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41.
Drought and Oxidative Load in the Leaves of C3 Plants: a Predominant Role for Photorespiration? 总被引:10,自引:0,他引:10
NOCTOR GRAHAM; VELJOVIC-JOVANOVIC SONJA; DRISCOLL SIMON; NOVITSKAYA LARISSA; FOYER CHRISTINE H. 《Annals of botany》2002,89(7):841-850
Although active oxygen species are produced at high rates inboth the chloroplasts and peroxisomes of the leaves of C3 plants,most attention has focused on the potentially damaging consequencesof enhanced chloroplastic production in stress conditions suchas drought. This article attempts to provide quantitative estimatesof the relative contributions of the chloroplast electron transportchain and the glycolate oxidase reaction to the oxidative loadplaced on the photosynthetic leaf cell. Rates of photorespiratoryH2O2 production were obtained from photosynthetic and photorespiratoryflux rates, derived from steady-state leaf gas exchange measurementsat varying irradiance and ambient CO2. Assuming a 10 % allocationof photosynthetic electron flow to the Mehler reaction, photorespiratoryH2O2 production would account for about 70 % of total H2O2 formedat all irradiances measured. When chloroplastic CO2 concentrationrates are decreased, photorespiration becomes even more predominantin H2O2 generation. At the increased flux through photorespirationobserved at lower ambient CO2, the Mehler reaction would haveto account for more than 35 % of the total photosynthetic electronflow in order to match the rate of peroxisomal H2O2 production.The potential signalling role of H2O2 produced in the peroxisomesis emphasized, and it is demonstrated that photorespiratoryH2O2 can perturb the redox states of leaf antioxidant pools.We discuss the interactions between oxidants, antioxidants andredox changes leading to modified gene expression, particularlyin relation to drought, and call attention to the potentialsignificance of photorespiratory H2O2 in signalling and acclimation. 相似文献
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1. Many ectothermic species have evolved the ability to invoke a ‘behavioural fever’ when infected with a pathogen. The relative costs and benefits of this response, however, have rarely been quantified. 2. The aim of this study was investigate the nature and consequences of behavioural fever in the house fly, Musca domestica L., in response to infection with a possible biocontrol agent, the fungal entomopathogen, Beauveria bassiana (Balsamo) Vuillemin. 3. It was found that infected flies preferred higher temperatures and allocated more effort to thermoregulation than uninfected flies. Flies could not overcome infection but the altered thermal behaviour allowed infected flies to extend their survival and to lay more eggs relative to infected flies maintained under constant conditions. However, flies allowed to fever had lower egg viability suggesting a possible cost. 4. Under the present experimental conditions, the putative costs and benefits fever balanced one another resulting in no net change in fitness. Fever did not, therefore, limit the control potential of the fungus. We discuss whether the costs and benefits of behavioural fever might differ in other ecological contexts. 相似文献
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R. W. BULL H. A. LEWIN M. C. WU K. PETERBAUGH D. ANTCZAK D. BERNOCO S. CWIK L. DAM C. DAVIES R. L. DAWKINS J. H. DUFTY J. GERLACH H. C. HINES S. LAZARY W. LEIBOLD H. LEVEZIEL
. LIE P. G. LINDBERG D. MEGGIOLARO E. MEYER R. OLIVER M. ROSS M. SIMON R. L. SPOONER M. J. STEAR A. J. TEALE J. W. TEMPLETON 《Animal genetics》1989,20(2):109-132
Summary. Two hundred and eighty-two alloantisera were submitted by 20 participating laboratories from 13 countries and tested against lymphocytes of 1298 cattle. The cell panel consisted of samples from 38 Bos taurus breeds, 11 Bos taurus crossbreeds, 4 Bos indicus breeds, 6 Bos taurus X Bos indicus , and a variety of other crossbred populations. Using a standardized lymphocytotoxicity test, all 17 previously identified BoLA specificities were confirmed. The workshop produced agreement on 16 new lymphocyte alloantigenic specificities. Three of the new specificities behaved as splits of previously identified BoLA specificities. Four of the new specificities behaved as alleles at the agreed BoLA-A locus. Seven new specificities are tentatively assigned to the BoLA-A locus but require further definition. Two new specificities may represent products of a second closely-linked BoLA locus. 相似文献
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In various fungi (Botrytis cinerea, B. allii, Sclerotinia gladioli,Sclerotiun cepivorum, S. rolfsii, and Rhizoctonia solani) theinitiation of sclerotia, their further development to full sizeand their maturation were three distinct stages with differentnutritional requirements. These processes were followed on peptone-saltsmedia with a variety of carbon sources (carbohydrate or mannitol)ranging in concentration between 0·5 and 3 per cent.The nitrogen nutrition was varied in the presence of 2 per cent.glucose with peptone replaced by asparagine, potassium nitrate,or ammonium salts. All were suitable provided a high aciditydid not develop. Urea was unsatisfactory. Details given includethe rate of sugar utilization in some examples. 相似文献
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ROOT GROWTH AND THE ONSET OF MITOSIS IN GERMINATING VICIA FABA 总被引:1,自引:0,他引:1