I Lomasomi: Loro Probabili Rapporti con la Crescita per Distensione della Parete Cellulare

Abstract

« Lomasomes »: their probable role in the expansion growth of the cell wall. — It was previously reported that lomasomes are present in higher plant cells. In a preliminary comunication Authors described the morfological characteristics of the lomasomes and their position in the cell. It was shown that lomasomes vary in organization which appears to be granular or vescicular and in distribution along the cell wall. Both these characters seemed directly related with the level of cellular differentiation.

In this paper it has been reported that the number of lomasomes per cell was sharply decreased when Avena Coleoptiles were illuminated per 3 hours. During this period of time also the growth of the Coleoptiles was inhibited about 8%. These data seem favorable to the hypothesis that lomasomes are tigtly involved in the mechanisms controlling the expansion growth of the cell wall.     

Plasmalemmasomes and lomasomes in Candida albicans

Candida albicans possesses plasmalemmasomes and lomasomes whose origin, structure and distribution are described. It is suggested that plasmalemmasomes become lomasomes during cell wall synthesis. The endoplasmic reticulum and lomasomes may be regarded as the functional equivalent to the Golgi apparatus in C. albicans and this view is discussed.     

La Flora E La Vegetazione Pel Capo S. Elia (Sardegna Meridionale)

Abstract

Morphological organization of the lomasomes. — From a study on morphological organization of the lomasomes, in Avena coleoptile cells, it has been reported: 1) lomasomes form is quite variable, nevertheless, usually they resemble to a cone having a flattened tip and the base line against the cellular wall. 2) the external border of the lomasoma towards the cytoplasm is represented by the plasma membrane; such external profile results very sinuous and deep invaginations are present. 3) the internal structure is characterized by the presence of an unstructurated matrix containing spherical vescicles, flattened vescicles and tubules all showing an higher density to the electron radiations than the cytoplasmic matrix. Both vescicles and tubules are delimited by a single membrane.     

Electron microscope study of Cryptostroma corticale

An ultrastructural study of Cryptostroma corticale has been carried out with scanning and transmission electron microscopes. The usual features in fungi, as well as features characteristic of the family, were shown. It was noted that lomasomes and myelin-type structures were demonstrated by the two fixatives used. Their significance is discussed.     

Una Struttura Comparabile Con I Lomasomi Nelle Cellule Austoriali di Cuscuta Pentagona Engelm

Abstract

A structure comparable with the lomasomes in baustorial cells of « Cuscuta pentagona » Engelm. — Electron microscopic observations of haustorial cells in « Cuscuta pentagona » revealed to the A. the presence of some vesicular structures, outside the plasma membrane, comparable to the lomasomes of Moore and McAlear. The vesicles usually group in a bag of the plasma membrane and show an envelope consisting of unit membrane; their shape and size are variable and some of them are not well distinct while some others show ribosome-like bodies inside .In the examined cells the plasma membrane shows prominences which are in connection with the vesicle membrane, so that the A. thinks it possible the derivation of the vesicles from the peripherical cytoplasm. The function of these structures is not yet explained; they are only found in non photosyntetic cells, such as some Mycophyta, dark grown « Avena » coleoptiles and dodder's haustorial cells. The previously ultrastructural researchs on dodder have not pointed out lomasomes, which seem to be exclusive of the haustoria, so that it is possible to suppose a connection between the lomasome function and that of the haustoria.     

银耳（Tremella fuciformis）原基分化前期双核菌丝细胞和分生孢子的边缘体与质膜体

本文报道银耳（Ｔｒｅｍｅｌｌａｆｕｃｉｆｏｒｍｉｓ）原基分化前期．在双核菌丝的幼细胞、成熟细胞和分生孢子中,与质膜相关联的两类膜结构──边缘体和质膜体的形成与功能。根据相似结构的存在．支持小泡或多泡体排出质膜之外附在细胞壁上成为边缘体和参于细胞壁合成的假定。银耳原基分化前期．双核菌丝迅速分裂的幼细胞．其质膜内陷产生泡状质膜体,内含数个小泡,或产生膜状质膜体;在成熟细胞中．质膜内陷通常形成回旋的膜结构──膜状质膜体．内含１—２个电子致密小泡．当这两类质膜体脱离质膜进入细胞质后,有的膜层和小泡局部被消化．因此,推断质膜体具有内吞和输送养料的作用。另外．在桶孔隔膜闭塞一侧电子致密度高的细胞质中．还观察到一种罕见的只有单个膜层的质膜体．其内充满３个电子致密小泡．估计它的形成与功能同膜状质膜体相似。作者认为．桶孔闭塞和质膜体的出现是与银耳原基细胞分化有关联的两个重要特征。最后,在成熟细胞中,尚可以观察到质膜体的膜层能够散开形成内质网．因此．内质网也可以来源于质膜体。     

Ultrastructure and Development of Sclerotia of Botrytis cinerea Pers. in vitro

The development of sclerotia of Botrytis cinerea was examined at four stages during their maturation. The surface structure developed a network of profusely branched hyphae through their coalescence to a compact sclerotial body which was maturated by the deposition of melanin pigment. A characteristic feature of the hyphal cells of B. cinerea during the later stages of development was the presence of paramural bodies (plasmalemmasomes and lomasomes). Electrondense bodies with a limiting double-membrane congregated against the transverse septa of hyphal cells as sclerotia matured and may migrate from cell to cell through septal pores. We suggest that these and the lipid bodies found in hyphal cells may have a storage function in the resting sclerotia.     

Ultrastructural localization of antigenic determinants conserved during Perkinsus atlanticus trophozoite to prezoosporangium differentiation

Trophozoite, prezoosporangium and zoospore are the 3 main developmental stages that form the life cycle of protozoa of the genus Perkinsus. Several studies have shown that the differentiation of Perkinsus species from the trophozoite to the prezoosporangium stage involves a substantial modification of the antigenic characteristics of these molluscan parasites. With the aim of determining the presence and distribution of antigenic determinants conserved during trophozoite to prezoosporangium differentiation, a polyclonal serum was raised against trophozoites of P. atlanticus purified from parasitized gills of the clam Tapes semidecussatus. Immunocytochemical analyses showed that the serum generated against P. atlanticus trophozoites strongly cross-reacted with the prezoosporangium stage. Immunogold electron microscopy studies revealed that the granular component of the nucleolus, chromatin, cell wall, plasmalemma, lomasomes and vacuolar membrane are the main subcellular structures where the immunodominant epitopes consistently expressed by trophozoites and prezoosporangia are located. Furthermore, analysis of the immunogold staining pattern revealed that the labelling density obtained for prezoosporangia in the nucleolus, cell wall, plasmalemma and lomasomes was significantly higher than that obtained for trophozoites. The most immunoreactive structure in trophozoites was the granular component of the nucleolus, whereas in prezoosporangia it was the lomasome. Interestingly, the main antigenic compartment of P. atlanticus, considering both developmental stages, was the lomasome of the prezoosporangium. These findings show that P. atlanticus trophozoite to prezoosporangium differentiation is accompanied by significant qualitative and quantitative changes in the ultrastructural distribution of the immunodominant antigens shared by these 2 developmental stages.     

Electron microscopic studies of saprobic and parasitic forms of Coccidioides immitis

During studies of both saprobic and parasitic cycles of Coccidioides immitis, we found that the hyphae contained septa with simple pores, Woronin bodies, pinocytotic vesicles and/or lomasomes. The alternating thallic arthroconidia were released by fracturing of the adjacent sterile cells. The endospores were formed by progressive cleavage of the spherules. The taxonomic classification of C. immitis still remains obscure.     

Mise en évidence par le cryodécapage de lomasomes dans la basidiospore de Hypholoma fasciculare (Huds. ex Fr.) Kummer

Summary Lomasomes were shown to be present in mature basidiospores of Hypholoma fasciculare using the freeze-etching technique. Grooves in the plasmalemma were also generally observed. It is suggested that lomasomes are related to the elaboration of the chitinous spore wall and, in accordance with the views of Campbell, plasmalemma grooves are connected with the melanisation of its outer parts.     

Ultrastructure of Cryptococcus neoformans in the cerebrospinal fluid of a patient with cryptococcal meningitis

The ultrastructure of Cryptococcus neoformans in the cerebrospinal fluid, which was obtained from a patient suffering from systemic lupus erythematosus and cryptococcal meningitis, before treatment and on the 10th and 20th day after the start of treatment was studied. Numerous cryptococci were detected in the cerebrospinal fluid before treatment. However, in most of them their biological activity was low and their organelles were not clear. A few yeasts preserved well their organelles. Such cells showed a tendency to develop vesicular membrane structures (lomasomes) touching the internal part of the cell wall. In the cerebrospinal fluid on the 20th day all of the yeasts were dead, even though numerous yeasts were observed by an India-ink method. At this time no colonies were recovered from the fluid.     

The fine structure of psychrophilic and mesophilic Rhodotorula rubra

Transmission electron microscopy of thin sections of two mesophilic and a psychrophilic Rhodotorula rubra revealed structures normally associated with yeast. The capsule of all three strains was thicker in the cells grown in glucose than those grown in glucose-free media. The cell wall of all three strains showed more lamellae in the cells grown in a medium containing glycerol. Budding was of the Rhodoturula type. Endoplasmic reticula running parallel to the nucleus were commonly observed in the psychrophiles but not in the mesophiles. In the psychrophile, in association with the plasmalemma, lomasomes and plasmalemmasomes were observed. Giant mitochondria were commonly seen in the cells grown in a fermentable carbohydrate-free medium. Vacuoles were mostly empty.     

Fine Structure of Established Callus Cultures of Taraxacum officinale Weber

The nodular, brown callus cultures of Taraxacum officinale growslowly on a modified White's medium. A section of nodule revealsa meristematic layer bounded both internally and externallyby parenchymatous tissue. No other types of tissue occur withinthe callus. The cells of the inner parenchyma are often compressedand senescing, whereas in the outer tissue localized de-differentiationapparently contributes to the development of new nodules duringcallus growth. Fine-structural observations of both meristematic and parenchymatoustissues show the normal complement of higher plant cell organellesexcept for the apparent absence of cytoplasmic microtubules.The rough endoplasmic reticulum cisternae are often alignedparallel to the cell wall or in whorls and may show pores, thusresembling annulate lamellae. Numerous lipid bodies, up to 7µm wide, occur and these are sometimes invested by arraysof apparently membranous material. The mitochondria are frequentlyhighly branched and often show a scalariform arrangement ofcristae. The plastids show few internal membranes despite cultureof the callus under continuous illumination. Lomasomes are very common in all cells and in the parenchymatissue membranous wall bodies also occur. The latter bodiesare much larger than lomasomes and consist of wall overgrowthsin which vesicular, myelin-like or isolated membranous elementsare enmeshed in fibrillar material. It is suggested that membranouswall bodies may originate from the amalgamation and subsequentproliferation of several adjacent lomasomes. Taraxacum officinale Weber, dandelion callus cultures, fine structure     

ULTRASTRUCTURE OF THE CONCHOCELIS STAGE OF THE MARINE RED ALGA PORPHYRA LEUCOSTICTA1

The ultrastructure of the Conchocelis or filamentous stage of Porphyra leucosticta was investigated. Each cell contains 1 or 2 parietal, stellate chloroplasts with a single pyrenoid in each chloroplast. The centrally located nucleus is irregularly shaped and contains 1–2 nucleoli. The cytoplasm has typical floridean starch grains and nonmernbrane-bound lipid bodies. The cell wall is divided into an outer and an inner wall. Many lomasomes are associated with the cell membrane. Pit connections are found between cells, and their taxonomic significance is discussed.     

Fine structure of resting spore formation and germination in Entomophthora virulenta

The fine structure during the formation and germination of resting spores of Entomophthora virulenta is described. There were many microbodies in contact with oil droplets, and the microbodies appeared to participate in spore germination. The mature resting spore had an epispore layer with two regions and an endospore layer with five regions. Dictyosomes, numerous vesicles, and lomasomes were produced during the formation of the endospore layer. Prior to spore germination, the single large oil droplet separated into numerous small oil droplets, and the new cell wall was formed beneath the endospore layer which gradually disintegrated possibly by enzymatic actions. The germ tube perforated the epispore layer mainly by mechanical pressure.     

Fine structure of resting and germinatingPenicillium chrysogenum conidiospores

Summary The fine structure of resting and germinating conidia ofPenicillium chrysogenum has been examined by electron microscopy. In addition to enlargement of the cells, a number of changes in ultrastructure become evident as morphogenesis proceeds. The newly synthesized germ tube is continuous with the corresponding layers of the conidial wall. Some conidial wall layers, however, do not extend into the hyphal wall. Several sections showing initial septum synthesis suggest that a septal pore is not a necessary structural entity. A characteristic orientation of the initial septum formed after germination is described. Aside from numerical considerations, no significant changes occur in nuclei, mitochondria, or ribosomes. The electron micrographs illustrate the presence of spherosomes, lomasomes, and nucleoli; the possible significance of these structures is discussed.     

Structure of the cell wall of Pythium debaryanum

The structure of hyphal walls of Pythium debaryanum was investigated by electron microscopy of shadowed replicas and thin sections, before and after digestion by snail gut enzymes or by 1 n HCl at 100 C for 1 hr, and by X-ray diffraction. We found that the wall had two phases, one composed of microfibrils of unknown composition and a second consisting of an amorphous matrix, part of which stained like protein with potassium permanganate and part of which was removed by snail-gut enzymes. In the microfibrillar phase, there were two layers; an outer, thicker layer of randomly disposed microfibrils and an inner, thin layer of microfibrils oriented parallel to the hyphal axis. As in Neurospora crassa, the amorphous phase included a branching system of pores, 40-80 A in diameter. Unlike N. crassa, the cytoplasm of Pythium showed Golgi bodies frequently, and many lomasomes were observed between the cytoplasmic membrane and the wall. The relations between these organelles and the mechanism of wall formation in Pythium are not understood.     

毛竹茎秆纤维发育过程的超微结构观察

利用透射和扫描电镜观察了毛竹(Phyllostachys edulis(Carr.)H.De Lehaie)茎秆纤维发育过程中的超微结构变化.在纤维细胞初生壁形成期,细胞质中线粒体、内质网、高尔基体等细胞器数量有明显的增加,出现大量的由内质网与高尔基体分泌形成的运输小泡,周质微管平行分布于质膜内侧,出现环状片层结构,并在细胞壁与质膜之间出现壁旁体结构.随着次生壁的逐渐形成,细胞质中细胞器逐渐地解体并出现多泡小体;纤维细胞核出现染色质凝聚并边缘化,但在8年生的纤维中可以持续存在;在纤维次生壁形成的整个阶段都存在与周围细胞相联系的胞间连丝和运输小泡;次生壁在前4年加厚明显,以后加厚程度减缓,但可以持续很长一段时间,并随着加厚出现宽窄交替的多层结构.结果表明,线粒体、内质网、高尔基体和壁旁体等细胞器与周质微管一起参与了初生壁和次生壁早期的形成;纤维细胞次生壁的形成过程就是一个漫长的程序性细胞死亡(PCD),而PCD的产物与胞间连丝一起参与了次生壁的形成与加厚;染色质凝聚并边缘化的细胞核与胞间连丝的持续存在,证明毛竹茎秆纤维细胞是一种典型的长寿细胞.     

毛竹茎秆纤维发育过程的超微结构观察

利用透射和扫描电镜观察了毛竹（Phyllostachys edulis (Carr.) H. De Lehaie）茎秆纤维发育过程中的超微结构变化。在纤维细胞初生壁形成期,细胞质中线粒体、内质网、高尔基体等细胞器数量有明显的增加,出现大量的由内质网与高尔基体分泌形成的运输小泡,周质微管平行分布于质膜内侧,出现环状片层结构,并在细胞壁与质膜之间出现壁旁体结构。随着次生壁的逐渐形成,细胞质中细胞器逐渐地解体并出现多泡小体;纤维细胞核出现染色质凝聚并边缘化,但在8 年生的纤维中可以持续存在;在纤维次生壁形成的整个阶段都存在与周围细胞相联系的胞间连丝和运输小泡;次生壁 在前4 年加厚明显,以后加厚程度减缓,但可以持续很长一段时间,并随着加厚出现宽窄交替的多层结构。结果表明,线粒体、内质网、高尔基体和壁旁体等细胞器与周质微管一起参与了初生壁和次生壁早期的形成;纤维细胞次生壁的形成过程就是一个漫长的程序性细胞死亡（PCD）,而PCD 的产物与胞间连丝一起参与了次生壁的形成与加厚;染色质凝聚并边缘化的细胞核与胞间连丝的持续存在,证明毛竹茎秆纤维细胞是一种典型的长寿细胞。     

Ultrastructure of basidiospores and mycelium of Lenzites saepiaria

Hyde, James M. (University of Mississippi Medical School, Jackson), and Charles H. Walkinshaw. Ultrastructure of basidiospores and mycelium of Lenzites saepiaria. J. Bacteriol. 92:1218-1227. 1966.-Ungerminated and germinated basidiospores and 2-day-old mycelial cultures of Lenzites saepiaria were similar in their fine structure. Fixation with glutaraldehyde, followed by osmium tetroxide, was far superior to permanganate. Cell organelles were seen in cytoplasm of spores and hyphae, and clamp connections were abundant in hyphal elements. Numerous lomasomes, vesicular bodies, and complex concentric membranes occurred in the cytoplasm and were often associated with the cell membrane or the dolipore membrane (parenthesome) of the septum. Endoplasmic reticulum was not found, but numerous ribosomes were seen; polyribosome groupings were frequently noted. The nucleus was bounded by a double membrane which contained few pores. Germinating spores exhibited one or more large osmiophilic bodies in association with a vacuole and membranous elements. Other than possessing a thin wall, the emerging germ tube was similar in structure to the parent spore.