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141.
The protective effects of melatonin, vitamin E, and selenium alone or in combination were tested against cadmium-induced oxidative
damage in rat testes. A total of 60 male rats were equally divided into five study groups, one of which acted as control receiving
subcutaneous injections of physiological saline. The remaining four groups were treated with subcutaneous injections of cadmium
chloride at a dose of 1 mg/kg weight. The first study group received no treatment. The second group was treated with a combination
of 60 mg/kg vitamin E and 1 mg/kg sodium selenite. Group 3 was treated with 10 mg/kg melatonin, and the fourth group received
a combination of vitamin E, sodium selenite, and melatonin at the doses mentioned above. After 1 month, the animals were killed,
and the testes were excised for histological inspection and determination of tissue malondialdehyde and the activity of superoxide
dismutase. The animals receiving no treatment showed significantly higher malondialdehyde levels and reduced activity of the
enzyme (p < 0.05). Treatment with antioxidants resulted in a significant reduction in malondialdehyde when compared to the nontreated
animals (p < 0.05) and an increase in the superoxide dismutase activity that was almost the same as the controls. The combination of
melatonin, vitamin E, and selenium appears to have the more profound effect against cadmium-induced testicular injury. 相似文献
142.
The present study was carried to evaluate the protective effects of melatonin alone and vitamin E with selenium combination
against high dose cadmium-induced oxidative stress in rats. The control group received subcutanous physiological saline. The
first study group administered cadmium chloride (CdCl2) by subcutaneous injection of dose of 1 mg/kg. The second study group administered cadmium plus vitamin E with selenium (1 mg/kg
sodium selenite with 60 mg/kg vitamin E); the third study group administered cadmium plus 10 mg/kg melatonin (MLT); the fourth
study group administered CdCl2 plus a combination of melatonin in addition to vitamin E and selenium for a month. Determination levels of plasma malondialdehyde
(MDA), glutathione peroxidase (GSH-Px), blood superoxide dismutase (SOD), creatinine alanine transaminase (ALT), aspartate
aminotransferase (AST), alkaline phosphatase (ALP), blood urea nitrogen (BUN), and urea were measured in serum. In only CdCl2 administered group, the MDA, creatinine, ALT, AST, ALP, and urea levels in the serum were significantly higher than the control
group (p < 0.05). Whereas in all other groups, this values were significantly lower than the only CdCl2 administered group (p < 0.05). Erythrocytes GSH-Px, serum SOD activities of only CdCl2 received group were significantly lower than the control group (p < 0.05). In conclusion, vitamin E + Se, melatonin and vitamin E, and Se, in addition to MLT combinations, had protective
effects against high dose cadmium-induced oxidative damage. 相似文献
143.
To elucidate the role of low molecular weight chelators in long-distance root-to-shoot transport of heavy metals in Indian
mustard, an “off-line” size exclusion high-performance liquid chromatography–graphite furnace atomic absorption spectrometry
was developed to investigate heavy metals associated with low molecular weight chelators in xylem saps of Indian mustard (Brassica juncea). The size exclusion chromatogram presented only the peaks with molecular weight for all xylem saps and directly indicated
the long-distance transport of phytochelatins (PCs) of Indian mustard under Cd stress. In the absence of Cd stress, only organic
acids and inorganic anions participated in the long-distance transport of Cd, but organic acids, inorganic anions, glutathione
(GSH), and cysteine might relate to the long-distance transport of Cu or Zn. In the presence of Cd stress, PCs were induced,
and Cd ions in xylem saps were associated with the induced PCs. As the Cd levels in nutrient solution increased, more Cd in
xylem saps adopted the form of PC–Cd. Although PCs might participate in the long-distance transport of Cd under Cd stress,
the majority of Cd was still transported by organic acids and inorganic anions in xylem vessels. Moreover, results indicated
the existence of complexation competition for GSH and cysteine between Cd and Cu (or Zn) and complexation competition for
Cd between PCs and GSH (or cysteine) in xylem vessels. Our work might be very useful for understanding the mechanism of long-distance
transport of heavy metals in hyperaccumulator. 相似文献
144.
Ultrastructural changes in the kidneys of rats after acute cadmium exposure and the effects of exogenous metallothionein (MT)
were studied by transmission electron microscopy. Thirty-six adult Wistar rats were divided into three groups. Cadmium chloride
(CdCl2) (3.5 mg/kg/day) was injected subcutaneously in the first group. In the second group, 30 μmol/kg MT was administered in addition
to CdCl2. Control rats received 0.5 ml subcutaneous saline solution. Four rats from each group were killed on days 1, 3, 5, and 7
after administration of the compounds. Kidney tissues were taken and fixed in 2.5% glutaraldehyde solution for electron microscopic
observations. Tissue damage in kidney increased as time passed since the administration of CdCl2 in the first group. Degeneration in the proximal and distal tubules was observed. Increased apoptosis was seen in the proximal
tubules epithelium, especially on day 7. Peritubular capillaries became dilated, there was degeneration of the endothelial
cells, and the amount of intertubular collagen fibers was increased. On day 1, irregular microvilli in the proximal tubules,
deepening of the basal striations, and myelin figures; on day 3, multiple vesicular mitochondria and regions of edema around
tubules; on days 5 and 7, increased apoptotic cell in the proximal tubules and widened rough endoplasmic reticulum of the
endothelial cells of glomerular capillaries were observed. We observed that the structural alterations that increased depending
on the day of Cd administration decreased after exogenous MT administration, the dilation of the peritubular capillaries persisted,
and there were degenerated proximal tubules. It was established that cadmium chloride was toxic for kidney cortex and caused
structural damage. Exogenous MT partly prevents CdCl2-induced damage. 相似文献
145.
Water use efficiency of twenty-five co-existing Patagonian species growing under different soil water availability 总被引:2,自引:0,他引:2
The variation of plant water use efficiency (WUE) with water availability has two interacting components: a plastic response,
evident when individuals of the same genotype are compared (e.g. wet versus dry years), and an interspecific response, evident
when different species living in habitats with different water availability are compared. We analysed the WUE of 25 Patagonian
species that belong to four life forms (grasses, shrubs, annual herbs and perennial herbs) in relation to the climatic conditions
of 2 years and the mean historic water availability experienced by each species. To estimate water availability, we calculated
the effective soil water potential (EWP) of each species, based on available information about soil water dynamics, phenology
and root system structure. To estimate WUE, we used isotopic discrimination of leaf C (Δ13C) and mean annual water vapour difference between leaves and atmosphere (Δe) measured in situ. For the plastic response, for every species and life form, WUE increased from the dry to the wet year.
We hypothesize that photosynthesis was less nutrient limited in the wet than in the dry year, facilitating higher net photosynthesis
rates per unit of stomatal conductance in the wet year. For the interspecific response, WUE was lower in species native to
drier habitats than in species native to wetter habitats. This response was mostly accounted for by a decrease in Δe with EWP. Annual herbs, which avoid drought in time (they have the earliest growth cycle), and shrubs, which avoid drought
in space (they have the deepest roots), showed the highest EWP and WUE. We conclude that the conventional wisdom which states
that the highest WUE occurs within a species during the driest years, and among species in the driest habitats, does not always
hold true, and that co-existing life forms drastically differ in water availability and water economy. 相似文献
146.
Rice (Oryza sativa L.) seedlings stressed with CdCl2 (0.5 mM or 50 μM) showed typical Cd toxicity (leaf chlorosis, decrease in chlorophyll content, or increase in H2O2 and malondialdehyde contents). Rice seedlings pretreated with heat shock at 45°C (HS) for 2 or 3 h were protected against
subsequent Cd stress. Rice seedlings pretreated with HS had similar Cd concentration in leaves caused by CdCl2 as those non-HS. The content of H2O2 increased in leaves 1 h after HS exposure. However, APX and GR activities were higher in HS-treated leaves than their respective
control, and it occurred after 2 h of HS treatment. Pretreatment of rice seedlings with H2O2 under non-HS conditions resulted in an increase in APX, GR, and CAT activities and protected rice seedlings from subsequent
Cd stress. HS-induced H2O2 production and protection against subsequent Cd stress can be counteracted by imidazole, an inhibitor of NADPH oxidase complex.
Results of the present study suggest that early accumulation of H2O2 during HS signals the increase in APX and GR activities, which in turn prevents rice seedlings from Cd-caused oxidative damage. 相似文献
147.
Starch-branching enzymes (SBEs) play a pivotal role in determining the fine structure of starch by catalyzing the syntheses of alpha-1,6-branch points. They are the members of the alpha-amylase family and have four conserved regions in a central (beta/alpha)8 barrel, including the catalytic sites. Although the role of the catalytic barrel domain of an SBE is known, that of its N- and C-terminal regions remain unclear. We have previously shown that the C-terminal regions of the two SBE isozymes (designated as PvSBE1 and PvSBE2) from kidney bean (Phaseolus vulgaris L.) have different roles in branching enzyme activity. To understand the contribution of the N-terminal region to catalysis, six chimeric enzymes were constructed between PvSBE1 and PvSBE2. Only one enzyme (1Na/2Nb)-II, in which a portion of the N-terminal region of PvSBE2 was substituted by the corresponding region of PvSBE1, retained 6% of the PvSBE2 activity. The N-terminal truncated form (DeltaN46-PvSBE2), lacking 46 N-terminal residues of PvSBE2, lost enzyme activity and stability to proteolysis. To investigate the possible function of this region, three residues (Asp-15, His-24, and Arg-28) among these 46 residues were subjected to site-directed mutagenesis. The purified mutant enzymes showed nearly the same K(m) values as PvSBE2 but had lower V(max) values and heat stabilities than PvSBE2. These results suggest that the N-terminal region of the kidney bean SBE is essential for maximum enzyme activity and thermostability. 相似文献
148.
Bowman-birk proteinase inhibitor confers heavy metal and multiple drug tolerance in yeast 总被引:1,自引:0,他引:1
Cultured Coptis japonica cells show tolerance to various toxic compounds. By yeast functional screening of cadmium (Cd) plates with its cDNA library, we isolated a gene encoding Bowman-Birk proteinase inhibitor (CjBBI). The yeast transformant of CjBBI showed multiple tolerance to various drugs adding to Cd, and revealed reduced Cd accumulation in cells. Preferential organs for Cjbbi expression were aerial parts of intact plants, and the subcellular localization of CjBBI was shown, using its green fluorescent protein fusion, to be the apoplast. Induction of Cjbbi expression by Cd treatment suggested that CjBBI was responsible for the tolerance to Cd observed in C. japonica cells. 相似文献
149.
Role of roots in differences in seed cadmium concentration among soybean cultivars—proof by grafting experiment 总被引:2,自引:0,他引:2
Soybean cultivars show significant differences in cadmium (Cd) concentrations in seeds, due primarily to genetics, not environmental
factors. We previously suggested that low-Cd cultivars accumulate Cd in their roots and thus prevent its translocation to
the rest of the plant. Through grafting experiments, we drew the following conclusions about Cd absorption and translocation:
(1) The amount of Cd accumulated in shoots is determined by the Cd accumulation capacity of roots: cultivars with a small
capacity to accumulate Cd in roots translocate more Cd and accumulate it in shoots; (2) The Cd concentration in shoots is
determined by the Cd accumulation capacity of roots and the shoot productive ability of the scion cultivar; (3) The Cd tolerance
of shoots differs among cultivars. Enrei, with a high-Cd accumulation capacity of roots, had a low Cd tolerance of shoots
compared with Suzuyutaka and Hatayutaka, with a low Cd accumulation capacity of roots; (4) Cultivars differ in their distribution
of Cd to seed; (5) These results show that seed Cd concentration is influenced by the differences among cultivars in ease
of translocation of Cd to seed and in Cd accumulation capacity of roots. 相似文献
150.
Katarína Ďurčeková Jana Huttová Igor Mistrík Marta Ollé Ladislav Tamás 《Plant and Soil》2007,290(1-2):61-68
The effect of Cd on H2O2 production, peroxidase (POD) activity and root hair formation were analyzed in barley root. Cd causes a strong H2O2 burst in the root region 0–6 mm behind the root tip. POD activity was activated in root tip and raised toward the root base
in Cd treated roots. In situ analyses showed that both elevated H2O2 production and POD activity are localized in the early metaxylem vascular bundles. Cd induces root hair formation in the
region 2 to 4 mm behind the root tip that was not detected in control roots. These results suggest that Cd-induced root growth
inhibition is at least partially the consequence of Cd-stimulated premature root development involving xylogenesis and root
hair formation, which is correlated with shortening of root elongation zone and therefore with root growth reduction. 相似文献