Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study by Syracuse University scientists uncovers a reproduction conundrum

02.08.2012
For sperm, faster isn't always better
When it comes to sperm meeting eggs in sexual reproduction, conventional wisdom holds that the fastest swimming sperm are most likely to succeed in their quest to fertilize eggs. That wisdom was turned upside down in a new study of sperm competition in fruit flies (Drosophila melanogaster), which found that slower and/or longer sperm outcompete their faster rivals.

The study, recently published online in Current Biology and forthcoming in print on Sept. 25, was done by a team of scientists led by corresponding author Stefan Lüpold, a post-doctoral researcher in the Department of Biology in the College of Arts and Sciences. The team made the discovery using fruit flies that were genetically altered so that the heads of their sperm glow fluorescent green or red under the microscope. The fruit flies, developed by biology Professor John Belote, enable researchers to observe sperm in real time inside the female reproductive tract.

"Sperm competition is a fundamental biological process throughout the animal kingdom, yet we know very little about how ejaculate traits determine which males win contests," says Lüpold, a Swiss National Science Foundation Fellow working in the laboratory of biology Professor Scott Pitnick. "This is the first study that actually measures sperm quality under competitive conditions inside the female, allowing us to distinguish the traits that are important in each of the reproductive phases."

The research is also significant because the scientists studied naturally occurring variations in sperm traits, rather than manipulating the test populations for specific traits. After identifying and isolating groups of males with similar ejaculate traits that remained constant across multiple generations, the scientists mated single females with pairs of males from the different groups. "This approach allowed us to simultaneously investigate multiple ejaculate traits and also observe how sperm from one male change behavior depending upon that of rival sperm," Lüpold says.

Female fruit flies mate about every three days. Sperm from each mating swim through the female bursa into a storage area until eggs are released. Eggs travel from the ovaries into the bursa to await the sperm. However, sperm battles actually take place within the storage area. After each mating, new sperm try to toss sperm from previous matings out of storage. The female then ejects the displaced sperm from the reproductive system, eliminating the ejected sperm from the mating game. The researchers observed that longer and slower-moving sperm were better at displacing their rivals and were also less likely to be ejected from storage than their more agile counterparts.

"The finding that longer sperm were more successful is consistent with earlier studies," Lüpold says. "However, the finding that slower sperm also have an advantage is counterintuitive."

Why slower sperm have an advantage is still open to speculation. "It could be that, when swimming back and forth in storage, slower sperm hit the exit less frequently and are therefore less likely to be pushed out," Lüpold says. "Or, because sperm velocity is dependent on the density of sperm within the narrow storage area, it could be that velocity isn't really the target of sexual selection in fruit flies, but is rather a consequence of the amount of sperm packed into the storage organ."

The U.S. National Science Foundation (NSF) and the Swiss National Science Foundation funded the study.

Judy Holmes | EurekAlert!
Further information:
http://www.syr.edu

More articles from Life Sciences:

nachricht Transport of molecular motors into cilia
28.03.2017 | Aarhus University

nachricht Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside

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 Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Transport of molecular motors into cilia

28.03.2017 | Life Sciences

A novel hybrid UAV that may change the way people operate drones

28.03.2017 | Information Technology

NASA spacecraft investigate clues in radiation belts

28.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>