High-fat diets rich in medium- versus long-chain fatty acids induce distinct patterns of tissue specific insulin resistance

Excess dietary long-chain fatty acid (LCFA) intake results in ectopic lipid accumulation and insulin resistance. Since medium-chain fatty acids (MCFA) are preferentially oxidized over LCFA, we hypothesized that diets rich in MCFA result in a lower ectopic lipid accumulation and insulin resistance compared to diets rich in LCFA. Feeding mice high-fat (HF) (45% kcal fat) diets for 8 weeks rich in triacylglycerols composed of MCFA (HFMCT) or LCFA (HFLCT) revealed a lower body weight gain in the HFMCT-fed mice. Indirect calorimetry revealed higher fat oxidation on HFMCT compared to HFLCT (0.011.0±0.0007 vs. 0.0096±0.0015 kcal/g body weight per hour, P<.05). In line with this, neutral lipid immunohistochemistry revealed significantly lower lipid storage in skeletal muscle (0.05±0.08 vs. 0.30±0.23 area%, P <.05) and in liver (0.9±0.4 vs. 6.4±0.8 area%, P<.05) after HFMCT vs. HFLCT, while ectopic fat storage in low fat (LF) was very low. Hyperinsulinemic euglycemic clamps revealed that the HFMCT and HFLCT resulted in severe whole body insulin resistance (glucose infusion rate: 53.1±6.8, 50.8±15.3 vs. 124.6±25.4 μmol min⁻¹ kg⁻¹, P<.001 in HFMCT, HFLCT and LF-fed mice, respectively). However, under hyperinsulinemic conditions, HFMCT revealed a lower endogenous glucose output (22.6±8.0 vs. 34.7±8.5 μmol min⁻¹ kg⁻¹, P<.05) and a lower peripheral glucose disappearance (75.7±7.8 vs. 93.4±12.4 μmol min⁻¹ kg⁻¹, P<.03) compared to HFLCT-fed mice. In conclusion, both HF diets induced whole body insulin resistance compared to LF. However, the HFMCT gained less weight, had less ectopic lipid accumulation, while peripheral insulin resistance was more pronounced compared to HFLCT. This suggests that HF-diets rich in medium- versus long-chain triacylglycerols induce insulin resistance via distinct mechanisms.     

Chromosomal characterization of two species of genus <Emphasis Type="Italic">Steatogenys</Emphasis> (Gymnotiformes: Rhamphichthyoidea: Steatogenini) from the Amazon basin: sex chromosomes and correlations with Gymnotiformes phylogeny

Gymnotiformes are an important component of the Neotropical ichthyofauna and they are known for their ability to generate and detect electrical discharges. Phylogenetic relationships of Gymnotiformes are still not well understood. However, the monophyly of the superfamily Rhamphichthyoidea is well accepted, despite the position of tribe Steatogenini (Steatogenys, Hypopygus and Stegostenopos) within this superfamily is unclear. The genus Steatogenys includes three species that, together with Hypopygus and Stegostenopos, form tribe Steatogenini. Cytogenetic information is currently only available for Hypopygus lepturus. Here, we describe the karyotypes of Steatogenys elegans from four localities and S. duidae from two localities. S. elegans was found to have 2n = 50, ZZ/ZW (12m-sm/38st-a), while S. duidae had 2n = 50 (50m-sm). In S. elegans, constitutive heterochromatin (CH) was observed in the centromeric regions of all chromosomes, in the interstitial region of 1q, and in two blocks of Wq. In S. duidae, CH was observed in the centromeric and pericentromeric regions of all chromosomes, and in the interstitial regions of 2q, 3q, 5q, and 7q. Nucleolar organizer regions (NORs) were identified in the distal regions of one chromosome pair in each species. The CMA₃ fluorochrome (specific to G-C rich regions) coincided with the NORs in both species, and with the HC of S. elegans except on chromosome pair 5 and the W. The DAPI fluorochrome (specific to A-T rich regions) coincided with the CH of both species, and was very intense for chromosome pair 5 and the W of S. elegans. Our observations suggest that the ZZ/ZW system observed in S. elegans likely evolved through CH addition followed by a paracentric inversion. The chromosomal data described herein are consistent with the phylogenetic hypothesis that tribe Steatogenini should be positioned within family Ramphychthyidae.     

Evaluation of hexose and pentose in pre-cultivation of <Emphasis Type="Italic">Candida guilliermondii</Emphasis> on the key enzymes for xylitol production in sugarcane hemicellulosic hydrolysate

The evaluation of hexose and pentose in pre-cultivation of Candida guilliermondii FTI 20037 yeast on xylose reductase (XR) and xylitol dehydrogenase (XDH) enzymes activities was performed during fermentation in sugarcane bagasse hemicellulosic hydrolysate. The xylitol production was evaluated by using cells previously growth in 30.0 gl^?1 xylose, 30.0 gl^?1 glucose and in both sugars mixture (30.0 gl^?1 xylose and 2.0 gl^?1 glucose). The vacuum evaporated hydrolysate (80 gl^?1) was detoxificated by ion exchange resin (A-860S; A500PS and C-150-Purolite^®). The total phenolic compounds and acetic acid were 93.0 and 64.9%, respectively, removed by the resin hydrolysate treatment. All experiments were carried out in Erlenmeyer flasks at 200 rpm, 30°C. The maximum XR (0.618 Umg _Prot ^?1 ) and XDH (0.783 Umg _Prot ^?1 ) enzymes activities was obtained using inoculum previously growth in both sugars mixture. The highest cell concentration (10.6 gl^?1) was obtained with inoculum pre-cultivated in the glucose. However, the xylitol yield and xylitol volumetric productivity were favored using the xylose as carbon source. In this case, it was observed maximum xylose (81%) and acetic acid (100%) consumption. It is very important to point out that maximum enzymatic activities were obtained when the mixture of sugars was used as carbon source of inoculum, while the highest fermentative parameters were obtained when xylose was used.     

How well does presence‐only‐based species distribution modelling predict assemblage diversity? A case study of the Tenerife flora

Prediction error is considered an important problem in species distribution models. To address this issue, we here examined the accuracy of overlays of presence‐only‐based models for many individual species in representing patterns of assemblage diversity. For this purpose, we used a database of 977 160 records of seed plant occurrences on an intensively surveyed, species‐rich island (Tenerife, Canary Islands) for modelling the distribution of all its 841 native plant species individually. The modelling was done using Maxent, one of the best‐performing presence‐only modelling techniques, using various thresholds to convert the estimated suitability values into predicted presence or absence. Distribution models for each individual species were overlaid to predict species richness and composition, which were then compared to the observed values for well‐surveyed grid cells. We found high levels of compositional error, when the best performing suitability threshold for predicting species richness was applied. Our best prediction had a mean species richness error of 24% and a mean compositional error of 60% relative to the observed values for the well‐surveyed cells; >50% of all species were included erroneously in >25% of the well‐surveyed cells. Hence, large quantities of data are not necessarily enough to obtain reliable predictions of assemblage diversity, limiting the usefulness of this methodology in conservation planning.     

Chiral separation of flurbiprofen enantiomers by preparative and simulated moving bed chromatography

This study presents the chiral resolution of flurbiprofen enantiomers by preparative liquid chromatography using the simulated moving bed (SMB) technology. Flurbiprofen enantiomers are widely used as nonsteroidal anti‐inflammatory drugs, and although demonstrate different therapeutic actions, they are still marketed as a racemic mixture. The results presented here clearly show the importance of the selection of the proper solvent composition for the preparative separation of flurbiprofen enantiomers. Chiral SMB separation is carried out using a laboratory‐scale unit (the FlexSMB‐LSRE®) with six columns, packed with the Chiralpak AD® stationary phase (20 μm). Results presented include the experimental measurement of equilibrium and kinetic data for two very different solvent compositions, a traditional high hydrocarbon content [10%ethanol/90%n‐hexane/0.01% trifluoroacetic acid (TFA)] and a strong polar organic composition (100%ethanol/0.01%TFA). Experimental data, obtained using the two mobile phase compositions, are used to predict and optimize the SMB operation. After selecting 10%ethanol/90%n‐hexane/0.01%TFA as the most appropriate solvent composition, three feed concentrations of racemic flurbiprofen were considered. Using 40 g/l of racemic flurbiprofen feed solution, the purities for both outlet streams were above 99.4%, the productivity was 13.1 g_feed/(L_bed h), and a solvent consumption of 0.41 L_solvent/g_feed was achieved. Chirality, 2011. © 2011 Wiley‐Liss, Inc.     

Variation in Nectar and Pollen Availability,Sucrose Preference,and Daily Response in the Use of Flowers by <Emphasis Type="Italic">Heliconius erato phyllis</Emphasis>

The mechanisms mediating the use of flowers in the butterfly Heliconius erato phyllis (Nymphalidae) are poorly understood. Availability of nectar and pollen, nectar concentration, and abundance of Stachytarpheta cayennensis and Lantana camara (Verbenaceae), two flower species commonly used by H. erato phyllis in the Neotropics, as well as flower use by this butterfly species in the field were examined in southern Brazil. Under insectary conditions, the preference of H. erato phyllis for different sucrose concentrations (0, 10, 20, 40, and 80%) and the ability to associate sucrose concentrations with preferred and non-preferred flower colors were evaluated through choice tests. Lantana camara inflorescences were less abundant, but contained larger amounts of pollen and nectar than S. cayennensis, and H. erato phyllis utilized the flowers of the former species with higher frequency compared to the latter. In the choice tests, butterflies fed more intensely on 20 and 40% sucrose solutions, an interval in which the nectars of L. camara and S. cayennensis are situated, and were able to associate preferred sucrose concentrations with flower color efficiently within the color spectrum of L. camara flowers (i.e., preferred colors), but not within that of S. cayennensis (non-preferred colors). Thus, the greater use of L. camara flowers by H. erato phyllis is related to the plant’s superior floral rewards and not flower abundance, and to the cognitive abilities of these butterflies to adjust their feeding to the availability of pollen and nectar. To our knowledge, this is the first report showing sucrose preferences in a butterfly species.     

Overlapping role of dynamin isoforms in synaptic vesicle endocytosis

The existence of neuron-specific endocytic protein isoforms raises questions about their importance for specialized neuronal functions. Dynamin, a GTPase implicated in the fission reaction of endocytosis, is encoded by three genes, two of which, dynamin 1 and 3, are highly expressed in neurons. We show that dynamin 3, thought to play a predominantly postsynaptic role, has a major presynaptic function. Although lack of dynamin 3 does not produce an overt phenotype in mice, it worsens the dynamin 1 KO phenotype, leading to perinatal lethality and a more severe defect in activity-dependent synaptic vesicle endocytosis. Thus, dynamin 1 and 3, which together account for the overwhelming majority of brain dynamin, cooperate in supporting optimal rates of synaptic vesicle endocytosis. Persistence of synaptic transmission in their absence indicates that if dynamin plays essential functions in neurons, such functions can be achieved by the very low levels of dynamin 2.     

Synthesis of the flavonoid-induced lipopolysaccharide of Rhizobium Sp. strain NGR234 requires rhamnosyl transferases encoded by genes rgpF and wbgA

In the presence of flavonoids, Rhizobium sp. strain NGR234 synthesizes a new lipopolysaccharide (LPS), characterized by a rhamnan O-antigen. The presence of this rhamnose-rich LPS is important for the establishment of competent symbiotic interactions between NGR234 and many species of leguminous plants. Two putative rhamnosyl transferases are encoded in a cluster of genes previously shown to be necessary for the synthesis of the rhamnose-rich LPS. These two genes, wbgA and rgpF, were mutated. The resulting mutant strains synthesized truncated rough LPS species rather than the wild-type rhamnose-rich LPS when grown with flavonoids. Based on the compositions of these purified mutant LPS species, we inferred that RgpF is responsible for adding the first one to three rhamnose residues to the flavonoid-induced LPS, whereas WbgA is necessary for the synthesis of the rest of the rhamnan O-antigen. The NGR234 homologue of lpsB, which, in other bacteria, encodes a glycosyl transferase acting early in synthesis of the core portion of LPS, was identified and also mutated. LpsB was required for all the LPS species produced by NGR234, in the presence or absence of flavonoids. Mutants (i.e., of lpsB and rgpF) that lacked any portion of the rhamnan O-antigen of the induced LPS were severely affected in their symbiotic interaction with Vigna unguiculata, whereas the NGR?wbgA mutant, although having very few rhamnose residues in its LPS, was able to elicit functional nodules.     

Effect of impeller type and stirring frequency on the behavior of an AnSBBR in the treatment of low-strength wastewater

The influence of impeller type and stirring frequency on the performance of a mechanically stirred anaerobic sequencing batch reactor containing immobilized biomass on an inert support (AnSBBR - Anaerobic Sequencing Batch Biofilm Reactor) was evaluated. The biomass was immobilized on polyurethane foam cubes placed in a stainless-steel basket inside a glass cylinder. Each 8-h batch run consisted of three stages: feed (10 min), reaction (460 min) and discharge (10 min) at 30 °C. Experiments were performed with four impeller types, i.e., helical, flat-blade, inclined-blade and curved-blade turbines, at stirring frequencies ranging from 100 to 1100 rpm. Synthetic wastewater was used in all experiments with an organic-matter concentration of 530 ± 37 mg/L measured as chemical oxygen demand (COD). The reactor achieved an organic-matter removal efficiency of around 87% under all investigated conditions. Analysis of the four impeller types and the investigated stirring frequencies showed that mass transfer in the liquid phase was affected not only by the applied stirring frequency but also by the agitation mode imposed by each impeller type. The best reactor performance at all stirring frequencies was obtained when agitation was provided by the flat-blade turbine impeller.     

Genetic Structure of the Population of Alternaria solani in Brazil

Understanding the genetic structure of the population of Alternaria solani (AS) is an important component of epidemiological studies of early blight, a severe disease that affects potato (Po) and tomato (To) worldwide. Up to 150 isolates obtained from both hosts were analysed with RAPD and AFLP markers to estimate the amount and distribution of genetic variability of AS in Brazil. Using RAPD, gene diversity (h = 0.20) and scaled indices of diversity of Shannon (H′ = 0.66) and Stoddart and Taylor’s (G = 0.31) for the Po population were higher than those of the To (h = 0.07, H′ = 0.34, G = 0.17). For AFLP, the statistics for the Po (h = 0.17, H′ = 0.86, G = 0.49) and To (h = 0.17, H′ = 0.85, G = 0.36) populations were similar. For each RAPD and AFLP locus, the allele frequency for the overall population ranged from 0.006 to 0.988, and 0.007 to 0.993, respectively. Genetic differentiation was high (G_ST = 0.41 and θ = 0.59) and moderately high (G_ST = 0.23 and θ = 0.37) when estimated with RAPD and AFLP, respectively. Based on cluster analyses, there was strong evidence of association of pathogen haplotypes with host species. The null hypothesis of random association of alleles was rejected in the analysis of both RAPD (I_A = 13.1, P < 0.001) and AFLP (I_A = 2.2, P < 0.001) markers. The average number of migrants was estimated to be around one and two individuals per generation, using RAPD and AFLP, respectively. There was no correlation between genetic distance and geographical origin of AS haplotypes for RAPD (r = ?0.07, P = 0.84) and AFLP (r = ?0.03, P = 0.70). The AS population is clonal with high genetic variability, and there is genetic differentiation between the populations that affect To and Po.