Exams back T 9/30 Bonus #1 is due 10/02 Regulating Gene Expression

What makes us who we are? Nature and Nurture Based on “Nature via Nurture” by Matt Ridley (2003)

TraitsGenes Genes code for proteins. These proteins give rise to traits…

TraitsGenes 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:

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 (BMI)% Identical twins reared together80 Identical twins reared apart72 Fraternal twins reared together43 Biological siblings34 Parents and children living together26 Adopted children and parents 4 Unrelated children living together 1 *But food preference shows little genetic correlation Correlation of weight and relatedness 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 pp 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 twice87 Identical twins reared together86 Identical twins reared apart76 Fraternal twins reared together55 Biological siblings47 Parents and children living together40 Parents and children living apart31 Adopted children living together 0 Unrelated people living apart 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 twice87 Identical twins reared together86 Identical twins reared apart76 Fraternal twins reared together55 Biological siblings47 Parents and children living together40 Parents and children living apart31 Adopted children living together 0 Unrelated people living apart 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 Monogamous Both parents care for young Montane Nonmonogamous Mother cares for 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 Monogamous Both parents care for young Montane Nonmonogamous Mother cares for 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 More receptors Montane Nonmonogamous Mother cares for young briefly Less receptors Same levels of oxytocin and vasopressin

Voles Prairie Monogamous Both parents care for young More receptors ? Montane Nonmonogamous Mother cares for young briefly Less receptors ? Same levels of oxytocin and vasopressin Inject hormone into brain

Voles Prairie Monogamous Both parents care for young More receptors Monogamous Montane Nonmonogamous Mother cares for young briefly Less receptors Nonmonogamous Same levels of oxytocin and vasopressin Inject hormone into brain

Voles Prairie Monogamous Both parents care for young More oxytocin receptors ? Montane Nonmonogamous Mother cares for young briefly Less oxytocin receptors ? Same levels of oxytocin and vasopressin Block receptors

Voles Prairie Monogamous Both parents care for young More oxytocin receptors Nonmonogamous Montane Nonmonogamous Mother cares for young briefly Less oxytocin receptors Nonmonogamous Same levels of oxytocin and vasopressin Block receptors

Voles Prairie Monogamous Both parents care for young More oxytocin receptors Monogamous Montane Nonmonogamous Mother cares for young briefly Less oxytocin receptors Monogamous Same levels of oxytocin and vasopressin Increase levels of receptors (genetically) in ventral pallidum

Voles Prairie Monogamous Both parents care for young More receptors Montane Nonmonogamous Mother cares for young briefly Less receptors Same levels of oxytocin and vasopressin

Why might these voles use different reproductive strategies? Prairie voles Monogamous Both parents care for young Montane voles Nonmonogamous Mother cares for young briefly

Why might these voles use different reproductive strategies? Prairie voles: Resource poor habitat Monogamous Both parents care for young Montane voles: Resource rich habitat Nonmonogamous Mother cares for young briefly

Combinations of 3 nucleotides code for each 1 amino acid in a protein. We looked at the mechanisms of gene expression, now we will look at its regulation.

Exons are a very small part of DNA

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 Fig 15.1

Two points to keep in mind: 1.Cellular components are constantly turned- over. 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

Fowler and Thomashow The Plant Cell, Vol. 14, , 2002 mRNA levels change in response to cold acclimation

Fig 1b DNA damage inhibits rRNA transciption The ATM repair pathway inhibits RNA polymerase I transcription in response to chromosome breaks Nature Vol 447 pg (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