Small intestinal inflammation following oral infection with Toxoplasma gondii does not occur exclusively in C57BL/6 mice: review of 70 reports from the literature

Small intestinal immunopathology following oral infection with tissue cysts of Toxoplasma gondii has been described in C57BL/6 mice. Seven days after infection, mice develop severe small intestinal necrosis and succumb to infection. The immunopathology is mediated by local overproduction of Th1-type cytokines, a so-called "cytokine storm". The immunopathogenesis of this pathology resembles that of inflammatory bowel disease in humans, i.e., Crohn's disease. In this review, we show that the development of intestinal pathology following oral ingestion of T. gondii is not limited to C57BL/6 mice, but frequently occurs in nature. Using a Pubmed search, we identified 70 publications that report the development of gastrointestinal inflammation following infection with T. gondii in 63 animal species. Of these publications, 53 reports are on accidental ingestion of T. gondii in 49 different animal species and 17 reports are on experimental infections in 19 different animal species. Thus, oral infection with T. gondii appears to cause immunopathology in a large number of animal species in addition to mice. This manuscript reviews the common features of small intestinal immunopathology in the animal kingdom and speculates on consequences of this immunopathology for humankind.

Cl gene cluster encoding several small nucleolar RNAs: a comparison amongst trypanosomatids

Small nucleolar RNAs (snoRNAs) are small non-coding RNAs that modify RNA molecules such as rRNA and snRNA by guiding 2'-O-ribose methylation (C/D box snoRNA family) and pseudouridylation reactions (H/ACA snoRNA family). H/ACA snoRNAs are also involved in trans-splicing in trypanosomatids. The aims of this work were to characterise the Cl gene cluster that encodes several snoRNAs in Trypanosoma rangeli and compare it with clusters from Trypanosoma cruzi, Trypanosoma brucei, Leishmania major, Leishmania infantum, Leishmania braziliensis and Leptomonas collosoma. The T. rangeli Cl gene cluster is an 801 base pair (bp) repeat sequence that encodes three C/D (Cl1, Cl2 and Cl4) and three H/ACA (Cl3, Cl5 and Cl6) snoRNAs. In contrast to T. brucei, the Cl3 and Cl5 homologues have not been annotated in the Leishmania or T. cruzi genome projects (http//:www.genedb.org). Of note, snoRNA transcribed regions have a high degree of sequence identity among all species and share gene synteny. Collectively, these findings suggest that the Cl cluster could constitute an interesting target for therapeutic (gene silencing) or diagnostic intervention strategies (PCR-derived tools).

New insights into trypanosomatid U5 small nuclear ribonucleoproteins

Several protozoan parasites exist in the Trypanosomatidae family, including various agents of human diseases. Multiple lines of evidence suggest that important differences are present between the translational and mRNA processing (trans splicing) systems of trypanosomatids and other eukaryotes. In this context, certain small complexes of RNA and protein, which are named small nuclear ribonucleoproteins (U snRNPs), have an essential role in pre-mRNA processing, mainly during splicing. Even though they are well defined in mammals, snRNPs are still not well characterized in trypanosomatids. This study shows that a U5-15K protein is highly conserved among various trypanosomatid species. Tandem affinity pull-down assays revealed that this protein interacts with a novel U5-102K protein, which suggests the presence of a sub-complex that is potentially involved in the assembly of U4/U6-U5 tri-snRNPs. Functional analyses showed that U5-15K is essential for cell viability and is somehow involved with the trans and cis splicing machinery. Similar tandem affinity experiments with a trypanonosomatid U5-Cwc21 protein led to the purification of four U5 snRNP specific proteins and a Sm core, suggesting U5-Cwc-21 participation in the 35S U5 snRNP particle. Of these proteins, U5-200K was molecularly characterized. U5-200K has conserved domains, such as the DEAD/DEAH box helicase and Sec63 domains and displays a strong interaction with U5 snRNA.

Footprints of a trypanosomatid RNA world: pre-small subunit rRNA processing by spliced leader addition trans-splicing

The addition of a capped mini-exon [spliced leader (SL)] through trans-splicing is essential for the maturation of RNA polymerase (pol) II-transcribed polycistronic pre-mRNAs in all members of the Trypanosomatidae family. This process is an inter-molecular splicing reaction that follows the same basic rules of cis-splicing reactions. In this study, we demonstrated that mini-exons were added to precursor ribosomal RNA (pre-rRNA) are transcribed by RNA pol I, including the 5' external transcribed spacer (ETS) region. Additionally, we detected the SL-5'ETS molecule using three distinct methods and located the acceptor site between two known 5'ETS rRNA processing sites (A' and A1) in four different trypanosomatids. Moreover, we detected a polyadenylated 5'ETS upstream of the trans-splicing acceptor site, which also occurs in pre-mRNA trans-splicing. After treatment with an indirect trans-splicing inhibitor (sinefungin), we observed SL-5'ETS decay. However, treatment with 5-fluorouracil (a precursor of RNA synthesis that inhibits the degradation of pre-rRNA) led to the accumulation of SL-5'ETS, suggesting that the molecule may play a role in rRNA degradation. The detection of trans-splicing in these molecules may indicate broad RNA-joining properties, regardless of the polymerase used for transcription.

The small species of Belostoma Latreille (Heteroptera, Belostomatidae). III. A revision of oxyurum group, with a new species from Brazil and description of the male of B. noualhieri Montandon

Species of the oxyurum group (sensu Lauck) consist of five extant Neotropical small species, whose lengths range 15.0 to 20.0 mm. The anterior interocular width about 1.5 times the width of an eye and ventral diverticulum of phallus flattened, circular, and large are, in combination, diagnostic. The small species of the oxyurum group were included in the Lauck´s key to the identification of the species groups, without dealing with the species included in it because many of them are very similar in appearance. Therefore here we redescribe and key the Belostoma species of the oxyurum group. Belostoma oxyurum (Dufour) is newly recorded from Brazil (Paraná and Rio Grande do Sul). Holotype and lectotype are designated for B. oxyurum and B. sanctulum Montandon, respectively. The aspect of the prosternal keel, the ratio between the width of the ventral diverticulum of phallus and its length in ventral view, and the aspect of dorsal arms of ventral diverticulum have proven useful for better species delimitation. Based on specimens from Pará State (N. Brazil), Belostoma carajaensis Ribeiro & Estévez, sp. nov. is described and illustrated. This new species differs from B. sanctulum in having anteoculus shorter than interoculus and the dorsal arms of ventral diverticulum divergent and large. A male specimen of B. noualhieri Montandon was collected in São Paulo State and based mainly on features of male genitalia, this species is here also included under oxyurum group.

Impact of small variations in temperature and humidity on the reproductive activity and survival of Aedes aegypti (Diptera, Culicidae)

In short space of time increase in temperature and rainfall can affect vector populations and, consequently, the diseases for them transmitted. The present study analyzed the effect of small temperature and humidity variations on the fecundity, fertility and survival of Aedes aegypti. These parameters were analyzed using individual females at temperatures ranging from 23 to 27 °C (mean 25 °C); 28 to 32 °C (mean 30 °C) and 33 to 37 °C (mean 35 ºC) associated to 60±8% and 80±6% relative humidity. Females responded to an increase in temperature by reducing egg production, oviposition time and changing oviposition patterns. At 25 ºC and 80% relative humidity, females survived two-fold more and produced 40% more eggs when compared to those kept at 35 ºC and 80% relative humidity. However, in 45% of females kept at 35 ºC and 60% relative humidity oviposition was inhibited and only 15% females laid more than 100 eggs, suggesting that the intensity of the temperature effect was influenced by humidity. Gradual reductions in egg fertility at 60% relative humidity were observed with the increase in temperature, although such effect was not found in the 80% relative humidity at 25 º C and 30 º C. These results suggest that the reduction in population densities recorded in tropical areas during seasons when temperatures reach over 35 ºC is likely to be strongly influenced by temperature and humidity, with a negative effect on several aspects of mosquito biology.

Small-scale area effect on species richness and nesting occupancy of cavity-nesting bees and wasps

Small-scale area effect on species richness and nesting occupancy of cavity-nesting bees and wasps. The research was conducted in an urban forest remnant in southeast Brazil. We tested the predictions of the following hypotheses: (1) larger areas present higher species richness of bees and wasps, (2) solitary bees and wasps occupy more nests in larger areas, (3) rare species occupy more nests in smaller areas. We sampled Aculeate bees and wasps using trap nests from February to November 2004. We placed trap nests in sampling units (SU) with different size (25, 100 and 400 m²) located in 6 ha of secondary mesophytic forest. One hundred and thirty-seven trap nests were occupied by seven species of bees and four species of wasps. We found an increase in wasp, but not bee species richness following increase in SU size. Hymenoptera richness (i.e. bees plus wasps) was also greater in larger SU. Both the number and density of occupied nests increased with SU size. The wasp Trypoxylon lactitarse responded significantly to area size, larger SU having more occupied nests. The same pattern was exhibited by the wasp Auplopus militaris, the Megachile bee species, and the bee Anthodioctes megachiloides. Only Trypoxylon sp. was not affected by SU size. Our results show that cavity-nesting bee and wasps respond differently to the area effects. Such findings must be complemented by information on the frequency and dynamics of area colonization and nest occupancy by species of solitary Hymenoptera.

Euglossine bee communities in small forest fragments of the Atlantic Forest, Rio de Janeiro state, southeastern Brazil (Hymenoptera, Apidae)

Euglossine bee communities in small forest fragments of the Atlantic Forest, Rio de Janeiro state, southeastern Brazil (Hymenoptera, Apidae). Euglossine bees are important pollinators in forests and agricultural areas. Although the structure of their communities is critically affected by anthropogenic disturbances, little is known about these bees in small forest fragments. The objectives of this study were to analyze the composition, abundance, and diversity of euglossine bee species in nine small fragments of different phytophysiognomies of the Atlantic Forest in southeastern Brazil, and to identify the environmental variables that may be related to the species composition of these communities. Males were sampled quarterly from May 2007 to May 2009 with aromatic traps containing methyl cinnamate, vanillin, eucalyptol, benzyl acetate, and methyl salicylate. A total of 1558 males, belonging to 10 species and three genera of Euglossina were collected. The richness ranged from five to seven species per fragment. Euglossa cordata, E. securigera, Eulaema nigrita e E. cingulata were common to all fragments studied. The diversity differed significantly among areas, ranging from H' = 1.04 to H' = 1.65. The precipitation, phytophysiognomy, and altitude had the highest relative importance over the species composition variation. The results presented in this study demonstrate that small forest fragments are able to support populations of euglossine bee species, most of which are widely distributed and reportedly tolerant to open and/or disturbed areas and suggest that the conservation of such areas is important, particularly in areas that are regenerating and in regions with agricultural matrices where these bees can act as important pollinators

Dung beetle (Coleoptera, Scarabaeidae) assemblage of a highly fragmented landscape of Atlantic forest: from small to the largest fragments of northeastern Brazilian region

Human activities in tropical forests are the main causes of forest fragmentation. According to historical factor in deforestation processes, forest remnants exhibit different sizes and shapes. The aim of the present study was to evaluate the dung beetle assemblage on fragments of different degree of sizes. Sampling was performed during rainy and dry season of 2010 in six fragments of Atlantic forest, using pitfall traps baited with excrement and carrion. Also, we used two larger fragments as control. We used General Linear Models to determine whether the fragments presented distinguished dung beetle abundance and richness. Analysis of Similarities and Non-Metric Multidimensional Scaling were used to determine whether the dung beetle assemblage was grouped according to species composition. A total of 3352 individuals were collected and 19 species were identified in the six fragments sampled. Dung beetle abundance exhibited a shift according to fragment size; however, richness did not change among fragments evaluated. Also, fragments sampled and the two controls exhibited distinct species composition. The distinction on abundance of dung beetles among fragments may be related to different amount of resource available in each one. It is likely that the dung beetle richness did not distinguish among the different fragments due to the even distribution of the mammal communities in these patches, and consequent equal dung diversity. We conclude that larger fragments encompass higher abundance of dung beetle and distinct species. However, for a clearer understanding of effects of fragmentation on dung beetles in Atlantic forest, studies evaluating narrower variations of larger fragments should be conducted.

Protective effect of divalent cations against aluminum toxicity in soybean

A large proportion of soybean fields in Brazil are currently cultivated in the Cerrado region, where the area planted with this crop is growing considerably every year. Soybean cultivation in acid soils is also increasing worldwide. Since the levels of toxic aluminum (Al) in these acid soils is usually high it is important to understand how cations can reduce Al rhizotoxicity in soybean. In the present study we evaluated the ameliorative effect of nine divalent cations (Ca, Mg, Mn, Sr, Sn, Cu, Zn, Co and Ba) in solution culture on Al rhizotoxicity in soybean. The growth benefit of Ca and Mg to plants in an acid Inceptisol was also evaluated. In this experiment soil exchangeable Ca:Mg ratios were adjusted to reach 10 and 60 % base saturation, controlled by different amounts of CaCl2 or MgCl2 (at proportions from 100:0 up to 0:100), without altering the soil pH level. The low (10 %) and adequate (60 %) base saturation were used to examine how plant roots respond to Al at distinct (Ca + Mg)/Al ratios, as if they were growing in soils with distinct acidity levels. Negative and positive control treatments consisted of absence (under native soil or undisturbed conditions) or presence of lime (CaCO3) to reach 10 and 60 % base saturation, respectively. It was observed that in the absence of Aluminum, Cu, Zn, Co and Sn were toxic even at a low concentration (25 µmol L-1), while the effect of Mn, Ba, Sr and Mg was positive or absent on soybean root elongation when used in concentrations up to 100 µmol L-1. At a level of 10 µmol L-1 Al, root growth was only reverted to the level of control plants by the Mg treatment. Higher Tin doses led to a small alleviation of Al rhizotoxicity, while the other cations reduced root growth or had no effect. This is an indication that the Mg effect is ion-specific and not associated to an electrostatic protection mechanism only, since all ions were divalent and used at low concentrations. An increased exchangeable Ca:Mg ratio (at constant soil pH) in the acid soil almost doubled the soybean shoot and root dry matter even though treatments did not modify soil pH and exchangeable Al3+. This indicates a more efficient alleviation of Al toxicity by Mg2+ than by Ca2+. The reason for the positive response to Mg2+ was not the supply of a deficient nutrient because CaCO3 increased soybean growth by increasing soil pH without inducing Mg2+ deficiency. Both in hydroponics and acid soil, the reduction in Al toxicity was accompanied by a lower Al accumulation in plant tissue, suggesting a competitive cation absorption and/or exclusion of Al from plant tissue stimulated by an Mg-induced physiological mechanism.

Use of the swat model for hydro-sedimentologic simulation in a small rural watershed

Mathematical models have great potential to support land use planning, with the goal of improving water and land quality. Before using a model, however, the model must demonstrate that it can correctly simulate the hydrological and erosive processes of a given site. The SWAT model (Soil and Water Assessment Tool) was developed in the United States to evaluate the effects of conservation agriculture on hydrological processes and water quality at the watershed scale. This model was initially proposed for use without calibration, which would eliminate the need for measured hydro-sedimentologic data. In this study, the SWAT model was evaluated in a small rural watershed (1.19 km²) located on the basalt slopes of the state of Rio Grande do Sul in southern Brazil, where farmers have been using cover crops associated with minimum tillage to control soil erosion. Values simulated by the model were compared with measured hydro-sedimentological data. Results for surface and total runoff on a daily basis were considered unsatisfactory (Nash-Sutcliffe efficiency coefficient - NSE < 0.5). However simulation results on monthly and annual scales were significantly better. With regard to the erosion process, the simulated sediment yields for all years of the study were unsatisfactory in comparison with the observed values on a daily and monthly basis (NSE values < -6), and overestimated the annual sediment yield by more than 100 %.

Quality of surface water related to land use: a case study in a catchment with small farms and intensive vegetable crop production in southern Brazil

Water degradation is strongly related to agricultural activity. The aim of this study was to evaluate the influence of land use and some environmental components on surface water quality in the Campestre catchment, located in Colombo, state of Parana, Brazil. Physical and chemical attributes were analyzed (total nitrogen, ammonium, nitrate, total phosphorus, electrical conductivity, pH, temperature, turbidity, total solids, biological oxygen demand, chemical oxygen demand and dissolved oxygen). Monthly samples of the river water were taken over one year at eight monitoring sites, distributed over three sub-basins. Overall, water quality was worse in the sub-basin with a higher percentage of agriculture, and was also affected by a lower percentage of native forest and permanent preservation area, and a larger drainage area. Water quality was also negatively affected by the presence of agriculture in the riparian zone. In the summer season, probably due to higher rainfall and intensive soil use, a higher concentration of total nitrogen and particulate nitrogen was observed, as well as higher electrical conductivity, pH and turbidity. All attributes, except for total phosphorus, were in compliance with Brazilian Conama Resolution Nº 357/2005 for freshwater class 1. However, it should be noted that these results referred to the base flow and did not represent a discharge condition since most of the water samples were not collected at or near the rainfall event.

Coordenação local do Eu(III) em híbridos orgânicos/inorgânicos emissores de luz branca

Eu3+ luminescence and EXAFS (Extended X-ray Absorption Fine Structure) results are presented for organic-inorganic hybrid gel hosts composed of a siliceous network to which small chains of oxyethylene units are covalently grafted by means of urea bridges. Coordination numbers for Eu3+ ions range from 12.8 to 9.7 with increasing Eu3+ concentration while the Eu3+-first neighbours mean distance is found to be constant at 2.48-2.49 Å in the same concentration range. Emission spectra display a broad band in the green/blue spectral region superposed to narrow lines appearing in the yellow/red region in such a way that for the eyes emission appears white. The broad band is assigned to intrinsic NH groups emission and also to electron-hole recombination in the nanosised siliceous domains. The narrow lines are assigned to intra-4f6, 5D0->7F0-4 Eu3+ transitions and from the energy position of the 7F0-4 levels a mean distance could be calculated for the Eu3+-first neighbours. The calculated results are in good agreement with the experimental ones obtained from EXAFS analysis.

Implications, large and small, from chemical education research for the teaching of chemistry

Research studies in chemical education pose a communication problem for chemists. Unlike the findings from other specializations in chemistry the findings in chemical education tend to be reported in education journals that are not readily accessible to most chemists or chemistry teachers. This lecture is an attempt to remedy this gap in communication. Research studies fall into three broad categories. (i) issues related to the content of chemistry itself, that is, What content to teach? And What meaning of each topic is to be conveyed? (ii) issues related to how chemical content is taught, such as, the role of lectures, practical work, particular pedagogies, etc. and (iii) issues related to its learning, that is, learning of concepts, conceptual change, motivation, etc. Findings in each of these categories of research over the last twenty years have drawn attention to opportunities for improving the quality of chemical education in each of the levels of formal education where chemistry is taught. Sometimes the research findings seem small since they, in fact, merely diagnose the actual problem in teaching and learning. At other times, the research findings are large because they provide a solution to these problems. What remains to be done is to disseminate the findings so that appropriate teaching occurs more widely, with its consequent gains in the quality of learning. Research findings, of these small and large types will be used to illustrate the potential of research to make the practice of chemical education more effective.

Preparação de LiNbO3 e LiNbO3:Eu3+ pelo método dos precursores poliméricos

The ferroelectric compound LiNbO3 was prepared by the polymeric precursors method in the polycrystalline form containing different concentrations of Eu3+. The compounds were characterized by X-ray diffraction, vibrational and electronic spectroscopy. Electronic spectroscopy was shown to be sensitive to small concentrations of contaminating phases allowing a good control of the compound purity. The presence of Eu3+ ions leads to the formation of the LiNb3O8 phase in the range of 500 to 800 °C. Above this temperature range LiNbO3 and tetragonal (T') EuNbO4 were obtained.