Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Maelstrom quashes jumping genes

12.08.2008
Scientists have known for decades that certain genes (called transposons) can jump around the genome in an individual cell.

This activity can be dangerous, however, especially when it arises in cells that produce eggs and sperm. Such changes can threaten the offspring and the success of a species.

To ensure the integrity of these cells, nature developed a mechanism to quash this genetic scrambling, but how it works has remained a mystery. Now a team of scientists, including researchers at the Carnegie Institution's Department of Embryology, has identified a key protein that suppresses jumping genes in mouse sperm and found that the protein is vital to sperm formation.

"There is a tiny cell component that is unique to germ cells—the precursors to egg and sperm—called nuage, which means 'cloud' in French. Other researchers recently suspected that nuage was involved in keeping genes from jumping around in germ cells of the female fruit fly," explained Carnegie's Alex Bortvin, a senior author of the study. "But until this mouse study, no one knew for sure if it was involved in mammalian germ cells. To test if the mouse nuage played a similar role in mammals, we focused on a mouse protein called Maelstrom whose distant relative protein in the fruit fly was implicated in the other study."

In this research, published in the August 12th issue of Developmental Cell, the scientists first looked at where the protein Maelstrom resides during the formation of sperm. By marking the protein with a fluorescent antibody, they found that it was predominantly located in the cytoplasm, near the nucleus of the germ cell, at the nuage. To understand what Maelstrom does during the formation of sperm, the scientists created mutant mice that did not have the gene to produce the Maelstrom protein.

"We found that without the gene the process of meiosis was severely impaired," said Bortvin. "There was a profound defect in interactions of parental chromosomes, a process known as synapsis, leading to death of germ cells. This was clear evidence that the protein is vital to the formation of sperm."

The cause of such a defect became apparent when the researches looked at the behavior of transposons. "We observed massive flooding of the cytoplasm and nuclei of germ cells by transposons in the mutant mice," said Godfried van der Heijden, a Carnegie postdoctoral fellow and co-author. "This was the first time such a phenomenon was observed in germ cells of any species. Moreover, we found that the more transposons present in the nucleus, the more likely parental chromosomes would fail to locate each other during synapsis. Clearly, uncontrolled activity of jumping genes causes chromosomal mayhem in germ cells. Our results, coupled with work by Toshie Kai, a former Carnegie researcher studying the role of nuage in egg development in the fruit fly, suggest that nuage plays a central role in transposon silencing during the development of egg and sperm of many species from insects to mammals. "

The last surprise for the scientists was the observation that, contrary to the current view in the field, the silencing of jumping genes does not occur one time only in male germ cells during the mouse fetal development. Instead, every time a germline stem cell divides by meiosis to make sperm in adults the jumping genes are activated only to be silenced soon thereafter.

"This was a very puzzling finding," commented Bortvin. "Since the jumping genes are not silenced just once during the development of the fetus, but every time new sperm are produced during a mouse life, it's possible that germ cells may employ transposons in some fundamental way in male germline meiosis. This research is the first such clue of that possibility. We will be very busy over the next few years trying to crack this and other puzzles of Maelstrom's role in controlling meiosis and sperm production."

Alex Bortvin | EurekAlert!
Further information:
http://www.ciwemb.edu
http://www.CIW.edu

More articles from Life Sciences:

nachricht Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View
22.06.2018 | University of Sussex

nachricht New cellular pathway helps explain how inflammation leads to artery disease
22.06.2018 | Cedars-Sinai Medical Center

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Superconducting vortices quantize ordinary metal

Russian researchers together with their French colleagues discovered that a genuine feature of superconductors -- quantum Abrikosov vortices of supercurrent -- can also exist in an ordinary nonsuperconducting metal put into contact with a superconductor. The observation of these vortices provides direct evidence of induced quantum coherence. The pioneering experimental observation was supported by a first-ever numerical model that describes the induced vortices in finer detail.

These fundamental results, published in the journal Nature Communications, enable a better understanding and description of the processes occurring at the...

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Rapid water formation in diffuse interstellar clouds

25.06.2018 | Physics and Astronomy

Using tree-fall patterns to calculate tornado wind speed

25.06.2018 | Earth Sciences

'Stealth' material hides hot objects from infrared eyes

25.06.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>