Midterm 1 Flashcards
The Barker hypothesis posits that bad genes are responsible for chronic disease (T/F).
False! Unhealthy womb environment, as well.
What did the Hertfordshire Cohort Study show?
1980’s study in England and Wales found a correlation between rates of heart disease and infant mortality. A U-shaped graph for birth weight vs. mortality from CHD. Fetal death rates went along with CHD mortality rates in the area.
What did the Helsinki Birth Cohort study show?
Adults with CHD tended to have poor growth from infancy to age 2, then a sharp weight increase (postnatal catch-up) from ages 8-10.
The Dutch Hunger Winter showed which effects at early, mid, and late exposure to famine?
Early: 3x higher risk of CHD + obesity in women.
Mid: Light birthweight + obstructive airway diseases in adulthood.
Late: Light birthweight + impaired glucose tolerance in adulthood.
LBW is like a _________ of fetal adaptation to adverse prenatal environment.
surrogate marker
How does inappropriate stimulus / incorrect developmental window affect disease risk?
Raises it such that the risk is higher earlier in life.
Developmental plasticity is the ability of an organism to develop in various ways depending on _____.
the particular environment or setting
The reaction norm is the range of _______ that can be induced in a given environment.
phenotypes
What are the three characteristics of developmental plasticity?
- The response is somewhat dependent on environmental cues.
- There are critical windows for systems’ plasticity where they’re more vulnerable to change.
- The duration is time-limited to organogenesis.
How does developmental programming operate within the context of plasticity?
A stimulus or insult applied at a critical period of development will have lasting effects on the structure/function of the body leading to higher risk of disease later in life.
Differentiate between the Developmental Constraints Model and Predictive Adaptive Response Model.
DCM is that organisms adjust their phenotype during development to avoid immediate death.
PAR is that organisms adjust their phenotype based on developmental cues to optimize later performance, but can lead to disease when the predicted environment is incorrect.
The Thrifty Phenotype Hypothesis is an example of which model?
Both?
What are two examples of evolutionary and developmental mismatch?
Evolutionary: IVF and formula diet.
Developmental: Unbalanced maternal diet, placental disease.
What is the Thrifty Genotype?
Repeated famine exposure has led to positive selection for efficient energy storage genes now leading to higher obesity rates. Evolutionary mismatch.
What is the Thrifty Phenotype?
Fetal reallocation of energy stores towards brain development, altering other development and creating insulin resistance. Developmental Mismatch.
What are examples of some stressors that can act as a “second hit” for pathogenesis?
Nutrition, disease, infection, and toxicant exposure.
Epigenetic marks control the expression of genes that function in ________.
embryonic development
Name 4 types of epigenetic programming.
Methylation marks, Genetic imprinting, X-inactivation, and somatic cell differentiation
Which genome undergoes rapid demethylation and histone modification right after fertilization?
The paternal.
How is the maternal genome marked following fertilization?
Gradual demethylation, eventually a new wave of embryonic methylation that establishes blueprint for developing tissues.
Imprinted genes are genes whose expression is determined by _______.
the parent that contributed them, contrary to normal rules of equal inheritance
Why are there lots of epigenetic defects in the majority of cloned embryos?
Inefficient reprogramming of the somatic cell to the epigenetic state of the embryonic nucleus for which it’s substituting.
Name 3 methyl-donating nutrients that can rapidly alter gene expression in early development.
Folic Acid, B vitamins, and SAM-e methionine
How does caloric restriction impact the Insulin/GF1 and DNA methylation pathways?
Lowers insulin resistance and causes hypo/hypermethylation of tumor suppressor and p16 genes to decrease incidence of disease.
How is epigenetic damage different from genetic damage?
Epigenetic patterns can be reversed.
Describe Fragile X Syndrome.
Too many CGG repeats in the FMR1 gene (200 vs. 6-50) methylate the gene. CpG island at the promoter turns the gene off. Associated with mental developmental conditions.
How are epigenetics associated with the immune response?
Shifts in both acetylation and methylation are needed to permit recombination for the immune response. Too much folic supplementation can lead to a loss of epigenetic control here —> autoimmune disease.
Desribe Systemic lupus erythematosus through the lens of epigenetics.
SLE has autoantibodies against nuclear antigens affecting all organs and tissues. Immune cells are hypomethylated, dysregulation of T-lymphocytes.
What modifications does RA involve?
Rheumatoid arthritis can have altered methylation status in T and B cells as well as synovial fibroblasts. Global hypomethylation.
How can dietary supplements aid in age-related neurological disorders?
Methyl donors can help restore cognitive performance for diseases in which genes develop gradual methylation. Like sequestration of synuclein protein into Lewy bodies in Parkinson’s.
What is the regulatory role of sirtuins?
They regulate fat and glucose metabolism through histone and transcriptional deacetylation in many cellular areas. Energy homeostasis, healthspan determination,
Name the 3 families of epigenetic proteins.
Readers, writers, and erasers
How can DNA methylation increase cancer risk?
Hypomethylation can activate oncogenes and initiate chromosome instability, hypermethylation initiates silencing of tumor suppressor genes.
Physical exercise modifies DNA methylation patterns in favor of _____.
tumor suppressor genes + decreases oncogene expression
Genes of colorectal cancer cells were substantially _____ in comparison with normal tissues.
hypomethylated
Fragile X syndrome is an example of which type of epigenetic modification?
Histone modification
Drugs exist targeting epigenetic ____ as well as analogues of epigenetic modifications for clinical use.
enzymes
The modification of histones can induce _______ leading to the introduction of _____.
epigenetic changes; non-coding RNAs
Describe the Histone Code Hypothesis.
Chromatin activity depends on the degree of chemical modification of histone tails
DNA demethylation is an active process (T/F).
False, can be active/passive or a combination of both.
Where are the majority of methylated cytosines in mammals?
Symmetrical dinucleotide 5’CPG3’. 70-90% of CpG dinucleotides are methylated. Islands, near promoters, have methylation variability.
How does methylation change gene expression?
Methylation of promoters and enhancers prevents RNA polymerase from binding.
What pathway does DNA methylation use?
One-carbon metabolism, dependent on several enzymes/cofactors like folate, choline, and betaine.
DNMT1 maintains DNA methylation patterns through division while DNMT3a/b establishes new patterns during development (T/F).
True
What do long non-coding RNA do?
Sequence specific molecules that guide protein complexes to sites in chromatin to orchestrate transcriptional repression.
What are circRNAs?
Covalently closed ncRNAs that are major regulators for pathogenesis. They can sponge microRNAs, bind proteins, or be translated themselves.
What are the most crucial stages for epigenetic reprogramming?
Pre-implantation (De-methylation, X inactivation, Tissue-specific implementation)
Gametogenesis (De-methylation, X activation, Imprinting)
A true transgenerational effect can only be proved of the effect of the exposure is transmitted ____.
to F3 on the maternal line when exposure occurs during pregnancy; F2 on either line if exposure was before conception
Ontogenesis runs from conception to ____.
old age
A term gestational period is ___-___ weeks.
37;42
At ~5 days following feritlizaton, what happens?
Morula (highly replicated zygote) becomes a blastocyst which will then implant in the uterus.
What is the cortical reaction?
When sperm penetration causes zona pellucida to become impermeable to other sperm.
How many chromosomes are in a zygote + cells in a morula?
46 and 16!
The blastocyst will go on to form the ______ and _____ which make up the embryo and placenta, respectively.
inner cell mass; trophectoderm
Pregnancy can be clinically detected at the _____ stage with presence of the _____ hormone.
implantation; hCG in the corpus luteum
Following implantation, in _____, the embryonic disk differentiates into the ectoderm, mesoderm, and ______.
gastrulation; endoderm
The ectoderm forms the nervous system and epithelium while the endoderm forms connective tissue (T/F).
False, endoderm forms GI organs and GI/respiratory epithelium.
When is the embryo most sensitive to environmental factors?
Organogenesis, weeks 4-8.
What differs parturition from labor?
Parturition is a set of sequential hormonal (progesterone) and physical changes in preparation of labor, which involves contractions and dilation.
What are the four stages of parturition?
Quiescence (progesterone, relaxin), Activation (Estrogen, Uterine stretch), Stimulation (Prostaglandins, oxytocin, cytokines for dilation), and Involution (Oxytocin, recovery).
Progesterone withdrawal —> _____ bioavailability —> responsiveness to ______ —> ____ —-> Uterine stretch
estrogen; prostaglandin/oxytocin; CRH
Which hormone maintains quiescence?
Progesterone
Which hormone promotes myometrial changes like receptor sensitization and cervical ripening?
Estrogen
Which parturition hormone can be activated by stress?
CRH
Symmetrical FGR makes up 25% of cases with late onset and 25% risk for chromosomal abnormalities and neurological sequelae (T/F).
False, onset prior to 32 weeks.
Asymmetrical FGR is _______.
brain-sparing
What is the leading cause of fetal and maternal morbidity around the world?
Preeclampsia
Proteinuria, edema and abnormal liver function (HELLP) are all signs of what?
Preeclammpsia
Name two common cooccurrences of preeclampsia?
Pre-term birth and fetal growth restriction
Leptin inhibits _____.
insulin
How does the placenta’s structure support its function?
Large SA and thin intrahaemal membrane separating circulations.
The maternal surface of the placenta is 15-20 _____. The fetal is a ______ covered by amniotic membrane and vessels converging towards the _____.
cotelydons; chorionic plate; umbilical cord