翅果油树根瘤超微结构及其内生菌的观察

作者用光学显微镜,透射电镜和扫描电镜对翅果油树(Eldaeagnus mollis D.)根瘤侵染细胞的超微结构及其内生菌的形态进行了观察研究。翅果油树根瘤中的内生菌具有五种不同的发育形态:菌丝、固氮泡囊、孢囊、孢囊孢子和拟类菌体。内生菌的这些不同形态以及它们在共生固氮中的作用,本文也作了讨论。     

中国鲎变形细胞超微结构的进一步观察

中国鲎的变形细胞可在血液中发育成熟,根据其超微结构,可分为原始变形细胞、幼变形细胞和变形细胞三个阶段。 变形细胞受到外环境或内毒素的刺激后,第一型颗粒出现一系列变化,最终把内容物释放到细胞外。与此同时,细胞表面形成若干胞质性突起,边缘带分散断裂,质膜下和胞质性突起中出现微丝。第二型颗粒无变化,提示它们和血液凝胶化过程无直接关系。     

钩刺目纤毛虫--多核前裂虫的超微结构研究

对钩刺目－土壤纤毛虫－多核前裂虫的超微结构做了透射电镜观察。该种表现了与其他钩刺目种类相似的特征,包括体表分布的粘泡以及扁平的表膜泡,其主要细胞结构特征为：（１）－一层连续的支状内质网将虫体细胞质分成内外两部分;（２）线粒体仅密集于内层细胞质;（３）平行唇突表面的特殊的前列横微管敕纱由胞口发出,沿唇突表层向体后发出并纵行环绕于胞咽外侧,此前列横微管束明显地呈片层状构造;（４）射出体包括位于口区的两     

发菜的显微及亚显微结构的观察

通过光学显微镜、扫描电镜和透射电镜的观察、了解到一条发菜原植体大约由数十万计的念珠状细胞所组成,其藻丝多为单链,但也发现有分枝现象。整个原植体包被着厚薄不均的胶质鞘,外观粗糙,沟稜状起伏,且多裂隙。念珠状细胞为典型的原核细胞。细胞壁有三层结构,中央为色浅的核质区,四周为细胞质区其中散布着大量膜层薄而散乱的类囊体,膜上附有大量 rRNA 和藻胆体颗粒。还发现有膜层密集形如指纹的小类囊体。在细胞质中还分布着结构颗粒,多角体、聚磷酸体等嗜锇物质结构.一般细胞都具有分裂能力,方式多为横缢,先是细胞壁逐渐向中央扩展,最后将母细胞分成两个子细胞.从异形胞的结构特征来看,主要功能是渡过恶劣环境以保存物种。     

阔口尖毛虫形成包囊期间细胞超微结构的观察

阔口尖毛虫形成囊期间,细胞质内出现条带状或管产产的内质网和由不同大小的囊泡组成的包囊壁前体。并且,前体的产生与内质网有关;细胞质内发生自噬泡消化现象,这是细胞将原有结构和能量进行贮存,利用的一种重要形式;大核向细胞质突出形成阿米巴形结构,这与大核向细胞质排出部分核物质有关。     

ULTRASTRUCTURE OF CEPHALEUROS VIRESCENS (CHROOLEPIDACEAE; CHLOROPHYTA). II. GAMETES

Transmission electron microscopic examination of Cephaleuros virescens Kunze growing on leaves of Camellia sp. indicates that gametes are similar to those of Trentepohlia aurea. The gametes bear two, smooth isokont “keeled” flagella containing typical “9 + 2” axonemes and lacking scales. Flagellar insertion is apical and the parallel basal bodies overlap laterally. Each basal body is associated with a separate multilayered structure and component microtubular spline. The latter extends posteriorly beneath the plasmalemma. A nucleus, mitochondria, chloroplasts, and cytoplasmic haematochrome droplets are present. Pyrenoids and eyespots are absent. The subcellular components of C. virescens gametes are comparable to those found in gametes of T. aurea; however, the arrangement of basal bodies and multilayered structures differs slightly from that in T. aurea. Comparison of the fine structure of gametes from Cephaleuros, Phycopeltis, and Trentepohlia clearly indicates that the (1) mode of flagellar insertion, (2) morphology, number, and arrangement of multilayered structures, and (3) keeled flagella are common to these three genera and, thus far, unique among the green algae. Although flagellar insertion is apical, it is not bilaterally symmetrical (sensu stricto), nor is it asymmetrical (cf. Chara and Nitella sperms). The arrangement may be termed “reversed bilateral symmetry” and standardization of the terminology is recommended.     

ULTRASTRUCTURE OF THE DINOFLAGELLATE PERIDINIUM CINCTUM F. OVOPLANUM. II. LIGHT AND ELECTRON MICROSCOPIC OBSERVATIONS ON FERTILIZATION

Fertilization in Peridinium cinctum f. ovoplamtm has been investigated at both the light and electron microscopic levels. Gamete formation occurs when vegetative cells are placed into nitrogen deficient media. The majority of gametes observed possess thin thecal plates; however, some are naked. Gametes have few chloroplasts as compared to vegetative cells, numerous membrane bounded storage bodies, many starch grains, and chromosomes which appear slightly unwound. Gamete fusion is observed to peak 7–10 days after inoculation into nitrogen deficient media. Fusion occurs in an area of the sulcus devoid of reticulate thecal plates at or adjacent to the flagellar pores. A fertilization tube is formed and proceeds to widen along the sulcus. Karyogamy occurs within the fertilization tube before plasmogamy is completed. The resulting planozygote is a two walled structure containing two longitudinal flagella. It enlarges over a 2-week period giving rise to the hypnozygote.     

THE ULTRASTRUCTURE OF GALLS ON THE RED ALGA GRACILARIA EPIHIPPISORA1

A strain of Gracilaria epihippisora Hoyle produces gall-like cell proliferations in culture. These growths can be excised and grown separately, where they retain an undifferentiated morphology and reach 5mm in diameter. The gall tissue consists of a single morphological cell type without any differentiation between surface and internal cells as is characteristic of normal thallus tissue. Gall cells are typically 20–40 μm in diameter and contain the usual complement of organelles and a prominent vacuole, although there are several distinct features. The large multilobed plastids have an extensive proliferation of thylakoid membranes, which form an arrangement of loops and spirals. The thallus outer cell wall layer is highly reduced. The gall growths contain intracellular virus-like particles (ca. 80 nm in diameter) that occur in discrete groups.     

OBSERVATIONS ON THE HABIT,MORPHOLOGY AND ULTRASTRUCTURE OF CEPHALEUROS PARASITICUS (CHLOROPHYTA) AND A COMPARISON WITH C. VIRESCENS1

Cephaleuros parasiticus Karsten, an endophyte of Magnolia grandiflora L. has been examined with light, and scanning and transmission electron microscopy. The discoid thalli are composed of filaments which ramify throughout the leaf tissues beneath the epidermis. Algal filaments do not penetrate host cells, but do produce black leaf spots which have been mistaken for those caused by the fungus Glomerella cingulate (Ston.) Spauld. and Schrenk. Two distinct thallus types occur, often simultaneously on a single leaf. One bears clusters of zoosporangiate branches which seasonally emerge through the ventral (and rarely, dorsal) surface of the leaf. In contrast, the other thallus type bears gametangia which break through the dorsal leaf surface. Zoosporangia and gametangia have never been found on the same thallus. The zoosporangia are smaller than, but almost identical in shape to, those of C. virescens Kunze. Simple plasmodesmata are present in crosswalls and acetolysis indicates that little or no sporopollenin is present in the cell walls. The ultrastructure of biflagellate gametes and quadriflagellate zoospores is virtually indistinguishable from that reported for C. virescens and similar to that reported for Phycopeltis and Trentepohlia. In both gametes and zoospores there are keeled flagella, overlapping and parallel basal bodies, two 3-layered multilayered structures with microtubular splines, and two medial compound microtubular roots. Pyrenoids, eyespots, flagellar and body scales, striated roots (or rhizoplasts), and distal bands are absent. Two presumptive mating structures are present in each biflagellate gamete, and flagellar collars occur in both types of motile cells. The extreme similarity in motile cell ultrastructure revealed in this interspecific comparison parallels that similarity revealed in intergeneric comparisons.     

高氏后异刺线虫肠道和生殖细胞超微结构观察

我们曾经发现雌性高氏后异刺线虫在生殖周期中,虫体的外表形态和器官结构以及细胞核内DNA含量均发生连续的变化。现在进一步对线虫细胞的超微结构进行分析,着重观察核内染色质结构的变化。前三期雌虫肠细胞核内有许多粗大的染色质团块和显著的核仁。Ⅳ期肠核内染色质团块融合成少数球体,而且不断减少,以致消失,单剩下染色质细粒(纤丝切面)。而核仁增大,结构更为复杂。卵巢细胞亦有类似改变,但末见染色质球体。雄虫并无生殖周期,也无上述变化。     

OBSERVATIONS ON THE FINE STRUCTURE OF DICTYOCHA FIBULA EHRENBERG. II. THE PROTOPLAST1

Dictyocha fibula in exponential phase cultures displays a range of morphological variants of which the “sunburst” is most common. In this form, the perinuclear cytoplasm (perikaryon) contains an average of 72 dictyosomes, assorted vesicles, mitochondria, endoplasmic reticulum, and ribosomes. Cytoplasmic processes, globose to irregular, extend on fine cytoplasmic strands from the perikaryon into an extensive, viscous wall, structureless in electron micrographs except for scattered electron-opaque leaflets near the perikaryon. Mitochondria with tubular cristae occur within the globose process and occasionally within the connecting strands. Chloroplasts, with 3-disk lamellar bands and with pyrenoids not crossed by lamellae, are confined to the cytoplasmic processes in the sunburst from. A structure which may be the “flagellum” occasionally occurs attached to the perikaryon. However, no flagellar structures containing microtubules, nor flagellar root structures, have been found.     

OBSERVATIONS ON THE BREEDING OF THE PALILA PSITT1ROSTRA BA1LLEUI OF HAWAII

The behavioural ecology and breeding biology of the endangered Palila Psittirostra bailleui was studied from 1971 to 1975. The most intensive breeding occurred from June to August, and coincided with peak production of mamane Sophora chrysophylla seeds, the bir?s major food source. The Palila was able to make adjustments in its breeding to compensate for yearly differentiation in the timing and abundance of this food supply. Sexual chasing and courtship feeding were the most frequently encountered pre-nesting behaviours. Territory was a mate-defended area, which later in the nesting sequence was confined to the nest site. A total of 26 nests was found; most were placed on larger branches of mamane trees. Nest construction occurred primarily in the morning hours and lasted up to 20 days. Both sexes took part in nest construction, albeit the male role was minimal. Unless the nest was placed in the terminal fork of a tree, it usually contained a large stick base. The modal clutch size was two; eggs were laid early in the morning and in all cases one per day. Incubation sometimes began with the first egg and lasted 15–16 days. Only the female incubated, and she covered the eggs for about 75% of the daylight hours and throughout the night. Egg hatching was asynchronous, with the first young emerging early in the morning and the second not until later that same day. Only the female brooded, and the rate declined until day 15 when essentially it stopped. Both parents fed the young by regurgitation, and the number of feedings per hour decreased slightly over the nestling period. It is thought that insects and finely masticated plant material formed the bulk of the nestling diet until about day 5 when mamane seeds became important. Helpers were found at one nest. Young developed slowly and did not leave the nest until 21–27 days old. It is believed that these prolonged nestling periods were able to evolve because of the (former) absence of ground predators. After fledging, young remained with their parents for at least 30 days. Productivity was regulated by small clutch size, low population numbers and by the length of an individual nesting sequence (in that a pair could potentially raise only one brood each year). The primary reason for the endangered status of this bird appears to be the effect of habitat alteration upon a specialist, coupled with the fact that the small effective breeding population and low dis-persability of the species may have resulted in decreased genetic fitness.