Widespread parallel population adaptation to climate variation across a radiation: implications for adaptation to climate change

Global warming will impact species in a number of ways, and it is important to know the extent to which natural populations can adapt to anthropogenic climate change by natural selection. Parallel microevolution within separate species can demonstrate natural selection, but several studies of homoplasy have not yet revealed examples of widespread parallel evolution in a generic radiation. Taking into account primary phylogeographic divisions, we investigate numerous quantitative traits (size, shape, scalation, colour pattern and hue) in anole radiations from the mountainous Lesser Antillean islands. Adaptation to climatic differences can lead to very pronounced differences between spatially close populations with all studied traits showing some evidence of parallel evolution. Traits from shape, scalation, pattern and hue (particularly the latter) show widespread evolutionary parallels within these species in response to altitudinal climate variation greater than extreme anthropogenic climate change predicted for 2080. This gives strong evidence of the ability to adapt to climate variation by natural selection throughout this radiation. As anoles can evolve very rapidly, it suggests anthropogenic climate change is likely to be less of a conservation threat than other factors, such as habitat loss and invasive species, in this, Lesser Antillean, biodiversity hot spot.     

Analysing growth and development of plants jointly using developmental growth stages

Background and Aims Plant growth, the increase of organ dimensions over time, and development, the change in plant structure, are often studied as two separate processes. However, there is structural and functional evidence that these two processes are strongly related. The aim of this study was to investigate the co-ordination between growth and development using mango trees, which have well-defined developmental stages.Methods Developmental stages, determined in an expert way, and organ sizes, determined from objective measurements, were collected during the vegetative growth and flowering phases of two cultivars of mango, Mangifera indica. For a given cultivar and growth unit type (either vegetative or flowering), a multistage model based on absolute growth rate sequences deduced from the measurements was first built, and then growth stages deduced from the model were compared with developmental stages.Key Results Strong matches were obtained between growth stages and developmental stages, leading to a consistent definition of integrative developmental growth stages. The growth stages highlighted growth asynchronisms between two topologically connected organs, namely the vegetative axis and its leaves.Conclusions Integrative developmental growth stages emphasize that developmental stages are closely related to organ growth rates. The results are discussed in terms of the possible physiological processes underlying these stages, including plant hydraulics, biomechanics and carbohydrate partitioning.     

Three-dimensional structure of the ion-chanel forming peptide trichorzianin TA VII bound to sodium dodecyl sulfate micelles

Trichorzianin TA VII, Ac⁰ U¹ A² A³ U⁴ J⁵ Q⁶ U⁷ U⁸ U⁹ S¹⁰ L¹¹ U¹² P¹³ V¹⁴ U¹⁵ I¹⁶ Q¹⁷ Q¹⁸ Fol¹⁹, is a nonadecapeptide member of the peptaibol antibiotics biosynthesized by Trichoderma soil fungi, which is characterized by a high proportion of the α,α-dialkylated amino acids, α-aminoisobutyric acid (Aib, U) and isovaline (Iva, J), an acetylated N-terminus and a C-terminal phenylalaninol (Pheol, Fol). The main interest in such peptides stems from their ability to interact with phospholipid bilayers and form voltage-dependent transmembrane channels in planar lipid bilayers. In order to provide insights into the lipid-peptide interaction promoting the voltage gating, the conformational study of TA VII in the presence of perdeuterated sodium dodecyl sulfate (SDS-d25) micelles has been carried out. ¹H sequential assignments have been performed with the use of two-dimensional homo- and -heteronuclear nmr techniques including double quantum filtered correlated spectroscopy, homonuclear Hartmann-Hahn, nuclear Overhauser effect spectroscopy, ¹H-¹³C heteronuclear single quantum correlation, and heteronuclear multiple bond correlation. Conformational parameters, such as ³ J _NHCαH coupling constants, temperature coefficients of amide protons (Δδ/Δ T _NH) and quantitative nuclear Overhauser enhancement data, lead to detailed structural information. Ninety-eight three-dimensional structures consistent with the nmr data were generated from 231 interproton distances and six Φ dihedral angle restraints, using restrained molecular dynamics and energy minimization calculations. The average rms deviation between the 98 refined structures and the energy-minimized average structure is 0.59 Å for the backbone atoms. The structure of trichorzianin TA VII associated with SDS micelles, as determined by these methods, is characterized by two right-handed helical segments involving residues 1–8 and 11–19, linked by a β-turn that leads to an angle about 90°–100° between the two helix axes; residues 18 and 19 at the end of the C-terminal helix exhibit multiple conformations. © 1998 John Wiley & Sons, Inc. Biopoly 46: 75–88, 1998     

The noncoding RNA CcnA modulates the master cell cycle regulators CtrA and GcrA in Caulobacter crescentus

Bacteria are powerful models for understanding how cells divide and accomplish global regulatory programs. In Caulobacter crescentus, a cascade of essential master regulators supervises the correct and sequential activation of DNA replication, cell division, and development of different cell types. Among them, the response regulator CtrA plays a crucial role coordinating all those functions. Here, for the first time, we describe the role of a novel factor named CcnA (cell cycle noncoding RNA A), a cell cycle–regulated noncoding RNA (ncRNA) located at the origin of replication, presumably activated by CtrA, and responsible for the accumulation of CtrA itself. In addition, CcnA may be also involved in the inhibition of translation of the S-phase regulator, GcrA, by interacting with its 5′ untranslated region (5′ UTR). Performing in vitro experiments and mutagenesis, we propose a mechanism of action of CcnA based on liberation (ctrA) or sequestration (gcrA) of their ribosome-binding site (RBS). Finally, its role may be conserved in other alphaproteobacterial species, such as Sinorhizobium meliloti, representing indeed a potentially conserved process modulating cell cycle in Caulobacterales and Rhizobiales.

During cell cycle progression in the bacterium Caulobacter crescentus, the master cell cycle regulator CtrA is controlled by CcnA, a cell cycle-regulated non-coding RNA transcribed from a gene located at the origin of replication.     

Differential resistance to freezing and spatial distribution in a chemically polymorphic plant Thymus vulgaris

Secondary compounds play multiple ecological roles. In this study, we present novel experimental evidence of differential tolerance to freezing temperatures among chemotypes of a chemically polymorphic plant, Thymus vulgaris. Non‐phenolic chemotypes showed a significantly better survival and re‐growth after early‐winter freezing (?10° in early December) than phenolic chemotypes. Comparison of temperature data (1971–2002) at a phenolic and non‐phenolic site showed that whereas early‐winter freezing occurred in 6 years in the non‐phenolic site they never occurred at the phenolic site. Observations of trichome morphology (where the essential oil is stocked) with and without intense freezing indicate that non‐phenolic chemotypes may escape any negative effects of freezing by releasing their essential oil into the atmosphere during severe freezing. The correlation between tolerance of freezing and local temperature regimes strongly suggests that differential freezing resistance is a key ingredient of the distribution of thyme chemotypes in space.     

Design and biological activity of imidazole-containing peptidomimetics with a broad-spectrum antioxidant activity

Histidine-containing natural dipeptides, such as L-carnosine, were reported to be effective against different oxygen-derived free radicals, and also lipoperoxyl radicals. However, L-carnosine appeared to be uneffective in vivo, due to the presence of ubiquitous specific or semi-specific hydrolytic enzymes. Therefore, a series of peptidomimetics were synthesized in order to confer resistance to enzymatic hydrolysis. Some structural modifications were also done in an attempt to improve the antioxidant power of the molecule, for example, in relation to binding of ferrous ions. The following methods were used for the evaluation of peptidomimetics:– The resistance to enzymatic deactivation was determined using either a purified specific enzyme or a multi-enzymatic system.– The free radical scavenging potential was measured by different in vitro methods involving different free radical species and biological targets.– Deactivation of lipid hydroperoxides was monitored by HPLC and protection of membrane phospholipids and proteins was demonstrated.– The effectiveness of peptidomimetics in vivo was evaluated.It was shown that decarboxylation of L-carnosine results in an important improvement of the resistance towards hydrolytic enzymes. In vitro experiments have demonstrated, for a series of peptidomimetics, free radical scavenging and lipid hydroperoxide deactivating properties similar to or even better than the natural peptide (depending on the experimental design). In addition, the two peptidomimetics -alanylhistamine and L-prolylhistamine proved to be far superior in inhibiting the lipid hydroperoxide-mediated cross-linking of a representative protein. Finally, -alanylhistamine was able to protect skin enzymes from UV-induced degradation in vivo.     

Using γ-emitting artificial radionuclides,released by nuclear plants,as markers of restricted movements by chub,Leuciscus cephalus,in a large river,the Lower Rhône

Synopsis On the basis that -emitting artificial radionuclides, present in nuclear plant radioactive wastes, can be considered as natural collective markers of fish living downstream from a radioactive discharge, we studied the restricted movements of chub in a reservoir on the Lower Rhône river where the Marcoule nuclear plant is located. A qualitative determination, based on the detection of specific radioelements in our samples originating from radioactive waste, and a quantitative determination of the cesium-137 concentration in the samples, were used to identify fish radioactively marked by the effluent. Individual measurements of -radioactivity in 49 adult chub captured at two stations, each 2 km long and 6 km apart, divided the fish into two distinct sub-units: one living downstream of the discharge pipe, in which 73% were marked, and the other upstream, in which 79% were not marked. Similar results were found in two neighbouring stations when we analysed previous radioecological measurements of -radioactivity in groups of chub. After combining all the data concerning chub, detailed information was obtained on the spatial stability of the chub population in the reservoir. Two spatially different stocks were found and each stock can be divided in two components: a sedentary component that remains in a restricted zone (its home range), and a mobile component that undertakes movements between the two zones.     

BAC end sequences corresponding to the B4 resistance gene cluster in common bean: a resource for markers and synteny analyses

In common bean, a complex disease resistance (R) gene cluster, harboring many specific R genes against various pathogens, is located at the end of the linkage group B4. A BAC library of the Meso-american bean genotype BAT93 was screened with PRLJ1, a probe previously shown to be specific to the B4 R gene cluster, leading to the identification of 73 positive BAC clones. BAC-end sequencing (BES) of the 73 positive BACs generated 75 kb of sequence. These BACs were organized into 6 contigs, all mapped at the B4 R gene cluster. To evaluate the potential of BES for marker development, BES-derived specific primers were used to check for linkage with two allelic anthracnose R specificities Co-3 and Co-3 ( 2 ), through the analysis of pairs of Near Isogenic Lines (NILs). Out of 32 primer pairs tested, two revealed polymorphisms between the NILs, confirming the suspected location of Co-3 and Co-3 ( 2 ) at the B4 cluster. In order to identify the orthologous region of the B4 R gene cluster in the two model legume genomes, bean BESs were used as queries in TBLASTX searches of Medicago truncatula and Lotus japonicus BAC clones. Putative orthologous regions were identified on chromosome Mt6 and Lj2, in agreement with the colinearity observed between Mt and Lj for these regions.