Assessing ecosystem health of floodplain lakes using an Integrated Bioassessment Index

Lakes within river-floodplain ecosystems are key biodiversity refuges majorly threatened by eutrophication and hydrologic river-lake fragmentation. However, an integrative index, specifically designed to comprehensively assess the health of floodplain lakes, considering multiple biological taxa and major stressors, remains unavailable. Based on biological data collected from 68 isolated lakes in the eastern plain lake region of China, we constructed a reliable index for assessing floodplain lake ecosystem health: Integrated Bioassessment Index (L-IBAI). The L-IBAI consists of components of overall health and species diversity, eutrophication, and hydrological connectivity and water level regimes. To construct the L-IBAI, we firstly used the observed species (SO)-area (A) model to predict the expected species richness (SE), and then developed observed to expected indices by calculating the SO/SE ratio for fish (F-O/E-SA) and benthos (B-O/E-SA). The health level thresholds for the other four indices, namely the ratio of Secchi depth and water depth (ZSD/ZM), chlorophyll a in phytoplankton (Chl a), the percent of rheophile fish species, and emergent macrophytes coverage, were determined using cumulative frequency curves. The final L-IBAI score was obtained by summing the weighted values of the three components mentioned earlier. The L-IBAI can significantly discriminate rural from urban lakes, and is a reliable index for assessing lake ecosystem health. Moreover, we developed three simplified three-index integrated bioassessment indices, which consists of three indices belonging to the three elements are also effective. The developed L-IBAI is flexible to be extended and applied to other floodplain lakes, and outcomes of health assessments for the eastern plain lakes in China helped to identify conservation and restoration priorities

Genetic Variation and Phylogeography of <i>Lumbriculus variegatus</i> (Annelida: Clitellata: Lumbriculidae) Based on Mitochondrial Genes

Lumbriculus variegatus is a typical cold-water worm and is mainly distributed in the Tibetan Plateau and Northeast in China. The current study aimed to explore the genetic diversity and phylogeography of L. variegatus sampled from different geographical regions based on concatenated (COI + 16S rRNA, 879 bp) genes. Among 63 L. variegatus specimens, 29 haplotypes were identified with high haplotype diversity (h = 0.923) and nucleotide diversity (π = 0.062). The Bayesian phylogenetic analysis and Median-joining haplotype network revealed two lineages, or species, of L. variegatus. Taxa belonging to lineage I was mainly distributed in the Tibetan Plateau of China, North America, and Sweden, while lineage II composed taxa from Northeast China, southern China, and Sweden. The analysis of molecular variance indicated that the genetic difference was mainly due to differences between lineages. Neutrality tests showed that the overall L. variegatus have a stable population since the time of origin. Divergence time analysis suggested that L. variegatus originated from the Triassic period of Mesozoic in 235 MYA (95%HPD: 199–252 MYA), and the divergence between different lineages of L. variegatus began from the next 170 million years

Evolution of the Microstructure and Mechanical Performance of As-Sprayed and Annealed Silicon Coating on Melt-Infiltrated Silicon Carbide Composites

In this study, silicon coating was deposited on melt-infiltrated SiC composites using atmospheric plasma spraying and then annealed at 1100 and 1250 °C for 1–10 h to investigate the effect of annealing on the layer. The microstructure and mechanical properties were evaluated using scanning electron microscopy, X-ray diffractometry, transmission electron microscopy, nano-indentation, and bond strength tests. A silicon layer with a homogeneous polycrystalline cubic structure was obtained without phase transition after annealing. After annealing, three features were observed at the interface, namely β-SiC/nano-oxide film/Si, Si-rich SiC/Si, and residual Si/nano-oxide film/Si. The nano-oxide film thickness was ≤100 nm and was well combined with SiC and silicon. Additionally, a good bond was formed between the silicon-rich SiC and silicon layer, resulting in a significant bond strength improvement from 11 to >30 MPa

A Simple Index of Lake Ecosystem Health Based on Species-Area Models of Macrobenthos

An effective biological index should meet two criteria: (1) the selected parameters have clear relationships with ecosystem health and can be measured simply by standard methods and (2) reference conditions can be defined objectively and simply. Species richness is a widely used estimate of ecosystem condition, although it is increased by nutrient enrichment, a common disturbance. Based on macrobenthos data from 91 shallow Yangtze lakes disconnected from the mainstem, we constructed an observed species (SO)-area (A) model to predict expected species richness (SE), and then developed an observed to expected index (O/E-SA) by calculating the SO/SE ratio. We then compared O/E-SA with three other commonly used indices regarding their ability to discriminate cultivated and urban lakes: (1) River Invertebrate Prediction and Classification System (RIVPACS; O/E-RF), (2) Benthic Index of Biotic Integrity (B-IBI), and (3) Average Score Per Taxon (ASPT). O/E-SA showed significant positive linear relationships with O/E-RF, B-IBI and ASPT. Quantile regressions showed that O/E-SA and O/E-RF had hump-shape relationships with most eutrophication metrics, whereas B-IBI and ASPT had no obvious relationships. Only O/E-SA, O/E50 and B-IBI significantly discriminated cultivated from urban lakes. O/E-SA had comparable or higher performance with O/E-RF, B-IBI and ASPT, but was much simpler. Therefore, O/E-SA is a simple and reliable index for lake ecosystem health bioassessment. Finally, a framework was proposed for integrated biological assessment of Yangtze-disconnected lakes

The NF-κB-modulated miR-19a-3p enhances malignancy of human ovarian cancer cells through inhibition of IGFBP-3 expression

Ovarian cancer is the most lethal gynecologic malignancy due to the lack of symptoms until advanced stages, and new diagnosis and treatment strategy is in urgent need. In this study, we found higher expression of miR-19a-3p in ovarian cancer tissues compared with that in the adjacent normal tissues. By chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA) analysis, we showed that nuclear factor-kappaB (NF-κB) binds to the promoter of miR-19a-3p, leading to reduced expression in ovarian cancer cells. Further study indicated that miR-19a-3p inhibits the expression of insulin-like growth factor binding protein-3 (IGFBP-3), resulting in enhanced growth and migration of ovarian cancer cells in vitro and tumor growth in vivo. These results showed that miR-19a-3p enhances the oncogenesis of ovarian cancer through inhibition of IGFBP-3 expression, and which can be inhibited by NF-κB, suggesting an NF-κB/miR-19a-3p/IGFBP-3 pathway in the oncogenesis of ovarian cancer, which expands our understanding of ovarian cancer and they may contribute to the development of new diagnosis and treatment of ovarian cancer

Glucose Intake Alters Expression of Neuropeptides Derived from Proopiomelanocortin in the Lateral Hypothalamus and the Nucleus Accumbens in Fructose Preference Rats

To study the neuroendocrine mechanism of sugar preference, we investigated the role of glucose feeding in the regulation of expression levels of neuropeptides derived from proopiomelanocortin (POMC) in the lateral hypothalamus (LH) and nucleus accumbens (NAc) in fructose preference rats. Fructose preference rats were induced by using the lithium chloride backward conditioning procedure. The fructose preference was confirmed by the two-bottle test. The drinking behavior of rats was assessed by the fructose concentration gradient test. The preference of 10% glucose or 0.1% saccharine was assessed, and the expression levels of neuropeptides derived from POMC in the LH and the NAc in fructose preference rats were measured by Western blot analysis. Fructose preference rats displayed a greater fructose preference than control rats. Furthermore, fructose preference rats preferred glucose solution rather than saccharine solution, while control rats preferred saccharine solution rather than glucose solution. The expression levels of neuropeptides derived from POMC in the LH and the NAc were changed by glucose but not saccharine intake. In summary, the data suggests that glucose intake increases the expression of neuropeptides derived from POMC in the LH and the NAc in fructose preference rats