How do Mycorrhizas Affect C and N Relationships in Flooded Aster tripolium Plants?

The mycorrhizal associations established between plants and fungi have multiple effects on plant growth, directly affecting stress tolerance. This work aimed to explore arbuscular mycorrhizal (AM) effects on carbon and nitrogen relationships of Aster tripolium L. and consequently on its flooding tolerance. Mycorrhizal and non-mycorrhizal juvenile plants were submitted to non-flooding and tidal flooding conditions for 56 d. Tidal flooding reduced biomass, but the presence of mycorrhiza had an ameliorating effect. The AM symbioses seem to have, like flooding, a stressful effect on A. tripolium at an early stage of plant development. However, once the plant was established, an improvement of growth performance of plants with mycorrhiza under flooding conditions was observed. The better tolerance of AM plants to flooding was mediated through an improvement of the osmotic adjustment of the plant tissues (higher concentrations of soluble sugars and proline) and through the increment of nitrogen acquisition in tidal-flooded plants.     

Detection and quantification of unbound phytochelatin 2 in plant extracts of Brassica napus grown with different levels of mercury

The mercury (Hg) accumulation mechanism was studied in rape (Brassica napus) plants grown under a Hg concentration gradient (0 microm-1,000 microm). Hg mainly accumulated in roots. Therefore, the presence of phytochelatins (PCs) was studied in the roots of the plants. The high stability of the PC-Hg multicomplexes (mPC-nHg) seems to be the main reason for the lack of previous Hg-PC characterization studies. We propose a modification of the method to detect and quantify unbound PC of Hg in plant extracts via high-performance liquid chromatography coupled to electrospray tandem mass spectrometry and inductively coupled plasma mass spectrometry in parallel. We separated the PC from the Hg by adding the chelating agent sodium 2,3-dimercaptopropanesulfonate monohydrate. We only detected the presence of PC after the addition of the chelating agent. Some multicomplexes mPC-nHg could be formed but, due to their large sizes, could not be detected. In this study, only PC(2) was observed in plant samples. Hg accumulation was correlated with PC(2) concentration (r(2) = 0.98).     

Power saturation of ESR signal in ammonium tartrate exposed to 60Co gamma-ray photons, electrons and protons

In this paper we present an investigation of the electron spin resonance (ESR) line shape of ammonium tartrate (AT) dosimeters exposed to radiation with different linear energy transfer (LET). We exposed our dosimeters to gamma-ray photons ((60)Co), 7 MeV and 14 MeV initial energy electrons, and 19.3 MeV initial energy protons. The differences in the power saturation behavior of ESR spectra of AT irradiated with photons, electrons and protons could be correlated to the effective LET of the radiation beams. We analyzed the behavior of peak-to-peak amplitude as a function of microwave power, and we developed a fitting procedure that permits us to obtain the dependence of the homogeneity parameter of the line shape on the LET of the radiation using the Castner saturation theory. This simple procedure allows us to distinguish the LET of the radiation beam.     

Costs of twins in free-ranging white-bellied spider monkeys (Ateles belzebuth belzebuth) at Tinigua National Park, Colombia

A female spider monkey (Ateles belzebuth belzebuth) that gave birth to twins was studied during 13 months, and her activity budget and diet were compared to those of females with single offspring and females with no offspring to assess selective pressures that could influence litter size. We recorded qualitative information on the development and social interactions of the twins and three other single infants. Emi, the female that had the twins, had the highest proportion of resting time and the lowest proportion of feeding and moving time compared to other adult females and males. Emi also had the lowest average daily travel distance and relied more heavily on flowers and leaves than other group members who included a higher proportion of fruits in their diets. These results suggest that twins are energetically costly to spider monkeys because of the direct energy allocated into raising and carrying the twins and, also, because these costs have direct effects in the ability of a mother to obtain high-quality resources (e.g., fruits). The twins had a slower rate of physical and social development as well as a smaller body size compared to same-aged singletons by the end of the study. Thus, the extended periods of maternal care and the costs associated with rearing and carrying offspring are some of the factors that influence the evolution and maintenance of a litter size of one in most anthropoid primates.     

Schistosoma mansoni antigen-driven interleukin-10 production in infected asthmatic individuals

Asthmatics infected with Schistosoma mansoni have a less severe course of asthma and an inhibition of the Th2 inflammatory response that seems to be mediated by interleukin (IL-10). The objective of this study was to evaluate the capacity of some S. mansoni antigens to stimulate IL-10 production in vitro by cells of asthmatic infected individuals. Peripheral bloods mononuclear cells were stimulated with the S. mansoni recombinant antigens Sm22.6, Sm14, P24, and PIII antigen. IL-10 was measured in the supernatants of cultures. As the recombinant antigens were cloned in Escherichia coli, we blocked contaminant endotoxin with polymyxin B added to the cultures. We demonstrated that all antigens used drove high production of IL-10 in S. mansoni infected individuals (n = 13, 408 +/- 514 and 401 +/- 383 pg/ml, 484 +/- 245 pg/ml, 579 +/- 468 pg/ml, respectively). In asthmatics infected with S. mansoni (n = 21) rP24 induced higher levels of IL-10 (565 +/- 377 pg/ml) when compared to PIII, rSm14 and rSm22.6 (184 +/- 209 pg/ml; 292 +/- 243 pg/ml; 156 +/- 247 pg/ml, respectively). Conclusion: the S. mansoni antigens evaluated in this study stimulated IL-10 production by cells from infected individuals and therefore they have the potential to be used as a modulator of the inflammatory response in asthma.     

In vitro susceptibility to antifungal agents of environmental Cryptococcus spp. isolated in the city of Ribeirão Preto, São Paulo, Brazil

Infections by Cryptococcus strains other than C. neoformans have been detected in immunocompromised patients. Of these strains, three are considered human pathogens: C. albidus, C. laurenttii, and C. uniguttulatus. This study deals with the in vitro susceptibility of Cryptococcus to drugs such as amphotericin B, itraconazole, fluconazole, and 5-fluorocytosine. Environmental Cryptococcus isolates (50) distributed as follows: C. neoformans var. neoformans (16), C. albidus (17), C. laurentii (14), and C. uniguttulatus (3) were evaluated by the micro and macrodilution techniques, according to EUCAST and NCCLS recommendations, respectively. Considering both methodologies the respective minimal inhibitory concentrations (MIC) were 0.125 and 2 microg/ml for amphotericin B, 0.06 and 8 microg/ml for itraconazole, and 0.5 and more than 64 microg/ml for fluconazole and 5-fluorocytosine. Agreement percentages for the two methodologies were 100% for amphotericin B and fluconazole for all the strains tested. For itraconazole, the agreement percentage was 81.3% in the C. neoformans strain and 100% for all the others. All species had a agreement percentage of 94.1 to 100% when susceptibility to 5-fluorocytosine was tested. It is concluded that environmental isolates of C. neoformans var. neoformans, C. albidus, C. laurentii, and C. uniguttulatus may show high MICs against certain drugs, suggesting in vitro primary resistance to the antifungals tested.     

Hepatic stereology of Schistosomiasis mansoni infected-mice fed a high-fat diet

High-fat diets induce weight gain and fatty liver in wild-type mice. Schistosomiasis mansoni infection also promotes hepatic injury. This study was designed to quantify hepatic alterations in schistosomiasis mansoni-infected mice fed a high fat-rich chow compared to mice fed a standard rodent chow, using stereology. Female SW mice fed each either high-fat diet (29% lipids) or standard chow (12% lipids) over 8 months, and then were infected with Schistosoma mansoni cercariae. Four experimental groups were studied: infected mice fed a high-fat diet (IHFC) or standard chow (ISC), uninfected mice fed a high-fat diet (HFC) or standard chow (SC). Mice were sacrificed during early infection (9 weeks from exposure). The following hepatic biometry and the stereology parameters were determined: volume density (hepatocytes [h], sinusoids [s], steatosis [st] and hepatic fibrosis [hf]); numerical density (hepatocyte nuclei - Nv[h]); absolute number of total hepatocyte N[h], normal hepatocyte N[nh], and binucleated hepatocyte N[bh], percentage of normal hepatocyte P[nh] and binucleated hepatocyte P[bh]. IHFC and HFC groups exhibited TC, HDL-C, LDL-C, and body mass significantly greater (p < 0.05) than control group. No significant differences were found regards liver volume (p = 0.07). Significant differences were observed regards P[nh] (p = 0.0045), P[bh] (p = 0.0045), Nv[h] (p = 0.0006), N[h] (p = 0.0125), N[bh] (p = 0.0164) and N[nh] (p = 0.0078). IHFC mice group presented 29% of binucleated hepatocytes compared to HFC group (19%), ISC group (17%) and SC (6%). Volume density was significantly different between groups: Vv[h] (p = 0.0052), Vv[s] (p = 0.0025), Vv[st] (p = 0.0004), and Vv[hf] (p = 0.0007). In conclusion, schistosomiasis mansoni infection with concurrent high-fat diet promotes intensive quantitative changes in hepatic structure, contributing to an increasing on hepatic regeneration.     

A Rich1/Amot complex regulates the Cdc42 GTPase and apical-polarity proteins in epithelial cells

Using functional and proteomic screens of proteins that regulate the Cdc42 GTPase, we have identified a network of protein interactions that center around the Cdc42 RhoGAP Rich1 and organize apical polarity in MDCK epithelial cells. Rich1 binds the scaffolding protein angiomotin (Amot) and is thereby targeted to a protein complex at tight junctions (TJs) containing the PDZ-domain proteins Pals1, Patj, and Par-3. Regulation of Cdc42 by Rich1 is necessary for maintenance of TJs, and Rich1 is therefore an important mediator of this polarity complex. Furthermore, the coiled-coil domain of Amot, with which it binds Rich1, is necessary for localization to apical membranes and is required for Amot to relocalize Pals1 and Par-3 to internal puncta. We propose that Rich1 and Amot maintain TJ integrity by the coordinate regulation of Cdc42 and by linking specific components of the TJ to intracellular protein trafficking.     

Genetic characterization of the phenylacetyl-coenzyme A oxygenase from the aerobic phenylacetic acid degradation pathway of Escherichia coli

We show here that the paaABCDE genes of the paa cluster responsible for phenylacetate degradation in Escherichia coli W encode a five-component oxygenase that hydroxylates phenylacetyl-coenzyme A (CoA), the first intermediate of the pathway. The primary structure of the subunits of bacterial phenylacetyl-CoA oxygenases revealed that these enzymes constitute the prototype of a new and distinct group of the large bacterial diiron multicomponent oxygenase family.     

Genetic variability of Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) populations from Latin America is associated with variations in susceptibility to Bacillus thuringiensis cry toxins

Bacillus thuringiensis strains isolated from Latin American soil samples that showed toxicity against three Spodoptera frugiperda populations from different geographical areas (Mexico, Colombia, and Brazil) were characterized on the basis of their insecticidal activity, crystal morphology, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of parasporal crystals, plasmid profiles, and cry gene content. We found that the different S. frugiperda populations display different susceptibilities to the selected B. thuringiensis strains and also to pure preparations of Cry1B, Cry1C, and Cry1D toxins. Binding assays performed with pure toxin demonstrated that the differences in the toxin binding capacities of these insect populations correlated with the observed differences in susceptibility to the three Cry toxins analyzed. Finally, the genetic variability of the three insect populations was analyzed by random amplification of polymorphic DNA-PCR, which showed significant genetic diversity among the three S. frugiperda populations analyzed. The data presented here show that the genetic variability of S. frugiperda populations should be carefully considered in the development of insect pest control strategies, including the deployment of genetically modified maize in different geographical regions.