Investigation Of The Characteristics Of Brachionus Plicatili As A Genetic Material

Brachionus plicatili, a euryhaline species from the kingdom of Rotifera, is widelydistributed in both freshwater and marine environments. They play a critical role inaquatic ecosystem by supplying aquaculture organisms as prominent parts of theirfood web, thus possessing significance in both economy and scientific research.B.plicatili can be obtained from various sources, are small in size, and can grow easilyunder laboratory conditions, characteristics that make them an ideal subject forscientific study. Their life cycle is comprised of two stages: parthenogenesis andsexual reproduction, one alternating with the other. During parthenogenesis, femalesproduce diploid amictic eggs through mitosis to clone themselves; while in sexualreproduction stage, females generate haploid mictic eggs by meiosis, which developinto males if not fertilized and into resting eggs if fertilized. Those resting eggs havethick outer shells, a characteristic that renders them both the resistance to harshenvironments and the ability to hatch under favorable conditions in order to start anew round of parthenogenesis.In present study, we established the laboratory protocols for artificially culturingB.plicatili over their alternating life cycle, effectively inducing sexual reproductionand hatching of resting eggs. We also explored experimental methods for self-crossingand hybridization that can be applied to genetics research. The progenies ofsuccessive self-crossing or out-crossing were obtained, respectively. An enrichedgenomic microsatellite DNA library of B.plicatili by the method of FIASCO wasconstructed, from which a number of microsatellite DNA markers have been screenedand obtained. Based on their sequences, primers were designed to amplify thosepolymorphic microsatellite DNA sites. Their PAGE banding patterns allowed us to analyze the purity of offspring after successive self-crossing as well as the separatingpatterns of parental polymorphic DNA elements in their progenies duringhybridization experiments. For example, after successive self-crossing, the F4offspring of a parent that was heterozygous at one microsatellite locus, contained bothhomozygous and heterozygous individuals, with the homozygous ones occupyingabout85%. In hybridization experiments, the parental DNA markers showedsegregation in offspring, in accordance with the classical Mendel’s law of independentsegregation, thus confirming the feasibility of our experimental hybridization protocol.The ploidy of B.plicatili chromosome was also investigated here based our crossingresults. In sum, our research suggests that B.plicatili is easy to culture in laboratory,has valuable scientific and economic significance, suitable in genetic manipulations,and possesses a prominent potential to be another laboratory genetic material.However, due to current lack of a sufficient understanding of its genetic properties,more efforts are still needed in order to make B.plicatili a mature genetic subject ormodel organism.