Defensins are small, cysteine-rich, immune related proteins described to be the most widespread family of invertebrate antimicrobial peptides. Presently, there is limited information regarding spider defensins. In this study, a new defensin peptide was described in Latrodectus geometricus, Lg-defensin. The full open reading frame was resolved using RACE and de novo assembly, followed by a bioinformatical analysis and phylogenetic alignment to determine conserved sequence patterns and structural similarities to other defensins. Next, the functionality of Lg-defensin was determined using in vitro RNA interference to assess what impact silencing had on the spider’s ability to control a gram-positive and gram-negative bacterial infection, whose level was determined via qPCR analysis. Results indicated Lg-defensin to be a highly conserved defensin with similar structure and sequence patterns to other related taxa. Additionally, Lg-defensin was found to have higher antibacterial activity towards the gram-positive bacteria in contrast to its effect on gram-negative bacteria. This is the first report regarding the completed characterization of a defensin peptide in L. geometricus and provides a basis for future research regarding Lg-defensin and its clinically relevant capabilities.
","abstract_html":"<p>Defensins are small, cysteine-rich, immune related proteins described to be the most widespread family of invertebrate antimicrobial peptides. Presently, there is limited information regarding spider defensins. In this study, a new defensin peptide was described in <em>Latrodectus geometricus, </em>Lg-defensin. The full open reading frame was resolved using RACE and <em>de novo</em> assembly, followed by a bioinformatical analysis and phylogenetic alignment to determine conserved sequence patterns and structural similarities to other defensins. Next, the functionality of Lg-defensin was determined using <em>in vitro </em>RNA interference to assess what impact silencing had on the spider’s ability to control a gram-positive and gram-negative bacterial infection, whose level was determined via qPCR analysis. Results indicated Lg-defensin to be a highly conserved defensin with similar structure and sequence patterns to other related taxa. Additionally, Lg-defensin was found to have higher antibacterial activity towards the gram-positive bacteria in contrast to its effect on gram-negative bacteria. This is the first report regarding the completed characterization of a defensin peptide in <em>L. geometricus </em>and provides a basis for future research regarding Lg-defensin and its clinically relevant capabilities. </p>","abstract_has_math":false,"creators":["Thompson, Jacklyn Victoria"],"institution":null,"degree_name":"Master of Science - Biology","degree_level":"Thesis","degree_discipline":"Biology","degree_department":null,"school":null,"contributors":["Dr. Dennis Gravatt","Dr. Lindsay Porter","Dr. Zeljko Radulovic"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-12-01T08:00:00Z","date_published":"2022-12-01T08:00:00Z","updated_at":"2026-07-24T04:30:37Z","subjects":["Antimicrobial Peptides","Defensins","RNA-interference","Latrodectus","RT-qPCR","Spiders","Molecular Biology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarworks.sfasu.edu/etds/477","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dr. Dennis Gravatt","Dr. Lindsay Porter","Dr. Zeljko Radulovic"]},{"key":"dc:creator","label":"Author","values":["Thompson, Jacklyn Victoria"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2022-12-08T08:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science - Biology"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Antimicrobial Peptides","Defensins","RNA-interference","Latrodectus","RT-qPCR","Spiders","Molecular Biology"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarworks.sfasu.edu/etds/477"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Defensins are small, cysteine-rich, immune related proteins described to be the most widespread family of invertebrate antimicrobial peptides. Presently, there is limited information regarding spider defensins. In this study, a new defensin peptide was described in Latrodectus geometricus, Lg-defensin. The full open reading frame was resolved using RACE and de novo assembly, followed by a bioinformatical analysis and phylogenetic alignment to determine conserved sequence patterns and structural similarities to other defensins. Next, the functionality of Lg-defensin was determined using in vitro RNA interference to assess what impact silencing had on the spider’s ability to control a gram-positive and gram-negative bacterial infection, whose level was determined via qPCR analysis. Results indicated Lg-defensin to be a highly conserved defensin with similar structure and sequence patterns to other related taxa. Additionally, Lg-defensin was found to have higher antibacterial activity towards the gram-positive bacteria in contrast to its effect on gram-negative bacteria. This is the first report regarding the completed characterization of a defensin peptide in L. geometricus and provides a basis for future research regarding Lg-defensin and its clinically relevant capabilities.
"]},{"key":"dc:title","label":"Title","values":["Sequencing and functional characterization of a Latrodectus geometricus defensin, Lg-defensin"]}]}],"canonical_facts":{"dc:contributor":["Dr. Dennis Gravatt","Dr. Lindsay Porter","Dr. Zeljko Radulovic"],"dc:creator":["Thompson, Jacklyn Victoria"],"dc:date.available":["2022-12-08T08:00:00Z"],"dc:description.abstract":["Defensins are small, cysteine-rich, immune related proteins described to be the most widespread family of invertebrate antimicrobial peptides. Presently, there is limited information regarding spider defensins. In this study, a new defensin peptide was described in Latrodectus geometricus, Lg-defensin. The full open reading frame was resolved using RACE and de novo assembly, followed by a bioinformatical analysis and phylogenetic alignment to determine conserved sequence patterns and structural similarities to other defensins. Next, the functionality of Lg-defensin was determined using in vitro RNA interference to assess what impact silencing had on the spider’s ability to control a gram-positive and gram-negative bacterial infection, whose level was determined via qPCR analysis. Results indicated Lg-defensin to be a highly conserved defensin with similar structure and sequence patterns to other related taxa. Additionally, Lg-defensin was found to have higher antibacterial activity towards the gram-positive bacteria in contrast to its effect on gram-negative bacteria. This is the first report regarding the completed characterization of a defensin peptide in L. geometricus and provides a basis for future research regarding Lg-defensin and its clinically relevant capabilities.
"],"dc:identifier":["https://scholarworks.sfasu.edu/etds/477"],"dc:subject":["Antimicrobial Peptides","Defensins","RNA-interference","Latrodectus","RT-qPCR","Spiders","Molecular Biology"],"dc:title":["Sequencing and functional characterization of a Latrodectus geometricus defensin, Lg-defensin"],"thesis:degree_discipline":["Biology"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science - Biology"]},"updated_at":"2026-07-24T04:30:37Z"}