Student Research Projects

Accumulation of Triglyceride in Tropical Termites Infected with an Acanthocephlan Parasite

Student Sierra Brown, '16
Faculty Mentor(s)
Department Biology
Course BIO 489: Research in the Natural Sciences

Abstract

Termites of the species Nasutitermes acajutlae commonly found on the Caribbean islands of St. Thomas and St. John are sometimes infected with a juvenile form of an acanthocephalan parasite (‘spiny-headed worms’) Oncicola venezuelensis. Previous work by Dr. Rock, conducted in 1997, had shown that infected termites accumulate triglyceride (fat) though this finding has never been published. The purpose of the current project is to use an alternative (colorimetric) method to quantify triglyceride levels in infected and uninfected termites that have been stored for 18 years in ethanol and compare them with freshly harvested specimens acquired over spring break of the spring 2016 semester. Total lipids were extracted from homogenized termites using organic solvents and separated using thin-layer chromatography (TLC) and visualized with iodine staining. The colorimetric method of lipid quantification utilizes the reduction of potassium dichromate with concomitant reduction in absorbance at 350 nm. Freshly harvested specimens were dissected to verify the presence of the parasite and then pooled and dried to constant weight before lipid extraction with chloroform:methanol (2:1 v/v). None of the freshly collected specimens (from six different nests) were parasitized. Qualitative comparison of triglyceride levels using TLC, verified the accumulation of triglycerides in infected termites. The colorimetric analysis however, was fraught with problems – possibly due to impurities in the solvents. Nonetheless, the presence of a relatively large parasite in a small insect causing an increase in fat accumulation is intriguing. This challenges the intuitive assumption that the parasite would cause the host to lose weight/nutrients.