Andrew ( Gabriel ) Livshits
Biologists managed to find a way to produce induced pluripotent stem cells without the use of genetic engineering - have transformed ordinary cells into stem solely by exposure to chemicals . Details with reference to the article in Science leads scientists Nature News.
Experiment scientists from the University of Beijing in China was conducted on cells of mice . Instead of introducing the cells into additional DNA fragments , researchers are working on chemicals. Biologists searched for molecules that can cause the same effect as the activation key for cell reprogramming gene Oct4. In the preliminary stages of their work, researchers sifted through about ten thousand substances.
Initially, scientists found one substance that causes a number of changes in the cells that resemble the initial phase of reprogramming . These changes do not lead to the transformation of stem cells , but experts have continued to work and added another ingredient: 3 - deazaneplanotsin A short DZNep. This reagent was already well known to molecular biologists as an inhibitor of DNA methylation , so adding it brought the first positive result - a few turned into stem cells .
Addition of an inhibitor of DNA methylation ( a substance that blocks the reaction of adding methyl groups to DNA ) proved critical step due to the impact on the mechanism of regulation of gene activity . Methylated DNA in the cells available for reading , and return to its normal shape , by contrast, permits the reading of genetic information subsequent to the synthesis of proteins. Inhibitors of DNA methylation including DZNep, other scientists have investigated a group including as a means to reactivate silent genes in cancer cells. Chinese experts have been able to find this reagent used in the process of obtaining stem cells.
Final reprogramming recipe provides not only the impact of a substance capable of introduction into the cell to replace the additional copies of the Oct4 gene and not only DZNep. Another five ingredients have significantly improved the probability of successful cell transformation , up to 0.2 percent. This figure , as the researchers note, is comparable with the results of genetic engineering reprogramming.
Conducted with isolated from culture reprogrammed (or induced ) stem cell experiments have shown that they have the same properties as stem cells genetically engineered nature. Furthermore , the authors stress the security technique selected reagents five of the seven components are already registered as pharmaceuticals , which involves passage of the necessary checks.
Researchers at Oregon Health and Science University , together with colleagues from the School of Medicine at Boston University and Mahidol University in Bangkok (Thailand) managed to realize the once popular in genetics idea: instead reprogram mature cells into stem cells or simply removing them from embryos scientists first cloned from adult human fibroblasts , and then a clone obtained from the stem cells .
Under the " embryo " in an article for the journal Cell researchers meant not a product formed from the nervous system , and the blastocyst . They are derived from donor eggs and do not even fertilize : about any " abortive material " are not talking.
Scientists emphasize that using embryonic stem cells is supposed to treat life-threatening diseases, they can be used to restore lost organs and donor eggs obtained from volunteers who are paid a few thousand dollars. Donation for research purposes even easier health because it does not require synchronization of menstrual cycles of the donor and of the recipient , and the safety of the procedure is comparable to bone marrow donation .
Cells derived from blastocysts by all distinguished characteristics of stem cells, and monkey cells similar to previously succeeded in transforming cells of pancreas , bone marrow, hepatocytes ( liver cells) , neurons and even cardiac muscle cells , which may decrease synchronously with each other. The first line of stem cells has been derived from clones created from the skin cells of the human fetus ( again explain: Order Standard laboratory cell cultures , and did not work directly with abortive material) , and the second line of the researchers obtained using the genetic material of an 8- month-old baby with a rare congenital disease syndrome Leia . This is an extremely rare disorder caused by defective mitochondria and is accompanied by disturbances in the nervous system , and the preparation of stem cells could help researchers in finding possible treatments .
Therapeutic cloning is an alternative to the two techniques advantages. In contrast, the reprogrammed cells can be cloned embryonic greater potential to be converted into any desired tissue, as compared with the conventional embryonated they do not require a unique genetic material : Cloned embryos are genetically distinguishable from the cells of the patient.
Scientists have discovered that bacteria causing leprosy, Mycobacterium leprae is able to convert glial ( Schwann ) cells in the brain stem and use them to spread throughout the body . The work is published in the journal Cell, and its summary results NatureNews.
Schwann cells called helper brain fibers that surround neurons , turning around like a coat . Schwann cells provide electrical isolation of neurons through which increases the speed of conduction of excitation . As the majority of the glial cells , they usually do not move on the living body, and always in the same place .
The authors found that the leprosy mycobacterium M. leprae, penetrating into Schwann cells , reprogrammed them into stem cells . This is done in order to use the past as a transport . Marrow stem cells , unlike mature , quite often migrate long distances. Same bacteria infected stem cells , as the authors found to penetrate into the muscles , passing through the barrier that separates the brain from the rest of the body.
Reprogramming is performed by turning the "mature" and the inclusion of "children's" genes Schwann cells . Some also managed to get stem cells Shinya Yamanaka , which received in 2012 for his work Nobel Prize. Discovered by the authors of the new phenomenon is quite unusual for bacterial infections. In the master control genes normally interfere viruses that , for example, moth caterpillars zombie , forcing them to climb trees to increase the radius of the spread of virions.
Scientists have found that the division of stem cells in the brain is controlled by genes associated with lipid synthesis . The work is published in the journal Nature, and its summary results press release of the Swiss Federal Institute of Technology in Zurich.
The authors showed that the inhibition of the synthesis of new cell membrane lipids in stem cell division processes are blocked . This synthesis is carried out which a protein complex of fatty acid synthase (Fasn) gene controlled Spot14. Unlike mature neurons , stem cells synthase Fasn active , turning glucose consumption " building blocks " for new cell membranes . Such a connection with the division of metabolism indicates scientists target influencing on which potentially may stimulate neurogenesis .
Marrow stem cells are the only source of new neurons in the brain of an adult animal . In mammals, they are located in two areas - the olfactory bulb and the hippocampus . The first of these zones , as shown by recent studies , a person not involved in neurogenesis , but he is very active in the second zone .
Mechanisms that trigger the division of stem cells and the formation of these new neurons have been studied quite weak . It is known that on the level of the organism , this process can affect the physical activity and antidepressant drugs . More about this can be found here and here.
An international group of biologists read rotifers Adineta vaga genome and found that these organisms have renounced sexual reproduction millions of years ago , because of acquired characteristics of the genome are no longer able to return to it . The research is published in the journal Nature.
A key differentiator of the genome Adineta vaga, according to scientists , is " shuffling " in it alleles . Those genes that in organisms with sexual reproduction are located on paired chromosomes in rotifers confused - and baseline maternal and paternal copies from baseline Adineta vaga are often found on the same chromosome. This makes it impossible for normal sexual reproduction , as in the formation of gametes ( meiosis ) occurs pairing of chromosomes c subsequent exchange genes ( crossing-over ), and rotifers have many genes simply do not mate with whom .
Despite the fact that male rotifers never failed to detect , scientists still could not rule out that they have a certain sexual process in the very rare cases ( even among "normal" rate of microorganisms is asexual reproduction , and to the sexual process , they resort very rare).
Furthermore , the reading Adineta vaga genome revealed that about 8 percent of the total DNA sequence of invertebrate represent " stolen " from the bacteria and other microorganisms. That rotifers easily include foreign DNA into their genome , and it is maintained by a variety of species , has been known since 2008. However, to read the full genome scale of this process was not clear.
Abandonment of sexual reproduction occurs quite often in different groups of animals, but such a process always leads to a relatively rapid extinction . Microscopic multicellular rotifers, which can usually be found in pools and other freshwater bodies , are an exception to this rule. This group exists without sexual reproduction seems to have a few million years and managed to split into more than four hundred species. The success of parthenogenesis in rotifers have been linked to the fact that these animals are very easy to borrow someone else's genetic information , and thus maintain their diversity.
Japanese research team was able to get a miniature human liver from stem cells. Pluripotent stem cells turned into a disk diameter of 4 millimeters , which confirmed its efficiency , being transplanted in experimental mice with the failed own liver . Details of the work presented in the journal Nature, and briefly spoke about her Nature News.
Researchers have used the induced pluripotent stem cells , i.e. stem cells , obtained by reprogramming the mature adult cells . Then they succeeded in transforming both hepatocytes and cells of blood vessels and connective tissue, scientists have three-dimensional structure , a histological analysis showed that all required elements for the liver .
Transplant grown in test tubes miniature drives about four millimeters in diameter experimental mice demonstrated performance artificial liver . Two days after surgery the blood vessels of the animal connected with the vessels of the liver, and the cells continued to divide : the organ began to grow. The liver is known for its high capacity for regeneration , so patients who need a new liver , often transplanted small part of the body , taken from a living donor .
Talk about the imminent introduction into clinical practice of liver transplants of stem cells is not necessary. The researchers intend to observe the behavior of the first artificial liver in mice , to ensure its security and stability. Some previous research works have shown that induced stem cells regenerate in most tumor cells , so we first check the ability of the new liver to limit their growth and maintain the required functions .
Despite the fact that liver transplant patients are well established and after they can return to an active life , they can not be considered routine and affordable operation : immunologic restrictions hamper the selection of the donor. To address the shortage of scientists currently working in several ways : some groups are trying to collect the liver cell cultures from ready ( a liver already printed on the 3D- printer ) , others are trying to repeat the process of forming the body of stem cells from scratch.