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      Volume 34, Issue 3

      September 2009,   pages  333-491

    • M K Chandrashekaran (1937–2009)

      Vidyanand Nanjundiah

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    • Clipboard: Branches in the plant world

      Jean-Pierre Mazat Christine Nazaret

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    • Clipboard: Estradiol can modulate sensory processing with rapid and longer term consequences

      Juli Wade

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    • Clipboard: Of pungency, pain, and naked mole rats: chili peppers revisited

      Renee M Borges

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    • Commentary: R A Fisher, design theory, and the Indian connection

      A R P Rau

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    • B P Belousov and his reaction

      Alexander Pechenkin

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      The generation to which Boris Pavlovich Belousov (1893–1976) belonged has almost disappeared. The archives hold only a few documents about his life and basically secret research. This article is a brief biography of Belousov and attempts to reconstruct what lay behind his famous discovery of the oscillatory homogeneous chemical reaction named after him.

    • What history tells us XVIII. When functional biologists propose mechanisms of evolution

      Michel Morange

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    • Thermal stability of 𝛼-amylase in aqueous cosolvent systems

      Jay Kant Yadav V Prakash

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      The activity and thermal stability of 𝛼-amylase were studied in the presence of different concentrations of trehalose, sorbitol, sucrose and glycerol. The optimum temperature of the enzyme was found to be 50 ± 2°C. Further increase in temperature resulted in irreversible thermal inactivation of the enzyme. In the presence of cosolvents, the rate of thermal inactivation was found to be significantly reduced. The apparent thermal denaturation temperature (𝑇𝑚)app and activation energy (𝐸𝑎) of 𝛼-amylase were found to be significantly increased in the presence of cosolvents in a concentration-dependent manner. In the presence of 40% trehalose, sorbitol, sucrose and glycerol, increments in the (𝑇𝑚)app were 20°C, 14°C, 13°C and 9°C, respectively. The 𝐸𝑎 of thermal denaturation of 𝛼-amylase in the presence of 20% (w/v) trehalose, sorbitol, sucrose and glycerol was found to be 126, 95, 90 and 43 kcal/mol compared with a control value of 40 kcal/mol. Intrinsic and 8-anilinonaphathalene-1-sulphonic acid (ANS) fluorescence studies indicated that thermal denaturation of the enzyme was accompanied by exposure of the hydrophobic cluster on the protein surface. Preferential interaction parameters indicated extensive hydration of the enzyme in the presence of cosolvents.

    • GalNAc-T14 may be involved in regulating the apoptotic action of IGFBP-3

      Chen Wu Yaojun Shan Xinxia Liu Wenqian Song Jiali Wang Minji Zou Min Wang Donggang Xu

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      Insulin-like growth factor binding protein-3 (IGFBP-3) is known to induce apoptosis in an insulin-like growth factor (IGF)-dependent and IGF-independent manner, but the mechanism underlying the IGF-independent effects remains unclear. Polypeptide 𝑁-acetylgalactosaminyltransferase 14 (GalNAc-T14) is a novel IGFBP-3 binding partner. In this paper, small interference RNA (siRNA) targeting GalNAc-T14 was used to examine whether GalNAc-T14 affects the apoptotic action of IGFBP-3. Using semi-quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and western blot analysis, we determined that GalNAc-T14 expression was downregulated by the siRNA directed against GalNAc-T14. Apoptosis analysis of IGFBP-3-overexpressing cells treated with siRNA against GalNAc-T14 was performed to determine if GalNAc-T14 was specifically involved in IGFBP-3 signalling. The results, as determined by flow cytometric analysis and caspase-3 assay, showed that the extent of apoptosis induced by IGFBP-3 increased with RNA interference (RNAi) knockdown of GalNAc-T14. Our data suggest that GalNAc-T14 influences the apoptotic action of IGFBP-3 and might mediate the signalling pathway of IGFBP-3. Experiments to determine the role of GalNAc-T14 in the regulation of apoptosis induced by IGFBP-3 are under way.

    • Single-nucleotide variations associated with Mycobacterium tuberculosis KwaZulu-Natal strains

      Sarbashis Das Ragothaman M Yennamalli Anchal Vishnoi Parul Gupta Alok Bhattacharya

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      The occurrence of drug resistance in Mycobacterium tuberculosis, the aetiological agent of tuberculosis (TB), is hampering the management and control of TB in the world. Here we present a computational analysis of recently sequenced drug-sensitive (DS), multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of M. tuberculosis. Single-nucleotide variations (SNVs) were identified in a pair-wise manner using the anchor-based whole genome comparison (ABWGC) tool and its modified version. For this analysis, four fully sequenced genomes of different strains of M. tuberculosis were taken along with three KwaZulu-Natal (KZN) strains isolated from South Africa including one XDR and one MDR strain. KZN strains were compared with other fully sequenced strains and also among each other. The variations were analysed with respect to their biological influence as a result of either altered structure or synthesis. The results suggest that the DR phenotype may be due to changes in a number of genes. The database on KZN strains can be accessed through the website http://mirna.jnu.ac.in/mgdd/.

    • Single-nucleotide polymorphisms in peroxisome proliferator-activated receptor 𝛾 and their association with plasma levels of resistin and the metabolic syndrome in a South Indian population

      Abdul Haseeb Mohammad Iliyas Subhabrata Chakrabarti Arif A Farooqui Sudhir R Naik Sudip Ghosh Madhuri Suragani Nasreen Z Ehtesham

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      Studies on the association of the Pro12Ala and C1431T polymorphisms of PPAR𝛾 with diabetes and obesity have revealed extensive population-dependent variations. However, association of these polymorphisms with the metabolic syndrome and its individual components has not been well investigated in the Indian population. The Indian population harbours the maximum number of diabetics in the world who are thus more susceptible to metabolic disorders. We screened a South Indian population (𝑁 = 699) for a possible association of these polymorphisms with the metabolic syndrome (MS) and type 2 diabetes. We also investigated the correlation of these two single-nucleotide polymorphisms (SNPs) with plasma resistin levels. The C1431T SNP was associated with higher levels of plasma resistin (𝑃 = 0.017). Furthermore, C1431T was associated with resistin in different tertiles. Prevalence of the ‘Pro-C’ haplotype decreased with increasing tertiles of resistin (84.1% to 75.4%, 𝑃 = 0.037). Plasma resistin levels were not found to be associated with MS and type 2 diabetes. These results point to a likely association of plasma resistin levels with PPAR𝛾 polymorphisms in the Indian population.

    • BRCA1 and BRCA2 germline mutation analysis among Indian women from south India: identification of four novel mutations and high-frequency occurrence of 185delAG mutation

      Kannan Vaidyanathan Smita Lakhotia H M Ravishankar Umaira Tabassum Geetashree Mukherjee Kumaravel Somasundaram

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      Mutations in the BRCA1 and BRCA2 genes profoundly increase the risk of developing breast and/or ovarian cancer among women. To explore the contribution of BRCA1 and BRCA2 mutations in the development of hereditary breast cancer among Indian women, we carried out mutation analysis of the BRCA1 and BRCA2 genes in 61 breast or ovarian cancer patients from south India with a positive family history of breast and/or ovarian cancer. Mutation analysis was carried out using conformation-sensitive gel electrophoresis (CSGE) followed by sequencing. Mutations were identified in 17 patients (28.0%); 15 (24.6%) had BRCA1 mutations and two (3.28%) had BRCA2 mutations. While no specific association between BRCA1 or BRCA2 mutations with cancer type was seen, mutations were more often seen in families with ovarian cancer. While 40% (4/10) and 30.8% (4/12) of families with ovarian or breast and ovarian cancer had mutations, only 23.1% (9/39) of families with breast cancer carried mutations in the BRCA1 and BRCA2 genes. In addition, while BRCA1 mutations were found in all age groups, BRCA2 mutations were found only in the age group of ≤ 40 years. Of the BRCA1 mutations, there were three novel mutations (295delCA; 4213T → A; 5267T → G) and three mutations that have been reported earlier. Interestingly, 185delAG, a BRCA1 mutation which occurs at a very high frequency in Ashkenazi Jews, was found at a frequency of 16.4% (10/61). There was one novel mutation (4866insT) and one reported mutation in BRCA2. Thus, our study emphasizes the importance of mutation screening in familial breast and/or ovarian cancers, and the potential implications of these findings in genetic counselling and preventive therapy.

    • A simple and efficient Agrobacterium-mediated procedure for transformation of tomato

      Manoj K Sharma Amolkumar U Solanke Dewal Jani Yogendra Singh Arun K Sharma

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      We describe a highly efficient and reproducible Agrobacterium-mediated transformation protocol applicable to several varieties of tomato (Solanum lycopersicum, earlier known as Lycopersicum esculentum). Conditions such as co-cultivation period, bacterial concentration, concentration of benzyl amino purine (BAP), zeatin and indole acetic acid (IAA) were optimized. Co-cultivation of explants with a bacterial concentration of 108 cells/ml for three days on 2 mg/l BAP, followed by regeneration on a medium containing 1 mg/ml zeatin resulted in a transformation frequency of 41.4%. Transformation of tomato plants was confirmed by Southern blot analysis and 𝛽-glucuronidase (GUS) assay. The protocol developed showed very high efficiency of transformation for tomato varieties Pusa Ruby, Arka Vikas and Sioux. The optimized transformation procedure is simple, efficient and does not require tobacco, Petunia, tomato suspension feeder layer or acetosyringone.

    • Association preference and mechanism of kin recognition in tadpoles of the toad Bufo melanostictus

      Lilly Margaret Eluvathingal Bhagyashri A Shanbhag Srinivas K Saidapur

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      In experiments with specially designed choice tanks, tadpoles of Bufo melanostictus spend significantly greater amounts of time near kin than near non-kin. However, in the absence of kin members, they prefer to spend more time near non-kin rather than stay away in isolation in the opposite blank zone with no company. This implies that association of toad tadpoles with their kin is due to attraction rather than repulsion from non-kin. Experiments designed to elucidate the sensory basis of kin recognition showed that toad tadpoles recognize their kin based on chemical cues rather than visual cues. They can also discriminate between homospecific non-kin and heterospecific (Sphaerotheca breviceps) tadpoles since the tadpoles spent significantly greater amounts of time near the former than near the latter. These findings suggest that where kin members are unavailable, selection may have favoured living with non-kin so as to derive benefits from group living and that a phenotype-matching mechanism may operate for both kin and species discrimination in B. melanostictus.

    • Quantitative effect and regulatory function of cyclic adenosine 5'-phosphate in Escherichia coli

      Atul Narang

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      Cyclic adenosine 5′-phosphate (cAMP) is a global regulator of gene expression in Escherichia coli. Despite decades of intensive study, the quantitative effect and regulatory function of cAMP remain the subjects of considerable debate. Here, we analyse the data in the literature to show that:

      • In carbon-limited cultures (including cultures limited by glucose), cAMP is at near-saturation levels with respect to expression of several catabolic promoters (including lac, ara and gal). It follows that cAMP-mediated regulation cannot account for the strong repression of these operons in the presence of glucose.
      • The cAMP levels in carbon-excess cultures are substantially lower than those observed in carbon-limited cultures. Under these conditions, the expression of catabolic promoters is very sensitive to variation of cAMP levels.
      • cAMP · CRP invariably activates the expression of catabolic promoters, but it appears to inhibit the expression of anabolic promoters.
      • These results suggest that the physiological function of cAMP is to maintain homeostatic energy levels.

      In carbon-limited cultures, growth is limited by the supply of energy; the cAMP levels therefore increase to enhance energy accumulation by activating the catabolic promoters and inhibiting the anabolic promoters. Conversely, in carbon-excess cultures, characterized by the availability of excess energy, the cAMP levels decrease in order to depress energy accumulation by inhibiting the catabolic promoters and activating the anabolic promoters.

    • Structure–function–folding relationships and native energy landscape of dynein light chain protein: nuclear magnetic resonance insights

      P M Krishna Mohan Ramakrishna V Hosur

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      The detailed characterization of the structure, dynamics and folding process of a protein is crucial for understanding the biological functions it performs. Modern biophysical and nuclear magnetic resonance (NMR) techniques have provided a way to obtain accurate structural and thermodynamic information on various species populated on the energy landscape of a given protein. In this context, we review here the structure–function–folding relationship of an important protein, namely, dynein light chain protein (DLC8). DLC8, the smallest subunit of the dynein motor complex, acts as a cargo adaptor. The protein exists as a dimer under physiological conditions and dissociates into a pure monomer below pH 4. Cargo binding occurs at the dimer interface. Dimer stability and relay of perturbations through the dimer interface are anticipated to be playing crucial roles in the variety of functions the protein performs. NMR investigations have provided great insights into these aspects of DLC8 in recent years.

    • Influenza A (H1N1) 2009: a pandemic alarm

      Madhu Khanna Neha Gupta Ankit Gupta V K Vijayan

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      At this critical juncture when the world has not yet recovered from the threat of avian influenza, the virus has returned in the disguise of swine influenza, a lesser known illness common in pigs. It has reached pandemic proportions in a short time span with health personnel still devising ways to identify the novel H1N1 virus and develop vaccines against it. The H1N1 virus has caused a considerable number of deaths within the short duration since its emergence. Presently, there are no effective methods to contain this newly emerged virus. Therefore, a proper and clear insight is urgently required to prevent an outbreak in the future and make preparations that may be planned well in advance. This review is an attempt to discuss the historical perspective of the swine flu virus, its epidemiology and route of transmission to better understand the various control measures that may be taken to fight the danger of a global pandemic.

    • Bioluminescence emissions of the firefly Luciola praeusta Kiesenwetter 1874 (Coleoptera : Lampyridae : Luciolinae)

      A Gohain Barua S Hazarika N M Saikia G D Baruah

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      We recorded the in vivo emission and time-resolved spectra of the firefly Luciola praeusta Kiesenwetter 1874 (Coleoptera : Lampyridae : Luciolinae). The emission spectrum shows that the full width at half maximum (FWHM) value for this particular species is 55 nm, which is significantly narrower than the in vivo half-widths reported till now. The time-resolved spectrum reveals that a flash of about 100 ms duration is, in fact, composed of a number of microsecond pulses. This suggests that the speed of the enzyme-catalysed chemiluminescence reaction in the firefly for the emission of light is much faster than was previously believed.

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