Scavenging in the genus Natrix

Scavenging is reported as an unusual behaviour of snakes. However, it is likely more common than is supposed. Here I report the use of dead newts as prey source by water snakes of the genus Natrix at a dam in north-western Spain. Juveniles and adults viperine snakes (Natrix maura), and also an adult grass snake (Natrix natrix) were found feeding on newt carcasses

Relationship between two pathogens in an amphibian community that experienced mass mortalities

Because host species tend to harbor multiple parasitic species, coinfection in a host is com-mon. The chytrid fungusBatrachochytrium dendrobatidis(Bd) and the viruses in the genusRanavirus(Rv) are responsible for the decline of amphibians worldwide. Despite widegeographical co-occurrence and the serious conservation problem that coinfection withthese pathogens could represent, little is known about their possible synergistic interac-tions and effects in a host community. We investigated the occurrence and associationsbetween these two pathogens in an amphibian community after Rv-driven disease out-breaks were detected in four populations of the Iberian ribbed newt (Pleurodeles waltl)innorthwestern Spain. We collected tissue samples from amphibians and fish and estimatedBd and Rv infection loads by qPCR. A few months after the most recent mass mortalityevent, Rv infection parameters at the affected sites decreased significantly or were lowerthan such registered at the sites where no outbreaks were recorded. Both pathogens weresimultaneously present in almost all sites, but coinfection in a single host was rare. Ourfindings suggest that the co-occurrence of Bd and Rv does not predict adverse outcomes(e.g., enhanced susceptibility of hosts to one pathogen due to the presence or infectionintensity of the other) following an outbreak. Other variables (such as species identity orsite) were more important than infection with a pathogen in predicting the infection statusand severity of infection with the other pathogen. Our results highlight the importance ofhost-specific and environmental characteristics in the dynamics of infections, coinfectionpatterns, and their impacts.info:eu-repo/semantics/publishedVersio

Chemotaxis Study Using Optical Tweezers To Observe The Strength And Directionality Of Forces Of Leishmania Amazonensis

The displacements of a dielectric microspheres trapped by an optical tweezers (OT) can be used as a force transducer for mechanical measurements in life sciences. This system can measure forces on the 50 femto Newtons to 200 pico Newtons range, of the same order of magnitude of a typical forces induced by flagellar motion. The process in which living microorganisms search for food and run away from poison chemicals is known is chemotaxy. Optical tweezers can be used to obtain a better understanding of chemotaxy by observing the force response of the microorganism when placed in a gradient of attractors and or repelling chemicals. This report shows such observations for the protozoa Leishmania amazomenzis, responsible for the leishmaniasis, a serious tropical disease. We used a quadrant detector to monitor the movement of the protozoa for different chemicals gradient. This way we have been able to observe both the force strength and its directionality. The characterization of the chemotaxis of these parasites can help to understand the infection mechanics and improve the diagnosis and the treatments employed for this disease.6326Law, A.M.J., Aitken, M.D., Continuous-flow capillary assay for measuring bacterial chemotaxi (2005) Applied and Environmental Microbiology, 71 (6), pp. 3137-3143Khan, S., Jain, S., Reid, G.P., Trentham, D.R., The fast tumble signal in bacterial chemotaxis (2004) Biophysical Journal, 86 (6), pp. 4049-4058Neuman, K.C., Chadd, E.H., Liou, G.F., Bergman, K., Block, S.M., Characterization of photodamage to Escherichia coli in optical traps (1999) Biophysical Journal, 77 (5), pp. 2856-2863Who, World Health Organization, 2001Gontijo, B., Carvalho, M.L.R., Leishmaniose tegumentar Americana (2003) Revista da Sociedade Brasileira de Medicina Tropical, 36 (1), pp. 71-80Handman, E., Cell biology of Leishmania (2000) Advances in Parasitology, 44, pp. 1-39Rice, S.E., Purcell, T.J., Spudich, J.A., Building and using optical traps to study properties of molecular motors (2003) Biophotonics, PT B, 361, pp. 112-133Rohrbach, A., Stelzer, E.H.K., Three-dimensional position detection of optically trapped dielectric particles (2002) Journal of Applied Physics, 91 (8), pp. 5474-5488Gittes, F., Schmidt, C.F., Interference model for back-focal-plane displacement detection in optical tweezers (1998) Optics Letters, 23 (1), pp. 7-9Allersma, M.W., Gittes, F., DeCastro, M.J., Stewart, R.J., Schmidt, C.F., Two-dimensional tracking of ncd motiliry by back focal plane interferometry (1998) Biophysical Journal, 74 (2), pp. 1074-108

Hotel de negócios

Muito se tem falado de hotéis de negócios: oportunidades de investimentos, grupos estrangeiros alardeando sua experiência ou divulgando a intenção de desenvolver projetos desse segmento no Brasil. No entanto, esse ainda é um conceito novo para o país. O estudo aqui apresentado pretende esclarecer alguns parâmetros utilizados pela indústria hoteleira para classificar seus estabelecimentos dentro dessa categoria, bem como analisar a tendência que o mercado tem sinalizado tanto pelo lado da demanda quanto da oferta de quartos ou unidades habitacionais. Para tanto, são examinadas as informações disponíveis relativas a taxas de ocupação, distribuição dos hotéis por categoria e dos hóspedes pela motivação da viagem. Simultaneamente, procura-se traçar paralelos entre os movimentos anunciados pela política econômica brasileira e suas contribuições ao mercado hoteleiro. A partir dessas estatísticas, foram estabelecidas algumas hipóteses de evolução na oferta de hotéis voltados para o atendimento de viajantes a trabalho

A indústria de cimento

O presente artigo retoma a discussão sobre o setor cimenteiro, analisando seu comportamento a partir do último estudo publicado pelo BNDES nesta revista (GOMES et al, 1997), e trata dos aspectos relativos ao mercado de cimento Portland e às atividades empresariais correspondentes. A produção do setor, que no período compreendido entre 1986 e 1994 estava estabilizada, teve um significativo crescimento nos últimos quatro anos (1994/98), apresentando índice acumulado de 58,3%. O consumo per capita nacional, em 1998, atingiu o maior nível da história (cerca de 246 kg/hab./ano), situando-se bem próximo da média mundial (aproximadamente 271 kg/hab./ano). Nesse período, grande parte dos investimentos no setor foi direcionada a fusões e incorporação, mantendo-se, portanto, praticamente inalterada a capacidade instalada brasileira. A indústria de cimento desempenha papel relevante no desenvolvimento da infra-estrutura econômica e social de uma economia. Assim, num país de dimensões continentais como o Brasil, devem ser feitos esforços no sentido de manter a oferta não apenas nacional, mas também regional, com um patamar de preços e volume adequados às necessidades do mercado