Meeting Abstract

29.5  Wednesday, Jan. 4  Developmental potential of embryonic cells to generate larval and juvenile eyes in the polychaete Capitella teleta YAMAGUCHI, Emi*; SEAVER, Elaine C; University of Hawaii at Manoa, Kewalo Marine Lab; University of Hawaii at Manoa, Kewalo Marine Lab emiy@hawaii.edu

In spiralian animals, a common stereotypic cleavage program gives rise to adult animals with diverse body plans, such as polychaete annelids and bivalve mollusks. The spiral cleavage program allows for the unique identification of cells in the early embryo, which in many cases give rise to similar body regions across a broad range of taxa. In this study, we address the developmental potential of cells to generate eyes, a complex sensory organ, in the polychaete annelid Capitella teleta. In C. teleta and many other spiralians, the larval eyes are generated by the 1a and 1c lineages. We used single-cell laser ablation techniques to experimentally delete the 1a or 1c lineage, which resulted in larvae missing the left or right eye, respectively. Our results suggest that the eyes are specified by 1a and 1c as early as the 8-cell stage in C. teleta, and other cells are unable to regulate for the loss of these cells. Double ablation of both the 1a and 1c cells results in animals with no eyes and a reduced head. Ablations for the daughter cells of 1a and 1c that generate the eyes, 1a¹ and 1c¹, resulted in larvae missing the left or right eye, respectively. In addition, we addressed the question of larval eye regeneration and the origin of the adult eyes through direct ablation of the larval eyes. When the left eye is ablated in a larval stage animal, the eye does not regenerate, even after several days. The left eye is also missing in post-metamorphic juveniles, suggesting that the cells of the larval eyes contribute to the juvenile/adult eyes. These results suggest that the potential for eye development is strictly confined very early in the embryo to the lineages that eventually generate the eye, and it is likely that no other cells have the potential to develop eyes.