Influence of macro- and micronutrient fertilization on fungal contamination and fumonisin production in corn grains

The aim of this study was to investigate the effects of nutrients (nitrogen, zinc and boron) on fungal growth and fumonisins production in corn samples obtained at the beginning of grain formation and at harvest. Three nitrogen doses were applied to the corn plants through soil in combination with three zinc doses and two boron doses during sowing. Mycological analysis of grains, using Dichloran Rose-Bengal Chloramphenicol Agar, collected at the beginning of formation demonstrated a fungal population predominantly of yeasts. Analysis of freshly harvested corn revealed a higher frequency of Penicillium spp. (72%) and F verticillioides (27%). High Performance Liquid Chromatography analysis revealed that 100% of grains were contaminated with fumonisins B, at levels ranging from 0.3 to 24.3 mg/kg and 93% contaminated with fumonisin B(2) at levels ranging from 0.05 to 5.42 mg/kg. Nitrogen (50 kg/ha) in combination with boron (0.5 kg/ha) resulted in an increased fumonisin B2 production. (c) 2007 Elsevier Ltd. All rights reserved.

Package models and the information crisis of prebiotic evolution

The coexistence between different types of templates has been the choice solution to the information crisis of prebiotic evolution, triggered by the finding that a single RNA-like template cannot carry enough information to code for any useful replicase. In principle, confining d distinct templates of length L in a package or protocell, whose Survival depends on the coexistence of the templates it holds in, could resolve this crisis provided that d is made sufficiently large. Here we review the prototypical package model of Niesert et al. [1981. Origin of life between Scylla and Charybdis. J. Mol. Evol. 17, 348-353] which guarantees the greatest possible region of viability of the protocell population, and show that this model, and hence the entire package approach, does not resolve the information crisis. In particular, we show that the total information stored in a viable protocell (Ld) tends to a constant value that depends only on the spontaneous error rate per nucleotide of the template replication mechanism. As a result, an increase of d must be followed by a decrease of L, so that the net information gain is null. (C) 2008 Elsevier Ltd. All rights reserved.