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931.
The effect of light, oxygen tension, reducing conditions and thermal shock on egg hatching in Schistosoma mansoni were examined. Hatching was found to be unaffected by light or dark conditions or aerobic or anaerobic conditions. Cold shock from 15 to 120 sec was also ineffective in stimulating hatching. The reducing agents ascorbic acid and cysteine inhibited egg hatching. However, the oxidized forms of these compounds inhibited hatching as well, indicating that the reducing conditions they provided were not responsible for the inhibition. 相似文献
932.
The role of thermal fluctuations in the conformational dynamics of a single closed filament is studied. It is shown that,
due to the interaction between charges and bending degrees of freedom, initially circular chains may undergo transformation
to polygonal shape. 相似文献
933.
Synopsis The preferred temperature of three Hawaiian coral-reef fishes — Acanthurus triostegus sandvicensis, Abudefduf abdominalis, and Chaetodon multicinctus — were determined in two-chambered tanks that permitted the fish to regulate behaviorally tank temperature. Median selected temperatures over 72 h were as follows: adult C. multicinctus, 24.0° C; juvenile C. multicinctus, 27.0° C; adult Ab. abdominalis, 25.9° C; juvenile Ab. abdominalis, 30.2° C; adult Ac. triostegus, 29.2° C; juvenile Ac. triostegus, 29.3° C. Juvenile Ab. abdominalis selected significantly higher median temperatures than the adults. C. multicinctus and juvenile Ab. abdominalis selected higher median temperatures during the day than at night.Based on the senior author's dissertation submitted to the Graduate School of the University of Hawaii in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Oceanography.Contribution No. 555 from the Hawaii Institute of Marine Biology, University of Hawaii, Honolulu, Hawaii. 相似文献
934.
Olga V. Yurchenko Vasily I. Radashevsky Hwey-Lian Hsieh Arkadiy A. Reunov 《Aquatic Ecology》2009,43(2):513-519
The ultrastructure of spermatozoa of the Pacific oysters Crassostrea gigas from an industrially polluted area on the Hsinchu City coast and a relatively clean aquaculture area on Penghu Island, Taiwan,
was studied. Oyster gonads were sectioned and examined with light and transmission electron microscopes. The number of spermatozoa
in the acinus lumen was significantly lower in oysters from the polluted area than that from the relatively clean area (160 ± 33 cells
per 0.01 mm2 against 280 ± 42 cells per 0.01 mm2, respectively, P < 0.01). Oysters from the polluted area on the Hsinchu City coast had 26.6% spermatozoa with damaged acrosome, coarsely granular
chromatin and electron-lucent areas in the nucleus; cell membrane, mitochondria and flagellum were frequently absent in these
spermatozoa. By contrast, oysters from the clean area on Penghu Island had 0.4% spermatozoa with the same impairments. Sea
water temperature and salinity were similar in the two areas, whereas concentrations of nitrogenous nutrients and heavy metals
(e.g., cadmium, copper, and zinc) were higher in the industrially polluted area. It is suggested that high percentage of impairments
in the spermatozoa of oysters from the industrial area is attributable to environmental pollution. 相似文献
935.
Aniela Puszko Anna Krojcer Joanna Wietrzyk Julia Jezierska Maria Kubiak 《Journal of inorganic biochemistry》2010,104(2):153-2286
Three new complexes, products of the interaction of Cu(NO3)2 and methyl-substituted 4-nitropyridine N-oxides were synthesized and characterized by elemental analysis, magnetic, spectroscopic (IR, FIR and EPR), thermal and X-ray methods. The complexes (magnetic moments 1.70-1.81 BM at 300 K) of general formula [Cu(H2O)(NO3)2L2], L = 2-methyl-4-nitropyridine N-oxide and [Cu(NO3)2 L′2], where L′ = 2,6-dimethyl- and 2,3,6-trimethyl-4-nitropyridine N-oxide were obtained. The compounds were unstable upon dissolution. The X-ray single crystal structure of Cu(II) complex with 2,6-dimethyl-4-nitropyridine N-oxide was determined and analysed. The compounds and free ligands were tested in vitro on the cytotoxic activity against MCF-7 and SW-707 human cancer cell lines. The complexes with 4-nitropyridine N-oxide (a reference) and 2-methyl-4-nitropyridine N-oxide show a significant anti-proliferative activity against studied cell lines. A reciprocal relationship between the activity and the number of methyl groups was observed. Both ligands and complexes are cytotoxic active but to the different cell lines. 相似文献
936.
Abhishek Srivastava 《Biochemical and biophysical research communications》2010,395(3):348-351
Arginase is a binuclear Mn2+-metalloenzyme of urea cycle that hydrolyses arginine to ornithine and urea. Unlike other arginases, the Helicobacter pylori enzyme is selective for Co2+. Previous study reported that DTT strongly inhibits the H. pylori enzyme activity suggesting that a disulphide bond is critical for the catalysis. In this study, we have undertaken steady-state kinetics, circular dichroism and mutational analysis to examine the role of a disulphide bond in this protein. By mutational analysis, we show that the disulphide bond is not important for catalytic activity; rather it plays an important role for the stability of the protein as observed from thermal denaturation studies. The loss of catalytic activity in the wild-type protein with DTT is due to the interaction with Co2+. This is verified with the Mn2+-reconstituted proteins which showed a marginal loss in the activity with DTT. 相似文献
937.
938.
As part of the ongoing effort to study the mechanical behavior of biological materials in cryopreservation processes, the current study focuses on thermal expansion during vitrification (vitreous in Latin means glassy). A new device is utilized in this study, which has been described in detail in the companion paper (Part I). The current study (Part II) focuses on measurements of vitrified blood vessels permeated with the cryoprotectants VS55, DP6, and DMSO. Data analysis in this study includes polynomial approximation of experimental results in the lower part of the cryogenic temperature range, where the material behaves as solid over a practical time scale. The study further includes a unified thermal expansion analysis throughout the entire cryogenic temperature range by compiling the current results with previously reported data. Finally, analysis of the glass transition temperature, based on thermal strain data is presented. 相似文献
939.
940.
Benoit I Asther M Sulzenbacher G Record E Marmuse L Parsiegla G Gimbert I Asther M Bignon C 《FEBS letters》2006,580(25):5815-5821
The thermal stability of four molecular forms (native, refolded, glycosylated, non-glycosylated) of feruloyl esterase A (FAEA) was studied. From the most to the least thermo-resistant, the four molecular species ranked as follows: (i) glycosylated form produced native, (ii) non-glycosylated form produced native, (iii) non-glycosylated form produced as inclusion bodies and refolded, and (iv) glycosylated form produced native chemically denatured and then refolded. On the basis of these results and of crystal structure data, we discuss the respective importance of protein folding and glycosylation in the thermal stability of recombinant FAEA. 相似文献