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1.
Calcium binding to spinach (Spinacia oleracea L.) stromal proteins was examined by dual-wavelength spectrophotometry using the metallochromic indicator tetramethylmurexide. The data are consistent with the existence of at least two, probably independent, classes of binding sites. The total number of binding sites varied between 90–155 nmol·mg–1 protein with average binding constants of 1.1–2.7·mM–1. Both Mg2+ and La3+ inhibited calcium binding competitively, with average inhibitor constants of 0.26·mM–1 and 39.4·mM–1, respectively; an increase in the potassium concentration up to 50 mM had no effect. In a typical experiment a decrease in pH (7.8 to 7.1) resulted in a decrease in the total number of calcium binding sites from 90 to 59 nmol·mg–1 protein, but in an increase of the average affinity from 2.7 to 4.5·mM–1. Calculations, using these data and those of Gross and Hess (1974, Biochim. Biophys. Acta 339, 334–346) for binding site I of washed thylakoid membranes, showed that the free-Ca2+ concentration in the stroma under dark conditions, pH 7.1, is higher than under light conditions, pH 7.8. The physiological relevance of the observed calcium binding by stromal proteins is discussed.Abbreviations Ca
b
2+
bound calcium
- Ca
f
2+
free calcium 相似文献
2.
Phosphorus and nitrogen excretion rates by zooplankton communities from two eutrophic and shallow Dutch lakes were measured in laboratory. The variations in excretion rates in the lakes (May–October) were caused mainly by fluctuation in zooplankton biomass. Mean summer excretion rates (June–September) were 2.4 and 0.9 µg PO4P·1–1·d–1 in Lake Loosdercht and Lake Breukeleveen, respectively. This difference between the lakes was caused mainly by the lower zooplankton biomass in Lake Breukeleveen. The excretion of 2.4 µg PO4P·1–1·d– compared with the calculated P-demand of phytoplankton of 8.0 µg PO4P·1–1·d–1 is substantial in the summer (June–September) and far more important than the external P-supply of 0.4 µg P·1–1·d–1 and sediment release of 0.5 µg P·1–1·d–1. Both temperature and composition of zooplankton affected the weight specific excretion rates of the zooplankton community. The weight specific community excretion rates of P and N increased with temperature (exponential model); 1–8 g PO4P·mg–1 zooplankton-C·d–1 and 5–42 µg NH3N·mg–1 zooplankton-C·d–1 (10°C–20°C). 相似文献
3.
Silva E.M. Escamilla Dendooven L. Reynell J.A. Uscanga Ramírez A.I. Monroy Alatorre G. González de la Torre Martínez M. 《World journal of microbiology & biotechnology》1999,15(6):753-755
Strain H-984 of G. fujikuroi grown for 38h in a shake flask with medium containing 20g glucose l–1, 3g yeast extract l–1, 2.5g NH4NO3 l–1, 0.5g KH2PO4 l–1, 0.1g MgSO4 l–1, 1g CaCO3 l–1, and inoculated into a bioreactor with medium containing 60g glucose l–1; 1g NH4Cl l–1; 3g KH2PO4 l–1 and 1.5g MgSO4 l–1 produced 1100mg gibberellic acid l–1. 相似文献
4.
A 64-kilodalton (kDa) protein, situated in the lumen between the inner and outer envelopes of pea (Pisum sativum L.) chloroplasts (Soll and Bennett 1988, Eur. J. Biochem., 175, 301–307) is shown to undergo reversible phosphorylation in isolated mixed envelope vesicles. It is the most conspicuously labelled protein after incubation of envelopes with 33 nmol·1-1 [-32P]ATP whereas incubation with 50 mol·1-1 [-32P]ATP labels most prominently two outer envelope proteins (86 and 23 kDa). Half-maximum velocity for phosphorylation of the 64-kDa protein occurs with 200 nmol·1-1 ATP, and around 40 mol·1-1 ATP for phosphorylation of the 86- and 23-kDa proteins, indicating the operation of two distinct kinases. GGuanosine-, uridine-, cytidine 5-triphosphate and AMP are poor inhibitors of the labelling of the 64-kDa protein with [-32P]ATP. On the other hand, ADP has a potent influence on the extent of labelling (half-maximal inhibition at 1–5 mol·1-1). The ADP-dependent appearance of 32P in ATP indicates that ADP acts by reversal of kinase activity and not as a competitive inhibitor. However, the most rapid loss of 32P from pre-labelled 64-kDa protein occurs when envelope vesicles are incubated with ATP t1/2=15 s at 20 molsd1-1 ATP). This induced turnover of phosphate appears to be responsible for the rapid phosphoryl turnover seen in situ.Abbreviations LHCP
ligh-harvesting chlorophyll-a/b-binding protein
- S0.5
concentration giving half-maximal phosphorylation
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis
- Tricine
N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine 相似文献
5.
Peter H. Barry 《The Journal of membrane biology》1977,34(1):383-408
Summary It has been shown in an earlier paper that the slow transient decrease in conductance, somtimes referred to as creep, obtained with small-to-medium hyperpolarizing current or voltage pulses is due to K+ transport number differences across the walls of the transverse tubular system. Using the same basic numerical analysis and the parameters already obtained experimentally in the previous paper for frog skeletal muscle in a sulphate Ringer's solution, this paper predicts the equivalent membrane capacitance and dynamic resistance due to transport number effects for very low amplitude and low frequency sinusoidal currents from the phase lag of the voltage response behind the current. Such sinusoidal currentper se give rise to an equivalent capacitance which increased from less than 1F·cm–2 at 10 Hz to about 16F·cm–2 at 0.01 Hz and to an equivalent dynamic membrane resistance which increases from its instantaneous slope resistance value of 11.7kcm2 at 10 Hz to about 16kcm2 at 0.01 Hz. Similar small sinusoidal components of current superimposed on depolarizing and hyperpolarizing pulses (25–45 mV) give rise to even greater capacitances at low frequencies (e.g., 24–28F·cm–2 at 0.01 Hz). The response due to large sinusoidal currents was also investigated. These transport number effects help to explain the small discrepancies obtained by some workers between experimental and predicted values of skeletal muscle fiber impedances measured in the 1–10 Hz range and would seem to be critical for the interpretation of any skeletal muscle fiber impedance studies done at frequencies less than 1 Hz. 相似文献
6.
Summary The basolateral potassium conductance of cells of most epithelial cells plays an important role in the transcellular sodium transport inasmuch as the large negative equilibrium potential of potassium across this membrane contributes to the electrical driving force for Na+ across the apical membrane. In the present study, we have attempted to establish, theI-V curve of the basolateral membrane of theAmphiuma collecting tubule, a membrane shown to be K+ selective. TransepithelialI-V curves were obtained in short, isolated perfused collecting tubule segments. The shunt conductance was determined using amiloride to block the apical membrane Na+ conductance. In symmetrical solutions, the shuntI-V curve was linear (conductance: 2.2±0.3 mS·cm–2). Transcellular current was calculated by subtracting the shunt current from the transepithelial current in the absence of amiloride. Using intracellular microelectrodes, it was then possible to measure the basolateral membrane potential simultaneously with the transcellular current. The basolateral conductance was found to be voltage dependent, being activated by hyperpolarization: conductance values at –30 and –80 mV were 3.6±1.0 and 6.6±1.0 mS·cm–2, respectively. BasolateralI-V curves were thus clearly different from that predicted by the constant field model. These results indicate that the K+-selective basolateral conductance of an amphibian collecting tubule shows inward (anomalous) rectification. Considering the electrogenic nature basolateral Na–K-pump, this may account for coupling between pump-generated potential and basolateral K+ conductance. 相似文献
7.
Susan A. Mendelsohn Bruce D. Cherksey Kevin J. Degnan 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1981,145(1):29-35
Summary Activation of the -adrenergic receptors of the opercular epithelium ofFundulus heteroclitus stimulates Cl– secretion, while activation of the -adrenergic receptors inhibits Cl– secretion (Degnan and Zadunaisky, 1979). The possible involvement of adenosine 3, 5-monophosphate (cAMP) in these adrenergic responses was investigated. Isolated opercular epithelia incubated in Ringer, containing 10 mM theophylline, had cAMP levels ranging between 5.3 and 19.3 pmoles·mg protein–1 (mean=9.5±1.0 pmoles·mg protein–1). Activation of the -receptors by 10–5 M isoproterenol increased the mean cAMP level 430% (P<0.001). Blockage of the -receptors with propranolol greatly reduced the increase in cAMP in response to isoproterenol. Activation of the -receptors by 10–5 M arterenol stimulated the mean cAMP level 270% (P<0.01). However, when the -receptors were blocked with propranolol, arterenol had no effect on the cAMP level. The possible involvement of Ca++ in these adrenergic responses was investigated. Neither the stimulatory effect of isoproterenol, nor the inhibitory effect of arterenol on the Cl– secretion were diminished in the absence of extracellular Ca++. The Ca++ ionophore, A23187, and the calmodulin inhibitor, trifluoperazine, had no effects on the Cl– secretion. The Ca++-channel blocker, D600, had a significant inhibitory effect (P<0.005). Guanosine 3,5-monophosphate (cGMP) had no effect on the Cl– secretion.The results indicate that -adrenergic stimulation of Cl– secretion across the opercular epithelium is accompanied by an elevation in tissue cAMP levels. -adrenergic inhibition of Cl– secretion does not involve changes in the tissue cAMP. Neither of these responses appear to require Ca++. 相似文献
8.
An extracellular xylanase enzyme fraction A from a mesophilicClostridium strain SAIV was purified by ammonium sulfate precipitation, Sephadex G-50 gel filtration and DEAE-Sephadex A-50 ion exchange. The xylanase exhibited a molecular weight of 30,000 and it was stable upto 55° C with an optimum temperature of 50° C. It was most stable between pH 5–7, with an optimum pH of around 6. The Km value was 7.0 mg·xylan ml-1 and Vmax was 36 mol·xylose liberated mg-1 min-1. Carboxymethyl cellulose, filter paper cellulose and 4-p-nitrophenyl -D-xylopyranoside were not hydrolysed. The specific activity of xylanase fraction A (9.8 U mg-1) is 2–10 fold higher than the specific activity of xylanase in other mesophilic, xylanolytic, obligate anaerobic bacteria. A minor fraction of xylanase activity designated as xylanase B was also obtained supporting the view that the multiplicity of xylanases is common in microorganisms. 相似文献
9.
Rhodopseudomonas acidophila strain 7050 can satisfy all its nitrogen and carbon requirements from l-alanine. Addition of 100 M methionine sulfoximine to alanine grown cultures had no effect on growth rate indicating that deamination of alanine via alanine dehydrogenase and re-assimilation of the released NH
4
+
by glutamine synthetase/glutamate synthase was an insignificant route of nitrogen transfer in this bacterium. Determination of aminotransferase activities in cell-free extracts failed to demonstrate the presence of direct routes from alanine to either aspartate or glutamate. The only active aminotransferase involving l-alanine was the alanine-glyoxylate enzyme (114–167 nmol·min–1·mg–1 protein) which produced glycine as end-product. The amino group of glycine was further transaminated to yield aspartate via a glycineoxaloacetate aminotransferase (117–136 nmol·min–1 ·mg–1 protein). No activity was observed when 2-oxoglutarate was substituted for oxaloacetate. The formation of glutamate from aspartate was catalysed by aspartate-2-oxoglutarate aminotransferase (85–107 nmol·min–1·mg–1 protein). Determinations of free intracellular amino acid pools in alanine and alanine+100 M methionine sulfoximine grown cells showed the predominance of glutamate, glycine and aspartate, providing further evidence that in alanine grown cultures R. acidophila satisfies its nitrogen requirements for balanced growth by transamination.Abbreviations ADH
alanine dehydrogenase
- GDH
glutamate dehydrogenase
- GS
glutamine synthetase
- GOGAT
glutamate synthase
- MSO
methionine sulfoximine
- GOT
glutamate-oxaloacetate aminotransferase
- GPT
glutamate-pyruvate amino-transferase
- AGAT
alanine-glyoxylate aminotransferase
- GOAT
glycine-oxaloacetate aminotransferase
- GOTAT
glycine-2-oxoglutarate aminotransferase
- AOAT
alanine-oxaloacetate aminotransferase 相似文献
10.
Sharma Shweta Bhat T.K. Dawra R.K. 《World journal of microbiology & biotechnology》1999,15(6):673-677
Tannase (tannin acyl hydrolase E.C. 3.1.1.20) has been isolated from Aspergillus niger van Tieghem and purified 29-fold. The enzyme had a temperature optimum of 60°C, pH optimum of 6.0 with a second peak at pH 4.5, Km of 0.20mM and Vmax of 5.0mol min–1 mg–1protein. 相似文献
11.
Internal motions of d-ribose selectively 2H-labeled at the 2 position were measured using solid state 2H NMR experiments. A sample of d-ribose-2
-d was prepared in a hydrated, non-crystalline state to eliminate effects of crystal-packing. Between temperatures of –74 and –60°C the C2–H2 bond was observed to undergo two kinds of motions which were similar to those of C2–H2/H2 found previously in crystalline deoxythymidine (Hiyama et al. (1989) J. Am. Chem. Soc., 111, 8609–8613): (1) Nanosecond motion of small angular displacement with an apparent activation energy of 3.6 ± 0.7 kcal mol–1, and (2) millisecond to microsecond motion of large amplitude with an apparent activation energy 4 kcal mol–1. At –74°C, the slow, large-amplitude motion was best characterized as a two-site jump with a correlation time on the millisecond time scale, whereas at –60°C it was diffusive on the microsecond time scale. The slow, large-amplitude motions of the C2–H2 bond are most likely from interconversions between C2-endo and C3-endo by way of the O4-endo conformation, whereas the fast, small-amplitude motions are probably librations of the C2–H2 bond within the C2-endo and C3-endo potential energy minima. 相似文献
12.
Biochemical and biophysical parameters, including D1-protein turnover, chlorophyll fluorescence, oxygen evolution activity and zeaxanthin formation were measured in the marine seagrassZostera capricorni (Aschers) in response to limiting (100 mol·m–2·–1), saturating (350 mol·m–2·s–1) or photoinhibitory (1100 mol·m–2·s–1) irradiances. Synthesis of D1 was maximal at 350 mol·m–2·s–1 which was also the irradiance at which the rate of photosynthetic O2 evolution was maximal. Degradation of D1 was saturated at 350 mol·m–2·s–1. The rate of D1 synthesis at 1100 mol·m–2·s–1 was very similar to that at 350 mol·m–2·s–1 for the first 90 min but then declined. At limiting or saturating irradiance little change was observed in the ratio of variable to maximal fluorescence (Fv/Fm) measured after dark adaptation of the leaves, while significant photoinhibition occurred at 1100 mol·m–2·s–1. The proportion of zeaxanthin in the total xanthophyll pool increased with increasing irradiance, indicative of the presence of a photoprotective xanthophyll cycle in this seagrass. These results are consistent with a high level of regulatory D1 turnover inZostera under non-photoinhibitory irradiance conditions, as has been found previously for terrestrial plants.We would like to thank Professor Peter Böger (Department of Plant Biochemistry, University of Konstanz, Germany) for the kind gift of D1 antibodies. This work was partly supported by a University of Queensland Enabling Grant to CC. 相似文献
13.
Understanding how photosynthetic capacity acclimatises when plants are grown in an atmosphere of rising CO2 concentrations will be vital to the development of mechanistic models of the response of plant productivity to global environmental change. A limitation to the study of acclimatisation is the small amount of material that may be destructively harvested from long-term studies of the effects of elevation of CO2 concentration. Technological developments in the measurement of gas exchange, fluorescence and absorption spectroscopy, coupled with theoretical developments in the interpretation of measured values now allow detailed analyses of limitations to photosynthesisin vivo. The use of leaf chambers with Ulbricht integrating spheres allows separation of change in the maximum efficiency of energy transduction in the assimilation of CO2 from changes in tissue absorptance. Analysis of the response of CO2 assimilation to intercellular CO2 concentration allows quantitative determination of the limitation imposed by stomata, carboxylation efficiency, and the rate of regeneration of ribulose 1:5 bisphosphate. Chlorophyll fluorescence provides a rapid method for detecting photoinhibition in heterogeneously illuminated leaves within canopies in the field. Modulated fluorescence and absorption spectroscopy allow parallel measurements of the efficiency of light utilisation in electron transport through photosystems I and IIin situ.Abbreviations A
net rate of CO2 uptke per unit leaf area (µmol m–2 s–1)
- Asat
light-saturated A
- A820
change in absorptance of PSI on removal of illumination (OD)
- c
CO2 concentration in air (µmol mol–1)
- ca
c in the bulk air; ci, c in the intercellular spaces
- ce
carboxylation efficiency (mol m–2 s–1)
- E
transpiration per unit leaf area (mol m–2 s–1)
- F
fluorescence emission of PSII (relative units)
- Fm
maximal level of F
- Fo
minimal level of F upon illumination when PSII is maximally oxidised
- Fs
the steady-state F following the m peak
- Fv
the difference between Fm and Fo
- F'm
maximal F' generated after the m peak by addition of a saturating light pulse
- F'o
the minimal level of F' after the m peak determined by re-oxidising PSII by far-red light
- g1
leaf conductance to CO2 diffusion in the gas phase (mol m–2 s–1)
- g'1
leaf conductance to water vapour diffusion in the gas phase (mol m–2 s–1)
- kc and ko
the Michaelis constants for CO2 and O2, respectively, (µmol mol–1);
- Jmax
the maximum rate of regeneration of rubP (µmol m–2 s–1)
- l
stomatal limitation to CO2 uptake (dimensionless, 0–1)
- LCP
light compensation point of photosynthesis (µmol m–2 s–1)
- oi
the intercellular O2 concentration (mmol mol–1)
- Pi
cytosol inorganic phosphate concentration
- PSI
photosystem I
- PSII
photosystem II
- Q
photon flux (µmol m–2 s–1)
- Qabs
Q absorbed by the leaf
- rubisCO
ribulose 1:5 bisphosphate carboxylase/oxygenase; rubP, ribulose 1:5 bisphosphate; s, projected surface area of a leaf (m2)
- Vc,max
is the maximum rate of carboxylation (µmol m–2 s–1)
- Wc
the rubisCO limited rate of carboxylation (µmol m–2 s1)
- Wj
the electron transport limited rate of regeneration of rubP (µmol m–2 s–1)
- Wp
the inorganic phosphate limited rate of regeneration of rubP (µmol m–2 s–1)
-
absorptance of light (dimensionless, 0–1)
- a
of standard black absorber 1, of leaf
- s
of integrating sphere walls
- , CO2
compensation point of photosynthesis (µmol mol–1)
-
the specificity factor for rubisCO carboxylation (dimensionless)
- ,
convexity of the response of A to Q (dimensionless 0–1)
-
the quantum yield of photosynthesis on an absorbed light basis (A/Qabs; dimensionless)
-
the quantum yield of photosynthesis on an incident light basis (A/Q; dimensionless)
- app
the maximum
- m
the maximum
- m,app
the photochemical efficiency of PSII (dimensionless, 0–1)
- PSII,m
the maximum 相似文献
14.
Flax anther culture: effect of genotype,cold treatment and media 总被引:2,自引:0,他引:2
Bohuš Obert Beata Dedičová Andrea Hricová Jozef šamaj Anna Pret'ová 《Plant Cell, Tissue and Organ Culture》2004,79(2):233-238
We report on screening of wide range of flax cultivars for androgenic response and on testing of induction conditions for flax (Linum usitatissimum L.) anther culture and plant regeneration. Anthers were cultured on four different media: Mo, N6, MS and N&N supplemented with various combinations of growth regulators. The induction of callus formation from cultured anthers was the highest on N6 (with cultivar PR FGL 77 – 12 %) and N&N media (with cultivar Carolin – 2.8 %), preferentially after cold pretreatment (7days at 8 °C). Shoots were formed on calli derived from the microspores inside the cultured anthers on media N&N and N6 supplemented with 1mgl–1 zeatin or 1mgl–1BAP + 1mgl–1NAA, respectively and elongated on MS medium supplemented with 2mgl–1 zeatin. The highest number of shoots (120) was observed with cultivar Red Wing. Shoots were rooted on MS medium supplemented with 2mgl–1IAA. Our experiments resulted in total in 62 % anther response and 155 plants regenerated and transferred into soil. 相似文献
15.
An investigation of live or freshly prepared feeds used as maturationdiets for freshwater ornamental fish was conducted to uncover similaritiesor differences in total and essential fatty acids. Analysis of these maturation feeds reveals that there are relatively low levels of totalfatty acids (0.81–8.96 mg/100 mg–1 dry weight) and withthe exception of the beef heart diet all other feeds have undetectablelevels of docosahexaenoate (22:6n3). The beef heart diet was observed topossess 4.86 mg 100 mg–1 dry weight of 22:6n3 most probablydue to the addition of skipjack tuna, Katsuwanus pelamis, roe. All otherfeeds examined were found to contain low to moderate levels ofeicosapentaenoate (20:5n3) 0.00–0.61 mg/100 mg–1 dryweight. Surprisingly relatively high amounts of arachidonate (20:4n6)0.16–0.90 mg/100 mg–1 dry weight were observed in all ofthe maturation diets and ranged between 3.79%–27.16% ona percent composition basis. The results obtained to date indicate a need toscrutinize the role of arachidonate in the maturation and spawningprocess. 相似文献
16.
Walter Borzani 《Biotechnology letters》1995,17(12):1295-1298
Summary The following equations represent the influence of the ethanol concentration (E) on the specific growth rate of the yeast cells () and on the specific production rate of ethanol () during the reactor filling phase in fed-batch fermentation of sugar-cane blackstrap molasses: =
0 - k · E and v = v
0
· K/(K +E)
Nomenclature E
ethanol concentration in the aqueous phase of the fermenting medium (g.L–1)
- Em
value of E when = 0 or = 0 (g.L–1)
- F
medium feeding rate (L.h–1)
- k
empirical constant (L.g–1.h–1)
- K
empirical constant (g.L–1)
- Mas
mass of TRS added to the, reactor (g)
- Mcs
mass of consumed TRS (g)
- Me
mass of ethanol in the aqueous phase of the fermenting medium (g)
- Ms
mass of TRS in the aqueous phase of the fermenting medium (g)
- Mx
mass of yeast cells (dry matter) in the fermenting medium (g)
- r
correlation coefficient
- S
TRS concentration in the aqueous phase of the fermenting medium (g.L–1)
- Sm
TRS concentration of the feeding medium (g.L–1)
- t
time (h)
- T
temperature (° C)
- TRS
total reducing sugars calculated as glucose
- V
volume of the fermenting medium (L)
- V0
volume of the inoculum (L)
- X
yeast cells concentration (dry matter) in the fermenting medium (g.L–1)
-
filling-up time (h)
-
specific growth rate of the yeast cells (h–1)
- 0
value of when E=0
-
specific production rate of ethanol (h–1)
- 0
value of when E=0
-
density of the yeast cells (g.L–1)
-
dry matter content of the yeast cells 相似文献
17.
Summary Mercury concentration in intraoral air and urine of seven females with dental amalgam was measured before and after intake of one hard-boiled egg. A considerable decrease in mercury concentration in intraoral air was found. Twenty women with about equal dental amalgam status, with or without subjective symptoms related to dental amalgam, were also studied. Mercury concentrations in intraoral air and urine were measured. For all the 27 women the basal intraoral air concentration of mercury ranged over 0.6–10.4 g/m3 (median value 4.3 g/m3). This corresponds to a release of 0.02–0.38 ng/s (median value 0.16 ng/s). In urine, the mercury concentration varied from < 0.8–6.9 g/g creatinine (median value 1.9 g/g creatinine). Data from both parameters were significantly correlated to the total number of teeth areas with dental amalgam. Protein values in urine indicated no renal damage. Maximum concentrations of mercury vapour in intraoral air for the 27 women who had chewed chewing gum for 5 min varied between 2–60 g Hg/m3 (median value 19 g Hg/m3). This corresponds to 0.07–2.20 ng Hg/s and a median value of 0.70 ng Hg/s. 相似文献
18.
N. A. M. Wales 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,158(5):621-626
Summary Hagfish,Myxine glutinosa, were used in an investigation of the possible effects of various eicosanoids and the prostaglandin synthetase inhibitor indomethacin, on cortisol production, blood pressure control, urine flow and electrolyte balance.Cortisol levels in plasma of untreated control animals and plasma from animals 1 h following injection of 50 g kg–1 prostaglandin E1, E2, A2, F2 TXB2 and indomethacin were not detectable. However, plasma cortisol levels rose to between 10 and 26 pg ml–1 1 h following injection of either 50 g kg–1 arachidonic acid or prostaglandin E2. This rise was similar in magnitude to that produced 1 h following administration of 50 g kg–1 porcine ACTH.The resting dorsal aortic blood pressure of between 3.50 and 3.75 mmHg was reduced on average by 50% for 12–15 min when animals received 10 g kg–1 arachidonic acid, prostaglandin E1, E2, A2, and TXB2 and was effectively reduced to zero for 20 min or more following 50 g kg–1 of these eicosanoids. Similar doses of prostaglandin F2, however, evoked an increase in blood pressure (19–33%) whilst indomethacin was without effect.Control measurements of urine flow inMyxine were estimated to be between 540 and 660 l h–1 kg–1. There was a marked reduction in urine output following the arterial vasodepression induced by arachidonic acid, prostaglandin E1, E2, A2 and TXB2 in doses of 10 g kg–1, an effect which became even more pronouced following injection of 50 g kg–1 quantities, leading in some cases to complete anuria. There was no significant change in urine volume following either the vasopressor action of prostaglandin F2 or following indomethacin.None of the compounds tested in this study significantly influenced the plasma or urine electrolyte status ofMyxine. 相似文献
19.
Nitrate at 70m gave the highest biomass of Camptotheca acuminata in suspension culture in MS medium, but a NH4
+/NO3
– molar ratio of 5:1 (giving a total of 40 m N) gave the maximum camptothecin yield. A two-stage flask culture system was established to improve culture efficiency; cell dry weight, camptothecin content and yield was increased by 30%, 280% and 340%, respectively when compared with those of control, reaching up to 36g l–1, 0.36mgg–1, and 12.8mgl–1, respectively. 相似文献
20.
The growth of mustard was increased significantly when treated with up to 80 kg N ha–1 (N80). Spraying with (2-chloroethyl) trimethylammoniumchloride (chlormequat chloride) increased seed yield and seed protein content. Spraying nitrogen fertilized plots with chlormequat chloride, increased leaf area, leaf area ratio, leaf area duration, number of siliquae plant–1, number of seeds siliqua–1 and length of siliqua. Reducing, non-reducing and total sugars in the leaves at 80 days after sowing were also affected significantly. Chlorophyll a, b and total chlorophyll were little affected. The number of siliquae plant–1 was highly correlated with seed yield in both the seasons of experimentation. The correlation coefficient value () was 0.586 in 1982/83 and 0.912 in 1983/84.The total accumulation of nutrients, i.e. nitrogen, phosphorus and potassium in seed and straw was significantly affected by N80 × chlormequat chloride interaction. 相似文献