Advantages of environmental scanning electron microscopy in studies of microorganisms
作者:
Scott P. Collins,
Robert K. Pope,
Raymond W. Scheetz,
Richard I. Ray,
Patricia A. Wagner,
Brenda J. Little,
期刊:
Microscopy Research and Technique
(WILEY Available online 1993)
卷期:
Volume 25,
issue 5‐6
页码: 398-405
ISSN:1059-910X
年代: 1993
DOI:10.1002/jemt.1070250508
出版商: Wiley Subscription Services, Inc., A Wiley Company
关键词: Environmental scanning electron microscopy;Algae;Fungi
数据来源: WILEY
摘要:
AbstractMicroorganisms, including bacteria, fungi, protozoa, and microalgae, are composed predominantly of water which prohibits direct observation in a traditional scanning electron microscope (SEM). Preparation for SEM requires that microorganisms be fixed, frozen or dehydrated, and coated with a conductive film before observation in a high vacuum environment. Sample preparation may mechanically disturb delicate samples, compromise morphological information, and introduce other artifacts. The environmental scanning electron microscope (ESEM) provides a technology for imaging hydrated or dehydrated biological samples with minimal manipulation and without the need for conductive coatings.Sporulating cultures of three fungi,Aspergillussp.,Cunninghamellasp., andMucorsp., were imaged in the ESEM to assess usefulness of the instrument in the direct observation of delicate, uncoated, biological specimens. Asexual sporophores showed no evidence of conidial displacement or disruption of sporangia.Uncoated algal cells ofEuglena gracilisandSpirogyrasp. were examined using the backscatter electron detector (BSE) and the environmental secondary electron detector (ESD) of the ESEM. BSE images had more clearly defined intracellular structures, whereas ESD gave a clearer view of the surface.E. graciliscells fixed with potassium permanganate,Spirogyrasp. stained with Lugol's solution, andSaprolegniasp. fixed with osmium tetroxide were compared using BSE and ESD to demonstrate that cellular details could be enhanced by the introduction of heavy metals. The effect of cellular water on signal quality was evaluated by comparing hydrated to critical point dried specimens. © 1993 Wiley‐Liss, I
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