Diplostomum spp

Ubels, John L., DeJong, Randall J., Hoolsema, Brittany, Wurzberger, Amy, Nguyen, Thuy-Tien, Blankespoor, Harvey D. & Blankespoor, Curtis L., 2018, Impairment of retinal function in yellow perch (Perca flavescens) by Diplostomum baeri metacercariae, International Journal for Parasitology: Parasites and Wildlife 7 (2), pp. 171-179 : 172

2.2. Examination of eyes for infection by Diplostomum spp .

Perch and common shiners were anesthetized with tricaine methane sulphonate (MS-222), 100 mg /l in water buffered to pH 7 with NaHCO 3, and doubly pithed. Spottail shiners were decapitated.

To examine spottail shiner lenses for infection, the eyes, which are about 2–3 mm in diameter, were removed from the fish and pierced with a #10 triangular scalpel blade. The lens was expressed into Ringer solution using fine forceps and examined for the presence of metacercariae and lens opacities using a dissecting microscope. Lenses were also macerated in Ringer solution using fine forceps and Vanness scissors to release metacercariae for DNA sequencing.

For examination of perch and common shiner eyes, which are 6–7 mm in diameter, the cornea was removed from the eye. The lens was carefully removed using forceps and examined as described above. The remaining eyecup was examined under a dissecting microscope for the possible presence of metacercariae in the vitreous humor. The retina and choroid were then removed and macerated in Ringer solution using fine forceps and dissecting needles, and the tissue and Ringer solution were examined for the presence of metacercariae. Common shiner and perch lenses were macerated to release metacercariae for DNA sequencing.