Fig. 3

Allele-specific disruption of the GH/IGF-1 axis correlates with impaired bone mineralization. (A–C) µCT analysis of the caudal fin and vertebrae in adult WT and gon4laⁿⁿ²¹¹² mutants (3 mpf). (A) Representative images showing labeled endochondral bones (parhypural, PH; hypurals, H1–H6) and vertebral length (V, yellow lines). (B, C) Quantification of absolute bone lengths and relative ratios to standard length, demonstrating that nn2112 mutants exhibit proportionate dwarfism (n = 5–6/group). (D) qRT-PCR analysis of GH/IGF-1 axis disruption (gh1a, ghra, igf1a) in gon4laⁿⁿ²¹¹². The significant reduction in hepatic igf1a is accompanied by compensatory upregulation of gh1a and ghra, characteristic of GH insensitivity (n = 6/group). (E) Comparative qRT-PCR analysis of hepatic igf1a expression across different gon4la mutant alleles. Note that igf1a levels are significantly compromised only in nn2112, while nn2123 and nn2131 show no statistically significant difference from WT siblings. Expression levels are normalized to that of gapdh. (F, G) Vertebral BMD is only significantly reduced in gon4laⁿⁿ²¹¹² (n = 5–6/group), which aligns with the loss of igf1a expression. Statistical analysis: *, p < 0.05; **, p < 0.01; ***, p < 0.001.