Kinetics of production and characterization of the fucose-containing exopolysaccharide from Enterobacter A47

A fucose-containing exopolysaccharide (EPS) was produced by the bacterium Enterobacter A47 using glycerol byproduct from the biodiesel industry. The analysis of kinetic data suggested a partially growth associated EPS synthesis model. Although the EPS was composed of fucose, galactose and glucose at all cultivation stages, their relative proportion has varied considerably during the run. At the beginning (24 h), glucose was the main component (82.4 wt.%), being fucose and galactose minor components (5.0 wt.% and 10.9 wt.%, respectively), while at the end (96 h) it was composed of 26.0 wt.% fucose, 28.9 wt.% galactose and 43.7 wt.% glucose. The acyl groups content and composition have also changed, reaching their maximum content (19.2 wt.%) at the end of the run. Moreover, the molecular weight has increased linearly during the run (from 8 × 10⁵ to 5 × 10⁶). The changes observed in EPS composition and molecular weight have also had an impact upon the polymer's intrinsic viscosity, as shown by its linear increase from 3.95 to 10.72 dL g⁻¹. The results suggest that the culture might have synthesized at least two distinct EPS, with different sugar composition and average molecular weight, which predominated at different cultivation stages.     

Anthecology and reproductive system of Mourera fluviatilis (Podostemaceae): Pollination by bees and xenogamy in a predominantly anemophilous and autogamous family?

The Podostemaceae are sessile hydrophytes restricted to habitats with waterfalls and seasonal flow variability. Mourera fluviatilis belongs to the family and has a disjunct distribution in the Amazon and northeastern Brazil. The following hypotheses were tested: (i) both autogamy and anemophily act on the pollination system of M. fluviatilis, and (ii) the highest reproductive success is achieved by cross-pollination. Natural populations were monitored in the rivers Pirangi and Ipojuca, northeastern Brazil. Floral visitors are the polylectic bees Apis mellifera, Trigona spinipes (Apidae), Augochlora sp. and Augochloropsis sp. (Halictidae), though only the latter three are effective pollinators. In experiments on the reproductive system and pollination there was a high percentage of fruit formation (>86%), both in treatment and control plants. Although the index of self-incompatibility is 0.86, there was a significant difference in the number of seeds produced among reproductive system treatments, and xenogamy produced more seeds. There was no significant difference in the number of penetrated ovules between control and manual cross-pollination (xenogamy) treatments, 24 h after pollination. However, there were differences among treatments, 48 h after pollination, except for the control and xenogamy treatments. The pollen tubes from cross-pollination treatments usually penetrate the micropyle in shorter time and in higher quantity. We found differences among pollination experiments, except for the control and non-emasculated treatments, and between emasculated treatments. In spite of the ambiguity of floral attributes (pedicel, filaments and anthers colors, sweet odor, reduced perianth, absence of nectar, small and dry pollen grains), wind pollination is less important for this species; what predominates instead are first allogamy mediated by bees and second self-pollination at the end of anthesis.     

Effects of nicotine administration in a mouse model of familial hypertrophic cardiomyopathy, α-tropomyosin D175N

The effects of nicotine (NIC) on normal hearts are fairly well established, yet its effects on hearts displaying familial hypertrophic cardiomyopathy have not been tested. We studied both the acute and chronic effects of NIC on a transgenic (TG) mouse model of FHC caused by a mutation in α-tropomyosin (Tm; i.e., α-Tm D175N TG, or Tm175). For acute effects, intravenously injected NIC increased heart rate, left ventricular (LV) pressure, and the maximal rate of LV pressure increase (+dP/dt) in non-TG (NTG) and Tm175 mice; however, Tm175 showed a significantly smaller increase in the maximal rate of LV pressure decrease (-dP/dt) compared with NTGs. Western blots revealed phosphorylation of phospholamban Ser16 and Thr17 residue increased in NTG mice following NIC injection but not in Tm175 mice. In contrast, phosphorylation of troponin I at serine residues 23 and 24 increased equally in both NTG and Tm175. Thus the attenuated increase in relaxation in Tm175 mice following acute NIC appears to result primarily from attenuated phospholamban phosphorylation. Chronic NIC administration (equivalent to smoking 2 packs of cigarettes/day for 4 mo) also increased +dP/dt in NTG and Tm175 mice compared with chronic saline. However, chronic NIC had little effect on heart rate, LV pressure, -dP/dt, LV wall and chamber dimensions, or collagen content for either group of mice.     

Tenascin-C in the extracellular matrix promotes the selection of highly proliferative and tubulogenesis-defective endothelial cells

The extracellular matrix (ECM) contains important cues for tissue homeostasis and morphogenesis. The matricellular protein tenascin-C (TN-C) is overexpressed in remodeling tissues and cancer. In the present work, we studied the effect of different ECM—which exhibited a significant diversity in their TN-C content—in endothelial survival, proliferation and tubulogenic differentiation: autologous (endothelial) ECM devoid of TN-C, but bearing large amounts of FN; fibroblast ECM, bearing both high TN-C and FN contents; and finally, glioma-derived matrices, usually poor in FN, but very rich in TN-C. HUVECs initially adhered to the immobilized matrix produced by U373 MG glioma cells, but significantly detached and died by anoikis (50 to 80%) after 24 h, as compared with cells incubated with endothelial and fibroblast matrices. Surviving endothelial cells (20 to 50%) became up to 6-fold more proliferative and formed 74–97% less tube-like structures in vitro than cells grown on non-tumoral matrices. An antibody against the EGF-like repeats of tenascin-C (TN-C) partially rescued cells from the tubulogenic defect, indicating that this molecule is responsible for the selection of highly proliferative and tubulogenic defective endothelial cells. Interestingly, by using defined substrata, in conditions that mimic glioma and normal cell ECM composition, we observed that fibronectin (FN) modulates the TN-C-induced selection of endothelial cells. Our data show that TN-C is able to modulate endothelial branching morphogenesis in vitro and, since it is prevalent in matrices of injured and tumor tissues, also suggest a role for this protein in vascular morphogenesis, in these physiological contexts.     

Viability of sporulated oocysts of Neospora caninum after exposure to different physical and chemical treatments

The aim of the present study was to evaluate the viability of Neospora caninum sporulated oocysts after various chemical and physical treatments. Bioassays in gerbils and molecular techniques (PCR-RFLP) were used for identification of the oocysts shed by experimentally infected dogs. Sporulated oocysts were purified and divided into 11 treatment groups as follows: absolute ethanol for 1 hr; 20 C for 6 hr; 4 C for 6 hr; 60 C for 1 min; 100 C for 1 min; 10% formaldehyde for 1 hr; 10% ammonia for 1 hr; 2% iodine for 1 hr; 10% sodium hypochlorite for 1 hr; 70% ethanol for 1 hr; and one group was left untreated and kept as a positive control. All chemical treatments were performed at room temperature (37 C). A total of 33 gerbils, or 3 gerbils per treatment, were used for bioassays. After treatment, the oocysts were divided into aliquots of 1,000 oocysts and orally administered to gerbils. After 63 days, the gerbils were anesthetized and killed with 0.2 ml of T61; blood and tissue samples were collected for serological (IFAT and western blotting), molecular (real-time PCR), histopathology, and immunohistochemical tests. Treatments were considered effective only if all 5 detection techniques tested negative. High temperatures at 100 C for 1 min and 10% sodium hypochlorite for 1 hr were the only treatments that met this condition, effectively inactivating all oocysts.     

Interaction between primary and secondary sporocysts of Schistosoma mansoni and the internal defence system of Biomphalaria resistant and susceptible to the parasite

The outcome of the interaction between Biomphalaria and Schistosoma mansoni depends on the response of the host internal defence system (IDS) and the escape mechanisms of the parasite. The aim of this study was to evaluate the responsiveness of the IDS (haemocytes and soluble haemolymph factors) of resistant and susceptible Biomphalaria tenagophila lineages and Biomphalaria glabrata lineages in the presence of in vitro-transformed primary sporocysts and secondary sporocysts obtained from infected B. glabrata. To do this, we assayed the cellular adhesion index (CAI), analysed viability/mortality, used fluorescent markers to evaluate the tegumental damage and transplanted secondary sporocysts. B. tenagophila Taim was more effective against primary and secondary sporocystes than the susceptible lineage and B. glabrata. Compared with secondary sporocysts exposed to B. tenagophila, primary sporocysts showed a higher CAI, a greater percentage of dead sporocysts and were labelled by lectin from Glycine max and Alexa-Fluor 488 fluorescent probes at a higher rate than the secondary sporocysts. However, the two B. tenagophila lineages showed no cercarial shedding after inoculation with secondary sporocysts. Our hypothesis that secondary sporocysts can escape the B. tenagophila IDS cannot be confirmed by the transplantation experiments. These data suggest that there are additional mechanisms involved in the lower susceptibilty of B. tenagophila to S. mansoni infection.     

The activity of a metronidazole analogue and its β-cyclodextrin complex against Trypanosoma cruzi

In this study we prepared an inclusion complex between an iodide analogue of metronidazole (MTZ-I) and cyclodextrin (CD) to develop a safer and more effective method of treating Trypanosoma cruzi infections. According to our results, MTZ-I and MTZ-I:β-CD were 10 times more active than MTZ, demonstrating that the presence of an iodine atom on the side chain increased the trypanocidal activity while maintaining its cytotoxicity. The selective index shows that MTZ-I was 10 times more active against T. cruzi than it was against mammalian cells. The modification of MTZ side chains provides a promising avenue for the development of new drugs.     

Urinary 2,5 hexanedione as a biomarker of n-hexane exposure

n-Hexane is a saturated aliphatic hydrocarbon widely used in industry. In most cases it is used as a mixture with hexane isomers and various others solvents in the form of commercial hexane. n-Hexane is metabolized oxidatively to a number of compounds, including 2,5-hexanedione (2,5-HD), which is eliminated through the urine and is implicated in the neurotoxic effect of this solvent. The main objective of this study was to evaluate urinary 2,5-HD as a biomarker of n-hexane exposure. The study was carried out in seven industrial units. Post-shift urine samples from 111 workers who handled commercial hexane were collected and analysed for 2,5-HD by capillary gas chromatography. Air sampling was performed in the breathing zones of the workers, and the air samples were analysed using validated methods. Monitoring individual exposures showed that n-hexane exposure varied from 5 to 70 p.p.m. (mean ±SD = 15.24 ±2.98 p.p.m.). Significant correlation was observed between exposure to n-hexane and urinary 2,5-HD levels, with high correlation coefficients ( ρ= 0.81, p = 0.000), suggesting that urinary 2,5-HD is a good biomarker of occupational exposure to n-hexane. Urinary 2,5-HD is recommended as a better tool than air monitoring in the assessment of health risk, namely the early detection of n-hexane neurotoxicity.