In the first stage, even before meiosis technically begins, the genetic material within germ cells-the cells that eventually develop into eggs or sperm-is duplicated. Natural meiosis occurs in several highly choreographed stages, each of which happens in rapid succession. As you probably remember from high school biology, this is all part of an intricate intracellular dance called meiosis. Sexual reproduction, shorn of its more romantic and prurient elements, is essentially about mixing and combining genetic material, a process that happens both immediately before and during fertilization. Instead, he simply manipulates the basic mechanics of oyster sex. He doesn’t insert genetic material-let alone genes from another species-into his oysters. Let’s start by pointing out that Allen’s triploids aren’t what we would typically call genetically modified organisms. To understand how it worked, we’re going to have to have a simplified version of “the sex talk”. “The chemical didn’t work so well on salmon,” he says, “so we decided to give it a try on oysters instead. To do so, triploids looked like a promising approach.Ī common way to induce polyploidy in plants is to treat the growth tips of the plant with a toxin called cytochalasin, so Allen began to apply the chemical to the fertilized eggs of his fish subjects. A faster growth rate would also have made it easier to raise salmon in the cold waters of Maine. So Allen hoped to achieve a similar effect on salmon yield. Triploid blueberries, for example, are about twice as large as regular blueberries.” Therefore, you get what they call ‘polyploid gigantism’. As the DNA content of the cell increases, so does the size of the cell. “In plants,” Allen says, “the benefit of polyploidy is usually a larger plant or fruit. Polyploidy also frequently increases yield. Botanists induce polyploidy in plants to produce many varieties of seedless fruits, like bananas, grapes, and watermelon. Einkorn wheat, one of the oldest varieties, is a normal, diploid plant, while durum, or macaroni wheat, is tetraploid, and common wheat, or bread wheat, is hexaploid. In fact, the characteristics of some of the world’s most important crops may derive from the fact that different varieties may have different numbers of chromosomes. On the other hand, many plants, like blueberries and some redwoods, are naturally polyploid, and agricultural hybridization has induced polyploidy in many others. In humans, for example, polyploidy is a usually fatal condition (although some specialized somatic cells, like heart muscle and the smooth muscle lining our arteries, are sometimes polyploid). Polyploidy-having more than two sets of chromosomes-is relatively rare in animals, largely restricted to invertebrates and a few amphibians and fishes. That’s because induced triploidy had already proven effective at increasing yields in other organisms. “I was working with salmon, trying to do basically the same thing with salmon as we later with did oysters-make triploids.” “It was very early on in my graduate school career,” Allen says. The idea, at the time, was to develop products that would bolster Maine’s then nascent aquaculture industry. The first time Allen invented triploid oysters was in the late 1970s, when he was still a masters student at the University of Maine’s Ira Darling Marine Center. Oyster seed pallets in Samish Bay (Taylor Shellfish) That means they can be harvested earlier, before they’re affected by the diseases that have laid waste to natural oyster populations in places like the Chesapeake Bay and the estuaries of Normandy. The uneven number results in a mostly infertile oyster that, because it doesn’t waste energy producing gametes-eggs and sperm-grows bigger and faster than natural oysters. Allen’s innovation has been to create oysters with three sets of chromosomes. Natural oysters, like humans and most other eukaryotes, are diploid-each of their cells contains two sets of chromosomes, one from each parent. His monster: a sweet, plump morsel called the triploid oyster. Over the past three decades, Allen’s patented innovations in oyster culture have transformed this old-fashioned industry. Frankenstein, in this case, is Standish Allen, currently the director of the Aquaculture Genetics and Breeding Technology Center at William & Mary’s Virginia Institute for Marine Science. Not monsters in the pejorative sense, but man made creatures-the invention of a modern-day Dr. If you slurped down any oysters on the half-shell this summer, you probably didn’t realize they were monsters.
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