Supplementary Material for: Comparative cytogenetic analysis of diploid and triploid pacific abalone, Haliotis discus hannai

Cytogenetic analysis of triploid Haliotis discus hannai larvae (produced by chemical treatment) and its diploids were performed. The results showed that triploid H. discus hannai had a chromosome number of 3n = 54, consisting of 30 metacentric (m) and 24 submetacentric (sm) chromosomes, while the diploids had a chromosome number of 2n = 36, consisting of 20 metacentric (m) and 16 submetacentric (sm) chromosomes. Notably, both triploids and diploids displayed variation in the number of NORs and/or their diameter. The average number of NORs was significantly higher in triploids than in diploids (P < 0.05), while there was no significant difference in the average diameter of NORs between the two groups (P > 0.05). Additionally, 5S rDNA localization to 3 submetacentric chromosomes was observed in triploids, compared to 2 submetacentric chromosomes in diploids. The number of 18S rDNA sites displayed positional conservancy and quantitative variability in both diploids and triploids. Specifically, 18S rDNA was found at the end of the chromosome in both groups, with triploids exhibiting a significantly higher number of loci than diploids (P < 0.01). This study provides valuable insights into the cytogenetic characteristics of triploid H. discus hannai, which could facilitate further research on the stability of the chromosome set in this species.

本研究对经化学诱导产生的三倍体皱纹盘鲍（Haliotis discus hannai）幼虫及其二倍体个体开展了细胞遗传学分析。结果显示，三倍体皱纹盘鲍的染色体数目为3n=54，包含30条中着丝粒（m）染色体与24条亚中着丝粒（sm）染色体；其二倍体个体的染色体数目为2n=36，包含20条中着丝粒（m）染色体与16条亚中着丝粒（sm）染色体。值得注意的是，三倍体与二倍体个体均存在核仁组织区（NOR）数目及其直径的变异。三倍体个体的核仁组织区平均数目显著高于二倍体（P<0.05），但两组个体的核仁组织区平均直径无显著差异（P>0.05）。此外，三倍体个体中可观察到5S核糖体DNA（5S rDNA）定位在3条亚中着丝粒染色体上，而二倍体个体仅定位在2条亚中着丝粒染色体上。18S核糖体DNA（18S rDNA）位点数目在二倍体与三倍体个体中均表现出位置保守性与数量变异性。具体而言，两组个体的18S rDNA均位于染色体末端，且三倍体个体的位点数目显著高于二倍体（P<0.01）。本研究阐明了三倍体皱纹盘鲍的细胞遗传学特征，可为该物种染色体组稳定性的后续研究提供重要参考依据。