DAO 95:175-180 (2011)  -  DOI: https://doi.org/10.3354/dao02346

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Luna stain, an improved selective stain for detection of microsporidian spores in histologic sections

Tracy S. Peterson1,*, Jan M. Spitsbergen1, Stephen W. Feist3, Michael L. Kent1,2

1Department of Microbiology, Oregon State University, 220 Nash Hall, Corvallis, Oregon 97331, USA
2Department of Biomedical Sciences, Oregon State University, Corvallis, Oregon 97331, USA
3Centre for Environment Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Barrack Road, The Nothe, Weymouth, Dorset DT4 8UB, UK

ABSTRACT: Microsporidia in histologic sections are most often diagnosed by observing spores in host tissues. Spores are easy to identify if they occur in large aggregates or xenomas when sections are stained with hematoxylin and eosin (H&E). However, individual spores are not frequently detected in host tissues with conventional H&E staining, particularly if spores are scattered within the tissues, areas of inflammation, or small spores in nuclei (i.e. Nucleospora salmonis). Hence, a variety of selective stains that enhance visualization of spores is recommended. We discovered that the Luna stain, used to highlight eosinophils, red blood cells, and chitin in arthropods and other invertebrates, also stains spores of Pseudoloma neurophilia. We compared this stain to the Gram, Fite‚Äôs acid fast, Giemsa, and H&E stains on 8 aquatic microsporidian organisms that were readily available in our 2¬†laboratories: Loma salmonae, Glugea anomala, Pseudoloma neurophilia, Pleistophora hyphessobryconis, Pleistophora vermiformis, Glugea sp., Steinhausia mytilovum, and an unidentified micro­sporidian from UK mitten crabs Eriocheir sinensis. Based on tinctorial properties and background staining, the Luna stain performed better for detection of 6 of the 8 microsporidia. Gram stain was superior for the 2 microsporidia from invertebrates: S. mytilovum and the unidentified microsporidian from E. sinensis.


KEY WORDS: Luna stain · Selective stains · Microsporidia · Pseudoloma neurophilia · Gram stain · Chitin


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Cite this article as: Peterson TS, Spitsbergen JM, Feist SW, Kent ML (2011) Luna stain, an improved selective stain for detection of microsporidian spores in histologic sections. Dis Aquat Org 95:175-180. https://doi.org/10.3354/dao02346

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