Isolation, identification and analysis of the expression profile of miRNAs in Aedes albopictus / 南方医科大学学报

<p><b>OBJECTIVE</b>To verify the miRNA in Aedes albopictus and characterize the expression profile of several miRNAs across all the life stages of Aedes albopictus.</p><p><b>METHODS</b>Based on the published miRNA sequences of Anopheles gambiae and Aedes aegypti, 6 DIG-labeled antisense probes were synthesized. The total RNAs from Aedes albopictus in 6 developmental stages (embryo, early larvae, late larvae, pupa, male and female adults) were extracted with a mirVana miRNA isolation kit, loaded onto 15% denaturing polyacrylamide gel and hybridized with the appropriate DIG-labeled probes.</p><p><b>RESULTS</b>Northern blotting detected 5 miRNAs in Aedes albopictus, of which mir-9a was mainly expressed in embryo and larva stages, let-7 in pupa and adult stages, miR-184 in all life stages, mir-M1 only in the embryos and miR-1175 in all the life stages except for embryos. The expression profiles of these miRNAs in Aedes albopictus were similar to those in D. melanogaster and An.stepheni. miR-1174 was not detected in any of the developmental stages of Aedes albopictus.</p><p><b>CONCLUSION</b>These results present the first direct experimental evidence of miRNA in Aedes albopictus. The expression profiles of the analyzed miRNAs in Aedes albopictus showed stage specificity and conservation with other mosquitoes. Further studies on the functions of these miRNAs may offer new insights in mosquito biology and may lead to novel approaches to the development of insecticides.</p>

Antibacterial activity of recombinant thanatin expressed by E.coli ER2566 / 南方医科大学学报

<p><b>OBJECTIVE</b>To express antibacterial peptide thanatin in the prokaryotic expression system and test its antibacterial activity.</p><p><b>METHODS</b>The DNA sequence coding for the 21 peptides of thanatin was synthesized using the preferred genetic codes of E. coli, cloned into pTYB11 plasmid, and transformed into E.coli ER2566. The expression of thanatin fused with intein was induced by IPTG in E.coli, and intein-thanatin specifically bound to the column through intein tag was cleaved overnight at 4 degrees celsius; in DTT/cysteine buffer.</p><p><b>RESULTS</b>The cleaved thanatin was eluted with a protein concentration of 245 microg/ml in the first 4 ml. The purified thanatin had showed strong antibacterial activities against G- bacteria such as Shigella flexneri, Klebsiella pneumoniae, Shigella snnei, Escherichia coli O157, toxin producing Escherichia coli, Pseudomonas aeruginosa, and fungi such as Candida albicans, with especial potency in killing drug-resistant Klebsiella pneumoniae, Pseudomonas aeruginosa, and extended-spectrum beta-lactamases (ESBL)-producing E.coli. Eighty strains of drug-resistant (ESBL-producing) and 30 strains of sensitive E. coli were used for anti-bacterial assay, and no significant differences in the antibacterial activity of thanatin were found between the sensitive and drug-resistant E. coli (P>0.05).</p><p><b>CONCLUSION</b>The recombinant thanatin obtained shows strong antibacterial activity against drug-resistant and sensitive bacteria, and can be a potential substitute for routine antibiotics in the treatment of G- bacterial infections.</p>

Preliminary application of a mosquito densovirus-mediated artificial intron in vitro and in vive of mosquito / 病毒学报

An artificial intron consisting of the 5'-donor site (from the first intron of the human beta-globin gene) and the 3'-acceptor site (from the intron of an immunoglobulin gene heavy chain variable region) was obtained with a splice overlap extension PCR and was then inserted in frame into the coding sequence of nostructural protein NS1 gene fused to GFP gene in a recombinant mosquito densovirus plasmid p7NS1-GFP. The constructed plasmid was named as p7NS1-Intron-GFP. The plasmid p7NS1-Intron-GFP was co transfected with the helper plasmid pUCA into C6/36 cells, then the packaged recombinant and wild type viruses were purified and recovered. The second-instars of Aedes albopictus larvae were exposed to recombinant and wild type virus mixed stock. The high level GFP expression in C6/36 cells and larvae was observed under fluorescence microscope, indicating that the inserted artificial intron exerted its normal function in self-splicing both in vitro and in vivo. This study laid a foundation for application of an artificial intron in insect cells and development of new strategy for genetic engineering technology of mosqtuito and its pathogens.

Effect of cinobufagin on nuclear factor-kappaB pathway in HepG2 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of cinobufagin on nuclear factor-kappaB (NF-kappaB) pathway of liver cancer cell line HepG2.</p><p><b>METHODS</b>Dual-luciferase cis-reporting system was used to detect the relative value of pNF-kappaB-TA-luc upon tumor necrosis factor-alpha (TNF-alpha) stimulation of NF-kappaB pathway. Western blotting was used to detect the protein level of NF-kappaB p65, and RT-PCR was used to detect the gene transcription level of intercellular adhesion molecule-1 (ICAM-1), a target downstream gene of NF-kappaB.</p><p><b>RESULTS</b>At the concentration of 0.25 and 0.5 microg/ml, cinobufagin significantly lowered the relative value of luciferase (P<0.05). The results of Western blotting showed that cinobufagin significantly suppressed the protein expression of NF-kappaB p65. The transcription level of ICAM-1 was reduced by different doses of cinobufagin.</p><p><b>CONCLUSION</b>The anti-cancer effect of cinobufagin may be related to its activity in inhibiting the activation of NF-kappaB pathway.</p>

Bioinformatics analysis of mosquito densovirus nostructure protein NS1 / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To analyze and predict the structure and function of mosquito densovirus (MDV) nostructual protein1 (NS1).</p><p><b>METHODS</b>Using different bioinformatics software, the EXPASY pmtparam tool, ClustalX1.83, Bioedit, MEGA3.1, ScanProsite, and Motifscan, respectively to comparatively analyze and predict the physic-chemical parameters, homology, evolutionary relation, secondary structure and main functional motifs of NS1.</p><p><b>RESULTS</b>MDV NS1 protein was a unstable hydrophilic protein and the amino acid sequence was highly conserved which had a relatively closer evolutionary distance with infectious hypodermal and hematopoietic necrosis virus (IHHNV). MDV NS1 has a specific domain of superfamily 3 helicase of small DNA viruses. This domain contains the NTP-binding region with a metal ion-dependent ATPase activity. A virus replication roller rolling-circle replication(RCR) initiation domain was found near the N terminal of this protein. This protien has the biological function of single stranded incision enzyme.</p><p><b>CONCLUSION</b>The bioinformatics prediction results suggest that MDV NS1 protein plays a key role in viral replication, packaging, and the other stages of viral life.</p>

Construction of the life cycle of Angiostrongylus cantonensis in laboratory / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct the life cycle of Angiostrongylus cantonensis (A.cantonensis) in laboratory condition.</p><p><b>METHODS</b>SD rats were infected orally with the third-stage larvae of A.cantonensis collected from Jiangmen, Guangdong province. Six weeks after infection, the first-stage larvae were isolated from fresh feces of the rats by using Baermann funnel to infect 25 second-generation white jade snails raised in laboratory at the daily dose of 300 000 for 3 consecutive days. Three weeks later, the snails were dissected for counting the third-staged larvae of A.cantonensis, and those positive for A.cantonensis infection were fed directly to 10 fasting rats. The serum samples of the rats were then collected 2 weeks later for examination of specific antibodies using ELISA. The feces of the infected rats were examined microscopically after 6 weeks, and the brain, heart and lungs of the infected rats were dissected to observe the larvae at 3, 5, and 8 weeks, respectively.</p><p><b>RESULTS</b>The 3-stage larvae of A.cantonensis were found in the second-generation snails 3 weeks after infection. The positivity rate of serum specific antibodies was 100% in the 10 rats 2 weeks after feeding of the infected snails. The 1-stage larvae were detected in the feces of the rats 6 weeks after infection, and the fourth-stage larvae were found in the brain of the rats at 3 weeks, while adult worm and eggs were found in the heart and lungs of the infected rats at 5 and 8 weeks.</p><p><b>CONCLUSION</b>The successful establishment of human colon carcinoma cell line with PRL-3 gene knock-down provide a basis for investigation of the role of PRL-3 gene in the metastasis of human colorectal carcinoma.</p>

Screening and identification of therapeutic effect evaluation antigens of angiostrongyliasis / 南方医科大学学报

<p><b>OBJECTIVE</b>To identify antigens which may help evaluate the therapeutic effect of angiostrongyliasis from adult worm antigen of Angiostrongylus cantonensis.</p><p><b>METHODS</b>The adult worm antigens of A. cantonensis were analyzed by Western blotting with the sera of rats infected with A. cantonensis before and after treatment. The sera of rats were tested by enzyme-linked immunosorbent assay (ELISA).</p><p><b>RESULTS</b>The antigens with relative molecular mass between 38,000 and 78,000 reacted not only with the sera of rats before treatment, but also with that after treatment. The antigens with M(r) between 190,000 and 17,000 reacted with the sera of rats before treatment but not with that after treatment; those with M(r) between 32,000 and 24,000 antigens strongly reacted with the former, but the reaction became much weakened with the latter. The AC32-IgG antibody appeared earlier than the AC-IgG, and disappeared rapidly after treatment. Six of the 10 treated rats became negative for AC-IgG as found by ELISA.</p><p><b>CONCLUSION</b>The antigens of adult worm antigen of A. cantonensis with M(r) of 190,000, 32,000, 24,000, 17,000 and 16,000 may serve as candidate antigens for therapeutic effect evaluation of angiostrongyliasis.</p>