拟南芥苗端发育的超微结构研究

应用高压冷冻及低温脱水电镜技术研究了拟南芥苗端的发生,发育过程。结果表明,苗端发育过程可分为两个阶段,营养苗端和生殖苗端。其中,营养苗端的发育分为二个时期;早期,生长点平均,其结构不形成被子植物苗端所特有的原套一原体结构,后期,生长点隆起,其内部形成典型的原套一原体及组织分区结构。     

菱的腺毛发育及分泌活动的超微结构研究

菱的腺毛由单列圆筒状细胞组成,具有短暂的分泌功能。它们起源于叶片远轴面、叶柄的表皮细胞以及苗端茎轴、花柄的表皮细胞。处于分泌期的腺毛细胞其胞质浓厚,液泡化程度小,细胞具丰富的线粒体、高尔基体。腺毛丧失了分泌功能后即发育成为表皮毛。粘液物质由高尔基体分泌小泡携带至腺毛细胞侧壁,经胞吐与渗透结合的方式分泌至细胞外,粘液的化学成分主要为多糖。     

香榧营养苗端细胞组织分区的超微结构观察

本文研究了榧树(Torreya grandis)成熟植株在季节生长中营养苗端的超微结构变化。各区域细胞的主要区别特征为:顶端原始细胞与亚顶端细胞相接的细胞壁较厚,液泡多分布于细胞游离面,质体中淀粉粒较小;亚顶端细胞壁较厚,液泡较大,质体中淀粉粒较大而多;周缘区细胞质体多不具淀粉粒,液泡也较小,胞间连丝丰富;肋状区细胞被大量的含淀粉质体及液泡占据了大部分空间,胞间连丝丰富。在季节变化的四个时期中,各区域细胞的亚显微结构特征亦不相同。休眠期各区细胞淀粉质体较发达,细胞壁较厚,液泡大;叶扩展期淀粉质体减少或消失;芽鳞形成期出现大量小液泡;新的顶芽形成期液泡增加,核糖体含量较高。讨论了各区域细胞核形态与其细胞活跃性的关系。     

南湖菱果实的营养成分

南湖菱（TrapaacornisNakano）又名无角菱,是我国特产的水生经济植物,因主产浙江嘉兴南湖而得名,并以其果实无角、壳薄、味美而闻名。嫩菱生食,脆嫩甘甜多计,清凉解渴。老菱煮食,滋糯甜润清香,因而近年种植面积和产量均有较大增加,成为杭嘉湖水乡一项有较高经济效益的经济作物。但营养成分未见报道。本文对南湖菱鲜果肉营养成分进行了测定,为进一步开发利用提供实验资料。1．材料与方法1．1材料南湖菱的新鲜果实先后于1994年8月28日及9月12日和10月20日采自浙江嘉兴南湖和杭州,又于1995年Ic月29日采自嘉兴南湖的材料作氨基酸和…     

南方菟丝子质体超微结构、发育与功能的研究

本文研究了南方菟丝子（Cuscuta attstralis R.Br.)各个发育时期质体在茎中的分布,质体种类,超微结构及质体片层的长动态;用荧光分光光度法定性测定了各期的光合能力。结果表明：南方菟丝子体内含有叶绿素,具有叶绿体并能进行光合作用,是一种半寄生植物。叶绿体仅局限于韧皮薄壁细胞中,吸器发育过程中,叶绿体发育达到最完善,叶绿体片层系统的排列不同于一般种子植物而与一种半寄生植物槲寄生相似,菟丝子体内还存在一种“绿色造粉体”,分布于皮层细胞中,菟丝子在苗期光合自养能力和寄生能力均最强,此期是控制菟丝子危害的最适宜时期。     

南湖菱幼苗的生长及其形态结构

南湖菱成熟种子经低处理置水中保存,第２年萌发后,在不同苗期进行摄影与采样,制片观察,结果表明：南湖菱种子无胚乳。胚具典型的两子叶大小不等,胚根结构简化,下胚轴十分发达,主根不发育,不定根发育良好。幼苗期先后出现４种真叶,即：线形叶,带形叶、长椭圆形叶和小菱形叶,各营养器官均有发达的通气组织,韧皮部发育正常,木质部发育相对微弱。种子萌发、幼苗生长所需营养物质主要来自子叶,其次是叶。     

南方菟丝子质体超微结构、发育与功能的研究

本文研究了南方菟丝子（Cuscuta attstralis R.Br.)各个发育时期质体在茎中的分布,质体种类,超微结构及质体片层的长动态;用荧光分光光度法定性测定了各期的光合能力。结果表明：南方菟丝子体内含有叶绿素,具有叶绿体并能进行光合作用,是一种半寄生植物。叶绿体仅局限于韧皮薄壁细胞中,吸器发育过程中,叶绿体发育达到最完善,叶绿体片层系统的排列不同于一般种子植物而与一种半寄生植物槲寄生相似,菟丝子体内还存在一种“绿色造粉体”,分布于皮层细胞中,菟丝子在苗期光合自养能力和寄生能力均最强,此期是控制菟丝子危害的最适宜时期。     

南湖菱的组织培养与快速繁殖(简报)

以南湖菱（Trapa acornis Nakano）种子为外植体,在1／2 MS和NItsch液体培养基上均可萌发成无菌苗;无菌苗带芽茎段在Nitsch＋6-BA 0.5mg／L＋NAA 0.2mg／L＋0.5％活性炭的增殖培养基上,增殖倍数可迭3.4;壮苗后转入1／2 MS＋NAA 0.2mg／L＋1.5％活性炭的生根培养基,生根率80％以上。     

Specific intra-tissue responses to manganese in the floating lamina of Trapa natans L

Plant tolerance to heavy metals requires morpho-physiological mechanisms that are still poorly understood, especially in hydrophytes. This study focuses on the young floating lamina of the rhyzophyte Trapa natans exposed for 10 d to 130 microM Mn. The lamina has the ability to bioaccumulate Mn (> 3000 microg g(-1)). X-ray microanalysis of Mn cellular distribution revealed accumulation in the upper epidermis, in the first palisade layer, and in the idioblasts of the spongy tissue, which were shown with electron microscopy to contain osmiophilic vacuolar deposits, also observed to a minor extent in the control leaves. On the basis of biochemical and histochemical tests, these deposits were attributed to phenolic compounds that were probably able to chelate Mn. Net photosynthesis, photosynthetic pigments, room temperature microspectrofluorimetric analyses, and ultrastructural studies of plastids were performed to evaluate the status of the photosynthetic apparatus. A greater development of thylakoid membranes was observed in plastids of the second palisade and spongy tissue, which, however, did not accumulate Mn. Only the spongy tissue experienced inadequate assembly of PS II, but this did not significantly influence the photosynthetic yield of the whole lamina. It was concluded that T. natans can optimise productivity in the presence of Mn by means of specific intra-tissue responses within the framework of the floating lamina.     

Ultrastructural study on the hypothalamic-hypophysial-adrenal axis in fetal rats

Summary The adrenal glands of decapitated and encephalectomized fetal rats were investigated electron microscopically and compared to those of normal intact fetal rats. Although the adrenal cortices did not show three zones (zona glomerulosa, fasciculata, and reticularis) on the 16.5th day of gestation when the decapitation or encephalectomy was carried out in utero, the zonation was recognized in fetuses operated on the 21.5th day of gestation. The same was true for normal control fetuses. However, cytoplasmic characteristics suggesting steroidogenesis in the cortical cells were reduced to various degrees in the encephalectomized or decapitated fetuses, especially in the latter ones. The change in cytoplasmic appearance was more conspicuous in the inner portion of the cortex. This result suggests that for the maintenance of normal adrenocortical function the hypothalamus may be indispensable even during the prenatal life of rats.     

Effect of benzyladenine on the polypeptide pattern of plastids in excised watermelon cotyledons

We have shown in a previous paper that plastids of watermelon ( Citrullus vulgaris Schrad., cv. Fairfax) cotyledons differentiate into amyloplasts when the cotyledons are grown in water and into prochloroplasts when they are grown in benzyladenine (BA) solution. In the present work we have tested whether this large difference in development of the plastids is accompanied by equally conspicuous changes in their polypeptide pattern. Cotyledons were grown for 4 days in the dark either on distilled water or on 10⁻⁵ M BA. Alternatively they were transfered to 10⁻⁵ M BA after 4 days of growth in water.
Plastids of control cotyledons had a rather simple polypeptide pattern. The only prominent protein bands were the two subunits of ribulose bisphosphate carboxylase (EC 4.1.1.39). Contamination with storage protein was present. Plastids from BA-treated cotyledons had a much more complex polypeptide pattern. No storage protein contamination was observed. Polypeptide bands present only as traces in the control and having molecular weights of 32, 44, 48 and 49 kDa increased in intensity after an exposure of only 6 h to BA. The 32-kDa band seemed to be most dependent on the presence of the hormone. Contrary to what was observed in plastids, BA seemed to have no influence on the polypeptide pattern of mitochondria.     

Ultrastructural study of early development of Nosema algerae in Anopheles albimanus

Early development of Nosema algerae in Anopheles albimanus was studied by electron microscopy. Sporoplasms were observed in the thorax and first three abdominal segments at 1 hr after initial exposure. The first division occurred between 30 and 36 hr. Immature spores were present at 48 hr with mature spores observed at 54 hr. By 60 hr from initial exposure, some of the mature spores had extruded and sporoplasms were seen. By 96 hr, all stages were present and development was no longer synchronous.     

Ultrastructural studies on plastids of generative and vegetative cells in Liliaceae

Summary The behaviour of plastids and mitochondria during the formation and development of the male gametophyte of Chlorophytum comosum has been investigated using electron microscopy. During first pollen mitosis an intracellular polarization of plastids occurs in that the plastids are clustered in the centre of the microspore. The originating generative cell normally lacks plastids. Only in a small number of microspores have plastids been observed near the dividing nucleus of the microspore and later on in the generative cell. These observations agree with the genetic investigations of Collins (1922) on the mode of plastid inheritance which demonstrated a small amount of biparental plastid inheritance in Chlorophytum. The cytological mechanisms underlying plastid polarization during the first pollen mitosis are discussed.     

Ultrastructural studies on plastids of generative and vegetative cells inLiliaceae 3. Plastid distribution during the pollen development inGasteria verrucosa (Mill.) Duval

Summary This paper describes the development of pollen grains ofGasteria verrucosa from the late microspore to the mature two-cellular pollen grain. Ultrastructural changes and the distribution of plastids as a result of the first pollen mitosis have been investigated using light and electron microscopy. The microspores as well as the generative and the vegetative cell contain mitochondria and other cytoplasmic organelles during all of the observed developmental stages. In contrast, the generative cell and the vegetative cell show a different plastid content. Plastids are randomly distributed within the microspores before pollen mitosis. During the prophase of the first pollen mitosis the plastids become clustered at the proximal pole of the microspore. The dividing nucleus of the microspore is located at the distal pole of the microspore. Therefore, the plastids are not equally distributed into both the generative and the vegetative cell. The possible reasons for the polarization of plastids within the microspore are briefly discussed. The lack of plastids in the generative cell causes a maternal inheritance of plastids inGasteria verrucosa.     

Studies on the Pollen Morphology of Trapa from Zhejiang

In the present work, pollen grains of 9 species of Trapa L. from Zhejiang were examined under LM and SEM. They are subsphaeroidal or subprolate, obtuse-triangular in polar view, elliptic or subrounded in equatorial view, and 3-colpate. In the equatorial area, there are three ridge-shaped appendages which elongates along apertures toward two poles and ultimately combined, the ornamentation of other part of exine is minute-verrucate. The genus Trapa is uniform in shape of pollen grains, type and position of apertures and ornamentation of exine, while differentiation can be found in size of pollen grains and shape of ridge-shaped appendage. All of these provide valuable evidence for the classification of Trapa and the verification of their affinities. The validity of Trapaceae, the evolutionarytrends of pollen morphology and the affinities of some species are discussed in this paper.