CYTOPHOTOMETRIC DETERMINATION OF GENOME SIZE IN THREE SPECIES OF CYCLOPS LAKE BAIKAL (CRUSTACEA: COPEPODA: CYCLOPOIDA)
IN ONTOGENETIC DEVELOPMENT
E.A. Ivankina,1 A.L. Alekseeva,1 V.F. Semeshin,1 L.V. Omelyanchuk,1
I.G. Palchikova,2 N.G. Sheveleva,3 S.V. Kirilchik,3 I.F. Zhimulev 1
1 Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, 2 Technological Design Institute of Scientific Instrument Engineering SB RAS,
Novosibirsk, and 3 Limnological Institute SB RAS, Irkutsk;
1 e-mail: zotkevich@mcb.nsc.ru
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. Cytophotometric method was tested 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 genome size and a high reproducibility, which allows to use
these systems in future work. Here we first discovered chromatin diminution in two endemic Baikal species of Cyclopoida – Acanthocyclops incolotaenia and Diacyclops
galbinus, and estimated it as 94.4–96.1 % and 95.5–96.2 %, respectively. 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 °C.
Key words: Cyclops, chromatin diminution, DNA cytophotometry
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