Activator effect of coinjected enhancers on the muscle-specific expression of promoters in zebrafish embryos

The transient expression of reporter gene constructs in embryos provides a powerful tool to characterise cis-acting transcriptional elements of the genes involved in development. In the present study, we have analysed the expression pattern of several muscle-specific and ubiquitous regulatory sequences in microinjected zebrafish embryos. By using a fast and reproducible coinjection strategy, the mosaic expression of lacZ reporter gene was monitored in wholemount embryos injected with sequences containing putative enhancer elements and a carp myosin heavy chain promoter/lacZ reporter construct. We have found that a 0.9-kb myosin heavy chain (MyHC) proximal promoter containing several putative myogenic regulatory factors (MRF) binding sites is sufficient to restrict lacZ expression to the skeletal muscle fibres of prim-6 stage zebrafish embryos. Expression of a rat-derived foetal myosin light chain enhancer (MyLC) and different fragments of a carp β-actin regulatory region together with the MyHC promoter were compared by accumulating the type, number and spatial distribution of β-galactosidase-expressing cells on an expression map. β-galactosidase activity increased similarly whether the MyLC enhancer was ligated to the promoter/reporter construct directly or when coinjected as a separate fragment whilst skeletal muscle specificity was retained. The coinjection of two different forms of the β-actin regulatory elements also showed a marked effect on the MyHC promoter activity

Multi-agent modeling of the trajectory of the LBK Neolithic: a study in progress

International audienc

Multi-agent modeling of the trajectory of the LBK Neolithic: a study in progress

International audienc