Phylogenetic context and Basal metazoan model systems.

Phylogenetic Context and Basal Metazoan Model Systems1

SYNOPSIS. In comparative studies using model organisms, extant taxa are often referred to as basal. The term suggests that such taxa are descendants of lineages that diverged early in the history of some larger taxon. By this usage, the basal metazoans comprise just four phyla (Placozoa, Porifera, Cnidaria, and Ctenophora) and the large clade Bilateria. We advise against this practice because b...

Concatenated Analysis Sheds Light on Early Metazoan Evolution and Fuels a Modern “Urmetazoon” Hypothesis

For more than a century, the origin of metazoan animals has been debated. One aspect of this debate has been centered on what the hypothetical "urmetazoon" bauplan might have been. The morphologically most simply organized metazoan animal, the placozoan Trichoplax adhaerens, resembles an intriguing model for one of several "urmetazoon" hypotheses: the placula hypothesis. Clear support for a bas...

Comparative Neuroanatomy of Mollusks and Nemerteans in the Context of Deep Metazoan Phylogeny

Trypanosoma seryl-tRNA synthetase is a metazoan-like enzyme with high affinity for tRNASec.

Trypanosomatids are important human pathogens that form a basal branch of eukaryotes. Their evolutionary history is still unclear as are many aspects of their molecular biology. Here we characterize essential components required for the incorporation of serine and selenocysteine into the proteome of Trypanosoma. First, the biological function of a putative Trypanosoma seryl-tRNA synthetase was ...

Genomics of Basal Metazoans1

SYNOPSIS. An in-depth understanding of the biology of animals will require the generation of genomics resources from organisms from all phyla in the metazoan phylogenetic tree. Such resources will ideally include complete genome sequences and comprehensive EST (expressed sequence tag) datasets for each species of interest. Of particular interest in this regard are animals in the early diverging...