A Novel Piggybac Transposon Inducible Expression System Identifies a Role for Akt Signalling in Primordial Germ Cell Migration

In this work, we describe a single piggyBac transposon system containing both a tet-activator and a doxycycline-inducible expression cassette. We demonstrate that a gene product can be conditionally expressed from the integrated transposon and a second gene can be simultaneously targeted by a short hairpin RNA contained within the transposon, both in vivo and in mammalian and avian cell lines. We applied this system to stably modify chicken primordial germ cell (PGC) lines in vitro and induce a reporter gene at specific developmental stages after injection of the transposon-modified germ cells into chicken embryos. We used this vector to express a constitutively-active AKT molecule during PGC migration to the forming gonad. We found that PGC migration was retarded and cells could not colonise the forming gonad. Correct levels of AKT activation are thus essential for germ cell migration during early embryonic development.     

Review of Canadian species of the genera Gnathusa Fenyes,Mniusa Mulsant & Rey and Ocyusa Kraatz (Coleoptera,Staphylinidae, Aleocharinae)

Four species of Gnathusa Fenyes (G. alfacaribou Klimaszewski & Langor, G. caribou Lohse, G. eva Fenyes, and G. tenuicornis Fenyes) occur in the Nearctic and in Canada. Three species of Ocyusa Kraatz (O. asperula Casey, O. californica Bernhauer, O. canadensis Lohse), and three species of Mniusa Mulsant and Ray (M. minutissima (Klimaszewski & Langor), M. yukonensis (Klimaszewski & Godin), and M. odelli Klimaszewski & Webster, sp. n.), are known from the Nearctic and all but O. californica occur in Canada. The recently described Gnathusa minutissima Klimaszewski and Langor and Ocyusa yukonensis Klimaszewski and Godin, are transferred here to the genus Mniusa Mulsant & Rey. New provincial and state records are reported for: G. eva (Alberta), G. tenuicornis (Alberta, Oregon, and New Brunswick), O. canadensis (New Brunswick and Newfoundland), M. minutissima (New Brunswick), and M. yukonensis (Nova Scotia, New Brunswick, Quebec, and British Columbia). The female of M. yukonensis was discovered and is illustrated for the first time. The genus Mniusa is reported for the first time from Canada and represents the first confirmed generic record for North America. Keys for identification of all Canadian species, images of body and genital structures, maps showing distribution mainly in Canada, and new bionomics data are provided.