Mycorrhiza‐mediated interference between cover crop and weed in organic winter cereal agroecosystems: The mycorrhizal colonization intensity indicator

The mycorrhizal fungi are symbiotic organisms able to provide many benefits to crop production by supplying a set of ecosystem functions. A recent ecological approach based on the ability of the fungi community to influence plant–plant interactions by extraradical mycelium development may be applied to diversified, herbaceous agroecosystems. Our hypothesis is that the introduction of a winter cereal cover crop (CC) as arbuscular mycorrhizal fungi (AMF)–host plant in an organic rotation can boosts the AMF colonization of the other plants, influencing crop–weed interference. In a 4‐years organic rotation, the effect of two winter cereal CC, rye and spelt, on weed density and AMF colonization was evaluated. The AMF extraradical mycelium on CC and weeds roots was observed by scanning electron microscopy analysis. By joining data of plant density and mycorrhization, we built the mycorrhizal colonization intensity of the Agroecosystem indicator (MA%). Both the CC were colonized by soil AMF, being the mycorrhizal colonization intensity (M%) affected by environmental conditions. Under CC, the weed density was reduced, due to the increase of the reciprocal competition in favor of CC, which benefited from mycorrhizal colonization and promoted the development of AMF extraradical mycelium. Even though non‐host plants, some weed species showed an increased mycorrhizal colonization in presence of CC respect to the control. Under intense rainfall, the MA% was less sensitive to the CC introduction. On the opposite, under highly competitive conditions, both the CC boosted significantly the mycorrhization of coexistent plants in the agroecosystem. The proposed indicator measured the agroecological service provided by the considered CCs in promoting or inhibiting the overall AMF colonization of the studied agroecosystems, as affected by weed selection and growth: It informs about agroecosystem resilience and may be profitably applied to indicate the extent of the linkage of specific crop traits to agroecosystem services, contributing to further develop the functional biodiversity theory.     

Chemical reduction of pterins to dihydropterins as substrates for enzymatic reactions

Dihydropterins are important intermediates in various metabolic pathways, including the biosynthesis of tetrahydrofolate and tetrahydromethanopterin, a key coenzyme in the one-carbon metabolism of methanogenic Archaea. Some procedures for the reduction of pterins to dihydropterins may produce undesirable tetrahydropterin contaminants. This work describes a procedure for the rapid reduction of pterins to dihydropterins while minimizing tetrahydropterin production that may be particularly useful in producing substrates for enzyme reactions when the dihydropterin substrate cannot be purchased commercially.     

Restless Legs Syndrome and lateralized periodic movements due to a spinal schwannoma

We describe a case of Restless Legs Syndrome (RLS) associated to periodic limb movements (PLMs) in a woman with a cervical schwannoma. Neurological examination, laboratory tests, neurography and electromyography were unremarkable. Neuroimaging evidenced a schwannoma at C3 level that compressed the right ventral surface of the medulla. Somatosensory-evoked potentials showed absence of the N13 after right median nerve stimulation and reduction of amplitude of the same component after left nerve stimulation. A video-polysomnography documented PLMs with a marked prevalence of the right-sided movements. We believe that the cervical schwannoma played a role in the pathogenesis of RLS and of lateralized PLMs.