Putative function of cytochrome b559 as a plastoquinol oxidase.

The function of cytochrome b559 (cyt b559) in photosystem II (PSII) was studied in a tobacco mutant in which the conserved phenylalanine at position 26 in the beta-subunit was changed to serine. Young leaves of the mutant showed no significant difference in chloroplast ultra structure or in the amount and activity of PSII, while in mature leaves the size of the grana stacks and the amount of PSII were significantly reduced. Mature leaves of the mutant showed a higher susceptibility to photoinhibition and a higher production of singlet oxygen, as shown by spin trapping electron paramagnetic resonance (EPR) spectroscopy.

Thylakoid membrane reduction affects the photosystem stoichiometry in the cyanobacterium Synechocystis sp. PCC 6803.

Biogenesis of thylakoid membranes in both chloroplasts and cyanobacteria is largely not understood today. The vesicle-inducing protein in plastids 1 (Vipp1) has been suggested to be essential for thylakoid membrane formation in Arabidopsis (Arabidopsis thaliana), as well as in the cyanobacterium Synechocystis sp. PCC 6803, although its exact physiological function remains elusive so far.

The cyanobacterial homologue of the RNA chaperone Hfq is essential for motility of Synechocystis sp. PCC 6803.

The ssr3341 locus was previously suggested to encode an orthologue of the RNA chaperone Hfq in the cyanobacterium Synechocystis sp. strain PCC 6803. Insertional inactivation of this gene resulted in a mutant that was not naturally transformable and exhibited a non-phototactic phenotype compared with the wild-type.

A new purple sulfur bacterium isolated from a littoral microbial mat, Thiorhodococcus drewsii sp. nov.

A new strain of purple sulfur bacterium was isolated from a marine microbial mat sampled in Great Sippewissett Salt Marsh at the Atlantic coast (Woods Hole, Mass., USA). Single cells of strain AZ1 were coccus-shaped, highly motile by means of a single flagellum, and did not contain gas vesicles.

Evidence that cytochrome b559 mediates the oxidation of reduced plastoquinone in the dark.

The function of cytochrome b(559) in photosystem II (PSII) was investigated using a mutant created in tobacco in which the conserved phenylalanine at position 26 in the beta-subunit (PsbF) was changed to serine (Bock, R., Kössel, H., and Maliga, P.

Isolation and characterization of two hydrocarbon-degrading Bacillus subtilis strains from oil contaminated soil of Kuwait.

Two strains of hydrocarbon-utilizing bacteria were isolated from soil samples of the Kuwait Burqan oil field at a temperature of 37 degrees C. The bacteria were motile endospore-forming rods with slight differences in their metabolic patterns and 16S rRNA sequence. Vegetative cells of the strains designated as AHI and AHII had an ultrastructure typical of gram-positive bacteria and showed gram-positive staining.

Bacteriochlorophyllc formation and chlorosome development inChloroflexus aurantiacus.

The dependence of chlorosome development on bacteriochlorophyll (BChl)c synthesis was studied with the phototrophic green bacteriumChloroflexus aurantiacus. By selecting defined culture conditions, three possibilities could be identified. Upon addition of 5-aminolevulinic acid, cells of resting cultures increased their specific BChlc contents as well as the volumes of already existing chlorosomes.

Phylogenetic positions of novel aerobic, bacteriochlorophyll a-containing bacteria and description of Roseococcus thiosulfatophilus gen. nov., sp. nov., Erythromicrobium ramosum gen. nov., sp. nov., and Erythrobacter litoralis sp. nov.

We analyzed the 16S ribosomal DNAs of three obligately aerobic, bacteriochlorophyll a-containing bacteria, "Roseococcus thiosulfatophilus," "Erythromicrobium ramosum," and new isolate T4T (T = type strain), which was obtained from a marine cyanobacterial mat. "Roseococcus thiosulfatophilus" is a member of the alpha-1 subclass of the Proteobacteria and is moderately related to Rhodopila globiformis, Thiobacillus acidophilus, and Acidiphilium cryptum (level of sequence similarity, 90%). "Erythromicrobium ramosum" and isolate T4T are closely related to Erythrobacter longus and Porphyrobacter neustonensis (level of sequence similarity, 95%).

Attachment of Blastocrithidia triatomae (trypanosomatidae) by flagellum and cell body in the midgut of the reduviid bug Triatoma infestans.

The pathology and attachment of Blastocrithidia triatomae in two regions of the midgut of the reduviid bug Triatoma infestans (the stomach and the small intestine) were investigated by electron microscopy. In both regions the extracellular-membrane layers and the apical microvilli were often reduced, and some cells of the intestinal wall were vacuolated. In the stomach two types of attachment occurred: Flagella with intraflagellar swellings lay over and between the apices of the microvilli of the stomach cells, and in microvilli-free regions the cell body of B.

Ultrastructural and electron spectroscopic analyses of cyanobacteria and bacteria.

The extracellular sheath material and some intracellular cell components of cyanobacteria and phosphate-accumulating sewage bacteria were analysed by electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS). The specimens were embedded in water-soluble Nanoplast resin without any previous fixation and ultrathin sections were examined in a Zeiss CEM 902 microscope. A high sulphur content was detected in the inner sheath of the cyanobacterium Gloeothece.

Fine-structural and chemical analyses on inner and outer sheath of the cyanobacterium Gloeothece sp. PCC 6909.

Cells of the unicellular cyanobacterium Gloeothece sp. PCC 6909 are surrounded by an inner (enclosing 1-2 cells) and an outer (enclosing cell groups) sheath. Using conventional Epon-embedding in combination with ruthenium-red staining, the inner and outer sheaths appeared similar and displayed multiple bands of electron-dense subunits.

Further electron microscopic studies on the expression of Escherichia coli group II capsules.

The de novo expression of Escherichia coli K1, K5, and K12 capsules was analyzed with immunoelectron microscopy in temperature upshift experiments, with upshift from 18 degrees C (capsule restrictive) to 37 degrees C (capsule permissive). Newly produced capsular polysaccharides appeared at the cell surface atop membrane adhesion sites (Bayer's junctions). After plasmolysis of the bacteria at an early expression stage, the capsular polysaccharides were labeled at discrete sites in the periplasm by the immunogold technique.

Expression of the Escherichia coli K5 capsular antigen: immunoelectron microscopic and biochemical studies with recombinant E. coli.

The capsular K5 polysaccharide, a representative of group II capsular antigens of Escherichia coli, has been cloned previously, and three gene regions responsible for polymerization and surface expression have been defined (I. S. Roberts, R.

Evidence for phagosome-lysosome fusion in Mycobacterium leprae-infected murine Schwann cells.

Murine Schwann cells were infected with viable armadillo-derived Mycobacterium leprae in vitro, and the lysosomal marker enzyme, acid phosphatase, was stained by the Gomori reaction. Electron microscopic analysis revealed that Schwann cells infected with M. leprae possess acid phosphatase and that lysosomes fuse with infected phagosomes.

Race cultivar-specific differences in callose deposition in soybean roots following infection with Phytophthora megasperma f.sp. glycinea.

Primary roots of soybean (Glycine max (L.), Merrill, cv. Harosoy 63) seedlings were inoculated with zoospores from either race 1 (incompatible, host resistant) or race 3 (compatible, host susceptible) of Phytophthora megasperma f.

Nonfimbrial, mannose-resistant adhesins from uropathogenic Escherichia coli O83:K1:H4 and O14:K?:H11.

Nonfimbrial, mannose-resistant hemagglutinins (nonfimbrial adhesions [NFA] NFA-1 and NFA-2) were extracted from two agar-grown urinary isolates of Escherichia coli strains 827 (O83:K1:H4) and 54 (O14:K?:H11). The proteins were purified to homogeneity by ammonium sulfate precipitation and column chromatography. Nonfimbrial adhesins are soluble proteins, which tend to form aggregates of molecular weight above 10(6).

The T cell-specific serine proteinase TSP-1 is associated with cytoplasmic granules of cytolytic T lymphocytes.

This study describes the localization of the previously purified T cell-specific serine proteinase, termed TSP-1 (M. M. Simon et al.

Skin reactivity of unsensitized monkeys upon challenge with staphylococcal enterotoxin B: a new approach for investigating the site of toxin action.

The correlation between skin tests and emetic responses in unsensitized monkeys was used to elucidate the cellular site of action of staphylococcal enterotoxin B (SEB). Evidence is presented that SEB administered intradermally provoked immediate-type skin reactions associated with mild degranulation of cutaneous mast cells. The cytoplasma showed signs of synthetic and metabolic activity, with formation of vesicles and increased prominence of mitochondria.

Immunoelectron microscopic studies on the localization of peptidoglycan peptide subunit pentapeptides in bacterial cell walls.

The peptide subunit pentapeptide H-L-Ala-D-Glu(L-Lys-D-Ala-D-Ala-OH)-NH2 of peptidoglycan was localized in the cell walls of several Gram-positive bacteria employing the indirect immunoferritin technique. Specific antibodies to the D-alanyl-D-alanine moiety of non-crosslinked peptide subunit pentapeptide were raised in rabbits by immunization with synthetic immunogen albumin-(CH2CO-Gly-L-Ala-L-Ala-D-Ala-D-Ala-OH)39. Specificity of these antibodies for the peptide subunit pentapeptide and not for the peptide subunit tetrapeptide was corroborated in a Farr-type radio-active hapten binding assay.

Fusion of liposomes and chromatophores of Rhodopseudomonas capsulata: effect on photosynthetic energy transfer between B875 and reaction center complexes.

The photosynthetic chromatophore membranes of Rhodopseudomonas capsulata were fused with liposomes to investigate the effects of lipid dilution on energy transfer between the bacteriochlorophyll-protein complexes of this membrane. Phosphatidylcholine-containing liposomes were mixed with chromatophores at pH 6.0 to 6.

Electron microscopic study showing antibody-independent binding of C1q, a subcomponent of the first component of complement, to serum-sensitive salmonellae.

Effective serum-mediated killing of sensitive gram-negative bacteria requires all the complement components. In the preimmune phase the antibody-independent interaction of the first component of complement, C1, with the bacteria might be especially important. Electron microscopic studies showed that the C1 subcomponent C1q binds only to the serum-sensitive R form of Salmonella minnesota and not to the serum-resistant S form.

Isolation of surface lectins of GH3 cells from whole cells and isolated plasma membranes.

Lectins localized in the plasma membranes seem to be of special importance for the intercellular interaction mechanisms. We describe the isolation of mannose-binding proteins by Triton X-100 extraction and affinity chromatography on agarose-bound mannose. The isolation procedure was performed with whole GH3 cells as well as with isolated plasma membranes.

The differentiation of the photosynthetic apparatus and the intracytoplasmic membrane in cells of Rhodopseudomonas capsulata upon variation of light intensity.

In cells of Rhodopseudomonas capsulata, grown at growth limiting light intensity (7 W x m-2), the cellular bacteriochlorophyll (Bchl) content increased 13-fold, the Bchl concentration of membranes 3.4 fold, the concentration of reaction centers in membranes 1.6-fold, the size of the photosynthetic unit twofold, the concentration of carotenoids in membranes 2.