Figure S1 - Activation Kinetics and Off-Target Effects of Thymus-Initiated Cre Transgenes

Temporal comparison of endogenous gene transcription vs. Cre transgene activity. RNA was isolated from pooled, sorted C57BL/6 thymocyte populations, as shown, and used as template to probe MOE4302 gene arrays (Affymetrix, representing all known genes and ESTs). Gene expression data represent the mean MAS5 value for three independent gene chips at each stage, expressed as a percentage of maximum expression. Absolute maximum values were 18,142 for Cd2, 12,907 for Lck, and 3782 for Cd4, where the median (nominal present/absent cutoff) for all genes on the chip was set to 500. Where multiple probesets were present (n = 4 for Lck, n = 2 for Cd4), the corresponding probeset values were averaged. Reporter activity is derived from Figure 1, but is expressed as a percentage of maximum (without error bars) for comparison purposes. Only Cd4[Cre] activity appears to closely reflect the activity of its endogenous counterpart, while Cd2[Cre] activity is dramatically accelerated, and Lck[Cre] of either strain is substantially delayed. (PDF)

内源性基因转录与Cre转基因活性的时序对比分析。本研究从如图所示的混合分选C57BL/6小鼠胸腺细胞群体中提取RNA，将其作为模板用于MOE4302基因芯片（Affymetrix，覆盖所有已知基因与表达序列标签（Expressed Sequence Tag））的探针杂交检测。基因表达数据为各阶段3次独立基因芯片检测的MAS5值均值，并以最大表达量的百分比形式呈现。各基因的绝对最大值分别为：Cd2 18142、Lck 12907、Cd4 3782；芯片上所有基因的中位数（名义存在/缺失临界值）设为500。当存在多个探针组（probeset）时（Lck对应4个，Cd4对应2个），将对应探针组的数值取平均。报告基因活性数据源自图1，为便于对比，以最大活性的百分比形式呈现（未标注误差棒）。仅Cd4[Cre]的活性能够较为精准地反映其对应的内源性基因活性；而Cd2[Cre]的活性显著提前，两种品系的Lck[Cre]活性则均明显滞后。（PDF）