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At least 37 records · Page 2Linked to original sources
PubMed1985

Variant Cell Lines of Haplopappus gracilis with Disturbed Activities of Nitrate Reductase and Nitrite Reductase.

Selected variant cell lines of Haplopappus gracilis (Nutt) Gray that showed disturbed growth after transfer from an alanine medium to NO(3) (-) medium were characterized. The in vivo NO(3) (-) reductase activity (NRA) was lower in these lines than in the wild type. In vitro NRA assays suggest that decreased in vivo NRA was not caused by a lower amount of active enzyme. Cells of the variant lines revealed up to 75% lower extractable activity of NO(2) (-) reductase as compared with the wild type. This coincided with higher accumulation of NO(2) (-) by the variant than by the wild type cells after transfer from alanine medium to NO(3) (-) medium. NO(2) (-) accumulation was transient or continuous, depending on cell line, metabolic state of the cells, and light conditions.

Journal Article↗
PubMed1996

Enhanced root production in Haplopappus gracilis grown under spaceflight conditions.

The production and growth of roots in two aseptically maintained clonal populations of Haplopappus gracilis (family Compositae), each with a distinctive pattern of root production, were studied after they had been exposed to space for 5 days aboard a NASA Space Shuttle. Total root production of both populations was 67-95% greater when compared with their Earth-grown controls. Roots were generated: (1) laterally from pre-formed roots, the tips of which had been severed at the time of plantlet insertion into a "horticultural foam" substrate supplied with a nutrient solution; (2) adventitiously from the basal or cut-end portion of shoots; (3) de novo, i.e. from primordial which were non-existent at the outset of the experiment. Roots grew in all directions in space but were uniformly positively gravitropic in ground controls. In space and on Earth, both clonal populations maintained their clone-specific root formation and growth characteristics and produced an equivalent amount of tissue when compared to each other. As on Earth, and as expected, there were fewer and shorter roots on plantlets that formed floral buds. The significance of altered moisture distribution in the "horticultural foam" substrate in space for root growth and the significance of our findings for growing plants in altered gravity environments are discussed.

Computer Simulation↗
PubMed2002

New terpenoids from Haplopappus multifolius.

The chemical investigation of the aerial parts of Haplopappus multifolius afforded the new monoterpene 2,9-epoxy-p-menth-6-en-8-ol (7, haplopappol), the new monoterpenoid ester 9-cis-p-coumaroyloxy-alpha-terpineol (8, haplofolin), the new diterpene 18-hydroxylabda-7,13Z-dien-15-oic acid (6) and its known E-isomer (5). In addition, the known dihydroflavones 3',5-dihydroxy-4',7-dimethoxydihydroflavone and 3',4',5-trihydroxy-7-methoxydihydroflavone and the known dihydroflavonols 3',5-dihydroxy-4',7-dimethoxydihydroflavonol and 3',4',5-trihydroxy-3-acetyl-7-methoxydihydroflavonol were also obtained. The structural assignments of these compounds were made possible by the different spectroscopic measurements.

Asteraceae↗
PubMedDate not supplied

[Productivity of autotetraploids and frequency of aneuploidy in reproduction in Haplopappus gracilis L].

Comparative studies of productivity of autotetraploid plants H. gracilis L. after selection for high productivity, without selection for high productivity and aneuploidity, and after selection for low productivity have been done. The results show considerable effectiveness of selection for productivity. Presence of hyperaneuploid forms in the population is a major cause of the decreasing of autotetraploid productivity.

Aneuploidy↗
PubMed1970

The effects of amino acids and ammonium on the growth of plant cells in suspension culture.

A suspension culture of soybean (Glycine max L.) was grown on a defined medium in which the nitrogen sources were nitrate (25 mM) and ammonium (2 mM). The cells did not grow on nitrate unless the medium was supplemented with ammonium or glutamine. The l- and d-isomers of 12 amino acids tested singly could not replace ammonium. Most amino acids (4 mM) inhibited growth when the cells were cultured on nitrate and ammonium. Cells from five other plants (Reseda luteoli L.; Triticum monococcum L.; flax, Linum usitatissimum L.; horseradish, Amoracia lapathifolia Gilib; Haplopappus gracilis L.) grew on the defined medium with nitrate (25 mM) as the sole nitrogen source. Higher cell yields were obtained when ammonium (2 mM) or glutamine also was present. Supplementing the defined medium with high concentrations of ammonium (20 mM) inhibited growth of soybean, Haplopappus, and wheat cells. Addition of citrate (5 mM) relieved the inhibitory effects of ammonium in soybean and wheat cells but not in the Haplopappus cells.

Journal Article↗
PubMed1971

Ethylene Production by Plant Cell Cultures: Variations in Production during Growing Cycle and in Different Plant Species.

Suspension cultures of Rosa sp., soybean (Glycine max L.), wheat (Triticum monococcum L.), sweet clover (Melilotus alba Desc.), Haplopappus gracilis Nutt., and rue (Ruta graveolens) produced ethylene. The amount varied with the species. The rate of formation in rose and Haplopappus cells paralleled growth but accelerated when the stationary phase was reached, after which the rate declined sharply. Light was not required for ethylene production. Exogenous ethylene could not replace 2,4-dichlorophenoxyacetic acid or naphthalineacetic acid in the cell cultures, and there was no stimulation of growth in the normal medium. Ethylene at 20 mm reduced growth of Ruta and rose cells by 30 and 20%, respectively. The amounts of ethylene produced by the cultures do not affect growth.

Journal Article↗
PubMed1976

Osmotic shrinkage as a factor in freezing injury in plant tissue cultures.

Haplopappus gracilis and Acer saccharum tissue culture cells are extremely sensitive to freezing injury, and exhibit a decrease in survival from 98% at -1 C to 4% at -3 C (Haplopappus) and 92% at -3 C to 13% at -5 C (Acer) when suspended in distilled H(2)O, seeded at -1 C, and then cooled by 0.1 C/minute. Similar results are obtained when cells are suspended in growth medium. The extent of shrinkage of cells during freezing can be duplicated by exposure of the cells to plasmolyzing solutions of nonpenetrating substances (Delta T(f) = 1.86 phivm). Solutions of sucrose and glycerol that produce extensive plasmolysis cause a decrease in survival within 3 to 5 minutes at room temperature, and the higher the molality to which the cell is exposed the greater the injury. Also, the rate of rehydration of the plasmolyzed cell and of the frozen cell affects its survival, with the slower rate being more beneficial. The close correlation between the decrease in survival at subzero temperatures and the decrease in survival when cells are placed in solutions having osmolalities, which could produce the same extent of shrinkage as these killing temperatures, suggests that this shrinkage is related to freezing injury in tissue culture cells.

Journal Article↗
PubMed2000

A unique pollen wall mutation in the family Compositae: ultrastructure and genetics.

During a routine screening of pollen fertility in the n = 2 chromosome race of Haplopappus gracilis, a spineless pollen wall mutation was discovered that renders the otherwise functional pollen grains completely unrecognizable as Compositae pollen. Normal Haplopappus pollen is characterized by an outer layer, the ektexine, consisting of large spines supported by a roof (tectum), which in turn is supported by collumellae that are joined basally. A large cavity (cavea) stretches from aperture to aperture and separates columellae bases from the final ektexine unit, the foot layer. The spines, tectum, columellae, and columellae bases are filled with perforations (internal foramina), while the foot layer is without them. Immediately underlying the foot layer is a thickened, lamellate, disrupted, internal foramina-free second exine layer, the endexine. In contrast, the mutant pollen ektexine is a jumble of components with randomly dispersed spines as the only clearly definable unit. The endexine layer is similar to the endexine in normal pollen. The mutation apparently disrupts only the organization of ektexine units, and mutant pollen appears to be without the caveae and foot layer characteristic of normal pollen. In genetic tests, the mutant allele is recessive. There is a simple Mendelian pattern of inheritance of the mutant gene, and its phenotype is under sporophytic control.

Journal Article↗
PubMed2003

Argentinian plant extracts with relaxant effect on the smooth muscle of the corpus cavernosum of guinea pig.

Extracts of different polarity from Baccharis trimera, Haplopappus rigidus Huperzia saururus, Maytenus ilicifolia, Satureja parvifolia and Senecio eriophyton were tested for their relaxant activity on smooth muscle using L-phenylephrine precontracted strips of corpus cavernosum obtained from Guinea pigs. Highly significant and dose dependent results were obtained with the dichloromethane extracts of H. saururus (87% of relaxation at the dose of 10 mg/ml), S. parvifolia (95% of relaxation at 2.5 mg/ml) and S. eriophyton (94% of relaxation at 5 mg/ml). Similar effects were observed with the methanol extracts of H. saururus (88% of relaxation at 10 mg/ml) and S. parvifolia (84% of relaxation at 10 mg/ml). These results were comparable to those obtained with the dichloromethane and methanol extracts of the well known Mexican species Turnera diffusa. Moreover, the aqueous extract of H. rigidus and the aqueous and methanol extracts of S. eriophyton were highly effective in a dose dependent manner (more than 90% of relaxation at the dose of 10 mg/ml). Significant results, but with a lower overall relaxant activity (about 70% of relaxation at 10 mg/ml), could also be obtained with the aqueous extract of S. parvifolia and with the dichlormethane and methanol extracts of B. trimera and M. ilicifolia. The positive controls with Sildenafil citrate at doses ranging from 0.35 to 35 microg/ml yielded moderate effects (up to 46% of relaxation at 35 microg/ml). The effects observed in the present study seem to validate the folk medicinal use of the tested plants and open new ways in the search for natural products with vasodilatory effects.

Animals↗