Comparative landscape genetic analyses show a Belgian motorway to be a gene flow barrier for red deer (Cervus elaphus), but not wild boars (Sus scrofa).

While motorways are often assumed to influence the movement behaviour of large mammals, there are surprisingly few studies that show an influence of these linear structures on the genetic make-up of wild ungulate populations. Here, we analyse the spatial genetic structure of red deer (Cervus elaphus) and wild boars (Sus scrofa) along a stretch of motorway in the Walloon part of Belgium. Altogether, 876 red deer were genotyped at 13 microsatellite loci, and 325 wild boars at 14 loci. In the case of the red deer, different genetic clustering tools identified two genetic subpopulations whose borders matched the motorway well. Conversely, no genetic structure was identified in the case of the wild boar. Analysis of isolation-by-distance patterns of pairs of individuals on the same side and on different sides of the motorway also suggested that the road was a barrier to red deer, but not to wild boar movement. While telemetry studies seem to confirm that red deer are more affected by motorways than wild boar, the red deer sample size was also much larger than that of the wild boars. We therefore repeated the analysis of genetic structure in the red deer with randomly sub-sampled data sets of decreasing size. The power to detect the genetic structure using clustering methods decreased with decreasing sample size.

Plant cell membranes as biochemical targets of the phytotoxin helminthosporol.

Helminthosporol is one of the natural sesquiterpenoid toxins isolated and identified in the culture medium of the phytopathogenic ascomycete fungus Cochliobolus sativus. The effect of this phytotoxin was investigated on enzymatic activities, electron and ion transport in mitochondria, chloroplasts, and microsomes of plant. The results indicate that helminthosporol drastically affects the membrane permeability of these organelles to protons and substrate anions, inhibiting the mitochondrial oxidative phosphorylation, the photophosphorylation in chloroplasts, and the proton pumping across the cell plasma membrane. The 1,3-beta-glucan synthase activity, involved in defense mechanisms of plant cells against stress and damage, e.g., during pathogen attack, was also strongly inhibited by the toxin.