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Snapshots of Life: Stronger Than It Looks

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Structure of dental enamel

Credit: Olivier Duverger and Maria I. Morasso, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH

If you went out and asked folks what they’re seeing in this picture, most would probably guess an elegantly woven basket, or a soft, downy feather. But what this scanning electron micrograph actually shows isn’t at all soft: it is the hardest substance in the mammalian body—tooth enamel!

This exquisitely detailed image—a winner of the Federation of American Societies for Experimental Biology’s 2015 BioArt competition—was generated by Olivier Duverger and Maria Morasso of NIH’s National Institute of Arthritis and Musculoskeletal and Skin Diseases. Before placing a sample of mouse dental enamel under the microscope, they treated it briefly with acid in order to reveal how the tissue’s mineralized rods are interwoven in a manner that gives teeth both strength and flexibility.


DNA and the Roots of Hair Roots

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An Asian family (adult male and female and two adolescents, male and female) sitting around a coffee table playing a board game

Researchers have discovered one genetic recipe for this family’s thick dark hair.
Source: National Cancer Institute, NIH; Bill Branson, photographer.

It’s intriguing to find the roots of physical traits: skin color, height, and those weird tufts of hair on Uncle Mike’s ears. We’re all curious to know why we look the way we do. But new technologies are allowing us to discover the precise genetic roots of human traits that vary across the world. Variations in our DNA have helped us resist diseases and adapt to different climates and foods, enabling us to colonize just about every environment on the planet.

Recent studies have pinpointed variations responsible for lighter skin in Northern climates (such as SLC24A5 [1]) and the ability to tolerate milk sugar (lactose) in adulthood [2]. But a new NIH-funded study of a gene variant that arose in China adds a fascinating wrinkle—the use of a mouse model to help understand a potential human advantage [3]. (Regular readers will note that last week in this space I wrote about how mouse models could sometimes be misleading—this week the mouse is a champion!)