Snippets from Science

A problem with finding a vaccine for the flu virus is that there are almost a hundred different “strains” of influenza virus. This is because proteins forming the outer coat of the virus are subject to frequent mutation. In the March issue of Nature Structural and Molecular Biology, two studies report the production of human antibodies that target an area of the virus’s surface that does not change. This raises hope that in the near future scientists will develop a single vaccine containing antibodies that are effective against most strains of flu virus. (Scientific American, May, 2009)


Something to ponder:  Since the 1980s, evidence has been accumulating that our brains make decisions about what action to take fractions of a second before we are conscious of the action taken. Consider a person hiking a trail when a large snake slithers out of the brush in front of him. He subconsciously reacts by jumping out of the way as stress hormones are released into his bloodstream. A fraction of a second after these events occur, he becomes aware of what happened. The big question is how much subconscious decision making occurs in the brain before we initiate what we think is a conscious choice?


Ever hear of microscopic motors? Or molecular engines? They exist! Plant and animal cells have groups of molecules that provide movement. In fact, constant motion occurs within all our cells. For example, hair-like extensions of some cells have internal motors that cause the hairs to flail away in a coordinated manner. These extensions are called cilia or flagella, and their function is either to move the cell itself or move substances over the cell’s surface. An example can be found in our lungs where ciliated cells are constantly clearing mucus away so oxygen can diffuse into the bloodstream. Another example is the wriggling motion of sperm cells. These cells are powered by a molecular motor that causes internal filaments to slide back and forth over one another, creating a rhythmic wiggle in their tails that propel sperm from place to place—maybe even to an egg. The average human body is conservatively estimated to contain 10 trillion cells, each depending on internal motion for its life. When intracellular motion stops, human life stops as well.


At the ends of our chromosomes there are long stretches of non-coding DNA that prevent their ends from accidentally sticking together during cell division, which would disrupt the process. These chromosome ends are called telomeres. Each time a cell divides, a short length of a telomere is used up (or lost). As cells age, the telomeres get shorter and shorter. In culture a human cell divides about 125 times before death. This means that cells are “programmed” for senescence and death after so many divisions, and that telomeres play a prominent role in aging. Cancer cells somehow escape death by telomere loss, and can divide indefinitely. This quality greatly complicates cancer treatment.


An electron microscope allows scientists to peer inside cells. The Philips 300 Transmission Electron Microscope was theoretically powerful enough to enlarge a penny to a diameter of five miles.