The definition of the feature vectors based on the frequency of labeled paths [19, 20] or small fragments [10, 21] has been widely used.
Moreover, although the control cells showed marked loss of the BrdU label during the analysis period, the frequency of labeled p56Lck-deficient cells was considerably more stable.
For sparse labeling of neurons without selection for a particular subtype, the R26CreER Z/AP combination with an early postnatal injection of 4HT generates a frequency of labeling that is close to optimal for morphologic analyses [ 0.001% 0.01% of neurons labeled; 5,10].
Accordingly, when CK19CreERT was cross to the R26REYFP reporter [22], we found a low frequency of labeling in squamous epithelium of both the lingual and buccal surfaces (Figure 1C, D).
Quantitative analysis of ISZ labeling in the cerebellar cortex showed that EE tended to increase both the frequency of labeled PCs (Fig. S5E; wild-type: ST = 74.29%±2.18, EE = 87.06%±2.91; One Way Anova: P = 0.182. Transgenic: ST = 79.96%±5.81, EE = 93.76% ±1.89; One Way Anova: P = 0.05) and the intensity of ISZ signal (Fig. S5F).
We used the Cre/loxP system to define the type and frequency of labeled neurons: Cre or tamoxifen-inducible Cre (CreER) can be driven by a variety of specific promoters in transgenes generated by the mouse community (for example, [2], [3], [4], [5], [6], [7]).
We also measured the observed frequency of labeled clones at two different time points (E8.5 and E14.5) to determine if the frequency of labeled clones changed over time (either increased or decreased) as might happen with additional recombination outside of our time window (E6.0 E7.0) or with selective loss of a twin spot via apoptosis.
To test for the effect of labeling, we added a control by mixing labeled and unlabeled cells of the mixed population of the decreasing strains in equal proportions and assessed the frequency of labeled spores.
