Female fireflies have long known that the best romances are with a male firefly that offers the most nourishing and largest "nuptial gift" - a protein-packed capsule of sperm that is rich with egg-producing and life-extending nutrients for the female. However, the molecular composition of nuptial gifts has remained unknown even though the gifts offer benefits that keep a female firefly coming back for more. Now, new research at Tufts University, in collaboration with MIT scientists, reveals the mystery of this special package, offers the first peek into the content of firefly gifts, and sheds new light on post-mating sexual selection. The findings were published online on December 22,2016 in Scientific Reports. The open-access article is titled “Molecular Characterization of Firefly Nuptial Gifts: A Multi-Omics Approach Sheds Light on Postcopulatory Sexual Selection.” Focusing on the common Eastern firefly, Photinus pyralis, also known as the Big Dipper, researchers found more than 200 identifiable proteins within the nuptial gifts. The proteins' diverse functions can be inferred based on their resemblance to proteins known from other insects. Some are structural proteins that make up the fabric of the nuptial gift, while others are enzymes that may help unpackage the gift, allowing its contents to be released. Still other enzymes appear to be a biochemical way of nudging the female to lay more eggs. The researchers also identified enzymes that might enhance a male's paternity success by expediting sperm storage or by increasing the ability of male sperm to fertilize the female's eggs. Corresponding author Sara Lewis, Ph.D., Professor of Biology in the School of Arts and Sciences at Tufts University, said new technologies enabled the research group to decipher exactly what's inside these amorous bundles.
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