title: Temperature and developmental responses of body and cell size in Drosophila; effects of polyploidy and genome configuration.
abstract: Increased adult body size in Drosophila raised at lower temperatures could be attributed both to an increase in the cell volume and cell number. It is not clear, however, whether increased cell size is related to (or even caused by) increased nuclear volume and genome size (or configuration). Experiments with Drosophila melanogaster stocks (Oregon-R and w1118) raised at 16, 22, 24, and 28°C resulted in larger adult body and wing size with lower temperature, while eye size was less affected. The increase in wing size reflected an increase in cell size in both males and females of both stocks. The nucleus size, genome size, and DNA condensation of adult flies, embryos, and Schneider 2 cells (S2 cells, of larval origin) were estimated by flow cytometry. In both adult flies and S2 cells, both nucleus size and DNA condensation varied with temperature, while DNA content appears to be constant. From 12% to 18% of the somatic cells were tetraploid (4C) and 2-5% were octoploid (8C), and for the Oregon strain we observed an increase in the fraction of polyploid cells with decreasing temperature. The observed increase in body size (and wing size) at low temperatures could partly be linked with the cell size and DNA condensation, while corresponding changes in the haploid genome size were not observed.
authors.affiliation: Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway.
authors.forename: Marwa
authors.initials: M
authors.lastname: Jalal
authors.affiliation: Section for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway.
authors.forename: Tom
authors.initials: T
authors.lastname: Andersen
authors.affiliation: Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway. Electronic address: d.o.hessen@ibv.uio.no.
authors.forename: Dag O
authors.initials: DO
authors.lastname: Hessen
mesh_terms: D000818:Animals; D049628:Body Size; D002467:Cell Nucleus; D048429:Cell Size; D003080:Cold Temperature; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics* / Q000254:growth & development*; D005260:Female; D016678:Genome; D008297:Male; D011123:Polyploidy; D014921:Wings, Animal
keywords: DNA condensation; DNA content; Embryo; Flow cytometry; Polyploidy; Schneider 2 cells