Expression of glucose (GLUT) and glycerol (GLP) transporters in symbiotic and bleached Cassiopea xamachana (Bigelow, 1892) jellyfish

Cassiopea xamachana is a tropical medusa that lives in symbiosis with dinoflagellate algae, serving as a model organism for symbiotic studies. The symbiosis is necessary for this medusa to complete its life cycle. The symbiotic partners maintain a metabolic exchange of organic molecules that constitute an important source of energy for the animal host, with free organic molecules, like glucose and glycerol, being the primary source. This molecular exchange can be facilitated by cellular internal membrane transport proteins, such as Glucose membrane transporters (GLUTs) and Glycerol transport-like aquaglyceroporins (GLP-like), probably located at the symbiosomal interface. The present study was conducted in October 2021, evaluating the expression of transporter coding genes GLUT3, GLUT8, and GLP9 (two genes) by qPCR under conditions of symbiosis and after the loss of symbionts. Symbiotic medusae donated from Xcaret Park, Mexico (20° 34′ 24.59″ N; -87° 07′ 5.40″ W) were sampled and compared to medusae with an experimental decrease of algal symbionts. In agreement with glucose being an important mobile molecule, our results showed higher transcription levels for glucose transporters GLUT3 and GLUT8 in control compared to bleached medusae. By contrast, bleached medusae showed a higher expression of aquaglyceroporin transporters GLP9-1 and GLP9-2, probably associated with glycerol production after lipid catabolism, to compensate for lower organic carbon levels due to the loss of symbionts. Our results highlight the importance of free carbon molecules transported from symbiont to host and agree with glucose being an energy fuel for this symbiotic association.