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1.
Clonally propagated plants of Dactylis glomerata derived froma well-drained, heavily grazed cliff habitat (clone L) and froman undergrazed poorly-drained soil (clone A) were tested forwaterlogging tolerance in soil-culture. Water-logging did notaffect the two clones differentially, a result, which contrastedstrongly with that of a previous experiment in which simulatedgrazing (clipping to 20 cm) unexpectedly caused clone A to beless tolerant of waterlogging than clone L. Maximum leaf andleaf sheath length was reduced more by water-logging in cloneL than in clone A (P < 0.05). In solution-culture when providedwith factorial combinations of 0.5, 5 and 50 mg dm2 ofFe2+ and Mn2+ the shoot dry weight yield of the dry-soil clonewas reduced more than that of the wet-soil clone by 50 mg Fedm3 irrespective of Mn2+ concentration (P < 0.01)but the reduction of growth was less at higher Mn2+ concentrations.Fifty milligrams of Mn2+ dm3 reduced the growth of thedry soil clone but increased the growth of the wet soil clonewith Fe2+ at 5 mg dm2 (P < 0.05). Iron at 0.5 mg dm2was suboptimal for shoot growth of both clones at any levelof Mn2+ and caused more severe leaf chlorosis in the wet soilclone. Leaf tissue of clone L contained more iron than thatof clone A after waterlogging (P < 0.01) but in solutionculture, though increasing iron from 0.5 to 50 mg dm3almost doubled leaf iron content (P < 0.001), the interactionClones x Mn x Fe just failed to reach significance at P <0.05. The manganese content of leaf tissue from the two clonesvaried differently in response to solution manganese (Clonesx Mn P < 0.01), clone A showing a slightly greater increaseof manganese content at high solution concentration. Iron at50 mg dm3 suppressed Mn uptake (Mn x Fe, P < 0.001)in both clones. The two clones thus show marked environmentaladaptation to the chemistry of wet and dry soils. Dactylis glomerata, Cocksfoot grass, Orchard grass, waterlogging, iron, manganese, toxicity, deficiency, ecotypes 相似文献
2.
Impedance spectroscopy was used in studying frost hardinessof leaves of two diploid rhododendron cultivars, RhododendronL. PJM and R. Cunningham's White,and their tetraploid derivatives, R. Northern Starburst(NSB) and CW4. After the growing season and initial hardeningin a greenhouse, plants were subjected to an acclimation regimein a phytotron: 3 consecutive weeks at +5, +1 and -2°C each.Hardiness was studied with controlled freezing tests beforeeach decrease in temperature and at the end of the experiment,based on data of extracellular resistance reand relaxation time of the frost-exposed leaves. The correlation of the two estimateswas 0.92. Generally, the diploid clones had better frost hardinessthan the tetraploid clones. At the end of the experiment, frosthardiness of the diploid PJM was -28.7°C andthat of the tetraploid NSB -20.6°C. Leaves of the diploidCunningham's White and of the tetraploid CW4 hardenedto -32.0°C and -20.9°C, respectively. Frost hardinessestimated by impedance spectroscopy correlated well with earlierresults based on visual scoring (r = 0.810.86) and electrolyteleakage tests (r = 0.840.90), but results from impedancespectroscopy indicated weaker hardiness than the other tests.The difference between the results from impedance spectroscopyand the other tests was smaller and more coherent within theCunningham's White clones than within PJMand NSB. Changes in extracellular and intracellular resistanceof non-frozen leaves during the acclimation correlated withthe changes in frost hardiness of Cunningham's Whiteclones, but not with those of PJM and NSB, whichbelong to another subspecies.Copyright 2000 Annals of BotanyCompany Cold resistance, evergreen, frost hardiness, impedance spectroscopy, polyploid, Rhododendron, tetraploid 相似文献
3.
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
4.
Genotypic, Developmental and Drought-Induced Differences in Root Hydraulic Conductance of Contrasting Sugarcane Cultivars 总被引:3,自引:0,他引:3
Hydraulic properties of entire root systems and isolated rootsof three contrasting sugarcane clones were evaluated using transpiration-induceddifferences in hydrostatic pressure across intact root systems,root pressure-generated xylem sap exudation, and pressure-fluxrelationships. Regardless of the measurement technique employed,the clones were ranked in the same order on the basis of theirleaf areaspecific total root system hydraulic conductance(Croot). All methods employed detected large developmental changesin Grootroot with maximum values occurring in plants with approximately02 m2 total leaf area. Genotypic ranking according to Groot,was reflected as a similar ranking according to root length-specifichydraulic conductance (L) of individual excised roots. Genotypicdifferences in Groot and L were consistent with anatomical characteristicsobserved in individual roots. Patterns of Groot, during soildrying and following re-irrigation suggested that the declinein Groot, observed during soil drying occurred within the rootsrather than at the soilroot interface and may have beencaused in part by xylem cavitation in the roots. Key words: Root hydraulic conductance, Saccharum spp, transpiration, root pressure, pressure-flux 相似文献
5.
Kost Benedikt; Galli Alessandro; Potrykus Ingo; Neuhaus Gunther 《Journal of experimental botany》1995,46(9):1157-1167
An efficient system has been established that allows well controlledDNA microinjection into tobacco (Nicotiana tabacum) mesophyllprotoplasts with partially regenerated cell walls and subsequentanalysis of transient as well as stable expression of injectedreporter genes in particular targeted cells or derived clones.The system represents an effective tool to study parametersimportant for the successful transformation of plant cells bymicroinjection and other techniques. Protoplasts were immobilizedin a very thin layer of medium solidified with agarose or alginate.DNA microinjection was routinely monitored by coinjecting FITC-dextranand aimed at the cytoplasm of target cells. The injection procedurewas optimized for efficient delivery of injection solution intothis compartment. Cells were found to be at the optimal stagefor microinjection about 24 h after immobilization in solidmedium. Embedded cells could be kept at this stage for up to4 d by incubating them at 4 C in the dark. Within 1 h successfuldelivery of injection, solution was routinely possible into2040 cells. Following cytoplasmic coinjection of FITC-dextran and pSHI913,a plasmid containing the neo (neomycin phosphotransferase II)gene, stably transformed, paromomycin-resistant clones couldbe recovered through selection. Transgenic tobacco lines havebeen established from such clones. Injection solutions containingpSHI913 at a concentration of either 50 µg ml1or 1 mg ml1 have been tested. With 1 mg ml1 plasmidDNA the percentage of resistant clones per successfully injectedcell was determined to be about 3.5 times higher. Incubationof embedded protoplasts at 4C before microinjection was foundto reduce the percentage of resistant clones obtained per injectedcell Protoplasts were immobilized above a grid pattern and the locationof injected cells was recorded by Polaroid photography. Thefate of particular targeted cells could be observed. Isolationand individual culture of clones derived from injected cellswas possible. Following cytoplasmic coinjection of FITC-dextranand 1 mg ml1 plasmid DNA on average about 20% of thetargeted cells developed into microcalli and roughly 50% ofthese calli were stably transformed. Transient expression ofthe firefly luciferase gene (Luc) was nondestructively analysed24 h after injection of pAMLuc. Approximately 50% of the injectedcells that were alive at this time point expressed the Luc genetransiently. Apparently, stable integration of the injectedgenes occurred in essentially all transiently expressing cellsthat developed into clones. Key words: DNA microinjection, firefly luciferase, FITCdextran, Nicotiana tabacum, protoplast transformation 相似文献
6.
Duhamel TA Green HJ Perco JG Ouyang J 《American journal of physiology. Cell physiology》2006,291(4):C607-C617
We employed a glycogen-depleting session of exercise followed by a low-carbohydrate (CHO) diet to investigate modifications that occur in muscle sarcoplasmic reticulum (SR) Ca2+-cycling properties compared with low-CHO diet alone. SR properties were assessed in nine untrained males [peak aerobic power (O2 peak) = 43.6 ± 2.6 (SE) ml·kg1·min1] during prolonged cycle exercise to fatigue performed at 58% O2 peak after 4 days of low-CHO diet (Lo CHO) and after glycogen-depleting exercise plus 4 days of low-CHO (Ex+Lo CHO). Compared with Lo CHO, Ex+Lo CHO resulted in 12% lower (P < 0.05) resting maximal Ca2+-ATPase activity (Vmax = 174 ± 12 vs. 153 ± 10 µmol·g protein1·min1) and smaller reduction in Vmax induced during exercise. A similar effect was observed for Ca2+ uptake. The Hill coefficient, defined as slope of the relationship between cytosolic free Ca2+ concentration and Ca2+-ATPase activity, was higher (P < 0.05) at rest (2.07 ± 0.15 vs. 1.90 ± 0.10) with Ex+Lo CHO, an effect that persisted throughout the exercise. The coupling ratio, defined as the ratio of Ca2+ uptake to Vmax, was 2330% elevated (P < 0.05) at rest and during the first 60 min of exercise with Ex+Lo CHO. The 27 and 34% reductions (P < 0.05) in phase 1 and phase 2 Ca2+ release, respectively, observed during exercise with Lo CHO were not altered by Ex+Lo CHO. These results indicate that when prolonged exercise precedes a short-term Lo CHO diet, Ca2+ sequestration properties and efficiency are improved compared with those during Lo CHO alone. calcium cycling; vastus lateralis; contractile activity; glycogen; phosphorylation potential 相似文献
7.
Stamen Number and Variation in Diploid and Tetraploid Cherries 总被引:1,自引:0,他引:1
Stamen numbers were counted on flowers from a collection ofcherries, sweet cultivated varieties of Prunus avixan and P.cerasus. The most frequent numbers were 34 and 3940,no doubt representing seven and eight times the petal number.The character is apparently genetically controlled, clones beinghighly uniform within themselves but differing from others. On the average, flowers of tetraploid Morellos (P. cerasus)had lower numbers than diploid sweet cherries (P. avium), whiletetraploid Dukes were intermediate; this accords with the suspectedhybrid origin of the Dukes. Stamen number and variation wasnot associated with economic characters, but there was a tendencyfor varieties in more frequent incompatibility groups IVIto have lower values than groups VIIXII. 相似文献
8.
Wheat, red clover and ryegrass were grown in flowing solutionculture with sufficient (+ Cu) and deficient (Cu) suppliesof copper. The rates of Cu absorption (µg g1 dryroot day1) did not differ greatly between species ineither treatment. Wheat plants, when transferred from the Cu to the +Cu treatment, absorbed Cu at a much slower rate thanthose which had remained throughout in the + Cu treatment. Inall plants considerable proportions of the absorbed Cu wereretained in the roots, even when the plants were Cu-deficient,and the concentration in roots usually exceeded that in anypart of the shoots in both treatments. Transferring wheat plantsfrom the +Cu to the Cu treatment decreased the concentrationin all plant parts except old leaves; similarly, transferringfrom the Cu to +Cu treatment increased the concentrationin all parts of the shoots, execept old leaves, and in the roots. Lolium perenne, Trifolium pratense, Triticum aestivum, ryegrass, red clover, wheat, absorption, copper, flowing solution culture 相似文献
9.
Green tea extract and its major polyphenol (-)-epigallocatechin gallate improve muscle function in a mouse model for Duchenne muscular dystrophy 总被引:2,自引:0,他引:2
Dorchies OM Wagner S Vuadens O Waldhauser K Buetler TM Kucera P Ruegg UT 《American journal of physiology. Cell physiology》2006,290(2):C616-C625
Duchenne muscular dystrophy is a frequent muscular disorder caused by mutations in the gene encoding dystrophin, a cytoskeletal protein that contributes to the stabilization of muscle fiber membrane during muscle activity. Affected individuals show progressive muscle wasting that generally causes death by age 30. In this study, the dystrophic mdx5Cv mouse model was used to investigate the effects of green tea extract, its major component ()-epigallocatechin gallate, and pentoxifylline on dystrophic muscle quality and function. Three-week-old mdx5Cv mice were fed for either 1 or 5 wk a control chow or a chow containing the test substances. Histological examination showed a delay in necrosis of the extensor digitorum longus muscle in treated mice. Mechanical properties of triceps suræ muscles were recorded while the mice were under deep anesthesia. Phasic and tetanic tensions of treated mice were increased, reaching values close to those of normal mice. The phasic-to-tetanic tension ratio was corrected. Finally, muscles from treated mice exhibited 3050% more residual force in a fatigue assay. These results demonstrate that diet supplementation of dystrophic mdx5Cv mice with green tea extract or ()-epigallocatechin gallate protected muscle against the first massive wave of necrosis and stimulated muscle adaptation toward a stronger and more resistant phenotype. pharmacotherapy; muscular disorders; dystrophic mdx5cv mouse; muscle mechanical properties; muscle histology 相似文献
10.
Yin X Denton J Yan X Strange K 《American journal of physiology. Cell physiology》2007,292(1):C269-C277
An inwardly rectifying swelling- and meiotic cell cycle-regulated anion current carried by the ClC channel splice variant CLH-3b dominates the whole cell conductance of the Caenorhabditis elegans oocyte. Oocytes also express a novel outwardly rectifying anion current termed ICl,OR. We recently identified a worm strain carrying a null allele of the clh-3 gene and utilized oocytes from these animals to characterize ICl,OR biophysical properties. The ICl,OR channel is strongly voltage dependent. Outward rectification is due to voltage-dependent current activation at depolarized voltages and rapid inactivation at voltages more hyperpolarized than approximately +20 mV. Apparent channel open probability is zero at voltages less than +20 mV. The channel has a 4:1 selectivity for Cl over Na+ and an anion selectivity sequence of SCN > I > Br > Cl > F. ICl,OR is relatively insensitive to most conventional anion channel inhibitors including DIDS, 4,4'-dinitrostilbene-2,2'-disulfonic acid, 9-anthracenecarboxylic acid, and 5-nitro-2-(3-phenylpropylamino)benzoic acid. However, the current is rapidly inhibited by niflumic acid, metal cations including Gd3+, Cd2+, and Zn2+, and bath acidification. The combined biophysical properties of ICl,OR are distinct from those of other anion currents that have been described. During oocyte meiotic maturation, ICl,OR activity is rapidly downregulated, suggesting that the channel may play a role in oocyte Cl homeostasis, development, cell cycle control, and/or ovulation. chloride channel; ovulation; cell cycle; meiotic maturation 相似文献
11.
Decoated seeds of Clitoria ternatea L. germinated on Murashigeand Skoog (Physiologia Plantarum 1962, 15, 47397) basalmedium (BM) and differentiated callus and bipolar embryoids(two-step method) in low frequency. Calluses developed on lateralroots [BM+KN(0.1 mg 11)], on roots and hypocotyls [BM+KN(0.5mg 11)], and on roots [BM+KN+IAA (0.5 mg 11 ofeach)]. On basal medium with KN (0.5 mg 11) and withKN+IAA (0.5 mg11 of each), multiple shoot buds and embryoids(one-step method) were differentiated directly on split hypocotylsand roots. In the former, shoot buds developed even on unsplithypocotyls. Rhizogenesis on isolated shoot buds occurred efficientlyin BM+indole butyric acid (IBA 0.1 mg 11) and BM+IAA(0.1 mg 11 and 0.5 mg 11). Profuse direct embryoidsand shoot buds developing on root systems are interesting morphogeneticphenomena rarely reported. Clitoria ternatea L., callus, embryoids, multiple shoot buds, regeneration 相似文献
12.
Peanut (Arachis hypogaea L. ) seed powder accumulated ATP fromAMP and phosphoenolpyruvate (PEP) at a rate of approx. 100 pmolmin1mg powder at 35° C. When peanut seed powderwas incubated with various substrates, which may result in PEPor AMP (ADP) synthesis, then ATP accumulated. The best substratecombinations examined so far were AMP + succinate, NADH2, andAMP + malate + NAD, with activities of 33, 12 and 12 pmol minmg1powder,respectively; AMP + malate showed very low activity. Some combinationsexhibited linear activities with time, while others had an exponential-typeprofile. The temperature dependence of the ATP accumulationdemonstrated by the Ahrrenius plot had a double phase with atransition point at 25° C. The Ea values between 15°C and 25° C were 25 00050 000 cal/mol, while above25° C the Ea values fluctuated between 6000 and 8000 cal/mol(depending on the substrate). The AMP + PEP combination exhibiteda single-phase profile between 15° C and 40° C, withan Ea value of 22 000 cal/mol. In the presence of some substrates,ethephon (ethylene) had a stimulatory effect and caused an increasein the Ea values at the high temperature phase. A comparisonof seed powder from dormant seeds with that from non-dormantseeds revealed that some substrate combinations accumulate ATPfaster in non-dormant seeds and others do so in dormant seeds. Key words: Arachis hypogaea, ATP, Ethylene, Dormancy, Peanut, Seed 相似文献
13.
Biermann J Lang D Gorboulev V Koepsell H Sindic A Schröter R Zvirbliene A Pavenstädt H Schlatter E Ciarimboli G 《American journal of physiology. Cell physiology》2006,290(6):C1521-C1531
Polyspecific organic cation transporters (OCTs) have a large substrate binding pocket with different interaction domains. To determine whether OCT regulation is substrate specific, suitable fluorescent organic cations were selected by comparing their uptake in wild-type (WT) human embryonic kidney (HEK)-293 cells and in HEK-293 cells stably transfected with hOCT2. N-amidino-3,5-diamino-6-chloropyrazine-carboxamide (amiloride) and 4-[4-(dimethylamino)-styryl]-N-methylpyridinium (ASP) showed concentration-dependent uptake in hOCT2 at 37°C. After subtraction of unspecific uptake determined in WT at 37°C or in hOCT2 at 8°C saturable specific uptake of both substrates was measured. Km values of hOCT2-mediated uptake of 95 µM amiloride and 24 µM ASP were calculated. Inhibition of amiloride and ASP uptake by several organic cations was also measured [IC50 (in µM) for amiloride and ASP, respectively, tetraethylammonium (TEA) 98 and 30, cimetidine 14 and 26, and tetrapentylammonium (TPA) 7 and 2]. Amiloride and ASP uptake were significantly reduced by inhibition of Ca2+/CaM complex (55 ± 5%, n = 10 and 63 ± 2%, n = 15, for amiloride and ASP, respectively) and stimulation of PKC (54 ± 5%, n = 14, and 31 ± 6%, n = 26) and PKA (16 ± 5%, n = 16, and 18 ± 4%, n = 40), and they were increased by inhibition of phosphatidylinositol 3-kinase (+28 ± 6%, n = 8, and +55 ± 17%, n = 16). Inhibition of Ca2+/CaM complex resulted in a significant decrease of Vmax (16099 photons/s) that can be explained in part by a reduction of the membrane-associated hOCT2 (22 ± 6%, n = 9) as determined using FACScan flow cytometry. The data indicate that saturable transport by hOCT2 can be measured by the fluorescent substrates amiloride and ASP and that transport activity for both substrates is regulated similarly. Inhibition of the Ca2+/CaM complex causes changes in transport capacity via hOCT2 trafficking. organic cation transport; fluorescence measurement; 4-[4-(dimethylamino)-styryl]-n-methylpyridinium; amiloride 相似文献
14.
Citores Luca; de Benito Fernando M.; Iglesias Rosario; Ferreras J. Miguel; Jimnez Pilar; Argeso Pablo; Farias Gustavo; Mndez Enrique; Girbs Toms 《Journal of experimental botany》1996,47(10):1577-1585
Sambucus (Caprifoliaceae) species contain nigrin b and ebulinI, which are two-chain ribosomeinactivating proteins (RIPs)belonging to a new type of RIPS which are non-toxic to miceand cultured human cells. In this work the presence in fruitsof elder (S. nigra L.) of a new non-toxic type 2 RIP (nigrinf) that co-exists with a lectin known as SNA IV is described.Nigrin f strongly inhibited protein synthesis in mammalian,but not in plant, ribosomes, promoting the depurination of sensitiveribosomes and thus allowing the release of the RIP diagnosticRNA fragment. Nigrin f is composed of two dissimilar subunitslinked by disulphide bridges with apparent Mr values of 31 600and 26 300. The N-terminal amino acid sequence revealed closehomology of the catalytic A chain with type 1 RIPs, especiallythose from Cucurbitaceae, and the B chain with several lectinspreviously isolated from Sambucus species. Nigrin f was nottoxic to mice when injected intraperitoneally up to 2 mg kg1.In addition, NHC human cells were also insensitive to nigrinf up to 60 µg ml1. Anti-nigrin b rabbit polyclonalantibodies reacted with nigrin f, indicating that nigrin b andnigrin f are proteins with similar structures. Key words: Sambucus nigra, elder fruits, nigrin f, ribosomeinactivating protein, characterization 相似文献
15.
Enhanced suicidal death of erythrocytes from gene-targeted mice lacking the Cl-/HCO(3)(-) exchanger AE1 总被引:2,自引:0,他引:2
Akel A Wagner CA Kovacikova J Kasinathan RS Kiedaisch V Koka S Alper SL Bernhardt I Wieder T Huber SM Lang F 《American journal of physiology. Cell physiology》2007,292(5):C1759-C1767
Genetic defects of anion exchanger 1 (AE1) may lead to spherocytic erythrocyte morphology, severe hemolytic anemia, and/or cation leak. In normal erythrocytes, osmotic shock, Cl removal, and energy depletion activate Ca2+-permeable cation channels with Ca2+-induced suicidal erythrocyte death, i.e., surface exposure of phosphatidylserine, cell shrinkage, and membrane blebbing, all features typical for apoptosis of nucleated cells. The present experiments explored whether AE1 deficiency favors suicidal erythrocyte death. Peripheral blood erythrocyte numbers were significantly smaller in gene-targeted mice lacking AE1 (AE1/ mice) than in their wild-type littermates (AE1+/+ mice) despite increased percentages of reticulocytes (AE1/: 49%, AE1+/+: 2%), an indicator of enhanced erythropoiesis. Annexin binding, reflecting phosphatidylserine exposure, was significantly larger in AE1/erythrocytes/reticulocytes (10%) than in AE1+/+ erythrocytes (1%). Osmotic shock (addition of 400 mM sucrose), Cl removal (replacement with gluconate), or energy depletion (removal of glucose) led to significantly stronger annexin binding in AE1/ erythrocytes/reticulocytes than in AE1+/+ erythrocytes. The increase of annexin binding following exposure to the Ca2+ ionophore ionomycin (1 µM) was, however, similar in AE1/ and in AE1+/+ erythrocytes. Fluo3 fluorescence revealed markedly increased cytosolic Ca2+ permeability in AE1/ erythrocytes/reticulocytes. Clearance of carboxyfluorescein diacetate succinimidyl ester-labeled erythrocytes/reticulocytes from circulating blood was more rapid in AE1/ mice than in AE1+/+ mice and was accelerated by ionomycin treatment in both genotypes. In conclusion, lack of AE1 is associated with enhanced Ca2+ entry and subsequent scrambling of cell membrane phospholipids. annexin; cell volume; osmolarity; phosphatidylserine; energy depletion 相似文献
16.
The calabrese cultivar Brassica oleracea var. italica cv. GreenComet was used in a study of the effects of exogenous hormoneson the growth and differentiation of seedling organs in vitro.Four types of explants were tested: hypocotyl segments, rootsegments, primary leaf discs and cotyledon discs. These explantswere incubated on media containing factorial combinations ofBAP x IBA, BAP x NAA, KN x IBA and KN x NAA (all at 0, 0.1,10 and 10.0mg l1). Hypocotyls were the most regenerativeexplants; shoot production was favoured by cytokinin: auxinratios greater than one and was decreased by IBA at 10 mg l1when callus was produced. Shoot formation from root explantsoccurred either in the absence of hormones or with low concentrations;no shoot was produced when any hormone was present at 10 mgl1. In contrast, shoot production from primary leaf diseswas favoured by high concentrations of both auxin and cytokininwith the combination of BAP and IBA the most effective. Shootproduction from cotyledon discs was sporadic with no consistentresponse on any auxin/cytokinin combination. After further experimentson the optimization of hormone concentration, the followingcombinations were chosen as allowing reliable regeneration:0.1 mg l1 BAP+0.1mg l1 IBA for hypocotyl segments,0.075 mg l1 KN +0.025 mg l1 IBA for root segments,and 5.0 mg l1 BAP+5.0 mg l1 IBA for leaf discs. Brassica oleracea var. italica, calabrese, tissue culture, seedling, auxin, cytokinin 相似文献
17.
The authors regret that in this Mini Review a paper by Massanet al. (1990) (J. Immunol., 144, 46284632) was citedout of context. In this paper isolates of HIV-1 from peripheralblood mononuclear cells of seropositive individuals (and notmolecular clones as cited) were investigated for their macrophagetropism in vitro. 相似文献
18.
Background and Aims Neotyphodium lolii is a fungal endophyteof perennial ryegrass (Lolium perenne), improving grass fitnessthrough production of bioactive alkaloids. Neotyphodium speciescan also affect growth and physiology of their host grasses(family Poaceae, sub-family Pooideae), but little is known aboutthe mechanisms. This study examined the effect of N. lolii onnet photosynthesis (Pn) and growth rates in ryegrass genotypesdiffering in endophyte concentration in all leaf tissues. Methods Plants from two ryegrass genotypes, Nui D andNui UIV, infected with N. lolii (E+) differing approx. 2-foldin endophyte concentration or uninfected clones thereof (E)were grown in a controlled environment. For each genotype xendophyte treatment, plant growth rates were assessed as tilleringand leaf extension rates, and the light response of Pn, darkrespiration and transpiration measured in leaves of young (3045d old) and old (>90 d old) plants with a single-chamber openinfrared gas-exchange system. Key Results Neotyphodium lolii affected CO2-limited ratesof Pn, which were approx. 17 % lower in E+ than E plants(P < 0·05) in the young plants. Apparent photon yieldand dark respiration were unaffected by the endophyte (P >0·05). Neotyphodium lolii also decreased transpiration(P < 0·05), but only in complete darkness. There wereno endophyte effects on Pn in the old plants (P > 0·05).E+ plants grew faster immediately after replanting (P < 0·05),but had approx. 10 % lower growth rates during mid-log growth(P < 0·05) than E plants, but there was noeffect on final plant biomass (P > 0·05). The endophyteeffects on Pn and growth tended to be more pronounced in NuiUIV, despite having a lower endophyte concentration than NuiD. Conclusions Neotyphodium lolii affects CO2 fixation,but not light interception and photochemistry of Pn. The impactof N. lolii on plant growth and photosynthesis is independentof endophyte concentration in the plant, suggesting that theendophyte mycelium is not simply an energy drain to the plant.However, the endophyte effects on Pn and plant growth are stronglydependent on the plant growth phase. 相似文献
19.
Spaak Piet; Denk Angelika; Boersma Maarten; Weider Lawrence J. 《Journal of plankton research》2004,26(6):625-635
Evidence for extensive interspecific hybridization among speciesof the genus Daphnia has been accumulating on a global scale.Although there is evidence for limited gene flow between taxavia hybridization, many species still maintain discrete morphologicaland molecular characteristics. We studied temporal and spatialpatterns of sexual reproduction within the Daphnia galeatahyalinacucullatahybrid species complex in a lake (Plußsee), located innorthern Germany. Allozyme electrophoresis allowed us to trackseasonal changes in taxon composition as well as the quantificationof back-crosses. Sexually-reproducing animals (ephippial femalesand males) were mainly found in autumn. The simultaneous presenceof sexual morphs of D. galeata and D. galeata x hyalina withthe dominant D. hyalina taxa makes recent hybridization, aswell as back-crossing, plausible. Males and ephippial femalesof D. hyalina were not back-crossed as were the parthenogeneticfemales. The low number of sexual clones of the hybrid D. galeatax hyalina might reflect its reduced fertility, although thesefew clones were detected in high densities. Only hybrid-clonesthat had a back-cross genotype (towards D. hyalina) exhibitedephippial females and males. This indicates that male and ephippialfemale production within the Daphnia taxa is not random, whichmight increase the chance for the parental Daphnia species toremain distinct. 相似文献
20.
In the decussate plants Alternanthera philoxeroides and Hygrophilasp. the opposite axillary bud primordia are of unequal sizefrom the time of their inception; the larger or + buds lie alongone helix and the smaller or buds along another (helicoidalsystem). In decapitated plants of Alternanthera both buds grewout, but unequally; if the node was vertically split growthof the two shoots was more equal, and if the + buds were excisedgrowth of the shoots approximately equalled that ofcontrol + shoots. In decapitated shoots of Hygrophila grownin sterile culture only one bud, the + or larger one, grew outat each of the upper nodes. In excised cultured nodes, also,only the + bud grew out; but if the nodes were split longitudinallyboth buds grew out, initially rather unequally. These experimentssupport the view that the regulation of branching in these specieshas two components, apical dominance and the dominance of thelarger (+) bud over the smaller () bud at the same node.The restriction of growth potentiality imposed on the bud is not permanent but can be modified. Further correlativeeffects on bud outgrowth include those of the subtending leavesand of buds at other nodes. 相似文献