A direct-selection vector derived from pColE3-CA38 and adapted for foreign gene expression

The construction of a plasmid vector, pVT25, which allows an efficient and direct selection for transformed cells carrying recombinant plasmids is described. In this vector, the replicon and Ap^R gene from plasmid pBR327 are fused to the colE3 gene of pColE3-CA38, whereby positive selection is based on the inactivation of the lethal colicin E3 by the insertion of a foreign DNA fragment. However, pVT25 can be maintained within the Escherichia coli cells when complemented with another plasmid, pVT26, which expresses the colicin E3 immunity (imm) and the Tc^R phenotypes. Furthermore, pVT25 was used to regulate the expression of the synthetic human proinsulin gene fused to the colE3 gene at the single ClaI site. The production of the characteristic C-peptide of proinsulin, monitored by radioimmunoassay, was shown to be under the control of the inducible promoter of the colE3 gene.     

Insilico docking study of compounds elucidated from helicteres isora fruits with ampkinase- insulin receptor

Insulin receptor (IR) proteins were essential intracellular signaling peptides in the insulin action cascade. Insulin receptor substrateproteins (IRS-1and IRS-2) serve and regulate the insulin level in the normal insulin action. The broad role of IRS-1 and IRS-2 in cellgrowth and survival reveals a common regulatory pathway linking development, somatic growth, fertility, neuronal proliferation,and aging to the core mechanisms used by vertebrates for nutrient sensing. Such type of proteins were cyclic adenosinemonophosphate-activated protein kinase, this proteins play a key role in the insulin response and regulation. Type -2 Diabetesmellitus occurs during prolonged periods of peripheral insulin resistance due to inactivation of IRS proteins. The compoundsisolated from the medicinal plants were safer than synthetic drugs and possess high bio activity. In the present study, fourcompounds were elucidated from fruits of Helicteres isora. The elucidated compounds were evaluated for the antidiabetic activityusing in silico docking study. The receptor was analyzed for the active site and pocket finder tools. The aminoacids such asPhenylalanine, Lysine, Glutamic acid and Asparigine were predicted as active site binding residues. Docking studies were donethrough Autodock 4 software. All the compounds from fruits of Helicteres isora showed good docking profiles with AMP Kinase,except compound-3 (1,2,3,4-tetrahydro-1,5,6,8-tetramethyl-7-(2-methylprop-1-enylnaphthalene-4-ylpivalate). Finally the result fromthe study demonstrates that the HS-1, HS-2 and HS-4 posses potent anti diabetic activity against type-2 diabetes mellitus throughdrug action on AMP kinase cascade system.     

Two functionally distinctive phosphopantetheinyl transferases from amoeba Dictyostelium discoideum

The life cycle of Dictyostelium discoideum is proposed to be regulated by expression of small metabolites. Genome sequencing studies have revealed a remarkable array of genes homologous to polyketide synthases (PKSs) that are known to synthesize secondary metabolites in bacteria and fungi. A crucial step in functional activation of PKSs involves their post-translational modification catalyzed by phosphopantetheinyl transferases (PPTases). PPTases have been recently characterized from several bacteria; however, their relevance in complex life cycle of protozoa remains largely unexplored. Here we have identified and characterized two phosphopantetheinyl transferases from D. discoideum that exhibit distinct functional specificity. DiAcpS specifically modifies a stand-alone acyl carrier protein (ACP) that possesses a mitochondrial import signal. DiSfp in contrast is specific to Type I multifunctional PKS/fatty acid synthase proteins and cannot modify the stand-alone ACP. The mRNA of two PPTases can be detected during the vegetative as well as starvation-induced developmental pathway and the disruption of either of these genes results in non-viable amoebae. Our studies show that both PPTases play an important role in Dictyostelium biology and provide insight into the importance of PPTases in lower eukaryotes.     

Correlation between sugar pucker and the orientation around the C3′?O3′ bond (Φ′) in 3′-mononucleotides

Classical potential functions (CPF) calculations on 3′-mononucleotides, the building blocks of nucleic acids, predict a correlation between the sugar ring pucker and the torsion angle Φ′ around the C3′? O3′ bond. In ribonucleotides, the value of Φ′ depends on the sugar pucker, viz. the C2′-endo sugar pucker is associated with Φ′ = 210° and 270°, while the C3′-endo sugar pucker favors only Φ′ = 210°. On the other hand, in deoxyribonucleotides, both sugar puckers show a preference for Φ′ = 180°. These theoretical predictions are fully corroborated by the results obtained from x-ray and nmr studies on mono-, di-, and polynucleotides.     

Macrotermes mounds as sites for tree regeneration in a Sudanian woodland (Burkina Faso)

The importance of mounds created by Macrotermes subhyalinus as safe site for tree regeneration was analysed in a savannah woodland of Burkina Faso. Plantlets (height <1.5 m) were sampled and followed over an year in 72 × 4 m² quadrats located on M. subhyalinus mounds and adjacent areas. The mechanisms of regeneration and plantlet mortality were also determined. We identified three regeneration mechanisms: seedlings regenerated by seed (abundant on mounds), sprouts (abundant on adjacent areas) and root suckers (a rare case on both sites). A total of 37 species representing 17 families and 30 genera were found on all quadrats, of which 29 species were found on termite mounds and 22 species on adjacent areas. Species richness and density of plantlets at the 4 m² scale were higher on mounds than in the adjacent area (P < 0.05). Among plantlet categories, seedling density was significantly different among microhabitats (P < 0.001) and across sampling periods (P < 0.01) and, the majority of plantlet individuals appeared within the 0–25 cm height class. The mortality of plantlets and particularly seedling mortality differed significantly between microhabitats (P < 0.01) and between periods (P < 0.01), whereas more than half the variation in the death of Acacia erythrocalyx seedlings (the most abundant species) were related to the density of the live seedlings of the same species (P < 0.001). The observed mortality rate was way below 50%; plantlet density remained higher on mound during sampling periods as compared to the adjacent area. It can thus be concluded that Macrotermes termite mounds are favourable sites for the recruitments of woody plants in savannah woodlands.     

The genetic control of chemically and radiation-induced skin tumorigenesis: a study with carcinogenesis-susceptible and carcinogenesis-resistant mice

Outbred carcinogenesis-resistant (Car-R) and carcinogenesis-susceptible (Car-S) mouse lines were generated by phenotypic selection for resistance or susceptibility to two-stage skin carcinogenesis. These two Car mouse lines differ by >100-fold in susceptibility. In the present study, we tested the hypothesis that a subset of genetic loci responsible for susceptibility or resistance to chemical skin tumorigenesis may also be involved in radiation-induced skin tumorigenesis. Skin tumorigenesis was tested in groups of Car-S/R mice after X-ray initiation and 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion. We found that ionizing radiation can initiate skin tumors in Car-S mice but not in Car-R mice. In Car-S mice, the most effective radiation doses (6 and 10 Gy given in four fractions) gave a threefold increase in tumor multiplicity and a twofold increase in tumor incidence compared to a TPA-only control group. We performed a molecular analysis of Hras gene mutations in skin tumors of Car-S mice induced by X-ray initiation/TPA promotion or by TPA promotion alone. The most notable difference emerging from the comparison of these mutation patterns is the high incidence ( approximately 50%) of papillomas lacking Hras gene mutations in X-ray-initiated/TPA-promoted papillomas compared to 13% in papillomas induced by TPA alone, suggesting that lack of Hras gene mutations is a consistent feature of radiation-induced papillomas.