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United States Department of Agriculture

Agricultural Research Service

Title: Versatile and Inexpensive Specimen Holder for High Angle Azimuth Rotation in a Low Temperature Scanning Electron Microscope

Authors
item Wergin, William - COLLABORATOR, USDA, ARS
item Erbe, Eric
item Ochoa, Ronald

Submitted to: Microscopy and Microanalysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 2, 2001
Publication Date: N/A

Interpretive Summary: Nearly all plants important to agriculture are infected by very small organisms such as mites, nematodes and insects. In the United States, these pests cause annual economic losses from decreased food, fiber, and ornamental production estimated to be in the billions of dollars. One problem facing scientists attempting to identify these tiny pests is that their small size results in being poorly seen even with a light microscope. The current study was undertaken to develop a new type of holder, which can be used for magnifying frozen specimens up to 50,000 times in an instrument known as a scanning electron microscope. A small mite is used to illustrate the advantages of this holder. Results indicate that this holder is an inexpensive device that can be used to easily freeze or ship organisms from remote areas. Furthermore, by turning this holder between successive observations, a series of pictures can be obtained that provides 360 degree views of organisms. These advantages indicate that the holder is an important accessory that will be used by scientists to provide more complete descriptions of many small pests such as mites, nematodes and insects.

Technical Abstract: Because of their microscopic size and fragile nature, many minute organisms cannot be easily described with a low temperature scanning electron microscope. For example, it has been estimated that less than ten percent of the mite species have been taxonomically described. Recently, data from a low temperature scanning electron microscopy (LTSEM) has been used to facilitate and complement the information that is obtained with a light microscope. However, the limitations associated with the cold stage on this instrument frequently prevent or compromise the extent of information that can be obtained. This study evaluates the use of fabricated specimen holder designed for a cold stage on a LTSEM. A microscopic mite is used to illustrate the advantages of this holder. Results indicate that a primary specimen holder can be easily designed to accommodate a coin, such as a U.S. penny, which provides an inexpensive specimen holder that can be conveniently stored in liquid nitrogen or shipped from remote sampling locations by using a dry liquid nitrogen shipper. Furthermore, by rotating this holder between successive observations and recordings, a series of micrographs can be obtained that provides 360 degree views of specimens. These advantages indicate that the fabricated holder is an important accessory that can provide more complete data needed for taxonomic descriptions of minute organisms such as mites.

Last Modified: 4/16/2014