Drosophila Diaries: Ken and Barbie

By Michael Burel

 

The holidays are upon us, people. This is not a drill. While the greatest gift of all during the holiday season is giving rather than receiving, you can’t help but remember how amazing (and admittedly materialistic) it is to receive things from others. “Things, for free?!” Yes, things! For free! Such a life exists even for graduate students who exploit this chance to forgo extravagance in exchange for desperately needed life necessities: Tupperware, socks, food, shelter, social interaction, separation anxiety from work, relief from the dark ends of the seemingly infinite thesis tunnel. You know, the basics.

 

Perhaps one of the most interesting side effects of the holiday season is nostalgia, that wistful remembrance of holidays past. Remember getting that new LEGO set when you were six-years-old? The excitement of unwrapping a new video game? The screech you squealed when you finally got the newest iteration of Ken and Barbie dolls? In fact, it could have been this latter gift that spurred your desire to pursue science, seeing as Barbie herself has pursued over 150 careers in her lifetime , one of the most recent of which was computer engineering. Though her accompanying book I Can Be a Computer Engineer was met with sweeping criticism about Barbie’s reliance on male figures to code her ideas, it nevertheless was an imperative step towards increasing STEM awareness among the highly impressionable toddler set.

 

Quite surprisingly, Ken and Barbie dolls inspire not just receptive to-be scientists, but also the I-already-have-my-PhD-and-receive-federal-funding ones. In this segment of Drosophila Diaries, I’ll explore my favorite fruit fly gene name to date: ken and barbie.

 

You’ve heard it over and over again in your biology classes: Fruit flies provide an exceptional paradigm for studying gene function. They replicate quickly, possess evolutionarily conserved but simplified anatomy and cell behavior, and provide robust genetic tractability. It’s no wonder, then, why scientists in the early 1990’s used Drosophila spermatogenesis as a means to uncover novel genes that govern stem cell identity, mitosis, meiosis, morphogenesis, and cell-cell interactions. Within a single tissue, all of these processes can be empirically observed and probed ad nauseam, providing an unprecedented means to discover new genes (and subsequently name them weird, functionally-specific things).

 

In 1993, Diego Castrillon and colleagues published in Genetics a P-element mutagenesis screen that revealed mutations altering normal tissue function in the fruit fly testis. P-element mutagenesis screens offer some pretty nice incentives that expedite the genetic screening process. It involves a transposable element (those jumpy genes in our genome that plop in and out of place) inserting itself into random genes and disrupting their function by perturbing DNA sequences. P elements can be quickly mapped to genomic locations, used to make new mutant alleles of the gene it settled into, and exploited to clone out surrounding DNA and recover molecular information about its genetic geography.

 

Castrillon et al. generated over 8,000 fly lines that contained P elements plopped into random genomic locations. Of these, over 1,900 flies were screened for altered spermatogenesis; ultimately, they isolated and characterized 83 fly lines in which males couldn’t produce new progeny. These 83 fly lines were subdivided into seven different phenotypic classes, the last of which was a rather peculiar one: “sperm transfer defects.”

 

Male flies with sperm transfer defects essentially had difficulty in the final parts of copulation, the transfer of sperm to females. For example, male parts were sometimes in the wrong place, such as in twig mutant flies where the anal-genital plate was incorrectly rotated. Others, like the pointed mutation, had normal levels of motile sperm stored away but just couldn’t get them from point A to B. These two mutant flies had the right “tools” so to speak, but the final mutant fly in this phenotypic category apparently forgot its toolbox altogether. Flies mutant for one P-element insertion completely lacked external genital. In opening up the male flies, the researchers observed all the internal sexual parts were intact…but where were the outside parts? Whether plagued by holiday nostalgia or not, the scientists knew exactly what to name this new mutant gene: ken and barbie, after the dolls that also do not possess external genitalia.

 

As you’re wrapping up that gift for your brother or sister, niece or nephew, next-door neighbor, or local toy drive, consider two things: (1) how will this gift impress upon the next generation to enter into STEM fields, and (2) how will this gift inspire the hilarious naming of currently undiscovered genes and let scientists leave their comedic mark for decades to come. And if you’re in search for gift ideas for your fellow science enthusiasts, Scizzle has you covered.  ‘Tis the season.