Surface structure variants inDeinococcus radiodurans

The cell wall morphology and the polypeptide composition of two different strains as well as of two spontaneous mutants ofDeinococcus radiodurans have been compared. The two strains differ with respect to the density of their carbohydrate coat. One of the mutants lacks the surface (HPI) layer; the other one is devoid of a carbohydrate coat.     

The fine structure ofPhycomyces

Summary The cytological organization of the apices of sporangiophores and hyphae ofPhycomyces Blakesleeanus was studied by means of light- and electron microscopy. The sporangiophore apex in growth stage I contains a mass of cytoplasm in which is embedded a cluster of lipid globules. Within the plug several zones are differentiated by the grouping of organelles. These zones are not separated by membranes. The most apical zone is low in nuclei and vesicles but rich in mitochondria and dense bodies. Below this zone lies a compact group containing up to several hundred nuclei. Along the midline of the cell, below these nuclei, lies an ovoid region from which vesicles, nuclei and mitochondria are excluded. In this ovoid exclusion zone lies the cluster of lipid globules mentioned above. Lateral to the exclusion zone (i.e. in the peripheral region of the cell) the cytoplasm is rich in nuclei, mitochondria, dense bodies, and especially in developing autophagic vesicles. Of these vesicles, the most mature are found farthest from the cell apex. The region between the exclusion zone and the upper end of the cell's large central vacuole is occupied largely by mature, swollen autophagic vesicles. In addition to the zonal organization described above, microtubules are found to run along the cylindrical cell's axis at a distance from the cell wall, and extend to the extreme apex of the cell. Similar tubules occur in growing hyphae, together with dense bodies, and the hyphal apex contains non-autophagic vesicles that increase in size with distance from the hyphal tip. The hyphae lack the zonation shown by sporangiophore apices. Perinuclear masses of cisternae are described and related to the dictyosomes of higher plants. The findings are discussed in relation to the function of the apices in tip growth and sporulation.This work was supported in part by a National Science Foundation Graduate Fellowship to the author, and in part by grant No. GB 3241 from the National Science Foundation to ProfessorKenneth V.Thimann.     

The fine structure of amylopectin

A critical examination of an enzymic method for determining the ratio of A and B chains in amylopectin leads to a value of ～ 1:1, and not 2:1 as suggested other workers. Partial debranching with pullulanase gave results consistent with earlier suggestions that A chains are predominantly and selectively removed. The ratio of A and B chains in a partially branched amylopectin has been determined, and the results are discussed in relation to possible structures for amylopectin.     

The fine structure of neurons

1. Thin sections of representative neurons from intramural, sympathetic and dorsal root ganglia, medulla oblongata, and cerebellar cortex were studied with the aid of the electron microscope. 2. The Nissl substance of these neurons consists of masses of endoplasmic reticulum showing various degrees of orientation; upon and between the cisternae, tubules, and vesicles of the reticulum lie clusters of punctate granules, 10 to 30 mmicro in diameter. 3. A second system of membranes can be distinguished from the endoplasmic reticulum of the Nissl bodies by shallower and more tightly packed cisternae and by absence of granules. Intermediate forms between the two membranous systems have been found. 4. The cytoplasm between Nissl bodies contains numerous mitochondria, rounded lipid inclusions, and fine filaments.     

The fine structure of pea stomata

Summary The structure and cytology of the guard cells of pea are described. The differential wall thickenings, the radiate arrangement of wall fibrils from the pore site to the anticlinal walls, the lobed and dissected nature of the vacuole, and the fine structure of the plastids are believed to play a significant role in stomatal opening and closing. These findings are correlated with those on corn stomata. Finally a few points with regard to the role of microtubules and vesicles in wall thickenings are discussed.     

The fine structure of odonata chromatophores

The appearance, fine structure and pigment composition of the epidermal chromatophores of mature Austrolestes annulosus (Lestidae) are described and compared with the developing chromatophores of teneral Austrolestes and the mature chromatophores of Diphlebia lestoides (Amphipterygidae) and Ischnura heterosticta (Caenagrionidae). Mature chromatophores contain masses of near spherical light-scattering bodies and larger irregularly shaped pigment vesicles. These effect colour change by migrating in opposite directions, through a system of interconnecting granular endoplasmic reticulum tubules. The pigment, a mixture of xanthommatin and dihydroxanthommatin, has a liquid or gelatinous consistency. Developing chromatophores of teneral insects lack light-scattering bodies and well-defined migratory pigment vesicles, but contain irregular masses of pigment of similar chemical composition.     

The fine structure of silk fibroin

The fine structure of Bombyx mori silk fibroin was investigated by electron microscopy and X-ray diffraction techniques. Examination of silk fibers fragmented with ultrasonic radiation and negatively stained revealed the presence of ribbon-like filaments of well-defined lateral dimensions. Analysis of the breadths of the equatorial reflections in the X-ray diffraction pattern of fibroin yielded similar dimensions for the lateral extent of the crystallites. It is concluded that the crystalline material in B. mori silk fibroin is in the form of ribbon-like filaments of considerable length parallel to the fiber axis and of lateral dimensions approximately 20 x 60 A.     

The fine structure of intracerebral vessels

Summary Intracerebral vessels of the parietal lobe of the rhesus monkey have been examined by electron microscopy with special reference to the relationship between the leptomeninges and the cerebral cortex. A perivascular reticular sheath, in apparent communication with the subarachnoid space surrounds intracerebral arterioles. Myo-endothelial junctions occur in intracerebral arterioles, but no nerve fibres are found in association with such vessels. This indicates that the tone of these vessels may be regulated by chemical mechanisms, possibly mediated through the myo-endothelial junctions.     

The fine structure of Methylococcus capsulatus

The fine structure of Methylococcus capsulatus is described. Particular emphasis is focused on the intracytoplasmic membrane system which is organized as a stacked array of flattened saccules. Each saccule is limited by a 75 A unit membrane and lies in close apposition to adjacent saccules. Methylococcus capsulatus is an obligate methylotroph whose sole source of carbon and energy is methane (or methanol). In this study methane oxidation is demonstrated for the first time in a cell-free system. Work is in progress to determine the cellular organelles which constitute the particulate fraction responsible for methane oxidation. The possible role of the intracytoplasmic membranes in energy transfer is considered in relation to the functions of stacked membrane arrays in other animal, plant and bacterial systems.     

The fine structure of plant tumors

Summary Crown gall cells of several plant species contain considerably more endoplasmic reticulum than their normal or hyperplastic counterparts. This characteristic appears to be stable even in crown gall tissues grownin vitro for many years. No evidence for the presence of an etiological agent was found in any of the crown gall cells, nor was there any evidence of any structure peculiar to these cells. It is not possible at this time to determine if this increase in endoplasmic reticulum is responsible for the increased biosynthetic capacities of tumor cells.     

The fine structure of Micrococcus cyaneus

Summary Micrococcus cyaneus (strain CCM 856) was studied by electron microscopy of thin sections. The cells exhibit different forms (spherical, flattened and pear-shaped) varying in size from 0.6 to 1.1 m. The cell wall consists of one layer 40 to 60 nm thick, the surface of which is covered with, or expands as, a fuzzy material. The cytoplasmic membrane has an asymmetric triple-layered structure with a thickness varying from 8 to 10 nm, and infolds into the cytoplasm as intracytoplasmic membrane systems with configuration, size and number dependent on the fixation conditions. The shape and arrangement of the cells of M. cyaneus differs from that of other micrococci and therefore its taxonomic status should be re-evaluated.     

The fine structure of Psilocybe quebecensis

This work describes the ultrastructural characters ofPsilocybe quebecensis Ola'h &Heim, an hallucinogenic species, the so far known most northernGeophila exhibiting psychodysleptic action.Samplings have been selected on three different parts of the carpophore. Tissues obtained from the gills, central part of the stipe and hyphae below the fruit body of freshly collected carpophores.An accumulation of reserve polysaccharides has been localized in the hyphas of the sub-hymenium and in the mycelium around the stem. We give evidence that two types of pore septum characterise this species. The succession of the sporal tegument of dormant basidiospores and other ultrastructural characters are considered.

---

Résumé Le présent travail précise les caractères ultrastructuraux dePsilocybe quebecensis Ola'h &Heim.A cette fin, les prélèvements ont été faits sur des carpophores sauvages fraîchement récoltés. Trois zones de prélèvement ont été désignées sur le carpophore: lame, partie centrale du pied et hyphe aérien coiffant la base du pied. Ce champignon est une espèce hallucinogène, la plus septentrionale desGeophila Quél., la sectionCaerulescentes Sing., posédant une action psychodysleptique évidente. Nous mettons en évidence la localisation des substances de réserve polysaccharidiques dans les hyphes sous-hyméniales et dans le mycélium entourant le pied, ainsi que les deux types depore septum, la succession du tégument sporal ofdormant basidiospore et autres caractères ultrastructuraux.

---

---

Contribution No. 136 of the Faculty of Agriculture, Laval University, Quebec 10. Canada.     

The fine structure of Chromatium buderi

Summary The fine structure of the phototrophic sulfur bacterium Chromatium buderi was studied in ultrathin sections and freeze-etch preparations.In addition to an intracytoplasmic membrane system common to all species of the Chromatiaceae, C. buderi contained extended lamellar membrane structures possibly due to too high light intensities during growth. The cell wall of C. buderi was found to be covered by a honeycomb-like outer layer consisting of macromolecular wine-glass shaped subunits 60–80 nm by 60 nm in size. This outer cell wall layer appears to be a typical property of the large cell Chromatium species.Contribution No. 3008 of the Woods Hole Oceanographic Institution.