Composition and ultrastructure of the sporangiospore wall of Rhizopus stolonifer

1988 ◽  
Vol 34 (2) ◽  
pp. 180-186 ◽  
Author(s):  
Maria R. Diaz-Torres ◽  
Felix Claverie-Martin ◽  
Michael J. Geoghegan
Keyword(s):  
Electron Microscopy ◽  
Protein S ◽  
Spore Wall ◽  
High Electron ◽  
Uronic Acids ◽  
Rhizopus Stolonifer ◽  
Thin Sections ◽  
Transmission Electron ◽  
Innermost Layer ◽  
Amorphous Surface

The chemical composition and ultrastructure of the cell wall of Rhizopus stolonifer sporangiospores were determined. Spores were examined by transmission electron microscopy using both thin sections and surface replicas, and by scanning electron microscopy. The spore wall was found to be composed of three layers: (i) a ridged electron-opaque outer layer (10–240 nm thick) occasionally covered by a very thin extra layer; (ii) an electron-transparent layer containing electron-dense areas (160–245 nm thick); and (iii) an innermost layer of relatively high electron density overlaying the plasma membrane (15–40 nm thick). The spore wall had a rough amorphous surface without rodlet fascicles. Chemical analysis showed that the major components were protein, glucan, chitosan, and melanin, followed by smaller amounts of uronic acids, lipids, chitin, and mannose. The protein(s) contained high levels of aspartic acid and glutamic acid, followed by glycine, alanine, lysine, histidine, serine, and by smaller amounts of other amino acids. Melanin was intimately associated with protein and glucosamine.

Teliospore wall structure in Entorrhiza (Tilletiaceae) and its relationship to taxonomy of the genus

1992 ◽  
Vol 70 (10) ◽  
pp. 1964-1983 ◽  
Author(s):  
Brian A. Fineran ◽  
Judith M. Fineran
Keyword(s):  
Electron Microscopy ◽  
Outer Zone ◽  
Spore Wall ◽  
Wall Structure ◽  
Dense Matrix ◽  
Thin Sections ◽  
Transmission Electron ◽  
Layer 2 ◽  
Layer 4 ◽  
Freeze Etching

Spore wall organization in the five species of Entorrhiza (Ustilaginales) has been investigated using thin sections for transmission electron microscopy, supported by light and scanning electron microscopy and some freeze-etching. Material was examined from herbaria, specimens preserved in fixative, and fresh host tissue. The wall has four main layers, numbered 1–4 from the outside to inside of the wall; some layers are further differentiated into zones. Layer 1 in E. aschersoniana, E. caspaiyana, and E. caricicola has two zones: a broad outer zone 2 of dense matrix and a narrow inner zone 1 of less compacted material. Zone 1 is absent in E. cypericola. In E. scirpicola, layer 1 is represented by discontinuous longitudinal ridges. In all spores, layer 2 is composed of a homogeneous electron-dense matrix. Layer 1 in E. aschersoniana, E. casparyana, and E. caricicola is uniformly thick, but in E. cypericola it is broad with an irregular outer margin. In E. scirpicola, layer 2 is differentiated into a distinctive pattern of longitudinal ribs. In all spores of Entorrhiza, layer 3 is resolvable into fine lamellae, corresponding to the mosaic of striations seen after freeze-etching. Layer 3 in Entorrhiza is equivalent to the partition layer described in other Tilletiaceae. Layer 4 has the same organization in all the species, consisting of a very narrow zone 2 abutting layer 3 and a broad zone 1 that forms the rest of the layer. Based on wall structure, E. aschersoniana and E. casparyana represent the most closely related species, followed by E. caricicola, with E. cypericola more distant again. Entorrhiza scirpicola is considered the least related of the species; only its layers 3 and 4 resemble the other species. Key words: Entorrhiza, Tilletiaceae, spore wall ultrastructure, species relationships.

Ultrastructure of the dormant and germinating sporangiospore of Phascolomyces articulosus (Mucorales)

1978 ◽  
Vol 56 (7) ◽  
pp. 747-753 ◽  
Author(s):  
P. Jeffries ◽  
T. W. K. Young
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Freeze Fracture ◽  
Spore Wall ◽  
Wall Layer ◽  
Thin Sections ◽  
Transmission Electron ◽  
Sporangial Wall ◽  
Scanning Electron

Using results obtained with light and scanning electron microscopy of critical-point-dried material and transmission electron microscopy of carbon replicas and freeze-fracture and ultra-thin sections, the structure and germination of the sporangiospore of Phascolomyces articulosus Boedijn is described. The sporangial wall is trilaminate and the ornamented spore wall is two layered. During germination, a new wall layer develops between the plasmalemma and the original spore wall. Sporangial structure is related to that of other members of the Thamnidiaceae and the use of germinating spores of P. articulosus for infection studies of the mycoparasite Piptocephalis unispora is indicated.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

Dislocations in alumina deformed by prismatic slip

1978 ◽  
Vol 36 (1) ◽  
pp. 606-607
Author(s):  
J. Cadoz ◽  
J. Castaing ◽  
J. Philibert
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basal Slip ◽  
Prismatic Slip ◽  
Compression Tests ◽  
Thin Sections ◽  
Burgers Vector ◽  
Maximum Deformation ◽  
Transmission Electron ◽  
Mechanical Thinning

Plastic deformation of alumina has been much studied; basal slip occurs and dislocation structures have been investigated by transmission electron microscopy (T.E.M.) (1). Non basal slip has been observed (2); the prismatic glide system <1010> {1210} has been obtained by compression tests between 1400°C and 1800°C (3). Dislocations with <0110> burgers vector were identified using a 100 kV microscope(4).We describe the dislocation structures after prismatic slip, using high voltage T.E.M. which gives much information.Compression tests were performed at constant strainrate (∿10-4s-1); the maximum deformation reached was 0.03. Thin sections were cut from specimens deformed at 1450°C, either parallel to the glide plane or perpendicular to the glide direction. After mechanical thinning, foils were produced by ion bombardment. Details on experimental techniques can be obtained through reference (3).

Some early history of replica techniques for electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1076-1077
Author(s):  
Robert M. Fisher
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Optical Microscope ◽  
Early History ◽  
Bulk Materials ◽  
Thin Sections ◽  
Transmission Electron ◽  
Reflected Light ◽  
History Of ◽  
Electron Microscopes

By 1940, a half dozen or so commercial or home-built transmission electron microscopes were in use for studies of the ultrastructure of matter. These operated at 30-60 kV and most pioneering microscopists were preoccupied with their search for electron transparent substrates to support dispersions of particulates or bacteria for TEM examination and did not contemplate studies of bulk materials. Metallurgist H. Mahl and other physical scientists, accustomed to examining etched, deformed or machined specimens by reflected light in the optical microscope, were also highly motivated to capitalize on the superior resolution of the electron microscope. Mahl originated several methods of preparing thin oxide or lacquer impressions of surfaces that were transparent in his 50 kV TEM. The utility of replication was recognized immediately and many variations on the theme, including two-step negative-positive replicas, soon appeared. Intense development of replica techniques slowed after 1955 but important advances still occur. The availability of 100 kV instruments, advent of thin film methods for metals and ceramics and microtoming of thin sections for biological specimens largely eliminated any need to resort to replicas.

Dislocations and stacking faults in stainless steel

1957 ◽  
Vol 240 (1223) ◽  
pp. 524-538 ◽  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stainless Steel ◽  
Grain Boundaries ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Thin Sections ◽  
Partial Dislocations ◽  
Transmission Electron

Further experiments by transmission electron microscopy on thin sections of stainless steel deformed by small amounts have enabled extended dislocations to be observed directly. The arrangement and motion of whole and partial dislocations have been followed in detail. Many of the dislocations are found to have piled up against grain boundaries. Other observations include the formation of wide stacking faults, the interaction of dislocations with twin boundaries, and the formation of dislocations at thin edges of the foils. An estimate is made of the stacking-fault energy from a consideration of the stresses present, and the properties of the dislocations are found to be in agreement with those expected from a metal of low stacking-fault energy.

Morphology and ultrastructure of oral strains of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus

1980 ◽  
Vol 30 (2) ◽  
pp. 588-600
Author(s):  
S C Holt ◽  
A C Tanner ◽  
S S Socransky
Keyword(s):  
Electron Microscopy ◽  
Ruthenium Red ◽  
Actinobacillus Actinomycetemcomitans ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Large Numbers ◽  
Haemophilus Aphrophilus ◽  
Ruthenium Red Staining ◽  
Amorphous Surface ◽  
Scanning Electron

Selected human oral and nonoral strains of the genera Actinobacillus and Haemophilus were examined by transmission and scanning electron microscopy. The strains examined were morphologically identical to recognized Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, and Haemophilus paraphrophilus. By transmission electron microscopy, the cells were typically gram negative in morphology, with several strains possessing some extracellular ruthenium red-staining polymeric material. Numerous vesicular structures, morphologically identical to lipopolysaccharide vesicles, were seen to originate from and be continuous with the surface of the outer membrane. Large numbers of these vesicles were also found in the external environment. Scanning electron microscopic observations revealed that both actinobacilli and haemophili possessed surface projections and an amorphous surface material which connected and covered adjacent cells.

Ultrastructure of the Tertiary Envelope of the Cyst of the Tadpole Shrimp Triops longicaudatus (Branchiopoda; Notostraca)

2000 ◽  
Vol 6 (S2) ◽  
pp. 872-873
Author(s):  
James R. Rosowski ◽  
Terry L. Bartels ◽  
James F. Colburn ◽  
Jannell L. Colton ◽  
Denton Belk ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fairy Shrimp ◽  
Distilled Water ◽  
Thin Sections ◽  
Rainfall Events ◽  
Transmission Electron ◽  
Tadpole Shrimp ◽  
Species Specific ◽  
Scanning Electron

Tadpole shrimp inhabit temporary freshwater pools and ponds where their occurrence is largely regulated by rainfall events and water temperature. When dry basins are flooded, cysts of Triops imbibe water and hatch to produce rapidly growing, carapaced larvae. While previous studies show anostracan (fairy shrimp) cyst-surface morphology often species specific, few studies illustrate shell ultrastructure of Triops and none has considered T. longicaudatus. Here we examine the shell of T. longicaudatus (Notostraca) and compare its fine structure to other species of Triops and to that of Artemiafranciscana(Anostraca), which we previously studied.Cysts, produced in culture from Utah broodstock, were purchased from Triops, Inc., 1924 Creighton Rd., Pensacola, FL 32504. Thin sections of cysts were prepared for transmission electron microscopy (TEM) as previously described (Fig. 1). Cysts were also examined with scanning electron microscopy (SEM), dry, whole or fractured (Figs. 2,3), or after imbibition and/or hatching in oxygen saturated, double-distilled water, at 25 ° C.

Neoformation of halloysite on volcanic glass in a marine environment

Clay Minerals ◽  
1987 ◽  
Vol 22 (2) ◽  
pp. 179-185 ◽  
Author(s):  
T. Imbert ◽  
A. Desprairies
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Marine Environment ◽  
Experimental Studies ◽  
Volcanic Glass ◽  
Marine Environments ◽  
Thin Sections ◽  
Transmission Electron ◽  
Glass Shards

AbstractTransmission electron microscopy of ultramicrotomed thin-sections of Pleistocene and Eocene glass shards revealed the neoformation of (i) illite and (ii) halloysite at the glass periphery. According to previous experimental studies, halloysite neoformation in marine environments can occur on glass shards deposited in Si-rich sediments; an excess of Ca tends to inhibit the reaction.

Notizen: Changes in the Iron and Phosphorus Content of Stroma Inclusions during Etioplast-Chloroplast Development in Nicotiana

1977 ◽  
Vol 32 (1-2) ◽  
pp. 139-142
Author(s):  
B. Jülich ◽  
G. Gliem ◽  
A. G. S Jánossy
Keyword(s):  
Conformational Changes ◽  
Phosphorus Content ◽  
Chloroplast Development ◽  
Prolamellar Body ◽  
High Electron ◽  
Formation Processes ◽  
Thin Sections ◽  
X Ray ◽  
Transmission Electron ◽  
Phosphorus Containing

Conformational changes of the thylakoid arrangement during light-dependent etioplast-chloroplast development in cotyledons of Nicotiana clevelandii X N. glutinosa are correlated with a decrease of the iron and phosphorus content in electron-dense stroma inclusions. Parallel to the transformation of the prolamellar body and the stacking process of the thylakoids, both the iron and phosphorus content of the inclusions were found to be reduced. Their elemental composition was analysed by means of the energy-dispersive X-ray microanalysis. Due to their high electron-density these stroma inclusions can be observed by conventional transmission electron microscopy in unstained thin-sections from exclusively glutaraldehyde-fixed material. They seem to be involved in membrane formation processes concomitant with the dispersal of the prolamellar bodies. Thus, the iron and phosphorus containing inclusions were found either closely surrounded by membranes or in the intralamellar space of plastids from plantlets illuminated for 1 - 8 hours. In chloroplasts (illumination period 12 -24 hours) no connections between these inclusions and the thylakoids were noticed.

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