Characterization of IncI1/ST71 and IncF18:A-:B1 multidrug-resistance plasmids from an avian Escherichia coli isolate.

To characterize IncI1 and IncF18:A-:B1 multidrug-resistance plasmids from an avian Escherichia coli isolate, antibiotic susceptibility testing, conjugation assays, transformation assays, S1-PFGE, and WGS analysis were performed. The 119,457-bp plasmid pEC014-1 with a multidrug-resistance region (MRR) containing four different segments interspersed with six IS26 elements, belonged to incompatibility group I1 and sequence type 71. The 154,516-bp plasmid pEC014-2 with two replicons, typed as FII-18 and FIB-1, carried 14 resistance determinants including blaTEM-1b, blaOXA-1, oqxAB, dfrA17, aac(6')-Ib-cr, sul1, sul2, tet(A), floR, catB3, hph(aph(4)-Ia), aacC4(aac(3)-IV), aadA5, arr-3, and a merEDACPTR loci in MRR, and additionally encoded three virulence loci: iroNEDCB, sitABCD, and iucABCD-iutA. Plasmid stability assays showed that pEC014-1 and pEC014-2 were stable in recipient E. coli C600 for at least 15 days of passage. Competition assays were carried out to evaluate the fitness impact of pEC014-2 carriage in vitro, revealing a decrease in host fitness. Growth kinetics showed that the growth rate for pEC014-1 or/and pEC014-2 bearing cells was significantly slower than that of the E. coli C600 host strain in the exponential stage (p < 0.01), with only cells carrying pEC014-1 sustaining rapid growth after 6 h of exponential growth. Our findings highlight the mosaic structures of epidemic plasmid IncI1/ST71 and F18:A-:B1 lineages and contribute to a better understanding of the evolution and dissemination of these multidrug resistance and virulence plasmids.

Novel imidazo[1,2,4] triazole derivatives: Synthesis, fluorescence, bioactivity for SHP1.

The Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP1) is a convergent node for oncogenic cell-signaling cascades. Consequently, SHP1 represents a potential target for drug development in cancer treatment. The development of efficient methods for rapidly tracing and modulating the SHP1 activity in complex biological systems is of considerable significance for advancing the integration of diagnosis and treatment of the related disease. Thus, we designed and synthesized a series of imidazo[1,2,4] triazole derivatives containing salicylic acid to explore novel scaffolds with inhibitory activities and good fluorescence properties for SHP1. The photophysical properties and inhibitory activities of these imidazo[1,2,4] triazole derivatives (5a-5y) against SHP1PTP were thoroughly studied from the theoretical simulation and experimental application aspects. The representative compound 5p exhibited remarkable fluorescence response (P: 0.002) with fluorescence quantum yield (QY) of 0.37 and inhibitory rate of 85.21 ± 5.17% against SHP1PTP at the concentration of 100 µM. Furthermore, compound 5p showed obvious aggregation caused quenching (ACQ) effect and had high selectivity for Fe3+ ions, good anti-interference and relatively low detection limit (5.55 µM). Finally, the cellular imaging test of compound 5p also exhibited good biocompatibility and certain potential biological imaging application. This study provides a potential way to develop molecules with fluorescent properties and bioactivities for SHP1.

[Progress in genes related to seed-coat color in soybean].

Seed-coat color has changed from black to yellow during natural and artificial selection of cultivated soybean from wild soybean, and it is also an important morphological marker. Therefore, discovering genes related to the soybean seed-coat color will play a very important role in breeding and evolutionary study. Different seed-coat colors caused by deposition of various anthocyanin pigments. Although pigmentation has been well dissected at molecular level in several plant species, the genes controlling natural variation of seed-coat color in soybean remain to be unknown. Genes related to seed-coat color in soybean were discussed in this paper, including 5 genetic loci (I, T, W1, R and O). Locus I is located in a region that riches in chalcone synthase (CHS) genes on chromosome 8. Gene CHS is a multi-gene family with highly conserved sequences in soybean. Locus T located on chromosome 6 has been cloned and verified, which encodes a flavon-oid-3'-hydroxylase. Mutant of F3'H can not interact with the heme-binding domain due to lack of conservative domain GGEK caused by a nucleotide deletion in the coding region of F3'H. Locus R is located between A668-1 and K387-1 on chromosome 9 (linkage group K). This locus may encode a R2R3 MYB transcription factor or a UDP flavonoid 3-O glyco-syltransferase. Locus O is located between Satt207 and Satt493 on chromosome 8 (linkage group A2) and its molecular characteristics has not been characterized. Locus W1 may be a homology of F3'5'H gene.

Comparative proteomic analysis of apomictic monosomic addition line of Beta corolliflora and Beta vulgaris L. in sugar beet.

Apomixis refers to a process in which plants produce seed without fertilization through female syngamy that produces embryos genetically identical to the maternal parent. In sugar beet, interspecific hybrids between diploid Beta vulgaris and tetraploid Beta corolliflora were established and monosomic addition line M14 was selected because of the apomictic phenotype. By using two-dimensional electrophoresis gels we identified the proteins which were differently expressed between the M14 and B. vulgaris. A total of 27 protein spots which varied expressed between lines were isolated and successfully identified with MALDI-TOF MS. Among them five protein spots were found to be only presented in M14 and two protein spots only expressed in Beta. According to their functional annotations described in Swissprot database, these proteins were, respectively, involved in important biological pathways, such as cell division, functionally classified using the KEGG functional classification system. The result may be useful for us to better understand the genetic mechanism of apomixes.

The regulating role of mutant IkappaBalpha in expression of TIMP-2 and MMP-9 in human glioblastoma multiform.

BACKGROUND: Our previous studies demonstrated that mutant IkappaBalpha (IkappaBalphaM) inhibited the occurrence, growth and angiogenesis of human glioblastoma multiform (GBM). However, the specific mechanism by which IkappaBalphaM regulates protein-degrading enzymes secreted from GBM to inhibit invasion and metastasis has remained unclear. The aim of the present study was to investigate the regulatory role and significance of IkappaBalphaM genes in the expression of tissue inhibitor of metalloproteinase (TIMP)-2 and matrix metalloproteinase (MMP)-9 in human GBM. METHODS: We established the following four GBM cell lines stably expressing IkappaBalphaM by plasmid construction, gene transfection and screening for IkappaBalphaM protein expression: mutant IkappaBalpha-transfected cells (G36Delta-M), wild-type IkappaBalpha-transfected cells (G36Delta-W), empty plasmid transfected cells (G36Delta-P) and untransfected cells (G36Delta). The TIMP-2 and MMP-9 expression was detected by RT-PCR and Western blotting. Tumor cells were then implanted subcutaneously into nude mice to establish an animal model of ectopic tumor growth, and TIMP-2 and MMP-9 expression was determined by immunohistochemical methods. RESULTS: The results showed that there was a significant increase in TIMP-2 expression and a significant decrease in MMP-9 expression in the G36Delta-M group at both the RNA and protein levels compared with the G36Delta-W group, G36Delta-P group and G36Delta group. Similar results were observed in the immunohistochemical staining analysis of tumor tissues. In the G36Delta-M group, TIMP-2 expression was significantly higher while MMP-9 expression was significantly lower than in the other three groups. CONCLUSIONS: Our findings indicate that IkappaBalphaM inhibits the activation of NF-kappaB. It significantly up-regulates TIMP-2 expression in human malignant glioma cells and down-regulates the expression of MMP-9. Thus, IkappaBalphaM maintains the integrity of the extracellular matrix and further inhibits the growth and metastasis of tumor tissues.

[Construction of eukaryotic expression vector of short hairpin RNA targeting human xylosyltransferase-I gene].

OBJECTIVE: To design and construct the plasmids expressing short hairpin RNA (shRNA) targeting human xylosyltransferase- I (XT- I) which is the initiating enzyme in the biosynthesis of proteoglycans (PC). METHODS: Short chain oligonucleotides were designed according to the sequence of XT-I provided by GenBank. The DNA segments were gained through annealing after chemosynthesis, and were cloned into Pgenesil-1 vector. The recombinant XT- I shRNA expression vectors were identified by digestion and sequencing analysis. At last the constructed XT-I expression vectors were transfected into salivary adenoid cystic carcinoma cell line (ACC-M) by Lipofectomine 2000. The expression of green fluorescent protein (GFP) was detected by inverted fluorescent microscope and the rates of transfection were detected by flow cytometer. Semiquantitative RT-PCR was used to detect the expression of mRNA level of XT- I in transfected ACC-M cells and the protein expression of XT- I was detected by Western blot. RESULTS: The plasmids expressing shRNA targeting XT-I gene are called WJ1, WJ2, WJ3, WJ4, WJ5 and WJ6. Successful constructions were identified by digestion and sequencing. The mean rate of transfection was 50.26%. ACC-M cells transfected with WJ1-WJ6 expressed GFP successfully. And by RT-PCR and Western blot, WJ3 showed the most powerful RNAi gene silencing of inhibitory. The inhibition rate was 72.39% of mRNA level and 70.18% of protein level respectively. CONCLUSION: The XT-I shRNA expression vectors were constructed successfully which lays the foundation for RNAi study on the biosynthesis of PG in salivary gland tumors.

[Effect of shRNA-mediated silence of H-ras gene on proliferation of human SACC-M cells].

OBJECTIVE: To examine the effects of H-ras gene silence on cell cycle, proliferation and apoptosis of salivary adenoid cystic carcinoma -M (SACC-M) cell lines. METHODS: The plasmid H-ras-shRNA, containing the sequence of shRNA targeting H-ras, and HK-shRNA (without interfering effect) were constructed and transfected into SACC-M cells. The cell line with shRNA plasmid stable expression was isolated by G418. The expression levels of H-ras were detected by RT-PCR and protein immunofluorescent assay; cell cycle and cell apoptosis were analyzed by flow cytometry (FCM). The proliferation of cell was also determined by subcutaneous tumor formation in nude mice. RESULTS: After transfection of H-ras-shRNA plasmid, the mRNA expression of H-ras in SACC-M cells was down-regulated by 61.80% and protein expression of H-ras was inhibited by 62.76%; the cell proliferation was inhibited obviously; the G0G1 phase cells were increased. The cell apoptosis rate of H-ras-shRNA group was significantly higher than that of HK-shRNA group (P <0.05). The volume of subcutaneous tumor in nude mice was significantly smaller in Hras-shRNA group than in control group. CONCLUSIONS: The recombinant plasmid HRAS-shRNA could efficiently down-regulate the expression of H-ras gene and protein, induce apoptosis of SACC-M cells and simultaneously inhibit proliferation of these cells in vitro and in vivo.

[Preparation and identification of anti-human polyclonal antibody against xylosyltransferase-I].

AIM: To prepare the rabbit polyclonal antibody against human xylosyltransferase-I (XT-I) protein and to identify its specificity. METHODS: The predominant epitope of XT-I gene was predicted by the DNAssist software. The DNA fragment of this epitope region was synthesized by PCR and cloned into the pGEX-4T-2 vector. The recombinant plasmid was transformed into E.coli ER2566 and the fusion protein GST-XT was induced and isolated. The purified fusion protein was used to immunize New Zealand rabbits. The antibody titer was determined by ELISA. Purified polyclonal antibody was obtained through affinity chromatography column and the specificity of the purified antibody was characterized by Western blot. RESULTS: The amino acid 175-205 of XT-I (QKHQPELAKKPPSRQK-ELLKRKLEQQEKGKG) was selected as an antigen epitope. The synthesized DNA fragment of XT-I was successfully inserted into pGEX-4T-2 vector and the protein GST-XT was expressed. The purified fusion protein GST-XT was used as the immunogen to immunize rabbits and the polyclonal antibody against XT-I protein was obtained. The result of ELISA showed that the antibody titer was 1:640 000. Western blot analysis showed that the antibody had a good specificity. CONCLUSION: The rabbit polyclonal antibody against human XT-I protein has been successfully prepared, which lays the foundation for further study on the biosynthesis of PG by neoplastic myoepithelial cells in salivary tumors.

[An experimental study on porcine fibroblasts transfected by dental matrix protein-1 gene].

OBJECTIVE: To evaluate the expression of dental matrix protein-l (DMP1) in porcine oral mucosa fibroblasts (POMF) transfected by DMP1 and the influences of the transfection. METHODS: The full length of porcine DMP1 cDNA was linked into an eukaryotic expression vector pEGFP-C1. POMF and mesenchymal stem cells (MSC) were transfected with the pEGFP-DMP1. The expression of DMP1, dental sialoprotein (DSP), amelin and ameloblastin (Ambn) gene of transfected POMF and MSC were detected by RT-PCR. The expression of DMP1 and DSP protein was examined by immunocytochemical staining. The formation ratio of mineralized nodules of transfected cells was compared with un-transfected ones after mineralized induction. The formation of mineralized nodules of three-dimensional pellet transfected cells was compared with un-transfected ones after hematoxylin and eosin staining. RESULTS: The constructed pEGFP-DMP1 could produce 4.7 kb and 1.5 kb fragments. DMP1 gene, DSP gene and Ambn gene were expressed by POMF after transfection. Immunohistochemical staining and the quantitative analysis of protein showed that DMP1 and DSP protein was positive in transfected POMF and MSC. The formation ratio of mineralized nodules of transfected POMF and MSC was higher than that of un-transfected ones (P < 0.05). CONCLUSIONS: The expression of porcine DMP1 in POME after gene transfection can induce the expression of tooth-development-associated gene Ambn and DSP and enhance the formation of mineralized nodules.