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Summary: Oscillations in mRNA and protein of circadian clock components can be continuously monitored in vitro using synchronized cell lines. These rhythms can be highly variable due to culture conditions and are non-stationary due to baseline trends, damping and drift in period length. We present a technique for characterizing the modal frequencies of oscillation using continuous wavelet decomposition to non-parametrically model changes in amplitude and period while removing baseline effects and noise. Availability: The method has been implemented as the package waveclock for the free statistical software program R and is available for download from http://cran.r-project.org/ Contact: thomas.price@iop.kcl.ac.uk Supplementary information: Supplementary figures are available at Bioinformatics online. [ABSTRACT FROM AUTHOR]

BACKGROUND Prostacyclin (PGI2) plays an important role in mouse embryo development and implantation. However, it is unclear whether its action is mediated via the I prostaglandin receptor (IP). METHODS We compared the preimplantation development of IP deleted (IP−/−) embryos and wild-type (WT) embryos. We also evaluated the effect of iloprost, a stable PGI2 analog, and L-165041, a peroxisome proliferator activated receptor δ (PPARδ) ligand, on IP−/− versus WT embryos. Finally, we compared the development of heterozygous IP deficient embryos carrying a normal maternal IP allele versus paternal IP allele. RESULTS Development of IP−/− embryos lagged behind WT embryos and was not enhanced by either the PGI2 analog or the PPARδ ligand. WT embryos had slightly higher, although statistically not significant, implantation rates than IP−/− embryos. Heterozygous IP deficient embryos carrying a normal maternal IP allele showed better development and responded to the PGI2 analog, unlike those carrying the normal paternal IP allele. CONCLUSIONS IP receptors play an important role in preimplantation embryo development and mediate the embryos response to exogenous PGI2. Early embryo development depends on the oocyte IP receptor. [ABSTRACT FROM AUTHOR]