Scientists have shown how a father’s poor diet, lifestyle and trauma is passed onto his children.
Sperm carries ‘epigenetic’ marks that inform how the baby’s germ cells develop, researchers at the University of California (UC) Santa Cruz, United States (U.S.), have shown.
The study, published in Nature Communications, is one of the first to explain how a parent’s genetic markers have a direct impact on their children.
It offers some explanation for a study that came out earlier this week, showing the sons of Union Army soldiers had a higher risk of early death if their fathers had been prisoners of war subjected to brutal conditions.
Research on epigenetics – the biological study of genes that switch on and off – has gained steam in the past few decades, but particularly in the last few years.
For a long time, scientists dismissed the idea that sperm could carry epigenetic information to their offspring, partly because it is so hard to identify. There are no genetic mutations, rather some genes are prevented from expressing themselves fully.
And yet, more and more studies show that a father’s behaviour can be passed down to his children – be it stress, fear, or a slow metabolism from their dad’s poor diet.
However, recent studies on mice and humans have shown that 10 per cent of epigenetic information is retained in sperm.
Now, testing roundworms, the lab of Dr. Susan Strome has shown that this epigenetic information in sperm, known as ‘histone packaging’, directs the formation of the offspring’s cells.
The lab focused on an epigenetic marker call H3K27me3, which has been shown to repress gene expression in multiple studies.
Once they removed that marker, the vast majority of the offspring were infertile, showing that the marker was clearer essential for the offspring’s development.
Also, men who are classed as infertile could become fathers thanks to a new procedure that gives one in five the chance of conceiving a baby.
Most of the estimated 300,000 British men with extremely low or zero sperm count are told they can’t have biological children, because they either don’t produce enough sperm or there is a blockage in one of the tubes along which the sperm travels.
The new technique, being offered at five specialist National Health Service (NHS) hospitals across the country, involves surgically removing a tiny section of the testicle – less than a millimetre wide – dissecting it, and then retrieving individual sperm cells ‘stuck’ inside.
Crucial to the success of the new procedure, called MicroTESE, is a specialised microscope that magnifies the tubes inside the testicles by 20 times, helping the surgeon to find the sperm.
Dr. Channa Jayasena, consultant in reproductive endocrinology at Imperial College London, who performs the procedure, says: “Many of these men have been told they can’t have children, but this procedure sees between 10-30 per cent of them have a baby. It is amazing.”
Also, scientists have created self-lubricating condoms to help stop the spread of nasty infections.
They are covered in a special, durable coating designed to last however long your passionate romp does.
Sex without enough lube can be painful and increases the risk of condoms slipping off or breaking. When used correctly condoms are a highly effective form of contraception, but not everyone enjoys wearing them.
Many people opt for other ways to prevent pregnancy, like the Pill, but that doesn’t protect from nasty sexually transmitted infections (STI).
Most condoms are lubricated to make them easier to use, but often it is not enough.
That is why scientists at Boston University, United States (U.S.), backed by the Bill and Melinda Gates Foundation, have created self-lubricating ones.
They hope the new condoms will encourage more people to wrap it up before getting down and dirty, and reduce the spread of STIs, according to the BBC.
The condoms become really slippery when they come into contact with bodily fluids and can withstand at least 1,000 thrusts without losing any of its lubrication, according to the study published in the Royal Society Open Science journal.
Having sex typically lasts half that time, the researchers say.
In comparison, regular condoms with water-based lube became less slippery after 600 thrusts.
A group of 33 volunteers were asked to compare the condoms, with most saying they prefer the self-lubricating ones.
Researcher Prof Mark Grinstaff, from Boston University, said: “It feels a bit slimy when you handle it dry, but in the presence of water or natural fluids it becomes really slick. You only need a little bit of fluid to activate it.”
Clinical trials with couples could begin as early as next year.
Meanwhile, a new study suggests fathers who smoke raise the risk of their children and even their grandchildren developing Attention Deficit Hyperactive Disorder (ADHD).
Researchers say that in a study conducted on mice, dads who were exposed to nicotine had offspring more likely to experience cognitive deficits.
Previous studies have shown that mothers who smoke cigarettes raise their children’s risk of developing behavioural disorders, and now fathers have been shown to raise the risk too.
But the team, from Florida State University, says its findings are among the first to show that the risk does not stem from the child’s exposure to secondhand smoke but rather changes in key genes in the father’s sperm.
For the study, the team exposed male mice to low doses of nicotine in their drinking water as they produced sperm during puberty.
Next, the male mice mated with female mice with no nicotine exposure and reproduced.
The fathers had normal behaviour but both male and female offspring were shown to have behavioural disorders.
Problems included attention deficit disorders, hyperactivity and cognitive inflexibility, meaning they were unable to switch between thinking about two different concepts.
When female mice from this generation mated with males, their offspring had fewer deficits in cognitive flexibility, albeit still significant. The reverse was not true regarding the offspring of male mice from that generation bred with females.
Researchers analyzed the sperm from the male mice who were first exposed to nicotine. They found that several genes had been modified including the DRD2 gene, which codes a receptor that plays a role in cognition, memory and learning.
“The fact that men smoke more than women makes the effects in males especially important from a public health perspective,” said lead author Dr Pradeep Bhide, a professor of biomedical sciences & neuroscience at Florida State University.
“Our findings underscore the need for more research on the effects of smoking by the father, rather than just the mother, on the health of their children.”
Studies over the past decade in the field of epigenetics – the study of inheritable traits that are carried outside the genome – have provided support to the idea that the environmental conditions experienced by a parent can affect disease risk and other features of future generations.
A February 2017 study conducted on mice by the University of Massachusetts Medical School, found that the offspring of nicotine-exposed fathers were protected from toxic levels of nicotine compared to the offspring of fathers that were never exposed.
But there was a caveat: these children were also born with an inherited tolerance to drugs, meaning they could be unresponsive to certain antibiotics or even chemotherapy.
Another study published just last month by the University of Bergen in Norway found that dads who smoked only prior to conception were three times more likely to have children with early-onset asthma than dads who had never smoked.
It extends beyond just tobacco use. Several studies have linked paternal diet to metabolic changes in offspring, while others link paternal stress to anxiety-like behaviours in the next generation.