Winter mortality in the green anole, Anolis carolinensis (Lacertilia: Polychridae)

Volume: 25Start Page: 140End Page: 14

The Genera of Pleurobemini (Bivalvia: Unionidae: Ambleminae)

The unionid tribe Pleurobemini is diverse but poorly-understood phylogenetically. Current classification recognizes two highly diverse genera, Elliptio Rafinesque, 1819 and Pleurobema Rafinesque, 1820, besides the moderately diverse Fusconaia Simpson, 1900, and several genera with one to three species. However, classification at the species and genus level has been problematic. Molecular data and re-examination of shell morphology and anatomy indicate new groupings of these taxa. Several genera proposed by early workers such as Rafinesque and Swainson are available, but are poorly-characterized and are often overlooked. We analyzed two mitochondrial genes, cox1 and nad1, for 50 species assigned to Pleurobemini, including the type species of each genus and as many other species as possible. Although the majority of studied species in Elliptio, Pleurobema, and Fusconaia show close affinities to the respective type species, the affinities of others are problematic. Genera or subgenera such as Eurynia Rafinesque, 1819, SintoxiaRafinesque, 1820, and Pleuronaia Frierson, 1927, generally regarded as subjective synonyms, apply to some clades. Other clades or unaffiliated species have no available name. Quincuncina burkei (Walker, 1922), the type of the genus Quincuncina Ortmann, 1922, is assigned to Fusconaia Simpson, 1900. Fusconaia apalachicola (Williams and Fradkin, 1999), F. ebenus (Lea, 1831), F. rotulata (Wright, 1899) (also listed as Obovaria rotulata), F. succissa (Lea, 1852), Cyclonaias tuberculatus (Rafinesque, 1820), Uniomerus Conrad, 1853, and the Quincuncina infucata (Conrad, 1834) complex are all excluded from Pleurobemini. The first three are placed in the new genus Reginaia Campbell and Lydeard; Uniomerus Conrad, 1853 is assigned to Quadrulini; and the remainder belong in the pustulosa Lea, 1831 group of Quadrulini (genus RotundariaRafinesque, 1820)

Mutants of the Paf1 Complex Alter Phenotypic Expression of the Yeast Prion [PSI+]

The yeast [PSI+] prion is an epigenetic modifier of translation termination fidelity that causes nonsense suppression. The prion [PSI+] forms when the translation termination factor Sup35p adopts a self-propagating conformation. The presence of the [PSI+] prion modulates survivability in a variety of growth conditions. Nonsense suppression is essential for many [PSI+]-mediated phenotypes, but many do not appear to be due to read-through of a single stop codon, but instead are multigenic traits. We hypothesized that other global mechanisms act in concert with [PSI+] to influence [PSI+]-mediated phenotypes. We have identified one such global regulator, the Paf1 complex (Paf1C). Paf1C is conserved in eukaryotes and has been implicated in several aspects of transcriptional and posttranscriptional regulation. Mutations in Ctr9p and other Paf1C components reduced [PSI+]-mediated nonsense suppression. The CTR9 deletion also alters nonsense suppression afforded by other genetic mutations but not always to the same extent as the effects on [PSI+]-mediated read-through. Our data suggest that the Paf1 complex influences mRNA translatability but not solely through changes in transcript stability or abundance. Finally, we demonstrate that the CTR9 deletion alters several [PSI+]-dependent phenotypes. This provides one example of how [PSI+] and genetic modifiers can interact to uncover and regulate phenotypic variability