Nutrition and production of Helianthus annuus in a function of application of leaf silicon

Silicon (Si) is important as it increases plant tolerance to abiotic stresses. However, studies on in foliar fertilization are still scarce. The objective of this research was to evaluate the effect of foliar application of silicon on nutrition and production of Helianthus annuus. The study was carried with a completely randomized design, consisting of five doses of silicon (0; 0.84; 1.68; 2.52 and 3.36?mg L^?1) applied as silicate, with four replicates. Biometric evaluations and relative chlorophyll index (RCI) measurements were performed, being also observed the dry matter production and the silicon use efficiency by plants. The RCI is not affected by the foliar application of Si, while the height and leaf area increase by 8.3 and 25.4%, respectively. Foliar Si application up to the dose of 3.36?g L^?1 promotes linear increases in the dry matter production of shoots (32%), capitulum (19%) and the whole plant of sunflower (27%).     

AMMONIUM AND NITRATE IN SOIL AND RATOON SUGARCANE GROWN IN FUNCTION OF NITROGEN ON OXISOL

After harvest, sugarcane residues left on the soil surface can alter nitrogen (N) dynamics in the plant-soil system. In Oxisols, the nitrogen fertilizer applied had its effects on the levels of ammonium and nitrate in the soil, N concentration in the plant leaves, and on the growth and productivity of second ratoon plants. The N rates tested were of 0, 60, 120, 180, and 240 kg ha^?1. Each treatment was replicated four times. Four months after the experiment was started, ammonium and nitrate concentration in the soil, N levels in plant leaves, and plant growth were evaluated. Productivity was evaluated 11 months after the experiment was set. By increasing the content of mineral N in soil, plant growth variables reflected differences in the production of stems; however, it did not affect foliar N. The use of leaf analysis was not important to assess the nutritional status of nitrogen in the ratoon sugarcane. Nitrogen concentration in soil was affected by nitrogen fertilization, but not the N content in leaves. The rate of 138 kg N ha^?1enabled greater production of sugarcane stalks (140 t ha^?1).     

Osteolytic osteomyelitis associated with visceral leishmaniasis in a dog

A dog was examined with a history of weight loss and lameness of the left hind limb. A painful response to examination of the left hip joint, and lymphadenopathy were noted. Amastigote forms of Leishmania sp. were observed by cytology in samples from the popliteus lymph node, and anti-Leishmania sp. antibodies at a titer of 1:640 were detected in serum by indirect immunofluorescence. Radiological changes included osteolysis and a periosteal proliferative reaction in the left femoral greater trochanter. These changes were histologically characterized as an osteolytic granulomatous osteomyelitis associated with amastigotes within macrophages. Non-decalcified fragments of the periosteum were processed for immunohistochemistry, observed with prominent immunolabelling of amastigotes of Leishmania sp. within macrophages. The diagnosis was further confirmed by positive PCR for Leishmania sp., belonging to the Leishmania donovani complex.     

Functional traits and niche-based tree community assembly in an Amazonian forest

It is debated whether species-level differences in ecological strategy, which play a key role in much of coexistence theory, are important in structuring highly diverse communities. We examined the co-occurrence patterns of over 1100 tree species in a 25-hectare Amazonian forest plot in relation to field-measured functional traits. Using a null model approach, we show that co-occurring trees are often less ecologically similar than a niche-free (neutral) model predicts. Furthermore, we find evidence for processes that simultaneously drive convergence and divergence in key aspects of plant strategy, suggesting that at least two distinct niche-based processes are occurring. Our results show that strategy differentiation among species contributes to the maintenance of diversity in one of the most diverse tropical forests in the world.     

Occurrence of nematodes and anthelmintic management of ostrich farms from different Brazilian states: Libyostrongylus douglassii dominates mixed infections

Ostriches were imported to Brazil in the early 1990s without appropriate parasite control leading to a co-importation of parasites. Libyostrongylus douglassii, Libyostrongylus dentatus and Codiostomum struthionis are nematodes of the ostriches that have been reported on some Brazilian farms but no national survey has been performed. Moreover, little is known about anthelmintic usage to control these parasites in Brazil. Therefore, the occurrence of L. douglassii, L. dentatus and C. struthionis and the anthelmintic management practices in Brazilian ostrich farms were studied. A questionnaire about management practices and information on how to collect, store and ship feces to the laboratory were sent to 17 farms located in 9 Brazilian states. Received fecal samples were submitted to fecal cultivation and larval harvested. Infective larvae were morphologically analyzed and quantified. The majority of the farms (88%) used an anthelmintic at least once a year. Ivermectin was the principal anthelmintic. Libyostrongylus sp. and C. struthionis were found in samples from 76 and 18% of the examined farms, respectively. The presence of L. douglassii (61-97%) was higher than L. dentatus (3-57%) and C. struthionis (2-30%). At the farm level, both species of Libyostrongylus were always found together. Sheath tail measurements of their infective larvae were crucial for morphological diagnosis. L. dentatus and L. douglassii are well adapted to Brazil and are widely distributed in the Brazilian territory, proving that this mixed infection in Brazilian ostrich's farms is common.     

4-Acetoxydolastane diterpene from the Brazilian brown alga Canistrocarpus cervicornis as antileishmanial agent

Natural marine products have shown an interesting array of diverse and novel chemical structures with potent biological activities. Our study reports the antiproliferative assays of crude extracts, fraction and pure compound (4R,9S,14S)-4α-acetoxy-9β,14α-dihydroxydolast-1(15),7-diene (1) obtained from brown alga Canistrocarpus cervicornis showing the antileishmanial activity. We showed that 1 had a dose-dependent activity during 72 h of treatment, exhibiting IC(50) of 2.0 μg/mL, 12.0 μg/mL, and 4.0 μg/mL for promastigote, axenic amastigote and intracellular amastigote forms of Leishmania amazonensis, respectively. A cytotoxicity assay showed that the action of the isolated compound 1 was 93.0 times less toxic to the macrophage than to the protozoan. Additionally, compound 1 induced ultrastructural changes, including extensive mitochondrial damage; decrease in Rh123 fluorescence, suggesting interference with the mitochondrial membrane potential; and lipid peroxidation in parasite cells. The use of 1 from C. cervicornis against L. amazonensis parasites might be of great interest as a future alternative to the development of new antileishmanial drugs.     

Effect of elatol, isolated from red seaweed Laurencia dendroidea, on Leishmania amazonensis

In the present study, we investigated the antileishmanial activity of sesquiterpene elatol, the major constituent of the Brazilian red seaweed Laurencia dendroidea (Hudson) J.V. Lamouroux, against L. amazonensis. Elatol after 72 h of treatment, showed an IC(50) of 4.0 μM and 0.45 μM for promastigote and intracellular amastigote forms of L. amazonensis, respectively. By scanning and transmission electron microscopy, parasites treated with elatol revealed notable changes compared with control cells, including: pronounced swelling of the mitochondrion; appearance of concentric membrane structures inside the organelle; destabilization of the plasma membrane; and formation of membrane structures, apparently an extension of the endoplasmic reticulum, which is suggestive of an autophagic process. A cytotoxicity assay showed that the action of the isolated compound is more specific for protozoa, and it is not toxic to macrophages. Our studies indicated that elatol is a potent antiproliferative agent against promastigote and intracellular amastigote forms, and may have important advantages for the development of new anti-leishamanial chemotherapies.     

Additional Evidence of the Trypanocidal Action of (?)-Elatol on Amastigote Forms through the Involvement of Reactive Oxygen Species

Chagas’ disease, a vector-transmitted infectious disease, is caused by the protozoa parasite Trypanosoma cruzi. Drugs that are currently available for the treatment of this disease are unsatisfactory, making the search for new chemotherapeutic agents a priority. We recently described the trypanocidal action of (−)-elatol, extracted from the macroalga Laurencia dendroidea. However, nothing has been described about the mechanism of action of this compound on amastigotes that are involved in the chronic phase of Chagas’ disease. The goal of the present study was to evaluate the effect of (−)-elatol on the formation of superoxide anions (O₂^•−), DNA fragmentation, and autophagy in amastigotes of T. cruzi to elucidate the possible mechanism of the trypanocidal action of (−)-elatol. Treatment of the amastigotes with (−)-elatol increased the formation of O₂^•− at all concentrations of (−)-elatol assayed compared with untreated parasites. Increased fluorescence was observed in parasites treated with (−)-elatol, indicating DNA fragmentation and the formation of autophagic compartments. The results suggest that the trypanocidal action of (−)-elatol might involve the induction of the autophagic and apoptotic death pathways triggered by an imbalance of the parasite’s redox metabolism.