This week in animal research 18/11/16
Alzheimer’s disease can be prevented by stopping a crucial brain protein from turning rogue, a study in mice suggests.
Tau protein has long been suspected to play a role in causing the condition. In healthy brains, tau is essential for normal cell functioning. But during Alzheimer’s disease, the protein goes haywire, clumping together to form twisted tangles and, it is thought, releasing toxic chemicals that harm the brain.
Now Lars Ittner at the University of New South Wales, Australia, and his colleagues have pinpointed a crucial enzyme that controls how tau proteins behave in the brain. The enzyme, called p38γ kinase, helps keep tau in a healthy, tangle-free state, preventing the onset of memory loss and other symptoms in mice that have been bred to develop Alzheimer’s disease.
US researchers have synthesised a deadly toxin produced by poison dart frogs and made the toxin’s non-natural mirror image too.
BTX is a steroidal alkaloid and one of the most potent known natural toxins – it takes just 0.1mg to kill an average adult human. It works by irreversibly binding to pore-forming membrane proteins which function as voltage-gated sodium channels that help to conduct nerve impulses. BTX permanently opens sodium channels and prevents transmission of nerve signals leading to paralysis and heart failure.
Since its isolation from Colombian poison dart frogs in 1963, BTX has given scientists a way to study the role of sodium channels in many disorders including epilepsy, heart problems and pain. But with poison dart frogs now endangered and a lack of efficient synthetic route to produce BTX, the world’s supply has dwindled to less than 170mg.
M M Logan et al, Science, 2016, 354, 865 (DOI: 10.1126/science.aaf9717)
Lasers shone into the brains of mice can now activate individual neurons — and change the animals behaviour
Scientists have used the technique to increase how fast mice drink a milkshake, but it could also help researchers to map brain functions at a much finer scale than is currently possible.
Neuroscientists at Stanford University in California conducted their experiments on mice that were genetically engineered to have light-sensitive neurons in a brain region called the orbitofrontal cortex. That area is involved in perceiving, and reacting to, rewards. By shining a laser at specific neurons, the researchers increased the pace at which the mice consumed a high-calorie milkshake.
Transplanted pig's heart survives in monkey for at least 51 days in new record
The heart was genetically modified to reduce the risk of the monkey's immune system attacking it
Muhammad Mohiuddin, a cardiac transplant surgeon at National Heart, Lung, and Blood Institute in Bethesda, US, who lead the baboon study, told Science magazine: “People used to think that this was just some wild experiment and it has no implications.
“I think now we’re all learning that xenotransplantation in humans can actually happen.”
Gene-editing technique partially restores sight to blind rats
Blind animals have had their vision partially restored using a revolutionary DNA editing technique that scientists say could in future be applied to a range of devastating genetic diseases.
The study is the first to demonstrate that a gene editing tool, called Crispr, can be used to replace faulty genes with working versions in the cells of adults - in this case adult rats.
Before being used in humans, it would also need to be made more efficient, as only about 5% of cells had their faulty DNA replaced, the study found.
Human blood for old mice
Plasma from human blood was injected into old mice, appearing the slow the ageing process. Those receiving blood plasma were better at solving memory problems than a control group. It is believed that "younger" blood is able to increase neurogenesis.
Vaccines developed that protect mice from iron-scavenging molecules during infection
Researchers at the University of Michigan and the University of California have developed vaccines that protect mice from iron-scavenging molecules during infection. Bacteria have special molecules called siderophores that bind to iron and remove it from proteins in which it is already bound. Scientists have tried to exploit this mechanism by devising vaccines that unleash antibodies against the receptors. Whilst more work is required before the vaccines can be tested in humans, this could be an alternative to antibiotics, which are becoming increasingly ineffective and often wipe out good bacteria as well.