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1.
PHYTOALEXINS, WATER-STRESS AND STOMATA   总被引:1,自引:1,他引:0  
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2.
PHYTOALEXINS, WATER-STRESS AND STOMATA   总被引:2,自引:2,他引:0  
  相似文献   

3.
蛙心包淋巴孔的发现   总被引:5,自引:0,他引:5  
李继承 《动物学报》2000,46(4):372-375,T004
首次报道蛙心包淋巴孔 ,揭示心包腔淋巴转归途径。本实验应用扫描电镜和透射电镜观察心包淋巴孔的超微结构 ,并使用计算机图象处理技术对淋巴孔作定量分析。结果发现 ,正常蛙心包腔面有一些散在分布的心包淋巴孔和少量淋巴窦。构成淋巴孔的间皮细胞常出现粗大的胞质突起 ,伸入淋巴孔 ,形成瓣膜状结构。淋巴孔的平均直径为 0 72±0 33μm ,平均分布密度是 3 57± 2 0 7个 /0 0 1mm2 ;心包间皮淋巴窦的面积是 995 0 8±2 2 1 74μm2 /0 0 1mm2 。蛙心肌无血管 ,其血供仅由心腔内血液直接进入心肌的小梁间隙。心包脏层未发现有淋巴孔。结果表明 :间皮淋巴窦是心包膜正常“漏出”的形态依据。心包淋巴孔的发现 ,证明心包腔淋巴引流途径的存在。淋巴引流对于心肌组织间液的平衡 ,清除组织间液蛋白质 ,防止心肌间质水肿 ,有重要意义  相似文献   

4.
裂叶沙参气孔行为与光合蒸腾特性通径分析   总被引:2,自引:2,他引:0  
通过相关系数和通径系数分析方法,对不同海拔高度裂叶沙参(Adenophora lobophylla)气孔行为与光合、蒸腾特性的关系进行了相关性分析。气孔行为对光合、蒸腾均缺乏显著的相关性,说明裂叶沙参光合、蒸腾作用的气孔控制不显著;裂叶沙参叶片气孔开度直接影响光合速率和胞间CO2浓度,气孔导度对裂叶沙参蒸腾速率影响较大。  相似文献   

5.
中国西北地区松科和柏科气孔器形态   总被引:2,自引:0,他引:2  
现代针叶树气孔器的研究为鉴定化石气孔器奠定了基础,对第四纪植被变化和古气候的研究起着很重要的作用,是第四纪孢粉学的一个重要补充。本文运用常规的标准的孢粉分析方法,对中国西北地区常见的松科3属8种和柏科3属4种植物气孔器进行了观察分析。结果表明凭气孔器大小可以区分松科与柏科。利用气孔器大小、T型结构的形状?上部木质片与气孔器茎之间的夹角进行属的鉴别,再结合茎的长度、宽度、中间木质部的宽、T型外角度和上部木质片外缘形状等可以进行种的鉴别,并编制了一个初步的检索表。  相似文献   

6.
李慧  李继承 《动物学报》2002,48(4):511-518
应用透射电镜、扫描电镜和酶组织化学方法,研究胚胎期和出生后不同时期小鼠膈腹膜淋巴孔(PLS)和膈淋巴管的发生和发育,并用Elescope计算机图像处理技术对PLS进行定量分析。结果发现:胚胎13天时,膈腹膜仅由扁平形间皮细胞(FMC)组成;胚胎15天时,FMC间出现立方形间皮细胞(CMC)和早期腹膜淋巴孔(NLS);胚胎18天时,膈毛细淋巴管出现,台盼蓝吸收试验显示NLS无物质吸收功能;出生后1天(PND1),膈毛细淋巴管内皮细胞向PLS伸出胞质突起,并横跨CMC下结缔组织纤维和基底膜,形成腹膜下小管。后者与PLS沟通,建立了腹膜腔内物质转归通路。台盼蓝吸收试验表明,出生后PLS具有物质吸收功能,即为成熟腹膜淋巴孔(MLS)。PND5,立方细胞嵴(CMCR)发生,膈毛细淋巴管数量增多。PND10,大量立方细胞嵴融合,形成条带状分布的立方细胞区域,其上分布有大量MLS。随着发育进展,MLS平均面积和平均分布密度逐渐增大,且随着膈淋巴管的发育,吸收功能逐渐增强。  相似文献   

7.
陈锡沐  李秉滔   《广西植物》1991,(2):146-148+193
本文报道了罗布麻属和白麻属植物叶表面气孔形态的比较观察。结果表明,两者气孔形态的微观性状十分相似,同属一个类型。结合花部形态的比较分析,认为Poacynum Baill。独立成属的依据是不充分、不合理的,应将之归并回罗布麻属Apocynum L 中。列举了原白麻属所隶下2个种的正确学名。  相似文献   

8.
本实验以台盼蓝为示踪剂,观察成年雌豚鼠在妊娠、注射促排卵激素和雄激素时,卵巢囊淋巴孔对示踪剂的吸收情况,并结合扫描电镜和计算机图像处理,对豚鼠卵巢囊内壁的淋巴孔进行观察和统计,以研究妊娠和激素干预对豚鼠卵巢囊淋巴孔开放和淋巴吸收功能的影响。结果表明,妊娠组卵巢囊吸收示踪剂的量最多,促排卵组次之,雄激素组最少,且组间两两比较均有显著性意义(P<0.05)。在每1000μm~2的视野中,妊娠组卵巢囊淋巴孔的开放面积为189.9±48.7μm~2,促排卵组为104.4±31.2μm~2,雄激素组为40.5±18.7μm~2,组间两两比较均有显著性意义(P<0.05)。妊娠组卵巢囊内层纤毛柱状上皮的分泌颗粒数量最少,而促排卵组的分泌颗粒较多,且纤毛最活跃。本实验研究结果表明,妊娠和激素干预能影响豚鼠卵巢囊淋巴孔的开放和吸收,囊内卵巢的功能状态与豚鼠卵巢囊淋巴孔的调控密切相关。  相似文献   

9.
本实验通过扫描电镜等方法研究豚鼠卵巢囊及卵巢囊淋巴孔的结构,并探讨了卵巢囊及其淋巴孔的种属差异.实验结果首次报道豚鼠卵巢囊内、外层上皮均存在淋巴孔;豚鼠卵巢囊结构在输卵管走行、囊闭合程度及囊表面超微结构等方面与金仓鼠存在差异.结果提示豚鼠卵巢囊内、外层淋巴孔是沟通卵巢囊腔、卵巢囊淋巴系及腹膜腔的形态基础,可能是三者间物质转运的重要途径.卵巢囊淋巴孔可能影响物种的繁殖并参与囊腔内局部免疫反应.卵巢囊结构和发育程度与对应的输卵管伞端等结构及其他生殖特点相适应,研究结果丰富了生殖形态学和比较解剖学资料.  相似文献   

10.
High yields of metabolically active mitochondria can be rapidly isolated from reserve storage tissues of castor bean (Ricinus communis L.), cucumber (Cucumis sativus L., cv. Early Green Cluster), cotton (Gossypium hirsutum L., cv. Coker 711), and soybean (Glycine max L., cvs Forrest and Centennial) seedlings by application of crude homogenates to discontinuous sucrose gradients, allowing for a rapid separation of organelles from detrimental factors present in cell homogenates.  相似文献   

11.
家兔肋胸膜淋巴孔的发现   总被引:1,自引:0,他引:1  
李燕园  李继承 《动物学报》2002,48(6):797-803
为了研究成年家兔肋胸膜淋巴孔的超微结构与三维构形 ,作者应用扫描电镜和透射电镜对成年家兔肋胸膜淋巴孔进行观察 ,用计算机图像处理系统对胸膜淋巴孔作图像数据化处理 ;NaOH溶液消化间皮细胞 ,裸露间皮下结缔组织和筛斑 (maculacribriform)。发现肋胸膜立方形间皮细胞 (cuboidalmesothelialcell)之间有圆形或椭圆形的胸膜淋巴孔 (pleurallymphaticstomata) ,其平均面积和平均密度分别为 :7 2 0± 3 6 9μm2 和 1 2 1±0 72个 / 0 0 1mm2 。扁平形间皮细胞表面未见淋巴孔。胸膜淋巴孔籍胸膜下小管与毛细淋巴管相通。仅在立方形间皮下结缔组织中发现有筛斑。肋胸膜上还可见闭合淋巴孔 (closedlymphaticstomata)和由巨噬细胞组成的乳斑 (milkyspot)。覆盖在肋骨上的胸膜无淋巴孔分布。家兔胸膜淋巴孔通过胸膜下小管与淋巴管直接相连 ,形成从胸膜腔至脉管系的惟一直接通路。  相似文献   

12.
D. Morandi 《Plant and Soil》1996,185(2):241-251
This paper will review work mainly done during the last twenty years on the involvement of phytoalexin and phenolic compounds in mycorrhizal interactions. It has been observed that phytoalexins and associated molecules accumulate in roots after mycorrhizal infection, but less intensively and more slowly than in pathogenic interactions. Following mycorrhizal infection, enzymes of phenylpropanoid metabolism have been shown to be activated differentially. Some flavonoids and isoflavonoids have been reported to stimulate in vitro germination of mycorrhizal fungi or in vitro mycorrhizal infection, but their biological significance in signalling between the two symbiotic partners, and in biocontrol of plant disease by arbuscular mycorrhizal fungi, have not yet been elucidated.  相似文献   

13.
Pyrolysis–gas chromatography (Py–GC) combined with on-line methylation was applied to a correlation analysis between the distributions of fatty acid components in the lipids of zooplankter individuals and those of ingested algae using principal component analysis (PCA). Py–GC in the presence of organic alkali, tetramethylammonium hydroxide (TMAH), was used to estimate the apparent distributions of fatty acid components contained in a single individual zooplankter weighing several tens of micrograms and a small sample size of ingested algae samples in the order of 10 μg. The observed fatty acid compositions were used as a database for the PCA in order to discriminate the zooplankton and ingested algae samples. The result obtained indicated that the fatty acid compositions of zooplankton individuals used in this work were significantly reflected in those of their ingested food in spite of some contribution from isomerization and/or elongation of fatty acid components during digestion of the ingested algae phytoplankton in living zooplankters.  相似文献   

14.
高产油小球藻的筛选及其油脂分析   总被引:3,自引:0,他引:3  
小球藻广泛分布于各种生境,特别是淡水环境中,适应性强。其同化产物主要是淀粉,但在环境胁迫条件下可显著积累中性脂,其脂肪酸类型主要为C16和C18,适合作为生物柴油的原料。我们从中国部分地区水体中分离纯化到若干株小球藻,通过薄层层析比较分析了21株产油小球藻的油脂含量,筛选到一株三酰基甘油含量较高的藻株Chlorella sp.NMX37N。其适宜生长温区为15—35℃,在25℃时生长速率最快,比生长速率为0.53/d,生长的最适光强为250μmol photons/(m2.s)。批量培养实验显示,藻细胞的三酰基甘油含量随培养时间延长而增加,并在培养的稳定期达到最大值,此时培养液中氮基本被耗尽。在批量培养条件下培养Chlorella sp.NMX37N约40d,藻细胞中总脂含量可达到33%左右,与此相比通过两步培养方式,将培养至对数后期(约20d)的藻细胞缺氮处理48h后,得到的总脂产率相当。通过两步培养方式可以大大缩短培养时间,使得该藻细胞快速有效积累油脂。另外,气相色谱分析显示,该藻的总脂和三酰基甘油的脂肪酸均以C16∶0和C18∶2为主,占总脂肪酸的70%以上,且不含C20以上的长链脂肪酸,可以作为优质的生物柴油原料。  相似文献   

15.
Pretreatment of date palm seedlings with an hypoaggressive Fusarium isolate (AHD) protected them partially from further infection by Fusarium oxysporum f.sp. albedinis (Foa), the Bayoud disease pathogen. No mortality occurred during 2–3 months of incubation in plants pretreated with AHD, as opposed to aggressive isolate (ZAG) inoculated controls where up to 100% mortality was observed 15–30 days after inoculation. Such protection involved biochemical interactions between the host plant and AHD since no direct competition or antagonism was revealed between AHD and ZAG. The examination of the accumulation of phenolics and peroxidase activity, two parameters previously reported to be involved in date palm resistance to Foa, indicated that the response to AHD was correlated with the ability of pretreated date palm tissues to establish a faster defence response in the roots of both susceptible and resistant cultivars. Plants pretreated with AHD accumulated higher amounts of phenolics, mainly non‐constitutive hydroxycinnamic acid derivatives, which play a crucial role in date palm defence against Foa, as previously described by our group. These compounds were accumulated along with the constitutive caffeoylshikimic acids. A faster induction of peroxidase activity in response to Foa was also recorded in plants pretreated with AHD. Given the multi‐component nature of these induced responses, AHD could be part of integrated disease management strategies for a sustainable control of the palm tree Bayoud disease.  相似文献   

16.
五种微绿球藻产油和产多不饱和脂肪酸的研究   总被引:1,自引:0,他引:1  
从5种微绿球藻中鉴别出4个高产油藻种和1个产油量很低的藻种。4种高产油微绿球藻在平台期油脂含量最高,占细胞干重的57%以上,其中三酰基甘油的含量占细胞干重的32.4%-45.2%。分析5种微绿球藻细胞的脂肪酸组成及4种高产油藻三酰基甘油中的脂肪酸组成,发现在高产油藻中,总的饱和脂肪酸和单不饱和脂肪酸的比例达到95%以上,多不饱和脂肪酸在5%以下,而在产油量很低的微绿球藻中多不饱和脂肪酸比例达45%以上。高产油微绿球藻三酰基甘油的多不饱和脂肪酸含量在4%以下,是生物柴油的优质原料,而产油量低的微绿球藻可用于提取C20:5脂肪酸(EPA)。    相似文献   

17.
Contrary to earlier reports, well-organized but fewer stomata develop on the lower surface of the leaves of Nelumbo nucifera Willd. during aerial growth. The stomata, however, become obliterated by the readjustment of neighboring epidermal cells. During initial stages of degeneration the guard cells show irregularly thickened walls, disintegrated nuclei, and highly vacuolated cytoplasm. Such abnormal features finally lead to the disappearance of stomata from the lower surface of leaves. The ontogeny, structure and distribution of stomata on leaves, perianth lobes, stamens, receptacles and carpels are described. The stomata are haplocheilic in development and are anomocytic (ranunculaceous) at maturity. The concept of a meristemoid and the significance of this study in taxonomy and phylogeny are discussed.  相似文献   

18.
The impact of cis, trans and cyclopropane fatty acids on membrane fluidity was investigated using batch‐grown Pseudomonas putida P8 and Comamonas testosteroni ATCC 17454. A major difference observed between the two investigated strains is the absence of the ability to synthesize trans‐unsaturated fatty acids in Comamonas. When grown exponentially at 30 °C, a shift to 35 °C increased the trans/cis ratios of the fatty acids of P. putida P8 from 0 to 0.81 and 0 to 1.07, in lipid extracts and cell hydrolyzates, respectively. After prolonged growth followed by nutrient deprivation for 48 h, both at 30 °C, trans fatty acids were absent, but the cyclo/cis ratios rose from 0.1 to 1.55 in lipid extracts, and from 0.1 to 1.54 in cell hydrolyzates. C. testosteroni ATCC 17454 contained no cyclo fatty acids when harvested in the exponential phase after 6 h, whereas after 72 h cultivation, the cyclo/cis ratios rose to 0.49 and 0.47, in lipid extracts and cell hydrolyzates, respectively. Trans fatty acids were never observed in this strain. Increased cyclo/cis and trans/cis ratios correlated with decreased fluidity measured by the fluorescence anisotropy of 1,6‐diphenyl‐1,3,5‐hexatriene (DPH) intercalated in the bilayers of liposomes and by Fourier Transform Infrared (FTIR) spectroscopy of lipids prepared from the cells. The specific effect of cyclopropane fatty acids on membrane fluidity was much smaller than that of trans fatty acids. FTIR‐measurements of intact cells of P. putida P8 confirmed the high potency of trans fatty acids to decrease the fluidity. In cells with induced cyclopropane fatty acid synthesis, the membranes remained more fluidized, indicating the lower importance of these fatty acids for homeoviscosis.  相似文献   

19.
Secondary metabolites in plant defence mechanisms   总被引:24,自引:2,他引:22  
  相似文献   

20.
Impact of long-term salinity and subsequent oxidative stress was studied on cellular antioxidants, proline accumulation and lipid profile of Artemisia annua L. (Sweet Annie or Qinghao) which yields artemisinin (Qinghaosu), effective against cerebral malaria-causing strains of Plasmodium falciparum. Under salinity (0.0–160 mM NaCl), in A. annua, proline accumulation, contents of ascorbate and glutathione and activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT) increased, but the contents of reduced forms of glutathione (GSH) and ascorbate declined. The fatty-acid profiling revealed a major salinity-induced shift towards long-chain and mono-saturated fatty acids. Myristic acid (14:0), palmitoleic acid (16:1), linoleic acid (18:2) and erucic acid (22:1) increased by 141%, 186%, 34% and 908%, respectively, in comparison with the control. Contents of oleic acid (18:1), linolenic acid (18:3), arachidonic acid (22:0) and lignoceric acid (24:0) decreased by 50%, 17%, 44% and 78%, respectively. Thus, in A. annua, salinity declines ascorbate and GSH contents. However, increased levels of proline and total glutathione (GSH + GSSG), and activities of antioxidant enzymes might provide a certain level of tolerance. Modification in fatty-acid composition might be a membrane adaptation to long-term salinity and oxidative stress.  相似文献   

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