Then the cryld - lacz was introduced into different hosts . analysis of activity of p - galactosidase showed that the cryld and crylab expressed differently in different hosts . comparison of expression of cryld with crylab in the same host revealed that different upstream and competition for < j - factor were involved in the difference of cryld and crylab expression 结果表明，在不同遗传背景的菌株中， cry1d - lacz和cry1ab - lacz融合基因的表达完全不同，表明同一基因在不同菌株中转录调控不同，也许一些宿主专一性的因子参与了转录调控；而在同一菌株中cry1d - lacz和cry1ab - lacz的表达差异是由于上游区的不同以及竞争有限的因子所致。
