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1.
The effect of methyl bromide and P fertilization on the growth of four agricultural crops in a P-sorbing soil was studied.
Harvestable yields and P tissue content were significantly lower for celery (Apium graveolens L.), onion (Allium cepa L.) and pepper (Capsicum annuum L.) following fumigation. P fertilization up to 330 kg P ha−1 as superphosphate could not reverse this effect. The highest P fertilizer treatment had 25.4 μg g−1 bicarbonate-extractable P and 0.26 μg g−1 water extractable P. This P level produced acceptable commercial yields when vesicular arbuscular mycorrhizae (VAM) were
present (non-fumigated) and indicate the importance of the VAM association for these crops. In contrast, melon (Cucumis melo L.) growth was slightly greater following soil fumigation at all P fertilization rates. These findings indicate that crop
VAM dependence and efficacy of VAM biotypes must be considered as essential components for P fertilization recommendations
on fumigated P-sorbing soils.
Formerly Gilat, now University of Kent, Kent, UK 相似文献
2.
Critical levels of selenium in raya (Brassica juncea Czern L.), maize (Zea mays L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.) were worked out by growing these crops in an alkaline silty loam soil treated with different levels of selenite-Se ranging
from 1 to 25 μg g−1 soil. Significant decrease in dry matter yield was observed above a level of 5 μg Se g−1 soil in raya and maize; 4 μg Se g−1 soil in wheat and 10 μg Se g−1 soil in rice shoots. The critical level of Se in plants above which significant decrease in yield would occur was found to
be 104.8 μg g−1 in raya, 76.9 μg g−1 in maize, 41.5 μg g−1 in rice and 18.9 μg g−1 in wheat shoots. Significant coefficients of correlation were observed between Se content above the critical level and dry
matter yield of raya as well as rice (r = −0.99, P ≤ 0.01), wheat (r = −0.97, P ≤ 0.01) and maize ((r = −0.96, P ≤ 0.01). A synergistic relationship was observed between S and Se content of raya (r = 0.96, P ≤ 0.01), wheat (r = 0.89, P ≤ 0.01), rice (r = 0.85, P ≤ 0.01) and maize (r = 0.84, P ≤ 0.01). Raya, maize and rice absorbed Se in levels toxic for animal consumption (i.e. > 5 mg Se kg−1) when the soil was treated with more than 1.5 μg Se g−1. In case of wheat, application of Se more than 3 μg g−1 soil resulted in production of toxic plants. 相似文献
3.
Interaction effects of phosphorus and zinc on photosynthesis, growth and yield of dwarf bean grown in two environments 总被引:2,自引:0,他引:2
Giorgio Gianquinto Azmi Abu-Rayyan Livia Di Tola Diletta Piccotino Beatrice Pezzarossa 《Plant and Soil》2000,220(1-2):219-228
Two experiments were conducted in a factorial combination of three Zn levels (0, 10 and 40 mg Zn kg-1 soil) and two P levels (0 and 200 mg P kg-1 soil). Experiment 1 was carried out during winter in a heated glasshouse, and experiment 2 during summer under a rain shelter.
Plants of dwarf bean (Phaseolus vulgaris L., cv. Borlotto nano) were grown in pots filled with sandy soil. In both experiments, leaf Zn concentration was reduced
by the addition of P to plants grown at low Zn supply. However, leaf Zn concentration lower than the critical level was observed
only during experiment 2, and the main effects of low Zn were reductions of internode length, light use efficiency and maximum
photosynthetic rate. In plants with leaf Zn concentration lower than the critical level, saturating irradiance levels fell
from ∼1000 μmol m-2 s-1 PPFD to ∼300–400 μmol m-2 s-1 PPFD. Reduction of net photosynthesis was observed from the beginning of flowering and led to decreased seed production.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
Phalaris minorRetz. is a major exotic annual weed in the wheat (Triticum aestivum L.) crop. Unharvested rice (Oryza sativa L.) straw, unburned and burned, is often incorporated in the field prior to cultivating wheat. Isoxaflutole (Balance), a pre-emergent
systemic soil applied herbicide, has potential to control P. minor. Glasshouse experiments were conducted to determine the phytotoxicity of isoxaflutole defined by reductions in relation to
shoot length of P. minor when grown in unamended soil or soil amended with unburned or burned rice straw. A 120 g soil was amended with 0, 1, 2 and
4 g of unburned or burned rice straw, and placed in 150 mL styrofoam pots. Appropriate amount of isoxaflutole (75% active
ingredient, ai) was added to pots to get final concentration of 0, 7.5, 30, 60 and 120 μg ai/pot. Unamended soil and soil
amended with unburned or burned rice straw were analyzed for pH and organic matter; two important determinants of isoxaflutole
activity. Results indicate a significant reduction in shoot length of P. minor when grown in soil treated with isoxaflutole at 30, 60 or 120 μg ai/pot. Inhibition in the shoot length of P. minor was observed when soil amended with unburned straw was treated with isoxaflutole at 7.5 and 30 μg ai/pot compared with unamended
soil treated with similar amounts of isoxaflutole. No significant change in isoxaflutole toxicity was observed when soil amended
with unburned straw was treated with isoxaflutole at 60 and 120 lg ai/pot compared with unamended soil treated with similar
amounts of isoxaflutole. Isoxaflutole phytotoxicity to P. minor shoot length was eliminated when soil amended with burned straw was treated with isoxaflutole at 7.5 and 30 μg ai/pot. P. minor shoot length was greater when soil amended with burned straw was treated with isoxaflutole at 60 and 120 μg ai/pot relative
to herbicide-treated unamended soils. We conclude that incorporation of burned rice straw greatly reduces the phytotoxicity
of isoxaflutole toP. minor. 相似文献
5.
Cell cultures of Commiphora wightii (Arnott.) Bhandari were grown in shake flasks and a bioreactor and an increase in guggulsterone accumulation up to 18 μg
l−1 was recorded in cells grown in the production medium containing a combination of sucrose:glucose (4% total), precursors (phenylalanine,
pyruvic acid, xylose, and sodium acetate), morphactin, and 2iP. A yield of 10 g l−1 biomass and ∼200 μg l−1 guggulsterone was recorded in a 3-l flask and in a 2-l stirred tank bioreactor compared with 6.6 g biomass and 67 μg l−1 guggulsterone in 250-ml flasks. Increased vessel size was correlated with increased biomass and guggulsterone accumulation.
2iP alone was not effective for biomass and guggulsterone accumulation in cell cultures of C. wightii. 相似文献
6.
Summary Callus cultures were established from pith tissue of Coryphantha elephantidens (Lem.) Lem. on Murashige and Skoog (MS) basal medium supplemented with 9.05 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 2.3 μM kinetin. Highest shoot regeneration frequency was observed on a medium containing 6.9 μM kinetin and 2.3 μM 2,4-D under 30 μE m−2 s−1 light intensity with a 16-h photoperiod. Calluses retained organogenic potential throughout several passages of subculture
(18 mo.). Shoots were rooted on MS medium without plant growth regulators. All (100%) plantlets transplanted to soil survived
acclimatization. Regenerated plants showed good overall growth and were morphologically similar to the mother plants. 相似文献
7.
The effect of the fungicide, chlorothalonil, on vesicular-arbuscular mycorrhizal (VAM) symbiosis was studied in a greenhouse
using Leucaena leucocephala as test plant. Chlorothalonil was applied to soil at 0, 50, 100 and 200 μg g−1. The initial soil solution P levels were 0.003 μg mL−1 (sub-optimal) and 0.026 μg mL−1 (optimal). After 4 weeks, the sub-optimal P level was raised to 0.6 μg mL−1 (high). The soil was either uninoculated or inoculated with the VAM fungus, Glomus aggregatum. The fungicide reduced mycorrhizal colonization of roots, development of mycorrhizal effectiveness, shoot P concentration
and uptake and dry matter yields at all concentrations tested, although the highest inhibitory effect was noted as the concentration
of the fungicide was increased from 50 to 100 μg g−1. Phosphorus applied after four weeks tended to partially offset the deleterious effects of chlorothalonil in plants grown
in the inoculated and uninoculated soil which suggests that the fungicide was interfering with plant P uptake. The results
suggest that the use of chlorothalonil should be restricted to levels below 50 μg g−1 if the benefits of mycorrhizal symbiosis are to be expected.
Contribution from Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3464.
Contribution from Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3464. 相似文献
8.
Nath Tiwari Kavindra Chandra Sharma Nilesh Tiwari Vaibhav Deo Singh Brahma 《Plant Cell, Tissue and Organ Culture》2000,63(3):179-185
A protocol is described for rapid and large-scale in vitro clonal propagation of the valuable medicinal herb Centella asiatica (L.) by enhanced axillary bud proliferation in nodal segments isolated from mature plants. Although bud break was dependent
on BA supply, the synergistic combination of 22.2 μM BA and 2.68 μM NAA induced the optimum frequency (91%) of shoot formation as well as shoot number (4 to 5 shoots per node). Subculturing
of nodal segments harvested from the in vitro derived axenic shoots on the multiplication medium enabled continuous production of healthy shoots with similar frequency.
MS medium supplemented with 6.7 μM BA and 2.88 μM IAA was found most suitable for shoot elongation. Rooting was highest (90%) on full-strength MS medium containing 2.46 μM IBA. Micropropagated plants established in garden soil were uniform and identical to the donor plant with respect to growth
characteristics. This micropropagation procedure could be useful for raising a stock of genetically homogenous plant material
for field cultivation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
C. P. Kaviraj G. Kiran R. B. Venugopal P. B. Kavi Kishor Srinath Rao 《In vitro cellular & developmental biology. Plant》2006,42(2):134-138
Summary This study reports a protocol for plant regeneration from cultured explants of green gram [Vigna radiata (L.) Wilezek] via somatic embryogenesis. Somatic embryos were induced from nature cotyledons of var., TAP-7 and Pusa Baisaki
when cultured on Murashige and Skoog (MS) medium fortified with different concentrations of 2,4-dichlorophenoxyacetic acid,
α-naphthaleneacetic acid (NAA) and 2,4,5-trichlorophenoxyacetic acid singly or in combination with 2.22–8.88 μM N
6-benzylaminopurine (BAP) or 2.32–9.38 μM kinetin. The type and concentration of auxin and plant genotype influenced the frequency of somatic embryogenesis. NAA was
the most effective auxin for somatic embryo induction. The well-developed, cotyledonary shaped embryos of var. TAP-7 germinated
into plantlets at a frequency of 56.6% on MS medium supplemented with 1.88 μM abscisic acid and 6.66 μM BAP. Regenerated plants were transferred to soil and grown to maturity with 90% survival. The protocol described here offers
a good potential for genetic improvement using gene transfer techniques and the production of synthetic seeds of V. radiata. 相似文献
10.
Summary
Leptadenia reticulata (Retz.) Wight. & Arn., an important herbal medicinal plant, belongs to the family Asclepiadaceae. This plant has been known
for its medicinal uses since 4500 BC. Presently this is an endangered species. There is a need for applying non-conventional
methods of propagation for conservation and sustainable utilization of biodiversity of Leptadenia reticulata. We developed a micropropagation method for mass multiplication of L. reticulata. Explants harvested from greenhouse-maintained and field-grown plants were used to establish cultures of L. reticulata. The nodal shoot segments were surface-sterilized and cultured on Murashige and Skoog (MS) medium along with additives (25
mg l−1 each of adenine sulfate, arginine, and citric acid, and 50 mg l−1 ascorbic acid) containing 0.6 μM indole-3-acetic acid (IAA) and 9 μM N6-benzyladenine (BA). Three to four shoots differentiated from each node within 25–30 d at 26±2°C and 36 μmol m−2 s−1 spectral flux photon (SFP) for 12 hd−1. Shoots were further multiplied by (1) repeated transfer of mother explant on fresh medium containing 0.6 μM IAA and 2.2 μM BA, and (2) subculture of in vitro-differentiated shoots on MS medium with 6.6 μM BA and 0.6 μM IAA. After three or four subcultures, the basal clump with shoot bases was divided into three or four subclumps and multiplied
on the fresh medium. From each clump 15–20 shoots regenerated within 25 d. Ninety percent of the in vitro-produced shoots rooted ex vitro if these were pulse-treated with 123 μM each of indole-3-butyric acid and β-naphthoxyacefic acid. The plantlets were transferred to bottles containing sterile ‘soilrite’
(soilless compost and soil conditioner) moistened with half-strength MS macrosalts. Ninety-five percent of the plantlets were
hardened in the bottles within 15 d. The hardened plants were then transferred to black polybags in the nursery. Field transferred
plants are growing normally and have flowered. The protocol developed is reproducible. From a single nodal segment about 1700
hardened plants could be regenerated within 174 d. 相似文献
11.
Humic acid effect on pyrene degradation: finding an optimal range for pyrene solubility and mineralization enhancement 总被引:1,自引:0,他引:1
Liang Y Britt DW McLean JE Sorensen DL Sims RC 《Applied microbiology and biotechnology》2007,74(6):1368-1375
The addition of humic acid (HA) to polycyclic aromatic hydrocarbon (PAH) contaminated systems has been shown to enhance, inhibit,
or have no effect on the biodegradation of these PAHs. In this study, the surfactant effects of Elliott soil HA (ESHA) at
two pH values were tested. At pH 7.0, ESHA did not behave as a surfactant. At pH 11.8, ESHA acted as a surfactant, as displayed
by a decrease in surface tension with increasing concentrations of ESHA. The effect of ESHA on pyrene solubility was tested
by adding 0 to 800 μg ESHA/g soil to soil-slurries. Enhancement of pyrene apparent solubility demonstrated a dose- and time-related
effect. Broader doses from 0 to 10,080 μg ESHA/g soil and three higher doses from 3,360 to 10,080 μg ESHA/g soil were tested
for their effects on pyrene mineralization by indigenous soil microorganisms and a novel PAH-degrading Mycobacterium sp. KMS in soil microcosms, respectively. ESHA amendments between 20 and 200 μg ESHA/g soil were found to consistently increase
pyrene mineralization by indigenous microorganisms, while the 10,080 μg ESHA/g soil produced inhibition and all other doses
presented no effects. Pyrene degradation by M. KMS was significantly inhibited by the addition of the highest dose of ESHA. 相似文献
12.
Jameel M. Al-Khayri Feng H. Huang Teddy E. Morelock Tahani A. Busharar 《In vitro cellular & developmental biology. Plant》1992,28(2):64-66
Summary A system for the regeneration of spinach (Spinacia oleracea L.) from mature dry seed explants has been established. The response of two commercial spinach cultivars, ‘Grandstand’ and
‘Baker’, was examined. Callus proliferation was most prominent on MS medium supplemented with 9.3 μM of 6-furfurylaminopurine (kinetin) and 3.39 μM 2,4-dichlorophenoxyacetic acid (2,4-D). Adventitious shoot formation was observed within 8 wk after callus was transferred
onto regeneration medium. Shoot regeneration was best from callus induced on 9.3 μM kinetin and 4.56 μM 2,4-D. The regeneration medium contained 9.3 μM kinetin, 0.045 μM 2,4-D, and 2.89 μM gibberellic acid (GA3). Shoots were rooted on hormone-free medium, and plants grown in a greenhouse showed normal phenotype. This system is beneficial
in rapid propagation of spinach plants, particularly when only a limited number of seeds are available. 相似文献
13.
We tested the effect of forecasted soil drought and warming climate conditions for the next decades on emission rates of isoprenoids
by mediterranean shrublands. We measured isoprenoid emissions by whole dominant mediterranean woody plants (Erica multiflora L. and Globularia alypum L.) inhabiting the studied shrublands. Monoterpene emissions were detected in both species, but isoprene was emitted only
by E. multiflora. Maximum emission rates were found during the hottest periods (except for G. alypum, in which they occurred in autumn), and minimum emission rates in winter in E. multiflora. Terpene emission rates ranged from 0.08 μg/(g dry wt h) in winter in E. multiflora to 8.8 μg/(g dry wt h) in G. alypum in autumn. In E. multiflora, the terpene emission rates decreased in response to soil drought only in summer, but increased in response to warming in
spring and autumn. Isoprene emissions ranged from 0.1 μg/(g dry wt h) in spring to 4.4 μg/(g dry wt h) in summer. The effect
of the treatments was only detected in autumn when soil drought and warming had a negative effect on isoprene emission rates.
These data might improve our knowledge of isoprenoid emissions at the canopy level and in response to climate change, soil
drought, or warming.
Published in Russian in Fiziologiya Rastenii, 2009, Vol. 56, No. 1, pp. 35–45.
The text was submitted by the authors in English. 相似文献
14.
Semiarid areas in the US have realized extensive and persistent exotic plant invasions. Exotics may succeed in arid regions by extracting soil water at different times or from different depths than native plants, but little data is available to test this hypothesis. Using estimates of root mass, gravimetric soil water, soil-water potential, and stable isotope ratios in soil and plant tissues, we determined water-use patterns of exotic and native plant species in exotic- and native-dominated communities in Washington State, USA. Exotic and native communities both extracted 12 ± 2 cm of water from the top 120 cm of soil during the growing season. Exotic communities, however, shifted the timing of water use by extracting surface (0–15 cm) soil water early in the growing season (i.e., April to May) before native plants were active, and by extracting deep (0–120 cm) soil water late in the growing season (i.e., June to July) after natives had undergone seasonal senescence. We found that δ
18O values of water in exotic annuals (e.g., −11.8 ± 0.4 ‰ for Bromus tectorum L.) were similar to δ
18O values of surface soil water (e.g., −13.3 ± 1.4 ‰ at −15 cm) suggesting that transpiration by these species explained early season, surface water use in exotic communities. We also found that δ
18O values of water in taprooted exotics (e.g., −17.4 ± 0.3 ‰ for Centaurea diffusa Lam.) were similar to δ
18O values of deep soil water (e.g., −18.4 ± 0.1 ‰ at −120 cm) suggesting that transpiration by these species explained late season, deep water use. The combination of early-season, shallow water-use by exotic winter-actives and late-season, deep water-use by taprooted perennials potentially explains how exotic communities resist establishment of native species that largely extracted soil water only in the middle of the growing season (i.e., May to June). Early season irrigation or the planting of natives with established root systems may allow native plant restoration. 相似文献
15.
The effects of growth regulators, cold-pretreatment of flower buds, ovule (embryo sac) developmental stage and genotype on
induction of gynogenesis in unpollinated ovule cultures were assessed in niger (Guizotia abyssinica (L. f.) Cass.). Indirect callus-mediated gynogenesis occurred in cvs JNC-6 and Ootacamund when the ovules were cultured on
MS medium supplemented with 30 g l−1 sucrose and 2,4-D either alone (0.5–2.0 μM) or in combination (2.0 μM) with different cytokinins, such as adenine, BA, 2iP
and kinetin (0.5–2.0 μM). An optimum induction of gynogenesis was fostered on medium supplemented with 2.0 μM 2,4-D and 1.0 μM
kinetin. Cold-pretreatment of flower buds had no stimulatory effect, but ovules collected one day before anthesis were most
responsive to gynogenesis. The results showed significant variations in genotypic competence for gynogenesis with cv. Ootacamund
being the most responsive (12.5%) and cv. IGP-76 the least (2.5%). Gynogenic embryos differentiated and matured on media (30 g l−1 sucrose) supplemented with 0.5 μM NAA plus 1.0 μM kinetin, and 0.5 μM ABA, respectively. The haploidy (2n = 1x = 15) of gynogenic plants was confirmed by cytological analysis. 相似文献
16.
Xiuping Zou Demou Li Xiaoying Luo Keming Luo Yan Pei 《In vitro cellular & developmental biology. Plant》2008,44(3):169-177
Highly efficient Agrobacterium-mediated transformation of trifoliate orange (Poncirus trifoliata (L.) Raf.) was achieved via indirect shoot organogenesis. Stable transformants were obtained from epicotyl segments infected
with Agrobacterium strain EHA 105 harboring the binary vector pBI121, which contained the neomycin phosphotransferase gene (NPTII) as a selectable
marker and the β-glucuronidase (GUS) gene as a reporter. The effects of regeneration and selection conditions on the transformation
efficiency of P. trifoliata (L.) Raf. have been investigated. A 7-d cocultivation on a medium with 8.86 μM 6-benzylaminopurine (BA)+1.43 μM indole-3-acetic
acid (IAA) was used to improve callus formation from epicotyl segments after transformation. A two-step selection strategy
was developed to select kanamycin-resistant calluses and to improve rooting of transgenic shoots. Transgenic shoots were multiplied
on shoot induction medium with 1.11 μM BA + 5.71 μM IAA. Using the optimized transformation procedure, transformation efficiency
and rooting frequency reached 417% and 96%, respectively. Furthermore, the number of regenerated escape shoots was dramatically
reduced. Stable integration of the transgenes into the genome of transgenic citrus plants was confirmed by GUS histochemical
assay, PCR, and Southern blot analysis. 相似文献
17.
Renata Matraszek 《Acta Physiologiae Plantarum》2008,30(3):361-370
The author studied the effect of different nickel concentrations (0, 0.4, 40 and 80 μM Ni) on the nitrate reductase (NR) activity
of New Zealand spinach (Tetragonia expansa Murr.) and lettuce (Lactuca sativa L. cv. Justyna) plants supplied with different nitrogen forms (NO3
−–N, NH4
+–N, NH4NO3). A low concentration of Ni (0.4 μM) did not cause statistically significant changes of the nitrate reductase activity in
lettuce plants supplied with nitrate nitrogen (NO3
−–N) or mixed (NH4NO3) nitrogen form, but in New Zealand spinach leaves the enzyme activity decreased and increased, respectively. The introduction
of 0.4 μM Ni in the medium containing ammonium ions as a sole source of nitrogen resulted in significantly increased NR activity
in lettuce roots, and did not cause statistically significant changes of the enzyme activity in New Zealand spinach plants.
At a high nickel level (Ni 40 or 80 μM), a significant decrease in the NR activity was observed in New Zealand spinach plants
treated with nitrate or mixed nitrogen form, but it was much more marked in leaves than in roots. An exception was lack of
significant changes of the enzyme activity in spinach leaves when plants were treated with 40 μM Ni and supplied with mixed
nitrogen form, which resulted in the stronger reduction of the enzyme activity in roots than in leaves. The statistically
significant drop in the NR activity was recorded in the aboveground parts of nickel-stressed lettuce plants supplied with
NO3
−–N or NH4NO3. At the same time, there were no statistically significant changes recorded in lettuce roots, except for the drop of the
enzyme activity in the roots of NO3
−-fed plants grown in the nutrient solution containing 80 μM Ni. An addition of high nickel doses to the nutrient solution
contained ammonium nitrogen (NH4
+–N) did not affect the NR activity in New Zealand spinach plants and caused a high increase of this enzyme in lettuce organs,
especially in roots. It should be stressed that, independently of nickel dose in New Zealand spinach plants supplied with
ammonium form, NR activity in roots was dramatically higher than that in leaves. Moreover, in New Zealand spinach plants treated
with NH4
+–N the enzyme activity in roots was even higher than in those supplied with NO3
−–N. 相似文献
18.
Regalado EL Rodríguez M Menéndez R Concepción AA Nogueiras C Laguna A Rodríguez AA Williams DE Lorenzo-Luaces P Valdés O Hernandez Y 《Marine biotechnology (New York, N.Y.)》2009,11(1):74-80
Daily topical application of the aqueous ethanolic extract of the marine sea grass, Thalassia testudinum, on mice skin exposed to UVB radiation resulted in a dose-dependent recovery of the skin macroscopic alterations over a 6-day
period. Maximal effect (90%) occurred at a dose of 240 μg/cm2, with no additional effects at higher doses. Bioassay-guided fractionation of the plant extract resulted in the isolation
of thalassiolin B (1). Topical application of 1 (240 μg/cm2) markedly reduces skin UVB-induced damage. In addition, thalassiolin B scavenged 2,2-diphenyl-2-picrylhydrazyl radical with
an EC50 = 100 μg/ml. These results suggest that thalassiolin B is responsible for the skin-regenerating effects of the crude extract
of T. testudinum.
Erik L. Regalado and María Rodríguez have contributed equally to this work and should be considered as first authors. 相似文献
19.
Wester RC Hartway T Maibach HI Schell MJ Northington DJ Culver BD Strong PL 《Biological trace element research》1998,66(1-3):111-120
Literature from the first half of this century reports concern for toxicity from topical use of boric acid, but assessment
of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included
inductively coupled plasmamass spectrometry which now allows quantitation of percutaneous absorption of10B in10B-enriched boric acid, borax and disodium octaborate tetrahydrate (DOT) in biological matrices.
In vitro human skin percent doses of boric acid absorbed were 1.2 for a 0.05% solution, 0.28 for a 0.5% solution, and 0.70
for a 5.0% solution. These absorption amounts translated into flux values of, respectively, 0.25, 0.58, and 14.58 μg/cm2/h, and permeability constants (K
p
) of 5.0 x 10-4, 1.2 x 10-4, and 2.9 x 10-4 cm/h for the 0.05%, 0.5%, and 5.0% solutions. The above in vitro doses were at infinite, 1000 μL/cm2 volume. At 2 μL/cm2 (the in vivo dosing volume), flux decreased some 200-fold to 0.07 μg/cm2/h andK
p
of 1.4 x 10-6 cm/h, while percent dose absorbed was 1.75%.
Borax dosed at 5.0%/1000 μL/cm2 had 0.41 percent dose absorbed, flux at 8.5 μg/cm2/h, andK
p
was 1.7 x 10-4 cm/h. Disodium octaborate tetrahydrate (DOT) dosed at 10%/1000 μL/cm2 was 0.19 percent dose absorbed, flux at 7.9 μg/cm2/h, andK
p
was 0.8 x ICH cm/h. These in vitro results from infinite doses (1000 μL/cm2) were a 1000-fold greater than those obtained in the companion in vivo study. The results from the finite (2 μL/cm2) dosing were closer (10-fold difference) to the in vivo results. General application of infinite dose percutaneous absorption
values for risk assessment is questioned by these results. 相似文献
20.
Cell suspension cultures of Commiphora wightii, grown in modified MS medium containing 2,4-dichlorophenoxyacetic acid (0.5 mg l−1) and kinetin (0.25 mg l−1), produced ∼5 μg guggulsterone g−1 dry wt. In a 2 l stirred tank bioreactor, the biomass was 5.5 g l−1 and total guggulsterone was 36 μg l−1. 相似文献