How many organisms make you tick, and other questions
Posttraumatic stress disorder is a problem faced by almost 20 million people in our country as a result of trauma that they have experienced. PTSD causes a number of other physical and psychological problems that have been treated with some not very effective drugs for about 20 years. In a paper recently published in Science Translational Medicine on Sept. 16 (https://stm.sciencemag.org/ content/12/561/eabe1717), scientists gave mice traumatic electrical shocks at the same time that a sound was played. Some of these mice were injected with corticosterone immediately after receiving a shock. Corticosterone can affect memory by inducing the release of other hormones. Other mice who were also shocked were not injected with corticosterone. When a different sound was played to mice who received the corticosterone after the shock, they acted afraid even though the sound was unrelated to the shock they had received. This is a kind of PTSD behavior. The mice who did not get the corticosterone injection only showed fear when they heard the sound played just before the shock was given. If the PTSD affected mice were treated with the drug, Rexulti, that is used to treat humans with depression or schizophrenia, they showed fear only when they heard the sound played just before they were shocked.
So, can this drug be used to treat humans who have PTSD? A pharmaceutical company is currently testing the use of Rexulti in combination with another antidepressant drug to treat PTSD. The drug trial is nearing completion and may provide a medical treatment for PTSD that would be a major advance. This study does demonstrate how complicated it can be to develop new drugs for us.
This PTSD study brings to mind efforts to deal with the COVID pandemic. Pharmaceutical companies are working on the development of a vaccine, but we are told a vaccine is not likely to be available for months or even a year or more. There is some progress on this and a U.S. pharmacological company is testing a vaccine on 60,000 people before it will be made available. A worry identified by some recent scientists is a mutation in
COVID-19 that may make it resistant to a new vaccine. Scientists at the Rockefeller University have shown recently that if a vaccine contains two antibodies to the virus, it is more difficult for the virus to survive. However, it was also found that viruses resistant to several antibodies are found in some patients although these variants are rare. This pandemic is a remarkable example of the role and effect of natural selection on our lives and futures.
Life on Venus?
There is a recent paper published in the journal, Nature Astronomy (https://www.nature.com/articles/s41550-0201174-4), that raises questions about the existence of life on the planet, Venus. Astronomers used powerful telescopes to examine the wavelengths of light emerging from the atmosphere of Venus, and to their surprise they found evidence for a gas called phosphine. This gas is thought only to be produced by living organisms. It is produced on our planet by anaerobic bacteria that live in oxygen poor environments like our guts and marshes. Since phosphine is very difficult to make, scientists are speculating that there could be organisms on Venus that are producing this gas. However, while the size of Venus is similar to the Earth, its surface climate temperatures can be as high as 900 degrees Fahrenheit. Its cloudy skies may be a place where some life could exist and be the source of the phosphine. Not all astronomers agree with this hypothesis so this bit of science will be worth watching for several more years.
The microbes, 10 trillion of them, that live in our guts are not the products of our genes, but they are critical for the effective functions of our bodies. Indeed, a recent study of gut microbes (https://science.sciencemag.org/content/early/2020/08/26/science. abd6176.long) found that there are nerves in our gut the affect our appetites and also control blood sugar levels. Indeed, there are so many nerves in our guts that some think of it as another brain. It has been found that some microbes in our gut generate chemicals that are similar to neurotransmitters that our neurons use to communicate with each other. The scientists used mice that had been treated with antibiotics make them almost microbefree. What they found was that the number of gut neurons of these mice were reduced when the microbes did not produce chemicals to stimulate the neurons. These gut neurons regulate the amount of sugar in our blood by communicating with our liver and pancreas. These results could be the basis for treating human diseases like obesity and diabetes. We often think of ourselves as a single being, but science is finding frequently that we are actually a group of organisms that work together to keep us alive and generating new offspring. However, we also harbor organisms like COVID that prefer to kill us off and not join our community. Stay safe and avoid COVID.
Rollin Richmond is an emeritus professor of biology and emeritus president at Humboldt State University. He has worked as an evolutionary geneticist at several universities during his career. (Full disclosure: He happens to be responsible for 50 percent of Times-Standard publisher John Richmond’s genetic makeup.) Questions or comments about this column can be sent to rollinr@ humboldt.edu.