# Likelihood for transcriptions in a genetic regulatory system under asymmetric stable L\'evy noise

## TL;DR

This paper investigates how asymmetric stable Lévy noise influences gene transcription likelihood, revealing phenomena like stochastic bifurcation and turning points, and offers methods to control transcription probability through noise parameter tuning.

## Contribution

It introduces a novel analysis of asymmetric Lévy noise effects on gene regulation, identifying key phenomena and providing parameter strategies for gene transcription control.

## Key findings

- Asymmetric noise skews increase transcription likelihood with positive skewness.
- Stochastic bifurcation occurs at non-Gaussianity index α=1 in additive noise.
- Turning points in likelihood are observed at β≈-0.5, depending on skewness.

## Abstract

This work is devoted to investigating the evolution of concentration in a genetic regulation system, when the synthesis reaction rate is under additive and multiplicative asymmetric stable L\'evy fluctuations. By focusing on the impact of skewness (i.e., non-symmetry) in the probability distributions of noise, we find that via examining the mean first exit time (MFET) and the first escape probability (FEP), the asymmetric fluctuations, interacting with nonlinearity in the system, lead to peculiar likelihood for transcription. This includes, in the additive noise case, realizing higher likelihood of transcription for larger positive skewness (i.e., asymmetry) index $\beta$, causing a stochastic bifurcation at the non-Gaussianity index value $\alpha=1$ (i.e., it is a separating point or line for the likelihood for transcription), and achieving a turning point at the threshold value $\beta \approx -0.5$ (i.e., beyond which the likelihood for transcription suddenly reversed for $\alpha$ values). The stochastic bifurcation and turning point phenomena do not occur in the symmetric noise case ($\beta =0$). While in the multiplicative noise case, non-Gaussianity index value $\alpha=1$ is a separating point or line for both the mean first exit time (MFET) and the first escape probability (FEP). We also investigate the noise enhanced stability phenomenon. Additionally, we are able to specify the regions in the whole parameter space for the asymmetric noise, in which we attain desired likelihood for transcription. We have conducted a series of numerical experiments in `regulating' the likelihood of gene transcription by tuning asymmetric stable L\'evy noise indexes. This work offers insights for possible ways of achieving gene regulation in experimental research.