David C. Page has been a pioneer in the field of mammalian
sex determination for 20 years. He conducts studies of the sex
chromosomes and their roles in germ cell development, with special attention
on the function, structure, and evolution of the Y chromosome. Dr.
Page’s laboratory, in conjunction with colleagues at Washington
University, reconstructed the evolution of today's X and Y chromosomes
from an ancestral pair of autosomes that existed 300 million years ago. They
discovered that most Y chromosome genes are members of Y-specific families
that are primarily expressed in testicular germ cells, and exist as
mirror-image pairs on massive palindromes that are sites of frequent
gene conversion. Thus, the male-specific chromosome is intensely
recombinogenic despite the absence of conventional crossing over. Dr.
Page’s laboratory also discovered and characterized the most common
genetic cause of spermatogenic failure in humans. He is now turning
his attention to the question of germ cell sex determination in mammals
and to the development of the ovary.
2005 Symposium Topic: Genes, gender and germ cells |
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Allan
C. Spradling studies germ cells throughout their life
cycle, from fertilized eggs to germline stem cells in the adult. Several
years ago, Dr. Spradling and his colleagues used lineage tracing and
molecular techniques to identify a germline stem cell population in
the Drosophila ovary. Exploring the interactions between stem
cells and their specialized cellular microenvironment created by the
somatic niche led to a detailed molecular model for the control of stem
cell maintenance throughout adult life and oocyte differentiation. The
experimental beauty of these studies and the molecular insight gained
rapidly established the fly germline stem cell system as a model for
other stem cell studies. In addition to defining germline stem
cells, Dr. Spradling is also interested in the cellular and molecular
mechanisms underlying oocyte differentiation in both flies and mice. By
suggesting that oocytes may selectively remove damaged organelles such
as mitochondria that may otherwise be detrimental for the success of
the next generation, his studies address one of the most intriguing
questions of germ cell development.
2005 Symposium Topic: Stem cells searching for a meaningful relationship |
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Larry Young is interested in the molecular, cellular and
neurobiological mechanisms that underlie the regulation of social behavior. Specifically,
much of Dr. Young's research focuses on the role of oxytocin, vasopressin,
CRF and their receptors in the regulation of social recognition, social
bonding, and more recently, the consequences of social loss. His
research utilizes both transgenic and knockout mice, as well as monogamous
voles, and makes comparisons with primate species when possible.
2005 Symposium Topic: The neurobiology of the pair bond |
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Lique Coolen’s long-term research goal has been to
understand how the brain regulates motivation and reward using sexual
behavior in rodents as a model system. Recently her laboratory
has identified a population of spinal neurons that play a pivotal role
in the control of ejaculatory reflexes. The cell-specific lesions
of these cells completely abolish ejaculatory reflexes. Moreover,
these spinal neurons have anatomical connections to other spinal regions
where they control the coordinated autonomic and motor outflow necessary
for ejaculation. In addition, this population of spinal neurons
has projections to the thalamus where sensory signals specifically related
to ejaculation are conveyed. In turn, the thalamus projects to
various brain regions that may contribute to the rewarding or reinforcing
properties of ejaculation. Recently, they have shown that sexual
experience results in functional, morphological, and transcriptional
alterations of the mesolimbic system that plays an important role in
regulation of motivation and reward. Dr. Coolen and her laboratory
hypothesize that this plasticity may contribute to the reinforcing properties
of sexual behavior.
2005 Symposium Topic: The neurobiology of sexual reward |
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Ed
Kravitz and his laboratory have been studying aggression
using a lobster model system for over 20 years. Recently, with
a sequenced genome available and with powerful methods available for
manipulating genes, the focus of interest of his laboratory has shifted
to studies of aggression in fruit flies. In general, it is not
well known that fruit flies fight, even though the first mention of
fighting between pairs of male flies dates back to Sturtevant in 1915. Even
fewer citations exist in the literature suggesting that pairs of female
Drosophila fight also. Dr. Kravitz and his laboratory have carried
out a quantitative analysis of fighting behavior between pairs of male
and female fruit flies and they observe that some of the behavioral
patterns (modules) seen during fights are similar in male and female
fights, some are unique to females and some are unique to males. They
have been manipulating the expression of genes of the gender determination
pathway (transformer and fruitless) regionally and
globally in fly brains addressing the issue of whether they can transfer
female patterns of aggression to male brains and/or male patterns to
female brains.
2005 Symposium Topic: The modularity of behavior: genetics and
the patterns of |
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Barbara
Meyer’s laboratory uses the nematode C. elegans as
a model to study fundamental aspects of chromosome dynamics and
development. The
laboratory’s recent focus has been on understanding how chromosome
architecture and segregation are controlled during meiosis and
mitosis, how the sex chromosome is regulated to normalize gene expression
between the two sexes, and how choices are made between different
cell fates during development.
2005 Symposium Topic: Sex and repression |
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Catherine Dulac’s laboratory explores how pheromones are sensed and
induce specific behaviors. Pheromones have evolved in all animal
phyla to signal the sex and the dominance status of animals and to
promote mating and social rituals among conspecifics. In mammals,
pheromones are primarily detected by the vomeronasal organ (VNO). The
Dulac lab has identified several hundred candidate pheromone receptors,
uncovered the wiring diagram of VNO fibers, and generated mutant mice
that lack VNO function. These animals display courtship and
mounting behavior indiscriminately toward both males and females. These
data contradict the established notion that VNO activity is required
for the initiation of male-female mating behavior in the mouse and
suggest instead a critical role in insuring sex discrimination.
2005 Symposium Topic: Molecular architecture of pheromone sensing
in mammals |
