Letter. Episodic fresh surface waters in the Eocene Arctic Ocean

It has been suggested, on the basis of modern hydrology and fully coupled palaeoclimate simulations, that the warm greenhouse conditions that characterized the early Palaeogene period (55–45 Myr ago) probably induced an intensified hydrological cycle with precipitation exceeding evaporation at high latitudes. Little field evidence, however, has been available to constrain oceanic conditions in the Arctic during this period. Here we analyse Palaeogene sediments obtained during the Arctic Coring Expedition, showing that large quantities of the free-floating fern Azolla grew and reproduced in the Arctic Ocean by the onset of the middle Eocene epoch (50 Myr ago). The Azolla and accompanying abundant freshwater organic and siliceous microfossils indicate an episodic freshening of Arctic surface waters during an 800,000-year interval. The abundant remains of Azolla that characterize basal middle Eocene marine deposits of all Nordic seas probably represent transported assemblages resulting from freshwater spills from the Arctic Ocean that reached as far south as the North Sea. The termination of the Azolla phase in the Arctic coincides with a local sea surface temperature rise from 10°C to 13°C, pointing to simultaneous increases in salt and heat supply owing to the influx of waters from adjacent oceans. We suggest that onset and termination of the Azolla phase depended on the degree of oceanic exchange between Arctic Ocean and adjacent seas

Functional characterization of a defense-related class-III chitinase promoter from Lupinus albus, active in legume and monocot tissues

A class-III chitinase promoter was isolated from Lupinus albus. The region 5′ to the coding sequence of the IF3 gene was amplified by gene walking and sequenced. The proximal 2.0 kb sequence contains a predicted promoter site, including a TATA box, near the ATG start site. To test for minimal sequences needed for promoter activity, the region was restricted into fragments of 1.81, 1.51 and 1.13 kb and cloned into the pDM327 vector, upstream from the bar-gus fusion gene for Biolistic™ transformation. Transformation of lupin embryos, bean callus tissue, maize embryos and Ornithogalum callus demonstrated promoter activity for all fragments. In silico analysis identified putative cis-acting elements in the 1.81 kb fragment that could be important in controlling gene expression. Fungal elicitor activated-, woundinducible- and ethylene responsive elements were present in the 1.51 kb fragment. Myb elements and CAAT boxes that regulate responses to environmental factors and modulate promoter efficiency were identified in the 1.81 kb fragment. The 1.51 and 1.81 kb fragments were inserted upstream of the gus gene into the pBI121 vector for Agrobacterium tumefaciens transformation of tobacco. Quantitative GUS assays indicated that the promoter fragments are functional in planta and inducible by defense-related signals, wounding, as well as chemical elicitation. All important elements essential for Bion inducibility are present on the shorter (1.51 kb) promoter fragment, but both 5′ distal and proximal cis-elements are required for full functionality. The IF3 promoter is, thus, suitable for use in defense gene constructs prepared for the production of anthracnose resistant lupin.South African Agricultural Research Council (ARC) and the Protein Research Trust (PRT).http://link.springer.com/journal/106582017-12-31hb2016Plant Scienc