Macquarie University Psy2235 Week 2 Prenatal Development PDF

PSYU2235 / PSYX2235 Developmental Psychology PRENATAL DEVELOPMENT, GENES, AND ENVIRONMENT WEEK 2 DR JOSEPHINE PAPARO [email protected] THIS WEEK… Part 1 o Genetics ─ Genes, Heredity, Behavioural Genetics and Epigenetics Part 2 o Prenatal Development ─ Early Deve...

PSYU2235 / PSYX2235 Developmental Psychology PRENATAL DEVELOPMENT, GENES, AND ENVIRONMENT WEEK 2 DR JOSEPHINE PAPARO [email protected] THIS WEEK… Part 1 o Genetics ─ Genes, Heredity, Behavioural Genetics and Epigenetics Part 2 o Prenatal Development ─ Early Development in the Womb ─ Risks to Development o Teratogens o Prenatal stress 2 For anyone whom the content of this lecture may be personally impactful… https://www.pinkelephants.org.au/ https://rednose.org.au/ https://www.bearsofhope.org.au/ https://www.pregnancylossaustralia.org.au/ https://www.sands.org.au/ https://stillbirthfoundation.org.au/ https://www.panda.org.au/ MQ Wellbeing Service 3  PART 1: GENETICS Genes, Heredity, Behavioural Genetics and Epigenetics Part 1: Aims & Learning Outcomes Students should have an understanding of: 1. Basic* workings of individual heredity 2. Relative contributions of genes & environments & how they can work together 3. How genetic & environmental influences are studied 4. Gene-environment “correlations” (*disclaimer) 5 GENETICS: THE BASICS 6 Individual Differences: Genes & Environment Why do people differ? Why are some so alike? (Body language, posture etc) Why are some people… Smarter? Heavier? More sporty? More musically talented? More anxious? Shy? Nature (genes) o Genetic determinism vs. genes as influences, predispositions, tendencies, etc. Nurture (environment, experience) 7 Historical Background Ancient Greeks –“likeness” transmitted parents to children – Pythagoras - via male semen? Aristotle – women also involved Mendel – peas (1822-1844) – bred hybrids - discovered “ a basic unit of heredity forgotten until Darwin – Genetic variation in a species was adaptive – theory of natural selection (1859) Watson & Crick DNA double helix (1951-1953), more recent recognition of contributions of Wilkins & Franklin Behavioural Genetics: (Turkheimer & Gottesman, 1991) o contributions of nature and nurture to human and animal behaviour and behavioural diversity Epigenetics (Gottlieb) – changes in gene expression due to base pairs in DNA being turned off or turned on in response to environment Post-genomics – gene therapies; gene editing 8 What are Genes? Genes are units of hereditary information — ”blueprint” for a structure or the “recipe” for encoding a process o “Genome”: An algorithm or code DNA is in genes o Genes are comprised of short segments of DNA (deoxyribonucleic acid) Genes are on chromosomes - these are structures within cells that contain a person’s genes o 46 chromosomes (23 pairs = 22 pairs of autosomes + 1 pair of sex chromosomes XX or XY) o Genes (in pairs, one from each parent) are carried on the 46 chromosomes Molecular Biology 9 Mitosis and Meiosis Source: https://www.youtube.com/watch? 10 v=Ba9LXKH2ztU&t=3s Simple summary – Reproduction & Individual Heredity Mitosis – normal cell replication for somatic reproduction (skin, blood, muscles) Single cell divides and replicates resulting in 2 identical cells Each cell contains two sets of chromosomes Growth, repair of Copyright © 2012 Pearson Australia (a division of Pearson aging tissues, Australia Group Pty Ltd) – 9781442550094/White, Livesey, Hayes/Developmental Psychology/3e 11 Simple summary – Reproduction & Individual Heredity Meiosis – special process of cell division for sexual reproduction. Fundamental to formation of sperm (males) ova (females) 1st division sequence similar to mitosis A 2nd division sequence producing 4 cells, each with ½ number of chromosomes of original cell Fertilisation occurs when sperm and ova come together Each sex cell has 23 chromosomes (“haploid") At fertilization, chromosome pairs come together and the fertilized cell (zygote) returns to having the usual 23 ”pairs” of chromosomes (i.e. 46 chromosomes; 2 of each, called “diploid”) Crossing over occurs and there is the mixing 12 genetic information from chromosomes of the Copyright © 2012 Pearson Australia (a division of Pearson Australia Group Pty Ltd) – 9781442550094/White, Livesey, Hayes/Developmental Psychology/3e 13 Simple summary – Reproduction & Individual Heredity Mutations—”errors” in the process of meiosis or mitosis mean that chromosomal mutations or abnormalities can occur (~1/200 foetuses) E.g., Inversions, deletions, duplications, translocations Down Syndrome Trisomy 21 Turner Syndrome (XO) Klinefelter Syndrome (XXY) Chromosomal abnormalities are the main cause of spontaneous miscarriage 14 Basic Genetic Principles Dominant-recessive gene principle (the case of single gene-pair inheritance—Mendel) o There are 2 hereditary elements for each trait ─ 1 from the male parent ─ 1 from the female parent o These 2 alternate forms of the same gene are called “ALLELES” o One dominant allele can override the effect of the other recessive allele o Recessive genes are only expressed if both parents carry the recessive gene ie., there are 2 recessive genes 15 Dominant-Recessive Gene Principle: (Simple Case of Eye Colour) Gene for brown eyes (B) is dominant over the gene for blue eyes (b) Genotype— genetic constitution Possible outcomes are BB, Bb, bB, bb, bb E.g., parents Bb, Bb  BB, Bb, bB, bb Phenotype—observable characteristic – eye colour BB = brown eyes (homozygous) bb = blue eyes (homozygous) Bb = brown eyes (heterozygous) bB = brown eyes (heterozygous) 16 Polygenic inheritance* In most cases, many genes interact to produce a particular characteristic Human Genome Project—humans have 30,000 genes Reaction range — a range of possible phenotypes for each genotype Genetic potential for high IQ o Restricted environment IQ = 80 o Enriched environment IQ = 150 Genetic potential for average IQ o Restricted environment IQ = 50 o Enriched environment IQ = 108 17 Genetic Disorders: Dominant- Recessive Relationships Some disorders are carried on dominant gene - expressed in every individual carrying the allele eg., Huntington’s disease – which strikes after 40 yrs – 1 in 2 chance of inheritance Some disorders are carried on recessive gene e.g., Cystic Fibrosis; both parents have to carry the gene – there is a 1 in 4 chance of inheritance – (similar to eye colour example) For some traits there is co-dominance - effect of recessive gene is not totally masked, so phenotype is a combination E.g., Skin colour (black + white = light brown), sickle cell anemia 18  Genetic Disorders: Sex-Linked Inheritance Some traits are influenced by single genes that are located on the sex chromosomes o Typically “X-linked” (recessive) ─ These traits are expressed in males: Why? Red-green colour blindness Haemophilia Certain forms of deafness Duchenne Muscular Dystrophy 19 Prenatal Diagnosis and Genetic Counselling Some genetic & structural anomalies can be detected early in pregnancy Ultrasound – routine Maternal serum blood tests Chorionic villus sampling Nuchal translucency ultrasound scan o Fluid at back of neck (11-13 weeks) o Relative risk only 20 Prenatal Diagnosis and Genetic Counselling Pre- Implantation Genetic Diagnosis www.genetics.com.au 21 Prenatal Diagnosis and Genetic Counselling Purpose Not to produce perfect humans – although many ways in which technology can be applied Allow early treatment as appropriate Facilitate informed decision making Facilitate planning for a child with a health problem 22  METHODS FOR STUDYING GENE X ENVIRONMENT INTERACTIONS 23  Studying Gene-Environment contributions: Methods Research methods used with animals & with plants and crops can’t be used with humans Experimental breeding - Animal models Selective breeding for heritable traits (e.g., activity level, wool type, “maze bright”), selectively mate animals exhibiting that trait, “eugenics” Genetic manipulation/editing - insert a particular variant of a normal gene in cells or “knockout” a normal gene - compare these experimental animals with control animals to determine the function of the manipulated genes (Wehner & Balogh, 2003) Human developmental psychobiology is more ethically & morally challenging! 24 Behavioural Genetics: The Study of Gene-Environment Contributions in Humans 1) Kinship Studies 2) Twin Studies 3) Adoption Studies 25 Estimating Genetic & Environmental Influences KINSHIP STUDIES Compare relatives vs. unrelated people % of genes shared (avg) Identical twins 100% 1st degree relatives 50% (Parents and children, siblings, fraternal twins) 2nd degree relatives (half-siblings) 25% 3rd degree relatives (cousins) 12.5% 26 Estimating Genetic & Environmental Influences KINSHIP STUDIES Approximate Familial %Risk/Odds of Schizophrenia/ Bipolar Disorder (from NSW Health www.genetics.edu.au) Affected relative Sch Bipolar General population 1 2-3 Identical twin 45 70 Both parents 45 50 1 parent 13 15 Siblings 9 13 2nd degree relatives (aunt, grandparent) 3 5 3rd degree relatives (1st cousin) 1-2 2-3 27 Estimating Genetic & Environmental Influences TWIN STUDIES Comparing identical twins (Monozygotic - MZ) and fraternal twins (Dizygotic - DZ) MZ share 100% of genes DZ share 50% of genes (like siblings) For traits influenced by Source: https://gfycat.com/gifs/search/twins+danny+devito heredity, MZ twins will be more similar than DZ twins  E.g. For height, MZ 28 29 Estimating Genetic & Environmental Influences TWIN STUDIES Methodologies Same Environment: In what ways are identical twins more similar than fraternal twins? Different Environment: Identical twins separated near birth particularly informative 30  Estimating Genetic & Environmental Influences TWIN STUDIES Thinking Critically About Twin Studies* What could explain the lack of a perfect correlation for identical twins? What factors other than genes could explain similarities between identical twins? Do all children in the same family have the same environment? Is the family environment more similar for twins? What early factors might mean there are different environments for 31 monozygotic (identical) twins? Estimating Genetic & Environmental Influences TWIN STUDIES Limitations of Twin “Designs”* A natural experiment, but…... Can’t systematically vary the environment Can’t randomly allocate to different environments Can’t remove one twin experimentally Assumption that the diversifying influences of environment are no greater for fraternal than identical twins Role of Parents Parents who think twins are monozygotic may be more likely to treat them more similarly and expect the same from each twin because they look the same, compared with dizygotic twins – would interesting if this could be manipulated! 32 Estimating Genetic & Environmental Influences ADOPTION STUDIES Shared heredity - genetically related individuals separated and reared in different environments – how similar are they? What does this tell us? Shared environment - genetically unrelated individuals reared in the same environment New Interesting Case: Donor sperm/eggs/embryos 33 Estimating Genetic & Environmental Influences ADOPTION STUDIES Thinking Critically About Adoption Studies* Issue of non-random “selective placement” confounds interpretation Adoption research relies on pre-existing social practices o Bias in placement with “similar” parents o Meeting criteria for eligibility- screening o “Wanted” children adds value to environment? Disclosure Knowledge – sibling contrast effect Timing of disclosure/emotional aspects Donor sperm/egg/embryos 34  GENE X ENVIRONMENT INTERACTIONS: “LEVEL UPPING” WITH EPIGENETICS 35 Epigenetics Heredity and environment are not independent influences…… Changes in phenotype (appearance) or gene expression can be caused by mechanisms other than changes in the underlying DNA sequence - instead, non-genetic factors can cause the organism's genes to behave or express themselves differently … In other words, environmental events “turn genes on” or “turn genes off” 36 An Example… Gene Environment Interactions – Vulnerability to Depression (Caspi et al., 2003) 0.5 0.45 0.4 0.35 0.3 2 high risk genes 0.25 1 high risk 1 prot 0.2 2 protective genes 0.15 0.1 0.05 0 0 1 2 3 4+ stressful life events 37 Timing of Genetic Influences Genes do not complete their work before birth… they provide potentials o Turn on and turn off in patterned ways throughout lifespan Important question not: How much is explained by genes vs environment? Rather: How do heredity and environment work together? E.g., Which environmental factors cause genes to turn on? 38 Gene-Environment Correlations (Scarr & McCartney, 1983) 1. Passive—child passively receives correlated genes and environment Eg. musical parents provide both genes & a musical environment 2. Evocative—child elicits reactions from parents that lead them to provide environments correlated with the child’s genes Eg. parents notice musical ability in child and respond by providing input to foster that ability 39 Gene-Environment Correlations (Scarr & McCartney, 1983) 3. Active (niche-picking)—child’s genes lead him/her to actively seek out correlated environmental experiences Eg. musical child seeks to go to conservatorium for high school, goes to musicals on weekends, saves money for music lessons 40 PART 2: PRENATAL DEVELOPMENT The First Environment Part 2: Aims & Learning Outcomes Students should be able to: Understand pre-conception factors that may influence the developing fetus Describe the development of the fetus during pregnancy Describe the principles governing the effects of environmental factors that may harm the developing fetus Discuss the impact of prenatal stress on the growing fetus and implications for early development 42  BEFORE CONCEPTION 43 Pre-Pregnancy Environmental Risks: Factors influencing sperm/egg Factors associated with the physical well-being of the mother or father Maternal chronic illness (diabetes, high blood pressure, obesity) History of drug use or toxin exposure in either parent Inadequate nutrition in childhood or adolescence Previous numerous closely spaced pregnancies Family genetic history Mutations during gamete formation Age of mother or father at time of conception 44 Pre-Pregnancy Environmental Risks: Factors influencing sperm/egg Factors associated with the physical well-being of the mother or father Maternal chronic illness (diabetes, high blood pressure, obesity) History of drug use or toxin exposure in either parent Inadequate nutrition in childhood or adolescence Previous numerous closely spaced pregnancies Family genetic history Mutations during gamete formation Age of mother or father at time of conception 45 CONCEPTION AND PRENATAL DEVELOPMENT 46 Phases of Prenatal Development: Scale of Physical Development 47 Phases of Prenatal Development: The Emergence of Behaviour Thumb sucking may be present from 12 weeks By 14 weeks fetus can swallow and digest amniotic fluid, urinate, move fingers Kicking also present – mother feels about 18-20 weeks By 24 weeks fetus can hear sounds*, open & close eyes By 28 weeks daily circadian rhythms established *Fetal habituation research – 48 prenatal learning During Pregnancy Risks: Exposure to Teratogens Teratogen—any agent that causes a birth defect Environmental hazards o Radiation o Pollutants o Agent orange Prescribed/Illicit Drugs & Other Substances o Medications* o Illicit drugs o Tobacco o Alcohol Source: https://twitter.com/NOFASDAustralia/status/1473763037198 929925 Maternal disease factors *Challenges – e.g., necessary o Rubella (German measles) medications for severe anxiety, depression, psychosis, epilepsy 49 o Toxoplasmosis During Pregnancy Risks: Exposure to Teratogens Impact depends on Dosage & duration Genetic make-up of unborn child & mother Environment – other aspects Timing – critical periods in organogenesis 50 Phases of Prenatal Development: Three Phases Teratogens Germinal period – Conception (mid cycle, rarely have an egg meets sperm) influence in first zygote > blastocyst (mitosis) 2 weeks Implantation occurs around day 6 after fertilisation *Many unaware pregnant Embryonic period – Implantation  8 weeks Time of Most rapid period of development; maximum groundwork for all body structures and susceptibility to internal systems is laid down – teratogens. Gross structural organogenesis anomalies o Amnion typically result o Chorion o Placenta – placental barrier o Brain (3-4 wks); Heart beat (4 wks) General impact o Eyes, nose, ears, mouth 2nd month of teratogens is o Sexual differentiation less. 51 51 52 During Pregnancy Risks: Prenatal Stress Decreased blood flow to uterus  impacts fetal growth Maternal stimulant hormones  increase fetal heart rate and activity level, infant’s developing HPA axis NOTE: Clusters of risk - anxious women more likely to engage in other behaviours that impacts fetal development (e.g., smoking, drinking, eating poorly, etc.) 53 ***Barker Hypothesis Barker Hypothesis (Lancet, 1986) Adult disease is linked to prenatal exposures (e.g., obesity, cardiovascular disease, diabetes) Fetal Origins of Adult Disease Model (FOAD) and concept of “fetal programming”54 Fetal Programming of Prenatal Stress Animal studies: Fetal Programming Extensive literature Controlled laboratory conditions o Ethical constraints in humans Prenatal stress associated with: o Heightened fear & anxiety o Reduced exploration & play o Social withdrawal o Elevated corticosterone levels Mediating role of the HPA axis 55 Extending the Fetal Origins of Adult Disease Model (FOAD) to Early Developmental Influences PRENATAL POSTNATAL Maternalpsychological Maternal psychological Maternalpsychological Maternal psychological state state state state Maternalcaregiving Maternal caregiving genes MaternalHPA HPAaxis axis Infantstress Infant stressreactivity reactivity Maternal &&regulation regulation 56 What Can We do? Example – Michael Meaney’s work with stress and rats Rats exposed to prenatal stress whose mothers lick them more often are calmer than rats that are not licked enough. o Caretaking quality can offset effects of prenatal stress exposure!!! *POSSIBLE EPIGENETIC IMPLICATIONS? 57 Just to Balance the Story… Potential to Enhance the Prenatal Environment Talking to/thinking about unborn baby o Ultrasound may help Health Promoting Behaviours o Mother’s diet, relaxation, health Avoiding potentially harmful environments Music? Concept of fetal attachment o Establishing a relationship with the fetus – behaviours that may follow from that 58 Summing Up Basic understanding of principles of genetics Dominant and recessive inheritance How genetic and environmental factors act together to determine phenotypes (gene expression) How psychologists study these influences – o Twins, adoption, kinship – strengths and limitations of these “methodologies” Stages of prenatal development and threats/risks to development at this time 59  THANK YOU  See you next week for… From Birth to Early Infant Motor and Perceptual Development 60