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141.
Résumé La teneur en glutamine dans le cerveau des chatons nouveau-nés au cours de la maturation cérébrale est comparable à celle des animaux adultes. Les concentrations en acide glutamique et en GABA augmentent et vers la fin du premier mois postnatal correspondent au niveau des adultes. 相似文献
142.
Summary On the basis of experimental evidence, it is proved that phthalyl urea has the structure II, and not structure I, proposed byPiutti and generally accepted by other investigators. 相似文献
143.
G. Nikezić A. Horvat N. Nedeljković J. V. Martinović 《Cellular and molecular life sciences : CMLS》1996,52(3):217-220
Effects of 17-estradiol (E2) in vitro on Na-dependent Ca2+ efflux from, and depolarization-induced Ca2+ uptake into, the nerve cell were studied with the use of synaptosomes isolated from the brain stem, mesencephalic reticular formation (MRF), caudate nucleus and the hippocampus of long-term ovariectomized adult female rats. It was found that E2 (1) at a concentration of 10 nM or lower, stimulates Na-dependent Ca2+ efflux in the caudate nucleus and hippocampus, and does not affect the efflux in MRF and brain stem; (2) at concentrations above 10 nM has no effect on the Ca2+ efflux in any of the four structures investigated; and (3) produces a biphasic effect on the depolarization-induced Ca2+ uptake, increasing it in all structures except MRF at 10 nM concentration, and decreasing it at concentrations higher than 10 nM, irrespective of the structure investigated. These results suggest that E2, acting at extranuclear sites, modulates synaptic transmission via alterations of Ca2+ transport mechanisms in nerve endings. 相似文献
144.
Summary Thymectomized, lethally irradiated rats reconstituted with syngeneic bone marrow were injected with rat brain in complete Freund adjuvant mixture. Both, they and sham-thymectomized, irradiated and bone marrow protected rats displayed a higher incidence of leg paralysis than normal non-irradiated animals. Thymectomy lowered the incidence of the disease.Supported by the Research Fund of Croatia (Zagreb). 相似文献
145.
A2 adenosine receptors were characterized in human glomerular mesangial cells using [3H] 5-N-ethylcarboxamidoadenosine (NECA) as a tracer. There was a single group of receptor sites with a KD of 184 nM, and a number of sites of 317 fmol/mg of cell protein. Adenosine agonists increased 5-nucleotidase activity via A2 receptor stimulation. The specific A2 agonist-NECA, at 0.1 and 1 m, was a potent inhibitor of DNA synthesis. 相似文献
146.
The answer to the fine-tuning problem of the universe has been traditionally sought in terms of either design or multiverse. In philosophy circles, this is sometimes expanded by adding the option of explanatory nihilism—the claim that there is no explanation for statements of that high level of generality: fine-tunings are brute facts. In this paper, we consider the fourth option which, at least in principle, is available to us: co-evolution of the universe and observers. Although conceptual roots of this approach could be found already in ancient stoicism, it is still the least investigated explanatory option for resolving the problem of empirical fine tunings. We offer two preliminary models along which the co-evolution hypothesis could be developed further. They are still on the level of speculative metaphysics, but there are opportunities along the way to generate predictions which are in principle testable, especially in the domain of large-scale numerical simulations. 相似文献
147.
Nikola Vesović Ljubodrag Vujisić Vesna Perić-Mataruga Gordana Krstić Marija Nenadić Mirjana Cvetković 《Journal of Natural History》2017,51(9-10):545-560
Although all ground beetles have pygidial glands homologous in structure and function, there are many differences among species, often significant, in terms of chemical composition of the secretion and morphology of the gland components. In this paper, two predatory ground beetle species of the genus Carabus, namely C. (Tomocarabus) convexus and C. (Procrustes) coriaceus, were subjected to chemical, morphological and histological study of their pygidial glands and the glands’ secretions. Altogether, three carboxylic acids were isolated, and the pygidial gland reservoir and other glandular parts are morphologically described in the study. We also tested whether there exist differences in chemical content of the secretion obtained by upsetting the beetles in a traditional way and that obtained directly from intact reservoirs. Detailed data on morphology of the pygidial glands of both species are presented, as well as updated information about the chemical components of the glandular secretions. Apart from tiglic and methacrylic acids, which are typical for Carabus pygidial secretions, we also found benzoic acid as a minor component of the secretion in both species. In addition, a chemotaxonomic overview of Carabus taxa is given in the paper. 相似文献
148.
Wortmann SB Vaz FM Gardeitchik T Vissers LE Renkema GH Schuurs-Hoeijmakers JH Kulik W Lammens M Christin C Kluijtmans LA Rodenburg RJ Nijtmans LG Grünewald A Klein C Gerhold JM Kozicz T van Hasselt PM Harakalova M Kloosterman W Barić I Pronicka E Ucar SK Naess K Singhal KK Krumina Z Gilissen C van Bokhoven H Veltman JA Smeitink JA Lefeber DJ Spelbrink JN Wevers RA Morava E de Brouwer AP 《Nature genetics》2012,44(7):797-802
Using exome sequencing, we identify SERAC1 mutations as the cause of MEGDEL syndrome, a recessive disorder of dystonia and deafness with Leigh-like syndrome, impaired oxidative phosphorylation and 3-methylglutaconic aciduria. We localized SERAC1 at the interface between the mitochondria and the endoplasmic reticulum in the mitochondria-associated membrane fraction that is essential for phospholipid exchange. A phospholipid analysis in patient fibroblasts showed elevated concentrations of phosphatidylglycerol-34:1 (where the species nomenclature denotes the number of carbon atoms in the two acyl chains:number of double bonds in the two acyl groups) and decreased concentrations of phosphatidylglycerol-36:1 species, resulting in an altered cardiolipin subspecies composition. We also detected low concentrations of bis(monoacyl-glycerol)-phosphate, leading to the accumulation of free cholesterol, as shown by abnormal filipin staining. Complementation of patient fibroblasts with wild-type human SERAC1 by lentiviral infection led to a decrease and partial normalization of the mean ratio of phosphatidylglycerol-34:1 to phosphatidylglycerol-36:1. Our data identify SERAC1 as a key player in the phosphatidylglycerol remodeling that is essential for both mitochondrial function and intracellular cholesterol trafficking. 相似文献
149.
Polyembryonic development, where multiple embryos are formed from a single zygote, evolved at least 15 times in six different
phyla in animals. The mechanisms leading to polyembryony and the forces that shaped the evolution of the polyembryonic developmental
program have remained poorly understood. Recent studies of the polyembryonic development in the endoparasitic wasp Copidosoma floridanum have revealed that the evolution of polyembryony is associated with the evolution of developmental novelties such as total
cleavage, early specification of embryonic and extra-embryonic fates, and a specific cell proliferation phase. These changes
cumulatively result in the formation of thousands of embryos from a single egg. Laser ablation studies and analysis of early
cell fate specification have revealed that a single blastomere representing the progenitor of the primordial germ cell regulates
the proliferation of the embryos. We propose that evolutionary changes in cell cleavage, cell interactions, and the cell-differentiation
program, reminiscent of interactions between the germinal stem cell and stem cell niche in fly ovaries, underlies the evolution
of polyembryony.
Received 30 January 2007; received after revision 21 June 2007; accepted 11 July 2007 相似文献
150.
Wu T Mayaffre H Krämer S Horvatić M Berthier C Hardy WN Liang R Bonn DA Julien MH 《Nature》2011,477(7363):191-194
Electronic charges introduced in copper-oxide (CuO(2)) planes generate high-transition-temperature (T(c)) superconductivity but, under special circumstances, they can also order into filaments called stripes. Whether an underlying tendency towards charge order is present in all copper oxides and whether this has any relationship with superconductivity are, however, two highly controversial issues. To uncover underlying electronic order, magnetic fields strong enough to destabilize superconductivity can be used. Such experiments, including quantum oscillations in YBa(2)Cu(3)O(y) (an extremely clean copper oxide in which charge order has not until now been observed) have suggested that superconductivity competes with spin, rather than charge, order. Here we report nuclear magnetic resonance measurements showing that high magnetic fields actually induce charge order, without spin order, in the CuO(2) planes of YBa(2)Cu(3)O(y). The observed static, unidirectional, modulation of the charge density breaks translational symmetry, thus explaining quantum oscillation results, and we argue that it is most probably the same 4a-periodic modulation as in stripe-ordered copper oxides. That it develops only when superconductivity fades away and near the same 1/8 hole doping as in La(2-x)Ba(x)CuO(4) (ref.?1) suggests that charge order, although visibly pinned by CuO chains in YBa(2)Cu(3)O(y), is an intrinsic propensity of the superconducting planes of high-T(c) copper oxides. 相似文献