#aneuploidy

[bpod-bpod]

Placenta Rethink

A placenta can occasionally develop with cells with the wrong number of chromosomes, which was thought to compromise the pregnancy. Here, a study of trophoblasts (the early stage of a placenta developing after fertilisation) derived from stem cells reveals that chromosomal instability can occur spontaneously, suggesting it's an inherent feature, and also shows there are mechanisms for tolerating this state

Read the published research article here

Image from work by Danyang Wang and colleagues

Department of Obstetrics & Gynecology, University of Washington, Seattle, WA, USA

Image originally published with a Creative Commons Attribution – NonCommercial – NoDerivs (CC BY-NC-ND 4.0)

Published in Nature Communications, April 2025

You can also follow BPoD on Instagram, Twitter, Facebook and Bluesky

[bpod-bpod]

Actin Your Age

Loss of or impairment of a protein called F-actin in eggs of older females underlies the increased incidence of embryos with an abnormal chromosome number

Read the original article here

Still from video from work by Sam Dunkley and Binyam Mogessie

School of Biochemistry, University of Bristol, Bristol, UK

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in Science Advances, January 2023

You can also follow BPoD on Instagram, Twitter and Facebook

[bpod-bpod]

Miscounting Chromosomes

Egg cells or oocytes have unique characteristics that make them different from other cells. One of the main differences is the number of chromosomes – condensed structures of DNA. Most human cells have 46 – 23 pairs – but eggs (and sperm) have only 23. This number is critical because any more or less can lead to infertility and miscarriages. These errors occur during meiosis; specialised cell division that generates egg cells, and these errors become more common as women age, but we didn’t know why. By imaging oocytes from younger women (left) and older women (right), researchers have found that a protein called Sgo 2 (green) is vital to helping the chromosome pairs to line up correctly before being pulled apart by microtubules (orange). In older women, Sgo2 doesn’t localise to the right locations meaning that the chromosomes are not lined up correctly for the big divide, increasing the chances of older eggs not meeting that magic number of chromosomes.

Written by Sophie Arthur

Image from work by Bettina P Mihalas and colleagues

The Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in bioRxiv, January 2023 (not peer reviewed)

You can also follow BPoD on Instagram, Twitter and Facebook

[bpod-bpod]

Wrong Number

Whether it’s children on a school bus, money in the bank, or DNA in a cell, careful counting is critical. At the very earliest stage of development, the wrong number of chromosomes [bundled strings of DNA], called aneuploidy, can cause various serious conditions. Most research into this problem has focussed on errors during meiosis [cell division that produces sperm or eggs cells], but errors during chromosome segregation (when paired chromosomes separate and spread out) are equally likely to cause problems. A new study investigated the molecular mechanisms underpinning aneuploidy during cell division in early development, and found some embryos containing micronuclei – enclosed chromosomes that failed to properly segregate (examination of cattle embryos pictured, with an indicator of micronuclei contents highlighted red). Unpicking the process behind aneuploidy in cattle embryos could help better understand the process in humans, and lead to new approaches to keep chromosome numbers straight.

Written by Anthony Lewis

Image from work by Kelsey E. Brooks and colleagues, originally published in BioRXiv, Aug 2020, Oregon National Primate Research Center

Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Beaverton, OR, USA

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Research published in Development, April 2022

You can also follow BPoD on Instagram, Twitter and Facebook

[bpod-bpod]

Critical Number

Most human embryos fail to develop to term, often because they carry the wrong number of chromosomes, a condition known as aneuploidy. Approximately 50–70% of human early embryos are estimated to be aneuploid, and while some issues occur within the egg itself, something else must be causing such high levels of complications. Working with human and bovine embryos, which also experience this problem, researchers identified a crucial moment when errors arise, at the zygote stage, immediately after fertilisation (pictured, in a bovine embryo, with the cytoskeleton in blue). When the separate pronuclei carrying parental chromosomes (in pink) come together, the chromosomes gather at the pronuclear interface, but as the cytoskeleton orchestrates these complicated movements, this clustering step can easily go awry, causing chromosomes to go missing in subsequent cell divisions. A major cause of miscarriages and infertility, understanding this process could also help improve the selection of healthy embryos for fertility treatments.

Written by Emmanuelle Briolat

Image by Tommaso Cavazza and Melina Schuh, Max Planck Institute for Biophysical Chemistry

Max Planck Institute for Biophysical Chemistry, Göttingen, Germany

Image copyright held by the original authors. Image use is limited to non-commercial editorial coverage of the science.

Research published in Cell, May 2021

You can also follow BPoD on Instagram, Twitter and Facebook

[mental-mona]

In a first, study links maternal genes to risk of pregnancy loss

For the first time, scientists have identified genetic variants that increase the risk of aneuploidy, in which cells have an abnormal number

[biology-geology-beaches-india]

Te Scientific Research Notes of S. Sunkavally, Printed Part, Page. 162.

Dates unclear, but certainly between 2006-2012.

[biology-geology-beaches-india]

The Scientific Research Notes of S. Sunkavally (years:2002-2011).

5048-5051.