Benzyl propionate synthesis by fed-batch esterification using commercial immobilized and lyophilized Cal B lipase

Bioprocess and Biosystems Engineering - In this work, a fed-batch approach was adopted to overcome propionic acid lipase inactivation effects in the benzyl propionate direct esterification mediated...     

An evaluation of sequencing coverage and genotyping strategies to assess neutral and adaptive diversity

Whole genome sequences (WGS) greatly increase our ability to precisely infer population genetic parameters, demographic processes, and selection signatures. However, WGS may still be not affordable for a representative number of individuals/populations. In this context, our goal was to assess the efficiency of several SNP genotyping strategies by testing their ability to accurately estimate parameters describing neutral diversity and to detect signatures of selection. We analysed 110 WGS at 12× coverage for four different species, i.e., sheep, goats and their wild counterparts. From these data we generated 946 data sets corresponding to random panels of 1K to 5M variants, commercial SNP chips and exome capture, for sample sizes of five to 48 individuals. We also extracted low‐coverage genome resequencing of 1×, 2× and 5× by randomly subsampling reads from the 12× resequencing data. Globally, 5K to 10K random variants were enough for an accurate estimation of genome diversity. Conversely, commercial panels and exome capture displayed strong ascertainment biases. Besides the characterization of neutral diversity, the detection of the signature of selection and the accurate estimation of linkage disequilibrium (LD) required high‐density panels of at least 1M variants. Finally, genotype likelihoods increased the quality of variant calling from low coverage resequencing but proportions of incorrect genotypes remained substantial, especially for heterozygote sites. Whole genome resequencing coverage of at least 5× appeared to be necessary for accurate assessment of genomic variations. These results have implications for studies seeking to deploy low‐density SNP collections or genome scans across genetically diverse populations/species showing similar genetic characteristics and patterns of LD decay for a wide variety of purposes.     

Age,growth, and reproductive biology of the Atlantic spadefish Chaetodipterus faber in southern Brazil

Ichthyological Research - This is the first study to investigate the age, growth and reproductive biology of the Atlantic spadefish Chaetodipterus faber in southern Brazil. A total of 625...     

Understanding and predicting frost‐induced tropical tree mortality patterns

Extreme climatic and weather events are increasing in frequency and intensity across the world causing episodes of widespread tree mortality in many forested ecosystems. However, we have a limited understanding about which local factors influence tree mortality patterns, restricting our ability to predict tree mortality, especially within topographically complex tropical landscapes with a matrix of mature and secondary forests. We investigated the effects of two major local factors, topography and forest successional type, on climate‐induced tropical tree mortality patterns using an observational and modeling approach. The northernmost Neotropical dry forest endured an unprecedented episode of frost‐induced tree mortality after the historic February 2011 cold wave hit northwestern Mexico. In a moderately hilly landscape covering mature and secondary tropical dry forests, we surveyed 454 sites for the presence or absence of frost‐induced tree mortality. In addition, across forty‐eight 1 ha plots equally split into the two forest types, we examined 6,981 woody plants to estimate a frost‐disturbance severity metric using the density of frost‐killed trees. Elevation is the main factor modulating frost effects regardless of forest type. Higher occurrence probabilities of frost‐induced tree mortality at lowland forests can be explained by the strong influence of elevation on temperature distribution since heavier cold air masses move downhill during advective frosts. Holding elevation constant, the probability of frost‐induced tree mortality in mature forests was twice that of secondary forests but severity showed the opposite pattern, suggesting a cautious use of occurrence probabilities of tree mortality to infer severity of climate‐driven disturbances. Extreme frost events, in addition to altering forest successional pathways and ecosystem services, likely maintain and could ultimately shift latitudinal and altitudinal range margins of Neotropical dry forests.     

Impact of grazing,resource availability and light on prokaryotic growth and diversity in the oligotrophic surface global ocean

The impact of grazing, resource competition and light on prokaryotic growth and taxonomic composition in subtropical and tropical surface waters were studied through 10 microcosm experiments conducted between 30°N and 30°S in the Atlantic, Pacific and Indian oceans. Under natural sunlight conditions, significant changes in taxonomic composition were only observed after the reduction of grazing by sample filtration in combination with a decrease in resource competition by sample dilution. Sunlight exposure significantly reduced prokaryote growth (11 ± 6%) and community richness (14 ± 4%) compared to continuous darkness but did not significantly change community composition. The largest growth inhibition after sunlight exposure occurred at locations showing deep mixed layers. The reduction of grazing had an expected and significant positive effect on growth, but caused a significant decrease in community richness (16 ± 6%), suggesting that the coexistence of many different OTUs is partly promoted by the presence of predators. Dilution of the grazer-free prokaryotic community significantly enhanced growth at the level of community, but consistently and sharply reduced the abundance of Prochlorococcus and SAR11 populations. The decline of these oligotrophic bacterial taxa following an increase in resource availability is consistent with their high specialization for exploiting the limited resources available in the oligotrophic warm ocean.     

Proximodistal Organization of the CA2 Hippocampal Area

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Refinement of the AMBER force field for nucleic acids: improving the description of alpha/gamma conformers

We present here the parmbsc0 force field, a refinement of the AMBER parm99 force field, where emphasis has been made on the correct representation of the alpha/gamma concerted rotation in nucleic acids (NAs). The modified force field corrects overpopulations of the alpha/gamma = (g+,t) backbone that were seen in long (more than 10 ns) simulations with previous AMBER parameter sets (parm94-99). The force field has been derived by fitting to high-level quantum mechanical data and verified by comparison with very high-level quantum mechanical calculations and by a very extensive comparison between simulations and experimental data. The set of validation simulations includes two of the longest trajectories published to date for the DNA duplex (200 ns each) and the largest variety of NA structures studied to date (15 different NA families and 97 individual structures). The total simulation time used to validate the force field includes near 1 mus of state-of-the-art molecular dynamics simulations in aqueous solution.     

Long-term feeding a high-fat diet causes histological and parasitological effects on murine schistosomiasis mansoni outcome

This study investigated whether long-term feeding a high-fat diet (HFC) has an effect on schistosomiasis mansoni outcome compared to standard chow diet (SC). Swiss Webster female mice (3 wk old) fed each diet over 5 months, and then were infected with 50 Schistosoma mansoni cercariae. Their nutritional status was assessed by monitoring growth rates twice a week and measuring serum levels of lipoproteins. Mice were euthanised 63 days after infection. Parasitological and liver histological analyses were performed. The levels of TC, HDL-C and LDL-C, fecal and tissue schistosome eggs were statistically different (p<0.05) between groups. Livers from HFC mice showed exudative, exudative/exudative-productive, exudative-productive and productive granulomas, some degree of hepatic steatosis and focal necrosis. Mice fed normal-chow did not present productive granulomas and hepatic steatosis. The morphometric evaluation of hepatic granulomas did not reach statistical significance (p>0.05) between diets assayed. The high-fat diet for long-term produces effects on schistosomiasis mansoni outcome.     

Anastrozole quantification in human plasma by high-performance liquid chromatography coupled to photospray tandem mass spectrometry applied to pharmacokinetic studies

A rapid, sensitive and specific method for quantifying the aromatase inhibitor (anastrozole) in human plasma using dexchlorpheniramine as the internal standard (I.S.) is described herein. The analyte and the I.S. were extracted from 200 microl of human plasma by liquid-liquid extraction using a mixture of diethyl ether:dichloromethane (70:30, v/v) solution. Extracts were removed and dried in the organic phase then reconstituted with 200 microl of acetonitrile:water (50:50; v/v). The extracts were analyzed by high performance liquid chromatography coupled with photospray tandem mass spectrometry (HPLC-MS-MS). Chromatography was performed isocratically on a Genesis, C18 4 microm analytical column (100 mm x 2.1mm i.d.). The method had a chromatographic run time of 2.5 min and a linear calibration curve ranging from 0.05-10 ng ml(-1). The limit of quantification (LOQ) was 0.05 ng ml(-1). This HPLC-MS-MS procedure was used to assess pharmacokinetic studies.     

In vitro interaction between ceftazidime and vancomycin/teicoplanin in the presence of azithromycin againstPseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen, intrinsically resistant to many antibiotics and prone to acquire resistance against many drugs. It is assumed that agents that disorganise the structure of the outer membrane might allow the passage of other drugs into cell. To verify this hypothesis, ceftazidime (CAZ) has been tested in association with glycopeptides (GLYs) and azithromycin (AZI). Time-kill experiments were performed on a representative strain. CAZ in combination with GLYs showed 99, 90 and 10% of CFU/ml reduction in 33.9,52.5 and 13.6% of the cases, respectively; the addition of AZI increased the incidence of 99% CFU/ml reduction to 42% of the cases. Indifference was the most common finding, and additive/synergism in the other cases. Present findings demonstrated that CAZ favourably reacted with GLYs in the presence of AZI.