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Index of Subjects --_000_F85658DFB93C409685F40516E0E73B6Fdalca_ Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Very interesting, but some of the article could be a tad misleading. It is not clearly explained, but the writer seems to think that the strikin= g custom yellow sunglasses are somehow a clever part of helping the researc= her test for fluorescence in the bills of live puffins. Unclear, but they= are presumably being employed instead to stop the strong UV light used to = illuminate the bill from also entering and damaging the eyes. UV photons a= re intrinsically high energy and will break bonds in DNA (think skin cancer= s), so it is important to shield the retina. Straw-colored or yellow =91l= ong-pass=92 filters are routinely used for this as they filter out nearly a= ll UV but pass visible wavelengths, though a blindfold would work even bett= er for retinal shielding. It does seems likely that the fluorescent stripes on the bill may be at lea= st a helpful supplemental visual signal for other puffins, but the evidence= is insufficient to make sure. There is some near-UV in =91blue=92 skyligh= t, but it is never the dominant wavelength range (the peak lies in the blue= range not UV in skylight), and fluorescence is seldom quantum-efficient fo= r natural compounds =97 it takes many UV photons incident to cause one long= er-wavelength photon to be emitted (fluorescence), what you are looking at,= white-ish in one photo shown. So the amount of fluorescence could be quite= weak relative to the natural reflection from the other pigments in the bil= l, especially in sunlight which has a lower proportion of UV. Many insect= s and some birds are known to have UV-sensitive photoreceptors, maybe puffi= ns have these too but I think has not been established for them. But signa= ling is not the only possible explanation for natural UV-induced fluorescen= ce ... =85 some molecules with other functions fluoresce in UV but this is not par= t of being a visual signal offered to others. The natural rubber compound = resilin present in the legs of insects helps power their impressive jumps. = It contains tyrosine residues that cross-couple many resilin molecules tog= ether into an amorphous springy mass than can absorb then release mechanica= l energy. These residues cause it to fluoresce strongly in the blue range = when illuminated in UV, a byproduct of the function, helpfully diagnostic, = but not used in signaling. The exoskeleton of some (all?) scorpions fluore= sces in UV courtesy of a different molecule, which is how scorpion collecto= rs find them (at night using a =91blacklight=92 =3D UV flashlight), but I d= on=92t think it is established to be a visual signal there. The wings of = some butterflies contain pterins that fluoresce and perhaps may give a usef= ul visual signal, but alternatively these could just be toxic compounds dum= ped into the mostly inert wings to get rid of them out of the body (not sur= e I buy this but someone once suggested it). Steve (Hfx) -------------------------------------------------- On Apr 6, 2018, at 12:16 PM, Keith Lowe <mythos25@live.com<mailto:mythos25@= live.com>> wrote: http://www.cbc.ca/news/canada/newfoundland-labrador/puffin-beaks-flouresce-= 1.4607386 Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=3D550986> for Window= s 10 --_000_F85658DFB93C409685F40516E0E73B6Fdalca_ Content-Type: text/html; charset="Windows-1252" Content-ID: <E69D99C076FB7B4999F03FB1716BA94E@CANPRD01.PROD.OUTLOOK.COM> Content-Transfer-Encoding: quoted-printable <html> <head> <meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3DWindows-1= 252"> </head> <body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-lin= e-break: after-white-space;"> Very interesting, but some of the article could be a tad misleading. <div><br> </div> <div>It is not clearly explained, but the writer seems to think that the st= riking custom yellow sunglasses are somehow a clever part of helping the re= searcher test for fluorescence in the bills of live puffins. Unclear= , but they are presumably being employed instead to stop the strong UV light used to illuminate the bill from also = entering and damaging the eyes. UV photons are intrinsically high ene= rgy and will break bonds in DNA (think skin cancers), so it is important to= shield the retina. Straw-colored or yellow =91long-pass=92 filters are routinely used for this as they filter = out nearly all UV but pass visible wavelengths, though a blindfold would wo= rk even better for retinal shielding. </div> <div> <div>It does seems likely that the fluorescent stripes on the bill may be a= t least a helpful supplemental visual signal for other puffins, but the evi= dence is insufficient to make sure. There is some near-UV in =91blue= =92 skylight, but it is never the dominant wavelength range (the peak lies in the blue range not UV in skylight), and= fluorescence is seldom quantum-efficient for natural compounds =97 it take= s many UV photons incident to cause one longer-wavelength photon to be emit= ted (fluorescence), what you are looking at, white-ish in one photo shown. So the amount of fluorescence could be q= uite weak relative to the natural reflection from the other pigments in the= bill, especially in sunlight which has a lower proportion of UV. Ma= ny insects and some birds are known to have UV-sensitive photoreceptors, maybe puffins have these too but I think= has not been established for them. But signaling is not the only pos= sible explanation for natural UV-induced fluorescence ...</div> <div><br> </div> <div>=85 some molecules with other functions fluoresce in UV but this is no= t part of being a visual signal offered to others. The natural rubber= compound resilin present in the legs of insects helps power their impressi= ve jumps. It contains tyrosine residues that cross-couple many resilin molecules together into an amorphous spring= y mass than can absorb then release mechanical energy. These residues= cause it to fluoresce strongly in the blue range when illuminated in UV, a= byproduct of the function, helpfully diagnostic, but not used in signaling. The exoskeleton of some (all?= ) scorpions fluoresces in UV courtesy of a different molecule, which is how= scorpion collectors find them (at night using a =91blacklight=92 =3D UV fl= ashlight), but I don=92t think it is established to be a visual signal there. The wings of some butterflies contain = pterins that fluoresce and perhaps may give a useful visual signal, but alt= ernatively these could just be toxic compounds dumped into the mostly inert= wings to get rid of them out of the body (not sure I buy this but someone once suggested it).</div> <div><br> </div> <div>Steve (Hfx) <br> --------------------------------------------------<br> <div> <div>On Apr 6, 2018, at 12:16 PM, Keith Lowe <<a href=3D"mailto:mythos25= @live.com">mythos25@live.com</a>> wrote:</div> <br class=3D"Apple-interchange-newline"> <blockquote type=3D"cite"> <div lang=3D"EN-US" link=3D"blue" vlink=3D"#954F72" style=3D"font-family: H= elvetica; font-size: 12px; font-style: normal; font-variant: normal; font-w= eight: normal; letter-spacing: normal; line-height: normal; orphans: auto; = text-align: start; text-indent: 0px; text-transform: none; white-space: nor= mal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"> <div class=3D"WordSection1" style=3D"page: WordSection1;"> <div style=3D"margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calib= ri, sans-serif;"> <a href=3D"http://www.cbc.ca/news/canada/newfoundland-labrador/puffin-beaks= -flouresce-1.4607386" style=3D"color: rgb(149, 79, 114); text-decoration: u= nderline;">http://www.cbc.ca/news/canada/newfoundland-labrador/puffin-beaks= -flouresce-1.4607386</a></div> <div style=3D"margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calib= ri, sans-serif;"> <o:p> </o:p></div> <div style=3D"margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calib= ri, sans-serif;"> <o:p> </o:p></div> <div style=3D"margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calib= ri, sans-serif;"> Sent from<span class=3D"Apple-converted-space"> </span><a href=3D"http= s://go.microsoft.com/fwlink/?LinkId=3D550986" style=3D"color: rgb(149, 79, = 114); text-decoration: underline;">Mail</a><span class=3D"Apple-converted-s= pace"> </span>for Windows 10</div> </div> </div> </blockquote> </div> <br> </div> </div> </body> </html> --_000_F85658DFB93C409685F40516E0E73B6Fdalca_--
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Index of Subjects