Before revision:  In this paper we aim to show that the concept of ensemble of trajectories can be applied to a variety of stochastic models of gene expression and hence , apart from asymptotic behavior of remote tails of probability distributions of the dynamical observables, generating functions for the cumulants of these observables can easily be obtained.
After revision:  In this paper we aim to show that the concept of ensemble of trajectories can be applied to a variety of stochastic models of gene expression ranging from a simple birth-death process to a more sophisticate model containing burst and switch. By considering the protein numbers as a relevant dynamical observable , apart from asymptotic behavior of remote tails of probability distributions of the dynamical observables, generating functions for the cumulants of these observables can easily be obtained.