Schedule and Program - North Carolina Academy of Science

Wavelength-dependent effects of light on the geotactic response of 2ndinstar larval Drosophila melanogasterLindsey M. Stanley*, Mariana V. Gattegno, Jelena Y. Atkins, and David H. DommerMount Olive CollegeWhile the morphological and genetic basis of geotaxis (i.e. gravitaxis) in adult organisms is well studied, researchof this sensory system in larval insects remains enigmatic. Larvae lack the sophisticated morphological structuresthat adults use to sense the gravitational vector (e.g. Johnston’s organ) and thus must possess an alternate sensorymechanism. Forward genetic screens with adult Drosophila have shown that genetic knockouts of the UVsensitivephotoreceptor cryptochrome disrupt normal geotactic responses. This photoreceptor has evolvedat least two other functions, with described roles in both the circadian clock and in magnetic field detection,which demonstrates spectral antagonism. We utilized a novel behavioral assay for geotactic preference screeningindividual 2nd instar larval Drosophila under various mono and dichromatic light conditions. Results establishthat larvae require short-wavelength (≤ 470nm) light to perform developmentally appropriate negative geotacticresponses, and showed an elimination of gravitaxis under long-wavelength (≥ 525nm) light conditions. Toseparate a behavioral artifact on motivation from a neurophysiological effect of sensing the gravitational vector,larvae were tested under one dichromatic condition, a mixture of short (365nm blue) and long-wavelength(525nm green) light. Under this condition geotactic preference was abolished indicating that short-wavelengthlight is necessary to elicit geotaxis and that long-wavelength light is spectrally antagonistic, inhibiting normalgeotactic behavior. These results provide the first evidence of spectral antagonism modulating the geotacticpreference of any organism. Furthermore, they indicate that cryptochrome activation is necessary for geotaxis inlarval Drosophila, and suggests a specific link between geotaxis and the geomagnetic sensory system.Fertilizer Application and the Accumulation of Zn in Various VegetablesKyle O. Starling*Lenoir-Rhyne UniversityAs the global population soars beyond 7 billion, pressure to produce an adequate amount of food also increases.Industrial agriculture has increased crop yields by using large scale mechanization, increasing irrigation, andwidespread use of fertilizers. Unfortunately, the benefits we reap from these modern techniques come at the price ofsoil depletion/erosion, reliance on fossil fuels, and problems with over application of fertilizers. Erosion of topsoilfrom over-tilling or excessive grazing has proved to be especially troublesome; not only does it reduce crop yield, butalso may reduce the nutrient content of the crop grown in the depleted soil. Zinc is an essential micronutrient forboth humans and plants. In humans, zinc is important in everything from enzymatic activity to proper neurologicalfunctioning. While zinc was at one time thought to be present in satisfactory quantities in a variety of foods, it hassince been recognized as a “nutritional pandemic” in both developed and developing countries because people don’tseem to be getting enough of the metal in their diet. The purpose of this experiment is to analyze how the nutrientcontent of soil affects the concentration of Zn in vegetables. Samples were taken from garden plots that received adiffering number of fertilizer applications. These samples were analyzed using Atomic Absorption. Wisconsin FastPlants cultured in sand were also examined using the same instrumental technique. Preliminary studies using theaforementioned method and lettuce showed 0.0083 wt% Zn.Campbell University - 71