Thomas D. KocherDepartment of Biology
BSCI 338K - Lecture 3
Developmental genetics of sex
determination
Migration of Primordial Germ Cell (PGCs)
Functional gene network analysis of testis development genes
109 genes with 1.5-fold change in expression from e13-e16 in the mouse gonad. Cell processes involved in testis development were determined based on the number of arrows connected to each box (connectivity). (Clement et al. 2007)
Genetic interactions
Developmental pathway
Central switch?
(DiNapoli and Capel, 2007)
Vertebrate sex determination
Ezaz et al. 2006
SRY
Tilapia
(Genomar)
Sex-linked markers in Oreochromis niloticus: LG1
(Lee 2003)
Ph.D thesis ofBo-Young Lee
Epistasis in O. aureus
LG 1
LG 3
X/X X/Y
W/Z
Z/Z
(Lee 2004)
LG1 and LG3 are distinct chromosomes
(Cnaani 2007)
Sex-linked markers in tilapia
Sex determination in Malawi cichlids
• Survey of 19 species in five genera• 94 families (2066 offspring)• Extensive variation in sex ratios• Genotyped for microsatellite markers• Focused on LG 5 and 7
M.S. thesis of Jennifer Ser
Metriaclima phaeos - XY on LG7
Metriaclima phaeos - WZ on LG5
M. fainzilberi - WZ and XY
Grand summary…
Hidden complexity of genetic interactions
LG7 XY(widespread)
LG5 WZ(OB species)
LG? XYM. kompakt
LG?M. callainos
LG? WZM. lombardoi
LG? WZM. pyrsonotus
Metriaclima lombardoi
44 chromosomes
+ B chromosome
(some females)
Duplication in
largest pair
(some males) Irani Ferreira
Sex determiners in African cichlidsTilapia Malawi
Candidate gene on LG1
Ijiri et al. 2006
Quantitative PCR of mRNA
Ijiri et al. 2006Tilapia gonads 0-70 days
Project Opportunities: Sex Determination
• Fine map the LG1 XY locus in Nile tilapia
• Fine map the LG7 XY locus in Malawi cichlids
• Map new sex determiners in Malawi cichlids
• Map sex determiners in Lake Victoria cichlids
• Map sex determining locus in Astatotilapia burtoni
• Annotate sex determining regions of other fishes onto cichlid genome sequence
• Characterize expression of candidate genes during gonad development
Proposal Process• Proposal format
– Cover page
– Abstract (300 words)
– Proposal Body (10 pp total)
• Background (2-3 pp)
• Preliminary data (1-2 pp)
• Proposed research (5-6 pp)
• Expected Results and timeline (1 pp)
– References
– Budget
• Proposals due **** Feb 17, 2011 ****
• Peer reviews due Feb 22, 2011
• Panel meeting Feb 24, 2011
• Project start date March 1, 2011
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