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High genetic diversity and novelty in eukaryotic plankton assemblages inhabiting saline lakes in the Qaidam basin.

Wang J, Wang F, Chu L, Wang H, Zhong Z, Liu Z, Gao J, Duan H - PLoS ONE (2014)

Bottom Line: Notably, Chlorophyta group are only found in high abundance in Lake Gasikule (28.00%), whereas less represented in other hypersaline lakes such as Gahai (0.50%) and Xiaochaidan (1.15%).Out of the parameters, four show significant correlation to this CCA: altitude, calcium, sodium and potassium concentrations.The identified diversity and novelty patterns among eukaryotic plankton assemblages in saline lake are of great importance for understanding and interpreting their ecology and evolution.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, China; Institute of Shandong River Wetlands, Laiwu, China.

ABSTRACT
Saline lakes are intriguing ecosystems harboring extremely productive microbial communities in spite of their extreme environmental conditions. We performed a comprehensive analysis of the genetic diversity (18S rRNA gene) of the planktonic microbial eukaryotes (nano- and picoeukaryotes) in six different inland saline lakes located in the Qaidam Basin. The novelty level are high, with about 11.23% of the whole dataset showing <90% identity to any previously reported sequence in GenBank. At least 4 operational taxonomic units (OTUs) in mesosaline lakes, while up to eighteen OTUs in hypersaline lakes show very low CCM and CEM scores, indicating that these sequences are highly distantly related to any existing sequence. Most of the 18S rRNA gene sequence reads obtained in investigated mesosaline lakes is closely related to Holozoa group (48.13%), whereas Stramenopiles (26.65%) and Alveolates (10.84%) are the next most common groups. Hypersaline lakes in the Qaidam Basin are also dominated by Holozoa group, accounting for 26.65% of the total number of sequence reads. Notably, Chlorophyta group are only found in high abundance in Lake Gasikule (28.00%), whereas less represented in other hypersaline lakes such as Gahai (0.50%) and Xiaochaidan (1.15%). Further analysis show that the compositions of planktonic eukaryotic assemblages are also most variable between different sampling sites in the same lake. Out of the parameters, four show significant correlation to this CCA: altitude, calcium, sodium and potassium concentrations. Overall, this study shows important gaps in the current knowledge about planktonic microbial eukaryotes inhabiting Qaidam Basin (hyper) saline water bodies. The identified diversity and novelty patterns among eukaryotic plankton assemblages in saline lake are of great importance for understanding and interpreting their ecology and evolution.

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Novelty pattern plot for the different eukaryal classes found in mesosaline lake and hypersaline lake.(A) mesosaline saline, (B) hypersaline. Closest environmental match (CEM) and the closest cultured match (CCM) available in GenBank (BLAST search, May 2014). Dots below 61% similarity in both axes indicated no similarity sequences.
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pone-0112812-g006: Novelty pattern plot for the different eukaryal classes found in mesosaline lake and hypersaline lake.(A) mesosaline saline, (B) hypersaline. Closest environmental match (CEM) and the closest cultured match (CCM) available in GenBank (BLAST search, May 2014). Dots below 61% similarity in both axes indicated no similarity sequences.

Mentions: After water samples were obtained and sequenced, the identity of the different microorganisms was analyzed by BLAST search. For each OTUs, the similarity to the CEM and the CCM was recorded (Figure 6). The results were further classified according to salinity concentration (i.e., mesosaline vs. hypersaline, Figure 6A, B). The average CEM similarity (83%) was slightly lower than the average CCM similarity (83.87%) in hypersaline lakes. However, the average CEM similarity (89.96%) was much higher than the average CCM similarity (86.40%) in mesosaline lakes. We then analyzed the novelty of the taxonomic composition of the different assemblages. Each phylogenetic group exhibits a different novelty pattern, as observed with the supergroups Alveolates and Stramenopiles (Figure 6). In the kingdom Stramenopiles, the median genetic diversity values were ≥75% for both cultured and environmental matches, with similar sequence identity distributions in hypersaline lakes. Conversely, only approximately 35% of the Stramenopiles group in mesosaline lake matched both cultured and environmental sequences. As shown in Figure 6, dots below 80% similarity in both axes indicated highly divergent novel sequences. Notably, we observed that in mesosaline lakes (Figure 6A), at least four sequences had no similarity to CCM or CEM data, whereas in hypersaline lakes, up to eighteen OTUs yield generally low similarity values (Figure 6B). These OTUs were either not successfully cultured in the laboratory or have not been observed in nature.


High genetic diversity and novelty in eukaryotic plankton assemblages inhabiting saline lakes in the Qaidam basin.

Wang J, Wang F, Chu L, Wang H, Zhong Z, Liu Z, Gao J, Duan H - PLoS ONE (2014)

Novelty pattern plot for the different eukaryal classes found in mesosaline lake and hypersaline lake.(A) mesosaline saline, (B) hypersaline. Closest environmental match (CEM) and the closest cultured match (CCM) available in GenBank (BLAST search, May 2014). Dots below 61% similarity in both axes indicated no similarity sequences.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4234628&req=5

pone-0112812-g006: Novelty pattern plot for the different eukaryal classes found in mesosaline lake and hypersaline lake.(A) mesosaline saline, (B) hypersaline. Closest environmental match (CEM) and the closest cultured match (CCM) available in GenBank (BLAST search, May 2014). Dots below 61% similarity in both axes indicated no similarity sequences.
Mentions: After water samples were obtained and sequenced, the identity of the different microorganisms was analyzed by BLAST search. For each OTUs, the similarity to the CEM and the CCM was recorded (Figure 6). The results were further classified according to salinity concentration (i.e., mesosaline vs. hypersaline, Figure 6A, B). The average CEM similarity (83%) was slightly lower than the average CCM similarity (83.87%) in hypersaline lakes. However, the average CEM similarity (89.96%) was much higher than the average CCM similarity (86.40%) in mesosaline lakes. We then analyzed the novelty of the taxonomic composition of the different assemblages. Each phylogenetic group exhibits a different novelty pattern, as observed with the supergroups Alveolates and Stramenopiles (Figure 6). In the kingdom Stramenopiles, the median genetic diversity values were ≥75% for both cultured and environmental matches, with similar sequence identity distributions in hypersaline lakes. Conversely, only approximately 35% of the Stramenopiles group in mesosaline lake matched both cultured and environmental sequences. As shown in Figure 6, dots below 80% similarity in both axes indicated highly divergent novel sequences. Notably, we observed that in mesosaline lakes (Figure 6A), at least four sequences had no similarity to CCM or CEM data, whereas in hypersaline lakes, up to eighteen OTUs yield generally low similarity values (Figure 6B). These OTUs were either not successfully cultured in the laboratory or have not been observed in nature.

Bottom Line: Notably, Chlorophyta group are only found in high abundance in Lake Gasikule (28.00%), whereas less represented in other hypersaline lakes such as Gahai (0.50%) and Xiaochaidan (1.15%).Out of the parameters, four show significant correlation to this CCA: altitude, calcium, sodium and potassium concentrations.The identified diversity and novelty patterns among eukaryotic plankton assemblages in saline lake are of great importance for understanding and interpreting their ecology and evolution.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, China; Institute of Shandong River Wetlands, Laiwu, China.

ABSTRACT
Saline lakes are intriguing ecosystems harboring extremely productive microbial communities in spite of their extreme environmental conditions. We performed a comprehensive analysis of the genetic diversity (18S rRNA gene) of the planktonic microbial eukaryotes (nano- and picoeukaryotes) in six different inland saline lakes located in the Qaidam Basin. The novelty level are high, with about 11.23% of the whole dataset showing <90% identity to any previously reported sequence in GenBank. At least 4 operational taxonomic units (OTUs) in mesosaline lakes, while up to eighteen OTUs in hypersaline lakes show very low CCM and CEM scores, indicating that these sequences are highly distantly related to any existing sequence. Most of the 18S rRNA gene sequence reads obtained in investigated mesosaline lakes is closely related to Holozoa group (48.13%), whereas Stramenopiles (26.65%) and Alveolates (10.84%) are the next most common groups. Hypersaline lakes in the Qaidam Basin are also dominated by Holozoa group, accounting for 26.65% of the total number of sequence reads. Notably, Chlorophyta group are only found in high abundance in Lake Gasikule (28.00%), whereas less represented in other hypersaline lakes such as Gahai (0.50%) and Xiaochaidan (1.15%). Further analysis show that the compositions of planktonic eukaryotic assemblages are also most variable between different sampling sites in the same lake. Out of the parameters, four show significant correlation to this CCA: altitude, calcium, sodium and potassium concentrations. Overall, this study shows important gaps in the current knowledge about planktonic microbial eukaryotes inhabiting Qaidam Basin (hyper) saline water bodies. The identified diversity and novelty patterns among eukaryotic plankton assemblages in saline lake are of great importance for understanding and interpreting their ecology and evolution.

Show MeSH