The genetic variation in the critically endangered speciesIsoetes hypsophila was investigated using Random Amplified Polymorphism DNA (RAPD) markers. Thirteen primers were screened from sixty primers, and a total of 1...The genetic variation in the critically endangered speciesIsoetes hypsophila was investigated using Random Amplified Polymorphism DNA (RAPD) markers. Thirteen primers were screened from sixty primers, and a total of 104 DNA fragments were scored, of which, 52 were polymorphic loci. Low-level genetic diversity within populations with PPB values ranging from 7.69%to 25.96%was found. An Anal ysis of Molecular Variance (AMOVA) indicated that the most of variance (78.30%) occurred between Yunnan and Si chuan. The variances among populations within regions and within populations were only 3.89%and 17.82%, respectively.展开更多
The pattern of change of the microtubule cytoskele-ton of the root-tip cells of rice during mitosis was studied using immunofluorescence technic and confocal laser scanning microscopy. All the major stages of cell div...The pattern of change of the microtubule cytoskele-ton of the root-tip cells of rice during mitosis was studied using immunofluorescence technic and confocal laser scanning microscopy. All the major stages of cell division including preprophase, prophase, metaphase, anaphase and telophase were observed. The most significant finding was that in the preprophase cells microtubules radiating from the nuclear surface to the cortex were frequently seen. During development these microtubules became closely associated with the preprophase band and prophase spindle indicating that the microtubules radiating from the nuclear surface, the preprophase band and the prophase spindle were structurally and functionally closely related to each other. Granule-like anchorage sites for the radiating microtubules at the nuclear surface were often seen and the possibility that these granule-like anchorage sites might represent the microtubule organizing centres was discussed.展开更多
This study describes the use of algae as potential bioindicators of pollution containing industrial metals. Phytoplanktonic algae varied with waste type and with environmental and growth conditions.In water samples co...This study describes the use of algae as potential bioindicators of pollution containing industrial metals. Phytoplanktonic algae varied with waste type and with environmental and growth conditions.In water samples containing cermic waste Euglenophyta species and Cyclotella sp. (Bacillariophyta) were determined as potential indicator species of pollution, while in sample containing metallic waste, Cyclolella sp. was most dominant. Under laboratory growth conditions, phytoplankton collected from a major stream of the Nile River were cultivated by using Algal Growth Bottle Test (EPA, 1972). This revealed that Scensdesmus sp., Actinastrum hantzschii (Chlorophyta), Oscillatoria limneica (Cyanophyta) and Nitzschia linearis (Bacilldriophyta) were also poential indicators of pollution.展开更多
Effects of pH, temperature, EDTA and photosynthetically available radiation on the uptake and toticity of Cd was investigated in Spirodela polyrhiza (L.) Schleid. and Azolla pinnata R. Br. In general, Cd toxicity was ...Effects of pH, temperature, EDTA and photosynthetically available radiation on the uptake and toticity of Cd was investigated in Spirodela polyrhiza (L.) Schleid. and Azolla pinnata R. Br. In general, Cd toxicity was accentuated in conditions which favoured enhanced intracellular Cd uptake. Extracellular binding and intracellular uptake of Cd were lowered at pH values ) 7 due to reduced availability of the aquo ion; consequently,toxicity was markedly reduced. At pH value (7, extracellular binding remained unaffected,although intracellular uptake and toxicity of Cd were enhanced. This perhaps resulted from changes in membrane permeability as extracellular Cd binding was not affected by the decline in pH from 7 to 4. Moreover, speciation of Cd is known to remain unchanged throughout this pH range as most of the Cd (>99%) remains available as the aquo ion. The presence of EDTA in the medium decreased extracellular binding, intracellular uptake and toxicity of Cd in test plants. This was due to formation of Cd-EDTA complex which was obviously not available to tcst plants. Elcvation of temperature increased intracellular Cd uptake and this resulted in enhanced toxic effects. Similarly, increase in photosynthetically available radiation caused a slight increase in Cd uptake and toxicity in test plants.obviously, rise in temperature or PAR increased metabolic activities of test plants thereby leading to increased Cd transport and toxicity展开更多
基金Supported by the National Natural Science Foundation of China (30370098) and the State Key Basic Research and De velopment Plan (G2000046805)
文摘The genetic variation in the critically endangered speciesIsoetes hypsophila was investigated using Random Amplified Polymorphism DNA (RAPD) markers. Thirteen primers were screened from sixty primers, and a total of 104 DNA fragments were scored, of which, 52 were polymorphic loci. Low-level genetic diversity within populations with PPB values ranging from 7.69%to 25.96%was found. An Anal ysis of Molecular Variance (AMOVA) indicated that the most of variance (78.30%) occurred between Yunnan and Si chuan. The variances among populations within regions and within populations were only 3.89%and 17.82%, respectively.
文摘The pattern of change of the microtubule cytoskele-ton of the root-tip cells of rice during mitosis was studied using immunofluorescence technic and confocal laser scanning microscopy. All the major stages of cell division including preprophase, prophase, metaphase, anaphase and telophase were observed. The most significant finding was that in the preprophase cells microtubules radiating from the nuclear surface to the cortex were frequently seen. During development these microtubules became closely associated with the preprophase band and prophase spindle indicating that the microtubules radiating from the nuclear surface, the preprophase band and the prophase spindle were structurally and functionally closely related to each other. Granule-like anchorage sites for the radiating microtubules at the nuclear surface were often seen and the possibility that these granule-like anchorage sites might represent the microtubule organizing centres was discussed.
文摘This study describes the use of algae as potential bioindicators of pollution containing industrial metals. Phytoplanktonic algae varied with waste type and with environmental and growth conditions.In water samples containing cermic waste Euglenophyta species and Cyclotella sp. (Bacillariophyta) were determined as potential indicator species of pollution, while in sample containing metallic waste, Cyclolella sp. was most dominant. Under laboratory growth conditions, phytoplankton collected from a major stream of the Nile River were cultivated by using Algal Growth Bottle Test (EPA, 1972). This revealed that Scensdesmus sp., Actinastrum hantzschii (Chlorophyta), Oscillatoria limneica (Cyanophyta) and Nitzschia linearis (Bacilldriophyta) were also poential indicators of pollution.
文摘Effects of pH, temperature, EDTA and photosynthetically available radiation on the uptake and toticity of Cd was investigated in Spirodela polyrhiza (L.) Schleid. and Azolla pinnata R. Br. In general, Cd toxicity was accentuated in conditions which favoured enhanced intracellular Cd uptake. Extracellular binding and intracellular uptake of Cd were lowered at pH values ) 7 due to reduced availability of the aquo ion; consequently,toxicity was markedly reduced. At pH value (7, extracellular binding remained unaffected,although intracellular uptake and toxicity of Cd were enhanced. This perhaps resulted from changes in membrane permeability as extracellular Cd binding was not affected by the decline in pH from 7 to 4. Moreover, speciation of Cd is known to remain unchanged throughout this pH range as most of the Cd (>99%) remains available as the aquo ion. The presence of EDTA in the medium decreased extracellular binding, intracellular uptake and toxicity of Cd in test plants. This was due to formation of Cd-EDTA complex which was obviously not available to tcst plants. Elcvation of temperature increased intracellular Cd uptake and this resulted in enhanced toxic effects. Similarly, increase in photosynthetically available radiation caused a slight increase in Cd uptake and toxicity in test plants.obviously, rise in temperature or PAR increased metabolic activities of test plants thereby leading to increased Cd transport and toxicity
