Immunocytochemical localization and lectin-binding properties of the 22 kDa secretory protein from rat ventral prostate

The distribution of the 22 kDa secretory protein from rat ventral prostate was studied by light and electron microscopic immunocytochemistry. An anti-22 kDa protein antiserum was raised in rabbits and its specificity was tested by Western blotting. With the immunofluorescence technique, the 22 kDa protein was detected in the luminal secretions and intracellular apical granules of the ventral prostate. No reaction was observed in the seminal vesicle or dorsolateral prostate. After castration, no intracellular immunoreactivity was detected in ventral prostate, although positively labeled secretory material was retained within the acinar lumen. Restoration of normal intracellular staining pattern was incomplete after 5 daily testosterone injections. At the ultrastructural level, labeling was confined to apical secretory granules and condensing vacuoles. The 22 kDa protein separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to nitrocellulose was shown to bind intensely to wheat germ agglutinin (WGA) but only faintly to Concanavalin A. This protein was thus demonstrated to contain N-acetylglucosamine residues. Accordingly, on tissue sections, WGA reacted intensely with condensing vacuoles and secretory granules.     

Subinhibitory Antibiotic Concentrations Mediate Nutrient Use and Competition among Soil Streptomyces

Though traditionally perceived as weapons, antibiotics are also hypothesized to act as microbial signals in natural habitats. However, while subinhibitory concentrations of antibiotics (SICA) are known to shift bacterial gene expression, specific hypotheses as to how SICA influence the ecology of natural populations are scarce. We explored whether antibiotic ‘signals’, or SICA, have the potential to alter nutrient utilization, niche overlap, and competitive species interactions among Streptomyces populations in soil. For nine diverse Streptomyces isolates, we evaluated nutrient utilization patterns on 95 different nutrient sources in the presence and absence of subinhibitory concentrations of five antibiotics. There were significant changes in nutrient use among Streptomyces isolates, including both increases and decreases in the capacity to use individual nutrients in the presence vs. in the absence of SICA. Isolates varied in their responses to SICA and antibiotics varied in their effects on isolates. Furthermore, for some isolate-isolate-antibiotic combinations, competition-free growth (growth for an isolate on all nutrients that were not utilized by a competing isolate), was increased in the presence of SICA, reducing the potential fitness cost of nutrient competition among those competitors. This suggests that antibiotics may provide a mechanism for bacteria to actively minimize niche overlap among competitors in soil. Thus, in contrast to antagonistic coevolutionary dynamics, antibiotics as signals may mediate coevolutionary displacement among coexisting Streptomyces, thereby hindering the emergence of antibiotic resistant phenotypes. These results contribute to our broad understanding of the ecology and evolutionary biology of antibiotics and microbial signals in nature.     

An X-ray diffraction and differential scanning calorimetric study on the effect of sucrose on the properties of phosphatidylcholine bilayers

The influence of sucrose, between 0 and 70% in the aqueous phase, upon multilamellar liposomes of dimyristoylphosphatidylcholine was examined by differential scanning calorimetry and X-ray diffraction analysis. Increasing concentrations of sucrose increase the temperatures of both the main transition and the pretransition of the lipid. The effect is greater on the pretransition than on the main transition. At 35 degrees C the interlamellar spacing in the multilamellar liposomes is reduced by increasing sucrose concentration in the aqueous phase and no significant effects are seen in the chain lattice of the bilayers. This result is interpreted as a dehydrating effect of sucrose upon the bilayer-water system at 35 degrees C. At 5 degrees C the interlamellar spacing is increased and this increase is, at high (70%) sucrose concentrations, attributable to an untilting of the lipid acyl chains with no change in the thickness of the aqueous layers in the multilamellae.     

Two new species of Drosophila (Diptera,Drosophilidae) associated with inflorescences of Goeppertia monophylla (Marantaceae) in the city of São Paulo,state of São Paulo,Brazil

Two new Brazilian species of Drosophila (subgenus Drosophila) are described and illustrated: Drosophila asymmetrica sp. nov. and Drosophila peixotoi sp. nov. Both species were collected, and emerged, from inflorescences of Goeppertia monophylla (Marantaceae) in the urban Forest Reserve of the Instituto de Biociências da Universidade de São Paulo and their types will be deposited in the Museu de Zoologia da USP. The former species, which could not be assigned to any known group, has a conspicuously asymmetric aedeagus and a narrow oviscapt valve. The latter species belongs to the guarani group and is closely related to D. guaru, D. ornatifrons and D. subbadia, from which it can be distinguished by the presence of just one conspicuous large black spine at inner lower tip of cercus instead of two spines.     

Comparative population biology and reproduction of two sympatric crabs (Grapsidae) on Azores cobble beaches

Population biology of the intertidal crabs Pachygrapsus marmoratus Fabricius, 1787 and P. maurus (Lucas 1846) was investigated at cobble beaches with different levels of wave exposure. Surveys were taken monthly over 1.5 years at three intertidal levels. The growth rate of both species was similar, although P. marmoratus reached larger sizes. This species was more abundant on the mid-littoral zone of sheltered beaches, whereas P. maurus was more abundant on more exposed ones. The sex ratio was male biased in both species, particularly for the smaller and larger size classes. Both species showed an extended reproductive season, coinciding with the rising temperatures of spring and summer, with ovigerous females being found from June to September for P. marmoratus and from May to August for P. maurus. The present study indicates that both could develop adaptive strategies allowing them to coexist in the Azores littoral. The greater size of P. marmoratus seems to be an advantage on the competition for refuges with P. maurus, which results in its higher abundance and general dominance in the higher shore levels and in less exposed shores. However, P. maurus seems to be more fitted to live in the higher hydrodynamic habitats.     

The Spatial Distribution of Alkaloids in Psychotria prunifolia (Kunth) Steyerm and Palicourea coriacea (Cham.) K. Schum Leaves Analysed by Desorption Electrospray Ionisation Mass Spectrometry Imaging

Introduction

Species of the genera Psychotria and Palicourea are sources of indole alkaloids, however, the distribution of alkaloids within the plants is not known. Analysing the spatial distribution using desorption electrospray ionisation mass spectrometry imaging (DESI‐MSI) has become attractive due to its simplicity and high selectivity compared to traditional histochemical techniques.

Objectives

To apply DESI‐MSI to visualise the alkaloid distribution on the leaf surface of Psychotria prunifolia and Palicourea coriacea and to compare the distributions with HPLC–MS and histochemical analyses.

Methodology

Based upon previous structure elucidation studies, four alkaloids targeted in this study were identified using high resolution mass spectrometry by direct infusion of plant extracts, and their distributions were imaged by DESI‐MSI via tissue imprints on a porous Teflon surface. Relative quantitation of the four alkaloids was obtained by HPLC–MS/MS analysis performed using multiple‐reaction monitoring (MRM) mode on a triple quadrupole mass spectrometer.

Results

Alkaloids showed distinct distributions on the leaf surfaces. Prunifoleine was mainly present in the midrib, while 10‐hydroxyisodeppeaninol was concentrated close to the petiole; a uniform distribution of 10‐hydroxyantirhine was observed in the whole leaf of Psychotria prunifolia. The imprinted image from the Palicourea coriacea leaf also showed a homogeneous distribution of calycanthine throughout the leaf surface.

Conclusion

Different distributions were found for three alkaloids in Psychotria prunifolia, and the distributions found by MSI were in complete accordance with HPLC–MS analysis and histochemical results. The DESI‐MSI technique was therefore demonstrated to provide reliable information about the spatial distribution of metabolites in plants. Copyright © 2017 John Wiley & Sons, Ltd.     

Amelioration of PXR-mediated CYP3A4 induction by mGluR2 modulators

This work describes the rational amelioration of Cytochrome P450 4/5 (CYP3A4/5) induction through the Pregnane-X Receptor (PXR) pathway in a series of compounds that modulate the metabotropic glutamate Receptor 2 (mGluR2) via an allosteric mechanism. The compounds were initially shown to induce CYP3A4/5 via the gold-standard induction assay measured in primary human hepatocytes. This was followed up by testing the compounds in a PXR assay which correlated well with the assay in primary cells. Further, one of the compounds was crystallized with PXR (pdb code 6DUP). Analysis of this co-crystal structure, together with previously published PXR co-crystal structures, lead to modification ideas. The compounds synthesized based on these ideas were shown not to be CYP3A4/5 inducers. The mGluR2 activity of the resulting compounds was maintained.     

Fast phylogenetic inference from typing data

Background

Microbial typing methods are commonly used to study the relatedness of bacterial strains. Sequence-based typing methods are a gold standard for epidemiological surveillance due to the inherent portability of sequence and allelic profile data, fast analysis times and their capacity to create common nomenclatures for strains or clones. This led to development of several novel methods and several databases being made available for many microbial species. With the mainstream use of High Throughput Sequencing, the amount of data being accumulated in these databases is huge, storing thousands of different profiles. On the other hand, computing genetic evolutionary distances among a set of typing profiles or taxa dominates the running time of many phylogenetic inference methods. It is important also to note that most of genetic evolution distance definitions rely, even if indirectly, on computing the pairwise Hamming distance among sequences or profiles.

Results

We propose here an average-case linear-time algorithm to compute pairwise Hamming distances among a set of taxa under a given Hamming distance threshold. This article includes both a theoretical analysis and extensive experimental results concerning the proposed algorithm. We further show how this algorithm can be successfully integrated into a well known phylogenetic inference method, and how it can be used to speedup querying local phylogenetic patterns over large typing databases.

     

Growth at elevated CO2 leads to down-regulation of photosynthesis and altered response to high temperature in Quercus suber L. seedlings

The effects of growth at elevated CO₂ on the response to hightemperatures in terms of carbon assimilation (net photosynthesis,stomatal conductance, amount and activity of Rubisco, and concentrationsof total soluble sugars and starch) and of photochemistry (forexample, the efficiency of excitation energy captured by openphotosystem II reaction centres) were studied in cork oak (Quercussuber L.). Plants grown in elevated CO₂ (700 ppm) showed a down-regulationof photosynthesis and had lower amounts and activity of Rubiscothan plants grown at ambient CO₂ (350 ppm), after 14 monthsin the greenhouse. At that time plants were subjected to a heat-shocktreatment (4 h at 45C in a chamber with 80% relative humidityand 800–1000 mol m^–2 s^–1 photon flux density).Growth in a CO₂-enriched atmosphere seems to protect cork oakleaves from the short-term effects of high temperature. ElevatedCO₂ plants had positive net carbon uptake rates during the heatshock treatment whereas plants grown at ambient CO₂ showed negativerates. Moreover, recovery was faster in high CO₂-grown plantswhich, after 30 min at 25C, exhibited higher net carbon uptakerates and lower decreases in photosynthetic capacity (A_max aswell as in the efficiency of excitation energy captured by openphotosystem II reaction centres (F_vJF_m than plants grown atambient CO₂. The stomata of elevated CO₂ plants were also lessresponsive when exposed to high temperature. Key words: Elevated CO₂, temperature, acclimation, photosynthesis, Quercus suber L.