A Review of the fossil record of turtles of the clade Baenidae

The fossil record of the turtle clade Baenidae ranges from the Early Cretaceous (Aptian—Albian) to the Eocene. The group is present throughout North America during the Early Cretaceous, but is restricted to the western portions of the continents in the Late Cretaceous and Paleogene. No credible remains of the clade have been reported outside of North America to date. Baenids were warmadapted freshwater aquatic turtles that supported high levels of diversity at times through niche partitioning, particularly by adapting to a broad range of dietary preferences ranging from omnivorous to molluscivorous. Current phylogenies place Baenidae near the split of crown-group Testudines. Within Baenidae three more inclusive, named clades are recognized: Baenodda, Palatobaeninae and Eubaeninae. A taxonomic review of the group concludes that of 49 named taxa, 30 are nomina valida, 12 are nomina invalida and 7 are nomina dubia

Particles-vortex interactions and flow visualization in He4

Recent experiments have demonstrated a remarkable progress in implementing and use of the Particle Image Velocimetry (PIV) and particle tracking techniques for the study of turbulence in He4. However, an interpretation of the experimental data in the superfluid phase requires understanding how the motion of tracer particles is affected by the two components, the viscous normal fluid and the inviscid superfluid. Of a particular importance is the problem of particle interactions with quantized vortex lines which may not only strongly affect the particle motion, but, under certain conditions, may even trap particles on quantized vortex cores. The article reviews recent theoretical, numerical, and experimental results in this rapidly developing area of research, putting critically together recent results, and solving apparent inconsistencies. Also discussed is a closely related technique of detection of quantized vortices negative ion bubbles in He4.Comment: To appear in the J Low Temperature Physic

Overview and analysis of the polyprotein cleavage sites in the family Potyviridae

The genomes of plant viruses in the family Potyviridae encode large polyproteins that are cut by virus-encoded proteases into ten mature proteins. Three different types of protease have been identified, each of which cuts at sites with a distinctive sequence pattern. The experimental evidence for this specificity is reviewed and the cleavage site patterns are compiled for all sequenced species within the family. Seven of the nine cleavage sites in each species are cut by the viral Nla-Pro and patterns around these sites are related where possible to the active site-substrate interactions recently deduced following the resolution of the crystal structure of Tobacco etch virus (TEV) Nla-Pro (Phan et al., 2002. J. Biol. Chem. 277,50564-50572). In particular, a revised series of cleavage sites for Sweetpotato mild mottle virus (genus Ipomovirus) is proposed with a conserved His at the P1 position. This is supported by homology modelling studies using the TEV structure as a template. The data also provide a standard to correct the annotation of some other published sequences and to help predict these sites in further virus sequences as they become available. Comprehensive data for all sequences of each virus in the family, together with some summaries, have been made available at http://www.rothamsted.bbsrc.ac.uk/ppi/links/pplinks/potycleavage/ index.html