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The European Union (EU) seems to presume that the mass production of European research papers indicates that Europe is a leading scientific power, and the so-called European paradox of strong science but weak technology is due to inefficiencies in the utilization of this top level European science by European industry. We fundamentally disagree, and will show that Europe lags far behind the USA in the production of important, highly cited research. We will show that there is a consistent weakening of European science as one ascends the citation scale, with the EU almost twice as effective in the production of minimal impact papers, while the USA is at least twice as effective in the production of very highly cited scientific papers, and garnering Nobel prizes. Only in the highly multinational, collaborative fields of Physics and Clinical Medicine does the EU seem to approach the USA in top scale impact.

The function of HAK transporters in high-affinity K+ uptake in plants is well established; this study aims to demonstrate that some transporters of the same family play important roles in endomembranes. The PpHAK2-PpHAK4 genes of Physcomitrella patens encode three transporters of high sequence similarity. Quantitative PCR showed that PpHAK2 and PpHAK3 transcripts are expressed at approximately the same level as the PpACT5 gene, while the expression of PpHAK4 seems to be restricted to specific conditions that have not been determined. KHA1 is an endomembrane K+/H+ antiporter of Saccharomyces cerevisiae, and the expression of the PpHAK2 cDNA, but not that of PpHAK3, suppressed the defect of a kha1 mutant. Transient expression of the PpHAK2-green fluorescent protein (GFP) and PpHAK3-GFP fusion proteins in P. patens protoplasts localized to the endoplasmic reticulum and Golgi complex, respectively. To determine the function of PpHAK2 and PpHAK3 in planta, we constructed ΔPphak2 and ΔPphak2 ΔPphak3 plants. ΔPphak2 plants were normal under all of the conditions tested except under K+ starvation or at acidic pH in the presence of acetic acid, whereupon they die. The defect observed under K+ starvation was suppressed by the presence of Na+. We propose that PpHAK2 may encode either a K(+)-H(+) symporter or a K+/H+ antiporter that mediates the transfer of H+ from the endoplasmic reticulum lumen to the cytosol. PpHAK2 may be a model of the second function of HAK transporters in plant cells. The disruption of the PpHAK3 gene in ΔPphak2 plants showed no effect.

The widespread presence of Na(+)-specific uptake systems across plants and fungi is a controversial topic. In this study, we identify two HAK genes, one in the moss Physcomitrella patens and the other in the yeast Yarrowia lipolytica, that encode Na(+)-specific transporters. Because HAK genes are numerous in plants and are duplicated in many fungi, our findings suggest that some HAK genes encode Na(+) transporters and that Na(+) might play physiological roles in plants and fungi more extensively than is currently thought.

In recent years major progress has been achieved in the understanding of transport processes in higher plants. The boom in the field of molecular plant physiology led to the identification and characterization of membrane transporters with transport activities for potassium, calcium, sugars, nitrate, ammonium, sulphate, phosphate, amino acids, peptides, and metal ions. Such progress was hardly feasible without heterologous expression of the isolated transport proteins. This review summarizes the different approaches in characterizing plant membrane transporters using heterologous expression systems. By presenting concrete examples, it outlines different cloning strategies, displays the methods used for (i) expression of transport proteins and detection of their function, (ii) biochemical analyses, (iii) explorations of the structure-function relationship through mutational analysis, and concludes with a discussion about the physiological relevance of the analyses in heterologous expression systems.

The Rb+-uptake kinetics in K+-starved sunflower (Helianthus annuus) plants can be explained by the addition of two Michaelis-Menten equations. In contrast, Rb+ uptake can be described by a single Michaelis-Menten equation in normal-K+ plants. Differences in the Kms and in the Arrhenius plots of Rb+ uptake in the two types of plants suggest two uptake modes.