Download Retinoic Acid - Wesleyan College Faculty

Women In Science
Outlook Good – Medical schools, Vet Schools >
parity
Outlook OK – Dental Schools = Women gaining
ground for parity, still some work to do (2002 =
40% female in National Dental Schools, 50% at
MCG)
“Glass ceiling” still applies – fewer women than
predicted hold tenured positions, fewer are full
professors
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Reasons vary – career interruptions due to pregnancy
still problematic
Still some male-dominated areas (eg., engineering,
math, chemistry) where improvements can be made
at both entry and advanced levels
The 2009 Graduating Class of the
Medical College of Georgia School of Dentistry
Applications Received
Class Academic Qualifications
Applications
received for the
2005 entering
class:
Overall grade point
3.44
average:
Applications
received from
Georgia residents:
Number of
applicants granted
interviews:
Class size:
Ratio of Georgia
resident applicants
to enrollees:
237
237
131
62
3.82 to 1
Science grade
point average:
3.37
DAT Academic
Average:
18.6
DAT Perceptual
Test Average:
17.7
UGA Vet School Stats
Number of
Applicants
Number
Enrolled
Women /
Men
Enrolled
Average Age
of Enrolled
(Range)
At large
280
1
1/0
*
Georgia
192
71
54/17
25 (20-40)
Delaware
10
2
2/0
23 (*)
South
Carolina
55
16
14/2
22 (20-24)
West
Virginia
29
6
5/1
21 (21-23)
Totals
566
96
76/20
24 (20-40)
Average scores for accepted applicants
GPA
Cum.
At large *
GRE
Last 45hr
V+Q
GPA
Comb.
GPA
Science
GRE
Anal.
GRE
Biology
*
*
*
*
*
*
Georgia
3.53
3.49
3.59
1191
4.5
607
Delaware
3.68
3.46
3.73
1235
4.3
625
South
Carolina
3.72
3.67
3.77
1157
4.8
621
West
Virginia
3.70
3.67
3.79
1121
4.7
585
Overall
3.58
3.54
3.65
1180
4.5
608
Know What Makes A Difference
Excellent GPA essential


Pay attention to rigor
Be smart about scheduling
DAT/GRE/MCAT scores v. important



Take prep course if you can
Familiarity with computerized exams very useful
Get the books and use them
Internships invaluable


Do well, impress intern sponsors with work habits,
curiosity, engagement
Letters of rec from professionals important
Choose extracurriculars wisely
Experiences which differentiate you from others
should be pursued.
Career Choices and Goals
Difference between stated goals in early
career and path of career progression
Adjustments for academic reasons, for
family reasons, for monetary reasons
Internships vital to assisting in career
decisions
Solid academic preparation a must; later,
pedigree important
HAVE A PLAN
Map strategy for postgraduate plans
Engage in coursework, internships,
research opportunities that mesh with goal
Make your postgraduate plans a reality –
talk to representatives at schools to which
you are applying, find out about schools,
visit if possible
Senior year – backup plan in place
BEFORE graduation
The Secret Life of
Vitamin A
Holly Boettger-Tong, Wesleyan College
Department of Biology
What is Vitamin A ?
Required for normal vision
reproduction,differentiation,
homeostasis
Deficiency leads to blindness,
sterility
Retinol, Retinal, Retinoic acid
all have biological activity.
Nature of function depends
upon form, converting
enzymes, expression of
receptors for each retinoid
Retinoic Acid
Metabolite of Vitamin A
Organic compound that is produced endogenously
and whose production is dependent upon tissuespecific expression of enzymes (retinaldehyde
dehydrogenases, to be specific)
Affects vertebrate physiological processes
Development
Cell growth and differentiation
Morphogenesis
Adult tissue function
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Retinoid Isomer Structures
All-trans Retinoic acid
9-cis Retinoic acid
How Retinoic Acid Effects
Gene Expression
Retinoid binding
protein
Gene product
Retinoic Acid
Receptor – binds
ligand and DNA,
Influencing gene
expression
What is the Effect of Retinoic Acid
During Early Development?
What are the dose-response characteristics of
retinoic acid’s effects on Oryzias latipes
development?
What insight into the role of retinoic acid in
cardiogenesis might be gleaned from these
experiments?
What are the gene expression changes associated
with retinoid-altered development
How does the stage of development effect sensitivity
to retinoid effects?
Retinoids and Development
Specification of primary antero-posterior
axis, forming nervous system, establishing
limbs
Control of gene expression – produced at
specific developmental times to yield a
gradient of retinoic acid
Defects in retinoic acid production or in
receptor expression result in defective
development. Excess retinoic acid is
teratogenic, causing malformations which
are informative as to retinoid action in
specific tissues.
The Japanese Killifish
Oryzias latipes are native to Japan, Taiwan, and
southeastern Asia
Freshwater and common to rice paddies
Rapid development (ranges from 1-3 weeks) in
a translucent egg makes them ideal for
determining potential teratologic effects of
chemicals of interest
Good for students due to ease of culture
Experimental Design
Modified FETAX – treat embryos for three
days with different concentrations of
retinoid (or vehicle control), then
discontinue use and observe effects of
treatment
Monitor embryos daily, observing
morphology
Determine effects on hatching
Dose Dependent Inhibition of
Medaka Hatching by ATRA and 9-cis RA
100
% Failed Hatching
100
83
80
60
40
33
20
33
16
0
0
0.001
0.01
0.1
Dose of Retinoid (mM)
1
Embryonic Morphology on Experimental Day 6
Control
ATRA
9-cis RA
10nM
100nM
1mM
Cardiac Morphology
Is Dramatically Altered by 100nM ATRA
Treatment
Control
100nM ATRA
Cardiac Morphology
Is Altered by 50nM ATRA Treatment
50nM ATRA
Control
Range of Cardiac Malformations
Normally
Chambered
Hearts
Heart
Looping
Heart Strings/
Cardiac Tissue
Masses
Control
+++
-
-
10nM ATRA/9-cis
+++
-
-
50nM ATRA/9-cis
++
+++
-
100nM ATRA/9-cis
-
++
+++
1µM ATRA/9-cis
-
-
-
What are the Genetic Consequences of
Treating Neurula Embryos with Retinoic
Acid?
To study global changes in gene expression
patterns we use DNA microarrays
Large numbers of genes (from 5-10K)
represented on small coated glass slides
(chips)
Assess changes in gene expression patterns in
normal vs treated embryos (work in progress)
What are the Effects of Retinoic
Acid on Uterine Function?
Estrogen is a potent regulator of uterine growth
In immature rats, all uterine cell types proliferate
in response to estrogen treatment
What effect, if any, does retinoic acid have on
estrogen-induced uterine cell proliferation?
Can these effects be reiterated in vitro, using
cultured primary cells?
Is there a difference in response between
primary cells and immortalized cells?
All-trans Retinoic Acid Inhibits Estrogen
Induced Uterine Myometrial and
Stromal Cell Proliferation
1. Treat animals
with 30mg/kg ATRA
prior to estradiol ( E2
stimulates cell
proliferation in OVX rats)
3. Inject 3H Thy
4. Remove uterus 24 hrs
post E2 injection
5. Section uterus
6. Expose to emulsion
7. Develop slides
Why Switch to Cell Culture
Experiments?
Advantages:
Easier to work with than whole animals
More manipulable, faster results
Greater range of treatment concentrations
Cheaper
Can extend studies to humans (cultured
human cells)
Disadvantages:
May not reiterate effect seen in vivo
Non-physiological
Primary cells have limited lifespan
Effect of Retinoic Acid on Human
Myometrial Cell Proliferation
Retinoic Acid Alters Uterine
Smooth Muscle Cell Morphology
Control, Day 6
10-9 M ATRA, Day 6
Do Retinoids Influence the Growth of
Immortalized Human Uterine Cells?
Dose-Dependent Effects of ATRA on
Immortalized Myometrial Cell Survival
Control
10-9 M ATRA
10-11M ATRA
10-7 M ATRA
What Is the Mechanism of Differential
Sensitivity to ATRA Between Primary
Non-Pregnant Cells and Immortalized
Pregnant Cells?
Death due to necrosis or apoptosis?
Irrespective of Method of Immortalization?
What gene expression changes occur in
pregnant vs non-pregnant myometrial cells?
Do any of these gene changes increase
sensitivity to retinoids?
What Secrets Have These Experiments
Revealed About Retinoids?
Role of retinoids in heart development poorly
understood
Implications for cardiac malformations in higher
vertebrates (including man); opportunity to dissect
gene pathway leading to chambering
Retinoic acid inhibits smooth muscle cell
proliferation in both normal and benign tumor cells
(implications for pharmacologic treatment of
leiomyomas?)
Deducing mechanism of action may reveal more
information about growth control mechanisms in
these cells (implications for deciphering events
during pregnancy which lead to myometrial cell
hyperplasia)
Acknowledgements
Namita Mohanty (GH 2003, “Comparative Effects of Alltrans and 9-cis Retinoic Acid on Medaka (Oryzias
latipes) Development” BIOS 76(1), 2005.
Erin Rooney (Pirate 2005, “Effects of All-trans retinoic
acid on Immortalized Human Myometrial Cells”)
Munroe Sisters
Tri-Beta Research Foundation
NSF MRI 0116189