RESUMEN
Virus-induced gene silencing (VIGS) has been shown to be of great potential in plant reverse genetics. Advantages of VIGS over other approaches, such as T-DNA or transposon tagging, include the circumvention of plant transformation, methodological simplicity and robustness, and speedy results. These features make VIGS an attractive alternative instrument in functional genomics, even in a high throughput fashion. The system is already well established in Nicotiana benthamiana; however, efforts are being made to improve VIGS in other species, including monocots. Current research is focussed on unravelling the mechanisms of post-transcriptional gene silencing and VIGS, as well as on finding novel viral vectors in order to broaden the host species spectrum. We examined how VIGS has been used to assess gene functions in plants, including molecular mechanisms involved in the process, available methodological elements, such as vectors and inoculation procedures, and we looked for examples in which the system has been applied successfully to characterize gene function in plants.
Asunto(s)
Silenciador del Gen , Genes de Plantas/genética , Plantas Modificadas Genéticamente/genética , Nicotiana/genética , Transcripción Genética/genética , Virus de Plantas/genética , ADN Viral , Flores/genética , Vectores Genéticos , Genómica/métodos , Modelos Genéticos , Transformación GenéticaRESUMEN
Entamoeba chattoni frequently occurs as an intestinal infection in non-human primates. It has been isolated from both wild and captive animals. Morphologically this amoeba resembles E. histolytica. E. histolytica has also been isolated from non-human primates on a number of occasions but these isolations have been from captive animals. In recent years identification of E. histolytica has been enhanced by the introduction of iso-enzyme electrophoresis methods. This technology has been widely applied to amoebae isolated from humans from many parts of the world. Limited work using iso-enzyme electrophoresis on non-human primates in captivity has confirmed the earlier parasitological studies mentioned above as both E. histolytica and E. chattoni were isolated; furthermore zymodeme (strain or species based on the characteristic iso-enzyme electrophoretic pattern) analysis demonstrated that these two organisms could be readily distinguished by this method. The importance of establishing whether E. histolytica occurs in wild primates as a true zoonosis was emphasised by these studies, particularly from the point of view of potential disease transmission. A study of baboons (Papio ursinus) in South African game reserves has been initiated and three surveys have been conducted in the Kruger National Park; these baboons are considered to live in isolation from humans. Of the 210 isolations attempted 65-75% yielded E. chattoni while E. histolytica were cultured from the faeces of 1-3% of the baboons. Although the prevalence rates varied in each of the 3 study locations both species of amoeba were found in baboons from all of them. All the E. histolytica isolated thus far have been non-pathogenic zymodemes.(ABSTRACT TRUNCATED AT 250 WORDS)