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101.
Images of chlorophyll-a-fluorescence oscillations were recorded using a camera-based fluorescence imaging system. Oscillations with frequencies around 1 per min were initiated by a transient decrease in light intensity during assimilation at an elevated CO2-concentration. The oscillation was inhomogenously distributed over the leaf. In cells adjacent to minor veins, frequency and damping rate was high, if there was any oscillation. In contrast, the amplitude was highest in cells most distant from phloem elements (maximal distance about 300 m). The appearance of minor veins in oscillation images is explained by a gradient in the metabolic control in the mesophyll between minor veins and by transport of sugar from distant cells to phloem elements. The potential of fluorescence imaging to visualize microscopic source-sink interactions and metabolic domains in the mesophyll is discussed.Abbreviations Pi
inorganic phosphate
- Fru2,6BP
fructose-2,6-bisphosphate
- FBPase
fructose-1,6-bisphosphatase
- SPS
sucrose-phosphate synthetase
- HP
hexosephosphate 相似文献
102.
A new, sand-dwelling, armored dinoflagellate, Roscoffia minor sp. nov., is described from Ishikari beach, Hokkaido, Japan. The dinoflagellate has been collected from sand samples taken both near the water's edge and further upshore (25 m from the water's edge at a depth of 1 m), indicating that it is a true sand-dwelling species. Roscoffia minor is heterotrophic and lacks both a chloroplast and an eye-spot. The cell consists of a flattened cap-shaped epitheca and a large hemispheroidal hypotheca, and it is quite different from cells of the typical armored dinoflagellates. The thecal plate formula is: Po, 3′, la, 5″, 3c, 3s, 5″, 1″″. Its distinct cell shape and the thecal plate arrangement indicate affinity to the monotypic genus Roscoffia. Roscoffia minor is distinguished from Roscoffia capitata, the type species, by its smaller size and the possession of a finger-like apical projection. The thecal arrangement of the epitheca is similar to those of the members of the family Podolampaceae, while the hypothecal arrangement is the same as that of members of the subfamily Diplopsalioideae (family Congruentidiaceae). The organism seems to be positioned somewhere intermediate between these two families, but the family to which this dinoflagellate should be affiliated could not be determined. 相似文献
103.
T. R. Mahalingam S. Vijayalakshmi R. Krishna Prabhu A. Thiruvengadasami Ann Wilber C. K. Mathews K. Radha Shanmugasundaram 《Biological trace element research》1997,57(3):191-206
Blood is one of the widely used specimens for biological trace element research because of its biological significance and
ease of sampling. We have conducted a study of the blood of the Kalpakkam township population for trace and minor elements.
For this purpose, analytical methods have been developed and standardized in our laboratory for the elemental analysis of
blood plasma and red cells. Inductively coupled plasma-mass spectrometry (ICP-MS), a relatively new technique, has been applied
for the analysis of trace elements. Details regarding spectral interference and matrix interference encountered in the analysis
of blood and the methods of correcting them have been discussed. Flame atomic absorption spectrometry (AAS)/atomic emission
spectrometry (AES) has been applied for the determination of minor elements. Precision and accuracy of these methods have
also been discussed. 相似文献
104.
Abstract Ultrastructural and physiological characteristics of the C3-C4 intermediate Neurachne minor S. T. Blake (Poaceae) are compared with those of C3 and C4 relatives, and C3-C4Panicum milioides Nees ex Trin. N. minor consistently exhibits very low CO2 compensation points (τ: 1.0, usually 0.3–0.6 Pa) yet has C3-like δ13C values. CO2 assimilation rates (A) respond like those of C3 plants to a decrease in O2 partial pressure (2 × 104–1.9 × 103 Pa) at ambient CO2 levels, but this response is progressively attenuated until negligible at very low CO2. By contrast, other species of the Neurachneae are clearly either C4 (two spp.) or C3 (seven spp.). For plants grown and measured at different photon flux densities (PFDs), τ for N. minor and P. milioides increases from 0.5 to 1.0, and from 1.0 to 2.1 Pa, respectively, as PFD is decreased from 1860 to 460 μmol m?2s?1. In N. minor, the O2 response of τ is either biphasic as in P. milioides, but much diminished and with a higher transition point, or is very C4-like. As in C4 relatives, inner sheath cells contain numerous chloroplasts. Their walls possess a suberized lamella, which may make them more CO2-tight than bundle sheath cells of P. milioides, contributing to the almost C4-like τ characteristics of N. minor. The biochemical basis of C3-C4 intermediacy is considered. 相似文献
105.
Kirk Hayenga Charles Hedgcoth Mary Harrison Victor K. Lin B. J. Ortwerth 《Molecular and cellular biochemistry》1986,71(1):25-30
Summary Mouse lymphoma cells have three major isoaccepting lysine tRNAs. Two of these isoacceptors, tRNA2
Lys and tRNA4
Lys, were sequenced by rapid gel or chromatogram readout methods. They have the same primary sequence but differ in two modified nucleotides. tRNA4
Lys has an unmodified uridine replacing one dihydrouridine and an unidentified nucleotide, t6A*, replacing t6A. This unidentified nucleotide is not a hypomodified form of t6A. Thus, tRNA4ys is not a simple precursor of tRNA2
Lys. Both tRNAs have an unidentified nucleotide, U**, in the third position of the anticodon. Also, partial sequences of minor homologs of tRNA2
Lys and tRNA4
Lys were obtained. The distinctions between tRNA2
Lys and tRNA4
Lys may be part of significant cellular roles as illustrated by the differential effects of these isoacceptors on the synthesis by lysyl-tRNA synthetase of diadenosine-5,5-P1,P4-tetraphosphate, a putative signal in DNA replication. 相似文献
106.
The amino acid sequences of the major and minor globin chains from DBA/2 mice have been determined. This information is of interest because DBA/2 mice are the strain of origin for most murine erythroleukemia lines. The primary structure of DBA/2 globins agrees completely with that predicted from the coding properties of BALB/c globin genes. This identity does not support a rapid evolutionary divergence in inbred mouse strains, at least at these loci in these strains.This work was supported in part by National Institutes of Health Grants AM26956, HL24908, and AM14923 and by the Department of Energy under Contract DE-AC05-840R21400 with Martin Marietta Systems. The SUNY Buffalo Sequencing Facility was supported by a grant from the James Cummings Foundation and National Institutes of Health Grants RR05400 and RR07066. 相似文献
107.
108.
109.
110.
我院三十年消化系统恶性肿瘤病理统计分析 总被引:1,自引:0,他引:1
目的:了解烟台地区消化系统恶性肿瘤在过去不同年代的流行病学和发病学特点,以期为本地区恶性肿瘤的防治研究工作提供参考价值。方法:通过对烟台毓璜顶医院1971年-2000年经病理确诊的消化系统恶性肿瘤进行统计分析,统计了每十年为一个时间段内的主要发病部位的所有原发性恶性肿瘤,分析不同时间段的各器官恶性肿瘤的构成百分比、发病年龄、男女比例等流行病学特点,并将结果与国内外的统计资料进行比较和分析。结果:三个年代消化系统恶性肿瘤的检出率呈增加趋势,共检出恶性肿瘤8295例。胃癌及大肠癌是消化系统发病率最高的两种恶性肿瘤。结论:消化系统肿瘤高发提示胶东地区居民的食物种类、饮食习惯中存在不利于健康的因素。 相似文献