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41.
ERIK WESTBERG HANS‐HELMUT POPPENDIECK JOACHIM W. KADEREIT 《Biological journal of the Linnean Society. Linnean Society of London》2010,101(3):526-535
Oenanthe conioides is a lower Elbe endemic plant species growing in the freshwater tidal zone around Hamburg (Germany). Its closest relative Oenanthe aquatica is widely distributed in Eurasia and grows in calm and shallow freshwater. The two species differ in habitat requirements but are otherwise sympatrically distributed, suggesting that ecological divergence has to be maintained in the face of gene flow. In the present study, we investigated ecological differentiation and reproductive isolation in these two species. An amplified fragment length polymorphism analysis found clear genetic differentiation between the two species implying reproductive isolation. A reciprocal transplantation experiment including artificial F1 hybrids showed strong selection against immigrants. In the two parental habitats, the non‐native species are less fit than the native species. Hybrids are less fit in the habitat of Oe. aquatica but perform as well as the native species in the habitat of Oe. conioides. We hypothesize that selection against immigrants is the most important component of reproductive isolation between the two species, and that selection against immigrants is the result of exposure to cold and wind in the tidal habitat of Oe. conioides and to herbivory in the habitat of Oe. aquatica. These results are congruent with a role for differential ecological selection in the formation and maintenance of these two species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 526–535. 相似文献
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Photosynthesis of Ivy Leaves (Hedera helix) after Heat Stress I. CO2 -Gas Exchange and Diffusion Resistances 总被引:1,自引:0,他引:1
HELMUT BAUER 《Physiologia plantarum》1978,44(4):400-406
For an analysis of the inhibition of the photosynthetic CO2-uptake after heat stress attached leaves of Hedera helix L. were heat-stressed for 30 min at various temperatures. Subsequently their photosynthetic CO2-uptake, transpiration, respiration in light and darkness, and CO2-compensation concentration were measured under optimal conditions. After heat stress the stomatal resistance increased only corresponding to the raised CO2-concentration inside the leaves (due to the reduced CO2-uptake). The physical resistance between the mesophyll cell walls and the chloroplasts remained unchanged after heat stress. A non-stomatal inhibition of the CO2-uptake is indicated by a strong increase of the CO2-compensation concentration after heat stress. This is hardly due to a stimulation of the respiration in light, as the CO2-evolution into CO2-free air in light was even reduced. Therefore, it must be concluded that the photosynthetic process itself is impaired after heat stress. 相似文献
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SCHNABL HEIDE; WEISSENBOCK GOTTFRIED; SCHARF HELMUT 《Journal of experimental botany》1986,37(1):61-72
Cytological observations by fluorescence and U.V.-absorptionmicroscopy together with in vivo spectrophotometric analysesof stomata, guard cell protoplasts and epidermal cells of Viciafaba have shown that kaempferol 3,7-O-glycosides are localizedin the vacuoles. The alkaline-induced emission spectra recordedwith guard and epidermal cells after NH4OH-treatment were identical,exhibiting an emission maximum at 525 nm; the spectra correlatedwith that of reference flavonols after exposure to NH4OH Theexcitation spectra of both cell types are typical of these flavonolsshowing two maxima at 290 nm and 390 nm. In agreement, two absorptionmaxima were recorded for guard cells at 270 nm and 330 nm, withoutalkali, which shifted bathochromically to 275 nm and 380 nm,respectively, after NH4OH treatment. The fluorescence intensitymeasured at 525 nm demonstrates a photostability in epidermalcells whereas it increases by a factor of about five with theexcitation time up to 30 min in guard cells. For the latter,several possible processes are discussed. Key words: Alkaline-induced fluorescence, emission, excitation, U.V.-absorption spectra, kaempferol glycosides, cell specificity 相似文献
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HELMUT J. SCHMIDT 《The Journal of eukaryotic microbiology》1983,30(3):577-580
Immobilization antigens from 12 serotypes of three stocks of Paramecium tetraurelia and from one serotype of one stock of P. primaurelia were isolated and purified. Purified proteins were cleaved with cyanogen bromide, and the patterns of the fragment peptides were determined by electrophoresis on SDS-polyacrylamide gels. It was shown that each of the serotypes of stock 51 of P. tetraurelia has an antigen that produces a characteristic and unique pattern. Consequently, the antigens can be identified by their patterns. Antigens from the allelic serotypes tested had identical patterns. The method is sensitive enough for the investigation of small sample volumes, and useful as a simple biochemical technique for the identification of serotypes. 相似文献
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Light-induced high-amplitude swelling and lipid peroxide formationof isolated spinach chloroplasts were studied with regard tothe supposed analogy to lipid peroxide dependent disintegrationof mitochondria. Addition of glutathione to chloroplasts exposedto light results in excessive stimulation of swelling, whereasthe rate of lipid peroxide accumulation is significantly decreased.In the dark, glutathione does not show any substantial effect.Glutathione apparently serves as a donor substrate for the reductionof lipid peroxides in chloroplasts. The increased water uptakeof chloroplasts in the presence of glutathione cannot be conditionedby peroxidation of membrane lipids, as could be demonstratedfor mitochondria in similar experiments. Evidence is presentedthat a glutathione peroxidase activity is present in spinachhomogenate. The enzyme system, however, behaves quite differentlyfrom glutathione peroxidase of animal sources in respect tostability and pH dependency of the reaction rate (Received October 24, 1970; ) 相似文献
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