This week in animal research: w/e 30 January 15
Evolutionary competition between mice can lead them to evolve better, not bigger, balls. Researchers in the University of Western Australia found that mice could evolve to produce more sperm without having bigger testes. This runs against findings from earlier studies in primates.
Renee Firman said: "Our mouse study is the first to provide unequivocal evidence that sperm competition selects for an increase in the density of sperm-producing tissue, and consequently, increased testes efficiency,"
Man-made global warming is already melting the icecaps, reducing the space available to polar bears, but now there is another risk. Chemical pollutants are reducing the density of bear’s penis bone, making it harder for them to reproduce. Studies have shown that bears with high levels of PCBs (a pollutant) have smaller than average penis bones and testes.
“Together with a team from Canada, Dr Sonne examined buculum specimens from 279 polar bears that were born in north-east Greenland and Canada between 1990 and 2000. They used X-rays to study the density of calcium in the bones and then compared their findings with regional pollutant data. The team discovered a connection between low bone density and high PCB levels, but stressed that their findings are not strong enough to prove that the pollutants are the cause of the problem.”
By coaxing human stem cells to become dermal papilla cells, which are involved in follicle formation, scientists in Orlando believe they may be able to regrow human hair – and potentially a cure for baldness. Researchers managed to grow the hairs on the leg of a rat, and scientists wonder whether the technique could go on to work in humans.
Professor Terskikh said:
“Our stem cell method provides an unlimited source of cells from the patient for transplantation and isn't limited by the availability of existing hair follicles. Our next step is to transplant human dermal papilla cells derived from human pluripotent stem cells back into human subjects.”
Uloborus spiders spin a fluffy, charged, wool-like silk which comes out as a liquid (and solidifies). Their silk glands are one of the finest recorded at a mere 60 micrometres.
"As the spider yanks the silk from the duct, it solidifies into nanoscale filaments. This “violent tugging” has the effect of stretching and freezing the fibres into shape. It may even be responsible for increasing their strength, because filaments on the nanoscale become stronger as they are stretched. In order to endow the fibres with an electrostatic charge, the spider pulls them over a comb like plate located on its hind legs"
Diabetes in rats treated with an engineered microbiome. Scientists have engineered human lactobacilli, a common gut microbe, to secrete a protein GLP-1. When in contact with this protein, intestinal epithelial cells that cover the guts are converted into insulin-producing and monitoring cells, just like pancreatic cells. Diabetic rats that received the engineered probiotic ended up with up to 30% lower blood glucose levels.
“The rat study was a proof of principle, and future work will test higher doses to see if a complete treatment can be achieved”, said John March, professor of biological and environmental engineering in the College of Agriculture and Life Sciences and the paper’s senior author
A single copy of a gene linked to longevity is responsible for extra tissue in parts of the brain, which seems to protect against mental decline in old age. About 1/5 people inherit a single copy of the gene KL-VS, which improves heart and kidney function, and adds on average 3 years to the human lifespan. It also accounts for a 12% improvement in people’s mental test scores. When KL-VS was modelled in mice, scientists found this strengthened the connections between neurons and enhanced learning and memory. Scientists hope to be inspired by this pathway and turn it into a therapy to slow down Alzheimer’s disease.
“Our discovery adds to growing evidence that raising klotho levels, one of the effects of the KL-VS variant, may be a new therapeutic avenue for prevention or treatment of devastating diseases like Alzheimer’s,” said Dena Dubal, a neurologist at University of California, San Francisco.