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The amino acid analog p-fluorophenylalanine (FPA) inhibitedsugar and K+ secretion by nectary glands. FPA specifically reducedthe net excretion of Na+ and Cl by the salt glands ofthe halophyte Limonium vulgare and 36Clexcretion by theglands of the pitcher walls of the carnivorous plant Nepenthes.Net uptake and net accumulation of Na+ and Cl by Limoniumleaf tissue and 36Cl accumulation in Nepenthes pitchertissue were much less inhibited than excretion. The resultsare discussed in relation to literature reporting similar specificeffects of FPA on transport of ions from the symplast of barleyroots into the dead xylem elements. Limonium vulgare, Nepenthes hookeriana, salt-glands, excretion, p-fluorophenylalanine 相似文献
3.
The effect of Na+ on phosphate uptake was studied in four strainsof cyanobacteria: Synechococcus PCC 7942, Gloeothece PCC 6501,Phormidium sp. and Chlorogloeopsis PCC 6912. Phosphate uptakewas stimulated by Na+ in all cases. Li+ and K+ acted as partialanalogues for Na+. Half-saturation [K1/2(Na+)] of phosphateuptake was reached with Na+ concentrations ranging from 317µM in Chlorogloeopsis to 659 µM in Phormidium. Theconcentration of phosphate required to reach half-saturationof phosphate uptake [K1/2(Pi)]was not changed by the presenceof Na+. (Received April 11, 1994; Accepted July 5, 1994) 相似文献
4.
We have found that a significant difference exists in transformationefficiency between the crp+/crp isogenic pair of strainsof Escherichia coli, with the efficiency being much higher incrp than in crp+. The ratio of transformation efficiencybetween crp+ and crp strains depends very little on theplasmid size. This observation suggests that the differenceof the transformation efficiency is due to mechanisms otherthan a crp-regulated endonuclease. The crp gene is one of thefirst specific genes that have been shown to affect transformationefficiency. 相似文献
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Distinct roles of PMCA isoforms in Ca2+ homeostasis of bladder smooth muscle: evidence from PMCA gene-ablated mice 总被引:2,自引:0,他引:2
Liu L Ishida Y Okunade G Pyne-Geithman GJ Shull GE Paul RJ 《American journal of physiology. Cell physiology》2007,292(1):C423-C431
We previously showed that plasma membrane Ca2+-ATPase (PMCA) activity accounted for 2530% of relaxation in bladder smooth muscle (8). Among the four PMCA isoforms only PMCA1 and PMCA4 are expressed in smooth muscle. To address the role of these isoforms, we measured cytosolic Ca2+ ([Ca2+]i) using fura-PE3 and simultaneously measured contractility in bladder smooth muscle from wild-type (WT), Pmca1+/, Pmca4+/, Pmca4/, and Pmca1+/Pmca4/ mice. There were no differences in basal [Ca2+]i values between bladder preparations. KCl (80 mM) elicited both larger forces (150190%) and increases in [Ca2+]i (130180%) in smooth muscle from Pmca1+/ and Pmca1+/Pmca4/ bladders than those in WT or Pmca4/. The responses to carbachol (CCh: 10 µM) were also greater in Pmca1+/ (120150%) than in WT bladders. In contrast, the responses in Pmca4/ and Pmca1+/Pmca4/ bladders to CCh were significantly smaller (4050%) than WT. The rise in half-times of force and [Ca2+]i increases in response to KCl and CCh, and the concomitant half-times of their decrease upon washout of agonist were prolonged in Pmca4/ (130190%) and Pmca1+/Pmca4/ (120250%) bladders, but not in Pmca1+/ bladders with respect to WT. Our evidence indicates distinct isoform functions with the PMCA1 isoform involved in overall Ca2+ clearance, while PMCA4 is essential for the [Ca2+]i increase and contractile response to the CCh receptor-mediated signal transduction pathway. PMCA; bladder smooth muscle; gene-altered mice 相似文献
7.
The biosynthetic pathway from D-glucose to L-(+)-tartaric acid(TA) in detached leaves of the bean, Phaseolus vulgaris L.,was studied in three cultivars, two of which were known to containTA and one of which lacked TA, with the aid of several putativeradiolabeled intermediates, namely D-[l-14C]glucose, D-[6-14C]glucose,D-[U-14C]glucose, D-[U-14C]gluconate, L-[U-14C]-ascorbic acid,L-[l-l4C]idonate, D-xylo-5-[U-14C]hexulosonate, D-xylo-5-[l-14C]hexulosonate,D-xylo-5-[6-l4C]hexulosonate and L-[U-l4C]threonate. D-[U-14C]Glucoseand D-[U-l4C]gluconate were converted to TA with low isotopicyield but this yield was further reduced when leaf tissues weresupplied with unlabeled D-gluconate or D-xylo-5-hexulosonate.D-xylo-5-[U-14C]Hexulosonate and D-xylo-5-[l-14C]hexulosonatewere good precursors of TA. D-xylo-5-[6-14C]Hexulosonate didnot furnish 14C to TA. Addition of a metabolic product of D-xylo-5-hexulosonate(which was labeled by D-xylo-5-[l-14C]hexulosonate but not byD-xylo-5-[6-14C]hexulosonate) to leaves labeled with D-xylo-5-[l-14C]hexulosonatedoubled the incorporation of 14C into TA. L-[U-14C]Ascorbicacid, L-[l-14C]idonate and L-[U-14C]threonate failed to producelabeled TA. A metabolic scheme to accommodate these observationsis presented. (Received October 21, 1988; Accepted March 29, 1989) 相似文献
8.
The data of chlorophyll amounts in diverse bio-communities arecompiled and discussed with reference to matter production. The chlorophyll amount in euphotic zone of lakes and oceanswas less than 1 g/m2, mostly less than 0.1 g/m2. In phytoplanktonblooms it was ca. 0.11 g/m2. Large values of 520g/m2 were obtained in the outdoor mass cultures of Chlorella,in which the high population density and chlorophyll contentof the alga were observed. In terrestrial higher plant communitiesthe chlorophyll amount (ca. 110 g/m2) was usually higherthan in aquatic phytoplankton communities. The largest (13.3g/m2) was obtained with an evergreen gallery forest in Thailand.The chlorophyll amount of desert bio-community could be expectedto be as high as that in water blooms. The maximum chlorophyll amount in bio-communities seems to attainup to 20 g/m2 when the conditions are favorable.
1 Dedicated to Prof. H. TAMIYA on the occasion of his 60th birthday. (Received December 25, 1962; ) 相似文献
9.
2C DNA content values for 70 orchid species from 26 genera,including 37Dendrobiumspecies from eight taxonomic sections,were analysed using flow cytometry. The resulting nuclear DNAcontent values for species other thanDendrobiumranged from 1.91pg 2C-1to 15.19 pg 2C-1nuclei forCadetia tayloriandVanilla phaeantha,respectively.Dendrobiumnuclear DNA content values ranged from1.53 pg 2C-1to 4.23 pg 2C-1nuclei forD. cruentumandD. spectabile,respectively. DNA content measurements varied greatly withinDendrobiumsectionsLatouria and Spatulata. Nuclear DNA content values for the sixspecies analysed within Latouria ranged from 1.88 pg 2C-1nucleiforD. macrophyllumto 4.23 pg 2C-1nuclei forD. spectabile. NuclearDNA content values for the 16 species analysed within Spatulataranged from 1.69 pg 2C-1nuclei forD. discolorto 4.05 pg 2C-1nucleiforD. samoense. The least variation in DNA content was foundwithin the section Phalaenanthe, with nuclear DNA content valuesof 1.79 pg 2C-1, 1.86 pg 2C-1and 1.98 pg 2C-1forD. bigibbum,D.affineandD. phalaenopsis, respectively.Copyright 1998 Annalsof Botany Company Orchidaceae,Dendrobium, flow cytometry, propidium iodide, nuclear DNA, genome size, 2C values. 相似文献
10.
Fusicoccin (FC) inhibited net excretion of Cl by theglands of the pitchers of the carnivorous plant Nepenthes hookeriana;of Na+ and Cl by the salt glands of the halophytes Limoniumvulgare and L. pectinatum and of K+ in the nectar of Acer platanoidesflowers. It had no effect on K+ elimination with nectar of Impatienswalleriana (extrafloral nectaries) and Abutilon striatum. Abscisicacid (ABA) stimulated net excretion of K+ and Cl in Nepenthesand of Na+ and Cl in Limonium but had no effects on K+in nectar. Thus, FC and ABA had opposing effects on ion excretionby the salt eliminating glands of Limonium and Nepenthes. Bothcompounds, however, had similar effects on sugar secretion ofnectary glands which was either inhibited or unaffected by FCand ABA. It is suggested that the effects of FC and ABA on ion excretionby gland cells could be reconciled with literature showing FC-stimulationand possible ABA-inhibition of proton pumps at the plasmalemmaof plant cells. Nepenthes hookeriana, Limonium vulgare, Limonium pectinatum, Acer platanoides, salt-glands, nectaries, excretion, fusicoccin, abscisic acid, proton pump 相似文献
11.
For Gyrodinium aureolum significant irradiance and daylengtheffects were found on the division rate and on the growth-relevantChla-normalized photosynthetic rate (gPB). Optimum conditionsof irradiance and daylength were found at 230 µmol m2s1 and 14 h for the division rate, and at >260 µmolm2 s1 and <6 h for gPB.gPB showed no photoinhibition,while the division rate decreased markedly at irradiances abovesaturation. This difference and the difference in optimum irradiancebetween the division rate and gPB are explained by a decreasein cellular Chla/carbon ratio with increasing irradiance. Thecellular content of carbon and nitrogen decreased significantlywith increasing irradiance. Total phosphorus was independentof irradiance and daylength. Below the saturation irradiancefor gPB the daily Chla-normalized carbon yield may be describedas an exponential function of the daily irradiance (irradiancex daylength). 相似文献
12.
The lipid bilayertechnique was used to characterize theCa2+ dependence of a fastK+ channel formed by a synthetic17-amino acid segment [OaCNP-39-(1-17)] ofa 39-amino acid C-type natriuretic peptide (OaCNP-39) found in platypus (Ornithorhynchusanatinus) venom (OaV). TheOaCNP-39-(1-17)-formed K+ channel was reversiblydependent on1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-buffered cis (cytoplasmic)Ca2+ concentration([Ca2+]cis).The channel was fully active when[Ca2+]ciswas >104 M andtrans (luminal)Ca2+ concentration was 1.0 mM, butnot at low[Ca2+]cis.The open probability of single channels increased from zero at1 × 106 McisCa2+ to 0.73 ± 0.17 (n = 22) at103 McisCa2+. Channel openings to themaximum conductance of 38 pS were rapidly and reversibly activated when[Ca2+]cis,but not transCa2+ concentration(n = 5), was increased to >5 × 104 M(n = 14). Channel openings to thesubmaximal conductance of 10.5 pS were dominant at5 × 104 MCa2+.K+ channels did not open whencisMg2+ orSr2+ concentrations were increasedfrom zero to 103 M or when[Ca2+]ciswas maintained at 106 M(n = 3 and 2). The Hill coefficientand the inhibition constant were 1 and 0.8 × 104 McisCa2+, respectively. Thisdependence of the channel on high[Ca2+]cissuggests that it may become active under1) physiological conditions whereCa2+ levels are high, e.g., duringcardiac and skeletal muscle contractions, and2) pathological conditions that leadto a Ca2+ overload, e.g., ischemicheart and muscle fatigue. The channel could modify a cascade ofphysiological functions that are dependent on theCa2+-activatedK+ channels, e.g., vasodilationand salt secretion. 相似文献
13.
The Partitioning of Nitrate Assimilation Between Root and Shoot of a Range of Temperate Cereals and Pasture Grasses 总被引:2,自引:1,他引:1
Nitrate reductase activity (NRA, in vivo assay) and nitrate(NO-3) content of root and shoot and NO-3 and reduced nitrogencontent of xylem sap were measured in five temperate cerealssupplied with a range of NO-3 concentrations (0·120mol m3) and three temperate pasture grasses suppliedwith 0·5 or 5 0 mol m3 NO-3 For one cereal (Hordeumvulgare L ), in vitro NRA was also determined The effect ofexternal NO-3 concentration on the partitioning of NO-3 assimilationbetween root and shoot was assessed All measurements indicatedthat the root was the major site of NO3 assimilation in Avenasatwa L, Hordeum vulgare L, Secale cereale L, Tnticum aestivumL and x Triticosecale Wittm supplied with 0·1 to 1·0mol m3 NO-3 and that for all cereals, shoot assimilationincreased in importance as applied NO-3 concentration increasedfrom 1.0 to 20 mol m3 At 5.020 mol m3 NO3,the data indicated that the shoot played an important if notmajor role in NO-3 assimilation in all cereals studied Measurementson Lolium multiflorum Lam and L perenne L indicated that theroot was the main site of NO-3 assimilation at 0.5 mol m3NO-3 but shoot assimilation was predominant at 5.0 mol m3NO-3 Both NRA distribution data and xylem sap analysis indicatedthat shoot assimilation was predominant in Dactylis glomerataL supplied with 0.5 or 5.0 mol m3 NO-3 Avena sativa L., oats, Hordeum vulgare L., barley, Secale cereale L., rye, x Triticosecale Wittm., triticale, Triticum aestivum L., wheat, Dactylis glomerata L., cocksfoot, Lolium multiflorum Lam., Italian ryegrass, Lolium perenne L., perennial ryegrass, nitrate, nitrate assimilation, nitrate reductase activity, xylem sap 相似文献
14.
Na+ fluxes in Chara under salt stress 总被引:2,自引:0,他引:2
The influx and efflux of Na+ across the plasma membrane of Characorallina and Chara longifolia were examined under mild saltstress conditions. Na+ influx was found to be rapid in bothspecies with the freely exchangeable cytoplasmic Na+ cominginto isotopic equilibrium with external 22Na+ within 1 h ofexposure to isotope. Cytoplasmlc Na+ concentration and Na+ influxwere greater in C. corallina than in C. longifolla under thesame conditions. Na+ influx across the tonoplast was much lowerthan the flux across the plasma membrane. Na+ efflux was stimulatedat pH 5 relative to pH 7 by 218% in C. coralllna and 320% inC. longifolia. In both species externally applied Li+ inhibitedNa+ efflux at pH 5 but not at pH 7. Na+ etflux was not significantlyinhibited by amiloride. Key words: Na+ influx, Na+ efflux, Na+/H+ antiport, Chara 相似文献
15.
Cucumber seedlings, when cultured in vitro, showed differencesin cotyledon etiolation rates among cultivars with differentgenetic backgrounds for sex expression. The chlorophyll contentin gynoecious cultivars (acrF/acrF) decreased rapidly whilethat in monoecious ones (acr+/acr+) decreased more slowly, andthat in mono-gynoecious ones (acr1/acr1) decreased at an intermediaterate. Etiolation was suppressed even in early-etiolating cultivarswhen the flask remained unsealed or endogenously evolved ethylenewas removed. Cotyledon etiolation was enhanced even in late-etiolatingcultivars when ethephon was added to the flask. The rate ofetiolation corresponded to the ethylene concentration in theflask; much more ethylene was detected in early-etiolating cultivarsthan in late-etiolating ones. Ethylene accumulation is one of the important factors involvedin the cotyledon etiolation observed in in vitro cultures. Thedifference in etiolation rates among seedlings with differentgenetic backgrounds for sex expression corresponds to theirability for ethylene evolution, in the order of acrF>acr1>acr+. (Received January 6, 1981; Accepted March 23, 1981) 相似文献
16.
Hydrococcus brazieri and Arthritica semen on a sandflat at Coodanup,Peel Inlet, Western Australia, accounted for 89.5% of totalmollusc numbers. The mean density of H. brazieri was 9487 m2and A. semen averaged 8105 m2. H. brazieri grew at 0.5mm month1 and reached maturity in 4 months; A. semengrew at 0.3 mm month1 and reached maturity in 6 months.Somatic production in the Peel-Harvey estuarine system was estimatedto be 0.5 g m2yr1for H. brazieri and 4.1 g m2yr1for A. semen. The positions of these two species in the estuarinefoodweb is discussed. (Received 26 June 1981; 相似文献
17.
《Journal of experimental botany》1968,19(2):219
Page 678, line 3, for [4-14C] read [I-14C] Page 678, line 4, for [I-14C] read [4-14C] Page 679, line 17, for C-I of malate read C-4 of malate Page 679, line 18, for C-4 of malate read C-I of malate 相似文献
18.
KARSTEN ULF; WIENCKE CHRISTIAN; KIRST GUNTER O. 《Journal of experimental botany》1991,42(12):1533-1539
The effects of hypo- and hypersaline treatments ranging from768% on the intracellular inorganic ion and organic soluteconcentrations were determined in the eulittoral green macroalgaeUlothrix implexa, Ulothrix subflaccida, Enteromorpha bulbosa,Acrosiphonia arcta, and Ulva rigida from Antarctica and SouthernChile. The main inorganic cations were K+, Na+, and Mg2+ inall species. The major osmolyte in E. bulbosa, A. arcta, andU. rigida was K+ at increasing salinities. In both Ulothrixspecies, however, K+ levels declined during hypersaline stressand Na+ concentrations rose significantly. The main inorganicanions were Cl-, SO24-, and PO34- in all algae, while E. bulbosaand U. rigida also contained NO+3. A. arcta showed an extremelyhigh SO2-4 content. The organic solutes proline, sucrose, andß-dimethylsulphoniopropionate (DMSP) played an importantrole in osmotic acclimation. The occurrence of three organicosmolytes suggests an additional function of these solutes ascryoprotectants in the cold-water macroalgae investigated. 相似文献
19.
The relationships between photosynthesis and photosyntheticphoton flux densities (PPFD, P-l) were studied during a red-tideof Dinophysis norvegica (July-August 1990) in Bedford Basin.Dinophysis norvegica, together with other dinoflagellates suchas Gonyaulax digitate, Ceratium tripos, contributed {small tilde}50%of the phytoplankton biomass that attained a maximum of 16.7µg Chla 1 and 11.93 106 total cells I1.The atomic ratios of carbon to nitrogen for D.norvegica rangedfrom 8.7 to 10.0. The photosynthetic characteristics of fractionatedphytoplankton (>30 µm) dominated by D.norvegica weresimilar to natural bloom assemblages: o (the initial slope ofthe P-l curves) ranged between 0.013 and 0.047 µg C [µgChla]1 h1 [µmol m s1]1the maximum photosynthetic rate, pBm, between 0.66 and 1.85µg C [µghla]1 h1; lk (the photoadaptationindex) from 14 to 69 µ,mol m2 s1. Carbonuptake rates of the isolated cells of D.norvegica (at 780 µmolm2 s1) ranged from 16 to 25 pg C cell1h and were lower than those for C.tripos, G.digitaleand some other dinoflagellates. The variation in carbon uptakerates of isolated cells of D.norvegica corresponded with PBmof the red-tide phytoplankton assemblages in the P-l experiments.Our study showed that D.norvegica, a toxigenic dinoflagellate,was the main contributor to the primary production in the bloom. 相似文献
20.
Mutations that affect flightin expression in Drosophila alter the viscoelastic properties of flight muscle fibers 总被引:1,自引:0,他引:1
Henkin JA Maughan DW Vigoreaux JO 《American journal of physiology. Cell physiology》2004,286(1):C65-C72
Striated muscles across phyla share a highly conserved sarcomere design yet exhibit broad diversity in contractile velocity, force, power output, and efficiency. Insect asynchronous flight muscles are characterized by high-frequency contraction, endurance, and high-power output. These muscles have evolved an enhanced delayed force response to stretch that is largely responsible for their enhanced oscillatory work and power production. In this study we investigated the contribution of flightin to oscillatory work using sinusoidal analysis of fibers from three flightless mutants affecting flightin expression: 1) fln0, a flightin null mutant, 2) Mhc13, a myosin rod point mutant with reduced levels of flightin, and 3) Mhc6, a second myosin rod point mutant with reduced levels of phosphorylated flightin. Fibers from the three mutants show deficits in their passive and dynamic viscoelastic properties that are commensurate with their effect on flightin expression and result in a significant loss of oscillatory work and power. Passive tension and passive stiffness were significantly reduced in fln0 and Mhc13 but not in Mhc6. The dynamic viscous modulus was significantly reduced in the three mutants, whereas the dynamic elastic modulus was reduced in fln0 and Mhc13 but not in Mhc6. Tension generation under isometric conditions was not impaired in fln0. However, when subjected to sinusoidal length perturbations, work-absorbing processes dominated over work-producing processes, resulting in no net positive work output. We propose that flightin is a major contributor to myofilament stiffness and a key determinant of the enhanced delayed force response to stretch in Drosophila flight muscles. flight muscles; muscle mutants; myosin 相似文献