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Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 12:22pm

Unlike female sexual traits, the loss of male sexual traits is generally thought to take an extremely long time. In many other species, even rare males often retain their reproductive capabilities. However, these findings suggest that R. mikado has relied solely on parthenogenesis for such an extended period that even neutral mutations have accumulated, leading to the complete loss of male reproductive traits.
This study demonstrates that parthenogenesis in R. mikado has become irreversible. Although asexual reproduction is often considered evolutionarily short-lived due to the lack of genetic recombination, previous research estimated that this species has persisted for hundreds of thousands of years. How has R. mikado managed to survive for such a long time? This remains an intriguing mystery for future research.

Tomonari Nozaki et al, Lack of successful sexual reproduction suggests the irreversible parthenogenesis in a stick insect, Ecology (2025). DOI: 10.1002/ecy.4522

Part 2

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 12:21pm

Study shows male stick insects have lost their reproductive function

While most animals reproduce sexually, some species rely solely on females for parthenogenetic reproduction. Even in these species, rare males occasionally appear. Whether these males retain reproductive functions is a key question in understanding the evolution of reproductive strategies.

A new study published in Ecology by a research team provides insight into this question. The researchers focused on the rare males of Ramulus mikado, a stick insect species in Japan, where parthenogenesis is predominant. Their analysis of male reproductive behavior reveals new findings.

Males engage in mating but do not contribute genetically. The rare males actively mated with females, just like typical males. However, genetic analysis confirmed that no male-derived genes were passed on to their offspring. The study further revealed that these males do not produce functional sperm, rendering them incapable of restoring sexual reproduction in the species.

Their findings showed that the males exhibited the typical morphological traits of stick insects and engaged in mating behaviors with conspecific females. However, despite their reproductive attempts, they were completely sterile. At the same time, the female reproductive organs associated with sexual reproduction showed signs of degeneration.

The rare males of this stick insect have completely lost their reproductive function.

Part 1

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 8:36am

Why babies recover, but adults scar, after heart damage

Newborns with heart complications can rely on their newly developed immune systems to regenerate cardiac tissues, but adults aren't so lucky. After a heart attack, most adults struggle to regenerate healthy heart tissue, leading to scar-tissue buildup and, often, heart failure.

A new  study in experimental animals reveals a critical difference in how macrophages—a part of the immune system—help repair the heart in newborns versus adults after a heart attack. The study highlights a fundamental difference in how the immune system drives healing based on age.

The study is published in the journal Immunity.

In newborns, macrophages perform a process called efferocytosis, which recognizes and eats dying cells. This process triggers the production of a bioactive lipid called thromboxane, signaling nearby heart muscle cells to divide, and allowing the heart to regenerate damaged heart muscle, the study found. In adults, macrophages produce much less thromboxane, leading to a weaker repair signal.

"By mimicking the effects of thromboxane, we might one day improve tissue repair after a heart attack in adults," the researchers say.

Early Age Efferocytosis Directs Macrophage Arachidonic Acid Metabolism for Tissue Regeneration, Immunity (2025).

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 8:21am

As expected, the engineered bacteria localized specifically in the olfactory epithelium and released their payloads into adjacent brain regions. Mice fed a high-fat diet and treated with hormone-secreting bacteria exhibited reduced body weight gain, lower food consumption, improved glucose tolerance and diminished adipose tissue deposition compared with control groups.

Findings further indicated that leptin secreted by the bacteria persisted in the olfactory epithelium longer than recombinant leptin delivered intranasally.

Results support the method's potential as a noninvasive vector for brain-targeted therapies. While the study used an appetite-regulating hormone, this delivery system could be adapted for neurological conditions such as Parkinson's disease, Alzheimer's, and brain cancers, where drug penetration into the brain remains a major hurdle.

Haosheng Shen et al, Engineered commensals for targeted nose-to-brain drug delivery, Cell (2025). DOI: 10.1016/j.cell.2025.01.017

Part 2

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 8:20am

Crossing the blood–brain barrier with a payload via engineered bacteria

Researchers  have reported crossing the blood–brain barrier with help from a modified Lactobacillus plantarum. By delivering an appetite-regulating hormone directly to the olfactory epithelium, the hormone was able to reach its target.

Only the secreted hormone molecules crossed into the brain. Engineered Lactobacillus plantarum remained in the nasal passage, where it released its therapeutic payload, which then diffused along the olfactory pathway into the brain.

Current approaches to treating neurological conditions suffer from the highly protective nature of the blood–brain barrier. Intranasal therapies often encounter rapid clearance without a sustained therapeutic delivery.

In the study "Engineered Commensals for Targeted Nose-to-Brain Drug Delivery," published in Cell, researchers address these challenges by exploiting L. plantarum's natural affinity for the olfactory epithelium.
L. plantarum was chosen as a delivery vector as it naturally localizes to the olfactory epithelium binding sites. Initial investigations involved engineering L. plantarum to express and secrete hormones such as leptin, alpha-melanocyte-stimulating hormone and brain-derived neurotrophic factor (BDNF).

Experiments incorporated in vitro models using nasal cell monolayers and in vivo studies with male mice aged 6 to 8 weeks. Intranasal administration of fluorescent-labeled bacteria allowed visualization of bacterial localization.

Part 1

Comment by Dr. Krishna Kumari Challa on February 11, 2025 at 12:03pm

Mitochondria's role in diabetes

Mitochondria are essential for generating energy that fuels cells and helps them function.

Mitochondrial defects, however, are associated with the development of diseases such as type 2 diabetes. Patients who suffer from this disorder are unable to produce enough insulin or use the insulin produced by their pancreas to keep their blood sugar at normal levels.

Several studies have shown that insulin-producing pancreatic β-cells of patients with diabetes have abnormal mitochondria and are unable to generate energy. Yet, these studies were unable to explain why the cells behaved this way.

In a study published in Science, researchers used mice to show that dysfunctional mitochondria trigger a response that affects the maturation and function of β-cells.

The researchers also confirmed their findings in human pancreatic islet cells.

Mitochondrial dysfunction affects several types of cells

Their results prompted the team to expand their search into other cells that are affected during diabetes.

Reversing mitochondrial damage could help cure diabetes

Regardless of the cell type, the researchers found that damage to the mitochondria did not cause cell death.

This observation brought up the possibility that if they could reverse the damage, the cells would function normally.

To do so, they used a drug called ISRIB that blocked the stress response. They found that after four weeks, the β-cells regained their ability to control glucose levels in mice.

Losing your β-cells is the most direct path to getting type 2 diabetes. Through this study we now have an explanation for what might be happening and how we can intervene and fix the root cause.

Emily M. Walker et al, Retrograde mitochondrial signaling governs the identity and maturity of metabolic tissues, Science (2025). DOI: 10.1126/science.adf2034

Comment by Dr. Krishna Kumari Challa on February 11, 2025 at 11:50am

Nocturnal carnivores became more active during the day
The study took place at the Ongava Research Center in Namibia, a country in Southern Africa. It is a nature reserve that borders a national park, where tourists have a heavy presence.
During the dry season, animals on the reserve depend on man-made waterholes. With so few sources of water, this gave researchers a reliable spot to set up camera traps and document animal activity.

Photos were taken three days before humans came, three days while they were at the waterholes and three days after they left. Researchers did this for two years.
Four major carnivore species—the spotted hyena, black-backed jackal, brown hyena and African lion—came to the waterhole more during the day. Usually, these predators rule the night, and are less active during the day.
Having humans at the waterholes at night, when they typically aren't there, maybe threw the animals off a bit and made them nervous, say teh researchers .
Since carnivores in the area already knew humans would be around during the day, they may have felt more comfortable getting water then instead of at night when tourists usually aren't at waterholes.
Predators and prey could cross paths more often
Some herbivores also changed their schedule. The duiker, springbok, mountain zebra and plains zebra started to visit the waterholes at night, despite being more comfortable around people.

This change was likely to avoid the carnivores that started visiting the waterhole during the day. But not all herbivores made the switch.

There are many other herbivore species that are still active during the day and overlap with those carnivores now.
That can change the dynamics of the ecosystem, and some animals could get preyed upon during times of the day when they usually feel safer.
Tourism still essential for wildlife conservation
Outside of shifting schedules, the presence of humans may be stressful for some animals.

Even so, tourism remains an essential tool for bringing attention and money to wildlife conversation, the researchers said. It also offers employment and a source of income to many people, especially in rural regions.

But it also takes a very pristine environment and brings people into it.
We must understand how tourism is affecting these eco systems to protect them efficiently.

J. R. Patterson et al, Effects of human presence on African mammal waterhole attendance and temporal activity patterns, Journal of Zoology (2024). DOI: 10.1111/jzo.13245

Part 2

Comment by Dr. Krishna Kumari Challa on February 11, 2025 at 11:45am

Human presence at waterholes may change animal behavior

When tourists venture into nature, their thoughts are often focused on the animals they'll get to see. But animals may also have them in mind, according to a new study from the University of Georgia published in the Journal of Zoology.

With how common tourism is becoming, humans and animals will cross paths more often. Not only are tourists coming to watch the animals, but researchers will also stay out for long periods of time to count populations of different species.

As such, the study focused on how humans being nearby influenced the behavior of African mammals, including lions and zebras, while at waterholes.

When humans are present, some animals shift their daily activity patterns. the carnivores changed because of the human presence, and the herbivores changed because of the carnivore presence. It was not just one species that altered their behavior.

The study used a series of camera traps that took photos once animals walked by. Based on these pictures, researchers determined when and how often animals were visiting waterholes.

When humans were around, the time of day when some mammals came to the waterhole would shift compared to periods when humans weren't present. Some would visit earlier, while others visited later.

Animals shifting schedules can lead to different species interacting when they usually wouldn't—something that's especially a problem for some herbivores that could run into predators who typically aren't active during those times of the day.

Because of how important tourism is for conservation and income, the researchers emphasized the need to consider how human activity can impact animals on a larger scale.

Part 1 

Comment by Dr. Krishna Kumari Challa on February 11, 2025 at 11:41am

This work focuses on the study of the genome of the Oikopleura dioica species, a swimming organism of the marine zooplankton that belongs to the tunicates—a sister group of vertebrates—and is phylogenetically linked to evolutionary history. In this study model—a free-living tunicate or appendicularian—the team reconstructed the evolutionary history of fibroblast growth factor (FGF) gene families, which are critical in the developmental process of organisms.

"The findings suggest that the process of gene loss reduced the number of FGF growth factor gene families from eight to just two, which are the Fgf9/16/20 and Fgf11/12/13/14 families. These surviving subfamilies have doubled over the course of evolution to generate a total of 10 genes in appendicularians.
The "less, but more" evolutionary model "helps us to understand how sometimes losing opens up new possibilities for subsequent gains and, therefore, losses are necessary to favor the evolutionary origin of new adaptations

Gaspar Sánchez-Serna et al, Less, but More: New Insights From Appendicularians on Chordate Fgf Evolution and the Divergence of Tunicate Lifestyles, Molecular Biology and Evolution (2024). DOI: 10.1093/molbev/msae260

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Part 2

Comment by Dr. Krishna Kumari Challa on February 11, 2025 at 11:39am

Less, but more: A new evolutionary scenario marked by massive gene loss and expansion

Evolution is traditionally associated with a process of increasing complexity and gaining new genes. However, the explosion of the genomic era shows that gene loss and simplification is a much more frequent process in the evolution of species than previously thought, and may favor new biological adaptations that facilitate the survival of living organisms.

This evolutionary driver, which seems counter-intuitive—"less is more" in genetic terms—now reveals a surprising dimension that responds to the new evolutionary concept of "less, but more," i.e., the phenomenon of massive gene losses followed by large expansions through gene duplications.

This is one of the main conclusions of an article published in the journal Molecular Biology and Evolution.

The paper identifies new evolutionary patterns, and it outlines a new scenario, marked by the enormous potential for genetic change and evolutionary adaptation driven by large-scale gene loss and duplication in living organisms.

Gene loss is a widespread mechanism throughout the biological scale and represents an evolutionary driving force that can generate genetic variability and also biological adaptations, and this has traditionally been known as the 'less is more' hypothesis.

Now, the paper describes a new evolutionary framework called "less, but more," which extends the previous model in terms of the importance of gene loss as an evolutionary driving force.

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