Cow engineered to produce less allergenic milk

Researchers milk mice, make cow that should provide "high cheese yields."

But deleting the gene is a real challenge. Unlike mice, where genes can be knocked out routinely, the techniques for elimination of genes and cloning of embryos in the cow are quite a bit less advanced. So, the authors turned to a different approach, called RNA interference. This involves designing short pieces of RNA that match sequences in the messenger RNA produced by the BLG gene, which allows them to base pair and form stretches of double-helical RNA. This keeps the messenger RNA from being translated into the BLG protein. [...]

But a cultured cell doesn't actually make any milk. So, the authors turned to a convenient research animal: the mouse. Unfortunately, the mouse (like us humans) doesn't make any BLG protein. So, the authors first had to engineer a construct that caused the mice to produce bovine BLG in their mammary glands. Then they had to insert a second construct, one that produced the interfering RNAs. Then they had to get the mice pregnant and milk them. I am not making this up. Their methods section includes the description, "Milk was collected manually into capillary tubes by gentle massage of teats following oxytocin administration."

Again, it all seemed to work nicely. Mice without the interfering RNAs produced lots of BLG, while those with them barely made any. With the general approach validated, the authors turned to the lengthy and expensive process of making a transgenic cow by injecting the DNA that encodes the interfering RNA into cells in culture, then transferring the nucleus of those cells into a cow's egg in order to make a clone. This process is generally inefficient in many mammals, and often produces defective embryos. Only five pregnancies resulted from 57 cloning attempts, and only one produced a live birth. "Unexpectedly, the miRNA 6--4 calf was born without a tail." Oops.

The authors can't tell whether this was a cloning defect, a defect caused by the insertion of the genes for the interfering RNA, or simply a random genetic defect that has nothing to do with the experiments. Breeding should help sort that out.

Fortunately, the calf was a female, and hormone treatment got it to make milk. Which (no doubt much to the authors' relief), did not contain BLG. In fact, the protein levels in the milk remained constant, as other proteins were increased to compensate for the loss of BLG. These include the caseins, which the authors suggest "should provide for increased calcium levels and high cheese yields."

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4 Responses:

  1. eah says:

    That.. just... ... buh.

    Anyway, sincerely, thank you for calling attention to this.

  2. Phil says:

    What, no "doomed" tag?

  3. Oh we got a new computer but it's quite a disappointment
    'Cause it always gave this same insane advice:

  4. trollop says:

    Actually some types of cows already have less allergenic milk. Depending on what you are allergic to exactly. If it's casein, you're in luck!

    Turns out I can drink cow milk in the UK. No crazy itching or any other repercussions. I was majorly bummed that I didn't indulge more on my London trip. So this lead to some research. There's a book out "Devil In the Milk" ...which sounds like hoo haw, but I can say that I don't react to some types of cow milk.

    There is a mutation of the casein protein in most of the American cattle used for dairy. European breeds like the Guernsey and the Jersey cows have the A2 casein, whereas here in the US it's a mutated A1 casein protein. Goats, sheep, and water buffalo also have A2 casein. And of course someone has a trademark on A2 milk, so farmer's can't just label their milk as being A2.

    There's a dairy that has Jersey cows with milk and yogurt available here in the bay area. Plus it's creamier. Kerrygold Irish butter at Trader Joe's that's fine too. Actually it's much better than regular butter. It's delicious and creamy. Some imported chocolate and cookies also fine. I'm still experimenting.
    Unfortunately I'm still allergic to eggs.

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