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At least 469 records · Page 26Linked to original sources
PubMed1999

Stomatal behavior of four woody species in relation to leaf-specific hydraulic conductance and threshold water potential.

Midday stomatal closure is mediated by the availability of water in the soil, leaf and atmosphere, but the response to these environmental and internal variables is highly species specific. We tested the hypothesis that species differences in stomatal response to humidity and soil water availability can be explained by two parameters: leaf-specific hydraulic conductance (K(L)) and a threshold leaf water potential (Psi(threshold)). We used a combination of original and published data to estimate characteristic values of K(L) and Psi(threshold) for four common tree species that have distinctly different stomatal behaviors: black cottonwood (Populus trichocarpa Torr. & Gray.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), red alder (Alnus rubra Bong.) and western hemlock (Tsuga heterophylla (Raf.) Sarg.). We used the values to parameterize a simple, nonelastic model that predicts stomatal conductance by linking hydraulic flux to transpirational flux and maintaining Psi(leaf) above Psi(threshold). The model successfully predicted fundamental features of stomatal behavior that have been reported in the literature for these species. We conclude that much of the variation among the species in stomatal response to soil and atmospheric water deficits can be explained by K(L) and Psi(threshold). The relationship between Psi(threshold) and xylem vulnerability to cavitation differed among these species.

Journal Article↗
PubMed2002

Arsenic, Sb and Bi contamination of soils, plants, waters and sediments in the vicinity of the Dalsung Cu-W mine in Korea.

The objective of this study is to investigate environmental contamination derived from metalliferous mining activities. In the study area, the Dalsung Cu-W mine, soils, various crop plants, stream waters, sediments and particulates were sampled in and around the mine and analyzed for As, Sb and Bi by ICP-AES with a hydride generator. In addition, soil pH, cation exchange capacity, loss-on-ignition and soil texture were also measured. Concentrations of As, Sb and Bi in surface soils sampled in the mine dump sites averaged 2500, 54 and 436 microg g(-1), respectively. Relatively lower concentrations, however, were found in soils from alluvial and high land sites and household garden sites. Arsenic, Sb and Bi contents in plant samples varied depending upon their species and parts, with higher concentrations in spring onions, soybean leaves and perilla leaves and lower levels in red peppers, corn grains and jujube grains. These results confirm that elemental concentrations in plant leaves are much higher than those in plant grain. Elevated levels of As, Sb and Bi were also found in stream sediments sampled in the vicinity of the mine and decreased with distance from the mine. Concentrations in stream water samples ranged from 0.8 to 19.1 microg As l(-1) and from 0.3 to 8.4 microg Bi l(-1); all the samples contained less than 1.0 microg Sb l(-1). Because of very low particulate loading at the time of sampling, the metal contents in particulates were very low (< 8.2 microg As l(-1), < 0.22 microg Sb l(-1) and 2.8 microg Bi l(-1). This may be mainly due to the low solubility of those elements under moderately acidic and oxidizing conditions of the mining area.

Antimony↗
PubMed2000

Organoleptic impact of 2-methoxy-3-isobutylpyrazine on red bordeaux and loire wines. Effect of environmental conditions on concentrations in grapes during ripening.

The 2-methoxy-3-isobutylpyrazine content in grapes and red wines was assayed by stable isotope dilution gas chromatography-mass spectrometry, following vapor extraction and purification on a cation resin microcolumn. The threshold beyond which the green bell pepper character is marked in wines has been determined. From a comparison of the 2-methoxy-3-isobutylpyrazine concentrations of 50 red Bordeaux and Loire wines from different vintages and grape varieties (Cabernet Sauvignon, Cabernet franc, and Merlot) with the intensity of the green bell pepper character as perceived on tasting, the threshold value was estimated to be 15 ng/L. Statistical analysis of the 2-methoxy-3-isobutylpyrazine concentrations of 89 red Bordeaux wines showed that Cabernet wines were more commonly affected by this vegetative character. Changes in the 2-methoxy-3-isobutylpyrazine concentration as the grapes ripen are affected by the environmental and cultural conditions (soil, climate, training system, etc.). A very good correlation was shown between the breakdown of malic acid and 2-methoxy-3-isobutylpyrazine as the grapes ripened, irrespective of grape variety, type of soil, or weather conditions.

Environment↗
PubMed2004

Bioavailability of selenium from meat and broccoli as determined by retention and distribution of 75Se.

The concentration of selenium (Se), an essential nutrient, is variable in foods, depending, in part, on how and where foods are produced; some foods accumulate substantial amounts of Se when produced on high-Se soils. The chemical form of Se also differs among foods. Broccoli is a Se-accumulating plant that contains many methylated forms of Se, and Se bioavailability from broccoli has been reported to be low. Red meats such as pork or beef could accumulate Se when the animal is fed high-Se diets, and Se from such meats has been reported to be highly bioavailable for selenoprotein synthesis. In a further attempt to characterize the utilization of Se from broccoli and meats such as pork or beef, we have fed rats diets adequate (0.1 microg Se/g diet) in Se or high in Se (1.5 microg S/g diet), with the Se source being either high-Se broccoli or beef. Rats were then given test meals of broccoli or pork intrinsically labeled with 75Se. When dietary Se was nutritionally adequate (0.1 microg/g diet), more 75Se from pork than broccoli was retained in tissues; however, there were no significant differences in whole-body retention when dietary Se was high (1.5 microg/g diet). A significantly greater percentage of 75Se from broccoli than pork was excreted in the urine and dietary Se did not affect urinary excretion of broccoli 75Se, but the amount excreted from pork varied directly with dietary Se intake. Radiolabeled 75Se derived from pork effectively labeled selenoproteins in all tissues examined, but 75Se from broccoli was undetectable in selenoproteins. These differences in retention and distribution of Se from broccoli or pork are consistent with reported differences in bioavailability of Se from beef and broccoli. They also suggest that there are fewer differences in bioavailability when Se is consumed in supranutritional amounts.

Animal Feed↗
PubMed2006

Fall fertilization timing effects on nitrate leaching and turfgrass color and growth.

Fall season fertilization is a widely recommended practice for turfgrass. Fertilizer applied in the fall, however, may be subject to substantial leaching losses. A field study was conducted in Connecticut to determine the timing effects of fall fertilization on nitrate N (NO3-N) leaching, turf color, shoot density, and root mass of a 90% Kentucky bluegrass (Poa pratensis L.), 10% creeping red fescue (Festuca rubra L.) lawn. Treatments consisted of the date of fall fertilization: 15 September, 15 October, 15 November, 15 December, or control which received no fall fertilizer. Percolate water was collected weekly with soil monolith lysimeters. Mean log(10) NO3-N concentrations in percolate were higher for fall fertilized treatments than for the control. Mean NO3-N mass collected in percolate water was linearly related to the date of fertilizer application, with higher NO3-N loss for later application dates. Applying fall fertilizer improved turf color and density but there were no differences in color or density among applications made between 15 October and 15 December. These findings suggest that the current recommendation of applying N in mid- to late November in southern New England may not be compatible with water quality goals.

Color↗
PubMedDate not supplied

Short term effects of Glomus claroideum and Azospirillum brasilense on growth and root acid phosphatase activity of Carica papaya L. under phosphorus stress.

Arbuscular mycorrhizal fungi (AMF) are able to increase root enzymatic activity of acid and alkaline phosphatases. However, the role of AMF on phosphatase activity has not been reported in papaya (Carica papaya L.), which is frequently established at places with soil phosphorus (P) deficiencies. The goals of this research were to determine the effect of Glomus claroideum (Gc), and plant growth promoting rhizobacterium Azospirillum brasilense strain VS7 [Ab]) on root phosphatase activity and seedling growth of Carica papaya L. cv. Red Maradol under low P conditions. There were four treatments-colonization with: 1) Gc, 2) Ab, 3) Gc+Ab, and 4) non-inoculated seedlings. Plants were established in a coarse sand:sandy loam substrate under P-limitation (11 microg P ml(-1)), supplied with a modified Long Ashton Nutrient Solution. Seedling growth was severely reduced by low P. Gc+Ab inoculated plants had greater total dry matter and leaf area than non-colonized plants. Gc-inoculated plants had greater leaf area than non-colonized plants. Treatments did not differ in leaf area ratio, specific leaf area and, total chlorophyll content. There was a non-significant effect on stem relative growth rate with Gc and Gc+Ab plants. Mycorrhizal colonization enhanced the bacterial population 3.4-fold in the Gc+Ab treatment compared with the population quantified in Ab treatment. Soluble and extractable root acid phosphatase activity (RAPA) was higher in Gc inoculated plants. We discussed on the possible relation among both inoculated microorganisms and also with the P-limitation which plants were established.

Acid Phosphatase↗
PubMed1993

Cadmium and lead residues in field-collected red swamp crayfish (Procambarus clarkii) and uptake by alligator weed, Alternanthera philoxiroides.

The whole-body residues of Cd and Pb in the tissues of Louisiana swamp crayfish (Procambarus clarkii) were determined by flame AAS technique. Test animals were collected from roadside ditches (18 locations) alongside major highways. The water and soil samples were also collected from the same sites. The mean Cd and Pb concentrations (mg/l) in crayfish tissues were 0.46 and 0.07, respectively. The levels of Cd and Pb in the water were 0.09 and 0.04; and in soil were 2.85 and 0.87 mg/l, respectively. The concentration of cadmium was 32 and Pb 12 times more than in the water. The bioaccumulation factors (BF) for Cd and Pb in crayfish tissues were 5.1 and 1.7, Alligator weed (Alternanthera philoxiroides) plants were exposed to 0.5 mg/l Cd-chloride or Pb-nitrate solutions for 3 wk period, thrice. The mean Pb accumulation in roots was 1.31 mg/l, followed by stem (0.078 mg/l), but Cd only accumulated in root (0.83 mg/l). The BF for Pb and Cd in plant tissues were 14.8 and 16.6, respectively. The uptake of metals was time-dependent (P = < 0.01). These data suggest that although there is no biomagnification of Cd and Pb from alligator weed to crayfish, both metals readily accumulate in field-collected crayfish and laboratory-exposed alligator weed.

Animals↗
PubMed2001

Light reflected from colored mulches affects aroma and phenol content of sweet basil (Ocimum basilicum L.) leaves.

Basil (Ocimum basilicum L.) is an herb the leaves of which are used to add a distinct aroma and flavor to food. It was hypothesized that the size and chemical composition of sun-grown basil leaves could be influenced by the color of light reflected from the soil surface and by the action of the reflected light through the natural growth regulatory system within the growing plants. Leaf morphology, aroma compounds, and soluble phenolics were compared in basil that had been grown over six colors of polyethylene row covers. Altering the ratios of blue, red, and far-red light reflected to growing plants influenced both leaf morphology and chemistry. Leaves developing over red surfaces had greater area, moisture percentage (succulence), and fresh weight than those developing over black surfaces. Basil grown over yellow and green surfaces produced significantly higher concentrations of aroma compounds than did basil grown over white and blue covers. Leaves grown over yellow and green mulches also contained significantly higher concentrations of phenolics than those grown over the other colors. Clearly, the wavelengths (color) of light reflected to growing basil plants affected leaf size, aroma, and concentrations of soluble phenolics, some of which are antioxidants.

Color↗
PubMed1999

Isolation of azo-dye-degrading microorganisms and their application to white discharge printing of fabric.

Three bacterial strains, which degraded azo dyes, were isolated from soil and sewage samples. The strains were identified as Bacillus sp. OY1-2, Xanthomonas sp. NR25-2 and Pseudomonas sp. PR41-1. The bacteria produced azo-dyes-degrading enzymes. That catalyzed the reduction of methyl red and produced dimethyl p-phenylenediamine and o-aminobenzoic acid. The enzymes could thus be applied to white discharge printing of azo-dyed fabric by owing to there.

Journal Article↗
PubMed2006

Blue light activates the sigmaB-dependent stress response of Bacillus subtilis via YtvA.

Here we present evidence for a physiologically relevant light response mediated by the LOV domain-containing protein YtvA in the soil bacterium Bacillus subtilis. The loss and overproduction of YtvA abolish and enhance, respectively, the increase in sigma(B)-controlled ctc promoter activity at moderate light intensities. These effects were absent in the dark and in red light but present under blue-light illumination. Thus, activation of the general stress response in B. subtilis is modulated by blue light.

Bacillus subtilis↗
PubMed2005

Susceptibility of six cultivars of bean to different isolates of two species of Fusariumin greenhouse.

In greenhouse, susceptibility of 6 cultivars of bean (b1, green bean cv. contender, b2, Pinto b. cv. Cos-16, b3, green b. Sun Ray, b4, white b. cv. Daneshkadeh, b5, red b. cv. Naz, b6, red b. cv. Goli) evaluated to 7 isolates of 2 species of Fusarium (6 isolates of F. oxysporum and 1 isolate of F. solani from Varamin, Iran) in 4 pots (as replications) in factoriel experiment. The seedlings of each bean cultivars soaked in a suspension of the fungi (106 spores/ml.) for 5 minutes and transplanted into the pots contained sterilized soil, for control, the roots soaked in distilled water. After 35 days of inoculating and transplanting in greenhouse conditions (with 18-26 degrees C and 12 h light & 12 h dark) the percentage of necrotic roots and stems of the seedlings affected to the isolates of the fungi, also height and weight of them in different treatments datermined and calculated. The results showed that, the average of necrotic percent of the cultivars of bean seedlings grouped in 3 category (b1, b2, b3, b4 with 25.15% in group a and b5, red bean cv. Naz with 16.29% in group b and b6 red bean cv. Goli with 10.02% in group c) based on cluster analysis. But by Dunken method the infection set on 5 groups as respectively b4, 28,72% (a), b2, 25.83% (ab), b1 & b3, 23,18% & 22.84% (b), b5, 16.29% (c) and b6, 10.02% (d). So, red bean cv. Goli was more resistant and white bean cv. Daneshkadeh was more susceptible than of another cultivars, but averse the effect of the fungi on growth factors were different.

Cluster Analysis↗
PubMed2001

Yeast strains from Livingston Island, Antarctica.

Five yeast strains were isolated from soil and moss samples from the Livingston Island (Antarctica) and identified according to morphological cultural and physiological characteristics. All strains had an optimum growth temperature of 15 degrees C: none grew above 25 degrees C. They assimilated D-glucose, D-galactose, sucrose, cellobiose, trehalose, 2-keto-D-gluconate, D-xylose, D-ribose and melezitose. Four of them were nonfermentative, only one, which formed pseudomycelium fermented glucose, galactose, trehalose. Two strains were identified as pink-red yeasts belonging to genus Rhodotorula--R. minuta and R. mucilaginosa; two were related to the genus Cryptococcus--C. albidus and C. laurentii; one was Candida oleophila.

Antarctic Regions↗
PubMed1985

The role of condensed tannins in the nutritional value of Lotus pedunculatus for sheep. Rates of body and wool growth.

Lotus pedunculatus (cv. Grasslands Maku) grown on acid low-fertility soil and containing high concentrations of condensed tannin (76-90 g/kg dry matter (DM] was grazed by growing sheep for 31-42 d periods in three experiments. In Expt 2 an additional group of lambs grazed areas oversown with white clover (Trifolium repens) and red clover (Trifolium pratense). Lambs were transferred from grazing ryegrass (Lolium perenne)-white clover straight on to lotus in all experiments (unconditioned sheep). In Expt 3 a second group was included which had grazed high-tannin lotus for a pre-experimental period of 8 weeks (conditioned sheep). Effects of condensed tannin on body and wool growth were assessed by studying responses to daily oral administration of polyethylene glycol (PEG; molecular weight 3350, 75-100 g/d). PEG forms a complex with condensed tannin, which is assumed to be inert in its passage through the digestive system, and so effectively reduces the nutritional effects attributable to high condensed-tannin concentrations. Live-weight gain (LWG) in the absence of PEG was low (27-125 g/d) for sheep grazing high-tannin lotus, and PEG administration increased LWG by 41-61 g/d and increased wool growth. In Expt 3, responses to PEG supplementation tended to be less with conditioned than with unconditioned sheep, indicating that conditioned sheep had partially adapted to the high-tannin diet. PEG supplementation had no effect on either LWG or wool growth of sheep grazing areas oversown with mixed clovers, confirming its effects as specific to forages containing condensed tannins. These experiments therefore conclusively show that high concentrations of condensed tannin induced by growing Lotus pedunculatus under low soil fertility conditions prevent maximum expression of LWG and wool growth in grazing sheep. These results contrast with high LWG (153-315 g/d) observed in growing sheep grazing the same lotus cultivar grown in high fertility soil and containing 20 g condensed tannin/kg DM, a level considered to be nutritionally beneficial.

Administration, Oral↗
PubMed1997

Early Forest Soils and Their Role in Devonian Global Change

A paleosol in the Middle Devonian Aztec Siltstone of Victoria Land, Antarctica, is the most ancient known soil of well-drained forest ecosystems. Clay enrichment and chemical weathering of subsurface horizons in this and other Devonian forested paleosols culminate a long-term increase initiated during the Silurian. From Silurian into Devonian time, red clayey calcareous paleosols show a greater volume of roots and a concomitant decline in the density of animal burrows. These trends parallel the decline in atmospheric carbon dioxide determined from isotopic records of pedogenic carbonate in these same paleosols. The drawdown of carbon dioxide began well before the Devonian appearance of coals, large logs, and diverse terrestrial plants and animals, and it did not correlate with temporal variation in volcanic or metamorphic activity. The early Paleozoic greenhouse may have been curbed by the evolution of rhizospheres with an increased ratio of primary to secondary production and by more effective silicate weathering during Silurian time.

Journal Article↗
PubMed1993

TAN-1120, a new anthracycline with potent angiostatic activity.

A potent angiogenesis-inhibitory compound TAN-1120 was found to be produced by a Streptomyces species isolated from a soil sample. The producing organism was characterized as a new subspecies of S. triangulatus and named S. triangulatus subsp. angiostaticus subsp. nov. due to its specific ability to produce the compound. This substance was isolated as a red powder by a combination of organic solvent extraction, silica gel column chromatography and preparative HPLC using an ODS column. Its structure was elucidated by chemical reactions and spectral analyses to be a new baumycin-group anthracycline. Reduction of TAN-1120 gave two compounds, a deoxy derivative and baumycin A1. TAN-1120 showed remarkably potent angiostatic activity in two conventional angiogenesis assay systems in vivo, while doxorubicin and daunomycin had far weaker activity. It strongly inhibited proliferation of vascular endothelial cells did not prevent capillary cord formation in vitro by the endothelial cells on extracellular matrix-coated plates. TAN-1120 is one of the most potent angiostatic agents reported.

3T3 Cells↗
PubMed2004

Biological assessment of contaminated land using earthworm biomarkers in support of chemical analysis.

Biological indicators can be used to assess polluted sites but their success depends on the availability of suitable assays. The aim of this study was to investigate the performance of two earthworm biomarkers, lysosomal membrane stability measured using the neutral red retention assay (NRR-T) and the total immune activity (TIA) assay, that have previously been established as responsive to chemical exposure. Responses of the two assays were measured following in situ exposure to complexly contaminated field soils at three industrial sites as well as urban and rural controls. The industrial sites were contaminated with a range of metal (cadmium, copper, lead, zinc, nickel and cobalt) and organic (including polycyclic aromatic hydrocarbons) contaminants, but at concentrations below the 'New Dutch List' Intervention concentrations. Exposed earthworms accumulated both metals and organic compounds at the contaminated sites, indicating that there was significant exposure. No effect on earthworm survival was found at any of the sites. Biomarker measurements, however, indicated significant effects, with lower NRR-T and TIA found in the contaminated soils when compared to the two controls. The results demonstrate that a comparison of soil pollutant concentrations with guideline values would not have unequivocally identified chemical exposure and toxic effect for soil organisms living in these soils. However, the earthworm biomarkers successfully identified significant exposure and biological effects caused by the mixture of chemicals present.

Animals↗
PubMed1991

Degradation of organochlorine compounds in spent sulfite bleach plant effluents by actinomycetes.

Actinomycetes isolated from different soil samples were tested for their abilities to utilize spent sulfite bleach effluents from a paper mill. Degradation and dechlorination of the chlorinated compounds in the effluents of the first two bleaching stages, i.e., chlorination stage [(C + D)red.] and alkaline extraction stage (E1O), were monitored by determining total organic carbon (TOC) and activated-carbon-adsorbable organic-bound halogen (AOX). The isolates showed increased degradation rates after repeated incubations in the effluent-containing medium. Separation of the culture supernatants by ultrafiltration into three fractions of different molecular weights revealed substantial AOX and TOC reductions in the low-molecular-weight fraction. The AOX values of the higher-molecular-weight fractions were also reduced. Extracellular peroxidase and cell wall-bound catalase activities were produced during growth of the microorganisms on bleach effluents.

Actinomycetales↗