Evolutionary and Developmental Specialization of Foveal Cell Types in the Marmoset

In primates, high-acuity vision is mediated by the fovea, a small specialized central region of the retina. The fovea, unique to the anthropoid lineage among mammals, undergoes notable neuronal morphological changes during postnatal maturation. However, the degree of cellular similarity across anthropoid foveas and the molecular underpinnings of foveal maturation remain unclear. Here, we used high throughput single cell RNA sequencing (scRNA-seq) to profile retinal cells of the common marmoset (Callithrix jacchus), an early divergent in anthropoid evolution from humans, apes, and macaques. We generated atlases of the marmoset fovea and peripheral retina for both neonates and adults. Foveal and peripheral retina tissues were dissected from neonatal and adult marmoset retinas. The foveal piece (~1.5mm in diameter) of the retina containing the whole fovea area was dissected out and dissociated into individual cells for high throughput droplet-based single cell RNA sequencing (scRNA-seq, 10x Genomics). The peripheral area (any area 5mm away from the foveal center) was also dissociated into a single cell suspension and underwent two enrichment procedures. We first used CD73, a photoreceptor marker, to label photoreceptors and used a microbeads-conjugated secondary antibody to deplete all the CD73 labeled cells (1). Second, we enriched RGCs and ACs with CD90 positive selection via fluorescence-activated cell sorting (FACS). The peripheral cells after CD73 depletion or CD90 enrichment were used to generate scRNA-seq libraries (10X Genomics). Libraries were sequenced on the Illumina HiSeq 2500 platform.