The Culture And Complete Mitochondrial Genome Of Bosmina Fatalis

Bosmina is a cladoceran which is widely distributed throughout the world.Bosmina is fed by bacteria,phytoplankton and organic debris.At the same time,it is also the biological bait of fish and shrimp,and dominant specie of zooplankton in eutrophic water bodies.Thus,it plays an important role in freshwater ecosystems.In this study,Bosmina fatalis was cultivated in a single colony and its compositional features,structural features of the whole mitochondrial genome were analyzed by sequencing with Illumina Hiseq 4000 technology,and the phylogeny of B.fatalis was also explored.We hope to provide a molecular level basis for the cultivation,classification and evolution of B.fatalis.The culture conditions of B.fatalis were explored.We monoclonal culture of B.fatalis,and then four food density gradients of Chlorella pyrenoidosa and Scenedesmus obliquus were set at 0.05×106?0.1×106?0.2×106?0.4×106 cells/mL.B.fatalis was cultivated at a temperature of 25?,light intensity of 2000 lux and photoperiod L:D=13 H:11H.The results showed that compared with Chlorella pyrenoidosa,Scenedesmus obliquus was more suitable as the culture bait of B.fatalis.When the feeding density of Scenedesmus obliquus was 0.2×106 cells/mL,the population density and population growth rate of B.fatalis reached their maximum.The whole mitochondrial genome of B.fatalis was sequenced.The results showed that the total length of the mitochondrial genome sequence was 15209 bp,including 13 protein coding genes(PCGs),2 ribosomal RNA(rRNA)genes,22 transfer RNA(tRNA)genes and a non-coding control region.Among them,23 genes are located in the J chain and 14 genes are located in the N chain.The sum of base contents of A(adenine)and T(thymine)is 69.13%,and the sum of base contents of G(guanine)and C(cytosine)is 30.87%.The whole genome composition appears markedly A+T base biased.The phylogenetic relationship of B.fatalis in the dendrites was combed.Nine mitochondrial genome sequences of cladocerans were downloaded from GenBank.It was found that the length and base composition ratio of mitochondrial genome of B.fatalis were closer to those of five cladocerans of Daphnia.The neighbor joining(NJ)and maximum likelihood(ML)methods were used to construct a phylogenetic tree.The results showed that B.fatalis has a closer relative to Daphnia than to other cladocerans.This study provides basic data for species identification and evolution of B.fatalis,and also provides a reference for the cultivation of B.fatalis as the biological bait for fish and shrimp.