Intergenerational paternal effect of adult density in Drosophila melanogaster

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Enhanced stability of cis Pro-Pro peptide bond in Pro-Pro-Phe sequence motif

Identification of sequence motifs that favor cis peptide bonds in proteins is important for understanding and designing proteins containing turns mediated by cis peptide conformations. From (1)H NMR solution studies on short peptides, we show that the Pro-Pro peptide bond in Pro-Pro-Phe almost equally populates the cis and trans isomers, with the cis isomer stabilized by a CHc...pi interaction involving the terminal Pro and Phe. We also show that Phe is over-represented at sequence positions immediately following cis Pro-Pro motifs in known protein structures. Our results demonstrate that the Pro-Pro cis conformer in Pro-Pro-Phe sequence motifs is as important as the trans conformer, both in short peptides as well as in natively folded proteins.     

The Light Quanta Modulated Physiological Response of Brassica Juncea Seedlings Subjected to Ni(II) Stress

This work is a study of the inter‐relationship between parameters that principally affect the metal up‐take in the plant. The relationships between the concentration of metal in the growth medium, C_s, the concentration of metal absorbed by the plant, C_p, and the total biomass achieved, M, all of which are factors relevant to the efficiency of phytoremediation of the plant, have been investigated via the macro‐physiological response of Brassica juncea seedlings to Ni(II) stress. The factorial growth experiments treated the Ni(II) concentration in the agar gel and the diurnal light quanta (DLQ) as independently variable parameters. Observations included the evidence of light enhancement of Ni toxicity at the root as well as at the whole plant level, the shoot mass index as a possible indicator of shoot metal sequestration in B. juncea, the logarithmic variation of C_p with C_s and the power‐law dependence of M on C_p. The sum total of these observations indicates that for the metal accumulator B. juncea with regard to its capacity to accumulate Ni, the overall metabolic nature of the plant is important – neither rapid biomass increase nor a high metal concentration capability favor the removal of high metal mass from the medium, but rather the plant with the moderate photosynthetically driven biomass growth and moderate metal concentrations demonstrated the ability to remove the maximum mass of metal from the medium. The implications of these observations in the context of the perceived need in phytoremediation engineering to maximize C_p and M simultaneously in the same plant, are discussed.     

Nampt/PBEF/Visfatin regulates insulin secretion in beta cells as a systemic NAD biosynthetic enzyme

Intracellular nicotinamide phosphoribosyltransferase (iNampt) is an essential enzyme in the NAD biosynthetic pathway. An extracellular form of this protein (eNampt) has been reported to act as a cytokine named PBEF or an insulin-mimetic hormone named visfatin, but its physiological relevance remains controversial. Here we show that eNampt does not exert insulin-mimetic effects in vitro or in vivo but rather exhibits robust NAD biosynthetic activity. Haplodeficiency and chemical inhibition of Nampt cause defects in NAD biosynthesis and glucose-stimulated insulin secretion in pancreatic islets in vivo and in vitro. These defects are corrected by administration of nicotinamide mononucleotide (NMN), a product of the Nampt reaction. A high concentration of NMN is present in mouse plasma, and plasma eNampt and NMN levels are reduced in Nampt heterozygous females. Our results demonstrate that Nampt-mediated systemic NAD biosynthesis is critical for beta cell function, suggesting a vital framework for the regulation of glucose homeostasis.     

Gene silencing approaches through virus-based vectors: speeding up functional genomics in monocots

Plant Molecular Biology - The design and use of existing VIGS vectors for revealing monocot gene functions are described and potential new vectors are discussed, which may expand their repertoire....     

Differential interactions of antitumor antibiotics chromomycin A(3) and mithramycin with d(TATGCATA)(2) in presence of Mg(2+)

The antitumor antibiotics chromomycin A(3) (CHR) and mithramycin (MTR) are known to inhibit macromolecular biosynthesis by reversibly binding to double stranded DNA with a GC base specificity via the minor groove in the presence of a divalent cation such as Mg(2+). Earlier reports from our laboratory showed that the antibiotics form two types of complexes with Mg(2+): complex I with 1:1 stoichiometry and complex II with 2:1 stoichiometry in terms of the antibiotic and Mg(2+). The binding potential of an octanucleotide, d(TATGCATA)(2), which contains one potential site of association with the above complexes of the two antibiotics, was examined using spectroscopic techniques such as absorption, fluorescence, and circular dichroism. We also evaluated thermodynamic parameters for the interaction. In spite of the presence of two structural moieties of the antibiotic in complex II, a major characteristic feature was the association of a single ligand molecule per molecule of octameric duplex in all cases. This indicated that the modes of association for the two types of complexes with the oligomeric DNA were different. The association was dependent on the nature of the antibiotics. Spectroscopic characterization along with analysis of binding and thermodynamic parameters showed that differences in the mode of recognition by complexes I and II of the antibiotics with polymeric DNA existed at the oligomeric level. Analysis of the thermodynamic parameters led us to propose a partial accommodation of the ligand in the groove without the displacement of bound water molecules and supported earlier results on the DNA structural transition from B --> A type geometry as an obligatory requirement for the accommodation of the bulkier complex II of the two drugs. The role of the carbohydrate moieties of the antibiotics in the DNA recognition process was indicated when we compared the DNA binding properties with the same type of Mg(2+) complex for the two antibiotics.     

Haematinic effect of Hygrophila spinosa T. Anderson on experimental rodents

Ethanolic extract of the aerial parts of H. spinosa a semiwoody herb was examined on male albino rats for certain haematological changes. The extract (100 & 200 mg/kg, po) significantly increased the haemoglobin, haematocrit, RBC and total WBC, as compared with vehicle treated control rat haemogram. In anemic male albino rats, the extract significantly increased haemoglobin, haematocrit and RBC count. Serum iron and serum total iron binding capacity were significantly decreased in H. spinosa extract treated anemic rats as compared with those in the vehicle treated anemic control rats. These findings demonstrated the haematinic effect of H. spinosa extract on experimental animals.     

Isolation,purification and partial chemical characterization of a lethal factor from common indian toad (Bufo melanostictus,Schneider) skin extract

Indian toad (Bufo melanostictus, Schneider) skin extract (TSE) is pharmacologically potent and probably contains several bioactive compounds [Das et. al., Indian J Pharmacol, 28 (1996) 72]. A lethal factor was isolated and purified by neutral alumina column chromatography followed by HPLC. Spectroscopic (UV, IR, FAB-MASS) study indicated that the lethal factor (TSE-LF) was a 254 Da long chain compound with carbonyl, hydroxyl and ester as functional groups. LD50 of TSE-LF was found to be 3.5 mg/kg (iv). Biological study showed that TSE-LF possesses hypotensive, cardiotoxic, neurotoxic activity and produced death by apnoea in experimental animal. Cyproheptadine antagonised TSE-LF induced contraction of isolated smooth muscle indicating involvement of histamine/serotonin receptors. TSE-LF induced neurotoxic action on chick biventer cervices was mediated through Ca2+ ion.     

RecA-mediated rescue of Escherichia coli strains with replication forks arrested at the terminus

The recombinational rescue of chromosome replication was investigated in Escherichia coli strains with the unidirectional origin oriR1, from the plasmid R1, integrated within oriC in clockwise (intR1(CW)) or counterclockwise (intR1(CC)) orientations. Only the intR1(CC) strain, with replication forks arrested at the terminus, required RecA for survival. Unlike the strains with RecA-dependent replication known so far, the intR1(CC) strain did not require RecBCD, RecF, RecG, RecJ, RuvAB, or SOS activation for viability. The overall levels of degradation of replicating chromosomes caused by inactivation of RecA were similar in oriC and intR1(CC) strains. In the intR1(CC) strain, RecA was also needed to maintain the integrity of the chromosome when the unidirectional replication forks were blocked at the terminus. This was consistent with suppression of the RecA dependence of the intR1(CC) strain by inactivating Tus, the protein needed to block replication forks at Ter sites. Thus, RecA is essential during asymmetric chromosome replication for the stable maintenance of the forks arrested at the terminus and for their eventual passage across the termination barrier(s) independently of the SOS and some of the major recombination pathways.