| cyanobacterial ribonucleic acid polymerases recognize lambda promoters. | we compared the initiation specificities in vitro of deoxyribonucleic acid-dependent ribonucleic acid polymerases purified from two cyanobacteria, fremyella diplosiphon and anacystis nidulans, and from escherichia coli. a restriction fragment made from lambda deoxyribonucleic acid was used as a template. the cyanobacterial and e. coli ribonucleic acid polymerases recognized the same lambda promoters but exhibited different sensitivities to the inhibitor heparin, suggsesting differences in the st ... | 1979 | 159286 |
| studies on plant bile pigments, vii. preparation and characterization of phycobiliproteins with chromophores chemically modified by reduction. | the reversible denaturation and reduction with dithionite has been studied for the phycobiliproteins, c-phycocyanin (1) and allophycocyanin (2) from spirulina platensis, and c-phycoerythrin (4) from fremyella diplosiphon (both cyanobacteria). by treatment with sodium dithionite, the chromophores are selectively reduced at the central (c-10) methine bridge, producing pigments with bilirubinoid (lambda max = 418 nm from 1 and 2), and vinylpyrroloc (lambda max= 300 nm from 4) chromophores. the exte ... | 1979 | 488917 |
| subunits of phycoerythrin from fremyella diplosiphon: chemical and immunochemical characterization. | the alpha and beta subunits of the phycobiliprotein, phycoerythrin, isolated from the filamentous blue-green alga, fremyella diplosiphon, have been separated by chromatography on bio-rex 70 ion exchange resin. analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis shows no detectable cross-contamination of these subunit preparations. the molar extinction coefficients at 552 nm of the alpha and beta subunits in 8 m urea are 25,549 and 48,456, respectively. the amino acid compositio ... | 1975 | 804315 |
| complementation of a red-light-indifferent cyanobacterial mutant. | many cyanobacteria alter their phycobilisome composition in response to changes in light wavelength in a process termed complementary chromatic adaptation. mutant strains fdr1 and fdr2 of the filamentous cyanobacterium fremyella diplosiphon are characterized by aberrant chromatic adaptation. instead of adjusting to different wavelengths of light, fdr1 and fdr2 behave as if they are always in green light; they do not respond to red light. we have previously reported complementation of fdr1 by con ... | 1992 | 1409650 |
| isolation, crystallization, crystal structure analysis and refinement of b-phycoerythrin from the red alga porphyridium sordidum at 2.2 a resolution. | the light-harvesting pigment-protein complex b-phycoerythrin from the red alga porphyridium sordidum has been isolated and crystallized. b-phycoerythrin consists of three different subunits forming an (alpha beta)6 gamma aggregate. the three-dimensional structure of the (alpha beta)6 hexamer was solved by patterson search techniques using the molecular model of c-phycocyanin from fremyella diplosiphon. the asymmetric unit of the crystal cell (space group p3, with a = b = 111.2 a, c = 59.9 a, alp ... | 1992 | 1469725 |
| characterization of a light-regulated gene encoding a new phycoerythrin-associated linker protein from the cyanobacterium fremyella diplosiphon. | cyanobacteria utilize multimeric protein complexes, the phycobilisomes, as their major light-harvesting antennae. associated with the chromophorylated phycobiliproteins in these complexes are nonpigmented proteins, designated linker proteins. these linker proteins are believed to mediate assembly of the phycobilisome and energy transfer to the photosynthetic reaction center. we cloned and sequenced a gene, cpee, encoding a previously uncharacterized linker protein which is expressed in green lig ... | 1992 | 1522075 |
| characterization of the light-regulated operon encoding the phycoerythrin-associated linker proteins from the cyanobacterium fremyella diplosiphon. | many biological processes in photosynthetic organisms can be regulated by light quantity or light quality or both. a unique example of the effect of specific wavelengths of light on the composition of the photosynthetic apparatus occurs in cyanobacteria that undergo complementary chromatic adaptation. these organisms alter the composition of their light-harvesting organelle, the phycobilisome, and exhibit distinct morphological features as a function of the wavelength of incident light. fremyell ... | 1990 | 1694529 |
| isolation, crystallization, crystal structure analysis and refinement of constitutive c-phycocyanin from the chromatically adapting cyanobacterium fremyella diplosiphon at 1.66 a resolution. | constitutive phycocyanin from cyanobacterium fremyella diplosiphon (calothrix sp. pcc 7601) grown in green light, has been isolated and crystallized. the crystals belong to the space group r3 with cell constants a = b = 180.26 a, c = 61.24 a, alpha = beta = 90 degrees, gamma = 120 degrees. the crystal structure has been determined by patterson search techniques using the molecular model of c-phycocyanin from the cyanobacterium agmenellum quadruplicatum. the asymmetric unit of the crystal cell co ... | 1991 | 1899708 |
| the amino-acid sequence of three proteins of photosystem i of the cyanobacterium fremyella diplosiphon (calothrix sp pcc 7601). | three proteins containing 138 amino acids (psad protein), 80 amino acids (psac protein) and 66 amino acids (psae protein) of the photosystem i (ps i) complex of the cyanobacterium fremyella diplosiphon (calothrix sp pcc 7601) were isolated and sequenced. comparison with previously known sequences showed a close relationship to homologous proteins of nostoc, another filamentous cyanobacterium. | 1991 | 1930733 |
| role of electrostatic interaction in the stability of the hexamer of constitutive phycocyanin from fremyella diplosiphon. | the role of electrostatic interactions between the charges carried by the titratable groups in the different aggregates of constitutive phycocyanin from fremyella diplosiphon has been studied by using a simple theoretical approach based on the modified tanford-kirkwood model. the electrostatic potential has also been calculated by means of a numerical solution of the linearized poisson-boltzmann equations using the finite-differences technique. the ph dependence of the electrostatic contribution ... | 1991 | 1946325 |
| purification and properties of glutamine synthetases from the cyanobacteria synechocystis sp. strain pcc 6803 and calothrix sp. strain pcc 7601. | glutamine synthetases (gss) from two cyanobacteria, one unicellular (synechocystis sp. strain pcc 6803) and the other filamentous (calothrix sp. strain pcc 7601 [fremyella diplosiphon]), were purified to homogeneity. the biosynthetic activities of both enzymes were strongly inhibited by adp, indicating that the energy charge of the cell might regulate the gs activity. both cyanobacteria exhibited an ammonium-mediated repression of gs synthesis. in addition, the synechocystis sp. showed an inacti ... | 1990 | 1973929 |
| structure and light-regulated expression of phycoerythrin genes in wild-type and phycobilisome assembly mutants of synechocystis sp. strain pcc 6701. | phycoerythrin is a major pigmented component of the phycobilisome, a cyanobacterial light-harvesting complex. it contains bilin-type chromophores that absorb and transfer light energy to chlorophyll protein complexes of the photosynthetic membranes. in many cyanobacteria, phycoerythrin expression is regulated by light wavelength in a response known as chromatic adaptation. green light-grown cells contain higher levels of this biliprotein than do cells grown in red light. the phycoerythrin gene s ... | 1990 | 2106507 |
| a dual function of the notch gene in drosophila sensillum development. | we have investigated the function of the neurogenic gene notch (n) during development of the adult sensilla of drosophila. heat pulses were applied to flies carrying the temperature-sensitive notch allele nts1 at different larval and pupal stages. we can show that the reduction of notch+ function during a short interval prior to the onset of sensillum precursor division, resulting from a heat pulse between 0 and 14 hr after puparium formation (apf), leads to an increase in microchaete precursors ... | 1990 | 2227090 |
| molecular characterization of phycobilisome regulatory mutants of fremyella diplosiphon. | three classes of pigment mutants were generated in fremyella diplosiphon in the course of electroporation experiments. the red mutant class had high levels of phycoerythrin in both red and green light and no inducible phycocyanin in red light. thus, this mutant behaved as if it were always in green light, regardless of light conditions. blue mutants exhibited normal phycoerythrin photoregulation, whereas the inducible phycocyanin was present at high levels in both red- and green-light-grown cell ... | 1989 | 2464582 |
| the complete amino-acid sequence of the alpha and beta subunits of b-phycoerythrin from the rhodophytan alga porphyridium cruentum. | determination of the complete amino-acid sequence of the subunits of b-phycoerythrin from porphyridium cruentum has shown that the alpha subunit contains 164 amino-acid residues and the beta subunit contains 177 residues. when the sequences of b- and c-phycoerythrins are aligned with those of other phycobiliproteins, it is obvious that b-phycoerythrin lacks a deletion at beta-21-22 present in c-phycoerythrin. however, relative to c-phycoerythrin from fremyella diplosiphon (calothrix) (sidler, w. ... | 1989 | 2495805 |
| molecular cloning and nucleotide sequence of a developmentally regulated gene from the cyanobacterium calothrix pcc 7601: a gas vesicle protein gene. | since the gas vesicle protein (gvp) is highly conserved among the different gas-vacuolate prokaryotes, a 29-mer oligonucleotide corresponding to a portion of the anabaena flos-aquae gvp gene was synthesized and used to isolate the gvp structural gene from calothrix pcc 7601 (= fremyella diplosiphon). gas vacuole production in this filamentous cyanobacterium is restricted to hormogonia which occur at a specific stage during the developmental cell cycle. the gvp gene (gvpa) was localized on a 709 ... | 1985 | 2997744 |
| genes encoding major light-harvesting polypeptides are clustered on the genome of the cyanobacterium fremyella diplosiphon. | the polypeptide composition of the phycobilisome, the major light-harvesting complex of prokaryotic cyanobacteria and certain eukaryotic algae, can be modulated by different light qualities in cyanobacteria exhibiting chromatic adaptation. we have identified genomic fragments encoding a cluster of phycobilisome polypeptides (phycobiliproteins) from the chromatically adapting cyanobacterium fremyella diplosiphon using previously characterized dna fragments of phycobiliprotein genes from the eukar ... | 1986 | 3086870 |
| the complete amino-acid sequence of c-phycoerythrin from the cyanobacterium fremyella diplosiphon. | the amino-acid sequences of both subunits of c-phycoerythrin from the cyanobacterium fremyella diplosiphon have been determined. the alpha-subunit contains 164 amino acid residues, two phycoerythrobilin (peb) chromophores and has a molecular mass of 18,368 da (protein: 17,192 da + 2 peb, one peb accounting for 588 da). the beta-subunit consists of 184 residues, three peb chromophores and has a molecular mass of 20,931 da (protein: 19,168 da and 3 peb: 1,764 da). the five peb chromophores (open c ... | 1986 | 3092842 |
| isolation and characterization of light-regulated phycobilisome linker polypeptide genes and their transcription as a polycistronic mrna. | several cyanobacteria adjust both the phycobiliprotein and linker protein composition of the phycobilisome, a light-harvesting complex in cyanobacteria and some eucaryotic algae, to maximize absorption of prevalent wavelengths of light. this process is called complementary chromatic adaptation. we sequenced the amino terminus of a linker polypeptide which is associated with phycocyanin and accumulates to high levels during growth of the cyanobacterium fremyella diplosiphon in red light. a mixed ... | 1987 | 3108238 |
| molecular characterization and evolution of sequences encoding light-harvesting components in the chromatically adapting cyanobacterium fremyella diplosiphon. | the major light-harvesting complex in eukaryotic red algae and prokaryotic cyanobacteria is the phycobilisome, a water-soluble complex located on the outer surface of the photosynthetic membranes and composed of both pigmented phycobiliproteins (85%) and non-pigmented linker (15%) polypeptides. the phycobiliproteins are encoded by a gene family and exhibit varying degrees of sequence homology (25 to 55%). some cyanobacteria can maximize the absorption of prevalent wavelengths of light by adjusti ... | 1988 | 3127591 |
| functional assembly in vitro of phycobilisomes with isolated photosystem ii particles of eukaryotic chloroplasts. | phycobiliproteins obtained by dissociation of phycobilisomes were reassociated in vitro with intact thylakoids or isolated photosystems i and ii preparations obtained from cyanophytes (prokaryotes) or green algae (eukaryotes) to form bound phycobilisome complexes. energy transfer from fremyella diplosiphon phycobiliproteins to chlorophyll a of reaction centers i and ii was measured in: complexes containing intact thylakoids of the cyanophytes f. diplosiphon or anacystis nidulans and the eukaryot ... | 1986 | 3528156 |
| 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 possib ... | 1985 | 3922434 |
| cyanobacterial light-harvesting complex subunits encoded in two red light-induced transcripts. | the major light-harvesting complex in cyanobacteria and red algae, the phycobilisome, is composed of chromophoric and nonchromophoric polypeptides. two linked genes encoding major chromophoric components, the polypeptide subunits of phycocyanin, were isolated from the cyanobacterium fremyella diplosiphon. transcripts from this phycocyanin subunit gene cluster were present as major species in the cyanobacterium grown in red light, but not in cultures maintained in green light. the genes for the s ... | 1985 | 3931221 |
| complementary chromatic adaptation in a filamentous blue-green alga. | fluorescent and red light environments generate greatly different patterns of pigmentation and morphology in fremyella diplosiphon. most strikingly, red-illuminated cultures contain no measurable c-phycoerythrin and have a mean filament length about 10 times shorter than fluorescent-illuminated cultures. c-phycoerythrin behaves as a photoinducible constituent of this alga. spectrophotometric and immunochemical procedures were devised so that c-phycoerythrin metabolism could be studied quantitati ... | 1973 | 4199659 |
| ultrastructure of blue-green algae. | two freshwater blue-green algae, tolypothrix tenuis and fremyella diplosiphon, and an oscillatorialike marine alga, were found to possess structures on the photosynthetic lamellae which appear to correspond to the phycobilisomes of red algae. these homologous structures are important because they contain the phycobilins which are accessory pigments involved in photosynthesis. as in the red algae, the phycobilisomes were attached on the outer side of each lamellae, i.e., the side facing away from ... | 1969 | 5776533 |
| mutations affecting chromatic adaptation in the cyanobacterium fremyella diplosiphon. | the chromatically adapting cyanobacterium, fremyella diplosiphon, when grown in cool white fluorescent light, contains phycoerythrin as its predominant phycobiliprotein. when grown on agar plates with cool white illumination, mutant colonies deficient or devoid of phycoerythrin can be visibly distinguished from the wild type. a total of 25 anomalously pigmented strains were isolated and examined for their ability to chromatically adapt. based on absorption spectra of cell extracts and on fluores ... | 1983 | 6402499 |
| suppressor of hairless is required for signal reception during lateral inhibition in the drosophila pupal notum. | suppressor of hairless (su(h)) activity is zygotically required in larval imaginal discs for the singling out of adult sense organ precursor (sop) cells: loss of su(h) function results in too many proneural cluster cells adopting the sop fate, while overexpression of the su(h) protein prevents sop specification. su(h) null mutant alleles are recessive lethal at the late larval and early pupal stages. the development of su(h) mutant cells in pupae was therefore studied in somatic clones. clonal a ... | 1995 | 7601001 |
| photobiology of bacteria. | the field of photobiology is concerned with the interactions between light and living matter. for bacteria this interaction serves three recognisable physiological functions: provision of energy, protection against excess radiation and signalling (for motility and gene expression). the chemical structure of the primary light-absorbing components in biology (the chromophores of photoactive proteins) is surprisingly simple: tetrapyrroles, polyenes and derivatised aromats are the most abundant ones ... | 1994 | 7832590 |
| in vivo and in vitro characterization of the light-regulated cpcb2a2 promoter of fremyella diplosiphon. | when exposed to different spectral qualities of light, many cyanobacteria dramatically alter their phycobilisome rod composition in a process termed complementary chromatic adaptation. in the cyanobacterium fremyella diplosiphon, this response is associated with differential expression of the cpcb2a2, cpeba, and cpecde operons, which code for the phycobiliproteins phycocyanin and phycoerythrin and the phycoerythrin linker polypeptides, respectively. to define components of the signal transductio ... | 1994 | 7929008 |
| molecular modeling of phytochrome using constitutive c-phycocyanin from fremyella diplosiphon as a putative structural template. | phytochrome, the ubiquitous photosensor in green plants, is similar to c-phycocyanin in a number of ways. we have produced a model of the phytochrome chromophore binding pocket based on the x-ray crystal structure of c-phycocyanin from fremyella diplosiphon [duerring et al. (1991) j. mol. biol. 217, 577-592]. twenty residues around the chromophore binding site of c-phycocyanin were changed to the corresponding residues of avena phytochrome a for the modeling. in the minimized model, arg-318, ala ... | 1994 | 8199230 |
| construction of shuttle plasmids which can be efficiently mobilized from escherichia coli into the chromatically adapting cyanobacterium, fremyella diplosiphon. | in some strains of cyanobacteria the composition of the light-harvesting antennae is determined by the color of available light. the mechanism of this chromatic adaptation involves the regulation of gene expression by red and green light and has been most studied in fremyella diplosiphon (calothrix sp. pcc 7601), a filamentous cyanobacterium for which there has been no reported means of genetic manipulation. we have constructed shuttle plasmids which can be efficiently mobilized by rp4 from esch ... | 1993 | 8234495 |
| plasmids from two morphologically distinct cyanobacterial strains share a novel replication origin. | a 2.9-kbp replication origin from a plasmid endogenous to the filamentous cyanobacterium fremyella diplosiphon utex 481 was genetically characterized and sequenced. deletion analysis of the 2.9-kbp dna fragment delimited the minimum region necessary for replication in f. diplosiphon fd33 to approximately 2.5 kbp. dna sequence analysis revealed that the f. diplosiphon plasmid replication origin is structurally very similar to and shares significant identity with the 1.75-kbp replication origin re ... | 1993 | 8366056 |
| in vivo and in vitro footprinting of a light-regulated promoter in the cyanobacterium fremyella diplosiphon. | certain filamentous cyanobacteria, such as fremyella diplosiphon, modulate the components of their light-harvesting complexes, the phycobilisomes, and undergo complex morphological changes in response to the wavelength of incident light, or light quality. the operon encoding the subunits of phycoerythrin, cpeba, is transcriptionally activated in green light and is expressed at very low levels in red light. to begin elucidating the signal transduction pathway between the detection of specific lig ... | 1993 | 8449886 |
| characterization of transposon tn5469 from the cyanobacterium fremyella diplosiphon. | a transposon, designated tn5469, was isolated from mutant strain fdr1 of the filamentous cyanobacterium fremyella diplosiphon following its insertion into the rcac gene. tn5469 is a 4,904-bp noncomposite transposon with 25-bp near-perfect terminal inverted repeats and has three tandemly arranged, slightly overlapping potential open reading frames (orfs) encoding proteins of 104.6 kda (909 residues), 42.5 kda (375 residues), and 31.9 kda (272 residues). insertion of tn5469 into the rcac gene in s ... | 1995 | 8522506 |
| a role for cpeyz in cyanobacterial phycoerythrin biosynthesis. | pigment mutant strain fdr1 of the filamentous cyanobacterium fremyella diplosiphon is characterized by constitutive synthesis of the phycobiliprotein phycoerythrin due to insertional inactivation of the rcac regulatory gene by endogenous transposon tn5469. whereas the parental strain fd33 harbors five genomic copies of tn5469, cells of strain fdr1 harbor six genomic copies of the element; the sixth copy in fdr1 is localized to the rcac gene. electroporation of fdr1 cells yielded secondary pigmen ... | 1997 | 9023176 |
| suppression of mutants aberrant in light intensity responses of complementary chromatic adaptation. | complementary chromatic adaptation is a process in which cyanobacteria alter the pigment protein (phycocyanin and phycoerythrin) composition of their light-harvesting complexes, the phycobilisomes, to help optimize the absorbance of prevalent wavelengths of light in the environment. several classes of mutants that display aberrant complementary chromatic adaptation have been isolated. one of the mutant classes, designated "blue" or fdb, accumulates high levels of the blue chromoprotein phycocyan ... | 1997 | 9226271 |
| atomic structure of the trypsin-a90720a complex: a unified approach to structure and function. | a90720a is a potent serine proteinase inhibitor produced by the terrestrial blue-green alga microchaete loktakensis. most of its structure has been defined by spectroscopic and degradative studies, but the configurations of several stereochemical centers are unknown, and its mode of inhibition of serine proteinases is not understood. we therefore examined the structure of the compound in a complex with trypsin. | 1994 | 9383379 |
| rpba controls transcription of the constitutive phycocyanin gene set in fremyella diplosiphon. | three gene sets encode alpha and beta subunits of the phycobiliprotein phycocyanin (pc) in the filamentous cyanobacterium fremyella diplosiphon. the cpcb1a1 set (encodes pc1) is constitutively expressed, whereas the cpcb2a2 set (encodes pc2) is expressed only in red light and the cpcb3a3 set (encodes pc3) is expressed only during sulfur-limited growth. primary pigment mutant strain fdbm1 is characterized by elevated levels of pc. dna hybridization analysis showed that like many pigment mutants i ... | 1997 | 9401027 |
| the activity of drosophila hairless is required in pupae but not in embryos to inhibit notch signal transduction. | drosophila hairless (h) encodes a negative regulator of notch signalling. h activity antagonizes notch (n) signalling during bristle development at the pupal stage. we show here by clonal analysis that h acts by inhibiting signal transduction rather than by promoting signal production, during both selection of microchaete precursors in the notum and vein cell differentiation in the wing. allele-specific interactions further suggest that h inhibits notch signal transduction by interacting directl ... | 1998 | 9518521 |
| cyanobacterial transposons tn5469 and tn5541 represent a novel noncomposite transposon family. | a noncomposite transposon, designated tn5541, was isolated from strain fd33 of the filamentous cyanobacterium fremyella diplosiphon utex 481. sequence analysis showed that tn5541 is structurally and genetically very similar to tn5469, which is also endogenous to f. diplosiphon. both tn5469 and tn5541 encode homologous forms of an unusual composite transposase and a protein of unknown function. dna hybridization analysis showed that like tn5469, tn5541 was not widely distributed among cyanobacter ... | 1998 | 9811670 |
| crystal structure of a phycourobilin-containing phycoerythrin at 1.90-a resolution. | the structure of r-phycoerythrin (r-pe) from the red alga griffithsia monilis was solved at 1.90-a resolution by molecular replacement, using the atomic coordinates of cyanobacterial phycocyanin from fremyella diplosiphon as a model. the crystallographic r factor for the final model is 17.5% (rfree 22.7%) for reflections in the range 100-1.90 a. the model consists of an (alphabeta)2 dimer with an internal noncrystallographic dyad and a fragment of the gamma-polypeptide. the alpha-polypeptide (16 ... | 1999 | 10388620 |
| dna-binding properties of the fremyella diplosiphon rpba repressor. | mutant strain fdbm1 of the cyanobacterium fremyella diplosiphon is characterized by elevated transcription of the cpcb1a1 gene set due to inactivation of rpba by tn5469. the predicted rpba protein contains two regions resembling the characterized helix-turn-helix (hth) motif involved in dna recognition by many phage and bacterial transcription regulator proteins. it was therefore hypothesized that rpba functions as a dna-binding repressor involved in the control of transcription from cpcb1a1. a ... | 2000 | 10613862 |
| a new appraisal of the prokaryotic origin of eukaryotic phytochromes. | the evolutionary origin of the phytochromes of eukaryotes is controversial. three cyanobacterial proteins have been described as "phytochrome-like" and have been suggested to be potential ancestors of these essential photoreceptors: cph1 from synechocystis pcc 6803, showing homology to phytochromes along its entire length and known to attach a chromophore; and plpa from synechocystis pcc 6803 and rcae from fremyella diplosiphon, both showing homology to phytochromes most strongly only in the c-t ... | 2000 | 11029065 |
| lead toxicity in cyanobacterial porphyrin metabolism. | the effect of pb2+ on growth, tetrapyrrole photosynthetic pigment content, total free porphyrin, and 5-aminolevulinate dehydratase (ala-d) activity of a cyanobacterium, microchaete tenera, and its ability to sequester pb2+ from the culture medium were studied. pb2+ was assayed by graphite furnace atomic absorption spectrophotometry. m. tenera growth and chlorophyll a content were not affected by 0.5, 1.0, and 6.0 ppm of pb2+. these treatments doubled the protein content and increased the phycobi ... | 2001 | 11345546 |
| structure of c-phycocyanin from the thermophilic cyanobacterium synechococcus vulcanus at 2.5 a: structural implications for thermal stability in phycobilisome assembly. | the crystal structure of the light-harvesting phycobiliprotein, c-phycocyanin from the thermophilic cyanobacterium synechochoccus vulcanus has been determined by molecular replacement to 2.5 a resolution. the crystal belongs to space group r32 with cell parameters a=b=188.43 a, c=61.28 a, alpha=beta=90 degrees, gamma=120 degrees, with one (alphabeta) monomer in the asymmetric unit. the structure has been refined to a crystallographic r factor of 20.2 % (r-free factor is 24.4 %), for all data to ... | 2001 | 11601847 |
| a turquoise mutant genetically separates expression of genes encoding phycoerythrin and its associated linker peptides. | during complementary chromatic adaptation (cca), cyanobacterial light harvesting structures called phycobilisomes are restructured in response to ambient light quality shifts. transcription of genes encoding components of the phycobilisome is differentially regulated during this process: red light activates cpcb2a2, whereas green light coordinately activates the cpecde and cpeba operons. three signal transduction components that regulate cca have been isolated to date: a sensor-photoreceptor (rc ... | 2002 | 11807056 |
| cper is an activator required for expression of the phycoerythrin operon (cpeba) in the cyanobacterium fremyella diplosiphon and is encoded in the phycoerythrin linker-polypeptide operon (cpecdestr). | in the cyanobacteria, phycobilisomes are assembled from (alphabeta)(6) hexamers of the coloured phycobiliproteins, allophycocyanin, phycocyanin and phycoerythrin (pe). the precise architecture of the phycobilisome is determined by the various colourless linker proteins that bind to the biliprotein hexamers. genes for beta and alpha subunits of pe make up one operon (cpeba), whereas genes for pe-associated linker polypeptides are in a second operon. in the chromatically adapting cyanobacterium fr ... | 2002 | 12067341 |
| transcriptional heterochrony of scute and changes in bristle pattern between two closely related species of blowfly. | temporal shifts in the expression of regulatory genes, relative to other events taking place during development, can result in changes in morphology. such transcriptional heterochrony can introduce dramatic morphological changes that involve rather few genetic events and so has the potential to cause rapid changes during evolution. we have shown previously that stereotyped species-specific bristle patterns on the notum of higher diptera correlate with changes in the spatial regulation of scute e ... | 2002 | 12453458 |
| lesions in phycoerythrin chromophore biosynthesis in fremyella diplosiphon reveal coordinated light regulation of apoprotein and pigment biosynthetic enzyme gene expression. | we have characterized the regulation of the expression of the pebab operon, which encodes the enzymes required for phycoerythrobilin synthesis in the filamentous cyanobacterium fremyella diplosiphon. the expression of the pebab operon was found to be regulated during complementary chromatic adaptation, the system that controls the light responsiveness of genes that encode several light-harvesting proteins in f. diplosiphon. our analyses of peba mutants demonstrated that although the levels of ph ... | 2003 | 14508001 |
| cotb is essential for complete activation of green light-induced genes during complementary chromatic adaptation in fremyella diplosiphon. | the dramatic modifications of photosynthetic light harvesting antennae called phycobilisomes that occur during complementary chromatic adaptation in cyanobacteria are controlled by two separate photosensory systems. the first system involves the signal transduction components rcae, rcaf and rcac, which appear to make up a complex multistep phosphorelay. this system controls the light responsive expression of the cpcb2a2h2i2d2, cpeba and cpecde operons, which encode phycobilisome proteins. the se ... | 2003 | 14617141 |
| signal transduction during light-quality acclimation in cyanobacteria: a model system for understanding phytochrome-response pathways in prokaryotes. | the colorful process of complementary chromatic adaptation (cca), in which cyanobacteria dramatically alter their pigmentation in response to ambient light color changes, has intrigued scientists for more than a century. over the past four decades, intensive research on the model organism fremyella diplosiphon has revealed many details of the photobiology and molecular biology of this process, which includes restructuring of these organism's photosynthetic light-harvesting antennae, called phyco ... | 2004 | 15170477 |
| genomic dna microarray analysis: identification of new genes regulated by light color in the cyanobacterium fremyella diplosiphon. | many cyanobacteria use complementary chromatic adaptation to efficiently utilize energy from both green and red regions of the light spectrum during photosynthesis. although previous studies have shown that acclimation to changing light wavelengths involves many physiological responses, research to date has focused primarily on the expression and regulation of genes that encode proteins of the major photosynthetic light-harvesting antennae, the phycobilisomes. we have used two-dimensional gel el ... | 2004 | 15205436 |
| apla, a member of a new class of phycobiliproteins lacking a traditional role in photosynthetic light harvesting. | all known phycobiliproteins have light-harvesting roles during photosynthesis and are found in water-soluble phycobilisomes, the light-harvesting complexes of cyanobacteria, cyanelles, and red algae. phycobiliproteins are chromophore-bearing proteins that exist as heterodimers of alpha and beta subunits, possess a number of highly conserved amino acid residues important for dimerization and chromophore binding, and are invariably 160 to 180 amino acids long. a new and unusual group of proteins t ... | 2004 | 15489454 |
| chromophore attachment to phycobiliprotein beta-subunits: phycocyanobilin:cysteine-beta84 phycobiliprotein lyase activity of cpes-like protein from anabaena sp. pcc7120. | the gene alr0617, from the cyanobacterium anabaena sp. pcc7120, which is homologous to cpes from gloeobacter violaceus pcc 7421, fremyella diplosiphon (calothrix pcc7601), and synechococcus sp. wh8102, and to cpcs from synechococcus sp. pcc7002, was overexpressed in escherichia coli. cpes acts as a phycocyanobilin: cys-beta84-phycobiliprotein lyase that can attach, in vitro and in vivo, phycocyanobilin (pcb) to cysteine-beta84 of the apo-beta-subunits of c-phycocyanin (cpcb) and phycoerythrocyan ... | 2006 | 16452471 |
| delta and hairy establish a periodic prepattern that positions sensory bristles in drosophila legs. | in vertebrates and invertebrates, spatially defined proneural gene expression is an early and essential event in neuronal patterning. in this study, we investigate the mechanisms involved in establishing proneural gene expression in the primordia of a group of small mechanosensory bristles (microchaetae), which on the legs of the drosophila adult are arranged in a series of longitudinal rows along the leg circumference. in prepupal legs, the proneural gene achaete (ac) is expressed in longitudin ... | 2006 | 16542648 |
| nucleotide sequence of a multiple-copy gene for the b protein of photosystem ii of a cyanobacterium. | chloroplast photogene 32 codes for the 32-kilodalton triazine herbicide-binding protein at the b site of electron transport in photosystem ii of the photosynthetic apparatus-its product is the b protein and the gene is accordingly designated ps2b here. the cyanobacteria anacystis nidulans r2, fremyella diplosiphon, and nostoc sp. mac each contain several copies of ps2b. the sequence of one copy of ps2b from fremyella, ps2b-1, has been determined. the longest open reading frame would code for a p ... | 1984 | 16578775 |
| cyanobacterial phycobilisomes: selective dissociation monitored by fluorescence and circular dichroism. | phycobilisomes are supramolecular assemblies of phycobiliproteins responsible for photosynthetic light collection in red algae and cyanobacteria. they can be selectively dissociated by reduction of temperature and buffer concentration. phycobilisomes isolated from fremyella diplosiphon transfer energy collected by c-phycoerythrin and c-phycocyanin to allophycocyanin. the energy transfer to allophycocyanin is nearly abolished at 2 degrees c, as indicated by a blue shift in fluorescence emission, ... | 1980 | 16592802 |
| formation of hybrid phycobilisomes by association of phycobiliproteins from nostoc and fremyella. | formation of phycobilisomes has been accomplished in vitro from isolated phycobiliprotein fractions obtained from the same blue-green alga (intrageneric) and from different blue-green algae (intergeneric). phycobilisomes, which are supra-molecular complexes of phycobiliproteins, serve as major light-harvesting antennae for photosynthesis in blue-green and red algae. intrageneric association into energetically functional phycobilisomes, previously reported to occur with nostoc sp. allophycocyanin ... | 1982 | 16593223 |
| incorporation of different n sources and light response curves of nitrogenase and photosynthesis by cyanobacterial blooms from rice fields. | in this work, we estimate the contributions of the different sources of n incorporated by two n(2)-fixing cyanobacterial blooms (anabaena sp. and microchaete sp.) in the rice fields of valencia (spain) during the crop cycles of 1999 and 2000, and evaluate the response of nitrogenase and c assimilation activities to changing irradiances. our results show that, far from the generally assumed idea that the largest part of the n incorporated by n(2)-fixing cyanobacterial blooms in rice fields comes ... | 2006 | 16596437 |
| identification and characterization of a new class of bilin lyase: the cpct gene encodes a bilin lyase responsible for attachment of phycocyanobilin to cys-153 on the beta-subunit of phycocyanin in synechococcus sp. pcc 7002. | synechococcus sp. pcc 7002 and all other cyanobacteria that synthesize phycocyanin have a gene, cpct, that is paralogous to cpet, a gene of unknown function affecting phycoerythrin synthesis in fremyella diplosiphon. a cpct null mutant contains 40% less phycocyanin than wild type and produces smaller phycobilisomes with red-shifted absorbance and fluorescence emission maxima. phycocyanin from the cpct mutant has an absorbance maximum at 634 nm compared with 626 nm for the wild type. the phycocya ... | 2006 | 16644722 |
| action spectra for phycobiliprotein synthesis in a chromatically adapting cyanophyte, fremyella diplosiphon. | the action spectra for phycocyanin production by the cyanophyte fremyella diplosiphon shows maxima at 463 and 641 nm. the action spectrum for phycoerythrin production includes maxima at 387 and 550 nm. the maxima are based on a relative response rate well within the linear ascending portion of the dose response curves; the positions of the maxima are independent of the relative response rates chosen for reference over a 3-fold range although the comparative effectiveness of light at pairs of wav ... | 1977 | 16660196 |
| phycobilisomes from blue-green and red algae: isolation criteria and dissociation characteristics. | a general procedure for the isolation of functionally intact phycobilisomes was devised, based on modifications of previously used procedures. it has been successful with numerous species of red and blue-green algae (anabaena variabilis, anacystis nidulans, agmenellum quadruplicatum, fremyella diplosiphon, glaucosphaera vacuolata, griffithsia pacifica, nemalion multifidum, nostoc sp., phormidium persicinum, porphyridium cruentum, p. sordidum, p. aerugineum, rhodosorus marinus). isolation was car ... | 1979 | 16660778 |
| control of phycoerythrin synthesis during chromatic adaptation. | chromatic adaptation is the process by which blue-green algae alter the rates of biliprotein synthesis in response to changes in the color of available light. we have examined the control of phycoerythrin synthesis during the early stages of chromatic adaptation in fremyella diplosiphon using fluorescence spectroscopy and (35)s-labeling of polypeptides. phycoerythrin synthesis begins within 45 to 90 minutes after transfer of cells from red to green light, but is blocked by rifamycin. transfer of ... | 1979 | 16661054 |
| light-induced changes in allophycocyanin. | several lines of evidence indicate that allophycocyanin is the previously unidentified "phycochrome" observed in extracts of blue-green algae.fractions containing phycoerythrin, phycocyanin, and allophycocyanin and exhibiting light-induced absorbance changes were prepared from extracts of nostoc muscorum and fremyella diplosiphon by isoelectric focusing. illumination of such fractions with red light (650 nanometers) causes a reduction in absorbance at 620 nm ( approximately 1 to 2%) and an incre ... | 1980 | 16661143 |
| changes in accumulation and synthesis of transcripts encoding phycobilisome components during acclimation of fremyella diplosiphon to different light qualities. | we have used gene-specific dna fragments as hybridization probes to quantitate the levels of transcripts encoding several phycobilisome polypeptides in the cyanobacterium fremyella diplosiphon in response to changes in the light environment. while the levels of transcripts encoding allophycocyanin, the core linker polypeptide, and the constitutive phycocyanin subunits are similar in f. diplosiphon grown either in red or green light, the levels of other transcripts change dramatically. transcript ... | 1988 | 16666425 |
| role of protein synthesis in regulation of phycobiliprotein mrna abundance by light quality in fremyella diplosiphon. | if green light-acclimated fremyella diplosiphon cultures are transferred to red light, the transcription from the inducible phycocyanin gene set increases at least 30-fold within 60 minutes. this effect is inhibited completely by the protein synthesis inhibitors chloramphenicol and spectinomycin. application of chloramphenicol 30 minutes after transfer of cultures to inductive red light prevents further phycocyanin mrna accumulation within 10 minutes. if red light-acclimated cells are transferre ... | 1989 | 16666955 |
| insights into phycoerythrobilin biosynthesis point toward metabolic channeling. | phycoerythrobilin is a linear tetrapyrrole molecule found in cyanobacteria, red algae, and cryptomonads. together with other bilins such as phycocyanobilin it serves as a light-harvesting pigment in the photosynthetic light-harvesting structures of cyanobacteria called phycobilisomes. the biosynthesis of both pigments starts with the cleavage of heme by heme oxygenases to yield biliverdin ixalpha, which is further reduced at specific positions by ferredoxin-dependent bilin reductases (fdbrs), a ... | 2006 | 16857683 |
| homologous expression of a bacterial phytochrome. the cyanobacterium fremyella diplosiphon incorporates biliverdin as a genuine, functional chromophore. | bacteriophytochromes constitute a light-sensing subgroup of sensory kinases with a chromophore-binding motif in the n-terminal half and a c-terminally located histidine kinase activity. the cyanobacterium fremyella diplosiphon (also designated calothrix sp.) expresses two sequentially very similar bacteriophytochromes, cyanobacterial phytochrome a (cpha) and cyanobacterial phytochrome b (cphb). cyanobacterial phytochrome a has the canonical cysteine residue, by which covalent chromophore attachm ... | 2007 | 17388813 |
| energy transfer processes in gloeobacter violaceus pcc 7421 that possesses phycobilisomes with a unique morphology. | we examined energy transfer dynamics in phycobilisomes (pbss) of cyanobacteria in relation to the morphology and pigment compositions of pbss. we used gloeobacter violaceus pcc 7421 and measured time-resolved fluorescence spectra in three types of samples, i.e., intact cells, pbss, and rod assemblies separated from cores. fremyella diplosiphon, a cyanobacterial species well known for its complementary chromatic adaptation, was used for comparison after growing under red or green light. spectral ... | 2008 | 18039461 |
| inverse transcriptional activities during complementary chromatic adaptation are controlled by the response regulator rcac binding to red and green light-responsive promoters. | complementary chromatic adaptation (cca) provides cyanobacteria with the ability to shift between red and blue-green phenotypes that are optimized for absorption of different wavelengths of light. controlled by the ratio of green to red light, this process results from differential expression of two groups of operons, many of which encode proteins involved in photosynthetic light harvesting antennae biogenesis. in the freshwater species fremyella diplosiphon, the inverse regulation of these two ... | 2008 | 18346116 |
| photoregulation of cellular morphology during complementary chromatic adaptation requires sensor-kinase-class protein rcae in fremyella diplosiphon. | we used wild-type utex481; sf33, a shortened-filament mutant strain that shows normal complementary chromatic adaptation pigmentation responses; and fdbk14, an rcae-deficient strain that lacks light-dependent pigmentation responses, to investigate the molecular basis of the photoregulation of cellular morphology in the cyanobacterium fremyella diplosiphon. detailed microscopic and biochemical analyses indicate that rcae is required for the photoregulation of cell and filament morphologies of f. ... | 2008 | 18390655 |
| abundance changes of the response regulator rcac require specific aspartate and histidine residues and are necessary for normal light color responsiveness. | rcac is a large, complex response regulator that controls transcriptional responses to changes in ambient light color in the cyanobacterium fremyella diplosiphon. the regulation of rcac activity has been shown previously to require aspartate 51 and histidine 316, which appear to be phosphorylation sites that control the dna binding activity of rcac. all available data suggest that during growth in red light, rcac is phosphorylated and has relatively high dna binding activity, while during growth ... | 2008 | 18757544 |
| light-dependent and light-independent protochlorophyllide oxidoreductases in the chromatically adapting cyanobacterium fremyella diplosiphon utex 481. | the cyanobacterium fremyella diplosiphon can alternate its light-harvesting pigments, a process called comple-mentary chromatic adaptation (cca), allowing it to photosynthesize in green light (gl) and in fluctuating light conditions. nevertheless, f. diplosiphon requires chlorophylls for photosynthesis under all light conditions. two alternative enzymes catalyze the penultimate step of chlorophyll synthesis, light-dependent protochlorophyllide oxidoreductase (lpor) and dark-operative protochlo-r ... | 2009 | 19561333 |
| cpcf-dependent regulation of pigmentation and development in fremyella diplosiphon. | cyanobacteria harvest light for photosynthesis using photosynthetic light-harvesting complexes called phycobilisomes (pbss). lyases are enzymes responsible for covalent attachment of light-absorbing chromophores to the phycobiliproteins (pbps) contained in pbss. we isolated a pigmentation mutant in the filamentous cyanobacterium fremyella diplosiphon and determined that it possesses an insertional mutation in cpcf, which encodes one component of a heterodimeric phycocyanin lyase. here, we discus ... | 2009 | 19748483 |
| fdtonb is involved in the photoregulation of cellular morphology during complementary chromatic adaptation in fremyella diplosiphon. | we have characterized a fremyella diplosiphon tonb protein (fdtonb) and investigated its function during complementary chromatic adaptation. sequence similarity analysis of fdtonb (571 aa) led to identification of several conserved domains characteristic of tonb proteins, including an n-terminal transmembrane domain, a central proline-rich spacer and a c-terminal tonb-related domain (tbrd). we identified a novel glycine-rich domain containing (gly-x)(n) repeats. to assess fdtonb function, we con ... | 2010 | 19959581 |
| a novel role for a tonb-family protein and photoregulation of iron acclimation in fremyella diplosiphon. | photosynthetic organisms display adaptations to changes in light and nutrient availability. iron, which is required for the function of photosynthetic photosystems and other important biochemical processes, is an essential mineral that consequently impacts not only overall photosynthetic efficiency, but also the physiology of organisms in general. our recent study represents the first functional characterization of a cyanobacterial tonb protein. tonb proteins classically are membrane proteins th ... | 2010 | 20495348 |
| independence and interdependence of the photoregulation of pigmentation and development in fremyella diplosiphon. | many photosynthetic organisms exhibit light-dependent regulation of growth and development, including photoregulation of pigmentation, physiology, and form. we recently demonstrated that the photoregulation of cellular and filament morphology in fremyella diplosiphon is under control of a photosensory photoreceptor and differentially impacted by photosynthetic pigment accumulation. biliprotein photoreceptor rcae controls the light-dependent regulation of pigmentation and of cell and filament mor ... | 2010 | 20585508 |
| functional characterization of a cyanobacterial ompr/phob class transcription factor binding site controlling light color responses. | complementary chromatic acclimation (cca) allows many cyanobacteria to change the composition of their light-harvesting antennae for maximal absorption of different wavelengths of light. in the freshwater species fremyella diplosiphon, this process is controlled by the ratio of red to green light and allows the differential regulation of two subsets of genes in the genome. this response to ambient light color is controlled in part by a two-component system that includes a phytochrome class photo ... | 2010 | 20833804 |
| the importance of structured noise in the generation of self-organizing tissue patterns through contact-mediated cell-cell signalling. | lateral inhibition provides the basis for a self-organizing patterning system in which distinct cell states emerge from an otherwise uniform field of cells. the development of the microchaete bristle pattern on the notum of the fruitfly, drosophila melanogaster, has long served as a popular model of this process. we recently showed that this bristle pattern depends upon a population of dynamic, basal actin-based filopodia, which span multiple cell diameters. these protrusions establish transient ... | 2010 | 21084342 |
| characterization of green mutants in fremyella diplosiphon provides insight into the impact of phycoerythrin deficiency and linker function on complementary chromatic adaptation. | functions of phycobiliprotein (pbp) linkers are less well studied than other pbp polypeptides that are structural components or required for the synthesis of the light-harvesting phycobilisome (pbs) complexes. linkers serve both structural and functional roles in pbss. here, we report the isolation of a phycoerythrin (pe) rod-linker mutant and a novel pe-deficient mutant in fremyella diplosiphon. we describe their phenotypic characterization, including light-dependent photosynthetic pigment accu ... | 2010 | 21094137 |
| sulfate-driven elemental sparing is regulated at the transcriptional and posttranscriptional levels in a filamentous cyanobacterium. | sulfur is an essential nutrient that can exist at growth-limiting concentrations in freshwater environments. the freshwater cyanobacterium fremyella diplosiphon (also known as tolypothrix sp. pcc 7601) is capable of remodeling the composition of its light-harvesting antennae, or phycobilisomes, in response to changes in the sulfur levels in its environment. depletion of sulfur causes these cells to cease the accumulation of two forms of a major phycobilisome protein called phycocyanin and initia ... | 2011 | 21239582 |
| characterization of complementary chromatic adaptation in gloeotrichia utex 583 and identification of a transposon-like insertion in the cpeba operon. | many cyanobacteria are able to alter the pigment composition of the phycobilisome in a process called complementary chromatic adaptation (cca). the regulatory mechanisms of cca have been identified in fremyella diplosiphon, which regulates both phycoerythrin and phycocyanin levels, and nostoc punctiforme, which regulates only phycoerythrin production. recent studies show that these species use different regulatory proteins for cca. we chose to study the cca response of gloeotrichia utex 583 in a ... | 2011 | 21288891 |
| Light-dependent attenuation of phycoerythrin gene expression reveals convergent evolution of green light sensing in cyanobacteria. | The colorful process of chromatic acclimation allows many cyanobacteria to change their pigmentation in response to ambient light color changes. In red light, cells produce red-absorbing phycocyanin (PC), whereas in green light, green-absorbing phycoerythrin (PE) is made. Controlling these pigment levels increases fitness by optimizing photosynthetic activity in different light color environments. The light color sensory system controlling PC expression is well understood, but PE regulation has ... | 2011 | 22042852 |
| characterization of the activities of the cpey, cpez, and cpes bilin lyases in phycoerythrin biosynthesis in fremyella diplosiphon strain utex 481. | when grown in green light, fremyella diplosiphon strain utex 481 produces the red-colored protein phycoerythrin (pe) to maximize photosynthetic light harvesting. pe is composed of two subunits, cpea and cpeb, which carry two and three phycoerythrobilin (peb) chromophores, respectively, that are attached to specific cys residues via thioether linkages. specific bilin lyases are hypothesized to catalyze each peb ligation. using a heterologous, coexpression system in escherichia coli, the peb ligat ... | 2011 | 21865169 |
| regulation of phycoerythrin synthesis and cellular morphology in fremyella diplosiphon green mutants. | light-dependent modification of photosynthetic pigmentation and cellular growth responses is commonly associated with increased fitness in photosynthetic organisms, including cyanobacteria. prior analyses of pigmentation mutants in the freshwater cyanobacterium fremyelladiplosiphon has resulted in the observation that rcae is a photosensor responsible for regulating organismal responses to changes in red light (rl) and green light (gl). rcae regulates both pigmentation and cellular morphology, y ... | 2011 | 21888899 |
| convergence and divergence of the photoregulation of pigmentation and cellular morphology in fremyella diplosiphon. | photosynthetic pigment accumulation and cellular and filament morphology are regulated reversibly by green light (gl) and red light (rl) in the cyanobacterium fremyella diplosiphon during complementary chromatic adaptation (cca). the photoreceptor rcae (regulator of chromatic adaptation), which appears to function as a light-responsive sensor kinase, controls both of these responses. recent findings indicate that downstream of rcae, the signaling pathways leading to light-dependent changes in mo ... | 2011 | 22112451 |
| temporal responses of wild-type pigmentation and rcae-deficient strains of fremyella diplosiphon during light transitions. | a temporal study was conducted to evaluate the dynamic complementary chromatic adaptation (cca) response of two fremyella diplosiphon strains-wild-type pigmentation strain sf33 and an rcae-deficient (δrcae) strain, which lacks the photosensor that regulates cca. sf33 and δrcae cultures were monitored for 15 days after transition of green-light (gl) acclimated cultures to red light (rl) and vice versa. sf33 showed similar growth irrespective of the external light quality; however, a δrcae strain ... | 2011 | 22046449 |
| exploiting the autofluorescent properties of photosynthetic pigments for analysis of pigmentation and morphology in live fremyella diplosiphon cells. | fremyella diplosiphon is a freshwater, filamentous cyanobacterium that exhibits light-dependent regulation of photosynthetic pigment accumulation and cellular and filament morphologies in a well-known process known as complementary chromatic adaptation (cca). one of the techniques used to investigate the molecular bases of distinct aspects of cca is confocal laser scanning microscopy (clsm). clsm capitalizes on the autofluorescent properties of cyanobacterial phycobiliproteins and chlorophyll a. ... | 2010 | 22163584 |
| a semiempirical approach to the intra-phycocyanin and inter-phycocyanin fluorescence resonance energy-transfer pathways in phycobilisomes. | a semiempirical methodology to model the intra-phycocyanin and inter-phycocyanin fluorescence resonance energy-transfer (fret) pathways in the rods of the phycobilisomes (pbss) from fremyella diplosiphon is presented. using the förster formulation of fret and combining experimental data and pm3 calculation of the dipole moments of the aromatic portions of the chromophores, transfer constants between pairs of chromophores in the phycocyanin (pc) structure were obtained. protein docking of two pc ... | 2007 | 17299727 |
| photoreversibility of the effect of red and green light pulses on the accumulation in darkness of mrnas coding for phycocyanin and phycoerythrin in fremyella diplosiphon. | dna fragments encoding a red light-inducible phycocyanin gene and a green light-inducible phycoerythrin gene have been used to investigate the effect of red and green pulses on the accumulation of phycocyanin and phycoerythrin mrna in subsequent darkness. a red pulse promotes phycocyanin and suppresses phycoerythrin mrna accumulation while a green pulse has an opposite effect on both transcript levels. the effect of a saturating light pulse is canceled by a subsequently given pulse of the other ... | 1988 | 16666426 |
| photoreversible absorbance changes in solutions of allophycocyanin purified from fremyella diplosiphon: temperature dependence and quantum efficiency. | preparations of allophycocyanin isolated from the alga fremyella diplosiphon show light-induced optical absorbance changes that suggest the presence of a photoconvertible component [formula: see text] similar to the algal pigments described by j. scheibe [(1972) science 176, 1037-1039]. at ph < 4 the allophycocyanin has an absorption maximum at 620 nm. red illumination causes a loss of absorbance in the red, centered at 620 nm, and subsequent green illumination restores the lost absorbance. we h ... | 1979 | 16592721 |
| the glial cell undergoes apoptosis in the microchaete lineage of drosophila. | apoptosis plays a major role in vertebrate and invertebrate development. the adult drosophila thoracic microchaete is a mechanosensory organ whose development has been extensively studied as a model of how cell division and cell determination intermingle. this sensory organ arises from a cell lineage that produces a glial cell and four other cells that form the organ. in this study, using an in vivo approach as well as fixed material, we show that the glial cell undergoes nucleus fragmentation s ... | 2003 | 12441297 |
| a glial cell arises from an additional division within the mechanosensory lineage during development of the microchaete on the drosophila notum. | we have used different cell markers to trace the development of the sensory cells of the thoracic microchaete. our results dictate a revision in the currently accepted model for cell lineage within the mechanosensory bristle. the sensory organ progenitor divides to form two secondary progenitors: piia and piib. piib divides first to give rise to a tertiary progenitor-piii and a glial cell. this is followed by division of piia to form the shaft and socket cells as described before. piii expresses ... | 1999 | 10498695 |
| revisiting the drosophila microchaete lineage: a novel intrinsically asymmetric cell division generates a glial cell. | the bristle mechanosensory organs of the adult fly are composed of four different cells that originate from a single precursor cell, pi, via two rounds of asymmetric cell division. here, we have examined the pattern of cell divisions in this lineage by time-lapse confocal microscopy using gfp imaging and by immunostaining analysis. pi divided within the plane of the epithelium and along the anteroposterior axis to give rise to an anterior cell, piib, and a posterior cell, piia. piib divided prio ... | 1999 | 10409503 |
| patterning of drosophila leg sensory organs through combinatorial signaling by hedgehog, decapentaplegic and wingless. | during development, global patterning events initiate signal transduction cascades which gradually establish an array of individual cell fates. many of the genes which pattern drosophila are expressed throughout development and specify diverse cell types by creating unique local environments which establish the expression of locally acting genes. this process is exemplified by the patterning of leg microchaete rows. hairy (h) is expressed in a spatially restricted manner in the leg imaginal disc ... | 1999 | 10357933 |
| delamination and division in the drosophila neurectoderm: spatiotemporal pattern, cytoskeletal dynamics, and common control by neurogenic and segment polarity genes. | cytoskeletal changes occurring during the delamination of precursors of the peripheral (microchaete precursors in the pupal notum) and central nervous system (embryonic si neuroblasts) were studied. the pattern of cell division in the ventral neurectoderm (vn) of wild-type embryos was analyzed using brdu incorporation and correlated to the pattern of neuroblast delamination. finally, defects in the pattern of proliferation of the vn and neuroblast delamination which occur in notch and wingless m ... | 1994 | 7958415 |
| development of adult sensilla on the wing and notum of drosophila melanogaster. | we have investigated the temporal pattern of appearance, cell lineage, and cytodifferentiation of selected sensory organs (sensilla) of adult drosophila. this analysis was facilitated by the discovery that the monoclonal antibody 22c10 labels not only the neuron of the developing sensillum organ, but the accessory cells as well. the precursors of the macrochaetes and the recurved (chemosensory) bristles of the wing margin divide around and shortly after puparium formation, while those of the mic ... | 1989 | 2517255 |
| genes involved in the development of bristles and hairs in drosophila melanogaster. | mutations in three loci influencing the development of bristles and hairs were detected in experiments with strains containing either a mobilized stalker or a mobilized p-element. the mutations in two genes, suppressor of scute and putative microchaete, modify phenotypic expression of mutations in the scute locus. in particular, su(sc) mutations suppress the sc-phenotype in the scutellum and enhance the hw-phenotype in the thorax. mutations in the third gene, pseudoscute, lead to reduction of al ... | 1992 | 1334026 |
| grim promotes programmed cell death of drosophila microchaete glial cells. | the inhibitor of apoptosis (iap) antagonists reaper (rpr), grim and hid are central regulators of developmental apoptosis in drosophila. ectopic expression of each is sufficient to trigger apoptosis, and hid and rpr have been shown to be important for programmed cell death (pcd). to investigate the role for grim in pcd, a grim null mutant was generated. grim was not a key proapoptotic gene for embryonic pcd, confirming that grim cooperates with rpr and hid in embryogenesis. in contrast, pcd of g ... | 2010 | 20558283 |
| purification and characterization of rna polymerase from fremyella diplosiphon. | we have purified and characterized a dna-dependent rna polymerase from the blue-green alga fremyella diplosiphon. this enzyme, purified by gel filtration, deae-cellulose chromatography, and glycerol gradient centrifugation, is comprised of five polypeptide subunits. their masses are 161,000, 134,000, 91,000, 72,000, and 41,000 daltons. preparative electrophoresis of the purified enzyme on nondenaturing gels separates the 41,000-dalton polypeptide from the rest of the enzyme. the enzyme is extrem ... | 1978 | 16660654 |