Identification and characterization of nuclear location signal-binding proteins in nuclear envelopes

A radioiodinated, photoactivable synthetic nonapeptide corresponding to the nuclear location signal (NLS) of SV40 large T antigen has been used in photolabelling reactions with purified mouse liver nuclei, nuclear envelopes and other cellular fractions, to identify specific NLS-binding proteins which may be involved in selective transport of karyophilic proteins. SDS-polyacrylamide gel analysis of photolabelled products demonstrates that a 60 kDa nuclear protein and four nuclear envelope proteins (67, 60, 53 and 47 kDa) bind specifically to the native NLS and not to a mutant NLS or unrelated sequences. This binding shows saturation kinetics, with highest affinity of the NLS for the 60 and 67 kDa proteins. The nuclear 60 kDa NLS-binding protein is identical to the nuclear envelope 60 kDa NLS-binding protein by two-dimensional gel analysis of labelled proteins. Biochemical fractionation of labelled nuclear envelopes suggests that the 53 and 47 kDa proteins are peripheral membrane proteins whereas the 67 and 60 kDa proteins can be localized to the pore complex. The NLS also binds to solubilized 67, 60, 53 and 47 kDa proteins but with decreased affinity. Our results suggest that one of the early steps in selective nuclear transport of proteins may be the recognition of the NLS by the 60 kDa and/or 67 kDa binding proteins present in the nuclear pore complex.     

Nitrogenase activity of the antarctic cyanobacteriumNostoc commune: Influence of temperature

Nitrogenase activity (C₂H₂ reduction) ofNostoc commune isolated from Schirmacher Oasis (Antarctica) was compared withNostoc muscorum, N. calcicola, Anabaena doliolum andGloeocapsa sp. The temperature profile of acetylene reduction (5–30 °C) forN. commune revealed (a) that the highest rate of nitrogenase activity was at 25±1 °C, (b) that it was low (69 %) in comparison withN. muscorum, and (c) that nitrogenase activity continued at lower temperatures, which was not evident for other cyanobacteria. The results suggest thatN. commune is adapted to lower temperatures in terms of nitrogen fixation.     

Secretion of acid phosphatase by axenic Entamoeba histolytica NIH-200 and properties of the extracellular enzyme

Entamoeba histolytica (NIH-200) secreted large amounts of acid phosphatase in its external environment when grown axenically in modified TPS-II medium. Fractionation by DEAE-cellulose chromatography of the precipitate obtained from the cell-free medium at 60% ammonium sulfate saturation yielded 3 distinct peaks of enzyme activity. The enzyme in all the peaks showed resistance to tartrate but was inhibited by fluoride, cupric chloride, ethylene diamine-tetra acetic acid, ammonium molybdate and cysteine; however, enzyme associated with different peaks differed in its polyacrylamide gel electrophoretic profiles and behavior towards concanavalin A.     

Cadmium-mediated resistance to metals and antibiotics in a cyanobacterium

Summary Cadmium-resistant strains of the cyanobacterium Nostoc calcicola were isolated through the step-wise transfer of the organism to higher levels of the metal. One of the Cd-resistant strains (Cd^r–10) showed cross-resistance to antibiotics like neomycin (1 g/ml), chloramphenicol (3 g/ml) but not to streptomycin. The Cd-resistant strain also tolerated elevated levels of metals such as zinc (20 ppm) and mercury (1 ppm). The stability of the metal-resistance required the presence of Cd²⁺ ions in the growth medium. It is suggested that metal resistance may also be determined by gene(s) on the antibiotic resistance plasmids in cyanobacteria.     

Biological spectrum and other structural functional attributes of the vegetation of Kumaun Himalaya

Spectra on life form, leaf size, leaf persistence, flowering season, and shade tolerance of trees in different vegetation types occurring within the north-western catchment of the river Gola in Kumaun Himalaya are presented. The flora of Quercus leucotrichophora, Quercus lanuginosa and Quercus floribunda forests is phanerophytic, that of Pinus roxburghii and mixed forests therophytic. The grassland vegetation is characterized by the largest percentage of hemicryptophytes. The flora of the whole area, is therophytic. The biological spectrum for the entire Kumaun Himalaya is characterized as therohemigeophytic. Among the various altitudinal zones, the tropical has a preponderance of phanerophytes, the temperate and the alpine of hemicryptophytes.The observations on leaf size indicate that with the exception of Pinus roxburghii forest, in all vegetation types, the species with microphylls are greater in number. In this region, the vegetation expression is evergreen, although the tree flora has a considerable content of deciduous elements. In all the forests, the flowering period in most of the trees is vernal.On the basis of relative density, the greatest proportions of adult trees in the Pinus roxburghii and Quercus lanuginosa forests are shade intolerant, while in the mixed and Quercus leucotrichophora forests maximum trees are intermediate in shade tolerance. With the exception of the Pinus roxburghii forest, all the forests exhibit the dominance of trees which are shade tolerant at the seedling stage. On the basis of relative density, all forest types, except for Pinus roxburghii forest, have 74.5 to 100% trees with the potentiality of vegetative reproduction.Financial support from the Indian Space Research Organisation, Banglore and University Grants Commission, New Delhi is gratefully acknowledged.     

The influence of thyroxine on the host-parasite relationship of Ancylostoma caninum in swiss albino mice

Bhai Ismail and Pandey A.K. 1981. The influence of thyroxine on the host-parasite relationship of Ancylostoma caninum in Swiss albino mice. International Journal for Parasitology11: 377–379. Thyroxine treatment, 1μg/0.3 ml saline/mouse/day for 21 days, significantly increased the susceptibility of female mice (P > 0.001) but not of males to Ancylostoma caninum infection, compared with their saline-treated controls. This accounted for the loss of the sex difference between the worm populations of male and female mice (0.001 < P < 0.005). More hyperthyroid females died following infection with A. caninum than control female mice. The possible reasons for higher susceptibility of female mice are discussed.     

Gonadal hormones in experimental Ancylostoma caninum infections in male Swiss albino mice

Ismail Bhai and Pandey A. K. 1982. Gonadal hormones in experimental Ancylostoma caninum infections in male Swiss albino mice. International Journal for Parasitology12: 589–591. Orchiectomy in mice increased their resistance to Ancylostoma caninum infection. Testosterone propionate increased the susceptibility of castrated animals to infection and also increased the survival of larvae in muscles, compared with sham-operated placebo-treated controls with intact testes. Estradiol benzoate increased the resistance of castrated mice as demonstrated by differential larval recoveries. The possible involvement of the small intestine as a barrier to infection and the influence of testosterone on host susceptibility to infection is discussed.     

A Ca2+/CaM-dependent kinase from pea is stress regulated and in vitro phosphorylates a protein that binds to AtCaM5 promoter.

An immuno-homologue of maize Ca2+/calmodulin (CaM)-dependent protein kinase with a molecular mass of 72 kDa was identified in pea. The pea kinase (PsCCaMK) was upregulated in roots in response to low temperature and increased salinity. Exogenous Ca2+ application increased the kinase level and the response was faster than that obtained following stress application. Low temperature-mediated, but not salinity-mediated stress kinase increase was inhibited by the application of EGTA and W7, a CaM inhibitor. The purification of PsCCaMK using immuno-affinity chromatography resulted in coelution of the kinase with another polypeptide of molecular mass 40 kDa (p40). Western blot revealed the presence of PsCCaMK in nuclear protein extracts and was found to phosphorylate p40 in vitro. Gel mobility shift and South-Western analysis showed that p40 is a DNA-binding protein and it interacted specifically with one of the cis acting elements of the Arabidopsis CaM5 gene (AtCaM5) promoter. The binding of p40 to the specific elements in the AtCaM5 promoter was dependent of its dephosphorylated state. Our results suggest that p40 could be an upstream signal component of the stress responses.     

Impact of males on the progeny sex ratio of Campoletis chlorideae (Hym., Ichneumonidae), a parasitoid of Helicoverpa armigera (Hübner) (Lep., Noctuidae)

Abstract: The endoparasitoid Campoletis chlorideae and its host Helicoverpa armigera were reared in the laboratory to determine the progeny sex ratio of C. chlorideae in the presence and absence of male parasitoids. It was observed that the presence of male parasitoids affects the progeny sex ratio by decreasing the number of females in the offspring population, i.e. a significant increase in the proportion of males was observed in united sexes. Therefore, while constructing the life table of the parasitoid, the effect of presence of male parasitoids, should be considered together with other factors, which decreases the efficiency of the parasitoid.     

A highly specific heterologous enzyme-linked immunosorbent assay for measuring testosterone in plasma using antibody-coated immunoassay plates or polypropylene tubes.

A highly specific and sensitive enzyme-linked immunosorbent assay, using a heterologous combination of antiserum raised against testosterone-3-(O-carboxymethyl) oxime-bovine serum albumin and penicillinase-labeled testosterone-11 beta-carboxymethyl ether, was developed for measuring testosterone in human plasma. Immunoassay plates (96 wells) provided a sensitivity of 2.5 pg/well. This was achieved by maintaining the molar ratios of steroid to enzyme between 10 and 20. The assay was very specific for testosterone and did not show any cross-reaction with the related C19 steroids tested. Replacement of immunoassay plates with the locally available polypropylene tubes raised the detection limits to 25 pg/tube, but improved the range of doses of testosterone that could be measured up to 10,000 pg. The antiserum to testosterone derivative was linked to both immunoassay plates and polypropylene tubes through immunochemical bridges. Comparison of testosterone values of 52 plasma specimens obtained by both solid phase methods with those of radioimmunoassay showed good correlation.