Science News Headlines . Antarctica's blood-red ice is really an ominous sign of climate change . Why T-cells may be the missing link in coronavirus immunity . Stunning New Hubble Images Reveal Stars Gone Haywire . LIDAR reveals the oldest and biggest Maya structure yet found Read more details below. The ice in Vernadsky Research Base in Antarctica is now drenched in a shocking blood-red. Marine ecologist Andrey Zotov from the National Academy of Sciences of Ukraine, captured the images shown on the cover of JM, while conducting research at the Antarctic station. The reason for the colour: some tiny culprits, green algae! These microscopic green algae, officially called Chlamydomonas nivalis, are a type of single-cellular seaweed, and are common in all icy and snowy regions of Earth, from the arctic to alpine regions. They lie slumbering during the brutal winter, but once the sunlight warms enough to soften their crystallised world, the algae spring awake, making use of the meltwater and sunlight to rapidly bloom. "The algae need liquid water in order to bloom," University of Leeds microbiologist Steffi Lutz said. Young C. nivalis are green due to their photosynthesising chloroplasts and they have two tail-like structures called flagella, which they flail about to swim with. As they mature, they lose their mobility and develop unique adaptations to survive their extreme environment, including a secondary insulating cell wall and a layer of red carotenoids, which changes their appearance from green to orange to red. "This layer protects the algae from ultraviolet radiation," explained the National Antarctic Scientific Centre of Ukraine. The carotenoids also help the algae to absorb more warmth, which in turn creates more meltwater for them to thrive in. This is all well and good for the algae and all the creatures that eat them, like roundworms and springtails, but unfortunately there are other consequences, too: the algal blooms contribute to climate change. A study in 2016 showed that snow algal blooms can decrease the amount of light reflected from the snow (also know as albedo) by up to 13 percent across one melt season in the Arctic. This will invariably result in higher melt rates. In 2017 environmental scientists calculated that microbial communities, which include C. nivalis, contributed to over a sixth of the snowmelt where they were present in Alaskan icefields. Their experiments showed that areas with more meltwater led to the growth of 50 percent more algae and places with more algae melted further. This Antarctic summer has certainly seen a lot more meltwater than usual. Temperature records keep tumbling, leading to rapid melting at a scale previously only seen in the Northern Hemisphere. "These events are coming more frequently," warned glaciologist Mauri Pelto from Nichols College. So, increased temperatures lead to more melting of crystalised water, which encourages the growth of more algae, which leads to more melting and so on. But at least C. nivalis infested snow... smells sweet! This phenomenon is also known as 'watermelon snow', although it is definitely not edible, because the algae are toxic to humans. . Why T-cells may be the missing link in coronavirus immunity Scientists have spent months focused on the role of antibodies in fighting Covid-19. Antibodies are protein molecules that attach to the virus (called antigens), and neutralise them. Some are designed to recognise invading germs. Others such as phagocytes have the job of destroying them. Recent studies have shown that the level of antibodies in people who have been infected with Covid-19 reduces drastically after a few months. The question then is of course whether these people can be re-infected with the virus after some time. However, immunity to any infection arises from a complicated interplay of different cells and antibodies, which are produced in various human tissues. Evidence is emerging that T-cells, which can “remember” past infections and kill pathogens if they reappear, have a big influence on how long patients remain resistant to reinfection by Covid-19. T-cells, which circulate in the blood, might protect people who have been infected and recovered from the new coronavirus but have no detectable antibodies shortly thereafter. “Antibodies do look slightly precarious and transient in the blood, while there is a lot of evidence that T-cells are long lasting,” said Mala Maini, professor of viral immunology at University College London. People who recovered from SARS, the disease most closely related to Covid-19, in 2003 still show cellular immunity to that coronavirus 17 years later. T-cells are a type of white blood cell produced in the thymus (T=thymus) and come in several different types, including killer T-cells, helper T-cells and memory T-cells. They are involved in cell-mediated immunity. Then there are B-cells — another essential category of white blood cell produced in the bone marrow (B=bone marrow). Among other roles B-cells are the immune system’s antibody factories. Al Edwards, associate professor at Reading University’s School of Pharmacy, offers an analogy. “T-cells are tasting the virus whereas the antibodies are feeling the virus,” he said. “T-cells can promote antibody responses and antibody responses can promote a T-cell response. These two systems work together.” “Even if you’re left with no detectable circulating antibodies, that doesn’t necessarily mean you have no protective immunity, because you are likely to have memory immune cells (B and T cells) that can rapidly kick into action to start up a new immune response if you re-encounter the virus,” added Prof Maini of UCL. “So you might well get a milder infection.” As data emerge from clinical trials of potential Covid-19 vaccines, the extent to which they evoke T-cell immunity will be a focus of attention. Advocates of viral vaccines, which use a harmless genetically engineered virus to carry coronavirus antigens into human cells, are already suggesting that their method is more effective at raising a T-cell response than an alternative approach, which injects coronavirus genes in the form of RNA or DNA into human cells. Recently Oxford scientists presented the first clinical trial results of their ChAdOx1 vaccine, which is a genetically engineered virus modified from a chimpanzee adenovirus that gives them common cold. The trial, which involved more than 1000 people, showed that the vaccine caused them to make both antibodies as well as T-cells that can fight coronavirus. But it remains to be seen whether the combination of neutralising antibodies and T-cells raised by the vaccine will give strong and long-lasting immune protection. The studies are still on-going. One reason why antibodies have been the focus of attention is that they are far easier to measure in diagnostic tests than T-cells, which are almost 10,000 times larger. “Antibodies are protein molecules circulating in your blood, which can be measured in a straightforward assay [blood test],” said Herb Sewell, immunology professor at the University of Nottingham. “For T-cells, you have to extract them from the blood, keep them alive, and expose them to the assay.” Technology for mass testing of T-cell immunity is unlikely to be available in the near future. However the first lab studies of the overall immune response to Sars-Cov-2, the virus that causes Covid-19, are beginning to report results. One, led by Jennifer Juno at the University of Melbourne and published in Nature Medicine studied 41 Australians with mild to moderate symptoms. “. . . we found a wide range of antibody responses,” she said. “Some high and some low, but strong antibody responses were associated with . . . a subset of a subset of the T-cells which were more effective at helping drive a better antibody response.” Several studies suggest T-cells produced by other coronaviruses — which cause only mild cold-like illness — may also recognise Sars-Cov-2 and provide some protection against Covid-19. . Stunning New Hubble Images Reveal Stars Gone Haywire The NASA/ESA Hubble Space Telescope is the first major optical telescope to be placed in space. The rain clouds, the Earth's atmosphere, are all far below and so Hubble has an unobstructed and undistorted view of our Universe. It has demonstrated its full range of imaging capabilities with two new images of planetary nebulae. The images shown on the cover of JM are of two nearby young planetary nebulae, NGC 6302, dubbed the Butterfly Nebula, and NGC 7027. Both are among the dustiest planetary nebulae known and both contain unusually large masses of gas, which made them an interesting pair for study in parallel by a team of researchers. Most stars live placid lives for hundreds of millions to billions of years, burning mostly hydrogen to fuel their fires. But near the end of their lives they can turn into crazy whirligigs, puffing off shells and jets of hot gas. Astronomers have used Hubble to dissect such crazy fireworks happening in these two planetary nebulae. Researchers are trying to understand the mechanisms underlying this chaos. The Hubble Space Telescope has imaged these objects before, but not for many years and never before with the Wide Field Camera 3 instrument across its full wavelength range — making observations in near-ultraviolet to near-infrared light. The new Hubble images reveal in vivid detail how both nebulae are splitting themselves apart on extremely short timescales — allowing astronomers to see changes over the past couple of decades. In particular, Hubble’s broad multi-wavelength views of each nebula are helping the researchers to trace the histories of shock waves in them. Such shocks are typically generated when fresh, fast stellar winds slam into and sweep up more slowly expanding gas and dust ejected by the star in its recent past, generating bubble-like cavities with well-defined walls. Researchers suspect that at the heart of each nebula were two stars orbiting around each other. Evidence for such a central “dynamic duo” comes from the bizarre shapes of these nebulas. Each has a pinched, dusty waist and polar lobes or outflows, as well as other, more complex symmetrical patterns. A leading theory for the generation of such structures in planetary nebulae is that the mass-losing star is one of two stars in a binary system. The two stars orbit one another closely enough that they eventually interact, producing a gas disc around one or both stars. The disc then launches jets that inflate polar-directed lobes of outflowing gas. Another, related, popular hypothesis is that the smaller star of the pair may merge with its bloated, more rapidly evolving stellar companion. This very short-lived “common envelope” binary star configuration can also generate wobbling jets, forming the trademark bipolar outflows commonly seen in planetary nebulae. However, the suspect companion stars in these planetary nebulae have not been directly observed. Researchers suggest this may be because these companions are next to, or have already been swallowed by, far larger and brighter red giant. NGC 6302, commonly known as the Butterfly Nebula, exhibits a distinct S-shaped pattern seen in reddish-orange in the image. Imagine a lawn sprinkler spinning wildly, throwing out two S-shaped streams. In this case it is not water in the air, but gas blown out at high speed by a star. And the “S” only appears when captured by the Hubble camera filter that records near-infrared emission from singly ionised iron atoms. This iron emission is indicative of energetic collisions between both slow and fast winds, which is most commonly observed in active galactic nuclei and supernova remnants. The accompanying image of NGC 7027, which resembles a jewel bug, indicates that it had been slowly puffing away its mass in quiet, spherically symmetric or perhaps spiral patterns for centuries — until relatively recently. “Something recently went haywire at the very centre, producing a new cloverleaf pattern, with bullets of material shooting out in specific directions,” Kastner explained. The Hubble Space Telescope is a project of international cooperation between ESA and NASA. The team of astronomers who carried out this study consists of J. Kastner, J. Bublitz, B. Balick, P. Moraga, A. Frank, and E. Blackman. These observations were conducted under the Hubble observation programme 15953. Images NGC 6302 and NGC 7027 courtesy . . LIDAR reveals the oldest and biggest Maya structure yet found The ancient Maya civilisation developed in the region which is now Mexico, Guatemala, Honduras, El Salvador, etc., starting from around 2000 B.C. Soon they had developed agriulture, growing maize, beans and chillies. They built big cities by around 750 B.C. with large and elaborate temples. By the third century B.C., they had developed hieroglyphic writing as well. By the 16th century, the Spanish Empire colonised this region and the entire civilisation was destroyed. Excavations and airborne mapping at a previously unknown site in Mexico, called Aguada Fénix, have uncovered the oldest and largest known structure built by Maya people, say archaeologist Takeshi Inomata of the University of Arizona in Tucson and his colleagues. This raised ceremonial area made of clay and earth was constructed from around 1000 B.C. to 800 B.C., the scientists report June 3 in Nature. The new discovery adds to recent evidence that from its very beginnings around 3,000 years ago, the Maya civilization built monumental structures. The finds run counter to the idea that Maya society developed gradually from small villages to urban centers with pyramids and other massive buildings, as some scientists have suggested. Those Maya cities and kingdoms of what’s known as the Classic period didn’t flourish in parts of southern Mexico and Central America until around A.D. 250 to 900. What’s more, the study is yet another example of how an airborne remote-sensing technique called light detection and ranging, or LIDAR, is dramatically changing how archaeological research is done in heavily forested regions. The technique, which uses laser pulses to gather data on the contours of jungle- and vegetation-covered land, has uncovered other lost ruins at the Maya city of Tikal in Guatemala and a vast network connecting ancient cities of Southeast Asia’s Khmer Empire, among other finds. LIDAR maps of 21 ceremonial centres showed that each site contains a round or square mound near a long, rectangular platform, running west to east. That layout characterizes similar structures in areas where public rituals were held in many later Maya cities. Inomata’s team then used the LIDAR maps to focus on Aguada Fénix. There, the scientists found an elevated, rectangular plateau measuring about 1,400 meters long and nearly 400 meters wide. Within that space is a roughly 400-meter-long platform — the length of more than four American football fields — positioned east of a 10-meter-tall earthen mound. LIDAR revealed other structures around the human-built plateau, including rectangular buildings, plazas and several reservoirs. Discoveries at Aguada Fénix challenge a traditional assumption that only large settlements directed by kings and a ruling class could organize and execute big building projects, Inomata says. No remnants of a royal class that appear at later Maya sites, such as sculptures of high-ranking individuals, have been found at the site so far. People living in the region around Aguada Fénix, who were cultivating maize by 3,000 years ago, must have banded together to create a ritual site suitable for large gatherings, he suggests. https://www.sciencealert.com/these-astounding-images-of-antarctica-s-ice-drenched-blood-red-are-an-ominous-sign https://sci.esa.int/web/hubble/-/stunning-new-hubble-images-reveal-stars-gone-haywire-heic2011 issue of /Science News/.