Sordino Paolo, Andreakis Nikos, Brown Euan R, Leccia Nicola I, Squarzoni Paola, Tarallo Raffaella, Alfano Christian, Caputi Luigi, D'Ambrosio Palmira, Daniele Paola, D'Aniello Enrico, D'Aniello Salvatore, Maiella Sylvie, Miraglia Valentina, Russo Monia Teresa, Sorrenti Gerarda, Branno Margherita, Cariello Lucio, Cirino Paola, Locascio Annamaria, Spagnuolo Antonietta, Zanetti Laura, Ristoratore Filomena
Laboratory of Biochemistry and Molecular Biology, Stazione Zoologica Anton Dohrn, Naples, Italy.
PLoS One. 2008 Jun 4;3(6):e2344. doi: 10.1371/journal.pone.0002344.
The study of ascidians (Chordata, Tunicata) has made a considerable contribution to our understanding of the origin and evolution of basal chordates. To provide further information to support forward genetics in Ciona intestinalis, we used a combination of natural variation and neutral population genetics as an approach for the systematic identification of new mutations. In addition to the significance of developmental variation for phenotype-driven studies, this approach can encompass important implications in evolutionary and population biology.
METHODOLOGY/PRINCIPAL FINDINGS: Here, we report a preliminary survey for naturally occurring mutations in three geographically interconnected populations of C. intestinalis. The influence of historical, geographical and environmental factors on the distribution of abnormal phenotypes was assessed by means of 12 microsatellites. We identified 37 possible mutant loci with stereotyped defects in embryonic development that segregate in a way typical of recessive alleles. Local populations were found to differ in genetic organization and frequency distribution of phenotypic classes.
CONCLUSIONS/SIGNIFICANCE: Natural genetic polymorphism of C. intestinalis constitutes a valuable source of phenotypes for studying embryonic development in ascidians. Correlating genetic structure and the occurrence of abnormal phenotypes is a crucial focus for understanding the selective forces that shape natural finite populations, and may provide insights of great importance into the evolutionary mechanisms that generate animal diversity.
海鞘（脊索动物门，被囊动物亚门）的研究为我们理解基础脊索动物的起源和进化做出了重大贡献。为了提供更多信息以支持玻璃海鞘的正向遗传学研究，我们采用自然变异和中性群体遗传学相结合的方法来系统鉴定新突变。除了发育变异对表型驱动研究的重要性外，这种方法在进化生物学和群体生物学中也具有重要意义。
方法/主要发现：在此，我们报告了对三个地理上相互关联的玻璃海鞘群体中自然发生突变的初步调查。通过12个微卫星评估历史、地理和环境因素对异常表型分布的影响。我们鉴定出37个可能的突变位点，其胚胎发育存在典型缺陷，且以隐性等位基因的典型方式分离。发现当地群体在遗传结构和表型类别的频率分布上存在差异。
结论/意义：玻璃海鞘的自然遗传多态性是研究海鞘胚胎发育的宝贵表型来源。将遗传结构与异常表型的出现相关联是理解塑造自然有限群体的选择力的关键重点，并且可能为产生动物多样性的进化机制提供极其重要的见解。
