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1.
The formation of solid, discrete deposits of opaline silicawithin the cell lumen of leaf tissues is reported in speciesrepresenting three subfamilies of the Gramineae; the preparationof a silica-minimal nutrient solution is discussed. Opal phytolithnumbers are related to tissue age and to two external silicaconcentrations for tiller leaves over a period of 32 days followingbud initiation. Variations in silica deposition patterns among the individualleaves of a homologous series on the shoot apex are relatedto differential growth-rates. During ontogeny, deposition occursin an ordered sequence of cell types related to the basipetalmaturation gradient within the leaf. Initial deposition wasdetected in silica cells (idioblasts) of imbricated, bud leavesof Sieglingia decumbens, 1 mm long; phytoliths are confinedto these cells in expanding, basal portions of the leaf. Phytolithcounts/sq mm of epidermis vary with the degree of long-cellexpansion. The error is reduced by expressing silicificationas the number of phytoliths/100 silica cells. Post-expansiondeposition was initiated in epidermal long cells of the leafblade tip. The higher silica concentration resulted in a morerapid utilization of available deposition sites and larger phytoliths(P = 0.001). A passive cell influx of silicic acid is discussedin relation to cytodifferentiation. 相似文献
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Conditions for tryptophan synthesis from pyruvic acid, indole and NH4Cl by Enterobacter aerogenes AHU 1540 having a high tryptophanase activity, were investigated using a reaction mixture containing 1.7% of pyruvic acid. Under optimum conditions, 16.4g/liter of tryptophan was accumulated after 24 hr of incubation.Agaricus campestris AHU 9382 produced pyruvic acid in amounts of 22 ~ 26.5 g/liter from 5% of glucose after 3-days shaking culture. When E. aerogenes was added to this fermentation broth together with indole and NH4Cl, pyruvic acid produced was rapidly converted to tryptophan and yields of tryptophan as high as 15 g/liter were obtained after 12 hr of incubation. Furthermore, pyruvic acid fermentation by Saccharomyces exiguus AHU 3110 or Corynebacterium sp. 37-3A could also be used as a pyruvic acid source for subsequent tryptophan production. 相似文献
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Alasdair G. Burman 《Brittonia》1982,34(4):458-462
Thrasya oreophila, T. glaziovii, andT. auricoma are described, discussed, and illustrated. 相似文献
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<正>Phyllachora luteomaculata (Schwein.) Orton, J. Dept.Agric. Porto Rico 2: 152, 1918.Fig. 1≡ Sphaeria luteomaculata Schwein., Transactionsof the Amer. Phil. Soc., 相似文献
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The biogenic silica extracted from samples of 28 alpine plantspecies belonging to 23 genera and nine families collected inthe Swiss Alps (Valais) accounted for between 0.01 and 5.9%of the dry biomass of leaves and wood. Silica content, and plantcontribution to the soil biogenic silica pool, varied widelyamong taxa. Plant net productivity and biogenic silica productionfrom this study and from the literature have been used to predictthe input made by different subalpine and alpine plant communitiesto soil-borne phytolith assemblages, and their contributionto the silicon biocycle. Copyright 2001 Annals of Botany Company Silicon, productivity, phytoliths, subalpine, alpine, grasslands, heaths, forests, Gramineae, Cyperaceae, Ericaceae, Coniferae 相似文献
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应用ACGM标记分析禾本科几个物种间的系统发生关系 总被引:3,自引:0,他引:3
为了验证水稻基因组数据的通用性,利用ACGM标记分析了禾本科几个不同种属植物的亲缘关系。选用10份材料,它们分别代表禾本科的5个属(Oryza,Zea, Setaria ,Triticum,和Phyllostachys)。根据遗传距离建立了一个聚类树。这5个属的亲缘关系可以简单地表示为:((Oryza+(Zea+Setaria))+Triticum)+Phyllostachys。研究结果表明,水稻与玉米或水稻与粟之间的遗传距离比水稻和小麦或水稻与竹子之间的遗传距离近。 相似文献
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In this brief paper a new combination Duthiea brachypodlium (P. Candargy) Keng & Keng f. is here
published. Its basionym Triavenopsis brachypodium P. Candargy is found to be left unknown for more than
sixty-five years since its publication in 1897-99. Other synonyms of the genus Duthiea and of this speciesare also given in the present paper. 相似文献
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Anna A. Gorbushina Michael Boettcher Hans-JÜrgen Brumsack Wolfgang E. Krumbein Marius Vendrell-Saz 《Geomicrobiology journal》2013,30(1):117-132
Biogenic physical weathering and leaching of the quartzite dominated table mountain systems of South America is a slow but strongly biologically influenced process. Observations and analyses on the basis of sample materials collected during an expedition to the protected areas of the most conspicuous tepuis of Venezuela are reported. The rock material consists of more than 98% silica, and the waters collected reflect rainwater quality further deprived of some essential elements. Wear-down of these rocks is recognized as a biogeomorphogenetic process ruled by the microbiota surviving under harsh and nutrient-poor conditions. Poikilotrophic subaerial biofilms of cyanobacteria, fungi, and some lichens perforate quartz grains and idiomorphic quartz crystals, as well as the subcrystalline cement. The typical pattern of biopitting is regarded as proof of biogenic quartz destruction. Within the subaerial biofilms, which form a massive cover of the slowly biocorroded rock surface, lichens were found that mineralize to microstromatolitic structures in situ. The mineralization occurs exclusively in the lichen thalli and not in the associated massive biofilms of free-living cyanobacteria and fungi. The minerals deposited were identified as opal and considerable amounts of forsterite, the pure Mg end-member of the olivine mixing series (fayalite being the pure iron silicate). Forsterite, thus far, has been regarded as an igneous mineral phase typical for mantle-derived rocks, highly metamorphic dolomitic marbles, and as a planetary mineral found in meteorites. The biogenic dissolution/mineralization paragenesis is explained by the slow weathering and bioleaching processes dominant on these table mountains and by the exclusion of all other potential biomineralization products due to the peculiar geochemistry of the interstitial and run-off water on these plateaus, thus leading to the exceptional biogenesis of forsterite under surface conditions. 相似文献
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Data on the occurrence of free and conjugated gibberellins in different tribes of Gramineae are compiled and discussed with regard to their biosynthetic pathways. From the gibberellins detected so far the functioning of both the early 13-hydroxylation and the non-3,13-hydroxylation pathway of GA biosynthesis in gramineous plants can be deduced and the discovery of further gibberellin conjugates may be expected. 相似文献
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Joanna Pijanowska 《International Review of Hydrobiology》1992,77(1):153-163
Over a two-year period, each of the three Daphnia species in two lakes with different pressure by fish and invertebrate predators exhibited different defensive reactions: predator avoidance in space (Daphnia hyalina), seasonal morphological changes (Daphnia cucullata), and a combination of both (Daphnia cristata). Body size and general susceptibility to predation, combined with predators' preferences were most likely responsible for the kind of defence in each of the three Daphnia. 相似文献
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锦鸡儿属3种植物的核型研究 总被引:4,自引:0,他引:4
以锦鸡儿属中间锦鸡儿、柠条锦鸡儿、狭叶锦鸡儿为材料,用光学显微镜观察了3种锦鸡儿的染色体,按全国第一次植物染色体学术讨论会建议的标准进行了核型分析。结果表明,3种锦鸡儿的体细胞染色体数目2n=16,核型公式分别为:中间锦鸡儿2n=2x=16=10m 6sm、柠条锦鸡儿2n=2x=16=12m 4sm、狭叶锦鸡儿2n=2x=16=14m 2sm,中间锦鸡儿和柠条锦鸡儿的核型属于2A型,狭叶锦鸡儿的核型属于2B型。狭叶锦鸡儿二倍体染色体核型为首次报道。 相似文献
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桫椤科三种植物配子体发育的研究 总被引:11,自引:0,他引:11
用土壤培养桫椤Alsophila spinulosa(Wall.exHook.)R.M.Tryon、中华桫椤A.costularis Baker和白桫椤Sphaeropteris brunoniana(Hook.)R.M.Tryon的孢子,利用光学显微镜对其配子体发育的各个阶段进行了观察,包括孢子形态及其萌发、原丝体发育特点、片状体和生长点的形成及分化、假根特征、精子器和颈卵器的分化及发育,以及原叶体感染真菌后的显微特征。初步讨论了桫椤科不同属(种)间的配子体发育的系统学意义和有性世代的濒危原因。 相似文献
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Effect of CO2 Concentration Doubling on the Leaf Morphology and Structure of 10 Species in Gramineae
The effects of CO2 concentration on leaf thickness, chloroplast manbers in the bundle sheath cell, epidermal cell density, stomatal density, stomatal index, stomatal size were compared in 10 species in Gramineae: Triticum aestivum L., T. aestivum ssp. tibeticum, Hordeum vulgare L., H. brevisubulatum ( Trin. ) Link, Oryza sativa L., O. meyeriana ssp. granulata, Setaria italica (L.) Beauv, S. viridis (L.) Beauv, Sorghum vulgare Pers., Zea mays L. following their exposure to doubled carbon dioxide (700μL/L) and ambient carbon dioxide concentration (350μL/L). The results indicated that different species of plants might vary in their response to doubled CO2. In general, the leaves became thicker under the elevated CO2 condition. The mean stomatal density of the C3 species was decreased in doubled CO2, whereas the results of C4 species showed an inverse trend. The epidermal cell density and the chloroplast numbers of the bundle sheath cell in the wild plant species were less than those in the control under CO2 enrichment. The stomatal density was positively correlated with the stomatal index. Finally, the general pattern of structural variation under different CO2 concentrations was proposed, and their implication to the research of global change was discussed as well. 相似文献
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C. J. MARCHANT 《Botanical journal of the Linnean Society. Linnean Society of London》1968,60(383):411-417
The chromosome numbers of nine species of the genus Spartina have been determined and their meiotio pairing has been examined. All numbers are referable to either 2 n = 40 ( S. pectinata, S. patens, S. cynosuroides, S. gracilis, S. bakeri and S. arundinacea ), 2 n =60 ( S. maritima ) or 2 n =62 ( S. alternifiora and 8. glabra ). No intraspeoifio polyploids have been found. Supernumerary or B -chromosomes occur rarely in S. pectinata . Hence the basio chromosome number is deduced as being x = 10 for these speoies in contrast to former reports of x = 7. The implications of the new basic number with respect to taxonomic position are pointed out. 相似文献
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The karyotypes of 3 species of Roegneria and 2 species of Kengyilia were
analysed in this paper. They are all reported for the first time, and the karyotype
formulae are as follows: R. nutans, 2n = 4X= 28 = 26m+ 2sm; R. abolinii, 2n = 4X
=28 = 24m + 4sm; R. aristiglumis, 2n = 6X = 42 = 32m + 10sm (2sat); K. tahelacana
2n = 6X = 42 = 36m (2sat)+6sm (2sat); K. zhoasuensis, 2n = 6X= 42 = 34m(4sat)+ 8sm.
According to the characters of karyotypes, K. tahelacana and K. zhoasuensis havethe S, Y, P genomes of genus Kengyilia. 相似文献