Ecology of colonizing populations of the figfly Zaprionus indianus (Diptera, Drosophilidae) in Porto Alegre, Southern Brazil

Ecological parameters such as trophic niche overlap and niche breadth were computed from the frequency of all drosophilid species collected in 2001 and 2002, in the urban area of Porto Alegre city, Brazil. Independently of place, drosophilids community composition and components breeding or feeding sites, the highest frequencies of Zaprionus indianus (Gupta, 1970) were obtained during seasons with higher average temperatures, especially during summer. From a total of the 19,146 individuals of Z. indianus sampled, 80% were found in this season. The data of trophic niche breadth suggest a higher opportunism of adult flies in feeding substrate use, but the females are still selective in oviposition substrate choice. For the values of niche overlap, only for some species, did we find any correlation between these and species richness and/or number of resources, and the most of the correlation values considering breeding and feeding sites were positive. The colonization of Z. indianus in Porto Alegre could be leading to adjustments in the survival strategies of the resident species, but it is possible that many species have conditions for coexisting with the invader.

Cardiac raptor ablation impairs adaptive hypertrophy, alters metabolic gene expression, and causes heart failure in mice.

Background- Cardiac hypertrophy involves growth responses to a variety of stimuli triggered by increased workload. It is an independent risk factor for heart failure and sudden death. Mammalian target of rapamycin (mTOR) plays a key role in cellular growth responses by integrating growth factor and energy status signals. It is found in 2 structurally and functionally distinct multiprotein complexes called mTOR complex (mTORC) 1 and mTORC2. The role of each of these branches of mTOR signaling in the adult heart is currently unknown. Methods and Results- We generated mice with deficient myocardial mTORC1 activity by targeted ablation of raptor, which encodes an essential component of mTORC1, during adulthood. At 3 weeks after the deletion, atrial and brain natriuretic peptides and β-myosin heavy chain were strongly induced, multiple genes involved in the regulation of energy metabolism were altered, but cardiac function was normal. Function deteriorated rapidly afterward, resulting in dilated cardiomyopathy and high mortality within 6 weeks. Aortic banding-induced pathological overload resulted in severe dilated cardiomyopathy already at 1 week without a prior phase of adaptive hypertrophy. The mechanism involved a lack of adaptive cardiomyocyte growth via blunted protein synthesis capacity, as supported by reduced phosphorylation of ribosomal S6 kinase 1 and 4E-binding protein 1. In addition, reduced mitochondrial content, a shift in metabolic substrate use, and increased apoptosis and autophagy were observed. Conclusions- Our results demonstrate an essential function for mTORC1 in the heart under physiological and pathological conditions and are relevant for the understanding of disease states in which the insulin/insulin-like growth factor signaling axis is affected such as diabetes mellitus and heart failure or after cancer therapy.

Causes of legume rotation induced yield increases in cereals grown on West African soils

This study was conducted to investigate soil biological and chemical factors that give rise to cereal yield enhancing effects of legume rotations on sandy, nutrient poor West African soils. The aim was not only to gain more information on the role of legume residues and microorganisms in the soil nutrient cycle. But the study aimed at evaluating if differences in substrate qualities (e.g. root residues) cause changes in the microbial community structure due to specific and highly complex microbe-root-soil interactions. Site and system specific reactions of microorganisms towards rewetting, simulating the onset of rainy season, were observed. Higher respiration rates, higher amounts of microbial biomass carbon (Cmic) and nitrogen (Nmic) as well as higher ergosterol, muramic acid, glucosamine and adenylate concentrations were measured in CL soils of Koukombo and in both soils from Fada. The immediate increase in ATP concentrations after rewetting was likely caused by rehydration of microbial cells where N was not immobilized and, thus, available for plants facilitating their rapid development. Legume root residues led only to slightly better plant performances compared to the control, while the application of cereal roots reduced seedling growth. In contrast to sorghum seedlings, the microbial community did not react to the mineral treatment. Thus the energy supply in form of organic amendments increased microbial indices compared to mineral P application and the control. The results of basal respiration rates, Cmic and Corg levels indicate that the microbial community in the soil from Koukombo is less efficient in substrate use compared to microorganisms in the soil from Fada. However, the continuous carbon input by legume root residues might have contributed to these differences in soil fertility. With the 33P isotopic exchange method a low buffering capacity was detected in both soils irrespective of treatments. Calculated E values (E1min to E1min-1d and E1d-3m) indicated a slowly release of P due to root turnover while applied mineral P is taken up by plants or fixed to the soil. Due to the fact that sorghum growth reacted mainly to the application of mineral P and the microorganisms solely to the organic inputs, the combination of both amendments seems to be the best approach to a sustainable increase of crop production on many nutrient-poor, sandy West African soils. In a pot experiment, were CC and CL soils from Fada and Koukombo were adjusted to the same level of P and N concentrations, crop growth was significantly higher on CL soils, compared to the respective treatments on CC soils. Mycorrhizal infection of roots was increased and the number of nematodes, predominantly free living nematodes, was almost halfed on rotation soils. In conclusion, increased nutrient availability (especially P and N) through the introduction of legumes is not the only reason for the observed yield increasing effects. Soil biological factors seem to also play an important role. In a root chamber experiment the pH gradient along the root-soil-interface was measured at three times using an antimony microelectrode. For Fada soils, pH values were higher on CL than CC soils while the opposite was true for the Koukombo soils. Site-specific differences between Fada and Koukombo soils in N content and microbial community structures might have created varying crop performances leading to the contrasting pH findings. However, the mechanisms involved in this highly complex microbe-root-soil interaction remain unclear.

Os Répteis do Município de São Paulo: Diversidade e ecologia da fauna pretérita e atual

The reptile fauna in the municipality of São Paulo is well sampled due to intensive collection in the last 100 years. In the present work we provide a checklist of reptile species in São Paulo municipality based on preserved specimens in scientific collections. The reptile fauna was also characterized by three ecological parameters: habitat use, substrate use, and diet. We recorded a total of 97 reptile species (two turtles, one crocodilian, 19 lizards, seven amphisbaenians, and 68 snakes). Approximately 70% of the lizards and 40% of the snakes are typical of forest habitats of the Serra do Mar mountain range. Other squamates are typical of open formations that occur mainly on inland Cerrado habitats. All turtles and the crocodilian are associated to riparian habitats. Approximately 63% of the lizards are predominantly terrestrial, and the remaining species are arboreal. Most species of snakes are terrestrial (38%) or subterranean/criptozoic (25%) whereas a smaller proportion are arboreal (18%) or aquatic (9%). Lizards feed upon arthropods. Almost 50% of the snake species are specialized or feed mainly upon anuran amphibians. Other important items consumed by snakes are mammals (24%), lizards (18%), subterranean vertebrates (10%), and invertebrates (earthworms, mollusks and arthropods; 15%). A total of 51 reptile species have not been recorded for the last six years. Probably many of these species are extinct in the region due the intense local urbanization and habitat loss. The survey of species collected in São Paulo municipality and received in the Instituto Butantan in recent years allowed the identification of 10 lizards at least 42 snake species already occurring in the region. The high species richness of the original fauna seems related to the geographic location of the municipality, in a contact zone between forested areas of the Atlantic Forest (ombrophilous forest) and open formations (savannas, high-altitude grassland). Thus, the original habitat composition probably allowed sympatry among different species pools typical of both open and forested formations. The extant snake fauna recorded in the last three years indicates a higher loss of the species in open formations when compared to the forested areas.

Diversity, natural history, and geographic distribution of snakes in the Caatinga, Northeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evolução do hábito alimentar e utilização do substrato pelo gênero Philodryas Wagler, 1830

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

[Mitochondrial dysfunction during sepsis, impact and possible regulating role of hypoxia-inducible factor-1alpha]

There is a direct correlation between the development of the multiple organ dysfunction syndrome (MODS) and the elevated mortality associated with sepsis. The mechanisms responsible for MODS development are being studied, however, the main efforts regarding MODS evaluation have focused on oxygen delivery optimization and on the modulation of the characteristic inflammatory cascade of sepsis, all with negative results. Recent studies have shown that there is development of tissue acidosis, even when there are normal oxygen conditions and limited presence of tissue cellular necrosis or apoptosis, which would indicate that cellular energetic dysfunction may be a central element in MODS pathogenesis. Mitochondrias are the main source of cellular energy, central regulators of cell death and the main source for reactive oxygen species. Several mechanisms contribute to mitochondrial dysfunction during sepsis, that is blockage of pyruvate entry into the Krebs cycle, oxidative phosphorylation substrate use in other enzymatic complexes, enzymatic complex inhibition and membrane damage mediated by oxidative stress, and reduction in mitochondrial content. Hypoxia-inducible factor-1alpha (HIF-1alpha) is a nuclear transcription factor with a central role in the regulation of cellular oxygen homeostasis. Its induction under hypoxic conditions is associated to the expression of hundreds of genes that coordinate the optimization of cellular oxygen delivery and the cellular energy metabolism. HIF-1alpha can also be stabilized under normoxic condition during inflammation and this activation seems to be associated with a prominent pro-inflammatory profile, with lymphocytes dysfunction, and to a reduction in cellular oxygen consumption. Further studies should establish a role for HIF-1alpha as a therapeutic target.

Changes of dissolved organic matter compositions in artifical and natural seawater during Pseudovibrio growth experiment

To study the consumption of dissolved organic matter (DOM) by bacteria living in untra-oligotrophic artificial or natural seawater, we analyzed the composition of DOM before (timepoint t0, directly after inoculation) and after (timepoint t2, 3 weeks of incubation) growth of the bacteria using Fourier transform ion cyclotron mass spectrometry (ESI FT-ICR-MS). The oligotrophic natural seawater used originates from the South Pacific Gyre. Our data show that the bacteria were able to utilize a variety of different organic compounds. These compounds belong to different chemical compound groups and likely fuel the bacterial energy, carbon and nitrogen requirements under the ultra-oligotrophic conditions.

Factors and mechanisms controlling soil organic carbon turnover in subsoils of agricultural sites

Two-third of the terrestrial C is stored in soils, and more than 50% of soil organic C (SOC) is stored in subsoils from 30 – 100 cm. Hence, subsoil is important as a source or sink for CO2 in the global carbon cycle. Especially the stable organic carbon (OC) is stored in subsoil, as several studies have shown that subsoil OC is of a higher average age than topsoil OC. However, there is still a lack of knowledge regarding the mechanisms of C sequestration and C turnover in subsoil. Three main factors are discussed, which possibly reduce carbon turnover rates in subsoil: Resource limitation, changes in the microbial community, and changes in gas conditions. The experiments conducted in this study, which aimed to elucidate the importance of the mentioned factors, focused on two neighbouring arable sites, with depth profiles differing in SOC stocks: One Colluvic Cambisol (Cam) with high SOC contents (8-12 g kg-1) throughout the profile and one Haplic Luvisol (Luv) with low SOC contents (3-4 g kg-1) below 30 cm depth. The first experiment was designed to gain more knowledge regarding the microbial community and its influence on carbon sequestration in subsoil. Soil samples were taken at four different depths on the two sites. Microbial biomass C (MBC) was determined to identify depth gradients in relation to the natural C availability. Bacterial and fungal residues as well as ergosterol were determined to quantify changes in the in the microbial community composition. Multi-substrate-induced-respiration (MSIR) was used to identify shifts in functional diversity of the microbial community. The MSIR revealed that substrate use in subsoil differed significantly from that in topsoil and also differed highly between the two subsoils, indicating a strong influence of resource limitations on microbial substrate use. Amino sugar analysis and the ratio of ergosterol to microbial biomass C showed that fungal dominance decreased with depth. The results clearly demonstrated that microbial parameters changed with depth according to substrate availability. The second experiment was an incubation experiment using subsoil gas conditions with and without the addition of C4 plant residues. Soil samples were taken from topsoil and subsoil of the two sites. SOC losses during the incubation, were not influenced by the subsoil gas conditions. Plant-derived C losses were generally stronger in the Cam (7.5 mg g-1), especially at subsoil gas conditions, than in the Luv (7.0 mg g-1). Subsoil gas conditions had no general effects on microbial measures with and without plant residue addition. However, the contribution of plant-derived MBC to total MBC was significantly reduced at subsoil gas conditions. This lead to the conclusion that subsoil gas conditions alter the metabolism of microorganisms but not the degradation of added plant residues is general. The third experiment was a field experiment carried out for two years. Mesh bags containing original soil material and maize root residues (C4 plant) were buried at three different depths at the two sites. The recovery of the soilbags took place 12, 18, and 24 months after burial. We determined the effects of these treatments on SOC, density fractions, and MBC. The mean residence time for maize-derived C was similar at all depths and both sites (403 d). MBC increased to a similar extent (2.5 fold) from the initial value to maximum value. This increase relied largely on the added maize root residues. However, there were clear differences visible in terms of the substrate use efficiency, which decreased with depth and was lower in the Luv than in the Cam. Hence freshly added plant material is highly accessible to microorganisms in subsoil and therefore equally degraded at both sites and depths, but its metabolic use was determined by the legacy of soil properties. These findings provide strong evidence that resource availability from autochthonous SOM as well as from added plant residues have a strong influence on the microbial community and its use of different substrates. However, under all of the applied conditions there was no evidence that complex substrates, i.e. plant residues, were less degraded in subsoil than in topsoil.

Produção de lipases de Aspergillus niger e Aspergillus fumigatus através de fermentação em estado sólido, avaliação da especificidade do substrato e seu uso em reações de esterificação e alcoólise: evaluation of substrate specificity and use in esterification and alcoholysis reactions

Filamentous fungi were cultured under solid state fermentation of soybean residues to produce lipases. Enzymes produced by Aspergillus niger esterified oleic and butyric acids in the presence of ethanol, while enzymes produced by Aspergillus fumigatus demonstrated no esterification activity toward lauric acid. In case of A. niger, direct lyophilization of fermented bran led to higher esterification activity. The esterification of oleic acid by enzymes of A. fumigatus was neither influenced by pH adjustment nor by the extraction process. Conversions to ethyl esters were higher after pH adjustment with lyophilized liquid extract of A. niger.

THE USE OF AMPPD AS AN ALTERNATIVE SUBSTRATE FOR AP-MEDIATED DETECTION OF NONRADIOLABELED DNA PROBES IN EUCALYPTUS-SALIGNA

We present a non-radioactive alternative to Southern's (J. Mol. Biol. 98: 503-517, 1975) DNA-DNA hybridization technique. The use of AMPPD - Disodium 3-(4-Methoxyspiro {1,2-dioxetane-3,2'tricyclo[3.3.1.1(3,7)]decan}-4-yl)phyenyl phosphate as an alternative substrate for AP-mediated detection of digoxigenin-11 dUTP-labeled probes made possible the simple and nonhazardous reuse of blots. We used 0.8 % agarose gels containing 30 mug per lane of Eucalyptus saligna DNA, digested with Eco RI, electrophoresed and blotted on to nylon membranes (Hybond-N, Amersham, UK), using the Southern blotting procedure, and UV irradiated for one minute for DNA fixation. The hybridizations were carried out overnight with digoxigenin labeled random inserts of E. saligna DNA by using the Genius Kit (Boehringer Mannheim). Detection of the DNA-DNA hybrids was performed in the presence of 0.5% blocking agent and the substrates NBT/BCIP were replaced by 0.26 mM AMPPD in the final alkaline assay buffer (50 mul/cm2). After membrane incubation for five minutes at room temperature in a sealed plastic bag, the AMPPD solution was retrieved and stored at 4-degrees-C for reuse. A Kodak X-BRAF QA-S film was pressed firmly onto the bag containing the wet membrane, exposed for two to six hours and then developed. After use, the probes were stripped off and the blots reutilized, three times so far, with the same results.

Use of binding energy by an RNA enzyme for catalysis by positioning and substrate destabilization.

A fundamental catalytic principle for protein enzymes in the use of binding interactions away from the site of chemical transformation for catalysis. We have compared the binding and reactivity of a series of oligonucleotide substrates and products of the Tetrahymena ribozyme, which catalyzes a site-specific phosphodiester cleavage reaction: CCCUCUpA+G<-->CCCUCU-OH+GpA. The results suggest that this RNA enzyme, like protein enzymes, can utilize binding interactions to achieve substantial catalysis via entropic fixation and substrate destabilization. The stronger binding of the all-ribose oligonucleotide product compared to an analog with a terminal 3' deoxyribose residue gives an effective concentration of 2200 M for the 3' hydroxyl group, a value approaching those obtained with protein enzymes and suggesting the presence of a structurally well defined active site capable of precise positioning. The stabilization from tertiary binding interactions is 40-fold less for the oligonucleotide substrate than the oligonucleotide product, despite the presence of the reactive phosphoryl group in the substrate. This destabilization is accounted for by a model in which tertiary interactions away from the site of bond cleavage position the electron-deficient 3' bridging phosphoryl oxygen of the oligonucleotide substrate next to an electropositive Mg ion. As the phosphodiester bond breaks and this 3' oxygen atom develops a negative charge in the transition state, the weak interaction of the substrate with Mg2+ becomes strong. These strategies of "substrate destabilization" and "transition state stabilization" provide estimated rate enhancements of approximately 280- and approximately 60-fold, respectively. Analogous substrate destabilization by a metal ion or hydrogen bond donor may be used more generally by RNA and protein enzymes catalyzing reactions of phosphate esters.