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To find out more about the importance of the maternal environment on offspring, John Watt visits Dr Christine Jasoni, University of Otago. Christine explains her research into the influence of maternal environment on foetal brain development and the susceptibility of the offspring of obese or diabetic mothers to be obese or diabetic.

Key content

Key content

Genes and maternal health

Can our genes be influenced by the maternal environment while we’re still in the womb? Dr Christine Jasoni, University of Otago, thinks they can. She takes John on a tour of her lab and explains how the health of a mother can ultimately affect the circuitry of their unborn baby’s brain. She explains to John that, for example, obese or diabetic mothers may change the gene expression of their offspring in the womb. This may alter the way in which the foetal brain is wired, which then influences the child’s susceptibility to diabetes or obesity once they’re born.

Christine uses rodents to explore her hypothesis. After feeding them specific diets, thin brain slices are examined to visualise the proteins and look at the connections between the cells. Her research has shown that the brains of offspring of obese mothers have indeed changed. Even after moderating for the behaviour of the obese mother after birth by cross-fostering, the offspring still have an elevated risk for obesity. Christine would now like to look at whether there are specific times in pregnancy when specific maternal factors might be having an effect on brain development.

To sum up this episode, John revisits our genetics experts to get the final word on the ultimate genetics question. Nature versus nurture – what plays the bigger role in who and how we are?

Things to think about

Things to think about

In conjunction with this episode of Ever Wondered?, your students may enjoy these activities.

In this activity, students use an interactive or paper-based graphic organiser to explore common alternative conceptions about genetics. This activity can be done individually, in pairs or as a whole class.
Genetics true or false

In this activity, students participate in a simulation that demonstrates that both genetic make-up and environmental factors influence an individual’s likelihood of becoming obese.
Obesity risk factors

These are some common student misunderstandings about genetics based on education research. Keep them in mind while teaching – and address them as they come up.
Alternative conceptions about genetics

Associate Professor Tony Merriman used an analogy when he said “genes are like a blueprint from which the house is built” and went on to explain that the gene in the plan needs workers that work off the plan. Analogies are useful models for enhancing student understanding. In this activity, students have an opportunity to learn about the contents of a cell, including DNA, using an analogy of a school.
Inside a cell

In this activity, students extract and observe DNA from a tomato.
Introduction to DNA

Transcript

Transcript

DR JOHN WATT

So we’ve seen the genes that are implicated in disease, but now we’ll look at how the environment can affect a baby’s development while it’s still in the womb. At the University of Otago, Dr Christine Jasoni is exploring how the maternal environment during pregnancy affects the formation of the foetal brain.

DR CHRISTINE JASONI

What we’re really interested in understanding is how the circuitry in the brain forms during foetal life and how it is that the health of the mother, so maternal health, can have an impact on the wiring, on the establishment of this circuitry during foetal life.

DR JOHN WATT

Her research is exploring the hypothesis that obese or diabetic mothers may change the gene expression of their offspring in the womb, which would alter the brain’s wiring. This may lead to their children being susceptible to obesity after they are born.

DR CHRISTINE JASONI

If we think about body weight regulation, one of the theories that’s out there is this idea that there is a set point and your brain works really carefully to ensure that your body weight stays within the set point and that somehow that set point gets passed on to the offspring. There has to be some cellular way that that gets passed on, and we think it’s through the wiring.

DR JOHN WATT

In order to find out how this may work, Christine needs to test her hypothesis on real organisms. As she can’t use human subjects, she uses animals in the laboratory.

DR CHRISTINE JASONI

We use rodents, rats and mice, primarily mice. What we do is we feed the mice what we refer to as a cafeteria diet which has the same approximate components and calorie and fat levels that, ah, sort of the average human diet might have.

DR JOHN WATT

To get an idea of how they run their research, Christine took me into the lab to see some of the work being done.

DR CHRISTINE JASONI

One of the advantages of using rodent models which is what we use is that they do have a fast regeneration time and so we can speed up the process a little bit by using the rodents. But in reality, like all science, there is a decent amount of time that needs to be invested in it.

DR JOHN WATT

So can you tell me what’s going on here?

DR CHRISTINE JASONI

Yeah, so what these guys are doing is they’ve done an experiment where they’ve actually taken the brain and they’ve sliced it really thin and they’ve treated it in such a way that they’re able to visualise some of the proteins. So for example we can tag the cells that we’re specifically interested in and look at their connections.

DR JOHN WATT

By examining the brains of the offspring, Christine has now amassed evidence to show that the brain structures have indeed changed. The next step will be to examine the genes themselves to see how they are being impacted. In designing the experiments, Christine had to take into account that the mother’s behaviour after birth may impact on the baby’s weight. She had to design a control in the experiment to offset this.

DR CHRISTINE JASONI

One of the things that you can do is you can actually take the babies away from their obese mum and we can what we call cross-foster, that is, put them to nurse and be cared for by a normal weight mum. And we can show that they still have an elevated risk for obesity and so that tells us clearly, it sort of timelocks an effect as something that happens during the pregnancy. And what we’re trying to do now is we’re taking pregnancy and then we’re saying, “Are there specific times during pregnancy when specific maternal factors might be having effects on the brain during its development?”

DR JOHN WATT

While Christine’s work is continuing, she is defining important steps in the development of the foetal brain.

DR CHRISTINE JASONI

The really exciting thing about that is that we’re actually to a place where we can start to inform healthcare practitioners and also pregnant women about what the key times during their pregnancy are when they really should be paying attention to what they eat and their calorie intake.

DR JOHN WATT

Throughout the programme, we’ve seen examples where both genetics and the environment play a role in determining how genes are expressed. Now let’s put it boldly to the scientists and ask them directly. Is it our genes or our environment that makes us us?

ASSOCIATE PROFESSOR TONY MERRIMAN

Different camps tend to dichotomise very easily and have arguments about nature versus nurture. I think it’s both, and I wouldn’t like to quantitate how much of nature, how much of nurture. It’s so intricately entangled that nature’s important, nurture’s important – in fact, they’re both very important.

ASSOCIATE PROFESSOR VICKY CAMERON

I’m very much of the opinion that, for heart disease, it’s both nature and nurture. So we know that inheriting certain genetic variants is going to make you more susceptible to developing heart disease but that’s in combination with all the environmental and lifestyle risk factors.

DR CHRISTINE JASONI

While it’s definitely true that certain aspects of individuals are very genetically based, just in general, if you look at all humans, we all look sort of basically the same, we all function basically the same, but each of us of course is very, very individual – the aspects of us that are individual – and that is entirely the consequence of our genetics interacting with our environment.

PROFESSOR MARTIN KENNEDY

I think the bottom line is that, yeah, everything in life is ... involves both nature and nurture. The question is how do they interact and can we understand how they interact and can we modify that then to improve our outcomes and disease and everything else?

DR JOHN WATT

So there you have it, we are a combination of DNA and our environment. Our DNA determines what we are but our environment shapes who we are. And it’s worth remembering a large proportion of the human genome is the same as every other animal on the planet.

Go to www.biotechlearn.org.nz