Browsing by Subject "zebrafish"

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Biophysics of Zebrafish (Danio rerio) Sperm
    (Elsevier, 2009-02) Hagedorn, M.; Ricker, J.; McCarthy, M.; Meyers, S.A.; Tiersch, T.R.; Varga, Z. M.; Kleinhans, F.W.; Physics, School of Science
    In the past two decades, laboratories around the world have produced thousands of mutant, transgenic, and wild-type zebrafish lines for biomedical research. Although slow-freezing cryopreservation of zebrafish sperm has been available for 30 years, current protocols lack standardization and yield inconsistent post-thaw fertilization rates. Cell cryopreservation cannot be improved without basic physiological knowledge, which was lacking for zebrafish sperm. The first goal was to define basic cryobiological values for wild-type zebrafish sperm and to evaluate how modern physiological methods could aid in developing improved cryopreservation protocols. Coulter counting methods measured an osmotically inactive water fraction (Vb) of 0.37 ± 0.02 (SEM), an isosmotic cell volume (Vo) of 12.1 ± 0.2 μm3 (SEM), a water permeability (Lp) in 10% dimethyl sulfoxide of 0.021 ± 0.001(SEM) um/min/atm, and a cryoprotectant permeability (Ps) of 0.10 +/− 0.01 (SEM) × 10−3 cm/min. Fourier transform infrared spectroscopy indicated that sperm membranes frozen without cryoprotectant showed damage and lipid reorganization, while those exposed to 10% glycerol demonstrated decreased lipid phase transition temperatures, which would stabilize the cells during cooling. The second goal was to determine the practicality and viability of shipping cooled zebrafish sperm overnight through the mail. Flow cytometry demonstrated that chilled fresh sperm can be maintained at 92% viability for 24 h at 0°C, suggesting that it can be shipped and exchanged between laboratories. Additional methods will be necessary to analyze and improve cryopreservation techniques and post-thaw fertility of zebrafish sperm. The present study is a first step to explore such techniques.
  • Thumbnail Image
    Item
    Effect of Curcuminoids in Turmeric on Developing Zebrafish Treated with Ethanol
    (Office of the Vice Chancellor for Research, 2016-04-08) Connors, Craig; Mohammed, Arooj; Muralidharan, Pooja; Sarmah, Swapnalee; Marrs, James; Marrs, Kathleen A.; Chism, Grady
    This experiment was designed with the intention of determining whether turmeric could act as a rescue agent to prevent or mitigate the extent of Fetal Alcohol Spectrum Disorder (FASD) caused by early ethanol exposure using zebrafish as a model system. A range of turmeric concentrations were made from a stock solution of turmeric dissolved in ethanol (1mg turmeric in 5mL ethanol). The active agents in turmeric are the curcuminoids: Curcumin, Desmethoxycurcumin, and Bisdemethoxycurcumin. The curcuminoids concentration was estimated using liquid chromatography. These agents were present in the turmeric stock solution at the following concentrations: Bisdemethoxycurcumin: 36.6 +/- 0.1 ug/mL, Desmethoxycurcumin: 43.4 +/- 0.1 ug/mL, and Curcumin: 124.1 +/- 0.2 ug/mL. Untreated zebrafish embryos were placed in embryo medium, ethanol treated embryos in 100mM ethanol containing embryo medium, and turmeric co-supplemented medium with differing concentrations of turmeric. Since the turmeric stock solution was dissolved in ethanol, the concentration of ethanol was kept at a constant 100mM ethanol and the amount of turmeric solution added. The concentrations of the test plates were then based on this solution and made to be 100 mM ethanol and 1.16 uM curcuminoids, 100 mM ethanol and 1.74 uM curcuminoids, and 100 mM ethanol and 2.32 uM curcuminoids. The developing embryos were treated with the turmeric solution and/or ethanol during 2-24 hours post fertilization (hpf). These embryos were imaged at 72 hpf and their body length and eye diameter were measured. The embryos supplemented with curcuminoids showed a significant rescue effect on the body length and eye diameter compared to ethanol treated embryos. This indicates that the curcuminoids acted as a rescue agent to reduce the effects that are typical of FASD in developing zebrafish.
  • Thumbnail Image
    Item
    Marijuana and Opioid Use during Pregnancy: Using Zebrafish to Gain Understanding of Congenital Anomalies Caused by Drug Exposure during Development
    (MDPI, 2020-08-08) Sarmah, Swapnalee; Sales Cadena, Marilia Ribeiro; Cadena, Pabyton Gonçalves; Marrs, James A.; Biology, School of Science
    Marijuana and opioid addictions have increased alarmingly in recent decades, especially in the United States, posing threats to society. When the drug user is a pregnant mother, there is a serious risk to the developing baby. Congenital anomalies are associated with prenatal exposure to marijuana and opioids. Here, we summarize the current data on the prevalence of marijuana and opioid use among the people of the United States, particularly pregnant mothers. We also summarize the current zebrafish studies used to model and understand the effects of these drug exposures during development and to understand the behavioral changes after exposure. Zebrafish experiments recapitulate the drug effects seen in human addicts and the birth defects seen in human babies prenatally exposed to marijuana and opioids. Zebrafish show great potential as an easy and inexpensive model for screening compounds for their ability to mitigate the drug effects, which could lead to new therapeutics.
  • Thumbnail Image
    Item
    Phenotypical microRNA screen reveals a noncanonical role of CDK2 in regulating neutrophil migration
    (National Academy of Sciences, 2019-09-10) Hsu, Alan Y.; Wang, Decheng; Liu, Sheng; Lu, Justice; Syahirah, Ramizah; Bennin, David A.; Huttenlocher, Anna; Umulis, David M.; Wan, Jun; Deng, Qing; Medical and Molecular Genetics, School of Medicine
    Neutrophil migration is essential for inflammatory responses to kill pathogens; however, excessive neutrophilic inflammation also leads to tissue injury and adverse effects. To discover novel therapeutic targets that modulate neutrophil migration, we performed a neutrophil-specific microRNA (miRNA) overexpression screen in zebrafish and identified 8 miRNAs as potent suppressors of neutrophil migration. Among those, miR-199 decreases neutrophil chemotaxis in zebrafish and human neutrophil-like cells. Intriguingly, in terminally differentiated neutrophils, miR-199 alters the cell cycle-related pathways and directly suppresses cyclin-dependent kinase 2 (Cdk2), whose known activity is restricted to cell cycle progression and cell differentiation. Inhibiting Cdk2, but not DNA replication, disrupts cell polarity and chemotaxis of zebrafish neutrophils without inducing cell death. Human neutrophil-like cells deficient in CDK2 fail to polarize and display altered signaling downstream of the formyl peptide receptor. Chemotaxis of primary human neutrophils is also reduced upon CDK2 inhibition. Furthermore, miR-199 overexpression or CDK2 inhibition significantly improves the outcome of lethal systemic inflammation challenges in zebrafish. Our results therefore reveal previously unknown functions of miR-199 and CDK2 in regulating neutrophil migration and provide directions in alleviating systemic inflammation.
  • Thumbnail Image
    Item
    Prickle1 is required for EMT and migration of zebrafish cranial neural crest
    (Elsevier, 2019) Ahsan, Kamil; Singh, Noor; Rocha, Manuel; Huang, Christina; Prince, Victoria E.; Medicine, School of Medicine
    The neural crest—a key innovation of the vertebrates—gives rise to diverse cell types including melanocytes, neurons and glia of the peripheral nervous system, and chondrocytes of the jaw and skull. Proper development of the cephalic region is dependent on the tightly-regulated specification and migration of cranial neural crest cells (NCCs). The core PCP proteins Frizzled and Disheveled have previously been implicated in NCC migration. Here we investigate the functions of the core PCP proteins Prickle1a and Prickle1b in zebrafish cranial NCC development. Using analysis of pk1a and pk1b mutant embryos, we uncover similar roles for both genes in facilitating cranial NCC migration. Disruption of either gene causes pre-migratory NCCs to cluster together at the dorsal aspect of the neural tube, where they adopt aberrant polarity and movement. Critically, in investigating Pk1-deficient cells that fail to migrate ventrolaterally, we have also uncovered roles for pk1a and pk1b in the epithelial-to-mesenchymal transition (EMT) of pre-migratory NCCs that precedes their collective migration to the periphery. Normally, during EMT, pre-migratory NCCs transition from a neuroepithelial to a bleb-based and subsequently, mesenchymal morphology capable of directed migration. When either Pk1a or Pk1b is disrupted, NCCs continue to perform blebbing behaviors characteristic of pre-migratory cells over extended time periods, indicating a block in a key transition during EMT. Although some Pk1-deficient NCCs transition successfully to mesenchymal, migratory morphologies, they fail to separate from neighboring NCCs. Additionally, Pk1b-deficient NCCs show elevated levels of E-Cadherin and reduced levels of N-Cadherin, suggesting that Prickle1 molecules regulate Cadherin levels to ensure the completion of EMT and the commencement of cranial NCC migration. We conclude that Pk1 plays crucial roles in cranial NCCs both during EMT and migration. These roles are dependent on the regulation of E-Cad and N-Cad.
  • Thumbnail Image
    Item
    Targeting polyamine biosynthesis to stimulate beta cell regeneration in zebrafish
    (Taylor & Francis, 2020-07-25) Robertson, Morgan A.; Padgett, Leah R.; Fine, Jonathan A.; Chopra, Gaurav; Mastracci, Teresa L.; Biology, School of Science
    Type 1 diabetes (T1D) is a disease characterized by destruction of the insulin-producing beta cells. Currently, there remains a critical gap in our understanding of how to reverse or prevent beta cell loss in individuals with T1D. Previous studies in mice discovered that pharmacologically inhibiting polyamine biosynthesis using difluoromethylornithine (DFMO) resulted in preserved beta cell function and mass. Similarly, treatment of non-obese diabetic mice with the tyrosine kinase inhibitor Imatinib mesylate reversed diabetes. The promising findings from these animal studies resulted in the initiation of two separate clinical trials that would repurpose either DFMO (NCT02384889) or Imatinib (NCT01781975) and determine effects on diabetes outcomes; however, whether these drugs directly stimulated beta cell growth remained unknown. To address this, we used the zebrafish model system to determine pharmacological impact on beta cell regeneration. After induction of beta cell death, zebrafish embryos were treated with either DFMO or Imatinib. Neither drug altered whole-body growth or exocrine pancreas length. Embryos treated with Imatinib showed no effect on beta cell regeneration; however, excitingly, DFMO enhanced beta cell regeneration. These data suggest that pharmacological inhibition of polyamine biosynthesis may be a promising therapeutic option to stimulate beta cell regeneration in the setting of diabetes.