Efficient high-volume cleaning of Aspergillus nidulans cleistothecia using bare fingers.

Abstract

Even seasoned workers find it tedious and sometimes frustrating to remove Hülle cells and stray conidia from Aspergillus cleistothecia by rolling them with forceps across an agar surface, particularly when large numbers must be cleaned. It can be even more challenging to teach the skill to others, especially to a whole class of easily discouraged undergraduates, who may be seeing their first high-mag image of forceps tips at the same time as their first view of a cleistothecium. Creative Commons License This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License. This regular paper is available in Fungal Genetics Reports: http://newprairiepress.org/fgr/vol50/iss1/2 4 Fungal Genetics Newsletter Efficient high-volume cleaning of Aspergillus nidulans cleistothecia using bare fingers. Terry W. Hill, Darlene M. Loprete, Jared A, Castagna, and Samuel O. Weems. Department of Biology and Department of Chemistry, Rhodes College, Memphis, TN 38112 USA. Even seasoned workers find it tedious and sometimes frustrating to remove Hülle cells and stray conidia from Aspergillus cleistothecia by rolling them with forceps across an agar surface, particularly when large numbers must be cleaned. It can be even more challenging to teach the skill to others, especially to a whole class of easily discouraged undergraduates, who may be seeing their first high-mag image of forceps tips at the same time as their first view of a cleistothecium. The tips of forceps are sharp and rough, and the hands that wield them often shaky. A peridium is no match for an ill-aimed poke or slash. We find, however, that cleistothecia can be cleaned very rapidly, with reduced breakage, and with minimal contamination by doing away with forceps altogether and using instead the tools that nature gave us “at our fingertips”. Indeed they are our fingertips themselves. The method is simply to roll cleistothecia briefly and firmly around the surface of a 4% agar plate (with or without diatomaceous earth per Kaminskyj and Hamer, 1996, Fungal Genetics Newsletter 43:71) beneath a well-cleaned fingertip. A few seconds’ rubbing in a circle about an inch in diameter is all that is required. The pressure of the finger is spread evenly, and the cleistothecia only rarely break. For increased efficiency, several cleistothecia can be rubbed at once beneath a single fingertip. Soap-andwater washing, followed by two or three 10-second immersions of the finger in 95% alcohol, with Kimwipe-drying after each immersion, is sufficient in our experience to reduce levels of bacterial contamination to no more than those observed when using flamed forceps – i.e., essentially none. Published by New Prairie Press, 2017