A Note on Ice Island WH-5

As reported by Hattersley-Smith, Ice Island WH-5, the easternmost and largest (approximately 20 by 9 km.) of the islands resulting from the massive calving of the Ward Hunt Ice Shelf during the winter 1961-2, drifted eastward, whereas the other four islands drifted westward. WH-5, tracked through radar photography by the U.S. Navy "Birdseye" ice reconnaissance flights, continued its eastward movement during the winter 1962-3. It entered the Lincoln Sea, moved south through Robeson Channel and between February 24 and 28, 1963 became lodged across Kennedy Channel, with one end resting against the shore of Ellesmere Island and the other end held by mid-channel Hans Island. In this position the ice island formed an effective barrier to the southward movement of sea-ice from the Arctic Ocean. Open water soon appeared south of the obstruction and by May extended well into Kane Basin. In a study of WH-5 during the summer of 1963 emphasis was placed on physical oceanography, both to observe the local influence of the ice island and to take advantage of the unusual presence of open water in an area where ice normally restricts ship operations. The study was directed by D. C. Nutt and L. K. Coachman and was sponsored by the Arctic Institute with support from the U.S. Office of Naval Research and the U.S. Coast Guard and the collaboration of the Woods Hole Oceanographic Institution, the U.S. Naval Oceanographic Office, the U.S. Military Sea Transportation Service and the U.S. Air Force at Thule, Greenland. ... This brief note, based only on data immediately available, is being published to provide timely information on the recent drift and break-up of ice island WH-5. A more comprehensive report will follow. ..

A Note on Ice Island WH-5

As reported by Hattersley-Smith, Ice Island WH-5, the easternmost and largest (approximately 20 by 9 km.) of the islands resulting from the massive calving of the Ward Hunt Ice Shelf during the winter 1961-2, drifted eastward, whereas the other four islands drifted westward. WH-5, tracked through radar photography by the U.S. Navy "Birdseye" ice reconnaissance flights, continued its eastward movement during the winter 1962-3. It entered the Lincoln Sea, moved south through Robeson Channel and between February 24 and 28, 1963 became lodged across Kennedy Channel, with one end resting against the shore of Ellesmere Island and the other end held by mid-channel Hans Island. In this position the ice island formed an effective barrier to the southward movement of sea-ice from the Arctic Ocean. Open water soon appeared south of the obstruction and by May extended well into Kane Basin. In a study of WH-5 during the summer of 1963 emphasis was placed on physical oceanography, both to observe the local influence of the ice island and to take advantage of the unusual presence of open water in an area where ice normally restricts ship operations. The study was directed by D. C. Nutt and L. K. Coachman and was sponsored by the Arctic Institute with support from the U.S. Office of Naval Research and the U.S. Coast Guard and the collaboration of the Woods Hole Oceanographic Institution, the U.S. Naval Oceanographic Office, the U.S. Military Sea Transportation Service and the U.S. Air Force at Thule, Greenland. ... This brief note, based only on data immediately available, is being published to provide timely information on the recent drift and break-up of ice island WH-5. A more comprehensive report will follow. ..

Metabolic Control of Oocyte Apoptosis Mediated by 14-3-3zeta-regulated Dephosphorylation of Caspase-2

Xenopus oocyte death is partly controlled by the apoptotic initiator caspase-2 (C2). We reported previously that oocyte nutrient depletion activates C2 upstream of mitochondrial cytochrome c release. Conversely, nutrient-replete oocytes inhibit C2 via S135 phosphorylation catalyzed by calcium/calmodulin-dependent protein kinase II. We now show that C2 phosphorylated at S135 binds 14-3-3zeta, thus preventing C2 dephosphorylation. Moreover, we determined that S135 dephosphorylation is catalyzed by protein phosphatase-1 (PP1), which directly binds C2. Although C2 dephosphorylation is responsive to metabolism, neither PP1 activity nor binding is metabolically regulated. Rather, release of 14-3-3zeta from C2 is controlled by metabolism and allows for C2 dephosphorylation. Accordingly, a C2 mutant unable to bind 14-3-3zeta is highly susceptible to dephosphorylation. Although this mechanism was initially established in Xenopus, we now demonstrate similar control of murine C2 by phosphorylation and 14-3-3 binding in mouse eggs. These findings provide an unexpected evolutionary link between 14-3-3 and metabolism in oocyte death