Using fluorescence in situ hybridization, the authors investigated the homology between three plant species, maize (Zea mays L.) and tobacco (Nicotiana tabacum L.), maize and Arabidopsis thaliana (L.) Heynh. at cy...Using fluorescence in situ hybridization, the authors investigated the homology between three plant species, maize (Zea mays L.) and tobacco (Nicotiana tabacum L.), maize and Arabidopsis thaliana (L.) Heynh. at cytogenetic level using two probes corresponding to functional disease resistance genes myb1 and NDR1 in Arabidopsis and tobacco respectively. The hybridization signals of the tested probes were detected in maize chromosomes 8 and 5 respectively, and the single location of each of the two probes showed only single copy of them in maize genome. The results provided a valuable insight into searching for genes associated with programmed cell death in plants using heterologous probe with comparative genetic approach. In addition, the improvements of FISH technique using heterologous probes were discussed.展开更多
Based on both cDNA sequence of barley powdery mildew resistance control element Mlo and DNA sequence of the known putative disease resistance gene from Triticum monococcum L., we designed some primers to amplify resis...Based on both cDNA sequence of barley powdery mildew resistance control element Mlo and DNA sequence of the known putative disease resistance gene from Triticum monococcum L., we designed some primers to amplify resistant homologous sequences in the near isogenic lines (NILs) of powdery mildew resistance using RT-PCR method. Two expressed cDNA fragments were isolated from wheat genome. One showed 83% homology to the Mlo gene of barley. The other contained two possible open reading frames (ORFs). NBS conservative domains 2, 3 of disease resistance gene and 13 LRR structures similar to rice Pib protein terminal were found respectively in the two ORFs. It indicated that the latter fragment belongs to NBS-LRR-like genes. The obvious difference of RT-PCR products was observed between the before challenged and the challenged for 72 h by Blumeria graminis f. sp. tritici, which, implied that this sequence could be associated with disease resistance of wheat. Using nulli-tetrasomic lines of 'Chinese Spring', the NBS-LRR-like gene had been located on chromosome 1D.展开更多
Conserved domains e.g. nucleotide binding site (NBS) were found in several cloned plant disease resistance genes. Based on the NBS domain, resistance gene analogs (RGAs) have been isolated previously and were used as ...Conserved domains e.g. nucleotide binding site (NBS) were found in several cloned plant disease resistance genes. Based on the NBS domain, resistance gene analogs (RGAs) have been isolated previously and were used as probes to screen a soybean (Glycine max L. Merr.) cDNA library. A full-length cDNA, KR3, was obtained by screening the library and rapid amplification of cDNA ends (RACE) method. Sequence analysis revealed that the cDNA is 2 353 bp in length and the open reading frame (ORF) codes for a polypeptide of 636 amino acids with a Toll-Interleukin-1 receptor (TIR) and a NBS domain. Sequence alignment showed that it was similar to N gene of tobacco. The phylogenetic tree analysis of R proteins with NBS from higher plants was performed. The KR3 gene has low copies in soybean genome and its expression was induced by exogenous salicylic acid (SA).展开更多
The degenerate primers were designed based on the conserved NBS-LRR motifs among the known disease-resistance genes. A fragment of about 500 bp was amplified from genomic DNA of sweet potato using the specifically des...The degenerate primers were designed based on the conserved NBS-LRR motifs among the known disease-resistance genes. A fragment of about 500 bp was amplified from genomic DNA of sweet potato using the specifically designed degenerate primers. After cloning and sequencing, 20 NBS-LRR type of disease-resistance gene analogue (RGAs) in sweet potato were observed. The deduced amino acid sequence of DNA fragment contains the conserved motifs of NBS-LRR type RGAs, such as P-loop, Kinase-2α, Kinase-3α and GLPL domain. The 20 RGAs could be sorted into two subclasses, namely TIR- NBS-LRR type and non-TIR-NBS-LRR type. Compared with the known resistance genes including N, L6 and M, the percentages of homologous amino acid sequence in 10 TIR-NBS-LRR range between 21% -44%. While other 10 non-TIR-NBS-LRR assume 15% -46% homology with the known resistance genes (Prf, RPM1, RPS2, etc. ). Consequently the RGAs may further be used as molecular marker for screening the candidate disease-resistance genes in sweet potato.展开更多
From the. genome of the Rice-field Eel,Monopterus alubs partial DNA sequence has been obtained that shows homology to the 5'cDNA sequence of the gene encoding rat tyrosine kinase receptor ptk3. Southern blots reve...From the. genome of the Rice-field Eel,Monopterus alubs partial DNA sequence has been obtained that shows homology to the 5'cDNA sequence of the gene encoding rat tyrosine kinase receptor ptk3. Southern blots revealed identical hybridization patterns in both sex.展开更多
Alternative splicing is a major contributor to genomic complexity and proteome diversity, yet the analysis of alternative splicing for the sequence containing nucleotide binding site and leucine-rich repeats (NBS-LRR...Alternative splicing is a major contributor to genomic complexity and proteome diversity, yet the analysis of alternative splicing for the sequence containing nucleotide binding site and leucine-rich repeats (NBS-LRR) domain has not been explored in rice (Oryza sativa L.). Hidden Markov model (HMM) searches were performed for NBS-LRR domain. 875 NBS-LRR-encoding sequences were obtained from the Institute for Genomic Research (TIGR). All of them were used to blast Knowledge-based Oryza Molecular Biological Encyclopaedia (KOME), TIGR rice gene index (TGI), and Universal Protein Resource (UniProt) to obtain homologous full-length cDNAs (FL-cDNAs), tentative consensus sequences, and protein sequences. Alternative splicing events were detected from genomic alignment of FL-cDNAs, tentative consensus sequences, and protein sequences, which provide valuable information on splice variants of genes. These sequences were aligned to the corresponding BAC sequences using the Spidey and Sim4 programs and each of the proteins was aligned by tBLASTn. Of the 875 NBS-LRR sequences, 119 (13.6%) sequences had alternative splicing where multiple FL-cDNAs, TGI sequences and proteins corresponded to the same gene. 71 intron retention events, 20 exon skipping events, 16 alternative termination events, 25 alternative initiation events, 12 alternative 5' splicing events, and 16 alternative 3' splicing events were identified. Most of these alternative splices were supported by two or more transcripts. The data sets are available at http://www.bioinfor.org. Furthermore, the bioinformatics analysis of splice boundaries showed that exon skipping and intron retention did not exhibit strong consensus. This implies a different regulation mechanism that guides the expression of splice isoforms. This article also presents the analysis of the effects of intron retention on proteins. The C-terminal regions of alternative proteins turned out to be more variable than the N-terminal regions. Finally, tissue distribution and protein localization of alternative splicing were explored. The largest categories of tissue distributions for alternative splicing were shoot and callus. More than one-thirds of protein localization for splice forms was plasma membrane and cytoplasm. All the NBS-LRR proteins for splice forms may have important function in disease resistance and activate downstream signaling pathways.展开更多
Eight hundred and thirty eight base pair fragment of mitochondrial COI gene of wild and cultured populations (CP1, CP4, CP5 and CP6) of Fenneropenaeus chinensis was amplified and sequenced. The A, T, G and C contents ...Eight hundred and thirty eight base pair fragment of mitochondrial COI gene of wild and cultured populations (CP1, CP4, CP5 and CP6) of Fenneropenaeus chinensis was amplified and sequenced. The A, T, G and C contents of the sequence were 235bp(28.0%), 307bp(36.6%), 138bp(16.5%) and 158bp(18.9%), respectively. Furthermore, 556bp fragment of the sequence was used to discuss the phylogenetic relationship among 14 Penaeidae species using Alpheus armillatus as the outgroup. From the molecular phylogenetic tree constructed by neighbor-joining method, we obtained three large shrimp groups:Farfantepenaeus, Litopenaeus and Fenneropenaeus group. The results also indicated that there were a closer genetic relationships between F. aztecus and F. paulensis, L. schmitti and L. setiferus, F. indicus and F. merguiensis, and the genus Farfantepenaeus was closer to Litopenaeus.展开更多
In recent years (2007 to 2011), although the overall number of rabies cases in China has decreased, there is evidence of emerging or re-emerging cases in regions without previous rabies cases or with low incidence of ...In recent years (2007 to 2011), although the overall number of rabies cases in China has decreased, there is evidence of emerging or re-emerging cases in regions without previous rabies cases or with low incidence of rabies. To investigate the origin and the factors affecting the spread of rabies in China, specimens were collected from 2007 to 2011 from provinces with emerging and re-emerging cases and tested for the presence of the rabies virus. Positive specimens were combined with sequences from GenBank to perform comparisons of homology and functional sites, and to carry out phylogenetic analyses. Out of these regions, five provinces had 9 positive specimens from canine and cattle, and 34 canine or human specimens were obtained from previously high-incidence provinces. Complete sequences of G gene were obtained for these samples. Homology of the sequences of these 43 specimens was 87%-100% at the nucleotide level and 93.7% -100% at the amino acid level. These G gene sequences were combined with reference sequence from GenBank and used to construct a phylogenetic tree. The results showed that 43 specimens were all assigned to China clade I and clade II, with all specimens from emerging and re-emerging areas placed within clade I. Specimens isolated from Shanxi and Inner Mongolia in 2011 were distinct from previously-isolated local strains and had closer homology to strains from Hebei, Beijing and Tianjin whereas new isolates from Shanghai were tightly clustered with strains isolated in the 1990s. Finally, Shaanxi isolates were clustered with strains from adjacent Sichuan. Our results suggest that the rabies cases in emerging and re-emerging areas in China in the last 5 years are a consequence of the epidemic spreading from of neighboring provinces and regions experiencing a serious epidemic of rabies.展开更多
East Lake(Lake Donghu),located in Wuhan,China,is a typical city freshwater lake that has been experiencing eutrophic conditions and algal blooming during recent years.Marine and fresh water are considered to contain a...East Lake(Lake Donghu),located in Wuhan,China,is a typical city freshwater lake that has been experiencing eutrophic conditions and algal blooming during recent years.Marine and fresh water are considered to contain a large number of viruses.However,little is known about their genetic diversity because of the limited techniques for culturing viruses.In this study,we conducted a viral metagenomic analysis using a high-throughput sequencing technique with samples collected from East Lake in Spring,Summer,Autumn,and Winter.The libraries from four samples each generated 234,669,71,837,12,820,and 34,236 contigs(>90 bp each),respectively.The genetic structure of the viral community revealed a high genetic diversity covering 23 viral families,with the majority of contigs homologous to DNA viruses,including members of Myoviridae,Podoviridae,Siphoviridae,Phycodnaviridae,and Microviridae,which infect bacteria or algae,and members of Circoviridae,which infect invertebrates and vertebrates.The highest viral genetic diversity occurred in samples collected in August,then December and June,and the least diversity in March.Most contigs have low-sequence identities with known viruses.PCR detection targeting the conserved sequences of genes(g20,psbA,psbD,and DNApol)of cyanophages further confirmed that there are novel cyanophages in the East Lake.Our viral metagenomic data provide the first preliminary understanding of the virome in one freshwater lake in China and would be helpful for novel virus discovery and the control of algal blooming in the future.展开更多
Acting as one of the pattern recognition receptors (PRRs), C-type lectin is believed to mediate pathogen recognition and plays an important role in the clearance of pathogens as part of the innate immune system. In ...Acting as one of the pattern recognition receptors (PRRs), C-type lectin is believed to mediate pathogen recognition and plays an important role in the clearance of pathogens as part of the innate immune system. In this work, a novel C-type lectin gene (named LvLecl) was cloned from the shrimp Litopenaeus vannamei, The ORF of LvLecl is 510 bp, encoding 169 amino acids. The deduced amino acid sequence contains a putative signal peptide of 19 amino acids at the N-terminal and a carbohydrate recognition domain (CRD) at the C-terminal. LvLecl was mainly expressed in the hepatopancreas. Real-time PCR analysis indicated that the level of LvLecl transcripts significantly changed in the hepatopancreas after the shrimp were artificially challenged with LPS, Micrococcus lysodeikticus and white spot syndrome virus (WSSV). RNAi-based silencing of LvLecl resulted in increases in mortality when the shrimp were challenged with WSSV, and the median lethal time was reduced compared with controls. Although there was no characteristic "EPN" (Glu-Pro-Ser) or "QPD" (Gin-Pro-Asp) motif, the recombinant LvLecl, expressed in Escherichia coli BL21 (DE3), could also agglutinate M. lysodeikticus and Vibrio anguillarum. The agglutinating activities were calcium-dependent and could be inhibited by D-mannose, D-glucose, D-galactose and N-Acetyl-D-mannose. These results suggest that LvLecl might be involved in the immune response against WSSV and bacterial infections and contribute to non-self recognition as a pattern recognition receptor in the innate immune system of the shrimp L. vannamei.展开更多
Helicobacter pylori (H. pylori) virulence factors pro- mote the release of various chemoattractants/inflam- matory mediators, including mainly the neutrophil- attractant chemokine interleukin-8 and neutrophil- activ...Helicobacter pylori (H. pylori) virulence factors pro- mote the release of various chemoattractants/inflam- matory mediators, including mainly the neutrophil- attractant chemokine interleukin-8 and neutrophil- activating protein (NAP), involved in H. pylor/-induced gastric pathologies. Co-administration of Chios mastic gum (CMG), which inhibits H. pylor/NAP, with an H. pylori eradication regimen might add clinical benefits against H. pylori-related gastric pathologies, but pos- sibly not CMG as main therapy. Although H. pylori NAP and other H. pylori-related cytotoxins [i.e., vaculating cytotoxin (VacA)] appear to play a major role in gener- ating and maintaining the H. pylori-associated gastric inflammatory response and H. pylor/NAP is a promising vaccine candidate against H. pylori infection (H. pylori-1), concerns regarding its potential drawbacks, particularly neurogenic ones, due to possible cross- mimicry, should be considered. Possible cross-mimicry between H. p, vlor/ NAP and/or bacterial aquaporin (AQP) and neural tissues may be associated with the anti-AQP-4 antibody-related neural damage in multiple sclerosis (MS)/neuromyelitis optica patients. Moreover, the sequence homology found between H. pylori VacA and human Na+/K+-ATPase A subunit suggests that antibodies to VacA involve ion channels in abaxonal Schwann cell plasmalemma resulting in demyelination in some patients. A series of factors have been im- plicated in inducing blood-brain barrier (BBB) disrup- tion, including inflammatory mediators (e.g., cytokines and chemokines induced by H. pylor/-I) and oxidative stress. BBB disruption permits access of AQP4-specific antibodies and T lymphocytes to the central nervous system, thereby playing a major role in multiple sclero- sis pathogenesis. Relative studies show a strong asso- ciation between H. pylori-I and MS. H. pylor/-I induces humoral and cellular immune responses that, owing to the sharing of homologous epitopes (molecular mim- icry), cross-react with components of nerves, thereby contributing and perpetuating neural tissue damage. Finally, H. pylori NAP also plays a possible pathoge- netic role in both gastric and colon oncogenesis.展开更多
Recent transcription profiling studies have revealed an unexpectedly large proportion of antisense transcripts in eukaryotic genomes. These antisense genes seem to regulate gene expression by interacting with sense ge...Recent transcription profiling studies have revealed an unexpectedly large proportion of antisense transcripts in eukaryotic genomes. These antisense genes seem to regulate gene expression by interacting with sense genes. Previ- ous studies have focused on the non-coding antisense genes, but the possible regulatory role of the antisense protein is poorly understood. In this study, we found that a protein encoded by the antisense gene ADF1 acts as a transcription suppressor, regulating the expression of sense gene MDF1 in Saccharomyces cerevisiae. Based on the evolutionary, ge- netic, cytological and biochemical evidence, we show that the protein-coding sense gene MDF1 most likely originated de novo from a previously non-coding sequence and can significantly suppress the mating efficiency of baker's yeast in rich medium by binding MATa2 and thus promote vegetative growth. These results shed new light on several im- portant issues, including a new sense-antisense interaction mechanism, the de novo origination of a functional gene, and the regulation of yeast mating pathway.展开更多
The complex transformation of a tadpole to a frogduring amphibian development is under the control of thyroid hormone (T3). T3 is known to regulate gene transcription through its nuclear receptors. We have previouslyi...The complex transformation of a tadpole to a frogduring amphibian development is under the control of thyroid hormone (T3). T3 is known to regulate gene transcription through its nuclear receptors. We have previouslyisolated many genes which are up-regulated by T3 in theintestine of Xenopus laevis tadpoles. We have now cloneda full- length cDNA for one such gene (IU12). Sequenceanalysis shows that the IU12 cDNA encodes a plasmamembrane protein with 12 transmembrane domains andhomologous to a mammalian gene associated with cell activation and organ development. Similarly, we have foundthat IU12 is activated during intestinal remodeling whenboth cell death and proliferation take place. Furthermore,IU12 is an early T3-response gene and its expression in theintestine during T3-induced metamorphosis mimics thatduring normal development. These results argue for a roleof IU12 in the signal transduction pathways leading to intestinal metamorphosis.展开更多
文摘Using fluorescence in situ hybridization, the authors investigated the homology between three plant species, maize (Zea mays L.) and tobacco (Nicotiana tabacum L.), maize and Arabidopsis thaliana (L.) Heynh. at cytogenetic level using two probes corresponding to functional disease resistance genes myb1 and NDR1 in Arabidopsis and tobacco respectively. The hybridization signals of the tested probes were detected in maize chromosomes 8 and 5 respectively, and the single location of each of the two probes showed only single copy of them in maize genome. The results provided a valuable insight into searching for genes associated with programmed cell death in plants using heterologous probe with comparative genetic approach. In addition, the improvements of FISH technique using heterologous probes were discussed.
文摘Based on both cDNA sequence of barley powdery mildew resistance control element Mlo and DNA sequence of the known putative disease resistance gene from Triticum monococcum L., we designed some primers to amplify resistant homologous sequences in the near isogenic lines (NILs) of powdery mildew resistance using RT-PCR method. Two expressed cDNA fragments were isolated from wheat genome. One showed 83% homology to the Mlo gene of barley. The other contained two possible open reading frames (ORFs). NBS conservative domains 2, 3 of disease resistance gene and 13 LRR structures similar to rice Pib protein terminal were found respectively in the two ORFs. It indicated that the latter fragment belongs to NBS-LRR-like genes. The obvious difference of RT-PCR products was observed between the before challenged and the challenged for 72 h by Blumeria graminis f. sp. tritici, which, implied that this sequence could be associated with disease resistance of wheat. Using nulli-tetrasomic lines of 'Chinese Spring', the NBS-LRR-like gene had been located on chromosome 1D.
文摘Conserved domains e.g. nucleotide binding site (NBS) were found in several cloned plant disease resistance genes. Based on the NBS domain, resistance gene analogs (RGAs) have been isolated previously and were used as probes to screen a soybean (Glycine max L. Merr.) cDNA library. A full-length cDNA, KR3, was obtained by screening the library and rapid amplification of cDNA ends (RACE) method. Sequence analysis revealed that the cDNA is 2 353 bp in length and the open reading frame (ORF) codes for a polypeptide of 636 amino acids with a Toll-Interleukin-1 receptor (TIR) and a NBS domain. Sequence alignment showed that it was similar to N gene of tobacco. The phylogenetic tree analysis of R proteins with NBS from higher plants was performed. The KR3 gene has low copies in soybean genome and its expression was induced by exogenous salicylic acid (SA).
文摘The degenerate primers were designed based on the conserved NBS-LRR motifs among the known disease-resistance genes. A fragment of about 500 bp was amplified from genomic DNA of sweet potato using the specifically designed degenerate primers. After cloning and sequencing, 20 NBS-LRR type of disease-resistance gene analogue (RGAs) in sweet potato were observed. The deduced amino acid sequence of DNA fragment contains the conserved motifs of NBS-LRR type RGAs, such as P-loop, Kinase-2α, Kinase-3α and GLPL domain. The 20 RGAs could be sorted into two subclasses, namely TIR- NBS-LRR type and non-TIR-NBS-LRR type. Compared with the known resistance genes including N, L6 and M, the percentages of homologous amino acid sequence in 10 TIR-NBS-LRR range between 21% -44%. While other 10 non-TIR-NBS-LRR assume 15% -46% homology with the known resistance genes (Prf, RPM1, RPS2, etc. ). Consequently the RGAs may further be used as molecular marker for screening the candidate disease-resistance genes in sweet potato.
文摘From the. genome of the Rice-field Eel,Monopterus alubs partial DNA sequence has been obtained that shows homology to the 5'cDNA sequence of the gene encoding rat tyrosine kinase receptor ptk3. Southern blots revealed identical hybridization patterns in both sex.
基金This work was supported by Natural Sciences Foundation of Guangdong Province (No. 0409078)Natural Sciences Foundation from the Education Department of Guangdong Province (No. z02051).
文摘Alternative splicing is a major contributor to genomic complexity and proteome diversity, yet the analysis of alternative splicing for the sequence containing nucleotide binding site and leucine-rich repeats (NBS-LRR) domain has not been explored in rice (Oryza sativa L.). Hidden Markov model (HMM) searches were performed for NBS-LRR domain. 875 NBS-LRR-encoding sequences were obtained from the Institute for Genomic Research (TIGR). All of them were used to blast Knowledge-based Oryza Molecular Biological Encyclopaedia (KOME), TIGR rice gene index (TGI), and Universal Protein Resource (UniProt) to obtain homologous full-length cDNAs (FL-cDNAs), tentative consensus sequences, and protein sequences. Alternative splicing events were detected from genomic alignment of FL-cDNAs, tentative consensus sequences, and protein sequences, which provide valuable information on splice variants of genes. These sequences were aligned to the corresponding BAC sequences using the Spidey and Sim4 programs and each of the proteins was aligned by tBLASTn. Of the 875 NBS-LRR sequences, 119 (13.6%) sequences had alternative splicing where multiple FL-cDNAs, TGI sequences and proteins corresponded to the same gene. 71 intron retention events, 20 exon skipping events, 16 alternative termination events, 25 alternative initiation events, 12 alternative 5' splicing events, and 16 alternative 3' splicing events were identified. Most of these alternative splices were supported by two or more transcripts. The data sets are available at http://www.bioinfor.org. Furthermore, the bioinformatics analysis of splice boundaries showed that exon skipping and intron retention did not exhibit strong consensus. This implies a different regulation mechanism that guides the expression of splice isoforms. This article also presents the analysis of the effects of intron retention on proteins. The C-terminal regions of alternative proteins turned out to be more variable than the N-terminal regions. Finally, tissue distribution and protein localization of alternative splicing were explored. The largest categories of tissue distributions for alternative splicing were shoot and callus. More than one-thirds of protein localization for splice forms was plasma membrane and cytoplasm. All the NBS-LRR proteins for splice forms may have important function in disease resistance and activate downstream signaling pathways.
基金funded by Projects under the Major State Basic Research Development Program(G1999012009).
文摘Eight hundred and thirty eight base pair fragment of mitochondrial COI gene of wild and cultured populations (CP1, CP4, CP5 and CP6) of Fenneropenaeus chinensis was amplified and sequenced. The A, T, G and C contents of the sequence were 235bp(28.0%), 307bp(36.6%), 138bp(16.5%) and 158bp(18.9%), respectively. Furthermore, 556bp fragment of the sequence was used to discuss the phylogenetic relationship among 14 Penaeidae species using Alpheus armillatus as the outgroup. From the molecular phylogenetic tree constructed by neighbor-joining method, we obtained three large shrimp groups:Farfantepenaeus, Litopenaeus and Fenneropenaeus group. The results also indicated that there were a closer genetic relationships between F. aztecus and F. paulensis, L. schmitti and L. setiferus, F. indicus and F. merguiensis, and the genus Farfantepenaeus was closer to Litopenaeus.
基金National Department Public Benefit Research Foundation (201103032)Pathogens Network Monitoring Technology Research (2008ZX10004-008)
文摘In recent years (2007 to 2011), although the overall number of rabies cases in China has decreased, there is evidence of emerging or re-emerging cases in regions without previous rabies cases or with low incidence of rabies. To investigate the origin and the factors affecting the spread of rabies in China, specimens were collected from 2007 to 2011 from provinces with emerging and re-emerging cases and tested for the presence of the rabies virus. Positive specimens were combined with sequences from GenBank to perform comparisons of homology and functional sites, and to carry out phylogenetic analyses. Out of these regions, five provinces had 9 positive specimens from canine and cattle, and 34 canine or human specimens were obtained from previously high-incidence provinces. Complete sequences of G gene were obtained for these samples. Homology of the sequences of these 43 specimens was 87%-100% at the nucleotide level and 93.7% -100% at the amino acid level. These G gene sequences were combined with reference sequence from GenBank and used to construct a phylogenetic tree. The results showed that 43 specimens were all assigned to China clade I and clade II, with all specimens from emerging and re-emerging areas placed within clade I. Specimens isolated from Shanxi and Inner Mongolia in 2011 were distinct from previously-isolated local strains and had closer homology to strains from Hebei, Beijing and Tianjin whereas new isolates from Shanghai were tightly clustered with strains isolated in the 1990s. Finally, Shaanxi isolates were clustered with strains from adjacent Sichuan. Our results suggest that the rabies cases in emerging and re-emerging areas in China in the last 5 years are a consequence of the epidemic spreading from of neighboring provinces and regions experiencing a serious epidemic of rabies.
文摘East Lake(Lake Donghu),located in Wuhan,China,is a typical city freshwater lake that has been experiencing eutrophic conditions and algal blooming during recent years.Marine and fresh water are considered to contain a large number of viruses.However,little is known about their genetic diversity because of the limited techniques for culturing viruses.In this study,we conducted a viral metagenomic analysis using a high-throughput sequencing technique with samples collected from East Lake in Spring,Summer,Autumn,and Winter.The libraries from four samples each generated 234,669,71,837,12,820,and 34,236 contigs(>90 bp each),respectively.The genetic structure of the viral community revealed a high genetic diversity covering 23 viral families,with the majority of contigs homologous to DNA viruses,including members of Myoviridae,Podoviridae,Siphoviridae,Phycodnaviridae,and Microviridae,which infect bacteria or algae,and members of Circoviridae,which infect invertebrates and vertebrates.The highest viral genetic diversity occurred in samples collected in August,then December and June,and the least diversity in March.Most contigs have low-sequence identities with known viruses.PCR detection targeting the conserved sequences of genes(g20,psbA,psbD,and DNApol)of cyanophages further confirmed that there are novel cyanophages in the East Lake.Our viral metagenomic data provide the first preliminary understanding of the virome in one freshwater lake in China and would be helpful for novel virus discovery and the control of algal blooming in the future.
基金Supported by the National Basic Research Program of China (973 Program) (No. 2006CB101804)the National Natural Science Foundation of China (No. 30972245)Public Industry (Agriculture) Specific Research Program (No. 200803012)
文摘Acting as one of the pattern recognition receptors (PRRs), C-type lectin is believed to mediate pathogen recognition and plays an important role in the clearance of pathogens as part of the innate immune system. In this work, a novel C-type lectin gene (named LvLecl) was cloned from the shrimp Litopenaeus vannamei, The ORF of LvLecl is 510 bp, encoding 169 amino acids. The deduced amino acid sequence contains a putative signal peptide of 19 amino acids at the N-terminal and a carbohydrate recognition domain (CRD) at the C-terminal. LvLecl was mainly expressed in the hepatopancreas. Real-time PCR analysis indicated that the level of LvLecl transcripts significantly changed in the hepatopancreas after the shrimp were artificially challenged with LPS, Micrococcus lysodeikticus and white spot syndrome virus (WSSV). RNAi-based silencing of LvLecl resulted in increases in mortality when the shrimp were challenged with WSSV, and the median lethal time was reduced compared with controls. Although there was no characteristic "EPN" (Glu-Pro-Ser) or "QPD" (Gin-Pro-Asp) motif, the recombinant LvLecl, expressed in Escherichia coli BL21 (DE3), could also agglutinate M. lysodeikticus and Vibrio anguillarum. The agglutinating activities were calcium-dependent and could be inhibited by D-mannose, D-glucose, D-galactose and N-Acetyl-D-mannose. These results suggest that LvLecl might be involved in the immune response against WSSV and bacterial infections and contribute to non-self recognition as a pattern recognition receptor in the innate immune system of the shrimp L. vannamei.
文摘Helicobacter pylori (H. pylori) virulence factors pro- mote the release of various chemoattractants/inflam- matory mediators, including mainly the neutrophil- attractant chemokine interleukin-8 and neutrophil- activating protein (NAP), involved in H. pylor/-induced gastric pathologies. Co-administration of Chios mastic gum (CMG), which inhibits H. pylor/NAP, with an H. pylori eradication regimen might add clinical benefits against H. pylori-related gastric pathologies, but pos- sibly not CMG as main therapy. Although H. pylori NAP and other H. pylori-related cytotoxins [i.e., vaculating cytotoxin (VacA)] appear to play a major role in gener- ating and maintaining the H. pylori-associated gastric inflammatory response and H. pylor/NAP is a promising vaccine candidate against H. pylori infection (H. pylori-1), concerns regarding its potential drawbacks, particularly neurogenic ones, due to possible cross- mimicry, should be considered. Possible cross-mimicry between H. p, vlor/ NAP and/or bacterial aquaporin (AQP) and neural tissues may be associated with the anti-AQP-4 antibody-related neural damage in multiple sclerosis (MS)/neuromyelitis optica patients. Moreover, the sequence homology found between H. pylori VacA and human Na+/K+-ATPase A subunit suggests that antibodies to VacA involve ion channels in abaxonal Schwann cell plasmalemma resulting in demyelination in some patients. A series of factors have been im- plicated in inducing blood-brain barrier (BBB) disrup- tion, including inflammatory mediators (e.g., cytokines and chemokines induced by H. pylor/-I) and oxidative stress. BBB disruption permits access of AQP4-specific antibodies and T lymphocytes to the central nervous system, thereby playing a major role in multiple sclero- sis pathogenesis. Relative studies show a strong asso- ciation between H. pylori-I and MS. H. pylor/-I induces humoral and cellular immune responses that, owing to the sharing of homologous epitopes (molecular mim- icry), cross-react with components of nerves, thereby contributing and perpetuating neural tissue damage. Finally, H. pylori NAP also plays a possible pathoge- netic role in both gastric and colon oncogenesis.
文摘Recent transcription profiling studies have revealed an unexpectedly large proportion of antisense transcripts in eukaryotic genomes. These antisense genes seem to regulate gene expression by interacting with sense genes. Previ- ous studies have focused on the non-coding antisense genes, but the possible regulatory role of the antisense protein is poorly understood. In this study, we found that a protein encoded by the antisense gene ADF1 acts as a transcription suppressor, regulating the expression of sense gene MDF1 in Saccharomyces cerevisiae. Based on the evolutionary, ge- netic, cytological and biochemical evidence, we show that the protein-coding sense gene MDF1 most likely originated de novo from a previously non-coding sequence and can significantly suppress the mating efficiency of baker's yeast in rich medium by binding MATa2 and thus promote vegetative growth. These results shed new light on several im- portant issues, including a new sense-antisense interaction mechanism, the de novo origination of a functional gene, and the regulation of yeast mating pathway.
文摘The complex transformation of a tadpole to a frogduring amphibian development is under the control of thyroid hormone (T3). T3 is known to regulate gene transcription through its nuclear receptors. We have previouslyisolated many genes which are up-regulated by T3 in theintestine of Xenopus laevis tadpoles. We have now cloneda full- length cDNA for one such gene (IU12). Sequenceanalysis shows that the IU12 cDNA encodes a plasmamembrane protein with 12 transmembrane domains andhomologous to a mammalian gene associated with cell activation and organ development. Similarly, we have foundthat IU12 is activated during intestinal remodeling whenboth cell death and proliferation take place. Furthermore,IU12 is an early T3-response gene and its expression in theintestine during T3-induced metamorphosis mimics thatduring normal development. These results argue for a roleof IU12 in the signal transduction pathways leading to intestinal metamorphosis.