Agarol,a new sesquiterpene from Aquilaria agallocha

The isolation of two sesquiterpenes, gmelofuran and agarol, from Aquilaria agallocha is described Gmelofuran has not been previously reported from this genus and the structure of agarol has been elucidated by physical methods and chemical reactions.     

Curcumin and kaempferol prevent lysozyme fibril formation by modulating aggregation kinetic parameters

Interaction of small molecule inhibitors with protein aggregates has been studied extensively, but how these inhibitors modulate aggregation kinetic parameters is little understood. In this work, we investigated the ability of two potential aggregation inhibiting drugs, curcumin and kaempferol, to control the kinetic parameters of aggregation reaction. Using thioflavin T fluorescence and static light scattering, the kinetic parameters such as amplitude, elongation rate constant and lag time of guanidine hydrochloride-induced aggregation reactions of hen egg white lysozyme were studied. We observed a contrasting effect of inhibitors on the kinetic parameters when aggregation reactions were measured by these two probes. The interactions of these inhibitors with hen egg white lysozyme were investigated using fluorescence quench titration method and molecular dynamics simulations coupled with binding free energy calculations. We conclude that both the inhibitors prolong nucleation of amyloid aggregation through binding to region of the protein which is known to form the core of the protein fibril, but once the nucleus is formed the rate of elongation is not affected by the inhibitors. This work would provide insight into the mechanism of aggregation inhibition by these potential drug molecules.     

Rhinosporidiosis in Delhi, North India: Case Series from a Non-endemic Area and Mini-review

We report three cases of rhinosporidiosis from migrant population of Delhi. Three male patients had sino-nasopharyngeal, nasopharyngeal and nasal rhinosporidiosis, respectively. One patient gave a history of bathing in stagnant water. The diagnosis was made by clinical presentation and microscopic observation of characteristic sporangia of Rhinosporidium seebri in mycological and histopathological investigations. All the patients were successfully treated with complete surgical excision of lesions and cauterization of base. There were no recurrences.     

GA application induces alteration in sex ratio and cell death in <Emphasis Type="Italic">Jatropha curcas</Emphasis>

Jatropha curcas L. is a commercially important plant with biodiesel and medicinal potential. It is a monoecious plant with staminate and pistillate flowers in same inflorescence with number of staminate flowers being higher than pistillate ones resulting in very low fruit yield. Altering sex ratio to increase the number of female flowers would lead to better yield. Phytohormones are most important factors known to alter sex ratio in plants. The mechanism by which phytohormones alter sex ratio differs in different plant species. Among phytohormones, GA plays an important role in sex alteration. In this study, we report the effect of exogenous application of GA on sex modification in J. curcas. There was considerable increase in number of female flowers by application of GA. At lower concentrations (10 and 100 ppm), increase in number of female flowers and fruit yield was proportionate to the concentration of hormone used but at higher concentration (1,000 ppm) though there was an increase in number of female flowers, fruit yield decreased. This was due to an increased peduncle length and enhanced cell death as a consequence of endogenous release of hydrogen peroxide in response to increased GA, resulting in withering of fruits.     

Sterculia guttata seeds extractives--an effective mosquito larvicide

The larvicidal activity of ethanol, chloroform and hexane soxhlet extracts obtained from S. guttata seeds was investigated against the IVth instar larvae of Dengue fever vector, Aedes aegypti and filarial vector, Culex quinquefasciatus. All extracts including fractions of ethanol extract exhibited 100% larval kill within 24 hr exposure period at 500 ppm concentration. Fraction A1 of ethanol was found to be most promising; its LC50 was 21.552 and 35.520 ppm against C. quinquefasciatus and A. aegypti respectively. Naturally occurring S. guttata seed derived fractions merit further study as potential mosquito larval control agents or lead compounds.     

Effect of Ascorbic Acid Supplementation on Certain Oxidative Stress Parameters in the Post Reperfusion Patients of Myocardial Infarction

Reperfusion injury causes oxidative stress thereby resulting in an imbalance between oxidant-antioxidant systems. In the present communication, the effect of ascorbic acid supplementation has been studied on certain oxidant and antioxidant parameters in the blood of the patients with myocardial infarction before and after thrombolysis. In patients after thrombolysis, the activity of antioxidant enzyme, superoxide dismutase, in the blood was found to be significantly reduced where as the activity of the oxidant enzyme, xanthine oxidase, was found to be significantly increased. Malondialdehyde levels, the index of free radical mediated damage, was also found to be significantly elevated in thrombolyzed patients compared to the patients before thrombolysis. Supplementation of vitamin C to the post reperfusion patients restored these parameters back to normal or near normal levels.     

The social, moral, ethical, legal and political implications of today's biological technologies: an Indian point of view

The last 50 years have seen an increasing emphasis on ethical, moral, social, legal, political and economic implications of science for reasons that are discussed in this article. Biotechnology has been no exception to this trend. Areas of biotechnology where the above implications have been important, are briefly described. Ethical and related issues in today's biology-based technologies are discussed with special reference to India. Examples of technological exploitation within a country, or of one country by another, using modern biology-based technologies are given. The possible implications of one new and emerging biology-based technology are discussed. It is concluded that a well-informed and knowledgeable society is the only assured insurance against possible misuse of biology-based technologies of today and tomorrow, including their use for the exploitation of people. The recent decision of the Prime Minister of India to set up a National Knowledge Commission is mentioned in this context.     

Chromosomal integration mechanism of infecting mu virion DNA

DNA transposition is central to the propagation of temperate phage Mu. A long-standing problem in Mu biology has been the mechanism by which the linear genome of an infecting phage, which is linked at both ends to DNA acquired from a previous host, integrates into the new host chromosome. If Mu were to use its well-established cointegrate mechanism for integration (single-strand nicks at Mu ends, joined to a staggered double-strand break in the target), the flanking host sequences would remain linked to Mu; target-primed replication of the linear integrant would subsequently break the chromosome. The absence of evidence for chromosome breaks has led to speculation that infecting Mu might use a cut-and-paste mechanism, whereby Mu DNA is cut away from the flanking sequences prior to integration. In this study we have followed the fate of the flanking DNA during the time course of Mu infection. We have found that these sequences are still attached to Mu upon integration and that they disappear soon after. The data rule out a cut-and-paste mechanism and suggest that infecting Mu integrates to generate simple insertions by a variation of its established cointegrate mechanism in which, instead of a "nick, join, and replicate" pathway, it follows a "nick, join, and process" pathway. The results show similarities with human immunodeficiency virus integration and provide a unifying mechanism for development of Mu along either the lysogenic or lytic pathway.     

Crystal Structure of Full-length Mycobacterium tuberculosis H37Rv Glycogen Branching Enzyme: INSIGHTS OF N-TERMINAL β-SANDWICH IN SUBSTRATE SPECIFICITY AND ENZYMATIC ACTIVITY*

The open reading frame Rv1326c of Mycobacterium tuberculosis (Mtb) H37Rv encodes for an α-1,4-glucan branching enzyme (MtbGlgB, EC 2.4.1.18, Uniprot entry {"type":"entrez-protein","attrs":{"text":"Q10625","term_id":"1707934","term_text":"Q10625"}}Q10625). This enzyme belongs to glycoside hydrolase (GH) family 13 and catalyzes the branching of a linear glucose chain during glycogenesis by cleaving a 1→4 bond and making a new 1→6 bond. Here, we show the crystal structure of full-length MtbGlgB (MtbGlgBWT) at 2.33-Å resolution. MtbGlgBWT contains four domains: N1 β-sandwich, N2 β-sandwich, a central (β/α)₈ domain that houses the catalytic site, and a C-terminal β-sandwich. We have assayed the amylase activity with amylose and starch as substrates and the glycogen branching activity using amylose as a substrate for MtbGlgBWT and the N1 domain-deleted (the first 108 residues deleted) MtbΔ108GlgB protein. The N1 β-sandwich, which is formed by the first 105 amino acids and superimposes well with the N2 β-sandwich, is shown to have an influence in substrate binding in the amylase assay. Also, we have checked and shown that several GH13 family inhibitors are ineffective against MtbGlgBWT and MtbΔ108GlgB. We propose a two-step reaction mechanism, for the amylase activity (1→4 bond breakage) and isomerization (1→6 bond formation), which occurs in the same catalytic pocket. The structural and functional properties of MtbGlgB and MtbΔ108GlgB are compared with those of the N-terminal 112-amino acid-deleted Escherichia coli GlgB (ECΔ112GlgB).     

Comparative Assessment of ISSR and RAPD Marker Assays for Genetic Diversity Analysis in Jojoba [Simmondsia chinensis (Link) Schneider]

A collection of male and female plants of ten Jojoba [Simmondsia chinensis (Link) Schneider] genotypes was analyzed with 50 RAPID and 55 ISSR markers to compare the efficiency and utility of these techniques for detecting genetic polymorphism. RAPID and ISSR analysis yielded 442 and 566 scorable amplified products, respectively, of which 60.7 and 69.3% were polymorphic. ISSRs revealed efficiency over RAPDs due to high EMR (effective multiplex ratio), DI (diversity index, mean PIC per primer) and MI (marker index) values. Jaccard similarity matrices among male plants, among female plants and between male and female plants of the ten jojoba genotypes varied between 0.705-0.784. Dendrograms generated by cluster analysis (UPGMA, NTSYS-pc) supported by bootstrap values using RAPID and ISSR datasets led to grouping of most of male and females genotypes in separate clusters. While pattern of clustering remained more or less same, the two dendrograms did differ with respect to the grouping of a few male and female genotypes. The value of the Mantel test shows poor correlation (r = 0.41) between ISSR and RAPID marker datasets.