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.
. Antarctica's blood-red ice is really an ominous sign of climate change
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, 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.
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. Experiments showed that areas with more meltwater led to the growth of 50 percent more algae and places with more algae melted further. 
. 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. 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. “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.
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. B-cells are the immune system’s antibody factories. They areanother essential category of white blood cell produced in the bone marrow (B=bone marrow).  
“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.” 
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. 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. 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. Technology for mass testing of T-cell immunity is unlikely to be available in the near future. 
. 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. The images shown on the cover of JM are of two nearby young planetary nebulae, NGC 6302, dubbed the Butterfly Nebula, and NGC 7027.
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.
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.
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 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.  Now bullets of material are shooting out in specific directions.
. 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. 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 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.
Inomata’s team 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 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. Some axes excavated from the site date back to about 1000 B.C. (see picture).
Sources: ScienceAlert, FT.com, ESA, Sciencenews.org