Long term resilience decline in plant ecosystems across the Danian Dan-C2 hyperthermal event, Boltysh crater, Ukraine

Acknowledgements and Funding The authors are extremely grateful for the receipt of NERC award NE/ D005043/1, which funded the initial Boltysh impact crater study. R. Spicer and J. Leake are thanked for interesting discussions. C. Wellman, W. Gosling and M. Donovan are thanked for constructively critical reviews of the paper. Scientific editing by Quentin Crowley

Ordered water molecules as key allosteric mediators in a cooperative dimeric hemoglobin

One of the most remarkable structural aspects of Scapharca dimeric hemoglobin is the disruption of a very well-ordered water cluster at the subunit interface upon ligand binding. We have explored the role of these crystallographically observed water molecules by site-directed mutagenesis and osmotic stress techniques. The isosteric mutation of Thr-72 → Val in the interface increases oxygen affinity more than 40-fold with a surprising enhancement of cooperativity. The only significant structural effect of this mutation is to destabilize two ordered water molecules in the deoxy interface. Wild-type Scapharca hemoglobin is strongly sensitive to osmotic conditions. Upon addition of glycerol, striking changes in Raman spectrum of the deoxy form are observed that indicate a transition toward the liganded form. Increased osmotic pressure, which lowers the oxygen affinity in human hemoglobin, raises the oxygen affinity of Scapharca hemoglobin regardless of whether the solute is glycerol, glucose, or sucrose. Analysis of these results provides an estimate of six water molecules lost upon oxygen binding to the dimer, in good agreement with eight predicted from crystal structures. These experiments suggest that the observed cluster of interfacial water molecules plays a crucial role in communication between subunits.

San Francisco Bay Area, California, Nautical Chart, 1889 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: San Francisco entrance, California, United States Coast and Geodetic Survey ; eng.d by J. Enthoffer, E.A. Maedel, J.J. Young, W.A. Thompson, H.M. Knight, A. Peterson, and J.G. Thompson; red.r dr.ng by A. Lindenkohl, C. Junken, E. Molkow, E.J. Sommer. It was published by U.S.C. & G.S., printed March 15, 1889, corrected to April 12, 1889. Scale 1:40,000. Covers the San Francisco Bay Area. The image inside the map neatline is georeferenced to the surface of the earth and fit to the California Zone III State Plane Coordinate System NAD83 (in Feet) (Fipszone 0403). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows coastal features such as lighthouses, buoys, beacons, rocks, channels, points, coves, islands, bottom soil types, wharves, and more. Includes also selected land features such as roads, railroads, drainage, land cover, selected buildings, towns, and more. Relief shown by contours and spot heights; depths by soundings. Includes notes, tables, and list of authorities. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

San Francisco, California and vicinity, 1954 (Raster Image)

This layer is a georeferenced raster image of the United States Geological Survey sheet map entitled: San Francisco and vicinity, California, 1954. It was published in 1957. Scale 1:24,000. Compiled from 1:24,000 scale maps of the San Quentin 1947, San Rafael 1954, Point Bonita 1954, San Francisco North 1947, and San Francisco South 1947 7.5 minute quadrangles. Hydrography compiled from USC&GS charts 5532 and 5402. The image inside the map neatline is georeferenced to the surface of the earth and fit to the California Zone III State Plane Coordinate System NAD27 (in Feet) (Fipszone 0403). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. USGS maps are typical topographic maps portraying both natural and manmade features. They show and name works of nature, such as mountains, valleys, lakes, rivers, vegetation, etc. They also identify the principal works of humans, such as roads, railroads, boundaries, transmission lines, major buildings, etc. Relief is shown with contour intervals 25 and 40 feet with supplementary contours at 5 and 20 foot intervals and spot heights. Please pay close attention to map collar information on projections, spheroid, sources, dates, and keys to grid numbering and other numbers which appear inside the neatline. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.