Molecular evolution of the mammalian alpha 2B adrenergic receptor

The alpha 2B adrenergic receptor (A2AB) is a heptahelical G protein-coupled receptor for catecholamines. We compared the almost complete coding region (about 1,175 bp) of the A2AB gene from 48 mammalian species, including eight newly determined sequences, representing all the 18 eutherian and two marsupial orders. Comparison of the encoded proteins reveals that residues thought to be involved in agonist binding are highly conserved, as are the regions playing a role in G protein-coupling. The three extracellular loops are generally more variable than the transmembrane domains and two of the intracellular loops, indicating a lower functional constraint. However, the greatest variation is observed in the very long, third intracellular loop, where only a few residues and a polyglutamyl tract are preserved. Although this polyglutamyl domain displays a great variation in length, its presence in all described A2ABs confirms its proposed role in agonist-dependent phosphorylation of the third intracellular loop. Phylogenetic analyses of the A2AB data set, including Bayesian methods, recognized the superordinal clades Afrotheria, Laurasiatheria, and Euarchontoglires, in agreement with recent molecular evidence, albeit with lower support. Within Afrotheria, A2AB strongly supports the paenungulate clade and the association of the continental African otter shrew with Malagasy tenrecs. Among Laurasiatheria, A2AB confirms the nesting of whales within the artiodactyls, as a sister group to hippopotamus. Within the Euarchontoglires, there is constant support for rodent monophyly.     

A Combined Immunofluorescence-DNA-Fluorescence Staining Technique for Enumeration of Thiobacillus ferrooxidans in a Population of Acidophilic Bacteria

An antiserum raised against whole cells of Thiobacillus ferrooxidans was allowed to react with a variety of acidophilic and nonacidophilic bacteria in an enzyme-linked immunosorbent assay and an indirect immunofluorescence assay. Both experiments demonstrated that the antiserum was specific at the species level. This preparation was used to evaluate the role of T. ferrooxidans in the microbial desulfurization process. Leaching experiments were performed, and the numbers of T. ferrooxidans cells and other bacteria were estimated by using a combined immunofluorescence-DNA-fluorescence staining technique that was adapted for this purpose. Nonsterile coal samples inoculated with T. ferrooxidans yielded high concentrations of soluble iron after 16 days. After this period, however, T. ferrooxidans cells could no longer be detected by the immunofluorescence assay, whereas the DNA-fluorescence staining procedure demonstrated a large number of microorganisms on the coal particles. These results indicate that T. ferrooxidans is removed by competition with different acidophilic microorganisms that were originally present on the coal.     

Summer social structure of crabeater seal <Emphasis Type="Italic">Lobodon carcinophaga</Emphasis> in the Amundsen Sea,Antarctica

During the PS75 expedition of ice-breaking RV Polarstern in the Amundsen Sea, in February–March 2010, we studied the at-sea quantitative distribution of the “upper trophic levels,” seabirds and marine mammals. In the Amundsen Sea Embayment, 14,200 pinnipeds belonging to four species were recorded (2100 during 670 half-hour transect counts from the bridge and 12,100 during 50 h of helicopter flight). Crabeater seal Lobodon carcinophaga represented more than 97 % of the total. Two types of major aggregations of crabeaters were noted: on the one hand, very large groups hauled out on the pack ice, composed mainly of adults/bachelors and very few calves. On the other hand, swimming pods of calves were accompanied by one or two leading adults around icebergs. Our interpretation is that, after the beginning of the reproduction period with trios (cow, calf and future father) scattered on pack ice, such pods can be considered the last step of the breeding cycle.     

Observations of floating anthropogenic litter in the Barents Sea and Fram Strait,Arctic

Although recent reports indicate that anthropogenic waste has made it to the remotest parts of our oceans, there is still only limited information about its spread, especially in polar seas. Here, we present litter densities recorded during ship- and helicopter-based observer surveys in the Barents Sea and Fram Strait (Arctic). Thirty-one items were recorded in total, 23 from helicopter and eight from research vessel transects. Litter quantities ranged between 0 and 0.216 items km^?1 with a mean of 0.001 (±SEM 0.005) items km^?1. All of the floating objects observed were plastic items. Litter densities were slightly higher in the Fram Strait (0.006 items km^?1) compared with the Barents Sea (0.004 items km^?1). More litter was recorded during helicopter-based surveys than during ship-based surveys (0.006 and 0.004 items km^?1, respectively). When comparing with the few available data with the same unit (items km^?1 transect), the densities found herein are slightly higher than those from Antarctica but substantially lower than those from temperate waters. However, since anthropogenic activities in the Fram Strait are expanding because of sea ice shrinkage, and since currents from the North Atlantic carry a continuous supply of litter to the north, this problem is likely to worsen in years to come unless serious mitigating actions are taken to reduce the amounts of litter entering the oceans.     

Cellular localization of a plant protein PSAM 1 in arbuscular mycorrhizas of Pisum sativum

Psam 1 is a single-copy gene which is activated during early plant-fungal interaction in wild-type pea inoculated with Glomus mosseae and which codes for PSAM 1, a putative protein of 108 amino acids. A synthetic peptide was designed in an antigenic region of this protein to produce a polyclonal antibody against PSAM 1 and to investigate its cellular localization. Western blot analysis revealed that a polypeptide of about 14.5 kDa accumulated more in mycorrhizal than non-mycorrhizal pea roots. The PSAM 1 antigen was immunolocated in planta in arbuscule-containing cells of mycorrhizal roots and especially in the cytoplasm surrounding young arbuscules in cortical cells, which suggests that its accumulation is somehow related to the symbiotic state of these cells. Received: 27 June 1998 / Accepted: 27 July 1998     

Phosphonate utilization by bacteria in the presence of alternative phosphorus sources

Batch and continuous culture experiments were carried out to investigate the effect of orthophosphate and p-nitrophenylphosphate on the utilization of various phosphonates as a P source by bacteria. Detailed tests with methylphosphonate as a model phosphonate and the phosphonate-degrading Pseudomonas paucimobilis strain MMM101a revealed that, in contrast with the majority of literature data, the phosphates did not suppress phosphonate utilization. Under conditions of P stress, strain MMM101a simultaneously took up both P-sources, with a preference for the phosphate-P. Study of the kinetic parameters for strain MMM101a, growing on the different P sources revealed similar, rather low, maximum growth rates (ca. 0.15 h^-1). However, the affinity for orthophosphate (K_s: 0.17 M), was more than two orders of magnitude higher than for methylphosphonate (K_s: 66 M), which might account for the preferential uptake of orthophosphate. Cellular phosphorus yields in continuous cultures varied considerably with the conditions applied. The results suggest that phosphonate degradation can occur also in environments with substantial backgrounds of phosphate.Abbreviations D2010 Dequest 2010, Hydroxyethane diphosphonic acid - D2041 Dequest 2041, Ethylenediamine tetramethylphosphonic acid - Gly Glyphosate - N Phosphonomethyl glycine - HEPES N-2-Hydroxy-Ethylpiperazine-N-2-EthaneSulfonic acid - MeP Methylphosphonate - OD₆₅₀, OD₄₁₃ Optical densities respectively at 650 and 413 nm - Pi Orthophosphate - Pn Phosphonate-phosphorus - pNPP para-Nitrophenylphosphate - pNP paranitrophenol - D dilution rate of chemostat, day^-1     

Weight loss moderately affects the mixed meal challenge response of the plasma metabolome and transcriptome of peripheral blood mononuclear cells in abdominally obese subjects

Introduction

The response to dietary challenges has been proposed as a more accurate measure of metabolic health than static measurements performed in the fasted state. This has prompted many groups to explore the potential of dietary challenge tests for assessment of diet and lifestyle induced shifts in metabolic phenotype.

Objectives

We examined whether the response to a mixed-meal challenge could provide a readout for a weight loss (WL)-induced phenotype shift in abdominally obese male subjects. The underlying assumption of a mixed meal challenge is that it triggers all aspects of phenotypic flexibility and provokes a more prolonged insulin response, possibly allowing for better differentiation between individuals.

Methods

Abdominally obese men (n?=?29, BMI?=?30.3?±?2.4 kg/m²) received a mixed-meal challenge prior to and after an 8-week WL or no-WL control intervention. Lean subjects (n?=?15, BMI?=?23.0?±?2.0 kg/m²) only received the mixed meal challenge at baseline to have a benchmark for WL-induced phenotype shifts.

Results

Levels of several plasma metabolites were significantly different between lean and abdominally obese at baseline as well as during postprandial metabolic responses. Genes related to oxidative phosphorylation in peripheral blood mononuclear cells (PBMCs) were expressed at higher levels in abdominally obese subjects as compared to lean subjects at fasting, which was partially reverted after WL. The impact of WL on the postprandial response was modest, both at the metabolic and gene expression level in PBMCs.

Conclusion

We conclude that mixed-meal challenges are not necessarily superior to measurements in the fasted state to assess metabolic health. Furthermore, the mechanisms accounting for the observed differences between lean and abdominally obese in the fasted state are different from those underlying the dissimilarity observed during the postprandial response.

     

Medicago truncatula ENOD40-1 and ENOD40-2 are both involved in nodule initiation and bacteroid development

The establishment of a nitrogen-fixing root nodule on legumes requires the induction of mitotic activity of cortical cells leading to the formation of the nodule primordium and the infection process by which the bacteria enter this primordium. Several genes are up-regulated during these processes, among them ENOD40. Here it is shown, by using gene-specific knock-down of the two Medicago truncatula ENOD40 genes, that both genes are involved in nodule initiation. Further, during nodule development, both genes are essential for bacteroid development.     

Niche conservatism among non‐native vertebrates in Europe and North America

Niche conservatism, the hypothesis that niches remain constant through time and space, is crucial for the study of biological invasions as it underlies native‐range based predictions of invasion risk. Niche changes between native and non‐native populations are increasingly reported. However, it has been argued that these changes arise mainly because in their novel range, species occupy only a subset of the environments they inhabit in their native range, and not because they expand into environments entirely novel to them. Here, using occurrences of 29 vertebrate species native to either Europe or North America and introduced into the other continent, we assess the prevalence of niche changes between native and non‐native populations and assess whether the changes detected are caused primarily by native niche unfilling in the non‐native range rather than by expansion into novel environments. We show that niche overlap between native and non‐native populations is generally low because of a large degree of niche unfilling in the non‐native range. This most probably reflects an ongoing colonization of the novel range, as niche changes were smaller for species that were introduced longer ago and into a larger number of locations. Niche expansion was rare, and for the few species exhibiting larger amounts of niche overlap, an unfilling of the niche in the native range (e.g. through competition or dispersal limitations) is the most probable explanation. The fact that for most species, the realized non‐native niche is a subset of the realized native niche allows native‐range based niche models to generate accurate predictions of invasion risk. These results suggest that niche changes arising during biological invasions are strongly influenced by propagule pressure and colonization processes, and we argue that introduction history should be taken into account when evaluating niche conservatism in the context of biological invasions.