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1.
Pollen released at 1100 h has the highest viability (92.2%)but is no longer viable 3 d (84 h) after anthesis.In vitropollen-tubegrowth is fast (140 µm h-1) and increases significantlywithin the first 8 h.In vivopollen tubes also grow quickly andreach the base of the style within 2 h after pollination andenter the micropyle 8 h after pollination. There is no significantdifference between self- and cross-pollination in either therate and the number of pollen tubes in the pistil and the numberof ovules penetrated by a pollen tube. Teak has late-actinggametophytic self-incompatibility; the majority of pollen tubesgrow through the style but some do not continue to grow fromthe style towards the embryo sacs. Pollen-tube abnormalitiesinclude swollen, reversed, forked and tapered tips and irregularand spiralling tubes. These are most prevalent in self-pollination(20.4%). The index of self-incompatibility of 0.17 and low fruitset following self-pollination (2.49%) indicates that teak ismostly self-incompatible. Drastic fruit abortion occurs withinthe first week following controlled pollination. Within 14 d,fruit size and fruit set from cross-pollination is generallymuch greater than from self-pollination. Tectona grandis; pollen viability; pollen-tube growth; pollination; controlled pollinations; incompatibility. 相似文献
2.
The mechanism of self incompatibility in pistils of Lilium longiflorum Thunb. cv. Hinomoto, which is overcome by heat treatment, was analyzed. Immersing detached pistils in a distilled water bath
held at 45°C for 5 min suppressed levels of ethylene and activities of 1-aminocyclopropane-1-carboxylate (ACC) oxidase at
6 h after self- and cross-incompatible pollination. However, the levels and activities showed no significant difference 48
h after pollination. Levels of ACC and activities of ACC synthase at 6 h after self-incompatible pollination were lower in
pistils with heat treatment. Moreover, the heat treatment suppressed the activity of superoxide dismutase and enhanced the
activity of catalase, ascorbate peroxidase, dehydroascorbate reductase, and glutathione reductase. In addition, the amount
of hydrogen peroxide (H2O2) was reduced by heat treatment. In summary, heat treatment suppressed the ethylene-forming system and also enhanced the hydrogen
peroxide-scavenging system in self-pollinated pistils associated with self incompatibility. A possible correlation between
self incompatibility and stress in pistils after self-incompatible pollination is discussed based on the results obtained
using heated pistils.
Received: 12 April 2000 / Revision accepted: 19 September 2000 相似文献
3.
The elongation of pollen tubes in Lilium longiflorum cv. Hinomoto after self-incompatible pollination stopped halfway, but that after cross-compatible pollination (cross with cv. Georgia) did not. The elongation of pollen tubes after self-pollination was enhanced by exogenous cAMP and by pertussis toxin or cholera toxin, which activates adenylate cyclase. The level of endogenous cAMP in pistils after self-pollination was approximately one half of that after cross-pollination. Furthermore, the activity of adenylate cyclase in pistils after self-pollination was also approximately one half of that after cross-pollination. By contrast, cAMP phosphodiesterase in pistils after self-pollination was approximately 2 times as high as that after cross-pollination. A possible correlation between self-incompatibility and the low level of endogenous cAMP in lily pistils is discussed on the basis of these results. 相似文献
4.
Elongation of pollen tubes in pistils of Lilium longiflorum cv. Hinomoto after self-incompatible pollination was here found to be promoted by acetylcholine (ACh) and other choline derivatives, such as acetylthiocholine, l-alpha-phosphatidylcholine and chlorocholinechloride [CCC; (2-chloroethyl) trimethyl ammonium chloride]. Moreover, the elongation was promoted by neostigmine, a potent inhibitor of acetylcholinesterase (AChE; acetylcholine-decomposing enzyme) (EC 3.1.1.7.) and activities of this and choline acetyltransferase (ChAT; acetylcholine-forming enzyme) (EC 2.3.1.6.) in pistils were associated with self-incompatibility. The activity of ChAT was lower after self-incompatible as compared with cross-compatible pollination. Application of cAMP promoted ChAT activities in both cases, whereas activity of AChE in pistils after self-pollination was higher than that after cross-compatible pollination and was suppressed by cAMP in both cases. Furthermore, AChE activity was inhibited by treatment with neostigmine or heating. Our results indicate that the self-incompatibility with self-pollination is due to decrease of ACh and cAMP, causing reduction of ChAT and AC (adenylate cyclase) and concise elevation of AChE and PDE (cAMP phosphodiesterase), and therefore suppressed growth of pollen tubes. 相似文献
5.
Overcoming Self-incompatibility through the Use of Lectins and Sugars in Petunia and Eruca 总被引:1,自引:0,他引:1
Treatment of stigma with a lectin (Con A/PHA) before pollinationwas effective in overcoming self-incompatibility in Petuniahybrida, a gametophytic self-incompatible system, and Erucasativa, a sporophytic self-incompatible system. Treatment ofpollen with glucose/N-acetyl-D-galactosamine (tested only withPetunia) was also effective. These results suggest the involvementof pollen lectins and specific sugar components of the pistilin self-incompatibility recognition. Petunia hybrida, Eruca sativa, self-incompatibility, pollen recognition, lectins 相似文献
6.
Biehler Klaus; Haupt Silke; Beckmann Jrn; Fock Heinrich; Becker Thomas W. 《Journal of experimental botany》1997,48(7):1439-1449
The CO2-, H2O- and 16O2/18O2 isotopic-gas exchange and the fluorescencequenching by attached leaves of the wild-type and of the phytochrome-deficienttomato aurea mutant was compared in relation to water stressand the photon fluence rate. The chlorophyll content of aurealeaves was reduced and the ultra-structure of the chloroplastswas altered. Nevertheless, the maximum rate of net CO2 uptakein air by the yellow-green leaves of the aurea mutant was similarto that by the dark-green wild-type leaves. However, less O2was produced by the leaves of the aurea mutant than by leavesof the wild-type. This result indicates a reduced rate of photosyntheticelectron flux in aurea mutant leaves. No difference in bothphotochemical and non-photochemical fluorescence quenching wasfound between wild-type and aurea mutant leaves. Water stresswas correlated with a reversible decrease in the rates of bothnet CO2 uptake and transpiration by wild-type and aurea mutantleaves. The rate of gross 16O2 evolution by both wild-type andaurea mutant leaves was fairly unaffected by water stress. Thisresult shows that in both wild-type and aurea leaves, the photochemicalprocesses are highly resistant to water stress. The rate ofgross 18O2 uptake by wild-type leaves increased during waterstress when the photon fluence rate was high. Under the sameconditions, the rate of gross 18O2 uptake by aurea mutant leavesremained unchanged. The physiological significane of this differencewith respect to the (presumed) importance of oxygen reductionin photoprotection is discussed. Key words: Water stress, gas exchange, fluorescence quenching, Lycopersicon esculentum, mutant (tomato, aurea), energy dissipation 相似文献
7.
Elongation of pollen tubes in pistils after self-pollination of Lilium longiflorum cv. Hinomoto exhibiting strong gametophytic self-incompatibility was promoted by cAMP and also promoted by some metabolic modulators, namely, activators (forskolin and cholera toxin) of adenylate cyclase and inhibitors (3-isobutyl-1-methylxanthine and pertussis) of cyclic nucleotide phosphodiesterase. Moreover, the elongation was promoted by acetylcholine (ACh) and other choline derivatives, such as acetylthiocholine, L-α-phosphatidylcholine and chlorocholinechloride [CCC; (2-chloroethyl) trimethyl ammonium chloride]. A potent inhibitor (neostigmine) of acetylcholinesterase (AChE) as well as acetylcholine also promoted the elongation. cAMP enhanced choline acetyltransferase (ChAT) activity and suppressed AChE activity in the pistils, suggesting that the results are closely correlated with self-incompatibility in L. longiflorum. In short, it came to light that cAMP modulates ChAT (acetylcholine-forming enzyme) and AChE (acetylchoine-decomposing enzyme) activities to enhance the level of ACh in the pistils of L. logiflorum after self-incompatible pollination. These results indicate that the self-incompatibility on self-pollination is caused by low levels of ACh and/or cAMP.Key Words: pollen tubes, self-incompatibility, Lilium longiflorum, cAMP, acetylcholie, AChE, ChATCyclic AMP (cAMP) is an essential signaling molecule in both prokaryotes and eukaryotes.1 The existence of cAMP in higher plants was questioned by some reviewers2–4 in the mid 1970''s, so that many workers were discouraged from studying roles in plant biology. However, its presence was confirmed by mass spectrometry5 and infrared spectrometry6 in the early 1980''s and increasing evidence7–12 now suggests that cAMP makes important contributions in plant cells, as in animals.Lily (Lilium longiflorum) exhibits strong gametophytic self-incompatibility.13,14 Thus, elongation of pollen tubes in the pistil after self-incompatible pollination in L. longiflorum cv. Hinomoto stops halfway, in contrast to the case after cross-compatible pollination (cross with cv. Georgia).14 This self-incompatibility appears to be associated with the stress and self-incompatible pollination on stigmas of lilies results in activation and/or induction of enzymes such as NADH- and NADPH-dependent oxidases, xanthine oxidase, superoxide dismutase (SOD), catalase and ascorbate peroxidase in the pistils.15 The activities of NADH- and NADPH-dependent oxidases (O2−-forming enzymes), however, are known to be suppressed by cAMP16 and increase in the level of cAMP in guinea pig neutrophils results in their decreased expression.17 The level of O2− reactions with SOD is also decreased by cAMP.18 In the case of the lily, inhibition of NADH- and NADPH-dependent oxidases by cAMP was found to be noncompetitive with NAD(P)H.16 We hypothesized that decrease in active oxygen species such as O2− and suppression of stress enzyme activities in self-pollinated pistils of lily by cAMP might cause elongation of pollen tubes after self-pollination and this proved to be the case. Namely, elongation of pollen tubes after self-incompatible pollination in lily was promoted by exogenous cAMP at a concentration as low as 10 nM, a conceivable physiological level.13 Moreover, similar elongation could be achieved with adenylate cyclase activators [forskolin(FK) and cholera toxin] and cAMP phosphodiesterase inhibitors [3-isobutyl-1-methylxanthine (IBMX) and pertussis toxin].14,19 These phenomena led us to examine the involvement of endogenous cAMP in pistils after self-incompatible or cross-compatible pollination. As expected, the level of endogenous cAMP in pistils after self-pollination was approximately one half of that after cross-pollination. Furthermore, this was associated with a concomitant decrease in adenylate cyclase and increase in cAMP phosphodiesterase.19Many researchers in the field of plant biology have been unsuccessful in attempts to estimate the quantity of cAMP and to detect activities of adenylate cyclase and cAMP phosphodiesterase. On major difficulty is the presence of proteases and we have overcome this problem by using protease inhibitors, such as aprotinin and leupeptin.19In 1947, acetylcholine (ACh) of higher plants was first reported in a nettle (Urtica urens) found in the Himalaya mountain range.20 In 1983, its existence in plants was confirmed by mass spectrometry of preparations from Vigna seedlings.21 In our preliminary studies, CCC (chlorocholinechloride), a plant growth retardant (specifically an anti-gibberellin), enhanced the elongation of the pollen tubes in pistils after self-incompatible pollination in lilies. This led us to investigate whether other choline derivatives cause similar effects and positive findings were obtained with ACh, acetylthiocholine and L-α-phosphatidlylcholine.22 Moreover, the elongation was also promoted by neostigmine, an inhibitor of acetylcholine esterase (AChE) activity. In line with these results, choline acetyltransferase (ChAT) demonstrated low and AChE high activity in pistils after self-incompatible pollination.The positive influence of cAMP14,19 and ACh22 in pistils of L. longiflorum after self-incompatible pollination encouraged us to examine the involvement of these two molecules in regulation of pollen tube elongation of lily after self-incompatible and cross-compatible pollination. As a result, it was revealed that cAMP promotes ChAT and suppresses AChE activity in pistils after both self- and cross-pollination. In other words, the self-incompatibilty in pistils of L. longiflorum appears to be due to levels of ACh and/or cAMP below certain threshold values.Hitherto, these substances have not been recognized to play important roles in the metabolic systems of higher plants. However, given their conservation through evolution, it is natural that such central metabolic substances make essential contributions, regardless of the organism. We have succeeded in establishing physiological functions of cAMP and ACh in pistils of lily14,19,22 and this points to use of plant reproductive organs such as research materials. The exact responsibilities of the two molecules may depend on differences in tissues or organs of plants and further molecular biological studies in this area are clearly warranted. This issue is currently being investigated. 相似文献
8.
L. V. Kovaleva G. V. Timofeeva E. V. Zakharova A. S. Voronkov V. Yu. Rakitin 《Russian Journal of Plant Physiology》2011,58(3):402-408
In the pollen-pistil system of petunia (Petunia hybrida L.) self-compatible and self-incompatible clones within 7 h after self-pollination, we determined the content of ACC (1-aminocyclopropane-1-carboxylic
acid), the activity of two enzymes (ACC synthase and ACC oxidase), and the rate of ethylene production. Depending on the type
of pollination, germination of pollen on the stigma surface and the pollen tube growth in the tissues of style were accompanied
by different levels of ACC and ethylene release. The pollen-pistil system of the self-compatible clone contained twice more
ACC than in the self-incompatible clone, whereas the pollen-pistil system in the self-incompatible clone produced 4–5 times
more ethylene than in the self-compatible clone. For both types of pollination, ACC and ethylene were predominantly produced
in the stigma tissues. The rate of ethylene production therein was 50 times greater than in the styles and ovaries, and the
content of ACC was 100 times higher than in the styles and ovaries. Germination of male gametophyte after both types of pollination
was accompanied by elevated ACC synthase activity (especially in the case of compatible pollination), whereas notable increase
in ACC oxidase activity was manifested in growing pollen tubes after self-incompatible pollination 相似文献
9.
研究了活性氧在UV-B(280~320 nm)诱导的玉米(Zea mays)幼苗叶片乙烯合成中的作用。结果表明,UV-B促进了玉米幼苗活性氧和乙烯的产生;乙 烯合成抑制剂氨氧乙烯基甘氨酸 (AVG)和氨氧乙酸(AOA)能明显减弱UV-B对玉米幼苗乙烯产生的诱导作用,但对活性氧(ROS)的 产生没有明显影 响;ROS的清除剂不但能抑制UV-B诱导的 ROS的产生,而且还可以抑制UV_B诱导的乙烯的产生,但这种抑制作用可以被外源O2.-的供体所逆转。这 说明,乙烯的积累不能作为UV-B胁迫下ROS的诱导的因素,相反,ROS的积累则导致了乙烯的积累;因此,ROS可能参与了UV-B胁迫诱导的乙烯的产生 。质膜NADPH氧化酶的抑制剂二苯碘鎓(DPI)和H2O2的特异性清除剂过氧化氢酶(CAT)对UV-B胁迫诱导的乙烯积累 几乎没有影响, 这说明H2O2 可能与UV-B诱导的玉米幼苗叶片乙烯的产生无关, 在UV-B诱导的玉米幼苗叶片乙烯的生物合成过程中O2.-起着很重要的作用,相关的O2.-不是由 NADPH氧化酶催化产生的。 相似文献
10.
BARAT GOPAL KRISHNA; HIRATA HIROSHI; KUMAZAWA KIKUO; MITSUI SHINGO 《Plant & cell physiology》1969,10(3):545-553
Distribution of iron-containing oxidases in aging nodal rootsof rice and wheat was studied. Activities of cytochrome c oxidase(1.9.3.1
[EC]
, cytochrome c : O2 oxidoreductase), catalase (1.11.1.6
[EC]
,H2O2: H2O2 oxidoreductase) and peroxidase (1.11.1.7
[EC]
, donor:H2O2 oxidoreductase) in wheat roots were comparatively higherthan were those in rice roots at corresponding stages. Cytochromec oxidase in roots remained active throughout the lives of therice and wheat crops. In rice roots, catalase seemed to playa distinct role around the panicle formation stage. Decay ofcatalase activity took place earlier than did that of peroxidaseand cytochrome c oxidase activities. In wheat roots similarenzyme activity changes were not observed. Data may suggestthat the high activity of iron containing oxidases at the panicleformation stage (I) may be chiefly due to catalase activityin rice roots.
1Paper presented at the 14th Annual Meeting of the Society ofthe Science of Soil and Manure, Japan (1968). (Received November 21, 1968; ) 相似文献
11.
The application of GA3in aqueous solution to leaves or flowersof hermaphrodite cultivars of strawberry, Redgauntlet and Rabunda,prevented growth of the receptacle despite hand pollination.This inhibitory effect occurred only when GA3 was applied priorto anthesis. Although viable pollen was produced and germinatedto grow down the styles of treated plants, no seeds were formed.Receptacle growth failed underneath the unfertilized carpels,but the basal region devoid of carpels enlarged and ripened.The effect of GA3 was the same in vivo and for flowers grownin vitro. ABA and BAP also inhibited growth of pollinated flowersin vitro, but neither substance stimulated growth of the baseof the receptacle. 2-NOA stimulated receptacle growth of pollinatedflowers but did not overcome the inhibitory effect of GA3. Removal of fertile carpels 9 days after pollination preventedfurther receptacle growth. GA3 treatment of the bare receptaclere-started growth but was less effective than 2-NOA. No growth substance treatment induced parthenocarpic developmentin these cultivars when unopened buds were emasculated and culturedwithout pollination, although GA3 induced some swelling of thereceptacle base. Fragaria x ananassa Duch., strawberry fruit set, fruit growth, growth regulators 相似文献
12.
Characterization and Induction of the Activity of 1-Aminocyclopropane-1-Carboxylate Oxidase in the Wounded Mesocarp Tissue of Cucurbita maxima 总被引:4,自引:0,他引:4
Hyodo Hiroshi; Hashimoto Chise; Morozumi Shingo; Hu Wenzhong; Tanaka Kuniaki 《Plant & cell physiology》1993,34(5):667-671
1-Aminocyclopropane-1-carboxylate (ACC) oxidase (ethylene-formingenzyme) was isolated from wounded mesocarp tissue of Cucurbitamaxima (winter squash) fruit, and its enzymatic properties wereinvestigated. The enzyme required Fe2+ and ascorbate for itsactivity as well as ACC and O2 as substrates. The in vitro enzymeactivity was enhanced by CO2. The apparent Km value for ACCwas 175 µM under atmospheric conditions. The enzyme activitywas inhibited by sulfhydryl inhibitors and divalent cationssuch as Co2+, Cu2+, and Zn2+. ACC oxidase activity was induced at a rapid rate by woundingin parallel with an increase in the rate of ethylene production.The exposure of excised discs of mesocarp to 2,5-norbornadiene(NBD),an inhibitor of ethylene action, strongly suppressed inductionof the enzyme, and the application of ethylene significantlyaccelerated the induction of the activity of ACC oxidase inthe wounded mesocarp tissue. These results suggests that endogenousethylene produced in response to wounding may function in promotingthe induction of ACC oxidase. (Received January 13, 1993; Accepted April 15, 1993) 相似文献
13.
N. Leduc G. C. Douglas M. Monnier V. Connolly 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,80(5):657-664
Summary Growth of pollen tubes and seed set were compared after hand pollination in situ and in vitro in two self-incompatible species, Trifolium pratense and Trifolium repens. Adhesion of pollen grains to the stigma was greater in vitro for both species. After cross-pollination, in vitro culture gave a significant increase in the cumulative growth of pollen tubes in pistils of T. pratense compared to in situ conditions. After selfing in T. repens, pollen tube growth was significantly increased by in vitro culture of florets. Seed set after crossing in situ and in vitro was similar for both species. Seed set after selfing in vitro was not increased in T. pratense. Several genotypes of T. repens were classified as very good, good and poor selfers based on their capacity for seed set following selfing in situ. In vitro pollination increased self seed formation by 1.7-, 18.0- and 31.0-fold for each class, respectively. Ovules located nearest to the style were fertilized more often after selfing than after crossing. 相似文献
14.
Role of calreticulin in the sensitivity of myocardiac H9c2 cells to oxidative stress caused by hydrogen peroxide 总被引:5,自引:0,他引:5
Ihara Y Urata Y Goto S Kondo T 《American journal of physiology. Cell physiology》2006,290(1):C208-C221
Calreticulin (CRT), a Ca2+-binding molecular chaperone in the endoplasmic reticulum, plays a vital role in cardiac physiology and pathology. Oxidative stress is a main cause of myocardiac apoptosis in the ischemic heart, but the function of CRT under oxidative stress is not fully understood. In the present study, the effect of overexpression of CRT on susceptibility to apoptosis under oxidative stress was examined using myocardiac H9c2 cells transfected with the CRT gene. Under oxidative stress due to H2O2, the CRT-overexpressing cells were highly susceptible to apoptosis compared with controls. In the overexpressing cells, the levels of cytoplasmic free Ca2+ ([Ca2+]i) were significantly increased by H2O2, whereas in controls, only a slight increase was observed. The H2O2-induced apoptosis was enhanced by the increase in [Ca2+]i caused by thapsigargin in control cells but was suppressed by BAPTA-AM, a cell-permeable Ca2+ chelator in the CRT-overexpressing cells, indicating the importance of the level of [Ca2+]i in the sensitivity to H2O2-induced apoptosis. Suppression of CRT by the introduction of the antisense cDNA of CRT enhanced cytoprotection against oxidative stress compared with controls. Furthermore, we found that the levels of activity of calpain and caspase-12 were elevated through the regulation of [Ca2+]i in the CRT-overexpressing cells treated with H2O2 compared with controls. Thus we conclude that the level of CRT regulates the sensitivity to apoptosis under oxidative stress due to H2O2 through a change in Ca2+ homeostasis and the regulation of the Ca2+-calpain-caspase-12 pathway in myocardiac cells. apoptosis; calcium; endoplasmic reticulum 相似文献
15.
Hydrogen peroxide generated by copper amine oxidase is involved in abscisic acid-induced stomatal closure in Vicia faba 总被引:1,自引:0,他引:1
H2O2 is an essential signal in absicic acid (ABA)-induced stomatalclosure. It can be synthesized by several enzymes in plants.In this study, the roles of copper amine oxidase (CuAO) in H2O2production and stomatal closure were investigated. ExogenousABA stimulated apoplast CuAO activity, increased H2O2 productionand [Ca2+]cyt levels in Vicia faba guard cells, and inducedstomatal closure. These processes were impaired by CuAO inhibitor(s).In the metabolized products of CuAO, only H2O2 could inducestomatal closure. By the analysis of enzyme kinetics and polyaminecontents in leaves, putrescine was regarded as a substrate ofCuAO. Putrescine showed similar effects with ABA on the regulationof H2O2 production, [Ca2+]cyt levels, as well as stomatal closure.The results suggest that CuAO in V. faba guard cells is an essentialenzymatic source for H2O2 production in ABA-induced stomatalclosure via the degradation of putrescine. Calcium messengeris an important intermediate in this process. Key words: Abscisic acid, calcium, copper amine oxidase, hydrogen peroxide, putrescine, stomatal closure, Vicia faba
Received 13 October 2007; Revised 16 December 2007 Accepted 20 December 2007 相似文献
16.
Changes in photosystem stoichiometry in response to shift ofenvironments for cell growth other than light regime were studiedwith the cyanophyte Synechocystis PCC 6714 in relation to thechange induced by light-quality shift. Following two environment-shiftswere examined: the shift of molecular form of inorganic carbonsource for photosynthesis from CO2 to HCO3 (CO2 stress)and the increase in salinity of the medium with NaCl (0.5 M)(Na+ stress). Both CO2 and Na+ stresses induced the increasein PSI abundance resulting in a higher PSI/PSII stoichiometry.CO2 stress was found to elevate simultaneously Cyt c oxidaseactivity (Vmax). The feature was the same as that caused bylight-quality shift from preferential excitation of PSI to PSII(light stress) though the enhancement by either stress was smallerthan that by light stress. Under our experimental conditions,PSI/PSII stoichiometry appeared to increase at a fairly constantrate to the basal level even when the basal level had been differentlydetermined by the light-quality. Enhancing rates for PSI/PSIIstoichiometry and for Cyt c oxidase activity were also similarto each other. Since the two stresses affect the thylakoid electrontransport similarly to the shift of light-quality, we interpretedour results as follows: three environmental stresses, CO2, Na+,and light stresses, cause changes in electron turnover capacityof PSI and Cyt c oxidase under a similar, probably a common,mechanism for monitoring redox state of thylakoid electron transportsystem.
1On leave from Department of Biology, College of Natural Science,Kyngpook National University, Taegu 702-701, Korea.
2Present address: Department of Marine Bioscience, Fukui Pre-fecturalUniversity, Obama, Fukui, 917 Japan. 相似文献
17.
The possible involvement of chemotropic factors influencingpollen tube growth in the style and ovary of Salpiglossis wasstudied. Pollen deposited at the base of excised styles germinatedreadily, with pollen tubes penetrating the transmitting tissueand growing towards the stigma, implying that no chemotropicrequirement exists for pollen tube growth in the style. However,the position and high efficiency of seed set following limited-pollinationof intact pistils would support the involvement of localizedchemotropism operating within the ovary. Chemotropism, limited pollination, fertilization efficiency, Salpiglossis sinuata 相似文献
18.
Large-conductance calcium-activated potassium channel activity is absent in human and mouse neutrophils and is not required for innate immunity 总被引:2,自引:0,他引:2
Essin K Salanova B Kettritz R Sausbier M Luft FC Kraus D Bohn E Autenrieth IB Peschel A Ruth P Gollasch M 《American journal of physiology. Cell physiology》2007,293(1):C45-C54
Large-conductance Ca2+-activated K+ (BK) channels are reported to be essential for NADPH oxidase-dependent microbial killing and innate immunity in leukocytes. Using human peripheral blood and mouse bone marrow neutrophils, pharmacological targeting, and BK channel gene-deficient (BK/) mice, we stimulated NADPH oxidase activity with 12-O-tetradecanoylphorbol-13-acetate (PMA) and performed patch-clamp recordings on isolated neutrophils. Although PMA stimulated NADPH oxidase activity as assessed by O2 and H2O2 production, our patch-clamp experiments failed to show PMA-activated BK channel currents in neutrophils. In our studies, PMA induced slowly activating currents, which were insensitive to the BK channel inhibitor iberiotoxin. Instead, the currents were blocked by Zn2+, which indicates activation of proton channel currents. BK channels are gated by elevated intracellular Ca2+ and membrane depolarization. We did not observe BK channel currents, even during extreme depolarization to +140 mV and after elevation of intracellular Ca2+ by N-formyl-L-methionyl-L-leucyl-phenylalanine. As a control, we examined BK channel currents in cerebral and tibial artery smooth muscle cells, which showed characteristic BK channel current pharmacology. Iberiotoxin did not block killing of Staphylococcus aureus or Candida albicans. Moreover, we addressed the role of BK channels in a systemic S. aureus and Yersinia enterocolitica mouse infection model. After 3 and 5 days of infection, we found no differences in the number of bacteria in spleen and kidney between BK/ and BK+/+ mice. In conclusion, our experiments failed to identify functional BK channels in neutrophils. We therefore conclude that BK channels are not essential for innate immunity. killing assay; reactive oxygen species; BK-deficient mice; mice infection 相似文献
19.
The effects of temperature, light, nutrients and CO2on the gametophyticself-incompatibility response in a clone of Lycopersicon peruvianumhave been quantified using fluorescence microscopy of stylesquashes prepared from detached flowers held under experimentalconditions for 48 h after self pollination. Self-incompatibilitywas significantly weakened by raising the temperature from 15°C to 22 or 25°C, and by incubating flowers withoutan energy source - i.e. in the dark and/or without externallysupplied sucrose. The sucrose effect was not duplicated by equimolarmannitol or a full mineral nutrient solution plus vitamins.CO2 applied at 5% in air for 8 h after pollination had no detectableeffect on pollen tube arrest. Observed weakening effects werenot sufficient for use in production of selfed seed. They indicate,however, that self-incompatibility in this clone of L. peruvianumis a temperature-sensitive, energy-dependent process, and supportthe oppositional model of self-incompatibility in which incompatiblepollen tubes are actively inhibited. Lycopersicon, Solanaceae, carbon dioxide, light, nutrients, self-incompatibility, temperature 相似文献
20.
The pattern of electric signals accompanying compatible and incompatible pollination were studied in pistils of petunia (Petunia hybrida L.) and rape (Brassica napus L). Electric potential was recorded for 4–7 hours with non-polarizable Ag/AgCl electrodes implanted into the ovary and beneath
the sigma. At the end of measurements, pistils were fixed and the growth of pollen tubes was analyzed under a fluorescent
microscope.
Action potentials appeared in both species. In rape the potential dropped by 10 mV for few minutes after pollination regardless
of the compatibility of the cross. In this species, during compatible pollination action potentials with amplitudes of 15–20
mV were recorded up to one hour after pollination. They were followed by a long lasting decrease of the potential by 10 to
50 mV. Contrary, after the self-incompatible pollination, action potentials were rare and of lower amplitudes and the potential
gradually raised in comparison to the initial level. During the first hour after the compatible pollination of Petunia hybrida series of action potentials with amplitudes reaching 10–20 mV were recorded. At the time corresponding to the pollen tubes
entrance to the transmitting tissue of the style, action potentials reaching up to 40 mV were followed by a steady decrease
of the potential. The electric signals traveled along the style with velocity of 25 mm/s. Incompatible pollination in petunia
resulted only in minor oscillation and gradual increase of the potential up to 100 mV in comparison to the initial level.
The present investigation demonstrated that each phase of pollen-stigma recognition events, germination and growth of pollen
tubes within the style have its characteristic pattern of electric changes which was species specific and depended on compatibility
of the cross. 相似文献