SEMINAR: MBF STUDENT SEMINAR **FRI, 10/19 @ 1PM** ANDREW KEMPSELL & SHAREIN EL-TOURKY

[Pam Harris <pharris@rsmas.miami.edu>]

 

MBF Student Seminar Series

 

Andrew Kempsell

Advisor: Dr. Lynne Fieber

“Learning and memory deficits accompanying aging in Aplysia californica”

Tail withdrawal following mechanical stimulation is a well-documented behavior in Aplysia with a known neural circuit. The involvement of primary mechanosensory neurons makes the tail withdrawal reflex (TWR) optimal for correlating behavioral responses with individual neuronal output as a function of age. Habituation in the TWR, a form of non-associative learning, is marked by a decrease in the amplitude of tail withdrawal upon repeated tactile stimulation to the tail. Habituation in the TWR was monitored in freely behaving animals from sexual maturity to senescence. Whereas animals at sexual maturity were capable of habituating to tactile stimulation of the tail by 10 trials, measured as a significant decrease in time to recover from tail touch, senescent animals did not significantly habituate before 15 trials. Synaptic facilitation, a proxy for studying learning at the cellular level, was also monitored as a function of age in isolated neurons innervating the TWR. Ten minute exposure to serotonin induced facilitation of excitatory responses in mature but not old neurons. Changes in habituation of the TWR in senescent animals may indicate alterations in learning and memory that are evident at the cellular level via changes in excitatory synaptic transmission of innervating nerve cells.

 

 

Sharein El-Tourky

Advisor: Dr. Gary Hitchcock

“Mesozooplankton in the Florida Straits:

patterns in biomass and distribution.”

Variability in mesozooplankton distribution influences carbon cycling in the sea. Changes in the location or amount of zooplankton biomass may have cascading effects on the food chain, particularly larval fish growth rates. In 2003 and 2004, a study on larval Billfish dynamics was conducted in the Straits of Florida. Once component of this study was the collection of mesozooplankton biomass samples via monthly MOCNESS tows. These tows were made at 16 stations with a 1 m² 150 micron mesh net in four depth intervals: 0-25m, 25-50m, 50m-75m, and 75m-100m. Analyses of these tows were made in order to elucidate spatial and temporal trends in plankton biomass for comparison to trends in biomass of key larval fish prey species. No significant inter-annual variation in plankton biomass was observed. Zooplankton biomass was higher in winter months at all stations (December to May) than in summer. A spatial gradient was apparent in mesozooplankton biomass, with highest values at the western edge of the Straits, where biomass was approximately twice that at the eastern edge near Bimini. Vertical patterns show maximum biomass at 25 – 50 m, with minimal values at 75 – 100 m across the Current. These patterns correspond to seasonal and spatial gradients in chlorophyll α and estimated productivity gradients across the Straits.

 

FRIDAY, OCTOBER 19, 2012

1:00pm

RSMAS campus, S/A 103

--

Pamela Harris

Marine Biology and Fisheries

Rosenstiel School of Marine & Atmospheric Science

University of Miami

4600 Rickenbacker Causeway/SLAB-118

Miami, FL 33149

(305) 421-4176

fax - (305) 421-4600

pharris@rsmas.miami.edu  

 

http://www.rsmas.miami.edu/academics/divisions/marine-biology-fisheries/