共查询到20条相似文献,搜索用时 6 毫秒
1.
Pitt R. E. Parks J. E. Huber S. C. Sangree J. A. 《Plant Cell, Tissue and Organ Culture》1997,50(3):215-219
The permeability of rye leaf protoplasts to glycerol was determined using 1,3-14C glycerol and liquid scintillation spectrometry. Estimates were 1.0×10−8 m s−1 at 0°C and 4.1×10−8 m s−1 at 22 and 31°C. The activation energy for glycerol permeability was 32.8 kJ/mol. The effect of electroporation on glycerol
uptake was also explored. Treatments were performed with a field strength of 100 V/cm and an exponential decay constant of
5.8 ms. At 22 °C, electroporation affected the rate and extent of glycerol permeation, causing an increase in the intercept
of the glycerol uptake curve and a decrease in the slope. Electroporation had no significant effect on glycerol uptake when
performed at 0°C, when the cells were electroporated at 0°C then warmed to 31 °C, or when the cells were electroporated at
22 °C then cooled to 0°C. The results at 22°C were consistent with an influx of glycerol during electroporation.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
2.
Sarigüllü Ozgüney I Yeşim Karasulu H Kantarci G Sözer S Güneri T Ertan G 《AAPS PharmSciTech》2006,7(4):E39-E45
The aim of this study was to evaluate and compare the in vitro and in vivo transdermal potential of w/o microemulsion (M)
and gel (G) bases for diclofenac sodium (DS). The effect of dimethyl sulfoxide (DMSO) as a penetration enhancer was also examined
when it was added to the M formulation. To study the in vitro potential of these formulations, permeation studies were performed
with Franz diffusion cells using excised dorsal rat skin. To investigate their in vivo performance, a carrageenan-induced
rat paw edema model was used. The commercial formulation of DS (C) was used as a reference formulation. The results of the
in vitro permeation studies and the paw edema tests were analyzed by repeated-measures analysis of variance. The in vitro
permeation studies found that M was superior to G and C and that adding DMSO to M increased the permeation rate. The permeability
coefficients (Kp) of DS from M and M+DMSO were higher (Kp=4.9×10−3±3.6×10−4 cm/h and 5.3×10−3±1.2×10−3 cm/h, respectively) than the Kp of DS from C (Kp=2.7×10−3±7.3×10−4 cm/h) and G (Kp=4.5×10−3±4.5×10−5 cm/h). In the paw edema test, M showed the best permeation and effectiveness, and M+DMSO had nearly the same effect as M.
The in vitro and in vivo studies showed that M could be a new, alternative dosage form for effective therapy. 相似文献
3.
Brush border membrane vesicles, BBMV, from eel intestinal cells or kidney proximal tubule cells were prepared in a low osmolarity
cellobiose buffer. The osmotic water permeability coefficient P
f
for eel vesicles was not affected by pCMBS and was measured at 1.6 × 10−3 cm sec−1 at 23°C, a value lower than 3.6 × 10−3 cm sec−1 exhibited by the kidney vesicles and similar to published values for lipid bilayers. An activation energy E
a
of 14.7 Kcal mol−1 for water transport was obtained for eel intestine, contrasting with 4.8 Kcal mol−1 determined for rabbit kidney proximal tubule vesicles using the same method of analysis. The high value of E
a
, as well as the low P
f
for the eel intestine is compatible with the absence of water channels in these membrane vesicles and is consistent with
the view that water permeates by dissolution and diffusion in the membrane. Further, the initial transient observed in the
osmotic response of kidney vesicles, which is presumed to reflect the inhibition of water channels by membrane stress, could
not be observed in the eel intestinal vesicles. The P
f
dependence on the tonicity of the osmotic shock, described for kidney vesicles and related to the dissipation of pressure
and stress at low tonicity shocks, was not seen with eel vesicles. These results indicate that the membranes from two volume
transporter epithelia have different mechanisms of water permeation. Presumably the functional water channels observed in
kidney vesicles are not present in eel intestine vesicles. The elastic modulus of the membrane was estimated by analysis of
swelling kinetics of eel vesicles following hypotonic shock. The value obtained, 0.79 × 10−3 N cm−1, compares favorably with the corresponding value, 0.87 × 10−3 N cm−1, estimated from measurements at osmotic equilibrium.
Received: 28 January 1999/Revised: 15 June 1999 相似文献
4.
Water conductance of the cuticular membrane (CM) of mature sweet cherry fruit (Prunus avium L. cv. Sam) was investigated by monitoring water loss from segments of the outer pericarp excised from the cheek of the fruit.
Segments consisted of epidermis, hypodermis and several cell layers of the mesocarp. Segments were mounted in stainless-steel
diffusion cells with the mesocarp surface in contact with water, while the outer cuticular surface was exposed to dry silica
(22 ± 1 °C). Conductance was calculated by dividing the amount of water transpired per unit area and time by the difference
in water vapour concentration across the segment. Conductance values had a log normal distribution with a median of 1.15 × 10−4 m s−1 (n=357). Transpiration increased linearly with time. Conductance remained constant and was not affected by metabolic inhibitors
(1 mM NaN3 or 0.1 mM carbonylcyanide m-chlorophenylhydrazone) or thickness of segments (range 0.8–2.8 mm). Storing fruit (up to 42 d, 1 °C) used as a source of
segments had no consistent effect on conductance. Conductance of the CM increased from cheek (1.16 ± 0.10 × 10−4 m s−1) to ventral suture (1.32 ± 0.07 × 10−4 m s−1) and to stylar end (2.53 ± 0.17 × 10−4 m s−1). There was a positive relationship (r2=0.066**; n=108) between conductance and stomatal density. From this relationship the cuticular conductance of a hypothetical astomatous
CM was estimated to be 0.97 ± 0.09 × 10−4 m s−1. Removal of epicuticular wax by stripping with cellulose acetate or extracting epicuticular plus cuticular wax by dipping
in CHCl3/methanol increased conductance 3.6- and 48.6-fold, respectively. Water fluxes increased with increasing temperature (range
10–39 °C) and energies of activation, calculated for the temperature range from 10 to 30 °C, were 64.8 ± 5.8 and 22.2 ± 5.0 kJ
mol−1 for flux and vapour-concentration-based conductance, respectively.
Received: 23 March 2000 / Accepted: 28 July 2000 相似文献
5.
Settled zoospores of the green macroalga Enteromorpha intestinalis were subjected to several different freezing and storing
treatments at both cryogenic and non-cryogenic temperatures after which their viability was assessed using a spore germination
bioassay. Three different cooling rates were tested: slow cooling at –1°C min−1 and –0.5°C min−1 to end temperatures in the range –20°C to –40°C, and a two-step procedure whereby the spores were frozen to –30°C at a rate
of –1°C min−1 prior to immersion in liquid nitrogen at –196°C. Spore viability was also investigated using the cryoprotectants glycerol
and dimethyl suphoxide (DMSO), a reduced saline medium and various storage times. In the majority of experiments, the use
of a cryoprotectant during the freezing process significantly increased the viability of the spores, with DMSO affording slightly
greater protection than glycerol. All treatments produced high viabilities (ranging from 75.3–100.0%) after 5-min storage
at the different end temperatures. However, progressively longer storage up to 7 days generally resulted in a marked reduction
in viability. This was with the exception of spores frozen in a reduced saline medium; a medium of 75% seawater and either
5 or 10% DMSO greatly increased spore viability, with values of > 40% recorded for spores stored at –20°C for up to 5 weeks.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Peter W. Kazakoff Timothy R. McGuire Eric B. Hoie Martin Cano Patrick L. Iversen 《In vitro cellular & developmental biology. Animal》1995,31(11):846-852
Summary An essential component of anyin vitro model for endothelial permeability is a confluent cell monolayer. The model reported here utilizes primary human umbilical
vein endothelial cells (HUVEC) cultured on recently developed polyethylene terephthalate micropore membranes. Using a modification
of the Wright-Giemsa stain, confluent HUVEC monolayers grown on micropore membranes were routinely assessed using light microscopy.
Determination of confluence using this method was confirmed by scanning electron microscopy. Transendothelial electrical resistance
of HUVEC monolayers averaged 27.9±11.4 Ω · cm2, 10 to 21% higher than literature values. Studies characterizing the permeability of the endothelial cell monolayer to3H-inulin demonstrated a linear relationship between the luminal concentration of3H-inulin and its flux across HUVEC monolayers. The slope of the flux versus concentration plot, which represents endothelial
clearance of3H-inulin, was 2.01±0.076 × 10−4 ml/min (r2=.9957). The permeability coefficient for the HUVEC monolayer-micropore membrane barrier was 3.17±0.427×10−6 cm/s with a calculated permeability coefficient of the HUVEC monolayer alone of 4.07±0.617×10−6 cm/s. The HUVEC monolayer reduced the permeability of the micropore membrane alone to3H-inulin (1.43±0.445×10−5 cm/s) by 78%. Evans blue dye-labeled bovine serum albumin could not be detected on the abluminal side without disruption
of the HUVEC monolayer. These results demonstrate a model for endothelial permeability that can be extensively assessed for
monolayer integrity by direct visualization, transendothelial electrical resistance, and the permeability of indicator macromolecules. 相似文献
7.
Amy E. Miller Joshua P. Schimel James O. Sickman Thomas Meixner Allen P. Doyle John M. Melack 《Biogeochemistry》2007,84(3):233-245
Cold-season processes are known to contribute substantially to annual carbon (C) and nitrogen (N) budgets in continental high
elevation and high-latitude soils, but their role in more temperate alpine ecosystems has seldom been characterized. We used
a 4-month lab incubation to describe temperature (−2, 0, 5°C) and moisture [50, 90% water-holding capacity (WHC)] effects
on soil C and N dynamics in two wet and one dry meadow soil from the Sierra Nevada, California. The soils varied in their
capacity to process N at and below 0°C. Only the dry meadow soil mineralized N at −2°C, but the wet meadow soils switched
from net N consumption at −2°C to net N mineralization at temperatures ≥0°C. When the latter soils were incubated at −2°C
at either moisture level (50 or 90% WHC), net NO3
− production decreased even as NH4
+ continued to accumulate. The same pattern occurred in saturated (90% WHC) soils at warmer temperatures (≥0°C), suggesting
that dissimilatory processes could control N cycling in these soils when they are frozen. 相似文献
8.
Hiroshi Takashima Ayako Araki Keiko Takemoto Naokazu Yoshikawa Keiichi Tsukahara 《Journal of biological inorganic chemistry》2006,11(3):316-324
In order to understand the detailed mechanism of the stereoselective photoinduced electron-transfer (ET) reactions of zinc-substituted
myoglobin (ZnMb) with optically active molecules by flash photolysis, we designed and prepared new optically active agents,
such as N,N′-dimethylcinchoninium diiodide ([MCN]I2) and N,N′-dimethylcinchonidinium diiodide ([MCD]I2). The photoexcited triplet state of ZnMb, 3(ZnMb)*, was successfully quenched by [MCN]2+ and [MCD]2+ ions to form the radical pair of ZnMb cation (ZnMb·+) and reduced [MCN]·+ and [MCD]·+, followed by a thermal back ET reaction to the ground state. The rate constants (k
q) for the ET quenching at 25 °C were obtained as k
q(MCN)=(1.9±0.1)×106 M−1 s−1 and k
q(MCD)=(3.0±0.2)×106 M−1 s−1, respectively. The ratio of k
q(MCD)/k
q(MCN)=1.6 indicates that the [MCD]2+ preferentially quenches 3(ZnMb)*. The second-order rate constants (k
b) for the thermal back ET reaction from [MCN]·+ and [MCD]·+ to ZnMb·+ at 25 °C were k
b(MCN)=(0.79±0.04)×108 M−1 s−1 and k
b(MCD)=(1.0±0.1)×108 M−1 s−1, respectively, and the selectivity was k
q(MCD)/k
q(MCN)=1.3. Both quenching and thermal back ET reactions are controlled by the ET step. In the quenching reaction, the energy
differences of ΔΔH
≠(MCD–MCN) and ΔΔS
≠(MCD–MCN) at 25 °C were obtained as −1.1 and 0 kJ mol−1, respectively. On the other hand, ΔΔH
≠(MCD–MCN)=11±2 kJ mol−1 and TΔΔS
≠(MCD–MCN)=−10±2 kJ mol−1 were given in the thermal back ET reaction. The highest stereoselectivity of 1.7 for [MCD]·+ found at low temperature (10 °C) was due to the ΔΔS
≠ value obtained in the thermal back ET reaction.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
9.
M. D. Baustian S. Q. Wang K. W. Beyenbach 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(1):61-70
Plasma and urine of toadfish (Opsanus tau) in sea water and 10% sea water were analyzed to assess responses of an aglomerular fish to hypoosmotic challenge. Following
transfer to 10% sea water, plasma osmotic pressure decreased slowly from 318 to 241 mmol · kg H2O−1, over a period of 10–15 days. Urine osmotic pressure decreased in parallel from 299 to 207 mmol · kg H2O−1, leaving urine/plasma ratios of osmotic pressure essentially unchanged. In contrast, the volume and composition of urine
changed rapidly following transfer to 10% sea water. Urine flow rate increased 110% from 3.0 to 6.3 μl · 100g−1 · h−1 and Na+ excretion increased 346%, while excretion of Mg2− and SO4
2− decreased 81% and 90%, respectively. Excretion rates for Cl− were low in seawater toadfish and decreased further in 10% sea water. An unknown sulfur-containing anion, present in the
urine of seawater toadfish, contributed significantly to the composition and ionic balance in urine of toadfish in 10% sea
water. These results suggest that the inability to produce strongly dilute urine obliges toadfish to lose salt in order to
excrete water, in hypoosmotic media. The decrease in plasma osmotic pressure may be both a strategy to reduce osmotic and
ionic gradients in dilute media and a consequence of the kidney's inability to excrete water without salt.
Accepted: 22 August 1996 相似文献
10.
P. A. Sansberro H. Y. Rey L. A. Mroginski M. M. Collavino 《Journal of Plant Growth Regulation》1998,17(2):101-105
The effects of benzyladenine (BAP), kinetin (KIN), zeatin (ZEA), isopentenyladenine (2iP), and thidiazuron (TDZ) were studied
on in vitro growth of rudimentary embryos of Ilex paraguariensis St. Hil. Heart stage zygotic embryos were removed from seeds of immature, light green fruits and cultured aseptically on
quarter-strength Murashige and Skoog medium containing 3% sucrose, 0.65% agar, and supplemented with or without three concentrations
of BAP, KIN, ZEA, 2iP, or TDZ. Cultures were incubated in darkness at 27 ± 2°C. Media containing 4.4 × 10−6
m BAP, 4.6 × 10−6
m KIN, or 4.9 × 10−6
m 2iP were totally ineffective in inducing embryo growth after culture for 28 days. However, lower concentrations of these
compounds (4.4 × 10−8
m BAP, 4.6 × 10−8
m KIN, 4.5 × 10−8
m ZEA, or 4.9 × 10−8
m 2iP) promoted embryo growth. TDZ at 9.9 × 10−9
m, 9.9 × 10−8
m, or 9.9 × 10−7
m induced embryo growth at similar rates. The maximum percentage of embryos converted to seedlings was achieved when the medium
was supplemented with 4.5 × 10−7
m ZEA.
Received August 1, 1997; accepted February 19, 1998 相似文献
11.
Enhanced production of recombinant rabies virus glycoprotein (rRVGP) by Drosophila melanogaster S2 cells through control of culture conditions 总被引:1,自引:0,他引:1
Culture conditions that affect product quality are important to the successful operation and optimization of recombinant protein
production. The objective of this study was to optimize culture conditions for growth of recombinant Drosophila melanogaster S2 cells (S2AcRVGP) in order to enhance the production of rRVGP. The addition of DMSO and glycerol to the medium and growth
at a reduced temperature (22 °C) were the culture condition variations selected to be tested. Experimental cultures were first
performed in serum-free Sf900 II medium in 250 ml Schott flasks. The most promising conditions identified in these experiments
were also tested on a higher scale in a 3l bioreactor. In the Schott flasks experiments, all the changes in culture conditions
resulted in an increase of rRVGP production. The protein concentration was 3.6-fold higher with addition of 1% DMSO and 1%
glycerol and 9.3-fold higher when the cells were cultured at 22 °C instead of the standard 28 °C. The maximum concentration
of rRVGP reached was 591 μg l−1. In bioreactor experiments, with control of pH at 6.20 and DO at 50%, the reduced culture temperature (22 °C) was the strategy
that promoted the highest glycoprotein production, 928 μg l−1. 相似文献
12.
Chlorogenic acid, 3’-O-caffeoyl D-quinic acid, is an inherent ligand present inHelianthus annuus L. The effect of pH on chlorogenic acid binding to helianthinin suggests that maximum binding occurs at pH 6.0. The protein-polyphenol
complex precipitates as a function of time. The association constant of the binding of chlorogenic acid to helianthinin, determined
by equilibrium dialysis, at 31°C has a value of 3.5 ± 0.1 × 104M−-1 resulting in a ΔG value of − 6.32 ± 0.12 kcal /mol. The association constantK
ais 1.0 ± 0.1 × 104M−1 as determined by ultraviolet difference spectral titration at 25°C with ΔG° of -5.46 ± 0.06 kcal/mol. From fluorescence spectral
titration at 28°C, theK
avalue is 1.38 ± 0.1 × 1 0 4M−1 resulting in a ΔG of − 5.70 ± 0.05 kcal/mol. The total number of binding sites on the protein are 420 ± 50 as calculated
from equilibrium dialysis. Microcalorimetric data of the ligand-protein interaction at 23°C suggests mainly two classes of
binding. The thermal denaturation temperature,T
mof the protein decreases from 76°C to 72°C at 1 × 10−3M chlorogenic acid concentration upon complexation. This suggests that the complexation destabilizes the protein. The effect
of temperature onK
aof chlorogenic acid shows a nonlinear increase from 10.2°C to 45°C. Chemical modification of both lysyl and tryptophanyl residues
of the protein decreases the strength of binding of chlorogenic acid. Lysine, tryptophan and tyrosine of protein are shown
to be present at the binding site. Based on the above data, it is suggested that charge-transfer complexation and entropically
driven hydrophobic interaction are the predominant forces that are responsible for binding of chlorogenic acid to the multisubunit
protein, helianthinin.
Publication No. 324. 相似文献
13.
Bustard MT McEvoy EM Goodwin JA Burgess JG Wright PC 《Applied microbiology and biotechnology》2000,54(3):424-431
The aerobic biodegradation of high concentrations of 1-propanol and 2-propanol (IPA) by a mixed microbial consortium was
investigated. Solvent concentrations were one order of magnitude greater than any previously reported in the literature. The
consortium utilized these solvents as their sole carbon source to a maximum cell density of 2.4 × 109 cells ml−1. Enrichment experiments with propanol or IPA as carbon sources were carried out in batch culture and maximum specific growth
rates (μmax) calculated. At 20 °C, μ
max values were calculated to be 0.0305 h−1 and 0.1093 h−1 on 1% (v/v) IPA and 1-propanol, respectively. Growth on propanol and IPA was carried out between temperatures of 10 °C and
45 °C. Temperature shock responses by the microbial consortium at temperatures above 45 °C were demonstrated by considerable
cell flocculation. An increase in propanol substrate concentration from 1% (v/v) to 2% (v/v) decreased the μ
max from 0.1093 h−1 to 0.0715 h−1. Maximum achievable biodegradation rates of propanol and IPA were 6.11 × 10−3% (v/v) h−1 and 2.72 × 10−3% (v/v) h−1, respectively. Generation of acetone during IPA biodegradation commenced at 264 h and reached a maximum concentration of
0.4% (v/v). The results demonstrate the potential of mixed microbial consortia in the bioremediation of solvent-containing
waste streams.
Received: 14 December 1999 / Received revision: 3 April 2000 / Accepted: 7 April 2000 相似文献
14.
Carlos Pedrós-Alió Juan I. Calderón-Paz Núria Guixa Antoni Navarrete Dolors Vaqué 《Polar Biology》1996,16(8):613-622
We determined biomass and activity of microbial plankton across the Polar Front (PF) in Drake Passage during January 1994.
Temperature was around 0°C south and between 3 and 5°C north of the PF. Both biomass and activities of microorganisms were
significantly lower in the Antarctic waters south of the PF than in the sub-Antarctic waters north of it. Thus, values of
chlorophyll a, integrated between 0 and 200 m, reached 150 mgm−2 north, but only 25 mg m−2 south of the PF. Likewise, bacteria varied between 1014 and 4×1013 cells m−2. However, the abundance of heterotrophic nanoflagellates was extremely low throughout Drake Passage (around 3×1010 cells m−2). Bacterial doubling times were long (mean of 25 days). Bacterivory was estimated from the abundance of predators and prey
and from temperature. The grazing impact on bacterioplankton biomass was insignificant (less that 0.05% per day) and low on
bacterial heterotrophic production (15% per day). Neither biomass nor the activities of microorganisms were found to increase
at the PF. The microbial food web was uncoupled and the bacteria did not seem to be controlled by predation. 相似文献
15.
Teresa Manso Carla Nunes Sara Raposo Maria Emília Lima-Costa 《Journal of industrial microbiology & biotechnology》2010,37(11):1145-1155
Large-scale production has been the major obstacle to the success of many biopesticides. The spreading of microbial biocontrol
agents against postharvest disease, as a safe and environmentally friendly alternative to synthetic fungicides, is quite dependent
on their industrial mass production from low-cost raw materials. Considerable interest has been shown in using agricultural
waste products and by-products from food industry as nitrogen and carbon sources. In this work, carob pulp aqueous extracts
were used as carbon source in the production of the biocontrol agent Pantoea agglomerans PBC-1. Optimal sugar extraction was achieved at a solid/liquid ratio of 1:10 (w/v), at 25°C, for 1 h. Batch experiments were
performed in shake flasks, at different concentrations and in stirred reactors at two initial inoculums concentrations, 106 and 107 cfu ml−1. The initial sugar concentration of 5 g l−1 allowed rapid growth (0.16 h−1) and high biomass productivity (0.28 g l−1 h−1) and was chosen as the value for use in stirred reactor experiments. After 22 and 32 h of fermentation the viable population
reached was 3.2 × 109 and 6.2 × 109 cfu ml−1 in the fermenter inoculated at 106 cfu ml−1 and 2.7 × 109 and 6.7 × 109 cfu ml−1 in the bioreactor inoculated at 107 cfu ml−1. A 78% reduction of the pathogen incidence was achieved with PBC-1 at 1 × 108 cfu ml−1, grown in medium with carob extracts, on artificially wounded apples stored after 7 days at 25°C against P. expansum. 相似文献
16.
Exponential growth of “snow molds” at sub-zero temperatures: an explanation for high beneath-snow respiration rates and Q
10 values 总被引:2,自引:0,他引:2
Numerous studies have demonstrated exceptionally high temperature sensitivity of the beneath-snow respiratory flux in cold-winter
ecosystems. The most common, but still untested, explanation for this high sensitivity is a physical one based on the observation
that water availability in soils increases exponentially as soils warm from −3 to 0°C. Here, we present evidence for a biological
hypothesis to explain exponential kinetics and high Q
10 values as beneath-snow soils warm from −3 to 0°C during the early spring in a high-elevation subalpine forest. First, we
show that some of the dominant organisms of the beneath-snow microbial community, “snow molds”, exhibit robust exponential
growth at temperatures from −3 to −0.3°C. Second, Q
10 values based on growth rates across the temperature range of −2 to −0.3°C for these snow molds vary from 22 to 330. Third,
we derive an analytical equation that combines the relative contributions of microbial growth and microbial metabolism to
the temperature sensitivity of respiration. Finally, we use this equation to show that with only moderate snow mold growth
(several generations), the combined sensitivities of growth and metabolism to small changes in beneath-snow soil temperature,
create a double exponential in the Q
10 function that may explain the extremely high (~1 × 106) Q
10 values observed in past studies. Our biological explanation for high Q
10 levels is supported by several independent studies that have demonstrated build up of microbial biomass under the snow as
temperatures warm from −2 to 0°C. 相似文献
17.
Inhibition of photosynthetic processes in foliose lichens induced by temperature and osmotic stress 总被引:2,自引:0,他引:2
Negative effects of osmotically-induced dehydration of two foliose lichen species, Lasallia pustulata and Umbilicaria hirsuta, was studied at physiological (22 °C), low (5 °C) and freezing temperature (−10 °C), using chlorophyll (Chl) fluorescence.
In both species, exposure to increasing sucrose concentrations led to a pronounced decrease in potential (FV/FM), and actual (Φ2) quantum yields of photochemical processes in photosystem 2. L. pustulata was more sensitive to osmotic stress, because comparable osmotic dehydration inhibited FV/FM and Φ2 more than in U. hirsuta. Critical concentration of sucrose that fully inhibited photochemical processes of photosynthesis was 2.5 M, which represented
water potential (Ψw) of −18.8 MPa. Decrease in background Chl fluorescence (F0) and increase in non-photochemical quenching (qN) revealed two phases of osmotic stress in lichens: phase I with no change
(Ψw 0 to −6.6 MPa) and phase II (Ψw −11.3 to −18.8 MPa) typical by substantial change in Chl fluorescence parameters. Effects of thallus anatomy on species-specific
response to osmotic dehydration is discussed and attributed to the results obtained by optical microscopy and Chl fluorescence
imaging technique. 相似文献
18.
HuiJuan Kou Min Ye Qiang Fu Yang Han XiaoLi Du Jing Xie Zhu Zhu TaiSheng Li 《中国科学:生命科学英文版》2012,55(4):321-327
High performance liquid chromatography was coupled with UV detection for simultaneous quantification of lopinavir (LPV) and
ritonavir (RTV) in human plasma. This assay was sensitive, accurate and simple, and only used 200 μL of plasma sample. Samples
were liquid-liquid extracted, and diazepam was used as an internal standard. The chromatographic separation was achieved on
a C18 reversed-phase analytic column with a mobile phase of acetonitrile-sodium dihydrogen phosphate buffer (10 mmol L−1, pH 4.80) (60:40, v/v). UV detection was conducted at 205 nm and the column oven was set at 40°C. Calibration curves were
constructed between 0.5–20 μg mL−1 for LPV and 0.05–5 μg mL−1 for RTV. The relative standard deviations were 2.16%–3.20% for LPV and 2.12%–2.60% for RTV for intra-day analysis, and 2.34%–4.04%
for LPV and 0.31%–4.94% for RTV for inter-day analysis. The accuracy was within 100%±10%. The mean extraction recoveries were
79.17%, 52.26% and 91.35% for RTV, LPV and diazepam, respectively. This method was successfully applied to human plasma samples
from patients orally administered a salvage regimen of lopinavir-ritonavir tablets. 相似文献
19.
P. C. Tiburcio F. C. F. Galvez L. J. Cruz V. C. Gavino 《Journal of applied phycology》2007,19(6):727-731
Gamma linolenic acid (GLA) degradation in Spirulina followed first-order reaction kinetics. At an accelerated temperature range of 45 to 55°C, the degradation rate constants
(k
r) of GLA obtained were 4.0 × 10−2 to 8.8 × 10−2 day−1. The energy of activation (E
a) was 16.53 kcal mol−1, and the Q10 was 2.22. Based on 20% GLA degradation, the shelf life of sun-dried Spirulina at 30°C is 263 days or 8.6 months using the Arrhenius plot, and 258 days or 8.5 months using the Q
10 approach.
Presented at the 6th Meeting of the Asia Pacific Society of Applied Phycology, Manila, Philippines. 相似文献
20.
Mounir R Durieux A Bodo E Allard C Simon JP Achbani EH El-Jaafari S Douira A Jijakli MH 《Biotechnology letters》2007,29(4):553-559
Aureobasidium pullulans (de Bary) Arnaud (Ach 1-1) was grown in a glucose fed-batch fermentor to 106 g dry wt l−1 in 48 h. The cells were dried in a fluidized bed dryer with a final viability of 62%. After 7 months at 4°C, the viability
was 28% of the initial value (= 2.3 × 1010 c.f.u. g−1 dry matter). A protection level of 89% was achieved with the biomass preparation at 1 × 108 c.f.u. ml−1 after 28 and 7 days for apples stored respectively at 5 and 25°C against Penicillium expansum. Our process is suitable to produce large quantities of the strain Ach 1-1 as biological control agent for apple preservation. 相似文献