Multigenerational genomic responses to dietary phosphorus and temperature in Daphnia.
Temperature and nutrient availability are both hypothesized to affect organisms at the cellular and genomic levels. In this multigenerational study, Daphnia magna (D. magna) and Daphnia pulex (D. pulex) were maintained at high (20 °C) and low (10 °C) temperatures and nourished with phosphorus (P)-sufficient (50 μmol/L) and P-deficient (2 μmol/L) algae for up to 35 generations to assess the multigenerational impacts on genome size and nucleus size. Analysis by flow cytometry revealed significant increases in nucleus size for both species as well as genome size for D. magna in response to a low temperature. The degree of endoreplication, measured as cycle value, was species specific and responded to temperature and dietary composition. Under dietary P deficiency, D. magna, but not D. pulex, showed an apparent reduction in haploid genome size (C-value). These genomic responses are unlikely to reflect differences in nucleotide numbers, but rather structural changes affecting fluorochrome binding. While the ultimate and proximate causes of these responses are unknown, they suggest an intriguing potential for genomic responses that merits further research.
a Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway.
Marwa
M
Jalal
Nita K
NK
Shala
Marcin W
MW
Wojewodzic
Tom
T
Andersen
Dag O
DO
Hessen
D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000502:physiology; D003621:Daphnia / Q000187:drug effects / Q000235:genetics*; D005434:Flow Cytometry; D059646:Genome Size / Q000187:drug effects*; D016014:Linear Models; D016226:Phosphorus, Dietary / Q000494:pharmacology*; D013045:Species Specificity; D013696:Temperature
D016226:Phosphorus, Dietary
Daphnia; cytométrie en flux; flow cytometry; genome size; nucleus size; phosphore; phosphorus; taille du génome; taille du noyau