Decline in Constitutive Proliferative Activity in the Zebrafish Retina with Ageing

Supplementary Materials The following are available online at https://www.mdpi.com/article/10.3390/ijms222111715/s1. Table S1: Studies demonstrating the presence of proliferating cells in the juvenile/adult retina of different teleost species. File S1: Mean ± S.E.M. data and data on statistical multiple comparisons related to graphs shown in Figure 2; File S2: Mean ± S.E.M. data and data on statistical multiple comparisons related to graphs shown in Figure 3.It is largely assumed that the teleost retina shows continuous and active proliferative and neurogenic activity throughout life. However, when delving into the teleost literature, one finds that assumptions about a highly active and continuous proliferation in the adult retina are based on studies in which proliferation was not quantified in a comparative way at the different life stages or was mainly studied in juveniles/young adults. Here, we performed a systematic and comparative study of the constitutive proliferative activity of the retina from early developing (2 days post-fertilisation) to aged (up to 3–4 years post-fertilisation) zebrafish. The mitotic activity and cell cycle progression were analysed by using immunofluorescence against pH3 and PCNA, respectively. We observed a decline in the cell proliferation in the retina with ageing despite the occurrence of a wave of secondary proliferation during sexual maturation. During this wave of secondary proliferation, the distribution of proliferating and mitotic cells changes from the inner to the outer nuclear layer in the central retina. Importantly, in aged zebrafish, there is a virtual disappearance of mitotic activity. Our results showing a decline in the proliferative activity of the zebrafish retina with ageing are of crucial importance since it is generally assumed that the fish retina has continuous proliferative activity throughout life.This research was funded by Ministerio de Economía Industria y Competitividad (to E.C.), grant number BFU-2017-89861-P; Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación (to A.B.-I.), grant number PID2020-115121GB-I00; Xunta de Galicia (to E.C.), grant number ED431C 2021/18; Xunta de Galicia (to I.H.-N.), grant number ED 481 A2018 216. “The APC was funded by the Xunta de Galicia”. Grants were partially financed by the European Social Fund.S