Fig. 7
Transcriptional changes during oogenesis underlie sphk2MZ resistance to sphingosine buildup.
Oocytes isolated from wildtype and sphk2-/- female fish show (A) increased sphingosine (Sph) levels in mutant oocytes associated with loss of S1P (Sph-1P) with (B) no difference in total ceramide levels. (C) Oocytes derived from sphk2-/- oocytes showed significant upregulation of cers2b transcripts, as imaged following in situ hybridization. Note that signal in the wildtype oocytes was equivalent to background staining using a sense-strand control probe. (D) Correspondingly, embryos derived from sphk2-/- females (right) showed relative tolerance to sphingosine accumulation when compared to those from wildtype females (left) when cultured in medium with 5 uM sphingosine. For (A, B) . results are averaged from three independent experiments using at least 50 embryos per measurement. For (C,D), representative embryos are shown, n > 25, from at least three independent experiments.