Aspectos da morfologia na relação presa/predadores de três predadores Characiformes e suas principais presas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Uma descrição semiótica da metáfora no ensino de biologia: asserções sobre a célula animal

The main objective of this survey is describing signly the metaphor learning resource, with focus on biology education. Our teorical reference is the peircean semiotics, because it means solid heritage to code surveys implicated at science education, it led us to do an explanation about the main lines about that reference, addressed to researchers and lecturers interested in those reasonings. In the description yearned, another objectives appear: demonstrate diferences between metaphor/analogy and pragmatic analogy; to list metaphors, from cell representation analysis, and argue about principals diferences and probable cognitive consequences between the metaphor event in the visual representation and speech sentences. Therefore we analysed the animal cell of a high school first grade studying book – biology – cell biology – used by São Paulo and another state students. The findings demonstrate the undeniable importance of the metaphor as a learning tool in the biology education, and new findings about that, such as its limits in the concept elaboration, gnosiologic consequences for receptioning, the search needs for propositions– pictures between concept relations – in the science speech construction, and other results.

Ultrastructural analysis of the effect of mating delay on cell death in the ovaries of virgin honey bee (Apis mellifera L.) queens

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

Dynamics of cell and tissue genesis in the male reproductive system of ticks (Acari: Ixodidae) Amblyomma cajennese (Fabricius, 1787) and Amblyomma aureolatum (Pallas, 1772): a comparative analysis

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

Effect of Er:YAG laser and diamond drill on hybrid layer morphology obtained with self-etch adhesive: analysis by SEM and confocal laser scanning microscopy (CLSM)

This study aimed to evaluate the effect of Er:YAG (L) and diamond drills (DD) on: 1) the microshear bond strength (MPa); 2) the adhesive interface of two-step (TS) – Adper Scotchbond Multipurpose and one-step (OS) adhesives – Adper EasyOne, both from 3M ESPE. Material and methods: According to the preparation condition and adhesives, the samples were divided into four groups: DD_TS (control); DD_OS; L_TS and L_OS. 60 bovine incisors were randomly divided into experimental and groups: 40 for microshear bond strength (n = 10) and 20 for the adhesive interface morphology [6 to measure the thickness of the hybrid layer (HL) and length of tags (t) by CLSM (n = 3); 12 to the adhesive interface morphology by SEM (n = 3) and 2 to illustrate the effect of the instruments on dentine by SEM (n = 1)]. To conduct the microshear bond strength test, four cylinders (0.7 mm in diameter and 1 mm in height with area of adhesion of 0.38 mm) were constructed with resin composite (Filtek Z350 XT – 3M ESPE) on each dentin surface treated by either L or DD and after adhesives application. Microshear bond strength was performed in universal testing machine (EMIC 2000) with load cell of 500 kgf and a crosshead speed of 0.5 mm / min. Adhesive interface was characterized by thickness of hybrid layer (HL) and length of tags (t) in nm, with the aid of UTHSCSA ImageTool software. Results: Microshear bond strength values were: L_TS 34.10 ± 19.07, DD_TS 24.26 ± 9.35, L_OS 33.18 ± 12.46, DD_OS 21.24 ± 13.96. Two-way ANOVA resulted in statistically significant differences only for instruments (p = 0.047). Mann-Whitney identified the instruments which determined significant differences for HL thickness and tag length (t). Concerning to the adhesive types, these differences were only observed for (t). Conclusion: It can be concluded that 1) laser Er:YAG results in higher microshear bond strength values regardless of the adhesive system (TS and OS); 2) the tags did not significant affect the microshear bond strength; 3) the adhesive interface was affected by both the instruments for cavity preparation and the type of adhesive system used.

Structural and ultrastructural characteristics of interrenal gland and chromaffin cell of matrinxa, Brycon cephalus Gunther 1869 (Teleostei-Characidae)

This work presents the structure and ultrastructure of the interrenal gland and chromaffin cells, as well as the morphology of the head kidney of Brycon cephalus, the head kidney is composed of fused bilateral lobes located anterior to the swim bladder and ventrolateral to the spinal column, the parenchyma revealed lympho-haematopoietic tissue, melano-macrophage centres, interrenal gland and chromaffin cells. The interrenal gland consisted of cords or strands of cells grouped around the posterior cardinal vein and their branches. Chromaffin cells are found in small groups, closely associated with the interrenal gland and/or under the endothelium of the posterior cardinal vein. So far, the ultrastructural analysis has revealed only one interrenal cell type which contained abundant smooth endoplasmic reticulum and numerous mitochondria with tubulo-vesicular cristae, characteristic of steroid-producing cells. Two types of chromaffin cells were observed. The first type was characterized by the presence of vesicles with round, strongly electron-dense granules, which were eccentrically located, Such cells were interpreted as noradrenaline cells, Meanwhile, cells which contained smaller vesicles and electron-lucent granules, with a small halo separating the granule from the vesicular limiting membrane, were identified as adrenaline cells.

Crystallization and preliminary X-ray diffraction analysis of a eumenine mastoparan toxin: a new class of mast-cell degranulating peptide in the wasp venom

Mastoparans are tetradecapeptides found to be the major component of vespid venoms. A mastoparan toxin isolated from the venom of Anterhynchium flavomarginatum micado has been crystallized and X-ray diffraction data collected to 2.7 Angstrom resolution using a synchrotron-radiation source. Crystals were determined to belong to the space group P6(2)22 (P6(4)22). This is the first mastoparan to be crystallized and will provide further insights into the conformational significance of mastoparan toxins with respect to their potency and activity in G-protein regulation.

Design of a simple detection cell with extended optical path length for capillary electrophoresis: Application to multiresidue pesticide analysis

Absorbance detection in capillary electrophoresis (CE), offers an excellent mass sensitivity, but poor concentration detection limits owing to very small injection volumes (normally I to 10 nL). This aspect can be a limiting factor in the applicability of CE/UV to detect species at trace levels, particularly pesticide residues. In the present work, the optical path length of an on-column detection cell was increased through a proper connection of the column (75 mu m i.d.) to a capillary detection cell of 180 mu m optical path length in order to improve detectability. It is shown that the cell with an extended optical path length results in a significant gain in terms of signal to noise ratio. The effect of the increase in the optical path length has been evaluated for six pesticides, namely, carbendazim, thiabendazole, imazalil, procymidone triadimefon, and prochloraz. The resulting optical enhancement of the detection cell provided detection limits of ca. 0.3 mu g/mL for the studied compounds, thus enabling the residue analysis by CE/UV.

Analysis of a molten carbonate fuel cell: cogeneration to produce electricity and cold water

The fuel cell is an emerging cogeneration technology that has been applied successfully in Japan, the USA and some countries in the European Union. This system performs direct conversion of the chemical energy of the oxidation of hydrogen from fuel with atmospheric oxygen into direct current electricity and waste heat via an electrochemical process relying on the use of different electrolytes (phosphoric acid, molten carbonate and solid oxide, depending on operating temperature). This technology permits the recovery of waste heat, available from 200 degreesC up to 1000 degreesC depending on the electrolyte technology, which can be used in the production of steam, hot or cold water, or hot or cold air, depending on the associated recuperation equipment. In this paper, an energy, exergy and economic analysis of a fuel cell cogeneration system (FCCS) is presented. The FCCS is applied in a segment of the tertiary sector to show that it is a feasible alternative for rational decentralized energy production under Brazilian conditions. The technoeconomic analysis shows a global efficiency or fuel utilization efficiency of 86%. Analysis shows that the exergy losses in the fuel cell unit and the absorption refrigeration system are significant. Furthermore, the payback period estimated is about 3 and 5 years for investments in fuel cells of 1000 and 1500 US$/kW, respectively. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Fuel cell cogeneration system: a case of technoeconomic analysis

Fuel Cell is the emerging technology of cogeneration, and has been applied successfully in Japan, U.S.A. and some OECD countries. This system produces electric power by an electrolytic process, in which chemical substances (the most utilized substances are solid oxide, phosphoric acid and molten carbonate) absorb the components H-2 and O-2 of the combustion fuel. This technology allows the recovery of residual heat, available from 200 degrees C up to 1000 degrees C (depending on the electrochemical substance utilized), which can be used for the production of steam, hot or cold water, or hot or cold air, depending on the recuperation equipment used. This article presents some configurations of fuel cell cogeneration cycles and a study of the technical and economic feasibility for the installation of the cogeneration systems utilizing fuel cell, connected to an absorption refrigeration system for st building of the tertiary sector, subject to conditions in Brazil. (C) 1999 Elsevier B.V. Ltd. All rights reserved.

Thermodynamic analysis of direct steam reforming of ethanol in molten carbonate fuel cell

Fuel cell as molten carbonate fuel cell (MCFC) operates at high temperatures. Thus, cogeneration processes may be performed, generating heat for its own process or for other purposes of steam generation in the industry. The use of ethanol is one of the best options because this is a renewable and less environmentally offensive fuel, and is cheaper than oil-derived hydrocarbons, as in the case of Brazil. In that country, because of technical, environmental, and economic advantages, the use of ethanol by steam reforming process has been the most investigated process. The objective of this study is to show a thermodynamic analysis of steam reforming of ethanol, to determine the best thermodynamic conditions where the highest volumes of products are produced, making possible a higher production of energy, that is, a more efficient use of resources. To attain this objective, mass and energy balances were performed. Equilibrium constants and advance degrees were calculated to get the best thermodynamic conditions to attain higher reforming efficiency and, hence, higher electric efficiency, using the Nernst equation. The advance degree (according to Castellan 1986, Fundamentos da Fisica/Quimica, Editora LTC, Rio de Janeiro, p. 529, in Portuguese) is a coefficient that indicates the evolution of a reaction, achieving a maximum value when all the reactants' content is used of reforming increases when the operation temperature also increases and when the operation pressure decreases. However, at atmospheric pressure (1 atm), the advance degree tends to stabilize in temperatures above 700 degrees C; that is, the volume of supplemental production of reforming products is very small with respect to high use of energy resources necessary. The use of unused ethanol is also suggested for heating of reactants before reforming. The results show the behavior of MCFC. The current density, at the same tension, is higher at 700 degrees C than other studied temperatures such as 600 and 650 degrees C. This fact occurs due to smaller use of hydrogen at lower temperatures that varies between 46.8% and 58.9% in temperatures between 600 and 700 degrees C. The higher calculated current density is 280 mA/cm(2). The power density increases when the volume of ethanol to be used also increases due to higher production of hydrogen. The highest produced powers at 190 mA/cm(2) are 99.8, 109.8, and 113.7 mW/cm(2) for 873, 923, and 973 K, respectively. The thermodynamic efficiency has the objective to show the connection among operational conditions and energetic factors, which are some parameters that describe a process of internal steam reforming of ethanol.

Correlation between semen analysis by motile sperm organelle morphology examination and sperm DNA damage

Regression analysis of 538 semen samples demonstrated that percentages of normal nuclear sperm and all spermatozoa with abnormalities of nuclear form at high magnification had significant negative correlation with percentages of DNA fragmentation. on the other hand, there was a positive correlation between percentages of spermatozoa with nuclear vacuoles and those with DNA fragmentation. (Fertil Steril (R) 2010;94:1937-40. (C) 2010 by American Society for Reproductive Medicine.)

The effects of male age on sperm analysis by motile sperm organelle morphology examination (MSOME)

Background: This study aimed to investigate the influence of age on sperm quality, as analysed by motile sperm organelle morphology examination (MSOME).Methods: Semen samples were collected from 975 men undergoing evaluation or treatment for infertility. Sperm cells were evaluated at 8400x magnification using an inverted microscope equipped with Nomarski (differential interference contrast) optics. Two forms of spermatozoa were considered: normal spermatozoa and spermatozoa with large nuclear vacuoles (LNV, defined as vacuoles occupying > 50% of the sperm nuclear area). At least 200 spermatozoa per sample were evaluated, and the percentages of normal and LNV spermatozoa were determined. The subjects were divided into three groups according to age: Group I, less than or equal to 35 years; Group II, 36-40 years; and Group III, greater than or equal to 41 years.Results: There was no difference in the percentages of normal sperm between the two younger (I and II) groups (P > 0.05). The percentage of normal sperm in the older group (III) was significantly lower than that in the younger (I and II) groups (P < 0.05). There was no difference in the percentage of LNV spermatozoa between the younger (I and II) groups (P > 0.05). The percentage of LNV spermatozoa was significantly higher in the older group (III) than in the younger (I and II) groups (P < 0.05). Regression analysis demonstrated a significant decrease in the incidence of normal sperm with increasing age (P < 0.05; r = -0.10). However, there was a significant positive correlation between the percentage of spermatozoa with LNV and male age (P < 0.05, r = 0.10).Conclusion: The results demonstrated a consistent decline in semen quality, as reflected by morphological evaluation by MSOME, with increased age. Considering the relationship between nuclear vacuoles and DNA damage, these age-related changes predict that increased paternal age should be associated with unsuccessful or abnormal pregnancy as a consequence of fertilisation with damaged spermatozoa. Given that sperm nuclear vacuoles can be evaluated more precisely at high magnification, these results support the routine use of MSOME for ICSI as a criterion for semen analysis.

Effects of incubation temperature on muscle morphology and growth in the pacu (Piaractus mesopotamicus)

This study describes the influence of incubation temperature during initial development phase on the morphology and muscle growth characteristics in the pacu (Piaractus mesopotamicus). Pacu eggs were incubated at 25, 27, and 29 degreesC until hatching. After day 5, fish from each temperature were transferred to 5001 tanks. At hatching and after 5, 25, and 60 days, muscle samples were collected, some were frozen in liquid nitrogen and others fixed in 4% paraformaldehyde or 2.5% glutaraldehyde. These samples were used for morphological, histochemical, immunohistochemical, and morphometric analysis. At hatching, we observed a superficial monolayer of small diameter fibers, lying just beneath the skin surrounding several round cells. From day 5, we observed two distinct populations of muscle fibers distributed in two layers: (1) red-in a superficial region with aerobic activity, and following acid preincubation, high mATPase activity, and 2) white-with anaerobic activity, and following alkaline preincubation, high mATPase activity. Twenty-five days after hatching, an intermediate layer and cell proliferating zones could be seen in the dorsal fin muscle region, with intermediate characteristics. Throughout the experimental period, there was an increase in muscle mass due to new fiber recruitment in the cell proliferating zones and between the more differentiated fibers in red, intermediate, and white muscles. This was more obvious from day 25, and at 29 degreesC than at 25 and 27 degreesC. Fiber hypertrophy occurred from hatching to 60 days and was more evident from 5 to 25 days. The number of proliferating nuclei (PCNA-labelling) increased from hatching to 60 days, and was more obvious in the 29 degreesC group at 60 days. Our results show that at incubation temperatures of 25, 27 and 29 degreesC, hypertrophy was predominantly from hatching to 25 days, after that muscle growth by hyperplastic mechanism increased. The interaction of muscle hypertrophic and hyperplastic growth processes in the 29 degreesC group produced the largest fish at the end of the experiment. (C) 2004 Elsevier B.V. All rights reserved.