Discipline: Biological Sciences
Shantae Lewis - University of the Virgin Islands
Co-Author(s): Erlin Ravariere, University of the Virgin Islands, St. Croix
Invasive species pose a threat to the ecosystems that they invade by out-competing native species for resources. The seagrass Halophila stipulacea is one of these invasive species. It originated in the Indian Ocean and has invaded the waters of the Virgin Islands; if it is not stopped or at least controlled it can lead to the extinction our native species. Which would be tragic for our fishes, because they prefer to eat the seagrass that is native to us. The goal of our project is to find the genetic variability of H. stipulacea and to use that information to create an invasion history model. In doing this we hope to gain more knowledge on the seagrass, and to understand the source of invasion and how it was spread on St. Thomas and around the Virgin Islands. In order to achieve this goal we had several smaller objectives including: extracting high yield DNA samples and making them into libraries, finding a protocol that would give the most DNA yield, and determining their genetic structure and colonial diversity of the seagrass. The first step was to collect leaf samples of Halophila stipulacea from eight different sites around the Virgin Islands. After the leaves were collected they were cleaned in order to get rid of epiphytes and debris; then they were stored in silica gel to dry. During the summer plants were extracted using one leaf and the DNeasy mini kit by Qiagen. The yields we received form this were varying from one extreme to the other, they showed no trends to draw results from whether they were extracted fresh or using more leaves. Later we found that the DNA quantity from our samples were much lower than we needed them to be and so all samples had to be re-extracted. The regular CTAB procedure was used, it produced good yields but they were still not high enough. Extractions are now done using plants with 15 to 25 leaves or that weigh about 0.1 gram when dried. These new extractions are done using the Halophila Next Generation DNA Extraction Protocol. So far ten (10) of the larger samples have been made into libraries and are in the process of having their DNA sequenced. Additionally, we have re-extracted 47 of the remaining 54 samples. Using this new protocol our DNA from the gel electrophoresis resulted in much brighter bands, they are less sheared and streaky than previous extractions. We also received some bands with high molecular weight; the highest amount being approximately 1 microgram with the lowest being about 300 nanograms. Based on where we are, we have not had the chance to test our hypothesis which states that, the genetic variability of the seagrass, Halophila stipulacea, will be lower than that of its place of origin.
Funder Acknowledgement(s): We would also like to acknowledge UVI NSF HBCU-UP Grant #1137472 and Experimental Program to Stimulate Competitive Research (VI-EPSCoR award #0814417) for their contribution in making this research possible.
Faculty Advisor: Alice Stanford, Ph.D., firstname.lastname@example.org
Role: As the lead researcher my job was to assist in cleaning and extracting DNA from the samples. To aid in finding the best protocol. It was also my job to write the abstract and the PowerPoint with the help of my co-author.