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Multicellular fruiting bodies are induced by starvation conditions and house desiccation-resistant myxospores that will germinate into vegetative cells upon exposure to nutrients. Interestingly, fruiting body formation in Stigmatella aurantiaca, a well-characterized myxobacterium, is stimulated by blue and/or red light. The S. aurantiaca genome annotation indicates two photoactive yellow proteins (PYPs) and two bacteriophytochromes (BphPs) that the closely related myxobacterium Myxococcus xanthus lacks. BphPs are red-light photoreceptors found in both photosynthetic and non-photosynthetic bacteria. Six out of 15 sequenced genomes of myxobacteria contain BphPs. Our hypothesis is that BphPs may play a role in fruiting body formation. We cultured S. aurantiaca DW4/3.1 and M. xanthus DZ2 on starvation agar plates in both light and dark conditions. Our preliminary results show that light-incubated S. aurantiaca produce larger and more pigmented fruiting bodies compared to the ones formed in dark. Conversely, fruiting bodies of M. xanthus grow better in the dark. We are going to perform transposon mutagenesis to inactivate the genes coding for BphPs in S. aurantiaca and observe the fruiting body formation of these mutants. Understanding the role of BphPs in myxobacteria and whether they work in tandem with other genes responsible for fruiting body formation may shed light on developmental biology questions about multicellular life-cycles and cell differentiation.
AMYOTROPHIC LATERAL SCLEROSIS IN C. ELEGANS: UNDERSTANDING HOW TDP-43 AGGREGATION
AFFECTS MOTOR NEURON FUNCTIONEmily Rendleman, Cindy Voisine.
Northeastern Illinois University, Chicago, IL.
TDP-43 is an RNA-binding protein that has been linked to neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), though the pathological mechanisms of TDP-43 are unknown. To study the effects of TDP-43 on neuronal function, we generated a C. elegans model for ALS by cloning the human wild-type TDP-43 gene tagged with a yellow fluorescent protein under a pan-neuronal promoter. The neuronal function of both transgenic and wild-type worms were assessed with behavioral assays to monitor motility, pharyngeal pumping, and egg-laying.
Preliminary results show that the presence of wild-type human TDP-43 in the C. elegans system has significant, detrimental effects on worm coordination and ability to move across solid surfaces and in liquid, indicative of GABAergic neuronal dysfunction. The characterization of this neuronal dysfunction will help us gain further understanding of ALS related neurodegenerative disease pathology.
GROWTH AND PHOTOSYNTHETIC CHARACTERISTICS OF PROGENY FROM WINTER AND SUMMER-ACTIVE
HELIANTHUS IN THE CORPUS CHRISTI, TX AREAAbigail Johnson, David Grise.
Texas A&M University-Corpus Christi, Corpus Christi, TX.
Helianthus annuus is the most common species of sunflower in North America and is commonly found growing and flowering year round in Corpus Christi, Texas. To determine if there are differences in growth and photosynthetic characteristics between progeny from summer-active and winter-active plants during each season, plants were grown individually and with 2 or 4 associates from the opposite group of plants during the winter and summer growing seasons. Our hypothesis is that there is no difference in growth and photosynthetic characteristics between progeny from winter-active and summer-active plants during either season. If so, as climate changes, this could lead to the establishment of winter-active cohorts in more northern areas. We found no significant difference in the photosynthetic rate measured in February 2013 for target plants between progeny from winter-active and summer-active plants (P =
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0.0810). In addition, there was no difference in height for target plants (P = 0.3709) or for height of associate plants (P = 0.448). In the winter growing season, progeny from summer-active plants are doing as well as progeny from winteractive plants. We found no differences in growth and photosynthetic characteristics between progeny from summeractive and winter-active plants indicating that H. annuus could extend its growing season in regions farther north of our area if winters become warmer in these areas.
ALTERATIONS IN STEM CELL FUNCTION FOLLOWING A PERSISTENT COXSACKIEVIRUS INFECTION OF
NEURAL STEM AND PROGENITOR CELLS, AND ACCELERATED DISEASE PROGRESSION IN A MOUSE
MODEL OF ALZHEIMER’S DISEASEAlicia Zamudio Montes de Oca, Ralph Feuer.
San Diego State University, San Diego, CA.
Coxsackievirus B3 (CVB3) is a human pathogen that can leave long-lasting alterations in the central nervous system (CNS) of the surviving host. Our laboratory has characterized the ability of CVB3 to persist in the CNS, preferentially targeting neural progenitor and stem cells (NPSCs). We wished to examine the effects of a persistent CVB3 infection in hAPP751 transgenic mice, a mouse model for Alzheimer’s disease (AD). These mice express the amyloid-β1-42 protein under the murine Thy1 promoter and reproduce some aspects of AD pathology observed in patients.
The hAPP751 transgenic mice infected with CVB3 shortly after birth showed increased mortality as compared to either infected nontransgenic littermates or mock-infected hAPP751 transgenic mice over a 7-month period. We hypothesize that fundamental molecular changes in neurons of persistently infected hAPP751 transgenic mice may accelerate the progression of neurological disease in our AD mouse model. To assess this hypothesis, NPSCs were isolated from the cortices of 3-day-old hAPP751 transgenic mice or nontransgenic littermates. These NPSCs were infected with a recombinant CVB3 expressing the enhanced green fluorescence protein (eGFP-CVB3) to establish a carrier-state infection. Infected hAPP751 NPSCs and NPSCs from nontransgenic littermates were monitored for a period of 50 days, and the number of viable cells were quantified. After differentiation in culture, alterations in cell lineage commitment, autophagic flux, and amyloid-b protein levels will be tested. Our preliminary results suggest that a previous neurotropic infection which persists in the host may accelerate the progression of a subsequent neurodegenerative disease by altering neural stem-cell function.
GROWTH AND LIPID PRODUCTION OF THE MICROALGAE SPIROGYRA FOR BIOFUEL PRODUCTIONBeatriz Millare, Christine Case.
Skyline College, San Bruno, CA.
The finite amount of fossil fuels and the greenhouse gas emissions from their combustion have become significant issues and ignited interest in biodiesel production. Microalgae are one of the most hopeful sources for an alternative fuel because of their ability to reproduce rapidly and their high lipid content which can be transformed into a renewable, carbon-neutral fuel. Moreover, microalgal lipids are biodegradable. Past studies have reported on single-cell microalgae with little attention to filamentous genera. The purpose of this study is to investigate the growth and lipid production of filamentous Spirogyra. Spirogyra sp. is being grown in Petri plates containing treated sewage effluent, seawater, and tap water adjusted to various pH levels (from 6 to 8). Cultures are incubated at room temperature (20 – 25 °C) with ambient sunlight for 15 days. Cell growth is determined by counting algal filaments and measuring filament length. Lipid content is determined by staining the Spirogyra with Sudan black. Preliminary results suggest Spirogyra grows best, increasing its filament length 1.5 μm/day and tripling its lipid content, at pH 7 in tap water. Algae in basic (pH 8) media grew slower (0.5 μm/day) but also tripled its lipid content. Lipid content doubled in Spirogyra in sewage effluent, but the algal growth rate decreased (0.8 μm/day). Algal numbers and cellular lipid content decreased in seawater and acidic media. The results may lead to sustainable fuel production that does not promote global warming.
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Biological Sciences FRI-468
ASSESSING GEOCHEMICAL CONTROLS ON MERCURY TRANSFORMATIONS AND TRANSPORT AT A
NORTHERN CALIFORNIA COASTAL LAGOON SITEIvy Lurz, Priya Ganguli, Sharon Hibdon, A. Russell Flegal.
University of California, Santa Cruz, Santa Cruz, CA.
Ephemeral lagoons along California’s northern coastline are an important yet poorly-understood part of the coastal ecosystem. They exist in a dynamic environment where nutrient-rich, oxygen-poor groundwater mixes with near shore seawater. This interface creates an environment well suited to the growth of anaerobic bacteria that are capable of converting a common form of inorganic mercury (Hg2+) into monomethylmercury (CH3Hg+), which is a bioaccumulative neurotoxin. The toxicity and bioavailability of mercury can therefore be related to factors that influence microbiology, such as nutrient, carbon, and oxygen concentrations. To gain a better understanding of mercury cycling in near-shore systems, researchers in the lab are characterizing the form and concentration of mercury in seawater, groundwater, and lagoon water at a coastal lagoon site in northern California. The concentration of nutrients (NO3-, NO2-, NH4+, PO43and SiO44-) and dissolved organic carbon (DOC) in the water samples will be determined. These data will be used to describe nutrient gradients at the study area and will contribute to a greater understanding of geochemical controls on mercury transformations and transport at the land-sea margin.
NET-PHYTOPLANKTON SURVEY IN GUAJATACA RESERVOIR, A MESOTROPHIC LAKE IN PUERTO RICOHector Esparra-Escalera, María Rodríguez-Santiago, Bárbara Sánchez-Santana, Carlos Santos-Flores.
University of Puerto Rico at Mayagüez, Mayagüez, PR.
Phytoplankton communities play important roles in aquatic systems, serving as main oxygen producers as well as first links in trophic chains. Moreover, phytoplankton species composition has been widely employed as a bioindicator of trophic status. Our purpose is to form a data base on net-phytoplankton composition that can be useful for water management of insular, man-made lakes. Guajataca Reservoir, a mesotrophic lake, was selected because it is at the lowest end of the trophic range among local reservoirs. It was constructed in 1929 by the Puerto Rico Electric Power Authority, and since 1950 its volume of water has been decreasing due to sedimentation. Duplicate samples were taken between March and July 2012 and in January 2013 from Guajataca Reservoir using two attached Bongo nets with mesh size of 64 µm. Samples were preserved with formalin (4% final volume), and the net-plankton composition was determined. Net-phytoplankton density (cells/mL) increased from March to April. In July, there was a decrease in phytoplankton density followed by an increase in species richness. Nevertheless, in January, there was an increase in diatoms. Green algae in all of the samples dominated the phytoplankton composition; within this group, Pediastrum was the most abundant in this lake.
FISHING OUT A ROLE FOR TRANSCRIPTION FACTORS IN HUMAN DISEASE: ANALYSIS OF KAISO IN
ZEBRAFISH DEVELOPMENTYuri Almeida, Seth Frietze.
Northern New Mexico College, Espanola, NM.
Transcription factors control gene expression and play an important role in cell differentiation. Transcription factors function by binding to DNA and to other proteins. Several human diseases are linked to mutations in genes that encode transcription factors. There is consistent evidence of the role of ZBTB33 (zinc finger and BTB domain containing 33, also referred as Kaiso) and its involvement in human tumorigenesis and specific gastrulation defects.
Kaiso is found on chromosome 14 on Danio rerio (zebrafish). To investigate the function of Kaiso in development and disease, we aim to characterize its expression in zebrafish by mining expression databases. We also plan to predict its target genes by searching the zebrafish genome for potential DNA binding sites. To validate this data, we will suppress Kaiso expression in zebrafish by injection of morpholinos targeting Kaiso and look for developmental and gene expression defects. Overall, this research will reveal new information on a transcription factor associated with human disease.
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QUANTIFYING THE ELECTROPHYSIOLOGICAL EFFECTS OF GOLD, STAR-SHAPED NANOPARTICLES ON
CA3 PYRAMIDAL NEURONSKirstie Salinas, Zurab Kereselidze, Xomalin Peralta, Fidel Santamaria.
University of Texas at San Antonio, San Antonio, TX.
Nanotechnology is an emergent discipline that has the potential to change biomedical research. We are interested in using metal nanoparticles in neurobiology that can be used for photo-thermal therapy, drug delivery, or as spatial markers to trace neurons or organelles. However, the health hazard of nanoparticles is of concern, given that some nanoparticles have been found to be toxic to cells. We hypothesized that in the nervous system, their effect could be subtle, affecting the electrophysiological properties of neurons. Thus, we investigated how gold, star-shaped nanoparticles affect the spiking activity of hippocampal mouse cells in brain slices. We have synthesized gold nanostars and characterized them optically and morphologically. We have initially developed a protocol to deliver the nanoparticles by pressure injection while recording the extracellular activity of multiple pyramidal cells from 14- to 21-day-old mice. These types of nanoparticles are expected to bind to surface proteins, thus altering the electrical properties of the cell. Our studies show an increase in CA3 firing rate after the introduction of gold nanostars.