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Microbes don’t stand a chance against monotreme milk, and fluorescent beaks necessitate seabird shades

by Melissa Gilden
April 23, 2018 | APPEARED IN VOLUME 96, ISSUE 17

 

Got monotreme milk?

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Credit: Laura Romin/Larry Dalton
Bacteria battler: Platypus milk is loaded with an antibacterial protein.

Platypuses easily win the title of weirdest mammal. These crazy-looking critters have the ability to shoot deadly venom from their feet, and they lay eggs rather than give birth to live young. So it should come as no surprise to learn that their milk is unusual too and may present a new avenue for combating antibiotic resistance.

Australian scientist Janet Newman and colleagues at the Commonwealth Scientific & Industrial Research Organisation and Deakin University identified monotreme lactation protein (MLP), which is expressed only in monotreme milk, as having antibacterial activity against Staphylococcus aureus and Enterococcus faecalis—the respective causes of staph and urinary tract infections (Acta Crystallogr., Sect. F: Struct. Biol. Cryst. Commun. 2018, DOI: 10.1107/s2053230x17017708).

MLP has a novel, tightly coiled subunit of α helices in its structure, which the team refers to as the “Shirley Temple fold,” group leader Tom Peat tells Newscripts. Monotremes like the platypus don’t have nipples and instead express milk onto their bellies. The researchers hypothesize that the unique structure of MLP and its antibacterial qualities may have been evolutionarily required to protect baby platypuses from the bacteria-laden biome where they find their food. This contrasts significantly with the more familiar lactation strategy of placentals and marsupials, which may have developed to reduce the exposure of their young to microbial infection.

Will these findings indubitably solve the problem of antibiotic resistance? Not quite, “But every option we have and can explore is good, as bacteria that cause infection are becoming more and more resistant to the current compounds we have to fight them,” Peat says.

 

Seabird shades

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Credit: @JamieDunning/Twitter
Future so bright: A dead puffin models sunglasses made to protect its eyes from UV light.

Several oceans away, U.K. ornithologist Jamie Dunning was playing with ultraviolet light in the lab when he happened on a fluorescent finding. The University of Nottingham scientist wanted to see if a stray, deceased Atlantic puffin (Fratercula arctica) he had lying around had the same glow as its relative, the crested auklet (Aethia cristatella). “I’m the kind of guy that people send dead birds to,” Dunning recently told Newsweek.

Parts of the puffin’s beak lit up brightly. But what could be an evolutionary explanation for such luminosity?

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Bird vision, like that of humans, relies on rods and cones to see color. However, birds have tetrachromatic vision, meaning they see far more colors and, presumably, more glorious sunsets than humans, with our paltry trichromacy. So that fluorescence on puffins’ beaks must be some kind of communication or signal that only they can see, hypothesized Dunning. “They must be able to see it—that’s the only reason it would exist.”

So far, the glow has been observed only in dead puffins, so to safely make the same observation in live ones, he had sunglasses made for them. He recently shared an adorable photo of a deceased puffin donning the shades on Twitter, which ruffled a few feathers and inspired one commenter to request he use the phrase “I wear my sunglasses in flight” when the work is ultimately published.

Melissa Gilden wrote this week’s column. Please send comments and suggestions to newscripts@acs.org.

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