In this newsletter we describe how structures called ERCs – extrachromosomal rDNA circles – contribute to the aging process when they bind to the nuclear pore complex. Plus, mouse sperm target zebrafish eggs, and a new marsupial model organism.
– Peter Rodgers, Chief Magazine Editor
A marsupial called the fat-tailed dunnart (S. crassicaudata) is emerging as an important model organism for evolutionary developmental biology. Image credit: Alan Couch (CC BY 2.0)
Aging is a process that involves small molecular defects gradually building up to a point where an organism can no longer function, ultimately leading to its death. Research on the model organism S. cerevisiae (budding yeast) has suggested that structures called ERCs – short for extrachromosomal rDNA circles – have a role, but the mechanisms by which they influence the aging process were not understood. Now, as explained in this Insight article, ERCs exert their influence by tethering to the nuclear pore complex, which is the main gateway in and out of the nucleus in cells. The disruption caused by the ERCs results in the production of non-functional proteins, leading to mis-segregation of chromosomes, which is a hallmark of aging. Similar effects may also influence the aging process in animals.
Until recently, it was believed that the mechanisms that help sperm recognize and respond to eggs were different for mammals and fish. In mammals, for example, the sperm must penetrate a ‘coat’ around the egg called the zona pellucida, while in teleost fish the sperm has to pass through a narrow canal called the micropyle. Now, as reported in eLife, researchers have shown that mouse sperm can locate and enter the micropyle in zebrafish. This and other findings suggest that, despite the many differences between the eggs of mammals and fish, sperm may rely on evolutionarily conserved mechanisms to find and navigate toward the egg.
Cell migration is a crucial process in biology, and it is well known that blood vessels act as guides for different types of migrating cells, including neurons. However, an important research question has remained unanswered: can differences in blood flow influence cell migration? Now, as described in this Insight article, 3D imaging experiments with mice aged 6–12 weeks have shown migrating neurons accumulating near blood vessels with a high flow rate, with migration either slowing down or stopping when the blood flow is reduced. The researchers also identified ghrelin – a hormone that rises during fasting – as a factor that mediates the effect of flow rate on migration.
Unlike humans and other placental mammals, marsupials give birth to highly premature offspring that have to complete most of their development within their mother’s pouch. This means that newborn marsupials possess traits that are critical for immediate survival outside the womb, such as well-developed forelimbs for climbing into the pouch. It also means that marsupials are a powerful system for investigating the genetic mechanisms underlying development. With its short gestation period and extremely undeveloped state at birth, a marsupial called the fat-tailed dunnart (S. crassicaudata) is emerging as an important model organism. Now, as reported in eLife, comparisons between the dunnart and the laboratory mouse – a well-established placental model – have the potential to provide important insights into evolutionary developmental biology.
Learning new cognitive skills, such as navigating an unfamiliar city, is a fundamental part of daily life, but scientists still do not fully understand how the brain changes as these skills are acquired. Previous studies have suggested that experts with many years of training, such as taxi drivers, may experience increases in the size of certain structures in the brain, but we do not know how short-term training affects the brains of typical healthy adults. Now, based on a study in which 75 people were subjected to structural and functional brain imaging before and after intensive training programs, it is clear that the new skills are associated with changes in the connectivity between different regions of the brain, rather than any changes in its physical structure.
Social media, AI and other digital technologies have profound impacts on public health, politics and society at large. For this reason, write Joseph Bak-Coleman and colleagues in a preprint, “it is critical to develop a scientific understanding of these impacts to inform evidence-based technology policy that minimizes harm and maximizes benefits.” However, they continue, the data needed to understand these impacts are generated and controlled by the same industry that might be subject to evidence-based regulation. Moreover, tech companies also fund much of this research. Bak-Coleman et al. make a number of recommendations to avoid these problems, including stricter policing of conflicts of interest, greater use of institutional review boards, and better access to tech data for researchers.
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