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.
- 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.
- 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.