Effects of different fixatives on demonstrating epinephrine and ACTH hormones in Tetrahymena

Abstract

The unicellular Tetrahymena produces, contains, and secretes many hormones characteristic of higher animals. We tested three fixatives, formaldehyde, N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDAC), and glutaraldehyde for suitability for immunocytochemical demonstration of epinephrine and adrenocorticotropic harmone (ACTH) in Tetrahymena. Using flow cytometric immunocytochemistry, staining of ACTH was highest after EDAC fixation and that of epinephrine after glutaraldehyde fixation. Using laser scanning confocal microscopy, formaldehyde fixation prevented staining. Glutaraldehyde fixation produced high autofluorescence, which obscured specific staining. After EDAC fixation, ACTH was localized in the ciliary row; however, demonstration of epinephrine was not improved. Our results show that there is no “fixative for any hormone.” Different fixatives are needed to demonstrate different hormones in Tetrahymena.

Key words::

• ACTH
• EDAC
• epinephrine
• glutaraldehyde
• hormones
• Tetrahymena

Acknowledgments

The authors thank Katy Kallay and Angela Kozak for their expert technical assistance.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.