Enviropig Step 2

Dept. of Agronomy and Horticulture Author

01/26/2016 Added

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The second portion of the Enviropig story that tells us how scientists transform embryos into transgenic organisms. For more information visit the Enviropig website: https://ge.unl.edu/enviropig/

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[00:00:06.895](upbeat music)
[00:00:16.136]^ My name is Dr Brett White
[00:00:17.459]and I'm an associate professor of animal science
[00:00:20.246]at the University of Nebraska Lincoln
[00:00:22.196]and my specialty is reproductive physiology.
[00:00:25.470]My job is to transform animal cells
[00:00:28.721]to create a genetically engineered animal.
[00:00:32.737]So the production of the enviropig
[00:00:35.106]was actually performed by scientists
[00:00:37.544]at the University of Guelph
[00:00:39.982]and I'm just giving you an overview
[00:00:43.488]of the same processes
[00:00:45.381]or similar processes that might be used
[00:00:47.537]to make a genetically engineered animal.
[00:00:50.068]This technology is newer and more efficient
[00:00:52.599]so therefore it's more commonly used now.
[00:00:55.896]CRISPR stands for clustered regularly interspaced short
[00:01:00.284]palindromic repeats.
[00:01:02.444]CRISPR was first detected
[00:01:04.510]in a specific form of bacteria
[00:01:07.807]and it's part of its innate immune repsonse
[00:01:10.674]so it uses short RNA sequences
[00:01:14.180]to determine if foreign DNA is present
[00:01:17.222]and remove that from the system.
[00:01:19.892]These sequences are followed by
[00:01:22.260]sort of gap DNA or space DNA
[00:01:25.998]and it utilizes that to
[00:01:29.046]basically check for foreign DNA
[00:01:30.997]and try to remove that from the system.
[00:01:33.969]Scientists can make use of
[00:01:35.223]CRISPR "scissors" by creating a CRISPR
[00:01:38.264]that cuts DNA in a targeted region.
[00:01:42.056]The CRISPR and the transgene
[00:01:44.053]we wish to incorporate into the animal
[00:01:47.002]are injected into an oocyte or egg.
[00:01:51.042]When the CRISPR cuts the DNA of the egg,
[00:01:54.060]hopefully the transgene is nearby
[00:01:56.196]and becomes incorporated
[00:01:58.147]when the DNA is repaired
[00:02:00.111]by natural mechanisms.
[00:02:02.456]The machine used for this is
[00:02:05.219]high-powered microscope,
[00:02:07.193]where we inject the CRISPR and transgene
[00:02:09.863]into the cytoplasm of an egg or oocyte.
[00:02:13.531]Each major movement on the controllers
[00:02:16.870]will make a slight movement at the level of the embryo.
[00:02:21.612]We grab the embryo with a suction
[00:02:24.746]from one side,
[00:02:26.047]hold it in place.
[00:02:27.463]Then we inject the embryo
[00:02:29.204]with a finely sharpened pipette
[00:02:34.150]and inject our CRISPR and transgene
[00:02:37.540]into the cytoplasm of the oocyte.
[00:02:40.512]We don't know what cells have the transgene
[00:02:43.391]so therefore we inject a bunch of cells
[00:02:45.922]and we transfer them all into
[00:02:49.358]other females to try to produce progeny.
[00:02:53.352]The eggs are transferred into
[00:02:55.419]what we call a surrogate or recipient female
[00:02:58.182]that's at a similar stage of her reproductive cycle
[00:03:02.384]and we put in about 30 to 40 embryos
[00:03:06.796]and hope that she carries these embryos to term.
[00:03:11.324]The transformed eggs are then
[00:03:13.762]given to the pig breeder,
[00:03:15.862]who will try to produce progeny.
[00:03:19.113]So in summary,
[00:03:21.528]we inject fertilized embryos with CRISPR
[00:03:26.171]and our transgene
[00:03:28.029]into the cytoplasm
[00:03:29.933]and hope that that becomes integrated
[00:03:32.905]and transforms the embryo.
[00:03:35.482]Once we've transformed embryos,
[00:03:37.688]we don't know which ones have incorporated
[00:03:39.745]the transgene
[00:03:40.952]so we have to wait until the piglets are born
[00:03:43.646]to then screen those animals.
[00:03:47.361](upbeat music)

Enviropig Step 2

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Enviropig Step 2

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