DISSERTATION RESEARCH: Estimating the Somatic Mutation Rate of the Tree Delonix regia

生物体中的突变可能有两种方式之一：一种是减数分裂突变，出现在精子和卵子的产生过程中；另一种是体细胞突变，出现在正常细胞分裂和生长过程中的DNA复制过程中。典型的体细胞突变率基本上是未知的，但似乎比减数分裂突变率低许多倍。在生长受限的短命生物中，减数分裂突变率对整体突变率有很大影响。然而，在树木等长寿生物中，细胞在生长过程中可能会分裂数百万次。因此，突变率可能受体细胞突变的影响更大。该项目将估计热带大树Delonix Regia的体细胞突变率。将检查在大枝条的底部和顶端产生的花在几种花粉适合性指标上的差异，并估计分开花的细胞分裂的数量。这些估计将用于确定每个细胞分裂的体细胞突变率和每个体细胞突变的平均影响。突变率的知识对生物学的许多领域都很重要。特别是体细胞突变会对人类福利产生巨大影响(例如，通过引发癌症)，这里测量的体细胞突变率可以被其他科学家用来确定它们发生的一般可能性。

Mutations in organisms may arise one of two ways: as either a meiotic mutation, which appears during the production of sperm and eggs, or as a somatic mutation, which appears during the duplication of DNA that occurs during normal cell division and growth. The typical rate of somatic mutation is essentially unknown, but appears to be many times less than the rate of meiotic mutation. In short-lived organisms with limited growth, the overall mutation rate is strongly influenced by the rate of meiotic mutation. In long-lived organisms such as trees, however, cells may divide millions of times during growth. Thus, the rate of mutation may be more strongly influenced by somatic mutation. This project will estimate the rate of somatic mutation in the large tropical tree Delonix regia. Flowers produced at the base and apex of large branches will be examined for differences in several measures of pollen fitness, and the number of cell divisions separating flowers will be estimated. These estimates will be used to determine the rate of somatic mutation per cell division and the average effect of each somatic mutation. Knowledge of mutation rates is of fundamental importance to many areas of biology. Somatic mutation in particular can have dramatic impact on human welfare (e.g., by giving rise to cancers), and the rate of somatic mutation rate measured here may be used by other scientists seeking to determine the general likelihood of their occurrence.