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971.
A growing body of evidence suggests an important role for fibrinogen-like proteins in innate immunity in both vertebrates and invertebrates. It has been shown that fibrinogen-related proteins (FREPs), plasma proteins present in the freshwater snail Biomphalaria glabrata, the intermediate host for the human blood fluke Schistosoma mansoni, are diverse and involved in snail innate defense responses. To gain further insight into the functions of FREPs, recombinant FREP proteins (rFREPs) were produced in Escherichia coli and antibodies (Abs) were raised against the corresponding rFREPs. We first show that most FREP proteins exist in their native conformation in snail hemolymph as multimeric proteins. Western blot analyses reveal that expression of multiple FREPs including FREP4 in plasma from M line and BS-90 snails, which are susceptible and resistant to S. mansoni infection, respectively, is up-regulated significantly after infection with the trematode Echinostoma paraensei. Moreover, our assays demonstrate that FREPs are able to bind E. paraensei sporocysts and their secretory/excretory products (SEPs), and a variety of microbes (Gram-positive and Gram-negative bacteria and yeast). Furthermore, this binding capability shows evidence of specificity with respect to pathogen type; for example, 65-75-kDa FREPs (mainly FREP4) bind to E. paraensei sporocysts and their SEPs whereas 95-kDa and 125-kDa FREPs bind the microbes assayed. Our results suggest that FREPs can recognize a wide range of pathogens, from prokaryotes to eukaryotes, and different categories of FREPs seem to exhibit functional specialization with respect to the pathogen encountered. 相似文献
972.
Ya-li Li Guang-zhi Wu Gavin S. Dawe Li Zeng Shu-sen Cui Gabriele Loers Thomas Tilling Li Sun Melitta Schachner Zhi-Cheng Xiao 《PloS one》2008,3(12)
Background
Cell surface glycosylation patterns are markers of cell type and status. However, the mechanisms regulating surface glycosylation patterns remain unknown.Methodology/Principal Findings
Using a panel of carbohydrate surface markers, we have shown that cell surface sialylation and fucosylation were downregulated in L1−/y neurons versus L1+/y neurons. Consistently, mRNA levels of sialyltransferase ST6Gal1, and fucosyltransferase FUT9 were significantly reduced in L1−/y neurons. Moreover, treatment of L1+/y neurons with L1 antibodies, triggering signal transduction downstream of L1, led to an increase in cell surface sialylation and fucosylation compared to rat IgG-treated cells. ShRNAs for both ST6Gal1 and FUT9 blocked L1 antibody-mediated enhancement of neurite outgrowth, cell survival and migration. A phospholipase Cγ (PLCγ) inhibitor and shRNA, as well as an Erk inhibitor, reduced ST6Gal1 and FUT9 mRNA levels and inhibited effects of L1 on neurite outgrowth and cell survival.Conclusions
Neuronal surface sialylation and fucosylation are regulated via PLCγ by L1, modulating neurite outgrowth, cell survival and migration. 相似文献973.
Cobalt is an essential microelements in many biological processes involving enzymatic activity. We found that Zn2+ and Mg2+, which are in the active site of native calf intestine alkaline phosphatase (CIP), can be replaced by Co2+ directly in solution. The effect of Co2+ concentration on the substitution reaction was examined at ratios of [Co2+]/[CIP] from 0:1 to 8:1. The quantity of Zn2+ in CIP decreased progressively as the ratio was increased, but the amount of Mg2+ changed in irrregular fashion. A series of active site models of the reaction mechanism of CIP are proposed. Low pH was found to promote the replacement of Mg2+ by Co2+. To understand how the substitution affects the enzyme, we also solved the secondary structure of CIP after reaction with Co2+ in different conditions. 相似文献
974.
Zhang Y Ju J Peng H Gao F Zhou C Zeng Y Xue Y Li Y Henrissat B Gao GF Ma Y 《The Journal of biological chemistry》2008,283(46):31551-31558
An intracellular mannanase was identified from the thermoacidophile Alicyclobacillus acidocaldarius Tc-12-31. This enzyme is particularly interesting, because it shows no significant sequence similarity to any known glycoside hydrolase. Gene cloning, biochemical characterization, and structural studies of this novel mannanase are reported in this paper. The gene consists of 963 bp and encodes a 320-amino acid protein, AaManA. Based on its substrate specificity and product profile, AaManA is classified as an endo-beta-1,4-mannanase that is capable of transglycosylation. Kinetic analysis studies revealed that the enzyme required at least five subsites for efficient hydrolysis. The crystal structure at 1.9 angstroms resolution showed that AaManA adopted a (beta/alpha)8-barrel fold. Two catalytic residues were identified: Glu151 at the C terminus of beta-stand beta4 and Glu231 at the C terminus of beta7. Based on the structure of the enzyme and evidence of its transglycosylation activity, AaManA is placed in clan GH-A. Superpositioning of its structure with that of other clan GH-A enzymes revealed that six of the eight GH-A key residues were functionally conserved in AaManA, with the exceptions being residues Thr95 and Cys150. We propose a model of substrate binding in AaManA in which Glu282 interacts with the axial OH-C(2) in-2 subsites. Based on sequence comparisons, the enzyme was assigned to a new glycoside hydrolase family (GH113) that belongs to clan GH-A. 相似文献
975.
Our previous studies have indicated that TGF-beta1 exerts its effect on the expression of A-type potassium channels (I(A)) in rat vascular myofibroblasts by activation of protein kinase C during the phenotypic transformation of vascular fibroblasts to myofibroblasts. In the present study, patch-clamp whole-cell recording and transwell-migration assays were used to examine the effects of TGF-beta1- and phorbol 12-myristate 13-acetate (PMA)-induced expression of I(A) channels on myofibroblast migration and its modulation by the protein kinase A (PKA) pathway. Our results reveal that incubation of fibroblasts with TGF-beta1 or PMA up-regulates the expression of I(A) channels and increases myofibroblast migration. Blocking I(A) channel expression by 4-aminopyridine (4-AP) significantly inhibits TGF-beta1- and PMA-induced myofibroblast migration. Incubation of fibroblasts with forskolin does not result in increased expression of I(A) channels but does cause a slight increase in fibroblast migration at higher concentrations. In addition, forskolin increases the TGF-beta1- and PMA-induced myofibroblast migration but inhibits TGF-beta1- and PMA-induced the expression of I(A) channels. Whole-cell current recordings showed that forskolin augments the delayed rectifier outward K(+) (I(K)) current amplitude of fibroblasts, but not the I(A) of myofibroblasts. Our results also indicate that TGF-beta1- and PMA-induced expression of I(A) channels might be related to increase TGF-beta1- or PMA-induced myofibroblast migration. Promoting fibroblast and myofibroblast migration via the PKA pathway does not seem to involve the expression of I(A) channels, but the modulation of I(K) and I(A) channels might be implicated. 相似文献
976.
This study isolated nine strains of aerobic phenol-degrading granules. These isolates (I1–I9) were characterized using 16S
rRNA gene sequencing, with γ-Proteobacteria as the dominant strains in the aerobic granules. While most strains demonstrated either high phenol-degrading capabilities
or auto-aggregation capabilities, three isolates, I2, I6, and I8 showed both features. These findings contradict the previous
view that auto-aggregation and phenol degradation are mutually exclusive in aerobic granules. Strains I2 and I8 independently
formed single-culture aerobic granules except for I3. Anti-microbial activity test results indicated that strains I2 and I8
inhibited growth of strain I3. However, co-culturing I3 with I2 or I8 helped to form granules. 相似文献
977.
Proteomic analysis of cervical cancer cells treated with suberonylanilide hydroxamic acid 总被引:1,自引:0,他引:1
Jianxiong He Canhua Huang Aiping Tong Bin Chen Zhi Zeng Peng Zhang Chunting Wang Yuquan Wei 《Journal of biosciences》2008,33(5):715-721
Suberonylanilide hydroxamic acid (SAHA) is an orally administered histone deacetylase inhibitor (HDACI) that has shown significant
antitumour activity in a variety of tumour cells. To identify proteins involved in its antitumour activity, we utilized a
proteomic approach to reveal protein expression changes in the human cervical cancer cell line HeLa following SAHA treatment.
Protein expression profiles were analysed by 2-dimensional polyacrylamide gel electrophoresis (2-DE) and protein identification
was performed on a MALDI-Q-TOF MS/MS instrument. As a result, a total of nine differentially expressed proteins were visualized
by 2-DE and Coomassie brilliant blue (CBB) staining. Further, all the changed proteins were positively identified via mass
spectrometry (MS)/MS analysis. Of these, PGAM1 was significantly downregulated in HeLa cells after treatment with SAHA. Moreover,
PGAM1 has been proven to be downregulated in another cervical cancer cell line (CaSki) by western blot analysis. Together,
using proteomic tools, we identified several differentially expressed proteins that underwent SAHA-induced apoptosis. These
changed proteins may provide some clues to a better understanding of the molecular mechanisms underlying SAHA-induced apoptosis
in cervical cancer. 相似文献
978.
Pi Y Liao Z Jiang K Huang B Deng Z Zhao D Zeng H Sun X Tang K 《Bioscience reports》2008,28(6):349-355
AOC (allene oxide cyclase; EC 5.3.99.6), an essential enzyme in jasmonic acid and its methyl ester biosynthesis, was cloned from Camptotheca acuminata (named as CaAOC), a native medicinal plant species in China. CaAOC had significant similarity at the amino-acid level with AOCs from other plant species. Comparison between the sequences of the full-length cDNA and genomic DNA of CaAOC revealed that the genomic DNA of CaAOC contained an 89-bp intron and a 240-bp intron. Southern-blot analysis indicated that CaAOC was a multiple-copy gene, and real-time quantitative PCR analysis showed that CaAOC was expressed constitutively in all organs tested, with the highest expression level in leaves. The results from treatment experiments using different signalling components, including methyl jasmonate, abscisic acid, salicylic acid and H(2)O(2), revealed that expression of CaAOC had a prominent diversity. Heavy metal (copper) significantly enhanced CaAOC expression, whereas wounding (induced by UV-B) was not so effective. 相似文献
979.
Tang JN Zeng ZG Wang HN Yang T Zhang PJ Li YL Zhang AY Fan WQ Zhang Y Yang X Zhao SJ Tian GB Zou LK 《Journal of microbiological methods》2008,75(3):432-436
Polymerase chain reaction (PCR) detection of microorganism in faecal specimens is hampered by poor recovery of DNA and by the presence of PCR inhibitors. In this paper, we describe a new modified method for extracting PCR-quality microbial community DNA from pig faecal samples, which combines the pretreatment with polyformaldehyde, and subsequent DNA lysis in the presence of CTAB, salt, PVP, and beta-mercaptoethanol, followed by isolation of nucleic acids using chloroform (no phenol) based protocol. The method resulted in a 1.3- to 11-fold increase in DNA yield when compared to four other widely used methods. Genomic DNA extracted from all five methods was assessed by both agarose gel electrophoresis and polymerase chain reaction for amplification of 16S rDNA specific fragments. The results showed that the improved method represented a reproducible, simple, and rapid technique for routine DNA extraction from faecal specimens and was notably better than using the QIAamp DNA Stool Mini Kit. 相似文献
980.
Multiplex PCR and DNA microarray were combined with tyramide signal amplification (TSA) to develop a reliable method suitable for simultaneous detection of six species of human diarrheal pathogens (Yersinia enterocolitica, Shigella spp, Salmonella typhi, Brucella spp, Vibrio cholera and Escherichia coli O157:H7). Meanwhile, our method could distinguish V. cholera serotype O1 from O139, and O157:H7 from O157: non-H7. This assay conferred a specificity of 100% for target pathogens. The limit of detection was 103 degrees CFU/mL approximately. The results of 98.6% (357/362) clinical specimens and 100% (5/5) mocked double-blind samples were the same to that from conventional assay. Consequently this assay is sensitive and a specific tool suitable for diagnostic detection and surveillance of multiple human pathogens. 相似文献