| [effects of nordihydroguairetic acid and ethanol on the growth of entamoeba invadens]. | the effects of the alcoholic extract (resin) obtained from larrea tridentata, of nordihydroguiaretic acid (ndga) and of ethanol over axenic cultures of entamoeba invadens pz strain were studied. the activity of these substances was demonstrated in growht curves. inocula of 1-3 x 10(5) trophozites by milliliter in culture tubes containing 11 ml of tp-s-1 medium were done, and incubated at 25 degree c. in each experiment the follwoing was done: a) tipical growth curve as a control, b) curve with t ... | 1978 | 211947 |
| [isolation of kumatakenine and 5,4'-dihydroxy-3,7,3'-trimethoxiflavone from larrea tridentata]. | | 1974 | 4849012 |
| antiviral activities of methylated nordihydroguaiaretic acids. 1. synthesis, structure identification, and inhibition of tat-regulated hiv transactivation. | nordihydroguaiaretic acid (ndga, meso-1) possesses four phenolic hydroxyl groups. treatment of ndga with 0.50-4.1 equiv of dimethyl sulfate and 3.0-6.0 equiv of potassium carbonate in acetone at 56 degrees c gave nine methylated products. eight of those mono-, di-, tri-, and tetra-o-methylated ndgas were isolated in pure form, and their structures were identified unambiguously by spectroscopic methods. a preparative amount of tetramethyl ndga m4n (10) was obtained in 99% yield from ndga by use o ... | 1998 | 9685238 |
| chemical studies of phytoestrogens and related compounds in dietary supplements: flax and chaparral. | high-performance liquid chromatographic (hplc) and mass spectrometric (ms) procedures were developed to determine lignans in flaxseed (linum usitatissimum) and chaparral (larrea tridentata). flaxseed contains high levels of phytoestrogens. chaparral has been associated with acute nonviral toxic hepatitis and contains lignans that are structurally similar to known estrogenic compounds. both flaxseed and chaparral products have been marketed as dietary supplements. a mild enzyme hydrolysis procedu ... | 1995 | 7892296 |
| inhibition of human immunodeficiency virus type 1 transcription and replication by dna sequence-selective plant lignans. | a plant lignan, 3'-o-methyl nordihydroguaiaretic acid (3'-o-methyl ndga, denoted malachi 4:5-6 or mal.4; molecular weigth 316), was isolated from larrea tridentata and found to be able to inhibit human immunodeficiency virus (hiv) tat-regulated transactivation in vivo, induce protection of lymphoblastoid cem-ss cells from hiv (strain iiib) killing, and suppress the replication of five hiv-1 strains (wm, mn, vs, jr-csf, and iiib) in mitogen-stimulated peripheral blood mononuclear cells, all in a ... | 1995 | 7479972 |
| soil ecology of coccidioides immitis at amerindian middens in california. | outbreaks of coccidioidomycosis and isolation of coccidioides immitis have been reported from amerindian middens. this study was undertaken to determine the most important ecological component(s) for the occurrence of c. immitis at archeological sites. soils from 10 former indian villages with no prior history of coccidioidal infection were collected and cultured. the physicochemical properties of the midden soils were compared with nonmidden soils and positive soils. the following theories for ... | 1974 | 4856715 |
| contact dermatitis from larrea (creosote bush). | six men suffering from acute dermatitis had positive patch tests to larrea (creosote bush). the lesions preferentially involved sun-exposed sites, simulating a photodermatitis, but also were on the legs and scrotum. our findings were more consistent with contact allergy than with a primary irritant or a phototoxic response. the patch tests were also positive to zuccagnia punctata. in two cases the exposure to the creosote bush occurred as a result of casual occupations, in two because of househo ... | 1986 | 3950120 |
| contact dermatitis from larrea tridentata (creosote bush) | | 1986 | 3745539 |
| furanoid lignans from larrea tridentata. | from the leaves and stems of larrea tridentata six new furanoid lignans, compounds 1-6, have been isolated and their structures determined through interpretation of physical and spectroscopic properties. the use of 1d and 2d noe experiments was of particular importance in assigning the stereochemistry. | 1990 | 2166136 |
| chaparral-induced toxic hepatitis--california and texas, 1992. | cases of acute toxic hepatitis in two patients--one in california and one in texas--have been attributed to ingestion of an herbal nutritional supplement product derived from the leaves of the creosote bush known commonly as chaparral. this report summarizes the investigations of these cases. | 1992 | 1406577 |
| detoxification in relation to toxin tolerance in desert woodrats eating creosote bush. | we studied the relationship between the use of three detoxification pathways and urine ph and the tolerance of desert woodrats from two populations to a mixture of naturally occurring plant secondary metabolites (mostly phenolics) in resin from creosote bush (larrea tridentata). the two populations of desert woodrats came from the mojave desert (mojave woodrats), where woodrats consume creosote bush, and from the great basin desert (great basin woodrats), where the plant species is absent. we fe ... | 2001 | 11789959 |
| [effect of alcoholic extracts of wild plants on the inhibition of growth of aspergillus flavus, aspergillus niger, penicillium chrysogenum, penicillium expansum, fusarium moniliforme and fusarium poae moulds]. | fungicidal activity of wild plants larrea tridentata, karwinskia humboldtiana, ricinus communis, eucalyptus globulus, ambrosia ambrosioides, nicotiana glauca, ambrosia confertiflora, datura discolor, baccharis glutinosa, proboscidea parviflora, solanum rostratum, jatropha cinerea, salpianthus macrodonthus y sarcostemma cynanchoides was evaluated against the moulds species aspergillus flavus, aspergillus niger, penicillium chrysogenum, penicillium expansum, fusarium poae y fusarium moniliforme mo ... | 2002 | 12828509 |
| absorption of copper(ii) by creosote bush (larrea tridentata): use of atomic and x-ray absorption spectroscopy. | larrea tridentata (creosote bush), a common north american native desert shrub, exhibits the ability to take up copper(ii) ions rapidly from solution. following hydroponic studies, u.s. environmental protection agency method 200.3 was used to digest the plant samples, and flame atomic absorption spectroscopy (faas) was used to determine the amount of copper taken up in different parts of the plant. the amount of copper(ii) found within the roots, stems, and leaves was 13.8, 1.1, and 0.6 mg/g, re ... | 2001 | 11699784 |
| molecular phylogeny of larrea and its allies (zygophyllaceae): reticulate evolution and the probable time of creosote bush arrival to north america. | nucleotide sequences of rubisco large subunit (rbcl) and the internal transcribed spacers (its) of nrdna were obtained for the five species of larrea and one species each of bulnesia (its only) and plectrocarpa (rbcl only). parsimony analyses were conducted, including sequences from seven genera of zygophyllaceae reported by other authors-kallstroemia, zygophyllum, augea, fagonia, pintoa, guaiacum, and porlieria. the main conclusions of the present study are (1) the argentine endemic plectrocarp ... | 2001 | 11697924 |
| root communication among desert shrubs. | descriptive and experimental studies of desert shrub distributions have revealed important questions about the mechanisms by which plants interact. for example, do roots interact by mechanisms other than simple competition for limiting resources? we investigated this question using the desert shrubs ambrosia dumosa and larrea tridentata grown in chambers that allowed observation of roots during intraplant and intra- and interspecific interplant encounters. two types of root "communication" were ... | 1991 | 11607151 |
| a conceptual model for primary productivity, decomposition and nitrogen cycling in the chihuahuan creosotebush desert. | the conceptual framework for a simulation model of primary productivity, decomposition and nitrogen cycling in a shrub-dominated desert ecosystem in southern new mexico is presented. this model is based on our previous attempt to simulate carbon allocation patterns in the desert shrub larrea tridentata cov., which demonstrated that moisture patterns alone are insufficient to predict desert productivity. these results, as well as others, suggest that mineral nutrients, especially nitrogen, may al ... | 1986 | 14975855 |
| the safety of low-dose larrea tridentata (dc) coville (creosote bush or chaparral): a retrospective clinical study. | to determine whether internal use of low doses of larrea tridentata tincture or topical applications of this traditional herbal medicine are safe. | 2001 | 11327523 |
| masoprocol decreases serum triglyceride concentrations in rats with fructose-induced hypertriglyceridemia. | historically, extracts of the creosote bush have been used by native healers of the southwest region of north america to treat symptoms of type 2 diabetes. more recently, we have shown that masoprocol (nordihydroguaiaretic acid), a pure compound isolated from the creosote bush (larrea tridentata), decreases serum glucose and triglyceride (tg) levels when administered orally in rodent models of type 2 diabetes. the present studies were undertaken to determine if masoprocol also decreases tg conce ... | 2000 | 11016888 |
| vulnerability to xylem cavitation and the distribution of sonoran desert vegetation. | we studied 15 riparian and upland sonoran desert species to evaluate how the limitation of xylem pressure (psi(x)) by cavitation corresponded with plant distribution along a moisture gradient. riparian species were obligate riparian trees (fraxinus velutina, populus fremontii, and salix gooddingii), native shrubs (baccharis: spp.), and an exotic shrub (tamarix ramosissima). upland species were evergreen (juniperus monosperma, larrea tridentata), drought-deciduous (ambrosia dumosa, encelia farino ... | 2000 | 10991900 |
| masoprocol decreases rat lipolytic activity by decreasing the phosphorylation of hsl. | masoprocol (nordihydroguaiaretic acid), a lipoxygenase inhibitor isolated from the creosote bush, has been shown to decrease adipose tissue lipolytic activity both in vivo and in vitro. the present study was initiated to test the hypothesis that the decrease in lipolytic activity by masoprocol resulted from modulation of adipose tissue hormone-sensitive lipase (hsl) activity. the results indicate that oral administration of masoprocol to rats with fructose-induced hypertriglyceridemia significan ... | 2000 | 10950827 |
| hepatotoxicity of botanicals. | hepatic impairment resulting from the use of conventional drugs is widely acknowledged, but there is less awareness of the potential hepatotoxicity of herbal preparations and other botanicals, many of which are believed to be harmless and are commonly used for self-medication without supervision. the aim of this paper is to examine the evidence for hepatotoxicity of botanicals and draw conclusions regarding their pathology, safety and applications. | 2000 | 10948380 |
| origins and ecological consequences of pollen specialization among desert bees. | an understanding of the evolutionary origins of insect foraging specialization is often hindered by a poor biogeographical and palaeoecological record. the historical biogeography (20,000 years before present to the present) of the desert-limited plant, creosote bush (larrea tridentata), is remarkably complete. this history coupled with the distribution pattern of its bee fauna suggests pollen specialization for creosote bush pollen has evolved repeatedly among bees in the lower sonoran and moja ... | 2000 | 10714881 |
| effect of masoprocol on glucose transport and lipolysis by isolated rat adipocytes. | masoprocol (nordihydroguaiaretic acid) is a lipoxygenase inhibitor isolated from the creosote bush and used by native healers to treat type 2 diabetes. it has been recently shown to decrease serum glucose, free fatty acid (ffa), and triglyceride (tg) concentrations in rodent models of type 2 diabetes. the current study was initiated to quantify the effects of masoprocol incubation of adipocytes isolated from normal rats. the results indicate that masoprocol significantly increased glucose uptake ... | 1999 | 10206430 |
| effect of masoprocol on carbohydrate and lipid metabolism in a rat model of type ii diabetes. | extracts of the creosote bush (larrea tridentata, family zygophyllaceae) have long been used as a folk remedy for type ii (non-insulin-dependent) diabetes by native americans in southwestern north america. in this study we have evaluated the metabolic effects of masoprocol, a pure compound isolated from the creosote bush, in a rat model of type ii diabetes. animals were fed a 20% fat (by weight) diet for 2 weeks prior to intravenous injection with streptozotocin (stz, 0.19 mmol/kg). diabetic ani ... | 1999 | 10027587 |
| masoprocol (nordihydroguaiaretic acid): a new antihyperglycemic agent isolated from the creosote bush (larrea tridentata). | an ethnomedically-driven approach was used to evaluate the ability of a pure compound isolated from the creosote bush (larrea tridentata) to lower plasma glucose concentration in two mouse models of type 2 diabetes. the results indicated that plasma glucose concentration fell approximately 8 mmol/l in male c57bl/ks-db/db or c57bl/6j-ob/ob mice following the oral administration of masoprocol (nordihydroguaiaretic acid), a well known lipoxygenase inhibitor. the decline in plasma glucose concentrat ... | 1998 | 9617755 |
| chaparral-associated hepatotoxicity. | personal health care practices that may include the use of dietary supplements are common in the united states. products marketed as dietary supplements are diverse and may include botanicals, vitamins, and/or minerals. chaparral (larrea tridentata) is a botanical dietary supplement made from a desert shrub and used for its antioxidant properties. several reports of chaparral-associated hepatitis have been published since 1990, but a complete picture of the clinical presentation is still unclear ... | 1997 | 9129552 |
| antimicrobial activity of extracts of three major plants from the chihuahuan desert. | dilution methods were employed to determine the effect of ethanolic extracts of agave lecheguilla torr. (agavaceae), baccharis glutinosa pers. (compositae) and larrea tridentata (dc.) cov. (zygophyllaceae) on growth of yeasts, molds and bacteria. the three extracts analyzed showed good antimicrobial activity against more than one organism. the minimal inhibitory concentration of the extracts was also determined. | 1996 | 8771460 |
| isolation of anti-hiv-1 lignans from larrea tridentata by counter-current chromatography. | several lignans, mostly new, were isolated from larrea tridentata by assay-guided counter-current chromatography (ccc). using the secreted alkaline phosphatase bioassay of hiv tat transactivation and the two-phase hexane-ethyl acetate-methanol-water solvent system, two major components (gr and lo) were identified as anti-hiv active principles. the chemical structures of the constituents of gr (g1-g4) and lo (l1-l4) were determined by gc-ms and nmr. after optimization of isolation conditions, a l ... | 1996 | 8581122 |
| [biliary calculi in the golden hamster. xxxvii. the prophylactic action of the creosote bush (larrea tridentata) in pigmented cholelithiasis produced by vitamin a]. | in the present work the results of an experiment performed in the golden hamster (mesocricetus auratus), strain chcm, are presented, in which the possible preventive action of pigment cholelithiasis by a powdered, desiccated, hydroalcoholic extract of leaves of "gobernadora" (larrea tridentata) was studied. the extract was added to the lithogenic diet (basic diet + 25,000 i.u. of vitamin a) at the 4% level; the hamsters were fed with the experimental diets during 70 days. the results showed that ... | 1994 | 8209150 |
| cystic renal cell carcinoma and acquired renal cystic disease associated with consumption of chaparral tea: a case report. | nordihydroguaiaretic acid is an antioxidant used experimentally to induce cystic renal disease in rats. it may be extracted from the leaves of the creosote bush, which are consumed as chaparral tea in the southwestern united states. we report a case of cystic renal disease and cystic adenocarcinoma of the kidney associated with a history of protracted consumption of chaparral tea. | 1994 | 7966683 |
| nordihydroguaiaretic acid-mediated inhibition of ultraviolet b-induced activator protein-1 activation in human keratinocytes. | nordihydroguaiaretic acid (ndga) is a polyphenolic compound from the larrea tridentata bush that has been identified as a chemopreventive drug in animal studies. topically applied ndga has been shown to prevent phorbol ester promotion of tumors in mouse skin, suggesting that ndga may be a candidate drug for the chemoprevention of skin cancer. ultraviolet (uv) b irradiation from sunlight exposure is the major cause of human skin cancer. uvb irradiation causes epigenetic alterations in target kera ... | 2002 | 12112316 |
| synthesis and chiral hplc analysis of the dibenzyltetrahydrofuran lignans, larreatricins, 8'-epi-larreatricins, 3,3'-didemethoxyverrucosins and meso-3,3'-didemethoxynectandrin b in the creosote bush (larrea tridentata): evidence for regiospecific control of coupling. | the creosote bush (larrea tridentata) lignans are linked via 8-8' bonds, with the simplest apparently being e-p-anol derived. of the latter, four of the six theoretically possible diastereoisomers were isolated, namely (-)-larreatricin, (-)-8'-epi-larreatricin, meso-3,3'-didemethoxynectandrin b and the new compounds, (+)- and (-)-3,3'-didemethoxyverrucosins. following synthesis of each in either racemic or meso form, and chiral hplc separation of the antipodes of the racemates, it was establishe ... | 2003 | 12945702 |
| (+)-larreatricin hydroxylase, an enantio-specific polyphenol oxidase from the creosote bush (larrea tridentata). | an enantio-specific polyphenol oxidase (ppo) was purified approximately 1,700-fold to apparent homogeneity from the creosote bush (larrea tridentata), and its encoding gene was cloned. the posttranslationally processed ppo ( approximately 43 kda) has a central role in the biosynthesis of the creosote bush 8-8' linked lignans, whose representatives, such as nordihydroguaiaretic acid and its congeners, have potent antiviral, anticancer, and antioxidant properties. the ppo primarily engenders the e ... | 2003 | 12960376 |
| synthesis and anticancer activity of nordihydroguaiaretic acid (ndga) and analogues. | nordihydroguaiaretic acid (ndga) 1 is a constituent of the creosote bush larrea divaricata and is well known to be a selective inhibitor of lipoxygenases. ndga can also inhibit the platelet derived growth factor receptor and the protein kinase c intracellular signalling family, which both play an important role in proliferation and survival of cancers. moreover, ndga induces apoptosis in tumour xenografts. although it is likely to have several targets of action, ndga is well tolerated in animals ... | 2001 | 12375879 |
| nordihydroguaiaretic acid: hepatotoxicity and detoxification in the mouse. | larrea tridentata (moc & sess) cov. (zygophyllaceae) is an ethnobotanically important plant found in the american southwest and northern mexico. although numerous beneficial effects have been attributed to this plant, several case reports have demonstrated high doses of larrea-containing herbals induce hepatotoxicity and nephrotoxicity in humans. nordihydriguaiaretic acid (ndga) is a lignan found in high amounts (up to 10% by dry weight) in the leaves and twigs of l. tridentata. previously, ndga ... | 2002 | 12457882 |
| biomimetic approaches to tendon repair. | the linear organization of collagen fibers in tendons results in optimal stiffness and strength at low strains under tensile load. however, this organization makes repairing ruptured or lacerated tendons extremely difficult. current suturing techniques to join split ends of tendons, while providing sufficient mechanical strength to prevent gapping, are inadequate to carry normal loads. immobilization protocols necessary to restore tendon congruity result in scar formation at the repair site and ... | 2002 | 12485699 |
| adaptive radiation of gall-inducing insects within a single host-plant species. | speciation of plant-feeding insects is typically associated with host-plant shifts, with subsequent divergent selection and adaptation to the ecological conditions associated with the new plant. however, a few insect groups have apparently undergone speciation while remaining on the same host-plant species, and such radiations may provide novel insights into the causes of adaptive radiation. we used mitochondrial and nuclear dna to infer a phylogeny for 14 species of gall-inducing asphondylia fl ... | 2007 | 17439611 |
| mechanical and thermal properties of novel polymerized ndga-gelatin hydrogels. | nordihydroguaiaretic acid (ndga), an antioxidant with two functional ortho-catechols from the creosote bush, has been shown to increase the mechanical properties of synthetic collagen fibers, producing biologically based, biocompatible fibers with material properties in uniaxial tensile tests to failure that are comparable to those of native tendon (koob and hernandez, biomaterials 23 (2002) 203; koob et al., j biomed mater res, 56 (2001) 31; 56 (2001) 40). the ndga polymerization scheme was app ... | 2003 | 12527270 |
| responses of soil nitrogen dynamics in a mojave desert ecosystem to manipulations in soil carbon and nitrogen availability. | we investigated the effects of changes in soil c and n availability on n mineralization, nitrification, denitrification, nh(3) volatilization, and soil respiration in the mojave desert. results indicate a c limitation to microbial n cycling. soils from underneath the canopies of larrea tridentata (dc.) cov., pleuraphis rigida thurber, and lycium spp. exhibited higher rates of co(2 ) flux, lower rates of nh(3) volatilization, and a decrease in inorganic n (nh(4)(+)-n and no(3)(-)-n) with c additi ... | 2003 | 12647127 |
| a pinoresinol-lariciresinol reductase homologue from the creosote bush (larrea tridentata) catalyzes the efficient in vitro conversion of p-coumaryl/coniferyl alcohol esters into the allylphenols chavicol/eugenol, but not the propenylphenols p-anol/isoeugenol. | the creosote bush (larrea tridentata) accumulates a complex mixture of 8-8' regiospecifically linked lignans, of which the potent antioxidant nordihydroguaiaretic acid (ndga) is the most abundant. its tetra-o-methyl derivative (m4n) is showing considerable promise in the treatment of refractory (hard-to-treat) brain and central nervous system tumors. ndga and related 9,9'-deoxygenated lignans are thought to be formed by dimerization of allyl/propenyl phenols, phenylpropanoid compounds that lack ... | 2007 | 17624297 |
| activity against drug resistant-tuberculosis strains of plants used in mexican traditional medicine to treat tuberculosis and other respiratory diseases. | tuberculosis (tb) kills about 3 million people per year worldwide. furthermore, tb is an infectious disease associated with hiv patients, and there is a rise in multidrug-resistant tb (mdr-tb) cases around the world. there is a need for new anti-tb agents. the study evaluated the antimycobacterial activity of nine plants used in mexican traditional medicine to treat tuberculosis and other respiratory diseases. nasturtium officinale showed the best activity (mic = 100 microg/ml) against the sensi ... | 2008 | 17726732 |
| simplified method for detecting tritium contamination in plants and soil. | cost-effective methods are needed to identify the presence and distribution of tritium near radioactive waste disposal and other contaminated sites. the objectives of this study were to (i) develop a simplified sample preparation method for determining tritium contamination in plants and (ii) determine if plant data could be used as an indicator of soil contamination. the method entailed collection and solar distillation of plant water from foliage, followed by filtration and adsorption of scint ... | 2003 | 12809299 |
| complex responses within a desert bee guild (hymenoptera: apiformes) to urban habitat fragmentation. | urbanization within the tucson basin of arizona during the past 50+ years has fragmented the original desert scrub into patches of different sizes and ages. these remnant patches and the surrounding desert are dominated by larrea tridentata (creosote bush), a long-lived shrub whose flowers are visited by > 120 native bee species across its range. twenty-one of these bee species restrict their pollen foraging to l. tridentata. to evaluate the response of this bee fauna to fragmentation, we compar ... | 2006 | 16711050 |
| prooxidant activity and toxicity of nordihydroguaiaretic acid in clone-9 rat hepatocyte cultures. | nordihydroguaiaretic acid (ndga) is a polyphenol. it is present at high concentrations in the leaves of the evergreen desert shrub, larrea tridentate (creosote bush), which has a long history of medicinal use traditionally by the native americans and mexicans. it is generally believed that the antioxidant properties of ndga are responsible for the medicinal value of this desert shrub. the clone-9 rat hepatocyte cultures were used as an in vitro model to assess the hepatotoxic potential of ndga a ... | 2006 | 16839654 |
| carbon isotope discrimination and foliar nutrient status of larrea tridentata (creosote bush) in contrasting mojave desert soils. | we investigated the relationships between foliar stable carbon isotope discrimination (delta), % foliar n, and predawn water potentials (psi(pd)) and midday stomatal conductance ( g(s)) of larrea tridentata across five mojave desert soils with different age-specific surface and sub-surface horizon development and soil hydrologies. we wished to elucidate how this long-lived evergreen shrub optimizes leaf-level physiological performance across soils with physicochemical characteristics that affect ... | 2004 | 14625769 |
| relationship between the heat tolerance of photosynthesis and the thermal stability of rubisco activase in plants from contrasting thermal environments. | inhibition of net photosynthesis (pn) by moderate heat stress has been attributed to an inability of rubisco activase to maintain rubisco in an active form. to examine this proposal, the temperature response of pn, rubisco activation, chlorophyll fluorescence, and the activities of rubisco and rubisco activase were examined in species from contrasting environments. the temperature optimum of rubisco activation was 10 degrees c higher in the creosote bush (larrea tridentata) compared with the ant ... | 2004 | 15084731 |
| injury and physiological responses of larrea tridentata (dc) coville exposed in situ to sulphur dioxide. | the response of shrubs of larrea tridentata (dec) coville (creosotebush) exposed to sulphur dioxide (so(2)) was evaluated using in situ plants of the majove desert. larrea was exposed to acute levels of 0.3 to 2.0 microl litre(-1) so(2) for periods up to 13 days using field chambers or an open-air fumigation system. plants exposed in the spring exhibited considerable leaf injury (necrosis and defoliation) when exposed to 2.0 microl litre(-1) so(2), and in the autumn had leaf injury when exposed ... | 1987 | 15092685 |
| activity of some mexican medicinal plant extracts on carrageenan-induced rat paw edema. | the extracts obtained from 14 plants of the mexican medicinal flora were assessed for anti-inflammatory activity by carrageenan-induced rat paw edema model. the i.p. administration of the extracts at a dose of 400 mg/kg produced a high reduction of edema with 70% of the plant extracts. oenothera rosea methanol extract, sphaeralcea angustifolia chloroform extract, acaciafarnesiana, larrea tridentata and rubus coriifolius methanol extracts as well as the aqueous extract of chamaedora tepejilote we ... | 2004 | 15330501 |
| antioxidant lignans from larrea tridentata. | three lignans, (7s,8s,7's,8's)-3,3',4'-trihydroxy-4-methoxy-7,7'-epoxylignan, meso-(rel 7s,8s,7'r,8'r)-3,4,3',4'-tetrahydroxy-7,7'-epoxylignan, and (e)-4,4'-dihydroxy-7,7'-dioxolign-8(8')-ene, together with 10 known compounds, were isolated from the leaves of larrea tridentata. the structures of the new compounds were determined primarily from 1d and 2d nmr spectroscopic analysis. their antioxidant activities against intracellular reactive oxygen species were evaluated in hl-60 cells. | 2004 | 15381414 |
| creosote bush (larrea tridentata) resin increases water demands and reduces energy availability in desert woodrats (neotoma lepida). | although many plant secondary compounds are known to have serious consequences for herbivores, the costs of processing them are generally unknown. two potential costs of ingestion and detoxification of secondary compounds are elevation of the minimum drinking water requirement and excretion of energetically expensive metabolites (i.e., glucuronides) in the urine. to address these impacts, we studied the costs of ingestion of resin from creosote bush (larrea tridentata) on desert woodrats (neotom ... | 2004 | 15503528 |
| a wrky gene from creosote bush encodes an activator of the abscisic acid signaling pathway. | the creosote bush (larrea tridentata) is a xerophytic evergreen c3 shrub thriving in vast arid areas of north america. as the first step toward understanding the molecular mechanisms controlling the drought tolerance of this desert plant, we have isolated a dozen genes encoding transcription factors, including ltwrky21 that encodes a protein of 314 amino acid residues. transient expression studies with the gfp-ltwrky21 fusion construct indicate that the ltwrky21 protein is localized in the nucle ... | 2004 | 15504732 |
| cytotoxic and other metabolites of aspergillus inhabiting the rhizosphere of sonoran desert plants. | in a study to discover potential anticancer agents from rhizosphere fungi of sonoran desert plants cytotoxic etoac extracts of four aspergillus strains have been investigated. two new metabolites, terrequinone a (1) and terrefuranone (2), along with na-acetyl aszonalemin (ll-s490beta) (3) were isolated from as. terreus occurring in the rhizosphere of ambrosia ambrosoides, whereas as. terreus inhabiting the rhizosphere of an unidentified brickellia sp. afforded dehydrocurvularin (4), 11-methoxycu ... | 2004 | 15620238 |
| cytotoxic lignans from larrea tridentata. | six lignans, including the cyclolignan 3,4'-dihydroxy-3',4'-dimethoxy-6,7'-cyclolignan, were isolated from the flowering tops of larrea tridentata. additionally the flavanone, (s)-4',5-dihydroxy-7-methoxyflavanone, was isolated for the first time from l. tridentata or any member of the family zygophyllaceae. all of the compounds were assessed for their growth inhibitory activity against human breast cancer, human colon cancer and human melanoma cell lines. the lignans had ic50 values of 5-60 mic ... | 2005 | 15797607 |
| larrea tridentata (creosote bush), an abundant plant of mexican and us-american deserts and its metabolite nordihydroguaiaretic acid. | although controversial, creosote bush, larrea tridentata (sesse and moc. ex dc) coville, is used to treat a variety of illnesses including infertility, rheumatism, arthritis, diabetes, gallbladder and kidney stones, pain and inflammation. recently, it has been used as a nutritional supplement. the primary product extracted from this common plant of the arid regions of northern mexico and southwestern united states is the potent antioxidant nordihydroguaiaretic acid (ndga). it was widely used dur ... | 2005 | 15814253 |
| the anti-apoptotic effects of nordihydroguaiaretic acid: inhibition of cpla(2) activation during tnf-induced apoptosis arises from inhibition of calcium signaling. | nordihydroguaiaretic acid (ndga) is a plant lignan produced by larrea tridentata, the creosote bush of the american southwest. in this report we examine the mechanism underlying the ability of ndga to inhibit tnf-induced apoptosis. our results show that ndga blocks many key indicators of apoptosis. caspase cleavage, mitochondrial inactivation, externalization of phosphatidyl serine, and (51)cr-release were all blocked by low micromolar concentrations of ndga. ndga also inhibited the cpla(2)-depe ... | 2005 | 15950244 |
| effect of larrea tridentata (creosote bush) on cholesterol gallstones and bile secretion in hamsters. | larrea tridentata (sesse and moc. ex dc.) coville is used for the treatment of gallstones in traditional mexican medicine. the possible prevention or elimination of gallstones by ethanolic and aqueous extracts of the leaves and twigs of l. tridentata was tested in hamsters fed a rich carbohydrate, fat-free diet. in addition, the effects of the ethanolic extract and its main metabolite, nordihydroguaiaretic acid, on bile secretion in the perfused liver were tested. in the experiment on prevention ... | 2005 | 16105230 |
| nordihydroguaiaretic acid (ndga) inhibits the igf-1 and c-erbb2/her2/neu receptors and suppresses growth in breast cancer cells. | nordihydroguaiaretic acid (ndga) is a phenolic compound isolated from the creosote bush larrea divaricatta that has anti-cancer activities both in vitro and in vivo. we can now attribute certain of these anti-cancer properties in breast cancer cells to the ability of ndga to directly inhibit the function of two receptor tyrosine kinases (rtks), the insulin-like growth factor receptor (igf-1r) and the c-erbb2/her2/neu (her2/neu) receptor. in mcf-7 human breast cancer cells, low micromolar concent ... | 2005 | 16142439 |
| molecular mechanisms and clinical applications of nordihydroguaiaretic acid (ndga) and its derivatives: an update. | creosote bush, larrea tridentata, is known as chaparral or greasewood in the united states and as gobernadora or hediondilla in mexico. nordihydroguaiaretic acid (ndga), the main metabolite of the creosote bush, has been shown to have promising applications in the treatment of multiple diseases, including cardiovascular diseases, neurological disorders and cancers. creosote bush is a promising agent of north american herbal medicine, and it has extensive pharmacological effects and specific mech ... | 2010 | 20424564 |
| plant secondary metabolites alter the feeding patterns of a mammalian herbivore (neotoma lepida). | mammalian herbivores are predicted to regulate concentrations of ingested plant secondary metabolites (psms) in the blood by modifying the size and frequency of feeding bouts. it is theorized that meal size is limited by a maximum tolerable concentration of psms in the blood, such that meal size is predicted to decrease as psm concentration increases. we investigated the relationship between psm concentration in the diet and feeding patterns in the herbivorous desert woodrat (neotoma lepida) fed ... | 2005 | 16163555 |
| isozymes in larrea divaricata and larrea tridentata (zygophyllaceae): a study of two amphitropical vicariants and autopolyploidy. | electrophoretic variants for seven isozyme systems - probably encoded by 18 structural gene loci - in diploid populations of larrea divaricata and diploid and tetraploid populations of its north american vicariant derivative l. tridentata were assayed by polyacrilamide and starch gel electrophoresis. high molecular similarity of diploid and tetraploid cytotypes of l. tridentata supports the hypothesis of interracial autopolyploidy. the absence of fixed heterozygosity and additive profiles indica ... | 1997 | 16220366 |
| enhanced monsoon precipitation and nitrogen deposition affect leaf traits and photosynthesis differently in spring and summer in the desert shrub larrea tridentata. | leaf-level co2 assimilation (a(area)) can largely be predicted from stomatal conductance (g(s)), leaf morphology (sla) and nitrogen (n) content (n(area)) in species across biomes and functional groups. the effects of simulated global change scenarios, increased summer monsoon rain (+h2o), n deposition (+n) and the combination (+h2o +n), were hypothesized to affect leaf trait-photosynthesis relationships differently in the short- and long-term for the desert shrub larrea tridentata. during the sp ... | 2006 | 16441760 |
| gallic acid and tannase accumulation during fungal solid state culture of a tannin-rich desert plant (larrea tridentata cov.). | larrea tridentata (sesse & mocino ex dc.) coville, also known as larrea, gobernadora, chaparral, or creosote bush, is a shrubby plant which dominates some areas of the desert southwest in the united states and northern mexico and its use has not been exploited and standardized. in this study, gobernadora was studied to evaluate its potential use for support of solid state culture. influence of two minimal media added with gobernadora powder as the sole carbon source and inducer of tannin-degradi ... | 2007 | 16574410 |
| tetra-o-methyl nordihydroguaiaretic acid (terameprocol) inhibits the nf-κb-dependent transcription of tnf-α and mcp-1/ccl2 genes by preventing rela from binding its cognate sites on dna. | abstract: | 2010 | 21138578 |
| a plant lignan, 3'-o-methyl-nordihydroguaiaretic acid, suppresses papillomavirus e6 protein function, stabilizes p53 protein, and induces apoptosis in cervical tumor cells. | persistent infection with oncogenic human papillomaviruses (hpvs) is the most important factor in the induction of uterine cervical cancer, a leading cause of cancer mortality in women worldwide. upon cell transformation, continual expression of the viral oncogenes is required to maintain the transformed phenotype. the viral e6 protein forms a ternary complex with the cellular e6-ap protein and p53 protein which promotes the rapid degradation of p53. recent studies have revealed that lignans fro ... | 2007 | 17393435 |
| nordihydroguaiaretic acid attenuates potassium dichromate-induced oxidative stress and nephrotoxicity. | larrea tridentata also known as creosote bush, larrea, chaparral, greasewood or gobernadora has been used in the folk medicine for the treatment of several illnesses. the primary product that is present at high concentrations in the leaves from this plant is nordihydroguaiaretic acid (ndga) which is a powerful antioxidant. on the other hand, potassium dichromate (k(2)cr(2)o(7))-induced nephrotoxicity is associated with oxidative stress. the aim of this work was to study the effect of ndga on k(2 ... | 2008 | 18155343 |
| shrub invasion decreases diversity and alters community stability in northern chihuahuan desert plant communities. | global climate change is rapidly altering species range distributions and interactions within communities. as ranges expand, invading species change interactions in communities which may reduce stability, a mechanism known to affect biodiversity. in aridland ecosystems worldwide, the range of native shrubs is expanding as they invade and replace native grassland vegetation with significant consequences for biodiversity and ecosystem functioning. | 2008 | 18523686 |
| "pharm-ecology" of diet shifting: biotransformation of plant secondary compounds in creosote (larrea tridentata) by a woodrat herbivore, neotoma lepida. | diet switching in mammalian herbivores may necessitate a change in the biotransformation enzymes used to process plant secondary compounds (pscs). we investigated differences in the biotransformation system in the mammalian herbivore, neotoma lepida, after a radical shift in diet and secondary compound composition. populations of n. lepida in the mojave desert have evolved over the past 10,000 years to feed on creosote (larrea tridentata) from an ancestral state of consuming juniper (juniperus o ... | 2008 | 18752424 |
| terameprocol, a methylated derivative of nordihydroguaiaretic acid, inhibits production of prostaglandins and several key inflammatory cytokines and chemokines. | abstract: | 2009 | 19133137 |
| [larrea tridentata. effect on a non-metabolic model of urolithiasis in rats]. | to evaluate the effect of l. tridentata infusion on the development of urinary calculi in a non-metabolic model. | 2008 | 19241660 |
| the effect of nordihydroguaiaretic acid on iodoacetate-induced toxicity in cultured neurons. | nordihydroguaiaretic acid (ndga) is present in high concentrations in the desert shrub creosote bush, larrea tridentate. this plant has been used in traditional medicine because of its beneficial effects related, at least in part, to its antioxidant properties. taking into account some evidence about neuroprotective effects elicited by ndga, we evaluated the effect of this compound on the neurotoxicity induced by iodoacetate (iaa), an inhibitor of glyceraldehyde-3-phosphate dehydrogenase (gapdh) ... | 2009 | 19367647 |
| the bioactivity of plant extracts against representative bacterial pathogens of the lower respiratory tract. | lower respiratory tract infections are a major cause of illness and death. such infections are common in intensive care units (icu) and their lethality persists despite advances in diagnosis, treatment and prevention. in mexico, some plants are used in traditional medicine to treat respiratory diseases or ailments such as cough, bronchitis, tuberculosis and other infections. medical knowledge derived from traditional societies has motivated searches for new bioactive molecules derived from plant ... | 2009 | 19486533 |
| nordihydroguaiaretic acid inhibits transforming growth factor beta type 1 receptor activity and downstream signaling. | it has been well documented that nordihydroguaiaretic acid (ndga), a phenolic lignan isolated from the creosote bush, larrea tridentate, has anti-cancer activity in vitro and in vivo. several mechanisms have been identified that could contribute to these actions, as ndga directly inhibits metabolic enzymes and receptor tyrosine kinases that are established anti-cancer targets. in the present study, we show that ndga inhibits the transforming growth factor beta (tgf-beta) type i receptor, a serin ... | 2009 | 19540220 |
| fungal cultures of tar bush and creosote bush for production of two phenolic antioxidants (pyrocatechol and gallic acid). | 'tar bush' and 'creosote bush' were substrates of fungal cultivation for tannase production and gallic acid and pyrocatechol accumulation. aspergillus niger gh1 grew similarly on both plant materials under solid state culture conditions, reaching maximal levels after 4 d. fungal strain degraded all tannin content of creosote bush after 4 d of fermentation and >75 % of tar bush after 5 d. higher level of tannase activity was detected in tar bush fermentation. biotransformation of tannins to galli ... | 2009 | 19649735 |
| nordihydroguaiaretic acid from creosote bush (larrea tridentata) mitigates 12-o-tetradecanoylphorbol-13-acetate-induced inflammatory and oxidative stress responses of tumor promotion cascade in mouse skin. | nordihydroguaiaretic acid (ndga) is a phenolic antioxidant found in the leaves and twigs of the evergreen desert shrub, larrea tridentata (sesse and moc. ex dc) coville (creosote bush). it has a long history of traditional medicinal use by the native americans and mexicans. the modulatory effects of topically applied ndga was studied on acute inflammatory and oxidative stress responses in mouse skin induced by stage i tumor promoting agent, 12-o-tetradecanoylphorbol-13-acetate (tpa). double tpa ... | 2009 | 19861506 |
| nordihydroguaiaretic acid analogues: their chemical synthesis and biological activities. | nordihydroguaiaretic acid is a natural occurring lignan mainly isolated and commercially produced from desert plant, creosote bush (larrea divaricata cav. or corillea tridentate), which can be widely found in the border zone of southern of usa and northern of mexico. during past 100 years, extensive research has demonstrated that nordihydroguaiaretic acid and its synthetic analogues are potentially useful in treating diseases related to cancers, diabetes, viral, bacterial infections, and inflamm ... | 2009 | 19903157 |
| combined effects of precipitation and nitrogen deposition on native and invasive winter annual production in california deserts. | primary production in deserts is limited by soil moisture and n availability, and thus is likely to be influenced by both anthropogenic n deposition and precipitation regimes altered as a consequence of climate change. invasive annual grasses are particularly responsive to increases in n and water availabilities, which may result in competition with native forb communities. additionally, conditions favoring increased invasive grass production in arid and semi-arid regions can increase fire risk, ... | 2010 | 19967416 |
| elevated co2 increases plant uptake of organic and inorganic n in the desert shrub larrea tridentata. | resource limitations, such as the availability of soil nitrogen (n), are expected to constrain continued increases in plant productivity under elevated atmospheric carbon dioxide (co(2)). one potential but under-studied n source for supporting increased plant growth under elevated co(2) is soil organic n. in arid ecosystems, there have been no studies examining plant organic n uptake to date. to assess the potential effects of elevated atmospheric co(2) on plant n uptake dynamics, we quantified ... | 2010 | 20094733 |
| mechanism of the oh radical scavenging activity of nordihydroguaiaretic acid: a combined theoretical and experimental study. | the antioxidant nordihydroguaiaretic acid (ndga) is a plant phenolic lignan originally isolated from the creosote bush (larrea tridentata). it has been shown that ndga scavenges efficiently hydroxyl radicals ((*)oh). in the present paper the mechanism by which ndga scavenges (*)oh is addressed performing a combined experimental and theoretical investigation. we found that ndga protects, in a concentration-dependent way, bovine serum albumin and dna from the damage induced by (*)oh generated by t ... | 2010 | 20415502 |
| risk-based determination of critical nitrogen deposition loads for fire spread in southern california deserts. | fire risk in deserts is increased by high production of annual forbs and invasive grasses that create a continuous fine fuel bed in the interspaces between shrubs. interspace production is influenced by water, nitrogen (n) availability, and soil texture, and in some areas n availability is increasing due to anthropogenic n deposition. the daycent model was used to investigate how production of herbaceous annuals changes along gradients of precipitation, n availability, and soil texture, and to d ... | 2010 | 20666252 |
| drought increases freezing tolerance of both leaves and xylem of larrea tridentata. | drought and freezing are both known to limit desert plant distributions, but the interaction of these stressors is poorly understood. drought may increase freezing tolerance in leaves while decreasing it in the xylem, potentially creating a mismatch between water supply and demand. to test this hypothesis, we subjected larrea tridentata juveniles grown in a greenhouse under well-watered or drought conditions to minimum temperatures ranging from -8 to -24 °c. we measured survival, leaf retention, ... | 2011 | 20825578 |
| inhibition of poxvirus growth by terameprocol, a methylated derivative of nordihydroguaiaretic acid. | terameprocol (tmp) is a methylated derivative of nordihydroguaiaretic acid, a phenolic antioxidant originally derived from creosote bush extracts. tmp has previously been shown to have antiviral and anti-inflammatory activities, and has been proven safe in phase i clinical trials conducted to evaluate tmp as both a topical and parenteral therapeutic. in the current study, we examined the ability of tmp to inhibit poxvirus growth in vitro, and found that tmp potently inhibited the growth of both ... | 2010 | 20888364 |
| additional flavonoids from the leaves of larrea tridentata. | | 1981 | 17401826 |
| nordihydroguaiaretic acid inhibits insulin-like growth factor signaling, growth, and survival in human neuroblastoma cells. | neuroblastoma is a common pediatric malignancy that metastasizes to the liver, bone, and other organs. children with metastatic disease have a less than 50% chance of survival with current treatments. insulin-like growth factors (igfs) stimulate neuroblastoma growth, survival, and motility, and are expressed by neuroblastoma cells and the tissues they invade. thus, therapies that disrupt the effects of igfs on neuroblastoma tumorigenesis may slow disease progression. we show that nvp-aew541, a s ... | 2007 | 17486636 |
| effects of crude aqueous medicinal plant extracts on growth and invasion of breast cancer cells. | plants used in folklore medicine continue to be an important source of discovery and development of novel therapeutic agents. in the present study, we determined the effects of crude aqueous extracts of a panel of medicinal plants on the growth and invasion of cancer cells. our results showed that extracts of l. tridentata (creosote bush) and j. communis l. (juniper berry) significantly decreased the growth of mcf-7/az breast cancer cells. the latter as well as a. californica (yerba mansa) inhib ... | 2007 | 17487409 |
| pleistocene wood rat middens and climatic change in mohave desert: a record of juniper woodlands. | leafy twigs and seeds of juniper are abundant in nine ancient neotoma middens discovered in low, arid, desert ranges devoid of junipers, near frenchman flat, nevada. existing vegetation is creosote bush and other desert shrubs. twelve radiocarbon dates suggest that the middens were deposited between 7800 to more than 40,000 years ago. dominance of utah juniper and absence of pinyon pine in most deposits indicates a local pleistocene woodland climate more arid than the usual pinyon-juniper climat ... | 1964 | 17833902 |
| aboveground net primary production dynamics in a northern chihuahuan desert ecosystem. | aboveground net primary production (anpp) dynamics are a key element in the understanding of ecosystem processes. for semiarid environments, the pulse-reserve framework links anpp to variable and unpredictable precipitation events contingent on surficial hydrology, soil moisture dynamics, biodiversity structure, trophic dynamics, and landscape context. consequently, anpp may be decoupled periodically from processes such as decomposition and may be subjected to complex feedbacks and thresholds at ... | 2008 | 17968592 |
| transitory effects of elevated atmospheric co2 on fine root dynamics in an arid ecosystem do not increase long-term soil carbon input from fine root litter. | experimental increases in atmospheric co2 often increase root production over time, potentially increasing soil carbon (c) sequestration. effects of elevated atmospheric co2 on fine root dynamics in a mojave desert ecosystem were examined for the last 4.5 yr of a long-term (10-yr) free air co2 enrichment (face) study at the nevada desert face facility (ndff). sets of minirhizotron tubes were installed at the beginning of the ndff experiment to characterize rooting dynamics of the dominant shrub ... | 2011 | 21355868 |
| maintenance of c sinks sustains enhanced c assimilation during long-term exposure to elevated [co(2)] in mojave desert shrubs. | during the first few years of elevated atmospheric [co(2)] treatment at the nevada desert face facility, photosynthetic downregulation was observed in desert shrubs grown under elevated [co(2)], especially under relatively wet environmental conditions. nonetheless, those plants maintained increased a (sat) (photosynthetic performance at saturating light and treatment [co(2)]) under wet conditions, but to a much lesser extent under dry conditions. to determine if plants continued to downregulate ... | 2011 | 21516309 |
| an endophytic/pathogenic phoma sp. from creosote bush producing biologically active volatile compounds having fuel potential. | a phoma sp. was isolated and characterized as endophytic and as a pathogen of larrea tridentata (creosote bush) growing in the desert region of southern utah, usa. this fungus produces a unique mixture of volatile organic compounds (vocs), including a series of sesquiterpenoids, some alcohols and several reduced naphthalene derivatives. trans-caryophyllene, a product in the fungal vocs, was also noted in the vocs of this pungent plant. the gases of phoma sp. possess antifungal properties and is ... | 2011 | 21535100 |
| 2,2'-dimethoxy-4,4'-[rel-(2r,3s)-2,3-di-methylbutane-1,4-diyl]diphenol. | the title mol-ecule, c(20)h(26)o(4), commonly known as meso-dihydro-guaiaretic acid, is a naturally occurring lignan extracted from larrea tridentata and other plants. the mol-ecule has a noncrystallographic inversion center situated at the midpoint of the central c-c bond, generating the meso stereoisomer. the central c-c-c-c alkyl chain displays an all-trans conformation, allowing an almost parallel arrangement of the benzene rings, which make a dihedral angle of 5.0 (3)°. both hydr-oxy groups ... | 2009 | 21583141 |
| a comparison of the anti-staphylococcus aureus activity of extracts from commonly used medicinal plants. | resurgences of staphylococcus aureus infection continue globally, with antibiotic resistance increasing dramatically, making these infections more difficult to treat. s. aureus epidemics impose public health threats, and economic burdens on health care costs worldwide, presenting challenges modern medicine struggles to control. | 2014 | 24635487 |
| ecosystem response to nutrient enrichment across an urban airshed in the sonoran desert. | rates of nitrogen (n) deposition have increased in arid and semiarid ecosystems, but few studies have examined the impacts of long-term n enrichment on ecological processes in deserts. we conducted a multiyear, nutrient-addition study within 15 sonoran desert sites across the rapidly growing metropolitan area of phoenix, arizona (usa). we hypothesized that desert plants and soils would be sensitive to n enrichment, but that these effects would vary among functional groups that differ in terms of ... | 2011 | 21639034 |
| plutonium uptake and behavior in vegetation of the desert southwest: a preliminary assessment. | eight species of desert vegetation and associated soils were collected from the nevada national security site (n2s2) and analyzed for 238pu and 239 + 240pu concentrations. amongst the plant species sampled were: atmospheric elemental accumulators (moss and lichen), the very slow growing, long-lived creosote bush and the rapidly growing, short-lived cheatgrass brome. the diversity of growth strategies provided insight into the geochemical behavior and bio-availability of pu at the n2s2. the highe ... | 2011 | 21796316 |
| effects of elevated atmospheric co(2) on rhizosphere soil microbial communities in a mojave desert ecosystem. | the effects of elevated atmospheric carbon dioxide [co(2)] on microbial communities in arid rhizosphere soils beneath larrea tridentata were examined. roots of larrea were harvested from plots fumigated with elevated or ambient levels of [co(2)] using free-air co(2) enrichment (face) technology. twelve bacterial and fungal rrna gene libraries were constructed, sequenced and categorized into operational taxonomical units (otus). there was a significant decrease in otus within the firmicutes (bact ... | 2011 | 21779135 |
| genetic diversity in chihuahuan desert populations of creosotebush (zygophyllaceae: larrea tridentata). | we examined isozyme variation in the dominant chihuahuan desert shrub, larrea tridentata (creosotebush), to determine the genetic variation within and among populations, the biogeographic relationships of populations, and the potential inbreeding in the species. we surveyed 17 populations consisting of 20 to 50 individuals per population along a 1600-km north-south transect across the chihuahuan desert. the southernmost population was near villa hidalgo, mexico, and the northernmost near isleta ... | 2005 | 21652451 |
| the vulnerability to freezing-induced xylem cavitation of larrea tridentata (zygophyllaceae) in the chihuahuan desert. | the temperature dependence of freezing-induced xylem cavitation was studied in a chihuahuan desert population of larrea tridentata (zygophyllaceae). field measurements of wood temperature and xylem embolism were combined with anatomical studies and laboratory measurements of embolism in stem and root samples frozen under controlled conditions. our laboratory experiments corroborated the previously observed relationship between minimum freezing temperature and embolism. the area of the low-temper ... | 2002 | 21665620 |
| recruitment potential of two perennial grasses with different growth forms at a semiarid-arid transition zone. | the objective of this study was to quantify differences in recruitment potential (seed production, seed presence in the soil) for two congeneric perennial grasses (bouteloua gracilis, bouteloua eriopoda [poaceae]) that dominate adjacent arid and semiarid grassland biomes. it was hypothesized that these species have different recruitment strategies at the biome transition zone that are related to differences in their growth form and longevity. recruitment potential for each bouteloua species was ... | 2002 | 21665589 |
| Testing the diet-breadth trade-off hypothesis: differential regulation of novel plant secondary compounds by a specialist and a generalist herbivore. | Specialist herbivores are predicted to have evolved biotransformation pathways that can process large doses of secondary compounds from the plant species on which they specialize. It is hypothesized that this physiological specialization results in a trade-off such that specialists may be limited in ability to ingest novel plant secondary compounds (PSCs). In contrast, the generalist foraging strategy requires that herbivores alternate consumption of plant species and PSC types to reduce the pos ... | 2011 | 21927911 |
| larrealignans a and b, novel lignan glycosides from the aerial parts of larrea tridentata. | two new lignan glycosides, named larrealignans a (1) and b (2), and a known lignan (3) were isolated from the aerial parts of larrea tridentata (zygophyllaceae). the structures of 1 and 2 were determined on the basis of spectroscopic analysis and the results of hydrolytic cleavage. the isolated compounds (1-3) and aglycones (1a, 2a) of 1 and 2 were evaluated for their cytotoxic activities against hl-60 human leukemia cells. | 2011 | 22130367 |
| Responses of soil cellulolytic fungal communities to elevated atmospheric CO2 are complex and variable across five ecosystems. | Elevated atmospheric CO(2) generally increases plant productivity and subsequently increases the availability of cellulose in soil to microbial decomposers. As key cellulose degraders, soil fungi are likely to be one of the most impacted and responsive microbial groups to elevated atmospheric CO(2). To investigate the impacts of ecosystem type and elevated atmospheric CO(2) on cellulolytic fungal communities, we sequenced 10,677 cbhI gene fragments encoding the catalytic subunit of cellobiohydro ... | 2011 | 21883796 |