Current Microscopy Strategies to Image Fungal Vesicles: From the Intracellular Trafficking and Secretion to the Inner Structure of Isolated Vesicles.

Extracellular vesicles (EVs) are nano-sized structures that play important roles in a variety of biological processes among members of the Eukaryota domain. They have been studied since the 1940s and a broader use of different microscopy techniques to image either isolated vesicles or vesicles within the intracellular milieu (trafficking) has been limited by their nanometric size, usually below the resolution limit of most standard light microscopes. The development of genetically encoded fluorescent proteins and fluorescent probes able to switch between "on" and "off" states, as well the improvement in computer-assisted microscopy, photon detector devices, illumination designs, and imaging strategies in the late Twentieth century, boosted the use of light microscopes to provide structural and functional information at the sub-diffraction resolution, taking advantage of a nondestructive analytical probe such light, and opening new possibilities in the study of life at the nanoscale. As well, traditional and novel electron microscopy techniques have been widely used in the characterization of subcellular compartments, either isolated or in situ, providing a comprehensive understanding of their functional role in many cellular processes. Here, we present basic aspects of some of these techniques that have already been applied and their potential application to the study of fungal vesicles.

Commercially Relevant Orthogonal Multi-Component Supramolecular Hydrogels for Programmed Cell Growth.

This study reports the ability of synthetically simple, commercially viable sugar-derived 1,3:2,4-dibenzylidenesorbitol-4',4"-diacylhydrazide (DBS-CONHNH2 ) to support cell growth. Simple mixing and orthogonal self-sorting can formulate heparin, agarose, and heparin-binding micelles into these gels-easily incorporating additional function. Interestingly, the components used in the gel formulation, direct the ability of cells to grow, meaning the chemical programming of these multi-component gels is directly translated to the biological systems in contact with them. This simple approach has potential for future development in regenerative medicine.

1,3:2,4-Dibenzylidene-D-sorbitol (DBS) and its derivatives--efficient, versatile and industrially-relevant low-molecular-weight gelators with over 100 years of history and a bright future.

Dibenzylidene-D-sorbitol (DBS) has been a well-known low-molecular-weight gelator of organic solvents for over 100 years. As such, it constitutes a very early example of a supramolecular gel--a research field which has recently developed into one of intense interest. The ability of DBS to self-assemble into sample-spanning networks in numerous solvents is predicated upon its 'butterfly-like' structure, whereby the benzylidene groups constitute the 'wings' and the sorbitol backbone the 'body'--the two parts representing the molecular recognition motifs underpinning its gelation mechanism, with the nature of solvent playing a key role in controlling the precise assembly mode. This gelator has found widespread applications in areas as diverse as personal care products and polymer nucleation/clarification, and has considerable potential in applications such as dental composites, energy technology and liquid crystalline materials. Some derivatives of DBS have also been reported which offer the potential to expand the scope and range of applications of this family of gelators and endow the nansocale network with additional functionality. This review aims to explain current trends in DBS research, and provide insight into how by combining a long history of application, with modern methods of derivatisation and analysis, the future for this family of gelators is bright, with an increasing number of high-tech applications, from environmental remediation to tissue engineering, being within reach.

Non-melanoma skin cancers: physio-pathology and role of lipid delivery systems in new chemotherapeutic treatments.

Non-melanoma carcinoma has high incidence rates and has two most common subtypes: basal cell carcinoma and squamous cell carcinoma. This type of carcinoma is usually not fatal; however, it can destroy sensory organs such as the nose, ears, and lips. The treatment of these injuries using non-invasive methods is thus strongly recommended. Some treatments for non-melanoma carcinoma are already well defined, such as surgery, cryosurgery, curettage and electrode section, and radiotherapy; however, these conventional treatments cause inflammation and scarring. In the non-surgical treatment of non-melanoma carcinoma, the topical administration of chemotherapeutic drugs contributes for an effective treatment with reduced side effects. However, the penetration of anticancer drugs in the deeper layers of the skin is required. Lipid delivery systems (liposomes, solid lipid nanoparticles, nanostructured lipid carriers) have been developed to overcome epidermal barrier of the skin and to allow the drugs to reach tumor cells. These lipid nanoparticles contribute to control the release profile of the loaded chemotherapeutic drugs, maintaining their stability and increasing death of tumor cells. In this review, the characteristics of non-melanoma carcinoma will be discussed, describing the main existing treatments, together with the contribution of lipid delivery systems as an innovative approach to increase the effectiveness of topical therapies for non-melanoma carcinomas.

Multi-component hybrid hydrogels - understanding the extent of orthogonal assembly and its impact on controlled release.

This paper reports self-assembled multi-component hybrid hydrogels including a range of nanoscale systems and characterizes the extent to which each component maintains its own unique functionality, demonstrating that multi-functionality can be achieved by simply mixing carefully-chosen constituents. Specifically, the individual components are: (i) pH-activated low-molecular-weight gelator (LMWG) 1,3;2,4-dibenzylidenesorbitol-4',4''-dicarboxylic acid (DBS-COOH), (ii) thermally-activated polymer gelator (PG) agarose, (iii) anionic biopolymer heparin, and (iv) cationic self-assembled multivalent (SAMul) micelles capable of binding heparin. The LMWG still self-assembles in the presence of PG agarose, is slightly modified on the nanoscale by heparin, but is totally disrupted by the micelles. However, if the SAMul micelles are bound to heparin, DBS-COOH self-assembly is largely unaffected. The LMWG endows hybrid materials with pH-responsive behavior, while the PG provides mechanical robustness. The rate of heparin release can be controlled through network density and composition, with the LMWG and PG behaving differently in this regard, while the presence of the heparin binder completely inhibits heparin release through complexation. This study demonstrates that a multi-component approach can yield exquisite control over self-assembled materials. We reason that controlling orthogonality in such systems will underpin further development of controlled release systems with biomedical applications.

Effect of buffer at nanoscale molecular recognition interfaces - electrostatic binding of biological polyanions.

We investigate the impact of an over-looked component on molecular recognition in water-buffer. The binding of a cationic dye to biological polyanion heparin is shown by isothermal calorimetry to depend on buffer (Tris-HCl > HEPES > PBS). The heparin binding of self-assembled multivalent (SAMul) cationic micelles is even more buffer dependent. Multivalent electrostatic molecular recognition is buffer dependent as a result of competitive interactions between the cationic binding interface and anions present in the buffer.

Emergence of highly-ordered hierarchical nanoscale aggregates on electrostatic binding of self-assembled multivalent (SAMul) cationic micelles with polyanionic heparin.

We report three surfactants, with cationic N,N-di-(3-aminopropyl)-N-methylamine (DAPMA) head groups and aliphatic chains connected via an amide linkage, and investigate their ability to self-assemble and bind polyanionic heparin - a process of potential clinical importance in coagulation control. Modifying the hydrophobic chain length tunes the self-assembly event, with C16-DAPMA having the lowest critical micelle concentration and also being the optimal heparin binder. Remarkably highly structured hierarchical nanoscale aggregates are formed on binding between the spherical cationic micelles and linear polyanionic heparin. C14-DAPMA and C16-DAPMA yield organized polycrystalline assemblies as observed by transmission electron microscopy (TEM), predicted in solution by mesoscale simulations and characterized by small-angle X-ray scattering (SAXS). This confirms that the micelles remain intact during the hierarchical assembly process and become packed in a face-centered cubic manner. The nanoscale assembly formed by C16-DAPMA showed the highest degree of order. Importantly, these studies indicate the impact of hydrophobic modification on self-assembly and heparin binding, demonstrate remarkably high stability of these self-assembled micelles even when forming strong electrostatic interactions with heparin, and provide structural insights into nanoscale hierarchical electrostatic assemblies.

Quantitative transportation assessment in curved canals prepared with an off-centered rectangular design system.

The purpose of this study was to assess the ability of an off-centered rectangular design system [ProTaper Next (PTN)] to maintain the original profile of the root canal anatomy. To this end, ProTaper Universal (PTU), Reciproc (R) and WaveOne (WO) systems were used as reference techniques for comparison. Forty clear resin blocks with simulated curved root canals were randomly assigned to 4 groups (n = 10) according to the instrumentation system used: PTN, PTU, R and WO. Color stereomicroscopic images of each block were taken before and after instrumentation. All image processing and data analysis were performed with an open source program (Fiji v.1.47n). Evaluation of canal transportation was obtained for two independent regions: straight and curved portions. Univariate analysis of variance and Tukey's Honestly Significant Difference test were performed, and a cut-off for significance was set at α = 5%. Instrumentation systems significantly influenced canal transportation (p = 0.000). Overall, R induced significantly lower canal transportation compared with WO, PTN and PTU (p = 0.000). The curved portion displayed superior canal transportation compared to the straight one (p = 0.000). The significance of the difference among instrumentation systems varied according to the canal level evaluated (p = 0.000). In its straight portion, R and WO exhibited significantly lower transportation than PTN; whereas in the curved portion, R produced the lowest deviation. PTU exhibited the highest canal transportation at both levels. It can be concluded that PTN produced less canal transportation than PTU and WO; however, R exhibited better centering ability than PTN.

Electrostatic binding of polyanions using self-assembled multivalent (SAMul) ligand displays - structure-activity effects on DNA/heparin binding.

This paper reports that modifying the ligands in self-assembled multivalent (SAMul) displays has an impact on apparent binding selectivity towards two nanoscale biological polyanions - heparin and DNA. For the nanostructures assayed here, spermidine ligands are optimal for heparin binding but spermine ligands are preferred for DNA. Probing subtle differences in such nanoscale binding interfaces is a significant challenge, and as such, several experimental binding assays - competition assays and isothermal calorimetry - are employed to confirm differences in affinity and provide thermodynamic insights. Given the dynamic nature and hierarchical binding processes involved in SAMul systems, we employed multiscale modelling to propose reasons for the origins of polyanion selectivity differences. The modelling results, when expressed in thermodynamic terms and compared with the experimental data, suggest that DNA is a shape-persistent polyanion, and selectivity originates only from ligand preferences, whereas heparin is more flexible and adaptive, and as such, actively reinforces ligand preferences. As such, this study suggests that inherent differences between polyanions may underpin subtle binding selectivity differences, and that even simple electrostatic interfaces such as these can have a degree of tunability, which has implications for biological control and regulation on the nanoscale.

In vitro effects of L-arginine and guanidino compounds on NTPDase1 and 5'-nucleotidase activities from rat brain synaptosomes.

Tissue accumulation of arginine (Arg), N-acetylarginine (NA), argininic acid (AA) and homoarginine (HA) occurs in hyperargininemia, an inborn error of the urea cycle. In the present study, we investigated the in vitro effects of Arg, NA, AA and HA on NTPDase1 and 5'-nucleotidase activities from synaptosomal cerebral cortex of rats. The results showed that Arg enhances NTPDase1 activity at the high concentrations tested (1.5 and 3.0mM) for both the ATP and ADP nucleotides. Activation was also observed with other guanidino compounds tested: NA, AA and HA activated ATP and ADP hydrolysis in all experiments at the concentration of 25 microM. Besides this, NA and AA activated ATP hydrolysis at a lower concentration (1 microM). In another set of experiments, we verified the effect of Arg on purified apyrase at pH 8.0 and 6.5 and observed an increase in the enzyme activity at all Arg concentrations tested (0.01-3.0mM). In contrast, Arg and the other guanidino compounds tested did not alter 5'-nucleotidase activity. These results suggest that changes in nucleotide hydrolysis may be involved in the brain dysfunction caused by hyperargininemia amongst other potential pathophysiological mechanisms involved in this condition.

ATP and ADP hydrolysis in the kidney and liver of fish, chickens and rats.

We investigated NTPDase-like activity [ecto-nucleoside triphosphate diphosphohydrolases (E-NTPDases)] in liver and kidney membrane from silver catfish (Rhamdia quelen), chicken (Gallus gallus) and rat (Rattus norvegicus) under different conditions and in the presence of several inhibitors. The cation concentration required for maximal activity was 0.5, 1.5 and 2.0 mM for fish, chicken and rat liver, respectively (with ATP and ADP as substrates). The maximal activity in the kidney was observed at calcium concentrations of 0.5, 2.0, 1.5 mM (ATP) and 0.5, 1.5, 1.0 (ADP) for fish, chickens and rats, respectively. The results showed that the pH optimum for all animals and for the two tissues was close to 8.0. The temperature chosen was 25 degrees C for fish and 36 degrees C for chicken and rat preparations. Ouabain had no effect on the NTPDase-like activity of fish, chickens or rats. NTPDase activity was decreased in the presence of lanthanum in the chicken (ADP) and rat (ATP and ADP) liver. In the kidney, lanthanum inhibited fish ATP and rat ATP and ADP (0.2 mM) hydrolysis. N-ethylmaleimide (NEM) had an inhibitory effect on the kidney of all species at the concentration of 3.0 mM (ADP). Orthovanadate only inhibited fish membrane NTPDase; azide only inhibited the preparation at high concentrations (10 mM) and fluoride inhibited it at 10 mM (fish and chicken) and 5 mM (rat). Trifluoperazine (0.05-0.2 mM) and suramin (0.03-0.3 mM) inhibited NTPDase at all concentrations tested. These results suggest that NTPDase-like activity shows a different behavior among the vertebrate species and tissues studied. Additionally, we propose that NTPDase1 is the main enzyme present in this preparation.

Caracterização dos indivíduos que realizaram prática/tentativa de autoextermínio em Itapecerica, Minas Gerais, Brasil / Características de las personas que realizaron la práctica o intento de auto extermínio em Itapecerica, Minas Gerais, Brasil / Characterization of the individuals who executed and/or attempted self-extermination in Itapecerica, Minas Gerais, Brazil

Objetivo: analisar as características dos indivíduos que realizaram a tentativa e/ ou efetivação do autoextermínio no município de Itapecerica, Minas Gerais, Brasil. Método: Pesquisa de natureza exploratória e descritiva. Foi realizada análise dos dados através das declarações de óbitos e notificações por suicídio, segundo o Sistema de Informação de Mortalidade (SIM) e o Sistema de Notificação e Agravos (SINAN) em que foram contempladas todas as variáveis, no período de 2013 a 2015. Resultados: a maioria dos óbitos ocorreram no sexo masculino, solteiros, de cor branca, na faixa etária entre 31-50 anos, sendo que o método mais utilizado foi o enforcamento. Em relação às tentativas, predominou-se o sexo feminino, de cor branca, faixa etária entre 31-50 anos e o método mais utilizado, foi o medicamento. Conclusão: Neste estudo, foi possível caracterizar as vítimas acometidas pelas tentativas e pelo ato consumado do autoextermínio, no entanto observou-se incompletude no preenchimento dos documentos analisados, principalmente em relação ao nível de escolaridade nas Declarações de Óbitos (DO’s) que constava como ‘ignorado’.

Objective: to analyze the characteristics of individuals who attempted and/or carried out self-extermination in the municipality ofItapecerica, Minas Gerais, Brazil. Method: Exploratory and descriptive research. Data analysis was performed through the deathand suicide reports, according to the Mortality Information System (MIS) and the SINAN (Diseases and Notification InformationSystem), in which all variables were considered, in the period from 2013 to 2015. Results: most deaths occurred in males, single,white, in the age group between 31-50 years, and the most commonly used method was hanging. Regarding the attempts, therewas predominance of females, white, age group between 31-50 years and the most used method was the medicine. Conclusion:This study allowed characterizing the victims affected by the attempts and consummation of the self-extermination, however,the analyzed documents were incomplete, mainly in relation to the level of schooling in the Declarations of Deaths (DO's), appearing as "Ignored".

Objetivo: analizar las características de las personas que realizaron el intento y/o la realización de auto-exterminio en el municipiode Itapecerica, MG. Método: Pesquisa de naturaleza exploratoria y descriptiva. Se realizó el análisis de datos de certificados dedefunción y notificaciones para el suicidio de acuerdo con el Sistema de Información de Mortalidad (SIM) y el Sistema deNotificación y Enfermedades (SINAN), donde se contemplan todas las variables. Resultados: La mayoría de las muertes ocurrieronen los hombres, solteros, de raza blanca, con edades comprendidas entre 31-50 años y el método más utilizado fue el colgante. Encuanto a los intentos, predominó el sexo femenino, raza blanca, con edades comprendidas entre 31-50 años y el método másutilizado fueron las medicinas. Conclusión: Como resultado de este estudio, fue posible caracterizar las vítimas acometidas portentativas e por ato consumado do autoextermínio, sin embargo fue observado incompletitud en los documentos analizados, principalmente en relación a el nível de enseñanza en los Certificados de Defúcion (CD’s) que figurava como “desconocido”.

Quantitative transportation assessment in curved canals prepared with an off-centered rectangular design system

Abstract The purpose of this study was to assess the ability of an off-centered rectangular design system [ProTaper Next (PTN)] to maintain the original profile of the root canal anatomy. To this end, ProTaper Universal (PTU), Reciproc (R) and WaveOne (WO) systems were used as reference techniques for comparison. Forty clear resin blocks with simulated curved root canals were randomly assigned to 4 groups (n = 10) according to the instrumentation system used: PTN, PTU, R and WO. Color stereomicroscopic images of each block were taken before and after instrumentation. All image processing and data analysis were performed with an open source program (Fiji v.1.47n). Evaluation of canal transportation was obtained for two independent regions: straight and curved portions. Univariate analysis of variance and Tukey's Honestly Significant Difference test were performed, and a cut-off for significance was set at α = 5%. Instrumentation systems significantly influenced canal transportation (p = 0.000). Overall, R induced significantly lower canal transportation compared with WO, PTN and PTU (p = 0.000). The curved portion displayed superior canal transportation compared to the straight one (p = 0.000). The significance of the difference among instrumentation systems varied according to the canal level evaluated (p = 0.000). In its straight portion, R and WO exhibited significantly lower transportation than PTN; whereas in the curved portion, R produced the lowest deviation. PTU exhibited the highest canal transportation at both levels. It can be concluded that PTN produced less canal transportation than PTU and WO; however, R exhibited better centering ability than PTN.

Quantitative transportation assessment in simulated curved canals after large apical preparations

Aim: To evaluate the ability of rotary (ProTaper Universal [PTU] and ProTaper Next [PTN]), reciprocating (Reciproc [R] and WaveOne [WO]) and adaptive (Twisted File Adaptive [TFA]) systems in maintaining the original canal profile in straight and curved parts after apical preparations up to size 40. Methods: Resin blocks with simulated curved canals were randomly assigned to five groups: PTU, PTN, R, WO and TFA. Images were captured from each block before and after canal preparation (n=10). Assessment of canal transportation was obtained for the straight and curved parts of the canal. ANOVA followed by Tukey's test was used (α = 5%). Results: Transportation values were increased at the curved part (P = .00). For both canal levels, TFA system induced the lowest mean of canal transportation followed by PTN, R, WO and PTU systems. At the straight portion, transportation for R and TFA systems were similar (P > .05), and these values were significantly lower than for WO, PTN and PTU (P = .00). At the curved portion, TFA resulted in less canal transportation, followed by PTN, R, WO and PTU systems (P = .00). Conclusions: TFA system produced less canal transportation than other systems tested during large apical preparations. (AU)

A avaliação da aprendizagem a distância: um estudo em representações sociais / Evaluation of distance learning: a study in social representations

Este estudo consiste em um relato de pesquisa sobre a avaliação da aprendizagem na modalidade a distância. Optou-se pelo suporte teórico-metodológico da Teoria das representações sociais explicitada por Moscovici (1978, 2003), Jodelet (2011) Abric (2001) e Sá (2002). Tem como objetivo identificar as representações sociais que os alunos de pedagogia a distância de uma universidade mineira estão construindo sobre a avaliação da aprendizagem. Os procedimentos de coleta de dados incluíram a aplicação de um questionário, com questões abertas e outras formuladas de acordo com a escala Likert; a técnica de associação livre de palavras, tratadas pelo software Evoc, que busca identificar nas representações sociais os elementos centrais e periféricos; e a realização de grupos focais. Participaram da pesquisa 212 alunos concluintes do curso de pedagogia a distância dos polos Triângulo (Araxá, Uberaba, Uberlândia); Espírito Santo (Cariacica, Colatina) e Regional Triângulo Mineiro (São Gotardo). De acordo com as análises realizadas, foi possível verificar que o projeto pedagógico do curso prevê uma avaliação processual e formativa. Os dados demonstram também que os alunos estão construindo diferentes representações sobre a avaliação a distância. Possivelmente, essas representações estão ancoradas em sentimento que denota ser a avaliação: “uma atividade de aprendizagem e conhecimento” (53%); “adequada que permite a realização de um curso a distância, porém exige dedicação e persistência” (20%); “complexa, rigorosa, tradicional, classificatória e que não mede conhecimentos” (27%).

This study consists of a research report on the evaluation of a distance learning course. We chose theoretical and methodological supports of Social Representation Theory explained by Moscovici (1978, 2003), Jodelet (2011), Abric (2001) and Sá (2002). Its objective is to identify the social representations that students of a distance learning course of University of Minas Gerais in Brazil are constructing on their evaluation of learning. The procedures for data collection included the use of a questionnaire with open questions and others formulated according to Likert scale; the technique of free association of words by Evoc software, which tries to identify social representations of central and peripheral elements, and the organization of focus groups. 212 graduating students of the pedagogy distance learning course participated in the research of the School of Education of the Minas Triangle (Araxá, Uberaba, Uberlândia), Espírito Santo (Cariacica, Colac) and Minas Triangle region (São Gotardo). According to the analysis performed, we found that the pedagogical project of the course provides a procedural and formative assessment. The data also show that students are constructing different representations of distance learning. Possibly these representations are anchored in the idea that the evaluation is “an activity of learning and knowledge” (53%), “an adequate activity for a distance course, but it requires dedication and persistence” (20%); “complex, rigorous, traditional, classificatory, but it does not measure knowledge” (27%).

Práticas docentes na Saúde: contribuições para uma reflexão a partir de Carl Rogers / Teaching practices in health area: contributions for reflexions from Carl Rogers / Prácticas docentes en la salud: contribuciones para una reflexión a partir de Carl Rogers

O trabalho do profissional da área da saúde depende da qualidade técnica e da interação pessoal que institui. Sua formação deve oferecer subsídios para que o egresso utilize características humanistas ao exercer sua prática profissional. Esta pesquisa, realizada com o aporte teórico de Carl Rogers, objetivou verificar a presença da concepção humanista nas práticas educativas dos professores da área da saúde de uma universidade em MG. Optou-se por uma abordagem qualitativa, com pesquisa bibliográfica e de campo. A coleta dos dados procedeu-se por meio de um questionário aplicado a 41 docentes de 05 cursos da saúde. De forma singela, verificou-se a presença de propostas humanistas: nos Projetos Pedagógicos dos cursos, que defendem um ensino centrado no estudante com professores facilitadores e aprendizagem significativa; e nas práticas pedagógicas docentes, delineadas na forma como o professor articula o conteúdo, avalia, planeja, interage com os alunos e utiliza as estratégias de ensino.

The work of professional in the health area depends on the technical quality and on establishing personal interaction. His/her training should provide subsidies so that egress from this area can make use of humanist features on exercising his/her professional practice. Supported by the theoretical contribution of Carl Rogers, we aim at verifying the presence of humanist conception in the educational practices of teachers of the health area in a university in MG. We opted for a qualitative approach, with bibliographical and field research. Data collection was conducted through a questionnaire administered to 41teachers from 5 health courses. We could observe the scarce presence of humanist proposals: the Pedagogical Projects of the courses, which advocate a student-centered teaching with faculty facilitators and meaningful learning. In teaching pedagogical practices outlined in the way teacher organize the content, how he/she evaluates, plans, interacts with students and makes use of teaching strategies.

El trabajo del profesional del área de salud depende de la calidad técnica y del establecimiento de interacción personal. La formación del egreso debe ofrecer subsidios para que utilice características humanistas al ejercer su práctica profesional. Esta investigación, realizada con o aporte teórico de Carl Rogers, tuvo el objetivo de verificar la presencia de la concepción humanista en las prácticas educativas de los profesores del área da salud de una universidad en Minas Gerais. Se optó por un abordaje cualitativo con investigación bibliográfica y de campo. La recolección de datos se realizó por medio de un cuestionario aplicado a 41 docentes de 05 cursos da salud. De forma simple se verificó la presencia de propuestas humanistas: en los Proyectos Pedagógicos de los cursos que defienden enseñanza centrada en el estudiante con profesores facilitadores y aprendizaje significativa; y en las prácticas pedagógicas docentes delineadas por la forma como el profesor articula el contenido, evalúa, planea, interactúa con los alumnos y utiliza las estrategias de enseñanza.

Effects of clomazone herbicide on hematological and some parameters of protein and carbohydrate metabolism of silver catfish Rhamdia quelen.

The effects of clomazone (0.5 and 1.0 mg/L) according to nominal concentrations used in paddy rice fields (0.4-0.7 mg/L) on protein and carbohydrate metabolism and haematological parameters were evaluated in silver catfish (Rhamdia quelen) after 12, 24, 48, 96 and 192 h of exposure with a recovery period of 96 and 192 h. Liver glycogen increased significantly (P<0.05) in all periods and concentrations tested. The maximum glycogen increase reaches 250% after 12h of exposure. Muscle glycogen reduced significantly after 24, 48, 96 and 192 h for both clomazone concentrations (P<0.05). Significantly elevated plasma glucose values (P<0.05) and variation in glucose in the liver and muscle of exposed fish were observed. Muscle lactate levels increased after 12, 24 and 48 h of clomazone exposure (22-67%), but reduced in the liver (P<0.05). Protein levels were enhanced in the liver and white muscle, except at 96 and 192 h of exposure, whereas it increased in the plasma in the period from 48 to 96 h (P<0.05). Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were significantly elevated in the plasma (P<0.05). In the liver, ALT increased after 24 h, while AST activity was enhanced only after 12 h of exposure. Hematocrit contents were reduced after 96 and 192 h of exposure. Most of the metabolic disorders observed did not persist after the recovery period, except for the liver AST and ALT activity. Clomazone concentrations used in this study appear safe to fish, Rhamdia quelen, because overall parameters can be recovered after 96 and 192 h in clean water. ALT and AST activity may be an early biomarker of clomazone toxicity.

Effect of glyphosate herbicide on acetylcholinesterase activity and metabolic and hematological parameters in piava (Leporinus obtusidens).

In this study, teleostean fish Leporinus obtusidens (piava) were exposed to different concentrations of Roundup, a glyphosate (acid equivalent) herbicide: 0 (control), 3, 6, 10, and 20 mg/L for 96 h (short-term). Acetylcholinesterase (AChE) activity was verified in brain and muscle tissues. Metabolic parameters in the liver and muscle (lactate, glycogen, glucose, protein, and ammonia), as well as some hematological parameters, were determined. Unexposed fish exhibited significantly higher brain AChE activity when compared to that of the muscle (P<0.05) (13.8+/-0.76 and 6.1+/-1.31 micromol/min/g protein, respectively). Results indicated that AChE activity significantly decreased in the brain of fish exposed to all glyphosate concentrations tested, but in the muscle this parameter was not altered. In addition, fish exposed to all glyphosate concentrations showed a significant increase in hepatic glycogen and glucose, but a significant reduction in muscle glycogen and glucose. Lactate and protein of fish exposed to all glyphosate concentrations presented a significant decrease in the liver, but did not change significantly in the muscle. Levels of ammonia in both tissues increase in fish at all glyphosate concentrations. Exposure to this herbicide produced a decrease in all hematological parameters tested. These results indicate that AChE activity as well as metabolic and hematological parameters may be good early indicators of herbicide contamination in L. obtusidens.

Metabolic responses of matrinxa (Brycon cephalus) to dietary protein level.

Effects of increasing dietary protein were studied in matrinxa, (Brycon cephalus), an omnivorous teleost from the Amazon Basin in Brazil. Four isocaloric diets were formulated to contain 20%, 27%, 34% and 41% of crude protein (CP). Plasma glucose levels were significantly increased while triacylglycerols were significantly reduced at 41% of CP. Free fatty acids were significantly reduced at each level of rising CP. Plasma amino acids and ammonium followed the dietary CP increase. Liver glycogen and amino acids were reduced; liver glucose and lactate were constant, and ammonium increased with the CP in diets. Muscle glycogen and pyruvate decreased, protein did not change, while lactate and free amino acids increased. Kidney glycogen proportionally rose with the increase of CP from 20-41%. Pyruvate and lactate augmented irregularly from 20-41% CP. A gluconeogenic profile was observed in the kidney; the liver worked as regulator of body glucose. Increase of dietary CP and decrease of carbohydrates pushed muscle and liver catabolism of fat and sugar stores to satisfy energetical demands. CP contents above 34% were not recommended for B. cephalus, if the carbohydrate does not compensate the metabolical demands.

Effects of the herbicides clomazone, quinclorac, and metsulfuron methyl on acetylcholinesterase activity in the silver catfish (Rhamdia quelen) (Heptapteridae).

Fingerlings of the silver catfish (Rhamdia quelen) were exposed to three herbicides widely used in rice culture in south Brazil: clomazone, quinclorac, and metsulfuron methyl. LC50 was determined and acetylcholinesterase (AChE) activity was evaluated in brain and muscle tissue of fish exposed to different herbicide concentrations after 96h (short term). The LC50 value (nominal concentration) was 7.32 mg/L for clomazone and 395 mg/L for quinclorac, but was not obtained for metsulfuron-methyl since all fingerlings survived the highest concentration of 1200 mg/L. Brain and muscle AChE activity in unexposed fish were 17.9 and 9.08 micromol/min/g protein, respectively. Clomazone significantly inhibited AChE activity in both tissues, achieving maximal inhibition of about 83% in brain and 89% in muscle tissue. In contrast, quinclorac and metsulfuron methyl caused increases in enzyme activity in the brain (98 and 179%, respectively) and inhibitions in muscle tissue (88 and 56%, respectively). This study demonstrated short-term effects of exposure to environmentally relevant concentrations of rice field herbicides on AChE activity in brain and muscle tissue of silver catfish.