Monday, July 29, 2024
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I say that if modern dragonflies were as big as their ancestors, with around two-foot wingspans (see Week 5: Meganeura monyi), I would still try and befriend them. Unfortunately, this would probably be a bad idea. Dragonflies at their current size have a hunting success rate of 95%. Truthfully, I do not want to face the mandibles of a giant dragonfly. I can guarantee you I would not be able to outrun it.
Not only are dragonflies deadly to their prey, but they are also deadly to bacteria (although perhaps not intentionally). Researchers from Australia and Nigeria discovered that dragonfly wings have an inherent antibacterial property. They developed a new technique using powerful ion and electron microscopes to look at the nanostructures of dragonfly wings. Unlike previous microscopy techniques, this one does not risk burning biological materials.
They found over 10 billion tiny “fingers” lining the wing surface. These blunt nanopillars vary in height and may have maximum widths of a few hundred atoms. Separate studies investigating the material of these nanostructures suggest that they are made of fatty acids, rather than the assumed chitin.
When the scientists analyzed the efficiency of these wings in killing E. coli, they found that the nanopillars’ bacterial killing mechanism was not like poking something with a massive bed of nails as we had assumed. Bacteria don’t die the second they touch the wings. Their membranes don’t touch the nanostructures at all. Bacteria on the wings secrete a molecular glue called extracellular polymeric substance (EPS). EPS plus the finger-like extensions of the E. coli stick them to the nanopillars. All this adhesive force deforms the bacterial membrane. When the E. coli starts to wiggle around and move, the shear force (the force parallel to its body) tears it apart. Its guts (well, cellular contents) leak out, and the bacteria deflates and dies. Then, the bacteria sink into the nanopillars. It is impaled. Truly dramatic. A kind of horror story, really.
Are there some questions about this study? Absolutely. First, this was done with E. coli, which has two membranes. Will the same effects happen with bacteria that have one membrane? Also, how much of an effect do the EPSs have? Will bacteria that produce less EPS still get ripped apart? Finally, does this mechanism still work if the nanopillars are at different heights? So much more investigation to do!
Now that we know so much more about dragonflies, I can talk about my week. Monday: blog writing, video editing, packing SOCK boxes. Tuesday: packing boxes, Niels Bohr library tour, editing demos. Wednesday: filming and editing vortices video, resume workshop (I need to edit my resume), unsuccessful journey for free books, successful journey home (highlights: fish market, June bug, Kai on an oversized chair). Thursday: intern appreciation lunch (Jessica says we can defeat imposter syndrome), more video editing, finished the SOCK additional materials, the Renwick and a beer garden (highlights: 1.8 Renwick, lawn chair go-kart, dinosaur vase).
Groundbreaking things occurred on Friday. We went to NASA Goddard! In list form (otherwise, this would be way too long), here are some of my highlights:
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The Hubble telescope texts its mom.
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Hubble star software that compared and matched star configurations was adapted to track and identify whale sharks and sea bass.
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NASA makes cosmic dust.
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Seeing the Hubble control room.
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Touching space rocks.
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Fantastic tardigrade poster.
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Pedro Pascal mass spectrometer.
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Getting to see the Nancy Grace Roman in construction!
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A slab of sandstone containing dinosaur tracks was found during construction of a building.
A great Friday rolled into a great weekend. Sonja and I had brunch and saw The Rover at the Shakespeare Theatre Company Academy with Collins and Reidyn. It was not at all what I was expecting, and also hilarious. We had some tea and walked home, and then Kai and I made dumplings for dinner. Sunday morning, Sonja and I walked to Georgetown and got delicious pastries from Yellow (Harissa egg croissant? Fantastic.), observed some rats, and walked around. We then rushed back to Shenkman for the 4 pm Intern Olympics. I am proud to say that my team came in First Place (oh yeah!). I kicked the ball (and accidentally hit Collins in the face) in soccer but did not come first at hallway hurdles (proof of why I could not outrun a giant dragonfly). Kaden, Brynn and my nation slayed.
This week’s dragonfly is the Fiery Skimmer, Orthetrum villosovittatum, the dragonfly the authors used in the bacteria study (Bactericidal Effects of Natural Nanotopography of Dragonfly Wing on Escherichia coli from Bandara et al.). It is found in some parts of Indonesia, New Guinea, and Australia in boggy seepages, streams and swamps. As you might assume from its name, the male dragonflies are bright, fiery red. The females are ochre-coloured. Fantastic dragonfly.
Maia Chandler