Cellular imbalance in the levels of antioxidants and reactive oxygen species (ROS) is directly associated with a number of pathological states and results in programmed cell death or apoptosis. We demonstrate the use ofin vitro culturedSpodoptera frugiperda (sf9) insect cells as a model to study oxidative stress induced programmed cell death. Apoptosis ofin vitro cultured sf9 cells was induced by the exogenous treatment of H₂O₂ to cells growing in culture. The AD₅₀ (concentration of H₂O₂ inducing about 50% apoptotic response) varied with the duration of treatment, batch to batch variation of H₂O₂ and the physiological state of cells. At 24 h post-treatment with H₂O₂ AD₅₀ was about 475 Μm. Apoptosis could also be induced byin situ generation of H₂O₂ by the inhibition of catalase activity upon hydroxylamine treatment. Hydroxylamine acted synergistically with H₂O₂ with an AD₅₀ of 2.2 mM. DMSO, a free radical scavenger, inhibited H₂O₂-induced apoptosis thereby confirming the involvement of reactive oxygen species. Exposure of cells to UV radiation (312 nm) resulted in a dose-dependent induction of apoptosis. These results provide evidence on the novel use of insect cells as a model for oxidative stress-induced apoptosis.

Host pathogen interaction results in a variety of responses, which include phagocytosis of the pathogen, release of cytokines, secretion of toxins, as well as production of reactive oxygen species (ROS). Recent studies have shown that many pathogens exert control on the processes that regulate apoptosis in the host. The induction of apoptosis upon infection results from a complex interaction of parasite proteins with cellular host proteins. Abrogation of host cell apoptosis is often beneficial for the pathogen and results in a successful host invasion. However, in some cases, it has been shown that induction of apoptosis in the infected cells significantly imparts protection to the host from the pathogen. There is a strong correlation between apoptosis and the host protein translation machinery: the pathogen makes all possible efforts to modify this process so as to inhibit cell suicide and ensure that it can survive and, in some cases, establish latent infection. This review discusses the significance of various pathways/steps during virus-mediated modulation of host cell apoptosis.

Selaginella bryopteris is a lithophyte with remarkable ressurection capabilities. It is full of medicinal properties, hence also known as ‘Sanjeevani’ (one that infuses life). For lack of credible scientific evidence the plant is not in active use as a medicinal herb. We provide scientific evidence for whyS. bryopteris is known as ‘Sanjeevani’.

The aqueous extract ofS. bryopteris possesses growth-promoting activity as well as protective action against stress-induced cell death in a number of experimental cell systems including mammalian cells. Treatment of the cells in culture with 10% aqueous extract enhanced cell growth by about 41% in Sf9 cells and 78% in mammalian cells. Pre-treatment of cells with the Selaginella extract (SE) (1-2x5%) protected against oxidative stress (H2O2)-induced cell death. The killing potential of ultra violet (UV) was also significantly reduced when the cells were pre-treated with SE for 1 h. Thermal radiation suppressed cell growth by about 50%. Pre-treatment of cells with SE for 1 h afforded complete protection against heat-induced growth suppression. SE may possess anti-stress and antioxidant activities that could be responsible for the observed effects. Chemical analysis shows that SE contains hexoses and proteins. Taken together,S. bryopteris extract may help in stress-induced complications including those due to heat shock.