A simple and effective method for assessing chromatin diminution values in copepods using qPCR

Abstract

The value of chromatin diminution (CD) in different species of freshwater cyclopoid copepods can differ significantly. The biological and evolutionary roles of these differences remain unclear. To expand the knowledge on CD distribution and magnitude in this group of copepods, a quick method for its evaluation was required. This study proposes a simple approach for CD assessment in copepods using quantitative realtime PCR (qPCR). The magnitude of changes in the genome size was assessed by comparing fluorescence curves of qPCR fragments of target genes for pre- and post-diminution materials. The method was tested on four cyclopoid copepods species. In Cyclops kolensis, CD was assessed as 95.3 ± 1.2; in Acanthocyclops vernalis it was assessed at 94.6 ± 0.8%; at C. insignis, it was 82.3 ± 5.2%; and for the first time, CD was found in Megacyclops viridis at 91.1 ± 2.6%. The advantages of our approach are its rapidity, simplicity and minimal requirements of materials studied.