Eutrophication in Poyang Lake (Eastern China) over the Last 300 Years in Response to Changes in Climate and Lake Biomass

<div><p>Poyang Lake is suffering from persistent eutrophication, which is degrading the local ecosystem. A better understanding of the mechanisms that drive eutrophication in lake systems is essential to fight the ongoing deterioration. In this study, hydraulic residence time (HRT) was used to evaluate Poyang Lake’s trophic state. A hydrology and ecosystem forced model was constructed to simulate long-term changes in algae and aquatic plant biomass and total phosphorous (TP). A comparison analysis revealed that between 1812 and 1828 (i.e., a consistent-change stage), climate and hydrology were the main driving forces, while algae and aquatic plant biomass contributed only 20.9% to the trophic changes in Poyang Lake. However, between 1844 and 1860 the biomass predominated contributing 63.6%. This could be attributed to nutrient absorption by algae and aquatic plants. A correlation analysis of the water TP and algae and aquatic plant biomass revealed a strong positive relationship. However, the algae and aquatic plant growth rate tended to decline after the biomass reached half of the maximum. This research reconstructs the long-term trophic evolution of Poyang Lake and provides a better understanding of the relationship between climatic and hydrological changes and lake ecosystems.</p></div

Additional file 1 of Effects of dual-task training on chronic ankle instability: a systematic review and meta-analysis

Supplementary Material

Simulations of Model 2 and Mann-Kendall trend analyses.

<p>Anomaly series of monthly algae biomass and the corresponding UF_k index from 1955–2008 (A1) and 1700–1899 (A2); Anomaly series of monthly aquatic plant biomass and the corresponding UF_k index from 1955–2008 (B1) and 1700–1899 (B2); Anomaly series of monthly TP content and the corresponding UF_k index from 1955–2008 (C1) and 1700–1899 (C2).</p

(A) Standardized HRT and simulated TP series from 1700–1899; (B) Comparison between ΔHRT and simulated TP from 1700–1899.

<p>(A) Standardized HRT and simulated TP series from 1700–1899; (B) Comparison between ΔHRT and simulated TP from 1700–1899.</p

HRT anomaly (ΔΔHRT) in Model 1 and its change process.

<p>(A) ΔHRT calculated with observed meteorological and hydrological data for 1800–2008; (B) ΔHRT calculated with simulated meteorological and hydrological data for 1700–1899.</p

Co-Expression and Co-Purification of Archaeal and Eukaryal Box C/D RNPs

<div><p>Box C/D ribonucleoprotein particles (RNPs) are 2′-O-methylation enzymes required for maturation of ribosomal and small nuclear RNA. Previous biochemical and structural studies of the box C/D RNPs were limited by the unavailability of purified intact RNPs. We developed a bacterial co-expression strategy based on the combined use of a multi-gene expression system and a tRNA-scaffold construct that allowed the expression and purification of homogeneous archaeal and human box C/D RNPs. While the co-expressed and co-purified archaeal box C/D RNP was found to be fully active in a 2′-O-methylation assay, the intact human U14 box C/D RNP showed no detectable catalytic activity, consistent with the earlier findings that assembly of eukaryotic box C/D RNPs is nonspontaneous and requires additional protein factors. Our systems provide a means for further biochemical and structural characterization of box C/D RNPs and their assembly factors.</p></div

(A) Relationship between the simulated primary biomass and TP; (B) A S-shaped curve showing the growth pattern of the living organisms (redraw and modified from Rubin and Davidson, 2001, [95]).

<p>(A) Relationship between the simulated primary biomass and TP; (B) A S-shaped curve showing the growth pattern of the living organisms (redraw and modified from Rubin and Davidson, 2001, [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169319#pone.0169319.ref095" target="_blank">95</a>]).</p

Validation of the Model 2 simulations (1700–1899).

<p>(A) Comparison between pollen concentration anomaly from core ZK01 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169319#pone.0169319.ref051" target="_blank">51</a>] and simulated algae biomass anomaly; (B) Comparison between TOC anomaly from core DCH [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169319#pone.0169319.ref036" target="_blank">36</a>] and simulated primary biomass anomaly; (C) Comparison between DI-TP from core WC-2 and simulated TP anomaly.</p

Diagrams of co-expression plasmids based on pQlink system.

<p>A). The pQlink-N vector inserted with tRNA-box C/D RNA chimera coding sequence. B). Co-expression plasmids inserted with all proteins and RNA encoding sequences. The region containing inserted genes is highlighted on top for pQafCDtRNA+ and pQhsCDtRNA+, respectively. Other elements of the co-expression plasmid are also shown at the bottom.</p

Co-expression and purification of recombinant <i>Archaeoglobus fulgidus</i> sR3 sRNP.

<p>A) Silver-stained SDS-PAGE gel analysis of purified sR3 sRNP components “Af-3Pro-sR3” denotes the sample expressing Nop5, fibrillarin, L7Ae and sR3 RNA. “Af-3Pro-tRNA-sR3” denotes that expressing Nop5, fibrillarin, L7Ae and sR3-tRNA chimeric RNA. Box C/D proteins and sR3-tRNA chimeric RNA are labeled and indicated by arrows. The sR3 sRNPs were purified by Ni-NTA affinity followed by gel filtration method based on the single histidine tag present in Nop5. B). Polyacrylamide gel analysis of total RNA extracted from cells expressing only box C/D proteins (Af-3Pro) or proteins plus sR3-tRNA chimeric RNA (Af-3Pro-tRNA-sR3). The location of sR3-tRNA chimera is indicated.</p