However , in all six parameters, no significant differences were found between the WT and control groups

However , in all six parameters, no significant differences were found between the WT and control groups. led to demyelination, accompanied by behavioral changes, including decreased total movement distance, velocity, total movement time and fast movement time. After withdrawal of Mtz for a seven day recovery period, the expression of EGFP and MBP protein was observed again which indicates Doxycycline monohydrate remyelination. Additionally , locomotor capacity was restored. Collectively, Tg(mbp: nfsB-egfp), a heritable and stable transgenic collection, provides a novel, powerful tool to study the mechanisms of demyelination and remyelination. Keywords: Demyelination, Myelin basic protein, Oligodendrocyte, Remyelination, Transgenic zebrafish == INTRO == The myelin sheath is the membrane structure protecting, supporting and nourishing axons. As the multi-layered insulating structure around the axon, the myelin sheath mediates the rapid conduction of nerve impulses (Almeida et al., 2011; Czopka et al., 2013). Demyelinating diseases are a variety of diseases in which the neuronal myelin sheath is damaged due to genetic, environmental factors or unknown factors. The mechanisms of demyelination remain unclear. This damage impairs the conduction of signals in the affected nerves. Then, the reduction in conduction causes deficiencies in sensation, movement, cognition, or other functions, depending on which nerves are involved (Compston and Coles, 2002; Scherer and Wrabetz, Rabbit polyclonal to Smad7 2008). The zebrafish is an ideal model to study injury and regeneration of the myelin sheath. The contributive features of zebrafish include external fertilization, large numbers of spawn, transparent eggs and embryos, rapid development, and the opportunity for genetic analysis. Moreover, the myelin structure, myelin synthesis and gene Doxycycline monohydrate expression are highly conserved between zebrafish and mammals (Chung et al., 2013; Gerlai, 2011; Jung et al., 2010). The Tol2 transposon is a unique autonomous transposable element in vertebrates that carries 11 kb of exogenous insert to complete the transposition without reducing the transpositional activity (Kawakami, 2005; Kawakami and Shima, 1999; Parinov et al., 2004). The nitroreductase (NTR)/metronidazole (Mtz) system is a hybrid chemical-genetic cell mutilation technology widely used in zebrafish studies. This system relies on the NTR-mediated conversion of a non-toxic pro-drug (a nitroimidazole substrate, such as Mtz) into a cytotoxic agent, which induces the death of NTR positive cells, thus allowing controllable and reversible ablation of target cells (Curado et al., 2008). Moreover, Mtz can be efficiently washed out, the affected tissue can quickly recover. Therefore , the NTR/Mtz system is effective intended for cell mutilation in a temporal and spatial manner and is applicable to any target cell population without a bystander effect. This technique offers a novel way to analyze tissue interactions, cell interactions, and mechanisms underlying degeneration and regeneration. In this study, we generated a transgenic zebrafish collection that expressed a fusion protein composed of enhanced green fluorescent protein (EGFP) and NTR from themyelin basic protein(mbp) promoter. Tg(mbp: nfsB-egfp) expressed NTR-EGFP in the oligodendrocyte lineage cells. Treatment of zebrafish larvae Tg(mbp: nfsB-egfp) with Mtz resulted in the selective ablation of cells expressing the NTR-EGFP fusion protein. The cell death of oligodendrocytes led to demyelination, accompanied by behavioral changes, including decreased total movement distance, average speed, total movement time and fast movement time. Strikingly, after withdrawal of Mtz, the expression of EGFP was observed again, demonstrating that remyelination occurred. Additionally , exercise capacity was partially restored. To our knowledge, this study is the first insight into the behavioral tests related to demyelination and Doxycycline monohydrate remyelination in a zebrafish model. == RESULTS == == mbppromoter-driven oligodendrocytes express EGFP == Myelin basic protein, encoded by thembpgene, is the main protein component of the myelin sheath. Thembpgene is specifically expressed in differentiated oligodendrocyte lineage cells, including oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system. Therefore , mbpwas generally used to monitor and notice myelin as a marker gene (Chung et al., 2013; Jung et al., 2010; Kazakova et al., 2006; Li et al., 2007; Lyons et al., 2009). In this study, we generated transgenic zebrafish Tg(mbp: nfsB-egfp)nk002which expressed EGFP at 4 dpf. The EGFP signals first appeared in the ventral hindbrain, nervus lateralis and spinal cord. The distribution of EGFP signals continued linearly along the spinal cord and nervus lateralis in the trunk (Fig. 1A, B, white arrowheads). EGFP expression in the spinal cord was enhanced at 5 dpf (Fig. 1D, E, white arrowheads) and 6 dpf (Fig. 1G, H, white arrowheads). In situhybridization revealed that thembp-expressing cells of Tg(mbp: nfsB-egfp)nk002at 46 dpf were similarly localized compared to the EGFP.