Having been a science teacher, I know how hard it is to engage young minds in the classroom, even when the kids are bright and enthusiastic. School science is traditionally perceived as dull and boring, and it takes a special skill to spice up science lessons so that they capture pupils' imagination.
I was, therefore, pleased to read about a project which not only turned two high-schoolers on to science, but got their names on an influential paper in the very prestigious journal Cell.
Five years ago, high school students Joe Gross and Jake Falbo paid a visit to Graham Hatfull's lab at the University of Pittsburgh, in the hope of getting some experience in scientific research.
"Why don't you go out and disover some new viruses," Hatfull told them. "All you need to do is go and look under a rosebush and you'll find a phage that's unlike anything anyone's ever seen before."
A phage (short for bacteriophage, or 'bacteria-eater') is a virus that infects bacterial cells. Phage lambda (above) is probably the best characterized of all the viruses known.
The virus is the simplest form of life, but it is infinitely complex. Actually, standard textbooks do not classify viruses as living things, because they can only reproduce by infecting a host cell and using the machinery of that cell to replicate its DNA and synthesize its proteins.
Viruses exist in every habitat on Earth, from the Sahara desert and Antarctica, to hot acidic springs and hydrothermal vents on the sea floor.
Logic dictates that the smaller an organism, the more varieties of it there are, and microbiologists are only now beginning to grasp just how diverse viral life is. There may, for example, be over a million species of virus in a kilogram of mud, and more species of virus in a single millilitre of water than there are all other species combined.
So numerous are species of virus that the project in which Gross and Falbo were enrolled led to the indentification of no less than 40 previously unidentified phages.
It would appear that the vast majority of genetic material resides in viral genomes. It has long been known that a significant proportion of the human genome consists of viral DNA, and recently developed methods for the en masse sequencing of viral DNA have shown that approximately half of every viral genome consists of hitherto unknown genes.
Furthermore, because of the nature of their life cycle, viruses are probably responsible for generating the diversity of genes found in all organisms today. Upon infecting a cell, a virus can combine its own genes with the host genome, producing novel gene combinations or even entirely new genes. These new genetic units are then shuttled between organisms in subsequent viral life cycles.
The promiscuity of viral recombination makes viruses a driving force for Darwinian evolution, with host cells acting as a melting pot in which new mutations and gene combinations are stirred up. Host cells seem to act as a reservoir of genetic material from which viruses can pick and mix, and some geneticists are beginning to look at all viruses as a super-organism consisting of one massive pool of genetic information.
Pingback: Diverse Classroom Design