The cytokinesis process of generative cells in Amaryllis vitiata Ait. wasexamined with electron microscopy. Investigation of 14 pollen tubes showed that 70percent of the generative cells were divided by a cell plate, ...The cytokinesis process of generative cells in Amaryllis vitiata Ait. wasexamined with electron microscopy. Investigation of 14 pollen tubes showed that 70percent of the generative cells were divided by a cell plate, while the other, 30 percentshowed a cleavage furrow which occurred at the position where a cell plate should takeplace. The cell plate appeared at First as a subunit in late anaphase, which was assembledin the midzone of the phragmoplast and coalesced as one large continued unit in telophase.On the other hand, just in anaphase, as two identical chromosome masses were segregatedfrom each other, the plasma membrane of the generative cell were furrowing inside fromthe tWo sides in the interzonal region. In some instances, the cell was almost divided intotwo parts by the constriction furrow. The occurrence of cleavage seemed to be associatedwith the re-establishment of the nuclear envelope and the disorder of microtubular arrays,as well as the unusual behavior of the chromosomes.展开更多
Objective： To examine modulations caused by cyclooxygenase-2 （COX-2） inhibitors on altered microenvironments and overbalanced neurotransmitters in pilocarpine-induced epileptic status rats and to investigate possib...Objective： To examine modulations caused by cyclooxygenase-2 （COX-2） inhibitors on altered microenvironments and overbalanced neurotransmitters in pilocarpine-induced epileptic status rats and to investigate possible mechanisms. Methods： Celecoxib （a COX-2 inhibitor） was administered 45 min prior to pilocarpine administration. The effects of COX-2 inhibitors on mlPSCs （miniature GABAergic inhibitory postsynaptic currents） of CA3 pyramidal cells in the hippocampus were recorded. Expressions of COX-2, c-Fos, newly generated neurons, and activated microgliosis were analyzed by immunohistochemistry, and expressions of c^-subunit of y-amino butyric acid （GABAA） receptors and mitogen-activated protein kinase/extracellular signal-regulated protein kinase （MAPK/ERK） activity were detected by Western blotting. Results： Pretreatment with celecoxib showed protection against pilocarpine-induced seizures. Celecoxib prevented microglia activation in the hilus and inhibited the abnormal neurogenesis and astrogliosis in the hippocampus by inhibiting MAPK/ERK activity and c-Fos transcription. Celecoxib also up-regulated the expression of GABAA receptors. NS-398 （N-2-cyclohexyloxy-4-nitrophenyl-methanesulfonamide）, another COX-2 inhibitor, enhanced the frequency and decay time of mIPSCs. Conclusion： The COX-2 inhibitor celecoxib decreased neuronal excitability and prevented epileptogenesis in pilocarpine-induced status epilepticus rats. Celecoxib regulates synaptic reorganization by inhibiting astrogliosis and ectopic neurogenesis by attenuating MAPK/ERK signal activity, mediated by a GABAergic mechanism.展开更多
Objective To investigate the effect of interleukin-6(IL-6)on the human growth hormone(hGH)gene expression in a rat somatotropic pituitary cell line MtT/S.Methods The plasmids containing various lengths of hGH gene 5&#...Objective To investigate the effect of interleukin-6(IL-6)on the human growth hormone(hGH)gene expression in a rat somatotropic pituitary cell line MtT/S.Methods The plasmids containing various lengths of hGH gene 5'-promoter fragments were constructed.Stably transfected MtT/S cells were created by cotransfecting the above plasmids and pcDNA3.1(+)with DMRIE-C transfection reagent.After the administration of these cells with IL-6 and/or various inhibitors of signaling transduction pathways,the luciferase activities in MtT/S cells lysis were assayed to demonstrate the effects of IL-6 on hGH gene promoter activity and possibly involved mechanism.Results The 103 U/mL IL-6 stimulated GH secretion and synthesis,and promoted the 5'-promoter activity of GH gene in stably transfected MtT/SGL cells with the action of 1.69 times above the control.Among inhibitors of signaling transduction pathways,mitogen-activated protein kinase kinase(MAPKK/MEK)inhibitor PD98059(40 μmol/L)and p38 mitogen-activated protein kinase(MAPK)inhibitor SB203580(5 μmol/L)completely blocked the stimulatory effect of IL-6.Western blot analysis further confirmed the activation of phosphorylated MEK and p38 MAPK in MtT/SGL cells.Neither over-expression of Pit-1 nor inhibition of Pit-1 expression affected IL-6 induction of hGH promoter activity.A series of deletion constructs of hGH promoter were created to identify the DNA sequence that mediated the effect of IL-6.The results showed that the stimulatory effect of IL-6 was abolished following deletion of the-196 to-132 bp fragment.Conclusions IL-6 promotes GH secretion and synthesis by rat MtT/S somatotroph cells.The stimulatory effect of IL-6 on hGH gene promoter appears to require the activation of MEK and p38 MAPK,and a fragment of promoter sequence that spans the-196 to-132 bp of the gene,but may be unlinked with Pit-1 protein.展开更多
The dynamic distribution of phosphorylated Histone H3 on Ser10 (phospho-H3) in cells was investigated to determineits function during mitosis. Human breast adenocarcinoma cells MCF-7, and Chinese hamster cells CHO wer...The dynamic distribution of phosphorylated Histone H3 on Ser10 (phospho-H3) in cells was investigated to determineits function during mitosis. Human breast adenocarcinoma cells MCF-7, and Chinese hamster cells CHO were analyzedby indirect immunofluorescence staining with an antibody against phospho-H3. We found that the phosphorylationbegins at early prophase, and spreads throughout the chromosomes at late prophase. At metaphase, most of the phospho-H3 aggregates at the end of the condensed entity of chromosomes at equatorial plate. During anaphase and telophase,the fluorescent signal of phospho-H3 is detached from chromosomes into cytoplasm. At early anaphase, phospho-H3shows ladder bands between two sets of separated chromosome, and forms “sandwich-like structure” when the chro-mosomes condensed. With the cleavage progressing, the “ladders” of the histone contract into a bigger bright dot. Thenthe histone aggregates and some of compacted microtubules in the midbody region are composed into a “bar-like”complex to separate daughter cells. The daughter cells seal their plasma membrane along with the ends of the “bar”,inside which locates microtubules and modified histones, to finish the cytokinesis and keep the “bar complex” out of thecells. The specific distribution and kinetics of phospho-H3 in cytoplasm suggest that the modified histones may takepart in the formation of midbody and play a crucial role in cytokinesis.展开更多
Eutrophication has become a serious concern in many lakes, resulting in cyanobacterial blooms. However, the mechanism and pathways of cyanobacteria decline are less understood. To identify and define the growth and de...Eutrophication has become a serious concern in many lakes, resulting in cyanobacterial blooms. However, the mechanism and pathways of cyanobacteria decline are less understood. To identify and define the growth and decline of Microcystis blooms in Taihu Lake of China, and to illuminate the destination of surface floating blooms, we investigated the biomass distribution and variations in colony size, morphology, and floating velocity from October 2008 to September 2009. The results showed that the Microcystis bloom declined in response to biomass decrease, colony disaggregation, buoyancy reduction, and increased phytoplankton biodiversity, and these indicative parameters could be applied for recognition of the development phases of the bloom. Three major decline pathways were proposed to describe the bloom decline process, colony disaggregation （Pathway I）, colony settlement （Pathway II）, and cell lysis in colonies （Pathway III）. We proposed a strategy to define the occurrence and decline of Microcystis blooms, to evaluate the survival state under different stress conditions, and to indicate the efficiency of controlling countermeasures against algal blooms.展开更多
AIM： To investigate the possible mechanism by which hepatitis B virus X protein （HBx） mediates apoptosis of HepG2 cells. METHODS： HBx expression vector pcDNA3.1-X was transfected into HepG2 cells to establish an H...AIM： To investigate the possible mechanism by which hepatitis B virus X protein （HBx） mediates apoptosis of HepG2 cells. METHODS： HBx expression vector pcDNA3.1-X was transfected into HepG2 cells to establish an HBx high- expression cellular model as pcDNA3.1-X transfected group. The pcDNA3.1-X and pSilencer3.1-shHBX （HBx antagonist） were cotransfected into HepG2 cells to es- tablish an HBx low-expression model as RNAi group. Untransfected HepG2 cells and HepG2 cells transfected with negative control plasmid were used as controls. Apoptosis rate, the expression of Fas/FasL signaling pathway-related proteins and the phosphorylation lev- els of MLK3, MKK7 and JNKs, which are upstream molecules of death receptor pathways and belong to the family of mitogen-activated protein kinases （MAPKs）,were measured in each group RESULTS： Compared with HepG2 cell group and RNAi group, apoptosis rate, the expression of Fas and FasL proteins, and the activation of MLK3, MKK7 and 3NKs were increased in the pcDNA3.1-X transfected group. The activation of JNKs and expression of FasL protein were inhibited in the pcDNA3.1-X transfected group when treated with a known JNK inhibitor, SP600125. When authors treated pcDNA3.1-X transfected group with K252a, a known MLK3 inhibitor, the activation of MLK3, MKK7 and 3NKs as well as expression of FasL protein was inhibited. Furthermore, cell apoptosis rate was also significantly declined in the presence of K252a in the pcDNA3.1-X transfected group. CONCLUSION： HBx can induce HepG2 cell apoptosis via a novel active MLK3-MKK7-JNKs signaling module to upregulate FasL protein expression.展开更多
CDKs play key roles in controlling cell cycle progression in all eukaryotes. In plants, multiple CDKs are present,among which the best characterized CDKs are PSTAIRE CDKs. In this study, we carried out Western blot,im...CDKs play key roles in controlling cell cycle progression in all eukaryotes. In plants, multiple CDKs are present,among which the best characterized CDKs are PSTAIRE CDKs. In this study, we carried out Western blot,immunoelectron microscopy and antibody treatment with an anti-PSTAIRE monoclonal antibody to explore the subcellular localization and functions of PSTAIRE CDKs in Physarum polycephalum. The results of Western blot and immunoelectron microscopy showed that in P. polycephalum, a PSTAIRE CDK-like protein was 34 kD in molecular weight and located in both nuclei and cytoplasm. In nuclei, the protein was mainly associated with chromosomes and nucleoli. The expression of the PSTAIRE CDK-like protein in both the plasmodia and nuclei showed little fluctuation through the whole cell cycle. When treated with an anti-PSTAIRE monoclonal antibody at early S phase, the cells were arrested in S phase, and the mitotic onset of P. polycephalum was blocked for about 1 h when treated at early G2 phase.Our data indicated that the PSTAIRE CDK- like protein has a direct bearing on the mitosis.展开更多
Amitosis, different from mitosis, is a rare form of the proliferation of the cells. Most amitosis were observed in animal cells; only few of them were reported in plant cells. The cytological investigation in this stu...Amitosis, different from mitosis, is a rare form of the proliferation of the cells. Most amitosis were observed in animal cells; only few of them were reported in plant cells. The cytological investigation in this study demonstrated first time in Pelargonium zonale two different amitotic nuclear division ways： cleavage and constriction, in which no appearance of the visible chromosomes and no spindles were observed. After amitotic nuclear division the cytokinesis was also observed, in which the cytoplasm divided directly into two or more parts accompany with formation of two or more daughter cells. This study showed the genetic material may sometimes be unequally distributed between the daughter cells in amitosis, and the amitosis could lead to bi-, tri- and multinucleated cells. These new findings are discussed in regard to the nuclear amitotic process in polyploid cells which gives rise to smaller, viable nuclei in multinucleated cells with reduced numbers of genomes. It was suggested that amitosis could be a way of the division of the endoreduplicated cells.展开更多
文摘The cytokinesis process of generative cells in Amaryllis vitiata Ait. wasexamined with electron microscopy. Investigation of 14 pollen tubes showed that 70percent of the generative cells were divided by a cell plate, while the other, 30 percentshowed a cleavage furrow which occurred at the position where a cell plate should takeplace. The cell plate appeared at First as a subunit in late anaphase, which was assembledin the midzone of the phragmoplast and coalesced as one large continued unit in telophase.On the other hand, just in anaphase, as two identical chromosome masses were segregatedfrom each other, the plasma membrane of the generative cell were furrowing inside fromthe tWo sides in the interzonal region. In some instances, the cell was almost divided intotwo parts by the constriction furrow. The occurrence of cleavage seemed to be associatedwith the re-establishment of the nuclear envelope and the disorder of microtubular arrays,as well as the unusual behavior of the chromosomes.
文摘Objective： To examine modulations caused by cyclooxygenase-2 （COX-2） inhibitors on altered microenvironments and overbalanced neurotransmitters in pilocarpine-induced epileptic status rats and to investigate possible mechanisms. Methods： Celecoxib （a COX-2 inhibitor） was administered 45 min prior to pilocarpine administration. The effects of COX-2 inhibitors on mlPSCs （miniature GABAergic inhibitory postsynaptic currents） of CA3 pyramidal cells in the hippocampus were recorded. Expressions of COX-2, c-Fos, newly generated neurons, and activated microgliosis were analyzed by immunohistochemistry, and expressions of c^-subunit of y-amino butyric acid （GABAA） receptors and mitogen-activated protein kinase/extracellular signal-regulated protein kinase （MAPK/ERK） activity were detected by Western blotting. Results： Pretreatment with celecoxib showed protection against pilocarpine-induced seizures. Celecoxib prevented microglia activation in the hilus and inhibited the abnormal neurogenesis and astrogliosis in the hippocampus by inhibiting MAPK/ERK activity and c-Fos transcription. Celecoxib also up-regulated the expression of GABAA receptors. NS-398 （N-2-cyclohexyloxy-4-nitrophenyl-methanesulfonamide）, another COX-2 inhibitor, enhanced the frequency and decay time of mIPSCs. Conclusion： The COX-2 inhibitor celecoxib decreased neuronal excitability and prevented epileptogenesis in pilocarpine-induced status epilepticus rats. Celecoxib regulates synaptic reorganization by inhibiting astrogliosis and ectopic neurogenesis by attenuating MAPK/ERK signal activity, mediated by a GABAergic mechanism.
文摘Objective To investigate the effect of interleukin-6(IL-6)on the human growth hormone(hGH)gene expression in a rat somatotropic pituitary cell line MtT/S.Methods The plasmids containing various lengths of hGH gene 5'-promoter fragments were constructed.Stably transfected MtT/S cells were created by cotransfecting the above plasmids and pcDNA3.1(+)with DMRIE-C transfection reagent.After the administration of these cells with IL-6 and/or various inhibitors of signaling transduction pathways,the luciferase activities in MtT/S cells lysis were assayed to demonstrate the effects of IL-6 on hGH gene promoter activity and possibly involved mechanism.Results The 103 U/mL IL-6 stimulated GH secretion and synthesis,and promoted the 5'-promoter activity of GH gene in stably transfected MtT/SGL cells with the action of 1.69 times above the control.Among inhibitors of signaling transduction pathways,mitogen-activated protein kinase kinase(MAPKK/MEK)inhibitor PD98059(40 μmol/L)and p38 mitogen-activated protein kinase(MAPK)inhibitor SB203580(5 μmol/L)completely blocked the stimulatory effect of IL-6.Western blot analysis further confirmed the activation of phosphorylated MEK and p38 MAPK in MtT/SGL cells.Neither over-expression of Pit-1 nor inhibition of Pit-1 expression affected IL-6 induction of hGH promoter activity.A series of deletion constructs of hGH promoter were created to identify the DNA sequence that mediated the effect of IL-6.The results showed that the stimulatory effect of IL-6 was abolished following deletion of the-196 to-132 bp fragment.Conclusions IL-6 promotes GH secretion and synthesis by rat MtT/S somatotroph cells.The stimulatory effect of IL-6 on hGH gene promoter appears to require the activation of MEK and p38 MAPK,and a fragment of promoter sequence that spans the-196 to-132 bp of the gene,but may be unlinked with Pit-1 protein.
文摘The dynamic distribution of phosphorylated Histone H3 on Ser10 (phospho-H3) in cells was investigated to determineits function during mitosis. Human breast adenocarcinoma cells MCF-7, and Chinese hamster cells CHO were analyzedby indirect immunofluorescence staining with an antibody against phospho-H3. We found that the phosphorylationbegins at early prophase, and spreads throughout the chromosomes at late prophase. At metaphase, most of the phospho-H3 aggregates at the end of the condensed entity of chromosomes at equatorial plate. During anaphase and telophase,the fluorescent signal of phospho-H3 is detached from chromosomes into cytoplasm. At early anaphase, phospho-H3shows ladder bands between two sets of separated chromosome, and forms “sandwich-like structure” when the chro-mosomes condensed. With the cleavage progressing, the “ladders” of the histone contract into a bigger bright dot. Thenthe histone aggregates and some of compacted microtubules in the midbody region are composed into a “bar-like”complex to separate daughter cells. The daughter cells seal their plasma membrane along with the ends of the “bar”,inside which locates microtubules and modified histones, to finish the cytokinesis and keep the “bar complex” out of thecells. The specific distribution and kinetics of phospho-H3 in cytoplasm suggest that the modified histones may takepart in the formation of midbody and play a crucial role in cytokinesis.
基金Supported by the National Basic Research Program (973 Program)(No. 2008CB418002)the National Major Programs of Water Body Pollution Control and Remediation (Nos. 2009ZX07104-005,2009ZX07106-001)
文摘Eutrophication has become a serious concern in many lakes, resulting in cyanobacterial blooms. However, the mechanism and pathways of cyanobacteria decline are less understood. To identify and define the growth and decline of Microcystis blooms in Taihu Lake of China, and to illuminate the destination of surface floating blooms, we investigated the biomass distribution and variations in colony size, morphology, and floating velocity from October 2008 to September 2009. The results showed that the Microcystis bloom declined in response to biomass decrease, colony disaggregation, buoyancy reduction, and increased phytoplankton biodiversity, and these indicative parameters could be applied for recognition of the development phases of the bloom. Three major decline pathways were proposed to describe the bloom decline process, colony disaggregation （Pathway I）, colony settlement （Pathway II）, and cell lysis in colonies （Pathway III）. We proposed a strategy to define the occurrence and decline of Microcystis blooms, to evaluate the survival state under different stress conditions, and to indicate the efficiency of controlling countermeasures against algal blooms.
基金Supported by Natural Science Foundation of Jiangsu Province,No.10KJD310002The Graduate Innovation Program in Science and Technology of Xuzhou Medical College,No.XYCX201005
文摘AIM： To investigate the possible mechanism by which hepatitis B virus X protein （HBx） mediates apoptosis of HepG2 cells. METHODS： HBx expression vector pcDNA3.1-X was transfected into HepG2 cells to establish an HBx high- expression cellular model as pcDNA3.1-X transfected group. The pcDNA3.1-X and pSilencer3.1-shHBX （HBx antagonist） were cotransfected into HepG2 cells to es- tablish an HBx low-expression model as RNAi group. Untransfected HepG2 cells and HepG2 cells transfected with negative control plasmid were used as controls. Apoptosis rate, the expression of Fas/FasL signaling pathway-related proteins and the phosphorylation lev- els of MLK3, MKK7 and JNKs, which are upstream molecules of death receptor pathways and belong to the family of mitogen-activated protein kinases （MAPKs）,were measured in each group RESULTS： Compared with HepG2 cell group and RNAi group, apoptosis rate, the expression of Fas and FasL proteins, and the activation of MLK3, MKK7 and 3NKs were increased in the pcDNA3.1-X transfected group. The activation of JNKs and expression of FasL protein were inhibited in the pcDNA3.1-X transfected group when treated with a known JNK inhibitor, SP600125. When authors treated pcDNA3.1-X transfected group with K252a, a known MLK3 inhibitor, the activation of MLK3, MKK7 and 3NKs as well as expression of FasL protein was inhibited. Furthermore, cell apoptosis rate was also significantly declined in the presence of K252a in the pcDNA3.1-X transfected group. CONCLUSION： HBx can induce HepG2 cell apoptosis via a novel active MLK3-MKK7-JNKs signaling module to upregulate FasL protein expression.
基金This work was supported by the National Natural Science Foundation of China(No.39870389)the Supported by the Excellent Young Teachers Program of MOE,P.R.C.
文摘CDKs play key roles in controlling cell cycle progression in all eukaryotes. In plants, multiple CDKs are present,among which the best characterized CDKs are PSTAIRE CDKs. In this study, we carried out Western blot,immunoelectron microscopy and antibody treatment with an anti-PSTAIRE monoclonal antibody to explore the subcellular localization and functions of PSTAIRE CDKs in Physarum polycephalum. The results of Western blot and immunoelectron microscopy showed that in P. polycephalum, a PSTAIRE CDK-like protein was 34 kD in molecular weight and located in both nuclei and cytoplasm. In nuclei, the protein was mainly associated with chromosomes and nucleoli. The expression of the PSTAIRE CDK-like protein in both the plasmodia and nuclei showed little fluctuation through the whole cell cycle. When treated with an anti-PSTAIRE monoclonal antibody at early S phase, the cells were arrested in S phase, and the mitotic onset of P. polycephalum was blocked for about 1 h when treated at early G2 phase.Our data indicated that the PSTAIRE CDK- like protein has a direct bearing on the mitosis.
文摘Amitosis, different from mitosis, is a rare form of the proliferation of the cells. Most amitosis were observed in animal cells; only few of them were reported in plant cells. The cytological investigation in this study demonstrated first time in Pelargonium zonale two different amitotic nuclear division ways： cleavage and constriction, in which no appearance of the visible chromosomes and no spindles were observed. After amitotic nuclear division the cytokinesis was also observed, in which the cytoplasm divided directly into two or more parts accompany with formation of two or more daughter cells. This study showed the genetic material may sometimes be unequally distributed between the daughter cells in amitosis, and the amitosis could lead to bi-, tri- and multinucleated cells. These new findings are discussed in regard to the nuclear amitotic process in polyploid cells which gives rise to smaller, viable nuclei in multinucleated cells with reduced numbers of genomes. It was suggested that amitosis could be a way of the division of the endoreduplicated cells.
