Identification of an antimicrobial entity from the cyanobacterium Fischerella sp. isolated from bark of Azadirachta indica (Neem) tree

The active principle in a methanolic extract of the laboratory-grown cyanobacterium, Fischerella sp. isolated from Neem (Azadirachta indica) tree bark was active against Mycobacterium tuberculosis, Enterobacter aerogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, Escherichia coli as well as three multi-drug resistant E. coli strains in in vitro assays. Based on MS, UV, IR ¹H NMR analyses the active principle is proposed to be hapalindole T having the empirical formula C₂₁H₂₃N₂ClSO and a molecular weight of 386 with the melting point range 179–182 ^°C. The estimated production of Hapalindole T from the cyanobacterium is 1.25 mg g⁻¹ lyophilized biomass. It is suggested that cyanobacteria colonizing specialized niches such as tree bark could be an antibacterial drug resource.     

Reactivity switching and selective activation of C-1 or C-3 in 2,3-unsaturated thioglycosides

Reactivity switching and selective activation of C-1 or C-3 in 2,3-unsaturated thioglycosides, namely, 2,3-dideoxy-1-thio-d-hex-2-enopyranosides are reported. The reactivity switching allowed activation of either C-1 or C-3, with the use of either N-iodosuccinimide (NIS)/triflic acid (TfOH) or TfOH alone. C-1 glycosylation with alcohol acceptors occurred in the presence of NIS/TfOH, without the acceptors reacting at C-3. On the other hand, reaction of 2,3-unsaturated thioglycosides with alcohols mediated by triflic acid led to transposition of C-1 ethylthio-moiety to C-3 intramolecularly, to form 3-ethylthio-glycals. Resulting glycals underwent glycosylation with alcohols to afford 3-ethylthio-2-deoxy glycosides. However, when thiol was used as an acceptor, only a stereoselective addition at C-3 resulted, so as to form C-1, C-3 dithio-substituted 2-deoxypyranosides.     

Adventitious shoot regeneration and in vitro biosynthesis of steroidal lactones in <Emphasis Type="Italic">Withania coagulans</Emphasis> (Stocks) Dunal

A micropropagation system through leaf explant culture has been developed for Withania coagulans. Shoot bud proliferation occurred through both adventitious and de novo routes depending on the hormonal regime of the culture medium. Green compact nodular organogenic callus developed on Murashige and Skoog (MS) medium supplemented with 2.3 μM kinetin (Kn) and lower levels of 6–benzyladenine (BA) (13.3 μM) while multiple adventitious shoot bud differentiation occurred on medium fortified with 2.3 μM kinetin (Kn) and higher levels of BA (22.2 μM). Shoot buds were transferred to proliferation medium containing 2.2 μM BA, 2.3 μM Kn, and 3.9 μM phloroglucinol (PG) for further growth and development of shoot system. Elongated shoots were rooted using a two-step procedure involving pulse treatment of 7 days in a medium containing 71.6 μM choline chloride (CC) and 3.9 μM PG and then transferred to rooting medium containing ½ MS, 1.2 μM IBA, 3.6 μM PAA, and 14.3 μM CC for 3 weeks. Well-rooted plants were transferred to a greenhouse for hardening and further growth. Random amplification of polymorphic DNA (RAPD) showed monomorphic bands in all the plants thereby confirming clonality of the regenerants. Thin layer chromatography (TLC) showed the presence of withanolides in the regenerated plants. Quantification through reverse-phase HPLC revealed increased concentration of withanolides in the regenerated plants compared to the field-grown mother plant. Accumulation of withaferin A and withanolide A increased up to twofold and that of withanone up to tenfold. Direct regeneration via leaf explants will be useful for Agrobacterium-mediated genetic transformation, and will facilitate pathway manipulation using metabolic engineering for bioactive withanolides.     

Ribosome-DnaK interactions in relation to protein folding

Bacterial ribosomes or their 50S subunit can refold many unfolded proteins. The folding activity resides in domain V of 23S RNA of the 50S subunit. Here we show that ribosomes can also refold a denatured chaperone, DnaK, in vitro, and the activity may apply in the folding of nascent DnaK polypeptides in vivo. The chaperone was unusual as the native protein associated with the 50S subunit stably with a 1:1 stoichiometry in vitro. The binding site of the native protein appears to be different from the domain V of 23S RNA, the region with which denatured proteins interact. The DnaK binding influenced the protein folding activity of domain V modestly. Conversely, denatured protein binding to domain V led to dissociation of the native chaperone from the 50S subunit. DnaK thus appears to depend on ribosomes for its own folding, and upon folding, can rebind to ribosome to modulate its general protein folding activity.     

Identification of goat sperm ecto-cyclic AMP independent protein kinase substrate localized on sperm outer surface

We have demonstrated the location of a cyclic AMP independent serine/threonine protein kinase (ecto-CIK) on the outer surface of mature goat spermatozoa. We purified and characterized the major physiological protein substrate (MPS) of ecto-CIK. 32P-labeled membrane proteins phosphorylated by endogenous ecto-CIK of intact cauda-epididymal spermatozoa was solubilized with 1% Triton X-100 and then fractionated by following several chromatographic techniques like Sephacryl S-300 molecular sieve chromatography, DEAE-cellulose ion-exchange chromatography and chromatofocussing. The MPS of ecto-CIK has been purified to apparent homogeneity and it was found to be a monomeric protein of 100 kDa. Three isoforms of MPS have been found with pI of 6.37, 6.05, and 5.14 and all these isoforms served as the specific substrate of ecto-CIK. The ecto-kinase has nearly 30 times greater affinity for MPS as compared to casein the most potent exogenous protein substrate. Addition of MPS (pI 5.14) antibody caused head-to-head sperm agglutination. The Fv/Fab fragment of anti-MPS caused significant inhibition of sperm motility. The data show that MPS is an ecto-protein localized on the sperm head. MPS may thus play an important role for the regulation of sperm-egg interaction.     

Indigenous Plants Demonstrating Effective Antioxidant Properties

Biology Bulletin - Increased production of antioxidant herbal supplements utilizing traditional medicinal plants has been attributed to a high margin of economic effectiveness, environmental...     

Organization and dynamics in micellar structural transition monitored by pyrene fluorescence

Structural transitions involving shape changes play an important role in cellular physiology. Such transition can be induced in charged micelles at a given temperature by increasing ionic strength of the medium. We have monitored the change in organization and dynamics associated with sphere-to-rod transition of SDS micelles utilizing pyrene fluorescence. We report here, utilizing changes in the ratio of pyrene vibronic peak intensities (I₁/I₃), the apparent dielectric constant experienced by pyrene in spherical SDS micelles (in absence of salt) to be ∼32. Interestingly, the apparent micellar dielectric constant exhibits a reduction with increasing NaCl concentration. The dielectric constant in rod-shaped micelles of SDS (in presence of 0.5 M NaCl) turns out to be ∼22. To the best of our knowledge, these results constitute one of the early reports on polarity estimates in rod-shaped micelles. In addition, pyrene excimer/monomer ratio shows increase in SDS micelles with increasing NaCl concentration. We interpret this increase due to an increase in average number of pyrene molecules per micelle associated with the sphere-to-rod structural transition. These results could be significant in micellar drug solubilization and delivery, and in membrane morphology changes.     

Unfolded protein response during cardiovascular disorders: a tilt towards pro-survival and cellular homeostasis

Molecular and Cellular Biochemistry - The endoplasmic reticulum (ER) is an organelle that orchestrates the production and proper assembly of an extensive types of secretory and membrane proteins....