Overexpression of Mitochondrial Ligases Reverses Rotenone-Induced Effects in a Drosophila Model of Parkinson’s Disease

Mul1 and Park are two major mitochondrial ligases responsible for mitophagy. Damaged mitochondria that cannot be removed are a source of an increased level of free radicals, which in turn can destructively affect other cell organelles as well as entire cells. One of the toxins that damages mitochondria is rotenone, a neurotoxin that after exposure displays symptoms typical of Parkinson’s disease. In the present study, we showed that overexpressing genes encoding mitochondrial ligases protects neurons during treatment with rotenone. Drosophila strains with overexpressed mul1 or park show a significantly reduced degeneration of dopaminergic neurons, as well as normal motor activity during exposure to rotenone. In the nervous system, rotenone affected synaptic proteins, including Synapsin, Synaptotagmin and Disk Large1, as well as the structure of synaptic vesicles, while high levels of Mul1 or Park suppressed degenerative events at synapses. We concluded that increased levels of mitochondrial ligases are neuroprotective and could be considered in developing new therapies for Parkinson’s disease

Effects of Aging on the Molecular Circadian Oscillations in Drosophila

Circadian clocks maintain temporal homeostasis by generating daily output rhythms in molecular, cellular, and physiological functions. Output rhythms, such as sleep/wake cycles and hormonal fluctuations, tend to deteriorate during aging in humans, rodents, and fruit flies. However, it is not clear whether this decay is caused by defects in the core transcriptional clock, or weakening of the clock-output pathways, or both. The authors monitored age-related changes in behavioral and molecular rhythms in Drosophila melanogaster. Aging was associated with disrupted rest/activity patterns and lengthening of the free-running period of the circadian locomotor activity rhythm. The expression of core clock genes was measured in heads and bodies of young, middle-aged, and old flies. Transcriptional oscillations of four clock genes, period, timeless, Par domain protein 1ϵ, and vrille, were significantly reduced in heads, but not in bodies, of aging flies. It was determined that reduced transcription of these genes was not caused by the deficient expression of their activators, encoded by Clock and cycle genes. Interestingly, transcriptional activation by CLOCK-CYCLE complexes was impaired despite reduced levels of the PERIOD repressor protein in old flies. These data suggest that aging alters the properties of the core transcriptional clock in flies such that both the positive and the negative limbs of the clock are attenuated.Keywords: Drosophila, Aging, Clock gene expression, Circadian clockKeywords: Drosophila, Aging, Clock gene expression, Circadian cloc

The Clock Input to the First Optic Neuropil of Drosophila melanogaster Expressing Neuronal Circadian Plasticity

In the first optic neuropil (lamina) of the fly's visual system, two interneurons, L1 and L2 monopolar cells, and epithelial glial cells show circadian rhythms in morphological plasticity. These rhythms depend on clock gene period (per) and cryptochrome (cry) expression. In the present study, we found that rhythms in the lamina of Drosophila melanogaster may be regulated by circadian clock neurons in the brain since the lamina is invaded by one neurite extending from ventral lateral neurons; the so-called pacemaker neurons. These neurons and the projection to the lamina were visualized by green fluorescent protein (GFP). GFP reporter gene expression was driven by the cry promotor in cry-GAL4/UAS-GFP transgenic lines. We observed that the neuron projecting to the lamina forms arborizations of varicose fibers in the distal lamina. These varicose fibers do not form synaptic contacts with the lamina cells and are immunoreactive to the antisera raised against a specific region of Schistocerca gregaria ion transport peptide (ITP). ITP released in a paracrine way in the lamina cortex, may regulate the swelling and shrinking rhythms of the lamina monopolar cells and the glia by controlling the transport of ions and fluids across cell membranes at particular times of the day

Stress conditions affect the immunomodulatory potential of Candida albicans extracellular vesicles and their impact on cytokine release by THP-1 human macrophages

Human immune cells possess the ability to react complexly and effectively after contact with microbial virulence factors, including those transported in cell-derived structures of nanometer sizes termed extracellular vesicles (EVs). EVs are produced by organisms of all kingdoms, including fungi pathogenic to humans. In this work, the immunomodulatory properties of EVs produced under oxidative stress conditions or at host concentrations of $CO_{2}$ by the fungal pathogen Candida albicans were investigated. The interaction of EVs with human pro-monocytes of the U-937 cell line was established, and the most notable effect was attributed to oxidative stress-related EVs. The immunomodulatory potential of tested EVs against human THP-1 macrophages was verified using cytotoxicity assay, ROS-production assay, and the measurement of cytokine production. All fungal EVs tested did not show a significant cytotoxic effect on THP-1 cells, although a slight pro-oxidative impact was indicated for EVs released by C. albicans cells grown under oxidative stress. Furthermore, for all tested types of EVs, the pro-inflammatory properties related to increased IL-8 and TNF-$\alpha$ production and decreased IL-10 secretion were demonstrated, with the most significant effect observed for EVs released under oxidative stress conditions

Circadian Plasticity of Mammalian Inhibitory Interneurons

Inhibitory interneurons participate in all neuronal circuits in the mammalian brain, including the circadian clock system, and are indispensable for their effective function. Although the clock neurons have different molecular and electrical properties, their main function is the generation of circadian oscillations. Here we review the circadian plasticity of GABAergic interneurons in several areas of the mammalian brain, suprachiasmatic nucleus, neocortex, hippocampus, olfactory bulb, cerebellum, striatum, and in the retina

The primary antibodies used in the study.

<p>The primary antibodies used in the study.</p

<i>Cry</i>-GAL4-driven GFP intensity measured at different time points (ZTs) in the 5^th s-LN_v cell body.

<p>Means ± SEM, a and b mean statistically significant differences between ZT1 and ZT16, respectively, and other time points. Statistics: Non-parametric ANOVA Kruskal-Wallis Range Test [N = 21; H = 11.755; p = 0.083].</p

Localization of CRY-positive cells in the brain of <i>Drosophila melanogaster</i>.

<p>Flies were examined at four ZTs: ZT1, ZT4, ZT13 and ZT16 (ZT0 – the beginning of the day and ZT12 – the beginning of the night) but images shown in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0021258#pone-0021258-g001" target="_blank">Fig. 1</a> were obtained from the brain of individuals collected for experiments at different ZTs. ZT for each image is given in brackets. A1–3: Four large ventral lateral neurons (l-LN_vs), four small LN_vs (s-LN_vs) and an arborization in the accessory medulla (aMe) immunoreactive to PDF (magenta) and labeled with <i>cry</i>-GAL4-driven GFP (green) (ZT1). B1–3: Double-labeling of the LN_vs with PDF antiserum (magenta) and <i>cry</i>-GAL4-driven GFP (green) (ZT16). The 5^th s-LN_v expresses GFP but not PDF (asterisk). C1: <i>cry</i>-GAL4-driven GFP expression in the optic lobe: LN_vs and LN_ds (asterisk). The LN_vs send processes to the medulla (ME) and a single projection to the lamina (LA) which divides and terminates in the lamina cortex (arrows) (ZT4). C2–3: CRY-positive dorsal lateral neurons (LN_ds). Out of 6 LN_ds (C2) (ZT4), 3–4 cells have a higher (by 45–80%) intensity of GFP than other LN_ds in most preparations (C3) (ZT13). D: CRY-positive network of processes in the lobula (LO) (arrow). Processes from DN₃s and LN_vs in the medulla, also shown. E1–2: Dorsal neurons DN₃s and LN_vs. The LN_vs project to the medulla (ME) and to the lamina (arrows) (ZT4). DN₃s form a cluster of cells (asterisk) and send processes to the medulla (E2). F1–2: Network of processes of LN_vs with varicosities in the medulla and in the lamina (arrow); CRY-positive DN₁s (asterisk, F2) (ZT1). Scale bars: 20 µm; in C2: 10 µm.</p