Chromatic adaptation in a mutant of Fremyella diplosiphon incapable of phycoerythrin synthesis.

A mutant of the chromatically adapting cyanobacterium Fremyella diplosiphon, incapable of phycoerythrin synthesis but responding to wavelength modulation of its biliprotein content, was isolated. The biliprotein composition of the mutant and of the wild type were identical after growth in red light, but green light induced, in the mutant, the synthesis of a biliviolin-type chromophore bound to some of the alpha subunits of its phycocyanin. Implications of the results on the regulation and possible pathways of biliprotein biosynthesis are discussed.

The cyanobacteriales: a legitimate order based on the type strain Cyanobacterium stanieri?

As a logical consequence of the definition of a bacterium (Stanier and van Niel, 1962), R. Y. Stanier created the name "cyanobacteria" as a replacement for "blue-green algae".

Effects of chromatic illumination on cyanobacterial phycobilisomes. Evidence for the specific induction of a second pair of phycocyanin subunits in Pseudanabaena 7409 grown in red light.

Pseudanabaena 7409 is a chromatically cyanobacterium which photocontrols the synthesis of both phycoerythrin and phycocyanin [Tandeau de Marsac (1977) J. Bacteriol. 130, 82--91].

Wavelength modulation of phycoerythrin synthesis in Synechocystis sp. 6701.

The spectral dependence of phycoerythrin synthesis has been studied in a unicellular photautotrophic cyanobacterium, Synechocystis sp. 6701, in which phycoerythrin synthesis alone is under chromatic control. Cells were partially depleted of their phycobiliprotein pigments through nitrate starvation in the light.

Molecular composition of cyanobacterial phycobilisomes.

Phycobilisomes isolated from eight different species of cyanobacteria contain in addition to the light-harvesting phycobiliproteins, a small number of colorless polypeptides with molecular weights higher than those of the chromopolypeptide subunits of the phycobiliproteins. In the phycobilisomes of the species examined, from four to nine colorless polypeptides were resolved by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Those of highest molecular weight (70,000-120,000) also occurred in the washed membrane fraction of the cell and may therefore be derived from the thylakoids, to which the phycobilisomes are attached in vivo.

Physico-chemical and immunological properties of allophycocyanins.

Allophycocyanins were purified from diverse cyanobacteria and one rhodophytan alga (Cyanidium caldarium). The native proteins are trimeric molecules with the structure (alpha beta)3. Representative native allophycocyanins and their alpha and beta subunits were characterized with respect to molecular weight, amino acid composition, isoelectric point, absorption and fluorescence spectra and immunological properties.

A comparison of cryptophytan phycocyanins.

The spectroscopically different phycocyanins present in the type strain of Hemiselmis virescens, Millport 64, and in a second strain of this cryptophytan species, Plymouth 157, have been purified and compared. They are similar in native molecular weight and in subunit structure, both containing alpha and beta subunits with molecular weights of approximately 10000 and 19000 respectively. However, they do not have the same chromophore composition.

Role of allophycocyanin as light-harvesting pigment in cyanobacteria.

Photosynthetic action spectra of several cyanobacteria show a peak at about 650 nm, the height of which is correlated with allophycocyanin content in the strains examined. Allophycocyanin harvests light more efficiently than do phycocyanin and phycoerythrin. The contribution of chlorophyll a absorption to photosynthetic activity is barely detectable in cells of normal pigment composition.

Comparative immunology of algal biliproteins.

The three spectroscopically distinct classes of phycobiliproteins characteristic of the Cyanophyta and Rhodophyta-phycocyanins, allophycocyanins, and phycoerythrins-share no common antigenic determinants detectable by the Ouchterlony double diffusion technique. Each class of phycobiliprotein, from both Cyanophyta and Rhodophyta, possesses a strong determinant common to all members of that class. With respect to an antiserum directed against a specific cyanophytan biliprotein, all heterologous biliproteins of the same class are immunologically identical, as shown by the fact that absorption with a given heterologous antigen simultaneously eliminates crossreactions with other heterologous antigens.

Subunit structure of the phycobiliproteins of blue-green algae.

The phycobiliproteins of the blue-green algae Synechococcus sp. and Aphanocapsu sp. were characterized with respect to homogeneity, isoelectric point, and subunit composition.

Comparative study of the structure of gas vacuoles.

The fine structure of gas vacuoles was examined in two blue-green algae, two green bacteria, three purple sulfur bacteria, and two halobacteria. The gas vacuole is a compound organelle, composed of a variable number of gas vesicles. These are closed, cylindrical, gas-containing structures with conical ends, about 80 to 100 nm in width and of variable length, ranging from 0.

Basal organelles of bacterial flagella.

Liberated by enzymatic lysis of the cells, the flagella of Rhodospirillum rubrum, R. molischianum, and R. fulvum all have a similar structure.

THE FINE STRUCTURE OF STALKED BACTERIA BELONGING TO THE FAMILY CAULOBACTERACEAE.

The fine structure of a series of stalked bacteria belonging to the genera Caulobacter and Asticcacaulis has been examined in thin sections. The cell wall has the multilayered structure typical of many Gram-negative bacteria, and continues without interruption throughout the length of the stalk. The core of the stalk, continuous with the cytoplasmic region of the cell, is enclosed in an extension of the cell membrane, and contains a system of internal membranes: it is devoid of ribosomes and nucleoplasm.

THE FINE STRUCTURE OF GREEN BACTERIA.

The fine structure of several strains of green bacteria belonging to the genus Chlorobium has been studied in thin sections with the electron microscope. In addition to having general cytological features typical of Gram-negative bacteria, the cells of these organisms always contain membranous mesosomal elements, connected with the cytoplasmic membrane, and an elaborate system of isolated cortical vesicles, some 300 to 400 A wide and 1000 to 1500 A long. The latter structures, chlorobium vesicles, have been isolated in a partly purified state by differential centrifugation of cell-free extracts.

The fine structure of Rhodospirillum rubrum.

The fine structure of Rhodospirillum rubrum grown under a series of defined conditions has been examined in thin sections prepared by the methods of Ryter and Kellenberger. In cells grown anaerobically at different light intensities, the abundance of 500 A membrane-bounded vesicles in the cytoplasm is inversely related to light intensity, and directly related to cellular chlorophyll content. When the chlorophyll content of the cell is low, the vesicles are exclusively peripheral in location; they extend more deeply into the cytoplasm when the chlorophyll content is high.