The use of 2-[2’-hydroxy-5’-aminophenyl]benzoxazole (HAMBO), a new fluorochrome for the morphological analysis of Fonsecaea pedrosoi ATCC 46428 using a microculture technique

Abstract

Fluorochromes have been employed in fungi for many reasons, including the evaluation of cell feasibility, growth, physiological monitoring during stress, antifungal resistance and diagnosis of infections in clinical specimens. This study evaluated the incorporation of 2-[2’-hydroxy-5’-aminophenyl]benzoxazole (HAMBO) into the vegetative and reproductive mycelia of Fonsecaea pedrosoi. Fonsecaea pedrosoi (strain ATCC 46428) was incubated for 15 days on a microculture of potato dextrose agar containing HAMBO. Slides with fungal growth were analyzed using epifluorescence microscopy. The fluorochrome impregnated the surface of the cellular material. The detailed external definition of the microstructure allowed for the differentiation of hyphae and conidia and for the detection of changes in fluorochrome deposition and membrane thickness in the cellular elements investigated. HAMBO has intrinsic fluorescence, lack of functional groups susceptible to enzymatic hydrolysis, and slow photofading, which make it suitable for microscopic analysis when it is necessary to expose material to UV light for a long period.