Monday, 14 October 2019

CRISPRed fruit flies mimic monarch butterfly, and could make you vomit

Scientists recreate in flies the mutations that let monarch butterfly eat toxic milkweed with impunity

Date:October 2, 2019
Source:University of California - Berkeley

The fruit flies in Noah Whiteman's lab may be hazardous to your health.

Whiteman and his University of California, Berkeley, colleagues have turned perfectly palatable fruit flies -- palatable, at least, to frogs and birds -- into potentially poisonous prey that may cause anything that eats them to puke. In large enough quantities, the flies likely would make a human puke, too, much like the emetic effect of ipecac syrup.

That's because the team genetically engineered the flies, using CRISPR-Cas9 gene editing, to be able to eat milkweed without dying and to sequester its toxins, just as America's most beloved butterfly, the monarch, does to deter predators.

This is the first time anyone has recreated in a multicellular organism a set of evolutionary mutations leading to a totally new adaptation to the environment -- in this case, a new diet and new way of deterring predators.

Koala epidemic provides lesson in how DNA protects itself from viruses

Date: October 10, 2019
Source: Cell Press



In animals, infections are fought by the immune system. Studies on an unusual virus infecting wild koalas, by a team of researchers from the University of Massachusetts Medical School and the University of Queensland, reveal a new form of "genome immunity." The study appears October 10 in the journal Cell.

earRetroviruses, including pathogens like HIV, incorporate into the chromosomes of host cells as part of their infectious lifecycle. Retroviruses don't usually infect the germ cells that produce sperm and eggs and are therefore usually not passed from generation to generation, but this has happened several times during evolution. Out of the entire 3 billion nucleotides of the human genome, only 1.5% of the sequence forms the 20,000 genes that code for proteins -- and 8% of the human genome comes from fragments of viruses. These pathogen invasions of the genome have sometimes been beneficial. For example, a gene "co-opted" from a virus is required for formation of the placenta in all mammals, including humans.

Pictish carved beasts 'unlike anything found before'

A 1,200-year-old standing stone discovered in the Highlands has carvings never before seen on a Pictish stone, archaeologists have said.

The stone was found lying in the ground and covered by vegetation at an early Christian church site near Dingwall.

Archaeologists have now revealed the side of the stone that was down in the earth and hidden from view was decorated with "two massive beasts".

Just over a metre of the original two metre-tall (6ft) stone survives.

The beasts were carved down the side of a cross.

John Borland, of Historic Environment Scotland and president of the Pictish Arts Society, said: "The two massive beasts that flank and surmount the cross are quite unlike anything found on any other Pictish stone.

"These two unique creatures serve to remind us that Pictish sculptors had a remarkable capacity for creativity and individuality.

Norfolk RSPCA centre saves 50th seal with injuries from rubbish


11 October 2019

A grey seal rescued on the North Sea coast has become the 50th to be treated by a wildlife centre for injuries caused by discarded man-made rubbish.

The animal, a male named Scylla, was found with an infected wound caused by a fishing net embedded around his neck.

The RSPCA centre in Norfolk said 2019 could be a record year for seal rescues "for all the wrong reasons".

"It's hard to describe how much pain and distress this can cause a seal," said manager Alison Charles.

"They are weighed down by this huge mass of netting, which must make it hard for them to swim, and then the net starts to cut and embed into their neck too.

"The injuries are horrendous, sometimes inches deep, and all the while the seal is becoming weaker and weaker and cannot feed so their suffering continues and they slowly starve to death.

"It is just horrific."

Sunday, 13 October 2019

Imprinting on mothers may drive new species formation in poison dart frogs- What do marrying one's parents, Oedipus complex have to do with evolution? - via Herp Digest

Date: October 3, 2019
Source: Smithsonian Tropical Research Institute

The old saying that people marry their parents may be true for poison dart frogs, and it may even lead to the formation of new species, according to a new study in Nature based on work at the Smithsonian Tropical Research Institute (STRI).

Strawberry poison dart frogs live on the mainland in Panama's Bocas del Toro province and have been isolated on islands in the archipelago that formed during the past 10 million years as sea level rose. Only a single color morph exists on some islands -- orange or green, for example, but on other islands several color morphs exist together, like blue and red frogs.

"In the past, people assumed that this group of brightly colored poison dart frogs were warning predators that their skin is toxic," said Corinne Richards-Zawacki, research associate at STRI and professor of biological sciences at the University of Pittsburgh. "But predators don't seem to care what color the frogs are, at least based on our earlier experiments. That's why we started asking whether the way they choose mates might lead to populations of different colors on different islands.”

The team set up three different situations: baby frogs raised with two parents of the same color (red baby, red parents), baby frogs raised with each parent a different color (red baby, one red and one blue parent) and baby frogs raised by foster parents of a different color (red baby, blue parents). In each case they asked which color the female offspring would choose as mates and which color the male offspring would perceive as a rival.

"We discovered that female frogs with parents of the same color tended to choose mates of that same color, whereas frogs with foster parents of a different color would choose mates the color of the foster parents," said Yusan Yang, who is completing her doctoral thesis at the University of Pitts-burgh. "The same was true for male-male aggression. This tells us that imprinting was more important than genetics when it comes to shaping these behaviors that are based on color.”

When baby frogs were raised with one parent of the same color and one parent of a different color, females chose mates the color of their mother, and males chose rivals the color of their mother, indicating that maternal imprinting was probably more important than paternal imprinting.
They also created a mathematical model showing that male aggression based on imprinting, in concert with female mate choice based on imprinting was enough to cause a scenario to evolve, where like mates with like, which could lead to two color morphs becoming separate species.

"We're fascinated by the idea that behavior can play such an important role in evolution," Richards-Zawacki said.

Story Source:
Materials provided by Smithsonian Tropical Research Institute. Note: Content may be edited for style and length.

Journal Reference:
  1. Yusan Yang, Maria R. Servedio, Corinne L. Richards-Zawacki. Imprinting sets the stage for speciation. Nature, 2019; 574 (7776): 99 DOI: 10.1038/s41586-019-1599-z

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Smithsonian Tropical Research Institute. "Imprinting on mothers may drive new species formation in poison dart frogs: What do marrying one's parents, Oedipus complex have to do with evolution?." ScienceDaily. ScienceDaily, 3 October 2019. 
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