The remarkable endurance of the Y chromosome, ‘master of maleness’
Context
- The Y chromosome, often referred to as the “master of maleness”, has long captivated scientists and historians alike.
Y chromosome
- In humans, in addition to the 22 pairs of chromosomes in each, we have a pair of sex chromosomes called X and Y.
- Sex as a specification is determined by these sex chromosomes. They carry sex-determining genes.
- All biological males have X and Y chromosomes and all biological females have two X chromosomes.
- The ‘sex-determining region Y’ on the Y chromosome determines the biological male sex.
‘Juvenile delinquent’
- Estimated to have emerged around 200-300 million years ago in a common ancestor of all mammals, the Y chromosome has had a unique genetic journey, and embedded within its DNA lies a remarkable tale of evolution.
- Scientists published the complete genetic sequence of the Y chromosome in 2003. This sequence provided an outline of 23 million bases of the 60 million or so bases that together make up the Y chromosome.
- In total, the chromosome encoded for only 55 genes and accounted for around 2% of the genetic material inside a cell.
- Many researchers jokingly refer to the Y chromosome as the “juvenile delinquent” among chromosomes pertaining to its abundance of repetitive sequences, poor functional utility (with a small number of genes), reluctance to socialise (i.e. recombine with other chromosomes), and a high proclivity to degenerate over the course of evolution.
- Indeed, because it has little potential to recombine, the diminutive Y chromosome has been passed from father to son, carrying the legacy of generations.
Vital genes
- In a landmark genetic study, published in March 2003 in the American Journal of Human Genetics, researchers reported that around 0.5% of all the men in the world have inherited a Y chromosome from the Mongol emperor Genghis Khan or one of his descendants.
- Y chromosome possesses genes that are vital to biological functions, including those linked to ageing and lifespan regulation.
- In the animal kingdom (including mammals), scientists have noticed substantial differences in lifespan between the sexes: the females tend to live longer than the males.
- This phenomenon has been attributed largely to the absence of a second Y chromosome in males, exposing the deleterious mutations in the X chromosome.
- It is also well known that men lose the Y chromosome with age and that this is associated with a higher frequency of cancers, Alzheimer’s disease, and a shorter lifespan.
Losing the Y
- Studies have shown that LoY in humans occurs with age and is associated with several debilitating medical conditions – a finding that has been validated in mice with LoY, resulting in weak heart muscles (cardiomyopathy), stretchedor thickened heart tissue (fibrosis), and heart failure.
- researchers have also found that the pathological effects observed on account of LoY in mice’s hearts could be negated by transforming growth factor beta 1-neutralising antibodies, suggesting a potential treatment for this medical condition in future.
- The human Y chromosome is about one-third as big as the X chromosome. So, many animal species, including humans, have a genuine fear of losing the Y chromosome in the distant future.
Conclusion
- Genome sequences of the Neanderthals, an ancient relative of the modern human, harbour telltale signs of the replacement of the Y chromosome beginning from modern humans. This suggests that such replacement is not new to the human lineage, and that it is quite possible that the Y chromosome may have to relinquish its coveted title of “master of maleness” to another chromosome in the times to come.
Editorial 2: Responsibility and the complexities of climate leadership
Context
- Over the last few weeks, there has been an increasingly vocal campaign to unseat the President-Designate of COP28, Minister Sultan Al Jaber of the host nation, the United Arab Emirates (UAE).
Background
- This includes a recent letter from United States and European parliamentarians calling for his removal on the grounds that he is CEO of the Abu Dhabi National Oil Company.
- As representatives of developing countries in the climate change front line, and as leaders of the Climate Vulnerable Forum, a group of 58 of the world’s most climate vulnerable countries hosting 1.5 billion of the world’s poorest people, we know only too well the urgency of the climate challenge.
- We have endured climate-related economic losses of $500 billion in the last two decades alone.
This is a journey of unity
- However, recognising that this journey, towards a clean energy future, is one we must embark on together.
- Fossil fuel-dependent economies are critical to these efforts, and they clearly have a more difficult task defining their energy transition strategy.
- It is important to avoid division and continue to engage the fellow parties at COP28 and elsewhere on the best way forward for their economies and for the planet.
- Finance will be crucial for COP28.
Debt is a barrier
- Many of the nations are crippled by unsustainable debts, including debts which are becoming unpayable due to climate damages largely caused by emissions elsewhere.
- Rather than going one by one over the financial cliff, we urgently need a collective approach which recognises the debt problem and the barrier it now poses to clean energy investment and climate adaptation.
- Sovereign wealth funds and multilateral development banks (MDBs) could assist in de-risking restructured debts and insuring re-issued climate bonds,
- The UAE leadership for a clean energy target starting in 2025, transforming the Abu Dhabi National Oil Company into the Abu Dhabi Clean Energy and Grid Company by 2030, and towards global financial reform including of the International Monetary Fund.
- The Loss and Damage fund that was secured last year in Sharm El-Sheikh must not be just be another empty bank account, and fossil fuels-dependent economies can demonstrate their commitment to a shared future by making subscriptions to support funding for climate damages in the most vulnerable countries, well in advance of the COP.
- Holding COP28 in the UAE, and with Sultan Al-Jaber as COP President-Designate, may well be an opportunity to engage the fossil fuels industry to make some significant and quantifiable commitments to emissions cuts and climate action in general.
Key Points emphasized by the COP28 president-designate Sultan Ahmed Al Jaber:
- Methane Emissions and Net-Zero Plans.
- Inclusive Energy Transition and Climate Justice.
- Maximizing Technology Adoption and Climate Finance.
- Renewable Energy Capacity and Hydrocarbons.
- Carbon Capture Technologies and Industrial Emissions.
- Breakthroughs in Battery Storage, Nuclear Energy, and Fusion.
Conclusion
- There are no winners and losers in a global climate breakdown. Instead of seeking to exclude relevant parties and stakeholders, we believe everyone should participate in decisions with such important ramifications.
- Time is running out, and we all need to work together to save the 1.5°C Paris target before it is too late.
