"Stochastic Dynamics of Autonomous and Nonautonomous Transposable Element Interactions in Genomes"Omole, Adekanmi DanielTransposable elements (TEs) are mobile, self-replicating DNA sequences that can invade and persist in a host genome. While some TEs encode the enzymes necessary for their mobility, referred to as autonomous TEs, others, known as nonautonomous TEs, rely on transposition machinery encoded by autonomous TEs for their movement. Here, we use a stochastic model to investigate the interaction between autonomous and nonautonomous TEs mobilized via a copy-and-paste mechanism. Our analysis reveals conditions necessary for the stable coexistence of these TEs and challenges the notion that nonautonomous TEs are solely parasitic, highlighting their crucial role in TE dynamics. Analytically, we derive conditions governing the relative abundances of TEs and offer insights into why nonautonomous TEs tend to outnumber autonomous ones. Employing a linear noise approximation approach, we compute a stationary (Gaussian) distribution to quantify fluctuations in TE copy numbers around equilibrium values, yielding a rate-independent estimate of TE copy number variances, allowing for comparison with empirical data. Furthermore, we examine the impact of host silencing on TEs and find that nonautonomous TEs can play a crucial role in regulating TE proliferation, minimizing conflict with their host. Our findings indicate that the long-term coexistence of TEs necessitates encoding sufficient enzymes for the transposition of both types of TEs. We also observe that nonautonomous TEs contribute to controlling excessive TE proliferation, providing a benefit that offsets their cost, resulting in minimal impact from host silencing. |
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