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81.
Muschner VC Lorenz AP Cervi AC Bonatto SL Souza-Chies TT Salzano FM Freitas LB 《American journal of botany》2003,90(8):1229-1238
Passiflora, a genus with more than 400 species, exhibits a high diversity of floral and vegetative structures and a complex taxonomy, which includes 23 subgenera and many sections and series. To better understand Passiflora's variability and interspecific relationships, the phylogeny of 61 species, classified in 11 of 23 suggested subgenera, was investigated. Three molecular markers were used, the nuclear ribosomal internal transcribed spacers (nrITS), the plastid trnL-trnF spacer regions (~1000 bp), and the rps4 plastid gene (~570 bp). Three major clades were highly supported, independent of the marker and phylogenetic method used; one included the subgenera Distephana, Dysosmia, Dysosmioides, Passiflora, and Tacsonioides, a second, the subgenera Adopogyne, Decaloba, Murucuja, and Pseudomurucuja, and a third, the subgenus Astrophea. We call these the Passiflora, Decaloba, and Astrophea clades, respectively. The position of subgenus Deidamioides is undefined. The monophyly of Passiflora could not be statistically corroborated, and the relationships among the major clades and of these clades with the related genera remain unresolved. Our results indicate that a reevaluation of the monophyly of Passiflora and its infrageneric classification is necessary. 相似文献
82.
Pereira T Zheng X Ruas JL Tanimoto K Poellinger L 《The Journal of biological chemistry》2003,278(9):6816-6823
83.
Middelboe M Hagström A Blackburn N Sinn B Fischer U Borch NH Pinhassi J Simu K Lorenz MG 《Microbial ecology》2001,42(3):395-406
Viral lysis of specific bacterial populations has been suggested to be an important factor for structuring marine bacterioplankton
communities. In the present study, the influence of bacteriophages on the diversity and population dynamics of four marine
bacterial phage-host systems was studied experimentally in continuous cultures and theoretically by a mathematical model.
By use of whole genome DNA hybridization toward community DNA, we analyzed the dynamics of individual bacterial host populations
in response to the addition of their specific phage in continuous cultures of mixed bacterial assemblages. In these experiments,
viral lysis had only temporary effects on the dynamics and diversity of the individual bacterial host species. Following the
initial lysis of sensitive host cells, growth of phage-resistant clones of the added bacteria resulted in a distribution of
bacterial strains in the phage-enriched culture that was similar to that in the control culture without phages after about
50-60 h incubation. Consequently, after a time frame of 5-10 generations after lysis, it was the interspecies competition
rather than viral lysis of specific bacterial strains that was the driving force in the regulation of bacterial species composition
in these experiments. The clonal diversity, on the other hand, was strongly influenced by viral activity, since the clonal
composition of the four species in the phage-enriched culture changed completely from phage-sensitive to phage-resistant clones.
The model simulation predicted that viral lysis had a strong impact on the population dynamics, the species composition, and
the clonal composition of the bacterial community over longer time scales (weeks). However, according to the model, the overall
density of bacteria in the system was not affected by phages, since resistant clones complemented the fluctuations caused
by viral lysis. Based on the model analysis, we therefore suggest that viral lysis can have a strong influence on the dynamics
of bacterial populations in planktonic marine systems. 相似文献
84.
Lorenz JN 《American journal of physiology. Regulatory, integrative and comparative physiology》2002,282(6):R1565-R1582
The development and widespread use of genetically altered mice to study the role of various proteins in biological control systems have led to a renewed interest in methodologies and approaches for evaluating physiological phenotypes. As a result, cross-disciplinary approaches have become essential for fully realizing the potential of these new and powerful animal models. The combination of classical physiological approaches and modern innovative technology has given rise to an impressive arsenal for evaluating the functional results of genetic manipulation in the mouse. This review attempts to summarize some of the techniques currently being used for measuring cardiovascular, renal, and pulmonary variables in the intact mouse, with specific attention to practical considerations useful for their successful implementation. 相似文献
85.
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87.
Beta(1)/beta(2)/beta(3)-adrenoceptor knockout mice are obese and cold-sensitive but have normal lipolytic responses to fasting 总被引:1,自引:0,他引:1
Jimenez M Léger B Canola K Lehr L Arboit P Seydoux J Russell AP Giacobino JP Muzzin P Preitner F 《FEBS letters》2002,530(1-3):37-40
Catecholamines are viewed as major stimulants of diet- and cold-induced thermogenesis and of fasting-induced lipolysis, through the β-adrenoceptors (β1/β2/β3). To test this hypothesis, we generated β1/β2/β3-adrenoceptor triple knockout (TKO) mice and compared them to wild type animals. TKO mice exhibited normophagic obesity and cold-intolerance. Their brown fat had impaired morphology and lacked responses to cold of uncoupling protein-1 expression. In contrast, TKO mice had higher circulating levels of free fatty acids and glycerol at basal and fasted states, suggesting enhanced lipolysis. Hence, β-adrenergic signalling is essential for the resistance to obesity and cold, but not for the lipolytic response to fasting. 相似文献
88.
Roggo L Bernard V Kovacs AL Rose AM Savoy F Zetka M Wymann MP Müller F 《The EMBO journal》2002,21(7):1673-1683
Here we present a detailed genetic analysis of let-512/vps34 that encodes the Caenorhabditis elegans homologue of the yeast phosphatidylinositol 3-kinase Vps34p. LET-512/VPS34 has essential functions and is ubiquitously expressed in all tissues and developmental stages. It accumulates at a perinuclear region, and mutations in let-512/vps34 result in an expansion of the outer nuclear membrane as well as in a mislocalization and subsequent complete lack of expression of LRP-1, a C.elegans LDL receptor normally associated with the apical surface of hypodermal cells. Using a GFP::2xFYVE fusion protein we found that the phosphatidylinositol 3-phosphate (PtdIns 3-P) product of LET-512/VPS34 is associated with a multitude of intracellular membranes and vesicles located at the periphery, including endocytic vesicles. We propose that LET-512/VPS34 is required for membrane transport from the outer nuclear membrane towards the cell periphery. Thus, LET-512/VPS34 may regulate the secretory pathway in a much broader range of compartments than was previously suggested for the yeast orthologue. 相似文献
89.
Folding and dimerization of tick-borne encephalitis virus envelope proteins prM and E in the endoplasmic reticulum 总被引:4,自引:0,他引:4 下载免费PDF全文
Flavivirus envelope proteins are synthesized as part of large polyproteins that are co- and posttranslationally cleaved into their individual chains. To investigate whether the interaction of neighboring proteins within the precursor protein is required to ensure proper maturation of the individual components, we have analyzed the folding of the flavivirus tick-borne encephalitis (TBE) virus envelope glycoproteins prM and E by using a recombinant plasmid expression system and virus-infected cells. When expressed in their polyprotein context, prM and E achieved their native folded structures with half-times of approximately 4 min for prM and about 15 min for E. They formed heterodimeric complexes within a few minutes after synthesis that were required for the final folding of E but not for that of prM. Heterodimers could also be formed in trans when these proteins were coexpressed from separate constructs. When expressed without prM, E could form disulfide bonds but did not express a specific conformational epitope and remained sensitive to reduction by dithiothreitol. This is consistent with a chaperone-like role for prM in the folding of E. PrM was able to achieve its native folded structure without coexpression of E, but signal sequence cleavage at the N terminus was delayed. Our results show that prM is an especially rapidly folding viral glycoprotein, that polyprotein cleavage and folding of the TBE virus envelope proteins occurs in a coordinated sequence of processing steps, and that proper and efficient maturation of prM and E can only be achieved by cosynthesis of these two proteins. 相似文献
90.
Mitochondrial death protein Nix is induced in cardiac hypertrophy and triggers apoptotic cardiomyopathy 总被引:14,自引:0,他引:14
Yussman MG Toyokawa T Odley A Lynch RA Wu G Colbert MC Aronow BJ Lorenz JN Dorn GW 《Nature medicine》2002,8(7):725-730
Loss of cardiomyocytes through programmed cell death is a key event in the development of heart failure, but the inciting molecular mechanisms are largely unknown. We used microarray analysis to identify a genetic program for myocardial apoptosis in Gq-mediated and pressure-overload cardiac hypertrophy. A critical component of this apoptotic program was Nix/Bnip3L. Nix localized to mitochondria and caused release of cytochrome c, activation of caspase-3 and apoptotic cell death, when expressed in HEK293 fibroblasts. A previously undescribed truncated Nix isoform, termed sNix, was not targeted to mitochondria but heterodimerized with Nix and protected against Nix-mediated apoptosis. Forced in vivo myocardial expression of Nix resulted in apoptotic cardiomyopathy and rapid death. Conversely, sNix protected against apoptotic peripartum cardiomyopathy in G(alpha)q-overexpressors. Thus, Nix/Bnip3L is upregulated in myocardial hypertrophy, and is both necessary and sufficient for Gq-mediated apoptosis of cardiomyocytes and resulting hypertrophy decompensation. 相似文献