Two new genera of Indian Umbelliferae/Apiaceae

Two new monotypic genera are proposed:Karnataka, based uponSchultzia? benthamii C. B. Clarke (=K. benthamii) from southern Peninsular India andKedarnatha, based onK. sanctuarii, recently obtained from the Himalaya. Neither genus appears to be closely related to other apioid genera of our area.     

Computer calculation-based quantitative structure-activity relationships for the oxidation of phenol derivatives horseradish peroxidase compound II

 The second-order rate constants for the oxidation of a series of phenol derivatives by horseradish peroxidase compound II were compared to computer-calculated chemical parameters characteristic for this reaction step. The phenol derivatives studied were phenol, 4-chlorophenol, 3-hydroxyphenol, 3-methylphenol, 4-methylphenol, 4-hydroxybenzoate, 4-methoxyphenol and 4-hydroxybenzaldehyde. Assuming a reaction of the phenolic substrates in their non-dissociated, uncharged forms, clear correlations (r = 0.977 and r = 0.905) were obtained between the natural logarithm of the second-order rate constants (ln k _app and ln k ₂ respectively) for their oxidation by compound II and their calculated ionisation potential, i.e. minus the energy of their highest occupied molecular orbital [E(HOMO)]. In addition to this first approach in which the quantitative structure-activity relationship (QSAR) was based on a calculated frontier orbital parameter of the substrate, in a second and third approach the relative heat of formation (ΔΔHF) calculated for the process of one-electron abstraction and H^• abstraction from the phenol derivatives was used as a parameter. Plots of the natural logarithms of the second-order rate constants (k _app and k ₂) for the reaction and the calculated ΔΔHF values for the process of one-electron abstraction also provide clear QSARs with correlation coefficients of –0.968 and –0.926 respectively. Plots of the natural logarithms of the second-order rate constants (k _app and k ₂) for the reaction and the calculated ΔΔHF values for the process of H^• abstraction provide QSARs with correlation coefficients of –0.989 and –0.922 respectively. Since both mechanisms considered, i.e. initial electron abstraction versus initial H^• abstraction, provided clear QSARs, the results could not be used to discriminate between these two possible mechanisms for phenol oxidation by horseradish peroxidase compound II. The computer calculation-based QSARs thus obtained for the oxidation of the various phenol derivatives by compound II from horseradish peroxidase indicate the validity of the approaches investigated, i.e. both the frontier orbital approach and the approach in which the process is described by calculated relative heats of formation. The results also indicate that outcomes from computer calculations on relatively unrelated phenol derivatives can be reliably compared to one another. Furthermore, as the actual oxidation of peroxidase substrates by compound II is known to be the rate-limiting step in the overall catalysis by horseradish peroxidase, the QSARs of the present study may have implications for the differences in the overall rate of substrate oxidation of the phenol derivatives by horseradish peroxidase. Received: 29 March 1996 / Accepted: 17 July 1996     

Bovicins: The Bacteriocins of Streptococci and Their Potential in Methane Mitigation

Probiotics and Antimicrobial Proteins - Bovicin is a type AII lantibiotic, possessing two β-methyllanthionine and a disulfide bridge encoded by bovA gene hitherto unknown a couple of decades...     

Application of Plasmonics in Solar Cell Efficiency Improvement: a Brief Review on Recent Progress

We need electrical energy for our various daily life activities, and the existing fossil fuel will serve the purpose for a limited period only. Therefore, we need to look at alternate energy resources for long-term sustainable growth. Solar energy has been considered as one of the potential viable alternate sources of non-conventional energy. Solar photon harvesting is a technique where solar photon energy is being converted to electrical energy using solar cell devices. However, the solar power conversion efficiency is usually seen to be poor limiting the applications to large extent. Improving solar cell efficiency has, thus, been a great challenge to researchers who are actively working in this field. Various technological aspects are being looked at to improve efficiency, and out of them, plasmonic light trapping technique has been considered as one of the promising techniques. In the past years, considerable research efforts are being made towards the design and execution of the solar cell devices and to understand the mechanisms of performance enhancement. The present review outlines briefly the recent progress of plasmonic solar cell efficiency improvement that has happened, especially, for last 5–6 years. Plasmonic solar cells made of Si (silicon), GaAs (gallium arsenide); plasmonic dye-sensitized solar cells; plasmonic polymer (organic) solar cells and perovskite solar cells are mainly discussed along with the critical aspects that may influence the device performance.

     

Unexpectedly enhanced stereoselectivity of peroxidase-catalyzed sulfoxidation in branched alcohols

Lyophilized horseradish peroxidase (HRP) exhibits poor stereoselectivity in the sulfoxidation of thioanisole when the enzyme is either redissolved in water or suspended in organic solvents. However, when HRP is co-lyophilized in the presence of lyoprotectants or ligands, its stereoselectivity, although still low in most organic solvents, increases up to 4-fold if assayed in secondary or tertiary alcohols (but not in their linear isomers). A mechanistic hypothesis is presented explaining this puzzling phenomenon on the basis of a model of the active site of the enzyme-substrate complex derived from its X-ray crystal structure by means of molecular dynamics and energy minimization.     

Macrophage Mannosyl Fucosyl Receptor: Its Role in Invasion of Virulent and Avirulent L. Donovani Promastigotes

The interaction of leishmania parasites with macrophages is known to be receptor mediated. Previous study from this laboratory (J. Parasitol. 82:632, 1996) showed the significant involvement of LPG and gp63 receptors in the recognition of virulent strains onto the macrophages. The role of carbohydrate receptors--the other major receptors besides LPG and gp63 receptors, in the recognition of both virulent (strains AG83 and GE1) and avirulent (strain UR6) leishmania onto the host macrophages has been the major focus of the present investigation. Various neoglycoproteins were used as efficient ligands to preblock the carbohydrate receptors on the macrophage surface. Similarly, various sugar specific lectins were used to preblock the corresponding carbohydrate ligands on the parasite surface. When these preblocked macrophages or parasites were used to study their mode of recognition, it was obvious from the findings that avirulent leishmania promastigotes possibly use the mannosyl fucosyl receptors (MFR) more avidly for their initial attachment and subsequent internalization into the macrophages whereas the virulent leishmania exhibits limited use of this receptor. When a macrophage-like cell line (J774), lacking in MFR, was purposely selected to test the previous findings, as expected, the attachment of avirulent promastigotes (UR6) onto the cell line was found to be negligible when compared to the peritoneal macrophages. Thus, it appears that avirulent leishmania promastigotes probably utilize MFR significantly for their initial recognition and subsequent internalization by macrophages.     

A Chromosome Segment Substitution Library of Weedy Rice for Genetic Dissection of Complex Agronomic and Domestication Traits

Chromosome segment substitution lines (CSSLs) are a powerful alternative for locating quantitative trait loci (QTL), analyzing gene interactions, and providing starting materials for map-based cloning projects. We report the development and characterization of a CSSL library of a U.S. weedy rice accession ‘PSRR-1’ with genome-wide coverage in an adapted rice cultivar ‘Bengal’ background. The majority of the CSSLs carried a single defined weedy rice segment with an average introgression segment of 2.8 % of the donor genome. QTL mapping results for several agronomic and domestication traits from the CSSL population were compared with those obtained from two recombinant inbred line (RIL) populations involving the same weedy rice accession. There was congruence of major effect QTLs between both types of populations, but new and additional QTLs were detected in the CSSL population. Although, three major effect QTLs for plant height were detected on chromosomes 1, 4, and 8 in the CSSL population, the latter two escaped detection in both RIL populations. Since this was observed for many traits, epistasis may play a major role for the phenotypic variation observed in weedy rice. High levels of shattering and seed dormancy in weedy rice might result from an accumulation of many small effect QTLs. Several CSSLs with desirable agronomic traits (e.g. longer panicles, longer grains, and higher seed weight) identified in this study could be useful for rice breeding. Since weedy rice is a reservoir of genes for many weedy and agronomic attributes, the CSSL library will serve as a valuable resource to discover latent genetic diversity for improving crop productivity and understanding the plant domestication process through cloning and characterization of the underlying genes.     

Molecular Pathogenesis of Wilson Disease Among Indians: A Perspective on Mutation Spectrum in ATP7B gene, Prevalent Defects, Clinical Heterogeneity and Implication Towards Diagnosis

Aims We aim to identify the molecular defects in the ATP7B, the causal gene for Wilson disease (WD), in eastern Indian patients and attempt to assess the overall mutation spectrum in India for detection of mutant allele for diagnostic purposes. Methods Patients from 109 unrelated families and their first-degree relatives comprising 400 individuals were enrolled in this study as part of an ongoing project. Genomic DNA was prepared from the peripheral blood of Indian WD patients. PCR was done to amplify the exons and flanking regions of the WD gene followed by sequencing, to identify the nucleotide variants. Results In addition to previous reports, we recently identified eight mutations including three novel (c.3412 + 1G > A, c.1771 G > A, c.3091 A > G) variants, and identified patients with variable phenotype despite similar mutation background suggesting potential role of modifier locus. Conclusions So far we have identified 17 mutations in eastern India including five common mutations that account for 44% of patients. Comparative study on WD mutations between different regions of India suggests high genetic heterogeneity and the absence of a single or a limited number of common founder mutations. Genotype–phenotype correlation revealed that no particular phenotype could be assigned to a particular mutation and even same set of mutations in different patients showed different phenotypes.