Studies Of Early Embryonic Development And Genetic Diversity Of Perinereris Aibuhitensis

In recent years, Perinereris aibuhitensis has received more and more attentions for itscommercial values and ecologic effects. In this study, samples of P.aibuhitensis werecollected from coastal Shandong Peninsula, and its early embryonic development andgenetic diversities were analyzed under controlled laboratory conditions. Resultsshowed that:1. The early embryonic developmentThe parental sampls of P. aibuhitensis are collected from the semi-artificially culturedpopulations at August2010. During July and August2011, some of the culturedpopulations is matured into heteronereis. Though the heteronereis can reproduce underartificial conditions when both male and female individuals (30~50) are pooled into oneplastic basket, the artifical fertilizing methods are applied in order to obtainsynchronously ontogenitic embryoes. After disinfection, the fertilized eggs are transferredinto cement pond for intermediate culture. When the embryoes develop into theontogentic stage of3-chaetae nectochaete on the3th day after incubation, the larvae arecollected from cement pond and put into mud pond for last cultivation. The earlyontogeny of P. aibuhitensis is observed under microscope (Olympus–CX31), and thetypical characteristic images are taken using charge-coupled device (CCD) and SONYH-50camera. There are some phenomena that are different from previous reports,including numbers of oil globules vs embryonic development, temperature vs embryonicdevelopment. One of pathogenic ciliate species emerged during the early developmentand resulted in mass death of embryo and larvae of P. aibuhitensis.2. Genetic diversityFour geographic populations of P. aibuhitensis were sampled from coastal ShandongProvince too investigate the genetic diversity, population structure and historicaldemography. A684base-pair fragment of mitochondrial DNA cytochrome oxidasesubunit I gene was analysed in92individuals. Results showed that the sampled P.aibuhitensis population had low haplotype diversity and nucleotide diversity. Topologies of neighbour-joining tree were shallow but the frequencies of common haplotypesindicated recent evolutionary lineages associated geographic areas. Significant geneticdifferentiations were detected among the four populations suggesting limited gene flow.Neutrality tests and mismatch distribution showed population expansion in P.aibuhitensis, however, samples collected from Yellow River Estuary and Jiaozhou Baymight meet a a recent bottleneck or selection.