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611.
Raffaele Porta Marina Camardella Vittorio Gentile Antonio De Santis 《Journal of neurochemistry》1984,42(2):321-325
Since a specific inhibition of cerebral spermidine (Spd) synthase activity by alicyclic amines was preliminarily observed in vitro, we examined the in vivo inhibitory effectiveness of dicyclohexylamine (DCHA) on Spd biosynthesis in 21-day-old rat brain. For this purpose a previously reported HPLC procedure (Porta et al., 1981a) was modified to analyze the cerebral levels of DCHA at the time of polyamine determinations. The intraperitoneally injected DCHA was shown to cross the blood-brain barrier easily, reaching high levels in the cerebral tissue (approximately 750 nmol/g brain) within 1 h of its administration. The effect of the drug on the polyamine metabolism resulted in a significant depletion of Spd biosynthesis from the sixth hour after the treatment and in an earlier and prolonged increase of the putrescine (Pt) steady-state levels. Conversely, the spermine (Spm) endogenous pools remained unchanged throughout the 24-h post-DCHA period. Moreover, following the intracerebral administration of [1,4-14C]Pt, significantly lower specific radioactivity (s.r.a.) values for labeled Pt and Spd were recorded in the brains of DCHA-treated animals. Conversely, after intracerebral [14C]Spd injection, the s.r.a. of newly formed [14C]Spm remained unchanged, confirming the specificity of the DCHA effect on the Spd biosynthesis. 相似文献
612.
Stefania Bennici Gaetano Distefano Giuseppina Las Casas Mario Di Guardo Giuseppe Lana Ettore Pacini Stefano La Malfa Alessandra Gentile 《The Annals of applied biology》2019,175(1):29-41
Male gametophyte development is a critical phase of the plant life cycle due to its high sensitivity to environmental stresses. The rise in the average global temperature, often accompanied by extreme fluctuations, has an important impact on biological processes. Among those, male gametophytes are particularly sensitive to temperature stress during flower bud development and anthesis. Male gametophyte development was extensively studied in several plant species, but little information is available about the effects of temperature stress on male gametophyte development in the genus Citrus. We evaluated the effects of cold and hot temperatures during microsporogenesis and microgametogenesis on one of the most economically valuable citrus species, the “Comune” clementine (Citrus clementina Hort. ex. Tan.). The effect of constant temperature on the androecium was evaluated by a time course histological analysis performed on the anthers and by monitoring in vitro pollen germination. The results revealed how suboptimal hot and cold temperatures induce drastic alterations on the morphology of the tapetal cells, microspores and mature pollen grains. Shifting from the optimal temperature affected the timing of starch depletion in the anther walls, such as epidermis, endothecium and middle layer, influencing the pollen germination rate and pollen tube growth. To the best of our knowledge this is the first study attempting to assess how temperature stress affects male reproductive development in citrus. A better understanding of the mechanisms underlining male sterility will provide novel insights to elucidate the physiology of this agronomical important quality trait. 相似文献
613.
Andrea Delpino Francesco Paolo Gentile Francesca Di Modugno Marcello Benassi Anna Maria Mileo Elisabetta Mattei 《Radiation and environmental biophysics》1992,31(4):323-332
M-14 human tumor cells have been subjected to two regimens of step-down heating (SDH) consisting of a conditioning treatment at 42 degrees C for 1 h or at 44.5 degrees C for 20 min, immediately followed by heating at 40 degrees C. Both conditioning treatments thermosensitize the cells towards the subsequent heating at 40 degrees C; the thermosensitization ratio is 6.4 for cells conditioned at 42 degrees C for 1 h and 32.3 for cells conditioned at 44.5 degrees C for 20 min. The overall protein synthetic activity is reduced to 32.7% or 18.4% of control values following 1 h at 42 degrees C and 20 min at 44.5 degrees C, respectively; this inhibition is followed by a full recovery of the synthetic activity during the subsequent exposure at 40 degrees C. SDH-treated cells synthetize four heat shock proteins, with approximate molecular weights of 28, 64, 70 and 90 kDa. The pattern of HSPs induction observed in SDH-treated cells is similar to that found in cells subjected to single hyperthermic exposures. Cells subjected to the SDH sequence 42 degrees C/1 h-->40 degrees C/4 h develop thermotolerance, as indicated by a reduced sensitivity to further hyperthermic challenges. 相似文献
614.
P Fattoretti C Viticchi G Cognini S Gentile L Piantanelli 《Bollettino della Società italiana di biologia sperimentale》1980,56(23):2421-2427
Beta-adrenergic receptors from submandibular glands of mice were studied by equilibrium binding experiments. Due to the fact that some discrepancies were previously observed among different author data, we compared two methods for non specific binding substruction, that represents the major source of errors in such experiments. Data were obtained strongly suggesting the presence of multiple population of binding sites and/or negative cooperativity. 相似文献
615.
616.