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Enrico Sanna Costantino Motzo Marcello Usala Davide Pau Elisabetta Cagetti Giovanni Biggio 《Journal of neurochemistry》1998,70(6):2539-2544
Abstract: Expression of rat brain γ-aminobutyric acid type A (GABAA) receptors in Xenopus laevis oocytes can be achieved by injection of the oocytes with synaptosomes. This approach has now been applied to evaluate changes in the function of nigral GABAA receptors after degeneration of the striatonigral GABAergic pathway induced by the unilateral infusion of kainic acid into the rat striatum. Ten days after striatal injection, synaptosomal membranes were prepared from the substantia nigra and introduced into oocytes. Nigral GABAA receptors incorporated into the oocyte cell membrane were then characterized electrophysiologically under voltage-clamp conditions. The maximal amplitude of GABA-induced Cl? currents in oocytes injected with synaptosomes from denervated substantia nigra was twice that observed in oocytes injected with synaptosomes from control substantia nigra. The concentration of GABA required for the half-maximal response did not differ between the two groups of oocytes. In addition, the potentiation of GABA-induced currents by the benzodiazepine diazepam (1 µM) and the steroid derivative allopregnanolone (3 µM) was increased by ~65 and 60%, respectively, in oocytes injected with synaptosomes from denervated substantia nigra compared with those injected with control synaptosomes. The concentrations of diazepam and allopregnanolone giving half-maximal responses were not affected by denervation. In contrast, the inhibitory effects of the benzodiazepine receptor inverse agonists FG 7142 (10 µM) and 6,7-dimethoxy-4-ethyl-β-carboline-3-carboxylic acid ethyl ester (1 µM) were reduced by 48 and 38%, respectively, after denervation. These results indicate that the up-regulation of nigral GABAA receptors induced by degeneration of the striatonigral GABAergic pathway is associated with an increased efficacy of positive allosteric modulators, such as benzodiazepines and steroids, and with a reduced efficacy of negative allosteric modulators such as β-carbolines. 相似文献
253.
The role of alien fish (the centrarchid Micropterus salmoides) in lake food webs highlighted by stable isotope analysis
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Maria Letizia Costantini Pasquale Carlino Edoardo Calizza Giulio Careddu Davide Cicala Simona Sporta Caputi Federico Fiorentino Loreto Rossi 《Freshwater Biology》2018,63(9):1130-1142
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Morphology of the terminalia of the stick insect Dajaca napolovi from Vietnam (Insecta: Phasmatodea)
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Davide Vallotto Joachim Bresseel Jérôme Constant Marco Gottardo 《Entomological Science》2016,19(4):376-382
Aschiphasmatinae is a small group of stick insects from the Oriental region whose genital morphology has been rarely described in detail. The subfamily is of particular interest, as phylogenetic studies have shown Aschiphasmatinae to be the sister group to the remaining Euphasmatodea. In this paper, the male and female terminalia are described for the first time in Dajaca napolovi Brock, a little known aschiphasmatine species from Vietnam. In the male, the transversally undivided abdominal sternum IX and gently incurved cerci with a conspicuous apical tooth represent apomorphies of Aschiphasmatinae. Thorn pads on the hind margin of abdominal tergum X consist of only a single row of 6–7 ventrally oriented teeth. The simple thorn pad structure of Aschiphasmatinae can represent an ancestral condition for Euphasmatodea. The vomer on venter X is well‐developed and features two unusually large basal apodemes and a strongly developed apical spine showing a specialized streaked surface micropattern. Female terminalia are characterized by an unkeeled abdominal sternum VIII covering the reduced primary ovipositor. Gonapophysis VIII does not extend beyond the tip of gonapophysis IX. An asymmetry concerning the size of the paired gonapophyses is reported for the first time in Phasmatodea. 相似文献
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When phylogenetic trees constructed from morphological and molecular evidence disagree (i.e. are incongruent) it has been
suggested that the differences are spurious or that the molecular results should be preferred a priori. Comparing trees can
increase confidence (congruence), or demonstrate that at least one tree is incorrect (incongruence). Statistical analyses
of 181 molecular and 49 morphological trees shows that incongruence is greater between than within the morphological and molecular
partitions, and this difference is significant for the molecular partition. Because the level of incongruence between a pair
of trees gives a minimum bound on how much error is present in the two trees, our results indicate that the level of error
may be underestimated by congruence within partitions. Thus comparisons between morphological and molecular trees are particularly
useful for detecting this incongruence (spurious or otherwise). Molecular trees have higher average congruence than morphological
trees, but the difference is not significant, and both within- and between-partition incongruence is much lower than expected
by chance alone. Our results suggest that both molecular and morphological trees are, in general, useful approximations of
a common underlying phylogeny and thus, when molecules and morphology clash, molecular phylogenies should not be considered
more reliable a priori. 相似文献
259.
Gabriella Mincione Alessandro Piccirelli Davide Lazzereschi David S. Salomon Giulia Colletta 《Journal of cellular physiology》1998,176(2):383-391
The EGF-like family of proteins, such as epidermal growth factor (EGF), transforming growth factor α (TGFα), amphiregulin (AR), betacellulin (BTC), cripto-1 (CR-1), and heregulin (HRG), plays an important role in the pathogenesis of several human carcinomas as autocrine growth factors. Differentiation and proliferation of rat thyroid cells in culture (FRTL-5 cells) are regulated by thyrotropin (TSH); withdrawal of TSH from culture medium produces growth arrest, whereas its addition to quiescent cells stimulates cell entry into S phase. Instead, transformed thyroid cell lines as FRTL-5H2 cell line, overexpressing erbB-2, Kimol cells, transformed by the wild-type K-ras and A6 clone, transformed by a temperature sensitive K-ras mutant, can grow without addition of TSH to the culture medium. In order to identify whether EGF-like growth factors and corresponding receptors (erbB-2, erbB-3, and erbB-4) could be involved in the autonomous growth of these transformed rat thyroid epithelial cells, Northern blot for mRNA analysis and Western blot for protein expression were performed. In contrast to normal control FRTL-5 cells, both K-ras and erbB-2-transformed cells expressed elevated levels of erbB-2 receptor. Moreover, both K-ras transformed cells, Kimol and A6 cells, but no FRTL-5H2 cells, were found able to express also high levels of erbB-4 receptor and HRG/NDF ligand. Treatment of K-ras transformed thyroid cells with neutralizing antibody against HRG/NDF reduced by 50% cell proliferation. These data indicate that unlike the erbB-2 overexpressing FRTL-5 cells, in K-ras rat thyroid epithelial cells, the growth factor heregulin signals through the heterodimer erbB-2/erbB-4 receptors in an autocrine fashion. J. Cell. Physiol. 176:383–391, 1998. © 1998 Wiley-Liss, Inc. 相似文献
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