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Summary
Lathyrus sylvestris is a pioneer legume often found in disturbed habitats. Mainly reproduced through vegetative propagation, this clonal species presents a system of ramets that remain connected for several years. The existence of carbon transfer among ramets within a clone has been studied using 14C in situ. Assimilate translocation from primary to secondary ramets was observed in all clones when the primary ramet was exposed to 14CO2. The amount of transfer ranged from trace up to 90% of the total 14C incorporated. However, in only half of the clones there was consistent enrichment of the secondary ramet (5 to 89%) suggesting that interramets transfer of carbon may be facultative. Furthermore, when significant export occurred from the primary ramet, it was always principally towards only one ramet even when the clone included more than one. The transfer of 14C from secondary to primary ramets was shown to be significant only when photosynthesis of the latter was decreased by shading. In this case import of carbon was never more than 60% of the incorporated 14C.No correlation was found between age or size of the ramets and the intensity of transfer. The shading effect let suppose that transfers are mainly driven by carbon limitation due to changing environmental conditions and not to the state of ramet maturity. The adaptative advantage of such facultative physiological integration between ramets of a clone is discussed. 相似文献
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A temperature-jump study of the electron transfer reactions in Hansenula anomala flavocytochrome b2 总被引:2,自引:0,他引:2
Temperature-jump experiments on flavocytochrome b2 were carried out at different levels of heme reduction at pH 7.0 and 6.0, and as a function of pyruvate concentration. The relaxation, corresponding to an increase in the concentration of reduced heme, is in no case a simple process. AtpH 7.0 the mean reciprocal relaxation time is 1/tau* = 190 s-1, independent of enzyme concentration, wavelength of observation and percentage of heme reduction. Flavin semiquinone has been identified as the major electron donor to the heme in this process. At the same pH the presence of pyruvate in the millimolar concentration range increases the relaxation rate and affects its amplitude. The latter effect could be accounted for by a change in redox equilibria between heme and flavin upon pyruvate binding. At pH 6.0 the relaxation pattern depends more clearly on the level of heme reduction. A rapid process (tau-1 = 2500 s-1), predominant at high percentages of reduced heme, has been assigned to the reduction of heme by flavin hydroquinone, while the slower process (tau-1 = 350 s-1), essentially the only one present at or below 50% of heme reduction, has been ascribed to the reduction of heme by flavin semiquinone. These results are discussed in relation to the catalytic mechanism of the enzyme. 相似文献
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Variations in genomic DNA methylation during the long-term in vitro proliferation of oil palm embryogenic suspension cultures 总被引:1,自引:0,他引:1
Alain Rival Pascal Ilbert Axel Labeyrie Esperanza Torres Sylvie Doulbeau Aline Personne Stéphane Dussert Thierry Beulé Tristan Durand-Gasselin James W. Tregear Estelle Jaligot 《Plant cell reports》2013,32(3):359-368
Key message
The long-term proliferation of embryogenic cell suspensions of oil palm is associated with changes in both genomic methylation rates and embryogenic capacities.Abstract
In the aim of exploring the relationship between epigenetic stability and the long-term in vitro proliferation of plant tissues, we have studied changes in genomic DNA methylation levels in embryogenic suspensions of oil palm (Elaeis guineensis Jacq.). Five embryogenic callus lines were obtained from selected hybrid seeds and then proliferated as suspension cultures. Each clonal line obtained from a single genotype was subdivided into three independent subclonal lines. Once established, cultures proliferated for 12 months and genomic DNA was sampled at 4 months intervals for the estimation of global DNA methylation rates through high performance liquid chromatography (HPLC) quantitation of deoxynucleosides. Our results show that in vitro proliferation induces DNA hypermethylation in a time-dependent fashion. Moreover, this trend is statistically significant in several clonal lines and shared between subclonal lines originating from the same genotype. Interestingly, the only clonal line undergoing loss of genomic methylation in the course of proliferation has been found unable to generate somatic embryos. We discuss the possible implications of genome-wide DNA methylation changes in proliferating cells with a view to the maintenance of genomic and epigenomic stability. 相似文献5.
Economic Botany - So Close Yet So Different: Cultural Differences among Farmers in Central Kenya Affect Their Knowledge of Sorghum (Sorghum bicolor [L.] Moench) Landrace Identification. Whether... 相似文献
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Mavingui P Van VT Labeyrie E Rancès E Vavre F Simonet P 《Applied and environmental microbiology》2005,71(11):6910-6917
Bacteria belonging to the genus Wolbachia are obligatory microendocytobionts that infect a variety of arthropods and a majority of filarial nematode species, where they induce reproductive alterations or establish a mutualistic symbiosis. Although two whole genome sequences of Wolbachia pipientis, for strain wMel from Drosophila melanogaster and strain wBm from Brugia malayi, have been fully completed and six other genome sequencing projects are ongoing (http://www.genomesonline.org/index.cgi?want=Prokaryotic+Ongoin), genetic analyses of these bacteria are still scarce, mainly due to the inability to cultivate them outside of eukaryotic cells. Usually, a large amount of host tissue (a thousand individuals, or about 10 g) is required in order to purify Wolbachia and extract its DNA, which is often recovered in small amounts and contaminated by host cell DNA, thus hindering genomic studies. In this report, we describe an efficient and reliable procedure to representatively amplify the Wolbachia genome by multiple-displacement amplification from limited infected host tissue (0.2 g or 2 x 10(7) cells). We obtained sufficient amounts (8 to 10 microg) of DNA of suitable quality for genomic studies, and we demonstrated that the amplified DNA contained all of the Wolbachia loci targeted. In addition, our data indicated that the genome of strain wRi, an obligatory endosymbiont of Drosophila simulans, shares a similar overall architecture with its relative strain wMel. 相似文献
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V. Labeyrie 《BioControl》1961,6(4):257-263
Summary The layings ofCassida deflorata
Suffr. are parasited in southern France byMymaridae (Anaphoidea sp. andFulmekiella ovata
soyka),Trichogrammatidae (Monorthochaeta nigra
Blood.) andEulophidae (Foersterella flavipes
Foerst. andTetrastichus rhosaces
Walk.).
In the Alpes-Maritimes, two successive generations ofMymaridae andTrichogrammatidae seem to attack the layings ofC. deflorata.
In Corsica, parasitism byMymaridae andF. flavipes is very frequent and may be the essential regulating factor of the populations ofCassida.
In the other regions that have been studied, although the large number ofCassida imagos appearing in spring show that mortality during the aestivation and hibernation is not the primary factor, it does
not seem that the limitation of the populations is essentially caused by the activity of oophagous insects.
相似文献
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