Author: Abegail R Bigasin,  Undergraduate (UC San Diego)

Designation: 

Description:
Nematocysts are specialized stinging organelles that fend off predators or catch prey, and are made only by cnidarians. However, four different metazoan phyla that prey on cnidarians have evolved the ability to sequester nematocysts for their own defense. Nematocyst sequestration is not well-studied; we do not fully understand how the animal is able to recognize the foreign organelles and incorporate them into its own cells. Nematocysts are endocytosed from digested food by specialized cnidophage cells that are housed in an organ called the cnidosac, which resides at the tips of cerata (dorsal appendages that contain branches of the digestive system). The proximal section of each ceras (plural: cerata) contains digestive tissue, whereas the distal section contains the cnidosac and cnidophages. Among the phylum Mollusca, the nudibranch gastropod Berghia stephanieae is an emerging research organism that possesses the ability to sequester nematocysts from the anemone Exaiptasia pallida. Taking advantage of growing genomic tools for Berghia, differential expression analysis was conducted on distal and proximal cerata, with the goal of identifying genes that are associated with cnidophage fate specification and function.  Using four different bioinformatics analysis packages we found 105 differentially expressed genes, of which 35 genes were upregulated in the distal cerata (where the cnidophages reside). In the near future in situ hybridization will be used to verify the location and expression of these genes. The four phyla that sequester nematocysts are also able to regenerate the sequestering tissues.  In Berghia, we observed that cerata regenerate robustly, and that the cnidosac regenerates very early on in the process.  By identifying genes up-regulated in distal cerata, we hope to look at the relationship between the genes involved in regeneration and those involved in nematocyst sequestration.

Category: Scientific Program Abstract > Special Sessions > SS01 ASLO Student Symposium