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Comment by Dr. Krishna Kumari Challa on August 24, 2024 at 11:33am

Researchers identify piRNAs as a highly relevant genetic cause of male infertility

Many couples struggle with infertility. Contrary to popular belief, men are just as often the cause of an unfulfilled desire for children as women—and genetics play a significant role in this. Researchers from the Institute of Reproductive Genetics at the University of Münster have now provided new insights on this topic.

The study, published in Nature Communications, shows for the first time that disruptions in the so-called piRNA pathway are an underestimated cause of defective sperm production.

RNA, short for ribonucleic acid, is a single-stranded molecule composed of nucleotides present in every cell of an organism and acts as a carrier of genetic information. PiRNA refers to specialized, very small RNA fragments found in the testes that help suppress the activity of transposons, also known as jumping genes. 

The researchers analyzed the DNA of more than 2,000 infertile men, mostly from the Münster Center for Reproductive Medicine and Andrology, for variations in piRNA pathway genes.

They identified 39 men with variations in 14 piRNA genes, many of which are reported  for the first time.  Their findings reveal that faulty regulation of piRNAs is a far more common cause of male infertility than previously recognized.

The impact of these genetic variants on sperm production differed between humans and mouse models, suggesting that findings from mice are not universally applicable to humans. In some patients with piRNA variants, an increased number of transposons was detected.

A higher count of jumping genes in germ cells causes genomic instability, leading to various disruptions in sperm production, from abnormal shapes to complete absence of sperm.

While the newly discovered disruptions in the piRNA pathway cannot yet be treated, these insights will help provide more men with an accurate diagnosis in the future—offering relief to many who have faced years of uncertainty and allowing for more targeted treatments.

Birgit Stallmeyer et al, Inherited defects of piRNA biogenesis cause transposon de-repression, impaired spermatogenesis, and human male infertility, Nature Communications (2024). DOI: 10.1038/s41467-024-50930-9

Comment by Dr. Krishna Kumari Challa on August 24, 2024 at 11:26am

Even mild concussions can have lifelong brain impacts

A team of neuroscientists, brain specialists and psychiatrists has found evidence suggesting that minor brain injuries that occur early in life, may have health impacts later on.

In their paper published in the journal JAMA Network Open, the group describes how they analyzed and compared MRI scans from hundreds of people participating in the U.K.'s Prevent Dementia study.
Prior research has suggested that some forms of dementia could be related to some types of brain injuries. In this new effort, the research team, hoping to learn more about the impact of concussions or other minor brain injuries on dementia, looked at MRI scans of 617 people between the ages of 40 to 59 who had volunteered to take part in the Prevent Dementia study and who had undergone at least three MRI scans. They also studied their medical histories, focusing most specifically on whether they had had brain injuries anytime during their life.

The research team noted that 36.1% of the volunteers reported having experienced at least one brain injury that was serious enough to have caused them to be unconscious for a short period of time—such injuries are classified as traumatic brain injuries (TBIs).

Looking at the MRI scans, the researchers found higher than normal instances of cerebral microbleeds (1 in 6 of them) and other symptoms of what they describe as evidence of small vessel disease of the brain. They also found that those patients with at least one TBI were more likely to smoke cigarettes, had more sleep problems, were more likely to have gait issues and to suffer from depression. They also noted that the more TBIs a person had, the more such problems became apparent.

Another thing that stood out, the team notes, was that those people who had experienced a TBI when younger had a higher risk of memory problems than did patients with cardiovascular disease, high blood pressure or diabetes, a possible clue about their likelihood of developing dementia.

Audrey Low et al, Neuroimaging and Clinical Findings in Healthy Middle-Aged Adults With Mild Traumatic Brain Injury in the PREVENT Dementia Study, JAMA Network Open (2024). DOI: 10.1001/jamanetworkopen.2024.26774

Comment by Dr. Krishna Kumari Challa on August 24, 2024 at 11:21am

Yeast meiosis study finds temperature changes result in shorter meiotic chromosome axes and more crossovers

In a study of meiosis in budding yeast, a research team found that yeast senses temperature changes by increasing the level of DNA negative supercoils to increase crossovers and modulate chromosome organization during meiosis.

Meiosis is a specialized cell division producing gametes with the half chromosome complement of their progenitor cells. Meiotic crossovers between homologous (maternal and paternal) chromosomes, which result in the reciprocal exchange of chromosome fragments, play two important roles: physically holding the homologous chromosomes together to ensure their proper segregation, and promoting the genetic diversity of their progeny.

The formation of crossovers is regulated by the architecture of meiotic chromosomes, each of which is organized as a linear array of loops anchored at their bases to a proteinaceous axis.
The researchers studied yeast meiosis, and found that changes in temperature (either decreased or increased) resulted in shorter meiotic chromosome axes and more crossovers. The research teams further found that temperature changes coordinately enhanced the hyperabundant distribution of axis proteins (such as Red1 and Hop1) on chromosomes and the number of putative crossover marker Zip3 foci.

Importantly, temperature-induced changes in the distribution of axis proteins and Zip3 foci depend on changes in DNA negative supercoils, which have been shown to regulate the number of crossovers. In addition, temperature changes regulate the abundance of axis-associated proteins and thus axis length, independently of changes in DNA negative supercoils.

These results suggest that yeast meiosis senses temperature changes by increasing the level of DNA negative supercoils to increase the number of crossovers and modulate chromosome organization. These findings provide a new perspective on understanding the effect and mechanism of temperature on meiotic crossovers and chromosome organization, with important implications for evolution and breeding.

: Yingjin Tan et al, Temperature regulates negative supercoils to modulate meiotic crossovers and chromosome organization, Science China Life Sciences (2024). DOI: 10.1007/s11427-024-2671-1

Comment by Dr. Krishna Kumari Challa on August 24, 2024 at 11:03am

Biological clocks in nature

Much of what we know about plant circadian rhythms is the result of laboratory experiments where inputs such as light and temperature can be tightly controlled.

Less is known about how these biological timing mechanisms operate in the more unpredictable natural world where they evolved to align living things to daily and seasonal cycles.

A pioneering collaborative study between  researchers has helped redress the balance with a series of innovative field experiments that show how plants combine clock signals with environmental cues under naturally fluctuating conditions.

 This research team has produced statistical models based on these field-based studies that could help us predict how plants, major crops among them, might respond to future temperatures.

In this present study, "Circadian and environmental signal integration in a natural population of Arabidopsis," which appears in PNAS, the research team set out to identify this mechanism in nature.

In two field studies around the March and September equinoxes, they analyzed a natural population of Arabidopsis halleri plants on a rural Japanese field site. They monitored how gene expression in the plants changed over 24-hour cycles as light and temperature varied.

Experiments involved extracting RNA from plants every two hours, freezing these samples and taking them back to the lab for analysis so that they could track gene expression levels in tissues.

Using the information collected from samples, the researchers observed patterns in the expression of genes in the previously discovered genetic pathway that integrates information from the plant circadian clock with light and temperature signals.

The data collected showed that the plants in wild populations showed the same sensitivity to cold and bright dawn conditions previously observed in laboratory experiments.

Based on this information, the team developed statistical models which accurately predict how gene expression activity under control of the circadian clock will respond to environmental signals over a day in nature.

This is the first time anyone has modeled a whole circadian clock signaling pathway in plants growing outdoors.

If we can produce models that can accurately predict gene expression in relation to environmental conditions, then it may be possible to breed plants that are able to adapt to future climate conditions.

Haruki Nishio et al, Circadian and environmental signal integration in a natural population of Arabidopsis, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2402697121

Comment by Dr. Krishna Kumari Challa on August 24, 2024 at 10:48am

Colorful traits in primates ease tensions between groups, data suggest

Primate ornamentation plays a crucial role in communication not only within social groups but also between them, according to a new study. The research, published in Evolution Letters, reveals that the males of species with overlapping home ranges often display vibrant colors or elaborate features, traits that may help reduce intergroup aggression by enabling quick assessment of potential rivals.

Ornaments are sexually selected traits that serve as powerful signals, often indicating an individual's genetic quality, health or physical strength.

These differences in appearance between males and females, known as dimorphic traits, are expressed in features like colorful fur or elaborate body structures. Examples include the golden snub-nosed monkey's lip wart and blueish face, the mandrill's vivid facial features with its red nose and blue skin, the gelada baboon's impressive mane and red chest patch, or the proboscis monkey's remarkably large nose.

A new study has uncovered an intriguing link between these dimorphic traits and how primates interact with other groups.

The researchers analyzed data from 144 primate species, including both monkeys and apes (prosimians and anthropoids). They focused on how ornamentation relates to the overlap of home ranges, which measures how much living space groups share with their neighbours.

The research shows that the vibrant colours  and elaborate body ornaments seen in many primate species may do more than attract mates or establish social hierarchies. These features also play an important role in communication between different social groups.

The findings showed a clear pattern: "Species that shared more space with their neighbors had significantly greater differences in ornamentation between the sexes. In species where groups frequently interact, males are more likely to sport flashy traits that set them apart from females."

The study also found that intergroup encounters were less likely to be aggressive in species with greater home range overlap. Encounters deemed conflict-related included behaviors such as physical confrontation, displays of strength, avoidance, displacement, vigilance and vocal warnings.

This suggests that vivid physical traits might help to reduce conflict between groups, possibly by allowing them to quickly assess potential rivals from a distance.

The study sheds new light on the evolution of primate ornamentation and provides valuable insights into the complex world of animal communication.

Cyril C Grueter et al, The role of between-group signaling in the evolution of primate ornamentation, Evolution Letters (2024). DOI: 10.1093/evlett/qrae045

Comment by Dr. Krishna Kumari Challa on August 24, 2024 at 10:21am

This desert school's unique design offers respite from heat

In the sweltering heat of India's Thar desert, where summer highs soar above 50 degrees Celsius, an architecturally striking school is an oasis of cool thanks to a combination of age-old techniques and modern design.

The school used the same yellow sandstone as the 12th-century fort in nearby Jaisalmer, in India's western state of Rajasthan, dubbed the "golden city" due to the colour of the rock.

Like the fort, the school has thick rubble walls that help bounce back the heat, while the interior is plastered with lime, a porous material that regulates humidity and aids natural cooling.
Unlike the ancient fort, its roof is lined with solar panels, which provide all the school's power in an area with frequent electricity cuts.

Temperatures inside the school, designed by US-based architect Diana Kellogg and built by local artisans—many of them parents of pupils—can be as much as 20 percent lower than those outside.

The air inside feels as if it is coming from an AC.

Elevated windows allow hot air to escape as it rises. Rainwater is harvested from the flat roof.

In some places, the walls are dotted with perforations—a technique known as "jali" that was traditionally used for modesty, shielding women from view in the conservative society.

At the school, it is used to promote ventilation, creating a breeze channeled by the building's oval shape.

There is cross-ventilation. And the white tiles on the terrace reflect the sunlight.

Combining tradition with modern design and sustainable techniques was key for this 'cool school'.

Comment by Dr. Krishna Kumari Challa on August 24, 2024 at 10:08am

Faulty gene makes the brain too big—or too small

A gene called ZNRF3, known to be involved in cancer, also messes with the mind. The human brain relies on two copies of this gene to build a correctly sized brain. If one of the copies is defective, the brain will be either too small or too large—known as mirror effect—leading to various neurological symptoms.

Scientists tested the faulty versions of the gene in the lab and found a correlation between patients' brain size and the location of the mutations in the gene. After a long diagnostic odyssey, they were finally able to establish a definitive cause for the disease of these patients. Their study is published in the American Journal of Human Genetics.

The gene ZNRF3 produces two copies of a protein that prevents the brain from making too many or too few brain cells. It also does the same in many other organs, so that mutations in its DNA sequence can lead to uncontrolled cell proliferation and are therefore associated with a variety of tumors, such as colon or adrenal cancer.

One of their analyses revealed that there is a small region of the ZNRF3 gene, called RING, where many mutations found in cancers are located compared to the rest of the gene. In fact, most of the patients with abnormally large brains have their mutations in the RING region. This means that they may have an increased risk of developing tumors during their lifetime.

Further analyses showed that almost all the mutations that lead to abnormal development are located in two distinct regions of the gene: one in the RING region, and the other in a smaller region that is important for interacting with another gene called RSPO. It turned out that almost all the defects in the RING region were from the patients with an abnormally large brain, while the defect in the RSPO-interacting region came from the patient with an abnormally small brain.

However, one patient had a fault in the RING region but had an abnormally small brain. We traced his family history and found that his mother used drugs heavily during her pregnancy, which could explain his abnormally small—instead of large—brain. Apparently, environmental influences can override genetic defects in this condition.

The gene ZNRF3 orchestrates the perfect balance of biochemical signals, particularly in the Wnt signaling pathway, needed to produce the right number of brain cells. This gene works in concert with the gene RSPO, which also interacts with the Wnt signaling.

These results showed that the right brain size depends on a balanced Wnt signaling, which, once tipped toward too much or too little, can cause the brain to become too large or too small.

 Paranchai Boonsawat et al, Deleterious ZNRF3 germline variants cause neurodevelopmental disorders with mirror brain phenotypes via domain-specific effects on Wnt/β-catenin signaling, The American Journal of Human Genetics (2024). DOI: 10.1016/j.ajhg.2024.07.016

Comment by Dr. Krishna Kumari Challa on August 24, 2024 at 9:58am

In female flies fed NPs, heart size (diastolic diameter) increased, and diastolic intervals increased in females fed both MPs and NPs. Meanwhile, heart sizes of male flies fed both sizes of plastic exhibited significant changes to diastolic and systolic diameters.

Furthermore, the researchers write, "Unlike females, male flies also see changes to Systolic Interval (SI) Time and fractional shortening. Total SI time is reduced by 40% in flies exposed to MPs while female flies see no change. Finally, males exposed to NPs experience an 11% reduction in fractional shortening. This phenomenon is unique to males, as females see no change to fractional shortening following dietary exposure to either plastic size."
The researchers note that they had initially hypothesized that the changes they recorded might have resulted from MPs and NPs actually creating a physical barrier to normal heart development. They also believe that "molecular interactions between the plastics and the heart itself" are responsible for the sexually dimorphic changes they observed, especially the differences in male and female heart sizes.

However, they acknowledge, "The true mechanism behind these observed changes is unknown, and so further research is needed to identify if exposure to MPs and NPs interacts with any mammalian conserved genes which may lead to cardiac dysfunction."
They also suggest that further research could include a variety of ingestible plastic shapes, and that further research should also focus on pinpointing the specific molecular changes causing the observed functional disorders.

 Alyssa M. Hohman et al, The heart of plastic: utilizing the Drosophila model to investigate the effects of micro/nanoplastics on heart function, Frontiers in Toxicology (2024). DOI: 10.3389/ftox.2024.1438061

Part 2

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Comment by Dr. Krishna Kumari Challa on August 24, 2024 at 9:56am

Micro- and nanoplastics ingested by Drosophila cause changes in heart size and function

Plastics are ubiquitous in products we use every day, and recent studies have begun to reveal the effects of micro- and nanoplastics (MPs and NPs) on the health of humans and animals.

Much research on the health effects of MPs and NPs to date has focused on marine life, especially fish. A few early studies have investigated possible toxic effects of plastics on terrestrial species such as birds, earthworms, insects, humans and other mammals, but myriad specifics remain unknown.

A team of researchers from Iowa State University, using fruit flies (Drosophila melanogaster), has now made the first examination of the effects of MP and NP toxicity on the heart. The team's work is published in a Brief Research Report in Frontiers in Toxicology.

Drosophila hearts and vertebrate hearts are similar with respect to functional and genetic changes during development and aging. For this new study, the researchers obtained wild-type Drosophila fly larvae and divided them into a control group and two test groups.
They fed all the flies a diet of cornmeal from the beginning of their development until they reached maturity (pupation). Flies in the two test groups received cornmeal to which the researchers added polystyrene MPs (larger than 100 nm and smaller than 5 mm) or NPs (smaller than 100 nm).

Five days after the flies hatched, the researchers collected approximately 15 flies of each sex from each of the two test groups and the control group. The team anesthetized the flies, dissected their beating hearts, and recorded high-speed video at over 200 frames/second for analysis.

Among the notable results, the analysis indicates that plastic exposure produces different results in males and females. The heart rates of female flies exposed to both MPs and NPs decreased 13%, while their heart periods (time between the beginning of a heartbeat and the beginning of the next heartbeat) increased correspondingly. Male flies did not exhibit this change, but males fed MPs exhibited greater variability than those fed NPs and those in the control group.
Part 1

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 11:04am

‘Dark Oxygen’ Is Coming from These Ocean Nodules

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