REDUCED DROUGHT TOLERANCE DURING DOMESTICATION AND THE EVOLUTION OF WEEDINESS RESULTS FROM TOLERANCE–GROWTH TRADE‐OFFS

The increased reproductive potential, size, shoot allocation, and growth rate of weedy plants may result from reduced resource allocation to other aspects of plant growth and defense. To investigate whether changes in resource allocation occurred during domestication or the evolution of weediness, we compared the mycorrhizal responsiveness, growth, and drought tolerance of nine native ruderal, nine agriculturally weedy (four U.S. weedy and five Australian weedy), and 14 domesticated populations (eight ancient landraces and six improved cultivars) of the common sunflower (Helianthus annuus). Domesticated sunflower cultivars were less drought tolerant, but had higher plant growth and fecundity and coarser roots than wild populations. There were no changes in level of drought tolerance between improved cultivars and ancient landrace plants, but there was an increase in allocation to flowers with recent selection. Weedy populations were intermediate between domesticated cultivars and native ruderal populations for plant growth rate, root architecture, and drought tolerance. Weedy populations benefited most from mycorrhizal inoculation by having fewer wilted leaves and wetter soil. Overall, we found that trade‐offs between drought tolerance and several aspects of plant growth, including growth rate, allocation to flowering, and root architecture, govern evolution during sunflower domestication and the invasion of disturbed habitat.     

Looking for Landmarks: The Role of Expert Review and Bibliometric Analysis in Evaluating Scientific Publication Outputs

Objective

To compare expert assessment with bibliometric indicators as tools to assess the quality and importance of scientific research papers.

Methods and Materials

Shortly after their publication in 2005, the quality and importance of a cohort of nearly 700 Wellcome Trust (WT) associated research papers were assessed by expert reviewers; each paper was reviewed by two WT expert reviewers. After 3 years, we compared this initial assessment with other measures of paper impact.

Results

Shortly after publication, 62 (9%) of the 687 research papers were determined to describe at least a ‘major addition to knowledge’ –6 were thought to be ‘landmark’ papers. At an aggregate level, after 3 years, there was a strong positive association between expert assessment and impact as measured by number of citations and F1000 rating. However, there were some important exceptions indicating that bibliometric measures may not be sufficient in isolation as measures of research quality and importance, and especially not for assessing single papers or small groups of research publications.

Conclusion

When attempting to assess the quality and importance of research papers, we found that sole reliance on bibliometric indicators would have led us to miss papers containing important results as judged by expert review. In particular, some papers that were highly rated by experts were not highly cited during the first three years after publication. Tools that link expert peer reviews of research paper quality and importance to more quantitative indicators, such as citation analysis would be valuable additions to the field of research assessment and evaluation.     

Role of iron-reducing bacteria in corrosion and protection of carbon steel

The role of iron-reducing bacteria (IRB) in biocorrosion is under discussion. According to some reports, IRB are able to induce protection of carbon steel while others suggest an important enhancement of corrosion through the reduction and removal of passive films of ferric compounds on the metal surface. In this work, we review recent knowledge concerning microbial respiration, the ecology of IRB containing biofilms and the corrosive or protective effect of such biofilms on metal surfaces.     

New Genotype of Dengue Type 3 Virus Circulating in Brazil and Colombia Showed a Close Relationship to Old Asian Viruses

Dengue type 3 genotype V viruses have been recently detected in Brazil and Colombia. In this study, we described another Brazilian isolate belonging to this genotype. Phylogenetic analysis including dengue type 3 viruses isolated worldwide showed that Brazilian and Colombian viruses were closely related to viruses isolated in Asia more than two decades ago. The characteristic evolutionary pattern of dengue type 3 virus cannot explain the close similarity of new circulating viruses with old viruses. Further studies are needed to confirm the origin of the new dengue type III genotype circulating in Brazil and Colombia.     

Cartilage oligomeric matrix protein-deficient mice have normal skeletal development

Cartilage oligomeric matrix protein (COMP) belongs to the thrombospondin family and is a homopentamer primarily expressed in cartilage. Mutations in the COMP gene result in the autosomal dominant chondrodysplasias pseudoachondroplasia (PSACH) and some types of multiple epiphyseal dysplasia (MED), which are characterized by mild to severe short-limb dwarfism and early-onset osteoarthritis. We have generated COMP-null mice to study the role of COMP in vivo. These mice show no anatomical, histological, or ultrastructural abnormalities and show none of the clinical signs of PSACH or MED. Northern blot analysis and immunohistochemical analysis of cartilage indicate that the lack of COMP is not compensated for by any other member of the thrombospondin family. The results also show that the phenotype in PSACH/MED cartilage disorders is not caused by the reduced amount of COMP.     

High initial activity but low storage stability observed for several preparations of subtilisin Carslberg suspended in organic solvents

Colyophilization with methyl-beta-cyclodextrin activates subtilisin Carlsberg by more than 200-fold in organic solvents, though this is a short-lived effect. About 93% of the enzyme's high initial activity observed in THF (at 45 degrees C) decreases exponentially with a t(1/2) of 1.8 h, until it reaches a residual activity (of 7%) that remains constant throughout the 4 days duration of the experiment. A further study of this enzyme reveals a general trend: the initial activities of the lyophilized powder and the cross-linked enzyme crystals are also greatly reduced upon incubation in this solvent, although these preparations retain 50% of their activity after about 20 h of incubation. All of the preparations studied retained some residual activity (which persisted throughout the duration of the experiments) after the initial exponential decay. The data here presented suggest that the mode of enzyme preparation is an important issue to consider when planning lengthy reactions.     

Site2 binding energetics of the regulatory step of growth hormone-induced receptor homodimerization

Receptor signaling in the growth hormone (GH)-growth hormone receptor (GHR) system is controlled through a sequential two-step hormone-induced dimerization of two copies of the extracellular domain (ECD) of the receptor. The regulatory step of this process is the binding of the second ECD (ECD2) to the stable preassociated 1 : 1 GH/ECD1 complex on the cell surface. To determine the energetics that governs this step, the binding kinetics of 38 single- and double-alanine mutants in the hGH Site2 contact with ECD2 were measured by using trimolecular surface plasmon resonance (TM-SPR). We find that the Site2 interface of hGH does not have a distinct binding hot-spot region, and the most important residues are not spatially clustered, but rather are distributed over the whole binding surface. In addition, it was determined through analysis of a set of pairwise double alanine mutations that there is a significant degree of negative cooperativity among Site2 residues. Residues that show little effect or even improved binding on substitution with alanine, when paired with D116A-hGH, display significant negative cooperativity. Because most of these pairwise mutated residues are spatially separated by >or=10 A, this indicates that the Site2 binding interface of the hGH-hGHR ternary complex displays both structural and energetic malleability.     

Effect of Vibrio alginolyticus on larval survival of the blue mussel Mytilus galloprovincialis

The effect of increasing concentrations of Vibrio alginolyticus on survival of Mytilus galloprovincialis larvae was studied in a 48 h static bioassay in 1 l glass bottles. Five bacterial densities were tested ranging from 10(2) to 10(6) bacteria ml(-1). Larval survival and normality (veliger larvae with the typical D-shape) were evaluated after 48 h. An inverse relationship between bacterial concentration and larval survival and normality was observed. In spite of high larval survival (79%) under conditions of high bacterial density (10(5) bacteria ml(-1)), the percent of normal larvae was 11%. Besides an irregular shape, abnormal larvae also presented velum reduction. Results from this study suggest that concentrations of V. alginolyticus lower than 10(3) bacteria ml(-1) should be maintained during M. galloprovincialis larval culture.     

Use of viral vectors for vaccine production in plants

The small size of plant viral genomes, the ease with which they can be manipulated, and the simplicity of the infection process is making the viral vectors an attractive alternative to the transgenic systems for the expression of foreign proteins in plants. One use of these virus expression systems is for vaccine production. There are two basic types of viral system that have been developed for the production of immunogenic peptides and proteins in plants: epitope presentation and polypeptide expression systems. In this review, we discuss advances made in this field.     

Rhizodeposition and the enhanced mineralization of 2,4-dichlorophenoxyacetic acid in soil from the Trifolium pratense rhizosphere

Enhanced biodegradation of organic xenobiotic compounds in the rhizosphere is frequently recorded although the specific mechanisms are poorly understood. We have shown that the mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) is enhanced in soil collected from the rhizosphere of Trifolium pratense[e.g. maximum mineralization rate=7.9 days-1 and time at maximum rate (t1)=16.7 days for 12-day-old T. pratense soil in comparison with 4.7 days-1 and 25.4 days, respectively, for non-planted controls). The purpose of this study was to gain a better understanding of the plant-microbe interactions involved in rhizosphere-enhanced biodegradation by narrowing down the identity of the T. pratense rhizodeposit responsible for stimulating the microbial mineralization of 2,4-D. Specifically, we investigated the distribution of the stimulatory component(s) among rhizodeposit fractions (exudates or root debris) and the influence of soil properties and plant species on its production. Production of the stimulatory rhizodeposit was dependent on soil pH (e.g. t1 for roots grown at pH 6.5 was significantly lower than for those grown at pH 4.4) but independent of soil inorganic N concentration. Most strikingly, the stimulatory rhizodeposit was only produced by T. pratense grown in non-sterile soil and was present in both exudates and root debris. Comparison of the effect of root debris from plant species (three each) from the classes monocotyledon, dicotyledon (non-legume) and dicotyledon (legume) revealed that legumes had by far the greatest positive impact on 2,4-D mineralization kinetics. We discuss the significance of these findings with respect to legume-rhizobia interactions in the rhizosphere.