A rolling stone supposedly gathers no moss, but Israeli and German scientists who collect this ancient carpet-like plant claim it provides clues for better programming of stem cell development. Dr. Nir Ohad of Tel Aviv University's plant sciences department and Prof. Ralf Reski of the University of Freiburg have discovered a new use for the "Polycomb group" proteins (PcG) found in moss. They recently reported their research - funding by the German-Israeli Foundation - in the journal Development.
Even though it is just a green plant, moss shares basic development processes with humans. "We may not have found the switch that turns stem cells into tissue," says Ohad, "but we have found a key component that makes this switch work." Embryonic stem cells can be turned into virtually any type of body cell. The research has direct implications for the study of plant biology, especially to provide basic information on how the plant body and reproduction are regulated. It also gives science a tool to control tissue specification, timing of reproduction and the development of traits in seeds that serve as the source for human and animal feed.
In their new paper, the researchers describe an ancient mechanism that alters the way DNA organizes inside the cell nucleus, which in turn affects gene expression. This finding has important implications in stem cell therapies that can go awry if implanted stem cells aren't reprogrammed properly. The researchers examined the PcG complex's "central regulatory function" and how it programs an organism's development. Insights from this research have implications for plant and human development alike and with time could be applied to cancer research, says Ohad, as tumors can result when the cellular mechanisms of stem cell differentiation are defective or impaired; this can lead to the misregulation of the genetic code and the breakdown of a healthy cell. He adds that the "switch" that ensures the proper development of the organism emerged early in the evolution of all organisms with a nucleus and organized DNA, long before animals and plants evolved into vastly different species.
In some scientific disciplines, mosses are considered less advanced organisms. But Ohad calls mosses highly adaptive organisms, which after 450 million years are still with us. "The original moss - Physcomitrella patens - hasn't endured all these years, but its descendents have," he says. He adds that the biology of moss is similar to the biology of other ancient creatures, like crocodiles and flies, helping scientists understand the evolution and function of basic biological mechanisms. The researchers believe that the basic function of the mechanism in moss is in regulating cell differentiation, just as stem cells differentiate and "decide" to become a leaf or flower, for example. "As they develop, stem cells go from having an undefined function to a specific one," he concludes. "If you don't know how to manipulate the type of tissue you want to modulate, replace or heal, you might cause the malfunction of another type of tissue."
CAN YOU FIND IT IN YOUR HEART?
Just half of the 722 Britons recently interviewed for an anatomy study knew where their heart was located, say researchers at Kings College. Only a third were able to identify the correct position for lungs, according to the study published in MMC Family Practice. The researchers questioned members of the public and patients at three hospitals in London. The results were no better than those of a similar study conducted in 1970, lead researcher John Weinman said. Study participants were shown outlines of a male or female body with one organ in the correct place and the rest of the organs misplaced. Overall, 85.9 percent of those interviewed knew where the intestines belonged while 80.7 percent knew where the bladder belonged. Based on the study, healthcare professionals should not assume patients are knowledgeable even about those organs in which their medical problem is located, Weinman said.
Americans may die as octogenarians, but their paid and published obituaries increasingly show them looking much younger. Some critics charge this is an example of ageism. A recent study at Ohio State University that looked at photographs published in The Plain Dealer of Cleveland found that the number of obituary photographs showing the deceased at a much younger age more than doubled between 1967 and 1997. And women were more than twice as likely as men to have a youthful obituary photo, said OSU social work Prof. Keith Anderson, who coauthored the study.
Anderson said either spouses or adult children of the deceased chose the photographs. They understandably wanted a photo that they thought represented their spouse or parent at his or her peak, he said. But what is remarkable is how we as a society define these peak years.
In 1967, about 17 percent of the obituary photographs surveyed in the daily newspaper were "age-inappropriate" - meaning they showed the deceased at least 15 years younger than when they died. By 1997, the rate (among 400 obit photos) had increased to 36%. "Obituaries and their photographs are one reflection of our society," wrote Anderson in the study published in Omega: Journal of Death and Dying. "Our findings suggest that we were less accepting of aging in the 1990s than we were back in the 1960s."