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PubMed2004

In vitro isoflavonoid production in callus from different organs of Pueraria lobata (Wild.) Ohwi.

Pueraria lobata (Wild.) Ohwi is a medicinal plant producing large amounts of isoflavonoid glycosides. Here, the ability of in vitro callus cultures to synthesize isoflavonoids was tested. Callus cultures have been initiated from different explants of in vitro germinated plants using modified MS medium. Roots, leaves and stem segments were the best sources of callus tissue. The isoflavonoid profile and content was determined by means of chromatographic methods. Callus from all organs contained isoflavonoid aglycones: genistein and daidzein and daidzein glycosides: daidzin, puerarin and 3'-methoxypuerarin. The differences between each kind of explant were observed in both the total amount of isoflavonoids and in the proportion of individual compounds. The highest content was in root callus, followed by leaf- and stem callus.

Chromatography, High Pressure Liquid↗
PubMed2001

Evaluation of the biological activity of crude extracts from plants used in Yucatecan traditional medicine. Part II. DNA-interacting activity.

Extracts from leaves, stems, and roots of twelve plants used commonly in Yucatecan traditional medicine were evaluated in the DNA-methyl green assay. Twenty one extracts showed DNA-interacting activity, and nine of them, belonging to five plant species, presented a displacement activity of 5% or higher. The highest activity (17.6%) was detected in the leaf extract of Heliotropium angiospermum.

DNA↗
PubMed2003

Antimycobacterial evaluation of Peruvian plants.

We present the results of an antimycobacterial screening of 270 Peruvian plant samples representing 216 species from 171 genera in 63 families. Dichloromethane extracts were tested at a concentration of 50 microg/ml for inhibition of Mycobacterium tuberculosis in radiometric culture. Slightly more than half of the samples tested showed inhibition of M. tuberculosis at this concentration.

Antitubercular Agents↗
PubMed1988

Degradation of hemicellulose and pectin by horse caecum contents.

1. Polysaccharide depolymerases and glycoside hydrolases involved in the breakdown of plant structural polysaccharides (hemicellulose and pectins) were monitored in three fractions of the liquid phase of horse caecum digesta: acellular fluid (AF), bacteria (B) and protozoa plus bacteria (PB). 2. Both bacteria and protozoa were found to be involved in the decomposition of pectic substances, with two enzymic activities: depolymerase (polygalacturonase, EC 3.2.1.15; and pectin lyase, EC 4.2.2.10) and esterase (pectinesterase, EC 3.1.1.11). The activity of the PB fraction was higher than that of B. 3. With hemicellulosic substrates, all three fractions showed a significant xylan endo-1,3-beta-xylosidase (EC 3.2.1.32) activity. Mannan was hardly broken down. 4. Galactomannan and arabinogalactan were broken down more extensively by the PB fraction than by the B fraction. Glycosidase activities (xylan 1,4-beta-xylosidase, EC 3.2.1.37 and alpha-L-arabinofuranosidase, EC 3.2.1.55) were also observed.

Animals↗
PubMedDate not supplied

Cryptococcus neoformans in Papua New Guinea: a common pathogen but an elusive source.

Around Port Moresby, Papua New Guinea (PNG), the annual incidence of cryptococcal meningitis is estimated to be up to 42.8 per million population; Cryptococcus neoformans var. gattii is the predominant causative agent. In Australia and California, environmental isolations have established an ecological association of C. neoformans var. gattii with Eucalyptus camaldulensis, E. tereticornis, and more recently E. rudis and E. gomphcephala. In PNG few E. camaldulensis survive experimental planting, E. tereticornis is endemic and there are no records of planting of the non-endemic E. rudis and E. gomphcephela. Despite extensive sampling of eucalypt-associated and other sources, we were unable to identify the ecological niche of C. neoformans var. gattii and neoformans in this region.

Cryptococcus neoformans↗
PubMed2002

Use of non-crop food vascular plants in Montseny biosphere reserve (Catalonia, Iberian Peninsula).

An ethnobotanical survey was carried out in the massif of Montseny (Catalonia, Iberian Peninsula), a mountainous UNESCO's biosphere reserve that summarizes the main European (from Mediterranean to subalpine) climates and landscapes. This article presents the results concerning the use of non-crop vascular food plants, numbering 132. Edible plants (75), as well as those involved in drink preparation (84) are considered. The study shows the different ways of preparation, preservation and consumption of plants. Most food plants also have uses as folk medicines in the region considered, and the relationships between foods and medicines are discussed. The presence and usage of wild relatives of cultivated plants in the territory studied are also commented upon.

Beverages↗
PubMed2000

Distribution and utilization of 15N in cowpeas injected into the stem under influence of water deficit.

Investigations were carried out on Vigna unguiculata L. Walp. to estimate the distribution and utilization of 15N in different organs after stem injection during vegetative, flowering and pod filling stage. During flowering effects of water deficit were also examined. In well watered plants, within 4 days after injection, 65% of 15N accumulated in leaves. This was drastically reduced to 42% by water deficit. 15N accumulation in stems increased under water deficit. The translocation of 15N from the stem base to roots were not altered by water deficit. During pod filling 62% of recovered 15N in the plants had accumulated in seeds, 24% in leaves and 11% in stems within 4 days, whereas the uptake of nitrogen in pod walls and roots remained low (2%). These results demonstrate that the method of injecting very small quantities (1 mg/plant) of 15N into the stem base allows an exact and detailed quantitative assessment of N translocation/distribution with regard to different organs, different growth stages and different treatments.

Fabaceae↗
PubMed2000

Structures of two diterpenoid dimers from bulbs of Fritillaria ebeiensis.

A new ent-kaurane diterpenoid dimer, fritillebinide C(1) together with one known diterpenoid dimer fritillebinide B (2) were isolated from the bulbs of Fritillaria ebeiensis G.D. Yu et G.Q. Ji. Compound 1 has been determined to be ent-3beta-acetoxy-kauran-16beta,17-acetal ent-16beta-kauran-17(S)-aldehyde(1) by means of spectral analysis and chemical evidence.

Chromatography↗
PubMed2000

Structural elucidations of two ent-kaurane dimers from bulbs of Fritillaria ebeiensis var. purpurea.

A novel ent-kaurane diterpenoid dimer, fritillebinide B (1) together with one known diterpenoid dimer fritillebinide A (2) were isolated from the bulbs of Fritillaria eheiensis var. purpurea G.D. Yu et P. Li. Compound 1 has been established to be ent-3beta-acetoxy-kauran-16beta,17-acetal ent-16beta-kauran-17(R)-aldehyde (1) by means of spectral analysis and chemical evidence.

Chromatography↗
PubMed2002

Triterpene and coumarins from Skimmia laureola.

In the course of our studies on the chemical constituents of the leaves of Skimmia laureola, a new triterpene O-methyl cyclolaudenol (1) and a new coumarin, (+)-7-methoxy-6-(2'R-methoxy-3'-hydroxy-3'-methyl butyl) coumarin (2) were isolated. In addition five known coumarins, isogospherol (3), heraclenol (4), 5,8-dimethoxy coumarin-2H-1-benzopyran-2-one (5), 7-methoxy-6[2'-oxo-3'-methyl butyl] coumarin (6), and (+)-ulopterol (7) were also isolated for the first time from this plant. The structures were identified by spectroscopic studies and the stereochemistry at C-2' in compounds 3 and 4 were established by Horeau's procedure.

Coumarins↗
PubMed2006

Seasonal variation of colchicine content in Colchicum brachyphyllum and Colchicum tunicatum (Colchicaceae).

As part of our continuing investigation of Jordanian Colchicum species, (-)-colchicine content in C. brachyphyllum Boiss. & Haussk. ex Boiss and Colchicum tunicatum Feinbr (Colchicaceae), growing wild in Jordan, was determined during different growth stages. Using external reference standard, a reverse-phase gradient photo-diode array high performance liquid chromatography (PDA-HPLC) method was adapted. Underground parts in both species and during different growth stages, always showed higher (-)-colchicine content than the above ground parts. In C. brachyphyllum total (-)-colchicine content of underground parts during flowering stage was found to be about 0.15% (wt/wt), while that of aerial parts was only about 0.04% (wt/wt). In C. tunicatum total (-)-colchicine content of underground parts was found to be 0.12% (wt/wt), and 0.13% (wt/wt) during flowering and vegetating stages, respectively, while that of aerial parts was only about 0.04% (wt/wt) and 0.02% (wt/wt), respectively. In C. tunicatum, stems, roots and unripe seeds are the main storages of (-)-colchicine at flowering, vegetating and seeding stages, respectively, while in C. brachyphyllum, corms are the main storage of (-)-colchicine at flowering and seeding stages.

Chromatography, High Pressure Liquid↗
PubMed1985

The measurement of whole body vibration in the workplace.

A measurement system was developed to assess the amount of whole body vibration to which workers are exposed during routine operation of machinery in an industrial setting. This system is discussed in terms of plant structural design, production levels, direction and intensity of vibrational forces, measuring equipment, proper measurement technique and field application. Comparison of field data with ANSI and ISO fatigue-decreased proficiency boundaries indicated that small press operators were not at an increased risk for impaired work efficiency. Limitations of the field survey are presented and application of this system to other occupational environments is discussed.

Efficiency↗
PubMed1999

Rac homologues and compartmentalized phosphatidylinositol 4, 5-bisphosphate act in a common pathway to regulate polar pollen tube growth.

Pollen tube cells elongate based on actin- dependent targeted secretion at the tip. Rho family small GTPases have been implicated in the regulation of related processes in animal and yeast cells. We have functionally characterized Rac type Rho family proteins that are expressed in growing pollen tubes. Expression of dominant negative Rac inhibited pollen tube elongation, whereas expression of constitutive active Rac induced depolarized growth. Pollen tube Rac was found to accumulate at the tip plasma membrane and to physically associate with a phosphatidylinositol monophosphate kinase (PtdIns P-K) activity. Phosphatidylinositol 4, 5-bisphosphate (PtdIns 4, 5-P2), the product of PtdIns P-Ks, showed a similar intracellular localization as Rac. Expression of the pleckstrin homology (PH)-domain of phospholipase C (PLC)-delta1, which binds specifically to PtdIns 4, 5-P2, inhibited pollen tube elongation. These results indicate that Rac and PtdIns 4, 5-P2 act in a common pathway to control polar pollen tube growth and provide direct evidence for a function of PtdIns 4, 5-P2 compartmentalization in the regulation of this process.

Amino Acid Sequence↗
PubMed2004

Expressional analysis of an EREBP transcription factor gene OsEBP-89 in rice.

OsEBP-89 gene encodes an ethylene responsive element binding protein (EREBP) transcription factor from rice (Oryza sativa). Northern blot analysis revealed that OsEBP-89 was expressed in root, stem, seeds, flowers and leaves of rice. Histochemical assay showed that GUS expressed mainly in phloem of vascular tissues of the root and stem transition region (RST), basal part of sheath roots, stem node and basal part of adventitious roots, also in endosperm of seeds in transgenic rice harboring OsEBP-89/GUS construct (pNSG). A sequence of region from C279 to C97 was found to play an important role for OsEBP-89 genes expression though promoter deletion assay. The possible function of OsEBP-89 gene was discussed.

Gene Expression Profiling↗
PubMed2002

Photosynthetic carbon reduction and carbon oxidation cycles are the main electron sinks for photosystem II activity during a mild drought.

Stomatal closure can explain the inhibition of net CO2 uptake by a leaf subjected to a mild drought: the photosynthetic apparatus appears resistant to lack of water. Changes in both the water content of leaves maintained in a constant environment and the ambient CO2 molar fraction during measurements on well-hydrated leaves lead to similar effects on net CO2 uptake and whole chain electron transport as estimated by leaf chlorophyll fluorescence measurements. In particular, it is shown that photosystem II (PSII) functioning and its regulation are not qualitatively changed during desiccation and that the variations in PSII photochemistry can simply be understood by changes in substrate availability in this condition. Moreover, an analysis of the literature shows that when inhibition of net CO2 uptake by C3 leaves under drought (Phaseolus vulgaris L., Helianthus annus L. and Solanum tuberosum L.) was lower than 80 %, elevated CO2 completely restored the photosynthetic capacity. The CO2 molar fraction in the chloroplasts declines as stomata close in drying leaves. As a consequence, in C3 plants, ribulose-1,5-bisphosphate oxygenation increases and becomes the main sink for photosynthetic electrons. Depending on the prevailing photon flux density, the O2 uptake through photorespiratory activity can entirely replace carbon dioxide as an electron acceptor, or not. The rate of the Mehler reaction remains low and unchanged during desiccation. However, drought could also involve CO2-sensitive modification of the photosynthetic metabolism depending on plant growth conditions and possibly also on plant species.

Carbon↗
PubMed2002

Regulation of photosynthesis of C3 plants in response to progressive drought: stomatal conductance as a reference parameter.

We review the photosynthetic responses to drought in field-grown grapevines and other species. As in other plant species, the relationship between photosynthesis and leaf water potential and/or relative water content in field-grown grapevines depends on conditions during plant growth and measurements. However, when light-saturated stomatal conductance was used as the reference parameter to reflect drought intensity, a common response pattern was observed that was much less dependent on the species and conditions. Many photosynthetic parameters (e.g. electron transport rate, carboxylation efficiency, intrinsic water-use efficiency, respiration rate in the light, etc.) were also more strongly correlated with stomatal conductance than with water status itself. Moreover, steady-state chlorophyll fluorescence also showed a high dependency on stomatal conductance. This is discussed in terms of an integrated down-regulation of the whole photosynthetic process by CO2 availability in the mesophyll. A study with six Mediterranean shrubs revealed that, in spite of some marked interspecific differences, all followed the same pattern of dependence of photosynthetic processes on stomatal conductance, and this pattern was quite similar to that of grapevines. Further analysis of the available literature suggests that the above-mentioned pattern is general for C3 plants. Even though the patterns described do not necessarily imply a cause and effect relationship, they can help our understanding of the apparent contradictions concerning stomatal vs. non-stomatal limitations to photosynthesis under drought. The significance of these findings for the improvement of water-use efficiency of crops is discussed.

Biological Transport↗
PubMed2003

Refilling of a hydraulically isolated embolized xylem vessel: model calculations.

When they are hydraulically isolated, embolized xylem vessels can be refilled, while adjacent vessels remain under tension. This implies that the pressure of water in the refilling vessel must be equal to the bubble gas pressure, which sets physical constraints for recovery. A model of water exudation into the cylindrical vessel and of bubble dissolution based on the assumption of hydraulic isolation is developed. Refilling is made possible by the turgor of the living cells adjacent to the refilling vessel, and by a reflection coefficient below 1 for the exchange of solutes across the interface between the vessel and the adjacent cells. No active transport of solutes is assumed. Living cells are also capable of importing water from the water-conducting vessels. The most limiting factors were found to be the osmotic potential of living cells and the ratio of the volume of the adjacent living cells to that of the embolized vessel. With values for these of 1.5 MPa and 1, respectively, refilling times were in the order of hours for a broad range of possible values of water conductivity coefficients and effective diffusion distances for dissolved air, when the xylem water tension was below 0.6 MPa and constant. Inclusion of the daily pattern for xylem tension improved the simulations. The simulated gas pressure within the refilling vessel was in accordance with recent experimental results. The study shows that the refilling process is physically possible under hydraulic isolation, while water in surrounding vessels is under negative pressure. However, the osmotic potentials in the refilling vessel tend to be large (in the order of 1 MPa). Only if the xylem water tension is, at most, twice atmospheric pressure, the reflection coefficient remains close to 1 (0.95) and the ratio of the volume of the adjacent living cells to that of the embolized vessel is about 2, does the osmotic potential stay below 0.4 MPa.

Air↗