Everybody knows the shortest distance between two points is a straight line, and now Harvard researchers have evidence that sperm have been taking the familiar axiom to heart.Though competition among individual sperm is usually thought to be intense, with each racing for the chance to fertilize the egg, Harvard scientists say that in some species, sperm form cooperative groups that allow them to take a straighter path to potential fertilization.A new study, conducted by Heidi Fisher, a postdoctoral student working in the lab of Hopi Hoekstra, the Alexander Agassiz Professor of Zoology in the Museum of Comparative Zoology, and postdoctoral student Luca Giomi, who works with L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, professor of organismic and evolutionary biology, and of physics, shows that in Peromyscus maniculatus, a species of deer mouse known to be promiscuous, sperm clump together to swim in a more linear fashion. The study is described in a July paper in Proceedings of the Royal Society B.“We generally think that each individual sperm cell swims its little heart out to get to the egg. But it had been discovered that, in at least a handful of organisms, sperm will cooperate and swim as a group,” said Hoekstra, who is also a professor of organismic and evolutionary biology.Exactly why sperm clump together, however, had remained a mystery — until now.“We had some hints that cooperation was enhancing their swimming performance, but what we didn’t understand was how it was helping,” Fisher said. “With this study, we combined a mathematical model with much finer-scale measurements that looked at groups that ranged from single sperm cells to groups of as many as 30 cells. What we realized was that that while their overall speed wasn’t increasing at all, that the time it took them to go from point A to point B was decreasing — they swim in a straighter line.”The study also found that sperm from promiscuous mice were likelier to form clumps of the optimum size, and that, when compared with sperm from Peromyscus polionotus — a closely related, but monogamous, species of mouse — the trait is likely driven by sexual selection.The new paper builds on a 2010 study conducted in Hoekstra’s lab, which found that sperm cells preferentially clump with those produced by the same male. Spurred by that earlier paper, Mahadevan approached Hoekstra with the idea of creating a mathematical model to understand whether and how sperm received an advantage by forming groups.“I read the paper and thought we could make a quantitative theory of the observations they had made,” he said. “But of course, the only way to know whether any model was capable of anything predictive was to make it testable.“In this context … the question was: Is it possible to make the aggregate do better than the individual?” he continued. “One way to do that is to get all the tails to synchronize, but that doesn’t happen. The other way is to cancel out the random motion of the individuals in an aggregate because the sperm adhere to each other. Eventually, for large aggregates, the sperm point toward each other and thus cannot swim at all. This mechanism, when quantified in a model that Luca and I developed, led to testable predictions. When Heidi did the experiment, we found that this was essentially correct.”In addition to finding that sperm that band together swim in a more linear fashion, researchers identified the clump size at which sperm reaped the largest reward for grouping. Groups with too few cells, Hoekstra said, continued to swim along more meandering paths, while sperm in over-large groups often ended up swimming against each other.“What we found is that both species have an optimum at around eight, which was what the model predicted, but there were fewer groups that were too big or too small in the promiscuous species,” she said. “That is consistent with the idea that sexual selection is driving this trait in the promiscuous species, whereas in the monogamous species, where there’s not as much competitive pressure, things are a bit more relaxed, so we see more variance in the clump sizes.”In the end, Mahadevan said, the study represented an ideal collaboration between the theoretical and the empirical.“If you talk to evolutionary biologists, their approaches are often genetic, because they’re trying to understand what the genetic bases are for natural selection pressures,” he said. “From a theoretical point of view, the focus is on reproductive capacity. What’s interesting in this particular situation is we can take a question of reproductive capacity and add a physiological twist to it that’s associated with sperm motility, and then we can take that apart in the context of what happens when you change the shape of the sperm, or their ability to adhere to each other, or their ability to move.“In my view we haven’t so much answered the question as we’ve sharpened it,” he continued. “And we’ve done by that couching a conceptual notion of competition and cooperation in terms of physical and physiological variables that can be measured and lead to testable predictions.”
Bioenergy scientists, policymakers, industry leaders and enthusiasts met in Tifton, Ga., Aug. 3-5 to discuss how Georgia and surrounding states could soon establish and grow a vibrant renewable energy market to help the world find alternative ways to power itself.High gas prices spur forward thinkingThe three-day 2010 Southeast Bioenergy Conference was held at the University of Georgia Tifton Campus Conference Center. Keynote speaker Christopher Steiner told more than 500 participants that costly gas isn’t necessarily a bad thing. It could be the catalyst to spark a sincere, long-term U.S. energy strategy to break its addiction to foreign oil.Right now, there are 1 billion people living “America-style” lives, or lives demanding high energy needs, he said. By 2040, that number will be 3 billion. “That’s three times as many people demanding the kind of energy, the kind of stuff, the kind of lives we have and standing with us at the world’s energy spigot,” said Steiner, a Forbes staff writer and author of the recently published “$20 per gallon.”$6 per gallon gasoline?Higher gas prices will hopefully come gradually, he said, to allow U.S. gas consumers to adapt or change transportation habits. Several years ago when prices hit $2 per gallon, not much changed; and $3-per-gallon gas a few years later did little to change consumption. But in 2008, when prices topped $4 per gallon, things changed. That year, Americans drove 100 billion fewer miles than in 2007. “It’s very clear to me that the changes gas price bring to us is as much a study in sociology as they are in economics,” said Steiner, who predicts gas prices could reach $6 per gallon in the next five years.Some oil used by Americans comes from anti-American countries The U.S. uses 25 percent of the world’s oil supply, importing 60 percent from unstable countries or ones that publicly speak against American policies or actions, said U.S. Rep. Jack Kingston (R-Ga.).“Our scramble for alternative fuels is as much a matter of national security as it is anything about economics or the environment,” he said. “And I believe that innovation, conservation and exploration, just like you do, have to be part of it.”Governor says Georgia prime spot for bioenergy cropsThe state’s “sun, soil and water” provide for fertile grounds for mass bioenergy production, Gov. Sonny Perdue said during the conference luncheon. He added that major energy companies in the U.S. and around the world are now looking to do potential business in the state.“The good news is we’re in a good spot. We have everything it takes: natural resources, intellectual capital and an entrepreneurial spirit,” he said. “…We have watched the birthing and nurturing and potty training of a whole new industry in Georgia.”Lectures and breakout sessions at the conference included “Your Next Job Could be in Clean Energy Technology,” “Wood Pellets – The Southeast’s Hottest Export,” “Promising Energy Crops for the Southeast,” “New Developments in Bioenergy Products & Processes” and “Ag Energy in Action – Success Stories from the Southeast.”More information on the conference can be found at www.sebioenergy.org.
Facebook0Tweet0Pin0 Photo Courtesy of Jim MarshallAfter a week off Grays Harbor Raceway will get back to racing this Saturday September 14th. The night will feature a full lineup of all five of GHR’s staple classes. Those classes include the 360 Sprints, Shipwreck Beads IMCA Modifieds, USAC Ford Focus Midgets, Cut Rate Auto Parts Street Stocks, and Hornets.Tickets for Saturday will be Adults $13.00, Senior (62+)/Juniors (13-18)/Military $10.00, Youths (6-12) $5.00, Youths (5 and Under) FREE, Family Pass (Two Adults and Up To Four Youths) $30.00, and Premium Seating $20.00. Pit gates open at 2:30, front gates, 4:30, and racing starting around 6:30.It seems like it has been quite some time since the 360 Sprint were last in action. After five events completed Reece Goetz continues to sit atop the winner’s list with two feature victories. Currently he is the only driver to have won more than once while Henry Van Dam, J.J. Hickle, and Evan Margeson have a single triumph apiece.In Shipwreck Beads IMCA Modified action there is a three way tie for most victories. Joe German, Craig Moore, and Zack Simpson each have won twice this year at Grays Harbor Raceway. Joining them on the win chart for 2013 is Scott Miller, Jeff Foster, Alan Muenchow, Josh Muller, Jeremy Shank, and Jesse Williamson who have all won once.Chase Goetz continues to dominate the USAC Ford Focus Midget ranks as he seeks his first career GHR championship. Goetz has visited victory lane a total of seven times while Jared Peterson has won twice and is the only driver to have beaten Goetz so far this year.You could also say the Cut Rate Auto Parts Street Stocks is a realm of pure domination as well. Jason Tole has won eight times this year including the Cut Rate Auto Parts Iron Man 100. Cory Sweatman, Austin Kerrigan, and Jack Parshall are the only other drivers to have beat Tole and each of them has done so on one occasion. A tight point battle is underway with not many races left. Cory Sweatman has a narrow three point lead over Jason Tole headed into Saturday night.Last but not least the Hornets are putting on a good championship battle. Defending champ Chad Norton has a slim five point advantage over Willie Wright coming into this weekend. Chad North and Jeff Daniel have each won three main events while Brian Norton has two triumphs to his credit. Willie Wright is the only driver to have won in the division once in 2013.The Grays Harbor Raceway is known for its high speeds and side by side racing as well as its large track size. Hosting racing action from April to October regular classes include 360 Sprints, IMCA Modifieds, USAC Ford Focus Midgets, Street Stocks, Hornets, and for the first time the Northwest Extreme Winged Sprint Car Series. Special events include visits by the World of Outlaw Sprint Car Series and American Sprint Car Series-Northwest Region. You can keep up on all the latest activity at www.graysharborraceway.com for the most-recent news and stories.Additional InformationTrack: Grays Harbor RacewayLocation: 32 Elma McCleary Road, Elma, WA, 98541Track Contact: (360)-699-RACEWebsite: www.graysharborraceway.comSponsors: Budweiser, Bully Dog Performance, Cut Rate Auto Parts, Harbor Pacific Distributing, Hoosier Racing Tires, Lucky Eagle Casino and Hotel, The Contingency Connection, Lucas Oil Products, Our Community Credit Union, Pepsi, Shipwreck Beads, Whitney’s Auto Group, Elma Chamber of Commerce, Quinault Beach Resort and Casino, Grays Harbor County Fairgrounds, Adamas Reality, Olympic Eagle Distributing, Midnight Cruisers Rod Fest, PNE Corporation, Push Rods, Q-Mart, Midnight Cruisers, Fosses Hot Rods & Cool Cars, Harrington Financial, I-5 Quarter ¼ Midget Club, Jacknut Apparel, 104.7 KDUX FM, KIX 95.3 FM, RockAuto.com By Ben Deatherage for Grays Harbor Raceway