蜜桃影像

Dr. Kathleen Karrer蜜桃影像

MilwaukeeWI53201United States of America

Emeritus Professor

Faculty 1989-2014

Dr. Kathleen Karrer and her three younger sisters were raised in Michigan by very supportive parents who encouraged all of their career goals.  Dr. Karrer's inclination towards teaching appeared early, when she and her sisters played "school" after school, and she always got to be the teacher.  Her earliest experiments were performed in the kitchen with her Dad and were along the lines of putting a balloon on top of a bottle and observing that when the air in the bottle was heated the balloon would expand.  When the bottle was placed in the freezer...  

After discovering in high school that she liked biology, she came to 蜜桃影像 as an undergraduate, where she enjoyed the laboratory courses, especially Experimental Cell Biology and Experimental Developmental Biology.  In the Cell Biology lecture course with Dr. Anthony Mahowald, she became interested in the general question of how the germ line of an organism differs from the soma.   

At the advice of her Professors at 蜜桃影像, she went to Yale University to do her graduate work in the laboratory of Dr. Joseph Gall.  The lab was a fantastic environment, where she met many great scientists and made good friends.  The most unusual characteristic of the lab was that while its members all thought about chromosomes, they worked on an astounding array of organisms, including protozoa, flies and amphibians.  It was there that she was introduced to the ciliated protozoan, Tetrahymena, which was to be the subject of her life's work.  In the course of her dissertation project she made the surprising discovery that the extrachromosomal rDNA molecules were giant, 20kb, inverted repeats.   

For her postdoctoral studies she went to the lab of Dr. Anthony Mahowald, who by this time was at Indiana University.  Again, she met some wonderful people and scientists, including Dr. Gail Waring, who was to become a lifelong friend and scientific colleague at 蜜桃影像.  Over the years they have shared a lot scientifically, and some also some great vacations including a raft trip through the Grand Canyon and a night scuba dive with manta rays in Hawaii.  At Indiana, Dr. Karrer was interested in the nuclear bodies of Drosophila melanogaster germ cells.  The morphology of nuclear bodies varies with the species and corresponds to the species type of the cytoplasm rather than the nuclear genome.  Her goal was to isolate nuclear bodies and determine whether the nuclear body protein was the translational product of polar granule RNA.  However, the quantity of the nuclear bodies was too low to recover enough of them to complete this project.   

Upon starting her first faculty position at Brandeis University in 1979, she maintained her interest in the germ line vs. the soma, but decided to return to Tetrahymena as an experimental organism.  These fascinating single celled organisms have two nuclei, the germ line micronucleus and the somatic macronucleus.  During sexual reproduction, the parental macronucleus is destroyed and a new one develops from a mitotic product of the micronucleus.  Macronuclear development includes massive genome remodeling, including elimination of about 15% of the genome by removal of interstitial genomic sequences, breakage of the 5 micronuclear chromosomes into 181 macronuclear chromosomes, de novo methylation of adenine residues in the DNA and endoreduplication of the genome to a copy number of about 50.  At Brandeis her graduate students began studies on DNA methylation, determining the timing of methylation and showing that methylation was a stochastic process and that the maintenance methylase must have a de novo activity (Gail Harrison, Elizabeth Capowski).  In addition, they initiated studies on some of the DNA rearrangements that occur in the genome (John Wells, Bernice Allito, Susan Gavens), and identified a new stage in the development of sexual maturity (Melissa Rogers). 

In 1989, Dr. Karrer came to 蜜桃影像 as a Clare Boothe Luce Professor.  There she was again fortunate to attract some talented and hardworking graduate students.  Among other things, they showed that DNA methylation was dependent on chromatin structure, as opposed to DNA sequence (Teresa Van Nuland) and continued the work on eliminated sequences.  They showed that many of the eliminated sequences were homologous to transposable elements (Jill Gershan, Jeff Wuitschick) and continued the work on the mechanism of DNA elimination (Jay Ellingson, Namrata Patil). Jeff Wuitschick identified the first example of the Maverick elements as an eliminated DNA element in Tetrahymena, and made the surprising discovery that elimination could be induced by any part of these 20 kb elements, and did not require specific flanking sequences.  More recently, the work in the lab has been focused on a gene, ASI2, which is required for endocycling in the developing macronucleus (Rupa Udani, Shuqiang Li, Lihui Yin and Susan Gater).  Dr. Karrer has also enjoyed mentoring undergraduates in their first independent research projects.  Six of them, Michelle DiTomas, Stacia Pfeiffer, Paula Hempen, Paul Lindstrom, Alison Meyer and Andrew Lochowicz had their work published in peer-reviewed journals. 

In her spare time, Dr. Karrer enjoys gardening (perennials are best), attending plays at the Milwaukee Repertory Theater and 蜜桃影像 men's basketball games.  

Notable Awards: 

Clare Boothe Luce Professor, (1989-94) 

Fr. John P. Raynor Faculty Award in Teaching Excellence, 1999 

Nora Finnigan Werra Faculty Achievement Award, 2009