Thawed embryos

Scientists have successfully frozen (and thawed) a fish embryo for the first time

Anna Kerman, XX2 century, based on the materials of SCBI: Smithsonian Scientist and Partners Revolutionize Vital Conservation Tool With Use of Gold Nanotechnology and Lasers

For more than 60 years in a row, scientists have been trying to preserve the embryos of the danio-rerio fish using cryotechnologies. This fish is often used as a model animal in research related to human health. According to an article published in ACS Nano, experts from the Smithsonian Conservation Biology Institute and the University of Minnesota have successfully cryopreserved the embryos of a danio fish for the first time. During the work, the scientists used gold nanoparticles and a laser to defrost the embryos. Previous researchers have failed at this stage. It is believed that the results of the new study will be useful for health, species diversity conservation and fish breeding.

Figure from the article in ACS Nano – VM.

"There is no doubt that the use of this technology, in fact, represents a paradigm shift in cryopreservation and conservation of many species of wild animals," says study co–author Mary Hagedorn, a researcher from the Institute of Conservation Biology. – To make something work at such low temperatures usually requires a little ingenuity. Therefore, we used a unique approach, combining biology and existing technologies. And we managed to do something that was previously impossible: successfully freeze and unfreeze the embryo in such a way that after the procedure it did not collapse, but began to develop."

By freezing sperm, eggs and embryos, specialists can preserve endangered species and preserve genetic diversity. Moreover, frozen biomaterial can be used to restore the latter after years – and even centuries. Although scientists have successfully frozen the embryos of many mammals, as well as the sperm of many fish species, when working with fish embryos, researchers have encountered a number of difficulties.

Successful cryopreservation involves freezing the embryo – putting it into a cryogenetically stable state – and subsequent defrosting. It is important that defrosting should be done faster than freezing. In addition, it is necessary to use a special antifreeze that stops the growth of ice crystals. These crystals, like needles, destroy membranes and cause the embryo to literally fall apart. But fish embryos are very large in size. This makes it difficult to freeze quickly. In addition, it is more difficult to prevent the formation of ice crystals in this case. And finally, since aquatic animals have to exist in an unfavorable environment, the membranes of the embryos are practically impermeable, which makes it difficult to process them with antifreeze.

Technologies that allow the use of lasers and gold nanoparticles are now actively developing – and they have ensured the success of the new research. Gold nanotubes, tiny golden cylinders, turn light (for example, from a laser) into heat. The researchers placed antifreeze and nanotubes inside the embryos, which allowed to speed up the defrosting process. Embryos subjected to such treatment have developed at least to the stage of a diurnal embryo. They have formed a heart, gills and tail muscles. In addition, the embryos were moving, demonstrating their viability. The next step of scientists will be fine–tuning the developed approach - this is necessary to increase the proportion of surviving embryos. In addition, the researchers plan to develop a process automation system to increase the throughput of the technology.

The new approach can also be used for cryopreservation of embryos of other fish species, since they are similar to danio embryos. Also, the technology can be changed somewhat in order to preserve the embryos of reptiles and birds, as well as to increase the efficiency of freezing mammalian embryos, including giant pandas and large cats. Finally, this approach can help fisheries work more efficiently, thereby reducing their impact on wildlife.

Portal "Eternal youth" http://vechnayamolodost.ru  18.07.2017