Conserved functions of prion candidates suggest a primeval role of protein self-templating.

Amyloid-based prions have simple structures, a wide phylogenetic distribution, and a plethora of functions in contemporary organisms, suggesting they may be an ancient phenomenon. However, this hypothesis has yet to be addressed with a systematic, computational, and experimental approach. Here we present a framework to help guide future experimental verification of candidate prions with conserved functions to understand their role in the early stages of evolution and potentially in the origins of life. We identified candidate prions in all high-quality proteomes available in UniProt computationally, assessed their phylogenomic distributions, and analyzed candidate-prion functional annotations. Of the 27 980 560 proteins scanned, 228 561 were identified as candidate prions (~0.82%). Among these candidates, there were 84 Gene Ontology (GO) terms conserved across the three domains of life. We found that candidate prions with a possible role in adaptation were particularly well-represented within this group. We discuss unifying features of candidate prions to elucidate the primeval roles of prions and their associated functions. Candidate prions annotated as transcription factors, DNA binding, and kinases are particularly well suited to generating diverse responses to changes in their environment and could allow for adaptation and population expansion into more diverse environments. We hypothesized that a relationship between these functions and candidate prions could be evolutionarily ancient, even if individual prion domains themselves are not evolutionarily conserved. Candidate prions annotated with these universally occurring functions potentially represent the oldest extant prions on Earth and are therefore excellent experimental targets.

[An attempt to determine intermediate hosts of the tapeworm Echinococcus multilocularis in Poland]. / Próba wykrycia zywicieli posrednich tasiemca Echinococcus multilocularis na terenie Polski.

Echinococcus multilocularis, a tiny tapeworm (2-3 mm in length) occurs in the small intestine of red foxes and raccoon dogs in Poland. Small rodents, intermediate hosts of the tapeworm can ingest parasite eggs excreted in faeces by final host. Humans can become infected by accidental ingestion of the eggs. The resulting disease, alveolar echinococcosis, potentially lethal zoonosis, typically presents as an infiltrative tumor-like growth in the liver, which may invade neighbouring organs. The objective of the study was to determine intermediate host species for E. multilocularis in Poland. During the years 2004-2006, a total of 1425 animals, i.e. 1170 rodents (14 species), 238 insectivores (4 species) and 17 Mustelids (3 species) were trapped and autopsied for the presence of E. multilocularis protoscolices (larvae). Animals were captured in northern, north-eastern, central and southern Poland, areas where the high prevalence of the tapeworm was recorded in foxes. In 44 (3.1%) of examined animals were found cysts in the liver, however no typical lesions were affirmed. Infection was not confirmed using PCR technique with primers specific for E. multilocularis (EmCA90, EmTriple83).

Infection of red foxes (Vulpes vulpes) with Echinococcus multilocularis during the years 2001-2004 in Poland.

During the period of 2001-2004, 1,514 red foxes from the north and the southeast of Poland were sampled and examined parasitologically for infections with Echinococcus multilocularis. A mean 23.8% were found infected in the whole study area. The highest prevalence (50.0-62.9%) was found in some counties in the northeastern (Warmia-Mazuria) and the southeastern (Carpathian Foothill) part of the country. During the study period, significant differences in the prevalence were found on a regional level. Based on the results obtained to date, the paper presents an overview of the current epidemiological situation of E. multilocularis in the fox population in Poland.