= Allan C. Spradling
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= A. C. Spradling
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{synonym}
<Allan C. Spradling> is a <biologist> whose work includes <Drosophila melanogaster> <genetics> and <oogenesis>. Carnegie Science's institutional biography identifies his collaboration with <Gerald M. Rubin> in developing a way to introduce <genes> into the fly <genome>, directly connecting his full name to the researcher credited as A. C. Spradling.<Allan Spradling research biography by Carnegie Science>[May 7, 2018, full name and collaboration on gene transfer]{ref}
Their 1982 experiment used a <P element> carrying a functional version of a gene whose defect altered eye color. Transformed flies recovered normal eye color, and the inserted <DNA> was stably inherited in later generations. The study thus connected a visible functional readout with evidence of chromosomal integration and inheritance.<Genetic transformation of Drosophila with transposable element vectors by G. M. Rubin and A. C. Spradling>[Abstract, rosy marker, integrated copies and stable inheritance]{ref}
A toy inheritance model explains why later generations matter. Suppose a new <allele> is present on one of two homologous <chromosomes> in a <germline> cell lineage. In a simple cross to an organism lacking that allele, assume ordinary equal segregation, equal survival and complete detection. Each offspring then has probability $1/2$ of inheriting the insertion, so the expected number among twenty offspring is ten. The assumptions define a model, not an observed ratio from the 1982 study.
Seeing a changed cell in an initially treated animal would not alone establish transmission to offspring. The distinction between a temporary signal, a stable insertion and an inherited alteration is central to explaining the advance. Spradling and collaborators helped turn <Drosophila melanogaster> from an organism in which mutations could be observed into one in which introduced <DNA> could be tested experimentally.
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