Issue 120 / November - December 2017
Hidden Oceans in Frozen Worlds
Hidden Oceans in Frozen Worlds
Saxena P. et al. Relevance of tidal heating on large TNOs. Icarus, December 2017.
Searching for alien life, a new study from NASA suggests that some icy worlds in our outer solar system, including Pluto, Eris and other trans-Neptunian objects (TNOs) may harbor liquid water oceans beneath the surface. These frigid worlds are too cold to have liquid water on their surfaces, where temperatures are usually below minus 200 degrees. But new evidence shows that there may have layers of liquid water beneath their icy crusts. Underground oceans have been previously suggested in a number of icy worlds such as the Saturn satellites Titan and Enceladus. It is considered that these subsurface oceans stay liquid as a result of a mechanism called "tidal heating." The powerful gravitational pull of these worlds' giant parent planets result in the stretch and flex of their interiors which heat up because of the friction. The NASA team used the equations for tidal heating and calculated its contribution to the “heat budget” for a wide variety of discovered and hypothetical TNO-moon systems. Their analyses revealed that tidal heating can be a tipping point that may have preserved oceans of liquid water beneath the surface of large TNOs like Pluto and Eris to the present day. Tidal heating is believed to be only a "tipping point" as there's another factor in play: the heat produced by the decay of the objects' radioactive elements. These subsurface oceans are potential reservoirs of water and life, which are two critical elements for extraterrestrial life. This study further supports the idea that our solar system may harbor many more potentially habitable worlds than previously thought.
Reading Aloud Boosts Memory
Noah D. et al. This time it’s personal: the memory benefit of hearing oneself. Memory, December 2017.
A new study found that the dual effect of both speaking and hearing helps encode the memory more strongly, hence the act of reading and speaking text aloud is a generally more effective way to remember information than reading it silently or just hearing it read aloud. The study recruited 95 college students, asking them to remember as many words as possible from a list of 160 words. In one session, they read a list of words into a microphone, then returned two weeks later for a follow-up. In some cases, the participants read the words presented to them aloud, while in others, they either heard their own recorded voice played back to them, heard recordings of others reading the words, or read the words silently to themselves. Afterward, they were tested to see how much they remembered from the list. The participants remembered more words if they had read them aloud compared to all other conditions, even the one where people heard their own voices reading the words. Hearing your own voice seem to add a substantial improvement on memory. This could stem from synergistic interactions of two biological processes. First, motor processing cues are activated as a result of the act of speaking aloud because your mouth is physically mouthing the words. Second, your auditory processing is also activated because you’re hearing the words, and in addition to hearing words, you’re hearing them in your own voice. It is also possible that production is more memorable at a higher cognitive level because it includes a distinctive, self-referential component. These observations emphasize the invaluable role of rehearsals in learning and remembering. In summary, reading aloud in the moment is a very effective memory tool.
A New Drug to Stop the Cancer Cells
Kelly NJ et al. Hypoxia activates cadherin-22 synthesis via eIF4E2 to drive cancer cell migration, invasion and adhesion. Oncogene, October 2017.
Scientists found a way to decrease the spread of cancer by hindering a protein that keeps tumor cells together and allows them to invade tissues. Tumors that have outgrown their blood supply, and are therefore deprived of oxygen, are the most difficult to treat, as the cells within are capable of spreading rapidly and doing the most tissue damage. Consequently, higher levels of hypoxia in a tumor are strongly linked to poor survival rates in cancer patients. ┬áAnalyzing over a hundred breast and brain cancer patient tumor samples, researchers found that the more the tumor was deprived of oxygen (also called hypoxic), the more cadherin-22 gene was expressed in it. They also found that the more cadherin-22 is expressed in a tumor, the more advanced the cancer stage and the worse the prognosis is estimated for the patients. Cadherin-22 is located on cell surfaces, allowing hypoxic cancer cells to stick together and migrate collectively as a group. When researchers genetically removed cadherin-22 from the cultured cancer cells in the hypoxia conditions in the lab, they found a dramatic reduction in migration and invasion rates of breast and brain cancer cells by up to 90 percent. This study highlights cadherin-22 as a potential new target of cancer therapy and leaves the challenge for cancer biologists to find a treatment or a drug that can block cadherin-22 to potentially prevent cancer cells from moving, invading and metastasizing.comments powered by Disqus