Dayton's Glog on Cephalopods

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by daytonshaw
Last updated 4 years ago


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Dayton's Glog on Cephalopods

To determine what chemical compounds were responsible for rapid, adaptive colour change, scientists used analytical chemistry to identify what the main components inside chromatophores were. This was done using microcapillary, reverse-phase high pressure liquid chromatography (RP-HPLC) combined with tandem mass spectrometry (MS/MS). First, the chromatophores were extracted from adult cuttlefish. The chromatophore cells were broken open to release their contents which were then purified to separate all of the different chemical compounds. They were then analyzed by RP-HPLC-MS/MS!RP-HPLC is where the inside of the stationary phase (microcapillary) is non-polar and the mobile phase (solvent) is polar. This means the more polar the molecules are in the chromatophore, the less they'll 'stick' inside stationary phase and the faster they will travel through the capillary/HPLC. Other non-polar molecules in the chromatophore will tend to 'stick' with the stationary phase more often and take longer to travel through the HPLC. The end result of HPLC is the separation of all the different proteins from one another, contained within the chromatophore based on their polarity. Now to determine what they are!Tandem mass spectrometry (MS/MS) is a technique used to quantify and identify molecules by separating them further by ionization (give them a charge), sorting the ions, fragmenting the ions, sorting them again and finally detecting them. The molecules are ionized by an ion-source and then separated by their mass to charge ratio (m/z). If a molecule has a molecular mass of 400 g/mol and a charge of 1, it will have a m/z of 400, while if another molecule has a mass of 400 g/mol but a charge of 2 after being ionized, the m/z will be 200. The first mass spectrometer will ionize and separate molecules in increasing m/z. The selected ions are fragmented by a dissociation source and the second MS will separate the new ions again by their new m/z ratio. The ions are finally detected by the second MS and develops a spectrum. Each molecule has a unique fragmentation pattern that generates their own unique mass spectrum! We use these mass spectra to identify and quantify the proteins present in the chromatophore! In this experiment, the spectra were compared to a protein spectra database to determine what was present.

Using reverse-phase HPLC combined with tandem mass spectrometry, it was determined that the proteins reflectin and crystallin were the dominant/most abundant structural proteins present in chromatophores.Reflectin is a protein with a high refractive index (bend and separate different wavelengths of light significantly) while crystallin is hypothesized to focus any light into the chromatophore. Cephalopods have 3 layers of chromatophores that absorb light in a wide range of wavelengths in such a thin skin layer. This ability is made possible due to the presence of reflectin and its high index of refraction. Light can interact with one or all of the layers depending on which layer(s) are exposed by the cephalopod. As a result, cephalopods are able to exhibit many different colours on demand simply by contracting their skin and concentrating its chromatophores to give darker colours or relaxing to give lighter colours. Thanks to Analytical Chemistry, we can use this new information to enhance optic technologies whether its cameras, video displays, fiber optics or anything else! It could even lead the way to potential enhancements in military camouflage.

Click the black title to access the news article!!!

Being able to blend into your surroundings can be a big advantage for both predator and prey in the animal kingdom. Seasonal camouflage is amazing, but adaptive camouflage takes 'blending in' to a whole new level. Very few creatures are capable of rapidly changing their skin colour on the spot and none do it better than Cephalopods (Cuttlefish, squid, octupus)!Adaptive camouflage is an amazing feature developed by Mother Nature and personally, one that I find to be pretty cool, which is why I chose this news article! Cuttlefish, for example, can use this ability for warnings, camouflage, and even to hypnotize their prey ( Check the gif below!). But have you ever wondered why cephalopods can change their skin so drastically? We know that their skin contains specialized cells called 'chromatophores' that change colour when they contract or expand. But what exactly inside those structures allows the colour/pattern to change so immensely and so quickly? That's where analytical chemistry comes to the rescue...


Analytical Chemistry Rocks!


Great intro to how chromatophores work and shows adaptive camouflage in action! Watch until the flamboyant cuttlefish changes colour! (~1min 30secs)

Check this out!

Analytical Question: What are the structural chemical compounds in chromatophores that allow cephalopods like cuttlefish to rapidly change colour?

The Power of Analytical Chemistry: Chemists Dissect Cephalopod Camouflage




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