A new – astrocytic – hypothesis has been put forward by Aleksei Boyko, Ukrainian researcher, specialist of the National Agrarian University of Ukraine. In the framework of this hypothesis, ageing is treated as a result of changes in cerebrum cells. The key role is played by transmutation of cells of the radial neuroglia into stellate cells - astrocytes. Since such cell transmutation is a programmed process, the researcher is inclined to the opinion that ageing and following death have been programmed.
The researcher analyzed and compared animals with different ageing rates, and noticed that the majority of reptile, fish and amphibian species which grow old rather slowly have a very high regenerative activity of neural tissue. In other words, these species are able to quickly eliminate nervous system damage and replace extinct nerve cells (neurons). Mammals and birds have almost fully lost the regenerative capacity of the neural tissue, with new neurons formed only in certain parts of the cerebrum, for example, in the walls of the lateral ventricles of the hippocampus. Neuron predecessors – neuroblasts – migrate into various parts of the brain via radial neuroglia fibres, and turn into full-fledged neurons to replace extinct or damaged cells.
The researchers have found out that the mammals undergo changes during their life, with gradual transformation of radial neuroglia cells and transmutation into astrocytes. The astrocytes do not allow neuron predecessors to migrate to the required areas. Thus, renovation of brain cells becomes impossible, and brain cells, having lost their vital resource, ultimately mortify. Such age-specific brain changes undoubtedly cause changes to other internal and organ systems of the organism, with vascular derangements, hormonal status change, brygmus, alopecia, intercellular collagen accumulation, among the common signs of ageing. In contrast to mammals, amphibians such as fish and reptiles preserve their radial neuroglia cells throughout the life cycle, and ageing happens more slowly.
According to the researchers' astrocyte hypothesis, this is a probable ageing mechanism. They believe that it is the presence or absence of radial neuroglia cells that determines the life span.
Nadezda Markina | alfa
Biologists unravel another mystery of what makes DNA go 'loopy'
16.03.2018 | Emory Health Sciences
Scientists map the portal to the cell's nucleus
16.03.2018 | Rockefeller University
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences