News Highlights - June 2021

Welcome to my third round-up of science news, this time featuring items that caught my attention in over the last few months. As always, I’ll provide a link to the article and to any relevant scientific papers, where available.

This month, there's an animal theme and I’ll be taking a look at how dogs can detect people with Covid-19 infections; a new method for saving bees from pesticide poisoning; the symbiotic relationship between a squid and bacteria; and how 3D-printing may be able to reduce ivory demand.

First up, dogs detecting Covid-19 infections. As restrictions on socialising ease, we’re being encouraged to take lateral flow antigen tests for Covid-19, even if we have no symptoms, to help track and ultimately reduce the spread of the virus. A recent Cochrane Review has determined, based on 64 studies, that rapid tests such as the lateral flow tests have variable accuracy. Tests carried out by, or under the supervision of, trained personnel are more likely to give an accurate result than those carried out at home, and the rate of positive cases correctly identified is around 75% in people with symptoms and only 58% for asymptomatic people. An accurate result in only 58% of cases is little better than a random pick of “positive” or “negative”, but recent research by scientists in France and the UK has suggested that trained dogs may be significantly better at working out who is infected and who isn’t.

Lateral flow tests (Credit: Marc Baldwin

In a press release published in May 2021, researchers from the French National Veterinary School and the Necker-Cochin hospital in Paris announced that in their tests of 335 people the team of nine dogs studied had an average accuracy of 97% for Covid-19 positive volunteers and 91% for uninfected subjects. The dogs identified the subjects by sniffing pads held in the armpit of the volunteers and the results of this study (carried out during March and April 2021) support the findings of a proof-of-concept trial carried out with dogs in Paris and Beirut that was published in December 2020.

In the UK, researchers from the London School of Hygiene and Tropical Medicine have also been studying the ability of dogs to detect Covid infections. In an, as yet, unpublished paper the team report on their findings. Samples from 2,829 people were collected and 54 samples were submitted for chemical analysis using a volatile organic compound (VOC) analyser and 400 samples were tested by the six dogs once they were trained – both sets of samples equally divided between Covid-19 positive and negative participants. The VOC analyser was 99% accurate in determining which samples came from infected volunteers and the dogs were 82-94% accurate. Interestingly, the researchers found no significant difference in the ability of the dogs to detect the original (Wuhan) strain of the virus and the Alpha variant (“Kent”/B.1.1.7), even though the dogs were trained using the original strain, suggesting that the changes between the original strain and the Alpha variant did not radically alter the scent profile – this does not necessarily mean that other variants will follow the same pattern, but re-training the dogs would be a relatively quick process.

Labrador following a scent trail (Credit: Marc Baldwin)

More research will be required to ensure that dog testing is robust and can be reliably used on people rather than just samples on cloth, but it certainly offers potential for mass screening at airports and other high footfall areas. Having taken a lateral flow test, I know that I’d rather be sniffed by a dog than do that again!

News article & press release links: https://www.theguardian.com/lifeandstyle/2021/may/20/dogs-can-better-detect-covid-in-humans-than-lateral-flow-tests-finds-study

https://www.vet-alfort.fr/detection-de-la-covid-19-par-des-chiens-resultats-tres-prometteurs

Scientific papers: Grandjean, D. et al., (2020). Can the detection dog alert on COVID-19 positive persons by sniffing axillary sweat samples? A proof-of-concept study. PLoS ONE. 15 (12), e0243122, https://doi.org/10.1371/journal.pone.0243122

Guest, C. & Dewhurst, S. Y. et al., (pre-print). Using trained dogs and organic semi-conducting sensors to identify asymptomatic and mild SARS-COV-2 infections. https://www.lshtm.ac.uk/media/49791

Dinnes, J. et al., (2021). Rapid, point‐of‐care antigen and molecular‐based tests for diagnosis of SARS‐CoV‐2 infection. Cochrane Database of Systematic Reviews 2021. Issue 3. Article number CD013705, DOI: 10.1002/14651858.CD013705.pub2

The important role played by bees in pollinating plants and crops is well known, as is the fact that many species of bee are struggling. Organophosphate pesticides, which make up about one third of all insecticide sales worldwide, are particularly toxic to bees. There are enzymes called phosphotriesterases that can break down organophosphates, but these enzymes don’t normally survive the acidic digestive system of bees for long enough to help remove

Bumblebee on Salvia (credit: Stephanie Powley)

the toxins. A recent study by Cornell University, however, has shown potential for making phosphotriesterases able to withstand the hostile conditions inside bees; the enzymes can be “packaged” inside molecules of calcium carbonate (chalk) and gelatine, which are a similar size and shape to pollen grains. The chalk protects the enzymes from the acids in the bee’s gut meaning that when insecticide-contaminated pollen is ingested by the bee, the enzymes are ready to break down the toxins. The team at Cornell fed the packaged enzymes to bumblebees along with pollen contaminated with the organophosphate malathion. Bees fed the enzyme alone or a sugar syrup control died from poisoning, but those fed the enzymes in the molecule survived.

The discovery of a technique for providing bees with an antidote to insecticide poisoning is an interesting development and certainly has potential for improving the health of managed hives. As noted by Professor Dave Goulson from the University of Sussex in the Chemistry World article on the subject, expanding this technique to wild bee colonies will be challenging, and there is a risk that having such a “cure” for the poisoning of managed bees could lead to increased pesticide use. If these concerns can be mitigated, this could be a hugely beneficial step forward in the conservation of pollinators.

News article: https://www.chemistryworld.com/news/pollen-mimicking-antidote-saves-bees-after-pesticide-exposure/4013733.article

Scientific paper: Chen, J. et al., (2021). Pollen-inspired enzymatic microparticles to reduce organophosphate toxicity in managed pollinators. Nature Food. 2, 339-347, DOI: https://doi.org/10.1038/s43016-021-00282-0

The next article in my list combines my love of marine creatures with my interest in all-things mass spectrometry. A team of scientists from several universities in the United States have used imaging mass spectrometry, where mass spectra are taken from across the surface of a sample to see how the chemical make up changes, to understand how newly hatched Hawaiian bobtail squid (Euprymna scolopes) acquire the Vibrio fischeri bacteria that provide them with their bioluminescence. The incredibly detailed and intricate work of the team has identified a chemical signal given out by the squid that allows it to attract the right bacteria and, more importantly, the right strain of V. fischeri, from the huge diversity of microbial life in the oceans when they hatch.

Bobtail squid (Credit: Silke Baron (CC BY 2.0))

The processes used in this study will provide a framework for further work of this kind to understand symbiotic relationships between animals and microbes.

News article: https://www.sciencedaily.com/releases/2021/03/210309153830.htm

Scientific paper: Zink, K. E. et al., (2021). A small molecule coordinates symbiotic behaviours in a host organ. mBio. 12 (2), in press. DOI: https://doi.org/10.1128/mBio.03637-20

Finally for this update, a group of researchers in Vienna, Austria have developed a 3D-printed material that successfully mimics elephant ivory and have used it to restore a 17th century casket in an Austrian church. The material, dubbed “Digory” by its creators, is a polymer made of acrylic resin with tricalcium phosphate particles and is 3D printed using laser light to cross-link the polymers and build up intricate designs. The Digory can even be painted with a mixture including black tea to reproduce the dark veins found in elephant ivory. Other artificial ivory replacements have been produced before, but the scientists claim that this is the first that can be printed at high resolution and has the same look and feel as ivory.

African elephants at Colchester Zoo (Credit: Stephanie Powley)

It is hoped that this new material will allow for high quality restoration of existing artworks and antiquities without the use of elephant ivory and perhaps, in time, reduce the demand for new ivory. If Digory looks as good in use as it appears to, this could be a step in the right direction for the conservation of elephants in the wild.

News article: https://www.chemistryworld.com/news/3d-printed-digital-ivory-saves-antique-artworks-and-maybe-elephants/4013664.article

Scientific paper: Rath, T. et al., (2021). Developing an ivory-like material for stereolithography-based additive manufacturing. Applied Materials Today. 23, 101016. DOI: https://doi.org/10.1016/j.apmt.2021.101016

That’s all for this time, check back for my next round up of science news and please let me know if you come across something interesting that you’d like me to look at!