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The term 'stay-green' (SG) is used in studies with varieties showing delayed senescence in the field. However, delayed appearance of visual symptoms of leaf senescence does not guarantee a longer duration of photosynthesis. The question arises whether the variation in photosynthetic capacity between silage maize varieties currently on the Belgian market is large enough to define different SG types. Furthermore, physiological traits were investigated as proxies for photosynthesis, including chlorophyll concentration, nitrogen (N) concentration, SPAD readings and greenness score. Finally, the functionality of the SG trait was determined by studying dry matter (DM) and N partitioning in the plants. To address these questions, eight silage maize varieties were monitored at two sites in Belgium over 2 years (2013-2014). Two plant types were found: hereafter called 'normal' and 'SG'. The SG varieties had higher values for photosynthetic capacity and they coincided with higher values for the proxies. Because a higher photosynthetic capacity did not provoke higher assimilate accumulation in the leaves, the SG trait was characterized as a cosmetic one. The SG trait influenced N dynamics in the plant: lower N translocation from the leaves to the ear resulted in lower ear N concentration and lower ear DM yield. No differences in whole-crop N concentration and whole-crop DM yield were found. As the SG trait mainly provokes shifts in partition of DM and N between vegetative and generative tissues, the energy source also shifts from starch (provided by the ear) to cell wall material (provided by the stover). [ABSTRACT FROM AUTHOR]

Silage maize variety testing systems usually evaluate new varieties within properly defined maturity groups; within a maturity group, all varieties are harvested on a single harvest date. In a small country like Belgium where growing conditions are similar across the maize growing areas, all tested silage maize varieties, comprising different maturity groups, are harvested on a single date. Under this testing system, only few varieties are harvested at the physiological stage where they theoretically show their optimal performance. In the current research, eight silage maize varieties were monitored from 25 to 40% whole-crop dry matter (DM) content at three locations in Belgium during the period 2007–2009. The optimal harvest date was calculated as the date where whole-crop DM yield, ear DM yield and organic matter digestibility were maximal. The variety rank at the optimal harvest date was compared with the variety rank at any studied single harvest date. Harvest dates where the variety rank was not statistically different to the rank at the optimal harvest date were pooled in a ‘harvest window’. Based on the current data, the harvest window comprised a flexible harvest period of about 14 days. It was therefore concluded that applying a single harvest date is scientifically justified for the ranking of silage maize varieties in Belgium, when the whole-crop DM content is between 28·1 and 40·6% with a maximum difference of 7·2% between all compared varieties. [ABSTRACT FROM PUBLISHER]

By using data of Belgian trials for Value of Cultivation and Use (1963–2007) the change in agronomic performance of ryegrass varieties was quantified. Data included 144 Lolium perenne and 69 Lolium multiflorum candidate varieties, plus ‘Vigor’ and ‘Lemtal’, two varieties which were always included in the Value of Cultivation and Use (VCU) trials. As the genetics of ‘Vigor’ and ‘Lemtal’ have remained identical to those in 1963, these were used as constant standards to measure improvements of new varieties. Dry matter yield (DMY) of ‘Vigor’ and ‘Lemtal’ varied annually but did not show a progressive change, indicating that cultural changes in VCU trials of ryegrasses were small. By expressing DMY, persistency and rust resistance of the candidate varieties relative to Vigor and ‘Lemtal’, the change in agronomic performance due to breeding was determined. DMY increased with 0.3% of ‘Vigor’ and ‘Lemtal’ annually. Persistency showed an annual increase around 0.5% of the standard varieties. Before 1990, rust resistance of ryegrasses varied around 100% relative to ‘Vigor’ or ‘Lemtal’. After 1990, an annual increase of 3.6% against these standard varieties was found. [ABSTRACT FROM AUTHOR]

Fumonisins are mycotoxins produced by the fungus F. verticillioides, a common contaminant of maize (corn) worldwide. Maternal consumption of fumonisin Bl-contaminated maize during early pregnancy has recently been associated with increased risk for neural tube defects (NTDs) in human populations that rely heavily on maize as a dietary staple. Experimental administration: of purified fumonisin to mice early in gestation also results in an increased incidence of NTDs in exposed offspring. Fumonisin inhibits the enzyme ceramide synthase in de novo sphingolipid biosynthesis, resulting in an elevation of free sphingoid bases and depletion of downstream glycosphingolipids. Increased sphingoid base metabolites (i.e., sphinganine-l-phosphate) may perturb signaling cascades involved in embryonic morphogenesis by functioning as ligands for sphingosine-1-P (S1P) receptors, a family of G-proteincoupled receptors that regulate key biological processes such as cell survival/proliferation, differentiation and migration. Fumonisininduced depletion of glycosphingolipids impairs expression and function of the GPI-anchored folate receptor (Folr1), which may also contribute to adverse pregnancy outcomes. NTDs appear to be multifactorial in origin, involving complex gene-nutrientenvironment interactions. Vitamin supplements containing folic acid have been shown to reduce the occurrence of NTDs, and may help protect the developing fetus from environmental teratogens. Fumonisins appear to be an environmental risk factor for birth defects, although other aspects of maternal nutrition and genetics play interactive roles in determining pregnancy outcome. Minimizing exposures to mycotoxins through enhanced agricultural practices, identifying biomarkers of exposure, characterizing mechanisms of toxicity, and improving maternal nutrition are all important strategies for reducing the NTD burden in susceptible human populations. [ABSTRACT FROM AUTHOR]

Abstract: Microphthalmia-associated transcription factor (Mitf) is expressed in neural crest cell-derived melanocytes, and in the retinal pigment epithelium (RPE) during ocular development. Mutations in Mitf are associated with auditory/visual/pigmentary syndromes in humans. Mitfmi/mi mouse mutants lack pigmentation, and are microphthalmic, while Mitfvit/vit mouse mutants display abnormal RPE pigmentation, and progressive retinal degeneration. Microarray analysis was used to identify novel downstream gene targets/pathways in the RPE that are altered by mutations in the transcription factor Mitf. Using the Affymetrix platform, gene expression profiles were generated using the eyes of E13.5 mouse fetuses that were wildtype, heterozygous, or homozygous for the Mitfmi mutation. In a separate experiment, eyes from E13.5 mouse fetuses homozygous for the Mitfvit mutation were compared to eyes from the C57BL/6 control background strain. Statistical analyses were performed using robust multiarray average, mixed-effects ANOVA and random-variance t-tests. Altered expression of genes involved in pigment formation, melanosome biogenesis/transport, and redox homeostasis were observed. Twelve genes were commonly mis-regulated in the eyes of both Mitf mutants: 10 of these genes were downregulated in both mutants relative to controls, while 2 of the genes (Nramp1 (Slc11a1) and epoxide hydrolase) were downregulated in Mitfmi/mi mutants, and conversely, upregulated in Mitfvit/vit mutants. Quantitative RT-PCR and immunohistochemistry were used to confirm altered gene/protein expression. RPE expression of the Fe+2 iron transporter Nramp1 (Slc11a1) has not previously been reported. Fe+2 is an important co-factor utilized by the iron-dependent isomerohydrolase RPE65 in the retinoid visual cycle. However, excess accumulation of Fe+2 in the RPE has recently been associated with oxidative damage and age-related macular degeneration. Abnormal pigmentation and increased activity of Slc11a1 in the RPE of Mitfvit mice may contribute to the pathology and progressive retinal degeneration observed in these mutants. [Copyright &y& Elsevier]

Radio base stations are often mounted on towers of power transmission lines. They are usually powered from the low-voltage network through an isolating transformer, to separate the high- and low-voltage networks. The isolating transformer ensures security at customers' premises in the case of nearby power faults and particularly in case of lightning striking, which is a frequent cause of flashover of the high-voltage insulators and a subsequent phase-to-ground fault. To optimize such. protection, a better understanding of the current distribution to the ground in the initial phase of the lightning striking is required. This paper presents a computer simulation method and its results for the lightning current distribution between the sky wires, grounding systems, and power cable network. What is of special concern is the part of the lightning current that might be led into the metal-shielded distribution cable network. A rigorous electromagnetic modeling approach was applied for the analysis of the grounding effects in a network of coated aid uncoated low- and medium-voltage cables. The analysis was then applied to a practical case. [ABSTRACT FROM AUTHOR]

Presents a study that discussed the effects of ground loops on voltage measurement systems. Function of voltage measurement systems in high-power and high-voltage laboratories; Systems with respect to the signal transfer in the frequency domain; General behavior of interference coupling.

Several germination factors were studied in 23 Western European orchids in order to obtain a germination percentage which approximates the maximum percentage of coloured embryos after an adaptation of the tetrazolium test. The duration of seed pretreatment with Ca(OCl)2 + Tween-80 was one of the most important factors controlling the germination of Western European orchids. Best germination occurred in continuous darkness at 23°C on dilute media. The nitrogen source had a species related influence. The best results were obtained with casein hydrolysate, although it could nearly be replaced by one amino acid, L-glutamine. A cytokinin was required by Cypripedium calceolus and Epipactis helleborine but was not necessary for Listera ovata and Dactylorhiza maculata. Experiments with 3 species have shown that the objective, to obtain a germination percentage, which approximated the maximum percentage of coloured embryos, was achieved. This has led to the elaboration of a basic sowing method for European orchids. The application of this method gave good germination responses with 21 of the 23 species tested. [ABSTRACT FROM AUTHOR]

A modified tetrazolium method was formulated for use with seeds of Western European orchids. The sequence of treatments which gave the highest percentage of coloured (i.e. viable) embryos was: (1) pretreatment in a solution of 5% (w/v) Ca(OCl)2+ 1% (v/v) Tween‐80, (2) soaking for 1 day in sterile water, (3) the classical tetrazolium test. The optimal duration of the pretreatment in Ca(OCl)2+ Tween‐80 depends upon the species, and to investigate the effect a scanning electron microscopy study was performed on the testa of 3 species. For a given species, the optimal pretreatment period was not affected by the year of harvest or the source of the seed lots. [ABSTRACT FROM AUTHOR]