Directional cell-to-cell communication in theArabidopsis root apical meristem I. An ultrastructural and functional analysis

Summary As a foundation for studies on directional intercellular communication and its regulation in apical development, the network of plasmodesmata inArabidopsis root apical meristems was characterized by quantitative electron microscopy and dye-coupling analysis, using symplasmic probes, and real-time imaging in confocal laser scanning microscopy. A tissue-specific plasmodesmatal network, which interconnected the cells in the root apical meristem, was characterized by the following features, (a) Plasmodesmatal distribution and density were found to be tissue-specific, (b) Primary and secondary plasmodesmata were differentially grouped and regulated. Primary plasmodesmata were formed in large numbers in the transverse walls of each tissue, and were subject to deletion during cell differentiation. Secondary plasmodesmata were mostly distributed in longitudinal walls between cell files and common walls between neighboring tissues; they also provided a symplasmic path between different initial tiers in the meristem. Small fluorescent tracers moved through the plasmodesmatal network of the root apical meristem in two distinct phases. At low concentrations molecules trafficked in a non-tissue-specific manner, whereas at higher concentrations, their distribution reflected the presence of tissue-specific movement consistent with plasmodesmatal distribution. These findings are discussed in terms of the role of tissue-specific plasmodesmatal domains in the control of root development.     

Effects of impoundment on populations of bullhead Cottus gobio L. and minnow, Phoxinus phoxinus (L.), in the basin of Cow Green Reservoir

The distribution, growth and reproduction of bullhead, Cottus gobio , L., and minnow, Phoxinus phoxinus (L.), were studied at Cow Green Reservoir, Upper Teesdale, for 10 years following impoundment in 1970. Comparisons were made with pre-impoundment results. The length-for-age of bullheads increased after impoundment. The length-for-age of minnows decreased. In winter both species were confined mainly to deep water or to the stone facing of the earth dam. In summer they were found throughout the reservoir though bullheads were scarce in the littoral zone. Female bullheads became sexually mature at an earlier age (84% at age-group I) than before impoundment (33% at age-group I) but no change was apparent amongst males (67–62% in age-group I). The post-impoundment sex ratio did not differ from 1:1 and individual fecundity did not change after impoundment. There was a significant reduction in individual fecundity of the minnow. The mean instantaneous rate of mortality ( Z ) for bullhead of age-groups II to IV was 0.96 ± 0.34 year⁻¹, compared with 0.85 ± 0.29 year in the Tees before impoundment.     

关于低强度激光疗法的机理及其临床应用研究

刘承宜等人提出了低强度激光疗法的生物信息模型。根据ＢＩＭＬ,绿,兰和紫等冷色兴奋Ｇａ蛋白介导的生理过程,红,产黄等暖色兴奋Ｇｑ或Ｇｉ蛋白或受体关联蛋白酶介导的生理过程。本文将激光的生物效应分为直接效应和间接效应两类,根据ＢＩＭＬ成功地解释了已知第二信使生理功能的系统的低强度激光照射的作用机理和临床应用,可望用于开发低强度激光疗法的临床新应用。     

氦氖激光辐射提高种蛋孵化率的研究

本实验采用新技术激光辐射种蛋。结果表明,一定剂量的激光能显著提高种蛋的孵化率（６．６８％￣１３．２６％）,雏鸡的体重和生活力;同时还对激光的作用机理作了初步探讨。     

XeCl准分子激光消融几种生物组织的实验结果

本文报道了３０８ｎｍＸｅＣｌ准分子激光对人牙硬组织和猪肉软组织消融的实验研究结果,在国内首次开展了ＸｅＣｌ准分子激光牙科应用的基础研究,为准分子激光在牙科的临床应用提供了实验依据。     

激光辐照玉米诱发同工酶及染色体变异的研究

利用ＣＯ２激光辐照玉米种子,分析了酯酶同工酶（ＥＳＴ）和过氧化物酶同工酶（ＰＯＤ）及根尖细胞染色体变异,探讨了苗期损伤与染色体和同工酶变异的关系。结果表明：ＣＯ２激光辐照可诱发ＥＳＴ和ＰＯＤ活性和种类的变化,ＥＳＴ３和ＰＯＤ３随辐照剂量增加活性逐渐减弱以致消失,在根尖细胞中可观察到微核、染色体落后和染色体桥等变异,其畸变率的剂量效应可用Ｙ＝ａ＋ｂｘ来描述。Ｍ１种子发芽率、苗高与同工酶变化大小表现出     

近视眼激光角膜切除术原理及控制方法

本文从理论上研究了激光人眼角膜切除术的原理和控制方法。详细分析了角膜前表面的曲率半径对近发消融深度和治疗结果的影响。     

Excitation delocalization in the bacteriochlorophyll c antenna of the green bacterium Chloroflexus aurantiacus as revealed by ultrafast pump-probe spectroscopy

Room temperature absorption difference spectra were measured on the femtosecond through picosecond time scales for chlorosomes isolated from the green bacterium Chloroflexus aurantiacus. Anomalously high values of photoinduced absorption changes were revealed in the BChl c Q_y transition band. Photoinduced absorption changes at the bleaching peak in the BChl c band were found to be 7–8 times greater than those at the bleaching peak in the BChl a band of the chlorosome. This appears to be the first direct experimental proof of excitation delocalization over many BChl c antenna molecules in the chlorosome.     

中国对虾卵子活化及卵裂的激光扫描共聚焦显微镜研究(英文)

有报导,与其它动物不同,对虾的卵子一接触海水、不经过受精,就可以被活化。但是,只有受精卵才能卵裂发育。而且,各种对虾卵子内皮质棒及皮层颗粒的形态结构、活化过程各有不同。本文就中国对虾卵子的活化及卵裂过程进行了激光扫描共聚焦显微镜（ＬＳＣＭ）研究。该技术可以清晰地显示细胞的立体图像。采集中国对虾,人工诱导产卵,未受精卵取自产卵虾体内,受精卵分期分批取样,固定。供试样品经ＰＢＳ漂洗,ＡＯ、ＦＩＴＣ和ＰＩ染色,ＬＳＣＭ观察、图像处理。刚产出的、未活化卵子形态不规则,皮层内富含皮质棒和皮层颗粒（Ｆｉｇ１）。不论受精与否,产入海水的卵子都能被激活并恢复减数分裂。活化后的卵子释放出皮层囊泡内的皮质棒（Ｆｉｇｓ２＆３）。释放出的皮质棒转变为均质的胶质层（Ｆｉｇｓ４＆５）。随后,皮层颗粒释放并在卵子表面转化为均质化的孵化膜。卵子开始举起,与孵化膜之间形成卵周隙。卵周隙内具有絮状物质（Ｆｉｇｓ６,７＆８）。卵子产出后笫８～１０ｍｉｎ,经过减数分裂,第一极体排放,并随着孵化膜的举起而被推向卵外（Ｆｉｇ５）。笫２０ｍｉｎ,第二极体排放,并由卵子表面到达孵化膜的内缘（Ｆｉｇ６）。在２０℃水温条件下,受精卵产入海水中６０     

Injury toNitella internodal cells alters microtubule organization but microtubules are not involved in the wound response

Summary The arrangement and relative stability of cortical microtubules during and after wound induction in internodal cells ofNitella flexilis andNitella pseudoflabellata were examined by immunofluorescence and by microinjection of fluorescently tagged tubulin. The formation of cellulosic wall appositions (wound walls), induced by treatment with 5×10^–2MCaCl₂, was identicalin young, growing cells and older non-growing internodes, suggesting that the initial microtubule pattern, which differs in growing and non-growing cells, does not influence wound wall formation. Depolymerization of microtubules with oryzalin did not alter wound wall morphology and microtubules were not detected during wound wall formation. After cessation of wound wall growth, microtubules were once again found in the wound site but these were always randomly oriented, even in young cells where the surrounding microtubules were organized into transverse arrays. Microtubules were similarly randomized in chloroplast-free windows induced by laser irradiation. Analysis of microtubule organization in living cells revealed that the microtubules in wound sites are less stable than the microtubules of adjacent transversely oriented arrays. The results indicate that although wounding can alter the relative stability and spatial organization of cortical microtubules, microtubules are neither involved in vesicle transport nor the construction of cellulosic wound walls.Abbreviations AFW artificial fresh water - BSA bovine serum albumin - DMSO dimethyl sulfoxide - FITC fluorescein isothiocyanate - PBS phosphate-buffered saline