Figure 7.

Schematic representation of the effects of follicle-stimulating hormone (Fsh) and two downstream mediators, Igf3 and 11-KT, on IGF-binding protein (igfbp) transcript levels and potential roles of Igfbps in adult zebrafish testis. (A) Fsh rapidly reduced transcript levels of subgroup 2 (consisting of igfbp1a, -3, and -6a) and increased the expression/release of Igf3 and 11-ketotestosterone (11-KT). Igf3 also reduced the transcript levels of subgroup 2 members whereas those of subgroup 3 (consisting of igfbp1b, -2b, -5a, and -6b) were increased by Fsh and 11-KT. The transcript levels of subgroup 1 (consisting of igfbp2a and -5b) were not modulated in the present experiments. (B) Schematic representation of the igfbp transcript levels and their hormonal regulation in zebrafish testis tissue. The representation of the igfbp transcript amounts reflects read numbers from RNAseq data (Crespo, Bogerd, and Schulz, unpublished data) from 5 testes of normal adult males. The mean read numbers were transformed using the logarithm to the base 2, i.e., the scale covers a 1024-fold (2¹⁰) difference in average read numbers.