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