Chapter 7- Survival of the sickest, "Methyl Madness"
1. Agouti mice and vitamin supplements
- A species of mice carried an "agouti" gene, causing all of the generations to be yellow and obese.
- Scientists split these mice into two segregated groups. One group of pregnant mothers were fed a normal diet, whereas the pregnant mothers of the second group were fed vitamin supplements.
- The regular diet mothers birthed regular mice that displayed this agouti gene.
- The special diet mothers produced baby mice that were thin and brown, with no sign of the agouti gene.
- From this experiment, it was concluded that a compound in one of the vitamin supplements fed to the mother had traveled to the mother's embryo and blocked the instructions of this agouti gene.
- This type of gene repression is knows as "DNA methylation". Although the agouti gene was still present in the thin brown babies, it had been repressed because of this methylation.
1. Agouti mice and vitamin supplements
- A species of mice carried an "agouti" gene, causing all of the generations to be yellow and obese.
- Scientists split these mice into two segregated groups. One group of pregnant mothers were fed a normal diet, whereas the pregnant mothers of the second group were fed vitamin supplements.
- The regular diet mothers birthed regular mice that displayed this agouti gene.
- The special diet mothers produced baby mice that were thin and brown, with no sign of the agouti gene.
- From this experiment, it was concluded that a compound in one of the vitamin supplements fed to the mother had traveled to the mother's embryo and blocked the instructions of this agouti gene.
- This type of gene repression is knows as "DNA methylation". Although the agouti gene was still present in the thin brown babies, it had been repressed because of this methylation.
2. Smoking grandmothers and asthmatic children
-It is believed that epigenetic changes can be carried through a germ line throughout generations.
- Your mother's egg's DNA was greatly affected by your grandmother, as these eggs were produced while your mother was within your grandmother's womb.
- Your grandmother's actions affect her fetus's ovaries more than the fetus itself, therefore affecting you the greatest amount.
-It is believed that epigenetic changes can be carried through a germ line throughout generations.
- Your mother's egg's DNA was greatly affected by your grandmother, as these eggs were produced while your mother was within your grandmother's womb.
- Your grandmother's actions affect her fetus's ovaries more than the fetus itself, therefore affecting you the greatest amount.
3. Betel nut chewing and cancer
- Betel nuts are highly addictive and mildly intoxicating that commonly leads to oral cancer.
- Chewing these nuts causes the hyper-methylation of 3 cancer fighting genes; one that suppresses tumors, one that repairs damaged DNA, and one that kills lone cancer cells.
- Betel nuts are highly addictive and mildly intoxicating that commonly leads to oral cancer.
- Chewing these nuts causes the hyper-methylation of 3 cancer fighting genes; one that suppresses tumors, one that repairs damaged DNA, and one that kills lone cancer cells.
4. Lizards
- A specific species of lizards is either born with a large body and a large tail or a small body and a small tail.
- This depends on whether a mother smelled a snake or not while she was pregnant with her baby.
- If she smelled a snake, the baby would be born with a large body and a large tail. If not, the baby produced would have a small body and a small tail.
- A specific species of lizards is either born with a large body and a large tail or a small body and a small tail.
- This depends on whether a mother smelled a snake or not while she was pregnant with her baby.
- If she smelled a snake, the baby would be born with a large body and a large tail. If not, the baby produced would have a small body and a small tail.
5. The barker hypothesis
- Barker suggested there was a link between poor eating habits during pregnancy and later obesity in the child that was born.
- He summarized that the bad nutrition seen in the mother changed her baby's phenotype without altering the genotype.
- If the mother had this poor diet, the baby would then have a "thrifty" metabolism; meaning that it would hoard energy and become obese in order to require vital nutrients it's mother was missing during her pregnancy.
- Barker suggested there was a link between poor eating habits during pregnancy and later obesity in the child that was born.
- He summarized that the bad nutrition seen in the mother changed her baby's phenotype without altering the genotype.
- If the mother had this poor diet, the baby would then have a "thrifty" metabolism; meaning that it would hoard energy and become obese in order to require vital nutrients it's mother was missing during her pregnancy.
6. Childhood obesity
- Similar to the barker hypothesis, it is believed that childhood obesity is caused by poor nutrition habits belonging to the child's mother during her pregnancy.
- The baby will be born small, only to become obese in order to obtain missing nutrients.
- If a father smokes, it is likely that this will play a role in his child's health. This smoking causes an epigenetic change in his sperm and indicates that the child will be born into a harsh environment causing the same "thrifty metabolism" that would be seen if the mother had a poor pregnancy diet.
- Similar to the barker hypothesis, it is believed that childhood obesity is caused by poor nutrition habits belonging to the child's mother during her pregnancy.
- The baby will be born small, only to become obese in order to obtain missing nutrients.
- If a father smokes, it is likely that this will play a role in his child's health. This smoking causes an epigenetic change in his sperm and indicates that the child will be born into a harsh environment causing the same "thrifty metabolism" that would be seen if the mother had a poor pregnancy diet.
7. Boy or girl?
- Studies show that when a mother is immersed within a safer environment, she is more likely to have a boy instead of a girl.
- This is because girls are more likely to survive if malnourished than boys are.
- A boy fetus is more physiologically demanding that a girl fetus, and it is proven that a population that is higher in women with few strong males is more likely to survive than a male dominant population.
- This concludes why a girl is more likely to be born if a mother is in a harsh environment.