Meeting Abstract

109.2  Tuesday, Jan. 7 08:15  Identifying the molecular link between photosensitive tissues and the eyes of the bay scallop, Argopecten irradians. PAIRETT, A.N.; SERB, J.M.*; Iowa State University; Iowa State University apairett@iastate.edu

Molluscs utilize a vast array of photoreceptive structures, such as complex eyes capable of spatial vision or simple photoreceptive neurons found in the mantle tissue (extra-ocular photoreception, EOP). EOP is ubiquitous in molluscs, while spatial vision has evolved independently multiple times. This pattern suggests that, through the recruitment of photosensitive machinery from one system to another, EOP may be an evolutionary source for eyes. Scallops (Pectinidae) are well known for mirror-type eyes found along their mantle edge on modified tentacles, and represent an excellent opportunity to study the relationship of EOP and vision. Here we test whether the phototransduction system in the scallop eye is shared with EOP in the mantle by analysing gene expression in visual (eyes), putatively photoreceptive (mantle), and non-photoreceptive (adductor muscle) tissues from the bay scallop, Argopecten irradians. If the mantle functions in EOP, it will contain the molecular components of the phototransduction pathway, which are required for photoreception. We predict that photosensitive organs will show increased expression levels of photosensitive genes under light conditions when compared to a dark treatment. Illumina sequencing of the eye, mantle, and adductor muscle transcriptomes resulted in nearly 1.5 trillion reads, which were assembled into over 230,000 transcripts. Genes from the phototransduction pathway and circadian rhythm are shared between the mantle tissue and eyes, suggesting that the mantle tissue is photosensitive. However, only circadian rhythm genes showed differential expression between light and dark conditions in the mantle. Results from this work identifies possible links between two independent photoreceptive systems, thus implicating mechanisms that generated the diversity of molluscan eyes.