Natural vertical transmission by Stegomyia albopicta as dengue vector in Brazil.

The mosquito Stegomyia albopicta is among the most important arbovirus vectors in the world, particularly for Dengue viruses. Their natural history suggests that biologically these viruses are highly adapted to their mosquito hosts and they were most likely mosquito viruses prior to becoming adapted to lower primates and humans. As well as being maintained by transmission among susceptible humans, Dengue viruses may also be maintained by vertical transmission in mosquitoes during inter-epidemic periods. The larvae and mosquitoes of Stegomyia albopicta were used to identify the vertical transmission of the dengue virus in nature and to confirm the vectorial capacity concerning the Dengue virus type 2 infection. The minimum infection rate concerning S. albopicta infection with the Dengue virus was 1:36.45. In Brazil this was the first time that high minimum infection rates of vertical transmission of S. albopicta were detected in this species.

Natural vertical transmission by Stegomyia albopicta as dengue vector in Brazil / Transmissão vertical natural de Stegomyia albopicta como vetor de dengue no Brasil

The mosquito Stegomyia albopicta is among the most important arbovirus vectors in the world, particularly for Dengue viruses. Their natural history suggests that biologically these viruses are highly adapted to their mosquito hosts and they were most likely mosquito viruses prior to becoming adapted to lower primates and humans. As well as being maintained by transmission among susceptible humans, Dengue viruses may also be maintained by vertical transmission in mosquitoes during inter-epidemic periods. The larvae and mosquitoes of Stegomyia albopicta were used to identify the vertical transmission of the dengue virus in nature and to confirm the vectorial capacity concerning the Dengue virus type 2 infection. The minimum infection rate concerning S. albopicta infection with the Dengue virus was 1:36.45. In Brazil this was the first time that high minimum infection rates of vertical transmission of S. albopicta were detected in this species.

O mosquito Stegomyia albopicta está dentre os mais importantes vetores de arbovírus do mundo, particularmente para o Dengue virus. A história natural sugere que biologicamente esses vírus são altamente adaptados aos seus mosquitos vetores e foram, provavelmente, os vírus que infectavam mosquitos antes de se tornarem adaptados a primatas não humanos e humanos. Além de serem mantidos entre os homens susceptíveis, os Dengue viruses podem também ser mantidos pela transmissão vertical em mosquitos durante os períodos interepidêmicos. As larvas e mosquitos da espécie Stegomyia albopicta foram utilizados para a identificação da transmissão vertical do vírus dengue na natureza e para confirmar a capacidade vetorial em relação à infecção pelo DENV-2 infection. A taxa mínima de infecção em relação à infecção do S. albopicta com o Dengue virus foi de 1:36,45. No Brasil, esta é a primeira vez que altas taxas de infecção mínima da transmissão vertical de S. albopicta foram detectadas nessa espécie.

Azimuthal anchoring energy at the interface between a nematic liquid crystal and a PTFE substrate.

The azimuthal anchoring energy of the nematic liquid crystal 4-pentyl-4'-cyanobiphenil (5CB) on a poly(tetrafluoroethylene) (teflon, PTFE) film is measured for the first time. The PTFE film is deposed using the Wittmann and Smith technique which consists on rubbing a bar of this polymer against a glass substrate at a controlled temperature and pressure. Measurements of the azimuthal anchoring energy are made with a reflectometric technique which provides high accuracy and sensitivity. The dependence of the azimuthal anchoring energy on temperature and on the rubbing pressure is investigated. The extrapolation length remains virtually constant in the whole temperature range of the nematic phase except for an increase of 25% close to the clearing temperature. The azimuthal anchoring energy is somewhat strong and increases with increasing the deposition pressure of PTFE. The observation of a relevant pre-transitional anisotropy of the reflection coefficients in the isotropic phase proves that the surface interactions favor an excess of orientational order. Ageing of the anchoring energy and gliding of the easy axis are experimentally observed. Both these phenomena suggest the presence of an anisotropic adsorbed layer of nematic molecules on the PTFE film.