Poster Abstracts

2011 Integrative and Comparative Biology  
Cloning and expression of mTOR signaling components in the Y-organ of decapod crustaceans The metazoan target of rapamycin (mTOR) is a highly conserved protein kinase controlling cell growth in multicellular animals. Molting in crustaceans is regulated by ecdysteroids produced by a pair of molting glands (Y-organs, YO) located in the cephalothorax. During premolt, YOs hypertrophy and increase production of ecdysteroids. Here we focus on the role of mTOR signaling in YO growth. We hypothesize
more » ... t up-regulation of mTOR signaling is necessary for YO hypertrophy and that molt-inhibiting hormone (MIH) down-regulates mTOR signaling in the YO of intermolt animals. cDNAs encoding Akt (protein kinase B), mTOR, Rheb, and p70 S6 kinase (S6K) were cloned from blackback land crab, Gecarcinus lateralis. and European green crab, Carcinus maenas. The G. lateralis clones were obtained by RT-PCR and RACE. Degenerate primers for G. lateralis were used in nested RT-PCR. We isolated partial cDNAs encoding 664bp of the mTOR kinase domain, 547bp of the Akt pleckstrin and kinase domains and 679bp of the S6K N-terminal kinase domain. Identity/similarity of each sequenced gene to its human ortholog was, for mTOR 75%/90%, for Akt 52%/73% and for S6K 76%/88%. The C. maenas clones were derived from ESTs. Partial cDNAs encoding 1624bp of the mTOR FAT domain, and an additional 1766bp of ORF and 3'UTR for mTOR, 728bp of the Akt pleckstrin and kinase domains and 869bp of the S6K N-terminal kinase domain. Identity/similarity of each sequenced gene was, for mTOR 55%/69% and 73%/82%, for Akt 56%/72% and for S6K 78%/88%. We are using real-time PCR (qPCR) to quantify the effects of molting induced by eyestalk ablation (ESA) or multiple leg autotomy (MLA) on expression of Akt, mTOR, Rheb, and S6K. Supported by NSF (IOS-0745224). P3.50 ACKERLY, K. L.*; WARD, A. B. ; Adelphi University; kerriackerly@yahoo.com A Warmer Start: The correlation between vertebral development and C-start efficiency in Danio rerio The environment in which an individual develops significantly impacts that individual's morphology and, subsequently, locomotory performance. In fishes, previous research has shown that fish raised in lower temperatures develop more vertebrae, while fish raised in warmer temperatures develop less. Furthermore, previous studies have shown that a fish's ability to escape predators is strongly affected by the number of vertebrae present. In this study, the relationship between the effect of temperature on vertebral development and the subsequent effect on startle response was examined. We hypothesized that fish with more vertebrae would have higher performance when performing C-starts than those with fewer vertebrae. Zebrafish embryos were collected and evenly distributed into tanks with four temperatures, 24.5±1°C, 26.5±1°C, 28.5±1°C, 30.5±1°C, prior to the onset of somitogenesis. The startle responses were then recorded, and individuals were either analyzed for vertebral number or muscle fiber type. We found that individuals raised at higher temperatures have significantly less total and caudal vertebrae and that these individuals had significantly lower velocity and displacement during startle responses. These results will give insight into the effects that rising temperatures will have on the aquatic populations. P3.94 ADAMS, T*; BEAUBRUN, D; NELSON, M; CARROLL, M.A.; CATAPANE, E.J.; Medgar Evers College, Kingsborough Community College; catapane@mec.cuny.edu Study of Serotonin and Dopamine Post-Synaptic Receptor Mechanisms in the Bivalve Mollusc Crassostrea virginica Lateral cilia of gill of Crassostrea virginica are controlled by serotonergic-dopaminergic nerves from their ganglia. Serotonin (HT) increases, dopamine (DA) decreases cilia beating rates. Previous work showed increasing cilia beating rates depolarizes the cell. Applying DA or 20 Hz ES decreases beating rates and repolarizes the membrane. The post-synaptic HT and DA responses are G-protein linked metabotrophic mechanisms involving activation or inhibition of adenylcyclase and changes in ion channel conductance. We studied the ions involved in generating the post-synaptic responses by observing membrane potentials of lateral cells using DIBAC, a voltage sensitive fluorescent dye, while measuring cilia beating rates. We used artificial sea water with ion replacements based on Formulae and Methods VI, Marine Biological Labs, Woods Hole, MA. Stimulating the branchial nerve at 5 Hz increased cilia beating rates and caused prolonged increased fluorescence, indicative of membrane depolarization. Stimulating at 20 Hz after exciting cilia decreased beating rates and repolarized the membrane. Potassium free salt water reduced the response to 5 and 20 Hz ES. The same was seen with sodium free salt water. No differences were seen with calcium free salt water, but it should be kept in mind that cells contain sequestered calcium that may be sufficient to initiate responses when external calcium is low. The study shows correlation between changes in membrane potential of lateral ciliated cells and beating rates of the cilia, with the activity of effector channels which change ionic fluxes. It provides insights into the HT and DA post-synaptic receptor mechanisms in the gill of C. virginica. How do small teleost fishes respond to being stranded on land? Terrestrial movements by Danio rerio and Gambusia affinis Fish may become stranded on land when they jump out of water to escape predators or seek more favorable conditions; once stranded, the ability to return to the water is critical for individual survival. We have recently described a terrestrial jumping behavior in several fully-aquatic small teleost species. Here, we examine jumping in response to stranding by two species of teleost Danio rerio and Gambusia affinis. Because previous work in our laboratory suggests that Gambusia have a take-off angle of ~45 degrees, whereas the take-off angle of Danio approaches 90 degrees, we predicted that Gambusia would jump farther than similarly-sized Danio. To test this hypothesis, we placed individuals (n=10-12) of each species in a circular arena (~0.1 m diameter) lined with wetted lab-bench liner-paper and recorded their response for two minutes using a commercial-grade camcorder. We found that the average distance per jump for Danio was ~0.10 m, while Gambusia jumped only ~0.07 m, although maximum jump distances were similar for both species (~0.27 m). Danio jumped an average of over 40 times during a two minute trial, while Gambusia only jumped ~7 times. Consequently, over the course of the trial, Danio moved an average of >1.5 m, whereas the Gambusia moved <0.5 m. Although both fish have similar capacities for jumping, Danio showed a greater propensity to jump and traveled greater distances when stranded, relative to Gambusia. However, it is also possible that Gambusia employ a different strategy when stranded under natural conditions, such that they jump less frequently, but in a more directed manner. Poor foraging not breeding explains reproductive decline in a long-lived seabird. We examined data on age-related foraging patterns in reproductively active adult Nazca boobies (Sula granti), a pelagic seabird nesting in the Galápagos Islands. We looked for evidence of declining foraging ability with age by pairing our long-term demographic data with animal mounted remote sensing technologies. Using miniature GPS and depth recording units we tracked two groups of middle-age (9-16yrs) and old (17+yrs) birds on foraging trips during incubation in a cross-sectional fashion. We provide preliminary evidence of declining foraging performance with age in this species. We show that older birds remain away from the colony for longer periods than middle-aged birds, and that older birds gained less weight per foraging night than middle-age birds. We found that older birds have longer inter-dive intervals than middle-age birds and that older birds make fewer deep dives per day. We also found that older birds traveled further and at slower flight speeds from the colony on their foraging trips than middle-age birds. Nazca boobies experience a peak in reproductive success between years 9 and 13 with declining success after 16 years of age. This decline is due to the failure to complete a reproductive attempt, rather than failure to attempt breeding, providing an important clue regarding the nature of the reproductive senescence. Our evidence of age-associated changes in foraging ability may explain much of the observed reproductive decline. P3.149 ALLRED, L.M.*; CHRISTENSEN, L.A.; MEYERS, R.A.; GOLLER, F.; Weber State University, Ogden, UT, University of Utah, Salt Lake City; rmeyers@weber.edu Denervation and testosterone changes muscle fiber types in the Zebra Finch syrinx. Male and female Zebra Finches show sexual dimorphism in singing behavior, where males sing and females do not. Paralleling this behavior is dimorphism in muscle fiber composition and cross sectional area of the syrinx, a complex vocal organ in birds. Using histochemistry and immunohistochemistry, our lab previously discovered that the syrinx is composed of fast and superfast muscle fibers. Male Zebra Finches show a higher percentage of superfast fibers than females (85% vs. 24%, respectively). We investigated the effects of denervation and testosterone on the morphology of the syrinx. Denervation experiments were performed on both sexes, each resulting in a change in fiber type composition. The tracheosyringeal nerve to the syrinx was cut unilaterally between 4 and 40 days prior to syrinx removal. By day 9 post-denervation, males showed the greatest decrease in superfast fiber percentages (85% to 64%). By day 40 the original fiber type percentages returned. Denervated female syringes possess a population of slow fibers. This implies that denervation causes the expression of slower myosin and a change from superfast to fast muscle fibers in males and from fast to slow fibers in females. Testosterone supplementation was performed on females and administered for three weeks prior to the removal of the syrinx. Testosterone-treated syringes became masculinized, with an increase in superfast fiber percentages from 24% to 74% along with an increase in cross sectional area and fiber diameters. Although female syringes resembled those of males, they were still incapable of producing song. Further study will include an increase in sample size, diversity of species, and change in location of the nerve excision.
doi:10.1093/icb/icr007 fatcat:2i2rmrajuzccbay4bfuhvazgvm