Time-lapse confocal imaging-induced calcium ion discharge from the cumulus-oocyte complex at the time of cattle oocyte activation

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dc.contributor.authorMcLennan, H.J.
dc.contributor.authorSutton-McDowall, M.L.
dc.contributor.authorHeng, S.
dc.contributor.authorAbell, A.D.
dc.contributor.authorThompson, J.G.
dc.date.issued2020
dc.description.abstractOocyte activation, the dynamic transformation of an oocyte into an embryo, is largely driven by Ca²⁺ oscillations that vary in duration and amplitude across species. Previous studies have analysed intraoocyte Ca²⁺ oscillations in the absence of the oocyte’s supporting cumulus cells. Therefore, it is unknown whether cumulus cells also produce an ionic signal that reflects fertilisation success. Time-lapse confocal microscopy and image analysis on abattoir-derived cattle cumulus–oocyte complexes coincubated with spermatozoa revealed a distinct discharge of fluorescence from the cumulus vestment. This study demonstrated that this Ca²⁺ fluorescence discharge was an artefact induced by the imaging procedure independently of oocyte activation success. The fluorescence discharge was a direct result of cumulus cell membrane integrity loss, and future studies should consider the long-term effect of fluorescent labels on cells in time-lapse imaging. However, this study also demonstrated that the distinctive pattern of a coordinated fluorescence discharge was associated with both the presence of spermatozoa and subsequent embryo development to the morula stage, which was affected by Ca²⁺ chelation and a reduction in the active efflux of the fluorophore. This indicates that the cumulus vestment may have a relationship with oocyte activation at and beyond fertilisation that requires further investigation.
dc.description.statementofresponsibilityHanna J. McLennan, Melanie L. Sutton-McDowall, Sabrina Heng, Andrew D. Abell and Jeremy G. Thompson
dc.identifier.citationReproduction, Fertility and Development, 2020; 32(14):1223-1238
dc.identifier.doi10.1071/RD20143
dc.identifier.issn1031-3613
dc.identifier.issn1448-5990
dc.identifier.orcidMcLennan, H.J. [0000-0002-2058-2488]
dc.identifier.orcidSutton-McDowall, M.L. [0000-0002-4121-0202]
dc.identifier.orcidAbell, A.D. [0000-0002-0604-2629]
dc.identifier.orcidThompson, J.G. [0000-0003-4941-7731]
dc.identifier.urihttp://hdl.handle.net/2440/129527
dc.language.isoen
dc.publisherCSIRO Publishing
dc.relation.granthttp://purl.org/au-research/grants/arc/CE140100003
dc.relation.granthttp://purl.org/au-research/grants/nhmrc/1077694
dc.rightsJournal compilation © CSIRO 2020
dc.source.urihttps://doi.org/10.1071/rd20143
dc.subjectCalcium oscillations; confocal imaging; embryo development; fertilisation; fluorescent probes; oocyte activation
dc.titleTime-lapse confocal imaging-induced calcium ion discharge from the cumulus-oocyte complex at the time of cattle oocyte activation
dc.typeJournal article
pubs.publication-statusPublished

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