Navigation Links
Parasites ready to jump
Date:7/31/2009

Transposons are mobile genetic elements found in the hereditary material of humans and other organisms. They can replicate and the new copies can insert at novel sites in the genome. Because this threatens the whole organism, molecular mechanisms have evolved which can repress transposon activity. Professor Klaus Frstemann of the Gene Center of Ludwig-Maximilians-Universitt (LMU) in Munich and a team of researchers working with the fruitfly Drosophila melanogaster have now uncovered a new type of cellular defence that acts against DNA sequences present in high copy numbers inside the cell, even if they have not integrated into the genome. Small molecules of RNA (a class of nucleic acid closely related to the genetic material DNA) play the central role. "Transposons are genomic parasites, so to speak", says Frstemann. "If they are allowed to proliferate, the genome can become unstable or cancers can develop. We now want to find out whether mammalian cells possess this newly discovered defence mechanism and to elucidate precisely how it works." (EMBO Journal online, 30 July 2009.)

Transposons constitute a significant fraction of the genomes of most higher organisms. Indeed, it is estimated that these mobile elements, which include one or more genes, make up as much as half of the genetic material. "This demonstrates", says Frstemann, "that it is not always possible to tame these "selfish" genetic elements, although highly efficient mechanisms of defence have evolved. For instance, in the germ cells, which are required for reproduction, the system of so-called piRNAs ensures that transposon activity is inhibited but only if these RNAs are transmitted from the mother. Disruption of this system usually leads to a drastic reduction in the fertility of the progeny.

Germ cells are an ideal target for transposons, since these cells pass their genetic material together with integrated mobile elements on to all cells of the progeny. But normal body (somatic) cells can also be attacked by transposons. For example, certain viruses carry transposons in their genomes and introduce them into the host cells they infect. Therefore, transposon activity must also be repressed in somatic cells. Recently so-called endo-siRNAs that perform this function were discovered in the fruitfly. A similar class of molecules has been found in mice.

By means of a process called RNA interference, the siRNAs enable the cell to recognize and destroy messenger RNAs derived from transposons. The researchers in Frstemann's group were able to identify a protein that is essential for the production of endo-siRNAs. It turns out that this is a previously unknown variant of the protein "Loquacious". In Drosophila, Loquacious can bind to specific RNA molecules that serve as precursors of the endo-siRNAs. Furthermore, the team pinpointed an entirely novel feature of this system: Repression of transposon activity was also detectable when multiple copies of a mobile element were present in the cell but not yet incorporated into the genome.

The phenomenon of RNA interference first came to light only a short time ago, but has already become a well established field of study. Thanks to more recent findings, the known repertoire of small RNAs has grown. As Frstemann stresses, "It is therefore particularly important to discriminate between the various molecular classes in terms of their modes of synthesis and specific functions". This is no easy task, since all these molecules are similar in size and virtually indistinguishable chemically. "We will now test whether the mechanism we have found in Drosophila also exists in mammalian cells. We would also like to know how the mechanism is targeted specifically against sequences present in high copy numbers".


'/>"/>

Contact: Professor Klaus Frstemann
foerstemann@lmb.uni-muenchen.de
49-892-180-76912
Ludwig-Maximilians-Universitt Mnchen
Source:Eurekalert

Related biology news :

1. Discovery to aid in future treatments of third-world parasites
2. Study finds role for parasites in evolution of sex
3. Immune genes adapt to parasites
4. Locking parasites in host cell could be new way to fight malaria
5. Scripps Florida scientists awarded $1.5M to fight major water and food parasites
6. Purifying parasites with light
7. Parasites outweigh predators in Pacific Coast estuaries
8. Study shows parasites outweigh predators
9. Monarch butterflies help explain why parasites harm hosts
10. Disrupting common parasites ability to talk to each other reduces infection
11. Parasites might spur evolution of strange amphibian breeding habits
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:12/16/2016)... , Dec. 16, 2016 The global wearable medical device ... billion by 2021 from USD 5.31 billion in 2016, at a ... ... driven by technological advancements in medical devices, launch of a growing ... for wireless connectivity among healthcare providers, and increasing focus on physical ...
(Date:12/15/2016)... 2016   WaferGen Bio-systems, Inc. (NASDAQ: ... announced today that on December 13, 2016, it received ... Nasdaq Stock Market LLC which acknowledged that, as of ... common stock had been at $1.00 or greater for ... with Listing Rule 5550(a)(2) of the Nasdaq Stock Market. ...
(Date:12/15/2016)... Dec. 15, 2016 Advancements in ... health wellness and wellbeing (HWW), and security ... three new passenger vehicles begin to feature ... recognition, heart beat monitoring, brain wave monitoring, ... monitoring, and pulse detection. These will be ...
Breaking Biology News(10 mins):
(Date:1/17/2017)... ... January 17, 2017 , ... One Million Solutions in Health ... million in investment towards 15+ TEC Validation Projects™. As a pre-competitive consortium, ... in drug safety assessment, for the industry as a whole. , Through the ...
(Date:1/16/2017)... ... January 16, 2017 , ... Appellate Court of New ... the appeal filed by India-based Dishman Pharmaceutical & Chemical Ltd. company (DPCL) for ... one of its Dishman Group’s 100% wholly owned New Jersey-based subsidiary Dishman USA ...
(Date:1/14/2017)... -- The Alliance for Safe Biologic Medicines (ASBM) today issued ... guidance on biologic naming: We commend ... importance of distinct naming for all biologics, including biosimilars. ... will bring to patients, including new treatment options and ... the Guidance dealing with suffix design remains at odds ...
(Date:1/13/2017)... Island, NY (PRWEB) , ... January 13, 2017 ... ... teamed up with several companies to offer its customers three new solutions for ... probe would come in handy if a customer has an oddly-shaped sample that ...
Breaking Biology Technology: