Synthesis and in vitro antiviral activities of 3′-fluoro (or chloro) and 2′,3′-difluoro 2′,3′-dideoxynucleoside analogs against hepatitis B and C viruses

Chronic infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) lead to serious liver diseases worldwide. Co-infection with HBV and HCV is very common and is associated with increased risk of liver pathogenesis, liver cancer, and liver failure. Several 5-substituted 3′-fluoro (or chloro) (1–4, 6, 7, 17–19) and 2′,3′-difluoro 2′,3′-dideoxynucleosides (15 and 16) were synthesized and evaluated for in vitro antiviral activities against duck hepatitis B virus (DHBV), human hepatitis B virus, and hepatitis C virus. Of these compounds 4, 7, 17, and 19 demonstrated moderate anti-HBV activity, and 2, 4, 7, 8, and 19 were weak inhibitors of HCV. Although 5-iodo derivative (7) was most inhibitory against HCV, it exhibited a reduction in cellular RNA levels in Huh-7 cells. The 5-hydroxymethyl-3′-fluoro-2′,3′-dideoxyuridine (4) and 1-(3-chloro-2,3-dideoxy-β-d-erythro-pentofuranosyl)-5-fluorouracil (19) provided the most inhibition of both viruses without cytotoxicity.     

Bioremediation through microbes: systems biology and metabolic engineering approach

Today, environmental pollution is a serious problem, and bioremediation can play an important role in cleaning contaminated sites. Remediation strategies, such as chemical and physical approaches, are not enough to mitigate pollution problems because of the continuous generation of novel recalcitrant pollutants due to anthropogenic activities. Bioremediation using microbes is an eco-friendly and socially acceptable alternative to conventional remediation approaches. Many microbes with a bioremediation potential have been isolated and characterized but, in many cases, cannot completely degrade the targeted pollutant or are ineffective in situations with mixed wastes. This review envisages advances in systems biology (SB), which enables the analysis of microbial behavior at a community level under different environmental stresses. By applying a SB approach, crucial preliminary information can be obtained for metabolic engineering (ME) of microbes for their enhanced bioremediation capabilities. This review also highlights the integrated SB and ME tools and techniques for bioremediation purposes.     

Chlorolepiota indica sp. nov.—A new species from India

A new species Chlorolepiota indica is reported from Patiala in Punjab, India. The fungus is characterized by convex brown pileus covered by concentrically arranged brown scales with yellow tinge around the umbo. The stipe of the fruiting body is cream to pale yellow, pinkish to reddish brown near the pileus, and yellowish to dark grey brown towards the base.     

Enzymes of ammonia assimilation and their regulation inAzospirillum lipoferum strain D-2

Azospirillum lipoferum strain D-2 possesses the following enzymes for the assimilation of N₂ and NH ₄ ⁺ : nitrogenase, glutamine synthetase, NADPH-dependent glutamate synthase, NADH-/NADPH-dependent glutamate dehydrogenase, and NADH-dependent alanine dehydrogenase. Nitrogenase and glutamine synthetase are repressed, whereas glutamate dehydrogenase and alanine dehydrogenase are induced by NH ₄ ⁺ . Glutamine synthetase activity is modulated by both repression and depression and also by adenylylation.     

Potential of thidiazuron in improved micropropagation of Picrorhiza kurroa– an endangered medicinal herb of alpine Himalaya

The potential of thidiazuron (1-phenyl-3-(1, 2, 3-thiadiazol-5-yl) urea (TDZ) in the micropropagation of Picrorhiza kurroa, a western Himalayan herb was studied. The roots and rhizomes of this plant are rich in medicinally important glycosides i.e., picroside I, picroside II and kutkoside. Nodal segments (2.0–2.5 cm) from plants were pretreated with 0, 0.25, 0.50, 0.75, 1.0 μM TDZ for 7, 15 and 30 days. Maximum shoot multiplication was recorded after 60 days, provided, the nodal segments pretreated with 0.5 μM TDZ for 15 days were transferred to 0.8% agar gelled MS medium containing 3.0% sucrose. The shoots also showed profuse rooting having maximum length. When these plantlets were incubated at 15°C for 10 days and transferred to sand under polyhouse conditions, 100% survival was recorded after one month. In contrast, when the plantlets were not incubated at 15°C, only 86% survival was recorded. While the stomata and chlorophyll content of the tissue culture-raised plantlets treated at 15°C were comparable to that of plants growing in the field, the ones that were not treated at 15°C showed lower number of stomata and chlorophyll content.     

Siderophore-mediated transport of molybdenum inAzospirillum lipoferum strain D-2

A catechol-type compound was secreted byAzospirillum lipoferum D-2 in the growth medium when the cells became molybdenum-limited. The compound was identified as 3,5-dihydroxybenzoic acid. Production of 3.5-DHBA occurred under both molybdenum-limited as well as supplemented conditions. Presence of iron resulted in decreased production of 3,5-DHBA in the former case, whereas in the latter case it completely suppressed production of this compound. Spectral changes revealed coordination of molybdenum with 3,5-DHBA. Presence of 3,5-DHBA enhanced uptake of molybdenum. Appearance of a new 78-Kdal protein and hyperproduction of a 88-Kdal protein in the membrane fraction were the consequence of molybdenum limitation.