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  • 1
    ISSN: 1432-2048
    Keywords: Cell cycle ; Chlamydomonas ; Cell wall ; Autolysin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In light-dark-synchronized cultures of the unicellular green algaChlamydomonas reinhardtii, release of zoospores from the wall of the mother cell normally takes place during the second half of the dark period. The recently isolated mutant ‘ls’, however, needs light for the liberation of zoospores when grown photoautotrophically under a 12 h light-12 h dark regime. The light-induced release of zoospores was found to be prevented by addition of the photosystem-II inhibitor 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea. Furthermore, light dependence of this process was shown to be abolished when the mutant ‘ls’ was grown either photoautotrophically under a 14 h light-10 h dark regime or in the presence of acetate. Our findings indicate that the light-dependency of zoospore liberation observed in cultures of this particular mutant during photoautotrophic growth under a 12 h light-12 h dark regime might be attributed to an altered energy metabolism. The light-induced release of zoospores was found to be prevented by addition of cycloheximide or chloramphenicol, antibiotics which inhibit protein biosynthesis by cytoplasmic and organellar ribosomes, respectively. Actinomycin D, an inhibitor of RNA synthesis, however, did not affect the light-induced liberation of zoospores. Sporangia accumulate in stationary cultures of the mutant ‘ls’. Release of zoospores was observed when these sporangia were collected by centrifugation and incubated in the light after resuspension in fresh culture medium. Since liberation of zoospores was not observed after dilution of the stationary cultures with fresh culture medium, we suppose that components which interfere with the action of the sporangial autolysin are accumulated in the culture medium of the mutant ‘ls’.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: Crystal Structures ; Polyiodides ; Iodide ; Triiodide ; Pentaiodide ; Heptaiodide ; 1,3,5-Trialkyl-tetrahydro-1,3,5-triazinium Ions ; 1,3,5-Trimethyl-tetrahydro-1,3,5-triazinium Ion ; 1,3,5-Triethyl-tetrahydro-1,3,5-triazinium Ion ; 1,3,5-Tri-iso-propyl-tetrahydro-1,3,5-triazinium Ion ; 1,3,5-Tri-tertiarybutyl-tetrahydro-1,3,5-triazinium Ion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Polyhalides. 28. Further Investigations on 1,3,5-Trialkyl-tetrahydro-1,3,5-triazinium Polyiodides RTazIx: Preparation and Crystal Structure Analysis of the Compounds EtTazI3, i-PrTazIx with x = 3 and 5 and t-BuTazIx with x = (1), 3, 5 and 7The salts RTazIx with R = Et, i-Pr and t-Bu and 3 ≤ x ≤ 7 are formed by the reaction of 1,3,5-trialkyl-tetrahydro-1,3,5-triazinium iodide RTazI with iodine I2 from ethanoleous solution. 1,3,5-Triethyl-tetrahydro-1,3,5-triazinium triiodide C9H20N3I3 crystallizes triclinically in P1 with a = 773.5(1) pm, b = 842.8(1) pm, c = 1370.4(3) pm, α = 94.16(1)°, β = 97.34(1)°, γ = 106.35(1)° and Z = 2. The crystal structure is stacked by layers of cations EtTaz+ and of linear symmetric triiodide ions I3- alternating along [0 0 1]. 1,3,5-Tri-iso-propyl-tetrahydro-1,3,5-triazinium triiodide C12H26N3I3 crystallizes triclinically in P1 with a = 822.0(1) pm, b = 832.1(2) pm, c = 1553.6(2) pm, α = 78.26(1)°, β = 76.21(1)°, γ = 77.23(1)° and Z = 2. The crystal structure is built up from layers of cations i-PrTaz+ and of linear symmetric triiodide ions I3- alternating along [0 0 1]. 1,3,5-Tri-iso-propyl-tetrahydro-1,3,5-triazinium pentaiodide C12H26N3I5 crystallizes monoclinically in P21/c with a = 1015.4(2) pm, b = 1278.9(1) pm, c = 1811.3(2) pm, β = 92.47(1)° and Z = 4. The cationic (i-PrTaz+) and anionic (isolated V-shaped I5-) double layers alternate along [0 0 1]. 1,3,5-Tri-tertiary-butyl-tetrahydro-1,3,5-triazinium iodide C15H32N3I crystallizes monoclinically in P21/n with a = 863.9(1) pm, b = 1655.9(2) pm, c = 1307.6(1) pm, β = 92.90(1)° and Z = 4. Mixed layers built up from cations t-BuTaz+ and anions I- follow along [0 1 0]. 1,3,5-Tri-tertiary-butyl-tetrahydro-1,3,5-triazinium triiodide C15H32N3I3 crystallizes orthorhombically in Fdd2 with a = 1772.0(4) pm, b = 2477.8(6) pm, c = 2273.4(5) pm and Z = 16. The crystal structure is stacked by mixed layers of cations t-BuTaz+ and linear symmetric anions I3-. 1,3,5-Tri-tertiary-butyl-tetrahydro-1,3,5-triazinium pentaiodide C15H32N3I5 crystallizes monoclinically in C2/m with a = 1219.5(3) pm, b = 1420.9(3) pm, c = 1539.5(3) pm, β = 94.54(2)° and Z = 4. The crystal structure is built up from alternating cationic (t-BuTaz+) and anionic (symmetry generated I5-) double layers along [1 0 0]. The triiodide parts of different anionic double layers are linked up by iodine bridges I2 to zickzack chains. 1,3,5-Tri-tertiary-butyl-tetrahydro-1,3,5-triazinium heptaiodide C15H32N3I7 crystallizes monoclinically in P21/c with a = 1036.0(2) pm, b = 1768.3(4) pm, c = 1699.5(4) pm, β = 103.11(2)° und Z = 4. The crystal structure shows a three-dimensional network made by the alternating linkage of trigonal-pyramidal and Z-shaped heptaiodide ions.
    Notes: Die Verbindungen EtTazI3, i-PrTazIx mit x = 3 und 5 und t-BuTazlx mit x = 3, 5 und 7 lassen sich durch Umsetzung der entsprechenden 1,3,5-Trialkyl-tetrahydro-1,3,5-triazinium-iodide RTazI mit lod aus ethanolischer Lösung gewinnen. 1,3,5-Triethyltetrahydro-1,3,5-triaziniumtriiodid C9H20N3I3 kristallisiert in der triklinen Raumgruppe P1 mit a = 773,5(1) pm, b = 842,8(1) pm, c = 1370,4(3) pm, α = 94,16(1)°, β = 97,34(1)°, γ = 106,35(1)° und Z = 2. In der Kristallstruktur wechseln sich Schichten aus Kationen EtTaz+ und isolierten zentrosymmetrischen Anionen I3- längs [0 0 1] ab. 1,3,5-Tri-iso-propyl-tetrahydro-1,3,5-triazinium-triiodid C12H26N3I3 kristallisiert in der triklinen Raumgruppe P1 mit a = 822,0(1) pm, b = 832,1(2) pm, c = 1553,6(2) pm, α = 78,26(1)°, β = 76,21(1)°, γ = 77,23(1)° und Z = 2. In der Kristallstruktur folgen entlang [0 0 1] im Wechsel Schichten aus Kationen i-PrTaz+ und aus isolierten zentrosymmetrischen Anionen I3-. 1,3,5-Tri-iso-propyl-tetrahydro-1,3,5-triazinium-pentaiodid C12H26N3I5 kristallisiert in der monoklinen Raumgruppe P21/c mit a = 1015,4(2) pm, b = 1278,9(1) pm, c = 1811,3(2) pm, β = 92,47(1)° und Z = 4. In der Kristallstruktur ordnen sich längs [0 0 1] abwechselnd Kationen i-PrTaz+ und isolierte stark verengte V-förmige Anionen I5- zu Doppelschichten an. 1,3,5-Tri-tertiär-butyl-tetrahydro-1,3,5-triazinium-iodid C15H32N3I kristallisiert in der monoklinen Raumgruppe P21/n mit a = 863,9(1) pm, b = 1655,9(2) pm, c = 1307,6(1) pm, β = 92,90(1)° und Z = 4. In der Kristallstruktur befinden sich längs [0 1 0] Kationen t-BuTaz+ und Anionen I- in gemischten Schichten. 1,3,5-Tritertiär-butyl-tetrahydro-1,3,5 triaziniunm-triiodid C15H32N3I3 kristallisiert in der orthorhombischen Raumgruppe Fdd2 mit a = 1772,0(4) pm, b = 2477,8(6) pm, c = 2273,4(5) pm und Z = 16. In der Kristallstruktur folgen entlang [1 0 0] gemischte Schichten von Kationen t-BuTaz+ und isolierten zentrosymmetrischen Anionen I3-. 1,3,5-Tri-tertiär-butyl-tetrahydro-1,3,5-triazinium-pentaiodid C15H32N3I5 kristallisiert in der monoklinen Raumgruppe C2/m mit a = 1219,5(3) pm, b = 1420,9(3) pm, c = 1539,5(3) pm, β = 94,54(2)° und Z = 4. In der Kristallstruktur wechseln sich längs [1 0 0] Doppelschichten von Kationen t-BuTaz+ und symmetrieerzeugten Anionen I5- ab, deren Triiodid-artige Schenkel entlang [0 1 0] über Iod-Brücken zu zickzackförmigen Ketten verknüpft werden. 1,3,5-Tri-tertiär-butyl-tetrahydro-1,3,5-triazinium-heptaiodid C15H32N3I7 kristallisiert in der monoklinen Raumgruppe P21/c mit a = 1036,0(2) pm, b = 1768,3(4) pm, c = 1699,5(4) pm, β = 103,11(2)° und Z = 4. Die Kristallstruktur baut sich längs [0 0 1] aus vernetzten stark gewellten Doppelketten von fehlgeordneten Anionen I7- auf, in deren Zwischenräumen sich die Kationen t-BuTaz+ befinden.
    Additional Material: 15 Ill.
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