 Welcome to the latest news roundup from Understanding Animal Research where we will be running through some of the recently published scientific studies and news articles that involve animal research. As usual, you can find more detail on each of these stories on our website and links are provided in the caption below. Our first story is a remarkable new device made from a nano-material with the thickness of a single atom. Dubbed the graphene tattoo, the device acts like a pacemaker, delivering pulses of electricity to the heart in order to correct an irregular heartbeat. The graphene tattoo is a welcome development in the field of pacemakers, which usually fail between 5 and 15 years after implantation due to the rigid and metallic materials that they are made from. So far, this new device has been tested in mice and rats with promising results. New research from McGill University in Canada has discovered a link between a family of proteins called PRLs and the spread of cancer. PRLs, or phosphatases of regenerating liver, are a family of proteins involved in cell growth and metabolism. PRLs have been found in various species of animals, including humans. Known to play a unique role in the growth and spread of cancerous tumours, the latest research has confirmed that PRLs exist in all kinds of single and multi-cell animals and that the role of PRLs in binding magnesium transporters is common among all of the studied species. They also found that over-expression of PRLs results in more metastic cancer cells and increased spread to other organs. Scientists in China have created the first mock embryos grown from monkey cells. Mock mouse embryos were first created in 2018, but these embryos have limitations and they are not as comparable to human development. Which is why researchers at the Chinese Academy of Scientists have created blastoids using the embryonic stem cells of synomulgus monkeys. Raised and housed in cell cultures, the blastoids can survive for up to 18 days and develop further than any previous blastoid of this nature. As part of the study, researchers inserted 7-day-old blastoids into 8 female monkeys, 3 of which began to show hormones that indicate pregnancy. The results suggest that the blastoids can implant into the uterus and emulate aspects of pregnancy. A researcher involved in the study comments that the blastoids did not continue to develop inside the syrogate mothers suggesting that they are not perfect copies. She goes on to say that it's reassuring that the blastoids didn't develop further and that this failure should discourage disreputable individuals from trying to pitch human blastoids as a fertility treatment. A new study sheds light on the ever-growing body of evidence that microplastics are affecting people, animals and the environment. We now have evidence that microplastics can enter the blood-brain barrier after being ingested. The blood-brain barrier is a critical mechanism for preventing toxins from entering the brain and it's an area that scientists have been particularly interested in for some time as it can prevent medicines from reaching the brain directly. Scientists may have struggled to breach the blood-brain barrier but recent studies have shown that microplastics have no problem clearing this hurdle. In studies using mice and computer models scientists have shown that tiny plastic particles can move through the protective blood-brain barrier and identified how they do it. Quite worryingly, in tests that used mice, microplastics were found inside the brain just two hours after being ingested. This is not the first study to find microplastics inside sensitive areas of the body. Previous studies have shown that microplastics can have serious consequences when passing through other areas of the body such as the intestine. New research from MIT has shown how serotonin affects behaviour from individual molecules to the entire brain using C. elegans a tiny non-parasitic nematode worm. Serotonin is a chemical in the brain which influences mood and it's been a common target for medicines that look to reduce or eliminate depressive symptoms and other symptoms related to psychiatric disorders. There has been substantial research into developing medications that affect serotonin levels. However, our understanding of how serotonin affects behaviour has remained incomplete until now. Steve Flavill, senior author of the study says there have been major challenges in rationally developing psychiatric drugs that target the serotonergic system. The system is wildly complex. The results of the study have given science a new understanding of how serotonin acts on different sets of receptors and how these receptors modulate behaviour and activity across the brain. Researchers at Harvard University have discovered a new organelle inside the gut cells of fruit flies. Organelle are structures within cells that have one or more specific roles to perform which are essential for the whole cell to function. Well-known organelle include nuclei and mitochondria commonly referred to as the powerhouse of the cell. The newly discovered organelle's function is to stockpile phosphate, a chemical essential to maintaining a healthy body. If a shortage of phosphate occurs, the new organelle releases its stockpile in the form of phospholipids an essential component of the membrane structure of cells. New research in mice has discovered why some COVID-19 patients suffer severe inflammatory illnesses such as myocarditis, pericarditis, liver injury and acute kidney injury. Results from the study provide important insights on SARS-CoV-2 and the common cold including new possibilities for treating COVID-19, how cytokine depletion may relieve symptoms, why patients with rare kidney disease become more ill after infection with the common cold and how COVID-19 causes multi-organ injury in some patients. You can read more detail on the findings of this study in the links provided in the caption below. And lastly, we are ending with a new 3Rs development, a brand new brain organoid. It's always an exciting time for researchers when a new approach methodology is developed as they can contribute significantly to reducing the overall number of animals used in scientific study. The brand new batch of brain organoids have been created using primate cells by scientists at the German Primate Centre, Leibniz Institute for Primate Research in Gottingen. As stated in the original news article, scientists have now succeeded in genetically manipulating brain organoids quickly and effectively. The procedure requires only a few days instead of the usual several months and it can be used for organoids of different primate species. The brain organoids enable researchers to compare the function of different genes at early stages of brain development in primates and help us to better understand neurological diseases. Whilst brain organoids are not yet complex enough to replace a whole living animal, they play a distinct and welcome role in reducing the overall numbers of animals used in scientific research.