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The paper offers a survey of monastic island communities in Medieval Norway, including brief historical descriptions of their foundation, patrons, dissolution, sources, remaining building structure...

The RNA binding protein AtGRP7 is part of a circadian slave oscillator in Arabidopsis thaliana that negatively autoregulates its own mRNA, and affects the levels of other transcripts. Here, we identify a novel role for AtGRP7 as a flowering-time gene. An atgrp7-1 T-DNA mutant flowers later than wild-type plants under both long and short days, and independent RNA interference lines with reduced levels of AtGRP7, and the closely related AtGRP8 protein, are also late flowering, particularly in short photoperiods. Consistent with the retention of a photoperiodic response, the transcript encoding the key photoperiodic regulator CONSTANS oscillates with a similar pattern in atgrp7-1 and wild-type plants. In both the RNAi lines and in the atgrp7-1 mutant transcript levels for the floral repressor FLC are elevated. Conversely, in transgenic plants ectopically overexpressing AtGRP7, the transition to flowering is accelerated mainly in short days, with a concomitant reduction in FLC abundance. The late-flowering phenotype of the RNAi lines is suppressed by introducing the flc-3 loss-of-function mutation, suggesting that AtGRP7 promotes floral transition, at least partly by downregulating FLC. Furthermore, vernalization overrides the late-flowering phenotype. Retention of both the photoperiodic response and vernalization response are features of autonomous pathway mutants, suggesting that AtGRP7 is a novel member of the autonomous pathway.

The atpB and atpF genes of Propionigenium modestum were cloned as His-tag fusion constructs and expressed in Escherichia coli. Both recombinant subunits a and b were purified via Ni2+ chelate affinity chromatography. A functionally active Fo complex was reassembled in vitro from subunits a, b and c, and incorporated into liposomes. The Fo liposomes catalysed 22Na+ uptake in response to an inside negative potassium diffusion potential, and the uptake was prevented by modification of the c subunits with N,N′-dicyclohexylcarbodiimide (DCCD). In the absence of a membrane potential the Fo complexes catalysed 22Na+out/Na+in-exchange. After F1 addition the F1Fo complex was formed and the holoenzyme catalysed ATP synthesis, ATP dependent Na+ pumping, and ATP hydrolysis, which was inhibited by DCCD. Functional Fo hybrids were reconstituted with recombinant subunits a and b from P. modestum and c11 from Ilyobacter tartaricus. These Fo hybrids had Na+ translocation activities that were not distinguishable from that of P. modestum Fo.

Plants, as sessile organisms, are forced to take advantage of the limited availability of sunlight, their most important resource. Not surprisingly, many aspects of physiology and development are therefore organized by an endogenous chronometer in plants. This so-called ‘circadian’ clock imposes a 24-hour rhythm on metabolic reactions and physiological processes to optimally align them with the environmental light-dark cycle1.

The use of attenuated classical swine fever virus (CSFV) strains as live vaccines is no longer allowed for the control of classical swine fever in Europe, due to the inability to differentiate between infected and vaccinated animals (Differentiating Infected from Vaccinated Animals; DIVA), except as emergency vaccines or as bait vaccines for wild boars. Thus, the establishment of a DIVA vaccine(s) is of pivotal importance for the control of this infectious disease. In this study, recombinant versions of the live-attenuated vaccine strain CSFV Riems were generated by replacing parts of the E2 gene with the corresponding sequence of border disease virus strain Gifhorn. Three cDNA clones were constructed: pRiems-ABC-Gif, pRiems-A-Gif and pRiems-BC-Gif. Infectious particles were obtained from clones pRiems-ABC-Gif and pRiems-BC-Gif only, whereas transfected RNA from clone pRiems-A-Gif behaved like a replicon. Based on its ability to be differentiated in vitro from wild-type CSFV by mAbs, vRiems-ABC-Gif was assessed for immunogenicity and protection against challenge infection in pigs. Before challenge, no CSFV-specific anti-E2 antibodies could be detected with commercial E2-blocking ELISAs in vRiems-ABC-Gif-vaccinated animals, whereas vRiems-vaccinated pigs developed high titres of anti-E2 antibodies, confirming the marker properties of this vaccine candidate. After oral vaccination, only partial protection against challenge infection was observed in the vRiems-ABC-Gif vaccinees, whereas all intramuscularly vaccinated animals and all vRiems-vaccinated animals were fully protected. These experiments suggest that the strategy of exchanging specific antigenic epitopes among pestiviruses is a promising tool for the development of new CSFV marker vaccines.

The most prominent residue of subunit a of the F 1 F o ATP synthase is a universally conserved arginine (aR227 in Propionigenium modestum ), which was reported to permit no substitution with retention of ATP synthesis or H + -coupled ATP hydrolysis activity. We show here that ATP synthases with R227K or R227H mutations in the P. modestum a subunit catalyse ATP-driven Na + transport above or below pH 8.0, respectively. Reconstituted F o with either mutation catalysed 22 Na + out /Na + in exchange with similar pH profiles as found in ATP-driven Na + transport. ATP synthase with an aR227A substitution catalysed Na + -dependent ATP hydrolysis, which was completely inhibited by dicyclohexylcarbodiimide, but not coupled to Na + transport. This suggests that in the mutant the dissociation of Na + becomes more difficult and that the alkali ions remain therefore permanently bound to the c subunit sites. The reconstituted mutant enzyme was also able to synthesise ATP in the presence of a membrane potential, which stopped at elevated external Na + concentrations. These observations reinforce the importance of aR227 to facilitate the dissociation of Na + from approaching rotor sites. This task of aR227 was corroborated by other results with the aR227A mutant: (i) after reconstitution into liposomes, F o with the aR227A mutation did not catalyse 22 Na + out /Na + in exchange at high internal sodium concentrations, and (ii) at a constant ΔpNa + , 22 Na + uptake was inhibited at elevated internal Na + concentrations. Hence, in mutant aR227A, sodium ions can only dissociate from their rotor sites into a reservoir of low sodium ion concentration, whereas in the wild-type the positively charged aR227 allows the dissociation of Na + even into compartments of high Na + concentration.

The atpB and atpF genes of Propionigenium modestum were cloned as His-tag fusion constructs and expressed in Escherichia coli. Both recombinant subunits a and b were purified via Ni(2+) chelate affinity chromatography. A functionally active Fo complex was reassembled in vitro from subunits a, b and c, and incorporated into liposomes. The F(o) liposomes catalysed (22)Na(+) uptake in response to an inside negative potassium diffusion potential, and the uptake was prevented by modification of the c subunits with N,N'-dicyclohexylcarbodiimide (DCCD). In the absence of a membrane potential the Fo complexes catalysed (22)Na(+)(out)/Na(+)(in)-exchange. After F(1) addition the F(1)F(o) complex was formed and the holoenzyme catalysed ATP synthesis, ATP dependent Na(+) pumping, and ATP hydrolysis, which was inhibited by DCCD. Functional F(o) hybrids were reconstituted with recombinant subunits a and b from P. modestum and c(11) from Ilyobacter tartaricus. These Fo hybrids had Na(+) translocation activities that were not distinguishable from that of P. modestum F(o).

The conserved glutamate residue at position 65 of the Propionigenium modestum c subunit is directly involved in binding and translocation of Na+ across the membrane. The site-specific introduction of the cQ32I and cS66A substitutions in the putative vicinity to cE65 inhibited growth of the single-site mutants on succinate minimal agar, indicating that both amino acid residues are important for proper function of the oxidative phosphorylation system. This growth inhibition was abolished, however, if the cF84L/cL87V double mutation was additionally present in the P. modestum c subunit. The newly constructed Escherichia coli strain MPC848732I, harboring the cQ32I/cF84L/cL87V triple mutation, revealed a change in the coupling ion specificity from Na+ to H+. ATP hydrolysis by this enzyme was therefore not activated by NaCl, and ATP-driven H+ transport was not affected by this alkali salt. Both activities were influenced, however, by LiCl. These data demonstrate the loss of the Na+ binding site and retention of Li+ and H+ binding sites within this mutant ATPase. In the E. coli strain MPC848766A (cS66A/cF84L/cL87V), the specificity of the ATPase was further restricted to H+ as the exclusive coupling ion. Therefore, neither Na+ nor Li+ stimulated the ATPase activity, and no ATP-driven Li+ transport was observed. The ATPase of the E. coli mutant MPC32N (cQ32N) was activated by NaCl and LiCl. The mutant ATPase exhibited a 5-fold higher Km for NaCl but no change in the Km for LiCl in comparison to that of the parent strain. These results demonstrate that the binding of Na+ to the c subunit of P. modestum requires liganding groups provided by Q32, E65, and S66. For the coordination of Li+, two liganding partners, E65 and S66, are sufficient, and H+ translocation was mediated by E65 alone.