Comment

Comment by Dr. Krishna Kumari Challa on September 18, 2021 at 10:38am

Mass extinction: A warning that this can happen now too

The end-Permian mass extinction event of roughly 252 million years ago—the worst such event in earth's history—has been linked to vast volcanic emissions of greenhouse gases, a major temperature increase, and the loss of almost every species in the oceans and on land.

Now, it seems that even the lakes and rivers were no safe havens. A recent study published by an international team of researchers  has identified a new cause of extinction during extreme warming events: toxic microbial blooms.

In a healthy ecosystem, microscopic algae and cyanobacteria provide oxygen to aquatic animals as a waste product of their photosynthesis. But when their numbers get out of control, these microbes deplete free oxygen, and even release toxins into the water. By studying the fossil, sediment, and chemical records of rocks near Sydney, Australia, the researchers discovered that several pulses of bloom events had occurred soon after the first volcanic rumblings of the end-Permian mass extinction. Once the bottom-feeder animals, or "detritivores," were killed off, there was no one left to keep the microbes in check. The fresh water systems then seethed with algae and bacteria, delaying the recovery of animals for perhaps millions of years.

We're seeing more and more toxic algae blooms in lakes and in shallow marine environments that's related to increases in temperature and changes in plant communities which are leading to increases in nutrient contributions to freshwater environments. So, a lot of parallels to today. The volcanism was a source of CO₂ in the past but we know that the rate of CO₂ input that was seen back then was similar to the rate of CO₂ increases we're seeing today because of anthropogenic effects.

We can get a sense of how much climate has changed in the past, what the extremes are, how fast it can change, what the causes of climate change are and that gives us a nice backdrop for understanding what's happening today. The end-Permian is one of the best places to look for parallels with what's happening now.

The other big parallel is that the increase in temperature at the end of the Permian coincided with massive increases in forest fires. One of the things that that destroyed whole ecosystems was fire, and we're seeing that right now in several  places .

We should be concerned like hell!

Chris Mays et al, Lethal microbial blooms delayed freshwater ecosystem recovery following the end-Permian extinction, Nature Communications (2021). DOI: 10.1038/s41467-021-25711-3

https://phys.org/news/2021-09-animals-died-toxic-soup-earth.html?ut...

Comment by Dr. Krishna Kumari Challa on September 18, 2021 at 10:28am

How to make dormant seeds to germinate

Seeds that would otherwise lie dormant will spring to life with the aid of a new chemical discovered by researchers. 

Plants have the ability to perceive drought. When they do, they emit a hormone that helps them hold on to water. This same hormone, ABA, sends a message to seeds that it isn't a good time to germinate, leading to lower crop yields and less food in places where it's hot—an increasingly long list as a result of climate change.

"If you block ABA, you mess with the chemical pathway that plants use to prevent seed germination. A new chemical, Antabactin, does exactly this. If we apply it,  dormant seeds will sprout.

Demonstrations of Antabactin's effectiveness are described in a new paper published in the Proceedings of the National Academy of Sciences.

Aditya S. Vaidya et al, Click-to-lead design of a picomolar ABA receptor antagonist with potent activity in vivo, Proceedings of the National Academy of Sciences (2021). DOI: 10.1073/pnas.2108281118

https://phys.org/news/2021-09-chemical-discovery-reluctant-seeds.ht...

Comment by Dr. Krishna Kumari Challa on September 18, 2021 at 10:19am

How do cells acquire their shapes?

 A new mechanism that a simple yeast cell uses to acquire its shape has been identified recently by researchers. 

When cells move or grow, they must add new membrane to those growth regions.

The process of membrane delivery is called exocytosis. Cells also must deliver this membrane to a specific location in order to maintain a sense of direction―called "polarization"―or grow in a coordinated manner.

Researchers have demonstrated that these processes are coupled: local excess of exocytosis causes some of the proteins attached to the membrane to move ('flow') away from the growth region. These proteins that move away mark the non-growing cell region, thus establishing a self-sustaining pattern, which gives rise to the tubular shape of these yeast cells. 

This is the first time that this mechanism for cell patterning―the process by which cells acquire spatial nonuniformities on their surfaces―has been identified.

 Cell patterning by secretion-induced plasma membrane flows, Science Advances (2021). DOI: 10.1126/sciadv.abg6718

https://phys.org/news/2021-09-cells-mechanism.html?utm_source=nwlet...

Comment by Dr. Krishna Kumari Challa on September 18, 2021 at 10:14am

The microbial molecule that turns plants into zombies

A newly discovered manipulation mechanism used by parasitic bacteria to slow down plant aging, may offer new ways to protect disease-threatened food crops.

Parasites manipulate the organisms they live off to suit their needs, sometimes in drastic ways. When under the spell of a parasite, some plants undergo such extensive changes that they are described as "zombies". They stop reproducing and serve only as a habitat and host for the parasitic pathogens.

Until now, there's been little understanding of how this happens on a molecular and mechanistic level.

Research from the Hogenhout group at the John Innes Centre and collaborators published in Cell, has identified a manipulation molecule produced by Phytoplasma bacteria to hijack plant development. When inside a plant, this protein causes key growth regulators to be broken down, triggering abnormal growth.

Phytoplasma bacteria belong to a group of microbes that are notorious for their ability to reprogramme the development of their host plants. This group of bacteria are often responsible for the 'witches' brooms' seen in trees, where an excessive number of branches grow close together.

These bushy outgrowths are the result of the plant being stuck in a vegetative "zombie" state, unable to reproduce and therefore progress to a 'forever young' status. Phytoplasmas are a spectacular example of how the reach of genes can extend beyond the organisms to impact surrounding environments.

The new findings show how the bacterial protein  known as SAP05 manipulates plants by taking advantage of some of the host's own molecular machinery.

This machinery, called the proteasome, usually breaks down proteins that are no longer needed inside plant cells. SAP05 hijacks this process, causing plant proteins that are important in regulating growth and development, to effectively be thrown in a molecular recycling centre.

Without these proteins, the plant's development is reprogrammed to favour the bacteria, triggering the growth of multiple vegetative shoots and tissues and putting the pause on the plant ageing.

Parasitic modulation of host development by ubiquitin-independent protein degradation, Cell www.cell.com/cell/fulltext/S0092-8674(21)01012-6. DOI: 10.1016/j.cell.2021.08.029

https://phys.org/news/2021-09-microbial-molecule-zombies.html?utm_s...

Comment by Dr. Krishna Kumari Challa on September 17, 2021 at 10:34am

Ebola virus in survivors can trigger outbreaks years after infection

Ebola survivors can relapse and trigger outbreaks at least five years after infection, and long-term follow-up of former patients is needed to prevent devastating flare-ups, according to new research.

Scientists already knew Ebola could lie dormant in survivors, who test negative because the virus is in tissue rather than circulating in the blood.

But analysis of an outbreak this year in Guinea, published Wednesday in the journal Nature, found these "virus reservoirs" can awaken and cause new infections and transmission years on.

To trace the source of the Guinea outbreak, which involved 16 confirmed cases, 12 of whom died, researchers analysed the genomes of samples from several patients.

Ebola outbreaks are usually thought to result from the virus "spilling" from an animal host to a human.

But the analysis showed the Guinea strain was virtually identical to that from a 2013-16 wave.

If the virus had been circulating actively in the community since then, it would have accumulated a certain number of mutations as it spread.

Instead, the 2021 virus had just 12 changes, "far fewer than would be expected... during six years of sustained human-to-human transmission".

That strongly suggests the source was reactivated virus that had lain dormant in a survivor.

This is the longest known time between the declared end of an epidemic and a viral resurgence.

How and why dormant Ebola virus suddenly awakens and sickens a person remains something of a mystery, though there are some tantalising clues.

Sometimes a spike in Ebola antibodies can be detected in survivors at a given time -- a possible sign that the body is responding to a resurgent virus.

Around two-thirds of Ebola survivors have high antibody levels even five years after infection, but "the question to pose is what happens if there's a resurgence in the people whose immunity has dropped.

https://www.nature.com/articles/d41586-021-02378-w

source: Agence France-Presse

https://researchnews.cc/news/8930/Ebola-virus-in-survivors-can-trig...

Comment by Dr. Krishna Kumari Challa on September 17, 2021 at 10:20am

References

1. 1.

   Xiao, X. et al. Sci. Rep. 11, 11898 (2021).

   PubMed Article Google Scholar 

2. 2.

   Wang, L. F. & Eaton, B. T. Curr. Top. Microbiol. Immunol. 315, 325–344 (2007).

   PubMed Google Scholar 

https://www.nature.com/articles/d41586-021-02519-1?utm_source=Natur...

part 4

Comment by Dr. Krishna Kumari Challa on September 17, 2021 at 10:20am

Many markets

If the virus did jump between animals and people on several occasions, the fact that lineages A and B are linked to people who visited different markets in Wuhan suggests that multiple individual animals, of one or more species, that were carrying a progenitor of SARS-CoV-2 could have been transported across Wuhan, infecting people in at least two locations.

A study published in June¹ found that live animals susceptible to SARS-CoV-2, such as raccoon dogs and mink, were sold in numerous markets in Wuhan. Previous studies² of the virus that caused severe acute respiratory syndrome (SARS) have concluded that it, too, probably jumped multiple times from animals to people.

The latest study, if verified, would mean that the scenario of a researcher accidentally being infected in a lab, and then spreading the virus to the population at large, would have had to happen twice, says Garry. It’s much more likely that the pandemic has its origins in the wildlife trade, he says.

To gather more evidence, the team behind the new analysis now plans to run computer simulations to test how well multiple spillovers would fit with the diversity of known SARS-CoV-2 genomes.

doi: https://doi.org/10.1038/d41586-021-02519-1

part 3

Comment by Dr. Krishna Kumari Challa on September 17, 2021 at 10:19am

Fine-tooth comb

They analysed 1,716 SARS-CoV-2 genomes in a popular online genome repository called GISAID that were collected before 28 February 2020, and identified 38 such ‘intermediate’ genomes.

But when they looked at the sequences more closely, they found that many of these also contained mutations in other regions of their genomes. And they say that these mutations are definitively associated with either lineage A or lineage B — which discredits the idea that the corresponding viral genomes date to an intermediate stage of evolution between the two lineages.

The authors suggest that a laboratory or computer error probably occurred in sequencing one of the two mutations in these ‘intermediate’ genomes. “The more we dug, the more it looked like, maybe we can’t trust any of the ‘transitional’ genomes,” says study co-author Michael Worobey, an evolutionary biologist at the University of Arizona in Tucson.

Such sequencing errors are not unusual, say researchers. Software can sometimes fill in gaps in the raw data with incorrect sequences, and viral samples can become contaminated, notes Richard Neher, a computational biologist at the University of Basel in Switzerland. “Such mishaps are not surprising,” he says. “Especially early in the pandemic, when protocols weren’t very established and people tried to generate data as fast as they could.”

Several researchers contacted by Nature, who sequenced some of the samples included in the study, say it is unlikely that their sequences include errors in the two key nucleotides.

But the study authors counter that even if some of the genomes were sequenced correctly, other parts of the same genomes, or the locations from which the samples were collected, still clearly indicate that they belong to only one or the other lineage.

“It is very unlikely” that any of the so-called intermediate genomes are actually transitional genomes, says study co-author

part2

Comment by Dr. Krishna Kumari Challa on September 17, 2021 at 10:18am

Did the coronavirus jump from animals to people twice?

A preliminary analysis of viral genomes suggests the COVID-19 pandemic might have multiple animal origins — but the findings still have to be peer reviewed.

SARS-CoV-2, the virus that causes COVID-19, could have spilled from animals to people multiple times, according to a preliminary analysis of viral genomes sampled from people infected in China and elsewhere early in the pandemic.

If confirmed by further analyses, the findings would add weight to the hypothesis that the pandemic originated in multiple markets in Wuhan, and make the hypothesis that SARS-COV-2 escaped from a laboratory less likely, say some researchers. But the data need to be verified, and the analysis has not yet been peer reviewed.

The earliest viral sequences, taken from people infected in late 2019 and early 2020, are split into two broad lineages, known as A and B, which have key genetic differences.

Lineage B has become the dominant lineage globally and includes samples taken from people who visited the Huanan seafood market in Wuhan, which also sold wild animals. Lineage A spread within China, and includes samples from people linked to other markets in Wuhan.

A crucial question is how the two viral lineages are related. If viruses in lineage A evolved from those in lineage B, or vice versa, that would suggest that the progenitor of the virus jumped just once from animals to people. But if the two lineages have separate origins, then there might have been multiple spillover events.

The latest analysis — posted on the virological.org discussion forum — adds weight to the second possibility by questioning the existence of genomes linking the lineages.

The finding could be the “dagger into the heart” of the hypothesis that SARS-CoV-2 escaped from a lab, rather than originating from the wildlife trade. If you can show that A and B are two separate lineages and there were two spillovers, it all but eliminates the idea that it came from a lab.

The findings are “consistent with there being at least two introductions of SARS-CoV-2 into the human population.

Lineages A and B are defined by two key nucleotide differences. But some of the earliest genomes have a combination of these differences. Researchers previously thought that these genomes could be those of viruses at intermediate stages of evolution linking the two lineages.

But the researchers behind the new analysis looked at them in detail and noticed some problems.

part 1

Comment by Dr. Krishna Kumari Challa on September 17, 2021 at 9:46am

Part of the universe's missing matter found

Galaxies can receive and exchange matter with their external environment thanks to the galactic winds created by stellar explosions. Via the MUSE instrument from the Very Large Telescope at the ESO, an international research team, led on the French side by the CNRS and l'Université Claude Bernard Lyon 1, has mapped a galactic wind for the first time. This unique observation, which is detailed in a study published in MNRAS on 16 September 2021, helped to reveal where some of the universe's missing matter is located and to observe the formation of a nebula around a galaxy.

Galaxies are like islands of stars in the universe, and possess ordinary, or baryonic, matter, which consists of elements from the periodic table, as well as dark matter, whose composition remains unknown. One of the major problems in understanding the formation of galaxies is that approximately 80% of the baryons that make up the normal matter of galaxies is missing. According to models, they were expelled from galaxies into inter-galactic space by the galactic winds created by stellar explosions.

An international team led on the French side by researchers from the CNRS and l'Université Claude Bernard Lyon successfully used the MUSE instrument to generate a detailed map of the galactic wind driving exchanges between a young galaxy in formation and a nebula (a cloud of gas and interstellar dust).

The perfect positioning of the galaxy and the quasar, as well as the discovery of gas exchange due to galactic winds, made it possible to draw up a unique map. This enabled the first observation of a nebula in formation that is simultaneously emitting and absorbing magnesium—some of the universe's missing baryons—with the Gal1 galaxy.

This type of normal matter nebula is known in the near universe, but their existence for young galaxies in formation had only been supposed.

Scientists thus discovered some of the universe's missing baryons, thereby confirming that 80–90% of normal matter is located outside of galaxies, an observation that will help expand models for the evolution of galaxies.

 Johannes Zabl et al, MusE GAs FLOw and Wind (MEGAFLOW) VIII. Discovery of a Mgii emission halo probed by a quasar sightline, Monthly Notices of the Royal Astronomical Society (2021). DOI: 10.1093/mnras/stab2165

https://phys.org/news/2021-09-universe.html?utm_source=nwletter&...

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