Potential predation of the exotic Amblyseius swirskii on Euseius concordis (Acari: Phytoseiidae), a predatory mite commonly found in Brazil

Intra/interspecific predation by A. swirskii.

Both Benin and Netherlands populations of Amblyseius swirskii engaged in cannibalism, and in predation on Euseius concordis larvae. Provision of pollen decreased cannibalism considerably, but had a smaller effect on predation on E. concordis. Potential effect of the eventual introduction of A. swirskii for control of Bemisia tabaci in Brazil is discussed.     

Regulation of the photosynthetic electron transport and specific photoprotective mechanisms in <Emphasis Type="Italic">Ricinus communis</Emphasis> under drought and recovery

Ricinus communis is one of the major commercial non-edible oilseed crops grown in semiarid and arid environments worldwide and is reported as a drought tolerant species. Surprisingly, little is known about the mechanisms achieving this tolerance, especially in relation to photoprotection. The aim of this study was to analyze the association of the regulation of the photosynthetic electron transport and photoprotective mechanisms with drought tolerance in R. communis. Drought induced decreases in the relative water content, water potential and growth in R. communis exposed to 9 days of drought. After 6 days of rehydration, these parameters were completely recovered, demonstrating a potential of drought tolerance in this species. In addition, drought inhibited photosynthesis by stomatal and metabolic limitations (V _cmax, J _max, and Rubisco activity), with partial recovery after rehydration. Leaves displayed transient photoinhibition after 6 days of drought, which was completely recovered after 6 days of dehydration. The effective quantum yields and the electron transport rates of PSII and PSI were modulated to face drought avoiding the excess energy produced by decreases in CO₂ assimilation. NPQ was increased during drought, and it was maintained higher than control after the recovery treatment. In addition, the estimated cyclic electron flow was induced under drought and decreased after recovery. Photorespiration was also increased under drought and maintained at higher levels after the recovery treatment. Furthermore, antioxidative enzymes activities (SOD, APX, and CAT) were increased under drought to avoid ROS harmful effects. Altogether, we clearly showed that the modulation of photoprotective mechanisms and antioxidant enzymes are crucial to this species under drought. The implication of these strikingly strategies to drought tolerance is discussed in relation to agricultural and natural systems.     

Potential use of membrane bioreactor to treat petroleum refinery effluent: comprehension of dynamic of organic matter removal,fouling characteristics and membrane lifetime

Bioprocess and Biosystems Engineering - This study aims to evaluate membrane bioreactor (MBR) performance in a pilot scale to treat petroleum refinery effluent, and has been primarily focused on...     

Acute modulation of myocardial function by angiotensin 1–7

Angiotensin 1–7 is a bioactive heptapeptide of the renin–angiotensin system. Its cardiovascular actions have recently acquired growing relevance, mainly due to its counter-regulatory actions in the angiotensin cascade. The aim of the present study was to evaluate the actions of angiotensin 1–7 on myocardial function. Increasing concentrations of angiotensin 1–7 (10⁻⁹ to 10⁻⁵ M) were added to rabbit right papillary muscles: (1) in baseline conditions with intact endocardial endothelium (EE); (2) after selective removal of the EE with Triton X-100 (1 s, 0.01%); (3) with intact EE in the presence of the Mas receptor antagonist A-779, the AT₁ receptor antagonist ZD-7155, the AT₂ receptor antagonist PD-123,319 or the nitric oxide synthesis inhibitor NG-nitro-l-arginine (l-NA). Concerning the effects on contractility, we observed a significant decrease on active tension, dT/dt_max, peak shortening and dL/dt_max of −10.5 ± 3.6%, −8.0 ± 3.0%, −5.3 ± 2.6% and −5.7 ± 2.3%, respectively. There was no change on relaxation parameters, namely dT/dt_min or dL/dt_min. Time to half relaxation was significantly decreased. The presence of ZD-7155 or PD-123,319 did not change these effects. However, angiotensin 1–7 effects on myocardial properties were abolished after selective EE removal and in the presence of A-779 or l-NA. In conclusion, in this animal species, angiotensin 1–7 through its binding to Mas receptor induces a negative inotropic effect modulated by the EE and nitric oxide and independent of AT₁ or AT₂ receptors activation. As the effects described in the present work were influenced by the endocardial endothelium, they may be disrupted in situations associated to endothelial dysfunction, as in heart failure or myocardial ischemia.     

MADAMM: a multistaged docking with an automated molecular modeling protocol

Dealing with receptor flexibility in docking methodology is still a problem. The main reason behind this difficulty is the large number of degrees of freedom that have to be considered in this kind of calculations. In this paper, we present an automated procedure, called MADAMM, that allows flexibilization of both the receptor and the ligand during a multistaged docking with an automated molecular modeling protocol. We show that the orientation of particular residues at the interface between the protein and the ligand have a crucial influence on the way they interact during the docking process, and the standard docking methodologies failed to predict their correct mode of binding. We present some examples that demonstrate the capabilities of this approach when compared with traditional docking methodologies.     

Extinction of anciently associated gut bacterial symbionts in a clade of stingless bees

Animal-microbe symbioses are often stable for millions of years. An example is the clade consisting of social corbiculate bees—honeybees, bumblebees, and stingless bees—in which a shared ancestor acquired specialized gut bacteria that subsequently diversified with hosts. This model may be incomplete, however, as few microbiomes have been characterized for stingless bees, which are diverse and ecologically dominant pollinators in the tropics. We surveyed gut microbiomes of Brazilian stingless bees, focusing on the genus Melipona, for which we sampled multiple species and biomes. Strikingly, Melipona lacks Snodgrassella and Gilliamella, bacterial symbionts ubiquitous in other social corbiculate bees. Instead, Melipona species harbor more environmental bacteria and bee-specific Starmerella yeasts. Loss of Snodgrassella and Gilliamella may stem from ecological shifts in Melipona or the acquisition of new symbionts as functional replacements. Our findings demonstrate the value of broadly sampling microbiome biodiversity and show that even ancient symbioses can be lost.Subject terms: Symbiosis, Microbiome, Microbial ecology, Metagenomics, Microbial ecology     

Application of flow cytometry for the identification of <Emphasis Type="Italic">Staphylococcus epidermidis</Emphasis> by peptide nucleic acid fluorescence in situ hybridization (PNA FISH) in blood samples

Staphylococcus epidermidis is considered to be one of the most common causes of nosocomial bloodstream infections, particularly in immune-compromised individuals. Here, we report the development and application of a novel peptide nucleic acid probe for the specific detection of S. epidermidis by fluorescence in situ hybridization. The theoretical estimates of probe matching specificity and sensitivity were 89 and 87%, respectively. More importantly, the probe was shown not to hybridize with closely related species such as Staphylococcus aureus. The method was subsequently successfully adapted for the detection of S. epidermidis in mixed-species blood cultures both by microscopy and flow cytometry.     

Enantioselective determination of metoprolol acidic metabolite in plasma and urine using liquid chromatography chiral columns: applications to pharmacokinetics

Enantioselective separations on chiral stationary phases with or without derivatization were developed and compared for the HPLC analysis of (+)-(R)- and (-)-(S)-metoprolol acidic metabolite in human plasma and urine. The enantiomers were analysed in plasma and urine without derivatization on a Chiralcel OD-R column, and in urine after derivatization using methanol in acidic medium on a Chiralcel OD-H column. The quantitation limits were 17 ng of each enantiomer/ml plasma and 0.5 microgram of each enantiomer/ml urine using both methods. The confident limits show that the methods are compatible with pharmacokinetic investigations of the enantioselective metabolism of metoprolol. The methods were employed in a metabolism study of racemic metoprolol administered to a patient phenotyped as an extensive metabolizer of debrisoquine. The enantiomeric ratio (+)-(R)/(-)-(S)-acid metabolite was 1.1 for plasma and 1.2 for urine. Clearances were 0.41 and 0.25 l/h/kg, respectively, for the (+)-(R)- and (-)-(S)-enantiomers. The correlation coefficients between the urine concentrations of the acid metabolite enantiomers obtained by the two methods were >0.99. The two methods demonstrated interchangeable application to pharmacokinetics.     

Molecular mechanisms underlying the physiological responses of the cold-water coral Desmophyllum dianthus to ocean acidification

Cold-water corals (CWCs) are thought to be particularly vulnerable to ocean acidification (OA) due to increased atmospheric pCO₂, because they inhabit deep and cold waters where the aragonite saturation state is naturally low. Several recent studies have evaluated the impact of OA on organism-level physiological processes such as calcification and respiration. However, no studies to date have looked at the impact at the molecular level of gene expression. Here, we report results of a long-term, 8-month experiment to compare the physiological responses of the CWC Desmophyllum dianthus to OA at both the organismal and gene expression levels under two pCO₂/pH treatments: ambient pCO₂ (460 μatm, pH_T = 8.01) and elevated pCO₂ (997 μatm, pH_T = 7.70). At the organismal level, no significant differences were detected in the calcification and respiration rates of D. dianthus. Conversely, significant differences were recorded in gene expression profiles, which showed an up-regulation of genes involved in cellular stress (HSP70) and immune defence (mannose-binding c-type lectin). Expression of alpha-carbonic anhydrase, a key enzyme involved in the synthesis of coral skeleton, was also significantly up-regulated in corals under elevated pCO₂, indicating that D. dianthus was under physiological reconditioning to calcify under these conditions. Thus, gene expression profiles revealed physiological impacts that were not evident at the organismal level. Consequently, understanding the molecular mechanisms behind the physiological processes involved in a coral’s response to elevated pCO₂ is critical to assess the ability of CWCs to acclimate or adapt to future OA conditions.     

Mathematical and computational modeling in biology at multiple scales

A variety of topics are reviewed in the area of mathematical and computational modeling in biology, covering the range of scales from populations of organisms to electrons in atoms. The use of maximum entropy as an inference tool in the fields of biology and drug discovery is discussed. Mathematical and computational methods and models in the areas of epidemiology, cell physiology and cancer are surveyed. The technique of molecular dynamics is covered, with special attention to force fields for protein simulations and methods for the calculation of solvation free energies. The utility of quantum mechanical methods in biophysical and biochemical modeling is explored. The field of computational enzymology is examined.