A Mobile Bloomsday Feast

In this blog, Molly Gale Hammell celebrates two "holidays" that fall on June 16th: Transposon Day and Bloomsday.

First of all, I’d like to wish a very Happy Transposon Day to all of you! And a Happy Bloomsday to those who celebrate, as well!

It was just a few years ago that I was attending the 2019 CSHL Retroviruses Meeting and heard a lovely keynote talk from Professor Jeremy Luban of UMASS Med.  Giving that talk at CSHL, just down the road from the McClintock building, Professor Luban reminded us all that Transposon Day (Barbara McClintock’s birthday) was coming up and should be celebrated widely by the many fields impacted by McClintock’s work.  This was particularly relevant for a meeting on retroviruses given the wonderfully long and complicated evolutionary relationships shared between certain retroviruses and retrotransposons. Indeed, both fields are indebted to the original McClintock discovery of mobile genetic material as part of the larger body of her work that we celebrate today. Perhaps less widely known would be her discovery of chromosomal crossover during meiosis and the breakage-fusion-bridge cycle underlying aneuploidy. There’s a common thread through all of these discoveries, which is the movement of DNA between chromosomes – whether through the exchange of sister chromatid material, repair of broken chromosomes, or self-mobilization of transposons.

Transposon Day also happens to coincide with Bloomsday, a celebration of the Irish novelist James Joyce.  Joyce’s novel, Ulysses, takes place on a single day, June 16th, following protagonist Leopold Bloom around Dublin. Joyce’s Ulysses takes its structure from Homer’s epic Odyssey but follows, instead, the adventures of one ordinary day in the life of an ordinary man. The novel represents a landmark of modern fiction, or in the words of T.S. Eliot, “the most important expression which the present age has found.” It stands to remind us of all that is epic and grand in our own everyday lives.

Today, Bloomsday feasts are celebrated with menus that recall the meals shopped for, cooked, and eaten during Leopold Bloom’s long day. Breakfast might start with a fried pork kidney, lunch with a gorgonzola sandwich and a glass of burgundy, followed by a dinner of sliced liver and mashed potatoes. Scattered throughout the day are snacks of seed cake, fat peaches, shamefaced pears, and chocolate bars.

I invite you all to unite these two celebrations by raising a toast to transposons, and the way these genetic elements have contributed to the foods in a Bloomsday feast.  For example, whether your favorite burgundy wine is a crisp Chardonnay or a dry Pinot Noir, you might be surprised to learn that transposable elements are a major source of the polymorphisms that distinguish these related wine grapes. You might pair, as Bloom did, your glass of burgundy with a gorgonzola sandwich, noting that the fungus giving gorgonzola its blue-green color, P. roqueforti, includes stretches of DNA flanked by retrotransposons and shared via horizontal gene transfer with many other species in the Penicillium clade. You might follow Molly Bloom’s lead, with a snack of ripe peaches and pears, noting that the closest relative to the peach tree is actually an almond, not other stone fruits nor the much more distant pears.  Here, transposons have played a major role in diversifying the almond/peach genomes, and may even explain the sweet kernel phenotype that distinguishes almonds from other stone fruit pits.

Let us know whether you might be toasting this day with a glass of burgundy, a gorgonzola sandwich, and some ripe peaches. Or can we devise a new cocktail/mocktail that properly celebrates this momentous day? Perhaps a twist of Sicilian blood orange in a classic Negroni as we toast, “Yes, I will yes.”

Molly Gale Hammell

Molly Gale Hammell is a researcher based at the Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory.

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