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872.
Two-component systems, composed of a sensor histidine kinase and an effector response regulator (RR), are the main signal transduction devices in bacteria. In Bacillus, the Rap protein family modulates complex signaling processes mediated by two-component systems, such as competence, sporulation, or biofilm formation, by inhibiting the RR components involved in these pathways. Despite the high degree of sequence homology, Rap proteins exert their activity by two completely different mechanisms of action: inducing RR dephosphorylation or blocking RR binding to its target promoter. However the regulatory mechanism involving Rap proteins is even more complex since Rap activity is antagonized by specific signaling peptides (Phr) through a mechanism that remains unknown at the molecular level. Using X-ray analyses, we determined the structure of RapF, the anti-activator of competence RR ComA, alone and in complex with its regulatory peptide PhrF. The structural and functional data presented herein reveal that peptide PhrF blocks the RapF-ComA interaction through an allosteric mechanism. PhrF accommodates in the C-terminal tetratricopeptide repeat domain of RapF by inducing its constriction, a conformational change propagated by a pronounced rotation to the N-terminal ComA-binding domain. This movement partially disrupts the ComA binding site by triggering the ComA disassociation, whose interaction with RapF is also sterically impaired in the PhrF-induced conformation of RapF. Sequence analyses of the Rap proteins, guided by the RapF-PhrF structure, unveil the molecular basis of Phr recognition and discrimination, allowing us to relax the Phr specificity of RapF by a single residue change. 相似文献
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874.
Chronobiological aspects of blood glucose regulation: a new scope for the study of diabetes mellitus
The levels of blood glucose undergo circadian variations in every species studied. Such rhythm is the consequence of the oscillation in the rate of provision and consumption of glucose. The liver plays an important role in this rhythm, retaining or releasing glucose from or to the circulation. The driving forces for this glucose flow come from outside (food intake) and inside (neural and hormonal control) the body. This blood glucose control might be referred as homeorheusis rather than homeostasis. The final regulatory adjustment of this precise and delicate mechanism is probably located around the suprachiasmatic and other hypothalamic nuclei. In diseases such as diabetes mellitus, where there is an alteration in the circadian rhythm of blood glucose, one of the main goals of treatment must be its restoration to normal levels. 相似文献
875.
María I. Mollá Miguel A. Quevedo Francisca Castro 《Journal of applied animal welfare science : JAAWS》2013,16(2):85-95
Environmental enrichment is an improvement in the biological functioning of nonhuman animals in captivity resulting from modifications to their environment; however, specifying appropriate and practical measures of enrichment is problematic. This study analyzes the behavior of 4 bobcats (Lynx rufus) in the Jerez Zoo before and after the application of a global program of environmental enrichment that included (a) changes in the size and complexity of their installations, (b) the introduction of new objects into compounds, (c) changes in diet, and (d) modifications in the grouping of animals. A factorial correspondence analysis showed a highly significant relationship among individual animals, behavior, and experimental design. Behaviors such as locomotion, repeated pacing, vigilance, and grooming more often occurred before enrichment, whereas exploratory and food behaviors were more often associated with the enrichment phase. After the implementation of the enrichment program, the bobcats bred successfully for the first time since their arrival in the zoo. 相似文献
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878.
Carvalho¹ Carlos E. Menezes Marcelo O. T. Araújo Francisca S. Sfair Júlia C. 《Biodiversity and Conservation》2022,31(4):1217-1228
Biodiversity and Conservation - Protected areas are one of the main strategies of biodiversity conservation. However, if these areas do not coincide spatially with priority areas for conservation,... 相似文献
879.
Extracellular DNase activity was studied in 73 strains of Cryptococcus neoformans and 12 strains of Cryptococcus gattii. DNase activity was measured by DNase agar clearance with and without Methyl Green. All strains tested showed extracellular DNase activity and no significant difference was found betweenC. neoformans and C. gattii strains. DNase production was higher in strains from clinical origin (average radius of 6.2 mm) than among environmental strains (average radius of 2.9 mm). The extracellular enzyme may be detected by DNA substrate PAGE assays and its molecular weight was estimated at 31 kD. These results suggest that extracellular DNase could be considered as a virulence factor involved in C. neoformans–C. gattii species complex pathogenicity. 相似文献
880.
Luis Rodríguez‐Caso Armando Reyes‐Palomares Francisca Sánchez‐Jiménez Ana R. Quesada Miguel Ángel Medina 《Journal of cellular and molecular medicine》2012,16(12):2872-2893
Angiogenesis, the formation of new vessels from pre‐existing ones, is essential during ontogenetic development and is related to many important physio‐pathological processes in the adult. In fact, a persistent and deregulated angiogenesis is a required event for many diseases and pathological situations, including cancer progression and metastasis. Some rare diseases are also angiogenesis‐related pathologies. However, there is a lack of an exhaustive review on the topic. The main purpose of this work is to carry out a systematic review of literature to determine what (and how much) scientific information concerning angiogenesis‐related rare diseases can be extracted from available sources. After exhaustive searches in bibliographic databases, preselected data were filtered by selecting only those articles on rare diseases with an Orpha number hosted in the Orphanet web. The selected bibliographic references were further curated manually. With the 187 selected references, a critical reading and analysis was carried out allowing for an identification and classification of angiogenesis‐related rare diseases, the involved genes and the drugs available for their treatment, all on the basis of the information available in Orphanet database. 相似文献