Scientists from the US Department of Energy (DOE) Joint Genome Institute have discovered a bacterium so large it’s visible to the naked eye. Summing up what it means, researchers have compared it to a human encountering another as tall as Mount Everest.

As much as 50 times bigger than any known giant bacteria, which are single-celled organisms, this bacterium – named Thiomargarita magnifica – was first spotted in 2009 in the mangroves of Guadeloupe by a researcher at the Université des Antilles in the French West Indies.

The unusual size is notable because bacteria aren’t usually visible without a microscope. 

Along with its life cycle, the team furnished a detailed description of the physical and genomic features of this unusual bacterium in a research paper published in the journal Science earlier this week.

In the case of most bacteria, their DNA floats freely within the cytoplasm of their cells. But according to researchers, this newly discovered species keeps its DNA more organised within a structure that has a membrane (outer boundary).

Frog-eating bats can remember ringtones

Frog-eating bats, trained to associate a ringtone with a tasty treat, were able to retain their training for up to four years in the wild, scientists have found in the first such revelation.

The finding is being seen as evidence of frog-eating bats having long-term memory.

For the experiment, a team led by researchers from The Ohio State University acquainted 49 frog-eating bats with a series of ringtones that caught their attention. The bats were then trained to fly towards one of the ringtones to claim a reward: a baitfish snack.

In the years that followed, researchers recaptured eight of those bats and exposed them to the ringtone again. While all eight of them lurched towards the source of the ringtone, six of them raced all the way to the source and grabbed the snack, indicating that they were expecting food.

On the other hand, bats without any prior training were unmoved by exposure to unfamiliar tones.

Previous studies documenting long-term memory in species were centred on fish, birds, bats, goatss and primates that live in captivity the entire time, the researchers said. 

Although long-term memory gives humans an advantage, nature has shown that memory flexibility in animals, also known as adaptive forgetting, could be key to their survival.

How robotic fish can clean up oceans

Scientists have developed a light-activated fish robot that “swims” around quickly, identifying and removing microplastics from the environment. 

Found nearly everywhere on Earth, microplastics pose a massive threat to the environment and can harm animals when ingested. However, removing these tiny particles from the environment can be very hard owing to their size. 

Inspiration for this fish-shaped robot came from mother-of-pearl, also known as nacre, which is a strong and flexible material found on the inside surface of clam shells. Nacre layers are made of calcium carbonate and mineral-polymer composites on one side, and a silk protein filler on the other.

Using a gradient structure modelled on nacre, the team from China’s Sichuan University, whose findings were published in the journal Nano Letters last week, developed a durable and bendable material for soft robots — robots that resemble the mechanical properties of living tissues. They then used it to create a fish-shaped soft robot.

Pointing a near-infrared light laser at the tail and rapidly turning it on and off caused the robotic fish to flap, propelling the soft robot to swim further.

Once in the water, the swimming fish robot was able to repeatedly absorb nearby polystyrene microplastics and transport them elsewhere. Moreover, the material used to create the soft robot could heal itself if cut, while holding on to its ability to adsorb microplastics.

This is in contrast to traditional soft robots made of materials like hydrogels and elastomers, which can easily be damaged in aquatic environments.

Tetraneutron — new state of matter

For the first time, scientists have been able to confirm the existence of a ‘tetraneutron’, which is a bond of four neutrons bound together for a very brief period. This new and exotic state of matter could also have properties that may prove useful in existing or emerging technologies.

Neutrons are subatomic particles with no charge that combine with positively charged protons to make up the nucleus of an atom. Individual neutrons aren’t stable and convert into protons within a few minutes of formation. Even combinations of double and triple neutrons cannot attain what physicists call resonance —  a state of matter that is temporarily stable before it decays.

Since they first theorised about the ‘tetraneutron’ in 2014, researchers at the Iowa State University have been awaiting experimental confirmation to back their discovery of the new state of matter.

Theorists had predicted that four neutrons could form a resonant state with a lifetime of just 3×10-22 seconds, less than a billionth of a nanosecond, long enough for physicists to study it.

Now, researchers from TU Darmstadt in Germany have announced an experimental discovery of tetraneutrons, paving the way for new research to better understand how the universe was formed. 

The ‘tetraneutron’ joins the neutron as the second free (free of any charge) element on the nuclear chart.

ISS avoids collision course with Russian space debris

The International Space Station (ISS) was forced to manoeuvre to avoid collision with debris from a Russian anti-satellite weapons test on 16 June.

Russia had destroyed the defunct Soviet-era satellite Kosmos 1408 in an anti-satellite missile test in November last year.

According to NASA, a piece of debris from the test was predicted to pass within a half-mile radius of the ISS on 16 June. As a measure of caution, the ISS fired its thrusters for 4 minutes and 34 seconds, activating its Pre-Determined Debris Avoidance Maneuver (PDAM) to provide extra space for the debris to pass.

Experts say the debris could pose risk to the ISS, or other space missions in future.