On page 160-162, Dr. Sharon Moalem
begins his discussion of animals who have the ability to produce offspring
based on the mother’s experience during pregnancy. Dr. Moalem gives four
examples- the vole, the water flea, the locust, and the lizard. In each case
the DNA is expressed differently based on what the mother senses in the
environment. For the vole in particular, the mother is able to give birth to a
baby either with a thick coat or a thin coat. In a way, this mother vole is
able to determine if the baby will need to a thick coat for the winter or a
thin coat if the environment is relatively hot. Scientists have labeled the
mother’s experience to influence gene expression as a predictive adaptive
response or maternal effect.
Explain how it is possible for the
mother vole to produce a thick coat or a thin coat for a baby- include “turn
on”, “turn off”, DNA in your explanation and discuss the epigenetics involved
in this process. Give one more example of an animal that is able to determine
what the phenotype the child will have because of the environment and explain
how it relates to the vole. Include the implications that this would have on
humans, and decide if it is possible. Discuss the validity of child obesity
being an example of maternal effect through sources such as Dr. Moalem and
outside sources. Finally, relate it to big idea 1, and explain how this process
drives the diversity of life and explain how it can be a selective advantage while
discussing the implications of the overall population. (Provide Examples from
multiple sources.)
Rahul Kosgi (rkosgi4@students.d125.org)
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ReplyDeleteThe mother vole is able to perform this phenomenon by sensing the level of light in her environment during the time of conception. According to Dr. Moalem, the gene for the thick coat is always present, but based on the environment type the gene can be either turned on or off depending on the level of light. The DNA of the vole may not be transcribed to produce a thick coat after the gene is turned off. In this process, the DNA is not changed; only the phenotype is not expressed because the gene is not turned on. There is something to block the RNA polymerase 2 from transcribing the genes to mRNA from the DNA, and thus the thick coat may or may not be produced based on the amount of light. If there is a lot of light, and the mother detects that, there may be an excess of some protein in the body and that blocks the promoter and the RNA polymerase 2 cannot transcribe.
ReplyDeleteThe sheep is another example of the predictive adaptive response. Maternal obesity results in altered growth rates, adiposity, and glucose tolerance in the ewes that are born. The phenotypes of the baby sheep would be taller, bigger sheep that are a result of the obesity of the mother during childbirth. The results are similar to the vole as the obesity is only a problem during conception for the sheep, as the amount of light is only a problem during conception for the vole as well.(http://www.hindawi.com/journals/jdr/2011/592408/)
The junk food that a mother eat during pregnancy can result in a smaller child as the food with very low notional value signals that there will be a harsh atmosphere outside with little food, thus making the baby very small. So a mutation is possible for humans as well based on the outside condition during pregnancy. Also, according to the maternal and fetal health department of St. Thomas’s hospital, there is evidence to show that the fetus is likely to have cardiovascular problems because of the mother’s poor nutritional during childbirth. This implies that obesity and other problems are possible because of the eating habits of a mother during childbirth.(http://jp.physoc.org/content/565/1/3.full.pdf)
In the human species, the result of this predictive adaptive response brings out unhealthy offspring because of the eating conditions of the mother. However, in the animals that Dr.Moalem describes, the thick coat would be a selective advantage for the offspring because it suits the environment that the animal is living in. This relates to Big Idea 1 as this is an example of how the process of evolution, involving the predictive adaptive response, brings about diversity of life. Because of this type of response, different types of offspring are produced resulting in diversity of life. Because the mother is able to turn the gene on or off, the offspring can survive in the environment it is born in-making it a selective advantage. The operon being able to turn on and off relates to Big Idea 3 as well as organism detect external signals to produce a response according to the environment it lives in. The living system retrieves information from outside( Big Idea 3) and acts according to it, by turning the gene off and producing a thick or think coat accordingly.
Pranathi Merneedi (pmernee4@students.d125.org)