Dr. Alex M. Schreiber
Assistant Professor of Biology
Office: Johnson Hall of Science 121
Phone: 315-229-5822, fax:315-229-7429
email: aschreiber@stlawu.edu

Education:

B.A. University of Colorado, Boulder, CO (1989)
United States Peace Corps Volunteer, Kenya, E.A. (1989-1992)
M.S. Eastern Washington University, Cheney, WA (1994)
Ph.D. University of Rhode Island, Kingston, RI (1998)
Post-doctoral Fellow Carnegie Institution, Baltimore, MD (1998-2002)
Staff Associate Carnegie Institution, Baltimore, MD (2002-2007)
Visiting Assistant Professor, College of Notre Dame, Baltimore, MD (2007-2008)

Courses Offered:

Environmental Animal Physiology (Biol 247c)
Comparative Endocrinology (Biol 270)
Biology of Metamorphosis
Biology of Movie Monsters
Intro to Cell Biology (Biol 250)

Research Interests:

Nothing fascinates me more in this world than the mystery of vertebrate metamorphosis. How does a tadpole turn into a frog? What genes mediate the abrupt transformation of a larval fish or amphibian into its juvenile form? How did metamorphosis evolve? I study metamorphosis in two very different species: the African clawed frog, Xenopus laevis, and marine flatfishes (flounder, halibut, soles, tonguefish). Unlike frogs, which are typical bilaterally symmetrical vertebrates, adult flatfish are the most behaviorally lateralized and morphologically asymmetrical vertebrates the world has ever known: they have both eyes on the same side of the head, and they spend their lives swimming on one side. Interestingly, flatfish LARVAL morphology and behavior resembles that of other fish: their skull morphology is bilaterally symmetrical, and they swim with an upright posture. However, several weeks to months after hatching, these larval flatfish experience one of nature’s most dramatic transformations: first, they begin to develop a highly lateralized swimming posture similar to that of the adult, and second, their skull remodels abruptly, facilitating the migration of one eye over the top of the head to the other side.

The diverse developmental programs of tadpole metamorphosis, such as programmed cell death (e.g. gill and tail resorption), cell proliferation (limb growth), and organ remodeling (brain, skull, and gut) are mediated entirely by one small molecule: thyroid hormone (TH). In the absence of TH, a tadpole will grow, but will never turn into a frog. The receptors for TH are nuclear transcription factors that bind to specific regions of DNA (thyroid response elements, or TREs) located within the promoter regions of some genes; the binding of TH and its receptors to these TREs causes thyroid hormone responsive genes to be turned on or off to carry out different metamorphic programs. Incredibly, thyroid hormone appears to mediate this indirect development in ALL metamorphosing vertebrates, including flatfish.

These are a few research topics that keep me up at night and that I love address in the lab:

• The Molecular Evolution of Vertebrate Metamorphosis
  
• Does TH regulate more genes in metamorphosing vertebrates (frogs, salamanders, flatfish, eels, and lamprey) than in non-metamorphosing vertebrates (everyone else)?
• Do metamorphosing vertebrates have a greater number of TREs than non-metamorphosing verts?
• Were these TREs gained/lost/silenced/activated in different species throughout evolution?

• Organogenesis of the Amphibian Gut
  
  • How do different gut tissues (epithelial, mesenchyme, smooth muscle, nervous) interact with each other to remodel the gut of a vegetarian tadpole into that of a carnivorous frog?
    
    
• Left-Right Asymmetry: Frog vs. Flatfish
  
  • How does TH mediate a bilaterally symmetrical metamorphosis in tadpoles, but an asymmetric metamorphosis in flatfishes?
    
    
• Ontogeny of Flatfish Behavioral Asymmetry
• How does changing visual (eyes) and vestibular (inner ear) information interact to cause larval flatfish to transition from an upright to a lateralized swim-posture?

Selected Publications:

Kuan, Y-S, Gamse, J.T., Schreiber, A.M., Halpern, M.E. (2007). Selective asymmetry in a conserved forebrain to midbrain projection.  Journal of Experimental Zoology. 308, 669-678.

Schreiber, A.M. (2006). Asymmetric craniofacial remodeling and lateralized behavior in larval flatfish. Journal of Experimental Biology. 209, 610-621.

Schreiber, A.M., Cai, L., Brown, D.D. (2005). Remodeling of the intestine during metamorphosis of Xenopus laevis. Proceedings of the National Academy of Sciences USA. 102, 3720-3725.

Schreiber, A.M. and Brown, D.D. (2003). Tadpole skin dies autonomously in response to thyroid hormone at metamorphosis. Proceedings of the National Academy of Sciences USA. 100,  1769-1774.

Das, B., Schreiber, A.M., Huang, H., Brown, D.D. (2002). Multiple thyroid hormone-induced muscle growth and death programs during metamorphosis in Xenopus laevis. Proceedings of the National Academy of Sciences USA. 99,  12230-12235.

Schreiber, A.M., Das, B., Huang, H., Marsh-Armstrong, N., Brown, D.D. (2001). Diverse developmental programs of Xenopus laevis metamorphosis are inhibited by a dominant negative thyroid hormone receptor. Proceedings of the National Academy of Sciences USA. 98,  10739-10744.

Schreiber, A.M. (2001). Metamorphosis and early larval development of flatfishes (Pleuronectiformes): an osmoregulatory perspective. Comparative Biochemistry and Physiology  129, 587-595.

Schreiber, A.M. and Specker, J.L. (2000). Metamorphosis in the summer flounder, Paralichthys dentatus: thyroidal status influences changes in gill mitochondria-rich cells. General and Comparative Endocrinology  117, 238–250.

Schreiber, A.M. and Specker, J.L. (1999). Metamorphosis in the summer flounder, Paralichthys dentatus: changes in gill mitochondria-rich cells. Journal of Experimental Biology 202, 2475–2484.

Schreiber, A.M. and Specker, J.L. (1999) Metamorphosis in the summer flounder, Paralichthys dentatus: thyroidal status influences salinity tolerance. Journal of Experimental Zoology 284, 414–424.

Schreiber, A.M. and Specker, J.L. (1999). Early larval development and metamorphosis in the summer flounder (Paralichthys dentatus): changes in percent whole body water content and effects of altered thyroid status.Journal of Fish Biology 54, 148-157.

Schreiber, A.M. and Specker, J.L. (1998). Metamorphosis in the summer flounder (Paralichthys dentatus): stage-specific developmental response to altered thyroid status. General and  Comparative  Endocrinology 111, 156-166.

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