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Gut microbiomes run in families
New research from the UK published in Cell Host and Microbe has revealed that some parts of our microbiomes are inherited and shaped, not through a spread of microbes from parent to child, but through our genes. The investigators analysed the gut microbiomes of 1126 pairs of twins who were part of the TwinsUK study. This multi-year research effort, which includes a total of 12 000 twins, is looking at a number of diseases and conditions. The twins in the current study had already had their genomes analysed, and 1.3 million small genetic variations (also known as single-nucleotide polymorphisms) were known for each participant. The investigators used the genome-wide association approach to look for connections between genetic variations between twin pairs and certain bacterial types that were present and stable in the study subjects. One connection they were able to make was between the LCT gene, which is involved in making the enzyme that helps the body digest dairy products, and a type of microorganism called Bifidobacterium, which is commonly used in probiotics. They also found links between specific gut bacteria, blood pressure and self and non-self-recognition. “We identified more than a dozen microbes with known links to health that are heritable,” said the lead author on the research.
First proof Zika virus causes birth defects in animals
Research published in Nature is the first to prove that the Brazilian Zika virus (ZIKVBR) causes birth defects in animal models. Scientists from the University of California-San Diego used ZIKVBR isolated from a clinical case in northeast Brazil to infect two different strains (SJL and C57BL/6) of pregnant mice (two to six mice across several experiments). They evaluated the pups immediately after birth and found that those born from SJL ZIKVBR-infected females displayed clear evidence of whole-body growth delay — or intrauterine growth restriction — and showed signs of microcephaly, such as cortical malformations, compared to controls. No significant changes were observed in pups born from C57BL/6 ZIKVBR-infected females, which may be due to the robust anti-viral immune response of this mouse strain. They also showed that the virus was capable of inducing cell death in mouse neural tissue and that it could infect human brain organoids, inducing cell death and disrupting cortical layers. Their analyses suggest that ZIKVBR crosses the placenta and causes microcephaly by targeting cortical progenitor cells, inducing cell death and impairing neurodevelopment.
Genes found for educational achievement
An international study including research teams from the Universities of Queensland, Newcastle, and South Australia, as well as the QIMR Berghofer Medical Research Institute, Hunter Medical Research Institute, Queensland Institute of Technology, and the South Australian Health and Medical Research Institute, has identified 74 genetic “hot spots” associated with educational attainment. After studying the genomes of 300 000 people, the researchers found the 74 genes that may play a role in how long a person stays in school or whether they go to university. They also found that the genes that are associated with higher educational attainment are, on average, also associated with a decreased risk of Alzheimer’s disease. However, the researchers said that genetics only contribute about 20% towards educational attainment and that a person’s environment and social connections have the biggest influence on their school success. The research was published in Nature.
Neurotensin points to obesity
Middle-aged people with high levels of the chemical messenger neurotensin (NT) are twice as likely to become obese later in life compared to people with low levels, suggests a new study by US and Swedish scientists, published in Nature. NT could therefore be a potential target for obesity prevention and treatment, say the researchers. Although high levels of NT are known to be associated with increased risk of diabetes, cardiovascular disease and death, this is the first study to show that NT is required for these diseases. NT-deficient mice fed a high-fat diet absorb less fat than their wild-type littermates and are also protected from other conditions related to high fat intake, such as increased insulin resistance. In both mice and fruit flies, NT inhibits the activity of a key enzyme (AMPK) that regulates metabolism. This pathway, the researchers suggested, may have been conserved through evolution to ensure the efficient absorption of ingested fats. An analysis of 4632 human adults involved in a longitudinal study showed that pro-NT levels were significantly associated with body mass index and waist size. Non-obese people with pro-NT levels in the highest quartile were more than twice as likely to become obese later in life as those with pro-NT levels in the lowest quartile.
Glioma susceptibility in dogs may inform human condition
New research published in PLOS Genetics examining the genetic susceptibility of certain dog breeds to gliomas, may provide insights into how these brain tumours form in humans. Gliomas are the most common form of malignant primary brain tumours in humans and the second most common in dogs. Several dog breeds such as Boxer, Bulldog and Boston Terrier have an elevated risk of developing glioma, while certain related breeds do not, suggesting that a mix of genes may impact glioma formation. To identify genetic variations that contribute to the development of the tumour, the researchers performed a genome-wide association study using blood samples from 39 dogs diagnosed with glioma and 141 control dogs. By screening for variations commonly found in dogs that developed gliomas, they pinpointed three genes highly associated with susceptibility to the tumour: CAMKK2, P2RX7 and DENR. Two of these genes have additional links to cancer. Further experiments by the researchers showed that both human and canine gliomas express CAMKK2 at lower levels than normal brain tissue, and previous studies have shown that a variation of P2RX7 reduces protein function in dogs while other variations have been identified in cancer patients.