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Sleepy sheep have better sex

For rams, the greatest aphrodisiac might be melatonin, according to a study published in Animal Reproduction Science.

A team of researchers, led by Dave Kleemann of the South Australian Research and Development Institute, found that treating young Border Leicester rams with melatonin in spring improved semen and sperm quality, testicle size and pregnancy success rates.

The team treated rams at two sites with melatonin throughout the spring mating season to see whether it affected sexual maturity, as measured by behaviour towards ewes and semen quality.

On the whole, the treated rams didn’t behave markedly differently from untreated rams when wooing ewes, but treatment did result in an 82% to 89% increase in the rate of pregnancy.

Interestingly, the team found that pregnancy success was lower if the rams were treated with melatonin in autumn.

Testicle size and testosterone levels were also higher in treated rams, and their sperm had greater motility and less DNA damage. Together, these physiological factors may have contributed to greater pregnancy success.

Thinking jobs combat dementia

People who have mentally stimulating jobs are at a lower risk of dementia, suggests a study published in BMJ.

The researchers studied more than 100,000 people aged over 17 from the UK, Europe and US, and found that ‘active’ jobs (defined as requiring mentally demanding tasks) lowered the risk of dementia from 7.3 per 10,000 to 4.8 per 10,000.

The authors suggest that the proteins required to form new connections in the brain are more abundant in people with mentally demanding jobs.

“This new work is an important reminder to all in the specialty of dementia prevention that we can only go so far with intervention studies that are short, late, small, and include only people who are heterogenous in their risk profiles to reveal any benefit of mental enrichment on dementia risk,” writes Serhiy Dekhtyar of the Karolinska Institutet, Sweden, who independently reviewed the study.

“Carefully designed, large, population-based studies with long periods of follow-up that also aim to provide biological clues, can be an important addition to randomised controlled trials. This study is an outstanding example.”

Attacked by a sea snake? They might just be looking for love

According to a study published in Scientific Reports, venomous olive sea snakes – the most common sea snakes along Australia’s northern coasts – might only be attacking scuba divers because they think they are woo-worthy.

A sea snake in the ocean.
An olive sea snake in the ocean. Credit: Jack Breedon

The researchers analysed 158 encounters with the sea snakes and found that the ‘attacks’ may have actually been misplaced mating behaviour, because they were more frequent among males during mating season, and the snakes regularly flicked their tongues seductively.

Male snakes also showed other mating behaviours, such as charging and coiling around divers’ fins, but the researchers suggest bites may occur less frequently if divers hold still in these situations.

“The ocean is a dangerous place for human beings – if anything goes wrong, things can end badly,” says Rick Shine of Macquarie University, who led the study. “And seeing a giant sea snake hurtling towards you certainly qualifies as ‘something going wrong’.

“Hopefully, understanding why that snake is heading towards you – that he has mistaken you for a female of his own species – can calm your nerves and lead to a better outcome all around.”

First 3D-biobrinting of an entire active tumour

Researchers at Tel Aviv University, Israel, have achieved a world first by 3D-printing an entire active glioblastoma tumour in a Petri dish. The tumour had a complex system of blood-vessel-like tubes, simulating a real tumour.

An image of the tumour under a microscope, with tumour in red.
Microscopic image of the 3D-bioprinted glioblastoma model. The bioprinted blood vessels are covered with endothelial cells (red) and pericytes (cyan). Credit: Tel Aviv University

This will help researchers test drugs on the ‘real thing’ to get a better picture of how they will work in a patient.

“Glioblastoma is the most lethal cancer of the central nervous system, accounting for most brain malignancies,” says author Ronit Satchi-Fainaro. “Cancer, like all tissues, behaves very differently on a plastic surface than it does in the human body. Approximately 90% of all experimental drugs fail at the clinical stage because the success achieved in the lab is not reproduced in patients.

“If we take a sample from a patient’s tissue, together with its extracellular matrix, we can 3D-bioprint from this sample 100 tiny tumours and test many different drugs in various combinations to discover the optimal treatment for this specific tumour.

“Alternately, we can test numerous compounds on a 3D-bioprinted tumour and decide which is most promising for further development and investment as a potential drug.

“Our innovation gives us unprecedented access, with no time limits, to 3D tumours, mimicking better the clinical scenario, enabling optimal investigation.”

Anteater backpacks

Anteater on grass wearing a harness
Giant anteater with a GPS backpack. Credit: Aline Giroux.

Giant anteaters require more space as their habitats become less forested, according to a study published in PLOS ONE.

Researchers fitted backpack-like GPS devices to wild giant anteaters in Brazil to see how they roamed in areas with a low proportion of tree cover. They found that the animals wandered more when there were fewer trees.

This may have been because the giant anteaters require tree shade to cool off in extreme heat and have to go further to find both shade and food. The team found that male giant anteaters wandered further than females, potentially because it increased their chances of finding a mate.

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