The research, based on pol ens of Zygocactus truncates during ful-bloom period, selected suitable culture medium and temperature for pol en germination and explored the effects of storage temperatures and pol en col e...The research, based on pol ens of Zygocactus truncates during ful-bloom period, selected suitable culture medium and temperature for pol en germination and explored the effects of storage temperatures and pol en col ection methods on pol en vitality of Zygocactus truncates and the results showed that the culture medium containing 200 g/L saccharose, 20 mg/L boric acid, and 20 mg/L calcium chloride is suitable for pol en germination of Zygocactus truncates; when the temperature kept below 20 ℃, pol en germination period last short, and germination rate kept higher;pol en germination performed better with filaments, and pol en tube grew wel .展开更多
Incubation of dinoflagellate Crythecodinium cohnii chromosomes in cytoplasmic extracts of unfertilized Xenopus laevis eggs resulted in chromosomes decondensation and recondensation, nuclear envelope assembly, and nucl...Incubation of dinoflagellate Crythecodinium cohnii chromosomes in cytoplasmic extracts of unfertilized Xenopus laevis eggs resulted in chromosomes decondensation and recondensation, nuclear envelope assembly, and nuclear reconstitution.Dinoflagellate Crythecodinium cohnii is a kind of primitive eukaryote which possesses numerous permanently condensed chromosomes and discontinuous double-layered nuclear membrane throughout the cell cycle. The assembled nuclei, being surrounded by a continuous double membrane containing nuclear pores and the uniformly dispersed chromatin fibers are morphologically distinguishable from that of Dinoflagellate Crythecodinium cohnii. However, incubation of dinoflagellate Crythecodinium cohnii chromosomes in the extracts from dinoflagellate Crythecodinillm cohnii cells does not induce nuclear reconstitution.展开更多
The matrix metalloproteinase (MMP) stromelysin-3 (ST3) has long been implicated to play an important role in extracellular matrix (ECM) remodeling and cell fate determination during normal and pathological processes. ...The matrix metalloproteinase (MMP) stromelysin-3 (ST3) has long been implicated to play an important role in extracellular matrix (ECM) remodeling and cell fate determination during normal and pathological processes. However like other MMPs, the molecular basis of ST3 function in vivo remains unclear due to the lack of information on its physiological substrates. Furthermore, ST3 has only weak activities toward all tested ECM proteins. Using thyroid hormone-dependent Xenopus laevis metamorphosis as a model, we demonstrated previously that ST3 is important for apoptosis and tissue morphogenesis during intestinal remodeling. Here, we used yeast two-hybrid screen with mRNAs from metamorphosing tadpoles to identify potential substrate of ST3 during development. We thus isolated the 37 kd laminin receptor precursor (LR). We showed that LR binds to ST3 in vitro and can be cleaved by ST3 at two sites distinct from where other MMPs cleave. Through peptide sequencing, we determined that the two cleavage sites are in the extracellular domain between the transmembrane domain and laminin binding sequence. Furthermore, we demon strated that these cleavage sites are conserved in human LR. These results together with high levels of human LR and ST3 expression in carcinomas suggest that LR is a likely in vivo substrate of ST3 and that its cleavage by ST3 may alter cell-extracellular matrix interaction, thus, playing a role in mediating the effects of ST3 on cell fate and behavior ob- served during development and pathogenesis.展开更多
A cell-free preparation obtained from extracts of activated Xenopus laevis eggs induced chromatin decondensation and nuclear formation from demembranated Xenopus sperm nuclei. Electron microscopy revealed that the rea...A cell-free preparation obtained from extracts of activated Xenopus laevis eggs induced chromatin decondensation and nuclear formation from demembranated Xenopus sperm nuclei. Electron microscopy revealed that the reassembled nucleus had a double-layered nuclear membrane, nuclear pore complexes, and decondensed chromatin etc. Indirect immunofluorescence analysis demonstrated the presence of lamina in newly assembled nuclei. Western-blotting results showed that lamin LII was present in egg extracts and in lamina of the reassembled nuclei which were previously reported to contain only eggderived lamin LIII.展开更多
Objective： To study the precise role of DOR in the regulation of sodium channels at present. Methods： With Xenopus oocytes co-expressing sodium channel subtype 2 （Nav1.2） and DOR. Results： 1） Nav1.2 expression i...Objective： To study the precise role of DOR in the regulation of sodium channels at present. Methods： With Xenopus oocytes co-expressing sodium channel subtype 2 （Nav1.2） and DOR. Results： 1） Nav1.2 expression induced tetrodotoxin-sensitive inward currents; 2） DOR expression reduced the inward currents; 3） activation of DOR reduced the amplitude of the current and rightly shifted the activation curve of the current in the oocytes with both Nav1.2 and DOR, but not in ones with Nav1.2 alone; 4） the DOR agonist-induced inhibition of Nay 1.2 currents was in a dose-dependent manner and saturable; 5） the DOR agonist had no effect on naive oocytes. Conclusion： These data represent the first demonstration that activation of DOR inhibits Na^＋ channel function by decreasing the amplitude of sodium currents and increasing its threshold of activation. This novel finding has far-reaching impacts on novel solutions of certain neurological disorders such as hypoxic/ischemic injury, epilepsy and pain. Also, our data may improve the understanding of the mechanisms underlying acupuncture since acupuncture is known to activate the brain opioid system.展开更多
文摘The research, based on pol ens of Zygocactus truncates during ful-bloom period, selected suitable culture medium and temperature for pol en germination and explored the effects of storage temperatures and pol en col ection methods on pol en vitality of Zygocactus truncates and the results showed that the culture medium containing 200 g/L saccharose, 20 mg/L boric acid, and 20 mg/L calcium chloride is suitable for pol en germination of Zygocactus truncates; when the temperature kept below 20 ℃, pol en germination period last short, and germination rate kept higher;pol en germination performed better with filaments, and pol en tube grew wel .
文摘Incubation of dinoflagellate Crythecodinium cohnii chromosomes in cytoplasmic extracts of unfertilized Xenopus laevis eggs resulted in chromosomes decondensation and recondensation, nuclear envelope assembly, and nuclear reconstitution.Dinoflagellate Crythecodinium cohnii is a kind of primitive eukaryote which possesses numerous permanently condensed chromosomes and discontinuous double-layered nuclear membrane throughout the cell cycle. The assembled nuclei, being surrounded by a continuous double membrane containing nuclear pores and the uniformly dispersed chromatin fibers are morphologically distinguishable from that of Dinoflagellate Crythecodinium cohnii. However, incubation of dinoflagellate Crythecodinium cohnii chromosomes in the extracts from dinoflagellate Crythecodinillm cohnii cells does not induce nuclear reconstitution.
文摘The matrix metalloproteinase (MMP) stromelysin-3 (ST3) has long been implicated to play an important role in extracellular matrix (ECM) remodeling and cell fate determination during normal and pathological processes. However like other MMPs, the molecular basis of ST3 function in vivo remains unclear due to the lack of information on its physiological substrates. Furthermore, ST3 has only weak activities toward all tested ECM proteins. Using thyroid hormone-dependent Xenopus laevis metamorphosis as a model, we demonstrated previously that ST3 is important for apoptosis and tissue morphogenesis during intestinal remodeling. Here, we used yeast two-hybrid screen with mRNAs from metamorphosing tadpoles to identify potential substrate of ST3 during development. We thus isolated the 37 kd laminin receptor precursor (LR). We showed that LR binds to ST3 in vitro and can be cleaved by ST3 at two sites distinct from where other MMPs cleave. Through peptide sequencing, we determined that the two cleavage sites are in the extracellular domain between the transmembrane domain and laminin binding sequence. Furthermore, we demon strated that these cleavage sites are conserved in human LR. These results together with high levels of human LR and ST3 expression in carcinomas suggest that LR is a likely in vivo substrate of ST3 and that its cleavage by ST3 may alter cell-extracellular matrix interaction, thus, playing a role in mediating the effects of ST3 on cell fate and behavior ob- served during development and pathogenesis.
文摘A cell-free preparation obtained from extracts of activated Xenopus laevis eggs induced chromatin decondensation and nuclear formation from demembranated Xenopus sperm nuclei. Electron microscopy revealed that the reassembled nucleus had a double-layered nuclear membrane, nuclear pore complexes, and decondensed chromatin etc. Indirect immunofluorescence analysis demonstrated the presence of lamina in newly assembled nuclei. Western-blotting results showed that lamin LII was present in egg extracts and in lamina of the reassembled nuclei which were previously reported to contain only eggderived lamin LIII.
基金the Science Foundation of Shanghai Municipal Commission of Science and Technology(05DZ19745,06DZ19732,064319053,07DZ19722,07DZ19733)the National Basic Research Program of China(973 Program,2005CB523306)+1 种基金Shanghai Leading Academic Discipline Project(B112 and T0302)NIH-HD3485
文摘Objective： To study the precise role of DOR in the regulation of sodium channels at present. Methods： With Xenopus oocytes co-expressing sodium channel subtype 2 （Nav1.2） and DOR. Results： 1） Nav1.2 expression induced tetrodotoxin-sensitive inward currents; 2） DOR expression reduced the inward currents; 3） activation of DOR reduced the amplitude of the current and rightly shifted the activation curve of the current in the oocytes with both Nav1.2 and DOR, but not in ones with Nav1.2 alone; 4） the DOR agonist-induced inhibition of Nay 1.2 currents was in a dose-dependent manner and saturable; 5） the DOR agonist had no effect on naive oocytes. Conclusion： These data represent the first demonstration that activation of DOR inhibits Na^＋ channel function by decreasing the amplitude of sodium currents and increasing its threshold of activation. This novel finding has far-reaching impacts on novel solutions of certain neurological disorders such as hypoxic/ischemic injury, epilepsy and pain. Also, our data may improve the understanding of the mechanisms underlying acupuncture since acupuncture is known to activate the brain opioid system.
