AP Biology class blog for discussing current research in Biology

Author: thephilosopher

“Pink Noise” Improves Sleep

Insomnia affects nearly ten percent of Americans. A survey of more than seven thousand people found that 23% exhibited signs of insomnia and estimated that lack of sleep costs the country 63 billion dollars annually in lost productivity. Some preliminary studies have suggested that applying a gentle current to the brain might ameliorate this issue, but the idea has been understandably unpopular among potential patients.

In an effort to find another method to ameliorate insomnia, researchers conducted a study of of “pink noise,” a type of noise with a power spectrum that is inversely proportional to its frequency. It is called pink noise because visible light within this spectrum appears pink in color. In executing their study, the scientists had eleven volunteers spend two nights in their sleep lab, one while pink noise matched to their brain waves was played and one in silence. Before they went to sleep, they were showed pairs of words and asked to memorize them. The volunteers were also hooked up to EEGs so that their brains could be monitored while they slept.

During the night with pink noise playing, the researchers recorded prolonged deep sleep and increased size of the  wavelengths in the volunteers’ brains. These slow brain waves are connected with memory retention and “information processing,” which was reflected in the researchers results. The volunteer sleepers performed better in the memory exercise when the pink noise had played as they slept.

The scientists involved in this study emphasize that the pink noise was matched to the brain waves of the patients, and that further research and development could lead to tools to improve sleep and even enhance brain activity while awake. Entitled Auditory Closed-Loop Stimulation of the Sleep Slow Oscillation Enhances Memory, the study was published in Neuron.

Hypocretin: A New Avenue for Antidepressants

Depression is a major psychiatric disorder in the United States, affecting about six percent of the population. However, antidepressants in common use such as selective serotonin reuptake inhibitors (SSRIs) and other drugs have only flimsy evidence to support their efficacy. Recent studies suggest that positive results with these medications may be the result of the placebo effect rather than an effective treatment. Critics of current remedies for depression point out that they aren’t linked to observed deficiencies in certain hormones affect mood.

Scientists at the University of California Los Angeles Semel Institute recently discovered a new chemical, a peptide called hypocretin, directly linked to happiness and alertness. In their study, the scientists monitored patients undergoing treatment for severe epilepsy. “Piggy-backing” on the implanted electrodes from the patients’ treatment, the team monitored levels of hypocretin and MCH (or melanin concentrating hormone) throughout the day at 15 minute intervals. Notes of the patients’ activities were made simultaneously. Patients answered a questionnaire asking about their mood every hour they were awake. In analyzing their data, the scientists discovered that hypocretin was highest when patients experienced “positive emotions, anger, social interactions, and awakening.” In contrast, the MCH was highest during sleep lowest when hypocretin was high.

According to Professor Segel of the Semel Institute, who led the team that made this discovery, “The findings suggest that abnormalities in the pattern of activation of these systems may contribute to a number of psychiatric disorders.” Chemicals that counteract hypocretin are already being developed as sleeping pills, and hypocretin could provide the foundation for a new kind of antidepressant.

Fighting Cancer with Protein P53

Despite the amazing diagnostic technologies, pharmaceuticals, and procedures of modern medecine, cancer still takes the lives of more than half a million people in the US every year. Characterized by the unmediated reproduction and metastasis of tumorous cells, the various forms of the disease have proved difficult to slow and often nearly impossible to cure. Treating cancer usually requires rigorous chemotherapy or invasive surgery, each involving painful side-affects and long recovery periods.

Chemotherapy, while effective, indiscriminately attacks cells that divide quickly. Thus, the fast-dividing cells lining the mouth and intestine as well as the cells that cause hair to grow are also affected, causing an array of side affects. Scientists have been searching for a new way to fight cancer that would only target cancer cells while letting healthy cells function unhindered. A team at University of California, Irvine may have found that method in protein P53, mutated forms of which are implicated in “nearly 40 percent of diagnosed cases of cancer.

P53 is responsible for repairing damaged DNA and causing apoptosis, or programmed cell death, in cells that are damaged beyond repair. In a mutated form, P53 does not function properly, allowing cancerous cells that would normally be destroyed to proliferate. A therapy that reactivated mutated proteins could potentially surpress tumors without causing the nasty side affects of current drugs. Also, since P53 is present in so many cancer cases, a single treatment could be used against many different forms of the affliction. However, since P53 proteins “undulate constantly, much like a seaweed bed in the ocean,” sites where medicinal compounds could bind are difficult to locate.

The UCI team had to reach across disciplinal boundaries, enlisting computer scientists, molecular biologist and others to find a usable binding site. With the help of molecular dynamics, the group constructed a simulation of P53’s movements, eventually locating a transient site that could bind with stictic acid, one of forty-five small molecules they tried. Unfortunately, stictic acid is not a viable compound for pharmaceuticals, but the scientists at UCI think that other small molecules with similar characteristics will likely have similar effects and make effective treatments.

Researchers Harness Natural Painkillers with Electric Stimulation

The human body creates an analgesic called endogenous morphine, or endorphins, that are released in response to intense stimuli such as exercise, excitement, pain, and orgasm. These painkillers are endogenous opioid peptides originating in the pituitary gland, brain, and spinal cord that function as neurotransmitters, blocking pain and creating a sense of well being upon release. They are partially behind “runner’s high”, which occurs after continuous, strenuous exercise. Released endorphins allow a runner to surpass what would otherwise be their physical limits, as well as creating a sense of euphoria and happiness (a similar euphoria one experiences when ingesting opiates). Generally speaking, the feelings endorphins cause exist to tell us that we are doing a good thing – like eating food and having sex – and to encourage us to keeping seeking those things out.

It is the chemical’s analgesic properties, however, that are of particular interest to scientists at Michigan University led by Alexander DaSilva, who have successfully used a technique called transcranial direct current stimulation, or tDCS, to catalyze the release of endorphins. In this procedure, a tiny amount of current (2 milliamps) is applied to the brain, altering the behavior its component neurons. Previously, a similar procedure has been used to alter the speed of neuronal reactions and neuroplasticity – making a person able to react and learn faster. The Defense Advanced Research Projects Agency has used this process to “speed up the training of military snipers”.

In this case, tDCS caused the release of endogenous m-opioids (a type of endorphin) when electrodes were placed over the motor cortex. In the researchers’ study, the pain thresholds of test subjects increased significantly, though certain types of pain – such the kind caused by migraines – were not mediated. The scientists think that with repeated use, tDCS could address migraine pain as well.

If further study reveals this method of releasing natural painkillers to treat chronic pain to be viable, doctors could “decrease the use of opiates in general, and consequently avoid their side effects, including addiction”, says DaSilva. At the moment, the researcher caution that more analysis is necessary before tDCS can be used as treatment for chronic pain. In other words, don’t go out and buy a tDCS kit for that backache.


Odd Little Species Survives Without Sex

Of the two million know species on Earth, only about two thousand reproduce entirely asexually. Scientists think this is because organisms that reproduce without sex – which provides healthy genes from one parent that act as a template to repair mutated genes, leading to “theoretically healthier offspring” – are unable to mitigate the deleterious effects of gene mutation, which leads to their extinction. The bdelloid, a tiny, all-female, sea creature with a name that means “leechlike” for the way it moves, however, has survived for tens of millions of years without sex. In fact, they have diversified into more than four hundred species.

Researchers at the Marine Biology Laboratory in Woods Hole, MA wanted to find out why the bdelloid had avoided extinction, so they zapped some of the creatures with gamma radiation, which breaks up DNA. Oddly, the bdelloids did not succumb to the exposure even as the scientists pushed the radiation levels far past what would naturally occur on earth. When the mystified biologists examined the bdelloids’ DNA, they discovered that an early mutation had copied the entire genome, giving each organism four copies as opposed to the common two, which allowed it to repair severely damaged DNA. This mutation turned out to be beneficial for the aquatic creatures because it allows them to survive desiccation, a danger for bdelloids because of their transient underwater habitats.

More recently, scientists at the University of Cambridge published a paper in the journal PLoS Genetics recounting their discovery that about ten percent of the bdelloid’s genome is composed of alien DNA amassed through the consumption of bacteria, fungi, and algae. These foreign genes become active when a bdelloid dries out, and are thought to be partly responsible for the creature’s incredible ability to survive dehydration. Those same genes might also be behind “powerful antioxidants that protect bdelloids from the by-products of drying out”.

Evolutionary biologists are hopeful that a better grasp of the mechanisms that allow bdelloids to survive will lead to much greater discoveries such as how sex evolved. Matthew Meselson, a geneticist at Harvard University, said in an interview with LifeScience that “being able to understand how animal cells can be so resistant to radiation may be of some interest in understanding how [cancer, aging, and inflammation, of which DNA damage and repair are factors] might be inhibited in human cells.” Further experimentation could uncover new treatments that prolong life or fight cancer.

Mouse Stem Cells Become “Grandparents”

Copyright: Anne Burgess

Recently, researchers at Kyoto University in Japan were able to induce stem cells of rats to become viable eggs, which were then implanted in surrogate mothers. The resultant offspring were fertile, anatomically intact rats that were bred for additional generations, their ancestor being only a cell in a petri dish. This discovery has excited scientists the world over because it marks the first step towards making eggs for infertile humans or gays and lesbians.


The scientists at Kyoto began by taking female embryonic cells and “induced pluripotent stem cells”, and then inducing them to become an early form of eggs. Induced pluripotent stem cells (iPSCs) are adult cells that have been reprogrammed to express certain genes that make them effectively embryonic cells. There is some debate as to whether iPSCs differ from embryonic stem cells taken from harvested embryos, but in this instance they acted identically to the conventional stem cells.


The immature eggs, called “primordial germ-like cells” or PGCLCs, were then surrounded by “female gonadal somatic cells” (cells usually found in an ovary) to create a reconstituted ovary. These constructed ovaries were implanted into surrogate mothers, where the PGCLCs matured into “germinal vesicle-stage oocytes” or early embryos formed during the primary oocyte stage of oogenesis (egg formation), which occurs before birth. The mice that had been implanted with these constructed ovaries eventually gave birth to fertile offspring, which were followed by a few additional generations.


Though scientists have called this discovery a major step forward in reproductive biology, the lead scientist on the Kyoto team, Dr. Hayashi, cautioned: “it is impossible to immediately adapt this system to human stem cells” for a number of reasons scientific and moral. Creating egg cells from stem cells in humans could allow menopausal women to conceive, which brings its own set of moral quandaries as well. Ronald Green, a bioethicist at Dartmouth University, commented on NPR that one had to consider “the commercial possibilities of people selling to infertile people babies produced from George Clooney or Jennifer Aniston.” Evidently, the possibility that egg manufacture might one day be possible has sparked heated debate, but one must remember that it may only be speculation.

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