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Comment by Dr. Krishna Kumari Challa on July 29, 2023 at 7:57am

How a gut microbe causes flies to live fast and die young

Researchers have uncovered how one species of gut bacteria causes fruit flies to perish early. This discovery illuminates the complex interactions between the microbes in our guts and our health.

The human gut is home to somewhere between 200 and 1,000 species of bacteria. The vast majority of these species are beneficial, converting food into useful compounds that the human body cannot make by itself. But some bacterial species have a negative impact on health.

The sheer number of bacterial species in the human gut makes it extremely challenging to untangle their individual effects on our health. Researchers find it much simpler to look at the gut microbiome of fruit flies since they only have about two to five bacterial species in their guts.

In a previous study, researchers have found that one of these species, Acetobacter persici, accelerated aging in flies, causing them to die early. A. persici has a drastic impact on fly lifespan, curtailing it by about 20%–30%.

Now, by feeding flies with a diet of dead A. persici, scientists have discovered the connection between A. persici and shortened fly lifespans.

To their surprise, the researchers found that the shortened lifespan is not due to a compound produced by A. persici. Rather, a component in the bacterium's cell wall triggers a receptor in the fly's gut, which stimulates the immune system, boosting the production of antimicrobial compounds and activating intestinal stem cells. It's this enhanced immunity that causes the flies to die young. In an intriguing twist, the team discovered that these effects also boost a fly's resistance to infection by a harmful bacterium that can kill flies. It thus provides flies with a short-term advantage in exchange for an early death—a tradeoff that the researchers dubbed a "live fast, die young" lifestyle.

This increased resistance to infection explains why the vast majority of flies in the wild have A. persici or other Acetobacter species in their guts. It's better to have a strong resistance to stressors such as infection rather than to live to a ripe old age.

The finding raises the possibility that "postbiotics"—food and drinks that contain dead gut microbes (rather than prebiotics containing live ones)—with health benefits could be developed.

The team now aims to determine the genes involved in the immune signaling that leads to shorter lifespans. They also want to see if the same mechanism occurs in other animals such as mice and humans.

Taro Onuma et al, Recognition of commensal bacterial peptidoglycans defines Drosophila gut homeostasis and lifespan, PLOS Genetics (2023). DOI: 10.1371/journal.pgen.1010709

Comment by Dr. Krishna Kumari Challa on July 29, 2023 at 7:27am

Scientists discover secret of virgin birth, and switch on the ability in female flies

For the first time, scientists have managed to induce virgin birth in an animal that usually reproduces sexually: the fruit fly Drosophila melanogaster.

Once induced in this fruit fly, this ability is passed on through the generations: The offspring can reproduce either sexually if there are males around, or by virgin birth if there aren't.

For most animals, reproduction is sexual—it involves a female's egg being fertilized by a male's sperm. Virgin birth, or "parthenogenesis," is the process by which an egg develops into an embryo without fertilization by sperm—a male is not needed. The offspring of a virgin birth are not exact clones of their mother but are genetically very similar, and are always female.

This work 's the first to show that you can engineer virgin births to happen in an animal—it was very exciting to see a virgin fly produce an embryo able to develop to adulthood, and then repeat the process.

In the genetically manipulated flies, the females waited to find a male for half their lives—about 40 days—but then gave up and proceeded to have a virgin birth.

In the experiments, only 1–2% of the second generation of female flies with the ability for virgin birth produced offspring, and this occurred only when there were no male flies around. When males were available, the females mated and reproduced in the normal way.

Switching to a virgin birth can be a survival strategy: A one-off generation of virgin births can help to keep the species going.

To achieve their results, researchers first sequenced the genomes of two strains of another species of fruit fly, called Drosophila mercatorum. One strain needs males to reproduce, the other reproduces only through virgin birth. The researchers identified the genes that were switched on or switched off when the flies were reproducing without fathers.

With the candidate genes for virgin birth ability identified in Drosophila mercatorum, the researchers altered what they thought were the corresponding genes in the model fruit fly, Drosophila melanogaster. It worked: Drosophila melanogaster suddenly acquired the ability for virgin birth.

The research involved over 220,000 virgin fruit flies and took six years to complete.

More information: Alexis L Sperling, A genetic basis for facultative parthenogenesis in Drosophila, Current Biology (2023). DOI: 10.1016/j.cub.2023.07.006. www.cell.com/current-biology/f … 0960-9822(23)00913-2

Comment by Dr. Krishna Kumari Challa on July 28, 2023 at 12:42pm

Long Hot July
Science articles have had their own recurring theme in recent weeks: extreme heat. An expert recently said,  “I’m feeling like a broken record about heat breaking records.” As if to further her point, today she gathered a list of the latest all-time high temps–ALL set in 2023. To cap it off, this July is set to be the hottest month ever recorded on Earth—and likely the hottest in about 120,000 years—preliminary analyses show.

What's causing this: Breaking high-temperature records is a hallmark of climate change. With more and more heat being trapped in the atmosphere by the greenhouse gases emitted when humans burn fossil fuels, heat records are now set increasingly more often than cold ones.

The solution is to ditch fossil fuels as soon as possible and to build up our use of renewable energy. Easier said than done, yes, but if extreme weather is the sweltering, flooding, hurricaning canary in the coal mine we know it to be, the urgency to make change is ramping up.

Then follow all that experts say. 

Comment by Dr. Krishna Kumari Challa on July 28, 2023 at 10:17am

However, not all vegetarian diets are alike

Vegetarian meals marketed for convenience may be high in calories, refined carbohydrates, hydrogenated oils, high-fructose corn syrup, sucrose or artificial sweeteners and salt.

A higher risk of CVD and diabetes is possible on a vegetarian diet if the veggies pass through a deep fryer first. Foods rich in trans fatty acids and salt are associated with a 32% higher risk of coronary heart disease and a high risk of type 2 diabetes.

While a meta-analysis of 20 past trials cannot control for the wide range of diets included in those studies, which ranged from vegan to vegetarian (allowing for eggs and dairy), the overall signal from these diverse vegetarian diets was clear.

The vegetarian diet is associated with significant improvements in LDL-C, HbA1c (glucose level) and body weight in individuals with type 2 diabetes or at high risk of CVDs.

The data suggests that vegetarian diets might have a synergistic (or at least nonantagonistic) use in potentiating the effects of optimal drug therapy in the prevention and treatment of a range of cardiometabolic diseases.

So these things must be understood properly before going for a vegetarian diet.

Tian Wang et al, Vegetarian Dietary Patterns and Cardiometabolic Risk in People With or at High Risk of Cardiovascular Disease, JAMA Network Open (2023). DOI: 10.1001/jamanetworkopen.2023.25658

Part 2

Comment by Dr. Krishna Kumari Challa on July 28, 2023 at 10:16am

Meta-analysis finds vegetarian diets effective in lowering cholesterol, glucose and weight

Researchers have conducted a metadata analysis on vegetarian diets' effect on people at high risk of cardiovascular diseases (CVDs). They found that the vegetarian diet was associated with significantly improved LDL-cholesterol, HbA1c (glucose level) and body weight.

In their paper, "Vegetarian Dietary Patterns and Cardiometabolic Risk in People With or at High Risk of Cardiovascular Disease: A Systematic Review and Meta-analysis," published in JAMA Network Open, the researchers present a systematic review and meta-analysis of randomized clinical trials (RCTs) on vegetarian diets' effects in individuals with or at high risk of CVDs. It aimed to assess the association of vegetarian diets with outcomes, including LDL-C, HbA1c, SBP, body weight and energy intake.

In analyzing the data from 29 studies on 20 randomized clinical trials over 22 years with 1,878 total participants, the researchers found consistently positive outcomes for participants on vegetarian diets. The studies used were mainly conducted in the U.S. and also included studies from the Czech Republic, Italy, Iran, Korea, New Zealand, and the Republic of China. Within the metadata were subsets of study parameters that all followed a similar result trend. Compared with participants' usual diet, vegetarian intervention diets significantly lowered LDL-C by 12.9 mg/dL. Compared with external control diets, consuming a vegetarian diet was associated with decreased LDL-C by 6.6 mg/dL in a mean of six months.

Vegetarian diets were associated with similar LDL-C reduction in studies with (−7.2 mg/dL) and without (−6.8 mg/dL) energy restriction involved. Vegetarian diets even lowered LDL-C (−5.9 mg/dL) in a subset of studies with no physical activity intervention or requirements.

The most consistent weight reduction was observed in people at high risk of CVDs (−9.1 mg/dL). Among all different vegetarian diets, lacto-ovo (including dairy and egg) vegetarian diets were associated with the greatest reduction in LDL-C.

The most significant weight reduction was observed in people at high risk of CVD (−3.6), followed by people with type 2 diabetes (−2.8 kg). An unexpected signal between restricted and unrestricted caloric studies observed more than twice the weight reduction in vegetarian intervention diets without energy restriction.

Those with unrestricted (vegetarian) calorie intake lost an average of 4.7 kg compared to 1.8 kg for those with energy-restricted vegetarian diets. It is unclear if this indicates additional benefits of an all-you-can-eat vegetarian diet, specific limitations on the type of foods available, or hidden high-calorie deviations from participants on restrictive diets.

Part 1

Comment by Dr. Krishna Kumari Challa on July 27, 2023 at 1:33pm

Man Tests Positive For MERS-CoV in Abu Dhabi, WHO Reports

A man has tested positive for MERS-CoV in Abu Dhabi, the WHO. So far, the 28-year-old is the only case to test positive out of 108 close contacts identified, but the WHO is urging vigilance.

MERS‐CoV is a coronavirus first identified in the Middle East in 2012 after the virus made its way into humans from bats via camels. It's one of a number of zoonotic viruses (those that jump from animals into people) that health authorities keep close tabs on. The WHO was notified of the confirmed case by the United Arab Emirates' health surveillance body on July 10, 17 days after the young man tested positive in hospital on June 23. In light of the case, WHO "re-emphasizes the importance of strong surveillance" for acute respiratory infections and has urged health authorities to "carefully review any unusual patterns."

"No secondary cases have been detected to date," WHO's July 24 statement reads, although the organization expects additional cases will be reported from the Middle East or other countries where the virus circulates in animal hosts.

According to the WHO, the man had not recently traveled outside of the UAE before his diagnosis on June 23, and has no known history of direct contact with dromedary camels, the usual source of MERS infections.

"WHO continues to monitor the epidemiological situation and conducts risk assessments based on the latest available information," the statement reads.

https://www.who.int/emergencies/disease-outbreak-news/item/2023-DON478

Comment by Dr. Krishna Kumari Challa on July 27, 2023 at 1:27pm

Link Between Vitamin D And Psoriasis Severity

Vitamin D deficiency or lower vitamin D levels are associated with a significant increase in the severity of psoriasis, according to new research on nearly 500 cases, one of the largest studies yet. These findings suggest people with the irritating skin condition that affects millions of people may benefit from vitamin D-rich foods or supplements. Psoriasis is an immune-mediated disease characterized by an abnormally fast turnover of skin cells, and its exact cause is unclear. It's thought to arise from a genetic predisposition triggered by environmental factors. Anyone who experiences its chronic buildup of dead cells, which causes itchy, scaly patches, knows psoriasis can be painful and involve more than just physical health. Some people even wrongly assume it's contagious. Scientists think vitamin D plays a role in preventing the progression of skin diseases by modulating the immune response and acting directly on the skin's repair cells. The researchers used self-reported psoriasis-affected body surface area to measure the severity of the disease in each individual. They also collected data on vitamin D levels from blood samples. After adjusting the data to account for lifestyle factors like age, gender, race, BMI, and smoking habits, the analysis found that people with lower vitamin D levels had significantly more severe psoriasis. Those with more psoriasis-affected body surface area had lower average vitamin D levels. On the other hand, the less affected someone's skin was by psoriasis, the higher their average vitamin D levels were. This relationship suggests that vitamin D might affect how psoriasis develops and progresses. Vitamin D deficiency has been previously linked with an increased risk of depression and COVID-19 mortality, while supplementation, when levels are inadequate, may reduce heart attack risk and ease depressive symptoms.

The study has been presented at the annual meeting of the American Society for Nutrition, NUTRITION 2023.

Comment by Dr. Krishna Kumari Challa on July 27, 2023 at 10:37am

Egg 'signatures' allow drongos to identify cuckoo 'forgeries' almost every time, study finds

African cuckoos may have met their match with the fork-tailed drongo, which scientists predict can detect and reject cuckoo eggs from their nest on almost every occasion, despite them on average looking almost identical to drongo eggs.

Fork-tailed drongos, belligerent birds from sub-Saharan Africa, lay eggs with a staggering diversity of colors and patterns. All these colors and patterns are forged by the African cuckoo. Through natural selection, the African cuckoo's eggs have evolved to look almost-identical to drongo eggs—a rare example of high-fidelity mimicry in nature.

African cuckoos lay their eggs in drongos' nests to avoid rearing their chick themselves (an example of so-called brood parasitism). By forging drongo egg colors and patterns, cuckoos trick drongos into thinking the cuckoo egg is one of their own.

But drongos use knowledge of their own personal egg "signatures"—their eggs' color and pattern –to identify cuckoo egg "forgeries" and reject them from their nests, say scientists. These "signatures" are like the signatures we use in our daily lives: unique to each individual and highly repeatable by the same individual.

--- 

Researchers 

found that despite near-perfect mimicry of fork-tailed drongo eggs, African cuckoo eggs still have a high probability of being rejected.

Researchers carried out field work in the Choma district of Zambia during September to November across four years. The first step was to measure the differences in color and pattern of the fork-tailed drongo eggs and cuckoo eggs. The team found that the color and pattern of cuckoo eggs was, on average, almost identical to that of drongo eggs, and that all the broad types of drongo egg signatures were forged by the cuckoos.

The second step involved "egg rejection" experiments in which the researchers simulated cuckoo visits by "parasitizing" drongo nests with foreign eggs from other drongo nests (as a proxy for African cuckoo eggs). They then checked the nest daily to see whether the drongo parents accepted the foreign egg as one of their own, or realized it was an imposter and rejected it by removing it from their nest. The team could then test what differences in color and pattern between the foreign egg and the drongo's own eggs best predicted whether or not the drongo parents were tricked.

By combining results from both steps of the study, the researchers were able to create a model that predicted how often, on average, an African cuckoo would have its eggs rejected by a fork-tailed drongo host. They found the predicted rate of rejection to be 93.7%.

Additional simulations show this is likely due to drongos having evolved 'signatures' on their eggs. Even though cuckoos have evolved excellent 'forgeries,' individual cuckoos don't target individual drongo nests that match their own eggs. This means that for each cuckoo  egg laid, the likelihood that it will be a good enough match to that drongo's 'signature' is very low."

Lund et al. When perfection isn't enough: host egg signatures are an effective defence against high-fidelity African cuckoo mimicry, Proceedings of the Royal Society B: Biological Sciences (2023). DOI: 10.1098/rspb.2023.1125. royalsocietypublishing.org/doi … .1098/rspb.2023.1125

Comment by Dr. Krishna Kumari Challa on July 26, 2023 at 12:32pm

Gloomy climate calculation: Scientists predict a collapse of the Atlantic ocean current to happen mid-century

Important ocean currents that redistribute heat, cold and precipitation between the tropics and the northernmost parts of the Atlantic region will shut down around the year 2060 if current greenhouse gas emissions persist. This is the conclusion based on new calculations from the scientists that contradict the latest report from the IPCC.

Contrary to what we may imagine about the impact of climate change in Europe, a colder future may be in store. In a new study, published in Nature Communications, researchers from the University of Copenhagen's Niels Bohr Institute and Department of Mathematical Sciences predict that the system of ocean currents which currently distributes cold and heat between the North Atlantic region and tropics will completely stop if we continue to emit the same levels of greenhouse gases as we do today.

Using advanced statistical tools and ocean temperature data from the last 150 years, the researchers calculated that the ocean current, known as the Thermohaline Circulation or the Atlantic Meridional Overturning Circulation (AMOC), will collapse—with 95% certainty—between 2025 and 2095. This will most likely occur in 34 years, in 2057, and could result in major challenges, particularly warming in the tropics and increased storminess in the North Atlantic region. "Shutting down the AMOC can have very serious consequences for Earth's climate, for example, by changing how heat and precipitation are distributed globally. While a cooling of Europe may seem less severe as the globe as a whole becomes warmer and heat waves occur more frequently, this shutdown will contribute to an increased warming of the tropics, where rising temperatures have already given rise to challenging living conditions.

"This result underscores the importance of reducing global greenhouse gas emissions as soon as possible," says the researchers.

The calculations contradict the message of the latest IPCC report, which, based on climate model simulations, considers an abrupt change in the thermohaline circulation very unlikely during this century.

Peter Ditlevsen, Warning of a forthcoming collapse of the Atlantic meridional overturning circulation, Nature Communications (2023). DOI: 10.1038/s41467-023-39810-w. www.nature.com/articles/s41467-023-39810-w

Comment by Dr. Krishna Kumari Challa on July 25, 2023 at 12:48pm

Dementia risk linked to protein imbalance
Abnormal levels of certain proteins — most of which have functions unrelated to the brain — could be an early hallmark of Alzheimer’s disease. In a decades-long study of more than 10,000 people, unbalanced levels of 32 proteins during middle age were strongly associated with an elevated chance of developing dementia in later life. Some of the proteins showed changes only in blood plasma but not in brain tissue, which suggests that “mechanisms below the neck could also play a role”, says neurologist Nicholas Seyfried.

https://www.science.org/doi/10.1126/scitranslmed.adf5681

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