Courtesy rijksbandradio (original image) via Flckr; graphic by author.By now most readers are aware of the double helix, the two intertwined ribbons of genetic information that make up our DNA.
Now researchers at University of Cambridge have announced the discovery of a quadruple helix in the human genome. The four-stranded genetic ribbons are termed G-quadruplexes because they contain high levels of the nucleotide guanine (the other 3 nucleotides are adenine, thymine, and cytosine – together they make up the G, A, T, and C elements of DNA; uracil (U) replaces thymine in RNA). G-quadruplexes mainly appear at the moment of cell replication, when cells divide and multiply. Researchers think this indicates that G-quadruplexes are an essential part of the replication process. The upsurge of G-quadrupleexes was detected using fluorescent biomarkers. The discovery could open up new avenues in the treatment of cancer
"The research indicates that quadruplexes are more likely to occur in genes of cells that are rapidly dividing, such as cancer cells,” said Shankar Balasubramanian, the study’s lead researcher. “For us, it strongly supports a new paradigm to be investigated -- using these four-stranded structures as targets for personalised treatments in the future."
Balasubramanian, a professor at the Department of Chemistry and Cambridge Research Institute, thinks synthetic molecules could one day be used to corral the G-quadruplexes and hinder the out-of-control cell division often prevalent in cancerous cells. In fact, the research team has already been successful in slowing down the replication process by using such molecules. During their experiments, when cell division was blocked, the number of G-quadruplexes decreased.
The research was published in Nature Chemistry. The 'quadruple helix' discovery comes 60 years after the discovery of the double helix in 1953, also at the University of Cambridge.
"Reporting in the journal Science, Paul Kubes and colleagues filmed immune cells called neutrophils finding their way to a mouse's wounded liver. The researchers wanted to understand how neutrophils find injuries when bacteria aren't around to signal the damage."
Courtesy Nissim Benvenisty
Stem cells have the potential to become almost any type of body part. I believe they will soon be used to rejuvenate, repair, or rebuild body parts. Look at our past Science Buzz posts about stem cells. Bad knees or hips? Inject some stem cells to rebuild the cartilage. Stem cells also can repair cut spinal cords, damaged eyes, diseased brains, or help a diabetic's pancreas make insulin.
Up until now, the stem cells created by reprogramming adult skin cells still had bits and pieces remaining that were not safe enough for human applications.
"Now stem cell researcher Derrick Rossi of Harvard Medical School in Boston and his colleagues have developed a way to reprogram cells using synthetic RNA molecules." (Science Magazine) The technique is also twice as fast and 100% more efficient. The team calls its cells RiPS cells, for RNA induced Pluripotent Cells.
The new technique, is published online in the journal, Cell Stem Cell.
Courtesy Harvard University Gazette
"In the half-century since Henrietta Lacks' death, her ... cells ... have continually been used for research into cancer, AIDS, the effects of radiation and toxic substances, gene mapping, and countless other scientific pursuits".
Courtesy USDALets say you are walking in the woods and you see a 12 point deer ahead of you. You sneek up quietly but not quietly enough. The deer hears you looks right at you and begins to charge. Before you know it its right antler has sheered off your arm! What do you do? Well if you were a salamander you would simple re-grow it.
For centuries scientist have wondered how salamanders regenerate limbs. In recent history they believed the tissue around the injury regressed into pluripotent stem cells (the kind we have all heard about that can morph into many different types of cells) and they reform into each cell type needed to create the limb.
This research was conducted to help understand how the salamander was able to do this amazing feat so that we could apply it to humans. Unfortunately, stem cells are not the easiest thing to work with but, that is old news now.
New research has shown that the salamander's cells do not regress but have memory that allows them to grow into what they once were. The memory is so good that the cartilage from the lower limb re-grows in the lower limb again.
The way scientist were able to do this was by engineering a florescent protein in a group of salamanders and transplanted only a select cells (skin, bone, muscle, etc) into embryos. After the embryos had grown, a limb was amputated. When it re-grew scientists observed that the glowing cells were not spread out amongst all the different cell types, as it would be if the cells had regressed into blank slates, but the florescent protein was only found in the original transplanted cell type.
Good new for us humans. This new finding may, although most likely not in our life time, make it easier to regenerate human organs.
The cells of our bodies are constantly in motion. In fact, zap them with light and they vibrate, creating sound – much too faint to hear, but sensitive instruments can record the vibrations. Two biologists at the University of Manchester in England have found that healthy cells vibrate differently than cancerous cells. They are hoping to use this to develop new, less-invasive tests to diagnose cancer.
Courtesy EkemLast week we learned that scientists cloned human embryos using adult skin and fertile eggs from a woman donor. Now the Human Fertilization and Embryology Authority in Britain has approved creating human embryos using eggs from animals like cows or rabbits. Because the animal cell's nucleus would be removed before human DNA was added, scientists said the resulting egg would not be a chimera.
"Cow eggs seem to be every bit as good at doing this job as human eggs," said Lyle Armstrong of Newcastle University.
"We will only use them as a scientific tool and we need not worry about cells being derived from them ever being used to treat human diseases," Armstrong said.
Animal eggs are abundant and easily obtained. Researchers hope to refine their techniques by practicing first on animal eggs to producing human stem cells. Human stem cells, which have the ability to develop into any cell in the human body, show promise for understanding and healing many human ailments. The embryos would not be allowed to develop for more than two weeks.
A paper published in the online journal, Stem Cells, yesterday titled "Development of Human cloned Blastocysts Following Somatic Cell Nuclear Transfer (SCNT) with Adult Fibroblasts" is the first documented demonstration that ordinary cells from an adult human can be used to make cloned embryos mature enough to produce stem cells
"A research team at Stemagen, a biotech company based in San Diego, California, started with skin cells donated by two men and 25 eggs, or oocytes, donated by women at a nearby fertility center. The scientists removed the DNA-containing nuclei from the eggs and replaced them with DNA from the donor skin cells. Two of the eggs became 5-day-old embryos, or blastocysts, that were clones of the male donors."Science
The next big step will be to create a human embryonic stem cell line from cloned embryos. Stem cells from cloned embryos could provide a valuable tool for studying diseases, screening drugs, and creating transplant material to treat conditions like diabetes and Parkinson's disease.
As expected, critics are raising objections. This procedure requires cutting healthy eggs out of women, then altering them to produce living embryos, which are then destroyed. Should this be allowed?