A n A fternoon with P rofessor G eorge B entley B S J By: Kuntal Chowdhary, Harshika Chowdhary, Manraj Gill, Atiriya Hari, Rhea Misra, Jess Evaristo, Ali Palla This year, BSJ had the pleasure of interviewing Professor George Bentley. Professor Bentley’s research interests include avian reproductive biology, neuroendocrinology and behavior. As an ornithologist, Professor Bentley has completed extensive studies on song control systems. Endocrine and behavioral responses to stimuli such as vocalizations have been documented for decades, yet the “black box” approach has been applied to any explanation of the brain’s involvement. Any external stimulus has to be first monitored by and then responded to by the brain for the stimulus to have a physiological effect. To affect the reproductive axis, these stimuli must influence the gonadotropin-releasing hormone (GnRH) system. Much of Professor Bentley’s recent work has been on the recently identified neuropeptide, gonadotropin-inhibitory hormone (GnIH). BSJ had the opportunity to learn more about the role of stress in the GnRH system. BSJ: How did you get involved in your research in stress regarding birds? Prof. Bentley: I started my research career looking at what is called “photoperiodism” -- how birds and other mammals respond to changes in day length and how their reproductive system changes. I was interested in how this phenomenon occurs on a basic level -- how birds change from breeding to a nonbreeding status. I ended up working in a lab in Seattle that focused on the role of stress influencing different behaviors within discrete stages of the annual breeding cycle. I am not a stress biologist, historically. When I moved here, because of my interest in regulation of photoperiodism in seasonal breeding, I started working on a neuropeptide called Gonadotropin-Inhibitory Hormone (GnIH), which was discovered in Japan by a friend of mine, Kazu Tsutsui (Kazuyoshi Tsutsui). We started working on GnIH and we knew nothing about how peptides are regulated and their associated regulators. We initially thought this discovery was very exciting because this inhibitory peptide could explain or could be part of the mechanism with which birds and mammals terminate (switch-off) reproduction at the end of the breeding system when their gonads regress. Turns out that was not the case. We started to look at different hormones that might modulate the expression of GnIH. The obvious thing to look at was the HPA (Hypothalamic-pituitary-adrenal) axis. We wanted to see if stress hormones could modulate the GnIH. A graduate student of mine, Becca Calisi (Dr. Rebecca M. Calisi-Rodriguez), started by doing some work on stress at different times of the breeding season in house sparrows. We saw that GnIH was regulated differently at the start of the breeding season as compared to the end of the breeding season. We caught these birds from the wild and simulated a predation event -- we catch them, put them in a cloth bag, and hang up them for an hour. While the birds are sitting there in the bag, we assumed that they perceive that they would be eaten by predators and this elicits a strong stress response and allows us to see how GnIH was regulated. We found that it was regulated more at the start of the breeding season than later in the breeding season. This makes sense, as at the start of the breeding season, breeding can be delayed or advanced depending on what kinds of supplementary cues these birds are receiving. The drive of changing day length can switch on the reproduction system, so the birds do not enter full reproduction until everything is just perfect. Now in birds, we have been historically limited in terms of the tools we have to manipulate at the level of the gene. We first have to clone the gene. Daniela Kaufer and I, we were talking about collaborating and see how GnIH can respond to stress. One of her graduate students, Liz Kirby (Elizabeth Kirby), did a lot of this early work and culminated in a 55 • B erkeley S cientific J ournal • S tress • F all 2013 • V olume 18 • I ssue 1