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Publication Date

2011-08-07

Availability

UM campus only

Embargo Period

2011-08-07

Degree Name

Master of Science (MS)

Department

Biology (Arts and Sciences)

Date of Defense

2011-05-06

First Committee Member

Zhongmin Lu

Second Committee Member

Jeffery Prince

Third Committee Member

Phillip McCabe

Abstract

Prenatal alcohol exposure is known to have many profound detrimental effects on human fetal development (fetal alcohol spectrum disorders), which may manifest into lifelong disabilities. Although hearing deficiency is a recognized effect, how alcohol affects the auditory/vestibular systems has not been well studied. This is the first study that used the zebrafish, Danio rerio, as a model organism to investigate morphological effects of alcohol on the developing octavolateral system (auditory, vestibular and lateral line). Zebrafish embryos of two hours post fertilization (hpf) were treated in 2% alcohol for 48 hours and screened at 72 hpf for morphological defects of the inner ear and lateral line neuromasts. Inner ear size and otoliths of zebrafish from both alcohol-treated and control groups were examined using light microscopy. Zebrafish were stained with fluorescent vital dyes to visualize lateral line hair cells using confocal microscopy. The size of neuromasts and length of kinocilia were measured using scanning electron microscopy. Results reveal that alcohol treatment during the early development impairs the formation of otoliths, neuromasts and their hair cells, as well as ear size and kinocilium length. We observed several otolith phenotypes including zero, one, two abnormal, two normal and multiple otoliths for alcohol-treated zebrafish. Fetal alcohol exposure appears to severely impact the size of both anterior and posterior lateral line neuromasts. Our results indicate that early fetal alcohol exposure most likely results in functional defects of the octavolateral system due to inner ear and lateral line dysmorphology.

Keywords

auditory; hair cell; hearing; lateral line neuromast; otolith; prenatal

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