Injection of CRISPR solution into crustacean embryos Credit: Heather Bruce
It sounds like “just a hundred stories” – “how the insect got its wings” – but it’s really a mystery that has plagued biologists for over a century. Interesting and competitive theories of insect wing evolution have emerged in recent years, but none have been completely satisfactory. Finally, a team from the Marine Biological Laboratory (MBL), Woods Hall, has long since resolved this controversy using scientific papers as well as indications of sophisticated genomic approaches. The study, by MBL Research Associate Heather Bruce and MBL Director Nipam Patel, was published this week. Nature Ecology and Evolution.
The wings of the insect, the team confirmed, developed from the growth or “lobe” on the legs of the ancestral crustaceans (yes, crustaceans). After this marine creature migrated to land-dwelling about 300 million years ago, parts of the legs close to its body became embedded in the body wall during embryonic development, perhaps to better support its weight on land. “Then the lobes of the legs went over the back of the insect, and later it formed the wings,” says Bruce.
The insects incorporated the two crustacean leg parts of the ancestors (labeled 7 in red and 8 in pink) into the body wall. The cupboard on the leg segment 8 later formed the wing in the insects, while in the crustaceans this corresponding structure forms the tergal plate. Credit: Heather Bruce
Bruce says one of the reasons it took centuries to figure this out was that it wasn’t until about 2010 that it was discovered that the insects within the arthropod film revealed by genetic similarities are very closely related to crustaceans.
Says Bruce, “Previously, based on morphology, everyone had classified insects into the maryopod group, with millipedes and centipedes. He says, “And if you had a lot of tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking, tweaking Which was spread by insects and had no corresponding structure in the ancestors – because the researchers were looking for the wrong place for the insect ancestor. “
“People are very excited by the idea that something like the wings of an insect could be an evolutionary novelty,” says Patel. “But one story that fills in with genomic comparisons is that there is nothing new; Everything came from somewhere. And you can, in fact, find out where. “
https://www.youtube.com/watch?v=enRD31IQXeU
The Parhial Hawinesis, which shows up eating here, has had its genome sequenced and is the most genetically tractable crustacean for biological research. Credit: Heather Bruce
Bruce smelled his recently reported discovery while comparing genetic suggestions for the split legs of tiny beach-hopper crustaceans. On the other hand, And the split legs of insects, including the fruit fly Drosophila And beetles Tribolium. Using CRISPR-CAS9 gene editing, she systematically disabled five shared leg-patterning genes. On the other hand And in insects, and those genes were found to correspond to parts of the six legs away from the body wall. On the other handHowever, there is an extra, seventh leg part next to his body wall. Where did that segment go, she wondered? “And so I started digging into the literature, and I really came up with the idea that was suggested in 1893, the insects included their proximity. [closest to body] “The foot region in the body wall,” she says.
He says, “But I still didn’t have the wing of the story.” So I kept reading and reading, and I came up with this 1980s theory that insects could not fit their nearest leg into the body wall, but the small lobes on the back Went to the side and formed the wings. I thought, wow, my genomic and fetal data support these old theories. “
It would have been impossible to solve this long puzzle without the tools now available to investigate the numerous genomes of living things, including On the other hand, Which has evolved into the most genetically treatable research organism in Patel Lab Crustaceans.
Reference: “Knockout of the Crustacean leg pattern genes indicates that the insect’s wings and body walls evolved from parts of the ancient legs” Heather S. Bruce and Nippam H. Patel, by 1 December 2020, Nature Ecology and Evolution.
DOI: 10.1038 / s41559-020-01349-0
