Tag Archives: Chromosome

Y Chromosome Loss: A Possible Factor in Lung Cancer Progression and Outcomes

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Insights into the impact of Y chromosome loss on lung cancer treatment outcomes may guide therapeutic choices.

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Research indicates that men diagnosed with the predominant type of lung cancer are more likely to lose the Y chromosome in their cells. This phenomenon has both pros and cons; while it can prevent the immune system from combating tumors, it also enhances the effectiveness of standard anti-cancer therapies.

As men grow older, their cells frequently undergo mutations, leading to the loss of the Y chromosome. In immune cells, this loss is believed to correlate with heart disease and decreased life expectancy. Additionally, there is growing evidence that cancer cells that lose the Y chromosome may influence symptom progression, with bladder cancer being the most thoroughly researched case.

The loss of the Y chromosome is a binary occurrence—it either happens or it doesn’t. However, the health implications seem to depend significantly on the proportion of specific cells that lack the Y chromosome.

The recent study initiated by Dawn DeMeo and her team at Brigham and Women’s Hospital in Boston, Massachusetts, investigated how Y-chromosome genes are expressed in a publicly available dataset of lung adenocarcinoma samples. Lung adenocarcinoma, the most common form of lung cancer, originates from the mucus-producing cells lining the airways. Enhanced understanding of the relationship between Y loss and various health issues has motivated researchers to delve deeper into gene expression studies, according to DeMeo.

The team discovered that cancer cells, in contrast to healthy lung and immune cells, often lack the Y chromosome. This occurrence is independent of whether the tissue donor is a smoker—despite smoking being linked to lung cancer and Y chromosome loss.

The loss of Y chromosomes appears to accumulate over time. “Certain groups demonstrate a higher rate of Y chromosome loss across a greater number of cells, and we observe significant Y chromosome loss in a large fraction of tumors,” stated John Quackenbush from Harvard University.

To comprehend the reasons behind this accumulation, researchers examined other genetic alterations in Y-negative cells. They found that the loss of a common set of antigens produced by cancer cells correlates with diminished expression levels. These antigens usually notify immune T cells that cancer cells are abnormal and should be targeted. The decreased expression allows Y-negative cancer cells to proliferate unchecked.

“This implies that as tumor cells lose their Y chromosome, they become increasingly adept at evading immune surveillance, suggesting a selection of tumor cells that escape immune detection,” Quackenbush explained. T cell counts were consistently lower in samples with Y loss compared to those retaining the Y chromosome.

Positive findings emerged when researchers analyzed data from 832 lung adenocarcinoma patients treated with the immune checkpoint inhibitor pembrolizumab, a medication designed to restore the body’s immune response against tumors by reversing T-cell suppression. The analysis confirmed that Y chromosome loss was linked to improved treatment outcomes.

“Patients experiencing LOY [loss of Y] are more responsive to checkpoint inhibitors,” noted Dan Theodorescu from the University of Arizona, who found similar results in bladder cancer, establishing validation against an entirely different dataset.

However, while loss of the Y chromosome is linked to shorter life expectancies for men compared to women, existing data suggests it does not impact survival in patients with lung adenocarcinoma. Further research is needed to explore how the effects of such mutations influence survival across different cancer types, according to Theodorescu. As our understanding advances, he believes that loss of Y could eventually serve as a biomarker for clinical decision-making.

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Source: www.newscientist.com

Scientists Find the Atlas Blue Butterfly Has 229 Chromosome Pairs

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Researchers from the Wellcome Sanger Institute and the Spanish Institute of Biology have mapped the female genome of the Atlas Blue Butterfly (Polyommatus atlantica), revealing 227 pairs of autosomes and four sex chromosomes, marking it as the organism with the highest chromosome count among all multicellular animals globally.

Atlas Blue Butterfly (Polyommatus atlantica). Image credit: Roger Villa.

The Atlas Blue Butterfly is native to the mountainous regions of Morocco and Northeast Algeria.

Previously suspected to have the highest chromosome count in the Animal Kingdom, this is the first instance where scientists have successfully sequenced the butterfly’s genome to confirm this assumption.

In comparison, the more commonly observed Common Blue Butterfly (Polyommatus icarus) has only 24 chromosomes.

Variations in chromosome numbers are believed to facilitate the formation of new species and assist in adaptation to changing environments.

The Atlas Blue Butterfly belongs to a group of closely related species that have evolved rapidly over a short geological timeframe.

“The genome is crucial for understanding how organisms develop and what the future may hold,” stated Professor Mark Blaxter from the Wellcome Sanger Institute.

“To narrate the stories of our planet, we must explore various tales and observe their interactions.”

“Insights gained from one genome can also enrich our understanding of others.”

“For instance, chromosomal rearrangements are also present in human cancer cells, and investigating these patterns in the Atlas Blue Butterfly could lead to methods for mitigating cancer cell growth in the future.”

In their research, Professor Blaxter and his team discovered that chromosomal structure was altered due to less tightly packed DNA.

This indicates that while the amount of genetic information remained similar, it was organized into smaller segments.

Except for the sex chromosomes, all chromosomes were found to be fragmented, leading researchers to estimate a dynamic range of 24 to 229 chromosomes emerging over approximately 3 million years, a brief period in evolutionary terms.

Generally, such drastic chromosomal modifications are considered detrimental; however, the Atlas Blue Butterfly has thrived for millions of years.

Its population faces threats primarily from climate change and human environmental impact.

This study opens numerous avenues for future exploration.

Chromosomal division is thought to enhance genetic diversity by allowing for increased genomic mixing or possibly offering other unforeseen advantages.

While this may enable butterflies to adapt quickly, possessing numerous chromosomes can also introduce complications, potentially making them more susceptible to extinction in the long run.

Further studies comparing other butterfly species will clarify whether genes are lost or retained, offering greater insights into butterfly biology and evolution.

“Observing chromosomal degradation at this level is uncommon, yet evident in butterflies of other species, hinting at a significant need for exploration in this area,” noted Dr. Roger Villa, a researcher at the Evolutionary Biology Institute in Spain.

“Moreover, chromosomes hold the secrets of species, and examining how these changes influence butterfly behavior could help us form a comprehensive understanding of species emergence.”

“When we embarked on studying butterfly evolution, we realized that sequencing the extraordinary Atlas Blue Butterfly was essential,” remarked Dr. Charlotte Wright from the Wellcome Sanger Institute.

“This research emphasizes the collaborative spirit of scientific inquiry.”

“By examining how the chromosomes of the Atlas Blue Butterfly have split over time in specific environments, we can begin to uncover the potential benefits of this phenomenon, how it influences adaptability, and whether there are lessons in the DNA that could aid our future conservation efforts.”

The findings have been published in this week’s edition of Current Biology.

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Charlotte J. Wright et al. Chromosomal evolutionary constraints revealed by the 229 chromosome pairs of the Atlas Blue Butterfly. Current Biology, published online on September 10th, 2025. doi: 10.1016/j.cub.2025.08.032

Source: www.sci.news

The Vanishing Y Chromosome: A Potential Contributor to Heart Disease in Men

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Human Y (right) and X chromosomes observed via scanning electron microscopy

Human Y (right) and X chromosomes observed with scanning electron microscopy

Power and Syred/Science Photo Library

A recent study involving over 30,000 individuals has revealed that men who experience a loss of Y chromosomes in a substantial number of immune cells are at a higher risk for narrower blood vessels, a significant factor in the development of heart disease.

“The loss of Y chromosomes greatly impacts men,” states Kenneth Walsh from the University of Virginia, who was not involved in the research. “Men’s lifespan averages six years shorter than women’s, primarily due to the instability of sex chromosomes.”

Loss of the Y chromosome is one of the most prevalent mutations following conception in men. This phenomenon typically occurs in leukocytes, the immune cells responsible for attacking and eliminating pathogens, as the rapidly multiplying stem cells that generate white blood cells undergo division. The cells without Y chromosomes accumulate and become more frequent as individuals age; approximately 40% of 70-year-old men show detectable losses.

This issue gained traction in 2014 when Lars Forsberg from Uppsala University in Sweden and his colleagues noted that elderly men with significant Y chromosome loss in their blood typically had a lifespan that was five years shorter than those without it. Walsh later linked this loss to heart disease.

Forsberg and his research team have now uncovered further connections between Y chromosome loss and specific cardiovascular issues. They analyzed data from Swedish cardiopulmonary bioimaging studies, which provided detailed vascular scans of 30,150 volunteers aged between 65 and 64. None of the participants exhibited symptoms of cardiovascular disease; however, they were assessed for vascular stenosis or atherosclerosis.

Among the male participants, 12,400 possessed the necessary genetic information to evaluate their Y chromosome loss. They were categorized into three groups: those with no detectable Y loss in leukocytes, those with less than 10% loss, and those with over 10% loss. Atherosclerosis scores for these groups were then compared with each other and with a female cohort in the study.

The researchers discovered that approximately 75% of men who had the highest Y chromosome loss exhibited narrowed blood vessels, while around 60% of those with less than 10% loss showed similar findings.

Despite some atherosclerosis being observed even in those with undetectable Y loss, about 55% of men and roughly 30% of women in this category had been affected. “Clearly,” Forsberg noted, “[loss of Y] involves other factors.”

In the coming months, Thimoteus Speer and colleagues from the University of Goethe in Frankfurt studied men undergoing angiography, an X-ray technique for examining blood vessels due to suspected cardiovascular disease. They found that over the next decade, individuals who lost Y chromosomes in more than 17% of their immune cells were more than twice as likely to die from a heart attack compared to those with less affected cells.

“The findings of Lars Forsberg and our study are quite consistent,” Speer remarked. “He observes increased coronary atherosclerosis, correlating it with a higher risk of mortality from myocardial infarction [heart attack], emphasizing the relationship with coronary atherosclerosis.”

Walsh acknowledges that neither study definitively proves that Y chromosome loss directly causes these outcomes. However, statistical analyses suggest its independent effect aside from smoking or aging— the primary risk factors for mutations.

The pressing question remains: how does Y chromosome loss impact health? Previous research by Walsh indicated that removing chromosomes from mouse immune cells adversely affects the cardiovascular system by driving fibrosis, which is the formation of scar tissue. However, heart attacks and atherosclerosis are typically more associated with inflammation and lipid metabolism defects than fibrosis. Both Speer and Walsh assert that more research is essential to unravel this relationship.

With a deeper understanding of the underlying processes, Speer hopes that future blood tests for Y chromosome loss will guide proactive interventions. “[These tests] may help in identifying patients who could particularly benefit from specific treatments,” he concludes.

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Source: www.newscientist.com

Is the disappearance of the Y chromosome spelling the end for men?

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What might the future look like in a world without men? Recent studies indicate that the Y chromosome, a crucial factor in determining male identity, is experiencing malfunctioning.

The Y chromosome has already undergone significant degeneration and could potentially vanish entirely. But what implications would this disappearance have?

Could new sexes emerge? Or could the male species face extinction? Renowned Australian geneticist Jenny Graves, an expert on the Y chromosome, sheds light on these developments.

Why is the Y chromosome disappearing?

First, let’s revisit the concept of sex chromosomes. Women typically have two X chromosomes, while men possess one X and one Y chromosome.

These chromosome pairs, which account for about 4% of an individual’s DNA, play a vital role in determining sex.

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“Chromosomes typically occur in pairs, with men and women sharing the same sex pairs. Women have two large X chromosomes, whereas men have one X and one Y,” explains Graves.

“In comparison to the X chromosome, the Y chromosome is relatively small, containing only 45 genes, with one gene determining maleness and several others involved in sperm production. The remaining genes serve uncertain purposes. By contrast, the X chromosome contains 900-1400 genes.

Originally, the Y chromosome had over 900 genes similar to the X chromosome. Presently, only 45 genes remain. These sex chromosomes evolved from identical non-gender-associated chromosomes, rendering much of their current makeup functionally redundant.

The degeneration of the Y chromosome is not unique to humans; it also occurs in other species. For instance, fruit flies have lost the majority of their Y chromosomes.

“The loss of the Y chromosome seems to stem from a couple of factors. The Y chromosome is exclusively present in the testes, never in the ovaries; thus, it is constantly exposed to mutations during sperm production,” explains Graves.

“Sperm production involves numerous cell divisions, each susceptible to mutations that can substantially affect the chromosomes. Moreover, the Y chromosome cannot engage in genetic exchange, hindering its ability to repair mutations effectively.”

Most chromosomes repair mutations by exchanging DNA with their counterpart chromosome, a process known as recombination. However, the Y chromosome, inherited singly unlike the dual X chromosomes in women, lacks this mechanism for genetic exchange.

What does this mean for the future of the male species?

Compared to its original state, the human Y chromosome has lost 97% of ancestral genes, while the X chromosome remains relatively intact.

What are the implications of this rapid degeneration for the male species? Are we on the verge of a world devoid of human males?

“When I mention rapid degeneration, I refer to an evolutionary timeframe. Sex chromosomes have undergone roughly 180 million years of evolution in mammals. It took this long for the Y chromosome to erode to its current state,” notes Graves.

“The impending loss of the Y chromosome has stirred concern in some quarters. A rough estimate suggests it might take another six or seven million years before the chromosome completely disappears.”

Unless global billionaires achieve immortality breakthroughs, humans may never witness the initial stages of Y chromosome degradation. But hypothetically, what might this development entail?

While some species can reproduce through parthenogenesis (unfertilized egg development), humans require sperm-bearing genes for optimal functioning. These genomically imprinted genes necessitate male involvement for reproduction. However, viable alternatives exist.

“Evolving new sex-determining genes could pave the way, as seen in certain rodent species like the eastern European mole rat and Japanese spiny rat, which lack a Y chromosome entirely. These rodents adapted by relocating crucial Y chromosome genes to other chromosomes.”

Although successful in rodents, this strategy may not yield the same results in humans. While creating new sex genes is feasible, the ensuing clash between old and new genes poses uncertainties.

“This gene conflict scenario could potentially lead to divergent sex-determining systems across human populations,” Graves explains. At present, these speculations predominate. While the Y chromosome’s deterioration is evident, the future outcomes remain uncertain, encompassing the possibility of evolutionary changes resulting in new sexes.

Given the Y chromosome’s peculiarities and the substantial human population, Graves suggests that an individual born without a Y chromosome might already exist somewhere in the world, broaching intriguing evolutionary prospects.

About our expert Jenny Graves

Jenny Graves is a geneticist and professor at the La Trobe Institute for Molecular Sciences. She has authored over 430 articles and four books on genetics, establishing herself as a leading authority on human evolution and the evolving landscape of the Y chromosome.

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Source: www.sciencefocus.com

Arabica Coffee Genome Sequenced at Chromosome Scale by Scientists

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researchers Genomica Application Laboratory and elsewhere are releasing improved genome assemblies. Arabica coffee (arabica coffee tree)a hybrid of coffee tree and robusta coffee (Coffea genus) contributes to approximately 60% of the world's coffee production.

arabica coffee tree. Image credit: Fadil Askar.

arabica coffee tree derived from interbreeding between modern ancestors Coffea genus and another closely related coffee species, coffee tree.

As a result of this hybridization, arabica coffee treeflavor and its large and complex genome pose challenges to breeding and genetic research.

Some partial genome assemblies arabica coffee tree is currently available, but the mechanisms that generate its genetic diversity are unknown.

Researchers Michele Morgante and Gabriele Di Gaspero and their colleagues at the Istituto di Genomica Appplicata used the latest sequencing technology to generate a more complete genome assembly. arabica coffee treeallowing detailed analysis of its chromosomal structure.

Analysis of the genome, including previously inaccessible regions such as around centromeres, revealed differences in genome structure, function, and evolution contributed by the two ancestral species, particularly in genes involved in caffeine biosynthesis. found.

For this study, they also analyzed the genomes of 174 samples collected from different species within Earth. coffee genus and found a very low level of genetic diversity within it. arabica coffee tree.

Diversity found to be increasing in some regions arabica coffee tree Varieties of specific genomic regions due to two different sources of variation: chromosomal abnormalities and gene segments provided by so-called Timor hybrids. Arabica coffee x Canephora coffee tree A hybrid from East Timor.

This hybrid is the parent line for many modern varieties that combine disease resistance traits. Coffea genus And its unique flavor is arabica coffee tree.

The authors argue that genetic diversity arabica coffee tree Essential for commercial success, this discovery could help develop new coffee varieties with desirable traits, such as disease resistance or different flavor profiles.

“Resequence data from large accession sets reveal low intraspecific diversity at the center of species origin. arabica coffee tree” the authors write in their paper.

“Across a limited number of genomic regions, the diversity of some cultivated genotypes has increased to levels similar to that observed in one of the ancestral species. Coffea genusThis is probably the result of introgression derived from Timor hybrids. ”

“We also found that in addition to very few early exchanges between homologous chromosomes, there are many recent chromosomal abnormalities such as aneuploidies, deletions, duplications, and exchanges.”

“These phenomena are still polymorphic in the germplasm and may be the root cause of genetic variation in such low-variability species.”

of paper Published in this week's magazine nature communications.

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S. Scalabrine other. 2024.Chromosome-scale assembly reveals chromosomal abnormalities and exchanges that generate genetic diversity arabica coffee tree germ plasm. Nat Commune 15,463; doi: 10.1038/s41467-023-44449-8

Source: www.sci.news