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Neuroscience

Using Polymerzing Chain Reaction to Detect Mutations > In the SSP4 Gene of DrosoPhila Melanogaster

Kass, Peter ('09);  Wilson, Joseph ('10);  Johnson, Karl; Means, Kevin ('08)

The proper development of the central nervous system is vital to the functioning of any vertebrate. This proper development depends heavily on interactions between a group of molecules known as Heparin Sulfate Proteoglycans. However, a newly discovered gene, SSP4, has been linked to aiding in CNS development. Using P-element mutagenesis, we attempted to create 44 stocks of SSP4 mutant flies, which would allow us to analyze the gene's effect on CNS development. Through analyzing genomic DNA via PCR we determined that the P-element had failed and no mutants were produced. This then limited our ability to analyze mutant CNS phenotypes.
Funding provided by: The Norris Foundation

Ethynylestradiol Partially Recovers Stress-Induced Deficits in LTP

Barkley-Levenson, Amanda ('09); Scharfen, Anna ('09); King, Jonathan

Estrogens are reported to enhance hippocampal long term potentiation (LTP), and are believed to provide neuroprotection against stress-induced impairments in learning and memory. In this study, the effect of ethynylestradiol (EE, the main component of oral contraceptives) on hippocampal synaptic plasticity was examined. Rats were subjected to 1 week of restraint stress (2 hr/day) or restraint stress with EE treatment (100 ppm in food), and then trained on a Morris water maze task. Hippocampal slices were obtained after behavioral testing and extracellular population spikes were recorded. Stress group animals displayed significantly lower population spike amplitudes following theta burst stimulation than controls (136.15% vs. 159.83%, recorded for 30 min.). Treatment with both stress and EE significantly alleviated some of the deficits in LTP caused by the stress treatment alone (152.01% vs. 136.15%). These results suggest that EE has some neuroprotective capabilities and can at least partially recover stress-induced deficits in LTP.
Funding provided by: Pomona College SURP (AB), Howard Hughes Medical Institute (AS)

Using Vibration to Improve Balance Control

Gyorffy, Janelle ('09);  Fraiser, Ryan (PI '09)*;  Milton, John** Ohira, Toru***
*Pitzer College, Claremont CA; **The Claremont Colleges, Claremont CA; ***Sony Computer Science Laboratories, Tokyo, Japan

The purpose of this research was to determine the effect of Achilles’ tendon vibration on postural sway. Postural sway was measured using a force platform (Accusway, ATMI) while their Achilles’ tendon was vibrated using a Minishaker 4810 (Brüel & Kjaer). For all subjects the path length made by the fluctuations of the COP was increased with Achilles’ tendon vibration, but the area of the ellipse that enclosed 95% of the fluctuations decreased. In other words, the speed of the fluctuations in COP was greater, but confined to a smaller area. There was no effect of vibration frequency suggesting that the effects of vibration were not operating through mechanoreceptors, such as muscle spindles. The fluctuations in COP were not affected by performance of mental tasks concurrently or when a 200 micron vibration (C-2 tactor, Engineering Acoustics, Winter Park, FL.) was applied. These observations suggest that the stabilizing effects of vibration of postural sway are related to the mechanical effects of the vibration itself.
Funding provided by: The National Science Foundation Grant (0617072);  The William R. Kenan, Jr. Charitable Trust

Benzoate and Sarcosine, Promising Novel Antipsychotics?

Kaneshiro, Kayleigh ('10);  Tsai, Guochuan E.*

*UCLA, Los Angeles CA and LA Biomed

Schizophrenia targets the neurotransmission of the N-methyl-D-aspartate (NMDA) receptor selective for glutamate. Sodium benzoate inhibits D-amino acid oxidase (DAAO), which metabolizes the co-agonists of the NMDA receptor, D-alanine and D-serine. In addition, N-methyl-glycine (also called sarcosine) inhibits the GLY-T1 reuptake pump, enhancing the synaptic glycine available. We hypothesize higher levels of D-serine and D-alanine present in serum and brain tissue after treatment of sodium benzoate and/or sarcosine, and this enhancement of D-amino acids will reverse neurophysiological deficits produced by psychotomimetic, amphetamine, as well as improve the symptoms of patients with schizophrenia. We conducted two experiments. The first was the efficacy of sodium benzoate on 21 physically healthy patients clinically diagnosed for schizophrenia;  HPLC analyzed the levels of D-amino acids in the serum. The second study examined the CNS levels of the D-amino acids after sodium benzoate treatment and a dual treatment (benzoate and sarcosine) on mice. We observed that treatments restored amphetamine-disrupted prepulse inhibition.
Funding provided by: Claremont Colleges Neuroscience Summer Research Fellowship Program;  LA Biomed

The Effect of 17a-Ethynylestradiol on Spatial Learning and Memory in Male Rats

Scharfen, Anna ('09);  Barkley-Levenson, Amanda ('09);  King, Jonathan

There has been a growing concern over the impact that environmental estrogens (manmade compounds that mimic natural estrogens) have on animal physiology. In the current study, we examined whether 17a-ethynylestradiol (EE, a pharmaceutical estrogen found in the environment) provides neuroprotection against stress induced impairments in spatial learning and memory. Our results show that during block 1 of Morris water maze training, rats exposed to one week of restraint stress showed an increase in latency and a longer path length to platform over controls (w/o stress, w/o EE), but performed slightly worse than the stress+EE group. During a 72-hour retention test, the stress+EE group spent more time in the target quadrant (39.4%) than the stress group (29.8%). Our results may have been confounded by the treatment group’s aversion to EE in their food, which impaired their weight. Although differences were not observed in other training blocks, EE shows promise as a neuroprotective agent.
Funding provided by: Howard Hughes Medical Institute (AS);  Pomona College SURP (AB)

Utilizing Transposon Excisions for Synbindin Mutagenesis in Drosophila

Wilson, Joseph Gardner ('10);  Johnson, Karl

The heparan sulfate proteoglycan Syndecan regulates axon guidance at the midline and synapse growth at the neuromuscular junction in Drosophila. Previous research in vertebrates has implicated Synbindin as a binding partner for Syndecan. We aimed to create a mutation in Drosophila Synbindin, through an imprecise excision of a transposon in the first intron of Synbindin, in order to elucidate Synbindin’s role in neural development. After isolating DNA of each candidate mutant, we ran PCR and agarose gel electrophoresis to detect deletions. Although we did not find any mutations that generated amorphic alleles of Synbindin, larval and embryonic phenotypes of a Synbindin hypomorphic allele suggest a function for Synbindin at both the neuromuscular junction and at the midline. Continuing experimentation will include phenotype rescue, an analysis of other candidate sybindin alleles, examination of Syndecan localization in Synbindin mutants, and another attempt to generate a Synbindin mutation via transposon excision.
Funding provided by: The Norris Foundation (JW);  SOMAS grant from NSF (KJ)

Research at Pomona