Somatic polyploidy examined by flow cytometry in Daphnia

• Published in: Journal of plankton research Vol. 19; no. 12; pp. 2031 - 2040
• Main Authors: Korpelainen, Helena, Ketola, Matti, Hietala, Jaana
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.12.1997
• Subjects: Biological and medical sciences; Crustacea; Daphnia longispina; Daphnia magna; Daphnia pulex; Freshwater; Fundamental and applied biological sciences. Psychology; Invertebrates; Morphology. Histology. Cytology; Crustacea; Flow cytometry; Polyploidy; Genetic variability; Investigation method; Arthropoda; Cladocera; Daphnia; Phenotypic plasticity; Invertebrata; Branchiopoda
• ISSN: 0142-7873; 1464-3774
• DOI: 10.1093/plankt/19.12.2031

Flow cytometry was used to examine the patterns of somatic polyploidy and to determine the haploid genome sizes in Daphnia. The average proportions of polyploid nuclei among adult animals of D.pulex, D.longispina, D.pulex × D.longispina and D.magna equalled 27, 24, 24 and 24%, respectively. Both interclonal and developmentally regulated variation were observed in the level of somatic polyploidy. Adult animals expressed more extensive polyploidy than did juveniles. The estimates of the haploid genome sizes (C values) of D.pulex, D.longispina, D.pulex × D.longispina and D.magna equalled 0.32, 0.27, 0.26 and 0.37 pg, respectively. These are the smallest genomes reported in crustaceans. Apparently, somatic polyploidy compensates for the loss of genetic material and gives rise to genetic plasticity which may contribute to the considerable level of phenotypic plasticity observed in Daphina.