| new chalcones from bidens pilosa. | okanin 4'- o-beta- d-(2'',4'',6''-triacetyl)-glucoside, okanin 4'- o-beta- d-(6''- trans-p-coumaroyl)-glucoside, both new natural compounds, and okanin 3'- o-beta- d-glucoside have been isolated from the leaves of bidens pilosa l. their structures have been elucidated by means of uv, fd-ms, (1)h-nmr, and (13)c-nmr spectroscopy. nmr spectral data for okanin 4'- o-beta- d-glucoside (marein) are given. | 1988 | 17265204 |
| the dynamics of seed harvesting in early successional communities by a tropical ant, solenopsis geminata. | the neotropical ant, solenopsis geminata, in the moist lowlands of southeastern mexico was most abundant in agricultural fields and early second growth habitats. it was not found within forest habitats.in addition to its foraging for insects and general scavenging, this ant also harvests seeds. under field experimental conditions, a wide variety of small seeds, especially grasses, were taken. nest mound size and number were greatest on plots experimentally seeded to high grass density and low on ... | 1984 | 28311068 |
| is membrane potential involved in calmodulin gene expression after external stimulation in plants? | in bidens pilosa (cv. radiata), a non-injurious stimulus induces a local and transient change in membrane potential, and an injurious stimulus induces a transmitted electrical signal described as the combination of an action potential and a slow wave. we have studied calmodulin gene expression after these stimuli. when the stimulus is non-injurious, calmodulin mrna accumulation is only increased in the stimulated region. in contrast, when the stimulus is injurious, mrna accumulation takes place ... | 1996 | 8603755 |
| control of a symmetry-breaking process in the course of the morphogenesis of plantlets of bidens pilosa l. | a mechanism involving transport, storage and retrieval of a symmetry-breaking message controls the relative growth rate of the cotyledonary buds of plantlets of bidens pilosa l. the asymmetry was induced by administering a few needle pricks to one cotyledon of each plant. the storage of the symmetry-breaking message was independent of the number of pricks ("all or nothing" process) and irreversible. however, various treatments could render the plants either able to retrieve the stored symmetry-b ... | 1991 | 24194158 |
| constituents of bidens pilosa l.: do the components found so far explain the use of this plant in traditional medicine? | the dried aerial parts of bidens pilosa l. were extracted with petrol ether, chloroform, methanol, and methanol/water. the petrol ether and the methanol/water extracts showed some antimicrobial activity. fractionation of the extracts yielded well known substances, most of which have, however, not yet been described as constituents of bidens pilosa. several of these substances have previously been shown to be biologically active. thus, phenylheptatriyne, linolic acid and linolenic acid have antim ... | 1991 | 1674399 |