Floristic composition, life forms for C4 species, and the pattern of altitude distribution were studied on Tibetan Plateau. 79 species, in 7 families and 46 genera, were identified with C4 photosynthesis. 95 % of these C4 species belong to Gramineae (51 species), Cyperaceae (14 species), and Chenopodiaceae (10 species), indicating that C4 plants mainly occur in very few families (7 of 204) on the Tibetan Plateau. High altitude distribution for all the Chenopodiaceae C4 species (> 3 000 m above sea level) suggests that plants of this kind have large tolerance to cold, dryness, and strong ultraviolet radiation. Most Gramineae and Cyperaceae C4 species occurrences are consistent with extensive distribution of steppes and meadows in the vast flat of the central Plateau (1 000-3 000 m a.s.l.). Relatively high amount of hemicryptophyte form plants (44 %) in the region indicates that the vegetation, especially grassland, meadows, and steppe, are in good condition. There is a strong relationship between numbers of C4 species and altitude in the Tibetan Plateau. Occurrence of C4 species is significantly less in both high and low altitude plateaux in Tibet. Altitude distribution pattern for C4 species in the region is not only consistent with the altitude and climate, but also with the vegetation types in altitude gradient.
Natural occurrence of C4 species, life forms, and their longitudinal distribution patterns along the Northeast China Transect (NECT) were studied. Six vegetation regions experiencing similar irradiation regimes, but differing in longitude, precipitation, and altitude were selected along the NECT from 108 to 131 °E, around altitude of 43.5 °N. Seventy C4 species were identified in 41 genera and 13 families. 84 % of the total C4 species were found in four families: Gramineae (38 species), Chenopodiaceae (11 species), Cyperaceae (5 species), and Amaranthaceae (5 species). C4 grasses make up 54 % of the total identified C4 species along the NECT and form the leading C4 family in meadow, steppe, and desert along the NECT. C4Chenopodiaceae species make up about 16 % of the C4 species and become less important, particularly in the meadow and the eastern end of the NECT. 57 % of the total C4 species are therophytes and 37 % are hemicryptophytes, which is consistent with floristic composition and land utilization. In general, the number of C4 species decreased significantly from the west to the east or from dry to moist areas along the NECT, and was remarkably correlated with annual precipitation (r2= 0.677) and aridity (r2= 0.912), except for salinized meadow region. The proportion of C4 species from all the six vegetation regions was considerably correlated with these two climatic parameters (r2= 0.626 or 0.706, respectively). These findings suggest that the natural occurrence of C4 species varies significantly along the large-scale longitudinal gradient of the NECT. The notable relationship of C4 species number and proportion in the flora with variations in annual precipitation and aridity suggest that these two climatic parameters are the main factors controlling the longitudinal distribution patterns of C4 species along the NECT.
We determined and characterized the Mg2+-dependent, Ca2+-stimulated ATPase (Ca-ATPase) activity in cell plasma membranes from the myometrium of pregnant women, and compared these characteristics to those of the active Ca2+-transport already demonstrated in this tissue. Similarly to the Ca2+-transport system, the Ca2+-ATPase is Mg2+-dependent, stimulated by calmodulin, and inhibited by vanadate. The Km for Ca2+ activation is 0.40 m M, very similar to that found for active calcium transport, i.e. 0.25 m M. Consequently, this Ca2+-ATPase can be responsible for the active calcium transport across the plasma membranes of smooth muscle cells., F. Carrera, T. Proverbio, R. Marín, F. Proverbio., and Obsahuje bibliografii
Plants of Indian mustard (Brassica juncea) were treated with either 50 µM Cd, 250 µM Zn, or 25 µM Cd+125 µM Zn and the progression of chlorosis in the mature leaves monitored. As relative chlorophyll (Chl) contents in the mature leaves decreased to 75, 50, and 25 % relative to controls, both mature and young leaves were harvested and the Chl pools extracted. The metal treatments caused a greater loss of Chl b than Chl a. As mature leaves underwent progressive chlorosis, the young leaves displayed a characteristic over-greening, due largely to increased content of Chl b. However, as the young leaves began to experience chlorosis, a greater loss of Chl b was also observed. Thus during metal induced chlorosis, there is a preferential turnover of the Chl b pool in mature and young leaves. and S. Ebbs, S. Uchil.
The present study was devised to assess the effects of cadmium chloride (CdCl2) administration on certain andrological, endocrinological and biochemical alterations in adult male rabbits (n=24). The animals were assigned to control (n=8) and experimental (n=16) group. Experimental group was orally administered with 1.5 mg/kg body weight of CdCl2. The trials were carried out for a total of 5 weeks and blood sampling was carried out on weekly basis. A gradual decrease was noticed for body weight in the experimental group from week 1 to 5, being significantly lower in week 4 and 5 (P<0.05). A similar decremented trend was noticed for serum testosterone level being significantly lower in experimental group in week 4 and 5 (P<0.001). Significantly lower values were noticed for prolactin in experimental group in week 4 and 5 (P<0.05), than in the control. On the contrary, serum cortisol level showed a gradual increase in experimental group, from week 1 to 5, being significantly higher in week 4 and 5 (P<0.05). Regarding the biochemical attributes, all the parameters under study revealed a gradually ascending trend. Statistical significance was, however, achieved in varying weeks and at varying levels. The total protein and albumin were significantly higher in week 4 and 5 (P<0.01); alanine aminotransferase in week 2 (P<0.01), 3 (P<0.001), 4 (P<0.01) and 5 (P<0.001); aspartate aminotransferase in week 1, 2, 3, 4 and 5 (P<0.01); and alkaline phosphatase in week 1, 2 (P<0.01), 3, 4 and 5 (P<0.0001), respectively. Overall mortality rate in experimental group was 68.75 (11/16). In a nutshell, Cd exposure results in adverse effects on all physiological parameters of body and may lead to lethal consequences., S. Sajjad, H. Malik, U. Farooq, F. Rashid, H. Nasim, S. Tariq, S. Rehman., and Obsahuje bibliografii
The ultrastructure of cells of ground meristem in the peripheral zone of shoot apical meristem in Elodea canadensis Rich. was studied after treatment with cadmium in concentrations 0.5, 1, 2, 3, 5, and 6 g(Cd2+) m-3. After 5 d treatment, changes in the structural organisation of the plastid apparatus were found, namely in proplastid, amyloplast, and amoeboid stages of plastid development. and D. Stoyanova, E. Tchakalova.
We studied cadmium toxicity in murine hepatocytes in vitro. Cadmium effects on intracellular free Ca2+ concentration ([Ca2+]i) were assayed, using a laser scanning confocal microscope with a fluorescent probe, Fluo-3/AM. The results showed that administration of cadmium chloride (CdCl2, 5, 10, 25 μM) resulted in a dose-dependent decrease of hepatocyte viability and an elevated aspartate aminotransfe rase (AST) activity in the culture medium (p<0.05 for 25 μM CdCl2 vs. control). Significant increases of lactate dehydrogenase (LDH) activities in 10 and 25 μM CdCl2-exposed groups were observed (p<0.05 and p<0.01, respectively). A greatly decreased albumin content and a more malondialdehyde (MDA) formation also occurred after CdCl2 treatment. The Ca2+ concentrations in the culture medium of CdCl2-exposed hepatocytes were significantly decreased, while [Ca2+]i appeared to be significantly elevated (p<0.05 or p<0.01 vs. control). We found that in Ca2+-containing hydroxyethyl piperazine ethanesulfonic acid-buffered salt solution (HBSS) only, CdCl2 elicited [Ca2+]i increases, which comprised an initially slow ascent and a strong elevated phase. However, in Ca2+-containing HBSS with addition of 2-aminoethoxydiphenyl borane (2-APB), CdCl2 caused a mild [Ca 2+] i elevation in the absence of an initial rise phase. Removal of extracellular Ca2+ showed that CdCl2 induced an initially slow [Ca2+]i rise alone without being followed by a markedly elevated phase, but in a Ca2+-free HBSS with addition of 2-APB, CdCl2 failed to elicit the [Ca2+]i elevation. These results suggest that abnormal Ca2+ homeostasis due to cadmium may be an important mechanism of the development of the toxic effect in murine hepatocytes. [Ca2+]i elevation in acutely cadmium-exposed hepatocytes is closely related to the extracellular Ca2+ entry and an excessive release of Ca2+ from intracellular stores., S. S. Wang, L. Chen, S. K. Xia., and Obsahuje bibliografii a bibliografické odkazy
In order to understand better Cd resistance in soybean, Dongying wild soybean treated with different Cd concentrations were evaluated. The biomass, chlorophyll (Chl) content, leaf color, Chl a fluorescence parameters, photosynthesis parameters, and Cd contents were determined. Our results showed that when Cd concentration was ≤ 2 kg m-3, no significant decrease in biomass, photosynthetic parameters, and maximal photochemical efficiency of PSII was observed. This indicated that Dongying wild soybean resisted Cd toxic effects under such conditions. In addition, atomic absorption experiment results demonstrated that when Cd concentration was ≤ 0.5 kg m-3, the accumulation of Cd in wild soybean was lower in roots than that in shoots, while the accumulation of Cd was higher in roots than that in shoots when Cd concentration was ≥ 1 kg m-3. Therefore, Dongying wild soybean showed a certain resistance to Cd and could serve as a valuable germplasm resource for improving the breeding of
Cd-resistant soybean., L. Liu, Y. K. Shang, L. Li, Y. H. Chen, Z. Z. Qin, L. J. Zhou, M. Yuan, C. B. Ding, J. Liu, Y. Huang, R. W. Yang, Y. H. Zhou, J. Q. Liao., and Obsahuje bibliografii