University of Basel

About: University of Basel is a education organization based out in Basel, Basel-Stadt, Switzerland. It is known for research contribution in the topics: Population & Gene. The organization has 25084 authors who have published 52975 publications receiving 2388002 citations. The organization is also known as: Universität Basel & Basel University.

The evolution of interspecific mutualisms

Abstract: Interspecific mutualisms are widespread, but how they evolve is not clear. The Iterated Prisoner’s Dilemma is the main theoretical tool to study cooperation, but this model ignores ecological differences between partners and assumes that amounts exchanged cannot themselves evolve. A more realistic model incorporating these features shows that strategies that succeed with fixed exchanges (e.g., Tit-for-Tat) cannot explain mutualism when exchanges vary because the amount exchanged evolves to 0. For mutualism to evolve, increased investments in a partner must yield increased returns, and spatial structure in competitive interactions is required. Under these biologically plausible assumptions, mutualism evolves with surprising ease. This suggests that, contrary to the basic premise of past theoretical analyses, overcoming a potential host’s initial defenses may be a bigger obstacle for mutualism than the subsequent recurrence and spread of noncooperative mutants.

General stabilizing effects of plant diversity on grassland productivity through population asynchrony and overyielding

Abstract: Insurance effects of biodiversity can stabilize the functioning of multispecies ecosystems against environmental variability when differential species' responses lead to asynchronous population dynamics. When responses are not perfectly positively correlated, declines in some populations are compensated by increases in others, smoothing variability in ecosystem productivity. This variance reduction effect of biodiversity is analogous to the risk-spreading benefits of diverse investment portfolios in financial markets. We use data from the BIODEPTH network of grassland biodiversity experiments to perform a general test for stabilizing effects of plant diversity on the temporal variability of individual species, functional groups, and aggregate communities. We tested three potential mechanisms: reduction of temporal variability through population asynchrony; enhancement of long-term average performance through positive selection effects; and increases in the temporal mean due to overyielding. Our results support a stabilizing effect of diversity on the temporal variability of grassland aboveground annual net primary production through two mechanisms. Two-species communities with greater population asynchrony were more stable in their average production over time due to compensatory fluctuations. Overyielding also stabilized productivity by increasing levels of average biomass production relative to temporal variability. However, there was no evidence for a performance-enhancing effect on the temporal mean through positive selection effects. In combination with previous work, our results suggest that stabilizing effects of diversity on community productivity through population asynchrony and overyielding appear to be general in grassland ecosystems.

Proton-powered turbine of a plant motor

Abstract: ATP synthases are enzymes that can work in two directions to catalyse either the synthesis or breakdown of ATP, and they constitute the smallest rotary motors in biology The flow of protons propels the rotation1 of a membrane-spanning complex of identical protein subunits, the number of which determines the efficiency of energy conversion This proton-powered turbine is predicted to consist of 12 subunits2,3,4, based on data for Escherichia coli5 The yeast mitochondrial enzyme, however, has only 10 subunits6 We have imaged the ATP synthase from leaf chloroplasts by using atomic force microscopy and, surprisingly, find that its turbine has 14 subunits, arranged in a cylindrical ring

Laminin-nidogen complex. Extraction with chelating agents and structural characterization.

Abstract: Large quantities of intact laminin-nidogen complex could be extracted from a mouse tumor basement membrane with a physiological buffer containing EDTA. Analysis of the purified complex demonstrated that the two proteins occur in an equimolar ratio and that anchoring of these complexes to the extracellular matrix requires divalent cations. Reversible dissociation of the complex was achieved with 2 M guanidine X HCl and has been used for purification of the individual components. Electron microscopy and binding studies using laminin fragments demonstrated that nidogen interacts specifically with the center of the cross-shaped laminin molecule as represented by the short-arm structure fragment 1. The complex was also useful to confirm and refine a previously proposed dumb-bell structure of nidogen and to prepare and characterize the cell-binding fragment 8 from the long arm of laminin.