Physarum polycephalum is a well-studied microbial eukaryote with unique experimental attributes relative to other experimental model organisms. It has a sophisticated life cycle with several distinct stages including amoebal, flagellated, and plasmodial cells. It is unusual in switching between open and closed mitosis according to specific life-cycle stages. Here we present the analysis of the genome of this enigmatic and important model organism and compare it with closely related species. The genome is littered with simple and complex repeats and the coding regions are frequently interrupted by introns with a mean size of 100 bases. Complemented with extensive transcriptome data, we define approximately 31,000 gene loci, providing unexpected insights into early eukaryote evolution. We describe extensive use of histidine kinase-based two-component systems and tyrosine kinase signaling, the presence of bacterial and plant type photoreceptors (phytochromes, cryptochrome, and phototropin) and of plant-type pentatricopeptide repeat proteins, as well as metabolic pathways, and a cell cycle control system typically found in more complex eukaryotes. Our analysis characterizes P. polycephalum as a prototypical eukaryote with features attributed to the last common ancestor of Amorphea, that is, the Amoebozoa and Opisthokonts. Specifically, the presence of tyrosine kinases in Acanthamoeba and Physarum as representatives of two distantly related subdivisions of Amoebozoa argues against the later emergence of tyrosine kinase signaling in the opisthokont lineage and also against the acquisition by horizontal gene transfer.

There was and still is a statistically significant increase in spring practice injury risk. The 1998 rule change resulted in an even greater increase in spring practice injury risk. If the goal is to minimize the number of spring practice injuries, it will be best accomplished by limiting the number of scrimmages and limited-contact sessions.

A corollary of the central dogma of molecular biology is that genetic information passes from DNA to RNA by the continuous synthesis of RNA on a DNA template. The demonstration of RNA editing (the specific insertion, deletion or substitution of residues in RNA to create an RNA with a sequence different from its own template) raised the possibility that in some cases not all of the genetic information for a trait residues in the DNA template. Two different types of RNA editing have been identified in mitochondria: insertional editing represented by the extensive insertion (and occasional deletion) of uridine residues in mitochondrial RNAs of the kinetoplastid protozoa and the substitutional editing represented by the cytidine to uridine substitutions in some plant mitochondria. These editing types have not been shown to be present in the same organism and may have very different mechanisms. RNA editing of both types has been observed in nonmitochondrial systems but is not as extensive and may involve still different mechanisms. Here we report the discovery of extensive insertional RNA editing in mitochondria from an organism other than a kinetoplastid protozoan. The mitochondrial RNA apparently encoding the alpha subunit of ATP synthetase in the acellular slime mould, Physarum polycephalum, is edited at 54 sites by cytidine insertion.

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