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James W. Pennebaker, Chair The University of Texas at Austin, SEA 4.212, Austin, TX 78712 • (512) 475-7596

David Crews

Professor Ph.D., Rutgers University

Ashbel Smith Professor

Contact

Biography

RESEARCH SUMMARY

One of my research programs focuses on sex determination as a case study in how evolution has produced very different mechanisms for achieving the same end. Here I take advantage of the fact that in many reptiles the sex of the offspring depends on the incubation temperature of the egg, a process known as temperature-dependent sex determination (TSD). One question concerns how the physical stimulus of temperature is transduced into a physiological stimulus that operates ultimately at a molecular level to determine an individual's gonadal sex. In this work I use the red-eared slider turtle as the animal model system. I have demonstrated that sex steroid hormones are the physiological equivalent of incubation temperature, serving as the proximate trigger for male and female sex determination. Temperature appears to accomplish this end by acting on genes coding for steroidogenic enzymes (e.g., steroidogenic factor 1 and aromatase) and sex steroid hormone receptors (e.g., estrogen and androgen receptors), and other transcription factors and signaling molecules (e.g., Sox9, Wnt4, FOXL2, Mis, and Pumilio). Phylogenetic analysis indicates that TSD is the precursor of sex determination by genotypic mechanisms (e.g., sex chromosomes). My other research focuses on epigenetics. There is now evidence that an individual's likelihood of developing health problems involves a combination of that individual's own exposures as well as exposures of ancestors in generations past. This transmission of life experiences across generations represents the newly emerging field of environmental epigenetics.

Publications

Curriculum vitae

Interests

Physiology of behavior, sexual differentiation, and sex determination

PSY 341K • Animal Sexuality

44040 • Spring 2014
Meets TTH 200pm-330pm PHR 2.114
(also listed as WGS 323 )
show description

Topics of contemporary interest that may vary from semester to semester. Three lecture hours a week for one semester. May be repeated for credit when the topics vary. Prerequisite: For psychology majors, upper-division standing and Psychology 301 and 418 with a grade of at least C in each; for nonmajors, upper-division standing, Psychology 301 with a grade of at least C, and one of the following with a grade of at least C: Biology 318M, Civil Engineering 311S, Economics 329, Educational Psychology 371, Electrical Engineering 351K, Government 350K, Mathematics 316, 362K, Mechanical Engineering 335, Psychology 317, Sociology 317L, Social Work 318, Statistics 309, Statistics and Scientific Computation 302, 303, 304, 305, 306, 318.

PSY 341K • Animal Sexuality

43395 • Spring 2013
Meets TTH 200pm-330pm PHR 2.114
(also listed as WGS 323 )
show description

This course will emphasize the basics of sex determination and sexual differentiation, particularly as it relates to reproduction from the different levels of biological organization, from the molecular to the evolutionary. We will also discuss in some detail the ways hormones influence gene expression, the development of organ systems and the structure of cells, the interactions of endocrine secretions, the behavior of individuals, the structure of social hierarchies, and the evolution of mating systems. By the end of this course you should be able to discuss intelligently issues such as homosexuality in man and animals, environmental consequences of the release of agricultural and manufacturing chemicals into the environment on health, how hormones regulate reproduction and behavior, how stress affects reproduction and the immune system, how birth control pills work, etc.

PSY 341K • Animal Sexuality

43745 • Spring 2011
Meets TTH 200pm-330pm WEL 2.256
(also listed as WGS 323 )
show description

This course will emphasize the basics of sex determination and sexual differentiation, particularly as it relates to reproduction from the different levels of biological organization, from the molecular to the evolutionary. We will also discuss in some detail the ways hormones influence gene expression, the development of organ systems and the structure of cells, the interactions of endocrine secretions, the behavior of individuals, the structure of social hierarchies, and the evolution of mating systems. By the end of this course you should be able to discuss intelligently issues such as homosexuality in man and animals, environmental consequences of the release of agricultural and manufacturing chemicals into the environment on health, how hormones regulate reproduction and behavior, how stress affects reproduction and the immune system, how birth control pills work, etc.

PSY 341K • Animal Sexuality

43895 • Spring 2010
Meets TTH 200pm-330pm GRG 424
(also listed as WGS 323, BIO 383K, BIO 359R )
show description

Topics of contemporary interest that may vary from semester to semester. Three lecture hours a week for one semester. May be repeated for credit when the topics vary. Prerequisite: For psychology majors, upper-division standing and Psychology 301 and 418 with a grade of at least C in each; for nonmajors, upper-division standing, Psychology 301 with a grade of at least C, and one of the following with a grade of at least C: Biology 318M, Civil Engineering 311S, Economics 329, Educational Psychology 371, Government 350K, Mathematics 316, Psychology 317, Sociology 317L, Social Work 318, Statistics 309.

PSY 341K • Animal Sexuality

43150 • Spring 2009
Meets TTH 200pm-330pm WEL 2.256
(also listed as WGS 323, BIO 383K, BIO 359R )
show description

Topics of contemporary interest that may vary from semester to semester. Three lecture hours a week for one semester. May be repeated for credit when the topics vary. Prerequisite: For psychology majors, upper-division standing and Psychology 301 and 418 with a grade of at least C in each; for nonmajors, upper-division standing, Psychology 301 with a grade of at least C, and one of the following with a grade of at least C: Biology 318M, Civil Engineering 311S, Economics 329, Educational Psychology 371, Government 350K, Mathematics 316, Psychology 317, Sociology 317L, Social Work 318, Statistics 309.

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