MSGID: 1:317/3 64226d74   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Human cells help researchers understand squid camouflage    
      
     Date:   
         March 27, 2023   
     Source:   
         American Chemical Society   
     Summary:   
         Squids and octopuses are masters of camouflage. But some aspects   
         of how they become reversibly transparent are still 'unclear,'   
         because researchers can't culture cephalopod skin cells in the   
         lab. Now, researchers have replicated the tunable transparency of   
         squid skin in mammalian cells, which are more easily cultured.   
      
      
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   FULL STORY   
   ==========================================================================   
   Squids and octopuses are masters of camouflage, blending into their   
   environment to evade predators or surprise prey. Some aspects of how   
   these cephalopods become reversibly transparent are still "unclear,"   
   largely because researchers can't culture cephalopod skin cells in   
   the lab. Today, however, researchers report that they have replicated   
   the tunable transparency of some squid skin cells in mammalian cells,   
   which can be cultured. The work could not only shed light on basic squid   
   biology, but also lead to better ways to image many cell types.   
      
      
   ==========================================================================   
   The researchers will present their results at the spring meeting of the   
   American Chemical Society (ACS).   
      
   For many years, Alon Gorodetsky, Ph.D., and his research group have been   
   working on materials inspired by squid. In past work, they developed   
   "invisibility stickers," which consisted of bacterially produced squid   
   reflectin proteins that were adhered onto sticky tape. "So then, we had   
   this crazy idea to see whether we could capture some aspect of the ability   
   of squid skin tissues to change transparency within human cell cultures,"   
   says Gorodetsky, who is the principal investigator on the project.   
      
   The team at the University of California, Irvine focused their efforts   
   on cephalopod cells called leucophores, which have particulate-like   
   nanostructures composed of reflectin proteins that scatter   
   light. Typically, reflectins clump together and form the nanoparticles, so   
   light isn't absorbed or directly transmitted; instead, the light scatters   
   or bounces off of them, making the leucophores appear bright white.   
      
   "We wanted to engineer mammalian cells to stably, instead of   
   temporarily, form reflectin nanostructures for which we could better   
   control the scattering of light," says Gorodetsky. That's because if   
   cells allow light through with little scattering, they'll seem more   
   transparent. Alternatively, by scattering a lot more light, cells will   
   become opaque and more apparent. "Then, at a cellular level, or even   
   the culture level, we thought that we could predictably alter the cells'   
   transparency relative to the surroundings or background," he says.   
      
   To change how light interacts with cultured cells, Georgii Bogdanov,   
   a graduate student in Gorodetsky's lab who is presenting the results,   
   introduced squid- derived genes that encoded for reflectin into human   
   cells, which then used the DNA to produce the protein. "A key advance in   
   our experiments was getting the cells to stably produce reflectin and form   
   light-scattering nanostructures with relatively high refractive indices,   
   which also allowed us to better image the cells in three dimensions,"   
   says Bogdanov.   
      
   In experiments, the team added salt to the cells' culture media and   
   observed the reflectin proteins clumping together into nanostructures. By   
   systematically increasing the salt concentration, Bogdanov got   
   detailed, time-lapse 3D images of the nanostructures' properties. As   
   the nanoparticles became larger, the amount of light that bounced off   
   the cells increased, consequently tuning their opacity.   
      
   Then, the COVID-19 pandemic hit, leaving the researchers to wonder what   
   they could do to advance their investigation without being physically   
   in the lab.   
      
   So, Bogdanov spent his time at home developing computational models   
   that could predict a cell's expected light scattering and transparency   
   before an experiment was even run. "It's a beautiful loop between theory   
   and experiments, where you feed in design parameters for the reflectin   
   nanostructures, get out specific predicted optical properties and then   
   engineer the cells more efficiently -- for whatever light-scattering   
   properties you might be interested in," explains Gorodetsky.   
      
   On a basic level, Gorodetsky suggests that these results will help   
   scientists better understand squid skin cells, which haven't been   
   successfully cultured in a laboratory setting. For example, previous   
   researchers postulated that reflectin nanoparticles disassemble and   
   reassemble to change the transparency of tunable squid leucophores. And   
   now Gorodetsky's team has shown that similar rearrangements occurred   
   in their stable engineered mammalian cells with simple changes in salt   
   concentration, a mechanism that appears analogous to what has been   
   observed in the tunable squid cells.   
      
   The researchers are now optimizing their technique to design better   
   cellular imaging strategies based on the cells' intrinsic optical   
   properties. Gorodetsky envisions that the reflectin proteins could   
   act as genetically encoded tags that would not bleach inside human   
   cells. "Reflectin as a molecular probe provides a lot of possibilities   
   to track structures in cells with advanced microscopy techniques," adds   
   Bogdanov. For example, the scientists propose that imaging approaches   
   based on their work could also have implications for better understanding   
   cell growth and development.   
      
   The researchers acknowledge funding from the Defense Advanced Research   
   Projects Agency and the U.S. Air Force Office of Scientific Research.   
      
       * RELATED_TOPICS   
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                   # Biology # Biotechnology # Molecular_Biology #   
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                   # Environmental_Awareness # Environmental_Issues #   
                   Sustainability # Environmental_Policy   
       * RELATED_TERMS   
             o Somatic_cell o Stem_cell o Octopus o Epithelium o   
             Intelligence_of_squid_and_octopuses o Itch o Giant_squid   
             o Camouflage   
      
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   Story Source: Materials provided by American_Chemical_Society. Note:   
   Content may be edited for style and length.   
      
      
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/03/230327114905.htm   
      
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