Category Archives: Research Roundup

Research Roundup: Vaccine for Type 1 diabetes, refinement of stroke models leads to less animals used and more!

Welcome to this week’s Research Roundup. These Friday posts aim to inform our readers about the many stories that relate to animal research each week. Do you have an animal research story we should include in next week’s Research Roundup? You can send it to us via our Facebook page or through the contact form on the website.

  • Wound glue could replace internal sutures. Traditional sutures, staples, and wires are difficult to properly place in some areas of the body and do not close wounds immediately, which increases the risk of infection. Researchers have developed a human protein-based hydrogel sealant called MeTro that seals wounds in 60 seconds. Unlike other currently available sealants, MeTro contains all the characteristics of a successful surgical glue: it is elastic, adhesive, non-toxic, and biocompatible. It has successfully healed incisions in the arteries and lungs of rats and wounds in the lungs of pigs. MeTro remains stable while the wound heals, even when applied to tissues that constantly expand and relax, and then degrades without any traces of toxicity. Published in Science Translational Medicine.
  • Vaccine for virus induced Type 1 diabetes developed. The incidence of Type 1 diabetes is increasing while the etiology of the disease itself is unknown. One implicated environmental cause is enterovirus and in particular Coxsackievirus B (CVB). To investigate this link further, researchers inoculated mice with a CVB1 vaccine and tested whether this prevented the development of diabetes in a clinically relevant model. Prof. Malin Flodström-Tullberg stated: “these exciting results showing that the vaccine completely protects against virus-induced diabetes indicate the potential that such a vaccine has for elucidating the role of enteroviruses in human Type 1 diabetes.” This research was published in the journal Diabetologia.

  • Role of muscle in tissue regeneration. “One of the central mysteries in organ and tissue regeneration is, how do animals initiate all of the cellular and molecular steps that lead to regeneration?” states Peter Reddien. To investigate this question, these researchers turned to the planarian Schmidtea mediterranea. myoD. They found that longitudinal muscle fibers are responsible for initiating tissue regeneration while circular fibers aid with the formation of the correct pattern. These results underscore the relatively ignored role of different muscle fibers in tissue regeneration. This research was published in the journal Nature.

Whitehead Institute researchers have determined that a subtype of muscle fibers in planarians (top, wild type) is required for triggering the activity of genes that initiate the regeneration program. When these muscle fibers are removed, regeneration fails to proceed (middle and bottom).
Credit: Lucila Scimone/Whitehead Institute

  • Refinement of stroke induction method in mice promises a reduction in the number of animals used. Most strokes are caused by an abrupt blockage of arteries leading to the brain — ischaemic stroke. To model this in mice, the middle cerebral artery (MCA) of the brain is blocked. The limitation of this approach is that it often results in inconsistent lesion sizes – leading to a large number of animals being needed in order treatment effects being observed. In order to reduce variation in lesion size, these researchers modified the existing protocol so that incisions made in the blood vessels are repaired with tissue pads instead of these vessels being permanently tied off. This resulted in smaller variation in lesion size – and ultimately smaller numbers of animals being needed to detect statistically significant results. This study was published in the journal Disease Models & Mechanisms.

Research Roundup: Studying deadly cancers in dogs, low calorie diet and type 2 diabetes and more!

Welcome to this week’s Research Roundup. These Friday posts aim to inform our readers about the many stories that relate to animal research each week. Do you have an animal research story we should include in next week’s Research Roundup? You can send it to us via our Facebook page or through the contact form on the website.

  • “Researchers are turning to the family dog to find clues in hopes to find a cure for one of the deadliest forms of cancer.” Glioblastoma, a deadly brain cancer, killed over 15,000 people in 2015 and also affects dogs.  Researchers say that microscopic evaluation of the cancers in dogs and humans are very similar.  Roel Verhaak, a biologist and professor at Jackson Labs, says the goal of this research is to find anything, “..to prolong life expectancy and ultimately a cure.”  He and his team hope to find specific areas in the cells of the donated cancer tumors from dogs that are abnormal and compare them to abnormalities in the human form of the cancer.  Once this is clear, focus on faster ways to diagnose the cancer and more effective treatments can be developed.

Example of a short nosed dog.

  • Are all laboratory mice the same? Lab mice are commonly inbred through brother-sister mating. This practice of inbreeding allows researchers to study mice that are virtually genetically identical, thereby standardizing genes within and between experiments. However, between every 10 to 30 generations, new mutations pop up due to genetic drift — thus, not all mice are identical across generations despite inbreeding. To understand the degree of this problem, researchers at JAX “reset” the genetic mutations in 2005 by only selling C57BL/6 (B6) mice from an ancestral Adam and Eve. They then froze hundreds of embryos of the duo’s grandchildren to maintain genetically identical mice for 25-30 years, thereby bypassing issues of genetic drift. In a presentation at the American Society for Human Genetics’ Meeting, JAX scientists reported that their ancestral B6 mice have different genomes than B6 mice used by other breeding centers (e.g. Charles River) and the reference B6 genome all scientists use from 2002. The research will not be published until early 2018, so we will have to wait until then to learn how much genetic drift may be affecting experiments.

The C57BL/6 mouse.

  • The link between gut bacteria, high salt diet, cardiovascular disease and hypertension. Consuming a high salt diet is a risk factor for cardiovascular disease and hypertension. In the present study researchers investigated whether consuming a high salt diet affects the gut microbiome and whether this would be linked to subsequent detrimental health effects. In mice and humans, they found that a high salt diet let to a decrease in Lactobacillus bacteria in the gut and increased blood pressure. When given a probiotic, they found that that the bacteria and blood pressure levels remained unchanged. Professor Alm, the lead author on this research states ““We hope that our findings, along with future studies, will help to shed more light on the mechanism by which a high-salt diet influences disease.” This research was published in the journal Nature.
  • Low calorie diet reverses type 2 diabetes through multiple pathways. It is known that a low calorie diet can reverse type 2 diabetes — but the mechanism via which a low calorie diet exerts these effects is poorly understood. Using rats, researchers found that after only three days of being provided a very low calorie diet, specific metabolic processes in the liver were altered and which corresponded to the lowering of blood glucose concentrations. Professor Schulman stated: “These results, if confirmed in humans, will provide us with novel drug targets to more effectively treat patients with type 2 diabetes.”  This research was published in the journal Cell Metabolism.

 

Research Roundup: Human brain organoids, universal flu vaccine and more!

Welcome to this week’s Research Roundup. These Friday posts aim to inform our readers about the many stories that relate to animal research each week. Do you have an animal research story we should include in next week’s Research Roundup? You can send it to us via our Facebook page or through the contact form on the website.

  • Nighttime injuries heal slower than daytime ones. When animals are wounded, their body recruits different healing cells to help heal the wound. According to research this week, one of those healing cells — fibroblasts — travels at different speeds depending on the time of day. When a wound occurs, fibroblasts travel up through the skin to the surface and begin synthesizing and building structural support for the new skin. While traveling up through the layers of skin, fibroblasts come into contact with actin, which changes its structure throughout the day; long filaments during the day and globular at night. When actin is in a globular state, it is more difficult for the fibroblasts to reach the wound compared to when actin is in the long filament state. This finding was first discovered in skin-cells growing in a petri dish and then in the skin of mice. Medical records of humans recovering from burns show the same daytime-nighttime effect, but they have yet to study whether it is related to fibroblasts and actin. This research was published in Science Translational Medicine.
  • Ethical concerns on implanting human brain organoids in rodents. Almost 4 years ago scientists discovered how to turn human stem cells into human brain tissue (organoids). Since this discovery, scientists have been growing lentil-sized human brain tissue in test-tubes — until now. This weekend two research groups will report implanting human brain organoids into the brains of mice and rats, at the Society for Neuroscience Meeting in Washington D.C. The research reports that same of the implanted brain organoids became vascularized over the course of 2 months and the organoid began sending out axons to different parts of the host mouse brain. Bioethicists do not believe these procedures will make human-brained mice, but it may make them “human-ish.” This research is still in early stages and has not yet undergone rigorous peer-review, but the ethical concerns remain. Scientists may soon call for a commission to determine whether limits should be placed on how large the human brain organoids can grow, for example. Nonetheless, this research is exciting and may lead to many new animal models from Alzheimer’s to Zika. This research was published in an abstract for this weekend’s meeting.
  • Mother’s BPA exposure may influence offspring health. Bisphenol A (BPA) is an endocrine system disrupting chemical. Previous animal studies have shown that exposure to BPA is associated with cancer, behavior disorders, and reproductive issues. A new study conducted by researchers at Pennsylvania State University tested the effects of BPA on the offspring of female rabbits exposed during gestation. Rabbits were used in the study because they have a longer gestational period compared to rats and mice. The researchers found that BPA given to a pregnant female caused inflammation in the colon and liver of its offspring. Gut bacteria in the offspring exposed to BPA were also much less diversified, and offspring also had reduced beneficial bacterial metabolites and increased gut permeability (“leaky gut”). These three markers are hallmarks for inflammation induced chronic disease.  Using human colon cells, the researchers were able to reduce the gut permeability phenomenon by adding in the bacterial metabolites to BPA-treated cells. The researchers hypothesize that giving back bacterial metabolites lost through chemical exposure may reduce the risk of chronic diseases later in life. This research was published in mSystems.
  • Near-universal flu vaccine created. Influenza is a ubiquitous disease, with approximately 3-5 million cases yearly, and 250,000-500,000 deaths. Every year, a seasonal flu vaccine is created, that protects against either three or four of the more common predicted strains of influenza virus for the upcoming flu season. Sometimes, these predictions match and sometime they don’t. Now, scientists have created a new vaccine which could provide lifelong inoculation for most strains of the influenza virus. They accomplished this by identifying key set of ancestral genes in the older versions of different influenza strains and engineering a new vaccine. Mice inoculated by this new vaccine survived lethal doses of 7 out of 9 tested strains of the influenza virus. While there is still a way to go before this makes it to clinical trials – such as evaluation of lifelong immunity – this is a promising step. This research was published in the journal Scientific Reports

  • Breakthrough could lead to more effective treatments for diseases of the gut. The process where cells are broken down and elements recycled is called autophagy. This process helps to keep our bodies healthy, but when dysfunctional can cause tissue inflammation – particularly in the gut. In a new study, using fruit flies, researchers have identified that a protein called Kenny, accumulates and cause the inflammation when the process of authophay is dysfunctional. Understanding how autophagy process goes dysfunctional may lend insight into the development of effective treatments of diseases to the gut. This research was published in the journal Nature Communications.

Research Roundup: Fishy feelings, young blood and Alzheimer’s disease and more!

Welcome to this week’s Research Roundup. These Friday posts aim to inform our readers about the many stories that relate to animal research each week. Do you have an animal research story we should include in next week’s Research Roundup? You can send it to us via our Facebook page or through the contact form on the website.

  • Fish with feelings. Human emotion can be directly measured using interviews or surveys; however, the assessment of emotion in animals is not as simple. Fortunately, the behavioral, physiologic, neurologic, and genetic changes that accompany emotion can be assessed instead. For example, previous work has shown that highly evolved mammals, such as primates, display “jealous” behaviors. The occurrence of emotions in simpler animals, such as fish, has been debated for many years. A new study showed that Gilthead Sea Bream, a type of fish, displayed emotional reactions (i.e., investigative or escape behaviors) to stimuli presented under favorable or aversive conditions. Emotion was also assessed in the fish by measuring levels of cortisol and the activation of brain areas associated with positive and negative emotional states. This research indicates that simple animals may possess the cognitive ability to use emotions to guide their actions. This research was published in the journal Scientific Reports.

Gilthead Sea Bream, Image credit: Aqua EcoSystems

  • Results of first trial of infusing of young blood are in. Previous research in mice has suggested that infusion of young blood, through parabiosis, can improve the health of older mice. This work eventually led to the first small scale clinical trial in humans – involving the transfusion of young blood to older individuals with Alzheimer’s disease. Original reports of the results of that study were glowing – reporting modest improvements in the daily lives of these Alzheimer patients. However, subsequent scientific discourse has highlighted glaring problems with the experimental design and conduct of this clinical trial – including a high risk of bias and the lack of appropriate controls. This is a good example of the self correcting nature of science – and while this treatment still holds promise – the verdict on its efficacy in humans is still out.
  • MouseLight helps researchers unravel secrets of the brain. Researchers at the Howard Hughes Medical Institute Janelia Research Campus have created a 3D map of 300 mouse neurons, with the aim of adding another 700 in 2018. However, even this feat only scratches the surface of the 70 million neurons typically found in a mouse’s brain. Scientists injected a virus into the brains of mice which would infect a few cells and cause them to produce fluorescent proteins; they then imaged the brain with high-resolution microscopes and turned the resulting images into 3D computer models. They found many of the axons (slender projections of the neuron) were up to half a metre in length and stretched into unexpected regions of the brain, for example the neurons associated with taste also stretched into areas controlling movement and touch. More information on the project is available on the MouseLight website.

Brain of mouse lit up by MouseLight, Image Credit MouseLight

  • Tail regeneration in gecko and spinal cord injury. Lizard tails are an extension of their spinal cord and they have the ability to regenerate their tails, and thus spinal cords, when a section becomes detached. Researchers at University of Guelph have identified a special type of stem cell — the radial glial cell —  which allows geckos to regenerate their tail whenever it is detached and make a brand new portion of the spinal cord. Unlike geckos, humans do not have the radial glial cells and often make scar tissue following spinal cord injury rather than growing new cells. This specific research and related projects may one day help humans, and other mammals, to regenerate spinal cords  — which is not currently possible. This research was published in The Journal of Comparative Neurology.
  • Donor organs created by rebuilding pig livers. We have previously written about the use of genetically modified pigs and their valuable role in attenuating the organ crisis here. Now, a new method which uses pig organs as a scaffold for new organs – gives further promise to an end of the organ crisis. This method involves using a pig organ, dissolving the cells away from it, leaving the organ’s protein scaffold intact. Then, the scaffold is re-infused with human cells creating a “human organ” with a pig scaffold. This approach is promising because it reduces the likelihood of organ rejection. This research was presented at a meeting of the American Association for the Study of Liver Diseases in Washington DC this month.

Research Roundup: Alzheimer’s disease in the wild, second CAR-T therapy approved and more!

Welcome to this week’s Research Roundup. These Friday posts aim to inform our readers about the many stories that relate to animal research each week. Do you have an animal research story we should include in next week’s Research Roundup? You can send it to us via our Facebook page or through the contact form on the website.

  • Traces of Alzheimer’s Disease Detected in Wild Animals for the First Time. Researchers, including Simon Lovestone of Oxford University, have found evidence of Alzheimer’s in dolphins.  Dr. Lovestone asked the question, “Are dolphins, as a result of their long lives, susceptible to age-related neurological diseases, such as Alzheimer’s?”  To find the answer, he and his colleagues studied the brains of wild dolphins who died naturally.  The researchers found two proteins that are referred to as “the smoking guns of Alzheimer’s disease in humans” in these wild dolphins’ brains. It is not known if dolphins experience the same cognitive symptoms. The latter question can only be studied with captive dolphins which is not being advocated for by these researchers. They are hopeful that comparative studies of dolphin and human brains with Alzheimer’s will show what factors are responsible for the disease in order to develop treatments in the future.  This study was published in Alzheimer’s and Dementia.

Image credit: University of Oxford

  • Ottawa researchers develop new animal model for a rare, debilitating childhood disease. Pyridoxine-dependent epilepsy (PDE) is a rare disorder that causes infants and young children to suffer from prolonged seizures and related neurological problems which do not respond to commonly used epilepsy medications. Currently, symptoms are managed with large doses of pyridoxine, also known as vitamin B6. A team including researchers from the University of Ottawa and the Children’s Hospital of Eastern Ontario have developed a model for PDE using zebrafish that share the same genetic mutation as affected children. Newly hatched and very young zebrafish show similar epileptic and neurological symptoms which also respond to treatment with vitamin B6. The hope with this new animal model for PDE is for the development of new treatments, and better outcomes for the affected children. This research was published in Genetics.
  • A little myelin goes a long way toward restoring nervous system function. Myelin, the lipid/protein sheath that surrounds and protects nerve fibers, is critical for electrical signaling in the brain and for quickly sending nerve impulses from the brain to the body. Though it is well known that diseases of the nervous system, like multiple sclerosis, degrade myelin, what remains to be discovered is how myelin naturally repairs itself and whether thin myelin sheaths can restore brain circuitry over the long term. Researchers at the University of Wisonsin-Madison, studying a unique but common genetic mutation in Weimaraner dogs and remyelination of the optic nerve in cats, reported this week that renewed but thin myelin sheaths are sufficient to restore the impaired nervous system. Moreover, they can do so years after disease onset. These important findings confirmed that the gold standard for evaluating remyelination is the long-term persistence of myelin sheaths, which support nerve fiber function and survival. Future research will now be able to leverage this knowledge to test new therapies designed to promote myelin repair. The study was reported in the Proceedings of the National Academy of Sciences USA.

The normal mature dog spinal cord (A) has many axons surrounded by thick myelin sheaths (blue). In contrast, in the recovered 13-year-old dog with the genetic abnormality (B), there are many axons with thin myelin sheaths, identical to that seen in remyelination. Source.

  • FDA Approves Second CAR T-Cell Therapy. CAR T is a pioneering type of gene therapy for cancer. CAR T-cells are equivalent to given patients a “living drug”. “The therapy requires drawing blood from patients and separating out the T cells. Next, using a disarmed virus, the T cells are genetically engineered to produce receptors on their surface called chimeric antigen receptors, or CARs.” While this form of therapy has been in use in various small scale human trials, it is the second approval in the world for a type of CAR T therapy. Much of its success is due to pre-clinical safety and efficacy testing in animals models, such as mice — which we have covered previously. The “living drug”, known as Yescarta is produced by Kite Pharma and owned by Gilead Sciences and is approved for use against some types of large B-cell lymphomas. It costs 373,000 USD for the life-saving treatment.
  • Secrets to how rabies causes aggressive behavior untangled. Rabies is a viral disease which leads to encephalitis (inflammation of the brain) in mammals. While much is known about rabies, including our ability to vaccinate against it, a lot is unknown about how the rabies virus “hijacks” the brain and leads to aggressive behaviour. These researchers, using mice, investigated whether the rabies glycoprotein, which accumulates in the brain after virus exposure leads to behavioral changes. Dr. Harris, the lead researcher of this study stated, “When we injected this small piece of the virus glycoprotein into the brain of mice, the mice started running around much more than mice that got a control injection. Such a behavior can be seen in rabies-infected animals as well.” This research was published in the journal Scientific Reports.

Research Roundup: Killing cancer cells, growing drugs in chicken eggs and more!

Welcome to this week’s Research Roundup. These Friday posts aim to inform our readers about the many stories that relate to animal research each week. Do you have an animal research story we should include in next week’s Research Roundup? You can send it to us via our Facebook page or through the contact form on the website.

  • Growing drugs in chicken eggs may lower their cost. Interferon beta is a cell-signaling protein found in the body that acts against viruses, and is used to treat various illnesses ranging from multiple sclerosis to cancer. The downside is that the interferon protein molecule is extremely expensive to manufacture, costing between $300-$1000 for one microgram. Most dosages start at several micrograms; to treat multiple sclerosis, for example, the starting dose is 30 micrograms. Researchers developed a novel way to mass produce interferon beta using chickens genetically modified using CRISPR technology. While investigators still need to show that the chicken-produced protein is structurally the same as the protein in current medications, this technique could reduce the price of cancer drugs by at least 90%. Additionally, a drug produced using modified chickens, called Kanuma, has already been approved by the US Food and Drug Administration to treat Lysosomal Acid Lipase Deficiency. Researchers are currently writing up their results for publication.
  • How Studying Frog Embryos Is Helping Advance Tissue Engineering By Leaps And Bounds. The embryos and tadpoles of Xenopus frogs are transparent allowing researchers to observe their internal anatomy during development. This, and other features like their tolerance to extensive manipulation, make them easy to work with in a research setting. Frogs and humans have many similarities genetically and physiologically. Researchers at the University of Pittsburgh are working with frog embryos to understand the mechanical processes that guide the development of a complete living organism. They hope to use this to develop a tool that tissue engineers can use in regenerative medicine when building new tissue. Dr. Lance Davidson, professor at the University’s Swanson School of Engineering explains, “Many engineering fields have some kind of software or simulation tool that can take the guesswork out their designs before they actually start building. We are developing something similar for tissue engineers so they don’t have to rely on trial and error all the time.” They hope to apply this to support regenerative medicine therapies. Original source: Pitt’s Swanson School of Engineering

  • Engineered Proteins lower body weight in obese mice, rats, and primates. Obesity is an increasingly common problem throughout the world. Surgeries such as gastric bypass or sleeve are quite effective, however the procedure is highly invasive and can lead to permanent negative side effects. Because of these negative side effects, scientists are currently exploring what different types of proteins our bodies secrete during metabolism. One promising protein that they identified was growth differentiation factor 15 (GDF15). By treating obese mice with GDF15, scientists discovered that mice reduced how much food they were eating leading to a reduction in body weight, and had healthier metabolism. They then tested this treatment in obese rats and cynomolgus monkeys, and found the same results. Through more intensive tests they also discovered that treatment with GDF15 delays gastric emptying, changed food preferences, and activated areas of the gut-brain axis. This work is a great example of scientific discoveries following the path of mouse to rat to non-human primate and, hopefully one day soon, human. This research was published this week in Science Translational Medicine.
  • Zebrafish research guides new therapy possibilities for rare genetic disorder. Alagille Syndrome is a rare (1 in 100,000 births), potentially life-threatening genetic disorder that affects the heart, liver, and kidneys among other body systems. New research using zebrafish has helped to identify the tissues and genes which are important to the development of liver duct cells, and how the mutation associated with Alagille Syndrome causes development to go awry. The team, based out of Sanford Burnham Prebys Medical Discovery Institute, hopes that this discovery will aid in the development of regenerative therapies that will restore liver function, and possibly prevent the need for liver transplant in certain patients with this disorder. This research was published in Nature Communications.

Zebrafish: Wellcome Trust Sanger Institute

  • New compound targets energy generation killing cancer cells. Sperm cells can generate energy and they can do so in harsh conditions because they strategically contain mitochondria in their “head”. Cancer cells, can also survive under harsh conditions, and they can adapt to a shortage of nutrients by reprogramming the energy generation system. Cancer cells, in contrast to normal cells, contain an enzyme called FerT — and unsurprisingly — the only other cell containing this enzyme is sperm. Researchers hypothesized that by disrupting the activity of FerT in cancer cells – they would starve cancer cells of energy and that they would die. To this end – they created a synthetic orally administered compound (E260), and found in mouse cancer model – that indeed, cancer cells are killed. They also check other normal cells and found them to be unaffected. This research was published in the journal Nature Communications.

Research Roundup: Snail venom and cancer, reversal of advanced heart failure and more!

Welcome to this week’s Research Roundup. These Friday posts aim to inform our readers about the many stories that relate to animal research each week. Do you have an animal research story we should include in next week’s Research Roundup? You can send it to us via our Facebook page or through the contact form on the website.

  • Secrets found in snail venom may help treat cancer. Cone snails are marine mollusks that are found worldwide in warm climates. Usually reclusive, cone snails will produce a venomous sting when threatened using a single, harpoon-like tooth. They also use this venom to immobilize their prey, which are often much bigger and faster than the snails themselves. By examining the molecular makeup of cone snail venom, researchers are learning how a single toxin, which typically only affects the central nervous system, can also impact the immune system. This information may help develop therapies for cancers that involve uncontrolled overproduction of certain cells, such as gastric, breast, and lung cancers. Published in Scientific Reports.

In the wild, cone snails harpoon their prey as it swims by. In the lab, the cone snail has learned to exchange venom for dinner. Here, a snail extends its proboscis and discharges a shot of venom into a latex-topped tube.
Credit: Alex Holt/NIST

  • Scientists reverse advanced heart failure. Heart failure is one the most common reasons for hospital admittance in individuals 65 years or older. It occurs when the heart is unable to pump blood sufficiently to maintain the body’s needs. This week, researchers were able to reverse severe heart failure in a mouse model, by silencing the Hippo pathway. The Hippo pathway is associated with cell death, which occurs, for example, when heart tissue is starved of oxygen. Dr. James Martin, the corresponding author on this study states “Heart failure remains the leading cause of mortality from heart disease. The best current treatment for this condition is implantation of a ventricular assist device or a heart transplant, but the number of hearts available for transplant is limited”. This mouse model, which mimics the human condition of advanced heart failure, is therefore an exciting new avenue for further investigation into measures which limit the debilitating consequences of heart failure. This study appears in the journal Nature.
  • Zebrafish recover faster from stressful situations when housed together. Zebrafish are a small, schooling minnow-like species increasingly used in many aspects of biomedical research. A new study shows that when zebrafish are housed together after a stressful procedure, they recover faster, resume normal behaviours and even have lower levels of stress hormone than fish housed alone. The study also demonstrated that stress hormone levels can be measured non-invasively by sampling the water directly from fish tanks. Refining how we work with zebrafish, and discovering better ways to provide for their welfare needs are important aspects of doing valuable life-saving research with these animals. This research was published in the journal Animal Behavior.

Zebrafish: Wellcome Trust Sanger Institute

  • The link between caesarean sections, the microbiome, and obesity. Caesarean section, a.k.a. C-section, is a life-saving practice for delivering 10-15% of human newborns. However, C-section is also overused in the developed world with some regions delivering 43% of newborns by C-section. Although this practice is quite common, scientists and medical doctors understand little about the long-term effects of C-section. This week, scientists have uncovered evidence that being delivered by C-section is linked to an increased risk of obesity in mice. This link between C-section and obesity deals with the gut microbiome. When humans, or laboratory mice, are delivered normally they travel through the vaginal canal and get exposed to vaginal microbiota. C-section circumvents the vaginal canal and thus the newborns do not get exposed to this vaginal microbiota. Research published this week in Science Advances indicates that mouse pups born by C-section weigh significantly more than those born normally. They also have a different gut microbiomes. This research does not necessarily mean humans born by C-sections are at higher risk for obesity, because human newborns often get antibiotics immediately after delivery and mice are fostered to new mothers after being delivered by C-section. Nonetheless, this is a great step towards further understanding the consequences of C-section deliveries.
  • The validity of studies on the transplantation of tumours to mice questioned. This week ,a study published in the journal Nature Genetics, described changes in the genome of tumor tissue implanted into immunodeficient mice that may affect interpretation of research results. Human tumors can be studied in cell culture medium or by implanting cultured cells into immunodeficient rodent models. However, the process of ‘immortalization’ of cells grown in artificial culture medium alters the cells in ways that limit their usefulness as a model in tumor biology.  As an alternative, tumors collected from patients can be implanted directly into rodents (PDX or patient-derived xenograft avatars) to study their activity and response to therapeutic drugs.  This approach has been thought to better replicate the behavior of tumors in human patients with improved predictability of the model as a desired outcome. However, the study in Nature Genetics by Uri Ben-David and colleagues found that the unstable genome in many tumors continues to change after implantation into the mouse, and can accumulate mutations that differ in behavior and response to chemotherapeutics from the original patient tumor. These findings do not negate the value of the PDX avatar model, but do highlight the need for further investigation to determine how the genomic changes that occur affect the interpretation of results derived using this type of model.