Characterizing short germline-specific promoters with a range of expression levels in .

A core tenet of synthetic biology is that well-characterized regulatory elements are essential for engineering biological systems. Here, we characterize the specificity and expression levels of 18 short (254 to 880 bp) candidate germline promoters using a single-copy reporter assay in . Six promoters resulted in ubiquitous expression, three did not drive detectable expression, and nine were germline-specific.

Engineering rules that minimize germline silencing of transgenes in simple extrachromosomal arrays in C. elegans.

Transgenes are prone to progressive silencing due to their structure, copy number, and genomic location. In C. elegans, repressive mechanisms are particularly strong in the germline with almost fully penetrant transgene silencing in simple extrachromosomal arrays and frequent silencing of single-copy transgene insertions.