Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Selfing DNA prevents genomes from mixing

11.10.2002


Genomes of multicellular organisms are one of the greatest mysteries of biology. The more is discovered about them, the more questions are to be answered. One of such questions is connected with the size of a genome. As is known since the middle of the 20th century, the level of organization of an organism does not depend on the genome size, i.e., on the amount of DNA in the nucleus of a cell. Sometimes, a primitive organism contains much more DNA than a mammal. For example, the genome of certain amoebas is 200 times as large as that of humans. The nature of this phenomenon has been understood very recently. The most part of DNA does not contain any of protein-coding genes. Because of its unclear function, it is called the selfing or junk DNA, which is somewhat abusive. Its share in genomes of some species riches 95% (in human genome, its content is 75%). The selfing DNA can hardly serve as a material for evolution: it is so unstable that has no time to develop into a functional structure. However, as long as each species has its specific junk DNA, it must serve for something.



Different scientists tried to find an explanation for the biological purpose of the selfing DNA. About fifteen hypotheses were offered, and most of them turned to be invalid. In Russia, this problem has been studied for many years by doctor of biological sciences Aleksei Akifyev and his colleagues. The scientists believe that an actual function of the selfing DNA stands behind a phenomenon known for already 100 years and called the chromatin diminution. This is a key term in this context, let us remember it. The chromatin diminution is the elimination of an inactive chromatin from a genome. Some multicellular animals, such as ascarids and small crustaceans Cyclopoida, lose an important part of their chromosomal DNA at the early stages of embryogenesis. The diminution normally takes place in cells that are to build the body and never occurs in developmental precursors of germ cells. The latter still have all their selfing DNA. Apparently, these are the cells, in which the selfing DNA is functionally significant. The scientists have revealed that the selfing DNA prevents the confusion of closely related species.

Aleksei Akifyev and his colleagues have studied the genetic isolation mechanism using near species of crustaceans Cyclopoida as an example. The chromatin diminution is characteristic of one species and never occurs with the other. The researchers suggest that the DNA elimination is performed by certain enzymes that cut the genome at the right time and in the right place and are contained in the cytoplasm of an ovum. If a sperm cell of one species enters an ovum of another species, then the embryo dies either because of a failure to perform a necessary diminution or because of an unreasonable elimination of vital chromosomes by aforementioned enzymes.


The chromatin diminution never takes place in cells of humans and most animals, but they isolate the selfing DNA in another way ? by placing it in a position unreachable for most enzymes and thus making it functionally cut off. Each species has a unique structure and packing of the selfing DNA. In other words, indirect ways of a physical separation of some part of genome are known for many organisms.

Thus, a certain part of a genome with a particular size and structure serves for the genetic isolation of species. Therefore the selfing or junk DNA is not a piece of garbage, but a vital component. If one mechanism eliminates it, another mechanism should restore it while a species still exists. The scientists expect to understand more, if they will manage to reveal the molecular organization of the selfing DNA. The most suitable material for this study is DNA lost from cells as a result of the diminution.

Natalia Reznik | alfa

More articles from Life Sciences:

nachricht Discovery of a Key Regulatory Gene in Cardiac Valve Formation
24.05.2017 | Universität Basel

nachricht Carcinogenic soot particles from GDI engines
24.05.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Physicists discover mechanism behind granular capillary effect

24.05.2017 | Physics and Astronomy

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017 | Physics and Astronomy

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>