Interaction of pollen-specific actin-depolymerizing factor with actin

We have examined the interaction of recombinant lily pollen ADF, LlADF1, with actin and found that whilst it bound both G- and F-actin, it had a much smaller effect on the polymerization and depolymerization rate constants than the maize vegetative ADF, ZmADF3. An antiserum specific to pollen ADF, antipADF, was raised and used to localize pollen ADF in daffodil--a plant in which massive reorganizations of the actin cytoskeleton have been seen to occur as pollen enters and exits dormancy. We show, for the first time, an ADF decorating F-actin in cells that did not result from artificial increase in ADF concentration. In dehydrated pollen this ADF : actin array is replaced by actin : ADF rodlets and aggregates of actin, which presumably act as a storage form of actin during dormancy. In germinated pollen ADF has no specific localization, except when an adhesion is made at the tip where actin and ADF now co-localize. These activities of pollen ADF are discussed with reference to the activities of ZmADF3 and other members of the ADF/cofilin group of proteins.     

Effect of Bracteoles on Seed Germination and Dispersal of Two Species of Atriplex

The influence of bracteoles on the germination response of asalt marsh annual, Atriplex prostrata, and a salt desert perennial,A. griffithii, was determined. Attached bracteoles did not inhibitgermination of A. prostrata but completely inhibited germinationof A. griffithii seeds. Germination of seeds ofA. griffithiiwas also somewhat inhibited in the presence of detached bracteoles.The osmotic potential of dissolved substances in water-saturatedbracteoles was -4.8 ± 0.05 MPa for A. griffithii and-2.4 ± 0.15 MPa for A. prostrata. Ash content of bracteoleson a dry weight basis was 28.7 ± 0.37% for A. prostrataand 30.0 ± 0.29% for A. griffithii. The presence of relativelyhigh concentrations of dissolved salts in bracteoles may explainthe reduced germination of A. griffithii. Germination of seedsof the perennial A. griffithii may also be inhibited mechanicallyby the presence of persistent bracteoles, whereas the annualA. prostrata has ephemeral bracteoles that may serve to limitgermination in the autumn but are not present during the normalspring germination period. Bracteoles could affect the dispersalof seeds by water since some fruiting structures of A. griffithiiand A. prostrata are able to float in 1.0% NaCl solutions for5 and >30 d, respectively, compared with a maximum of 4 and3 d for seeds without bracteoles. Fruiting structures of A.prostrata floated for longer over a range of salinities thandid those ofA. griffithii ; this may play a significant rolein the dispersal of this salt marsh species. Copyright 2001Annals of Botany Company Atriplex, bracteoles, dispersal, flotation, germination, salinity, temperature     

Industrial attributes of β-glucanase produced by Bacillus sp. CSB55 and its potential application as bio-industrial catalyst

Bioprocess and Biosystems Engineering - The β-glucanase produced from Bacillus sp. CSB55 not only depicts the potent industrial characteristics but also relates as bio-industrial catalyst...     

Enhanced proteolysis leads to pre-mature cell death under the influence of elicitor like mycelial components from karnal bunt (tilletia indica) pathogen in wheat callus cultures

Calli raised from mature embryos of susceptible wheat cultivar WH 542 were used in the present study as in vitro bioassay system to study the influence of disease determinant(s) of Karnal bunt (Tilletia indica), a semi-biotrophic fungal pathogen of wheat. Influence of elicitor and conditioned medium (CM) prepared from fungal cultures of T. indica was investigated on induction of programmed cell death (PCD). Induction of PCD was observed as hypersensitive response (HR) in terms of browning at localized regions of callus cultures and induction of proteolytic enzyme(s). Elicitor treated calli showed higher induction of protease activity than untreated and CM-treated cultures, which showed not much change in the activity. It was further substantiated by gel protease assay and activation of caspase-3 like protein(s) in callus cultures that clearly suggested the presence of signaling molecule(s) in the fungal elicitor preparation rather than in conditioned medium. This study further demonstrated that only elicitor preparation possesses such molecule(s), which might be cell wall bound components, rather than secretory in nature as CM was unable to induce PCD in wheat callus cultivars.     

PRIMARY STRUCTURE OF ALLATOSTATIN 4, A NEVROPEPTIDE INHIBITOR OF JUVENILE HORMONE SYNTHESIS

Abstract Isolation and identification of allatostatin 4 (AST 4) from crude brain extracts of female Diploptera punctata are described. Synthetic analogues of allatostatin 4 truncated from the N-terminal were evaluated to gain some knowledge of structure-activity correlation. AST 4 reversibly inhibits the biosynthesis of JH in vitro . AST 4 has the following sequence: Asp-Arg-Leu-Tyr-Ser-Phe-Gly-Leu-NH₂. This neurohormone (AST 4) has no sequence similarity with any known neuropeptide from other organisms. Synthetic AST 4 as well as truncation fragments, including two with the five and six amino acids terminal residues deleted showed in vitro activity distinguishable from that of the native allatostatin.