Camptothecin (CPT) analogues and derivatives serve as a novel class of effective anticancer agents that exert their action against DNA topoisomerase I. This paper presents procedures for the rapid, high frequency regeneration of a camptothecin producing plant, Ophiorrhiza prostrata D. Don from leaf and internode explants via shoot organogenesis. The concentrations of plant growth regulators and explant types exhibited discrete roles in the efficacy of shoot induction. N6-benzyladenine (BA) was the most effective cytokinin for the induction of shoots. Murashige and Skoog (MS) medium with 8.87 µM BA and 2.46 µM indole-3-butyric acid (IBA) yielded the highest number of shoots from leaf and internode explants (76.0 and 90.8 shoots respectively). In the case of leaf explants, explants from the proximal end produced a higher number of shoots than those from the mid and distal end. Leaf and internode explants cultured on MS medium supplemented with α-naphthaleneacetic acid (NAA) and BA developed shoots, calli and roots. Calli subcultured onto medium supplemented with 8.87 µM BA and 2.46 µM IBA developed a mean of 20.1 shoots within 40 days. Excision and culture of internode and proximal leaf explants from the established cultures on MS basal medium significantly enhanced the number of shoots and yielded a mean of 18.3 and 13.7 shoots respectively within 40 days. Histological examination of leaf explants showed that the shoots were of sub-epidermal origin, confined to the sub-epidermal cells above the vascular traces. Shoots cultured on half-strength MS basal medium with 10.74 µM NAA and 2.32 µM Kn produced a mean of 48.2 roots per shoot. Direct transfer of rootless healthy shoots showed a 50% survival rate, whilst it was 100 percent in the case of in vitro rooted shoots.

O presente artigo questiona pressupostos sobre a distinção, comum na pesquisa de Internet, entre on-line e off-line. Várias pesquisas presumiram a "virtualidade", bem como uma forte divisão entre o on-line e o off-line como sendo um dado e um ponto de partida metodológico e analítico em pesquisa. Argumentamos que quando se aborda o uso de fato da Internet a partir de uma abordagem etnográfica, uma tal distinção se revela como um feito social altamente contingente: alguns atores empregam grandes habilidades para estabelecer uma distinção clara entre on-line e off-line em suas práticas de Internet; em outros, tal distinção não tem sentido, ou não é desejável, e tais distinções não são de fato estabelecidas. Utilizamos uma comparação entre cibercafés em Trinidad para demonstrar essa variabilidade e a ampla gama de diferentes relações on-line/off-line que são realmente observadas. Nós relacionamos esse material com a questão mais geral de se estabelecer "contextos" na pesquisa etnográfica.

This article interrogates assumptions about the on-line/off-line distinction in internet research. Much research has presumed "virtuality" and a strong division between the on-line and the off-line as a methodological and analytical given and starting point for research. We argue that when actual internet use is approached from an ethnographic perspective, this distinction turns out to be a highly contingent social accomplishment: some actors deploy great skill to establish a sharp on-line/off-line distinction in their internet practices; for others, it is meaningless or undesirable and the distinctions is not established in reality. A comparison of cybercafes in Trinidad is used to demonstrate this variability and the wide range of different on-line/off-line relationships that are in fact observed. We relate this material to the overall issue of establishing "contexts" in ethnographic research.