A putative GDP–GTP exchange factor is required for development of the excretory cell in Caenorhabditis elegans

The Caenorhabditis elegans excretory cell extends tubular processes, called canals, along the basolateral surface of the epidermis. Mutations in the exc-5 gene cause tubulocystic defects in this canal. Ultrastructural analysis suggests that exc-5 is required for the proper placement of cytoskeletal elements at the apical epithelial surface. exc-5 encodes a protein homologous to guanine nucleotide exchange factors and contains motif architecture similar to that of FGD1, which is responsible for faciogenital dysplasia. exc-5 interacts genetically with mig-2, which encodes Rho GTPase. These results suggest that EXC-5 controls the structural organization of the excretory canal by regulating Rho family GTPase activities.     

Analysis of common antigen of flagella in Bacillus cereus and Bacillus thuringiensis

Abstract Flagellar antigen of Bacillus cereus H.1 was purified and tested for serodiagnostic antigen by ELISA. The antibody against the flagellar antigen of B. cereus H.1 reacted not only with the homologous specific antigen but also reacted with the flagellar antigens of 23 strains of B. cereus . This common flagellar antigen of B. cereus was found to be due to 61-kDa protein by SDS-PAGE and immunoblot assay. Monoclonal antibody H15A5 against common antigenic epitope of B. cereus also reacted with flagellar antigens of 21 strains of Bacillus thuringiensis by ELISA. This monoclonal antibody reacted with the 61-kDa protein of the flagella of B. cereus H.1 and H.2 and B. thuringiensis Kurstaki HD1, Alesti and Aizawai juroi by immunoblot analysis. These results indicated that the common antigenic epitope of the 61-kDa protein existed in the flagella both of B. cereus and B. thuringiensis .     

Reconstitution and Characterization of H+-Translocating ATPase from the Plasma Membrane of Phaseolus mungo L. Roots

Plasma membrane H⁺-translocating ATPase was partially purifiedfrom mung bean (Phaseolus mungo L.) roots and reconstitutedinto soybean phospholipid (asolectin) liposomes by the n-octylglucosidedilution method. The resulting proteoliposomes were mainly unilamellarvesicles ranging in size from 0.05 to 0.2 µm. The existenceof ATP-drived H⁺-pumping across the proteoliposomes was demonstratedby the quenching of quinacrine fluorescence in the presenceof Mg²⁺. The quenching could be abolished by an uncoupler, FCCP,and an inhibitor of H⁺-translocating ATPase, vanadate. The reconstitutedATPase consisted of three major polypeptides of 105 KDa, 67KDa and 57 KDa. Its pH optimum, divalent cation stimulationand vanadate sensitivity were similar to those of partiallypurified ATPase. However, the specificity toward ATP was muchgreater following reconstitution. Also reconstitution reducedthe degree of inhibition by DCCD. Local anesthetics (e.g. dibucaine)had no effect on H⁺-pumping activity but increased the ATPaseactivity when proteoliposomes were reconstituted in their presence. (Received May 2, 1986; Accepted October 17, 1986)     

Mutagenicity of the reaction products of carbazole in the presence of nitrogen dioxide and nitrocarbazole

The mutagenicity of the photochemical reaction products of carbazole in the presence of nitrogen dioxide (NO2) and nitrocarbazole was investigated using a high-pressure mercury lamp (100 W). Samples extracted from the photochemical reaction products of carbazole with NO2 were more mutagenic than those of acridine and phenazine with NO2 for Salmonella typhimurium strain TA98 in the absence of S9 mix with a trend toward detoxification in the presence of the metabolic system. The mutagenicity of the photochemical reaction products of carbazole with NO2 were higher than those of the reaction products of carbazole with a mixture of NO2 and sulfur dioxide (SO2) and no irradiation. Mononitro- and dinitro-carbazole in the samples extracted from the reaction products were analyzed by mass spectrometry. It was suggested that mononitrocarbazole, which seemed to be weakly mutagenic, and dinitrocarbazole were readily formed by the reaction of carbazole with NO2, and that the other high-potency mutagens were formed by the photochemical reaction of carbazole with NO2 with irradiation by light.     

Vanadium K-edge X-ray-absorption spectroscopy of the functioning and thionine-oxidized forms of the VFe-protein of the vanadium nitrogenase from Azotobacter chroococcum.

Vanadium K-edge X-ray-absorption spectra were collected for samples of thionine-oxidized, super-reduced (during enzyme turnover) and dithionite-reduced VFe-protein of the vanadium nitrogenase of Azotobacter chroococcum (Acl*). Both the e.x.a.f.s and the x.a.n.e.s. (X-ray-absorption near-edge structure) are consistent with the vanadium being present as part of a VFeS cluster; the environment of the vanadium is not changed significantly in different oxidation states of the protein. The vanadium atom is bound to three oxygen (or nitrogen), three sulphur and three iron atoms at 0.215(3), 0.231(3) and 0.275(3) nm respectively.     

EPR characterization of the iron-sulfur-containing NADH-ubiquinone oxidoreductase of the Escherichia coli aerobic respiratory chain

The energy coupled NADH-ubiquinone (Q) oxidoreductase segment of the respiratory chain of Escherichia coli GR19N has been studied by EPR spectroscopy. Previously Matsushita et al. [(1987) Biochemistry 26, 7732-7737] have demonstrated the presence of two distinct NADH-Q oxidoreductases in E. coli membrane particles and designated them NADH dh I and NADH dh II. Although both enzymes oxidize NADH, only NADH dh I is coupled to the formation of the H+ electrochemical gradient. In addition to NADH, NADH dh I oxidizes nicotinamide hypoxanthine dinucleotide (deamino-NADH), while NADH dh II does not. In membrane particles we have detected EPR signals arising from four low-potential iron-sulfur clusters, one binuclear, one tetranuclear, and two fast spin relaxing g perpendicular = 1.94 type clusters (whose cluster structure has not yet been assigned). The binuclear cluster, temporarily designated [N-1]E, shows an EPR spectrum with gx,y,z = 1.92, 1.935, 2.03 and the Em7.4 value of -220 mV (n = 1). The tetranuclear cluster, [N-2]E, elicits a spectrum with gx,y,z = 1.90, 1.91, 2.05 and an Em7.4 of -240 mV (n = 1). These two clusters have been shown to be part of the NADH dh I complex by stability and inhibitor studies. When stored at 4 degrees C, both clusters are extremely labile as is the deamino-NADH-Q oxidoreductase activity. Addition of deamino-NADH in the presence of piericidin A results in nearly full reduction of [N-2]E within 17 s. In membrane particles pretreated with piericidin A, the cluster [N-1]E is only partly reducible by deamino-NADH and shows an altered line shape.(ABSTRACT TRUNCATED AT 250 WORDS)     

The immunohistolocalization of carbonic anhydrase III in the submandibular gland of rats and hamsters

Summary Carbonic anhydrase III has been localized using the avidin-biotin-glucose oxidase complex (ABC) method in the submandibular gland of the rat and hamster. This isozyme, which is predominant in skeletal muscle, was observed in intercalated duct, striated duct and excretory duct cells in the rat submandibular glands. In contrast, only some striated duct cells in hamster submandibular glands were stained.     

Filtering rates on natural bacteria by Daphnia longispina and Eodiaptomus japonicus in Lake Biwa

Filtering rates on [³H]thymidine-labelled natural unattachedbacteria and that on [¹⁴C]bicarbonate-labelled natural planktonwhich pass through the 25 µm-mesh-size screen were measuredfor Daphnia longispina and Eodiaptomus japonicus in Lake Biwa.Errors associated with the radioisotope technique, i.e the lossof labels after feeding trials and the self-absorption of thebeta emittance of ³H, were checked and corrected for the calculationof the filtering rates. It was suggested that Daphnia collectsbacteria efficiently, although the efficiency is somewhat variabledepending on food particle composition (i.e. presence and absenceof larger particles) and feeding condition (i.e. animal densityand physical disturbance). By contrast, copepodites of Eodiaptomuswere suggested to be less efficient bacteria feeders. Food resourceexploitation strategies of these two co-existing zooplanktersare discussed.     

Characterization of a human immunodeficiency virus neutralizing monoclonal antibody and mapping of the neutralizing epitope.

A monoclonal antibody was produced to the exterior envelope glycoprotein (gp120) of the human T-cell lymphotropic virus (HTLV)-IIIB isolate of the human immunodeficiency virus (HIV). This antibody binds to gp120 of HTLV-IIIB and lymphadenopathy-associated virus type 1 (LAV-1) and to the surface of HTLV-IIIB- and LAV-1-infected cells, neutralizes infection by cell-free virus, and prevents fusion of virus-infected cells. In contrast, it does not bind, or weakly binds, the envelope of four heterologous HIV isolates and does not neutralize heterologous isolates HTLV-IIIRF and HTLV-IIIMN. The antibody-binding site was mapped to a 24-amino-acid segment, using recombinant and synthetic segments of HTLV-IIIB gp120. This site is within a segment of amino acid variability known to contain the major neutralizing epitopes (S. D. Putney, T. J. Matthews, W. G. Robey, D. L. Lynn, M. Robert-Guroff, W. T. Mueller, A. J. Langlois, J. Ghrayeb, S. R. Petteway, K. J. Weinhold, P. J. Fischinger, F. Wong-Staal, R. C. Gallo, and D. P. Bolognesi, Science 234:1392-1395, 1986). These results localize an epitope of HIV type-specific neutralization and suggest that neutralizing antibodies may be effective in controlling cell-associated, as well as cell-free, virus infection.     

Salt tolerance of the reed plant Phragmites communis

Reed plants ( Phragmites communis Trinius) were grown at NaCl concentrations up to 500 m M and their growth, mineral contents and leaf blade osmotic potential were determined. Addition of NaCl up to 300 m M did not affect growth significantly. Sucrose, Cl^-and Na⁺ concentrations in the shoots increased with the salinity of the medium and the shoot water content decreased. K⁺ always contributed most to the leaf osmotic potential. Even in the presence of 250 m M NaCl in the rooting medium, the leaf blade contained only 50 mM Na⁺, suggesting that the plants have an efficient mechanism for Na⁺ exclusion. ²²Na⁺ uptake experiments suggested that the retranslo-cation of absorbed Na⁺ from shoots to the rooting medium lowered the uptake of Na⁺.