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1.
The toxicity of nitrofurantoin was studied on human WI-38 fibroblasts: this chemical was lethal when added at concentrations higher than 5·10−5 M in the culture medium. The protection afforded by anitoxidants was then tested: α-tocopherol gave at 10−4 M a light protection in contrast to ascorbic acid which even became toxic at high concentrations. We also tested catalase, superoxide dismutase and glutathione peroxidase introduced intracellularly by the microinjection technique. On a molecular basis, glutathione peroxidase was 23-times more efficient than catalase and 3000-times more than superoxide dismutase. The results also showed that a similar range of enzyme concentrations was found for the protection against high oxygen pressure. This suggests that, in the case of both oxygen and nitrofurantoin toxicity, the peroxide derivatives are the most toxic intermediates of the free radical attacks. 相似文献
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3.
Johan Geysen Johan Cardoen Sigrid Van Eynde Carine Geens Arnold De Loof 《Development genes and evolution》1988,197(2):101-109
Summary Polar organisation in the follicles of adult Sarcophaga bullata is reflected in the nurse cell-oocyte axis and in the orientation of the two polar cell pairs in the follicular epithelium. The internal organisation of the nurse cell chamber contributes to polarity but not to dorsoventral asymmetry. Dorsoventral asymmetry is correlated with the eccentric position of the germinal vesicle and the orientation of the polar cell pairs; no other follicle cell specialisations are seen. In an ovary, follicles are preferentially orientated with the dorsal side to the centre of the ovary. Cytoskeletal and some haemolymph proteins are molecular markers of polarity. Thus, in pre-vitellogenic stages, tubulin immunoreactivity is higher in the oocyte than in the nurse cells, actin immunoreactivity is the same over the cystocytes and larval serum proteins are restricted to the poles. During vitellogenesis, both actin and tubulin become more concentrated in the nurse cells and larval serum protein 1 accumulated in the polar cells during border cell migration when yolk polypeptides also accumulate in the oocyte. At the end of vitellogenesis a lipophorin is taken up by the oocyte. No molecular marker of dorsoventral asymmetry was identified. 相似文献
4.
The specific activity of bisphosphoglycerate synthase (EC 2.7.5.4) is significantly higher in rat mature erythrocytes than in reticulocytes from phenylhydrazine treated animals, while 2,3-bisphosphoglycerate levels do not differ between them. The enzyme specific activity and the concentration of 2,3-bisphosphoglycerate are both negligible in the erythroid cell pool from the bone marrow of anaemic animals. Thus, a cellular specialization in the last stages of erythropoiesis is confirmed. Human bisphosphoglycerate synthase shows a lower specific activity than that of rat without a parallel decrease in 2,3-bisphosphoglycerate levels. 相似文献
5.
Lernanthropus huamani n. sp. (Copepoda: Lernanthropidae), a parasite of the Peruvian sciaenid fish Menticirrhus ophicephalus (Jenyns), is described and illustrated. The new species differs from all other species of Lernanthropus by a combination of characters, including the dorsal plate, legs and other appendages. L. guacoldae Villalba & Fernández, 1984 is considered a synonym of L. pacificus Oliva & Duran, 1982. 相似文献
6.
Hanne Gahéry-Ségard Evelyne Jouvin-Marche Adrien Six Carine Gris-Liebe Marie Malissen Bernard Malissen Pierre-André Cazenave Patrice N. Marche 《Immunogenetics》1996,44(4):298-305
The number of mouse Tcra-V gene segments varies from one individual to another and is estimated to be about 100. Southern blot analysis revealed that
most of the Tcra-V are organized in clusters composed of copies of Tcra-V belonging to different subfamilies. We analyzed in detail a Tcra-V subfamily and looked for new Tcra-V in order to improve the knowledge of the mouse Tcra locus organization. A series of genomic clones derived from the B10.A mouse strain enclosing these clusters was used to determined
the structure of all the Tcra-V2. We were able to identify ten Tcra-V2. This study showed that the Tcra-V2 can be organized into three structural subgroups. The distribution of the genes along the Tcra locus, plus their structural organization, indicates that successive duplications occurred during the processes of expansion
and contraction of the Tcra-V gene subfamilies. Several Tcra-V2 are also identical, indicating recent duplications. The most divergent Tcra-V2 differ by 7.4% nucleotides, leading to 5.2% differences in amino acid contents.
Received: 8 August 1995 / Revised: 24 April 1996 相似文献
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Initiatedlselected (ISH) and normal (NH) rat hepatocytes were used to study cytoskeleton modifications induced by three liver acting chemicals: 2-AAF, a liver complete carcinogen; PB, a liver tumor promoter; and 4-AAF, a noncarcinogen analogue of 2-AAF. Cytoskeleton alterations were visualized by disappearance of F-actin fibers and tubulin depolymerization. The three drugs induced actin fragmentation in normal hepatocytes; a net loss of actin protein was observed with PB. They also induced varied tubulin depolymerization. The principal difference between chemicals is that 2-AAF led to non-reversible effects, in comparison with PB and 4-AAF which induced reversible damages on cytoskeleton. By contrast to normal hepatocytes, the cytoskeleton of ISH obtained from rats subjected to the resistant hepatocyte protocol was much less susceptible to the effect of the three chemicals. Moreover, we observed a lack of LDH release in the culture medium and a very rapid inducibility of GST activity after exposure of ISH to drugs. The moderate effect of the three chemicals on actin and tubdin in ISH could thus be explained by the resistant metabolic profile of these cells.Abbreviations TPA
12-O-tetradecanoyl-phorbol-13-acetate
- PB
phenobarbital
- 2-AAF
2-acetylaminofluorene
- 4-AAF
4-acetylaminofluorene
- GSH
reduced glutathione
- GST
glutathione-S-transferase
- LDH
lactatedehydrogenase
- NH
normal hepatocytes
- ISH
initiated/selected hepatocytes
- BSA
bovine serum albumin 相似文献
9.
Summary The results are given of experiments to test wether leaf analyses can be used for diagnostic determinations of deficiency and excess in mineral nutrition of lettuce in soilless culture. re]19760127 相似文献
10.
The kinetic behaviour of phosphofructokinase (ATP:D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) has been studied in situ, by using rat erythrocytes and reticulocytes treated with dimethyl suberimidate and 3,3'-dithiobispropionimidate as cross-linking reagents and with digitonin as the delipidating agent. Comparison of the ATP and fructose-6-P saturation curves of phosphofructokinase in dimethyl suberimidate-permeabilized cells with those obtained in haemolysates showed the enzyme to have reduced allosteric properties under in situ conditions, although it still responded to cyclic AMP (300 microM) added as allosteric effector. Non-sigmoidal fructose-6-P saturation curves were also observed using 3,3'-dithiobispropionimidate-permeabilized erythrocytes, either in the absence or in the presence of cyclic AMP. A hyperbolic behaviour was shown after cross-linking reversal of 3,3'-dithiobispropionimidate-permeabilized erythrocytes by treatment with dithiothreitol. Specific activity values of phosphofructokinase were always lower in permeabilized cells than in haemolysates. A significant inhibition of phosphofructokinase specific activity, without any effect on its allosteric behaviour, is exerted by reaction of dimethyl suberimidate or 3,3'-dithiobispropionimidate with erythrocyte lysates in the presence of an inhibitory concentration of ATP. These results suggest that penetration of the cross-linking reagent and its subsequent reaction with intracellular phosphofructokinase will have a direct effect upon the results obtained using this in situ approach.U 相似文献