Anatomy of Ricciocarpus natans, with emphasis on fine structure

The amphibious liverwort Ricciocarpus natans has been investigated with regard to structure and differentiation of cells and tissues.
The differentiation of the tissues was determined starting with their origin from the meristem situated in the median furrow. From this zone there is dorsally a differentiation of epidermis and aerenchyma, and ventrally a differentiation of epidermis and scales. Air–chambers arise schizogenously. They become divided by cells, which grow out from lateral walls and form an internal pore.
Parenchyma (aerenchyma and euparenchyma) cells and epidermis cells (including thallus margin and main scale cells) appear similar in ultrastructure. A characteristic localization of heteropycnotic chromatin close to the nucleolus is recognized. Mic–robodies have an extraordinary cap–shape. Vacuoles often contain electron dense bodies. Lipid droplets occur frequently in the cytoplasm. Storage products are not restricted to a certain tissue. Young scales have an apical papilla cell with many dictyosomes. Chloroplasts of the oilbody idioblast are much smaller than those of unspecialized cells. The rhizoids are smooth–walled.     

Follicles in the Endocrine Pancreas of Myxine glutinosa Studied by Scanning Electron Microscopy

Abstract Scanning electron microscopic studies of the inner surfaces of the follicular cavities in the endocrine pancreas of Myxine glutinosa have revealed two types of follicles. The predominant type of follicles is lined by cells bearing microvilli, while the rare second type has smooth surfaced cavities. It is postulated, that the microvillous cells absorb material stored in these follicles, while the smooth surfaced follicles are disintegrating.     

Scanning Electron Microscopy Analysis of Exine Patterns in Cultivars of Olive (Olea europaea L.)

Scanning electron microscope analysis of exine patterns in thepollen of nine cultivars of the olive tree (Olea europaea L.)has revealed specific differences between them. The differencesinclude variation in size, form and profile of the meshes andin the thickness of the muri. Every cultivar possesses its ownmorphological characteristics which are constant and are foundin successive years. Olea europaea L, olive, pollen, exine patterns     

Agrobacterium tumehciens After in vivo Inoculation of Potato (Sohnum tuberosum L.) (Scanning Electron Microscopy)

Five weeks after the in vivo inoculation of potatoes ( Solanum tuberosum L.) with Agrobacterium. tumefaciens strain B6S3, bacteria were found in the non-differentiated cells of tumors (formed from xylem parenchyma or other living cells), in xylem cells at the site of inoculation, as well as in xylem cells of the adjacent stem.
Bacteria were attached by fibrillar aggregates to the tumor cell walls. They were also attached to a fibrillar mass which arose from agrobacteria connected to this mass in the tumor. Agrobacteria, singly or in pairs, were attached to an electron dense formation (possibly bacterial extracellular polysaccharides) found both inside the xylem cells of the stem adjacent to the tumor and at the site of inoculation. Some A. tumefaciens cells were attached by means of a pedestal-like structure at the inoculation site.
A possible function of the different means of attachment of A. tumefaciens in both nontransformed plant cells and tumors is discussed.     

Transmission Electron Microscopy of Tissue Prepared for Scanning Electron Microscopy by Ethanol-Cryofracturing

Tissue processed for scanning electron microscopy by ethanol-cryofracturing combined with critical point drying was embedded and sectioned for transmission electron microscopy. Study of sections cut in a plane passing through the fracture edge indicated that preservation of cellular fine structure of fractured cells was excellent. Even at the most peripheral edge of the fracture there was no evidence that movement of cytoplasmic components occurred to distort the original structural organization of fractured cells. Lack of cytoplasmic detail in ethanol-cryofractographs has been due more to the nature of the fracturing of the tissue and to the obscuring effects of the metal coating than to structural deformation at the fracture edge or to limitations in resolving power of the scanning electron microscope used.     

Scanning Electron Microscopy of Plant Roots

A glycol methacrylate infiltration and polymerization techniquewas used to prepare clover roots inoculated with Rhizobium forscanning reflection electron microscopy. Root hairs and epidermalcells were coated with many bacteria; some bacteria seemed tobe embedded in the wall surface. Root hair tips were often smoothbut some older root hair surfaces showed a fibrillar meshworkpattern. Small granules c. 0.18 µm diameter were presenton the root hair and epidermal cell walls. The root cap, someroot hairs, and some epidermal cells were covered by an amorphousfilm thought to be the mucigel.     

Visualization of Individual Reovirus Particles by Low-Temperature, High-Resolution Scanning Electron Microscopy

We used low-temperature, high-resolution scanning electron microscopy (cryo-HRSEM) to visualize surface structures on individual reovirus particles. Both intact virions and two forms of subvirion particles—infectious subvirion particles and cores—were examined, and despite some distortion of particles during specimen preparation and viewing in the microscope, the images obtained by cryo-HRSEM exhibited a level of interpretable detail not routinely achieved by other methods without image averaging. Cryo-HRSEM images of discrete reovirus particles were used to characterize and confirm features of the outer protein capsid of this virus by comparison with image reconstructions previously derived from cryotransmission electron microscopy. Distinct surface features attributable to each of the four outer-capsid proteins were identified. In addition, cryo-HRSEM images confirmed that significant changes occur on the surfaces of individual reovirus particles during disassembly and entry of cells and that the reovirus outer capsid is organized as a left-handed T=13 icosahedron. Several unique capabilities and potential uses suggest that cryo-HRSEM has a place alongside other, more established methods for molecular characterizations of virus particles.     

Morphology and Ultrastructure of Staphylococcal L Colonies: Light, Scanning, and Transmission Electron Microscopy

Scanning electron microscopy utilizing critical point drying was used in parallel with light and transmission electron microscopy to study L colonies produced by a stable L-phase variant of Staphylococcus aureus (AH24H).     

Scanning Electron Microscopy of Ascospores of Schwanniomyces

Ascospores of the four recognized species of Schwanniomyces were examined by scanning electron microscopy. Spores of S. alluvius, S. castellii, and S. occidentalis, which were essentially identical, had abundant, long protuberances and wide, thin equatorial rings. The two known strains of S. persoonii differed from the other species as well as from each other. One strain had spores with a wide ring but only a few short protuberances; spores from the second strain were covered with craterlike depressions and had a narrow ring. Also examined were spores of Schwanniomyces hominis (=Saccharomyces rosei) which lacked a ring and were covered with short irregularly shaped protuberances, a finding consistent with the morphology of spores from other strains of S. rosei.     

Cryo-Preservation of Roots for Scanning Electron Microscopy

Fully hydrated roots can be examined in the scanning electronmicroscope after cryo-preservation. Shrinkage associated withdehydration by freeze-drying or critical point drying, to whichroot hairs and secreted mucigel are particularly vulnerable,is avoided. Roots, Lepidium sativum, scanning electron microscopy, cryo-preservation, fully hydrated     

Scanning Electron Microscopy of Intact Trichoderma Colonies

Scanning electron microscopy revealed a clear distinction between hyphal types and enabled early detection of hyphal initiation. Stages in the photoinduced differentiation in Trichoderma leading to conidiation could thus be studied.     

Scanning Electron Microscopy of Freeze-dried Protein Foams

Two proteins of low molecular weight, which bind cadmium and are rich in cysteine were isolated from kidneys of the striped dolphin, Stenella coeruleoalba, and identified as metallo-thioneins I and II. The two isoforms closely resembled horse renal isometallothioneins both in chromatographic behaviors and chemical compositions. The molecular weights of performic acid-oxidized proteins were estimated to be 6,800. Twenty to 21 cysteine residues and about 6 g-atoms of heavy metals (Zn, Cd, Cu, and Hg) were present per mole of each isomer.     

The Vascularization of the Kidneys in Bufo bufo (L.), Bombina variegata (L.), Rana ridibunda (L.) and Xenopus laevis (D.) (Amphibia,Anura) as Revealed by Scanning Electron Microscopy of Vascular Corrosion Casts

Abstract The vascular patterns of the ventral side of the kidneys in Bufo bufo and Rana ridibunda is similar. Strong venulae renales revehentes dominate. In Bombina variegata and Xenopus laevis, however, also many superficially located glomeruli are found at the ventral side. In Xenopus further branching of the renal arteries into afferent arterioles attracts attention. Bundles of delicate afferent arterioles originate within circumscribed areas of the renal artery. The glomerular layer of the kidney is tightest in Bombina, and has its maximal extension in Rana. It covers up to 2/3 of the thickness of the kidney while in the other species studied the glomeruli are restricted to the ventral third of the kidney. Glomeruli with double afferent or efferent arterioles were rarely found in Xenopus. The vascularization of the dorsal side of the kidneys is characterized by the presence of large (Bufo, Rana, Xenopus) or small (Bombina) venulae renales advehentes.     

Hexamethyldisilazane for Scanning Electron Microscopy of Gastrotricha

We evaluated treatment with hexamethyldisilazane (HMDS) as an alternative to critical-point drying (CPD) for preparing microscopic Gastrotricha for scanning electron microscopy (SEM). We prepared large marine (2 mm) and small freshwater (100 μm) gastrotrichs using HMDS as the primary dehydration solvent and compared the results to earlier investigations using CPD. The results of HMDS dehydration are similar to or better than CPD for resolution of two important taxonomic features: cuticular ornamentation and patterns of ciliation. The body wall of both sculpted (Lepidodermeila) and smooth (Dolichodasys) gastrotrichs retained excellent morphology as did the delicate sensory and locomotory cilia. The only unfavorable result of HMDS dehydration was an occasional coagulation of gold residue when the solvent had not fully evaporated before sputter-coating. We consider HMDS an effective alternative for preparing of gastrotrichs for SEM because it saves time and expense compared to CPD.     

Life Cycle of Neurospora crassa Viewed by Scanning Electron Microscopy

Scanning electron microscopy was used to examine the major stages of the life cycle of two wild-type strains of Neurospora crassa Shear and Dodge (St. Lawrence 3.1a and 74A): mycelia, protoperithecium formation, perithecia, ascospores, ascospore germination and outgrowth, macro and microconidia, and germination and outgrowth of macroconidia. Structures seen at the limit of resolution of bright-field and phase-contrast microscopes, e.g., the ribbed surface of ascospores, are well resolved. New details of conidial development and surface structure are revealed. There appears to be only one distinguishable morphological difference between the two strains. The pattern of germination and outgrowth which seems relatively constant for strain 74A or strain 3.1a, appears to be different for each. Conidia from strain 3.1a almost always germinate from a site between interconidial attachment points; whereas the germ tubes of strain 74A usually emerge from or very near the interconidial attachment site. These germination patterns usually do not segregate 2:2 in asci dissected in order. This observation suggests that conidial germination pattern is not under the control of a single gene.     

Correlative Photoactivated Localization and Scanning Electron Microscopy

The ability to localize proteins precisely within subcellular space is crucial to understanding the functioning of biological systems. Recently, we described a protocol that correlates a precise map of fluorescent fusion proteins localized using three-dimensional super-resolution optical microscopy with the fine ultrastructural context of three-dimensional electron micrographs. While it achieved the difficult simultaneous objectives of high photoactivated fluorophore preservation and ultrastructure preservation, it required a super-resolution optical and specialized electron microscope that is not available to many researchers. We present here a faster and more practical protocol with the advantage of a simpler two-dimensional optical (Photoactivated Localization Microscopy (PALM)) and scanning electron microscope (SEM) system that retains the often mutually exclusive attributes of fluorophore preservation and ultrastructure preservation. As before, cryosections were prepared using the Tokuyasu protocol, but the staining protocol was modified to be amenable for use in a standard SEM without the need for focused ion beam ablation. We show the versatility of this technique by labeling different cellular compartments and structures including mitochondrial nucleoids, peroxisomes, and the nuclear lamina. We also demonstrate simultaneous two-color PALM imaging with correlated electron micrographs. Lastly, this technique can be used with small-molecule dyes as demonstrated with actin labeling using phalloidin conjugated to a caged dye. By retaining the dense protein labeling expected for super-resolution microscopy combined with ultrastructural preservation, simplifying the tools required for correlative microscopy, and expanding the number of useful labels we expect this method to be accessible and valuable to a wide variety of researchers.     

Study on Chemosensitive Hairs in Wolf Spiders (Araneae, Lycosidae) by Scanning Electron Microscopy

The occurrence of chemosensitive hairs in some lycosid species is examined. The distribution and shape of such hairs dorsally on the male subadult palpal tarsus and the cymbium are compared. In certain species (e.g. of the genera. Pardosa and Alopecosa) the cymbium has a dense covering of these hairs while there are rather few of these in the male subadult palpal tarsus. The cymbium of Aulonia atbimana has comparatively few chemosensitive hairs dorsally, a condition supposedly related to the web-building habit in this species. Indications are given that the cymbial chemosensitive hairs are involved in the detection of presumed contact sex pheromones produced by the female. Certain intergeneric differences in the shape of the apical part of the cymbial chemosensitive hairs are noted.