Ribonuclease of Euglena gracilis

An enzyme in extracts of Euglena gracilis splits both purine and pyrimidine internucleotide bonds of ribonucleic acid. Its pH optimum is at 4.5; it is very heat-labile and is rather insensitive to inhibition by metal ions or sulfhydryl group reagents. A partial purification of the enzyme is described.     

Euglena gracilis: formation of giant mitochondria

The addition of antimycin A (0.5 microgram per milliliter) to cultures of a bleached strain of Euglena gracilis in the logarithmic phase of growth on succinate as a carbon source results in (i) an interruption of growth for 24 hours and (ii) an increase in whole-cell respiration and the emergence of a novel succinoxidase activity within 2 to 4 hours. After 3 to 5 hours, the mitochondria enlarge, fuse, and form a sheathlike structure situated close to the periphery of the cell.     

Circadian rhythmicity in amino acid incorporation in Euglena gracilis

A daily rhythm of amino acid incorporation exists in nondividing cultures of Euglena kept in a light-dark cycle. This rhythmicity persists for the two cycles measured in cultures transferred to constant conditions and is therefore probably circadian in nature.     

Internal cellular details of Euglena gracilis visualized by scanning electron microscopy

Simple washing of live Euglena gracilis cleans the pellicle of external coating material. When these cleaned cells are viewed with a scanning electron microscope, organelle outlines can be seen through the thinned pellicle. To view organelles directly, fixed Euglena cells are gently broken first or first frozen and then broken as part of their preparation for scanning electron microscopy. Subsequent viewing at magnifications of x 5,000 to x 21,000 reveals organelles, storage granules, endoplasmic reticulum, and nuclear pores, while retaining great depth of focus.     

Euglena gracilis: a novel lipid energy reserve and arachidonic acid enrichment during fasting

In Euglena gracilis grown in the dark, was esters, consisting of a combination of medium-chain fatty acids and alcohols that contain both odd and even numbers of carbon atoms, appear to be a reservoir for metabolic energy. When the organisms are fasted, their pellicular membrane systems become quite rich in long-chain polyenoic acids, mostly of the arachidonic acid family.     

Phototaxis and sensory transduction in Euglena

The accumulation of Euglena gracilis in an illuminated region is brought about by two main mechanisms: orientation and subsequent directed movement (positive phototaxis) toward light scattered from particles in the illuminated zone; and by the trapping of cells in this region because of shock reactions experienced upon the cells encountering a sudden decrease of light intensity at the light-dark boundary (inverse photophobic responses).Phototactic orientation is mediated by inverse photophobic reactions which occur when the shadow of the stigma periodically falls upon the photoreceptor proper. Euglena also exhibits shock reactions when an already high light intensity is increased further (direct photophobic responses). The expression of both types of phobic responses depends upon stimulus intensity and adaptation of the sensory system in a seemingly complex way. A definition of the minimum components of the stimulus transduction system and a systems analytical approach to the study of input-output relationships enables one to construct an electronic analog of the cell's signal processing system that converts the photoreceptor input to commands which activate or inhibit flagellar reorientation. Computer simulation studies show that this model has considerable predictive value. It is hoped that with the approach presented in this article, a generalized model has become available for dealing with the questions of sensory transduction in aneural systems. Certainly, at this point more questions have been raised than have been answered. Where is the processing device located? Are its kinetic properties determined by electrical processes or by the rates of chemical reactions? Is the processor, and thereby the behavior of the orgamism, modulated by natural environmental parameters, and can it be modified permanently through more drastic chemical treatment of the cell? Is the system capable of permanent or transitory modification through repeated response, that is, does it exhibit phenomena analogous to learning and memory in higher organisms? These are only a few of the problems that require study in the future.     

龙胆属1新种——纤茎龙胆

纤茎龙胆（新种） Gentiana gracilis S．S．Yang，F．Du et J．Wang sp.nov. 本种属小龙胆组（Sect．Chondrophylla Bunge）、小龙胆系（Ser．Humiles Marq．），与苍白龙胆（G．forestii Marg．）相近，区别在于本种植株纤细，基生叶小，茎生叶由下至上不变小，花粉红色或紫色，柱头裂片乳突中有多数黑色腺体，花药淡蓝色或白色，种子具细网纹．     

Symbiosis between Euglena and damselfly nymphs is seasonal

An endosymbiotic association has been demonstrated between Euglena and nymphs of three species of damselfly. The hindgut of the nymphs is inhabited by the euglenoid only during the winter. Symbiotic associations involving green euglenoids and insects are virtually unknown.     

Two c-type cytochromes from light- and dark-grown Euglena

A pigment-protein complex can be extracted, in aqueous 2-percent digitonin, from Euglena grown in the light. When further fractionated by acetone and ammonium sulfate this flagellate yields a c-type cytochrome. By similar extraction of dark-grown, nonphotosynthetic Euglena, another c-type cytochrome can be isolated. The cytochrome from the light-grown Euglena- is like that of cytochrome c isolated from a photosynthetic bacterium. The cytochrome from the dark-grown Euglena is like cytochrome f found in the chloroplasts of higher plants.     

迷果芹不同密度播种试验

设计4种不同播种密度试验,通过迷果芹不同播种密度出苗率、两年生保苗率和生产量的对比分析,结果表明播种密度在15kg/hm2时收益最佳,人工栽培与野生药材的活性成分含量相差不大。     

Biochemical modeling of an autonomously oscillatory circadian clock in Euglena

Eukaryotic microorganisms, as well as higher animals and plants, display many autonomous physiological and biochemical rhythmicities having periods approximating 24 hours. In an attempt to determine the nature of the timing mechanisms that are responsible for these circadian periodicities, two primary operational assumptions were postulated. Both the perturbation of a putative element of a circadian clock within its normal oscillatory range and the direct activation as well as the inhibition of such an element should yield a phase shift of an overt rhythm generated by the underlying oscillator. Results of experiments conducted in the flagellate Euglena suggest that nicotinamide adenine dinucleotide (NAD+), the mitochondrial Ca2+-transport system, Ca2+, calmodulin, NAD+ kinase, and NADP+ phosphatase represent clock "gears" that, in ensemble, might constitute a self-sustained circadian oscillating loop in this and other organisms.     

Galactosyl diglycerides: their possible function in Euglena chloroplasts

Illumination of euglenas grown in the dark induces the formation of chloroplasts characterized by the simultaneous appearance of chlorophyll and galactosyl diglycerides in a relatively fixed ratio. The fatty acyl chains of the galactosyl diglycerides are constructed so that they can provide a stable lock-and-key fit with the phytol chains of chlorophyll in such a way as to localize the porphyrin structures of chlorophyll and space them for efficient photoreception. Light-starved photobiotic euglenas show chloroplast shrinkage with a concurrent partial loss of galactosyl diglycerides.     

迷果芹多糖提取工艺研究

[目的]优化迷果芹根中多糖的提取工艺条件。为迷果芹的进一步研究提供参考。[方法]采用单因素和正交实验,考察了提取过程中提取温度、提取时间、提取次数和料液比对迷果芹多糖提取的影响,筛选迷果芹根中多糖的最佳提取工艺。[结果]单因素实验表明,当提取时间为2 h,浸提温度为90℃,料液比(g/ml)为1∶10和提取次数为2次时,迷果芹多糖的提取率最高。正交实验表明,影响迷果芹多糖提取率的因素的顺序是:提取温度>提取次数>料液比>提取时间;迷果芹多糖的最佳提取工艺为:提取温度90℃,提取时间2 h,提取次数为1次,加入10倍量的水。[结论]由方差分析可知,提取温度对迷果芹提取的影响作用最显著。其他3种因素均无显著性。     

Persisting circadian rhythm of cell division in a photosynthetic mutant of Euglena

A persisting, free-running, circadian rhythm of cell division in a heterotrophically grown mutant of Euglena gracilis var. bacillaris having impaired photosynthesis is obtained upon placing a culture that has been previously synchronized by a 10,14 light-dark cycle into continuous darkness at 19 degrees C (but not at 25 degrees C). A similar persisting rhythm is initiated in exponentially increasing cultures (growing in darkness at 19 degrees C) by a single "switch-up" in irradiance to continuous bright illumination. The results implicate an endogenous biological clock which "gates" the specific event of cell division in the cell developmental cycle.     

Effects of supernumerary chromosomes on production of pigment in Haplopappus gracilis

One of the two types of supernumerary chromosomes found in Haplopappus gracilis effects pigment production in the achene walls. When one, two, and four supernumerary chromosomes were added to the basic complement, a corresponding increase in the amount of one type of pigment was found to occur. No overlapping of the effects on pigment production was observed among different numbers of supernumeraries or between the supernumeraries and normal chromosome complement.     

UV-B辐射胁迫对细叶青冈幼苗叶绿素荧光特性的影响

通过对在自然生境(CK)、辐射UV-B增强(+10％)和辐射UV-B减弱(-80％)三种条件下的细叶青冈幼苗叶绿素含量、荧光参数Fv/Fm、Fv/Fo和φPSⅡ的测定研究,探讨UV-B辐射胁迫对细叶青冈生长的影响.结果表明,细叶青冈幼苗在辐射UV-B减弱胁迫下叶绿素含量、荧光参数Fv/Fm、Fv/Fo和φPSⅡ均高于辐...     

Circadian rhythm of cell division in Euglena: effects of random illumination regimen

A persisting, "free-running," circadian rhythm of cell division in autotrophically grown Euglena gracilis is obtained upon placing either an exponentially increasing population or a culture that has been synchronized by a 10:14 light-dark cycle in a random illumination regimen that affords a total of 8 hours of light each 24 hours. These results are interpreted as implicating an endogenous biological clock which "gates" the specific event of cell division in the cell developmental cycle.     

小叶青冈群落主要种群生态位研究

采用定量分析的方法对福建茫荡山自然保护区小叶青冈群落11个主要优势种进行了生态位研究,测定其生态位宽度、生态位相似比例等生态位特征值.结果表明：生态位宽度排在前6位的分别是小叶青冈、甜槠、木荷、弯蒴杜鹃、乌饭和深山含笑.小叶青冈与其他种群的生态位相似比例、生态位重叠值相对较高（猴头杜鹃例外）,表明它与其他种群之间的竞争相对激烈,易与生态位宽的树种形成共优群落.     

迷果芹粗多糖(SGS)药理学活性的初步研究

[目的]研究迷果芹粗多糖(SGS)对荷瘤(肝癌H22)小鼠的影响。[方法]用小鼠建立体内肿瘤模型,通过动物试验研究SGS对荷瘤小鼠体重的影响及对小鼠方向辨别障碍的保护作用。[结果]阳性对照药环磷酰胺明显增加了荷瘤小鼠瘤体重量,减轻了小鼠体重;SGS对荷瘤小鼠瘤体重量无明显影响,其3个剂量组的小鼠体重增长均明显高于阳性对照药环磷酰胺组。说明SGS对小鼠没有明显的副作用,或者说与阳性对照药环磷酰胺组相比,毒副作用较小。3个剂量组小鼠的胸腺指数和脾指数均高于环磷酰胺组,但无统计学意义。SGS的所试剂量对小鼠方向辨别障碍有一定的保护作用,但无统计学意义。[结论]SGS的毒副作用小且能增强机体的免疫力。     

新疆虫草的生物学特性

1 新疆黑槌虫草菌的形态特征 1.1 天然虫草形态特征子座从寄主头部发出,棕褐色,棒状,长约20 mm,柄粗约2 mm,可孕部似球形,黑褐色,子囊壳垂直埋生拟卵圆形,颈部长525～600 μm×210～300 μm,子囊柱状,子囊帽半球形,子囊孢子分隔,子囊孢子成熟后断裂成细长柱形的次生子囊孢子.