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661.
Superoxide dismutase (SOD, EC 1.15.1.1) was identified from ripening cucumber ( Cucumis sativus L.) and pepper( Capsicum annuum L.) fruits, Gel filtration revealed the presence of two major peaks of SOD with molecular masses of about 32 000 and 40 000. Peroxidase activity was observed mainly in material with a molecular mass above 70 000. SOD activity was inhibited by cyanide but not by chloroform-ethanol, indicating a cupro-zinc enzyme. SOD activity levels were high in immature-green fruits of both species, declining in cucumbers to a minimum during the mature-green stage and in peppers during the mature-green and breaker stages. SOD levels increased again until peppers became orange and cucumbers turned yellow, and finally decreased with ripening. The possible connection between SOD activity and tolerance to sunscald is discussed. 相似文献
662.
F. H. Wolfson 《Journal of fish biology》1983,22(6):647-655
Seven juvenile whale sharks ranging from 550 to 930 mm in length are reported. Measurements of six are tabulated with remeasurements of the single known embryo. The mode of reproduction of this shark is again questioned, and the lack of records of sizes between 1 and almost 4 m is discussed. 相似文献
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664.
Currently, one of the most disputed hypotheses regarding breast cancer (BC) development is exposure to short wavelength artificial light at night (ALAN) as multiple studies suggest a possible link between them. This link is suggested to be mediated by nocturnal melatonin suppression that plays an integral role in circadian regulations including cell division. The objective of the research was to evaluate effects of 1 × 30 min/midnight ALAN (134 µ Wcm?2, 460 nm) with or without nocturnal melatonin supplement on tumor development and epigenetic responses in 4T1 tumor-bearing BALB/c mice. Mice were monitored for body mass (Wb) and tumor volume for 3 weeks and thereafter urine samples were collected at regular intervals for determining daily rhythms of 6-sulfatoxymelatonin (6-SMT). Finally, mice were sacrificed and the tumor, lungs, liver, and spleen were excised for analyzing the total activity of DNA methyltransferases (DNMT) and global DNA methylation (GDM) levels. Mice exposed to ALAN significantly reduced 6-SMT levels and increased Wb, tumor volume, and lung metastasis compared with controls. These effects were diminished by melatonin. The DNMT activity and GDM levels showed tissue-specific response. The enzymatic activity and GDM levels were lower in tumor and liver and higher in spleen and lungs under ALAN compared with controls. Our results suggest that ALAN disrupts the melatonin rhythm and potentially leading to increased BC burden by affecting DNMT activity and GDM levels. These data may also be applicable to early detection and management of BC by monitoring melatonin and GDM levels as early biomarker of ALAN circadian disruption. 相似文献
665.
Valinomycin blocks protein synthesis at the elongation stage in intact reticulocyte while being without action on a cell free system. We demonstrate here that this membrane mediated inhibition is accompanied by a change of the energy charge (ATP/ADP/AMP ratio) of the cells. There seems to be an accumulation of AMP without a proportional gain in ADP. The change in energy charge in itself can be the cause of the inhibition of protein synthesis. We show also that valinomycin can cause a decrease of the energy charge at concentrations where its action as an ionophore is not seen and independent of a possible activation of the Na-K dependent ATPase.Present address: Meir Hospital, Kfar Saba, Israel 相似文献
666.
Organomercurials, p-chloromercuribenzoate and p-chloromercuriphenyl sulfonate, had very little influence on the viability and subsequent growth of the free-living protozoan treated at 0.01 mM or less for 1 hr in inorganic medium. Heat-synchronized treated in this fashion at intervals during the synchronization procedure retained 0.05 picomoles mercurial/cell. The heat-synchronized cells released mercury-binding substance to the inorganic medium, beginning with 0.07 picomoles/cell in 1 hr for cells treated during the first half of the synchronization procedure and increasing in the second half to release 0.24 picomoles/cell just before fission. This represents the release of substantial amounts of soluble sulfhydryls by cells preparing to divide. 相似文献
667.
Carmel Bilu Haim Einat Katy Tal-Krivisky Joseph Mizrahi Vicktoria Vishnevskia-Dai Galila Agam 《Chronobiology international》2019,36(7):919-926
Despite the common use of bright light exposure for treatment of seasonal affective disorder (SAD), the underlying biology of the therapeutic effect is not clear. Moreover, there is a debate regarding the most efficacious wavelength of light for treatment. Whereas according to the traditional approach full-spectrum light is used, recent studies suggest that the critical wavelengths are within the range of blue light (460 and 484 nm). Our previous work shows that when diurnal rodents are maintained under short photoperiod they develop depression- and anxiety-like behavioral phenotype that is ameliorated by treatment with wide-spectrum bright light exposure (2500 lux at the cage, 5000 K). Our current study compares the effect of bright wide-spectrum (3,000 lux, wavelength 420- 780 nm, 5487 K), blue (1,300 lux, wavelength 420-530 nm) and red light (1,300 lux, wavelength range 600-780 nm) exposure in the fat sand rat (Psammomys Obesus) model of SAD. We report results of experiments with six groups of sand rats that were kept under various photoperiods and light treatments, and subjected to behavioral tests related to emotions: forced swim test, elevated plus maze and social interactions. Exposure to either intense wide-spectrum white light or to blue light equally ameliorated depression-like behavior whereas red light had no effect. Bright wide-spectrum white light treatment had no effect on animals maintained under neutral photoperiod, meaning that light exposure was only effective in the pathological-like state. The resemblance between the effects of bright white light and blue light suggests that intrinsically photosensitive retinal ganglion cells (ipRGCs) are involved in the underlying biology of SAD and light therapy. 相似文献
668.
David Cahen Gerard Bults Haim Garty Shmuel Malkin 《Journal of biochemical and biophysical methods》1980,3(5):293-310
Photoacoustic (PA) measurements provide, by the very nature of the PA effect, the possibility to obtain information on the optical and thermal properties of samples. In addition they can yield information on the enthalpy changes and characteristic times involved in photo-induced processes as the acoustic signal in proportional to the heat produced following the absorption of the modulated excitation. In the study of optical properties the relative insensitivity to scattered light of the PA signal makes such measurement an attractive way to measure biological samples in vivo, or, at least, withpout the need to isolated the absorbing compounds. The dependence of the PA signal on the thermal properties of the sample is particularly useful when heterogeneous samples are studied. As a photocalorimetric method the technique shows considerable promise in the study of photo-biogenergetics, especially photosynthesis. Only in special cases can analytical applications of the method compete with fluorescence measurements (for detection), and with increasingly sophisticated optical transmission and reflectance techniques (for identification). However, the PA method may find important uses in fundamental research and in applied areas such as biomedicine and agricultural biochemistry. 相似文献
669.
670.