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 Seeds were withdrawn from storage at intervals from 1 to 28 d for up to 480 d and viability estimated.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.

Viral nucleolar localisation signals determine dynamic trafficking within the nucleolus

Localisation of both viral and cellular proteins to the nucleolus is determined by a variety of factors including nucleolar localisation signals (NoLSs), but how these signals operate is not clearly understood. The nucleolar trafficking of wild type viral proteins and chimeric proteins, which contain altered NoLSs, were compared to investigate the role of NoLSs in dynamic nucleolar trafficking. Three viral proteins from diverse viruses were selected which localised to the nucleolus; the coronavirus infectious bronchitis virus nucleocapsid (N) protein, the herpesvirus saimiri ORF57 protein and the HIV-1 Rev protein. The chimeric proteins were N protein and ORF57 protein which had their own NoLS replaced with those from ORF57 and Rev proteins, respectively. By analysing the sub-cellular localisation and trafficking of these viral proteins and their chimeras within and between nucleoli using confocal microscopy and photo-bleaching we show that NoLSs are responsible for different nucleolar localisations and trafficking rates.

Identification of a novel mammalian post-translational modification, phosphocholine, on placental secretory polypeptides

Placental neurokinin B appears to be post-translationally modified by phosphocholine (PC) attached to the aspartyl side chain at residue 4 of the mature peptide. Corticotrophin releasing factor (CRF) was found to be expressed by the rat placenta with the main secreted forms being phosphocholinated proCRF+/- one or two polysaccharide moieties. A combination of high-pressure liquid chromatography (HPLC) and two-site immunometric analysis suggested that PC was also attached to the placental precursors of adrenocorticotrophin, hemokinin, activin and follistatin. However, the fully processed forms of rat placental activin and CRF were free of PC. Formerly, the parasitic filarial nematodes have used PC as a post-translational modification, attached via the polysaccharicle moiety of certain secretory glycoproteins to attenuate the host immune system allowing parasite survival, but it is the PC group itself which endows the carrier with the biological activity. The fact that treatment of proCRF peptides with phospholipase C but not endoglycosidase destroyed PC immunoreactivity suggested a simpler mode of attachment of PC to placental peptides than that used by nematodes. Thus, it is possible that by analogy the placenta uses its secreted phosphocholinated hormones to modulate the mother's immune system and help protect the placenta from rejection.