A Simultaneous Genetic Screen for Zygotic and Sterile Mutants in a Hermaphroditic Vertebrate
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Authors
Sucar, Sofia
Issue Date
2013-01-07
Type
Thesis
Language
en_US
Keywords
Mangrove Killifish , Zygotic Mutants , Fish , Biology , Genetic Screen , Maternal Effect , Hermaphrodite , Sterile , Vertebrate , Kryptolebia marmoratus
Alternative Title
Abstract
The mangrove killifish (Kryptolebias marmoratus) is unique among vertebrates
due to its self-fertilizing mode of reproduction involving an ovotestis, analogous to the
nematode Caenorhabditis elegans. It develops externally, is easy to maintain, and reaches sexual maturity in about 100 days, making it a desirable vertebrate model organism for
developmental genetics. As a continuation of an initial pilot screen (Moore, Sucar,
Newsome, Ard, Bernhardt, Bland, & Ring, 2012) in which 73 out of 284 F1 fish were
found to display zygotic defects in their F2 offspring (25%), a three generation genetic
screen was performed using N-ethyl-N-nitrosourea as a mutagen in order to a) confirm
zygotic mutant allele heritability and b) simultaneously score for homozygous recessive
mutant sterile F2 fish. One to ten F2 fish per family were set up and their progeny
screened. From a total of 307 F2 fish screened, 10 were found to be 10 males and 16 were
found to be sterile. From the remaining 281 fish, 92 showed a wild type phenotype and
189 were carriers of zygotic recessive alleles. These carriers produced 25% progeny
exhibiting several zygotic phenotypes previously described in zebrafish (Mullins et al.,
1994) as well as in a K. marmoratus pilot screen. Also, new phenotypes such as golden
yolk, no trunk, and short tail, were discovered. In order to confirm inheritance of sterility,
fish were grown from the F3 generation from siblings of sterile F2 mutants. From 284 F3
fish belonging to 10 previously identified sterile families, 12 were 10 males. From the
remaining 272 fish, 69 were wild type, 83 were sterile and 120 were classified as */+
(either wild type or carriers) because their genotypes were undefined. This screen
provides proof of principle that K. marmoratus is a powerful vertebrate model for
developmental genetics and can be used to identify mutations affecting fertility.
Description
Thesis "A Simultaneous Genetic Screen for Zygotic and Sterile Mutants
in a Hermaphroditic Vertebrate" by Sofia Sucar, Fall 2012.