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Catsharks have an eye for fluorescence and they use it to perceive their kin

           

By Madhuvanthi Kannan

Scientists including Dr. Vincent Pieribone have shown that catsharks – spotty, reticent fishes of deep ocean waters – have extraordinary vision that helps them distinguish their mates from other species. The research performed in collaboration with the City University of New York and the American Museum of Natural History, among others, has just been published in Nature’s Scientific Reports.

At depths of 300 to 500 meters in the ocean, where catsharks thrive, only blue light from the sun makes its way through. All other colors of the spectrum are dispersed away by the immense volume of the ocean. When blue light strikes their bodies, the molecules on the shark skin absorb it, and in return, emit light of lower energy, lending a green hue to their facade. This biophysical phenomenon is what we call bio-fluorescence.

The team of scientists, who are in fact expert divers, unveiled in 2014 for the first time that marine fishes inhabiting the ocean waters of the Caribbean and the Western Pacific exhibit fluorescence. The finding came in as a surprise since, until then, fluorescence had only been observed in the aquatic inmates of shallower reefs. The recent study is a follow-up of the 2014 report. Here, the scientists probe deeper into whether and how catsharks perceive the fluorescence on their peers.

To do this, they isolated the pigment in the shark’s eyes and examined its light-absorbing properties. Just as the human eye is equipped with pigments that can detect the red, green and blue colors of the spectrum, the shark eye is also fitted but with pigments that can only perceive blue and green. For the sharks, this comes in handy because their skin is composed of complementary pigments that emit the exact same colors when blue light from the sun bounces off of their bodies. This means that, in the secret world of the deep, the sharks cloak themselves in an outfit only perceivable to their own kin. Even the human eye is insensitive to the fluorescence. Divers need blue illumination from an external light source and yellow barrier filters to be able to see the shark’s greenish hue.

What’s more, the team also established that catshark fluorescence elevates the contrast at the patches on their skin so much that they “stand out like a sore thumb” among themselves. The dark patches are areas of intense blue fluorescence while the paler tone on the rest of the body glows green in front of their eyes.

The other authors in the study are David Gruber, Ellis Loew, Dimitri Deheyn, Derya Akkaynak, Jean Gaffney, Leo Smith, Matthew DAVIS, Jennifer Stern and John Sparks.

Contact information: Dr. Vincent Pieribone, The John B. Pierce Laboratory, New Haven, CT.  E-mail: vpieribo@jbpierce.org.

Mary Burke selected to receive two awards

Congratulations to Mary Burke, Yale graduate student in the lab of Dr. Dana Small, who has been selected to receive the Annie Le Fellowship Award of 2016, and as part of the Yale Neuroscience Outreach Program, the Seton Elm-Ivy Award.

Ms. Burke will be recognized as the Annie Le Fellow for a single year beginning on September 1st.  To honor the memory of Annie Marie Le, a Yale graduate student between 2007 and 2009, Yale University established the Annie Le Fellowship Fund to benefit Ph.D. students in the Combined Program in the Biological and Biomedical sciences.  Each year one or more BBS students are selected for this monetary Fellowship.  Mary will be recognized for her exceptional academic achievements and service to Yale and the community by the Dean of the Graduate School at the annual Convocation ceremony in May.

Ms. Burke is part of the Yale Neuroscience Outreach Program which has been selected to receive a Seton Elm-Ivy Award.  Each year, outstanding efforts to sustain and expand the partnership between Yale University and the City of New Haven are recognized through the Seton Elm-Ivy Awards which were started in 1979 through the inspiration and support of Fenmore (Class of ’38) and Phyllis Seton, who established an endowment at the Community Foundation for Greater New Haven to support the awards ceremony.  Elm Awards are given to members of the New Haven community and Ivy Awards are given to Yale staff, faculty, and students.  The Seton Elm-Ivy Awards will be presented this year by President Peter Salovey and Mayor Toni Harp at a special luncheon on April 5th at the Presidents’ Room at Woolsey Hall.

Animals, from flies to humans, use olfaction to find resources, such as food and mates. How do such different creatures, with such different brains, all share this ability?

Dr. Justus Verhagen, an Associate Fellow at The John B. Pierce Laboratory, along with a multi-disciplinary team of researchers from the University of Colorado Boulder, University of California-Berkeley, Weill Cornell Medical College, the University of Pittsburgh, and New York University Medical Center are working to uncover the algorithmic and mechanistic processes governing this deeply embedded behavior.

This project is one of three funded by a $15M National Science Foundation initiative to unravel the mysteries of olfaction. The awards expand the NSF’s investments in the president’s BRAIN Initiative, and are funded by NSF’s Directorates for Biological Sciences and Mathematical and Physical Sciences.

Find out more: odornavigation.org