You may have missed… killer whale mummy’s boys, solar-powered gel filters water, lymphatic vessels produce blood cells, and mass star migration

Cosmos Magazine


Cosmos is a quarterly science magazine. We aim to inspire curiosity in ‘The Science of Everything’ and make the world of science accessible to everyone.

By Cosmos

Killer whales are mummy’s boys

New research has found that killer whale (Orcinus orca) mums are looking after their sons into adulthood, and its impacting their ability to have more babies.

“The magnitude of the cost that females take on to care for their weaned sons was really surprising,” says Dr Michael Weiss, a researcher at the University of Exeter, UK, and the Center for Whale Research in the US.

“While there’s some uncertainty, our best estimate is that each additional surviving son cuts a female’s chances of having a new calf in a given year by more than 50 percent. This is a huge cost to taking care of [adult] sons!”

The researchers studied a group of killer whales known as the “southern resident” population in the coastal waters of Washington state and British Columbia in the US, which has been monitored since 1976 by the Center for Whale Research.

The whales have a bizarre social system where both males and females stay with their mothers for life. By analysing existing data, the team was able to determine that there is a strong negative correlation between females’ number of surviving weaned sons and their annual probability of producing a viable calf.

An adult and juvenile killer whale breaching the water
Killer whale mother and her calf breaching. Credit: Kenneth C Balcomb/Center for Whale Research

These findings suggest that there are also significant benefits to female killer whales keeping adult sons alive and well.

“Females gain evolutionary benefits when their sons are able to successfully reproduce, and our results indicate that these benefits are enough to outweigh a large direct cost,” Weiss explains.

The southern resident population of killer whales are critically endangered, and one major concern is their low reproductive rates, so these findings may have important conservation implications by helping to inform future population viability analyses.

The new study is in Current Biology.

A solar-powered hydrogel that filters clean water

A potential solution for meeting the global need for reliable access to clean water works a lot like a sponge – soaking up clean water while leaving contaminants behind.

Engineers have detailed the next generation of solar absorber gel technology in a new study in the journal ACS Central Science. The sponge-like gel only needs sunlight to filter pollutants, including heavy metals, oils, microplastics, and some bacteria.

This new iteration has almost four times the filtration rate compared to first generation technology developed in 2021; one square metre of one centimetre thick material can produce more than 3.5 litres of water in as little as 1 minute.

The hydrogel is formed from a polymer called poly(N-isopropylacrylamide), or PNIPAm, which can either absorb or release water depending on the temperature. Below 33°C the hydrogel absorbs water from a source but when removed and heated by sunlight to temperatures above 33°, it begins to release the water.

A dark brown coloured gel with moisture on it in a petri dish
A sample of the solar absorber gel. Credit: Bumper DeJesus/Princeton University

Under the midday sun, the gel can release around 70% of the water it absorbs in as little as ten minutes.

Other polymers added to its surface in this iteration include Polydopamine (PDA), which filters contaminants from the water, and poly(sulfobetaine methacrylate) or PSBMA, which binds tightly with water molecules at the gel’s surface to form a hydration layer that repels oil and bacteria – allowing the device to be self-cleaning.

“There have been many efforts to develop a technology that uses solar energy to create clean, potable drinking water, but they often fail to produce enough water to meet daily need,” says Rodney Priestley, Professor of Chemical and Biological Engineering at Princeton University in the US.

“This latest iteration of our technology gets us another step closer towards the goal of having a technology driven by solar energy that can actually produce enough clean water to meet daily demand.”

Move over bone marrow, you’re not the only one making blood cells

Scientists investigating the causes of lymphoedema have made a major discovery – lymphatic vessels can produce red and white blood cells. The new Nature study changes our understanding of how blood cells are made; until now, it was believed that blood cells are derived solely from stem cells in the bone marrow.

Lymphatic vessels return excessive tissue fluid and protein (lymph) back to the bloodstream and are a major component of the immune system by transporting white blood cells.

Lymphoedema occurs when lymphatic vessels within the lymphatic system become blocked or damaged, causing swelling in the soft tissues of the body (more often in the arm or leg). It is a long-term condition that cannot be cured, only managed.

“We discovered a site in DNA important for controlling genes that program the identity and development of lymphatic vessels,” explains lead researcher Professor Natasha Harvey, a developmental biologist at the University of South Australia and Director of the Centre for Cancer Biology in Australia.

“If these genes aren’t switched on at the correct time and place, lymphatic vessels don’t form properly, causing lymph fluid to leak back into the tissues, leading to swelling (lymphoedema),” she says.

“In an unexpected discovery, we identified that the same gene that controls the development of lymphatic vessels also controls the production of blood cells.”

“This exciting discovery suggests that lymphatic vessels may be a previously unrecognised source of blood cells both during development and in disease.”

The finding raises questions as to whether this ability could be important for fighting infection or might play a role in some blood cancers.

The researchers will now investigate what triggers lymphatic vessels to produce different types of blood cells and when this occurs – during both normal development and disease.

First evidence of mass star migration into Andromeda Galaxy

Galaxies, like the Milky Way, grow and evolve over the course of billions of years by making new stars and merging with other galaxies through “galactic immigration” events.

So far, it’s only been possible to study these immigration events in our own galaxy. But a new study in the Astrophysical Journal has uncovered evidence of a large galactic immigration event in the Andromeda Galaxy – the Milky Way’s nearest large galactic neighbour. 

The team studied the movements of nearly 7,5000 individual stars in the inner halo of the Andromeda Galaxy, also known as Messier 31 (M31) and discovered patterns in the positions and motions of stars that revealed they began their lives as part of another galaxy that merged with M31 about 2 billion years ago.

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The team used the DOE’s Dark Energy Spectroscopic Instrument on the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory, a Program of NSF’s NOIRLab, to reveal intricate structures in this galaxy with unprecedented detail and clarity. Each of the dots on this image represents an individual star in the Andromeda Galaxy, with the motion of the star (relative to the galaxy) color-coded from blue (moving toward us) to red (moving away from us). Credit: KPNO/NOIRLab/AURA/NSF/E. Slawik/D. de Martin/M. Zamani

“Our new observations of the Milky Way’s nearest large galactic neighbour, the Andromeda Galaxy, reveal evidence of a galactic immigration event in exquisite detail,” says Arjun Dey, astronomer at the National Science Foundation’s (NSF) NOIRLab in the US, and lead author of the paper.

“Although the night sky may seem unchanging, the Universe is a dynamic place. Galaxies like M31 and our Milky Way are constructed from the building blocks of many smaller galaxies over cosmic history.”

The finding was made possible due to the Dark Energy Spectroscopic Instrument (DESI) – the most powerful multi-object survey spectrograph in the world.

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