http://hdl.handle.net/1957/9972 2013-05-24T09:46:07Z http://hdl.handle.net/1957/38705 Disturbance Driven Colony Fragmentation as a Driver of a Coral Disease Outbreak Brandt, Marilyn E.; Smith, Tyler B.; Correa, Adrienne M. S.; Vega-Thurber, Rebecca In September of 2010, Brewer's Bay reef, located in St. Thomas (U.S. Virgin Islands), was simultaneously affected by abnormally high temperatures and the passage of a hurricane that resulted in the mass bleaching and fragmentation of its coral community. An outbreak of a rapid tissue loss disease among coral colonies was associated with these two disturbances. Gross lesion signs and lesion progression rates indicated that the disease was most similar to the Caribbean coral disease white plague type 1. Experiments indicated that the disease was transmissible through direct contact between colonies, and five-meter radial transects showed a clustered spatial distribution of disease, with diseased colonies being concentrated within the first meter of other diseased colonies. Disease prevalence and the extent to which colonies were bleached were both significantly higher on unattached colony fragments than on attached colonies, and disease occurred primarily on fragments found in direct contact with sediment. In contrast to other recent studies, disease presence was not related to the extent of bleaching on colonies. The results of this study suggest that colony fragmentation and contact with sediment played primary roles in the initial appearance of disease, but that the disease was capable of spreading among colonies, which suggests secondary transmission is possible through some other, unidentified mechanism. This is the publisher’s final pdf. The published article is copyrighted by Public Library of Science and can be found at: http://www.plos.org/. 2013-02-20T00:00:00Z http://hdl.handle.net/1957/38587 A transgenic zebrafish liver tumor model with inducible Myc expression reveals conserved Myc signatures with mammalian liver tumors Li, Zhen; Zheng, Weiling; Wang, Zhengyuan; Zeng, Zhiqiang; Zhan, Huiqing; Li, Caixia; Zhou, Li; Yan, Chuan; Spitsbergen, Jan M.; Gong, Zhiyuan Myc is a pleiotropic transcription factor that is involved in many cellular activities relevant to carcinogenesis, including hepatocarcinogenesis. The zebrafish has been increasingly used to model human diseases and it is particularly valuable in helping to identify common and conserved molecular mechanisms in vertebrates. Here we generated a liver tumor model in transgenic zebrafish by liver-specific expression of mouse Myc using a Tet-On system. Dosage-dependent induction of Myc expression specifically in the liver was observed in our Myc transgenic zebrafish, TO(Myc), and the elevated Myc expression caused liver hyperplasia, which progressed to hepatocellular adenoma and carcinoma with prolonged induction. Next generation sequencing-based transcriptomic analyses indicated that ribosome proteins were overwhelmingly upregulated in the Myc-induced liver tumors. Cross-species analyses showed that the zebrafish Myc model correlated well with Myc transgenic mouse models for liver cancers. The Myc-induced zebrafish liver tumors also possessed molecular signatures highly similar to human those of hepatocellular carcinoma. Finally, we found that a small Myc target gene set of 16 genes could be used to identify liver tumors due to Myc upregulation. Thus, our zebrafish model demonstrated the conserved role of Myc in promoting hepatocarcinogenesis in all vertebrate species. This is the publisher’s final pdf. The published article is copyrighted by The Company of Biologists Ltd. and can be found at: http://www.biologists.com/journals.html 2013-03-01T00:00:00Z http://hdl.handle.net/1957/38023 Microsporidiosis in zebrafish research facilities Sanders, Justin L.; Watral, Virginia; Kent, Michael L. Pseudoloma neurophilia (Microsporidia) is the most common pathogen detected in zebrafish (Danio rerio) from research facilities. The parasite infects the central nervous system and muscle, and may be associated with emaciation and skeletal deformities. However, many fish exhibit subclinical infections. Another microsporidium, Pleistophora hyphessobryconis, has recently been detected in a few zebrafish facilities. Here we review the methods for diagnosis and detection, modes of transmission, and approaches used to control microsporidia in zebrafish, focusing on P. neurophilia. The parasite can be readily transmitted by feeding spores or infected tissues, and we showed that cohabitation with infected fish is also an effective means of transmission. Spores are released from live fish at various points, including the urine, feces, and sex products during spawning. Indeed, P. neurophilia infects both the eggs and ovarian tissues, where we found concentrations ranging from (12,000 – 88,000 spores/ovary). Hence, various lines of evidence support the conclusion that maternal transmission is a route of infection: spores are numerous in ovaries and developing follicles in infected females, spores are present in spawned eggs and water from spawning tanks based on PCR tests, and larvae are very susceptible to the infection. Furthermore, egg surface disinfectants presently used in zebrafish laboratories are ineffective against microsporidian spores. At this time, the most effective method for prevention of these parasites is avoidance. This is the author's peer-reviewed final manuscript, as accepted by the publisher. The article is copyrighted by the Institute for Laboratory Animal Research and published by Oxford University Press. It can be found at: http://ilarjournal.oxfordjournals.org/. 2012-01-01T00:00:00Z http://hdl.handle.net/1957/37954 Detection and transmission of Mycobacterium marinum and Mycobacterium chelonae in zebrafish (Danio rerio) Peterson, Tracy Shawn Mycobacteriosis is a common disease of laboratory zebrafish (Danio rerio). Different infection patterns occur in zebrafish depending on mycobacterial species. Mycobacterium marinum and M. haemophilum produce virulent infections associated with high mortality, whereas M. chelonae is more wide spread and not associated with high mortality. Identification of mycobacterial infections to the species level provides important information for making management decisions. Observation of acid-fast bacilli in histological sections or tissue imprints is the most common diagnostic method for mycobacteriosis in fish, but only allows for diagnosis to the genus level. Mycobacterial culture, followed by molecular or biochemical identification is the traditional approach for species identification, but recently it has been shown that DNA of diagnostic value can be retrieved from paraffin blocks. Type of fixative, time in fixative before processing, species of mycobacteria, and severity of infection were investigated as parameters to determine if the hsp gene PCR assay (primer set HS5F/hsp667R) could detect and amplify mycobacterial DNA from paraffin-embedded zebrafish. Whole zebrafish were experimentally infected with either M. chelonae or M. marinum, and then preserved in 10% neutral buffered formalin or Dietrich's fixative for 3, 7, 21 and 45 days. Subsequently, fish were evaluated by H&E and Fite's acid-fast stains to detect mycobacteria within granulomatous lesions. The PCR assay was quite effective, and obtained PCR product from 75% and 88% of the M. chelonae and M. marinum infected fish, respectively. Fixative type, time in fixative, and mycobacterial species showed no statistical relationship with the efficacy of the PCR test. Regarding natural transmission, zebrafish are capable of contracting mycobacterial infections by feeding on infected fish tissue, but other natural routes have not been clearly elucidated. Free living amoebae have been shown to be vectors for mycobacteria and their virulence is enhanced when residing in these protozoans. Paramecium caudatum are commonly used as a first food for zebrafish, and I investigated this ciliate's potential to serve as a vector of Mycobacterium marinum and M. chelonae. The ability of live P. caudatum to transmit these mycobacteria to larval, juvenile and adult zebrafish was evaluated. Infections were defined by histologic observation of granulomas containing acid-fast bacteria in extraintestinal locations. In both experiments, fish fed paramecia containing mycobacteria became infected at a higher incidence than controls. Larvae (exposed at 4 days post hatch) fed paramecia with M. marinum exhibited an incidence of 30% (24/80) and juveniles (exposed at 21 days post hatch) showed 31% incidence (14/45). Adult fish fed gelatin diets containing bacteria within paramecia or mycobacteria alone for 2 wk resulted in infections when examined 8 wk after exposure: M. marinum OSU 214; in paramecia 47% (21/45; 3.5 x 10⁵ dose/fish/day), M. marinum CH in paramecia 47% (9/19; 3.6 x 10⁵ dose/fish/day), M. chelonae in paramecia 38% (5/13; 3.5 x 10⁵ dose/fish/day). I investigated the ability of mycobacteria to persist within paramecia, as this has previously been demonstrated in amoebae. Gram negative bacteria ingested by paramecia were processed within an hour. In contrast, I determined using GFP-labeled Mycobacterium marinum that mycobacteria can persist within paramecia digestive vacuoles. The concentration of M. marinum at 1 hour was similar to that at the time of ingestion. Twenty-four hours post-ingestion and later there was significant decline in M. marinum concentrations compared to time of ingestion, but M. marinum continued to persist inside digestive vacuoles for up to one week. My results demonstrate for the first time that Paramecium caudatum can act as a vector for mycobacteria. This provides a useful animal model for evaluation of natural mycobacterial infections and demonstrates the possibility of mycobacterial transmission in zebrafish facilities via contaminated paramecia cultures. Graduation date: 2013; Access restricted to the OSU Community at author's request from April 2, 2013 - April 2, 2015 2013-02-27T00:00:00Z