
TY  - JOUR
A1  - Day, Margot L. 
A1  - Winston, Nicola 
A1  - McConnell, Josie L. 
A1  - Cook, David 
A1  - Johnson, Martin H. 
T1  - tiK<emph type="7">+</emph> toK<emph type="7">+</emph>: an embryonic clock?
JF  - Reproduction, Fertility and Development
JO  - Reprod. Fertil. Dev.
Y1  - 2001
VL  - 13
IS  - 1
SP  - 69
EP  - 79
KW  - cyclins, developmental timer, EAG, ERG, K+ channel, mouse embryo.
UR  - https://doi.org/10.1071/RD00048 
N2  - During embryogenesis cells make appropriately timed developmental decisions. Both &#8216;hourglass-like&#8217; and &#8216;clock-like&#8217; mechanisms have been demonstrated to act as timers in early development. The cell cycle rhythm, using feedback circuits to drive cells unidirectionally through checkpoints, is an example of a clock-like timer, but how it operates to time developmental events is unclear. In other cell types, cyclic oscillations in K+ channel activity, which parallel cell cycle and circadian rhythms, may be part of the timing mechanism. Changes in K+ oscillations accompany key developmental transitions and oncogenic transformation. Channel blockade interferes pharmaco-logically with cell cycle initiation or progression, whereas channel over-expression can be oncogenic. K+ channel activity also exists in early mouse oocytes through to at least the blastocyst stage, and it oscillates in phase with the developmental cell cycles, being high in M/G1 and low in S/G2. It resembles physiologically the activity of the K+ channels of the eag- or erg-like families. Reverse transcriptase&#8211;polymerase chain reaction of mouse oocytes has revealed the presence of transcripts encoding both EAG- and ERG-like proteins throughout preimplantation devel-opment. Channel activity continues to oscillate with a cell cycle periodicity in embryos from which the nucleus has been removed, or after inhibition by puromycin of the cyclin B&#8211;cyclin-dependent kinase 1 driven component of the chromosomal cycle. Channel oscillatory activity thus appears to be able to function autonomously of the chromo-somal cycle and may represent a distinct oscillatory timing activity with possible developmental significance. 
ER  -

