O. dioica histone gene expression profiles throughout development. qRT-PCR of histone genes from 12 developmental stages (see D): oo (oocytes), 2-8c (2-8 cells), 1h (1h postfertilization (pf)), TB (tailbud, 2.5 h pf), H (hatched, 3 h pf), ETP (early tadpole 5-7 h pf), TS (tailshift metamorphosis, 9-12 h pf), D2/3/4/5/6 (Day 2/3/4/5/6). Expression patterns were classed in 7 profiles. Determinations were performed on two technical replicates on each of two biological population replicates (P1, P2). Histone genes within a cluster were transcriptionally co-regulated and had the same developmental profiles (A, C). A) The majority of canonical histone genes and several replacement variants such as H3.3 were expressed throughout development. B) All canonical histones had additional gene loci exclusively expressed during organogenesis. C) Male-specific expression of the histone gene cluster at locus I. Male- (♂) and female (♀) only samples were included. E) Expression peaking in early tadpoles and D5 was only found for the divergent H2B.4 variant. F) Expression of linker histones H1.4 and H1.3 began 1 h pf, peaked at metamorphosis and decreased to D5. G) Genes for the divergent histone variants H2A.3 and H2B.3 are not clustered but were both predominantly expressed in D3/D4 animals. H) Expression of the gene encoding the divergent variant H2A.4.
Moosmann et al. BMC Evolutionary Biology 2011 11:208 doi:10.1186/1471-2148-11-208