Cellular senescence is a state in which cells become arrested in the cell cycle. That is, permanently stop dividing in response to stress or damage. The term “senescence” comes from the Latin senescere, meaning “to grow old.

Statistical hypothesis testing is a framework for making decisions about populations based on sample data.

• Null Hypothesis (\(H_0\)): A statement of no effect or no difference.
• Alternative Hypothesis (\(H_1\) or \(H_A\)): A statement that contradicts the null hypothesis.

Mathematical Framework

The test statistic \(t\) for comparing two means is as follows: \[t = \frac{\bar{X}_1 - \bar{X}_2}{\sqrt{\frac{s_1^2}{n_1} + \frac{s_2^2}{n_2}}}\]

Where \(\bar{X}_1, \bar{X}_2\) are sample means, \(s_1^2, s_2^2\) are sample variances, and \(n_1, n_2\) are sample sizes.

A note on P-values: \(p\)-value = \(P(T > t)\), where \(T\) is the test statistic under the null hypothesis. A small p-value (typically \(p\) < 0.05) indicates strong evidence against the null hypothesis, leading to its rejection.

Let’s get an idea of the reasons behind the inclusion of genes in the GenAge database. The dataset contains a column named why, which provides insight into the rationale for each gene’s inclusion.

The different shades of green represent distinct senescence mechanism categories, with each tile showing the relationship between a gene and its biological pathway category.

This 3D visualization plots genes using metrics derived from the GenAge database: the GenAge ID (potentially reflecting order of discovery), gene name length (often correlating with functional complexity), and the number of senescence mechanisms. This approach could reveal patterns in how complex genes participate in multiple aging pathways.

This heatmap visualizes co-occurrence patterns between senescence mechanism categories, with darker red indicating stronger associations. The matrix reveals which aging pathways frequently operate together in the same genes, highlighting the interconnected nature of senescence processes rather than isolated mechanisms. White cells identify potentially separate pathways or areas needing further research.