The tardigrade Hypsibius dujardini as a new model for studies on the evolution of development Public Deposited

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  • March 22, 2019
Creator
  • Gabriel, Willow Noelle
    • Affiliation: College of Arts and Sciences, Department of Biology
Abstract
  • The tardigrade Hypsibius dujardini as a new model for studies on the evolution of development (Under the direction of Dr. Robert P. Goldstein, Ph.D.) How genes are used in a novel manner during development of different species to give rise to the diversity of morphological forms that we see in nature is a major question in biology. In order to address this question, we have chosen to study embryonic development of the tardigrade Hypsibius dujardini. Tardigrades comprise a phylum that belongs to the protostome superclade Ecdysozoa and, as such, lies at a phylogenetically ideal position for studying the evolution of development. The Ecdysozoa also include arthropods and nematodes, groups that include two of the species whose development we know most about, Drosophila and C. elegans, and we can use many of the tools that have been developed in these species to study tardigrade development. Tardigrades have a number of qualities that make them attractive laboratory organisms (small size, short generation time, ease of husbandry), but there have been very few studies of tardigrade development to date. I have developed a number of protocols for investigating embryonic development in H. dujardini, including immunostaining, live imaging, and staining for several markers of tissue-specific differentiation. By immunostaining with antibodies that recognize homologs of the arthropod segmentation proteins Pax 3/7 and Engrailed, I was able to show that while Pax 3/7 homologs could be playing a similar role in neural development in tardigrades as in arthropods, I found no evidence of pair-rule type patterning for Pax 3/7 homologs in H. dujardini. Engrailed expression in the ectoderm of H. dujardini embryos, on the other hand, is more similar to what is seen in the development of arthropod segmentation, indicating that this portion of the segmentation cascade may function in a conserved manner in tardigrade embryos. In order to facilitate future studies of tardigrade development, I developed a staging system for H. dujardini embryos. I used both live imaging of embryos and DAPI staining of fixed embryos to describe developmental events in this species. By comparing tardigrade development to that of arthropods, nematodes, and other metazoan species, we will gain insight into how homologous genes function similarly or differently in development to produce the diverse morphology we see in nature.
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  • In Copyright
Advisor
  • Goldstein, Robert P.
Degree granting institution
  • University of North Carolina at Chapel Hill
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