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1.
2.
Summary Maize (Zea mays) leaf protoplasts were isolated from various leaves of two-week (4-leaf) seedlings and from sections of the third leaf blades. Microtubules (MTs) were visualized using immunofluorescence microscopy. Only freshly isolated protoplasts from the third and fourth leaf blades contained MTs, with protoplasts from the fourth leaf containing the most i.e. 13% of fourth-leaf protoplasts contained MTs. In general, protoplasts with fewer and smaller chloroplasts had more MTs. Initially 90–95% of protoplasts from basal portions of leaves had MTs but the percentage decreased slightly during culture particularly after 10 days. The antioxidant n-propyl gallate was beneficial in maintaining MT content. Few protoplasts from older sections intitially contained MTs but in all sections at least some protoplasts regained a significant MT content during culture (e.g., 10% of protoplast from the tip section possessed microtubules after 7 days of culture). Far fewer MTs were observed in individual leaf protoplasts than those isolated from suspension culture.Abbreviations BMS
Black Mexican Sweet
- MT
microtubule
- MtSB
microtubule stabilizing buffer
- PBS
phosphate buffered saline 相似文献
3.
DNA replication in maize leaf protoplasts 总被引:1,自引:0,他引:1
H. Wang Adrian J. Cutler M. Saleem Larry C. Fowke 《Plant Cell, Tissue and Organ Culture》1989,18(1):33-46
Maize leaf protoplasts were investigated for their metabolic competence and capacity to synthesize DNA. When protoplasts were incubated at elevated temperatures, they exhibited a heat shock response with specific proteins being preferentially synthesized. This indicated that the protoplasts were fully metabolically functional and capable of responding to environmental stimuli. Significant DNA synthesis was observed in these protoplasts after incorporation of 3H-thymidine into chromatin by trichloroacetic acid precipitation and by incorporation of 5-bromo-2-deoxyuridine (BrdU), an analog of thymidine, detected by immunofluorescence. The immunocytochemical method revealed that about 50% of nuclei in the maize leaf protoplasts were labelled after 3 days of culture and that most of these nuclei were labelled as intensely as normal mitotic cells. Aphidicolin, an inhibitor of DNA polymerase-, decreased the percentage of labelled nuclei, demonstrating that the labelling was substantially due to replicative DNA synthesis. However, chromosome condensation was not observed. It is proposed that these protoplasts are capable of DNA synthesis, but incapable of nuclear division. Effects of media additives on the number of nuclei entering S phase in these protoplasts were also assessed by the immunocytochemical method. Inclusion of 80mM Ca2+ in the enzyme solution increased protoplast yield and also appeared beneficial to DNA synthesis. The antioxidant, n-propyl gallate, which was used to stabilize the protoplasts, delayed the onset of DNA synthesis. Arginine and spermidine produced a slight increase in DNA synthesis.Abbreviations BrdU
5-bromo-2-deoxyuridine
- DMSO
dimethyl sulfoxide
- n-PG
n-propyl gallate
- PBS
phosphate-buffered saline
Dedicated to Dr. Friedrich Constabel on the occasion of his 60th birthday 相似文献
4.
The neem tree (Azadirachta indica) contains promising pest-control substances found effective against many economically important pests. These materials are easy to process by village-level industries and easy to use by limited-resource farmers, thereby offering potential for crop protection and off-farm income generation. The tree’s numerous pharmacological and other complementary uses make it doubly attractive for incorporation in large-scale rural development efforts. 相似文献
5.
Raman Kapur Mohammed Saleem Bryan L. Harvey Adrian J. Cutler 《In vitro cellular & developmental biology. Plant》1993,29(4):200-206
Summary Barley leaf blade protoplasts accumulate malonaldehyde, a product of lipid peroxidation, during culture. In addition, glutathione
levels fall after protoplast isolation and the proportion of glutathione in the oxidized state rises. These data indicate
oxidative stress after protoplast isolation and during culture. The cause of this phenomenon is revealed by data showing that
the activities of enzymes associated with antioxidative processes including glutathione reductase and ascorbate peroxidase
decrease after barley protoplast isolation. In contrast, protoplasts isolated from suspension cultured cells of bromegrass
and soybean exhibit little evidence for oxidative stress and increased activities of glutathione reductase and ascorbate peroxidase.
We suggest that an antioxidative response is associated with mitosis and colony formation from protoplasts, as exhibited by
bromegrass and soybean. Conversely, failure of an antioxidative response is associated with low viability and absence of mitosis,
as in barley. Increased viability of barley leaf protoplasts cultured on feeder layer cells is correlated with increased glutathione
content and higher glutathione reductase activity. 相似文献
6.
The endoplasmic reticulum (ER) membrane protein complex (EMC) is essential for the insertion of a wide variety of transmembrane proteins into the plasma membrane across cell types. Each EMC is composed of Emc1-7, Emc10, and either Emc8 or Emc9. Recent human genetics studies have implicated variants in EMC genes as the basis for a group of human congenital diseases. The patient phenotypes are varied but appear to affect a subset of tissues more prominently than others. Namely, craniofacial development seems to be commonly affected. We previously developed an array of assays in Xenopus tropicalis to assess the effects of emc1 depletion on the neural crest, craniofacial cartilage, and neuromuscular function. We sought to extend this approach to additional EMC components identified in patients with congenital malformations. Through this approach, we determine that EMC9 and EMC10 are important for neural crest development and the development of craniofacial structures. The phenotypes observed in patients and our Xenopus model phenotypes similar to EMC1 loss of function likely due to a similar mechanism of dysfunction in transmembrane protein topogenesis. 相似文献
7.
Sequence requirements for the termination of rolling-circle replication of plasmid pT181 总被引:3,自引:0,他引:3
Most small multicopy plasmids of Gram-positive bacteria and many in Gram-negative bacteria replicate by a rolling-circle (RC) mechanism. The replication initiator proteins encoded by the RC plasmids and single-stranded bacteriophages of Escherichia coli have origin-specific nicking-closing activities that are required for the initiation and termination of RC replication. We have investigated the sequence requirements for termination of RC replication of plasmid pT181. The initiator nick site is located in the loop of a hairpin region (IRII) within the pT181 origin of replication. By mutational analysis, we have found that several nucleotides within the stem of IRII which are critical for the initiation activity are dispensable for termination of replication. We also demonstrate that nucleotides in the right arm of IRII, but not the left arm, are absolutely required for termination of RC replication. We have also identified specific nucleotides in IRII that are critical for its termination activity. The sequence of the right arm of the hairpin must be located downstream of the initiator nick site for termination, suggesting that termination requires a specific orientation of the initiator protein at the origin. 相似文献
8.
M A Nayeem C M Habibullah Y Saleem M Ishaq M Salma 《Indian journal of experimental biology》1991,29(11):1064-1066
Fifty-two amoebic liver abscess cases were assessed for the release of lymphokines (LMIF) using detergent dissected membrane proteins (DDMP) of axenic Entamoeba histolytica (NIH:200) obtained with sodium deoxycholate treatment. Lymphokines release by T lymphocytes in response to both DDMP and whole amoebic lysate (WAL) was tested by leukocyte migration inhibition test on blood samples from amoebic liver abscess cases. A significant increase was noted in the release of LMIF and 100% positivity was observed with DDMP compared to whole amoebic extract with a positivity of 73%. The difference between means of the above two with regards to release of LMIF was found to be highly significant (P less than 0.005). This shows the patients had high degree of leukocyte sensitization to surface antigens of E. histolytica compared to the whole amoebic lysate. These findings suggest that the antigens shed might have important role as a potent antigen in elicitation of CMI response in amoebic liver abscess cases. 相似文献
9.
Summary With barley a large variation in frequency of plant formation from microspores of spikes from the same plant has been observed. The highest frequency of plant formation was obtained when culturing anthers in the dark on a high Ficoll medium containing 2,4-D and kinetin to induce proembryo (or callus) formation. Subsequently the proembryos or calli were cultured in dim light on a high Ficoll-high sugar medium containing IBA and kinetin. Finally the embryos were transferred to a starch agar medium. A maximum of 13 green plants were obtained from microspores of a single anther.The ratios of green to albino microspore derived plants varied from 91 to 19 depending on culture conditions. Under anaerobic conditions, lactic acid and other organic acids may have damaged the organelles in the cells resulting in the formation of albino plants. Thus, direct embryogenesis by using a well-buffered, high Ficoll-high sugar medium and proper aeration are essential for obtaining high frequency of green plants from microspores.Abbreviations 2,4-D
2,4 dichlorophenoxyacetic acid
- IBA
3 indolylbutyric acid 相似文献
10.
M Alam M Ahmad A Rasheed M Saleem M K Javaid S Ikram 《Indian journal of experimental biology》1990,28(10):940-942
The metabolic fate of isatin hydrazone (Ia), isatin-3-thiosemicarbazone (Ib), isatin-3-semicarbazone (Ic), isatin-3-phenylhydrazone (Id), isatin oxime (Ie) and 3-hydroxy-3-acetonyl oxindole (II) was studied in rabbits. The compounds were administered orally in the dose of 300 mg/kg body wt. Isatin anthranilic acid, tryptophan and nicotinic acid were identified as the major metabolites excreted in urine. The 3-hydroxy-3-acetonyl oxindole (II) gave on additional metabolite, oxindole. The major metabolites were separated and identified unambiguously on thin layer silica gel plate. Metabolic pathways have been proposed to explain the biotransformation of the compounds investigated. 相似文献