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 Antimicrobial substances identified in Komodo dragon blood
23.02.2017 | American Chemical Society

nachricht New Mechanisms of Gene Inactivation may prevent Aging and Cancer
23.02.2017 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>