Environmental-dependent proline accumulation in plants living on gypsum soils

Biosynthesis of proline—or other compatible solutes—is a conserved response of all organisms to different abiotic stress conditions leading to cellular dehydration. However, the biological relevance of this reaction for plant stress tolerance mechanisms remains largely unknown, since there are very few available data on proline levels in stress-tolerant plants under natural conditions. The aim of this work was to establish the relationship between proline levels and different environmental stress factors in plants living on gypsum soils. During the 2-year study (2009–2010), soil parameters and climatic data were monitored, and proline contents were determined, in six successive samplings, in ten taxa present in selected experimental plots, three in a gypsum area and one in a semiarid zone, both located in the province of Valencia, in south-east Spain. Mean proline values varied significantly between species; however, seasonal variations within species were in many cases even wider, with the most extreme differences registered in Helianthemum syriacum (almost 30 μmol g^?1 of DW in summer 2009, as compared to ca. 0.5 in spring, in one of the plots of the gypsum zone). Higher proline contents in plants were generally observed under lower soil humidity conditions, especially in the 2009 summer sampling preceded by a severe drought period. Our results clearly show a positive correlation between the degree of environmental stress and the proline level in most of the taxa included in this study, supporting a functional role of proline in stress tolerance mechanisms of plants adapted to gypsum. However, the main trigger of proline biosynthesis in this type of habitat, as in arid or semiarid zones, is water deficit, while the component of ‘salt stress’ due to the presence of gypsum in the soil only plays a secondary role.     

DEAD-Box RNA Helicases in Bacillus subtilis Have Multiple Functions and Act Independently from Each Other

DEAD-box RNA helicases play important roles in remodeling RNA molecules and in facilitating a variety of RNA-protein interactions that are key to many essential cellular processes. In spite of the importance of RNA, our knowledge about RNA helicases is limited. In this study, we investigated the role of the four DEAD-box RNA helicases in the Gram-positive model organism Bacillus subtilis. A strain deleted of all RNA helicases is able to grow at 37°C but not at lower temperatures. The deletion of cshA, cshB, or yfmL in particular leads to cold-sensitive phenotypes. Moreover, these mutant strains exhibit unique defects in ribosome biogenesis, suggesting distinct functions for the individual enzymes in this process. Based on protein accumulation, severity of the cold-sensitive phenotype, and the interaction with components of the RNA degradosome, CshA is the major RNA helicase of B. subtilis. To unravel the functions of CshA in addition to ribosome biogenesis, we conducted microarray analysis and identified the ysbAB and frlBONMD mRNAs as targets that are strongly affected by the deletion of the cshA gene. Our findings suggest that the different helicases make distinct contributions to the physiology of B. subtilis. Ribosome biogenesis and RNA degradation are two of their major tasks in B. subtilis.     

Rotavirus Viroplasm Proteins Interact with the Cellular SUMOylation System: Implications for Viroplasm-Like Structure Formation

Posttranslational modification by SUMO provides functional flexibility to target proteins. Viruses interact extensively with the cellular SUMO modification system in order to improve their replication, and there are numerous examples of viral proteins that are SUMOylated. However, thus far the relevance of SUMOylation for rotavirus replication remains unexplored. In this study, we report that SUMOylation positively regulates rotavirus replication and viral protein production. We show that SUMO can be covalently conjugated to the viroplasm proteins VP1, VP2, NSP2, VP6, and NSP5. In addition, VP1, VP2, and NSP2 can also interact with SUMO in a noncovalent manner. We observed that an NSP5 SUMOylation mutant protein retains most of its activities, such as its interaction with VP1 and NSP2, the formation of viroplasm-like structures after the coexpression with NSP2, and the ability to complement in trans the lack of NSP5 in infected cells. However, this mutant is characterized by a high degree of phosphorylation and is impaired in the formation of viroplasm-like structures when coexpressed with VP2. These results reveal for the first time a positive role for SUMO modification in rotavirus replication, describe the SUMOylation of several viroplasm resident rotavirus proteins, and demonstrate a requirement for NSP5 SUMOylation in the production of viroplasm-like structures.     

The first record of Lutzomyia longipalpis in the Argentine northwest

In 2004, the urban presence of Lutzomyia longipalpis was recorded for the first time in Formosa province. In 2006, the first autochthonous case of human urban visceral leishmaniasis (VL) was recorded in Misiones in the presence of the vector, along with some canine VL cases. After this first case, the vector began to spread primarily in northeast Argentina. Between 2008-2011, three human VL cases were reported in Salta province, but the presence of Lu. longipalpis was not recorded. Captures of Phlebotominae were made in Tartagal, Salta, in 2013, and the presence of Lu. longipalpis was first recorded in northwest Argentina at that time. Systematic sampling is recommended to observe the distribution and dispersion patterns of Lu. longipalpis and consider the risk of VL transmission in the region.     

The number of markers and samples needed for detecting bottlenecks under realistic scenarios,with and without recovery: a simulation‐based study

Detecting bottlenecks is a common task in molecular ecology. While several bottleneck detection methods exist, evaluations of their power have focused only on severe bottlenecks (e.g. to Ne ~10). As a component of a recent review, Peery et al. ( 2012 ) analysed the power of two approaches, the M‐ratio and heterozygote excess tests, to detect moderate bottlenecks (e.g. to Ne ~100), which is realistic for many conservation situations. In this Comment, we address three important points relevant to but not considered in Peery et al. Under moderate bottleneck scenarios, we test the (i) relative advantage of sampling more markers vs. more individuals, (ii) potential power to detect the bottleneck when utilizing dozens of microsatellites (a realistic possibility for contemporary studies) and (iii) reduction in power when postbottleneck recovery has occurred. For the realistic situations examined, we show that (i) doubling the number of loci shows equal or better power than tripling the number of individuals, (ii) increasing the number of markers (up to 100) results in continued additive gains in power, and (iii) recovery after a moderate amount of time or gradual change in size reduces power, by up to one‐half. Our results provide a practical supplement to Peery et al. and encourage the continued use of bottleneck detection methods in the genomic age, but also emphasize that the power under different sampling schemes should be estimated, using simulation modelling, as a routine component of molecular ecology studies.     

Two new Cocconeis taxa (Bacillariophyceae) from coral sands off the Mascarenes (Western Indian Ocean) and some related unidentified taxa

Coral sands off Réunion Island and Rodrigues (Mascarene archipelago, Western Indian Ocean) support diverse diatom communities, particularly rich in Monoraphidineae. Recent surveys of reef environments (June 2005 and June 2007) permitted the recognition of several taxa belonging to the diatom genus Cocconeis, among which are two new, relatively small taxa, epipsammic on coral sand. Cocconeis coronata Riaux-Gobin et Romero sp. nov. is similar to C. scutellum but has its own distinctive features. In external view, the concave raphe valve possesses uniseriate striae and a subsident hyaline marginal rim, while the strongly convex sternum valve has a submarginal, generally continuous crest, a hexagonal pattern of areolation, short, rounded spines that are often regularly arranged around valve face areolae, a complex areola hymen and small marginal chambers. Some morphometric differences were noted between the populations of C. coronata at Réunion and Rodrigues. Cocconeis margaritata Riaux-Gobin et Al-Handal, sp. nov. is smaller, possesses a sternum valve like that of C. placentula and C. neothumensis, but has denser striation and small pearl-like concretions around the areola aperture on the sternum valve. Several other taxa that resemble, or may be varieties of, C. margaritata require further study before being formally described. Cocconeis margaritata and C. coronata are small and relatively rare, so their study requires scanning electron microscopy.