UV/Methyl Ethyl Ketone Peroxide Mediated Chlorophenol Congener Degradation in Basic Media

The accumulation of Ag by the marine herbivorous gastropod, Littorina littorea, has been studied in a series of exposures in which the metal was added in aqueous form and as nanoparticles, both in the presence and absence of contaminated algal food (Ulva lactuca). Significant accumulation occurred in the gill, kidney, stomach and visceral mass when the snail was exposed to aqueous Ag in the absence of food. Despite the consumption of U. lactuca that had been previously contaminated by Ag, no accumulation was observed from the dietary route. When added as nanoparticles, accumulation of Ag was only measured in the head and gill and only in the absence of contaminated food. These observations suggest that Ag is most bioavailable to L. littorina when in true solution and that Ag measured in external tissues of the snail following exposure to nanoparticles arises from some physical association that does not result in significant transfer of the metal to internal organs.     

Extended shelf-life of liquid fermentation derived talc formulations of Trichoderma harzianum with the addition of glycerol in the production medium

Liquid fermentation based formulations of Trichoderma spp. are vulnerable to desiccation compared to solid state fermentation based formulations. The effect of the addition of glycerol, an osmoticant in the production medium on the shelf-life of Trichoderma harzianum was studied. The addition of glycerol at 3, 6 or 9% reduced the water activity in the medium. Both in shaker culture and fermentor, the addition of glycerol in production medium prolonged the shelf-life of talc formulation. The addition of glycerol at 3 and 6% extended the shelf-life (with viability of >2 × 10⁶ CFU g⁻¹) to 7 and 12 months, respectively compared to 4-5 months shelf-life in formulations derived without the addition of glycerol. Regression analysis showed that there was positive correlation between colony forming unit (CFU) and water activity. In bio-efficacy tests, even after storage for 12 months, formulations derived with the addition of glycerol at 3 or 6% in the production medium could protect the tomato plants from Fusarium wilt incidence by 44-50%. The use of addition of osmoticants in production medium for enhancing the shelf-life of liquid fermentation derived fungal formulations is discussed.     

R2D2, a bridge between the initiation and effector steps of the Drosophila RNAi pathway

The RNA interference (RNAi) pathway is initiated by processing long double-stranded RNA into small interfering RNA (siRNA). The siRNA-generating enzyme was purified from Drosophila S2cells and consists of two stoichiometric subunits: Dicer-2(DCR-2) and a previously unknown protein that we named R2D2. R2D2 is homologous to the Caenorhabditis elegans RNAi protein RDE-4. Association with R2D2 does not affect the enzymatic activity of DCR-2. Rather, the DCR-2/R2D2 complex, but not DCR-2 alone, binds to siRNA and enhances sequence-specific messenger RNA degradation mediated by the RNA-initiated silencing complex (RISC). These results indicate that R2D2 bridges the initiation and effector steps of the Drosophila RNAi pathway by facilitating siRNA passage from Dicer to RISC.