title: Lessons from mouse chimaera experiments with a reiterated transgene marker: revised marker criteria and a review of chimaera markers.
abstract: Recent reports of a new generation of ubiquitous transgenic chimaera markers prompted us to consider the criteria used to evaluate new chimaera markers and develop more objective assessment methods. To investigate this experimentally we used several series of fetal and adult chimaeras, carrying an older, multi-copy transgenic marker. We used two additional independent markers and objective, quantitative criteria for cell selection and cell mixing to investigate quantitative and spatial aspects of developmental neutrality. We also suggest how the quantitative analysis we used could be simplified for future use with other markers. As a result, we recommend a five-step procedure for investigators to evaluate new chimaera markers based partly on criteria proposed previously but with a greater emphasis on examining the developmental neutrality of prospective new markers. These five steps comprise (1) review of published information, (2) evaluation of marker detection, (3) genetic crosses to check for effects on viability and growth, (4) comparisons of chimaeras with and without the marker and (5) analysis of chimaeras with both cell populations labelled. Finally, we review a number of different chimaera markers and evaluate them using the extended set of criteria. These comparisons indicate that, although the new generation of ubiquitous fluorescent markers are the best of those currently available and fulfil most of the criteria required of a chimaera marker, further work is required to determine whether they are developmentally neutral.
authors.affiliation: Genes and Development Group, Centre for Integrative Physiology, School of Clinical Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Keighren
authors.forename: Jean
authors.initials: J
authors.lastname: Flockhart
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Hodson
authors.forename: Guan-Yi
authors.initials: GY
authors.lastname: Shen
authors.forename: James R
authors.initials: JR
authors.lastname: Birtley
authors.forename: Antonio
authors.initials: A
authors.lastname: Notarnicola-Harwood
authors.forename: John D
authors.initials: JD
authors.lastname: West
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D002678:Chimera / Q000235:genetics*; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D005260:Female; D047109:Fetal Development / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D005819:Genetic Markers; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009928:Organ Specificity; D012162:Retinal Degeneration / Q000235:genetics*; D019076:Transgenes / Q000502:physiology*
chemical_list: D015415:Biomarkers; D005819:Genetic Markers