Profiles were constructed for the subgroups from lists of matching amino acids generated by the alignment calculations. Superimposed lists were realigned to recognise conserved areas and elements. Individual subgroup profiles for the plant peroxidases were then combined into a single profile which in turn was combined with profiles from the animal/microbial peroxidases. The final profile suggested that numerous sequence features (motifs) were common to peroxidases of widely different function and origins.     

Natural Killer Cell Immunoglobulin-like Receptor (KIR) genotypes in Follicular Lymphoma patients: Results of a pilot study

Aims

The Natural Killer Cell Immunoglobulin-like Receptor (KIR) genotype profiling in Follicular Lymphoma has not been reported before in the literature.

Materials and methods

DNA extracted from 20 Follicular Lymphoma patients and 62 healthy controls was analyzed for KIR genotyping using a polymerase chain reaction/sequence specific primers technique (PCR/SSP) for the presence of 16 KIR gene and pseudogene loci.

Results

The AA, AB, and BB genotype frequencies were, respectively, 20%, 60% and 20% with an A:B ratio of 1:1. KIR 2DL4, KIR 3DL2, KIR 3DL3, and KIR 3DP1*003 were presented in all individuals. No significant difference between patients and controls was detected.

Conclusion

KIR genotyping profile does not seem to be associated with Follicular Lymphoma. The results presented in this pilot research represent the first international report about this important clinical entity.