泡状饶氏藻营养细胞的超微结构研究

本文报道我国特有的一种绿藻门植物－泡状饶氏藻营养细胞的超微结构特征,植物体由3层细胞组成,外层细胞最小,细胞质比较丰富,含有较多的各种细胞器,液泡体积较小,中层细胞具有很大的中央液泡,细胞质成为贴壁的薄层,各种细胞器结构仍清晰可见,内层细胞极度液泡化,细胞质呈现退化状态,周生的片状叶绿体上有许多大小不等的穿孔,使叶绿体呈网孔状外貌,叶绿体主要由许多成对的类囊体组成,叶绿体上往往有几个蛋白核,蛋白核经常被1或2条类囊体穿过,呈现分隔状,本文也报道了泡状饶氏藻的线粒体,质体,内质网,高尔基体和核内微管的结构特征,根据泡状饶氏藻的类囊体形态与Ulva mutabilis非常相似以及蛋白核的超微结构特征,它与石莼科植物可能有较密切的亲缘关系,属于绿藻门中进化的类群。     

STRUCTURE AND FUNCTION OF THE ALGAL PYRENOID. I. ULTRASTRUCTURE AND CYTOCHEMISTRY DURING ZOOSPOROGENESIS OF TETRACYSTIS EXCENTRICA1

The fine structure of the pyrenoid in the mature vegetative cell of Tetracystis excentrica Brown and Bold is described. During zoosporogenesis, the pyrenoid undergoes regression, and the ultrastructure of this process is described in detail. The ground substance undergoes dissolution, and reticulate fibrillar structures appear as well as intruding chloroplast thylakoids. Pyrenoid-associated starch plates diminish, and quantities of starch not associated with the pyrenoid are produced. New pyrenoids appear late in the division cycle after all other major organelles associated with the motile cell have been formed. Zoospore pyrenoids develop in thylakoid-free spaces of the chloroplast which are similar to the DNA-containing regions. The new pyrenoid ground substance, which is loosely fibrillar, arises in close proximity to starch grains which may be formed in the stroma. Then the zoospore pyrenoid produces 2 hemispherical starch plates identical to those in the mature vegetative cell. Zoospore pyrenoids lack the 2 convoluted thylakoids between the starch plates and the ground substance characteristic of those in the mature vegetative cell. Instead, the thylakoids are identical to those of the chloroplast at first, and then develop into a convoluted state in the vegetative cell. Cytochemical tests for DNA, RNA, and protein were made for the cytoplasm, nucleus, nucleolus, and pyrenoid. Conclusive evidence is presented for the presence of RNA in the cytoplasm and nucleolus, DNA in the nucleus, and protein in the pyrenoid. The tests did not conclusively demonstrate the presence or absence of DNA and RNA in the pyrenoid; however, they suggested that small amounts of both DNA and RNA may be present.     

A GREEN DINOFLAGELLATE WITH CHLOROPHYLLS a and b: MORPHOLOGY,FINE STRUCTURE OF THE CHLOROPLAST AND CHLOROPHYLL COMPOSITION1

A green-colored marine unicell has been grown in unialgal culture and its morphology, chloroplast fine structure, and chlorophyll composition investigated. The organism is typical of dinoflagellates in its shape, flagellation, nucleus, mitochondria, and trichocysts. It is similar to Gymnodinium but possesses fine body scales. Chloroplasts and two kinds of vesicles bounded by double membranes, but no organelles obviously identifiable as nuclei or mitochondria, are associated in ribosome-dense cytoplasm separated by a double membrane from the dinophycean cytoplasm. The chloroplasts are unlike any previously reported for dinoflagellates. Each is enclosed by an envelope consisting of a double membrane. Chloroplast lamellae consist of three appressed thylakoids. Interlamellar pyrenoids are present. Pigment analysis reveals chlorophylls a and b but not chlorophyll c. It seems likely that the organism is an undescribed dinoflagellate containing an endosymbiont with chlorophylls a and b and that the reduction of the endosymbiont nucleus and mitochondria has permitted a more initmate symbiosis.     

CHLOROPLAST STRUCTURE IN THE CHLOROMONADOPHYCEAN ALGA VACUOLARIA VIRESCENS1

The chloroplasts of Vacuolaria virescens Cienkowsky are present in large numbers between the cell membrane and the layer of cytoplasm surrounding the nucleus; they are disc-shaped structures ca. 3–4 μM long by 2–3 μM wide. Chloroplast bands consist of 3 opposed thylakoids with adjacent bands frequently interconnected. External to the girdle band is a chloroplast envelope separated from the cytoplasm by endoplasmic reticulum; there is no immediately apparent continuity between this endoplasmic reticulum and the nuclear envelope. Small electron-dense spheres in the chloroplast stroma are thought to be lipid food reserve. Eyespots and pyrenoids are absent.     

Fine Structure of Peridinium westii Lemm., a Freshwater Dinoflagellate

SYNOPSIS. The fine structure of Peridinium westii Lemm., an armoured dinoflagellate collected from Lake Tiberias, is reported. Thick cell walls contain plates, pores and tubules, and are surrounded by an external membrane. The cytoplasm is limited by 3 membranes. Nuclei contain numerous chromosomes with a fibrillar organization. The chloroplast envelope consists of 3 membranes; parallel lamellae, each generally comprising 3 thylakoids, are present. Pyrenoids are present in various forms within the chloroplast structure. Trichocysts are found in cells both as elongate dense cores within a membrane-enclosed sac and as striated rods. An eyespot is found in a plastid containing several thylakoids.     

CACHONINA ILLDEFINA SP. NOV. (DINOPHYCEAE): CHLOROPLAST TUBULES AND DEGENERATION OF THE PYRENOID1

A new species of the dinoflagellate genus Cachonina, C. illdefina sp. nov., was isolated from a red tide off El Capitan State Park, Santa Barbara County, California, in October 1973. The organism is light yellowgreen in color with deeply incised girdle and sulcal grooves. Electron microscopy of the organism, revealed a typical dinokaryotic nucleus. The chloroplasts of the organism are connected, and often contain microtubule-like elements, 25 nm diam. The pyrenoids are characterized as excluding chloroplast thylakoids and ribosomes, although containing an amorphous matrix and numerous tubular invaginations from the cytoplasm. The pyrenoids become detached from the chloroplasts and degenerate into small vesicles. C. illdefina is not bioluminescent.     

Electron Microscopic Observations on the Symbiosis of Paramecium bursaria and its Intracellular Algae*

SYNOPSIS. Observations were made on the fine structure of Paramecium bursaria and its intracellular Chlorella symbionts. Emphasis was placed on the structure of the algae and structural aspects of the relationship between the organisms. The algae are surrounded by a prominent cell wall and contain a cup-shaped chloroplast which lies just beneath the plasma membrane. Within the cavity formed by the chloroplast are a large nucleus, a mitochondrion, one or more dictyosomes, and numerous ribosomes. The chloroplast itself is made up of a series of lamellar stacks each containing 2–6 or more thylakoids with a granular stroma and starch grains intercalated between the stacks. The thylakoid stacks of mature algae are frequently more compact than those of recently divided algae. A large pyrenoid is located within the base of the chloroplast. It is made up of a granular or fibrillar matrix surrounded by a shell of starch. The matrix is bisected by a stack of 2 thylakoids. Prior to the division of the chloroplast the pyrenoid regresses; pyrenoids subsequently form in the daughter chloroplasts thru condensation of the matrix material and the reappearance of a starch shell. This shell appears to be formed by the hollowing-out of starch grains already present in the chloroplast stroma. Accordingly, in this case, starch moves from the stroma to the pyrenoid. The algae are located thruout the peripheral cytoplasm of the Paramecium. Each alga is located in an individual vacuole except immediately following division of the algae when the daughter cells are temporarily located in the vacuole which harbored the parental cell. Shortly thereafter the vacuole membrane invaginates, thereby isolating the daughter algae into individual vacuoles. Degenerating symbiotic algae are seen; because these are frequently found in vacuoles with bacteria, they are presumed to be undergoing digestion. Due to the conditions of culture these algae could have been either of intracellular or extracellular origin.     

LIGHT AND ELECTRON MICROSCOPIC CHARACTERIZATION OF TWO TYPES OF PYRENOIDS IN GONIUM (GONIACEAE,CHLOROPHYTA)1

The single, basal pyrenoids of Gonium quadratum Pringsheim ex Nozaki and G. pectorale Müller (Goniaceae, Chlorophyta) differed in appearance when vegetative colonies were cultured photoheterotrophically in medium containing sodium acetate. Chloroplasts of G. quadratum had distinct pyrenoids when grown in medium without major carbon compounds. However, the pyrenoids degenerated and were markedly reduced in size when such cells were inoculated into a medium containing 400 mg·L^?1 of sodium acetate. No pyrenoids were visible under the light microscope; however, with electron microscopy small pyrenoids and electron-dense bodies were visible within the degenerating chloroplasts, which had only single layers of thylakoid lamellae at the periphery. The chloroplasts subsequently developed distinct pyrenoids and several layers of thylakoid lamellae as the culture aged. In contrast, vegetative cells of G. pectorale always showed distinct pyrenoids when cells were inoculated into medium containing sodium acetate, sodium pyruvic acid, sodium lactate, and/or yeast extract. Therefore, we propose two terms, “unstable pyrenoids” and “stable pyrenoids,” for pyrenoids of G. quadratum and G. pectorale, respectively. Chloroplasts of the colonial green flagellates should thus be examined under various culture conditions in order to determine whether their pyrenoids are unstable or stable when pyrenoids are used as taxonomic indicators. Immunogold electron microscopy showed that the ratios of gold particle density of ribulose-1,5-biphosphate carboxylase/oxygenase (RuBisCO) between pyrenoid matrix and chloroplast stroma in G. quadratum grown in medium with or without sodium acetate were lower than those of G. pectorale. Heavy labeling by anti-RuBisCO was observed in both the electron-dense bodies and pyrenoid matrix of G. quadratum. This is the first electron microscopic demonstration of degeneration and development of both pyrenoids and thylakoid lamellae in the chloroplast as a function of culture condition in green algae.     

La Structure Fine de Chlorogonium elongatum. I. Etude Systematique au Microscope Electronique.

The flagellate Chlorogonium elongatum has been studied in the electron microscope by thin-sectioning techniques. The nucleus, limited by a porous membrane, contains a large nucleolus and some dense masses, probably of chromatin. When the medium is rich or the culture young, the chloroplast has few lamellae, and very few pyrenoids. Inversely, when the medium is poor or jthe culture old, the lamellae are abundant, appearing as piled discs or as a tortuous lamellar system. The pyrenoids are then numerous and are surrounded by starch grains. They are composed of an opaque, finely granular substance, and are never traversed by chloroplast lamellae. The stigma, within the chloroplast, is a circular or oval plate composed of a single tier of dense granulations. The cytoplasm contains mitochondria which are concentrated near the pellicle of the cell, an endoplasmic reticulum, an abundance of ribo-nucleoprotein particles or ribosomes, and a Golgi apparatus. These organelles resemble those observed in other protozoa. The two fiagella are encased in cylinders situated at the anterior end of the cell. At the base of the fiagella are the basal corpuscles or kinetosomes, which repose within a cupule. A dense granule which probably corresponds to the centrosome appears near this structure.     

LIPID MODIFICATIONS RELATED TO ENCYSTMENT AND EXCYSTMENT OF CRYPTOMONAS RUFESCENS SKUJA (CRYPTOPHYCEAE)1

The lipids of Cryptomonas rufescens (Skuja) cells have been analyzed. Quantitative changes of polar and neutral lipids were observed during cell encystment, induced by cultures in a nitrogen-deficient medium. During encystment, thylakoids disappeared while unsaturated galactolipids, characteristics of chloroplast membranes, decreased and neutral lipids accumulated in the cytoplasm. When excystment was induced, the reversal of the phenomenon was observed while thylakoids containing galactolipids were formed.     

A DESCRIPTIVE AND ULTRASTRUCTURAL STUDY OF THE GREEN ALGA,CHLAMYDOMONAS DESMIDII SP. NOV. (VOLVOCALES. CHLAMYDOMONADACEAE) FROM ROCKY MOUNTAIN NATIONAL PARK LAKES 1

The green algal flagellate Chlamydomonas desmidii sp. nov., is described from several lakes in Rocky Mountain National Park, Colorado. The biflagellate cells generally have an hour-glass shape. They possess a single chloroplast with two pyrenoids and a superficial stigma near the center of the cell. Numerous contractile vacuoles occur in the Peripheral cytoplasm and they are arranged in several rings around the nucleus in the constricted region of the cell. Ultrastructural studies verify these features and elaborate upon the structure of the cell.     

几种藻类蛋白核的超微结构研究

应用电镜及免疫电镜技术对莱茵藻、小球藻、条浒苔和紫菜等藻类的叶绿体蛋白核的超微结构及主要组成成分进行了观察和研究。结果显示：不同藻类的蛋白核结构不同,显示了藻类蛋白核的多样性。蛋白核为球形或椭圆形,由蛋白质组成。莱茵藻、小球藻和条浒苔的蛋白核外围被淀粉鞘所包围,而紫菜的蛋白核外围无淀粉鞘而直接被叶绿体的类囊体所包围。淀粉鞘由淀粉组成,淀粉鞘的厚薄与藻体藻龄及增养状态有关系。在蛋白核中央,一般都具有由类囊体形成的孔道,使蛋白核与外界联系,小球藻和条浒苔蛋白核具有1条纵向孔道,而莱茵藻和紫菜为多条孔道。金相免疫技术检测结果显示Rubisco和Rubisco活化酶均在蛋白核及淀粉鞘区域中定位,表明蛋白核具有光合作用功能．     

The lacunar cells and its relationship to interdigitating reticulum cells

Lacunar cells, which are characteristic of the nodular sclerosis type of Hodgkin's disease, were investigated by light and electron microscopy and by enzyme cytochemical and immunohistochemical methods. Characteristic ultrastructural features of the lacunar cells were its size, its multilobated nucleus, and the pale cytoplasm containing only a few organelles. These features distinguish the lacunar cell from typical Sternberg-Reed and Hodgkin cells. Enzyme cytochemically, lacunar cells were weakly positive for acid phosphatase and non-specific esterase. the reaction product was distributed either diffusely or more focally in the cytoplasm. By immunostaining, kappa, lambda, and IgG could be detected in some lacunar cells. The immunostaining pattern was bitypic, which might have resulted from non-specific uptake. All the results of the present study indicate that lacunar cells are non-lymphoid cells. When lacunar cells were compared with cells of normal lymphoid tissue, their ultrastructure was found to be very similar to that of interdigitating reticulum cells. Both cell types showed a bizzarrely shaped nucleus and an electron-transparent cytoplasm with only some vesicles and tubules. Furthermore, lacunar cells and interdigitating reticulum cells exhibited a similar reaction pattern of acid phosphatase and non-specific esterase. Thus, from a cytologic and enzyme cytochemical point of view, a direct relationship between the two cell types is very likely.     

Fine Structure of Yellow-Brown Symbionts (Prymnesiida) in Solitary Radiolaria and Their Comparison with Similar Acantharian Symbionts1

Yellow-brown, algal symbionts varying in diameter from approximately 5 μ m to 20 μ m, associated with solitary Radiolaria with spongiose skeletons (i.e. Spongodrymus sp.), exhibit fine structural features resembling the Prymnesiida (botanical class, Prymnesiophyceae). A large central vacuole is surrounded by a thin layer of cytoplasm containing plastids with lamellae composed of three thylakoids and granular pyrenoids with internal tubules immersed between the thylakoids. The pyrenoids lack internal thylakoid membranes. The nucleus is surrounded by a dilated cisterna of the nuclear envelope that also encloses the plastids and gives rise to saccules of the endoplasmic reticulum. The algal symbionts appear coccoid; hence no flagella nor surface scales were observed. The symbiont fine structure is compared to similar yellow-brown symbionts associated with Acantharia. Thus far, three kinds of algal symbionts have been observed to be associated with solitary Radiolaria: dinoflagellate, prasinomonad, and this apparent prymnesiomonad.     

TOWARD A NATURAL SYSTEM OF SPECIES IN CHLOROGONIUM (VOLVOCALES, CHLOROPHYTA): A COMBINED ANALYSIS OF MORPHOLOGICAL AND rbcL GENE SEQUENCE DATA

The taxonomy of species of Chlorogonium (Volvocales, Chlorophyta) was studied based on comparative light and electron microscopy and DNA sequence data of 23 strains from five major algal culture collections. All of the 23 strains showed pyrenoids under photoautotrophic conditions, but 17 of the 23 exhibited marked reduction in size of pyrenoids, or pyrenoids were absent under photoheterotrophic conditions. The strains could clearly be delineated into six species, C. euchlorum, C. elongatum, C. fusiforme, C. capillatum, C. neglectum, and C. kasakii on the basis of differences in cell shape, number of contractile vacuoles, number and stability of pyrenoids, and ultrastructure of pyrenoids and stigmata. This distinction of species based on morphology was also supported by analyses of rbc L gene sequences. The later strongly showed that each species, C. euchlorum (seven strains), C. elongatum (three strains), and C. capillatum (10 strains), forms a robust clade. Although some morphological differences were noted within different strains of C. euchlorum and C. capillatum, these features were regarded as strain-specific because they were not reflected in the rbc L gene phylogenies. In addition, the rbc L gene trees strongly suggested that C. neglectum and C. kasakii are closely related to each other, consistent with the similarity of the ultrastructure of pyrenoids and stigmata between the two species. However, C. kasakii can be distinguished clearly from C. neglectum by its multiple pyrenoids in the chloroplast and acute anterior and posterior ends in the vegetative cell.     

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。     

小麦与叶锈菌互作过程中细胞程序性死亡的细胞学观察

小麦(Triticum aesetivum)品种洛夫林10和叶锈菌(Puccinia recondita f.sp tritici)小种162、165分别组成不亲和组合与亲和组合。透射电镜观察表明,在小麦与叶锈菌的不亲和组合中,接种后12h,侵染点周围叶肉细胞核变形;接种后24h,核内染色质开始凝聚,并趋于细胞核边缘,同时叶绿体膨胀;接种后48h,核内染色质凝聚加剧,叶绿体开始解体;最终在接种后72h,细胞核、叶绿体完全解体,线粒体开始退化。此外,内质网和液泡共同行使溶酶体功能,吞噬各种细胞器残体及原生质降解组分。以上结果表明：在小麦与叶锈菌不亲和组合的互作过程中,寄主细胞呈现细胞程序性死亡的典型特征。而在亲和组合中,叶肉细胞间隙中可见有大量菌丝蔓延,菌丝与寄主细胞壁接触后分化产生吸器母细胞。菌丝的存在对寄主细胞的超微结构产生一定影响。从接种后24h开始,与菌接触的细胞出现质膜下陷,叶绿体稍显膨胀;在接种后48h、72h,大部分叶绿体膨胀,而其它细胞器无明显变化。     

Ultrastructural changes in major organelles during spermatial differentiation inBangia (Rhodophyta)

Summary The major organelles within the cells of maleBangia atropurpurea (Roth) C. Ag. filaments undergo a series of ultrastructural transformations during the production of spermatia. Initially, thylakoids within the large axial chloroplast develop a reticulate pattern commencing at the central pyrenoid region. Subsequent changes involve loss of lobes and diminution of volume through division; chloroplasts in final stages contain a few dilated, distorted thylakoids and many plastoglobuli. During differentiation the large nucleolus disappears from the nucleus and four masses of chromatin aggregate near the nuclear envelope. Furrows originating from the nuclear envelope form double membranes around each of the chromatin masses and most of the nucleoplasm is eliminated. Several types of fibrillar vesicles are formed during the process and large floridean starch reserves are utilized. Multilamellar bodies and microbody-like structures occur within the cells during certain phases of spermatiogenesis.     

Tetraflagellochloris mauritanica gen. et sp. nov. (Chlorophyceae), a New Flagellated Alga from the Mauritanian Desert: Morphology,Ultrastructure, and Phylogenetic Framing

Morphological, ultrastructural, and molecular‐sequence data were used to assess the phylogenetic position of a tetraflagellate green alga isolated from soil samples of a saline dry basin near F'derick, Mauritania. This alga can grow as individual cells or form non‐coenobial colonies of up to 12 individuals. It has a parietal chloroplast with an embedded pyrenoid covered by a starch sheath and traversed by single parallel thylakoids, and an eyespot located in a parietal position opposite to the flagellar insertion. Lipid vacuoles are present in the cytoplasm. Microspectroscopy indicated the presence of chlorophylls a and b, with lutein as the major carotenoid in the chloroplast, while the eyespot spectrum has a shape typical of green‐algal eyespots. The cell has four flagella, two of them long and two considerably shorter. Sequence data from the 18S rRNA gene and ITS2 were obtained and compared with published sequences for green algae. Results from morphological and ultrastructural examinations and sequence analysis support the placement of this alga in the Chlorophyceae, as Tetraflagellochloris mauritanica L. Barsanti et A. Barsanti, gen. et sp. nov.