Developmental biology – Claire Ainsworth

Embryos reverse ageing to become younger than when they first formed

Posted on April 30, 2021 by Claire

New Scientist, 22nd March 2021

Dr Elena Kontogianni, CC0, via Wikimedia Commons

A developing embryo reverses signs of ageing and appears younger than the fertilised egg from which it arose. The finding suggests that embryos are able to rejuvenate, which could lead to ways of reversing age-related diseases.

One of life’s great mysteries is how aged parents produce youthful offspring. Our cells show signs of age as a result of the accumulation of damage wrought by the environment and the body’s metabolism, and yet the eggs or sperm that our bodies make can combine to produce a baby biologically younger than its parents.

This has led biologists to suggest that the germline, the cells that give rise to eggs and sperm and which carry genes down successive generations, are immune to ageing. But recent research shows that not only does the germline age, but that ageing starts even as embryos develop in the uterus, much sooner than we thought.

“Then the question is, if ageing begins earlier, when does it actually begin?” says Vadim Gladyshev at Brigham and Women’s Hospital in Boston.

Age-related damage manifests as changes to patterns of chemical marks – known as methylation – on the DNA in the genomes of cells. These “epigenetic clocks” correlate…

Electricity helps fish take flight

Posted on April 30, 2021 by Claire

New Scientist, 16th March 2021

https://collections.carli.illinois.edu/cdm/singleitem/collection/nby_teich/id/428968

FLYING fish may have taken to the air when evolution tweaked electrical signals that control the size of their fins. This discovery suggests the existence of a previously unknown mechanism by which animals can change the relative size of specific body parts.

“How organs and tissues know when to stop growing at a certain size and stay there is a major mystery,” says Jake Daane at Northeastern University in Massachusetts. This scaling, known as allometry, is also a key driver of evolutionary change. The stunning variation in the fins of bony fish are a classic example, from the billowing veils of the tropical betta fish to the stumpy appendages of a mackerel.

Most dramatic of all are the wings of flying fish, which allow some species to leap from the sea and glide for 400 metres, the length of eight Olympic swimming pools. This helps fish evade underwater predators, a tactic so successful that it has evolved independently several times.

In comparisons of the genomes of nine species of flying fish and some non-flying relatives, Daane and his colleagues spotted genetic changes consistently associated with gliding, and uncovered sections of the genome being conserved by natural selection…

Placenta is full of mutated cells dumped by embryo

Posted on April 30, 2021April 30, 2021 by Claire

New Scientist, 22nd March 2021

Doc. RNDr. Josef Reischig, CSc., CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

THE human placenta is riddled with cancer-like patterns of mutations. But the discovery is better news than it might appear: it is helping scientists open a new window on the mysterious world of early human development.

In some ways, the placenta is a forgotten organ. It begins to form shortly after fertilisation from the embryo’s cells and then helps to support the future fetus as it develops before being discarded at birth.

But it is difficult to study how embryos “decide” which cells are destined for the placenta and which for the fetus.

“So far, we’ve been blind to the first split,” says Tim Coorens at the Wellcome Sanger Institute near Cambridge, UK.

Coorens and his colleagues, including his PhD supervisor Sam Behjati, decided to retrace the lineages of cells in full-term placentas to see where they came from.

Their approach relies on the fact that cells naturally accumulate mutations in their DNA and then pass these on when they divide. By comparing patterns of mutations between samples, it is possible to trace cells’ family trees back in time…

Rare diseases band together toward change in research

Posted on April 29, 2021April 29, 2021 by Claire

Patients with rare diseases, and the scientists who study those diseases, were long inhibited by geographic sparsity. But the social-media age has made it much easier for them to band together to leverage their experience and push forward change.

“There were 150 people in one room at the same time suddenly being able to share. And that was so powerful.” Jillian Hastings Ward recalls attending the first conference, in September 2019, involving scientists, clinicians and the parents of children with a group of rare genetic neurological conditions called ‘GRIN disorders’. There are probably just a few hundred people in total worldwide with GRIN disorders, which means research into their conditions is scarce and there is no cure.

The conference is part of a drive involving the CureGRIN Foundation, a GRIN patient advocacy and patient-led research network, that aims to change that. For Hastings Ward, who is a member of CureGRIN’s board and whose six-year-old son Sam has a GRIN disorder, it felt like a real turning point. “It was really moving to see that many people get together, and the energy it generated in the room was fantastic,” she says. “That ability that we have to help them prioritise, do further research, is something that I’m quite hopeful about in the future.”

This idea of patients coordinating and driving the direction and pace of research is the raison d’être of a growing rare-disease patient movement that aims to transform the relationships among patients, scientists, clinicians and the pharmaceutical industry and thus bring treatments to the clinic much faster than would otherwise be possible.

Patients and their families are forming communities that go beyond patient support and advocacy, and they are actively networking scientists and clinicians together, building medical registries, deciding on research priorities, identifying scientists to work on these priorities and raising funds to support them.

This emerging role of patients as builders of new research-enabling infrastructures represents a shift away from the traditional narrative, in which patients are simply recipients of the fruits of medical research, toward one in which they are active, equal partners in its coordination, design and execution…

Read more: Nature 07 October 2020: https://www.nature.com/articles/s41591-020-1098-7

Image: Pixabay

Sex and the single cell

Posted on October 5, 2017October 5, 2017 by Claire

Sex chromosomes in every cell of the body exert widespread and sometimes unexpected effects.

It was the mouse equivalent of the midnight munchies. Instead of sleeping normally, Karen Reue’s lab mice were waking early and nibbling on extra snacks, which was making them obese. On investigation, she was surprised to find that the probable reason for this out-of-hours feeding was the genetic sex of their cells — the number and kind of sex chromosomes they contain. “It wasn’t at all what we expected,” says Reue, a geneticist at the University of California, Los Angeles (UCLA).

“There is a huge consequence to having two X chromosomes versus an X and a Y.

The idea that our body cells have a ‘sex’, and that this property has consequences for our health, has taken biologists by surprise. Experiments performed in the mid-twentieth century had implied that the hormones produced by the ovaries or testes were the source of physiological differences between males and females. But Reue’s findings are part of a growing body of evidence showing that hormones are only part of the story. It now seems that the genetic sex of cells is crucial too. Cellular sex may also help to explain why women and men have different susceptibilities to conditions such as obesity, heart disease, neurodegeneration, autoimmunity and cancer, and why such conditions can behave differently in the two sexes. Certainly, when it comes to metabolism, “there is a huge consequence to having two X chromosomes versus an X and a Y throughout your whole body,” says Reue…

To read more, click here: Nature Outlook article on cellular sex (5th October 2017)

Secrets of life in a spoonful of blood

Posted on August 26, 2017August 26, 2017 by Claire

The intricate development of the fetus is yielding its long-held secrets to state-of-the-art molecular technologies that can make use of the mother’s blood.

Life starts with a puzzle. Out of sight in a mother’s womb, 3 billion letters of DNA code somehow turn into 3D bodies, all in the space of a mere 40 weeks. Fetuses form eyes, brains, hearts, fingers and toes — in processes that are meticulously coordinated in both time and space. Biologists have pieced together parts of this puzzle, but many gaps remain.

Now, a crop of molecular technologies is giving scientists tantalizing hints about how to fill in those gaps. Improved ways of reading and interpreting the information in fetal genetic material are uncovering a raft of genes involved in human development, and letting researchers eavesdrop on the hum of gene activity before birth. They can see which genes turn on or off at pivotal moments, and sense how the environment nurtures or intrudes on this…