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111.
Reproduction is a critical event in the life cycle of animals, and a high amount of energy is allocated to it. The aim of this study was to characterize the reproductive biology of two recently described species of Hyalella from the north-east region of state of Rio Grande do Sul in southern Brazil. The specimens were collected during 12 months from a stream source (Hyalella georginae) and from a water reservoir (H. gauchensis), in Palmeira das Missões municipality, state of Rio Grande do Sul. Upon sampling, ovigerous females and pairs in precopulatory behaviour were separated into microtubes. In the laboratory, the cephalothorax length (CL in mm) of all specimens was measured. Male size at onset of sexual maturity was larger than that of the females, in both species. There was a correlation between the size of paired males and females: larger males carried larger females, in both Hyalella species. Precopulatory pairs were found throughout the year; however, H. georginae had a higher frequency in spring, and H. gauchensis in autumn. There was a positive correlation between the CL of ovigerous females and the number of eggs/juveniles. A reduction in the number of eggs throughout the embryonic development was observed in H. georginae. The average fecundity of H. georginae was significantly higher than H. gauchensis. The differences between the reproductive biology of these species may be related to the physical and environmental conditions at which they are exposed in their habitats. 相似文献
112.
Francesca Cherubino Andreea Miszner Maria Daniela Renna Rachele Sangaletti Stefano Giovannardi Elena Bossi 《Cellular and molecular life sciences : CMLS》2009,66(23):3797-3808
The effects of three tricyclic antidepressants (TCAs) and two serotonin selective reuptake inhibitors (SSRIs) have been studied
with an electrophysiological approach on Xenopus laevis oocytes expressing the rat GABA (γ-Aminobutyric-acid) transporter rGAT1. All tested TCAs and SSRIs inhibit the GABA-associated
current in a dose-dependent way with low but comparable efficacy. The pre-steady-state and uncoupled currents appear substantially
unaffected. The efficacy of desipramine, but not of the other drugs, is strongly increased in the lysine-glutamate or -aspartate
mutants K448E and K448D. Comparison of I
max and K
0.5GABA in the absence and presence of desipramine showed that both parameters are reduced by the drug in the wild-type and in the
K448E mutant. This suggests an uncompetitive inhibition, in which the drug can bind only after the substrate, an explanation
in agreement with the lack of effects on the pre-steady-state and leak currents, and with the known structural data. 相似文献
113.
Maria Theodosiou Vincent Laudet Michael Schubert 《Cellular and molecular life sciences : CMLS》2010,67(9):1423-1445
Vitamin A is essential for the formation and maintenance of many body tissues. It is also important for embryonic growth and
development and can act as a teratogen at critical periods of development. Retinoic acid (RA) is the biologically active form
of vitamin A and its signaling is mediated by the RA and retinoid X receptors. In addition to its role as an important molecule
during development, RA has also been implicated in clinical applications, both as a potential anti-tumor agent as well as
for the treatment of skin diseases. This review presents an overview of how dietary retinoids are converted to RA, hence presenting
the major players in RA metabolism and signaling, and highlights examples of treatment applications of retinoids. Moreover,
we discuss the origin and diversification of the retinoid pathway, which are important factors for understanding the evolution
of ligand-specificity among retinoid receptors. 相似文献
114.
Maria Valeria Catani Valeria Gasperi Daniela Evangelista Alessandro Finazzi Agrò Luciana Avigliano Mauro Maccarrone 《Cellular and molecular life sciences : CMLS》2010,67(4):601-610
Platelets are stored at 22°C, since incubation at 37°C results in loss of viability. Nonetheless, in our body (37°C), platelets
survive for 8–10 days. This discrepancy has been explained in terms of deprivation of viability factors or accumulation of
apoptotic factors during storage. We report that the endocannabinoid anandamide (AEA) may be one of the agents allowing platelet
survival. In fact, at 37°C, human platelets enhance the expression of pro-apoptotic proteins (caspases, Bax, Bak) and decrease
the expression of Bcl-xL, thus changing the Bcl-xL/Bak ratio, a key platelet biological clock. AEA or its non-hydrolyzable
analogue, methanandamide, extend platelet life span, without reversing the changes in Bcl-xL/Bak ratio induced by heat stress.
Instead, AEA binding to type-1 cannabinoid receptor activates Akt, which regulates, through phosphorylation of Bad, the interactions
among different Bcl-2 family members. These findings could have implications for platelet collection and, potentially, for
their clinical use. 相似文献
115.
Vincenzo Luca Annarita Stringaro Marisa Colone Alessandro Pini Maria Luisa Mangoni 《Cellular and molecular life sciences : CMLS》2013,70(15):2773-2786
Pseudomonas aeruginosa is an opportunistic bacterial pathogen that forms sessile communities, named biofilms. The non-motile forms are very difficult to eradicate and are often associated with the establishment of persistent infections, especially in patients with cystic fibrosis. The resistance of P. aeruginosa to conventional antibiotics has become a growing health concern worldwide and has prompted the search for new anti-infective agents with new modes of action. Naturally occurring antimicrobial peptides (AMPs) represent promising future template candidates. Here we report on the potent activity and membrane-perturbing effects of the amphibian AMP esculentin(1-21), on both the free-living and sessile forms of P. aeruginosa, as a possible mechanism for biofilm disruption. Furthermore, the findings that esculentin(1-21) is able to prolong survival of animals in models of sepsis and pulmonary infection indicate that this peptide can be a promising template for the generation of new antibiotic formulations to advance care of infections caused by P. aeruginosa. 相似文献
116.
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119.
Frazão C McVey CE Amblar M Barbas A Vonrhein C Arraiano CM Carrondo MA 《Nature》2006,443(7107):110-114
RNA degradation is a determining factor in the control of gene expression. The maturation, turnover and quality control of RNA is performed by many different classes of ribonucleases. Ribonuclease II (RNase II) is a major exoribonuclease that intervenes in all of these fundamental processes; it can act independently or as a component of the exosome, an essential RNA-degrading multiprotein complex. RNase II-like enzymes are found in all three kingdoms of life, but there are no structural data for any of the proteins of this family. Here we report the X-ray crystallographic structures of both the ligand-free (at 2.44 A resolution) and RNA-bound (at 2.74 A resolution) forms of Escherichia coli RNase II. In contrast to sequence predictions, the structures show that RNase II is organized into four domains: two cold-shock domains, one RNB catalytic domain, which has an unprecedented alphabeta-fold, and one S1 domain. The enzyme establishes contacts with RNA in two distinct regions, the 'anchor' and the 'catalytic' regions, which act synergistically to provide catalysis. The active site is buried within the RNB catalytic domain, in a pocket formed by four conserved sequence motifs. The structure shows that the catalytic pocket is only accessible to single-stranded RNA, and explains the specificity for RNA versus DNA cleavage. It also explains the dynamic mechanism of RNA degradation by providing the structural basis for RNA translocation and enzyme processivity. We propose a reaction mechanism for exonucleolytic RNA degradation involving key conserved residues. Our three-dimensional model corroborates all existing biochemical data for RNase II, and elucidates the general basis for RNA degradation. Moreover, it reveals important structural features that can be extrapolated to other members of this family. 相似文献
120.