Comment

Comment by Dr. Krishna Kumari Challa on November 23, 2023 at 8:16am

Careful histological and morphological observations revealed that the stolon formation starts with the maturation of gonads in the posterior end. Then forms a head in the anterior part of the developing stolon. Sense organs such as eyes and antennae, and swimming bristles form soon after. Before the stolon detaches, it develops nerves and a 'brain' to sense and behave independently.

To understand the development of stolon's head, researchers investigated the developmental gene expression patterns of the sexually maturing worms. A well-known group of head formation genes are known to define the head region of various animals. They found that these genes are expressed more in the head region of the stolon. Typically, the head formation genes are not expressed as much in the middle of the body. But during gonad development in syllids, head formation genes are highly expressed in the middle of the posterior end of the original body.

This shows how normal developmental processes are modified to fit the life history of animals with unique reproductive styles.

Morphological, Histological and Gene-Expression Analyses on Stolonization in the Japanese Green Syllid, Megasyllis nipponica (Annelida, Syllidae), Scientific Reports (2023). DOI: 10.1038/s41598-023-46358-8

Part 2

Comment by Dr. Krishna Kumari Challa on November 23, 2023 at 8:14am

This sea worm's posterior swims away, and now scientists know how

Life always finds ways to surprise us. The presence of a unique reproductive mechanism in some annelid worms or segmented worms is one such surprise. In a process called stolonization, the posterior body part with gonads of the syllid worm detaches from its original body. The detached part is called the stolon, and it is full of gametes (eggs or sperm).

The stolon swims around by itself and spawns when it meets the opposite sex. Swimming autonomously would not only protect the original body from environmental dangers but could also help its gametes disperse over larger distances.

To swim autonomously, the stolons develop their own eyes, antennae, and swimming bristles while still attached to their original body. But how does the stolon head form in the middle of the original body?

Part 1

Comment by Dr. Krishna Kumari Challa on November 23, 2023 at 7:58am

Chlorine disinfectant is no more effective than water at killing off hospital superbug, new study shows

One of the primary chlorine disinfectants currently being used to clean hospital scrubs and surfaces does not kill off the most common cause of antibiotic-associated sickness in health care settings globally, according to a new study.

Research has shown that spores of Clostridioides difficile, commonly known as C. diff, are completely unaffected despite being treated with high concentrations of bleach used in many hospitals. In fact, the chlorine chemicals are no more effective at damaging the spores when used as a surface disinfectant—than using water with no additives. Writing in the journal Microbiology, the study's authors say susceptible people working and being treated in clinical settings might be unknowingly placed at risk of contracting the superbug.

As a result, and with incidence of biocide overuse only serving to fuel rises in antimicrobial resistance (AMR) worldwide, they have called for urgent research to find alternative strategies to disinfect C. diff spores in order to break the chain of transmission in clinical environments.

 Clostridioides difficile spores tolerate disinfection with Sodium hypochlorite disinfectant and remain viable within surgical scrubs and gown fabrics, Microbiology (2023). DOI: 10.1099/mic.0.001418

Comment by Dr. Krishna Kumari Challa on November 22, 2023 at 12:32pm

During this research work, when the hatchlings emerged, researchers recorded their sex and tested them for 18 heavy metals like cadmium and chromium, plus organic pollutants like polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs).

These contaminants are all known or suspected to function as 'xenoestrogens' or molecules that bind to the receptors for female sex hormones. Female turtles accumulate these contaminants at their foraging sites. As eggs develop within her, they absorb the contaminants that she accumulated and sequester them in the liver of the embryos, where they can stay for years after hatching.

the study found varying sex ratios among the different clutches, but most nests yielded predominantly female hatchlings, the researchers report.

And the degree of female bias in each nest showed an association with xenoestrogen levels in the hatchlings, they discovered: higher pollutant levels in hatchlings' livers correlated with a greater female bias in their nest.

More research is still needed to clarify whether these pollutants are contributing to differences in sex ratio, but the association already warrants concern, researchers say.

https://www.frontiersin.org/articles/10.3389/fmars.2023.1238837/full

Part 2

Comment by Dr. Krishna Kumari Challa on November 22, 2023 at 12:29pm

The World Is Running Out of Male Sea Turtles

Green sea turtles are already an endangered species, mainly due to humans hunting them, harvesting their eggs, degrading their habitats, or entangling them in garbage (fishing nets) of some kind.

But they also face another, more insidious threat from people: the loss of male hatchlings from the species.

You probably already know that this is partly caused by rising temperatures due to climate change – but a new study has now unveiled another human-caused problem driving this trend.

Certain pollutants may promote feminization in sea turtles. New research work  shows that the risk of extinction due to a lack of male green sea turtles may be compounded by contaminants that may also influence the sex ratio of developing green sea turtles, increasing the bias towards females.

Green sea turtles (Chelonia mydas) have a vast geographical range, inhabiting tropical, subtropical, and temperate regions of the Atlantic, Pacific, and Indian oceans, as well as the Mediterranean Sea.

Male hatchlings are now heavily outnumbered by females overall, although the degree of imbalance varies in different parts of their range. In some warmer places like the northern Great Barrier Reef, researchers say, hundreds of female turtles are now born for every male.

That's because sea turtles use temperature-dependent sex determination, meaning an embryo's sex is determined by sand temperatures around its egg in the nest, with warmer sand favoring females. As temperatures rise around the world, male hatchlings are growing scarce. But that's not the only factor involved in determining sex, the latest research suggests.

Part 1

Comment by Dr. Krishna Kumari Challa on November 22, 2023 at 11:34am

Gut microbes help alleviate constipation

Scientists have identified the genes in the probiotic Bifidobacteria longum responsible for improving gut motility. A research team reporting November 21 in the journal Cell Host & Microbe found that B. longum strains possessing the abfA cluster of genes can ameliorate constipation through enhanced utilization of an indigestible fiber called arabinan in the gut.

The researchers established the causal link between a genetic variant—the abfA cluster—to the key functional difference of probiotic B. longum in multiple model organisms, including mice and humans, and provided mechanistic and ecological insights into how a single gene cluster can affect the gut motility of hosts through arabinan metabolism.

Peter Kuffa et al, Fiber-deficient diet inhibits colitis through the regulation of the niche and metabolism of a gut pathobiont, Cell Host & Microbe (2023). DOI: 10.1016/j.chom.2023.10.016

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Solar panels vs planting forests: Which reduces climate change faster?

Photovoltaic fields outperform afforestation as a global climate-change mitigation strategy, according to a study published in the journal PNAS Nexus.

Comment by Dr. Krishna Kumari Challa on November 22, 2023 at 11:18am

How bloodstain 'tails' can point to significant, additional forensic details

Most of us know that evidence left at a crime scene, such as blood, can often reveal information that is key to investigating and understanding the circumstances around a crime—and that scientific methods can help interpret that information.

In the journal Physics of Fluids, a group of scientists   demonstrated how bloodstains can yield even more valuable details than what is typically gathered by detectives, forensic scientists, and crime scene investigators. By examining the protrusions that deviate from the boundaries of otherwise elliptical bloodstains, the researchers studied how these "tails" are formed. The article is titled "Bloodstain tails: Asymmetry aids reconstruction of oblique impact".

These protrusions are typically only used to get a sense of the direction that the drop traveled, but are otherwise neglected.

In fact, previous studies have primarily focused on larger blood drops falling vertically on flat surfaces or on inclined surfaces where gravity can reshape and obscure the tails. By contrast, the new study involved a series of high-speed experiments with human blood droplets with diameters of less than a millimeter impacting horizontal surfaces at various angles.

This new study shows that  the precise flow that determines the tail length differs from the flow responsible for the size and shape of the elliptical portion of the stain. "In other words, the tail lengths encompass additional independent information that can help analysts reconstruct where the blood drop actually came from."

Indeed, the tail length can reflect information about the size, impact speed, and impact angle of the blood drop that formed the stain. When measured for several blood stains in a stain pattern, the trajectories of the drops can be backtracked to their presumed origin.

Incorporating tail length into standard bloodstain analyses will produce more robust evidentiary information.

"Knowing the origin of the blood stains at a crime scene can help detectives determine whether a victim was standing or sitting, or help corroborate or question a witness's testimony.

Garam Lee et al, Bloodstain tails: Asymmetry aids reconstruction of oblique impact, Physics of Fluids (2023). DOI: 10.1063/5.0170124

Comment by Dr. Krishna Kumari Challa on November 22, 2023 at 11:06am

Unearthing how a carnivorous fungus traps and digests worms

A new analysis sheds light on the molecular processes involved when a carnivorous species of fungus known as Arthrobotrys oligospora senses, traps and consumes a worm. 

A. oligospora usually derives its nutrients from decaying organic matter, but starvation and the presence of nearby worms can prompt it to form traps to capture and consume worms. A. oligospora is just one of many species of fungi that can trap and eat very small animals.

When A. oligospora first senses a worm, the findings suggest, DNA replication and the production of ribosomes (structures that build proteins in a cell) both increase. Next, the activity increases of many genes that encode proteins that appear to assist in the formation and function of traps, such as secreted worm-adhesive proteins and a newly identified family of proteins dubbed "trap enriched proteins" (TEP).

Finally, after A. oligospora has extended filamentous structures known as hyphae into a worm to digest it, the activity is boosted by genes coding for a variety of enzymes known as proteases—in particular, a group known as metalloproteases. Proteases break down other proteins, so these findings suggest that A. oligospora uses proteases to aid in worm digestion.

These findings could serve as a foundation for future research into the molecular mechanisms involved in A. oligospora predation and other fungal predator-prey interactions.

Lin H-C, de Ulzurrun GV-D, Chen S-A, Yang C-T, Tay RJ, Iizuka T, et al. (2023) Key processes required for the different stages of fungal carnivory by a nematode-trapping fungus. PLoS Biology (2023). DOI: 10.1371/journal.pbio.3002400

Comment by Dr. Krishna Kumari Challa on November 22, 2023 at 11:00am

Babies as young as four months show signs of self-awareness: Study

Babies as young as four months old can make sense of how their bodies interact with the space around them, according to new research.

The findings, published in Scientific Reports, shed new light on how self-awareness develops. Experts  showed babies a ball on a screen moving towards or away from them. When the ball was closest to them on the screen, the babies were presented with a 'touch' (a small vibration) on their hands while their brain activity was being measured.  The researchers found that from just four months old, babies show enhanced somatosensory (tactile) brain activity when a touch is preceded by an object moving toward them.

These findings indicate that even in the first few months of life, before babies have even learned to reach for objects, the multisensory brain is wired up to make links between what babies see and what they feel. This means they can sense the space around them and understand how their bodies interact with that space. This is sometimes referred to as peripersonal space.

Of course, humans do this all the time as adults, using our combined senses to perceive where we are in space and making predictions about when we will touch an object or not. But now that we know that babies in the early stages of their development begin to show signs of this, it opens up questions about how much of these abilities are learned or innate.

Visual objects approaching the body modulate subsequent somatosensory processing at 4 months of age, Scientific Reports (2023). DOI: 10.1038/s41598-023-45897-4

Comment by Dr. Krishna Kumari Challa on November 22, 2023 at 10:55am

High temperatures may have caused over 70,000 excess deaths in Europe in 2022

The burden of heat-related mortality during the summer of 2022 in Europe may have exceeded 70,000 deaths according to a study .

The authors of the study, published in The Lancet Regional Health—Europe, revised upwards initial estimates of the mortality associated with record temperatures in 2022 on the European continent. The study is titled "The effect of temporal data aggregation to assess the impact of changing temperatures in Europe: an epidemiological modelling study."

Ballester J et al, The effect of temporal data aggregation to assess the impact of changing temperatures in Europe: an epidemiological modelling study, The Lancet Regional Health—Europe (2023). DOI: 10.1016/j.lanepe.2023.100779

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