THE EVOLUTION OF GENETIC MATERIAL ON THE Y CHROMOSOME AND ITS ROLE IN GENDER DETERMINATION Sam Taylor and Lauren Russell Biology 101H Dr. Jean DeSaix Dr. Moriah Beck April 15, 2009

S EX D ETERMINATION Women are XX Men are XY Primary vs. Secondary sex characteristics

E VOLUTION OF Y CHROMOSOME

E VOLUTION OF Y AND SRY

SRY AND SOX’S (SOX9 AND SOX3)

SRY ENABLES SOX9 EXPRESSION

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XX M ALE S EX R EVERSAL S YNDROME Human genetic disorder characterized by male physical characteristics and XX chromosomal karyotype In case study, tested to determine why self- identified male is infertile and has undescended testicles Gel electrophoresis compared subject’s DNA with normal male and normal female DNA

SRS P ATIENT N ORMAL M ALE

XX S EX R EVERSAL S YNDROME C ASE S TUDY C ONCLUSION This subject’s SRS syndromes caused by translocation of father’s SRY gene from Y to X chromosome during meiosis Confirmed SRY is required for physical male characteristics to be expressed Strengthened hypothesis that SRY silences SOX3 and enhances SOX9 on male X chromosomes

B IBLIOGRAPHY Delbridge, M. L. & Marshall Graves, J. A. (1999). Mammalian Y Chromosome Evolution and the male-specific functions of Y chromosome-borne genes. Journals of Reproduction and Fertility, 4 (2), Waters, P. D., Wallis, M. C., & Marshall Graves, J. A. (2007). Mammalian sex-Origin and evolution of the Y Chromosome and SRY. Seminars in Cell & Developmental Biology, 18 (3), Schartl, M. (2004). Sex Chromosome evolution in non-mammalian vertebrates. Current Opinion in Genetics and Development, 14 (6), Wang, T., Liu, J. H., Yang, J., Chen, J. & Ye, Z. Q.(2009). XX Male Sex Reversal Syndrome: A Case Report and Review of the Genetic Basis. First International Journal of Andrology: Andrologia, 41 (1), Campbell, Neil A. and Reece, Jane B. (2008). Biology (Eighth Edition). New York, NY: Pearson Benjamin Cummings. Pearson Education. secondary sex character. (2009). In Encyclopædia Britannica. Retrieved March 23, 2009, from Encyclopædia Britannica Online: