The plant glycosyltransferase clone collection for functional genomics

The glycosyltransferases (GTs) are an important and functionally diverse family of enzymes involved in glycan and glycoside biosynthesis. Plants have evolved large families of GTs which undertake the array of glycosylation reactions that occur during plant development and growth. Based on the Carbohydrate‐Active enZymes (CAZy) database, the genome of the reference plant Arabidopsis thaliana codes for over 450 GTs, while the rice genome (Oryza sativa) contains over 600 members. Collectively, GTs from these reference plants can be classified into over 40 distinct GT families. Although these enzymes are involved in many important plant specific processes such as cell‐wall and secondary metabolite biosynthesis, few have been functionally characterized. We have sought to develop a plant GTs clone resource that will enable functional genomic approaches to be undertaken by the plant research community. In total, 403 (88%) of CAZy defined Arabidopsis GTs have been cloned, while 96 (15%) of the GTs coded by rice have been cloned. The collection resulted in the update of a number of Arabidopsis GT gene models. The clones represent full‐length coding sequences without termination codons and are Gateway^® compatible. To demonstrate the utility of this JBEI GT Collection, a set of efficient particle bombardment plasmids (pBullet) was also constructed with markers for the endomembrane. The utility of the pBullet collection was demonstrated by localizing all members of the Arabidopsis GT14 family to the Golgi apparatus or the endoplasmic reticulum (ER). Updates to these resources are available at the JBEI GT Collection website http://www.addgene.org/ .     

Leaf ontogeny of <Emphasis Type="Italic">Schinus molle</Emphasis> L. plants under cadmium contamination: the meristematic origin of leaf structural changes

Previous works show the development of thicker leaves on tolerant plants growing under cadmium (Cd²⁺) contamination. The aim of this study was to evaluate the Cd²⁺ effects on the leaf meristems of the tolerant species Schinus molle. Plants were grown in nutrient solution containing 0, 10, and 50 μM of Cd²⁺. Anatomical analysis was performed on leaf primordia sampled at regular time intervals. Under the lowest Cd²⁺ level (10 μM), increased ground meristem thickness, diameter of the cells, cell elongation rate, and leaf dry mass were found. However, 50 μM of Cd²⁺ reduced all these variables. In addition, the ground meristem cells became larger when exposed to any Cd²⁺ level. The epidermis, palisade parenchyma, and vascular tissues developed earlier in Cd²⁺-exposed leaves. The modifications found on the ground meristem may be related to the development of thicker leaves on S. molle plants exposed to low Cd²⁺ levels. Furthermore, older leaves showed higher Cd²⁺ content when compared to the younger ones, preventing the Cd²⁺ toxicity to these leaves. Thus, low Cd²⁺ concentrations change the ground meristem structure and function reflecting on the development of thicker and enhanced leaves.     

Genome Sequence of Hybrid Vibrio cholerae O1 MJ-1236, B-33, and CIRS101 and Comparative Genomics with V. cholerae

The genomes of Vibrio cholerae O1 Matlab variant MJ-1236, Mozambique O1 El Tor variant B33, and altered O1 El Tor CIRS101 were sequenced. All three strains were found to belong to the phylocore group 1 clade of V. cholerae, which includes the 7th-pandemic O1 El Tor and serogroup O139 isolates, despite displaying certain characteristics of the classical biotype. All three strains were found to harbor a hybrid variant of CTXΦ and an integrative conjugative element (ICE), leading to their establishment as successful clinical clones and the displacement of prototypical O1 El Tor. The absence of strain- and group-specific genomic islands, some of which appear to be prophages and phage-like elements, seems to be the most likely factor in the recent establishment of dominance of V. cholerae CIRS101 over the other two hybrid strains.Vibrio cholerae, a bacterium autochthonous to the aquatic environment, is the causative agent of cholera, a life-threatening disease that causes severe, watery diarrhea. Cholera bacteria are serogrouped based on their somatic O antigens, with more than 200 serogroups identified to date (6). Only toxigenic strains of serogroups O1 and O139 have been identified as agents of cholera epidemics and pandemics; serogroups other than O1 and O139 have the potential to cause mild gastroenteritis or, rarely, local outbreaks. Genes coding for cholera toxin (CTX), ctxAB, and other virulence factors have been shown to reside in bacteriophages and various mobile genetic elements. In addition, V. cholerae serogroup O1 is differentiated into two biotypes, classical and El Tor, by a combination of biochemical traits, by sensitivity to biotype-specific bacteriophages, and more recently by nucleotide sequencing of specific genes and by molecular typing (5, 17, 19).There have been seven pandemics of cholera recorded throughout human history. The seventh and current pandemic began in 1961 in the Indonesian island of Sulawesi and subsequently spread to Asia, Africa, and Latin America; the six previous pandemics are believed to have originated in the Indian subcontinent. Isolates of the sixth pandemic were almost exclusively of the O1 classical biotype, whereas the current (seventh) pandemic is dominated by the V. cholerae O1 El Tor biotype as the causative agent, a transition occurring between 1923 and 1961. Today, the disease continues to remain a scourge in developing countries, confounded by the fact that V. cholerae is native to estuaries and river systems throughout the world (8).Over the past 20 years, several new epidemic lineages of V. cholerae O1 El Tor have emerged (or reemerged). For example, in 1992, a new serogroup, namely, O139 of V. cholerae, was identified as the cause of epidemic cholera in India and Bangladesh (25). The initial concern was that a new pandemic was beginning; however, the geographic range of V. cholerae O139 is currently restricted to Asia. Additionally, V. cholerae O1 hybrids and altered El Tor variants have been isolated repeatedly in Bangladesh (Matlab) (23, 24) and Mozambique (1). Altered V. cholerae O1 El Tor isolates produce cholera toxin of the classical biotype but can be biotyped as El Tor by conventional phenotypic assays, whereas V. cholerae O1 hybrid variants cannot be biotyped based on phenotypic tests and can produce cholera toxin of either biotype. These new variants have subsequently replaced the prototype seventh-pandemic V. cholerae O1 El Tor strains in Asia and Africa, with respect to frequency of isolation from clinical cases of cholera (27).Here, we report the genome sequence of three V. cholerae O1 variants, MJ-1236, a Matlab type I hybrid variant from Bangladesh that cannot be biotyped by conventional methods, CIRS101, an altered O1 El Tor isolate from Bangladesh which harbors ctxB of classical origin, and B33, an altered O1 El Tor isolate from Mozambique which harbors classical CTXΦ, and we compare their genomes with prototype El Tor and classical genomes. From an epidemiological viewpoint, among the three variants characterized in this study, V. cholerae CIRS101 is currently the most “successful” in that strains belonging to this type have virtually replaced the prototype El Tor in Asia and many parts of Africa, notably East Africa. This study, therefore, gives us a unique opportunity to understand why V. cholerae CIRS101 is currently the most successful El Tor variant.     

Rainfall manipulation experiments as simulated by terrestrial biosphere models: Where do we stand?

Changes in rainfall amounts and patterns have been observed and are expected to continue in the near future with potentially significant ecological and societal consequences. Modelling vegetation responses to changes in rainfall is thus crucial to project water and carbon cycles in the future. In this study, we present the results of a new model‐data intercomparison project, where we tested the ability of 10 terrestrial biosphere models to reproduce the observed sensitivity of ecosystem productivity to rainfall changes at 10 sites across the globe, in nine of which, rainfall exclusion and/or irrigation experiments had been performed. The key results are as follows: (a) Inter‐model variation is generally large and model agreement varies with timescales. In severely water‐limited sites, models only agree on the interannual variability of evapotranspiration and to a smaller extent on gross primary productivity. In more mesic sites, model agreement for both water and carbon fluxes is typically higher on fine (daily–monthly) timescales and reduces on longer (seasonal–annual) scales. (b) Models on average overestimate the relationship between ecosystem productivity and mean rainfall amounts across sites (in space) and have a low capacity in reproducing the temporal (interannual) sensitivity of vegetation productivity to annual rainfall at a given site, even though observation uncertainty is comparable to inter‐model variability. (c) Most models reproduced the sign of the observed patterns in productivity changes in rainfall manipulation experiments but had a low capacity in reproducing the observed magnitude of productivity changes. Models better reproduced the observed productivity responses due to rainfall exclusion than addition. (d) All models attribute ecosystem productivity changes to the intensity of vegetation stress and peak leaf area, whereas the impact of the change in growing season length is negligible. The relative contribution of the peak leaf area and vegetation stress intensity was highly variable among models.     

Is There Division of Labor in Cooperative Pseudoscorpions? An Analysis of the Behavioral Repertoire of a Tropical Species

Division of labor is a strategy that maximizes the foraging and reproductive success of eusocial insects. Although some arachnids exhibit colony structure and social organization similar to that of hymenopterans, temporal polyethism has only been demonstrated in few species. The social organization of cooperative pseudoscorpions Paratemnoides nidificator is similar to that of social spiders, but it involves a clear division of labor. Work allocation was experimentally investigated in colonies composed of only one developmental stage (young or adults) or by one sex (males or females), through laboratory manipulation. During 44 h of observation, more than 14 000 behavioral repetitions were quantified, distributed in 95 different types of behavioral acts, and grouped in 10 behavioral categories. The results showed that reproductive colonies of P. nidificator are maintained by gender‐ and age‐based activities. Males and non‐reproductive females performed the external cleaning of the colony and prey capture. Reproductive females take care of the juveniles and build reproductive silk chambers. Nymphs build most of the molt chambers and perform internal cleaning. In the absence of nymphs, male colonies survived 1–2 mo, while female colonies survived 3–4 mo. In nymph colonies, work is readjusted so that all maintenance tasks are executed. This is the first study clearly demonstrating division of tasks in arachnids. It suggests that specialization is an adaptative and evolutionarily old trait in this species. Unlike cooperative spiders, P. nidificator possesses physiological (e.g. reproduction, ecdysis, lifespan) and behavioral (e.g. behavioral synchrony or self‐organization) characteristics that allow task specialization.     

Length–weight relationships of 26 fish species from the middle section of the Negro River (Tacuarembó‐Durazno,Uruguay)

This study provides data on the length–weight relationship (LWR) for 26 species of neotropical fishes. Specimens were collected between 2008 and 2009 from a dam‐enclosed section of the middle Negro River (Uruguay). This study represents the first reference on length–weight relationships for 17 species, and also provides new maximum sizes for eight species.