Central place foraging by breeding Cook's petrel Pterodroma cookii: foraging duration reflects range, diet and chick meal mass

Pelagic seabirds are central place foragers during breeding and variation in foraging trip duration and range reflect differences in diet and chick provisioning, through the exploitation of divergent habitats of varying productivity. We tested whether these relationships hold in small procellarriids by equipping chick-rearing Cook's petrel Pterodroma cookii (200 g) with geolocation-immersion loggers, conducting isotope analysis of blood and measuring chick meal mass following foraging trips of varying duration. Cook's petrel tracked during chick rearing from Little Barrier Island (LBI) and Codfish Island (CDF), New Zealand had larger maximum ranges during longer foraging trips. Blood nitrogen isotope signatures (delta(15)N) of adults were significantly higher after foraging trips of longer duration, but not of greater maximum range. There was no significant relationship between blood carbon isotope signatures (delta(13)C) and foraging trip characteristics. Proportion of time spent on the sea surface and the mass of the meal brought back to chicks were consistently greater for Cook's petrel with larger maximum ranges, which in the case of birds from CDF coincided with productive subtropical convergence zone habitats. As predicted, trip duration reflected divergent foraging behaviours in Cook's petrel during breeding. We suggest that the availability of different prey is a key factor governing at-sea distributions and dietary composition of this species

The ‘Complex World’ of the Hsp90 Co-chaperone R2TP

The Hsp90 co-chaperone R2TP consists of the AAA+ ATPases, RUVBL1 (Rvb1p in yeast) and RUVBL2 (Rvb2 in yeast), which together make up a heterohexameric ring, in complex with PIH1D1 (Pih1p in yeast) and RPAP3 (Tah1p in yeast). R2TP is involved in the activation of client proteins, such as phosphatidylinositol 3 kinase-related kinases, including mTORC1, ATM, DNA-PK, SMG and ATR/ATRIP, or in the assembly of protein complexes including those of RNA polymerase and snoRNPs, amongst others. In other cases, the role of the TP component (RPAP3-PIH1D1) of R2TP, and consequently Hsp90, is controversial. None-the-less, the extensive role of RUVBL1-RUVBL2 complex in cells, either with or without Hsp90, means that dysfunction of these AAA+ ATPases, Hsp90 or components of the complexes they assemble leads to diseases such as cancer, ciliary dyskinesia and in the case of defects in ATM to ataxia telangiectasia-like syndrome. Recent advances in determining the structure of the R2TP complex has led to an increased understanding of the assembly and function of the R2TP complex. In this review we discuss the current structural advances in determining the architecture of the R2TP complex and the advances made in understanding its active state