Liu, N., & Lasko, P. (2015). Analysis of RNA Interference Lines Identifies New Functions of Maternally-Expressed Genes Involved in Embryonic Patterning in Drosophila melanogaster. G3 (Bethesda, Md.), 5(6), 1025–1034. http://doi.org/10.1534/g3.115.017517
There are certain eternal rhythms that calm and inspire us as we move through life. Think of the ocean: whether in difficult times or in joyful moments, it is soothing to hear the rhythm of the waves breaking on the shore, through day and night, a rhythm that stretches back through time, which predates, and will outlast, all of our human activities on this planet.
Today I would like to talk about another soothing, natural rhythm that will likely outlast us all: the publishing of solid, reliable papes about Drosophila germ cells by Paul Lasko’s lab at McGill University. Just as the waters thaw and the buds emerge each spring, so too does the trustworthy data runneth from the papes of Lasko. Today’s Sick Pape is just one of the latest of the deeply calming publications to break its data waves on the shores of PubMed.
Since 1988, Lasko and his crew has studied germ cells. Germ cells, which give rise to sperm and egg, are among the most kaleidoscopically psychedelic cells in the body, because they literally connect the generations. Think of it this way: all of the cells in your body began as one cell, which once lived inside the ovary of your mother. Yet this cell, like all the cells in her body, came from a single cell in her mother. And so on, back to the beginning of life. In the words of Edmund Wilson (1900), who wrote the first textbook on Cell Biology, “Life is a continuous stream...the individual body dies, but the germ cells live on...”
During embryonic development, the immortal germ cells are specified from their mortal neighboring cells. This is analogous to a bee colony selecting a queen: all the other cells in the animal will function as worker bees, while the germ cells sit like a queen, doing nothing but giving rise to the next generation. And, like most biological phenomena, the molecular mechanisms of germ cell development were largely worked out using large genetic screens in the fruit fly in the late 1970s and early 1980s. Specifically, to identify genes involved in germ cell development, many thousands of mutant fly lines, each with a mutation in a single gene, were screened for defects in germ cell development.
Paul Lasko’s early research focused on several of the genes that were identified in such screens (including Vasa, which we’ve mentioned before). Now, three decades on, one of his lab members, Niankun Liu, has continued this logical, time-tested approach to identify additional genes involved in germ cell development. Using a dope comprehensive database of Drosophila gene expression, these folks found a list of 51 mRNAs that are localized to the site of embryonic germ cell formation. They then used RNAi to systematically knock down each gene on the list, and test for defects in germ cell development. What’s more, they even took the highly commendable step of actually testing which of their RNAi lines works, so that they have a sense of which of their negative results are actually trustworthy. In the end, they come up with a handful of interesting new genes to follow up on, including a ubiquitin ligase of unknown function (check back in 30 years).
These may sound like modest results, but remember that systematic genetic screening is what got us where we are in the first place, and, just like the ocean, genetic screening will never get old. As autumn tightens its iron grip on the now barren landscape around us, there is nothing better than kicking back with a tasty mulled cider of a pape that you can truly rely on.