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Zebrafish Danio Rerio (zebrafish + danio_rerio)
Selected AbstractsDissociation of food and opiate preference by a genetic mutation in zebrafishGENES, BRAIN AND BEHAVIOR, Issue 7 2006B. Lau Both natural rewards and addictive substances have the ability to reinforce behaviors. It has been unclear whether identical neural pathways mediate the actions of both. In addition, little is known about these behaviors and the underlying neural mechanisms in a genetically tractable vertebrate, the zebrafish Danio rerio. Using a conditioned place preference paradigm, we demonstrate that wildtype zebrafish exhibit a robust preference for food as well as the opiate drug morphine that can be blocked by the opioid receptor antagonist naloxone. Moreover, we show that the too few mutant, which disrupts a conserved zinc finger-containing gene and exhibits a reduction of selective groups of dopaminergic and serotonergic neurons in the basal diencephalon, displays normal food preference but shows no preference for morphine. Pretreatment with dopamine receptor antagonists abolishes morphine preference in the wildtype. These studies demonstrate that zebrafish display measurable preference behavior for reward and show that the preference for natural reward and addictive drug is dissociable by a single-gene mutation that alters subregions of brain monoamine neurotransmitter systems. Future genetic analysis in zebrafish shall uncover further molecular and cellular mechanisms underlying the formation and function of neural circuitry that regulate opiate and food preference behavior. [source] Myogenesis and molecules, insights from zebrafish Danio rerioJOURNAL OF FISH BIOLOGY, Issue 8 2009S.-W. Chong Myogenesis is a fundamental process governing the formation of muscle in multicellular organisms. Recent studies in zebrafish Danio rerio have described the molecular events occurring during embryonic morphogenesis and have thus greatly clarified this process, helping to distinguish between the events that give rise to fast v. slow muscle. Coupled with the well-known Hedgehog signalling cascade and a wide variety of cellular processes during early development, the continual research on D. rerio slow muscle precursors has provided novel insights into their cellular behaviours in this organism. Similarly, analyses on fast muscle precursors have provided knowledge of the behaviour of a sub-set of epitheloid cells residing in the anterior domain of somites. Additionally, the findings by various groups on the roles of several molecules in somitic myogenesis have been clarified in the past year. In this study, the authors briefly review the current trends in the field of research of D. rerio trunk myogenesis. [source] Myogenic regulatory factors Myf5 and Mrf4 of fish: current status and perspectiveJOURNAL OF FISH BIOLOGY, Issue 8 2008Y. H. Chen Recent advances in the understanding of fish myogenic regulatory factors (MRF) are described in this review. Specifically, two of the MRFs are discussed, Myf5 and Mrf4, which are encoded by a highly linked gene loci (mrf4 and myf5) that is conserved among vertebrates. Experiments related to the expression patterns, biological functions and regulatory network of mrf4 and myf5 are highlighted, and examples of gene organizations and protein features among known vertebrate species are outlined. Furthermore, the complicated regulatory mechanisms of myf5 are discussed using zebrafish Danio rerio as a model. Multiple regulatory elements that control the specific expression of zebrafish myf5 are elucidated, including enhancer, silencer, proximal and distal elements, the interaction between proximal regulatory cassette ,82/,62 and its cognate binding transcription factors, and a plausible post-transcriptional regulatory mechanism. This review article highlights a fundamental molecular mechanism of mrf4 and myf5 during fish muscle development. [source] The evolution of teleost pigmentation and the fish-specific genome duplicationJOURNAL OF FISH BIOLOGY, Issue 8 2008I. Braasch Teleost fishes have evolved a unique complexity and diversity of pigmentation and colour patterning that is unmatched among vertebrates. Teleost colouration is mediated by five different major types of neural-crest derived pigment cells, while tetrapods have a smaller repertoire of such chromatophores. The genetic basis of teleost colouration has been mainly uncovered by the cloning of pigmentation genes in mutants of zebrafish Danio rerio and medaka Oryzias latipes. Many of these teleost pigmentation genes were already known as key players in mammalian pigmentation, suggesting partial conservation of the corresponding developmental programme among vertebrates. Strikingly, teleost fishes have additional copies of many pigmentation genes compared with tetrapods, mainly as a result of a whole-genome duplication that occurred 320,350 million years ago at the base of the teleost lineage, the so-called fish-specific genome duplication. Furthermore, teleosts have retained several duplicated pigmentation genes from earlier rounds of genome duplication in the vertebrate lineage, which were lost in other vertebrate groups. It was hypothesized that divergent evolution of such duplicated genes may have played an important role in pigmentation diversity and complexity in teleost fishes, which therefore not only provide important insights into the evolution of the vertebrate pigmentary system but also allow us to study the significance of genome duplications for vertebrate biodiversity. [source] Variations of sperm release in three batches of zebrafishJOURNAL OF FISH BIOLOGY, Issue 2 2004J. R. Kemadjou Njiwa By collecting and counting the number of sperm released during separate matings in three batches of zebrafish Danio rerio, aged 3,4, 4,5 and 5,6 months, males were observed to release sperm before the female started laying their eggs. After the female left the nest, the number and motility of sperm and life span of sperm of younger fish were higher than those of older fish in water samples collected under the nest and at the surface of the tank. Sperm were released in the form of sperm trails laid on the nest surface, subsequently active spermatozoa left the trails and moved in the water for several minutes. Sperm trails consisted of bands of viscous material in which the sperm were embedded. In most cases eggs were not laid directly over the sperm trail, suggesting that sperm may contact the eggs after the latter are released into the water. In all the three tested groups there was no significant difference (P > 0·05) between the number of sperm collected on some portions of the acetate sheets which lined the nest ceiling. This result demonstrated that the greater activity of younger fish accelerated the sperm dispersal in water. Male sperm duct glands, seminal vesicles, known to secrete mucosubstances are probably involved in the production of sperm trails. The possible influence of insemination on the mating style of zebrafish is discussed. [source] Effects of sediment eluates and extracts from differently polluted small rivers on zebrafish embryos and larvaeJOURNAL OF FISH BIOLOGY, Issue 1 2002M. Strmac The effects on newly fertilized eggs, embryos and larvae of zebrafish Danio rerio following exposure to sediment samples from the more heavily contaminated River Körsch, southern Germany, occurred earlier and were more prominent than in samples from the less contaminated Krähenbach. Dose- and time-related effects following exposure to Körsch sediment eluates and extracts included: (1) hatching failure and subsequent death of larvae exposed to undiluted aqueous sediment eluates and reduced hatching rates at sediment extract concentrations 0·0125%; (2) increased mortality after exposure to 25 and 50% dilutions of aqueous sediment eluates, and dilutions of 0·00625% sediment extracts; (3) reduction of heart beat frequency for 50% dilutions of sediment eluates and concentrations of 0·025% extracts; (4) increased frequency of heart and yolk sac oedema after exposure to 0·0125% sediment extracts. Since adverse effects of sediment extracts observed in zebrafish laboratory tests correlated with reproductive failure in natural populations of brown trout Salmo trutta f. fario in the severely polluted River Körsch, early life stages tests with zebrafish appear to be a suitable tool to assess the contamination rate of natural sediments. [source] Improved tomographic reconstructions using adaptive time-dependent intensity normalizationJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2010Valeriy Titarenko The first processing step in synchrotron-based micro-tomography is the normalization of the projection images against the background, also referred to as a white field. Owing to time-dependent variations in illumination and defects in detection sensitivity, the white field is different from the projection background. In this case standard normalization methods introduce ring and wave artefacts into the resulting three-dimensional reconstruction. In this paper the authors propose a new adaptive technique accounting for these variations and allowing one to obtain cleaner normalized data and to suppress ring and wave artefacts. The background is modelled by the product of two time-dependent terms representing the illumination and detection stages. These terms are written as unknown functions, one scaled and shifted along a fixed direction (describing the illumination term) and one translated by an unknown two-dimensional vector (describing the detection term). The proposed method is applied to two sets (a stem Salix variegata and a zebrafish Danio rerio) acquired at the parallel beam of the micro-tomography station 2-BM at the Advanced Photon Source showing significant reductions in both ring and wave artefacts. In principle the method could be used to correct for time-dependent phenomena that affect other tomographic imaging geometries such as cone beam laboratory X-ray computed tomography. [source] Crystallization and preliminary X-ray analysis of ZHE1, a hatching enzyme from the zebrafish Danio rerioACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 10 2009Akitoshi Okada The hatching enzyme of the zebrafish, ZHE1 (29.3,kDa), is a zinc metalloprotease that catalyzes digestion of the egg envelope (chorion). ZHE1 was heterologously expressed in Escherichia coli, purified and crystallized by the hanging-drop vapour-diffusion method using PEG 3350 as the precipitant. Two diffraction data sets with resolution ranges 50.0,1.80 and 50.0,1.14,Å were independently collected from two crystals and were merged to give a highly complete data set over the full resolution range 50.0,1.14,Å. The space group was assigned as primitive orthorhombic P212121, with unit-cell parameters a = 32.9, b = 62.5, c = 87.4,Å. The crystal contained one ZHE1 molecule in the asymmetric unit. [source] | ||||||||||