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At least 577 records · Page 32Linked to original sources
PubMed2001

Underutilised legumes: potential sources for low-cost protein.

Seeds of 104 leguminous species belonging to 17 genera were analysed for their protein contents. The promising ones were investigated for fibre, carbohydrate, ash, oil, fatty acids, amino acid profile and trypsin inhibitor activity (TIA). The variation of fibre contents was 4.1-8.9%, carbohydrate 18.4-49.2%, ash 1.8-7.2%, TIA 48.7-87.5 mg/g, oil 1.3-19.8% and protein 11.0-51.6%. The protein content (41-45%) in Acacia mellifera (41.6%), Albizzia lebbek (43.6%), Bauhinia triandra (42.7%), Lathyrus odoratus (42.8%), Parkinsonia aculeata (41.6%), Psophocarpus tetragonolobus (41.9%), Sesbania paludosa (41.2%) and S. sesban (43.8%) was in close proximity to soybean (42.8%), whereas Bauhinia retusa (51.6%), B. variegata (46.5%), Delonix elata (48.7%) and Gliricidia maculata (46.3%) showed higher percentages of protein than soybean. The essential amino acid composition of some of the seed proteins was reasonably well balanced (lysine up to 7.6%). The seeds of Bauhinia retusa (18.6%), B. triandra (16.5%), B. variegata (17.3%), Gliricidia maculata (16.2%), Parkia biglandulosa (18.9%) and Psophocarpus tetragonolobus (19.8%) had a good amount of oil, comparable to soybean (18-22%). The fatty acid composition of some genera/species was quite promising with high amount of unsaturated fatty acids.

Amino Acids↗
PubMed2005

Beta-orcinol depsidones from the lichen Usnea sp. from Sri Lanka.

Two beta-orcinol depsidone lactones, the methyl ethers of menegazziaic acid and stictic acid were isolated along with glyceryl trilinolate and usnic acid from an Usnea sp. new to Sri Lanka growing on rotting trees of Acacia decurrans. Usnic acid exhibited potent antitermite activity against a common pest of tea, Glyptotermes dilatatus, at low elevations.

Animals↗
PubMed2000

Optimization and development of a core-in-cup tablet for modulated release of theophylline in simulated gastrointestinal fluids.

A triple-layer core-in-cup tablet that can release theophylline in simulated gastrointestinal (GI) fluids at three distinct rates has been developed. The first layer is an immediate-release layer; the second layer is a sustained-release layer; and the last layer is a boost layer, which was designed to coincide with a higher nocturnal dose of theophylline. The study consisted of two stages. The first stage optimized the sustained-release layer of the tablet to release theophylline over a period of 12 hr. Results from this stage indicated that 30% w/w acacia gum was the best polymer and concentration to use when compressed to a hardness of 50 N/m2. The second stage of the study involved the investigation of the final triple-layer core-in-cup tablet to release theophylline at three different rates in simulated GI fluids. The triple-layer modulated core-in-cup tablet successfully released drug in simulated fluids at an initial rate of 40 mg/min, followed by a rate of 0.4085 mg/min, in simulated gastric fluid TS, 0.1860 mg/min in simulated intestinal fluid TS, and finally by a boosted rate of 0.6952 mg/min.

Analysis of Variance↗
PubMed1951

Mechanisms involved in fibrin formation.

That the role of thrombin in the conversion of fibrinogen to fibrin is essentially enzymatic, is established not only by the minute amounts of thrombin which are effective but also by the complete independence of fibrin yields and thrombin concentrations over a very wide range of thrombin dilutions and clotting times. The thrombin-fibrinogen reaction, in the phase beyond the "latent period" at least, seems fundamentally "first order." Technical requirements of the experiments leading to these conclusions include: (1) a highly purified (e.g. 97 per cent "clottable") fibrinogen, (2) absence of traces of thrombic impurities in the fibrinogen, (3) absence of fibrinolytic protease contaminant of the thrombin and the fibrinogen, and (4) sufficient stability of the thrombin even at very high dilutions. Four conditions affecting thrombin stability have been investigated. Fibrin yields are not significantly modified by numerous experimental circumstances that influence the clotting time, such as (1) temperature, (2) pH, (3) non-specific salt action due to electrical (ionic) charges, which alter the Coulomb forces involved in the fibrillar aggregation, (4) specific ion effects, whether clot-accelerating (e.g. Ca(++)) or clot-inhibitory (e.g. Fe(CN)(6)''''), (5) occluding (adsorptive) colloids, which have a "fibrinoplastic" action, e.g. (a) acacia and probably (b) fibrinogen which has been mildly "denatured" by salt-heating, acidification, etc. The data with which several European workers have attempted to substantiate the idea of a two-stage thrombin-fibrinogen reaction with an intermediary "profibrin" (allegedly partly "denatured") have been reanalyzed with controls which lead us to very different conclusions, viz. (1) denaturation and fibrin formation are independent; (2) partial denaturation is "fibrinoplastic" (see above); and (3) conditions of strong salinity and acid pH (5.1) usually do not completely prevent the thrombin-fibrinogen reaction but merely prolong the "latent" phase and lessen the time required for completion of essentially the same reaction (fibrin polymerization) when more favorable clotting conditions are restored. Thus, our experiments advance the modern concepts concerning the coagulation mechanisms along lines that, for the most part, agree with those of the Harvard physical chemists, and we oppose the European views concerning a two-stage reaction, "profibrin," and "the denaturase theory" of clotting.

Blood Coagulation↗
PubMed2004

Effects of D-003 on hepatic drug-metabolizing enzyme activities in rats.

D-003 is a mixture of very-long-chain aliphatic acids with cholesterol-lowering and concomitant anti-platelet effects. The microsomal cytochrome P-450 system comprises a superfamily of proteins present in hepatic and extrahepatic tissues that is responsible for the metabolism of many drugs. The present study was undertaken to investigate the effects of D-003 on in vivo drug-metabolizing hepatic enzymes. Two experimental series (n = 6 animals/group) were performed. In the first series rats were randomly distributed in one control and two groups treated with D-003 at 1,000 and 2,000 mg/kg for 14 days. In the second one they were distributed in one control and three groups treated with D-003 (250, 500, and 1,000 mg/kg) for 6 months. All treatments were orally administered by gastric gavage. Control rats were orally treated only with acacia gum/water vehicle. The content of microsomal P-450, b (5) cytochromes, total sulfhydryl groups, nonprotein sulfhydryl groups, and protein-bound sulfhydryl groups as well as the activities of NADPH cytochrome c reductase, aminopyrine demethylase, dimethylnitrosamine N-demethylase, 7-ethoxyresorufin O-deethylation, 7-pentoxyresorufin O-depentylation, and cytosolic glutathione S-transferase were assessed. D-003 administered up to 2,000 mg/kg or 1,000 mg/kg during 14 days or 6 months did not affect the activities of the hepatic drug-metabolizing enzymes investigated. It is concluded that D-003 is not metabolized by the liver cytochrome system and that potential risk derived from drug-to-drug interactions between D-003 and concomitant drugs appears to be low.

Administration, Oral↗
PubMedDate not supplied

Rabies in the kudu antelope (Tragelaphus strepsiceros).

An epizootic of rabies in the greater kudu (Tragelaphus strepsiceros) occurred in Namibia during 1977-1983. The virus strain involved in the epizootic proved to be identical to rabies strains found in infected dogs in many African countries. Such a sudden and large outbreak of rabies could not be explained on the basis of the etiologic agent. A thorough investigation into kudu characteristics revealed that the kudu population had increased disproportionally before the epizootic in response to favorable conditions. The social behavior of the kudu, i.e., group browsing on acacia trees, whose thorns cause lesions in the kudu's oral cavity, as well as the excretion of relatively high titers of virus in the saliva of infected animals provide suitable conditions for transmission in the kudu population after initial infection through the jackal or other species. These factors offer an explanation for this epizootic.

Animals↗
PubMed1988

Hepatic responses to edible gums during refeeding of starved rats.

The ability of edible gums to depress total liver lipids and activities of two hepatic enzymes (glucose-6-phosphate dehydrogenase and NADP-linked malic enzyme) was examined during the refeeding of 2 d starved rats. Gums were fed as 4% of dry ingredients, occasionally with added water, in otherwise identical high glucose, nutritionally adequate diets. Feeding of xantham gum for 1 or 2 d decreased the rise in two enzyme activities and in total liver lipids, but after 4 or 7 d only total liver lipids were affected. Agar, which is insoluble at room temperature, was effective only when incorporated in the diet as a stiff gel. Guar, carrageenan, karaya and pectin reduced the change in at least one hepatic parameter, but acacia and gum ghatti, which impart little viscosity to water, were without effect. The ability of seven gums to form semisolid gels at low concentrations was measured and appeared to be associated with the variable effectiveness of those gums in influencing lipid contents and enzyme activities of the liver.

Animals↗
PubMed1994

The effect of environmentally induced stem temperature gradients on transpiration estimates from the heat balance method in two tropical woody species.

Commercially available sap flow gauges were used to evaluate the performance of the stem heat balance (SHB) technique for measuring sap flow in coffee (Coffea arabica L. cv. Yellow Catuai) and koa (Acacia koa Gray) plants under greenhouse and field conditions. Transpiration rates measured gravimetrically and with the SHB technique were similar in greenhouse tests, provided that insulation in addition to that supplied by the gauge manufacturer was applied to reduce radiant heating in the vicinity of the sap flow gauges. Unrealistic estimates of transpiration rates were sometimes obtained under both field and greenhouse conditions as a result of negative stem temperature differentials from below to above the gauge heater, even in the absence of power applied to the heaters. It was possible to correct this environmentally induced bias by means of additional stem insulation that minimized the rate of change in stem temperature, or by applying simple corrections using the DeltaT values for unheated gauges operated as blanks. In the field, where dense canopies reduced the radiant energy load on stems, temperature corrections were unnecessary, because DeltaT values in unheated gauges were near zero.

Journal Article↗
PubMed1999

Can differences in root responses to soil drying and compaction explain differences in performance of trees growing on landfill sites?

Two tropical woody species, Acacia confusa Merrill and Litsea glutinosa (Lour.) C.B. Robinson, were grown under controlled conditions in PVC pipes filled with John Innes No. 2 soil. To investigate root distribution, physiological characteristics and hydraulic conductivity, four soil treatments were imposed-well-watered and noncompacted (control), well-watered and compacted; unwatered and noncompacted, and unwatered and compacted. In L. glutinosa, rooting depth and root elongation were severely restricted when soil bulk density increased from around 1.12 to 1.62 g cm(-3), whereas soil compaction had little effect on these parameters in A. confusa. As soil drying progressed, root water potential and osmotic potential declined more slowly in L. glutinosa than in A. confusa. Both the soil drying and compaction treatments significantly stimulated the accumulation of root abscisic acid (ABA) in both species. Soil drying damaged the root cell membrane of A. confusa, but had little influence on the root cell membrane of L. glutinosa. Soil drying had a greater effect on root hydraulic conductivity (L(p)) in L. glutinosa than in A. confusa, whereas the effect of soil compaction on L(p) was less in L. glutinosa than in A. confusa. Soil drying enhanced the effects of soil compaction on root L(p). We conclude that soil drying and compaction have large species-specific effects on the distribution, growth and physiology of roots. The relationships of these root properties to the species' ability to tolerate unfavorable soil conditions were examined.

Journal Article↗
PubMed2006

Citrate-release-mediated aluminum resistance is coupled to the inducible expression of mitochondrial citrate synthase gene in Paraserianthes falcataria.

Aluminum (Al) resistance in some leguminous plants is achieved by enhanced citrate release from roots. Enhancement requires several hours for complete activation and is postulated to involve Al-responsive genes or components. We examined the mechanism of Al-induced citrate release by studying the relationship between citrate release and expression of the mitochondrial citrate synthase (mCS) gene in three leguminous trees. Root elongation in Leucaena leucocephala (Lam.) de Wit was arrested within 24 h by 30 microM Al, whereas root elongation in Paraserianthes falcataria (L.) Neilson and Acacia mangium Willd. was inhibited < 50% by a 48-h treatment with 100 microM Al in calcium chloride solution. Roots of P. falcataria and A. mangium maintained enhanced release and accumulation of citrate for at least 28 days in response to Al treatment. Aluminum increased the accumulation of mCS transcripts in P. falcataria roots, but not in L. leucocephala roots, and thus up-regulation decreased following removal of Al. Lanthanum did not alter the expression level of mCS. Aluminum increased mCS activity concomitantly with enhanced mCS gene expression in P. falcataria, whereas it did not affect mCS activity in L. leucocephala. Aluminum content in root apices of P. falcataria was increased by cycloheximide, supporting the idea that de novo synthesis of proteins is a prerequisite for Al resistance. Our findings suggest that Al-inducible expression of mCS coupled with enhanced citrate release mediates Al resistance in P. falcataria.

Aluminum↗
PubMed1999

Rhizobium sp. strain NGR234 and R. fredii USDA257 share exceptionally broad, nested host ranges.

Genetically, Rhizobium sp. strain NGR234 and R. fredii USDA257 are closely related. Small differences in their nodulation genes result in NGR234 secreting larger amounts of more diverse lipo-oligosaccharidic Nod factors than USDA257. What effects these differences have on nodulation were analyzed by inoculating 452 species of legumes, representing all three subfamilies of the Leguminosae, as well as the nonlegume Parasponia andersonii, with both strains. The two bacteria nodulated P. andersonii, induced ineffective outgrowths on Delonix regia, and nodulated Chamaecrista fasciculata, a member of the only nodulating genus of the Caesalpinieae tested. Both strains nodulated a range of mimosoid legumes, especially the Australian species of Acacia, and the tribe Ingeae. Highest compatibilities were found with the papilionoid tribes Phaseoleae and Desmodieae. On Vigna spp. (Phaseoleae), both bacteria formed more effective symbioses than rhizobia of the "cowpea" (V. unguiculata) miscellany. USDA257 nodulated an exact subset (79 genera) of the NGR234 hosts (112 genera). If only one of the bacteria formed effective, nitrogen-fixing nodules it was usually NGR234. The only exceptions were with Apios americana, Glycine max, and G. soja. Few correlations can be drawn between Nod-factor substituents and the ability to nodulate specific legumes. Relationships between the ability to nodulate and the origin of the host were not apparent. As both P. andersonii and NGR234 originate from Indonesia/Malaysia/Papua New Guinea, and NGR234's preferred hosts (Desmodiinae/Phaseoleae) are largely Asian, we suggest that broad host range originated in Southeast Asia and spread outward.

Carbohydrate Sequence↗
PubMed2004

Radiation of the Australian flora: what can comparisons of molecular phylogenies across multiple taxa tell us about the evolution of diversity in present-day communities?

The Australian fossil record shows that from ca. 25 Myr ago, the aseasonal-wet biome (rainforest and wet heath) gave way to the unique Australian sclerophyll biomes dominated by eucalypts, acacias and casuarinas. This transition coincided with tectonic isolation of Australia, leading to cooler, drier, more seasonal climates. From 3 Myr ago, aridification caused rapid opening of the central Australian arid zone. Molecular phylogenies with dated nodes have provided new perspectives on how these events could have affected the evolution of the Australian flora. During the Mid-Cenozoic (25-10 Myr ago) period of climatic change, there were rapid radiations in sclerophyll taxa, such as Banksia, eucalypts, pea-flowered legumes and Allocasuarina. At the same time, taxa restricted to the aseasonal-wet biome (Nothofagus, Podocarpaceae and Araucariaceae) did not radiate or were depleted by extinction. During the Pliocene aridification, two Eremean biome taxa (Lepidium and Chenopodiaceae) radiated rapidly after dispersing into Australia from overseas. It is clear that the biomes have different histories. Lineages in the aseasonal-wet biome are species poor, with sister taxa that are species rich, either outside Australia or in the sclerophyll biomes. In conjunction with the fossil record, this indicates depletion of the Australian aseasonal-wet biome from the Mid-Cenozoic. In the sclerophyll biomes, there have been multiple exchanges between the southwest and southeast, rather than single large endemic radiations after a vicariance event. There is need for rigorous molecular phylogenetic studies so that additional questions can be addressed, such as how interactions between biomes may have driven the speciation process during radiations. New studies should include the hitherto neglected monsoonal tropics.

Australia↗
PubMed2004

Palaeobotanical studies from tropical Africa: relevance to the evolution of forest, woodland and savannah biomes.

Fossil plants provide data on climate, community composition and structure, all of which are relevant to the definition and recognition of biomes. Macrofossils reflect local vegetation, whereas pollen assemblages sample a larger area. The earliest solid evidence for angiosperm tropical rainforest in Africa is based primarily on Late Eocene to Late Oligocene (ca. 39-26 Myr ago) pollen assemblages from Cameroon, which are rich in forest families. Plant macrofossil assemblages from elsewhere in interior Africa for this time interval are rare, but new work at Chilga in the northwestern Ethiopian Highlands documents forest communities at 28 Myr ago. Initial results indicate botanical affinities with lowland West African forest. The earliest known woodland community in tropical Africa is dated at 46 Myr ago in northern Tanzania, as documented by leaves and fruits from lake deposits. The community around the lake was dominated by caesalpinioid legumes, but included Acacia, for which this, to my knowledge, is the earliest record. This community is structurally similar to modern miombo, although it is different at the generic level. The grass-dominated savannah biome began to expand in the Middle Miocene (16 Myr ago), and became widespread in the Late Miocene (ca. 8 Myr ago), as documented by pollen and carbon isotopes from both West and East Africa.

Africa↗
PubMed2001

Effect of hydrolysable and condensed tannins on growth, morphology and metabolism of Streptococcus gallolyticus (S. caprinus) and Streptococcus bovis.

Streptococcus gallolyticus (S. caprinus) was resistant in vitro to at least 7% (w/v) tannic acid and 4% (w/v) acacia condensed tannin, levels 10-fold greater than those tolerated by S. bovis. Growth of S. gallolyticus in liquid medium was characterized by a lag period which increased, and a growth rate which decreased, with increasing tannin concentration. S. gallolyticus was also more tolerant to the presence of simple phenolic acid monomers than was S. bovis, but the lag period was still concentration dependent. Gallate decarboxylase activity in S. gallolyticus was elevated in the presence of tannic acid or gallic acid but not with other phenolic acids. Scanning electron microscopic analysis showed that both the size and shape of S. gallolyticus and S. bovis changed in response to tannin but only S. gallolyticus was surrounded by an extracellular polysaccharide matrix which accumulated in a tannin-concentration-dependent fashion. Washing of the cells to remove extracellular polysaccharide increased the lag period of S. gallolyticus in the presence of 1% (w/v) tannic acid from 4 h to 6 h. In contrast, increasing extracellular polysaccharide synthesis in S. bovis did not increase its tolerance to tannic acid. These data demonstrate that S. gallolyticus has developed a number of mechanisms to reduce the potential effect of tannins on cell growth, and that these mechanisms provide the organism with a selective advantage over S. bovis when grown in the presence of tannins.

Carboxy-Lyases↗
PubMed1969

Effects of picloram and ethylene on leaf movement in huisache and mesquite seedlings.

Application of 4-amino-3,5,6-trichloropicolinic acid (picloram) to roots stimulated the production of ethylene in both mesquite [Prosopis juliflora (Swartz) DC. var. glandulosa (Torr.) Cockerell] and huisache [Acacia farnesiana (L.) Willd.] seedlings. Herbicide levels rose in tissues before we detected increased ethylene production. Rates of ethylene production by various parts of the plant paralleled herbicide concentrations. In both species, picloram caused loss of leaf movement and epinastic curvature of leaves and stems. Only huisache was defoliated by picloram. Rates of ethylene production increased before we observed any leaf movement or defoliation responses. Fumigation of plants with levels of ethylene, calculated to approximate those in herbicide-treated plants at the initial loss of leaf movement, caused the same symptoms as picloram treatment. The time sequence of ethylene fumigation and loss of the ability for leaf movement is compatible with the hypothesis that there is a causal relationship between picloram and ethylene production and loss of leaf movement.

Journal Article↗
PubMed1970

Involvement of Ethylene in Picloram-induced Leaf Movement Response.

The relationship of root-applied 4-amino-3,5,6-trichloropicolinic acid (picloram) to ethylene production and the leaf movement response in honey mesquite (Prosopis juliflora [Swartz] DC. var. glandulosa [Torr.] Cockerell) and huisache (Acacia farnesiana [L.] Willd.) was studied in detail. The threshold and saturation levels of exogenous ethylene and root-applied picloram necessary to inhibit leaf movement were determined. Internal levels of ethylene in excess of those necessary to saturate the leaf movement inhibition response occurred in tops of treated plants before and after symptom expression. These internal levels of ethylene, while averages for the entire plant tops, probably occur at the specific site of action and thus account for the action of picloram in inhibition of leaf movement and related responses. Quantitative differences in the leaf movement response of both species to picloram and ethylene were observed. In huisache alone, a very small change in ethylene levels was necessary to produce a major blockage of the leaf movement response, suggesting that the gas may have a natural function in that species.

Journal Article↗
PubMed1991

Gum arabic glycoprotein is a twisted hairy rope : a new model based on o-galactosylhydroxyproline as the polysaccharide attachment site.

Separation of the wound exudate from Acacia senegal (L.) Willd., "gum arabic," on a preparative Superose-6 column gave two major fractions: a high molecular weight gum arabic glycoprotein (GAGP) containing about 90% carbohydrate and a lower molecular weight heterogenous gum arabic polysaccharide fraction. Hydrogen fluoride-deglycosylation of GAGP gave a large ( approximately 400 residue) hydroxyproline-rich polypeptide backbone (dGAGP). Alkaline hydrolysis of GAGP showed that most of the carbohydrate was attached to the polypeptide backbone as small ( approximately 30 residue) hydroxyproline (Hyp)-polysaccharide substituents. After partial acid hydrolysis of the Hyp-polysaccharide fraction we identified O-galactosylhydroxyproline as the glycopeptide linkage, identical with that of hydroxyproline-rich arabinogalactan-proteins (AGPs). However, unlike the acidic alanine-rich AGPs, GAGP is basic and notably deficient in alanine. Thus, while the GAGP polypeptide backbone more closely resembles that of the Hyp-rich cell wall protein extensin, the GAGP polysaccharide sidechains resemble AGPs. Possibly all three proteins comprise a phylogenetically related extensin superfamily of extended rod-like macromolecules. The "wattle-blossom" model for AGP and gum arabic predicts a few large polysaccharide substituents along the polypeptide backbone of a spheroidal macromolecule. On the contrary, our data imply a rodlike molecule with numerous small polysaccharide substituents (attached to 24% of the Hyp residues), regularly arranged along a highly periodic polypeptide backbone based, hypothetically, on a 10 to 12 residue repetitive peptide motif. Thus, a simple statistical model of the gum arabic glycoprotein predicts a repeating polysaccharide-peptide subunit of about 7 kilodaltons. The small polysaccharide substituents will maximize intramolecular hydrogen bonding if aligned along the long axis of the molecule, forming in effect a twisted hairy rope. Electron micrographs of rotary shadowed GAGP molecules support that prediction and may also explain how such apparently large molecules can exit the cell by endwise reptation through the small pores of the primary cell wall.

Journal Article↗
PubMed2003

Evolutionary ecology of egg size and number in a seed beetle: genetic trade-off differs between environments.

In many organisms, large offspring have improved fitness over small offspring, and thus their size is under strong selection. However, due to a trade-off between offspring size and number, females producing larger offspring necessarily must produce fewer unless the total amount of reproductive effort is unlimited. Because differential gene expression among environments may affect genetic covariances among traits, it is important to consider environmental effects on the genetic relationships among traits. We compared the genetic relationships among egg size, lifetime fecundity, and female adult body mass (a trait linked to reproductive effort) in the seed beetle, Stator limbatus, between two environments (host-plant species Acacia greggii and Cercidium floridum). Genetic correlations among these traits were estimated through half-sib analysis, followed with artificial selection on egg size to observe the correlated responses of lifetime fecundity and female body mass. We found that the magnitude of the genetic trade-off between egg size and lifetime fecundity differed between environments--a strong trade-off was estimated when females laid eggs on C. floridum seeds, yet this trade-off was weak when females laid eggs on A. greggii seeds. Also differing between environments was the genetic correlation between egg size and female body mass-these traits were positively genetically correlated for egg size on A. greggii seeds, yet uncorrelated on C. floridum seeds. On A. greggii seeds, the evolution of egg size and traits linked to reproductive effort (such as female body mass) are not independent from each other as commonly assumed in life-history theory.

Analysis of Variance↗