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Abstract. Hybrid lethality is one of the mechanisms for reproductive isolation. Apoptotic features were detected in the cells of hybrid seedlings of Nicotiana glutinosa L.N. repanda Willd. Condensation of chromatin and fragmentation of nuclei were observed in the leaf protoplasts isolated from hybrid seedlings expressing this lethality. Fragmentation of nuclei was correlated with the progression of...
Abstract. A non-reducing trisaccharide, -D-mannopyranosyl-(14)--D-glucuronopyranosyl-(12)-myo-inositol (MGI) accumulated in the spent medium of cell-suspension cultures of `Pauls Scarlet rose (Rosa sp.) predominantly during the period of rapid cell growth. This trisaccharide was also produced by cultures of sycamore (Acer pseudoplatanus L.) but not by those of the graminaceous monocots maize (Zea...
Abstract.Embryo specific (emb) mutants exhibit aberrant embryo development without deleterious effects on endosperm development. We have analyzed five emb mutants of maize, which, based on their developmental profiles can be divided into two groups: mutants arrested at early stages and mutants with novel phenotypes. The members of the first group resemble wild-type proembryos and never reach other...
Abstract. The effect of hypoxia on root development and carbon metabolism was studied using potato (Solanum tuberosum L.) plants as a model system. Hypoxia led to a cessation of root elongation, and finally to the death of meristematic cells. These changes were accompanied by a 4- to 5-fold accumulation of hexoses, suggesting that insufficient carbohydrate supply was not the cause of cell death. In...
Abstract. We measured the osmotic water permeability (Pos) of vacuoles isolated from onion (Allium cepa L.), rape (Brassica napus L.), petunia (Petunia hybrida Hook.) and red beet (Beta vulgaris L.). For all the vacuolar types investigated, Pos values were in the range 2001000ms1. The change in membrane surface area induced by an osmotic gradient was smaller than 26%. The vacuolar Pos values for red...
Abstract. The pathway of sucrose metabolism in cyanobacteria is just starting to be elucidated. The present study describes the first isolation and biochemical characterization of a prokaryotic sucrose synthase (SS, EC 2.4.1.13). Two SS forms (SS-I and SS-II) were detected in Anabaena sp. strain PCC 7119. The isoform SS-II was purified 457-fold and its amino-terminal portion sequenced. Substrate specificity,...
Abstract. To elucidate the graviperception of the unicellular fungus, Phycomycesblakesleeanus, sporangiophores were inspected for intracellular structures which relocate with respect to gravity. Two structures, paracrystalline proteins (so-called octahedral crystals) and an aggregate of lipid globules, were identified which showed redistribution upon reorientation of the sporangiophore. Octahedral...
Abstract. The maize (Zea mays L.) male-sterile mutant polymitotic (po) was analyzed utilizing in-vitro cell culture and immunocytochemistry methods to better understand the relationship between the mutant phenotype and cell cycle events during microspore development. Using a live meiocyte culture system, initiation and progression through abnormal post-meiotic cell cycles at the end of meiosis II...
Abstract. The effects of elevated CO2 concentrations on the photochemistry, biochemistry and physiology of C4 photosynthesis were studied in maize (Zea mays L.). Plants were grown at ambient (350LL1) or ca. 3 times ambient (1100LL1) CO2 levels under high light conditions in a greenhouse for 30d. Relative to plants grown at ambient CO2 levels, plants grown under elevated CO2 accumulated ca. 20% more...
Abstract. Zoospores of Enteromorpha compressa (L.) Grev. secrete an adhesive cell coat which is involved in their attachment to various substrata. Two monoclonal antibodies (mAbs), designated Ent 1 and Ent 6, were raised against settled zoospores displaying secreted adhesive. Both antibodies labelled specifically the anterior region of the cell containing putative adhesive vesicles. During settlement...
Abstract. The physical characteristics of rubber particles from the four rubber (cis-1,4-polyisoprene) producing species Euphorbia lactiflua Phil., Ficus elastica Roxb., Hevea brasiliensis Mll. Arg., and Parthenium argentatum Gray, were investigated using transmission electron microscopy (TEM) and electron-paramagnetic-resonance (EPR) spin labeling spectroscopy. Transmission electron microscopy showed...
Abstract. Elicitation of Arabidopsis thaliana (L.) Heynh. suspension cultures with the bacterial protein harpin (from Pseudomonas syringae pv. syringae) induced the activation of two kinases of 39 and 44kDa, as demonstrated by in-gel kinase assays using myelin basic protein (MBP) as a substrate. Both these kinases appeared to be tyrosine-phosphorylated upon activation, as demonstrated by treatment...
Abstract. The architecture of the nuclei of higher plants includes a structure similar to the nuclear lamina of vertebrates. Changes in this structure were monitored during mitosis in carrot (Daucus carota L.) and celery (Apium graveolens L.) cells by immunofluorescence microscopy using an antibody that recognized the nuclear-matrix protein NMCP1. This protein has been shown to be localized exclusively...
Abstract.Lolium temulentum L. Ba 3081 was grown hydroponically in air (350molmol1 CO2) and elevated CO2 (700molmol1 CO2) at two irradiances (150 and 500molm2s1) for 35 days at which point the plants were harvested. Elevated CO2 did not modify relative growth rate or biomass at either irradiance. Foliar carbon-to-nitrogen ratios were decreased at elevated CO2 and plants had a greater number of shorter...
Abstract. The hydraulic conductivity of excised roots (Lpr) of the legume Lotus japonicus (Regel) K. Larsen grown in mist (aeroponic) and sand cultures, was found to vary over a 5-fold range during a day/night cycle. This behaviour was seen when Lpr was measured in roots exuding, either under root pressure (osmotic driving force), or under an applied hydrostatic pressure of 0.4MPa which produced a...
Abstract. The contribution of changes in stomatal conductance and metabolism in determining heterogeneous photosynthesis inhibition during dehydration and abscisic acid (ABA) feeding was investigated using detached leaves of Rosa rubiginosa L. The steady-state and maximal rates of electron transport under a transient high CO2 concentration were monitored using chlorophyll fluorescence imaging. The...
Abstract. Alfalfa (Medicago sativa L.) suspension cultures respond to yeast elicitors with a strong alkalinization of the culture medium, a transient synthesis of activated oxygen species, and typical late defence reactions such as phytoalexin accumulation and increased peroxidase activity. The alkalinization reaction as well as the oxidative burst were also observed when tobacco (Nicotiana tabacum...
Abstract. Pod storage protein (PSP) accumulated in developing pods of French bean (Phaseolus vulgaris L.) plants, and increasing the PSP mRNA level by pod removal resulted in the enhancement of PSP accumulation in pods that formed later. Pod storage protein was detected in flowers, young leaves and young stem internodes in addition to pods. Accumulation of PSP and its mRNA was induced by sink-removal...
Abstract. By using the mRNA differential display approach to isolate defense signaling genes active at the early stage of fungal infection two cDNA fragments with high sequence homology to rab-specific GDP-dissociation inhibitors (GDIs) were identified in rice (Oryza sativa L.) suspension cells. Using polymerase-chain-reaction products as probes, two full-length cDNA clones were isolated from a cDNA...
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