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961.
Summary The two flagella ofPoterioochromonas are inserted in an apical platform which is shaped by six long flagellar root fibres. The arrangement and structure of these root fibres are described in detail. One of these fibres is the single nucleating site for cytoplasmic interphase microtubules which extend peripherally down to the cytoplasmic tail. Another fibre proceeds toward the centre of the cell and passes the nucleus but is different in structure, position and function from the striated rhizoplast found in many chrysophycean flagellates which is observed but vestigial inPoterioochromonas.A specific kinetosomal mitochondrion has a threefold attachment to the flagellar root apparatus. The chloroplast is also bound to the root system. It has no stigma, but a special continuation of the periplastidial cisterna is developed instead. Another cisterna extends from the nuclear envelope-dictyosome interspace to the kinetosome of the long flagellum. The functional and taxonomic meanings of these structures and of their mutual arrangement are discussed. It is concluded that the present strain (no. 933-1 a of the Collection of Algal Cultures at the Institute of Plant Physiology, Göttingen) has to be excluded from the genusOchromonas. 相似文献
962.
963.
Distribution of radioactivity in paromomycin ascertained after application of 14C-D-glucose, 14C-D-glucosamine, 14C-2-deoxystreptamine, respectively, 14C-D-ribose is taken as basis for a biosynthesis scheme: While ribose bound in the antibiotic originates from glucose by oxidation and following decarboxylation, glucosamine is formed via fructose-6-phosphate. Paromose I arises from glucosamine, but not the cyclohexan derivative 2-deoxystreptamine, whose biosynthesis pathway is directly branching off glucose. 相似文献
964.
965.
Summary
Atriplex hymenelytra is an evergreen shrub distributed in the hot deserts of parts of Mexico and the southwestern United States. The leaves of the species have a number of characteristics that are adaptive in a hot, dry environment, some of which change seasonally. Steeply angled leaves reduce midday solar interception, yet result in relatively high interception when solar angles are low and vapor pressure deficits are at a minimum. The leaves substantially reduce their absorptance of incident radiation during the hot periods of the year by changing their moisture and hence dissolved salt contents. At these times the light intensity required for saturation of photosynthesis is low and a reduction in the radiation absorbed by the leaves therefore results in a greater water-use efficiency. 相似文献
966.
P. Brönnimann 《Pal?ontologische Zeitschrift》1977,51(1-2):94-101
Favreina tabasensis n. sp., a Crustacean (Decapoda) coprolite with numerous longitudinal canals is described from the Upper Jurassic of the Tabas area, east-central Iran. The same favreine form-species is also recorded and figured from the Neocomian of the Dinarids, Bata, Montenegro, Jugoslavia. Further, a lectotype is proposed forFavreina prusensis (Paréjas) from the Upper Portlandian of the region of Lake Apolyont, Turkey.Favreina montana Elliott from the Albian Qamchuqa formation, Gund-i-Shikavt, Erbil Liwa, northern Iraq, is considered as a nomen dubium non conservandum. 相似文献
967.
The structure of canarione, a new naphthoquinone from the lichens Usnea canariensis and U. hookeri was elucidated by UV, 1H-NMR, 13C-NMR, mass spectrometry, and chemical degradation as 5,8-dihydroxy-2-methyl-4H-naphtho [2,3b]-pyran-4,6,9 (6H, 9H)- trione. 相似文献
968.
969.
Anthocyanin pigments in Callistephus chinensis 总被引:1,自引:0,他引:1
Gert Forkmann 《Phytochemistry》1977,16(2):299-301
Identification of the anthocyanin pigments in the flowers of six genotypes of Callistephus chinensis has confirmed that a series of multiple alleles, R, r′ and r are responsible for the production of delphinidin, cyanidin, and pelargonidin derivatives respectively. However, mixtures of anthocyanidin types were present in all genotypes. In the presence of gene M, mainly 3,5-diglycosides were found; in recessive genotypes (mm) there were only 3-mono-glucosides. Unstable acylated derivatives of these pigments were also present. 相似文献
970.
Quantum Yields for CO(2) Uptake in C(3) and C(4) Plants: Dependence on Temperature, CO(2), and O(2) Concentration 下载免费PDF全文
The quantum yields of C3 and C4 plants from a number of genera and families as well as from ecologically diverse habitats were measured in normal air of 21% O2 and in 2% O2. At 30 C, the quantum yields of C3 plants averaged 0.0524 ± 0.0014 mol CO2/absorbed einstein and 0.0733 ± 0.0008 mol CO2/absorbed einstein under 21 and 2% O2. At 30 C, the quantum yields of C4 plants averaged 0.0534 ± 0.0009 mol CO2/absorbed einstein and 0.0538 ± 0.0011 mol CO2/absorbed einstein under 21 and 2% O2. At 21% O2, the quantum yield of a C3 plant is shown to be strongly dependent on both the intercellular CO2 concentration and leaf temperature. The quantum yield of a C4 plant, which is independent of the intercellular CO2 concentration, is shown to be independent of leaf temperature over the ranges measured. The changes in the quantum yields of C3 plants are due to changes in the O2 inhibition. The evolutionary significance of the CO2 dependence of the quantum yield in C3 plants and the ecological significance of the temperature effects on the quantum yields of C3 and C4 plants are discussed. 相似文献