The process of gene assembly in ciliates, an ancient group of organisms, is one of the most complex instances of DNA manipulation known in any organism. Three molecular operations ld, hi, and dlad have been postulated for the gene assembly process. We propose in this paper a mathematical model for contextual variants of ld and dlad on strings: recombinations can be done only if certain contexts are present. We prove that the proposed model is Turing-universal.