Structural Basis of Rap Phosphatase Inhibition by Phr Peptides

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.     

Raid process, activity pattern and influence of abiotic conditions in the slave-making ant Rossomyrmex minuchae (Hymenoptera, Formicidae)

Summary: In the present work, we present the results of a study on the seasonal and daily activity, as well as on the raid process in Rossomyrmex minuchae. A comparative study of the annual and daily activity of the host species, Proformica longiseta, has also been made in parasitized and non-parasitized colonies. R. minuchae is an obligate slave-maker, in which the annual activity is strongly related to abiotic conditions, especially temperature and moisture of the soil. The raid process is comprised of three phases: scouting, assault of the host nest and robbing of the host brood. Recruitment of nestmates by mean of adult transport, concentration close to and invasion of the host nest, are the three tasks carried out by R. minuchae workers during the assault phase. Major differences between Rossomyrmex and Polyergus (the other obligate dulotic genus of the tribe Formicini) in terms of behaviour, both in nestmate recruitment and in the host-nest invasion, reflect different parasitic strategies in the two genera, supporting the assignment of these two genera to different phylogenetic groups.     

A putative antimicrobial peptide from Hymenoptera in the megaplasmid pSCL4 of Streptomyces clavuligerus ATCC 27064 reveals a singular case of horizontal gene transfer with potential applications

Streptomyces clavuligerus is a Gram‐positive bacterium that is a high producer of secondary metabolites with industrial applications. The production of antibiotics such as clavulanic acid or cephamycin has been extensively studied in this species; nevertheless, other aspects, such as evolution or ecology, have received less attention. Furthermore, genes that arise from ancient events of lateral transfer have been demonstrated to be implicated in important functions of host species. This approximation discovered relevant genes that genomic analyses overlooked. Thus, we studied the impact of horizontal gene transfer in the S. clavuligerus genome. To perform this task, we applied whole‐genome analysis to identify a laterally transferred sequence from different domains. The most relevant result was a putative antimicrobial peptide (AMP) with a clear origin in the Hymenoptera order of insects. Next, we determined that two copies of these genes were present in the megaplasmid pSCL4 but absent in the S. clavuligerus ATCC 27064 chromosome. Additionally, we found that these sequences were exclusive to the ATCC 27064 strain (and so were not present in any other bacteria) and we also verified the expression of the genes using RNAseq data. Next, we used several AMP predictors to validate the original annotation extracted from Hymenoptera sequences and explored the possibility that these proteins had post‐translational modifications using peptidase cleavage prediction. We suggest that Hymenoptera AMP‐like proteins of S. clavuligerus ATCC 27064 may be useful for both species adaptation and as an antimicrobial molecule with industrial applications.     

Bobcat (Lynx rufus) Breeding in Captivity: The Importance of Environmental Enrichment

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.     

Variability in nuclear DNA among nonhuman primates: Application of molecular genetic techniques to intra- and inter-species genetic analyses

Nuclear DNA clones and sequence information derived from human genetic analyses were used to detect and characterize intra- and inter-species DNA variation at several nuclear loci in hominoids and cercopithecoids. Restriction fragment length polymorphisms were found at five loci among captive rhesus monkeys. Cross-species polymerase chain reaction (PCR) amplification detected an insertion within the beta-globin gene cluster in hylobatids. The combined use of cross-species PCR and denaturing gradient gel electrophoresis detected both species differences and intra-species polymorphism in the homeobox cluster 2 of hominoids. These results a) demonstrate that DNA clones and nucleotide sequence information from human molecular genetics can be used to facilitate studies of the molecular genetics of nonhuman primates, and b) document specific examples of intra- and inter-species molecular variability at several loci. © 1992 Wiley-Liss, Inc.     

High endemism of cacti remains unprotected in the Caatinga

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,...     

Extracellular DNase activity of Cryptococcus neoformans and Cryptococcus gattii

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.     

What is known on angiogenesis-related rare diseases? A systematic review of literature

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.