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Laboratory of Fish Endocrinology and Environmental Physiology

Laboratory of Fish Endocrinology and Environmental Physiology. Hawaii Institute of Marine Biology School of Ocean and Earth Science and Technology University of Hawai ` i. The People. Tetsuya Hirano Three postdoctorals Andy Pierce Lori Davis Marc Metien Four graduate students Eli Witt

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Laboratory of Fish Endocrinology and Environmental Physiology

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  1. Laboratory of Fish Endocrinology and Environmental Physiology Hawaii Institute of Marine Biology School of Ocean and Earth Science and Technology University of Hawai`i

  2. The People • Tetsuya Hirano • Three postdoctorals • Andy Pierce • Lori Davis • Marc Metien • Four graduate students • Eli Witt • Jason Breves • Anna Kosztowny • Masatomo Yoshioka

  3. The Neuroendocrine System: the interface between the organism and its environment • How do fish adapt to changing environmental conditions? • How do fish exploit resources? • How do fish optimize their use of energy? • How do fish optimize the timing of important events and processes? • How do human activities impact the biology of fish?

  4. Why HIMB • Availability of pristinely clean warm seawater • Proximity to California and Japan • Access to coral reef and coastal fish species • Association with SOEST • I/R appointment

  5. Current Projects • Osmoreception • Endocrine disruption • Regulation of growth, development and osmoregulation, and energy investment into those processes • Teleost fish • Elasmobranch fish • Regulation of egg development • Regulation of immune response • Fishmeal-free fish feeds

  6. Funding • EPA • Two NSF • Four USDA CREES • ~ $8-9 hundred thousand Output • ~ 150 peer-refereed publications • Twenty-eight previous postdoc’s and graduate students • Over eighty undergraduate students • A substantial number of high school students

  7. Regulating Salt and Water Balance • Involves a large portion of the neuroendocrine system • Involves sensors that monitor, and in turn, regulate salt and water balance

  8. Osmoregulation: The Challenge! “One of the most troublesome of all problems in clinical medicine is maintenance of adequate body fluids and proper balance between the extracellular and intracellular fluid volumes in seriously ill patients.” Arthur C. Guyton

  9. Osmoregulation typically accounts for 25-50% of the non-swimming energy budget in fish. • Hormones and other chemical messengers of the neuroendocrine system facilitate the adaptation of euryhaline fish to changing salinities by regulating the activity of osmoregulatory mechanisms.

  10. Hyposmotic Hyperosmotic Why osmoregulation? THE TEXTBOOK: When exposed to an osmotic challenge, cells burst or shrivel: THE REALITY: Under physiological conditions cells adapt to changes in extracellular osmolality by adjusting intracellular solute composition to regulate their volume.

  11. The real reason for osmoregulation: “Life is all about the interaction between molecules.” Linus Pauling

  12. Importance of Osmoregulation • The functional structure of macromolecules is maintained by weak forces • A stable internal osmotic environment is essential to the maintenance of the structure, and therefore, the function of macromolecules. (Modified from Neil Campbell, 1998)

  13. Sites of vasopressin synthesis Site of vasopressin secretion Little is known about the neuroendocrine mechanisms that control osmoregulation. The Reason: the complex structure and arrangement of most osmoreceptors Brain Pituitary gland

  14. RPD The prolactin cells of the rostral pars distalis of teleost fish provide an excellent model for studying osmoreception. • Conservatively, 95-99% of the rostral pars distalis is comprised of prolactin cells.

  15. Tilapia Prolactin Cells Appear To Be Osmoreceptors Extracellular osmolality Rostral pars distalis Prolactin cells (osmoreceptors) Prolactin

  16. Methods 1. Dissection RPD 340 nm FURA2 505 nm 380 nm FURA2----Ca2+ 4. Application to chamber AM ester cleaved by natural esterases FURA2 3. Cell dispersion 2. Overnight Pre-incubation FURA2----AM FURA2----AM Measuring Intracellular Free Calcium

  17. Relationship between extracellular osmolality, cell volume and prolactin release. 500 400 300 200 100 PRL (% change) 50 110 40 105 30 Cell volume (% change) 100 250 95 300 350 90 400 Osmolality (mOsmolal)

  18. Extracellular osmolality Summary • The rise in prolactin release in response to a decrease in extracellular osmolality is closely tied to an increase in cell size. • Hyposmotically-induced prolactin release is dependent on the inward movement of extracellular Ca2+. 3) Extracellular Ca2+ entry • increase in cell volume PRL Cell • Inward movement of H2O PRL release

  19. Thank You

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