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Abstract. Regulation by irradiance level of the mechanism for dissolved inorganic carbon (DIC) acquisition was examined in the red macroalga Gracilaria tenuistipitata Zhang et Xia. For this purpose, affinity for external DIC, carbonic anhydrase (CA; EC 4.2.1.1) activity and content of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) were determined in thalli grown at 45 and 500...
Abstract.The negative gravitropism of the sporangiophores of Phycomyces blakesleeanus Burgeff is elicited by different sensory inputs, which include flexure of the growing zone, buoyance of lipid globules and sedimentation of paracrystalline proteins, so-called octahedral crystals (C. Schimek etal., 1999a, Planta 210: 132142). Gravity-induced absorbance changes (GIACs), which are associated with primary...
Abstract.Non-photochemical quenching of chlorophyll fluorescence (NPQ) and quantum yield of photosystem II (PSII) were studied with intact mesophyll chloroplasts of maize (Zea mays L.) during the initial minutes of illumination using the pulse-modulated chlorophyll fluorescence technique. Non-photochemical quenching was rapidly reversible in the dark at any point during illumination, which is indicative...
Abstract. Aglycons derived from 4-O--D-glucosides of both caffeyl and 5-hydroxyconiferyl alcohols were incorporated into guaiacyl (G) and syringyl (S) units in the lignin of newly formed xylem of several angiosperms. It is likely that these aglycons enter the cinnamyl alcohol pathway as intermediates in the introduction of methoxyl groups onto aromatic rings, and serve as precursors for the biosynthesis...
Abstract. Upon herbivore attack, maize (Zea mays L.) emits a mixture of volatile compounds that attracts herbivore enemies to the plant. One of the major components of this mixture is an unusual acyclic C11 homoterpene, (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), which is also emitted by many other species following herbivore damage. Biosynthesis of DMNT has been previously shown to proceed via the...
Abstract. The cortical microfilament (MF) component of the cytoskeleton within axial elements of the secondary vascular system of the angiosperm tree, Aesculus hippocastanum L. (horse-chestnut) was studied using transmission electron microscopy of ultrathin sections and indirect immunofluorescence microscopy of actin in thick sections. As seen by electron microscopy, MF bundles have a net axial orientation...
Abstract.The ABA INSENSITIVE1 (ABI1) and ABI2 genes encode homologous type-2C protein phosphatases with redundant yet distinct functions in abscisic acid (ABA) responses. Results from Northern blot analysis showed that ABA- and mannitol-inducible expression of the COR47 and COR78/LTI78/RD29A (COR78) genes was more impaired in the abi2 mutant of Arabidopsis thaliana (L.) Heynh than in the abi1 mutant...
Abstract.A cDNA encoding UDP-glucose: baicalein 7-O-glucosyltransferase (UBGT) was isolated from a cDNA library from hairy root cultures of Scutellaria baicalensis Georgi probed with a partial-length cDNA clone of a UDP-glucose: flavonoid 3-O-glucosyltransferase (UFGT) from grape (Vitis vinifera L.). The heterologous probe contained a glucosyltransferase consensus amino acid sequence which was also...
Abstract. Microsporogenesis in Lilium longiflorum Thunb. is a naturally synchronous process and affords a system in which to study stage-specific events of meiosis and anther development. Zymogram gel analyses were conducted with extracts from a variety of stages of anther development to identify proteinases which likely play roles in anther metabolism. These experiments revealed that several proteinases...
Abstract. A novel plant lectin was isolated from salt-stressed rice (Oryzasativa L.) plants and partially characterized. The lectin occurs as a natural mixture of two closely related isoforms consisting of two identical non-covalently linked subunits of 15kDa. Both isoforms are best inhibited by mannose and exhibit potent mitogenic activity towards T-lymphocytes. Biochemical analyses and sequence...
Abstract. The ectopic expression of knotted homologues has cytokinin-like effects on plant morphology. The functional relationship between knotted and cytokinins was investigated in cultures of leaf tissue established from tobacco (Nicotiana tabacum L. cv. Havana 425) plants transformed with the maize knotted1 (kn1) gene regulated by cauliflower mosaic virus 35S RNA expression signals. In contrast...
Abstract. Two-year-old rosemary (Rosmarinus officinalis L.) plants were subjected to severe stress by exposure to prolonged drought during a Mediterranean summer. Severely stressed plants recovered completely after the autumn rainfalls although the relative water content remained below 35% for 3 months and the chlorophyll content of leaves was reduced by up to 85% during the drought. In severe stress:...
Abstract.The light-induced intracellular relocation of chloroplasts was examined in red-light-grown protonemal cells of the moss Physcomitrella patens. When irradiated with polarized red or blue light, chloroplast distribution in the cell depended upon the direction of the electrical vector (E-vector) in both light qualities. When the E-vector was parallel to the cross-wall (i.e. perpendicular to...
Abstract. The alga Chlamydomonas reinhardtii contains cytoplasmic vacuoles that are often filled with a dense granule that is released from the cell by exocytosis. Purified granules contained polyphosphate, complexed with calcium and magnesium, as the predominant inorganic components. Antiserum was raised against the major 70-kDa protein in granules purified from wall-deficient (cw15) mutants, which...
Abstract.The carB gene, encoding the phytoene dehydrogenase of Mucor circinelloides, was isolated by heterologous hybridisation with a probe derived from the corresponding gene of Phycomyces blakesleeanus. The cDNA and genomic copies complemented phytoene dehydrogenase defects in Escherichia coli and in carB mutants of M. circinelloides, respectively. Fluence-response curves for transcript accumulation...
Abstract.In addition to OPR1 and OPR2, two isoenzymes of 12-oxophytodienoate reductase, a third isoform (OPR3) has recently been identified in Arabidopsis thaliana (L.) Heynh. The expression of the OPR3 gene is induced not only by a variety of stimuli, such as touch, wind, wounding, UV-light and application of detergent, but also by brassinosteroids. The three enzymes were expressed in a functional...
Abstract. The interaction between Phytophthora infestans (Mont.) de Bary and Solanum was examined cytologically using a diverse set of wild Solanum species and potato (S.tuberosum L.) cultivars with various levels of resistance to late blight. In wild Solanum species, in potato cultivars carrying known resistance (R) genes and in nonhosts the major defense reaction appeared to be the hypersensitive...
Abstract. The metabolic responses occurring in cucumber (Cucumis sativus L.) roots (a strategy-I plant) grown under iron-deficiency conditions were studied in-vivo using 31P-nuclear magnetic resonance spectroscopy. Iron starvation induced activation of metabolism leading to the consumption of stored carbohydrates to produce the NAD(P)H, ATP and phosphoenolpyruvate necessary to sustain the increased...
Abstract.Two isoforms of chalcone synthase (CHS) were isolated from cDNA libraries derived from UV-A-irradiated anthocyanin-accumulating (DCb) and non-accumulating (DCs) cell cultures of carrot (Daucus carota L.). The clones designated as DcCHS1, which were present only in the DCb library, had a deduced primary sequence of 389 amino acids and an expected molecular mass of 42.7kDa, and seem to be alleles...
Abstract.Hieracium is a member of the Asteraceae family, and contains sexual species in addition to apomictic species that reproduce by apospory and produce seed without fertilization. A homologue of the floral organ-identity gene DEFICIENS (DEF) was isolated from an apomictic line of Hieracium piloselloides (Vill.) following differential display between mature ovules and those initiating autonomous...
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