Research Paper Outline
Parental Dominance in Imprinted Genes
- Survival of the fittest struggle begins inside a fertilized egg and throughout pregnancy
- Parent’s DNA competes for gene control
- Fetal genes are imprinted with either paternal or maternal molecules.
- About 100 of the tens of thousands of genes are gender-specific but critical for survival
- Imprinting mutations can lead to illness or death of a fetus or mother.
- Azim Suranià biologist at University of Cambridge lab of Robert Edwards
- In vitro fertilization
- Parthenogenesisà healthy offspring created from an unfertilized egg
- Can occur in fish and reptiles, but no known mammals
- Studied parthenogenesis in mice.
- Two sets of genes from males or two sets of genes from females = failed attempts
- àmaternal and paternal genes each donate something crucial to offspring.
- Offspring will each try to get more resources than available from parents
- Example
- Kinship Theoryà males & females want their offspring to survive, but their reproductive strategies are different, causing them to want different things for their offspring.
- Female mammals almost always have multiple partners. Male partner will devote every possible resource to develop his offspring.
- Females want to maximize amount of offspring – each could have a different father. Females give the embryo just what it needs to have enough for other offspring.
- à
- Imprints stamped on fetus’s genes can be turned on or off, and could change how the body reads genetic code.
- Expressed genes are turned on only if inherited from a mother/father.
- Fathers encourage growth
- Mothers provide resources while in the womb. Inherited by mothers = slow the growth and allow her to conserve resources for embryo.
- Lgf2 gene produces a protein key to growth.
- Directs production of a receptor for the protein that keeps embryo growing
- In mice, they are imprinted in mother and father
- Mother = lgf2r on
- Father = lgf2 on
- The imprints cancel each other out. If one copy is taken out = effects on growth depending on which parent’s is taken out.
- Turning off mom = large offspring
- Turning off dad = dwarf offspring
- Elizabeth Robertson – Columbia University – first to identify a printed gene.
- Igf2 encouraging growth – demanding more from mom
- Take out Igf2 with moms = normal
- Take out Igf2 with dads = embryos only grew about 60% of normal size
- à competition between mom and dad. When the gene is from a father, it is necessary for growth.
- Imprinted genes can influence behavior via a number of mechanisms
- Direct effects are illustrated by SNORD 115 and MAGEL2 = key genes underlying PWS
- Imprinted genes regulate maternal supply and demand of nutrients
- Imbalance in nutrient supply caused by lgf2 leads to abnormal offspring behavior
- Imprinting genes may also be influenced by the environment; pre-natal and post-natal
Raeburn, Paul. “Genetic Battle of the Sexes”. Discovermagazine.com. 23 May 2014. Web. 29 Oct. 2014. <http://discovermagazine.com/2014/june/15-genetic-battle-of-the-sexes>
Davies, Jennifer. Dent, Claire. McNamara, Grainne. Isles, Anthony. “Behavioural Effects of Imprinted Genes”. Current Opinion in Behavioral Sciences Vol. 2. pp 28-33. Web. 4 Aug. 2014. 29 Oct. 2014. <http://www.sciencedirect.com/science/article/pii/S2352154614000102>
Dent, Claire. Isles, Anthony. “Brain-expressed imprinted genes and adult behavior: the example of Nesp and Grb10”. Mammalian Genome Vol. 25, Issue 1-2. pp 87-93. Web. 24 Aug. 2013. 29 Oct. 2014. <http://link.springer.com/article/10.1007/s00335-013-9472-0>
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