Occurrence of weed species in Jatropha curcas intercropping systems

This study aimed to evaluate the level of infestation by weed species in a consolidated Jatropha plantation, as a function of the plant species grown in interrows. The experiment was installed in 2006 at the district of Itahum, city of Dourados, state of Mato Grosso do Sul, Brazil, made possible through a partnership between Embrapa Western Agriculture and Paraiso Farm. Treatments consisted of (1) Jatropha in monocrop, with no plant at the interrrows; or the following plants cultivaded at the interrows of Jatropha: (2) Stylosanthes spp.; (3) Brachiaria ruziziensis; (4) Brachiaria ruziziensis + Stylosanthess pp.; (5) Brachiaria humidicola; (6) Panicum maximum cv. massai; (7) Cajanus cajan cv. anão; (8) Crotalaria spectabilis; (9) Crop rotation system 1 - (maize second crop -Crambe abyssinica - soybean - peanut); and (10) Crop rotation system 2 - (cowpea - radish - maize - cowpea) conducted for two years. Phytosociological characterization of weed species was accomplished in 2011 based on the Ecological Approach. Estimations of relative abundance, frequency, dominance and Importance Value Index were obtained. Areas were also characterized by the diversity coefficients of Simpson and modified Shannon-Weiner, and then grouped by cluster analysis. Areas with low soil coverage resulted in higher infestation levels; crop rotation in the interrows of Jatropha produced a significant reduction in weed infestation, but the lowest infestation levels were observed when grasses were grown intercropped with Jatropha. Lower diversity coefficients were associated with occurrence of the most troublesome weed species. In the first years after planting Jatropha, species of Brachiaria or a crop rotation involving species with high mulching ability and whose biomass exhibit a high C:N ratio, should be established in the interrows to avoid problems with weeds infestation.

Dormancy studies on Euphorbia dracunculoides and Astragalus spp.: major weeds of arid areas

The aim of this study was to examine the dormancy behavior of Euphorbia dracunculoides and Astragalus spp., weeds of arid chickpea. The dormancy breaking treatments were: Gibberalic acid (GA3) and Thiourea each at 50, 100, 150, 200, 250, and 300 ppm and Potassium nitrate (KNO3) at 5,000, 10,000, 15,000, 20,000, 25,000, and 30,000 ppm (24 h soaking). Germination (G) percentage and germination energy (GE) of E. dracunculoides was maximum (89 and 22, respectively) at 250 ppm concentration of GA3 and 81.50 and 11.50 at 15000 ppm concentration of KNO3. Thiourea at 250 and 300 ppm resulted in maximum G percentage (51) and GE (25.50) of E. dracunculoides, whereas the G percentage and GE of Astragalus spp. were maximum (28 and 19, respectively) at the lowest concentration of GA3 (50 ppm). On the other hand, 5000 ppm and 150 ppm concentration of KNO3 and Thiourea showed maximum GE (19.5) and G percentage (28) of Astragalus spp., respectively. Overall, effective dormancy breaking chemical against E. dracunculoides was GA3 (250 ppm) while in Astragalus spp. none of chemicals showed very impressive results. These results showed that both weeds' seeds have dormancy in their habit. Hot water treatment and the above mentioned chemicals (best concentrations) when used with 4, 8, and 12 hours soaking showed ineffective results.

DETECTION OF GLYPHOSATE-RESISTANT PALMER AMARANTH (Amaranthus palmeri) IN AGRICULTURAL AREAS OF MATO GROSSO, BRAZIL

ABSTRACT The recent introduction of Palmer amaranth (Amaranthus palmeri) in Brazilian agricultural areas may promote several changes on weed management, especially in no-till systems and in glyphosate-resistant crops, since glyphosate-resistant biotypes of A. palmerihave been frequently selected in other countries. Therefore, this research was developed in order to evaluate the glyphosate susceptibility of a Palmer amaranth biotype recently identified in the State of Mato Grosso, Brazil. For this purpose, glyphosate susceptibility of three Amaranthusbiotypes was compared: A.hybridus var. patulus, collected in the State of Rio Grande do Sul - Brazil; A.hybridus var. patulus, collected in the State of São Paulo - Brazil; and A.palmeri, collected in the State of Mato Grosso - Brazil. Dose-response curves were generated for all biotypes, considering eight rates of glyphosate and six replicates. All the experiments were repeated twice. Both A.hybridus biotypes were satisfactorily controlled by glyphosate, demanding rates equal to or lower than 541.15 g a.e. ha-1 for 80% control (LD80). The A.palmeri biotype was not controlled by glyphosate in any of the assessments and required rates greater than 4,500 g a.e. ha-1 to reach LD80, which are economically and environmentally unacceptable. Comparison of the Brazilian A.palmeri biotype to the A. hybridus biotypes, as well as, to the results available in scientific international literature, led to the conclusion that the Brazilian Palmer amaranth biotype is resistant to glyphosate.

Influence of edaphic variables on the floristic composition and structure of the tree-shrub vegetation in typical and rocky outcrop cerrado areas in Serra Negra, Goiás State, Brazil

The present study analyzed the influence of edaphic variables on the floristic compositions and structures of the arboreal and shrub vegetation of typical cerrado (TC) and rocky outcrop cerrado (RC) communities in the Serra Negra mountain range in Piranhas Municipality, Goiás State, Brazil. Ten 20×50m plots were established in each community, and all individuals with minimum diameters ³5cm measured at 30cm above soil level were sampled. Composite soil samples were collected at 0-20cm depths in each plot for physical and chemical analyses. The proportions of above-ground rock cover work also estimated in each RC plot. A total of 2,009 individuals (83 species, 69 genera, and 34 families) were recorded. Qualea parviflora was the only species consistently among the 10 most structurally important taxa in both communities, and was considered a generalist species. The observed and estimated species richnesses were greater in RC than in TC, although plant basal areas and heights did not differ between them. There were positive correlations between rock cover×plant density and rock cover×basal areas. TWINSPAN and PCA analysis separated the TC and RC plots, and three RC habitat specialist species (Wunderlichia mirabilis, Norantea guianensis, and Tibouchina papyrus) were identified. Soil variables were found to have greater effects on the species compositions of the TC and RC sites than the geographic distances between sampling plots. According to CCA analysis, the exclusive (or more abundant species) of each community were correlated with soil variables, and these variables therefore determined the selection of some species and influenced the differentiation of the vegetation structures of the communities studied.

The tree-shrub vegetation in rocky outcrop cerrado areas in Goiás State, Brazil

We describe the floristic composition of the tree-shrub vegetation in 10 areas of rocky outcrop cerrado in Goiás State, Brazil. Ten 20×50m plots (totaling 1ha) were established and all of the individuals with diameters at 30cm above soil level (DB30) ³5cm were included in the sampling. Comparative analyses of the flora were realized using similarity indices (Sørensen and Czekanowski), classification analysis (TWINSPAN), and the Mantel test. A total of 13,041 tree-shrub individuals were sampled, distributed among 219 species, 129 genera and 55 families. Fabaceae was the most well-represented family, followed by Myrtaceae, Melastomataceae, Vochysiaceae, Malphigiaceae, and Rubiaceae. Fully 42.3% of the comparisons evaluated by the Sørensen index were >0.50, while all the values were <0.50 for the Czekanowski index, with the exception of Jaraguá and Mara Rosa areas. The TWINSPAN classification generated four divisions and, in general, only the differences in the size of the population were responsible for the groupings. The Mantel test indicated that there was no relationship between floristic similarity and the distances between the areas (r=0.32, P=0.05). It therefore appears that the areas of rocky outcrop cerrado in Goiás State are relatively floristically homogeneous and that they are principally distinguished by the differences in the sizes of the populations of their dominant species, and the presence of exclusive species in certain areas.

Plasma clearance and biodistribution of oxidatively modified 99mTc-ß-VLDL in rabbits

The biodistribution and removal from plasma (measured as fractional clearance rate, FCR, per hour) of native and oxidatively modified 99mtechnetium-labeled ß-very low density lipoprotein (99mTc-ß-VLDL) were investigated in hypercholesterolemic (HC) and control (C) three-month old New Zealand rabbits. The intracellular accumulation of ß-VLDL labeled with 99mTc was studied in vitro in THP-1 cells and monocyte-derived macrophages isolated from rabbits. After intravenous injection into C rabbits, copper-oxidized ß-VLDL (99mTc-ox-ß-VLDL) was cleared from the circulation faster (0.362 ± 0.070/h) than native ß-VLDL (99mTc-nat-ß-VLDL, 0.241 ± 0.070/h). In contrast, the FCR of 99mTc-ox-ß-VLDL in HC rabbits was lower (0.100 ± 0.048/h) than that of 99mTc-nat-ß-VLDL (0.163 ± 0.043/h). The hepatic uptake of radiolabeled lipoproteins was lower in HC rabbits (0.114 ± 0.071% injected dose/g tissue for 99mTc-nat-ß-VLDL and 0.116 ± 0.057% injected dose/g tissue for 99mTc-ox-ß-VLDL) than in C rabbits (0.301 ± 0.113% injected dose/g tissue for 99mTc-nat-ß-VLDL and 0.305 ± 0.149% injected dose/g tissue for 99mTc-ox-ß-VLDL). The uptake of 99mTc-nat-ß-VLDL and 99mTc-ox-ß-VLDL by atherosclerotic aorta lesions isolated from HC rabbits (99mTc-nat-ß-VLDL: 0.033 ± 0.012% injected dose/g tissue and 99mTc-ox-ß-VLDL: 0.039 ± 0.017% injected dose/g tissue) was higher in comparison to that of non-atherosclerotic aortas from C rabbits (99mTc-nat-ß-VLDL: 0.023 ± 0.010% injected dose/g tissue and 99mTc-ox-ß-VLDL: 0.019 ± 0.010% injected dose/g tissue). However, 99mTc-nat-ß-VLDL and 99mTc-ox-ß-VLDL were taken up by atherosclerotic lesions at similar rates. In vitro studies showed that both monocyte-derived macrophages isolated from rabbits and THP-1 macrophages significantly internalized more 99mTc-ox-ß-VLDL than 99mTc-nat-ß-VLDL. These results indicate that in cholesterol-fed rabbits 99mTc-ox-ß-VLDL is slowly cleared from plasma and accumulates in atherosclerotic lesions. However, although the extent of in vitro uptake of 99mTc-ox-ß-VLDL by macrophages was high, the in vivo accumulation of this radiolabeled lipoprotein by atherosclerotic lesions did not differ from that of 99mTc-nat-ß-VLDL.

The brain decade in debate: VI. Sensory and motor maps: dynamics and plasticity

This article is an edited transcription of a virtual symposium promoted by the Brazilian Society of Neuroscience and Behavior (SBNeC). Although the dynamics of sensory and motor representations have been one of the most studied features of the central nervous system, the actual mechanisms of brain plasticity that underlie the dynamic nature of sensory and motor maps are not entirely unraveled. Our discussion began with the notion that the processing of sensory information depends on many different cortical areas. Some of them are arranged topographically and others have non-topographic (analytical) properties. Besides a sensory component, every cortical area has an efferent output that can be mapped and can influence motor behavior. Although new behaviors might be related to modifications of the sensory or motor representations in a given cortical area, they can also be the result of the acquired ability to make new associations between specific sensory cues and certain movements, a type of learning known as conditioning motor learning. Many types of learning are directly related to the emotional or cognitive context in which a new behavior is acquired. This has been demonstrated by paradigms in which the receptive field properties of cortical neurons are modified when an animal is engaged in a given discrimination task or when a triggering feature is paired with an aversive stimulus. The role of the cholinergic input from the nucleus basalis to the neocortex was also highlighted as one important component of the circuits responsible for the context-dependent changes that can be induced in cortical maps.

Interhemispheric connections between primary visual areas: beyond the midline rule

In the last five years, a number of detailed anatomical, electrophysiological, optical imaging and simulation studies performed in a variety of non-human species have revealed that the functional organization of callosal connections between primary visual areas is more elaborate than previously thought. Callosal cell bodies and terminals are clustered in columns whose correspondence to features mapped in the visual cortex, such as orientation and ocularity, are starting to be understood. Callosal connections are not restricted to the vertical midline representation nor do they establish merely point-to-point retinotopic correspondences across the hemispheres, as traditionally believed. In addition, anatomical studies have revealed the existence of an ipsilateral component of callosal axons. The aim of this short review is to propose how these new data can be integrated into an updated scheme of the circuits responsible for assembling the primary visual field map.

Design and applications of modified oligonucleotides

Oligonucleotides have a wide range of applications in fields such as biotechnology, molecular biology, diagnosis and therapy. However, the spectrum of uses can be broadened by introducing chemical modifications into their structures. The most prolific field in the search for new oligonucleotide analogs is the antisense strategy, where chemical modifications confer appropriate characteristics such as hybridization, resistance to nucleases, cellular uptake, selectivity and, basically, good pharmacokinetic and pharmacodynamic properties. Combinatorial technology is another research area where oligonucleotides and their analogs are extensively employed. Aptamers, new catalytic ribozymes and deoxyribozymes are RNA or DNA molecules individualized from a randomly synthesized library on the basis of a particular property. They are identified by repeated cycles of selection and amplification, using PCR technologies. Modified nucleotides can be introduced either during the amplification procedure or after selection.

Cardiovascular complications and increased levels of circulating modified low density lipoprotein in HIV patients and patients with lipodystrophy

The introduction of highly active antiretroviral therapy (HAART) for patients infected with HIV has significantly prolonged the life expectancy and to some extent has restored a functional immune response. However, the premature introduction of HAART has led to a significant and alarming increase in cardiovascular complications, including myocardial infarction and the appearance of abnormal distribution of body fat seen as lipodystrophy. One key element in the development of ischemic coronary artery disease is the presence of circulating and tissue-fixed modified low density lipoprotein (mLDL) that contributes to the initiation and progression of arterial lesions and to the formation of foam cells. Even though not completely elucidated, the most likely mechanism involves mLDL in the inflammatory response and the induction of a specific immune response against mLDL. Circulating antibodies against mLDL can serve as an indirect marker of the presence of circulating and vessel-fixed mLDL. In the present study, we measured antibodies to mLDL and correlated them with immune status (i.e., number of CD4+ T cells) in 59 HIV patients and with the clinical manifestation of lipodystrophy in 10 patients. We observed a significant reduction in anti-mLDL antibody levels related both to lipodystrophy and to an immunocompromised state in HIV patients. We speculate that these antibodies may explain in part the rapid development of ischemic coronary artery disease in some patients.

Assessment of the progressive nature of cell damage in the pilocarpine model of epilepsy

Pilocarpine-induced (320 mg/kg, ip) status epilepticus (SE) in adult (2-3 months) male Wistar rats results in extensive neuronal damage in limbic structures. Here we investigated whether the induction of a second SE (N = 6) would generate damage and cell loss similar to that seen after a first SE (N = 9). Counts of silver-stained (indicative of cell damage) cells, using the Gallyas argyrophil III method, revealed a markedly lower neuronal injury in animals submitted to re-induction of SE compared to rats exposed to a single episode of pilocarpine-induced SE. This effect could be explained as follows: 1) the first SE removes the vulnerable cells, leaving behind resistant cells that are not affected by the second SE; 2) the first SE confers increased resistance to the remaining cells, analogous to the process of ischemic tolerance. Counting of Nissl-stained cells was performed to differentiate between these alternative mechanisms. Our data indicate that different neuronal populations react differently to SE induction. For some brain areas most, if not all, of the vulnerable cells are lost after an initial insult leaving only relatively resistant cells and little space for further damage or cell loss. For some other brain areas, in contrast, our data support the hypothesis that surviving cells might be modified by the initial insult which would confer a sort of excitotoxic tolerance. As a consequence of both mechanisms, subsequent insults after an initial insult result in very little damage regardless of their intensity.

Behavioral changes induced by cocaine in mice are modified by a hyperlipidic diet or recombinant leptin

The objective of the present study was to determine if the acute behavioral effects of cocaine acutely administered intraperitoneally (ip) at doses of 5, 10 and 20 mg/kg on white male CF1 mice, 90 days of age, would be influenced by leptin acutely administered ip (at doses of 5, 10 and 20 µg/kg) or by endogenous leptin production enhanced by a high-fat diet. The acute behavioral effects of cocaine were evaluated in open-field, elevated plus-maze and forced swimming tests. Results were compared between a group of 80 mice consuming a balanced diet and a high-fat diet, and a group of 80 mice fed a commercially available rodent chow formula (Ralston Purina) but receiving recombinant leptin (rLeptin) or saline ip. Both the high-fat-fed and rLeptin-treated mice showed decreased locomotion in the open-field test, spent more time in the open arms of the elevated plus-maze and showed less immobility time in the forced swimming test (F(1,68) = 7.834, P = 0.007). There was an interaction between diets and cocaine/saline treatments in locomotion (F(3,34) = 3.751, P = 0.020) and exploration (F(3,34) = 3.581, P = 0.024). These results suggest that anxiolytic effects and increased general activity were induced by leptin in cocaine-treated mice and that low leptin levels are associated with behavioral depression. Chronic changes in diet composition producing high leptin levels or rLeptin treatment may result in an altered response to cocaine in ethologic tests that measure degrees of anxiety and depression, which could be attributed to an antagonistic effect of leptin.

Determination of low tetanus or diphtheria antitoxin titers in sera by a toxin neutralization assay and a modified toxin-binding inhibition test

A method for the screening of tetanus and diphtheria antibodies in serum using anatoxin (inactivated toxin) instead of toxin was developed as an alternative to the in vivo toxin neutralization assay based on the toxin-binding inhibition test (TOBI test). In this study, the serum titers (values between 1.0 and 19.5 IU) measured by a modified TOBI test (Modi-TOBI test) and toxin neutralization assays were correlated (P < 0.0001). Titers of tetanus or diphtheria antibodies were evaluated in serum samples from guinea pigs immunized with tetanus toxoid, diphtheria-tetanus or triple vaccine. For the Modi-TOBI test, after blocking the microtiter plates, standard tetanus or diphtheria antitoxin and different concentrations of guinea pig sera were incubated with the respective anatoxin. Twelve hours later, these samples were transferred to a plate previously coated with tetanus or diphtheria antitoxin to bind the remaining anatoxin. The anatoxin was then detected using a peroxidase-labeled tetanus or diphtheria antitoxin. Serum titers were calculated using a linear regression plot of the results for the corresponding standard antitoxin. For the toxin neutralization assay, L+/10/50 doses of either toxin combined with different concentrations of serum samples were inoculated into mice for anti-tetanus detection, or in guinea pigs for anti-diphtheria detection. Both assays were suitable for determining wide ranges of antitoxin levels. The linear regression plots showed high correlation coefficients for tetanus (r² = 0.95, P < 0.0001) and for diphtheria (r² = 0.93, P < 0.0001) between the in vitro and the in vivo assays. The standardized method is appropriate for evaluating titers of neutralizing antibodies, thus permitting the in vitro control of serum antitoxin levels.

Comparison of the diagnosis of malaria by microscopy, immunochromatography and PCR in endemic areas of Venezuela

Whole blood samples (N = 295) were obtained from different locations in Amazonas and Sucre States, in Venezuela. Malaria was diagnosed by microscopy, OptiMAL™ and polymerase chain reaction (PCR), with Plasmodium vivax, P. falciparum, and P. malariae being detected when possible. We identified 93 infections, 66 of which were caused by P. vivax, 26 by P. falciparum, and 1 was a mixed infection. No infection caused by P. malariae was detected. The sensitivity and specificity of each diagnostic method were high: 95.7 and 97.9% for microscopy, 87.0 and 97.9% for OptiMAL, and 98.0 and 100% for PCR, respectively. Most samples (72.2%) showed more than 5000 parasites/µL blood. The sensitivity of the diagnosis by microscopy and OptiMAL decreased with lower parasitemia. All samples showing disagreement among the methods were reevaluated, but the first result was used for the calculations. Parasites were detected in the 6 false-negative samples by microscopy after the second examination. The mixed infection was only detected by PCR, while the other methods diagnosed it as P. falciparum (microscopy) or P. vivax (OptiMAL) infection. Most of the false results obtained with the OptiMAL strip were related to the P. falciparum-specific band, including 3 species misdiagnoses, which could be related to the test itself or to genetic variation of the Venezuelan strains. The use of the microscopic method for malaria detection is recommended for its low cost but is very difficult to implement in large scale, population-based studies; thus, we report here more efficient methods suitable for this purpose.

The modified 2VO ischemia protocol causes cognitive impairment similar to that induced by the standard method, but with a better survival rate

Permanent bilateral occlusion of the common carotid arteries (2VO) in the rat has been established as a valid experimental model to investigate the effects of chronic cerebral hypoperfusion on cognitive function and neurodegenerative processes. Our aim was to compare the cognitive and morphological outcomes following the standard 2VO procedure, in which there is concomitant artery ligation, with those of a modified protocol, with a 1-week interval between artery occlusions to avoid an abrupt reduction of cerebral blood flow, as assessed by animal performance in the water maze and damage extension to the hippocampus and striatum. Male Wistar rats (N = 47) aged 3 months were subjected to chronic hypoperfusion by permanent bilateral ligation of the common carotid arteries using either the standard or the modified protocol, with the right carotid being the first to be occluded. Three months after the surgical procedure, rat performance in the water maze was assessed to investigate long-term effects on spatial learning and memory and their brains were processed in order to estimate hippocampal volume and striatal area. Both groups of hypoperfused rats showed deficits in reference (F(8,172) = 7.0951, P < 0.00001) and working spatial memory [2nd (F(2,44) = 7.6884, P < 0.001), 3rd (F(2,44) = 21.481, P < 0.00001) and 4th trials (F(2,44) = 28.620, P < 0.0001)]; however, no evidence of tissue atrophy was found in the brain structures studied. Despite similar behavioral and morphological outcomes, the rats submitted to the modified protocol showed a significant increase in survival rate, during the 3 months of the experiment (P < 0.02).