Imaging the Electrocyte of Torpedo Marmorata by Scanning Force Microscopy

Scanning force microscopy (SFM) and scanning electron microscopy (SEM) were used to examine the tissue structure of the electric organ of Torpedo marmorata in air and in liquid after applying fracturing and cryosectioning techniques and chemical fixation. The electric organ is organized in columns of stacked electrocytes, arranged in a honeycomb pattern. The columns were cut along a plane normal to the cell stack and thin sections were transferred to polylysine coated glass coverslips. The polarity of the electrocytes was made apparent by immunofluorescence microscopy directed to different domains of the acetylcholine receptor (AChR), thus revealing the innervated face of the cell. SFM and SEM both showed cell surfaces to be overlaid by a network of collagen fibers by their characteristic banding pattern with about 64 nm periodicity and about 2.5 nm corrugation amplitude. In liquid, significantly lower structural resolution was achieved by SFM, probably due to sample elasticity

Análise de viabilidade econômica de um sistema de produção modal de eucalipto para lenha na região de Itapeva, SP.

bitstream/item/141820/1/Comunicado-Tecnico-365-2015.pd

Potential reduction of environmental impacts of ethanol production by the adoption of the "environmental protocol of the sugarenergy sector"

Brazil is the largest producer of ethanol derived from sugarcane in the world. The state of São Paulo, located in the southeastern region of the country accounts for 51% of national production and 16% of world production of ethanol. São Paulo was a pioneer in establishing an Environmental Protocol in 2006, which prohibited the burn of sugarcane straw before manual harvesting. In the season 2013/2014, seven million hectares of sugarcane were no longer harvested with use of fire, avoiding the emission of 26.7 million tons of pollutants and 4.4 million tons of greenhouse gases (GHG). In addition to reducing the emission of pollutants, it is expected that the mechanical harvesting promote the reduction of water consumption and the increase in cogeneration of electricity by the straw burn in the boilers at the mills. With the elimination of fire in the field, other conservation practices began to be used, such as the introduction of legumes crops during the reform of the plantation and the adoption of notill systems. The potential benefits of this set of practices are the reduction of synthetic nitrogen fertilizers application and the increase in carbon stocks and water reserve in soil. In this work, we evaluated the potential reduction of environmental impacts resulting from the introduction of these new practices in the production system of sugarcane and ethanol

Do fine root morphological and functional adaptations support regrowth success in a tropical forest restoration experiment?

In early stages of forest succession plants have a high nutrient demand, but it is still a matter of debate if regrowth success of pioneer species is related to plant functional traits favoring fast soil colonization and nutrient acquisition. In general, we would expect trade-offs between plant growth performance and fine root morphological properties in association with different plant life-history strategies. Hence, we hypothesized that fast growing plants should have a more efficient root system that allows them to outcompete slow-growing neighbors in a resource-limited environment. To test our hypothesis we monitored plant successional growth dynamics in a tropical lowland rainforest reforestation experiment conducted in southwest Costa Rica. We collected absorptive roots (<2mm diameter) from plant individuals (comprising 20 tree species and 11 plant families) with different growth dynamics (as indicated by measurements of stem diameter and height). For these samples we assessed a suite of fine root morphological traits, such as legume nodulation status, and furthermore quantified fine root nutrient concentration and phosphatase activities, as well as microbial biomass and phosphatase activity in soils in the close vicinity of fine roots. We found stark differences in fine root characteristics between the tree species investigated in this study, such that fast growing species exhibited relatively larger specific root length and higher turnover, whereas slow growing species tend to rely on mechanical resistance by increasing root tissue density and root life span. Our results suggest that the identified differences in the root trait spectrum between fast and slow growing species reflect plant functional adaptions to resource limitation, edaphic properties and soil microbial symbioses. Our findings further highlight the crucial need to foster our understanding of belowground root morphological and physiological traits during forest succession, especially so when aiming to restore forest ecosystem functioning in formerly intensified land-use systems

Anaerobic Treatment of Swine Wastewater in Semicontinuous Clayey Support Reactors

Three micronized clayey supports in laboratory-scale tank reactors under mesophilic conditions were studied. From the results obtained in a previous work, the temperature of θ = 25 °C was chosen. The start up and performance of these bioreactors, operating on swine wastewater feed, were also studied. The anaerobic treatment in a semicontinuous regime was carried out. Four stirred tank reactors were used, one of them containing suspended biomass for reference, while the rest contained various suspended micronized clay supports. The supports chosen were zeolite, esmectite, and saponite. The higher removal efficiency (about η COD 70% to 3.6 d HRT) was obtained when HRT increased in saponite and esmectite support reactors. Esmectite support showed the best anaerobic activity of microorganisms (μmax equal to 0.576 d–1). The reactor with zeolite support and the reference (non-support reactor) showed the worst yield in methane. The methane production model proposed by Chen and Hashimoto to achieve an optimum purifying performance was carried out. It accurately predicted the performance of the process and may be used in the design of treatment units

Central Nervous System Targets and Routes for SARS-CoV-2: Current Views and New Hypotheses

As the coronavirus disease 2019 (COVID-19) pandemic unfolds, neurological signs and symptoms reflect the involvement of targets beyond the primary lung effects. The etiological agent of COVID-19, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), exhibits neurotropism for central and peripheral nervous systems. Various infective mechanisms and paths can be exploited by the virus to reach the central nervous system, some of which bypass the blood-brain barrier; others alter its integrity. Numerous studies have established beyond doubt that the membrane-bound metalloprotease angiotensin-converting enzyme 2 (ACE2) performs the role of SARS-CoV-2 host-cell receptor. Histochemical studies and more recently transcriptomics of mRNA have dissected the cellular localization of the ACE2 enzyme in various tissues, including the central nervous system. Epithelial cells lining the nasal mucosae, the upper respiratory tract, and the oral cavity, bronchoalveolar cells type II in the pulmonary parenchyma, and intestinal enterocytes display ACE2 binding sites at their cell surfaces, making these epithelial mucosae the most likely viral entry points. Neuronal and glial cells and endothelial cells in the central nervous system also express ACE2. This short review analyzes the known entry points and routes followed by the SARS-CoV-2 to reach the central nervous system and postulates new hypothetical pathways stemming from the enterocytes lining the intestinal lumen.Fil: Barrantes, Francisco Jose. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentin