Seed longevity - moisture content relationships in hermetic and open storage

In seed storage research, moisture content can be maintained by providing a stable relative humidity (e.g. over saturated salt solutions) or by hermetic storage, but the two approaches provide different gaseous environments which might affect longevity. Seeds of timothy (Phleum pratense L.) and sesame (Sesamum indicum L.) were stored at 45 degrees C or 50 degrees C, respectively, with different moisture contents maintained by hermetic storage in laminated-aluminium-foil packets, or by desiccators above either saturated salt solutions or moistened silica gel. Seeds were withdrawn from storage at intervals from 1 to 28 d for up to 480 d and viability estimated. Within a species, the negative logarithmic relation between seed longevity and moisture content did not differ (P> 0.25, timothy; >0.05, sesame) between storage in desiccators over either moistened silica gel or saturated salt solutions, whereas the relation was much steeper (P< 0.005) in hermetic storage: longevity was similar at high moisture contents, but at low values much greater with hermetic storage. This effect of storage method on seed longevity's sensitivity to moisture content implies that oxygen is relatively more deleterious to seeds at lower than at greater moisture contents and confirms that hermetic storage is preferable for long-term seed storage at low moisture contents.

Formal total synthesis of (±)-conduramine E utilising the Bryce-Smith-Gilbert photoamination reaction

Utilising a Bryce-Smith-Gilbert photoamination of benzene as a key step, a synthesis of ()-conduramine E was carried out. A highly regioselective dihydroxylation of a cyclic diene was effected utilising Sharpless AD-mix-b.

Platelet PECAM-1 inhibits thrombus formation in vivo

Platelet endothelial cell adhesion molecule-1 (PECAM-1) is a cell surface glycoprotein receptor expressed on a range of blood cells, including platelets, and on vascular endothelial cells. PECAM-1 possesses adhesive and signaling properties, the latter being mediated by immunoreceptor tyrosine-based inhibitory motifs present on the cytoplasmic tail of the protein. Recent studies in vitro have demonstrated that PECAM-1 signaling inhibits the aggregation of platelets. In the present study we have used PECAM-1-deficient mice and radiation chimeras to investigate the function of this receptor in the regulation of thrombus formation. Using intravital microscopy and laser-induced injury to cremaster muscle arterioles, we show that thrombi formed in PECAM-1-deficient mice were larger, formed more rapidly than in control mice, and were more stable. Larger thrombi were also formed in control mice that received transplants of PECAM-1-deficient bone marrow, in comparison to mice that received control transplants. A ferric chloride model of thrombosis was used to investigate thrombus formation in carotid arteries. In PECAM-1-deficient mice the time to 75% vessel occlusion was significantly shorter than in control mice. These data provide evidence for the involvement of platelet PECAM-1 in the negative regulation of thrombus formation.

Genome expansion and gene loss in powdery mildew fungi reveal tradeoffs in extreme parasitism

Powdery mildews are phytopathogens whose growth and reproduction are entirely dependent on living plant cells. The molecular basis of this life-style, obligate biotrophy, remains unknown. We present the genome analysis of barley powdery mildew, Blumeria graminis f.sp. hordei (Blumeria), as well as a comparison with the analysis of two powdery mildews pathogenic on dicotyledonous plants. These genomes display massive retrotransposon proliferation, genome-size expansion, and gene losses. The missing genes encode enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, probably reflecting their redundancy in an exclusively biotrophic life-style. Among the 248 candidate effectors of pathogenesis identified in the Blumeria genome, very few (less than 10) define a core set conserved in all three mildews, suggesting thatmost effectors represent species-specific adaptations.