In this study, freeze - fractured specimens of Allium cepa root tip meristems were examined under the scanning electron microscope (SEM). This technique permitted the visualization of the outer membrane of the nuclear...In this study, freeze - fractured specimens of Allium cepa root tip meristems were examined under the scanning electron microscope (SEM). This technique permitted the visualization of the outer membrane of the nuclear envelope with nuclear pore complexes and polyribosomes. Some of the cell nuclei prepared with this procedure had fissures of various widths on their nuclear envelopes through which the nuclear lamina-like filaments (LLF) underneath the nucleoplasmic side of the envelopes were clearly visible. The diameters of these filaments varied between 25 and 125 nm. Many of the LLFs showed granular thickenings at places, and were attached to the inner surface of nuclear envelope in some regions. Similar LLFs were also seen at the peripheries of the freeze -fractured faces of nuclei. Meanwhile,the spatial relation between the nuclear matrix filaments (NMF) and other nuclear structures (nucleoli, chromatin and peripheral lamina - like filaments) was revealed in these fractured preparations. In addition, the methods and techniques in studying the nuclear lamina morphology and the roles played by NMFs in activities of various nuclear structures were discussed in brief.展开更多
The reaction ofAllium cepa root tips to the presence of potential toxic chemicals was used to evaluate the cyto/genotoxic effects of some water sources of Nen-Shkodra lowland agricultural area after massive 2010-2011 ...The reaction ofAllium cepa root tips to the presence of potential toxic chemicals was used to evaluate the cyto/genotoxic effects of some water sources of Nen-Shkodra lowland agricultural area after massive 2010-2011 flooding. MRL （Mean root length）, MI （mitotic index）, PI （phase index） and CA （chromosome abnormalities） endpoints of onion roots, grown in four water samples, were measured and compared with tap water and Cu solution 0.5 mg/L （negative and positive controls）. Inhibition of root growth, cell division and induction of mitotic and chromosomal aberrations were detected. The most polluted water sample caused MRL inhibition of 36%, MI decrease of 38%, and a considerable increase in chromosomal aberrations （7.8%） compared to the negative control. Most frequent CA types were： bridges and fragments, stickiness and C-metaphase. The results indicated a slight toxic tendency of analyzed natural waters, serving as an alert of environmental impact that chemical pollution had after flooding.展开更多
文摘In this study, freeze - fractured specimens of Allium cepa root tip meristems were examined under the scanning electron microscope (SEM). This technique permitted the visualization of the outer membrane of the nuclear envelope with nuclear pore complexes and polyribosomes. Some of the cell nuclei prepared with this procedure had fissures of various widths on their nuclear envelopes through which the nuclear lamina-like filaments (LLF) underneath the nucleoplasmic side of the envelopes were clearly visible. The diameters of these filaments varied between 25 and 125 nm. Many of the LLFs showed granular thickenings at places, and were attached to the inner surface of nuclear envelope in some regions. Similar LLFs were also seen at the peripheries of the freeze -fractured faces of nuclei. Meanwhile,the spatial relation between the nuclear matrix filaments (NMF) and other nuclear structures (nucleoli, chromatin and peripheral lamina - like filaments) was revealed in these fractured preparations. In addition, the methods and techniques in studying the nuclear lamina morphology and the roles played by NMFs in activities of various nuclear structures were discussed in brief.
文摘The reaction ofAllium cepa root tips to the presence of potential toxic chemicals was used to evaluate the cyto/genotoxic effects of some water sources of Nen-Shkodra lowland agricultural area after massive 2010-2011 flooding. MRL （Mean root length）, MI （mitotic index）, PI （phase index） and CA （chromosome abnormalities） endpoints of onion roots, grown in four water samples, were measured and compared with tap water and Cu solution 0.5 mg/L （negative and positive controls）. Inhibition of root growth, cell division and induction of mitotic and chromosomal aberrations were detected. The most polluted water sample caused MRL inhibition of 36%, MI decrease of 38%, and a considerable increase in chromosomal aberrations （7.8%） compared to the negative control. Most frequent CA types were： bridges and fragments, stickiness and C-metaphase. The results indicated a slight toxic tendency of analyzed natural waters, serving as an alert of environmental impact that chemical pollution had after flooding.
