Oral Presentations: Session C

Native peoples of Southern California historically used a variety of local plants as remedies for illnesses. Chaparral species such as Rhus ovata (sugar bush) were widely available and were used to ease headaches, coughs and chest pains, and colds. In light of the historical importance of this plant and other chaparral species, recent fungal pathogen-induced diebacks of Malosma laurina, a species closely related to R. ovata, have raised questions regarding the innate defenses of these plants against fungal pathogens. We attempted to scientifically evaluate the traditional medicinal use of R. ovata and its antifungal resistance by testing two hypotheses: 1) Will an extract of R. ovata leaves have antibacterial properties? 2) Will an extract of R. ovata leaves have antifungal properties? In order to test the first hypothesis we used a 96-well plate assay growth assay with resazurin dye to measure the growth of the bacteria Staphylococcus epidermidis and Staphylococcus aureus after treatment with various concentrations of a R. ovata leaf extract. Treatment with high concentrations (1 mg/mL) of R. ovata leaf extract inhibited growth of S. epidermidis and S. aureus, but at lower concentrations the extracts did not inhibit the growth of either organism. In order to test the second hypothesis we used a fungal disc diffusion assay on potato dextrose agar to measure the growth the fungus Botryosphaeria dothidea after treatment with R. ovata extracts. These extracts did not inhibit the growth of the fungus. Our results support the traditional use of R. ovata by Chumash Indians as a treatment for some ailments, however the lack of antifungal activity indicates that R. ovata may have alternative resistance mechanisms to ward off fungal pathogens such as B. dothidea that are currently causing dieback of related chaparral species.

We tested the hypothesis that an opportunistic endophytic fungus Botryosphaeria dothidea that frequently infects and causes dieback in several different species of chaparral shrubs in the Santa Monica Mountains continues to elongate and grow in host tissues at dehydration levels that exceed host survival. This was done by collecting several large branches from the field from three dominant species of co-occurring chaparral shrubs, Malosma laurina, Ceanothus spinosus, and Ceanothus megacarpus. We allowed branches to dehydrate at increasing lengths of time, from a few days to one week, in an air-conditioned laboratory, then sealed in plastic bags to allow tissuewater equilibration, and measured water potential at different dehydration levels. Stem segments were then inoculated with the fungal pathogen B. dothidea, sealed into test tubes, and allowed to incubate for a total of six days. After six days of fungal growth, lengths of hyphal invasion into stem tissues was recorded and final water potentials were determined using a dew point hygrometer. In Malosma laurina (± 3.74 SE, n = 30), exceeding the survival limits of the host plant (100% cavitation of stem xylem at -4 MPa). In Ceanothus spinosus (± 2.91 SE, n = 30), approaching the survival limits of the host at -9 MPa. In Ceanothus megacarpus (± 3.34 SE, n = 30), also approaching the survival limits of the host at -13 MPa. This indicates that the invasion and growth of the fungal pathogen B. dothidea in the stem xylem of these co-dominant chaparral species can continue under severe drought conditions recently experienced in California and likely contribute to the whole plant mortality increasingly observed for these species.

Undergraduate Research

Seaver Undergraduate Research

Alzheimer’s disease impacts 18 million patients worldwide. An early indicator of Alzheimer's disease is the degeneration of locus ceruleus neurons and reduction of norepinephrine concentration in locus ceruleus projection areas. The neurotoxin N-(2- chloroethyl)-N- ethyl-bromo- benzylamine (DSP 4 ) has been demonstrated to cause severe damage to locus ceruleus neurons and cortical norepinephrine transporters in mice. It has been observed that mice injected with DSP4 also present with elevated amyloid amyloid b levels and impaired spatial memory performance when compared with control mice. To effectively examine Alzheimer's disease, It is critical to develop a model that mimics the amyloid b (Ab) and tau pathology as well as the neuroinflammatory component of the disease. Using our pilot data, we designed an experiment (ongoing) to measure the effects of chronic folic acid deficiency in a mouse model of Azheimer's disease. To accomplish this, we have injected the mice with either saline (control), or 10 mg/kg DSP 4 (low dose) or, 50 mg/kg DSP 4 (high dose); then testing the C57bl mice using several behavioral and cognitive tests (ability to build a nest with Nestlets; occurrence of rearing using Open Field testing [OF]; curiosity using Novel Object Recognition[NOR]) during the spring and summer of 2018. In summer of 2017, we performed pilot tests by injecting C57bl/6 mice with varying levels of DSP 4 in order to determine the optimal dosage that manifests accurate rearing in our OF testing, a recognized measurement of Alzheimer’s disease in the mouse model. The DSP 4 injected mice used for the pilot tests were placed in OF tests, an experiment commonly used to measure general locomotor activity levels and anxiety in rodents. Data for the pilot study demonstrated that a significant portion of the mice died if injected with 50mg/kg DSP 4 within 3 day intervals. Mice with one injection of 50mg/kg DSP 4 did not show significance in overall 15 minute OF tests with regards to rearing or line crossings when compared with mice that were injected with saline. Indeed, significance occurred when data points were compared using minute by minute’s intervals.

The WIC food package provides an important benefit for mothers and children. Since 1974 the food package had not undergone any major revision until 2009, when it was revised to align with the Dietary Guidelines for Americans (DGA) and Healthy People 2020 goals. Recently, USDA commissioned an expert committee of the National Academies of Sciences, Engineering and Medicine (NASEM) to review the current food package and provide recommendations for the next cycle of revision. Recommendations by the committee include increasing the dollar amount of the cash value voucher (CVV) along with the addition of fish in order to improve alignment with the recent DGAs. The committee also recommended supporting cultural preferences and requiring states to offer additional options for various food categories. The current study was undertaken in 2016 to explore how participants choose WIC foods during the shopping experience. In-person interviews were conducted with 204 participants from five ethnic groups and in four languages at WIC sites around Southern California. This session will present information about what participants shared about their purchasing behavior for WIC foods. Over two-thirds of all participants reported looking at the prices of FV, and 80% reported using their own money to buy more FV. Across all ethnic groups, when asked which WIC foods participants would like more of, FV were the most frequently requested. Asian participants also preferred more fish. These results and many others suggest recent NASEM recommendations will further improve the acceptability of the food package, particularly among ethnic minority participants.

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