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Secrets of the narwhal tusk

first_imgTo Martin Nweeia, the narwhal — a mysterious whale with an off-center tusk — is much more interesting than the mythical unicorn.Now, eight years after he described the narwhal’s distinctive tusk as a sensory organ, the fascinating creature is coming into focus. Nweeia and his colleagues have mapped a sensory pathway between that spiral tooth and the narwhal brain, along the way showing how the animal may use its tusk to suss out its environment.A practicing dentist in Connecticut and a clinical instructor in the Department of Restorative Dentistry and Biomaterials Sciences at the Harvard School of Dental Medicine (HSDM), Nweeia calls himself “just a curious kid” whose interest in dental anthropology — teeth in people across evolutionary history — spurred him to look at, for example, the elephant tusk and other variants of teeth in animals. But for more than a dozen years he has been chasing narwhals in their native habitat halfway between the Arctic Circle and the North Pole.The more Nweeia studied narwhals, the less sense they seemed to make.One spiral tooth projects through the upper lip, jutting nine feet out from only one side of the male’s head. It is a tooth, not an antler with the sex-based size differences well known in the animal kingdom.Another tooth remains embedded in the other side of the narwhal’s mouth, an asymmetry not found elsewhere in nature. Male narwhal embryos have eight pairs of teeth in their developing mouths, but only two pairs form after birth, with one pair forming the tusks. Usually only one of these teeth becomes the signature tusk.The world of narwhal research means expeditions to the northern tip of Baffin Island, where Nweeia perches on ice floes or at shore-based camps, dons a dry suit to wade in 36-degree water, braves 120-mph winds, and watches warily for polar bears. Early in his 14-year career of arduous expedition, Nweeia and colleagues discovered that the narwhal tusk is the structural inverse of a human tooth: It has a rigid rod in the center surrounded by a flexible outer layer that contains porous tubules.“These things all fly in the face of every rule and property that one would learn about teeth, if one were to go to dental school,” Nweeia said.In 2005 he and colleagues including Peter Hauschka, associate professor of developmental biology at HSDM and Harvard-affiliated Boston Children’s Hospital, reported at a conference that the narwhal tusk is a sensory organ, delivering information about its icy ocean environment. Now a paper, published in the journal Anatomical Record, traces the path from sensation to brain using anatomy, histology, genetics, and neurophysiology.Martin Nweeia (dark jacket) and his team used a Holter monitor to measure differences in the narwhal’s heart rate and found significant changes depending on water salinity. Photo by Isabelle GrocNweeia’s team found nerves, tissues, and genes in the narwhal tusk pulp that are known for sensory function and that help connect the tusk to the brain. Armed with this new model, Nweeia needed to confirm that sensory information is actually transmitted along this pathway to the brain from the tusk in living narwhals.The team tested this hypothesis by slipping a “tusk jacket” — a clear tube sealed with foam at either end — onto a narwhal that had swum into waters off Baffin, still chilly in August.The stimulus was water, either high or low in salt, which sloshed through the tube and over the tusk in separate tests. The response was a change in heart rate, measured by a Holter monitor, the same portable device that people wear when their doctors want to document heart rhythms. The team hooked electrodes onto the narwhals’ skin, took heart-rate measurements, and then released the animals unharmed after less than 30 minutes.The scientists measured changes in heart rate and found significant changes depending on water salinity.Why would varying water salinity matter? Ice formation is critical to the success of an animal species that lives in an ever-changing ocean environment, the researchers surmised. Nweeia has concluded that the narwhal tusk senses variations in the salinity of the ocean waters as a possible way to demonstrate fitness to females. Such ability may help males find females in estrus, or help locate foods essential for newly born narwhals.Water salinity was the sensory stimulus, which triggered signals to the brain and then sparked responsive changes in heart rate, Nweeia explained.“This is the first tooth that has been shown by in vivo testing to have sensory function to a normal variable in its environment,” he said.Nweeia pointed out that human teeth are sensitive, too, but as in other mammals, this has been documented only after significant damage or disease. Human teeth can sense cold or heat or pain, especially when exposed after damage to the hard outer layer.Dental textbooks feature the hydrodynamic theory of tooth sensitivity, credited to Martin Brännström, which holds that changes in fluid inside tubules within the dentin layer cause variations in pressure that reach nerves in the tooth pulp. Brännström hypothesized that teeth are capable of detecting temperature, pressure, particle gradients, and tactile sensations.The next steps for Nweeia’s group, Narwhal Tusk Discoveries, are to complete a 12-year study collecting traditional Inuit knowledge of the narwhal and to find an evolutionary link to the tusk’s microstructure.“Imagine: Exploration, wonder, and mystery are all wound up in this magnificent spiraled tusk and sensory organ,” said Nweeia.This study was funded by National Science Foundation grants. Additional funding was made by the Harvard School of Dental Medicine, the Museum of Comparative Zoology at Harvard, the Smithsonian Institution, the Explorers Club, Castle Harlan, NSERC, Fisheries and Oceans Canada, and the Nunavut Wildlife Management Board.last_img read more

Five Traffickers Die in Clash with Police in Rio de Janeiro

first_imgBy Dialogo April 15, 2011 An operation by the Special Operations Battalion (BOPE) in two slums in northern Rio de Janeiro on 13 April left five dead, believed to be drug traffickers, a Military Police spokesperson informed AFP. The operation to suppress drug trafficking and weapons trafficking in the slums of Manguinhos and Mandela mobilized one hundred police officers, supported by two armored vehicles. Three pistols, two grenades, twenty-three motorcycles, and chemical substances for manufacturing drugs were confiscated, the police specified, and four arrests were made. Elsewhere, in western Rio, the Civil Police carried out an operation on 13 April to dismantle a police-style militia suspected of operating in thirteen slums. A city councilor was arrested, and fourteen arrest warrants were issued by the judicial authorities. The expansion of militias in Rio de Janeiro goes back to 2006, when groups of active or retired police officers invaded several favelas in the western part of the city, expelled drug traffickers, and started to collect “security fees” from inhabitants. Militias are present in 105 of the city’s 250 major slums, according to a report by Paulo Storani, a former captain of the elite Special Operations Unit (BOPE) of the Military Police. The authorities of Rio de Janeiro state, one of the country’s most violent, began a countercampaign in 2008 to pacify the city and eliminate militias and drug traffickers from the slums, ahead of hosting the World Cup in 2014 and the Olympics in 2016. At present, around twenty slums have been pacified.last_img read more

Manslaughter charges dropped for deadly bike crash suspect

first_img(WBNG) — A Broome County Grand Jury has dropped charges against Eric N. VanFossen of Endwell in the investigation into the death of a man who was riding his motorcycle recklessly in the town of Union on the night of Aug. 18. Initially, the sheriff’s office arrested 48-year-old John Hughes and charged him with manslaughter in the 2nd degree for extending a shovel onto to the road in an attempt to slow the motorcycle down. VanFossen was charged with manslaughter in the 2nd degree, a class C felony, by the Broome County Sheriff’s Office. “In this case, following an extensive investigation by the Broome County Sheriff’s Office and District Attorney’s Office, a Grand Jury reviewed several hours of witness testimony, along with other evidence and video surveillance.  The Grand Jury made the determination, based on their review of this case, the facts, although tragic, did not rise to the level necessary to move forward with criminal charges.”center_img In a statement, the Broome County District Attorney Michael A. Korchak said: VanFossen was arrested and charged later. His charges were dropped on Oct. 15.last_img read more

Central snaps Bucksport softball team’s winning streak at 23 games

first_imgBUCKSPORT — The Bucksport softball team saw its 23-game winning streak snapped Wednesday when it suffered a 3-1 defeat to the visiting Central Red Devils.Central scored the game’s opening run in the first inning before Bucksport scored one of its own to tie the game in the second. Yet the Red Devils added runs in the third and fourth innings and kept the Golden Bucks off the scoreboard the rest of the way en route to the victory.Kate Saunders took the loss for Bucksport despite striking out eight Central batters. Central’s Kaelyn Parks held the Golden Bucks to one hit as the Red Devils secured their first win of the season.The loss was Bucksport’s first since it fell to Madison 3-1 in the Class C championship game June 18, 2016. The team went 20-0 to claim the state title last season before defeating Mattanawcook Academy, Ellsworth and Dexter to begin the 2018 campaign.This is placeholder textThis is placeholder textlast_img read more

Carabao Cup: Man City lose to Man United but still make final

first_img Source: BBC Pep Guardiola says Manchester City need to “learn to be more clinical” after they made difficult work of reaching their third successive Carabao Cup final.Guardiola’s side will face Aston Villa at Wembley on 1 March – despite losing the second leg of their semi-final against Manchester United, advancing 3-2 on aggregate.Leading 3-1 from the first leg at Old Trafford, the holders pushed forward in search of a goal to put the tie to bed but could find no way past an inspired David de Gea.Instead, United put things back in the balance before half-time when Nemanja Matic put them ahead on the night with their first effort at goal.United had created nothing in open play but City could only half-clear Fred’s free-kick and Matic swept a powerful first-time strike past Claudio Bravo.“Over 180 minutes we were better than United,” said Guardiola. “We created chances to score a lot of goals and didn’t convert. We need to learn to be more clinical.“We played a side with incredible physicality. The goal was from a set-piece. The first time they shot on target. In both games, we were better.”City tried to respond after going behind – and De Gea, who had brilliantly denied Sergio Aguero and Riyad Mahrez in the opening minutes, was finally beaten when Raheem Sterling turned in Kevin de Bruyne’s cross, but the flag was already up for offside.The scoreline made for an anxious atmosphere at Etihad Stadium at the break and more United chances followed in the second half, with Harry Maguire heading over and Anthony Martial bringing a low save from Bravo but ultimately the visitors were unable to score a second.Sterling, still without a goal in 2020, had a chance to settle his side’s nerves and restore their two-goal cushion when he ran clear in the second half but he dallied and eventually skied his shot.More wastefulness from the home side followed, notably when the ball broke to substitute David Silva in front of goal but he chose to square to Ilkay Gundogan rather than shoot.It was only when Matic was sent off for his second booking with 14 minutes remaining that City regained any sort of control of the game, and they were able to see out the remainder without any further scares to ensure their progress.Guardiola’s side are into the final for a third successive year and will go for their seventh EFL Cup win when they face Villa in the final at Wembley on 1 March.Only Liverpool, who have won it eight times, have a better record in the competition.last_img read more