Cytobios最新文献

Varied intensities of nitrotyrosine immunoreactivity were detected by Western blots after the reaction of proteins or enzymes with peroxynitrite (PN), a strong oxidant derived from nitric oxide. Intense immunoreactivity of cAMP-dependent protein kinase, calmodulin and most histones may depend on greater access to tyrosine residues in the reaction, whereas the absence of immunoreactivity of caspase-3, ubiquitin and S-100 proteins may reflect lack of accessibility. In addition, the changes in UV/visible absorbency were observed after PN-treatment of polynucleotides, polypeptides or proteins. Brief PN-treatment of invertase increased its enzymatic activity. Furthermore, PN-treatment of rabbit IgG decreased its recognition by anti-IgG. The results suggest that PN may chemically modify polypeptides, proteins and polynucleotides and may subsequently alter their biological activity.

Cultured Chinese hamster ovary (CHO) cells were treated with the cytidine analogue 5-azacytidine (5-azaC) which, in good agreement with results previously described from studies carried out in other primary or established mammalian cell lines, resulted in extensive chromosome decondensation and a shift in the time of replication of normally late-replicating heterochromatin to earlier replication. DNA topoisomerases (mainly topo I) have been involved in transcription, and the hypomethylating effect of 5-azaC reportedly results in the expression of silenced genes. Whether such an increase in transcription is paralleled by increased levels of both topo I and topo II, as well as by an enhancement in the topoisomerase activities, has been investigated in this work. The results seem to suggest that both the relative amount of topoisomerases and their activities are enhanced after a protracted treatment with the cytidine analogue over those observed in untreated controls. These observations could be significant for antitumour therapy.

Vero cells were cultured without foetal calf serum (FCS), with 10% FCS, 10% FCS plus dexamethasone (DEX) or 20% FCS for 48, 120 or 240 h. The cells were analysed by a growth curve, cytochemical and immunocytochemical (anti-cellular fibronectin or anti-collagen IV) methods. In 48 h Vero cells produced fibronectin and collagen IV. All samples showed basophilic cytoplasm indicating high protein synthesis. The growth of metachromatic multicellular masses was induced by DEX. The Vero cells produced collagen IV with 10 and 20% FCS, and also cells which did not have this activity (without FCS or with 10% FCS + DEX). The multicellular masses induced by DEX were rich in fibronectin. DEX induced differentiation and the expression of collagen IV and fibronectin in Vero cells. This work was carried out to evaluate the possible therapeutic effects of glucocorticoids as inducers of cell differentiation.

The impact of monocrotophos on protein and carbohydrate metabolism in different tissues of albino rats was investigated. The monocrotophos (0.25 mg/ml) was orally intubated into an experimental group of rats. In another group, the same amount of water was orally intubated (control group) for 29 days. The protein content was increased in liver, serum and spleen of albino rats after treatment with monocrotophos. The protein content decreased in muscle and kidney, and overall the free sugar level decreased in all tissues. The glycogen content increased in muscle, serum and kidney after treatment with monocrotophos, and the glycogen content and reducing sugar level decreased in liver and spleen. The significance of these results is discussed.

A plant growth promotory bacterial strain, isolated from the potato rhizosphere, was characterized as Pseudomonas aeruginosa (GRC1). The isolate produced an hydroxamate type of siderophore after 48 h of incubation on tryptic soy medium under iron deficient conditions. The in vitro antifungal activity of P. aeruginosa was tested against two soil-borne plant pathogens, Macrophomina phaseolina and Fusarium oxysporum. The antagonistic behaviour of the isolate was tested by dual culture technique. The growth inhibition of M. phaseolina and F. oxysporum was 74.1% and 70.5%, respectively, after 5 days of incubation. The production of hydrocyanic acid and indole acetic acid was also recorded under normal growth conditions.

Allium cepa root growth was retarded by cisplatin treatment in a dose-dependent manner. A decrease in the mitotic index (MI) and an increase in the number of interphase cells was seen in cisplatin treated root tips. An increase in the frequency of abnormal mitoses and chromosomal aberrations was also observed in cisplatin treated groups which indicates its genotoxic effect on plant cells. The endogenous glutathione (GSH) level in the root tips decreased significantly after cisplatin treatment which may favour its increased interaction with cellular DNA thereby developing enhanced chromosomal aberrations and affecting cell divisions and root growth. It is suggested that the decrease in endogenous GSH may be related to the development of cisplatin-mediated genotoxic effects in plants.

The effect of triethyl lead (TriEL) as triethyl lead chloride on the rhythmic peristaltic contractile activity of ileum isolated from Swiss white mice was investigated, with the aid of a tensiometer. The response was measured as a change in period duration and force amplitude. TriEL concentrations of < 40 microM did not show any obvious effects on either of the parameters. In the concentration range between 40 and 120 microM, TriEL exclusively affected the rhythm of contractions in a concentration-dependent manner. It induced elongation of the period and reduction of the force amplitude. Concentrations of TriEL above 120 microM induced irreversible dramatic changes in the ileum contractile activity, while 200 microM TriEL induced a strong contracture followed by an irreversible cessation of the oscillatory contractile activity. The results demonstrate that the measurement of rhythmic contractions may be a useful model for a toxicological screening system.

The pineal gland is involved in wound repair and collagen deposition in sponge-induced granulomas. The aim of this investigation was to discover whether the pineal gland was able to regulate collagen accumulation in the intact skin. Wistar rats were divided into five groups: control, sham-operated with vehicle application, sham-operated with melatonin injections (30 micrograms/100 g body wt), pinealectomized with vehicle, and pinealectomized with melatonin supplementation. After 8 weeks, the collagen content was estimated as hydroxyproline concentration in the dry tissue of the skin. The results showed that melatonin markedly (p < 0.001) reduced collagen accumulation in the skin. Pinealectomy enhanced collagen deposition in the skin (p < 0.02) and melatonin application reduced the pinealectomy-induced elevation of collagen content (p < 0.001). Results clearly indicate that collagen accumulation in the intact skin is under the control of the pineal gland, and that melatonin, the pineal hormone, is responsible for this control.

Electron microscopy and immunolabelling with antiserum specific to cucumber mosaic virus coat protein were used to examine tobacco leaf cells infected by cucumber mosaic virus isolated from Catharanthus roseus (CMV-Cr). Crystalline and amorphous inclusions in the vacuoles were the most obvious cytological modifications seen. Immunogold labelling indicated that the crystalline inclusion was made up of virus particles and amorphous inclusions contained coat protein. Rows of CMV-Cr particles were found between membranes of dictyosomes, but membranous bodies and tonoplast-associated vesicles were not evident. Virus particles and/or free coat protein were easily detected in the cytoplasm by immunolabelling. No gold labelling was found within nuclei, chloroplasts and mitochondria.

The effect of different concentrations of aflatoxin G1 on growth and germination of Zea mays and Vicia faba seeds, as well as on some biochemical parameters viz chlorophyll, carotenoid, protein and lipid content of seedlings, were studied. Inhibition of seed germination and seedling growth of maize and broad bean increased with increases in toxin concentration. A reduction in carbohydrates in the shoot systems of maize and broad bean was accompanied by a corresponding reduction in chlorophyll content. The total proteins and total lipids of V. faba were significantly greater at a 10 micrograms/ml concentration of aflatoxin G1, whereas in Z. mays significant inhibition (p < 0.05) was observed. At 5.0 micrograms/ml aflatoxin G1 lipids and proteins were reduced in both plants but the effect was less obvious at lower concentrations.