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PubMed1978

Leucine: tRNA Ligase from Cultured Cells of Nicotiana tabacum var. Xanthi: Evidence for de Novo Synthesis and for Loss of Functional Enzyme Molecules.

Leucine:tRNA ligase was assayed in extracts from cultured tobacco (Nicotiana tabacum) XD cells by measuring the initial rate of aminoacylation of transfer RNA with l-[4,5-(3)H]leucine. Transfer RNA was purified from tobacco XD cells after the method of Vanderhoef et al. (Phytochemistry 9: 2291-2304). The buoyant density of leucine:tRNA ligase from cells grown for 100 generations in 2.5 mm [(15)N]nitrate and 30% deuterium oxide was 1.3397. After transfer of cells into light medium (2.5 mm [(14)N]nitrate and 100% H(2)O) the ligase activity increased and the buoyant density decreased with time to 1.3174 at 72 hours after transfer. It was concluded that leucine:tRNA ligase molecules were synthesized de novo from light amino acids during the period of activity increase. The width at half-peak height of the enzyme distribution profiles following isopycnic equilibrium centrifugation in caesium chloride remained constant at all times after transfer into light medium providing evidence for the loss of preexisting functional ligase molecules. It was concluded that during the period of activity increase the cellular level of enzyme activity was determined by a balance between de novo synthesis and the loss of functional enzyme molecules due to either inactivation or degradation.

Journal Article↗
PubMed1978

Characterization of protoheme levels in etiolated and greening plant tissues.

The protoheme content of etiolated, greening, and fully greened bean (Phaseolus vulgaris L. var. Light Red Kidney) leaves has been studied. The protoheme level in etiolated and fully greened leaf tissue stays relatively constant from age 7 to 14 days. In agreement with the studies reported for barley (Castelfranco and Jones 1975 Plant Physiol 55: 485-490), the protoheme content of greening bean and barley (Hordeum vulgare var. Larker) leaves does not change appreciably during the first 9 hours of illumination, but the level rises significantly by the 24th hour of illumination (cf. Hendry and Stobart 1977 Phytochemistry 16: 1545-1548). This increase also occurs in seedlings returned to the dark for 24 to 48 hours following a 10-minute pulse of light. These results demonstrate a limited correlation with previous studies on the development of b-type cytochromes during greening of these tissues (Gregory and Bradbeer 1973; Planta 109: 317-326).

Journal Article↗
PubMed1981

Cytokinins from the Moss Physcomitrella patens.

Gametophore-over-producing mutants of the moss, Physcomitrella patens, when grown in liquid culture export high levels of cytokinin into their culture medium. The cytokinin produced by these mutants is postulated to account for their peculiar phenotype, that of mosses treated with exogenous cytokinin. N(6)-(Delta(2)-isopentenyl)adenine, the major cytokinin, has been identified previously in two of these mutants (Wang, Cove, Beutelmann, Hartmann 1980 Phytochemistry 19: 1103-1105) and now in additional representatives. A second cytokinin, zeatin, has been identified by its chromatographic behavior and mass spectrum including chemical ionization mass spectrometry of its permethyl derivative.

Journal Article↗
PubMed1983

Effect of Varying CO(2) Partial Pressure on Photosynthesis and on Carbon Isotope Composition of Carbon-4 of Malate from the Crassulacean Acid Metabolism Plant Kalanchoë daigremontiana Hamet et Perr.

Intact leaves of Kalanchoë daigremontiana were exposed to CO(2) partial pressures of 100, 300, and 1000 microbars. Malic acid was extracted, purified, and degraded in order to obtain isotopic composition of carbon-1 and carbon-4. From these data, it is possible to calculate the carbon isotope composition of newly fixed carbon in malate. In all three treatments, the isotopic composition of newly introduced carbon is the same as that of the CO(2) source and is independent of CO(2) partial pressures over the range tested. Comparison with numerical models described previously (O'Leary 1981 Phytochemistry 20: 553-567) indicates that we would expect carbon 4 of malate to be 4 per thousand more negative than source CO(2) if diffusion is totally limiting or 7 per thousand more positive than source CO(2) if carboxylation is totally limiting. Our results demonstrate that stomatal aperture adjusts to changing CO(2) partial pressures and maintains the ratio of diffusion resistance to carboxylation resistance approximately constant. In this study, carboxylation and diffusion resistances balance so that essentially no fractionation occurs during malate synthesis. Gas exchange studies of the same leaves from which malate was extracted show that the extent of malate synthesis over the whole night is nearly independent of CO(2) partial pressure, although there are small variations in CO(2) uptake rate. Both the gas exchange and the isotope studies indicate that the ratio of external to internal CO(2) partial pressure is the same in all three treatments. Inasmuch as a constant ratio will result in constant isotope fractionation, this observation may explain why plants in general have fairly invariable (13)C contents, despite growing under a variety of environmental conditions.

Journal Article↗
PubMed1984

Effects of exogenous methionine on storage protein composition of soybean cotyledons cultured in vitro.

Supplemental methionine in a complete culture medium increased the methionine content of the protein fraction of cultured soybean (Glycine max L. Merrill) cotyledons (Thompson, Madison, Muenster 1981 Phytochemistry 20: 941-945). To explain the observed increase in protein methionine, we have measured the amounts and subunit compositions of 7S and 11S storage proteins and determined the amino acid compositions of the three major protein fractions (2-5S, 7S, 11S) of seeds developed on plants and of cultured cotyledons grown in the presence or absence of supplemental l-methionine. Development of cultured cotyledons was representative of development of seeds on plants. The ratios of 11S to 7S proteins, the subunit contents, and amino acid compositions of their storage protein fractions were similar, but not identical. Supplemental methionine increased the mole percent methionine in each of the three protein fractions of cultured cotyledons and changed the amounts of several other amino acids. Supplemental methionine inhibited expression of the 7S beta-subunit gene. Concomitant with the absence of the beta-subunit, which contains no methionine, was an increase in the ratio of 11S to 7S proteins, and an increase in the methionine content of the subunits composing these fractions. Inhibition of beta-subunit gene expression by methionine in cultured cotyledons provides a reproducible, easily controlled system for the study of eucaryotic gene expression.

Journal Article↗
PubMed1985

Stereochemical aspects of the biosynthesis of the side chain of 9beta, 19-cyclopropyl sterols in maize seedlings treated with tridemorph.

9beta, 19-Cyclopropyl sterols such as 24-methyl pollinastanol accumulate dramatically in maize (Zea mays L. var LG 11) seedlings treated with Tridemorph (2,6-dimethyl-N-tridecyl-morpholine), a systemic fungicide (M. Bladocha, P. Benveniste, Plant Physiol 1983 41: 756-762). In contrast to the situation in control plants where 24-ethyl sterols predominate largely, 24-methyl sterols were more than 98% of total cyclopropyl sterols. In addition, 24-methyl cyclopropyl sterols were a mixture of (24-R)- and (24-S)-24-methyl epimers and are similar in that respect to the 24-methyl cholesterol of control plants. The presence of two epimers at C-24 has been previously explained by the operation of two routes (M. Zakelj, L. J. Goad, Phytochemistry 1983 22: 1931-1936). One may proceed via Delta(24(28))- and Delta(24(25))-sterols to produce the (24-R)-24-methyl epimer. The other route may involve reduction of either a Delta(24(28))-, a Delta(23)-, or a Delta(25)-sterol intermediate to give the (24-S)-24-methyl epimer. Such intermediates have been searched for in excised Zea mays axes grown aseptically in the presence of Tridemorph and either [5-(14)C]mevalonic acid, or [Me-(14)C]-l-methionine. Whereas Delta(24(28))- and Delta(24(25))-cyclopropyl sterols were found in relatively large amounts, only traces of radioactivity were associated with Delta(25)-sterols. Gas chromatography/mass spectrometry analysis of the sterols from axes grown in the presence of [Me-(2)H(3)]-l-methionine showed that Delta(24(28))-cyclopropyl sterols contained only two (2)H atoms at C-28 as expected and that the 24-methyl pollinastanol fraction contained species with two (2)H atoms and no species with three (2)H atoms. These results indicate that both (24-R)- and (24-S)-epimers originate from a common Delta(24(28)) precursor. After incubation of the axis with [5-(14)C,(4-R)-4-(3)H(1)]mevalonic acid, the 24-methyl pollinastanol had a (3)H:(14)C atomic ratio of 4:6 which is consistent with the intermediacy of a Delta(24(25))-sterol. All these data are in accordance with a pathway where Delta(24(28))-cyclopropyl sterols are isomerized to give Delta(24(25))-cyclopropyl sterols which in turn would be reduced nonregiospecifically to yield both (24-R)- and (24-S)-24-methyl pollinastanols. A plausible mechanism for the reduction step is discussed.

Journal Article↗
PubMed1986

Stem infusions enhanced methionine content of soybean storage protein.

The quality of soybean (Glycine max [L.] Merrill) seed storage protein is limited by its low methionine (Met) content. Met supplementation of an in vitro soybean cotyledon culture has been shown to increase Met content by 21.9% due to an inhibition of the synthesis of the Met-devoid beta subunit of 7S storage protein (JF Thompson et al. 1981, Phytochemistry 20: 941-945). The objective of this research was to determine if Met supplementation of intact plants would result in a similar improvement in soybean protein quality. A solution including 10 millimolar d,l malic acid plus 10 millimolar K(2)HPO(4) with or without 20 millimolar d,l Met or 20 millimolar Na(2)SO(4) was infused throughout seed development into lower stem internodes of soybeans (cv ;Williams 79' or ;Williams 82') grown under both greenhouse and field conditions. Pediatric intravenous kits were used to infuse an average of 51.2 milliliters per plant. Met content of whole soybean seeds from intact plants receiving Met infusions increased by as much as 22.7%. Even greater (up to 31.0%) increases in cysteine (Cys) content were noted, indicating that soybean plants are able to metabolize Met to Cys, or that supplemental Met allows Cys accumulation by some other mechanism. Electrophoretic patterns showed a dramatic decrease in the synthesis of the beta subunit of 7S storage protein when Met was supplemented, and this effect was not confined to seeds at the lower nodes. In addition, seeds from upper compared to lower plant nodes (regardless of infusion treatment) had greater protein content (45.0 versus 41.6 w/w%), and different protein composition, as indicated by significantly different amino acid profiles. Methionine supplementation of intact soybean plants improved protein quality through an alteration in storage protein composition.

Journal Article↗
PubMed1990

Purification and characterization of an inducible sesquiterpene cyclase from elicitor-treated tobacco cell suspension cultures.

An elicitor-inducible sesquiterpene cyclase, which catalyzes the conversion of farnesyl diphosphate to 5-epi-aristolochene (IM Whitehead, DR Threlfall, DF Ewing [1989] Phytochemistry 28:775-779) and representing a committed step in the phytoalexin biosynthetic pathway in tobacco, was purified by a combination of hydrophobic interaction, anion exchange, hydroxylapatite, and chromatofocusing chromatography. From 2 kilograms of elicited tobacco (Nicotiana tabacum) cells, approximately 500 micrograms of cyclase protein was purified, representing greater than a 130-fold increase in the specific activity of the enzyme and a 4% recovery of the starting activity. The purified enzyme resolved as two major polypeptides of 60 and 62 kilodaltons by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Biochemical characterization of the enzyme activity included an absolute requirement for magnesium, an isoelectric point of 4.5 to 4.9, and a K(m) for farnesyl diphosphate of 2 to 5 micromolar. The purified cyclase protein was used to generate mouse polyclonal antibodies which efficiently inhibited cyclase activity in an in vitro assay. Electrophoresis of extracts from elicitor-treated cells or purified cyclase enzyme on native polyacrylamide gels separated the cyclase enzyme into four polypeptides as shown by immunoblot analysis using poly- and monoclonal antibodies. Proportionate cyclase enzyme activity comigrated with those polypeptides. No cyclase polypeptides were detectable in extracts of control cells by immunoblot analysis. However, immunoblot analysis of proteins from elicitor-treated cells using four independent monoclonal antibody lines and the polyclonal antibodies detected the same polypeptides, regardless of whether the proteins were separated by native or SDS-PAGE. The results suggest an induction of multiple cyclase polypeptides in elicitor-treated cells resulting from either the expression of multiple genes or multiple post-translational processing events.

Journal Article↗
PubMed2004

Gibberellin structure and function: biological activity and competitive inhibition of gibberellin 2- and 3-oxidases.

Some gibberellin (GA) analogues, especially with C-16,17 modifications of GA(5), can inhibit growth of plants apparently by acting as competitors with the endogenous substrate of GA biosynthetic enzymes. Here, we directly confirm the competitive action of GA derivatives but also show that some analogues may retain significant bioactivity. A recombinant 3-oxidase from pea, which converts GA(20) to bioactive GA(1), was inhibited by GA(5), and 16,17-dihydro-GA(5) derivatives, especially if the C-17 alkyl chain length was increased by up to three carbons or if the C-13 hydroxyl was acetylated. Genetic confirmation that GA(5) analogues target 3-oxidases in vivo was provided by comparing the growth response of a WT (LE) pea with a 3-oxidase mutant (le-1). Two pea 2-oxidases that inactivate bioactive GAs, were inhibited by GA(1) and GA(3) but were generally insensitive to GA(5) analogues. alpha-Amylase production by barley half-seeds in response to GA analogues provided a method to study their action when effects on GA biosynthesis were excluded. This bioactivity assay showed that 16,17-dihydro GA(5) analogues have some inherent activity but mostly less than for GA(5) (5-50-fold), which in turn was 100-fold less active than GA(1) and GA(3). However, although C-17 alkyl derivatives with one or two added carbons showed little bioactivity and were purely 3-oxidase inhibitors, adding a third carbon (the 17-n-propyl-16,17-dihydro GA(5) analogue) restored bioactivity to that of GA(5). Furthermore, this analogue has lost its capacity to inhibit stem elongation of Lolium temulentum (Mander et al., Phytochemistry 49:1509-1515, 1998a), although it strongly inhibits the 3-oxidase. Thus, the effectiveness of a GA derivative as a growth retardant will reflect the balance between its bioactivity and its capacity to inhibit the terminal enzyme of GA biosynthesis. The weaker growth inhibition in dicots including pea (approximately 10%) than in monocots such as L. temulentum (>35%) is suggestive of taxonomic differences in the bioactivity of GAs and/or their effects on GA biosynthesis.

Journal Article↗
PubMed1993

The separate roles of plant cis and trans prenyl transferases in cis-1,4-polyisoprene biosynthesis.

In plants, the elongation of cis-1,4-polyisoprene (natural rubber, M(r) > 10(6) requires a small transallylic diphosphate (< or = C20) initiator. The trans-allylic diphosphates are hydrophilic cytosolic compounds, whereas cis-1,4-polyisoprene is hydrophobic and compartmentalised in subcellular rubber particles. In this paper, it is demonstrated that soluble trans-prenyl transferase from latex of Hevea brasiliensis functions solely as farnesyl diphosphate synthase, and plays no direct role in cis-1,4-polyisoprene elongation. The cis-1,4-prenyl transferase is firmly associated with the H. brasiliensis rubber particle, as is also the case in other rubber-producing species [Archer, B. L., Audley, B. G., Cockbain, E. G. & McSweeney, G. P. (1963) Biochem. J. 89, 565-574; Madhavan, S., Greenblatt, G. A., Foster, M. A. & Benedict, C. R. (1989) Plant Physiol. 89, 506-511; Siler, D. J. & Cornish, K. (1993) Phytochemistry 32, 1097-1102]. The experimental data explain and refute previous reports in which soluble trans-prenyl transferase isolated from H. brasilensis latex was attributed both trans-prenyl transferase and cis-prenyl transferase activities [Light, D. R. & Dennis, M. S. (1989) J. Biol. Chem. 264, 18589-18597; Light, D. R., Lazarus, R. A. & Dennis, M. S. (1989) J. Biol. Chem. 264, 18598-18607]. Thus, it appears that plant prenyl transferases are comparable to animal enzyme systems in which trans-prenyl transferases are soluble enzymes whilst cis-prenyl transferases are membrane-bound [Ericcson, J., Runquist, M., Thelin, A., Andersson, M., Chojnacki, T. & Dallner, G. (1992) J. Biol Chem. 268, 832-838].

Dimethylallyltranstransferase↗
PubMed2006

Importance of species interactions to community heritability: a genetic basis to trophic-level interactions.

Recent community genetics studies have shown that specific genotypes of a host plant support distinct arthropod communities. Building upon these findings, we examined the hypothesis that a trophic community consisting of cottonwood trees, a galling herbivore and avian predators could also be related to the genetics of the host tree. We found genetic correlations among phytochemistry of individual tree genotypes, the density of a galling herbivore, and the intensity of avian predation on these herbivores. We detected significant broad-sense heritability of these interactions that range from H(B)2 = 0.70 to 0.83. The genetic basis of these interactions tended to increase across trophic levels suggesting that small genetic changes in the cottonwood phenotype could have major consequences at higher trophic levels affecting species interactions and energy flow. These findings show a heritable basis to trophic-level interactions indicating that there is a significant genetic basis to community composition and energy flow that is predictable by plant genotype. Our data clearly link plant genetics to patterns of avian foraging and show that species interactions are important components of community heritability and ecosystem processes. Overall, these data support the hypothesis that evolution of plant traits can alter trophic-level interactions and community composition.

Animals↗
PubMed1981

Compositae dermatitis. Current aspects.

Clinical features, botany, phytochemistry, patch testing, ecology and the absence of a role for pollen in Compositae dermatitis are discussed with a review of current aspects of photosensitivity for pathogenesis. It appears that the plants yield photoallergen(s) not yet identified.

Allergens↗
PubMed1997

Stimulation of aryl metabolite production in the basidiomycete Bjerkandera sp. strain BOS55 with biosynthetic precursors and lignin degradation products.

Aryl metabolites are known to have an important role in the ligninolytic system of white rot fungi. The addition of known precursors and aromatic acids representing lignin degradation products stimulated the production of aryl metabolites (veratryl alcohol, veratraldehyde, p-anisaldehyde, and 3-chloro-p-anisaldehyde) in the white rot fungus Bjerkandera sp. strain BOS55. The presence of manganese (Mn) is known to inhibit the biosynthesis of veratryl alcohol (T. Mester, E. de Jong, and J.A. Field, Appl. Environ. Microbiol. 61:1881-1887, 1995). A new finding of this study was that the production of the other aryl metabolites, p-anisaldehyde and 3-chloro-p-anisaldehyde, was also inhibited by Mn. We attempted to bypass the Mn-inhibited step in the biosynthesis of aryl metabolites by the addition of known and suspected precursors. Most of these compounds were not able to bypass the inhibiting effect of Mn. Only the fully methylated precursors (veratrate, p-anisate, and 3-chloro-p-anisate) provided similar concentrations of aryl metabolites in the presence and absence of Mn, indicating that Mn does not influence the reduction of the benzylic acid group. The addition of deuterated benzoate and 4-hydroxybenzoate resulted in the formation of deuterated aryl metabolites, indicating that these aromatic acids entered into the biosynthetic pathway and were common intermediates to all aryl metabolites. Only deuterated chlorinated anisyl metabolites were produced when the cultures were supplemented with deuterated 3-chloro-4-hydroxybenzoate. This observation combined with the fact that 3-chloro-4-hydroxybenzoate is a natural product of Bjerkandera spp. (H. J. Swarts, F. J. M. Verhagen, J. A. Field, and J. B. P. A. Wijnberg, Phytochemistry 42:1699-1701, 1996) suggest that it is a possible intermediate in chlorinated anisyl metabolite biosynthesis.

Basidiomycota↗
PubMed1976

Potential anti-fertility plants from Chinese medicine.

A brief review of the history of development of Chinese pharmacognosy and its application to gynecology and obstetrics is presented. An evaluation system is introduced for short-listing some potentially useful and anti-fertility plants. Twenty such plants are listed in order of priority according to our evaluation system. Brief descriptions of the botany, phytochemistry and reputed biological effects are provided. It is hoped that this article may provide an impetus for the development of new antifertility agents.

Abortifacient Agents↗
PubMedDate not supplied

Isolation of the uterotonic principle from Leonurus artemisia, the Chinese motherwort.

A search in ancient Chinese medicinal literature and modern phytochemical references indicates that the therapeutic value of Leonurus artemisia (I-mu ts'ao, the Chinese motherwort) might reside in a uterotonic principle present in leaves. Leonurine (4-guanidino-n-butyl syringate) was isolated from fresh and dry leaves of Leonurus artemisia. The uterotonic effect of leonurine was demonstrated in rat uterus in vitro. Results from this study suggest that functional phytochemistry based on ethnobotanical experience could lead to development of new and effective drugs from Chinese medicine.

China↗
PubMed1997

Traditional herbal medicines used to treat wounds and injuries in Nepal.

In rural Nepalese societies, due to the lack of modern health services and facilities, folk herbal preparations are still the dominant method of therapy for common ailments. These remedies are fairly well accepted, easily available, bear a minimal cost and are generally the only available resource. Information on the curative properties of 42 plant species from 40 genera and 23 families that are used to treat wounds and injuries, has been documented. These herbal remedies are based on ancestral knowledge and personal experience. Their successful use indicates that they are alive and functioning in the rural localities. Although the techniques of preparation of drugs or dosage forms employed by traditional healers have generally been observed to be poor and in most cases do not comply with the requirements of modern pharmaceutical practices, there are trends towards the development and modernization of practice including the standardization of specific dosage, storage of drugs, use of specific types of containers and their labelling. A critical evaluation of the phytochemistry and pharmacology of the alleged curative plants and the traditional pharmaceutical practices employed has been strongly recommended. In rural Nepalese societies, the number and distribution of traditional herbal practitioners and faith healers greatly exceed all other health workers. Their influence should be applied to the task of motivating the rural populace to adopt authentic herbal remedies and other health-related hygienic behaviour.

Humans↗
PubMed2006

Gitksan medicinal plants--cultural choice and efficacy.

BACKGROUND: The use of plants for healing by any cultural group is integrally related to local concepts of the nature of disease, the nature of plants, and the world view of the culture. The physical and chemical properties of the plants themselves also bear on their selection by people for medicines, as does the array of plants available for people to choose from. I examine use of medicinal plants from a "biobehavioral" perspective to illuminate cultural selection of plants used for medicine by the Gitksan of northwestern British Columbia, Canada. METHODS: Consultant consensus, "intercultural consensus", independent use of the same plants by other cultural groups, and phytochemistry and bioassay results from the literature, were employed in analysis of probable empirical efficacy of plant uses. RESULTS: 70% of 37 Gitksan medicinal plants were used similarly by other cultures where direct diffusion is not known to have occurred; eleven plants, including the eight most frequently mentioned medicinal plants, also show active phytochemicals or bioassays indicating probable physiologically based therapeutic effects. CONCLUSION: Analysis of intercultural consensus revealed that the majority of cultures in the British Columbia region within the plant ranges use the same plants, or closely related species, in similar ways. The rigor of this analysis is effected by the lack of consistent data on all taxa of interest for all cultures within the region.

British Columbia↗
PubMed2001

Pharmacognosy in the 21st century.

The term pharmacognosy as a constituent scientific discipline of pharmacy has been in use for nearly 200 years, and it refers to studies on natural product drugs. During the last half of the 20th century, pharmacognosy evolved from being a descriptive botanical subject to one having a more chemical and biological focus. At the beginning of the 21st century, pharmacognosy teaching in academic pharmacy institutions has been given new relevance, as a result of the explosive growth in the use of herbal remedies (phytomedicines) in modern pharmacy practice, particularly in western Europe and North America. In turn, pharmacognosy research areas are continuing to expand, and now include aspects of cell and molecular biology in relation to natural products, ethnobotany and phytotherapy, in addition to the more traditional analytical method development and phytochemistry. Examples are provided in this review of promising bioactive compounds obtained in two multidisciplinary natural product drug discovery projects, aimed at the elucidation of new plant-derived cancer chemotherapeutic agents and novel cancer chemopreventives, respectively. The systematic study of herbal remedies offers pharmacognosy groups an attractive new area of research, ranging from investigating the biologically active principles of phytomedicines and their mode of action and potential drug interactions, to quality control, and involvement in clinical trials.

Animals↗