Compared with other aquatic organic groups, the size of plankton is very small but its number is very high and its metabolic activity is very strong. So planktons play a key role in ecology system. In this thesis, using freshwater plankton community as studying object, we carried through some research by applying DNA fingerprinting technology as follows:
1. DNA polymorphism of plankton community at different trophic levels in Donghu Lake was studied by RAPD fingerprinting, and the relationship between DNA fingerprinting structure of the targeted plankton community and major environmental physical-chemical factors was analyzed. Nine of 60 screened random primers amplified a total of 210 observable bands, 93.3% of which were polymorphic and the lengths of the bands were between 150 bp and 2000 bp. The mean number of amplified bands at the five stations was 42, samples from station IV had the maximum number (53) and station V got the minimum (35). The contents of PO4-P and T-P at station І were the highest; the contents of NH4-N, T-N and NO2-N at station V were the highest; the contents of all physicochemical factors, except NO2-N, at station IV were the lowest; the contents of COD, Basicity, Hardness and Calcium showed low distinction. Clustering analysis based on RAPD marker showed that the five stations could be divided into two groups: stations I, II and III clustered into one group, station IV and V clustered into another group. This group relation was consistent with the clustering analysis based on the physicochemical factors. The study suggests: DNA fingerprinting structure of plankton community was closely related to the major environmental physiochemical factors. The accumulation about this kind of correlative materials will benefit to construct simple but potent water quality assessing system.
2. The composition of eukaryotic plankton community in Qiaodun Lake and Niushan Lake was compared, and meanwhile the relationship between 18S rDNA topology structure of plankton community and environmental physiochemical parameters was analyzed by DGGE fingerprinting. The result shows: ① 10 sites from two lakes amplified 81 bands in all
with 1 mutual band. 5 sites from Qiaodun Lake amplified 27 bands with 2 mutual bands; 5 sites from Niushan Lake amplified 54 bands with 5 mutual bands and no special bands. The analysis of 10 sites clustering based on DGGE marker shows: N1、N3、N4、N5 grouped into a cluster, Q1、Q2、Q3、Q5 clustered together, subsequently grouped Q4、N2 into another cluster. ② The physioemical parameters clustering of Qiaodun Lake was Q1、Q2、Q3、Q5 grouped into a cluster and Q4 comprised a single cluster, according to clustering based on DGGE marker. Maybe this correlates with water eutrophic state and the content of total phosphorus in Site Q4 was the highest; The physiochemical parameters clustering of Niushan Lake was N3、N4 grouped into a cluster and N1、N2、N5 grouped into a cluster. clustering based on DGGE marker divided N1、N2、N5 further. In conclusion, DNA fingerprinting of plankton community is closely related to major physical-chemical factors. Clustering based on DGGE marker indicated the discrepancy of plankton community from two lakes. Therefore, DGGE fingerprinting is potent for analyzing the difference of plankton community composition. This will accumulate information for studying population dynamics and community ecology.