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RAPHAEL LUGAN MARIE-FRANÇOISE NIOGRET LUCIE KERVAZO FRANÇOIS ROBERT LARHER JOACHIM KOPKA & ALAIN BOUCHEREAU 《Plant, cell & environment》2009,32(2):95-108
Metabolomic investigation of the freezing-tolerant Arabidopsis mutant esk1 revealed large alterations in polar metabolite content in roots and shoots. Stress metabolic markers were found to be among the most significant metabolic markers associated with the mutation, but also compounds related to growth regulation or nutrition. The metabolic phenotype of esk1 was also compared to that of wild type (WT) under various environmental constraints, namely cold, salinity and dehydration. The mutant was shown to express constitutively a subset of metabolic responses which fits with the core of stress metabolic responses in the WT. But remarkably, the most specific metabolic responses to cold acclimation were not phenocopied by esk1 mutation and remained fully inducible in the mutant at low temperature. Under salt stress, esk1 accumulated lower amounts of Na+ in leaves than the WT, and under dehydration stress its metabolic profile and osmotic potential were only slightly impacted. These phenotypes are consistent with the hypothesis of an altered water status in esk1 , which actually exhibited basic lower water content (WC) and transpiration rate (TR) than the WT. Taken together, the results suggest that ESK1 does not function as a specific cold acclimation gene, but could rather be involved in water homeostasis. 相似文献
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'Spicules' in halysitids: a reply 总被引:1,自引:0,他引:1
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JÜRGEN THIELE OTMAR HONER-SCHMID D
JÜRGEN WAHL GERTRUD KLEEFELD JOACHIM SCHULTZ 《The Journal of eukaryotic microbiology》1980,27(1):118-121
SYNOPSIS A method is described for the axenic mass cultivation of Paramecium tetraurelia strains 51s and 299s. the ciliate is grown in an enriched axenic medium developed by Soldo, Godoy & van Wagtendonk. Under continuous shaking on a rotary shaker, cultures were grown in one-liter Erlenmeyer flasks with 330 ml medium yield cell densities of 32,000 cell/ml and 20,000 cells/ml for strains 299s and 51s respectively. Doubling time is considerably shorter under these conditions than in the conventional static cultures. A 20-liter airlift bioreactor is described in detail which can be used successfully to otain up to 100 g wet weight of Paramecium in a single run; in this reactor the cell density reaches 38,000 cells/ml for strain 299s. and 23,000 cells/ml for 51s. This technic should facilitate the study of minor protein components of the ciliate. 相似文献
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JOACHIM RÖSEL RENATE RADEK KLAUS HAUSMANN 《The Journal of eukaryotic microbiology》1996,43(6):505-511
ABSTRACT Stephanonympha nelumbium is a large trichomonad measuring 45–60 μm in length and 20–40 μm in width. It is a member of the multinucleate and multiflagellate family Calonymphidae. While the numerous flagella arise in groups of four at the anterior cell pole, the posterior body portion is covered with attached spirochetes and rod-like bacteria. Generally, in the apical body portion of S. nelumbium , 50–100 nuclei are arranged in five to seven circular rows. Each nucleus is associated with a typical mastigont system, comprised of three anterior flagella, one recurrent flagellum being attached to the cell surface for a certain distance, and several typical root structures. Akaryomastigonts and costas do not occur. The fine structure of S. nelumbium corresponds with that of other calonymphids. The main difference to Calonympha is that the axostyle does not embrace the nucleus but passes it in form of a flattened rod. 相似文献
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JOACHIM MÜLLER UWE MOHR NORBERT SPRENGER KARLHEINZ BORTLIK THOMAS BOLLER & ANDRES WIEMKEN 《The New phytologist》1999,142(3):551-559
The effect of arbuscular mycorrhizas on fructan accumulation was studied in barley ( Hordeum vulgare ) infected with Glomus mosseae . Treatments with and without fertilizer were included in order to distinguish between mere fertilizer effects and the effects of the symbiosis, and plants were harvested at two different time points, 35 and 50 d after planting. Fructan was the major storage carboyhdrate in both leaves and roots. The amounts of fructan were markedly altered in the mycorrhizal plants. In roots of non-fertilized mycorrhizal plants, fructan pools were significantly greater than in the corresponding non-mycorrhizal plants. By contrast, fertilization caused a general decrease in amounts of fructan in roots. The increase of fructan in mycorrhizal roots was correlated with a decrease of invertase activity. In leaves, fructan pools decreased or remained unchanged upon mycorrhizal infection; fertilization had a similar effect. However, when individual leaves of a plant were compared, intriguing effects of the mycorrhizal symbiosis could be observed. Whereas in non-mycorrhizal plants, the youngest leaves had the highest fructan contents and the oldest leaves the lowest (as previously reported), this gradient was markedly altered in mycorrhizal plants, indicating systemic effects of mycorrhiza on assimilate partitioning in shoots. 相似文献
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Daphnia community analysis in shallow Kenyan lakes and ponds using dormant eggs in surface sediments
JOACHIM MERGEAY STEVEN DECLERCK DIRK VERSCHUREN LUC DE MEESTER 《Freshwater Biology》2006,51(3):399-411
1. Water fleas of the genus Daphnia are considered rare in tropical regions, and information on species distribution and community ecology is scarce and anecdotal. This study presents the results of a survey of Daphnia species distribution and community composition in 40 standing waterbodies in southern Kenya. The study sites cover a wide range of tropical standing aquatic habitats, from small ephemeral pools to large permanent lakes between approximately 700 and 2800 m a.s.l. Our analysis combines data on Daphnia distribution and abundance from zooplankton samples and dormant eggs in surface sediments. 2. Nearly 70% (27 of 40) of the sampled waterbodies were inhabited by Daphnia. Although their abundance in the active community was often very low, this high incidence shows that Daphnia can be equally widespread in tropical regions as in temperate regions. 3. Analysis of local species assemblages from dormant eggs in surface sediments was more productive than snapshot sampling of zooplankton communities. Surface‐sediment samples yielded eight Daphnia species in total, and allowed the detection of Daphnia in 25 waterbodies; zooplankton samples revealed the presence of only four Daphnia species in 16 waterbodies. 4. Daphnia barbata, D. laevis, and D. pulex were the most frequently recorded and most abundant Daphnia species. Canonical correspondence analysis of species–environment relationships indicates that variation in the Daphnia community composition of Kenyan waters was best explained by fish presence, temperature, macrophyte cover and altitude. Daphnia barbata and D. pulex tended to co‐occur with each other and with fish. Both species tended to occur in relatively large (>10 ha) and deeper (>2 m) alkaline waters (pH 8.5). Daphnia laevis mainly occurred in cool and clear, macrophyte‐dominated lakes at high altitudes. 相似文献
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JOACHIM W. KADEREIT 《Botanical journal of the Linnean Society. Linnean Society of London》1990,103(3):221-231
KADEREIT, J. W., 1990. Some suggestions on the geographical origin of the central, west and north European synanthropic species of Papaver L . Papaver rhoeas, P. dubium subsp. dubium and subsp. lecoqii, P. argemone subsp. argemone and P. hybridum are considered to be introduced in central, western and northern Europe. An analysis of the geographical distribution of the closest relatives of these five taxa leads to hypotheses on their geographical origin. It is suggested that P. rhoeas originates from the eastern border of the Mediterranean, where it might have differentiated only under human influence. The origin of P. dubium subsp. lecoqii is suggested to lie in S.E. Europe or west Anatolia, and that of subsp. dubium in S.E. central Europe. Papaver argemone subsp. argemone might have differentiated from two related subspecies in west Anatolia. No suggestions can be made with respect to P. hybridum , which is taxonomically isolated. The assumptions necessary for hypotheses on the geographical origin of synanthropically widespread taxa are briefly discussed. 相似文献
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LI-BING ZHANG JOACHIM W. KADEREIT 《Botanical journal of the Linnean Society. Linnean Society of London》2004,146(1):1-26
On the basis of the study of c . 1100 herbarium specimens, field observations and molecular (ITS, AFLPs) evidence, Primula sect . Auricula is classified into two subsections, 25 species and six subspecies. Primula auricula L. ssp. widmerae (Pax) L. B. Zhang stat. nov. , P. auricula Linn. ssp. tatriaca L. B. Zhang ssp. nov. , and P. latifolia Lapeyr. ssp. cynoglossifolia (Widmer) L. B. Zhang stat. nov. are newly described or combined; P. auricula s.l. is divided into two species: P. auricula Linn. and P. balbisii Lehm., representing the northern and the southern populations of P. auricula s.l. resolved in the molecular study, respectively; P. cottia Widmer and P. balbisii Lehm. are recovered from synonymy; P. grignensis D. M. Moser and P. pedemontana E. Thomas ex. Gaudin ssp. iberica Losa et P. Monts. are synonymized with P. hirsuta All. and P. pedemontana , respectively; P. clusiana is postulated to be an allopolyploid species. Phylogenetic relationships in the section are discussed based on morphological and molecular variation and geographical distribution. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 1–26. 相似文献