Publication Date

2017-5

Document Type

Honors Thesis

Degree Name

Bachelor of Arts

Department

Biological Sciences

Advisors

Laura A. Katz

Keywords

FISH, Nuclear scaling, Ciliates, Macronuclear development, Extensive fragmentation, Germline, Soma, Fluorescence in situ hybridization, Eukaryote cells-Genetics, Chilodonella, Nuclear fragmentation, Somatic embryogenesis

Abstract

Macronuclear development in ciliates is typically studied in only a few model taxa. At least three ciliate classes (Armophorea, Phyllopharyngea, and Spirotrichea) extensively fragment and unscramble their somatic genomes during development. Though Phyllopharyngea may have independent evolutionary origins for extensive fragmentation, of these three lineages, macronuclear development has almost exclusively been studied in the Spirotrichea. Preliminary data on Chilodonella uncinata (Phyllopharyngea) has indicated similar features to spirotrichous ciliates during development, including polytene chromosomes and three stages of macronuclear development: initial amplification, a DNA poor stage, and final amplification. The aim of this research is to characterize the macronuclear development of Chilodonella uncinatato test the following hypotheses: 1) cell size, nuclear size, and DNA content increase, and ratios between these variables become dysregulated during development; 2) the positions of all three nuclei (germline micronucleus, parental macronucleus, and developing macronucleus) are related to the stage of development; 3) the timeline of the developing macronucleus includes an initial round of amplification, a DNA poor stage, and a final round of amplification; and 4) chromosomal fragmentation and elimination occur following the initial amplification; telomeres are synthesized during the DNA poor stage; and gene sized chromosomes are amplified in the final stage. This work serves to add to our understanding of macronuclear development in ciliates by studying an under-investigated lineages with unique molecular features.

Language

English

Comments

61 pages : color illustrations. Includes bibliographical references (pages 58-61)

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