Laboratorio de Fisiología y Genética Marina (FIGEMA), Centro de Estudios Avanzados en Zonas Áridas (CEAZA) & Universidad Católica del Norte, 1781421 Coquimbo, Chile.
Laboratorio de Fisiología y Genética Marina (FIGEMA), Centro de Estudios Avanzados en Zonas Áridas (CEAZA) & Universidad Católica del Norte, 1781421 Coquimbo, Chile; Programa de Magister en Ciencia del Mar mención Recursos Costeros, Facultad de Ciencias del Mar, Universidad Católica del Norte, 1781421 Coquimbo, Chile.
J Invertebr Pathol. 2017 Nov;150:15-20. doi: 10.1016/j.jip.2017.08.014. Epub 2017 Sep 1.
Withering syndrome disease has experienced worldwide spread in the last decade. This fatal disease for abalone is produced by a rickettsia-like organism (WS-RLO), the bacterium "Candidatus Xenohaliotis californiensis". To evaluate the potential of the red abalone (Haliotis rufescens) to improve its resistance to infection by WS-RLO, the additive genetic component in the variation of this trait was estimated. For this, the variation in infection intensity with WS-RLOs and WS-RLOv (phage-infected RLOs) was analyzed in 56 families of full-sibs maintained for three years in a host-parasite cohabitation aquaculture system. A WS-RLO prevalence of 65% was observed in the analysed population; and from the total WS-RLO inclusions 60% were hyperparasited with the phage (WS-RLOv). The decrease in the food ingestion rate was the sole negative effect associated with increasing WS-RLO intensity of infection, suggesting that the high level of WS-RLOv load may have diminished the symptoms of WS disease in the analyzed abalones. The estimated heritabilities were moderate to mid, but significant, varying from 0.21 to 0.23 and 0.36 for WS-RLO and WS-RLOv infections, respectively. This suggests that variation in resistance to infection with WS-RLO may respond to selection in the evaluated red abalone population. Estimated response to selection (G) for the level of infection by WS-RLO indicated that if the 10% of red abalone with the lowest infection level is selected as broodstock, a 90% reduction in the intensity of infection in the progeny can be expected, even with the lowest estimation of heritability (h=0.21). This strong response would be also due to the large phenotypic variance of this trait. Strong positive correlations, both phenotypic and genotypic, were observed between infection intensities with WS-RLO and WS-RLOv, indicating that selection to increase resistance to one of the types of RLOs will affect resistance in the other in the same direction. This is the first study that demonstrates the existence of additive genetic variation for resistance to WS-RLO in abalone. Consequently, it is possible to increase the resistance to WS-RLO in H. rufescens by selective breeding, which can be an economically attractive and environmentally friendly manner to reduce mortalities and growth effects caused by WS in abalone farms.
在过去的十年中，萎缩症疾病在世界范围内传播。这种对鲍鱼致命的疾病是由一种类似立克次体的生物体（WS-RLO），即细菌“Candidatus Xenohaliotis californiensis”引起的。为了评估红鲍（Haliotis rufescens）提高对 WS-RLO 感染的抵抗力的潜力，估计了该性状变异的加性遗传成分。为此，在宿主-寄生虫共栖水产养殖系统中维持了三年的 56 个全同胞家系中，分析了 WS-RLO 和 WS-RLOv（感染噬菌体的 RLO）感染强度的变异。在所分析的种群中观察到 65%的 WS-RLO 流行率；并且在总 WS-RLO 包含物中，有 60%被噬菌体（WS-RLOv）过度寄生。随着 WS-RLO 感染强度的增加，食物摄入率的下降是唯一与负面相关的因素，这表明高水平的 WS-RLOv 负荷可能减轻了分析鲍鱼中的 WS 疾病症状。估计的遗传力从中等到中等，但显著，分别为 0.21 到 0.23 和 0.36，用于 WS-RLO 和 WS-RLOv 感染。这表明，对 WS-RLO 感染的抵抗力的变异可能对评估的红鲍种群中的选择有反应。对 WS-RLO 感染水平的选择反应（G）的估计表明，如果选择感染水平最低的 10%的红鲍作为亲鱼，则可以预期后代感染强度降低 90%，即使遗传力的最低估计值（h=0.21）。这种强烈的反应也归因于该性状的大表型方差。WS-RLO 和 WS-RLOv 感染强度之间观察到了强烈的表型和基因型正相关，表明对一种 RLO 类型的抗性选择将以相同的方向影响另一种类型的抗性。这是第一项证明鲍鱼对 WS-RLO 具有加性遗传变异的研究。因此，可以通过选择性繁殖来提高 H. rufescens 对 WS-RLO 的抗性，这是一种经济上有吸引力且对环境友好的方式，可以减少 WS 对鲍鱼养殖场造成的死亡率和生长影响。
