EFFECTS OF CHLORAMPHENICOL ON CHLOROPLAST AND MITOCHONDRIAL ULTRASTRUCTURE IN OCHROMONAS DANICA

The effect of chloramphenicol (CAP) on cell division and organelle ultrastructure was studied during light-induced chloroplast development in the Chrysophyte alga, Ochromonas danica. Since the growth rate of the CAP-treated cells is the same as that of the control cells for the first 12 hr in the light, CAP is presumed to be acting during that interval solely by inhibiting protein synthesis on chloroplast and mitochondrial ribosomes. CAP markedly inhibits chloroplast growth and differentiation. During the first 12 hr in the light, chlorophyll synthesis is inhibited by 93%, the formation of new thylakoid membranes is reduced by 91%, and the synthesis of chloroplast ribosomes is inhibited by 81%. Other chloroplast-associated abnormalities which occur during the first 12 hr and become more pronounced with extended CAP treatment are the presence of prolamellar bodies and of abnormal stacks of thylakoids, the proliferation of the perinuclear reticulum, and the accumulation of dense granular material between the chloroplast envelope and the chloroplast endoplasmic reticulum. CAP also causes a progressive loss of the mitochondrial cristae, which is paralleled by a decline in the growth rate of the cells, but it has no effect on the synthesis of mitochondrial ribosomes. We postulate that one or more chloroplast ribosomal proteins are synthesized on chloroplast ribosomes, whereas mitochondrial ribosomal proteins are synthesized on cytoplasmic ribosomes.     

青藏高原萹蓄、车前叶绿体超微结构研究

对生长在青藏高原两个海拔高度的蓄和车前叶绿体进行超微观察表明。1.高海拔地区蓄的叶绿体发生变形,叶绿体的长度缩短、厚度增加,被膜模糊,而车前叶绿体的形态变化不大。2.高海拔地区的两种植物叶绿体的基粒片层和基质片层都呈现肿胀现象,尤以蓄为显著。3．高海拔地区的两种植物叶绿体中基粒片层的叠垛程度均比低海拔地区的高。以上特征是青藏高原特殊的高寒生态条件长期影响的结果。     

玉米突变体（zb／zb）的叶绿体光合特性

常规育种中出现的偶然变异植株,用来作光合机理和遗传机理的研究,不需要复杂的生物技术操作手段,受到很多学者关注。植物的花斑叶是一种结构上的嵌合体。Hayden和Hopkins发现玉米(zae mays L.)的黄绿色突变体OYyg中缺少介于CPⅠ与CPⅡ之间的一条被他们称为复合体Ⅳ的小带。李玉湘和李继耕用玉米白色叶片和条纹叶片两种突变系,进行叶绿素蛋白复合体研究表明,纯白色突变系叶片中捕光叶绿素a/b蛋白复合体的合成受阻。本文用zb/zb与一正常自交系杂交,得到的F_1代为zb/zb基因型。将其分别播种后,对白色叶片和绿色叶片叶绿体膜的光合特性进行了多项比较研究。     

CO2倍增对3种禾本科植物叶绿体超微结构的影响

本对ＣＯ２正常浓度（３５０μＬ／Ｌ）倍增（７００μＬ／Ｌ）条件下,小麦、水稻和高粱等３种禾本科植物叶肉及维管束鞘细胞中叶绿体的数目,叶绿体的超微结构等进行了比较研究。在光镜和透射电镜下的观测结果表明：高浓度ＣＯ２可促进３种禾本科植物叶绿体的发育,使之数量增多、体积增大;叶绿体中淀粉粒积累增多、体积增大。其中,Ｃ４植物的高粱叶绿体中淀粉粒数量明显增加,而叶绿体光合膜的结构却受到很大破坏;Ｃ３植物的小     

EFFECTS OF DIFFERENT LEVELS OF INBREEDING ON PROGENY FITNESS IN PLANTAGO CORONOPUS

Inbreeding depression (δ) is a major selective force favoring outcrossing in flowering plants. Many phenotypic and genetic models of the evolution of selfing conclude that complete outcrossing should evolve whenever inbreeding depression is greater than one-half, otherwise selfing should evolve. Recent theoretical work, however, has challenged this view and emphasized (1) the importance of variation in inbreeding depression among individuals within a population; and (2) the nature of gene action between deleterious mutations at different loci (epistasis) as important determinants for the evolution of plant mating systems. The focus of this study was to examine the maintenance of inbreeding depression and the relationship between inbreeding level and inbreeding depression at both the population and the individual level in one population of the partially self-fertilizing plant Plantago coronopus (L.). Maternal plants, randomly selected from an area of about 50 m² in a natural population, were used to establish lines with expected inbreeding coefficients (f) of 0, 0.25, 0.50, 0.75, and 0.875. Inbreeding depression was estimated both in the greenhouse and at the site of origin of the maternal plants by comparing growth, survival, flowering, and seed production of the progeny with different inbreeding coefficients. No significant inbreeding depression for these fitness traits was detected in the greenhouse after 16 weeks. This was in strong contrast to the field, where the traits all displayed significant inbreeding depression and declined with increased inbreeding. The results were consistent with the view that mutation to mildly deleterious alleles is the primary cause of inbreeding depression. At the family level, significantly different maternal line responses (maternal parent × inbreeding level interaction) provide a mechanism for the invasion of a selfing variant into the population through any maternal line exhibiting purging of its genetic load. At the population level, evidence for synergistic epistasis was detected for the probability of flowering, but not for total seed production. At the family level, however, a significant interaction between inbreeding level and maternal families for both traits was observed, indicating that epistasis could play a role in the expression of inbreeding depression among maternal lines.     

ULTRASTRUCTURE OF DNA-CONTAINING AREAS IN THE CHLOROPLAST OF CHLAMYDOMONAS

The chloroplast of Chlamydomonas moewusii was examined by electron microscopic and cytochemical methods for the possible presence of DNA. Both the Feulgen reaction and acridine orange indicated the presence within the chloroplast of one or more irregularly shaped DNA-containing bodies generally in the vicinity of the pyrenoid. Electron micrographs revealed 25 A microfibrils in these areas which correspond to DNA macromolecules with respect to their location, morphology, and sensitivity to deoxyribonuclease digestion. The possibility that this material is the genetic system of the chloroplast and the hypothesis that the chloroplast represents an evolved endosymbiont are discussed.     

EFFECTS OF GLUCOSE ON THE PROCESS OF CHLOROPLAST DEVELOPMENT IN CHLORELLA PROTOTHECOIDES

By growing Chlorella protothecoides in a medium rich in glucoseand poor in nitrogen source (urea), the entirely chlorophyll-lesscells showing no discernible plastid structure and containingonly little RNA and protein were obtained. These cells, whichwere called "glucosebleached" cells, turned green after a certainlag period, when they were incubated, in the light, in a mediumcontaining the nitrogen source and basal mineral nutrients butwithout glucose. As has been shown in previous studies, thisgreening process involves two consecutive steps : a light-independentphase, in which RNA plays an essential role, and a light-requiringphase, in which the chlorophyll formation and full organizationof chloroplast take place accompanied by the formation of acertain species of protein ("alkali-stable" protein). The wholeprocess of greening was found to be profoundly suppressed byaddition of glucose, the degree of suppression being determinedby the relative concentrations of glucose and the nitrogen source.The primary act of glucose was manifest in the repression ofsyntheses of RNA, and of the species of protein mentioned above,which participate in, or causally related to, the first andsecond phases, respectively, in the greening process. ¹ This paper was read at the Symposium on Extranuclear Self-reproducingSystems held by the Botanical Society of Japan in October, 1964     

天花粉对小鼠子宫肥大细胞超微结构的影响

本研究用雌性中国１号小鼠１２只,分实验组和对照组,实验组分别腹腔注射天花粉后处死,取子宫组织作超薄切片,电镜观察。在天花粉作用下,常见子宫肥大细胞脱颗粒,呈功能活化状态,并与子宫平滑肌细胞紧密相邻。提示肥大细胞可能通过脱颗粒释放组胺促进子宫平滑肌的收缩。同时,也见肥大细胞与子宫结缔组织中的成纤维细胞,淋巴细胞等密切接触,提示成纤维细胞和淋巴细胞与天花粉作用下子宫肥大细胞的数量增多有关。     

核磁共振对水稻胚超微结构的影响

本文报导了水稻种子经核磁共振处理后,其胚细胞超微结构的变化。结果表明,水稻种子经核磁共振处理后,其胚细胞中的线粒体、线粒体内嵴的数量、粗面内质网及高尔基体的数量均有增加,淀粉粒的体积变小。因此,核磁共振处理能促进水稻种子胚细胞内的能量代谢、物质转化与物质运输。     

THE EFFECT OF LIGHT INTENSITY AND TEMPERATURE ON PLANT GROWTH AND CHLOROPLAST ULTRASTRUCTURE IN SOYBEAN

Soybean plants grown in controlled environment cabinets under light intensities of 220 w/m² or 90 w/m² (400–700 nm) and day to night temperatures of 27.5–22.5 C or 20.0–12.5 C in all combinations, exhibited differences in growth rate, leaf anatomy, chloroplast ultrastructure, and leaf starch, chlorophyll, and chloroplast lipid contents. Leaves grown under the lower light intensity at both temperatures had palisade mesophyll chloroplasts containing well-formed grana. The corresponding leaves developed under the higher light intensity had very rudimentary grana. Chloroplasts from high temperature and high light had grana consisting of two or three appressed thylakoids, while grana from the low temperature were confined to occasional thylakoid overlap. Spongy mesophyll chloroplasts were less sensitive to growth conditions. Transfer experiments showed that the ultrastructure of chloroplasts from mature leaves could be modified by changing the conditions, though the effect was less marked than when the leaf was growing.     

PATHOLOGICAL CHANGES IN ULTRASTRUCTURE: EFFECTS OF VICTORIN ON OAT ROOTS

Cells in the interior of susceptible oat roots treated with the disease-inducing agent victorin exhibit many of the ultrastructural features which characterize the epidermal or outermost root cap cells of untreated roots. An increase in electron density of cell walls fixed in permanganate is the first effect of victorin seen in the root interior. Other early victorin-induced changes are formation of enlarged, densely stained vesicles by the Golgi apparatus and organization of the endoplasmic reticulum into roughly parallel profiles. All of these features are characteristic of untreated epidermal cells. Victorin also induces the formation of large numbers of lomasome-like wall lesions and causes a marked increase in the number of nearly spherical, membrane-bounded structures tentatively identified as spherosomes. Similar lomasome- and spherosome-like structures are much more abundant in the outermost cells of the root cap than in other regions of untreated roots. This suggests that these structures may be characteristic of cells destined to undergo disintegration. Victorin-induced lesions appear to arise within the cell wall as the result of an activation of wall-degrading enzymes. An early change which makes the unit structure of the plasma membrane visible over extended areas may account for victorin-induced changes in permeability. Disrupted plasma membranes and swollen mitochondria are found only in cells heavily damaged by victorin. Many of the effects of victorin resemble those of calcium deficiency and calcium is known to suppress victorin-induced disease symptoms. This suggests that calcium nutrition may play a role in the pathological changes induced by victorin.     

EXPERIMENTAL ECOLOGICAL GENETICS IN PLANTAGO IV. EFFECTS OF TEMPERATURE ON GROWTH RATES AND REPRODUCTION IN THREE POPULATIONS OF PLANTAGO LANCEOLATA L. (PLANTAGINACEAE)

The effects of temperature on growth rates and flowering responses of Plantago lanceolata L. populations sampled from open, shaded, and sunflecked habitats were studied in controlled environments. A large number of characteristics were phenotypically plastic in response to a broad range of temperatures. Low night temperatures substantially reduced reproductive effort, whereas high temperatures produced a reduction in total biomass. Temperature had little effect on leaf or inflorescence production rates, other than at very low temperatures. The phenotypic plasticity observed in the growth chamber correlated well with the observed seasonal phenology. Genetic differences were found in inflorescence height and total plant productivity. The rapid growth rate, the high reproductive effort, and generally broad temperature optimum to moderate temperatures are consistent with the occurrence of P. lanceolata in a wide variety of disturbed habitats in temperate latitudes.     

甜菊组织培养物中叶绿体的超微结构与脱分代

含有叶绿体的甜菊（Ｓｔｅｖｉａｒｅｂａｕｄｉａｎａ）愈伤组织细胞转移至新鲜培养基后,导致光合片层的逐渐减少或消失,最后叶绿体脱分化形成原质体样的结构。超微结构观察表明,光合片层的减少或消失与降解及叶绿体分裂特别是不均等缢缩分裂而致基质组分和类囊体膜稀释有关。这一过程并不完全同步,一些质体含有少量正常的片展而另一些质体含有退化的片层甚至片展结构完全消失。细胞的一个明显特点是细胞器大多聚集在细胞核附近,细胞质增加并向细胞中央伸出细胞质丝。同时可观察到原质体。培养７ｄ后,许多细胞呈分生状态,细胞质富含细胞器,充满了细胞的大部分空间。此时细胞中的质体大多呈原质体状态。在细胞生长的稳定期,质体内膜组织成基质基粒片层,同时质体核糖体增加。文中讨论了高度液泡化细胞脱分化与细胞中叶绿体脱分化的关系。     

EFFECTS OF CALCIUM AND MAGNESIUM DEFICIENCY ON THIAMINE DISTRIBUTION IN RAT BRAIN AND LIVER

Wistar rats were divided into 4 groups and the following different synthetic diets were given for 1 month: group 1, calcium- and magnesium-deficient; group 2, calcium-deficient, magnesium-sufficient; group 3, calcium-sufficient, magnesium-deficient; group 4, calcium-sufficient, magnesium-sufficient (normal diet). After 1 month on these dietary regimens, the rats were killed. In calcium-deficiency (groups 1 and 2), thiamine concentration in synaptosomal and myelin-membrane fractions in the brain had decreased and the ratio of free thiamine to total thiamine and non-protein bound thiamine amount had increased in the brain. In magnesium-deficiency (groups 1 and 3), thiamine concentration in the liver and activities of thiamine-dependent enzymes in liver had decreased. These results indicate that calcium plays a role in binding thiamine in nerve membrane structures, which have a specific role in the conduction process of nervous tissues. In contrast, magnesium has little effect on thiamine in nervous tissues but may play an important role in thiamine-dependent enzyme systems in the liver.     

己酮可可碱对非酒精性脂肪性肝炎大鼠肝脏超微结构和酶组织化学的影响

目的研究己酮可可碱(PTX)对非酒精性脂肪性肝炎(NASH)大鼠肝脏超微结构和酶组织化学的影响。方法高脂饮食建立大鼠非酒精性脂肪性肝炎模型。取SD大鼠40只,分为对照组、12w模型组、16w模型组和治疗组,每组10只。腹主动脉采血,测ALT、AST、血糖等水平。取肝组织做电镜和SDH、CCO、ATPase、LDH的酶组织化学染色。结果两个模型组均比对照组ALT、AST、血糖升高,LDL降低(P<0.05)。治疗组血糖、AST比16w模型组降低(P<0.05)。电镜显示16w模型组线粒体肿大,嵴排列紊乱,基质密度降低。治疗组结构改善。酶组织化学显示四种酶的活性16w模型组均较对照组降低(P<0.05),治疗组活性均较16w模型组升高(P<0.05)。结论NASH时存在肝细胞能量代谢障碍,经PTX治疗后能量代谢障碍得到改善。     

血清及BSA对牛体外受精胚胎发育过程超微结构影响的研究

本研究将牛IVF胚胎分别在SOF FCS、SOF BSA和SOF PVA三种培养系统内进行培养,然后分别取三个系统中发育到原核期、2细胞、4细胞、8细胞、桑椹胚和囊胚阶段的胚胎进行透射电镜的观察,了解培养系统中血清和BSA的添加与否对胚胎发育过程中细胞内脂滴、细胞连接、细胞凋亡和微绒毛发育的影响。观察结果表明：各培养系统胚胎的细胞质中均存在大量的脂滴,表明外培养系统是造成脂滴积累的主要原因;血清的添加不会进一步促进脂滴的大量积累,反而可以避免多个脂滴聚合成更大的脂滴。三种培养系统条件下胚胎细胞连接无显著差异。培养系统中添加FCS或BSA时,桑椹胚期以后的胚胎细胞中存在凋亡小体,表明血清成分是引起细胞凋亡的重要原因。培养系统中血清成分的缺乏会影响胚胎表面微绒毛的发育。     

SMT对大鼠在体心脏缺血-再灌注损伤超微结构的保护作用

目的：研究ＳＭＴ对心脏缺血－再灌注损伤（ＩＲＩ）心肌超微结构的影响。方法：ＳＤ大鼠１８只,体重３２０￣３８０ｇ,随机分为三组：①缺血－再灌注组（ＩＲ）：夹闭冠状动脉左前降支６０ｍｉｎ,松夹２０ｍｉｎ。②缺血－再灌注＋ＳＭＴ组（ＳＭＴ）：再灌注前５ｍｉｎ,股静脉注射ｉＮＯＳ抑制剂Ｓ－ｍｅｔｈｙｌｉｓｏｔｈｉｏｕｒｅａ ｓｕｌｆａｔｅ（ＳＭＴ ５ｍｇ／ｋｇ ｗ）,余同ＩＲ组;③对照组（Ｃ）：暴露心脏后     

EFFECTS OF DIFFERENT LEVELS OF DIETARY PROTEIN ON BRAIN GLUTAMATE DEHYDROGENASE AND DECARBOXYLASE IN YOUNG ALBINO RATS

Abstract— Studies were carried out to identify the minimum levels of protein (casein) needed in the diet in order to prevent or reverse the deficits in brain enzymes previously found with protein deficiency. Groups of weanling albino rats were fed diets containing variable amounts of protein (5, 8, 10, 15 or 20 per cent in experiment I, and 5, 6, 7, 8 or 20 per cent in experiment II) for 5 or 10 weeks. Deficits in brain wt and brain glutamate dehydrogenase and decarboxylase were found to be prevented by a diet containing 8 per cent or more of protein, although for optimum growth 15 per cent protein in the diet was found to be necessary. Groups of rats were fed a 5 or 20% protein diet for 10 weeks after which the 5% protein animals were either continued on the diet for another 10 weeks or changed to one containing 8, 10, 15 or 20% protein. The brain enzyme deficits found with the 5% protein diet were found to be fully reversed by feeding a 10% protein diet during rehabilitation.     

玉米不同叶位叶片叶绿体超微结构与光合性能的研究

对玉米植株基部（第3叶）,中部（果穗叶）和上部（倒2叶）叶位叶片,进行叶绿体超微结构的观察,并测定了叶绿素含量和光合强度,结果表明,不同叶位叶片叶肉细胞中叶绿体的超微结构,随叶位上升而渐趋复杂化,果穗叶最为显著,向上又趋简单,具体表现为基粒片层的数目随叶位上升而增多基质片层和基质也随之增加,果穗叶最多,向上又趋减少,不同叶位叶片叶绿素含量和光合强度,果穗叶高于其它叶位。