Estimating Mortality Risks Associated with Starvation for Atlantic Cod Larvae using Molecular Markers and Cox Regression Models

使用分子标记和 Cox 回归模型估计与大西洋鳕鱼幼虫饥饿相关的死亡风险

• 批准号: 9730712
• 负责人: Tun-Liang Ong
• 金额: $ 24.01万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-03-01 至 2001-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9730712&HistoricalAwards=false
• 关键词: Estimating; Mortality; Risks; Associated; Starvation

Based on laboratory feeding experiments, this effort focuses on demonstrating the feasibility of using molecular markers coupled with statistical modeling for estimation of starvation-induced mortality in larval Atlantic cod. Our earlier studies have established that bulk RNA, 18S ribosomal RNA (rRNA) and metallothionein (MT) mRNA levels may serve as specific markers for starvation in cod larvae. A series of laboratory experiments will be completed to further characterize the responses of 18s rRNA and MT to changes in feeding, development and growth in Atlantic cod. Laboratory results (molecular biology and survival data) will be used to calibrate a Cox regression model for estimation of starvation mortality risks in larval Atlantic cod. The nonproportional hazards Cox regression model chosen for this study is commonly used by the life insurance industry for establishing risks and premium rates. It can accommodate time-dependent covariates, time-lagged effect, and a stepwise change in hazard rates over the lifespan of the organism studied. Our earlier work established that significant decreases18s rRNA levels can be used as a marker for the initial stages of starvation in Atlantic cod larvae. Dramatic increases in MT mRNA levels also were shown to be indicative of starvation. Both markers will be used to pinpoint recovery from starvation after refeeding. The power of mortality risks estimation will greatly increase if recovery from starvation can be established. A single marker alone may not be able to define the `point-of-no-return` in starvation with sufficient confidence. Animal and human studies have shown that dietary deprivation leads to polysome breakdown and a reduction in the number and activity of ribosomes. Refeeding after starvation results in significant increase in the levels of rRNAs. However, when starvation has exceeded the `point-of-no-return`, i.e. rRNA levels fail to rebound after refeeding, mortality sets in. To the extent that Atlantic cod is a suitable model for other fish and invertebrates that produce planktonic larvae, this effort will provide a picture of the molecular response of larvae to changing feeding conditions and provide tools to determine growth, starvation mortality and feeding conditions. These studies should provide insight into the effects of environmental variability on production of fish.

实验室饲养实验的基础上，这项工作的重点是证明的可行性，利用分子标记加上统计模型估计饥饿诱导的死亡率在大西洋鳕鱼幼虫。 我们早期的研究已经建立了散装RNA，18S核糖体RNA（rRNA）和金属硫蛋白（MT）的mRNA水平可能作为饥饿的鳕鱼幼虫的特异性标记。 将完成一系列的实验室实验，以进一步表征18s rRNA和MT的反应，在大西洋鳕鱼的摄食，发育和生长的变化。 实验室结果（分子生物学和存活数据）将用于校准考克斯回归模型，以估计大西洋鳕鱼幼鱼的饥饿死亡风险。 本研究所选用的非比例风险考克斯回归模型是寿险业常用的风险和费率模型。 它可以容纳时间依赖的协变量，时滞效应，并在研究的生物体的寿命的风险率的逐步变化。 我们早期的工作表明，18s rRNA水平的显著下降可以作为大西洋鳕鱼幼鱼饥饿初始阶段的标志。 MT mRNA水平的急剧增加也表明饥饿。 这两种标记物将用于确定重新喂食后从饥饿中恢复的情况。 如果能够从饥饿中恢复，估计死亡风险的能力将大大增加。 单靠一个标记可能无法足够有把握地确定饥饿的“不归路”。 动物和人类研究表明，饮食剥夺导致多核糖体分解和核糖体数量和活性的减少。 饥饿后再喂食导致rRNA水平显著增加。 然而，当饥饿超过“不归点”时，即rRNA水平在重新喂食后未能反弹时，死亡率开始上升。 在某种程度上，大西洋鳕鱼是其他鱼类和无脊椎动物，产生浮游幼虫的一个合适的模型，这项工作将提供一个图片的分子反应的幼虫不断变化的喂养条件，并提供工具，以确定增长，饥饿死亡率和喂养条件。这些研究应有助于深入了解环境变化对鱼类生产的影响。