Transcript 9/23 - Utexas

Regulating Gene Expression
Exams back T 9/30
Bonus #1 is due 10/02
What makes us
who we are?
Nature and
Nurture
Based on “Nature via Nurture” by Matt Ridley (2003)
Genes
Traits
Genes code for proteins. These proteins
give rise to traits…
Genes
Traits
Genes code for proteins. These proteins
give rise to traits…
It is rarely this simple.
Imprinting:
exposure to movement
(environment) sets
“mother”
X/Y chromosomes
in humans:
genes = traits
This article, shows how even today people see
nature and nurture as opposing each other:
The Pathogenesis of the Glaucomas:
Nature versus Nurture
Mackey, et al., Clinical & Experimental Opthamology
vol 36, pg 297, April 2008
Twin studies have been used to determine
the heritability of various traits.
Types of twins:
http://pennhealth.com/health_info/pregnancy/000199.htm
Twin studies have been used to determine
the heritability of various traits, but there
are some caveats:
How many twins have been studied?
How different are the environments?
Correlation of weight and relatedness
Correlation of weight (BMI)
%
Identical twins reared together
80
Identical twins reared apart
72
Fraternal twins reared together
43
Biological siblings
34
Parents and children living together 26
Adopted children and parents
4
Unrelated children living together
1
*But food preference shows little genetic
correlation
The nature of environmental influences on weight and obesity: A behavior genetic analysis. Grilo, Carlos M.;
Pogue-Geile, Michael F.; Psychological Bulletin, Vol 110(3), Nov 1991. pp. 520-537. And two books by
Matt Ridley: Nature via Nurture (2003) and Genome: the Autobiography of a Species in 23 Chapters (1999)
Intelligence
Correlation of IQ Inheritance :
The same person tested twice
Identical twins reared together
Identical twins reared apart
Fraternal twins reared together
Biological siblings
Parents and children living together
Parents and children living apart
Adopted children living together
Unrelated people living apart
%
87
86
76
55
47
40
31
0
0
From two books by Matt Ridley: Nature via Nurture (2003) and Genome: the Autobiography of a Species in 23 Chapters (1999)
When the
environment is
equal (everyone has
access to resources),
genetic differences
are magnified.
When environments
are different (only a
few have access to
resources),
environmental
differences are
magnified.
Proof or disproof?
Correlation of IQ Inheritance :
The same person tested twice
Identical twins reared together
Identical twins reared apart
Fraternal twins reared together
Biological siblings
Parents and children living together
Parents and children living apart
Adopted children living together
Unrelated people living apart
%
87
86
76
55
47
40
31
0
0
From two books by Matt Ridley: Nature via Nurture (2003) and Genome: the Autobiography of a Species in 23 Chapters (1999)
Can we see a genetic basis for complex
behaviors?
Voles
Prairie
Montane
• Monogamous
• Nonmonogamous
• Both parents care • Mother cares for
for young
young briefly
Oxytocin and Vasopressin
(hormones)
Water/salt
balance
Contraction
of womb
and milk
production
Encourages
bonding
between
individuals
Hormones are
molecules produced in
one cell and signal
another.
Oxytocin and Vasopressin
(hormones)
Water/salt
balance
Contraction
of womb
and milk
production
Encourages
bonding
between
individuals
Voles
Prairie
Montane
• Monogamous
• Nonmonogamous
• Both parents care • Mother cares for
for young
young briefly
Voles
Prairie
• Monogamous
• Both parents care
for young
Montane
• Nonmonogamous
• Mother cares for
young briefly
Same levels of oxytocin and vasopressin
Hormones are
molecules produced in
one cell and signal
another.
Voles
Prairie
• Monogamous
• Both parents care
for young
Montane
• Nonmonogamous
• Mother cares for
young briefly
Same levels of oxytocin and vasopressin
• More receptors
• Less receptors
Voles
Prairie
Montane
• Monogamous
• Nonmonogamous
• Both parents care
• Mother cares for
for young
young briefly
Same levels of oxytocin and vasopressin
• More receptors
• Less receptors
Inject hormone into brain
•?
• ?
Voles
Prairie
Montane
• Monogamous
• Nonmonogamous
• Both parents care
• Mother cares for
for young
young briefly
Same levels of oxytocin and vasopressin
• More receptors
• Less receptors
Inject hormone into brain
• Monogamous
• Nonmonogamous
Voles
Prairie
Montane
• Monogamous
• Nonmonogamous
• Both parents care
• Mother cares for
for young
young briefly
Same levels of oxytocin and vasopressin
• More oxytocin
• Less oxytocin
receptors
receptors
Block receptors
•?
• ?
Voles
Prairie
Montane
• Monogamous
• Nonmonogamous
• Both parents care
• Mother cares for
for young
young briefly
Same levels of oxytocin and vasopressin
• More oxytocin
• Less oxytocin
receptors
receptors
Block receptors
• Nonmonogamous
• Nonmonogamous
Voles
Prairie
• Monogamous
• Both parents care
for young
Montane
• Nonmonogamous
• Mother cares for
young briefly
Same levels of oxytocin and vasopressin
• More oxytocin
• Less oxytocin
receptors
receptors
Increase levels of receptors (genetically) in
ventral pallidum
• Monogamous
• Monogamous
Voles
Prairie
• Monogamous
• Both parents care
for young
Montane
• Nonmonogamous
• Mother cares for
young briefly
Same levels of oxytocin and vasopressin
• More receptors
• Less receptors
Why might these voles use different
reproductive strategies?
Prairie voles
Montane voles
• Monogamous
• Nonmonogamous
• Both parents care • Mother cares for
for young
young briefly
Why might these voles use different
reproductive strategies?
Prairie voles:
Montane voles:
Resource poor
Resource rich
habitat
habitat
• Monogamous
• Nonmonogamous
• Both parents care • Mother cares for
for young
young briefly
We looked at the
mechanisms of
gene expression,
now we will look
at its regulation.
Combinations of
3 nucleotides
code for each 1
amino acid in a
protein.
Exons are a very
small part of DNA
Fig 15.1
Each step in gene
expression presents an
opportunity to regulate
when and how much of
a gene product will be
produced.
Fig 15.1
Why change gene
expression?
•Different cells need
different components
•Responding to the
environment
•Replacement of
damaged/worn-out parts
Two points to keep in
mind:
1. Cellular components
are constantly turnedover.
2. Gene expression takes
time:
Typically more than an
hour from DNA to
protein. Most
rapidly 15 minutes.
Fig 15.1
Blood clotting must happen within minutes
mRNA levels change
in response to cold
acclimation
Fowler and Thomashow
The Plant Cell, Vol. 14, 1675-1690, 2002
DNA damage inhibits rRNA transciption
Fig 1b
The ATM repair pathway inhibits RNA polymerase I
transcription in response to chromosome breaks
Nature Vol 447 pg 730-734 (7 June 2007)
•Gene expression can be
controlled at many
points between DNA and
making the final
proteins.
•Changes in the various
steps of gene expression
control when and how
much of a product are
produced.
Fig 15.1