细胞周期

Veblen

对于细胞周期的拟合，Watson与Dean-Jett Fox有什么区别呢？
分别什么时候用它们呢？

niwanmao

FlowJo的帮助文档，有这么一段，可以给你解惑（Cell Cycle: Univariate）：

the Watson Pragmatic algorithm  and Dean Jett Fox (DJF) . The two models differ in their mathematical calculations of each phase of the cell cycle. Consequently, results from one model may vary quite significantly from the other. It is good laboratory practice to consistently use the same model throughout a study when reporting or publishing statistics. The methods the models employ to calculate their statistics are described below.



Watson Pragmatic

The Watson model was published by James Watson and colleagues in 1987. It assumes only that the data within the G0/G1 and G2/M peaks are normally distributed and that one of those two peaks is identifiable. [3]

The model initializes by approximating G0/G1 peak as a Gaussian distribution and making an initial guess of the mean by finding the channel with the most cell in the left portion of the data. The standard deviation (SD) or width of the population is then approximated by finding the width of the distribution at 60% of the maximum height. A minimization process (least squares fitting) is then executed over a range of -3 to 1 standard deviations about the first guess mean to improve the fit. The range is unbalanced to the left since little data is expected to occur below the G0/G1 peak, while the S phase cells are expected to occur to the right and are more likely to overlap and skew the fit.

Once the G0/G1 peak is fit, the G2/M mean is placed at 1.75 x the intensity of the G0/G1 mean. Theoretically the G2/M peak will have a mean twice as bright as the G0/G1, but in practice there is some loss in the process and the G2/M peak ends up being not quite twice as bright.

The width is estimated in the same manner and a second Gaussian distribution is fit to the data using the same minimization process.



Dean-Jett-Fox

The Dean-Jett Fox (DJF) model is a modification to one of the original algorithms published for modeling cell cycle data, the Dean-Jett (3), and was published in 1980 in Cytometry.

The G0/G1 and G2/M curves are fit using the same process as the Watson model. The difference occurs in the fit of the S phase. The Dean-Jett model fit a second order polynomial (f (x) = Ax^2 + Bx + C) to the S phase. The Fox modification is to make the fit the addition of a Gaussian distribution and the polynomial. This modification gives the DJF model the ability to properly fit a synchronous population with a complex S phase distribution.

简而言之，两者你都可选，但是一旦选定，就只能用一种模型，不能换。大多数情况下，用Watson的比较多。两种模型对拟合的算法不同，如果你的实验涉及到S期的评估比较多，并且S 期可能会分布比较复杂，那么可以需用DJF法。