A reconsideration of terminology in Frankia research: A need for congruence

Progress in understanding the Frankia -actinorhizal symbiosis has paralleled that of the Rhizobium -legume symbiosis. Previously, these two nitrogen-fixing symbioses have been considered as distinct and unrelated entities. However, it seems likely that many of the developmental stages, and perhaps even the molecular signals, are shared between these two apparently independent associations. For this reason, we propose to emphasize the similarities between the two symbioses by calling for a uniformity of terminology to describe nodule development.     

Shear Pulses Nucleate Fibril Aggregation

We have studied the effect of shear flow on the formation of amyloid fibrils of the whey protein β-lactoglobulin. β-Lactoglobulin aggregates into long, thin, and semiflexible fibrils upon heating at low pH and low ionic strength. Solutions with a protein concentration of 0.5% (w/w) were used, and the formation of fibrils was quantified with flow-induced birefringence, a proportional measure of the length concentration of the fibrils. From the decay of the birefringence after cessation of the flow, a length distribution could be fitted. Pulsed and continuous shear treatment of the samples resulted in a comparable enhancement of the fibrillar growth as compared to the fibrillar growth under quiescent conditions. This indicates that the onset of shear flow is the key parameter for the enhancement of fibrillar growth and not the continuous shear flow itself. This behavior is comparable to a nucleation-like process, during which preaggregates of the fibrils are induced during the onset of the flow and orthokinetic coagulation is absent. However, a difference was present in the length distribution between the pulsed and continuously sheared samples, which can be explained by the homogenizing effect of shear flow.