help me do this task

Instructions: Respond to the following questions by circling or bolding the text of the correct

answers. You are allowed to use your book, your notes, and your classmates as sources to answer

any question.

1. Researchers were interested in determining the relationship between social

class, DNA methylation patterns, and biological markers of cardiovascular disease. Using a large pool of research subjects (i.e. people),the researchers analyzed the amount of methylation across each individual’s entire genome and also categorized each individual by age group (35-44, 45-54, or 55-64 years old) and by their “Deprivation group” (“Affluent” or “Deprived”).Results are displayed in

Figure 2.

Figure 2. Total DNA methylation as a percent of the entire genome across three

age groups and two deprivation groups. In each category, a horizontal line

indicates mean DNA methylation percentage; filled circles indicate individual

data points. From McGuinness et al. 2012 International Journal of Epidemiology

Which of the following is/are justifiable conclusions that can be drawn from this data? (Multiple

answers may be correct, select all that are correct.)

i. Status as affluent or deprived appears to be caused by differences in the methylation of DNA

ii. For both deprivation groups (affluent and deprived) there is a trend of increased methylation with increasing age across all three age groups

iii. Individuals in the deprived category exhibit decreased methylation compared to affluent individuals, when compared within each age group

iv. There is a significant effect of “deprivation group” on the percent of DNA

methylation

v. There is a significant effect of “age group” on the percent of DNA methylation

vi. The quantity of DNA methylation present in an individual’s genome appears to be directly correlated with increasing socio-economic status (i.e. affluent).

vii. Deprived individuals likely have fewer genes silenced by DNA methylation than affluent individuals

viii. Older individuals likely have fewer genes silenced by DNA methylation than younger individuals.

ix. DNA methylation is silencing genes associated with stress in affluent individuals, but not silencing those genes in deprived individuals

x. There is not enough information provided to make a justifiable conclusion.

2. A study conducted by Begum et al. 2013, investigated if DNA methylation of CpG (Cytosine-Guanine) sites in the genome of adolescents, was affected by maternal/paternal stress between

infancy and the preschool years. The “promoter region of CpG Sites” refers to a region of DNA responsible for controlling the expression of genes (going from DNAaRNA). “Methylation of CpG Sites” refers to regions of the DNA that are not responsible for controlling the expression of genes (these regions are genes, DNA). “Maternal-All” and “Paternal All” included all the data from boys and girls in either “infancy” or “preschool”. The boxes on Figure 1., include a

reference of boxes (in dark, medium, and light shade) that refer to the percentage of methylated

CpG sites found in each sample, which is seen on the x-axis of Figure 1.

Which choice below would be the best explanation of the results from Figure 1 of this study?

i. There are greater CpG sites methylated due to maternal adversity in boys during infancy, while CpG sites are methylated less during paternal adversity in girls during preschool.

ii. Paternal and maternal stress caused methylation of CpG sites in boys and girls.

iii. CpG sites are methylated less often during infancy and more often during preschool.

iv. CpG sites are methylated more in boys, due to maternal adversity during infancy.

v. There was a greater percentage of methylation of CpG sites

vi. CpG sites are methylated less in girls, due to paternal adversity during infancy.

vii. Greater than 5% of methylation occurred in girls during maternal stress.

viii. Paternal stress led to a greater percentage of overall methylation of CpG sites in girls when compared to the percentage of methylated CpG sites due to paternal stress in boys.

3. The hypothalamus is a region of the brain where cortisol is produced and released. Cortisol (a type of glucocorticoid) is a hormone released during times of stress in most vertebrate animals like humans and mice. To deal with cortisol, a glucocorticoid receptor (GR), which is a type of protein, binds to cortisol. The interaction of cortisol and GR in the hypothalamus ultimately helps humans and mice to have less anxiety. Figure 2., represents a study that focused on the expression of the GR protein in response to undernourishment. Figure 2. Altered epigenetic expression of hippocampal GR protein. i and j, GR protein intensity

in the hippocampus. α tubulin (positive control). Nourished (C), and Undernourished (U).

Figure 2. Altered epigenetic expression of hippocampal GR protein. i and j, GR protein intensity

in the hippocampus. α tubulin (positive control). Nourished (C), and Undernourished (U).

Which option below best explains Figure 2 of this study?

i. Males produce less of the GR protein than females.

ii. Females produce less of the GR protein when undernourished compared to males who are undernourished.

iii. Males and females produce less of the GR protein when undernourished.

iv. Males and females under a normal diet produce equal amounts of the GR protein.

v. Males and females produce the GR protein when nourished and undernourished.

vi. Females and males produce the GR protein when nourished.

4. Explore the website ttp://learn.genetics.utah.edu/content/epigenetics/rats/ and learn about the effect of mother rats licking their pups on the expression of GR protein and pup behavior.

Researchers wanted to determine if the epigenetic modification (i.e. methylation) of the GR gene was inherited as an imprinted epigenetic modification (e.g. inherited from mom due to her traits; due to nature), or environmentally determined after birth due to differences in a mother rat’s attentiveness (i.e. nurture). They performed a cross-fostering experiment where pups born to one “type” of mother were raised by that same “type” of

mother or the opposite “type” of mother. The treatment identification codes are displayed in Table 1.

Following rearing, rat pups were allowed to reach

adulthood and then the GR gene DNA was tested for

methylation. Data are shown in Figure 3.

Table 1. Treatment identification codes for rats born of one “type” of mother but raised by another “type” of mother.
Pups born to	Pups raised by	Treatment code
Low-licking mother	Low-licking mother	L-L
High-licking mother	High-licking mother	H-H
High-licking mother	Low-licking mother	H-L
Low-licking mother	High-licking mother	L-H

Figure 3. Mean percent (± s.e.m.) of GR gene DNA that was methylated after a cross-fostering experiment with rats. From Weaver et al. 2004 Nature Neuroscience.

a. Which of the following is/are justifiable conclusions

based on the data in Figure 3? (Multiple answers

may be correct, select all that are correct.)

i. Rats born to low-licking mothers exhibit high levels of methylation regardless of which mother raised them.

ii. Rats born to high-licking mothers exhibit high levels of methylation regardless of which mothers raised them.

iii. Rats born to high-licking mothers exhibit low levels of methylation regardless of which mothers raised them.

iv. Rats raised by low-licking mothers exhibit high levels of methylation regardless of birth mother.

v. Rats raised by high-licking mothers exhibit high levels of methylation regardless of birth mother.

vi. Rats raised by high-licking mothers exhibit low levels of methylation regardless of birth mother.

vii. Epigenetic modification of the GR gene is primarily an inherited trait (i.e. nature)

viii. Epigenetic modification of the GR gene is primarily an environmentally determined trait (i.e. nurture)

Conclusions considering our understanding of how GR gene methylation affects rat behavior…

ix. Rats that are born to low-licking mothers are likely to behave more anxiously than rats born to high-licking mothers.

x. Rats that are raised by low-licking mothers are likely to behave more anxiously than rats raised to high-licking mothers.

xi. Rats that are born to high-licking mothers are likely to behave less anxiously than rats born to low-licking mothers.