Fig 1. GFP imaging in space and time–measurement and representations of prolactin gene transcription.

(a) A diagrammatic illustration of how the GFP reporter measurement is associated with the underlying process of native prolactin gene expression. Expression of the d2EGFP reporter transgene in these studies is controlled by a fragment of the human prolactin gene locus (as described previously[1, 8]). Both the endogenous prolactin gene and the prolactin-d2EGFP reporter gene mRNAs are transcribed in parallel, but are then translated independently into respective proteins (reproduced from [10]). (b) A GFP image of an intact tissue slice from an adult male prolactin-d2EGFP transgenic reporter rat, with a white enclosure to indicate a cell-tracked area for analysis. (c) A spatial distribution of cell centroids, defined as the median over the time-course of the coordinates, with its convex hull (blue). There are 101 cells. The convex hull will be used in Fig 3A in the estimation of the mean cell size. (d) Magnified typical video-frame sequences in time, showing dynamic changes in reporter gene transcription over a collection of single cells. A single sample is recorded concurrently in two channels of high (upper row) and low (lower row) sensitivities. (e) Typical GFP signals in a time course, showing high (left) and low (right) correlations. Correlation coefficients are 0.96 (left) and 0.14 (right) respectively. Each time series obtained in a single cell is reconstructed from two recordings illustrated in (d). See Fig 2B for the reconstruction process.