The microbes that eventually produced the planet's oxygen had to breathe something, after all.
- We owe the Earth's oxygen to ancient microbes that photosynthesized and released it into the world's oceans.
- A long-standing question has been: Before oxygen, what did they breathe?
- The discovery of microbes living in a hostile early-Earth-like environment may provide the answer.
Unassuming but remarkable microbial mats<p> Photosynthesis chiefly requires sunlight, water, and CO<sup>2</sup>. The CO<sup>2</sup> gets broken down into carbon and oxygen — the plant uses some of this oxygen and releases the rest. Without oxygen molecules, though, how did this work? </p><p> There are known microbial mats today that live in oxygen-free environments, but they're not thought to be sufficiently like their ancestors to explain ancient photosynthesis in an oxygen-free environment. </p><p> There have been a few oxygen stand-ins proposed. Photosynthesis can work with iron molecules, but fossil-record evidence doesn't support that idea. Hydrogen and sulphur have also been proposed, though evidence for them is also lacking. </p><p> The spotlight began to shift to arsenic in the first decade of the millennium when arsenic-breathing microbial mats were discovered in two hypersaline California lakes, <a href="https://science.sciencemag.org/content/308/5726/1305.abstract" target="_blank">Searles Lake</a> and <a href="https://www.discovermagazine.com/planet-earth/mono-lake-bacteria-build-their-dna-using-arsenic-and-no-this-isnt-about-aliens" target="_blank" rel="noopener noreferrer">Mono Lake</a>. In 2014, Visscher and colleagues <a href="https://www.nature.com/articles/ngeo2276" target="_blank">unearthed indications</a> of arsenic-based photosynthesis, or "arsenotrophic," microbial mats deep in the fossil record of the Tumbiana Formation of Western Australia. </p><p> Still, given the ever-shifting geology of the planets, the fractured ancient fossil record makes definitive study of ancient arsenotrophic photosynthesis difficult. The fossil record can't identify the role of the arsenic it reveals: was it involved in photosynthesis or just a toxic chemical that happened to be there? </p><p>Then, last year, arsenic-breathing microorganisms <a href="https://www.washington.edu/news/2019/05/01/arsenic-breathing-life-discovered-in-the-tropical-pacific-ocean/" target="_blank" rel="noopener noreferrer">were discovered</a> in the Pacific Ocean. A sulphur bacterium, <em>Ectothiorhodospira sp.</em> was also recently found to be metabolizing arsenic into <a href="https://en.wikipedia.org/wiki/Arsenite" target="_blank">arsenite</a> in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5064118/" target="_blank" rel="noopener noreferrer">Big Soda Lake</a> in Nevada. </p>
An ancient Earth environment, today<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ0NzIxMC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1OTQwOTYyN30.v96ZRXpIAf4yzDwcvXzVV3Fa4qULtUMxanXguPHD2wI/img.jpg?width=980" id="9eec4" class="rm-shortcode" data-rm-shortcode-id="a23585c057ee50ed500b96125e4a6b05" data-rm-shortcode-name="rebelmouse-image" />
a Map of Northern Chile; b Detail of frame showing Laguna La Brava in the southern Atacama; c The channel showing the mats in purple; d Hand sample, cross-section; e Microscopic image of bacteria.
Credit: Visscher, et al./Communications Earth & Environment<p>The study reports on Visscher's discovery of a living microbial mat thriving in an arsenic environment in Laguna La Brava in the Atacama Desert in Chile. "We started working in Chile," Visscher tells <a href="https://today.uconn.edu/2020/09/without-oxygen-earths-early-microbes-relied-arsenic-sustain-life/" target="_blank"><em>UConn Today</em></a>, "where I found a blood-red river. The red sediments are made up by <a href="https://en.wikipedia.org/wiki/Anoxygenic_photosynthesis" target="_blank">anoxogenic</a> photosynthetic bacteria. The water is very high in arsenic as well. The water that flows over the mats contains hydrogen sulfide that is volcanic in origin and it flows very rapidly over these mats. There is absolutely no oxygen."</p><p>The mats had not previously been studied, and the conditions in which they live are tantalizingly similar to those of early Earth. It's a high-altitude, permanently oxygen-free state with extreme temperature swings and lots of UV exposure. </p><p>The mats that somewhat resemble Nevada's purple <em>Ectothiorhodospira sp.</em> are going about their business of making carbonate deposits, forming new stromatolites. Most excitingly, those deposits contain evidence that the mats are metabolizing arsenic. The rushing waters surrounding the mats are also rich in hydrogen sulphide and arsenic.</p><p>Says Visscher, "I have been working with microbial mats for about 35 years or so. This is the only system on Earth where I could find a microbial mat that worked absolutely in the absence of oxygen."</p><p>Not that Earth is the only place where this could happen. Visscher notes that the equipment they used for studying the Laguna La Brava mats is not unlike the system aboard the Mars Perseverance Rover. "In looking for evidence of life on Mars, they will be looking at iron, and probably they should be looking at arsenic also."</p>
An intriguing theory explains animals' magnetic sense.
- Some animals can navigate via magnetism, though scientists aren't sure how.
- Research shows that some of these animals contain magnetotactic bacteria.
- These bacteria align themselves along the magnetic field's grid lines.
Magnetotactic bacteria hosts<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQyMTQ2Ny9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2MDcwMTYxMn0.BZ-cpaTejm38_HCvVoSZ92k58dxnQETahNmKOmB14X4/img.jpg?width=980" id="c6097" class="rm-shortcode" data-rm-shortcode-id="a9f01b7583442ad92a05927c79754f50" data-rm-shortcode-name="rebelmouse-image" alt="whale mother and calf" />
A right whale mother and calf
Credit: wildestanimal/Shutterstock<p>One of the paper's authors, Geneticist <a href="https://sciences.ucf.edu/biology/person/robert-fitak/" target="_blank">Robert Fitak</a>,<a href="https://sciences.ucf.edu/biology/person/robert-fitak/" target="_blank" rel="noopener noreferrer"></a> is affiliated with the biology department of the <a href="https://www.ucf.edu" target="_blank">University of Central Florida</a> in (UCF) Orlando. Prior to joining the department, he spent four years as a postdoctoral researcher at Duke University investigating the genomic mechanisms responsible for magnetic perception in fish and lobsters.</p><p>Fitak tells <a href="https://www.ucf.edu/news/animals-magnetic-sixth-sense-may-come-from-bacteria-new-paper-suggests/" target="_blank">UFC Today</a>, "The search for a mechanism has been proposed as one of the last major frontiers in sensory biology and described as if we are 'searching for a needle in a needle stack.'"</p><p>That metaphorical needle stack may well be the scientific community's largest database of microbes, the <a href="https://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-9-75" target="_blank" rel="noopener noreferrer">Metagenomic Rapid Annotations using Subsystems Technology database</a>. It lists the animal samples in which magnetotactic bacteria have been found.</p><p>The primary use of the database, says Fitak, has been the measurement of bacterial diversity in entire phyla. An accounting of the appearance of magnetotactic bacteria in individual species is something that has previously be unexplored. "The presence of these magnetotactic bacteria had been largely overlooked, or 'lost in the mud' amongst the massive scale of these datasets," he reports.</p><p>Fitak dug into the database and discovered that magnetotactic bacteria have indeed been identified in a number of species known to navigate by magnetism, among them loggerhead sea turtles, Atlantic right whales, bats, and penguins. <em>Candidatus Magnetobacterium bavaricum</em> is regularly found in loggerheads and penguins, while <em>Magnetospirillum</em> and <em>Magnetococcus</em> are common among right whales and bats.</p><p>As for other magnetic-field-sensitive animals, he says, "I'm working with the co-authors and local UCF researchers to develop a genetic test for these bacteria, and we plan to subsequently screen various animals and specific tissues, such as in sea turtles, fish, spiny lobsters and birds."</p>
The bacteria-host relationship<p>While the presence of the bacteria in these particular species is intriguing, further study is needed to be sure they're responsible for other animals' magnetic navigation. Their presence in these species <em>could</em> be just a coincidence.</p><p>Fitak also notes that he doesn't know at this point exactly where in the host animal the magnetotactic bacteria would reside, or other details of their symbiotic relationship. He suggests that they might be found in nervous tissue associated with navigation, such as that found in the brain or eye.</p><p>If confirmed, Fitak's hypothesis could suggest that our own sensitivity to the Earth's magnetic field might one day be enhanced via magnetotactic bacteria in our own individual microbiomes, should they be benign to us as hosts.</p>
Various studies examine the impact of humidity, temperature, rain, and sunshine on COVID-19.
- Researchers around the world have been working to analyze and understand this virus since the global pandemic started earlier this year.
- While the first SARS-CoV virus (2003) did not circulate long enough for researchers to distinguish any specific seasonal pattern, daily weather did have an impact on the number of cases.
- Other studies from China, Australia, Brazil, and the UK take a look at how our weather can impact the transmission of COVID-19.
How does weather impact virus transmission?<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzU5OTg4OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNTU1NjA2MX0.SvtcZz2PxVjC9AFLhC0sRpMDbcFp-RkAPJhuwTsZyWg/img.jpg?width=1245&coordinates=0%2C0%2C100%2C0&height=700" id="e5f2d" class="rm-shortcode" data-rm-shortcode-id="92f1bc5a03e54cc3f2f981acd09d14e2" data-rm-shortcode-name="rebelmouse-image" alt="COVID-19 virus SARS-CoV-2 under microscope weather virus" />
How does weather impact the COVID-19 virus?
Image by MIA Studio on Shutterstock<p><strong>Studies of the first SARS-CoV (in 2003) might help us understand.</strong><br></p><p>While this virus did not circulate long enough for researchers to distinguish any specific seasonal pattern, daily weather did have an impact on the number of cases. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2870397/" target="_blank" rel="noopener noreferrer">According to this study</a>, new cases of SARS-CoV were 18x higher in lower temperatures (under 24.6°C). </p><p><strong>Cold weather impacts your likelihood of getting sick in different ways. </strong></p><p>One factor, according to <a href="https://sciencing.com/cold-weather-affect-immunity-22739.html" target="_blank" rel="noopener noreferrer">Sciencing</a>, that may increase your susceptibility in cold weather is how your sinuses respond to the humidity and temperature changes. Your nose is a natural air filter for your body. When you spend time in cold temperatures, your nasal passages dry out due to the constriction of blood vessels. When you return to warmer temperatures (like coming inside after time spent out in the cold), the sudden influx of moisture can cause your nose to run.</p><p>This usually forces you to breathe through your mouth, robbing you of the filter and making you susceptible to viruses or bacteria in the air. </p><p><strong>Cold weather = more time spent indoors, which can increase the likelihood of transmission.</strong></p><p>Regardless of the weather, it takes exposure to a virus to get a virus. One common reason why virus infections may become more common during cold months is that more people are spending time indoors (and together). </p><p><a href="https://bigthink.com/politics-current-affairs/social-distancing-math" target="_self">As research has determined</a>, social distancing can heavily impact the spread of the COVID-19 virus. Being clustered closer together indoors can increase the likelihood of transmission, giving the effect of the virus spreading faster in the colder months. </p>
The weather and COVID-19 studies from around the globe<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzU5OTg5MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNTcwNzgxNH0.t5SY7q3HULHvoWIz5SpPA-DnPHjcgZqa0fANRn8ksxI/img.jpg?width=1245&coordinates=0%2C52%2C0%2C52&height=700" id="fb167" class="rm-shortcode" data-rm-shortcode-id="f3c84c531fb1b51decdb63e5f4a7c516" data-rm-shortcode-name="rebelmouse-image" alt="concept of condensation humidity impact COVID-19 condensation on window" />
How do things like humidity, rainfall and sunshine impact the spread of COVID-19?
Photo by matuska on Shutterstock<p>Laboratory and observational studies of COVID-19 patients have shown there is an impact of humidity on SARS-COV-2.</p><p><strong>Humidity and its impact on COVID-19:</strong></p><p><a href="https://wwwnc.cdc.gov/eid/article/26/9/20-1806_article#r7" target="_blank" rel="noopener noreferrer">A lab-generated aerosol of SARS-CoV-2</a> was stable at a humidity of 53 percent at room temperature (23°C). The virus had not degenerated much, even after 16 hours, and was more robust than SARS-CoV. </p><p>Although laboratory studies cannot be used to explicitly explain how the virus will act in the real world, these findings are very important in deepening our understanding of the virus and its transmission. </p><p><a href="https://www.sciencedirect.com/science/article/pii/S004896972032026X?via%3Dihub" target="_blank" rel="noopener noreferrer">Another study in China</a> (with more than 50 cases of COVID-19) found a link between humidity and reductions in COVID-19 cases. In this simulation, the team measured humidity as absolute humidity (the total amount of water in the air) and found that for every gram per cubic meter in absolute humidity, there was a 67 percent reduction in COVID-19 cases after a lag of 14 days. </p><p>Similar studies (with similar results) have been conducted in <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/tbed.13631" target="_blank" rel="noopener noreferrer">Australia</a>.</p><p><strong>Rainfall and its impact on COVID-19:</strong></p><p>Rainfall may also impact the spread of the virus. <a href="https://www.sciencedirect.com/science/article/pii/S0048969720325146?via%3Dihub" target="_blank" rel="noopener noreferrer">Research out of Brazil</a> looked at rainfall worldwide and confirmed a pattern: for each average inch per day of rain, there was an increase of 56 COVID-19 cases per day. There was no link found between the COVID-19 deaths and rainfall. </p><p><strong>Sunshine and its impact on COVID-19: </strong></p><p>A Spain study found (after 5 days of lockdown) the longer the hours of sunshine, the more cases there were of the virus. This positive association held true with a lag (between sunshine hours and cases) of both 8 and 11 days. </p><p>However, it's important to note that this actually contradicts findings from Influenza research, which suggests a lower transmission with longer hours of sunshine. While influenza and COVID-19 are obviously different, it's interesting to note this contrast, as they are both viral infections.</p><p><strong>While all of these studies are interesting, does it really prove COVID-19 is impacted by weather? </strong></p><p><a href="https://www.medrxiv.org/content/10.1101/2020.05.21.20108803v1" target="_blank" rel="noopener noreferrer">Research out of Oxford</a> actually lists reasons why people should not use these observational studies on the weather and COVID-19 cases to establish if the virus is more or less transmittable based on the season. </p><p>While it's important to note that there are still things we don't know about COVID-19 and that each country has different testing and studying methods, the more we know about how this virus behaves in different climates the more we can work to prevent further infection. </p>
A new study shows bacteria could survive travel from Earth to Mars.
Did Life on Earth Come From Space?<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="d4a27f047b961f104fa863a2b3ace6e2"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/cUyLODoZiVM?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
German researchers have just solved the mystery of how these substances work.
- As pathogens' resistance grows, scientists are searching for a class of drugs that could replace antibiotics.
- Antivitamins that switch off vitamins in bacteria are being investigated.
- Scientists have been struggling to understand how naturally occurring antivitamins do what they do.
Shutting down the dance of the proteins<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzU3Nzk5OS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMDk4NzI5NX0.FPVenf2jQ4I4raQqn5EpK_DxCGoYRSw3wzIzryl2ys0/img.jpg?width=980" id="27eb8" class="rm-shortcode" data-rm-shortcode-id="6cfa008038077a6fbcab3f53d2af6cf8" data-rm-shortcode-name="rebelmouse-image" alt="Vitamin B1" />
Image source: Ekaterina_Minaeva/Shutterstock<p>The study was led by <a href="https://www.uni-goettingen.de/en/89703.html" target="_blank">Dr. Kai Tittmann's</a> group from the Göttingen Center for Molecular Biosciences at the University of Göttingen in collaboration with <a href="https://www3.mpibpc.mpg.de/groups/de_groot/bgroot.html" target="_blank">Bert De Groot's Computational Biomolecular Dynamics Group</a> from the Max Planck Institute for Biophysical Chemistry Göttingen, and with <a href="https://www.chem.tamu.edu/rgroup/begley/" target="_blank">Tadhg Begley's group</a> from Texas A&M University in College Station, Texas.</p><p>The B1 antivitamin is naturally occurring, and is produced by bacteria as a means of killing off competing bacteria. Its critical atom appears in an apparently unimportant location, deepening the mystery.</p><p>To see how that single atom was doing such an effective job, the researchers used <a href="https://www.pnas.org/content/97/7/3171" target="_blank">high-resolution protein crystallography</a>. This allowed them to observe the interaction between the B1 antivitamin and B1 on an atomic level.<br></p><p>What they saw was that the antivitamin completely interrupted the "dance of protons" that's seen in functioning proteins. Tittmann <a href="https://www.uni-goettingen.de/en/3240.html?id=5964" target="_blank">says</a>, "Just one extra atom in the antivitamin acts like a grain of sand in a complex gear system by blocking its finely tuned mechanics." (Tittmann's group was the first to document this "dance" in <a href="https://www.technologynetworks.com/proteomics/news/dance-of-the-protons-discovery-shows-proteins-instant-message-324139" target="_blank">2019</a>.)</p>