rRNA based identification and detection systems for rhizobia and other bacteria

Ribosomal ribonucleic acids are excellent marker molecules for the elucidation of bacterial phylogeny; they also provide useful target sites for identification and detection with nucleic acid probes. Based on the currently available 16S rRNA sequence data, bacteria of the rhizobial phenotype (plant nodulation, nitrogen fixation) are members of three moderately related phylogenetic sub-groups of the -subclass of the Proteobacteria: i.e. the rhizobia group, the bradyrhizobia group, and the azorhizobia group. All rhizobia, azo-, brady-, meso- and sinorhizobia are closely related to and in some cases phylogenetically intermixed with, non-symbiotic and/or non-nitrogen-fixing bacteria. Especially in the case of Bradyrhizobium japonicum strains, the 16S rRNA sequence data indicate substantial heterogeneity. Specific probe design and evaluation are discussed. A multiprobe concept for resolving specificity problems with group specific probes is presented. In situ identification with group specific probes of rhizobia in cultures as well as rhizobia and cyanobacteria within plant material is shown.     

Multimorbidity and Its Patterns according to Immigrant Origin. A Nationwide Register-Based Study in Norway

Introduction

As the flows of immigrant populations increase worldwide, their heterogeneity becomes apparent with respect to the differences in the prevalence of chronic physical and mental disease. Multimorbidity provides a new framework in understanding chronic diseases holistically as the consequence of environmental, social, and personal risks that contribute to increased vulnerability to a wide variety of illnesses. There is a lack of studies on multimorbidity among immigrants compared to native-born populations.

Methodology

This nationwide multi-register study in Norway enabled us i) to study the associations between multimorbidity and immigrant origin, accounting for other known risk factors for multimorbidity such as gender, age and socioeconomic levels using logistic regression analyses, and ii) to identify patterns of multimorbidity in Norway for immigrants and Norwegian-born by means of exploratory factor analysis technique.

Results

Multimorbidity rates were lower for immigrants compared to Norwegian-born individuals, with unadjusted odds ratios (OR) and 95% confidence intervals 0.38 (0.37–0.39) for Eastern Europe, 0.58 (0.57–0.59) for Asia, Africa and Latin America, and 0.67 (0.66–0.68) for Western Europe and North America. Results remained significant after adjusting for socioeconomic factors. Similar multimorbidity disease patterns were observed among Norwegian-born and immigrants, in particular between Norwegian-born and those from Western European and North American countries. However, the complexity of patterns that emerged for the other immigrant groups was greater. Despite differences observed in the development of patterns with age, such as ischemic heart disease among immigrant women, we were unable to detect the systematic development of the multimorbidity patterns among immigrants at younger ages.

Conclusions

Our study confirms that migrants have lower multimorbidity levels compared to Norwegian-born. The greater complexity of multimorbidity patterns for some immigrant groups requires further investigation. Health care policies and practice will require a holistic approach for specific population groups in order to meet their health needs and to curb and prevent diseases.     

Bivalve distribution in hydrographic regions in South America: historical overview and conservation

Based on literature review and malacological collections, 168 native freshwater bivalve and five invasive species have been recorded for 52 hydrographic regions in South America. The higher species richness has been detected in the South Atlantic, Uruguay, Paraguay, and Amazon Brazilian hydrographic regions. Presence or absence data were analysed by Principal Coordinate for Phylogeny-Weighted. The lineage Veneroida was more representative in hydrographic regions that are poorer in species and located West of South America. The Mycetopodidae and Hyriidae lineages were predominant in regions that are richest in species toward the East of the continent. The distribution of invasive species Limnoperna fortunei is not related to species richness in different hydrographic regions there. The species richness and its distribution patterns are closely associated with the geological history of the continent. The hydrographic regions present distinct phylogenetic and species composition regardless of the level of richness. Therefore, not only should the richness be considered to be a criterion for prioritizing areas for conservation, but also the phylogenetic diversity of communities engaged in services and functional aspects relevant to ecosystem maintenance. A plan to the management of this fauna according to particular ecological characteristics and human uses of hydrographic regions is needed.     

Indicators of environmentally sound land use in the humid tropics: The potential roles of expert opinion,knowledge engineering and knowledge discovery

Despite abundant literature on indicators for sustainable resource management, practical tools to help local users to apply its general concepts at a local to regional level are scarce. This means that decisions over land evaluation and land use at a local level are often not based on the formal application of indicators or decision support systems for environmentally sound management but instead on the opinion of local expertise, for instance forest managers, cattle breeders, farmers and/or academics. This is particularly seen to be the case in the tropics where access to modern communication and information technologies is restricted.As the opinions of experts are often based on and influenced by personal experience, intuition, heuristics and bias, their evaluations and decision are often unclear to the non-expert working at a local level. In order to make their reasoning more comprehensible to the non-expert, the ecological condition of 176 plots in the tropical Southeast of Mexico were evaluated by experts on soil fertility, forest management, cattle breeding and agriculture. With the assistance of a knowledge engineer (one who converts expert knowledge and reasoning into a model), these expert opinions and reasoning were then translated into a formal computer model.As an alternative approach we applied a knowledge discovery technique, namely the induction of regression trees and automatically developed models using the expert evaluations as training data. Where knowledge engineering was tedious and time consuming, regression models could be rapidly generated. Moreover, the correspondence between regression trees and expert opinions was considerably higher than the correspondence between expert opinion and their own models. The regression trees used less explicative variables than the models generated by the experts. The minimisation of sampling effort due to variable space reduction means that the application of regression tree induction has a high potential for a rapid development of indicators for narrowly defined ecological assessments, needed for decision making on a local or regional scale.     

The role of vitellogenin during gestation of Girardinichthys viviparus and Ameca splendens; two goodeid fish with matrotrophic viviparity

Goodeid fish have matrotrophic viviparity, and unlike lecitotrophic fish, yolk loss forces the female to provide the nutritional requirements for embryonic development. Vitellogenin (VTG) is the yolk precursor protein synthesized in the maternal liver, but there is only circumstantial evidence regarding VTG supply during the ontogenesis of bony fish with matrotrophic viviparity. Therefore, the goal of the present study was to identify and quantify VTG during gestation of the black fin goodeid Girardinichthys viviparus and the butterfly split-fin goodeid Ameca splendens. Females at different gonadic developmental stages were selected in order to evaluate VTG mRNA expression in the maternal liver using RT-PCR; VTG quantification in maternal muscle and liver, as well as in the embryos, was done using ELISA, and immunohistochemical detection of VTG was done in the black fin goodeid. The results suggest that VTG supplies nutrients during embryonic development of both species, which have different life histories. It is possible that the transition from lecitotrophy to matrotrophic viviparity in bony fish with intraluminal gestation involved adaptive transition strategies that included changes in the relationship between oocytes and follicular cells, as well as a gradual loss of VTG synthesis during embryonic development.     

Regulation of the Glycine Transporter GLYT1 by microRNAs

Neurochemical Research - The glycine transporter GLYT1 participates in inhibitory and excitatory neurotransmission by controlling the reuptake of this neuroactive substance from synapses. Over the...     

Production and characterization of two N-terminal truncated esterases from Thermus thermophilus HB27 in a mesophilic yeast: effect of N-terminus in thermal activity and stability

Two N-terminally truncated variants of the esterase E34Tt from Thermus thermophilus HB27 (YP_004875.1) were expressed in Kluyveromyces lactis. Production and biochemical properties of both recombinant proteins were investigated. The esterase activity was greatly increased compared to the wild-type strain. In particular, the extracellular production of the ΔN16 variant (KLEST-3S) was 50-fold higher than that obtained with T. thermophilus HB27. Response surface methodology was applied to describe the pH and temperature dependence of both activity and stability. When compared with the wild type esterase, the optimal temperature of reaction decreased 35 and 15 °C for ΔN16 and ΔN26, respectively. KLEST-3S showed a maximum of activity at pH 7.5 and 47.5 °C, and maximal stability at pH 8.1 and 65 °C. KLEST-5A (ΔN26) did not show an absolute maximum of activity. However, best results were obtained at 40 °C and pH 8.5. KLEST-5A showed also a lower stability. In the presence of a surfactant, both proteins showed lower stability at 85 °C (t(?)< 5 min) than the wild-type enzyme (t(?)=135 min). However, in the absence of detergent, the stability of KLEST-3S was higher (t(?)=230 min, at 85 °C) than that of the mutant KLEST-5A (12 min) or the wild type enzyme (19 min). Minor differences were observed in the substrate specificity. Our results suggest that the N-terminal segment is critical for maintaining the hyperthermophilic function and stability.     

Larvae and postlarvae production of the green-white sea urchin Lytechinus variegatus (Echinodermata: Echinoidea) in culture conditions

We evaluated the biological feasibility of massive larvae and postlarvae production of the Caribbean green-white urchin Lytechinus variegatus. Experiments were designed to choose the initial larval density and microalgae diets under culture, to study metamorphosis, postlarval and juvenile growth. Massive production of competent larvae 650 microm long at 12-13 days is possible using larval densities of 0.25 to 1 larva/ml. The microalgae Rhodomonas sp. was suitable for the optimization of larval growth and survival. Metamorphosis of 100% of the larvae can be induced with films of bentic diatoms (Navicula sp. and Amphora sp.), after 96 h; however, diatoms are not adequate for postlarval development and a food supply of Ulva lactuta is necessary for proper growth. For juveniles, a diet of macroalgae (U. lactuta) and/or commercial marine shrimp culture pellet food is enough for growth, but the best results were obtained with shrimp or U. lactuta used alone (85-86%, against 46% with the mixed diet). We recommend future experiments on nutritional requirements to optimize growth of these and subsequent stages.