Morphology of the Cyst of Giardia microti by Light and Electron Microscopy1

ABSTRACT. Cysts of Giardia microti, isolated from feces and intestinal contents of Microtus ochrogaster, were examined by light and electron microscopy. These cysts differed morphologically from cysts of other G. duodenalis morphological types in that these cysts often contained two apparently differentiated trophozoites with mature ventral discs. Cysts more closely resembling those reported for G. lamblia and G. muris were in greater abundance in preparations made from intestinal contents and were interpreted as immature cysts. “Multiple fission” cysts, reported in G. muris and G. microti by earlier workers, were not observed; however, endosymbiotic bacteria were found in the cysts of G. microti and may have been responsible for reports of multiple fission in the cysts of Giardia.     

High-Contrast Observation of Unstained Proteins and Viruses by Scanning Electron Microscopy

Scanning electron microscopy (SEM) is an important tool for the nanometre-scale analysis of the various samples. Imaging of biological specimens can be difficult for two reasons: (1) Samples must often be left unstained to observe detail of the biological structures; however, lack of staining significantly decreases image contrast. (2) Samples are prone to serious radiation damage from electron beam. Herein we report a novel method for sample preparation involving placement on a new metal-coated insulator film. This method enables obtaining high-contrast images from unstained proteins and viruses by scanning electron microscopy with minimal electron radiation damage. These images are similar to those obtained by transmission electron microscopy. In addition, the method can be easily used to observe specimens of proteins, viruses and other organic samples by using SEM.     

Morphology of Giardia agilis: observation by scanning electron microscopy and interference reflexion microscopy

The flagellated protozoan, Giardia agilis, was isolated from tadpole small intestine and examined by scanning electron microscopy and interference reflexion microscopy. The general morphology of the G. agilis trophozoite is similar to G. muris and G. duodenalis, but with modifications that reflect its elongated form. Interference reflexion microscopic analysis of attachment of G. agilis reveals a pattern of focal contacts by the lateral crest of the ventral disc, the ventrolateral flange, the lateral shield, and by numerous microvillus-like appendages found along the lateral border of the trophozoite. The pattern of focal contacts was observed to be dynamic; trophozoites were observed to make and break the focal contacts in a relatively short time and to glide along the surface of the substratum without breaking focal contacts.     

拟环纹豹蛛附肢体毛感受器的扫描电镜观察

通过对拟环纹豹蛛(Pardosa pseudoannulata)附肢体毛(触毛、听毛、味觉感觉毛)的扫描电子显微镜观察,发现拟环纹豹蛛的触毛与体表形成的角度为锐角,触毛粗大,毛干较挺立,周围有绒毛环绕,触毛主要分布在蜘蛛体触肢的跗节、胫节和步足的跗节、胫节、端部处,其中第一步足分布最多,其数量较听毛和化学感觉毛多。拟环纹豹蛛的听毛细而长,基本垂直于表皮,毛囊深窝有褶皱,听毛主要分布于触肢和第四步足的胫节上,其余腿节分布较少,不同部位的听毛在形态、长度上没有太大的差别。拟环纹豹蛛的味觉感觉毛基部四周有微微隆起的圆形毛囊,味觉感觉毛大于听毛又小于触毛,四周被绒毛环绕,主要分布于蜘蛛的第一步足和第二步足的跗节胫节处,在触肢和螯肢也有少量分布。     

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 Xiphinema,Longidorus, and Californidorus Stylet Morphology

Stylet ultrastructure of five Xiphinema, four Longidorus, and three Californidorus species was compared by scanning electron microscopy. Morphological differences were seen in the odontophores and odontostyle bases between the genera and some of the species. All Xiphinema studied had well-developed odontophore flanges; the Longidorus species lacked flanges, except for weakly developed ones in L. diadecturus; and none of the Californidorus had flanges. Three sinuses were present in the odontophores of all species. The sinuses varied in length depending upon species. In Xiphinema and Californidorus the odontostyle bases had distinct overlapping collars, but in Longidorus the collars were absent except for L. diadecturus. The odontostyle-odontophore junction from a lateral view appeared as a slanted transverse line in all the species, but in a dorsal view of Xiphinema and Californidorus it was V-shaped. Dorsal longitudinal seams of the odontostyle and odontophore were observed in all the species. The dorsally located odontostyle aperture was ca. 1 μm from the anterior end in all species, except in one Longidorus sp. it was ca. 4 μm from the end.     

Pollen Morphology of Polemoniaceae in Relation to Systematics and Pollination Systems: Scanning Electron Microscopy

Representative pollen grains of each genus and section of the family Polemoniaceae were examined with scanning electron microscopy. Exine pattern diversity within the family is discussed in relation to pollination biology. Pollen data support some previously recognized relationships within the family; in other instances the use of pollen morphology suggests the institution of new associations. The value of pollen morphology as an index to possible phylogenetic interpretations within the Polemoniaceae is discussed.     

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).     

Colonial Morphology of Treponemes Observed by Electron Microscopy

The colonial morphology of three strains of cultivable, nonpathogenic treponemes including a human oral treponeme was examined by light and electron microscopy. Treponema phagedenis strains Kazan and Reiter produced large white colonies on the surface of solid media composed of sterility test broth, 0.9 to 3.1% agar, rifampin, and 12.5% rabbit or horse serum. A human oral treponeme, strain G7201, grew as diffused white zones on 0.9 to 3.1% agar plates. Under the cultural conditions employed agar concentrations slightly affected the time of appearance of colonies of the three strains of treponemes. When the colonies of these three strains were viewed by scanning electron microscopy, differences in their colonial morphology were observed. The 11-day-old colonies of human oral strain G7201 were very small, 5 to 15 μm in diameter, and had a slight irregular border. Kazan treponemes developed circular, entire and low convex colonies. Scanning and transmission electron microscopy revealed that the colonies of Reiter treponemes contained spherical forms almost up to 5 μm in diameter, each consisting of an outer membrane and a treponemal main body. They were very similar to the spherical bodies produced by strain G7201 in sucrose-containing broth.     

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.     

Scanning Electron Microscopy of Thermoplasma acidophilum

The scanning electron microscope was utilized to observe the morphology of the thermophilic, acidophilic mycoplasma, Thermoplasma acidophilum. Upon examination of the surface morphology, the size and shape of this unusual mycoplasma revealed its similarity to the other mycoplasmas that have been investigated.     

Scanning Electron Microscopy of Bacterial Colonies

A technique is described for observing bacterial colony growth. Bacillus cereus, B. subtilis, and B. cereus var. mycoides were grown on strips of dialysis membrane layered on nutrient agar. Microcolonies of the organisms on strips were fixed in Formalin vapor in situ; the strips then were removed from the agar and secured to scanning microscope specimen stubs without markedly disturbing the cellular arrangement. Scanning electron micrographs clearly depict morphology of individual cells, as well as the spatial orientation of cells within the colony. This technique is reproducible, adaptable, and simple.     

Examination of Virus-Infected Cultured Cells by Scanning Electron Microscopy

The scanning electron microscope (SEM) was used to detect changes in morphology of BSC-1 cells after infection with vesicular stomatitis virus (VSV) or herpes simplex virus. The morphological changes of the infected cells were related to the length of time of infection and to the virus used. Extensive alteration to the cytoplasm could be seen 24 and 48 hr after infection with 10 and 320 TCID(50) of VSV. Within 24 hr after infection with 1 TCID(50) of herpes simplex, a few nuclei were swollen. However, 72 hr after infection with 100 TCID(50) of herpesvirus, many nuclei were swollen and appeared in large aggregates, probably representing formation of a polykaryocyte. Corresponding samples stained with May-Grunwald-Giemsa were observed in the light microscope and morphological changes were compared to those seen with the SEM.     

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.     

Scanning Electron Microscopy of Second-Stage Juvenile Cephalic Morphology in Heterodera glycines Races

Scanning electron microscopy (SEM) was used to compare juvenile cephalic morphology of the five described races of Heterodera glycines. Races 1, 2, 3, and 4 were obtained in the United States and race 5 was obtained from Japan. Differences in the gross morphology o f labial discs; ventral, dorsal and lateral lips; amphidial apertures; and fissures on the labial disc o f some specimens were observed. There was considerable interracial and intraracial variation which precluded separation o f juveniles of H. glycines races by SEM.     

17种陆生贝类齿舌的扫描电镜观察及分类学意义探讨

采用扫描电镜观察了3目10科12属17种陆生贝类的齿舌形态.结果 显示,17种陆生贝类齿舌的中央齿均为1列,侧齿12～218列不等,缘齿0～204列不等.中央齿依齿片上小齿数目分为单齿型、三齿型和多齿型;侧齿与缘齿的形态多样,侧齿齿片上小齿数1～6枚不等,缘齿齿片上小齿数1～10枚不等.结合以往报道的38种陆生贝类齿舌...     

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.     

Scanning Electron and Phase-Contrast Microscopy of Bacterial Spores

The three-dimensional immages of free and intrasporangial spores produced by scanning electron microscopy show surface structures not visible by phase-contrast microscopy. Although fine surface detail is not elucidated by scanning electron microscopy, this technique does afford a definitive picture of the general shape of spores. Spores of Bacillus popilliae, B. lentimorbus, B. thuringiensis, B. alvei, B. cereus, and Sarcina ureae have varying patterns of surface ridge formation, whereas spores of B. larvae, B. subtilis, and B. licheniformis have relatively smooth surfaces.