Land use and biodiversity congruences at local scale: applications to conservation strategies

The establishment of protected areas is traditionally considered indispensable to preserve biodiversity hotspots or areas inhabited by threatened species. The analysis of correlations between composition or richness of several taxonomic groups in a specific area has emerged as a useful mechanism to quickly identify areas of biological and conservation interest, and is currently used to select and design protected areas. The effect of habitat fragmentation on these correlations at a regional scale has been studied, but the effect of land use on the correlations obtained at local scale is poorly understood. We evaluated the relationships among different taxonomic groups frequently used in biological assessments for reserve design (vascular flora, amphibians, reptiles, birds and mammals), taking into account the effects of land use on these correlations. We compared richness and species composition of these groups in 1 km² quadrants within a total area of 75 km² in a low mountain Mediterranean area. Richness and composition were significantly correlated between several groups, both using the complete data set and also analyzing natural and disturbed areas separately. Species composition and species richness correlations were not congruent at the full landscape approach, nor natural and disturbed quadrants. Factors extrinsic to the communities also varied their influence in the assemblage of the community and species richness or not land uses were taken into account. According to our results, natural and human-disturbed areas should not be combined in cross-taxon congruences analysis at local scale.     

Release rate for a pre-plant application of Nesidiocoris tenuis for Bemisia tabaci control in tomato

Nesidiocoris tenuis Reuter (Het.: Miridae) is widely used as a biological control agent of whiteflies and other pests in greenhouse-grown tomatoes. It is typically released augmentatively some weeks after transplanting and needs several weeks to establish. Releasing N. tenuis prior to transplanting could accelerate its establishment. However, timing for releases could affect biological control and require changes in release rates of the predator. Because N. tenuis is also phytophagous it must be released at a rate which provides the best equilibrium between adequate biological control of Bemisia tabaci Genn. and acceptable injury to the crop. The objective of this study was therefore to evaluate different release rates for releasing N. tenuis prior to transplanting for maximizing control capacity and minimizing injury to crop. The study was carried out in two subsequent trials in which different release rates were evaluated under a worst case scenario of rapid immigration of the pest into a tomato greenhouse. In the first experiment (winter experiment), four treatments were compared: (1) B. tabaci (0 N. tenuis/plant), (2) B. tabaci?+?0.5?N. tenuis/plant, (3) B. tabaci?+?1?N. tenuis/plant and (4) B. tabaci?+?2?N. tenuis/plant. In the second experiment (summer experiment), the treatments were: (1) B. tabaci (0 N. tenuis/plant), (2) B. tabaci?+?0.5?N. tenuis/plant and (3) B. tabaci?+?1?N. tenuis/plant. All the evaluated rates significantly reduced the population of whitefly and gave adequate control of the pest. However, only 0.5?N. tenuis/plant did not increase crop damage compared to the treatment with no N. tenuis.     

Metabolic stasis in an ancient symbiosis: genome-scale metabolic networks from two Blattabacterium cuenoti strains,primary endosymbionts of cockroaches

Background

Cockroaches are terrestrial insects that strikingly eliminate waste nitrogen as ammonia instead of uric acid. Blattabacterium cuenoti (Mercier 1906) strains Bge and Pam are the obligate primary endosymbionts of the cockroaches Blattella germanica and Periplaneta americana, respectively. The genomes of both bacterial endosymbionts have recently been sequenced, making possible a genome-scale constraint-based reconstruction of their metabolic networks. The mathematical expression of a metabolic network and the subsequent quantitative studies of phenotypic features by Flux Balance Analysis (FBA) represent an efficient functional approach to these uncultivable bacteria.

Results

We report the metabolic models of Blattabacterium strains Bge (iCG238) and Pam (iCG230), comprising 296 and 289 biochemical reactions, associated with 238 and 230 genes, and 364 and 358 metabolites, respectively. Both models reflect both the striking similarities and the singularities of these microorganisms. FBA was used to analyze the properties, potential and limits of the models, assuming some environmental constraints such as aerobic conditions and the net production of ammonia from these bacterial systems, as has been experimentally observed. In addition, in silico simulations with the iCG238 model have enabled a set of carbon and nitrogen sources to be defined, which would also support a viable phenotype in terms of biomass production in the strain Pam, which lacks the first three steps of the tricarboxylic acid cycle. FBA reveals a metabolic condition that renders these enzymatic steps dispensable, thus offering a possible evolutionary explanation for their elimination. We also confirm, by computational simulations, the fragility of the metabolic networks and their host dependence.

Conclusions

The minimized Blattabacterium metabolic networks are surprisingly similar in strains Bge and Pam, after 140 million years of evolution of these endosymbionts in separate cockroach lineages. FBA performed on the reconstructed networks from the two bacteria helps to refine the functional analysis of the genomes enabling us to postulate how slightly different host metabolic contexts drove their parallel evolution.

     

The influence of the rearing host on the response of the parasitoid Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae) to odours from Ephestia kuehniella and Plodia interpunctella in a Y-tube olfactometer

Venturia canescens (Gravenhorst) is an ichneumonid generalist parasitoid that successfully attacks the larvae of different lepidopteran pests that infest stored products. These pest species include Plodia interpunctella and Ephestia kuehniella. In this study, we aimed to evaluate the influence of the rearing host on the parasitoid’s ability to detect and respond to a new host different from the rearing species. For this reason, the trials tested the preference of parasitoids reared on P. interpunctella or E. kuehniella for products that were or were not infested with larvae of these hosts. The trials were conducted in a Y-tube olfactometer. Regardless of the rearing host species, the parasitoids showed no preference for uninfested products. The parasitoids were attracted to products infested with larvae of their rearing host in preference to uninfested products. They also showed preferential attraction to products infested with the new host over uninfested products. E. kuehniella was the preferred host, irrespectively of the parasitoid host rearing species. The results are discussed to develop a better understanding of the ecology of V. canescens for its application in biological control.     

Evolutionary combinatorial chemistry, a novel tool for SAR studies on peptide transport across the blood-brain barrier. Part 2. Design, synthesis and evaluation of a first generation of peptides.

The use of high-throughput methods in drug discovery allows the generation and testing of a large number of compounds, but at the price of providing redundant information. Evolutionary combinatorial chemistry combines the selection and synthesis of biologically active compounds with artificial intelligence optimization methods, such as genetic algorithms (GA). Drug candidates for the treatment of central nervous system (CNS) disorders must overcome the blood-brain barrier (BBB). This paper reports a new genetic algorithm that searches for the optimal physicochemical properties for peptide transport across the blood-brain barrier. A first generation of peptides has been generated and synthesized. Due to the high content of N-methyl amino acids present in most of these peptides, their syntheses were especially challenging due to over-incorporations, deletions and DKP formations. Distinct fragmentation patterns during peptide cleavage have been identified. The first generation of peptides has been studied by evaluation techniques such as immobilized artificial membrane chromatography (IAMC), a cell-based assay, log Poctanol/water calculations, etc. Finally, a second generation has been proposed.     

Chemically synthesized peptide libraries as a new source of BBB shuttles. Use of mass spectrometry for peptide identification

The blood–brain barrier (BBB) is a biological barrier that protects the brain from neurotoxic agents and regulates the influx and efflux of molecules required for its correct function. This stringent regulation hampers the passage of brain parenchyma‐targeting drugs across the BBB. BBB shuttles have been proposed as a way to overcome this hurdle because these peptides can not only cross the BBB but also carry molecules which would otherwise be unable to cross the barrier unaided. Here we developed a new high‐throughput screening methodology to identify new peptide BBB shuttles in a broadly unexplored chemical space. By introducing d‐ amino acids, this approach screens only protease‐resistant peptides. This methodology combines combinatorial chemistry for peptide library synthesis, in vitro models mimicking the BBB for library evaluation and state‐of‐the‐art mass spectrometry techniques to identify those peptides able to cross the in vitro assays. BBB shuttle synthesis was performed by the mix‐and‐split technique to generate a library based on the following: Ac‐d‐ Arg‐XXXXX‐NH₂, where X were: d‐ Ala (a), d‐ Arg (r), d‐ Ile (i), d‐ Glu (e), d‐ Ser (s), d‐ Trp (w) or d‐ Pro (p). The assays used comprised the in vitro cell‐based BBB assay (mimicking both active and passive transport) and the PAMPA (mimicking only passive diffusion). The identification of candidates was determined using a two‐step mass spectrometry approach combining LTQ‐Orbitrap and Q‐trap mass spectrometers. Identified sequences were postulated to cross the BBB models. We hypothesized that some sequences cross the BBB through passive diffusion mechanisms and others through other mechanisms, including paracellular flux and active transport. These results provide a new set of BBB shuttle peptide families. Furthermore, the methodology described is proposed as a consistent approach to search for protease‐resistant therapeutic peptides. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.     

Massive presence of insertion sequences in the genome of SOPE, the primary endosymbiont of the rice weevil Sitophilus oryzae

Bacteria that establish an obligate intracellular relationship with eukaryotic hosts undergo an evolutionary genomic reductive process. Recent studies have shown an increase in the number of mobile elements in the first stage of the adaptive process towards intracellular life, although these elements are absent in ancient endosymbionts. Here, the genome of SOPE, the obligate mutualistic endosymbiont of rice weevils, was used as a model to analyze the initial events that occur after symbiotic integration. During the first phases of the SOPE genome project, four different types of insertion sequence (IS) elements, belonging to well-characterized IS families from gamma-proteobacteria, were identified. In the present study, these elements, which may represent more than 20% of the complete genome, were completely characterized; their relevance as a source of gene inactivation, chromosomal rearrangements, and as participants in the genome reductive process are discussed herein.