Electron Microscopic Observation of Biological Specimens in Their Native State by Employing Cryogenic Techniques

1972 ◽  
Vol 30 ◽  
pp. 410-411 ◽  
Author(s):  
Tokio Nei ◽  
Haruo Yotsumoto ◽  
Yoichi Hasegawa ◽  
Yuji Nagasawa
Keyword(s):  
Electron Microscopic Observation ◽  
Surface Structures ◽  
Specimen Preparation ◽  
Native State ◽  
Electron Microscopic ◽  
Biological Specimen ◽  
Specimen Holder ◽  
Cold Stage ◽  
Preparation Techniques ◽  
Scanning Electron

In order to observe biological specimens in their native state, that is, still containing their water content, various methods of specimen preparation have been used, the principal two of which are the chamber method and the freeze method.Using its recently developed cold stage for installation in the pre-evacuation chamber of a scanning electron microscope, we have succeeded in directly observing a biological specimen in its frozen state without the need for such conventional specimen preparation techniques as drying and metallic vacuum evaporation. (Echlin, too, has reported on the observation of surface structures using the same freeze method.)In the experiment referred to herein, a small sliced specimen was place in the specimen holder. After it was rapidly frozen by freon cooled with liquid nitrogen, it was inserted into the cold stage of the specimen chamber.

Electron Microscopic Observation of the Longitudinal Organization of Poly (p-Phenylene Terephthalamide) Fibers

1982 ◽  
Vol 40 ◽  
pp. 680-681
Author(s):  
Li Li-Sheng ◽  
L.F. Allard ◽  
W.C. Bigelow
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Microscopic Observation ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Aromatic Polyamides ◽  
Radial Arrangement ◽  
Scanning Electron ◽  
Better Than

The aromatic polyamides form a class of fibers having mechanical properties which are much better than those of aliphatic polyamides. Currently, the accepted morphology of these fibers as proposed by M.G. Dobb, et al. is a radial arrangement of pleated sheets, with the plane of the pleats parallel to the axis of the fiber. We have recently obtained evidence which supports a different morphology of this type of fiber, using ultramicrotomy and ion-thinning techniques to prepare specimens for transmission and scanning electron microscopy.

Comparison of freeze-fractured yeast replicas using conventional TEM and low-voltage field-emission SEM

1989 ◽  
Vol 47 ◽  
pp. 74-75
Author(s):  
William P. Wergin ◽  
Eric F. Erbe ◽  
Terrence W. Reilly
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Low Voltage ◽  
Objective Lens ◽  
Specimen Preparation ◽  
Lens System ◽  
Air Drying ◽  
Preparation Techniques ◽  
Scanning Electron

Although the first commercial scanning electron microscope (SEM) was introduced in 1965, the limited resolution and the lack of preparation techniques initially confined biological observations to relatively low magnification images showing anatomical surface features of samples that withstood the artifacts associated with air drying. As the design of instrumentation improved and the techniques for specimen preparation developed, the SEM allowed biologists to gain additional insights not only on the external features of samples but on the internal structure of tissues as well. By 1985, the resolution of the conventional SEM had reached 3 - 5 nm; however most biological samples still required a conductive coating of 20 - 30 nm that prevented investigators from approaching the level of information that was available with various TEM techniques. Recently, a new SEM design combined a condenser-objective lens system with a field emission electron source.

A Biological Cryosystem for the Scanning Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 414-415
Author(s):  
Zhang zhaohua ◽  
Luo Dong ◽  
Guo Yisong
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Natural State ◽  
Specimen Preparation ◽  
Cold Stage ◽  
Specimen Temperature ◽  
Successful Design ◽  
Scanning Electron

Since early 1970's the use of cold stage on SEM for observation of hydrated samples in their natural state has become more and more popular despite its high cost. Experiences gained from earlier experiments indicate that a successful design should incorporate thefollowing features:1. The specimen temperature should be below −135°C (the recrystallization point of water), lower the temperature, better the results.2. The frozen specimen, the cold block in the specimen preparation chamber, as well as the cold stage should be kept under vacuum at all times to keep them frost free.3. Different specimen preparation processes such as fracturing, coating and sublimation should be possible in one compact preparation chamber .

scholarly journals Scanning electron microscopic observation of the infection process of a Metarhizium strain Ma6 highly pathogenic to Phyllotreta striolata

2018 ◽  
Author(s):  
Jianyu Li ◽  
Mengzhu Shi ◽  
Yuechao He ◽  
Jianwei Fu ◽  
Lizhen Zheng
Keyword(s):  
Body Surface ◽  
Electron Microscopic Observation ◽  
Infection Process ◽  
The Body ◽  
Body Parts ◽  
Pathogenic Microorganisms ◽  
Electron Microscopic ◽  
Highly Pathogenic ◽  
Phyllotreta Striolata ◽  
Scanning Electron

Background. Phyllotreta striolata is a worldwide pest that harms cruciferous vegetables. The use of pathogenic microorganisms to control pests is an important means of biological control. Using pathogenic microorganisms to prevent and control P. striolata has rarely been reported. Methods. In this study, the infection process of a Metarhizium strain highly pathogenic to P. striolata was observed by stereomicroscopyand scanning electron microscopy (SEM). Results.The results showed that the attachment of Metarhizium strain Ma6 to the body surface varied; the conidia distribution was greatest in the tibia of the posterior leg with thick bristles and in the intersegmental abdominal membrane, and the spore distribution occurred least in the smooth and hard portions of the insect’s body. At the start of the infection, Metarhizium strain Ma6 generally grew from the body parts with gaps or connecting spaces such as mouthparts and the thoracic leg base and joints, then the spores germinated with germ tubes and penetration peg, and the penetration peg penetrated the body surface. Ten days after inoculation, the mycelia divided into conidia, and many mycelia and spores covered the entire adult insect’s body. Discussion. Spore germination occurred on the 5th day after inoculation, and many hyphae and spores covered the entire adult insect body within 10 days after inoculation. And the invasion into tissue gaps from the weaker areas is more efficient than intruding from the body hard surface. This may be the reason for the Metarhizium strain Ma6’s high virulence. This study preliminarily clarified the infection ability and invasion approach of a Metarhizium strain against P. striolata, providing evidence for evaluating the strain’s insecticidal effect and application prospect.

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