Defrost and unclose
Clone of frozen brainsPyotr Smirnov, "Newspaper.
Ru»The Japanese managed to clone a mouse that had been lying in a regular freezer for 16 years.
There was a hope to clone mammoths and the "Ice Man". If you liked the meat from the freezer, you can clone the cow that gave it. The brain and kidneys are best suited for cloning.
Despite the blessing of the Roman Catholic Church to create analogues of embryonic stem cells from skin cells, biotechnologies around the world do not stop working to improve cloning methods and techniques. They hope that sooner or later their finest hour will come.
The next successful work performed by Teruhiko Wakayama and his colleagues has nothing to do with therapeutic and even more so reproductive human cloning. But it can mean much more to society than dozens of purely fundamental publications devoted to the details of this biotechnological process.
Scientists managed to clone a mouse using the genetic material of a rodent that had lain for 16 years in a standard freezer at -20 Celsius.
A cloned mouse (left) obtained from brain cells thawed after 16 years of its owner's stay in the freezer. Initially, the "brain" mouse shown in this photo had three brothers, but one died immediately after birth from respiratory failure, and another was eaten by a surrogate mother a day later; one remained and also lived to adulthood. //National Academy of Sciences, PNAS 2008.
The very term "cloning" means creating an organism with an absolutely matching genome. But after the creation of Dolly the sheep 12 years ago, this means, in fact, only one way of such "reproduction": transfer of the nucleus of an ordinary body cell into an egg cell without a nucleus, followed by transplantation into the future mother. Despite the apparent "high-tech" process, in fact, the cytoplasm of the egg takes over the main work. She manages to somehow change the processes going on inside the nucleus and make it divide, as if the egg had just been fertilized, turning into a zygote.
The zygote itself is not always transferred to the mother's body. You can force it to divide in vitro, and then researchers will have a wonderful material for isolating embryonic stem cells in their hands. It can then be used to grow individual tissues, and in the future – whole organs, ideally suited to the donor of the cell nucleus. It is also not necessary that an "empty" egg and a nucleus with a genome belong to the same species: for example, British scientists transplant the nuclei of human cells into deprived cow eggs.
The use of frozen material is also not new: in 2004, South Asian banteng bulls were cloned from frozen cells, and during in vitro fertilization, frozen sperm cells can be used, and more recently, eggs. But in order to preserve the viability of the cells, it is necessary to quickly cool them according to a special program to the temperature of liquid nitrogen, with the addition of appropriate reagents that prevent the formation of destructive ice crystals.
The "eldest" among the mice cloned from the thawed brain (far right) not only lived to adulthood, but also turned out to be quite a successful dad: all the mice in the photo are the fruit of the union of a male with a black female on the left. //National Academy of Sciences, PNAS 2008.
Wakayama and co-authors of the publication in the Proceedings of The National Academy of Sciences reasonably reasoned that it is not necessary to worry about the integrity of the entire cell for cloning. Therefore, they used the classical method described by the classical formula for biologists, which is hardly worth reading to animal advocates: "Let's prepare the mouse for the experiment. From the resulting gruel..."
The scientists prepared portions of gruel separately from different organs of a mouse that had been lying in the freezer for 16 years. Nuclei were isolated from each portion of the suspension, and then transferred to donor eggs, some of which were placed in mice – "surrogate mothers", and some were left to develop in a test tube.
From 1,606 isolated nuclei, Wakayama managed to obtain 1,100 activated eggs, which subsequently gave 13 healthy mice and 34 cell lines. Although these "losses" seem large, they are actually several times smaller than those faced by technology developers at the same stages of zygote development.
Biotechnologies not only demonstrated the technical feasibility of such an experiment, but also compared the suitability of different tissues for this. The brain, blood from the caudal vein, pancreas and kidneys are best suited for creating clones. But the bone marrow, thymus, spleen, heart, liver and intestines have nuclei with low transfer efficiency.
The donor from whose tissues the mice were obtained, before defrosting, cutting and turning his organs into "mush". //National Academy of Sciences, PNAS 2008.
In such a strange way, the technology of freezing old or terminally ill people entirely, which has been somewhat forgotten lately, has received support. In addition, scientists are now planning to find suitable frozen material for their work in the storerooms of paleontologists.
However, it is premature to talk about the prospects of cloning a mammoth or the same Otzi: after all, even whole pieces of rapidly decaying DNA are not enough – dozens of unchanged nuclei are needed, which are very problematic to isolate from long-dead animals.
Portal "Eternal youth" www.vechnayamolodost.ru05.11.2008