Mechanism of the fluorescent light induced suppression of Curly phenotype in Drosophila melanogaster

Systematic review of biological effects of exposure to static electric fields. Part II: Invertebrates and plants

BACKGROUND

The construction of high-voltage direct current (HVDC) lines for the long-distance transport of energy is becoming increasingly popular. This has raised public concern about potential environmental impacts of the static electric fields (EF) produced under and near HVDC power lines. As the second part of a comprehensive literature analysis, the aim of this systematic review was to assess the effects of static EF exposure on biological functions in invertebrates and plants and to provide the basis for an environmental impact assessment of such exposures.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was used to guide the methodological conduct and reporting.

RESULTS

Thirty-three studies - 14 invertebrate and 19 plant studies - met the eligibility criteria and were included in this review. The reported behavioral responses of insects and planarians upon exposure strongly suggest that invertebrates are able to perceive the presence of a static EF. Many other studies reported effects on physiological functions that were expressed as, for example, altered metabolic activity or delayed reproductive and developmental stages in invertebrates. In plants, leaf damage, alterations in germination rates, growth and yield, or variations in the concentration of essential elements, for example, have been reported. However, these physiological responses and changes in plant morphology appear to be secondary to surface stimulation by the static EF or caused by concomitant parameters of the electrostatic environment. Furthermore, all of the included studies suffered from methodological flaws, which lowered credibility in the results.

CONCLUSION

At field levels encountered from natural sources or HVDC lines (< 35kV/m), the available data provide reliable evidence that static EF can trigger behavioral responses in invertebrates, but they do not provide evidence for adverse effects of static EF on other biological functions in invertebrates and plants. At far higher field levels (> 35kV/m), adverse effects on physiology and morphology, presumably caused by corona-action, appear to be more likely. Higher quality studies are needed to unravel the role of air ions, ozone, nitric oxide and corona current on alterations in physiological functions and morphology.

Curly Encodes Dual Oxidase, Which Acts with Heme Peroxidase Curly Su to Shape the Adult Drosophila Wing

Curly, described almost a century ago, is one of the most frequently used markers in Drosophila genetics. Despite this the molecular identity of Curly has remained obscure. Here we show that Curly mutations arise in the gene dual oxidase (duox), which encodes a reactive oxygen species (ROS) generating NADPH oxidase. Using Curly mutations and RNA interference (RNAi), we demonstrate that Duox autonomously stabilizes the wing on the last day of pupal development. Through genetic suppression studies, we identify a novel heme peroxidase, Curly Su (Cysu) that acts with Duox to form the wing. Ultrastructural analysis suggests that Duox and Cysu are required in the wing to bond and adhere the dorsal and ventral cuticle surfaces during its maturation. In Drosophila, Duox is best known for its role in the killing of pathogens by generating bactericidal ROS. Our work adds to a growing number of studies suggesting that Duox’s primary function is more structural, helping to form extracellular and cuticle structures in conjunction with peroxidases.

Fruit fly geneticists rely on a handful of dominant mutations that modify adult morphology in a way that is easy to spot, like changing the shape of the fly’s wings, eyes or bristles. One of the first such mutants identified in the early days of fly genetics and to this day likely the most widely used mutation, is Curly, which causes an upward curvature in the adult wings. Despite its importance as a marker, the genetic cause of Curly has remained unknown. Here, we reveal that Curly mutations occur in the gene duox, which encodes a ROS-generating enzyme. ROS once thought to be merely harmful by-products of metabolism, can also have beneficial purposes. Here we provide evidence that Duox generates ROS to help form and stabilize the wings of fruit flies. Furthermore, we identify a second enzyme, Cysu, which uses the ROS generated by Duox to crosslink proteins in the wing, thereby stabilizing and shaping its structure. Duox occurs in numerous organisms, including humans and fulfills a number of other functions, in particular in immunity and pathogen defense. With this new knowledge, Curly mutations will provide an excellent tool to study and understand the roles Duox plays in a variety of biological contexts.

Controllable spectrum artificial sunlight source system using LEDs with 32 different peak wavelengths of 385-910 nm

This study developed a lighting system that produces an approximate spectral irradiance (SI) of ground level sunlight in the wavelength range of 385-910 nm (GLS₃₈₅₋₉₁₀) using 547 light-emitting diodes (LEDs) with 32 different peak wavelengths. The produced SI can be modified over an arbitrary wavelength band. The SI at the light outlet reached up to 1/2 of the GLS₃₈₅₋₉₁₀ of a sunny April day, although the produced SI deviated from the GLS₃₈₅₋₉₁₀ at some wavelengths. For subsequent experiments, the reference SI was defined as 1/4 GLS₃₈₅₋₉₁₀ of a sunny April day. The SI produced from the lighting system was adjusted to approximate the reference SI. The ratios of the produced SI and the reference SI were within 0.72-1.28. As an application of the lighting system for biological studies, the transmitted SI of a green leaf of perilla (Perilla frutescens L.) was investigated. The curve shape of the transmitted SI, which had characteristically low transmission percentages of blue and red light, reflected the characteristics of the absorption spectra of chlorophylls. The lighting system is therefore potentially beneficial for use in diagnosing physiological conditions of plant leaves, although its application is not limited to plant physiological studies.

Curled encodes the Drosophila homolog of the vertebrate circadian deadenylase Nocturnin

Drosophila melanogaster curled, one of the first fly mutants described by T. H. Morgan >90 years ago, is the founding member of a series of curled wing phenotype mutants widely used as markers in fruit fly genetics. The expressivity of the wing phenotype is environmentally modulated, suggesting that the mutation affects the metabolic status of cells rather than a developmental control gene. However, the molecular identity of any of the curled wing marker mutant genes is still unknown. In a screen for starvation-responsive genes, we previously identified the single fly homolog of the vertebrate nocturnin genes, which encode cytoplasmic deadenylases that act in the post-transcriptional control of genes by poly(A) tail removal of target mRNAs prior to their degradation. Here we show that curled encodes Drosophila Nocturnin and that the gene is required at pupal stage for proper wing morphogenesis after eclosion of the fly. Despite the complex ontogenetic expression pattern of the gene, curled is not expressed in the developing wing, and wing-specific curled knockdown mediated by RNAi does not result in the curled wing phenotype, indicating a tissue-nonautonomous, systemic mode of curled gene function. Our study not only presents an entry point into the functional analysis of invertebrate nocturnins but also paves the way for the identification of the still elusive Nocturnin target mRNAs by genetic suppressor screens on the curled wing phenotype.