Deriving structure from evolution: metazoan segmentation

Deriving structure from evolution: metazoan segmentation

Segmentation is a common feature of disparate clades of metazoans, and its evolution is a central problem of evolutionary developmental biology. We evolved in silico regulatory networks by a mutation/selection process that just rewards the number of segment boundaries. For segmentation controlled by a static gradient, as in long-germ band insects, a cascade of adjacent repressors reminiscent of...

Basal Metazoan Sensory Evolution

Losing the stem-loop structure from metazoan mitochondrial tRNAs and co-evolution of interacting factors

Conventional tRNAs have highly conserved sequences, four-armed cloverleaf secondary structures, and L-shaped tertiary structures. However, metazoan mitochondrial tRNAs contain several exceptional structures. Almost all tRNAs(Ser) for AGY/N codons lack the D-arm. Furthermore, in some nematodes, no four-armed cloverleaf-type tRNAs are present: two tRNAs(Ser) without the D-arm and 20 tRNAs without...

Cnidarian milestones in metazoan evolution.

Cnidarians display most of the characters considered as milestones of metazoan evolution. Whereas a tissue-level organization was probably already present in the multicellular common ancestor of all animals, the Urmetazoa, the emergence of important animal features such as bilateral symmetry, triploblasty, a polarized nervous system, sense organs (eyes, statocysts), and a (chitinous or calcium-...

PROTEAN: Deriving Protein Structure from Constraints

PROTEAN is an evolving knowledge-based system that is intended to identify the three-dimensional conformations of proteins in solution. Using a variety of empirically derived constraints, PROTEAN must identify legal positions for each of a protein’s constituent structures (e.g., atoms, amino acids, helices) in threedimensional space. In fact, because protein-structure analysis is an underconstr...