Fig. 1

A Effects of zebrafish Insl3 on four relaxin family peptide receptors (Rxfps) expressed in HEK293T cells transiently transfected with pcDNA3.1 and pCRE plasmids. Data are expressed as mean ± SEM (N = 3, technical replicates). Numbers in brackets indicate the EC₅₀ concentrations. AU, arbitrary units. B Expression levels of responsive Insl3 receptors in control, germ cell-depleted (by exposure to the cytostatic agent busulfan⁵¹), and testes with recovering (from busulfan) spermatogenesis, as described by Crespo et al.²⁵ (NCBI GEO data set GSE116611). Data are expressed as mean ± SEM (N = 5; *p < 0.05). C, D Localization of rxfp2a:EGFP (green; C) and rxfp2b:mCherry signal (red; D) in adult testis tissue. Confocal laser scanning microscopy analysis of whole-mount testes shows preferential expression of EGFP and mCherry in type A spermatogonia and Sertoli and myoid cells, respectively. DAPI counterstain is shown in gray. Representative germ cell types (insets 1–4) and Sertoli and myoid cells are shown (insets 5–6). A_und, type A undifferentiated spermatogonia; A_diff, type A differentiating spermatogonia; B, type B spermatogonia; SPC, spermatocytes. In D, red and white arrowheads indicate representative mCherry⁺ and mCherry⁻ somatic cells, respectively. Scale bars, 25 µm.