The term “microgravity” is used to describe the “weightlessness” or “zero-g” circumstances that can only be found in space beyond earth’s atmosphere. Rhodobacter sphaeroides is a gram-negative purple phototroph...The term “microgravity” is used to describe the “weightlessness” or “zero-g” circumstances that can only be found in space beyond earth’s atmosphere. Rhodobacter sphaeroides is a gram-negative purple phototroph, used as a model organism for this study due to its genomic complexity and metabolic versatility. Its genome has been completely sequenced, and profiles of the differential gene expression under aerobic, semi-aerobic, and photosynthetic conditions were examined. In this study, we hypothesized that R. sphaeroides will show altered growth characteristics, morphological properties, and gene expression patterns when grown under simulated microgravity. To test that, we measured the optical density and colony-forming units of cell cultures grown under both microgravity and normal gravity conditions. Differences in the cell morphology were observed using scanning electron microscopy (SEM) images by measuring the length and the surface area of the cells under both conditions. Furthermore, we also identified homologous genes of R. spheroides using the differential gene expression study of Acidovorax under microgravity in our laboratory. Growth kinetics results showed that R. sphaeroides cells grown under microgravity experience a shorter log phase and early stationary phase compared to the cells growing under normal gravity conditions. The length and surface area of the cells under microgravity were significantly higher confirming that bacterial cells experience altered morphological features when grown under microgravity conditions. Differentially expressed homologous gene analysis indicated that genes coding for several COG and GO functions, such as metabolism, signal-transduction, transcription, translation, chemotaxis, and cell motility are differentially expressed to adapt and survive microgravity.展开更多
A 1440bp open-reading frame encoding D-hydantoinase from Pseudomonas putida YZ-26 was cloned and sequenced（ GenBank AY387829）. The DNA fragment was inserted into Nde and BamHI sites of vector pET-3a, yielding a reco...A 1440bp open-reading frame encoding D-hydantoinase from Pseudomonas putida YZ-26 was cloned and sequenced（ GenBank AY387829）. The DNA fragment was inserted into Nde and BamHI sites of vector pET-3a, yielding a recombinant plasmid, pET-HDT. After being transferred into the host strain, the artificial strain, pET-HDT/ E. coli BL21 can express the D-hydantoinase as the soluble form in the Lura-Bertani medium without addition of any inducers. The activity of the enzyme toward substrate DL-hydantoin can reach 3000-4000 IU per cells from one-liter bacterial culture incubated at 30 ℃ for 10-12 h. By the comparison of amino acid sequence homology, hydrophobic residues analysis and secondary structure prediction, it was found that D-hydantoinase reported herein is quite similar to that from Pseudomonas putdia CCRC12857, and alike to that from Pseudomonas putdia DSM84 or other bacteria. A rapid and efficient purification procedure of the enzyme was performed by a three-step procedure： ammonium sulfate fractionation, phenyl Sepharose hydrophobic interaction chromatography and Sephacryl S-200 gel filtration. The molecular mass of the monomeric enzyme is 52042 Da as determined by MALDI-TOF mass spectrometry.展开更多
The bglS gene encoding endo-1,3-1,4-β-glucanase from Bacillus subtil＆ was cloned and sequenced in this study. The bglS expression cassette, including PGK1 promoter, bglS gene fused to the signal sequence of the yeas...The bglS gene encoding endo-1,3-1,4-β-glucanase from Bacillus subtil＆ was cloned and sequenced in this study. The bglS expression cassette, including PGK1 promoter, bglS gene fused to the signal sequence of the yeast mating pheromone a-factor （MFals）, and ADH1 terminator with G418-resistance as the selected marker, was constructed. Then one of the PEP4 allele of Saccharomyces cerevisiae WZ65 strain was replaced by bglS expression cassette using chromosomal integration of polymerase chain reaction （PCR）-mediated homologous recombination, and the bglS gene was expressed simultaneously. The recombinant strain S. cerevisiae （SC-βG） was preliminarily screened by the clearing hydrolysis zone formed after the barley β-glucan was hydrolyzed in the plate and no proteinase A （PrA） activity was measured in fermenting liquor. The results of PCR analysis of genome DNA showed that one of the PEP4 allele had been replaced and bglS gene had been inserted into the locus of PEP4 gene in recombinant strains. Different endo-1,3-1,4-β-glucanase assay methods showed that the recombinant strain SC-βG had high endo-1,3-1,4-β-glucanase expression level with the maximum of 69.3 U/（h·ml） after 60 h of incubation. Meanwhile, the Congo Red method was suitable for the determination of endo-1,3-1,4-β-glucanase activity during the actual brewing process. The current research implies that the constructed yeast strain could be utilized to improve the industrial brewing property of beer.展开更多
The presence of DNA homologues corresponding to verc203 (vernalization-related cDNA clone) was investigated by molecular hybridization techniques. The genes were detected in 16 plant species that cover 12 subclasses o...The presence of DNA homologues corresponding to verc203 (vernalization-related cDNA clone) was investigated by molecular hybridization techniques. The genes were detected in 16 plant species that cover 12 subclasses of the Takhtajan system of angiosperms classification including diverse model species. The results of Southern blot analysis showed a low copy number of this gene existed in rice, wheat, barley and Arabidopsis. The hybridization result of PCR products demonstrated the conservation of the gene corresponding to ver203 in diverse plants. The phylogenetic tree of the ver203 gene in tested plants was supported by evolution relationship of species. The ver203 gene expressed in a vernalized plumule winter wheat, instead of the root. And the endosperm before the treatment was essential for the ver203 expression during vernalization in wheat. In Arabidopsis thaliana, the pattern of expression showed that the gene corresponding to ver203 was expressed at low temperature for 14 days. Gibberellin(GA3) may accelerate the expression of ver203 gene in Arabidopsis exposed to low temperature. However, it could not replace vernalization treatment to initiate the gene expression.展开更多
Even though the nitrate assimilation operon has been extensively studied in Phormidium laminosum, some aspects still remain unclear. The genetic manipulation of this cyanobacterium is problematic that hinders the eluc...Even though the nitrate assimilation operon has been extensively studied in Phormidium laminosum, some aspects still remain unclear. The genetic manipulation of this cyanobacterium is problematic that hinders the elucidation of further aspects of nitrogen metabolism. To circumvent this, Thermosynechococcus elongatus BP-1 was selected as a surrogate host and its nirA gene was substituted by the homologous gene of P. laminosum. This process, based on Long Flanking Homology Polymerase Chain Reaction and the natural competence of T. elongatus BP-1, required an intermediate T. elongatus BP-1 ΔnirA::kat mutant, which carries a gene encoding a thermostable kanamycin nucleotidyl transferase in place of nirA_Te. In the presence of nirA_Pl, nirA defective mutants of T. elongatus BP-1 recovered the ability to grow with nitrate as the sole nitrogen source, and showed a phenotype similar to that observed in wild-type cells. The procedure could be useful to substitute other genes from T. elongatus BP-1 with the homologues from P. laminosum in order to study this particular operon. Furthermore, it may be used as a general tool to explore phenotypic changes due to the exchange of a single gene between cyanobacteria.展开更多
In order to adapt to the low temperature environment,organisms transmit excitement to the central system through the thermal sensing system,which is a classic reflex reaction.The cold receptor GLR-3 perceives cold and...In order to adapt to the low temperature environment,organisms transmit excitement to the central system through the thermal sensing system,which is a classic reflex reaction.The cold receptor GLR-3 perceives cold and produces cold avoidance behavior through peripheral sensory neurons ASER.In order to further understand the gene encoding of the cold sensing glr-3 gene and the evolution of its homologous gene group function and protein function,the nucleotide sequence and amino acid sequence of the glr-3 gene and its homologous gene in 24 species were obtained and compared.By clustering with the GRIK2 gene sequence of Rana chensinensis,the bioinformatics method was used to predict and sequence analyze the change of gene,evolution rate,physical and chemical properties of protein,glycosylation sites,phosphorylation sites,secondary structure and tertiary structure of protein.The analysis results show that the glr-3 gene and its homologous gene have obvious positive selection effect.The protein prediction analysis showed that the glr-3 gene and its homologous genes encoded proteins in these 25 species were hydrophilic proteins,and the proportion of side chains of aliphatic amino acids was high.The transmembrane helix was widespread and there were more N-glycosylation sites and O-glycosylation sites.The protein phosphorylation sites encoded were serine,threonine and tyrosine phosphorylation sites.Secondary structure prediction showed that the secondary structure units of the encoded protein wereα-helix,β-turn,random coil and extended chain,and the proportion ofα-helix was the largest.This study provides useful information on the evolution and function of the cold sensing gene glr-3 and its homologous genes.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
TH-98 isolate of transmissible gastroenteritis virus (TGEV) was propagated and harvested on swine testicle (ST) monolayer cell. Two pairs of primers were designed to amplify S gene by RT-PCR according to the published...TH-98 isolate of transmissible gastroenteritis virus (TGEV) was propagated and harvested on swine testicle (ST) monolayer cell. Two pairs of primers were designed to amplify S gene by RT-PCR according to the published sequence of TGEV'S gene cDNA with Oligo version 4.1 and DNasis software. The products of PCR were named Sa and Sb, of 2.3 kb and 2.1 kb respectively. Sa was inserted in EcoR I and Kpn I sites after Sb was cloned in Kpn I and Pst I multiple cloning sites of the same pUC18 plasmid. The recombinant pUC-S plasmid was identified and analyzed by corresponding restriction endonuclease and nested PCR on the basis of the genetic sites of S gene and pUC18 plasmid, which was identified as S gene of TGEV. Recombinant pUC-S was sequenced and analyzed in comparison with the other strains. Gene sequence comparison indicated that TH-98 shared 99, 97, 98, 97 and 94% identities with Purdue-115(US), Miller(US), TO14(Japan), FS772(British), 96-1933(British), respectively, their deduced amino acid homology was 99, 97, 97, 96 and 93% correspondingly. In addition, the analysis report verified that pUC-S owned a complete open reading frame (ORF) including initiation codon, signal sequences, remaining sequences and termination codon as well. Therefore, the results affirmed that S gene of TGEV TH-98 was extremely conservative.展开更多
Ras homolog enriched in brain(Rheb) is a small GTPase that activates mammalian target of rapamycin complex 1(mTORC1).Previous studies have shown that constitutively active Rheb can enhance the regeneration of sensory ...Ras homolog enriched in brain(Rheb) is a small GTPase that activates mammalian target of rapamycin complex 1(mTORC1).Previous studies have shown that constitutively active Rheb can enhance the regeneration of sensory axons after spinal cord injury by activating downstream effectors of mTOR.S6K1 and4E-BP1 are important downstream effectors of mTORC1.In this study,we investigated the role of Rheb/mTOR and its downstream effectors S6K1 and 4E-BP1in the protection of retinal ganglion cells.We transfected an optic nerve crush mouse model with adeno-associated viral 2-mediated constitutively active Rheb and observed the effects on retinal ganglion cell survival and axon regeneration.We found that overexpression of constitutively active Rheb promoted survival of retinal ganglion cells in the acute(14 days) and chronic(21 and 42 days) stages of injury.We also found that either co-expression of the dominant-negative S6K1mutant or the constitutively active 4E-BP1 mutant together with constitutively active Rheb markedly inhibited axon regeneration of retinal ganglion cells.This suggests that mTORC1-mediated S6K1 activation and 4E-BP1 inhibition were necessary components for constitutively active Rheb-induced axon regeneration.However,only S6K1 activation,but not 4E-BP1 knockdown,induced axon regeneration when applied alone.Furthermore,S6K1 activation promoted the survival of retinal ganglion cells at 14 days post-injury,whereas 4E-BP1 knockdown unexpectedly slightly decreased the survival of retinal ganglion cells at 14 days postinjury.Ove rexpression of constitutively active 4E-BP1 increased the survival of retinal ganglion cells at 14 days post-injury.Likewise,co-expressing constitutively active Rheb and constitutively active 4E-BP1 markedly increased the survival of retinal ganglion cells compared with overexpression of constitutively active Rheb alone at 14 days post-injury.These findings indicate that functional 4E-BP1 and S6K1 are neuroprotective and that 4E-BP1 may exert protective effects through a pathway at least partially independent of Rhe b/mTOR.Together,our results show that constitutively active Rheb promotes the survival of retinal ganglion cells and axon regeneration through modulating S6K1 and 4E-BP1 activity.Phosphorylated S6K1 and 4E-BP1 promote axon regeneration but play an antagonistic role in the survival of retinal ganglion cells.展开更多
To examine phosphatase and tensin homology deleted in chromosome 10 (PTEN),hypoxia-inducible factor-1 alpha (HIF-1 alpha) gene expressions and their relation to vascular endothelial growth factor(VEGF) protein express...To examine phosphatase and tensin homology deleted in chromosome 10 (PTEN),hypoxia-inducible factor-1 alpha (HIF-1 alpha) gene expressions and their relation to vascular endothelial growth factor(VEGF) protein expression in the patients with human colorectal adenomas and adenocarcinomas.Methods The expression of PTEN,HIF-1 alpha gene was detected by using in situ hybridization,and the VEGF expression levels by immunohistochemistry in colorectal adenomas and primary colorectal adenocarcinoma.Results Strong expression of HIF-1 alpha was detectable in the majority of colorectal dadenocarcinoma,particularly surrounding areas of necrosis in adenocarcinoma.PTEN,HIF-1 alpha mRNA and VEGF protein were positive in 51.6%,67.7% and 59.7% respectively in 62 cases of adenocarcinomas,and 77.8%,44.4% and 33.3% respectively in 18 cases of adenomas.The positive rate of VEGF was higher in the patients with colorectal adenocarcinomas than that in those with adenomas,whereas that of PTEN mRNA was contrary.HIF-1 mRNA expression was correlated significantly with lymph node metastasis,liver metastasis,Duke’s stage and recurrence.During colorectal tumor progression,the expression of HIF-1 alpha mRNA was positively correlated with the VEGF protein expression (χ2= 4.751 ,P<0.05),but negatively with the PTEN mRNA expression(χ2=21.84,P<0.01).Conclusion The absence or low expression of PTEN and the increased levels of HIF-1α and VEGF may paly an important role in carcinogenesis and progression of colorectal carcinoma.These results suggest that VEGF upregulated by HIF-1 alpha gene may be involved in angiogenesis of colorectal adenocarcinoma.4 refs,1 tab.展开更多
文摘The term “microgravity” is used to describe the “weightlessness” or “zero-g” circumstances that can only be found in space beyond earth’s atmosphere. Rhodobacter sphaeroides is a gram-negative purple phototroph, used as a model organism for this study due to its genomic complexity and metabolic versatility. Its genome has been completely sequenced, and profiles of the differential gene expression under aerobic, semi-aerobic, and photosynthetic conditions were examined. In this study, we hypothesized that R. sphaeroides will show altered growth characteristics, morphological properties, and gene expression patterns when grown under simulated microgravity. To test that, we measured the optical density and colony-forming units of cell cultures grown under both microgravity and normal gravity conditions. Differences in the cell morphology were observed using scanning electron microscopy (SEM) images by measuring the length and the surface area of the cells under both conditions. Furthermore, we also identified homologous genes of R. spheroides using the differential gene expression study of Acidovorax under microgravity in our laboratory. Growth kinetics results showed that R. sphaeroides cells grown under microgravity experience a shorter log phase and early stationary phase compared to the cells growing under normal gravity conditions. The length and surface area of the cells under microgravity were significantly higher confirming that bacterial cells experience altered morphological features when grown under microgravity conditions. Differentially expressed homologous gene analysis indicated that genes coding for several COG and GO functions, such as metabolism, signal-transduction, transcription, translation, chemotaxis, and cell motility are differentially expressed to adapt and survive microgravity.
基金Supported by the Natural Science Foundation of Shanxi Province(No.20031042).
文摘A 1440bp open-reading frame encoding D-hydantoinase from Pseudomonas putida YZ-26 was cloned and sequenced（ GenBank AY387829）. The DNA fragment was inserted into Nde and BamHI sites of vector pET-3a, yielding a recombinant plasmid, pET-HDT. After being transferred into the host strain, the artificial strain, pET-HDT/ E. coli BL21 can express the D-hydantoinase as the soluble form in the Lura-Bertani medium without addition of any inducers. The activity of the enzyme toward substrate DL-hydantoin can reach 3000-4000 IU per cells from one-liter bacterial culture incubated at 30 ℃ for 10-12 h. By the comparison of amino acid sequence homology, hydrophobic residues analysis and secondary structure prediction, it was found that D-hydantoinase reported herein is quite similar to that from Pseudomonas putdia CCRC12857, and alike to that from Pseudomonas putdia DSM84 or other bacteria. A rapid and efficient purification procedure of the enzyme was performed by a three-step procedure： ammonium sulfate fractionation, phenyl Sepharose hydrophobic interaction chromatography and Sephacryl S-200 gel filtration. The molecular mass of the monomeric enzyme is 52042 Da as determined by MALDI-TOF mass spectrometry.
基金the National Hi-Tech Research and Develop-ment Program (863) of China (No. 2007AA10Z315)the Natural Science Foundation of Zhejiang Province, China (No. Z304076)
文摘The bglS gene encoding endo-1,3-1,4-β-glucanase from Bacillus subtil＆ was cloned and sequenced in this study. The bglS expression cassette, including PGK1 promoter, bglS gene fused to the signal sequence of the yeast mating pheromone a-factor （MFals）, and ADH1 terminator with G418-resistance as the selected marker, was constructed. Then one of the PEP4 allele of Saccharomyces cerevisiae WZ65 strain was replaced by bglS expression cassette using chromosomal integration of polymerase chain reaction （PCR）-mediated homologous recombination, and the bglS gene was expressed simultaneously. The recombinant strain S. cerevisiae （SC-βG） was preliminarily screened by the clearing hydrolysis zone formed after the barley β-glucan was hydrolyzed in the plate and no proteinase A （PrA） activity was measured in fermenting liquor. The results of PCR analysis of genome DNA showed that one of the PEP4 allele had been replaced and bglS gene had been inserted into the locus of PEP4 gene in recombinant strains. Different endo-1,3-1,4-β-glucanase assay methods showed that the recombinant strain SC-βG had high endo-1,3-1,4-β-glucanase expression level with the maximum of 69.3 U/（h·ml） after 60 h of incubation. Meanwhile, the Congo Red method was suitable for the determination of endo-1,3-1,4-β-glucanase activity during the actual brewing process. The current research implies that the constructed yeast strain could be utilized to improve the industrial brewing property of beer.
文摘The presence of DNA homologues corresponding to verc203 (vernalization-related cDNA clone) was investigated by molecular hybridization techniques. The genes were detected in 16 plant species that cover 12 subclasses of the Takhtajan system of angiosperms classification including diverse model species. The results of Southern blot analysis showed a low copy number of this gene existed in rice, wheat, barley and Arabidopsis. The hybridization result of PCR products demonstrated the conservation of the gene corresponding to ver203 in diverse plants. The phylogenetic tree of the ver203 gene in tested plants was supported by evolution relationship of species. The ver203 gene expressed in a vernalized plumule winter wheat, instead of the root. And the endosperm before the treatment was essential for the ver203 expression during vernalization in wheat. In Arabidopsis thaliana, the pattern of expression showed that the gene corresponding to ver203 was expressed at low temperature for 14 days. Gibberellin(GA3) may accelerate the expression of ver203 gene in Arabidopsis exposed to low temperature. However, it could not replace vernalization treatment to initiate the gene expression.
文摘Even though the nitrate assimilation operon has been extensively studied in Phormidium laminosum, some aspects still remain unclear. The genetic manipulation of this cyanobacterium is problematic that hinders the elucidation of further aspects of nitrogen metabolism. To circumvent this, Thermosynechococcus elongatus BP-1 was selected as a surrogate host and its nirA gene was substituted by the homologous gene of P. laminosum. This process, based on Long Flanking Homology Polymerase Chain Reaction and the natural competence of T. elongatus BP-1, required an intermediate T. elongatus BP-1 ΔnirA::kat mutant, which carries a gene encoding a thermostable kanamycin nucleotidyl transferase in place of nirA_Te. In the presence of nirA_Pl, nirA defective mutants of T. elongatus BP-1 recovered the ability to grow with nitrate as the sole nitrogen source, and showed a phenotype similar to that observed in wild-type cells. The procedure could be useful to substitute other genes from T. elongatus BP-1 with the homologues from P. laminosum in order to study this particular operon. Furthermore, it may be used as a general tool to explore phenotypic changes due to the exchange of a single gene between cyanobacteria.
基金This study was funded by Heilongjiang Province College Students'Innovation Training Program of Northeast Forestry University(S202010225095).
文摘In order to adapt to the low temperature environment,organisms transmit excitement to the central system through the thermal sensing system,which is a classic reflex reaction.The cold receptor GLR-3 perceives cold and produces cold avoidance behavior through peripheral sensory neurons ASER.In order to further understand the gene encoding of the cold sensing glr-3 gene and the evolution of its homologous gene group function and protein function,the nucleotide sequence and amino acid sequence of the glr-3 gene and its homologous gene in 24 species were obtained and compared.By clustering with the GRIK2 gene sequence of Rana chensinensis,the bioinformatics method was used to predict and sequence analyze the change of gene,evolution rate,physical and chemical properties of protein,glycosylation sites,phosphorylation sites,secondary structure and tertiary structure of protein.The analysis results show that the glr-3 gene and its homologous gene have obvious positive selection effect.The protein prediction analysis showed that the glr-3 gene and its homologous genes encoded proteins in these 25 species were hydrophilic proteins,and the proportion of side chains of aliphatic amino acids was high.The transmembrane helix was widespread and there were more N-glycosylation sites and O-glycosylation sites.The protein phosphorylation sites encoded were serine,threonine and tyrosine phosphorylation sites.Secondary structure prediction showed that the secondary structure units of the encoded protein wereα-helix,β-turn,random coil and extended chain,and the proportion ofα-helix was the largest.This study provides useful information on the evolution and function of the cold sensing gene glr-3 and its homologous genes.
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TH-98 isolate of transmissible gastroenteritis virus (TGEV) was propagated and harvested on swine testicle (ST) monolayer cell. Two pairs of primers were designed to amplify S gene by RT-PCR according to the published sequence of TGEV'S gene cDNA with Oligo version 4.1 and DNasis software. The products of PCR were named Sa and Sb, of 2.3 kb and 2.1 kb respectively. Sa was inserted in EcoR I and Kpn I sites after Sb was cloned in Kpn I and Pst I multiple cloning sites of the same pUC18 plasmid. The recombinant pUC-S plasmid was identified and analyzed by corresponding restriction endonuclease and nested PCR on the basis of the genetic sites of S gene and pUC18 plasmid, which was identified as S gene of TGEV. Recombinant pUC-S was sequenced and analyzed in comparison with the other strains. Gene sequence comparison indicated that TH-98 shared 99, 97, 98, 97 and 94% identities with Purdue-115(US), Miller(US), TO14(Japan), FS772(British), 96-1933(British), respectively, their deduced amino acid homology was 99, 97, 97, 96 and 93% correspondingly. In addition, the analysis report verified that pUC-S owned a complete open reading frame (ORF) including initiation codon, signal sequences, remaining sequences and termination codon as well. Therefore, the results affirmed that S gene of TGEV TH-98 was extremely conservative.
基金National Natural Science Foundation of China,Nos.82070967,81770930the Natural Science Foundation of Hunan Province,No.2020jj4788 (all to BJ)。
文摘Ras homolog enriched in brain(Rheb) is a small GTPase that activates mammalian target of rapamycin complex 1(mTORC1).Previous studies have shown that constitutively active Rheb can enhance the regeneration of sensory axons after spinal cord injury by activating downstream effectors of mTOR.S6K1 and4E-BP1 are important downstream effectors of mTORC1.In this study,we investigated the role of Rheb/mTOR and its downstream effectors S6K1 and 4E-BP1in the protection of retinal ganglion cells.We transfected an optic nerve crush mouse model with adeno-associated viral 2-mediated constitutively active Rheb and observed the effects on retinal ganglion cell survival and axon regeneration.We found that overexpression of constitutively active Rheb promoted survival of retinal ganglion cells in the acute(14 days) and chronic(21 and 42 days) stages of injury.We also found that either co-expression of the dominant-negative S6K1mutant or the constitutively active 4E-BP1 mutant together with constitutively active Rheb markedly inhibited axon regeneration of retinal ganglion cells.This suggests that mTORC1-mediated S6K1 activation and 4E-BP1 inhibition were necessary components for constitutively active Rheb-induced axon regeneration.However,only S6K1 activation,but not 4E-BP1 knockdown,induced axon regeneration when applied alone.Furthermore,S6K1 activation promoted the survival of retinal ganglion cells at 14 days post-injury,whereas 4E-BP1 knockdown unexpectedly slightly decreased the survival of retinal ganglion cells at 14 days postinjury.Ove rexpression of constitutively active 4E-BP1 increased the survival of retinal ganglion cells at 14 days post-injury.Likewise,co-expressing constitutively active Rheb and constitutively active 4E-BP1 markedly increased the survival of retinal ganglion cells compared with overexpression of constitutively active Rheb alone at 14 days post-injury.These findings indicate that functional 4E-BP1 and S6K1 are neuroprotective and that 4E-BP1 may exert protective effects through a pathway at least partially independent of Rhe b/mTOR.Together,our results show that constitutively active Rheb promotes the survival of retinal ganglion cells and axon regeneration through modulating S6K1 and 4E-BP1 activity.Phosphorylated S6K1 and 4E-BP1 promote axon regeneration but play an antagonistic role in the survival of retinal ganglion cells.
文摘To examine phosphatase and tensin homology deleted in chromosome 10 (PTEN),hypoxia-inducible factor-1 alpha (HIF-1 alpha) gene expressions and their relation to vascular endothelial growth factor(VEGF) protein expression in the patients with human colorectal adenomas and adenocarcinomas.Methods The expression of PTEN,HIF-1 alpha gene was detected by using in situ hybridization,and the VEGF expression levels by immunohistochemistry in colorectal adenomas and primary colorectal adenocarcinoma.Results Strong expression of HIF-1 alpha was detectable in the majority of colorectal dadenocarcinoma,particularly surrounding areas of necrosis in adenocarcinoma.PTEN,HIF-1 alpha mRNA and VEGF protein were positive in 51.6%,67.7% and 59.7% respectively in 62 cases of adenocarcinomas,and 77.8%,44.4% and 33.3% respectively in 18 cases of adenomas.The positive rate of VEGF was higher in the patients with colorectal adenocarcinomas than that in those with adenomas,whereas that of PTEN mRNA was contrary.HIF-1 mRNA expression was correlated significantly with lymph node metastasis,liver metastasis,Duke’s stage and recurrence.During colorectal tumor progression,the expression of HIF-1 alpha mRNA was positively correlated with the VEGF protein expression (χ2= 4.751 ,P<0.05),but negatively with the PTEN mRNA expression(χ2=21.84,P<0.01).Conclusion The absence or low expression of PTEN and the increased levels of HIF-1α and VEGF may paly an important role in carcinogenesis and progression of colorectal carcinoma.These results suggest that VEGF upregulated by HIF-1 alpha gene may be involved in angiogenesis of colorectal adenocarcinoma.4 refs,1 tab.
