Orientation to light of juvenile and adult forms of melanic and albino populations of Biomphalaria glabrata (Say, 1818)

The process of light orientation by the snail Biomphalaria glabrata was studied using the selection technique in a Y-shaped aquarium under vertical or horizontal lighting schemes. Snail behavior was measured on the basis of distance (cm) covered per hour, direction of locomotion, and localization of the animal in the aquarium. A comparison was made of the action of the light stimulus on young and adult animals of albino populations from Santa Luzia (State of Minas Gerais, Brazil) and of a melanic population from Touros (State of Rio Grande do Norte) studied in groups and separately. All groups studied were attracted to light. Analysis of the data suggests the exitence of two orientation mechanisms with respect to light in these animals, i.e. high photo-orthokinesia and positive phototaxis, which influence their motion in the environment. This evidence permitted us to discuss features of the distribution dynamics of these mollusks in the environment and their relationship with the larval phases of Schistosoma mansoni, for which they act as intermediated hosts.

Orientation of the snail Biomphalaria straminea (Dunker, 1848) in response to light in a situation of selection

The behavioral response of Biomphalaria straminea to light was evaluted in terms of location of the snail in a Y-shaped aquarium in a situation of selection and of the rate (cm/hour) and direction of locomotion under homogeneous 9vertical) or differential (horizontal) lighting upon only one arm of the aquarium. The light source consisted of daylight fluorescent lamps with a spectrum close to that of natural light, with illumination varying from 28 to 350 lux. Analysis of the data showed that all animals, whether in groups or isolated, were attracted to light, although the time needed to approach the light source was 50% shorter for the former than for the latter. The rate of locomotion of B. straminea was 35% higher than observed in B. glabrata and 51% higher than that observed in B. tenagophila studied under similar conditions. The results are discussed in terms of social factors and geographical distribution of the three species.

Relative susceptibility of different stages of Rhodinius Prolixus to the entomopathogenic Hyphomycete Beauveria Bassiana

Laboratory bioassays were conducted to determine the relative suscepbility of eggs, 1st-, 3rd-, 5th- instar nymphs and adults of Rhodnius prolixus to one isolate of the entomopathogenic hyphomycete, Beauveria bassiana. Treatments consisted of directly spraying on insects of increasing doses of inoculum (3 x 10* to 3 x 10 (elevated to 5th potency) conidia per cm*). Mortality due to all doses of conidia was very high in the five tested stages of the target insect. Experiments on eggs demonstrated that the fungal isolate was able to kill eggs before they hatched. Both time-mortality and dose-mortality responses showed that the susceptibility of R. prolixus varied according to its stage of development and increased with age. As matter of fact, at the dose of 3 x 10* conidia per cm*, LD50 varied between 11.2 days in 1st-instar nymphs and 6.4 days in both 5th-instar nymphs and adults. Comparison of LD50 permitted to estimate that 1st-instar nymphs were about 700-fold less susceptible than the two oldest stages

Seasonality and relative abundance of Tabanidae (Diptera) captured on horses in the Pantanal, Brazil

Once a month, from June 1992 to May 1993, collections of tabanids on horse were conducted in the Nhecolândia, Pantanal State of Mato Grosso do Sul, Brazil. Tabanid catches using hand nets were conducted from sunrise to sunset at grassland and cerradão (dense savanna) habitats. A total of 3,442 tabanids from 21 species,12 genera, and 3 subfamilies were collected. Although species abundance varied seasonally depending on habitat, no habitat specificity was observed for the most abundant species. In the grassland, 1,625 (47.2%) tabanids belonging to 19 species were collected, while 1,817 (52.8%) tabanids from 17 species were caught in the cerradão. The number of tabanid species varied from 7 during winter (July/August) to 15 in the spring (October). Tabanus importunus (56%) was the most abundant species, followed by T. occidentalis (8.2%), and T. claripennis (8.1%). The tabanid peak, in October, coincided with the beginning of the rainy season. The population peak of most species, including those with higher vector potential, suggests that the rainy season can be considered as the period of potentially higher risk of mechanical transmission of pathogens by tabanids to horses in the region.

Variation of snail's abundance in two water bodies harboring strains of Pseudosuccinea columella resistant and susceptible to Fasciola hepatica miracidial infection, in Pinar del Río Province, Cuba

The abundance of freshwater snails in two rural sites of Pinar del Río, Cuba, which harbor Pseudosuccinea columella susceptible and resistant to miracidia of Fasciola hepatica was followed for one year. Susceptible snails were found in the most anthropic site (IPA) whereas the resistant population inhabited the most preserved one (El Azufre). Only two snail species coexisted with P. columella at IPA site (Physa cubensis and Tarebia granifera) while five species were found at El Azufre, including an endemic from that province (Hemisinus cubanianus). Populations of both resistant and susceptible snails showed stable densities throughout the year, although the susceptible strain attained higher abundance. The highest densities were observed in April-May 2004 for the susceptible population whereas the resistant strain attained its highest abundance in January 2004. No record of Fossaria cubensis was made and the thiarid T. granifera occurred only at low densities. One of the sampled sites (IPA) meets all the conditions for the first report of P. columella naturally infected with larvae of F. hepatica.

Effect of food on immature development, consumption rate, and relative growth rate of Toxorhynchites splendens (Diptera: Culicidae), a predator of container breeding mosquitoes

Food utilization by the larvae of Toxorhynchites splendens (Wiedemann) was studied in the laboratory by offering larvae of Aedes aegypti Linnaeus, Anopheles stephensi (Liston), and Culex quinquefasciatus (Say). Quantitative analyses of data indicated that immature development was significantly faster with increase in food availability. The regression analysis showed that the degrees of the relationship between immature duration (Id) and food availability were higher when offered early instars of prey (first and second instars) than late instars. Consumption rate (Cr) of the predator increased with increase in food availability and this relationship was highly significant when larvae of An. stephensi were offered as food. Consumption rate to food level decreased with increase in the age class of the prey. There was a significant negative correlation between Id and Cr. This aspect helps to increase population turnover of T. splendens in a shorter period when the prey is abundant. Conversely, the predator compensated the loss in daily food intake at low food level by extending Id thereby attains the minimum threshold pupal weight for adult emergence. There was an increase in the relative growth rate (RGR) of the predator when An. stephensi was offered as prey and this was related to the high protein content of the prey per body weight. There was a positive correlation between Cr and RGR. This adaptive life characteristic strategy of this predator is useful for mass-rearing for large scale field release programmes in the control of container breeding mosquitoes is discussed.

Anatomical studies of sibling species within neotropical lymnaeids, snail intermediate hosts of fascioliasis

Several anatomical parameters of the reproductive system have been used to distinguish Lymnaea cubensis from L. viatrix, the snail hosts of fascioliasis in South America and the Caribbean area. Three samples have been collected in the type localities of L. cubensis (Cuba), L. viatrix var. A ventricosa (Argentina, Río Negro Lower Valley), and L. viatrix var. B elongata (Peru, Lima), respectively. Only one parameter, the relative lengths of the penis sheath and preputium, showed significant differences between L. viatrix var. ventricosa and the two other taxa. None of the studied parameters separated L. cubensis from L. viatrix var. elongata.

Susceptibility and compatibility of Biomphalaria tenagophila from the Río de la Plata basin with Schistosoma mansoni from Brazil

Schistosomiasis has expanded to southern parts of Brazil. Between 2005-2007 the dispersion and the proliferation of Biomphalaria tenagophila was verified in the province of Corrientes near the Brazilian border. In order to study the possibility that schistosomiasis might spread into the basins of the Paraná and Uruguay Rivers, 440 B. tenagophila collected from 10 populations groups were experimentally exposed to infection with Schistosoma mansoni of the SJ2 strain. Snails from five localities were susceptible. Frandsen's index (TCP/100) shows that those snails from Mirungá (11%), Aguacerito (2%) and Curupicay (2%) were Class I and not very compatible. Meanwhile, snails from Copra (6%) and Pay-Ubre (22%), in the Paraná River basin, were Class II and poorly compatible.

Galveston Orientation Amnesia Test (GOAT)

O trauma crânio-encefálico contuso (TCEC) é freqüentemente seguido pela amnésia pós-traumática (APT), caracterizada como um estado transitório de confusão e desorientação. Sua duração tem sido utilizada para quantificar a gravidade do TCEC e prever distúrbios nas funções cognitivas, assim como para antever as alterações na capacidade funcional das vítimas pós-trauma. O Galveston Orientation Amnesia Test (GOAT) é o primeiro instrumento sistematizado criado e o mais amplamente utilizado para avaliar a APT. Este artigo apresenta esse instrumento, as bases conceituais para seu desenvolvimento e a adaptação e validação do GOAT para cultura brasileira. Além disso, descreve sua aplicação e comenta as restrições do seu uso. Resultados de pesquisas realizadas em nosso meio contribuíram para as evidências sobre a validade do GOAT. Também apontaram os indicadores do momento pós-trauma em que o GOAT deve ser aplicado e destacaram as dificuldades no uso desse instrumento.

Transmisión del Mal de Río Cuarto virus por ninfas de primer y tercer estadio de Delphacodes kuscheli

Se comparó la capacidad de ninfas de primer y tercer estadío de Delphacodes kuscheli Fennah (Hemiptera: Delphacidae) para adquirir y posteriormente transmitir el Mal de Río Cuarto virus (MRCV), bajo condiciones controladas. Ninfas I y III avirulíferas se alimentaron separadamente de plantas de trigo infectadas durante 48 horas, para luego ser colocadas en subgrupos de tres individuos sobre plantas de trigo sanas. Se realizaron transmisiones seriales utilizando períodos de inoculación de 24 horas. Ambos estadií os lograron adquirir y transmitir el MRCV, pero se evidenció una mayor cantidad de subgrupos infectivos cuando la adquisición se efectuó como ninfas I, así como una disminución significativa en la duración del período de latencia del virus respecto de los insectos que adquirieron el MRCV durante el tercer estadio ninfal.

Metales pesados y toxicidad de aguas del Río Aconcagua en Chile

The toxicity of surface waters in a zone with mining activity in the Aconcagua River was determined through growth inhibition bioassays of Pseudokirchneriella subcapitata, and correlated with heavy metal concentrations. Results show that the waters near the discharge of the mining effluent displayed toxicity during all periods of study; the molybdenum and copper concentration exceeded the norms of water quality. The correlations between the concentrations of metals and the growth rate of P. subcapitata varied in the different periods of the study; inverse and significant correlations with copper stand out in some periods.

Laüe back-reflection method for crystallographic orientation of a martensitic Cu-Zn-Al single crystal of the monoclinic system

A martensitic single crystal Cu-23.95Zn-3.62(wt.%)Al alloy was obtained melting pure Cu, Zn and Al using Bridgman's method. The martensitic phase (monoclinic) can present up to 24 variants, and orienting the surface according to a certain plane is a very hard task. The single crystal was submitted to 8 tons of tension (stress) along the longitudinal direction to reduce the number of variants and facilitate the surface orientation according to the desired plane. This single crystal was oriented using the Laüe back-reflection method to give surfaces with the following oriented crystallographic planes: (010), (120) and (130). It was observed that the tension stress was applied along the [010] direction.

Daño oxidativo en la microalga Pseudokirchneriella subcapitata expuesta a aguas receptoras de un efluente minero en del Río Blanco (V Región, Chile)

In this investigation antioxidant response and toxicity of metals in receiving water effluent miner in the Blanco river in Pseudokirchneriella subcapitata was assessed. The catalase activity, lipid damage through Tbars, the growth rate of was determined. The result showed an inhibition of the growth rate of P. subcapitata which correlated with increased catalase activity and the lipid liperoxidation. These responses were correlated with the concentrations of copper and iron.

Estudos de biodegradação de óleo diesel por consórcio microbiano coletado em Porto Velho - RO, amazônia

The goal of this research was to evaluate the biodegradation of diesel by a microbial consortium collected in a region close to distributors of fuel. The experiments were monitored by SPME-GC-FID and SPME-GC-MS. The consortium showed a high potential for production of biosurfactants, presenting an emulsification index of 53%. The consortium degraded completely n-alkanes, while dimethylnaphtalene, hepthyl-cyclohexane and 2,6,10-trimethyl-undecane were partially degraded and pristane was not degraded. From this consortium five strains were isolated and identified as Acinetobacter baumannii. Based on this initial investigation this consortium appears to be effective for bioremediation in Porto Velho - RO region.

Transmisión experimental del virus del mal de Río Cuarto por Delphacodes kuscheli

Entre las enfermedades que afectan al cultivo de maíz (Zea mays) en Argentina, la producida por el virus del mal de Río Cuarto (MRCV) es la más importante. El MRCV pertenece a la familia Reoviridae, género Fijivirus, y su propagación en la naturaleza es realizada por Delphacodes kuscheli (Hemiptera: Delphacidae). La modalidad de transmisión para los miembros de este género de virus es persistente propagativa. Se estableció la necesidad de ajustar un sistema de transmisión eficiente del virus para estudios de caracterización, partiendo de poblaciones libres de virus criadas en laboratorio, para lo cual se ensayaron distintos períodos de adquisición, latencia e inoculación, evaluándose además un rango de hospedantes diferenciales. Se lograron obtener insectos libres de virus en cantidad suficiente para llevar a cabo los trabajos, mediante su cría en fitotrones y cámaras aclimatadas. La transmisión experimental del MRCV se efectuó exitosamente, bajo idénticas condiciones, empleando períodos de adquisición, latencia e inoculación de dos, 10 y uno día respectivamente para los cereales de grano fino y de dos, 10 y dos días para el maíz. Se infectaron de este modo las siguientes especies: maíz, cebada (Hordeum vulgare), avena (Avena sativa), trigo (Triticum aestivum), centeno (Secale cereale), grama rhodes (Chloris gayana) y alpiste (Phalaris canariensis). La detección del virus en las plantas inoculadas se efectuó mediante pruebas serológicas, análisis de dsRNA en electroforesis en gel de poliacrilamida (obteniéndose las 10 bandas típicas de los fijivirus) y microscopía electrónica, detectándose las partículas isométricas de entre 60 y 70 nm de diámetro.