[Cytophotometric determination of genome size in two species of Cyclops Lake Baikal (Crustacea: Copepoda: Cyclopoina) in ontogenetic development].

Genome size of Cyclops in cells at early stages of cleavage (up to the 5th division) and in somatic cells were estimated by a static digital Feulgen cytophotometry in order to study the quantitative changes in DNA content during chromatin diminution. Our realization of the cytophotometric method was approbeted on five different digital-imaging systems in blood cells of four vertebrate species. In all cases, we observed a direct correlation of the obtained and known from the literature data on the genome size and a high reproducibility, which allows to use these systems in future work. We also optimized the conditions for DNA hydrolysis of both blood smears, and for two species of Cyclops from the Moscow population, as 30 min in 5 N HCl at 24 degrees C. Here we first revealed chromatin diminution in two endemic Baikal species of Cyclopoida: Acanthocyclops incolotaenia and Diacyclops galbinus estimated the extent ofchromatin diminution in Diacyclops galbinus as 95.5-96.2 %. Cytometric analysis of the third species, Mesocyclops leuckarti, did not reveal obvious chromatin diminution. We also optimized the conditions for DNA hydrolysis of both blood smear preparations, and for two species of copepods from the Moscow population, as 30 min in 5N HCl at 24 degrees C.