David C. Hardie, T. Ryan Gregory, and Paul D.N. Hebert
(DCH and TRG are joint first authors)
Journal of Histochemistry and Cytochemistry 50: 735-749.
Abstract
The study of genome size variation is important from a number of
practical and theoretical perspectives. For example, the
long-standing “C-value enigma” relating to the more than 200,000-fold
range in eukaryotic genome sizes is best studied from a broad
comparative standpoint. Genome size
data are also required in detailed analyses of genome structure and
evolution.
The choice of future genome sequencing projects will be dependent on
knowledge
regarding the sizes of genomes to be sequenced, and so on. To
date,
genome size data have been acquired primarily by Feulgen
microdensitometry
or flow cytometry. Each has several advantages, but also
important
limitations. In the present study, we provide a practical guide
to
the new technique of Feulgen image analysis densitometry. The article
is
designed for those interested in genome size measurements, but not
extensively
experienced in histochemistry, densitometry, or microscopy. As
such,
relevant historical and technical background information is
included.
For easy reference, we provide recipes for required reagents,
guidelines
for cell staining, and a checklist of steps for successful image
analysis.
We hope the accuracy, rapidity, and cost-effectiveness of Feulgen image
analysis
demonstrated in this paper will serve to stimulate further surveys of
genome
sizes in a variety of taxa.