Limits Of Gene Expression Research Articles

Protists and the Wild, Wild West of Gene Expression: New Frontiers, Lawlessness, and Misfits

The DNA double helix has been called one of life's most elegant structures, largely because of its universality, simplicity, and symmetry. The expression of information encoded within DNA, however, can be far from simple or symmetric and is sometimes surprisingly variable, convoluted, and wantonly inefficient. Although exceptions to the rules exist in certain model systems, the true extent to which life has stretched the limits of gene expression is made clear by nonmodel systems, particularly protists (microbial eukaryotes). The nuclear and organelle genomes of protists are subject to the most tangled forms of gene expression yet identified. The complicated and extravagant picture of the underlying genetics of eukaryotic microbial life changes how we think about the flow of genetic information and the evolutionary processes shaping it. Here, we discuss the origins, diversity, and growing interest in noncanonical protist gene expression and its relationship to genomic architecture.

Threshold responses to the dorsal regulatory gradient and the subdivision of primary tissue territories in the Drosophila embryo

Dorsoventral patterning in Drosophila is initiated by the maternal regulatory factor dorsal (dl), which is a member of the Rel family of transcription factors. dl functions as a transcriptional activator and repressor to establish different territories of gene expression in the precellular embryo. Differential regulation of dl target genes may be essential for subdividing each tissue territory (the presumptive mesoderm, neuroectoderm, and dorsal ectoderm) into multiple cell types in older embryos. Different paterns of snail (sna) and decapentaplegic (dpp) expression help define the limits of inductive interactions between the mesoderm and dorsal ectoderm after gastrulation. Similarly, the differential regulation of short gastrulation (sog) and dpp may be decisive in the initial subdivision of the dorsal ectoderm, whereas different limits of gene expression within the neuroectoderm might provide the basis for the subsequent subdivision of this tissue into ventral and lateral regions.