Gro Amdam, associate professor in the School of Life Sciences at Arizona State University, has been awarded two grants totaling the U.S. equivalent of about $1.4 million from the Norwegian Research Council to investigate biochemical factors and social life history properties that can influence aging and longevity in honeybees. Amdam also is with the Department of Chemistry, Biotechnology and Food Science at the Norwegian University of Life Sciences in Norway.
The first study will focus on the molecular properties of honeybee vitellogenin, a protein which, Amdam says, acts at the intersection between social behavior and aging. The second project, to be headed by Amdam’s postdoctoral fellow Siri-Christine Seehuus in Norway, will examine the genetic and endocrine factors, which may determine longevity in diutinus workers, a specialized sub-caste of honeybees.
In a series of previous studies, Amdam has shown that vitellogenin protein affects aging rate and endocrine signaling in honeybees. In addition, separate studies conducted with Robert Page, director of ASU’s School of Life Sciences in the College of Liberal Arts and Sciences, demonstrated that the protein also influences social behavior, longevity and sensory responsiveness.
“Generally, vitellogenin is described as a conserved yolk protein found across a broad range of egg-laying species. The functions of proteins homologous to honeybee vitellogenin therefore have been studied primarily in the context of female reproduction,” Amdam says. “New data from my laboratory suggests, however, that the protein can be active in signal transduction”
Amdam hopes to understand more about the structural and binding properties for the honeybee vitellogenin protein through examination of synthesized protein fragments, combined with crystallography and spectroscopy. Her intention is to unlock how the protein can have pleiotropic effects on honey bee social organization which also may open a window onto mechanisms that enabled honey bee social life to emerge.
Amdam and Seehuus will both exploit the plasticity found in honeybee social life history in their work examining the causal basis of the extreme longevity of honeybee diutinus workers (up to 1 year, in contrast to the normal lifespan of about 2 months). While Seehuus will focus on endocrine regulation, Amdam will study the role of a key social factor, the presence versus the absence of young brood.
“Since sister honeybees can be both short-lived and extremely long-lived, it is clear that diutinus development within a colony is not determined by genetic predisposition,” Amdam notes. “Rather, diutinus bees develop as a function of social change when the young brood (honeybee larvae) is removed from the nest. Preliminary results from my lab in Norway point to a major effect on lifespan of pheromones released by the brood.” Amdam graduate students have found that exposing the workers to brood phermones alone (using synthetics in the absence of actual brood) prompt the diutinus workers to build up particularly large body reserves of proteins and fats which likely have positive effects on survival.
Next, Amdam will study how the dual effects of brood, that is the physiological load of nursing the larvae and exposure to brood pheromones, translate into levels of individual gene- and protein expression, storage dynamics of tissues, and at the level of behavior, food intake and feeding.
Amdam expects that together the planned studies will unravel patterns of interplay, from molecular- to social mechanisms that can govern lifespan in social species.
Amdam has made key discoveries in the genetic, physiological and behavioral mechanisms underlying division of labor, caste development, and advanced understanding around the evolution of social life strategies, including aging, in social insects. Since 2006, her work, primarily using the honeybee as a model organism, has been published in professional journals as varied as Nature, Science, Experimental Gerontology, Proceedings of the National Academy of Science (PNAS), Behavioural Brain Research, Public Library of Science (PLoS), American Naturalist and Advances in Cancer Research. In 2007, Pew Charitable Trusts selected Amdam to be a Pew Scholar in biomedical sciences and she had the distinction of being named “Outstanding Young Investigator” by the Research Council of Norway.
To hear Amdam talk about her research, visit ASU's School of Life Science’s Web page for K-12 audiences, “Ask-a-Biologist”: http://askabiologist.asu.edu/podcasts.