You may have missed… dammed platypuses, crime scene cats, toxin testing with the naked eye, and dissociative symptoms

Large river dams could be threatening platypus populations

Platypuses are an iconic Australian monotreme but now a new Australian study has identified a potential threat to their populations, perhaps counterintuitively finding that large river dams pose significant barriers to their movement and gene flow.

Researchers examined the genetic makeup of platypuses above and below five major dams and in four free-flowing adjacent rivers in New South Wales.

“We extracted the DNA from the blood collected by our Platypus Conservation Initiative researchers at the University of New South Wales (UNSW). By using thousands of molecular markers, we were able to identify a strong signal indicating that genetic differentiation increased rapidly between platypuses below and above these large dams,” explains lead author Dr Luis Mijangos, a former UNSW PhD student who is now a researcher at the University of Canberra.

Read more: Platypus: the preposterous platypus is no joke.

Genetic differentiation is a way to measure the dispersal and gene flow between different populations. If there is greater genetic differentiation between populations then that means that they can’t interbreed easily, so different variants of genes (called alleles) accumulate in varying frequencies.

Platypus being held in a towel
A platypus. Credit: Dr Gilad Bino

Importantly, they found genetic differentiation also increased over time after  the dams were built, indicating long-term impacts. The authors suggest implementing strategies to reduce these effects, such as relocating individual platypuses above and below dams or building structures to facilitate their movement.

Finding brain activity related to dissociative symptoms

Dissociative symptoms, like having an out-of-body experience or feeling emotionally numb, can be caused by trauma. But while these symptoms may help someone cope in the short term, they can have negative impacts if they persist for long periods of time.

In a new study published in Neuropsychopharmacology, researchers have now identified the regions within brain networks that communicate with each other when these individuals experience different types of symptoms.

“We found that dissociation common to post-traumatic stress disorder (PTSD) and dissociation central to dissociative identity disorder (DID) are each linked to unique brain signatures,” says co-lead author Dr Lauren A.M. Lebois at Harvard Medical School in the US.

Given that DID disproportionally affects women, the researchers included 91 women with and without histories of childhood trauma, current PTSD, and with varied levels of dissociative symptoms in the study. They completed functional magnetic imaging (fMRI) scans to gain insight into their brain activity.

Specifically, the researchers found different dissociative symptoms were uniquely associated with connections of areas in brain networks that are responsible for cognition and emotional processes.

The authors hope that a better understanding of these processes will help destigmatise these experiences and may one day point to new therapies.

Could crime scene cats help find DNA evidence?

For the first time, forensic researchers from Flinders University have examined how pets at crime scenes may be helpful in gathering key genetic evidence.

They investigated the role of cats in the transfer of human DNA by collecting samples from 20 pet cats from multiple households, in collaboration with the Victoria Police Forensic Services Department.

Detectable levels of DNA were found in 80% of the samples and interpretable profiles that could be linked to a person of interest were generated in 70% of the cats tested.

Read more: From the crime scene to the courtroom: the journey of a DNA sample.

The researchers say the findings, which have been published in Forensic Science International, can be relevant when interpreting DNA results from crime scenes in which pets were present.

“This type of data can help us understand the meaning of the DNA results obtained, especially if there is a match to a person of interest,” says co-author Dr Mariya Goray, from the College of Science and Engineering at Flinders.

“Are these DNA finding a result of a criminal activity or could they have been transferred and deposited at the scene via a pet?”

Detecting toxin concentrations with the naked eye

Engineers have developed a fast and cost-effective new method to test liquids for a ubiquitous family of compounds known as amphiphiles.

Amphiphilic compounds contain both a hydrophilic (water-loving or polar) region and hydrophobic (oil-loving or non-polar) region. Endotoxins are a common type of amphiphile found in gram-negative bacterial cell walls that can contaminate water and even cause severe illness and death, but current testing processes are expensive and unsustainable.

The new test uses rolling droplets on microstructured surfaces to detect amphiphiles at ultralow concentrations.

Pnas. 2211042119fig01 cropped
Fluorescence image of amphiphiles concentrated at the edges of micropillars on a microstructured surface. Credit: Image courtesy of the Aizenberg Lab/Harvard SEAS

The surface is made up of thousands of circular micropillars, which are coated with long-tailed molecules so that the surface is smooth and friction free – except for at the edges of the micropillars where there are gaps in the coating (like molecular potholes).

When a liquid droplet containing no amphiphile molecules rolls down the surface it will hit a pothole and stop because of the friction. But a droplet with higher levels of amphiphiles will continue to roll, because the amphiphiles co-assemble with the long-tailed molecules and fill the gaps in the surface.

So, where the droplet stops on the surface tells scientists the concentrations of amphiphiles.

The research has been published in the journal PNAS.

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