Investigation Of Plankton Diversity In Pearl River And The Application In Drowning Site Inference

Objective To investigate the diversity of plankton in Pearl River water by high-throughput sequencing.The consistency between animal experiments and drowning cases and diatoms was analyzed by Microwave Digestion-Vacuum Filtration-Automated Scanning Electron Microscopy method(MD-VF-Auto SEM)respectively,and the role of plankton in the prediction of drowning sites was explored,so as to provide the basis for the study of the location of drowning.Methods 1.In this study,four water sampling sites were set up in Guangzhou section of the Pearl River to collect water samples and extract DNA.The V4 variable region of 18 SrDNA gene was sequenced by highthroughput sequencing platform Illumina Hiseq.Sequence analysis and species annotation were carried out by Bioinformatics Method to understand the community composition of the Pearl River water body;alpha diversity and beta analysis were further used Diversity analysis can further compare the differences between different water extraction points.2.In this study,animal experiments and drowning cases were set up,and MDVF-Auto SEM was used The consistency of diatom species in tissue samples and water samples was compared by statistical analysis and cluster analysis:(1)animal experiment: 20 rabbits were divided into two groups,16 in the drowning group were drowned in the water tank with four water sampling points and placed for 24 hours for dissection;4 in the blank group were immediately executed for dissection;the lungs of each rabbit were taken Tissue 2 g.The quantity and species of diatoms(genera)in 20 experimental rabbit samples(lung and drowning fluid)were detected by MD-VF-Auto SEM.(2)Drowning cases: 93 drowning cases(liver,kidney,lung and water samples)were collected,and the quantity and species of diatoms were detected by MD-VF-Auto SEM.SPSS 24.0 was used to analyze the data.Results 1.Based on the V4 region of 18 SrDNA,about 583685 highquality sequences were obtained and 1289 OTUs were annotated.After species annotation,it was found that the species diversity of plankton in the four sampling sites was rich,covering 6 phylum 187 species,among which the species richness of the water sample in point 13 is the lowest,and the plankton in point 8 is quite different from the other three points.2.Animal experiment: the consistency of diatom species between lung tissue and water samples was 0.25-0.75.When the clustering distance was0-5,5-10 and 10-15,8 / 16,9 / 16 and 14 / 16 samples and water samples could be classified into one group respectively.Drowning cases: in 93 cases,the consistency of diatom types between closed organs(liver,kidney)and lung tissues,organs(liver,kidney,lung)and water samples was 0.48-0.73.In 30 cases with known drowning sites,the consistency was 0.57-0.67.When the clustering distance is 0-5,5-10 and 10-15,35 / 93,50 / 93 and 79/ 93 cases can be classified into one cluster respectively.Conclusion In the study of plankton diversity in the Pearl River,more species were identified by high-throughput sequencing technology.The diversity analysis found the difference of species composition between different water collection points.According to the different species,it provided an important basis for the establishment of plankton genetic markers and the construction of drowning site inference method.In animal experiments,although the location of drowning is determined,the inconsistency is about 50%,and the highest consistency is only 75%;in actual cases,the inconsistency rate is about 40% when the site of drowning is determined,and the consistency rate is 40% when the site of drowning is not determined;the consistency of diatoms in lung tissue and water sample is not a necessary condition for drowning diagnosis.It can be seen that in this study,we used high-throughput sequencing technology to investigate the plankton diversity in the Pearl River,and analyzed the population distribution and population sequence of plankton in the Guangzhou section of the Pearl River,which not only provided basic information for the biodiversity of the water in the Guangzhou section of the Pearl River,but also helped to find more drowning related plankton,and provided reference for forensic drowning identification and drowning site inference.