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first_imgThe mitotic spindle, an apparatus that segregates chromosomes during cell division, may be more complex than the standard textbook picture suggests, according to researchers at the Harvard School of Engineering and Applied Sciences (SEAS).The findings, which result from quantitative measurements of the mitotic spindle, appear in the journal Cell.The researchers used a femtosecond laser to slice through the strands of the organelle and then performed a mathematical analysis to infer the microscopic structure of the spindle from its response to this damage.“We’ve been using this nanosurgery technique to understand the architecture and assembly of the spindle in a way that was never possible before,” says Eric Mazur, Balkanski Professor of Physics and Applied Physics at Harvard, who co-authored the study. “It’s very exciting.”The spindle, which is made of protein strands called microtubules, forms during cell division and segregates chromosomes into the daughter cells. It was previously unclear how microtubules are organized in the spindles of animal cells, and it was often assumed that the microtubules stretch along the length of the entire structure, pole to pole.Mazur and his colleagues demonstrated that the microtubules can begin to form throughout the spindle. They also vary in length, with the shortest ones close to the poles.“We wondered whether this size difference might result from a gradient of microtubule stabilization across the spindle, but it actually results from transport,” says lead author Jan Brugués, a postdoctoral fellow at SEAS. “The microtubules generally nucleate and grow from the center of the spindle, from which point they are transported towards the poles. They disassemble over the course of their life span, resulting in long, young microtubules close to the midline and older, short microtubules closer to the poles.”“This research provides concrete evidence for something that we’ve only been able to estimate until now,” Brugués adds.Mazur and Brugués worked with Daniel Needleman, assistant professor of applied physics and molecular and cellular biology at Harvard, and Valeria Nuzzo, a former postdoctoral fellow in Mazur’s lab at SEAS, to bring the tools of applied physics to bear on a biological question.The team used a femtosecond laser to make two small slices perpendicular to the plane of growth of the spindle apparatus in egg extracts of the frog species Xenopus laevis.They were then able to collect quantitative data on the reconstruction of the spindle following this disruption and precisely determine the length and polarity of individual microtubules. Observing the speed and extent of depolymerization (unraveling) of the spindle, the team worked backwards to compile a complete picture of the beginning and end points of each microtubule. Finally, additional experiments and a numerical model confirmed the role of transport.“The laser allowed us to make precise cuts and perform experiments that simply were not possible using previous techniques,” says Mazur.With further inquiries into spindle architecture, the researchers hope that scientists will one day have a complete understanding, and possibly even control over, the formation of the spindle.“Understanding the spindle means understanding cell division,” notes Brugués. “With a better understanding of how the spindle is supposed to operate, we have more hope of tackling the range of conditions — from cancer to birth defects — that result from disruptions to the cell cycle or from improper chromosomal segregation.”The research was supported by the National Science Foundation and by a fellowship from the Human Frontiers Science Program.For additional information, contact Caroline Perry at [email protected]last_img read more

first_imgFantasy football owners already received one major Week 14 injury shock when Odell Beckham Jr. (quad) was announced as “out” on Saturday despite not even being on the Giants final injury report. At this point, you can bet those in the fantasy playoffs will be double and triple checking the final active/inactive updates just to see if “questionable” WRs T.Y. Hilton, Danny Amendola, Doug Baldwin, and Keke Coutee are playing. We can be reasonably sure Sammy Watkins is out (see below), and both Julio Jones and Stefon Diggs didn’t wind up on their teams’ respective injury reports, so they should be good. Either way, fantasy start ’em, sit ’em decisions will not be easy.We’ll update this post with the latest news throughout the day, so check back frequently. For additional injury information on “questionable” QBs Matthew Stafford and Joe Flacco, check here; for more on dinged-up RBs, including Doug Martin and Isaiah, go here. Check out the Week 14 weather report by clicking here. You can also follow us on Twitter (@SN_Fantasy) for all the latest news and updates. Keke Coutee injury updateUPDATE: Coutee is officially OUT.Coutee (hamstring) was limited in practice this week, which is par for the course with him. He’ll once again be a game-time decision against the Colts.He had his big breakout against Indianapolis back in Week 4 (11-109), but given his currently limited play and Demaryius Thomas’s presence, Coutee isn’t a recommended starting option. If he’s out, Thomas would be a decent WR3 option. Week 14 Rankings:Quarterback | Running Back | Wide Receiver | Tight End | D/ST | KickerIs T.Y. Hilton playing Week 14?UPDATE 2: Hilton is officially ACTIVE.UPDATE: ESPN’s Adam Schefter reports Hilton will play today against Houston.After sitting out practice early in the week, Hilton (shoulder) returned to practice on Friday, and coach Frank Reich said he is “somewhat optimistic” Hilton will play against the Texans.Obviously, this will likely come down to a game-time call, but Hilton will remain a must-start if he’s active. When these teams met in Week 4, he had 115 yards on four receptions, and he remains a high-upside play every week. If he’s out, look for Dontrelle Inman and Chester Rogers to be the Colts top wide receivers, though it would be tough to start either given the matchup. Eric Ebron might get the biggest bump in value if Hilton is out.WEEK 14 PPR RANKINGS: Running back | Wide receiver | Tight endDanny Amendola injury updateUPDATE: Amendola is officially ACTIVE.Amendola (knee) got in limited practices all week and is “questionable” for Sunday’s game against the Patriots.It seems likely Amendola will play, and he might have some FLEX value in PPR leagues. His biggest fantasy impact might be his affect on DeVante Parker, who takes a notable hit in value if Amendola is active.​WEEK 14 DFS CASH LINEUPS: Yahoo | FanDuel | DraftKingsIs Doug Baldwin playing Monday night?Baldwin (hip) didn’t practice this week and is “questionable” for Monday night’s game against Minnesota. Baldwin played in Week 12 despite missing practice all week, so he’s very much a game-time decision. Nursing multiple injuries and facing a tough matchup, Baldwin is a risky WR3 if he plays. David Moore would get a bump in value if Baldwin is out, but Tyler Lockett is the only “must-start” Seahawks WR.MORE WEEK 14 DFS: Values | Stacks | Lineup BuilderWhen is Sammy Watkins playing again?Although officially listed as “doubtful” for Week 14, Watkins suffered a setback with his injured foot in practice this week and is expected to miss four-to-six weeks.At this point, he can be dropped in fantasy leagues. Chris Conley will start in Watkins’ absence and is worth a pickup given the Chiefs high-powered offense. He’s merely on the WR3 bubble against the Ravens, but he’s showed his upside by scoring three times in the past two games. The recently picked up Kelvin Benjamin, who’s not expected to play in Week 14, could also be in the mix and might be worth a flier if you have the roster space.WEEK 14 DFS GPP LINEUPS: Yahoo | FanDuel | DraftKingslast_img read more