Effects of toxic Microcystis aeruginosa on the expression of Hox genes in Daphnia similoides sinensis.

Lake eutrophication and cyanobacterial blooms have become worldwide environmental issues. Under cyanobacterial blooms (especially Microcystis), Daphnia spp. can transfer beneficial information to their offspring in order to improve adaptability. Hox genes are important regulatory factors of transcription in metazoans, and are involved in the growth and development of organisms. However, the mechanisms of Microcystis on the expression of Hox genes in Daphnia are unclear. In this study, the effects of Microcystis aeruginosa on Hox gene expression in the mothers and offspring (F1) of two Daphnia similoides sinensis clones were investigated using a mixed diet of M. aeruginosa and Scenedesmus obliquus. Compared with the 100%S food treatment, the survival rates at the end of the experiment of clone 1-F1 in the food treatments containing M. aeruginosa were significantly lower, but it was significantly higher for clone 2-F1 in the 20%M + 80%S food treatment. Moreover, the survival rates at the end of the experiment of clone 1-F1 in the food treatments containing M. aeruginosa were significantly higher than those of their mother. Based on previous transcriptome data, 14 Hox genes of D. similoides sinensis were identified, including Abd-B, CDX-1, Dll, HOX-1, HOX-2, HOXA1, HOXA2, HOXB3, HOXB3-2, HOXB7, HOXC4, HOXC7, HOXC8, and HOXD10. The expressions of Abd-B, HOX-2, HOXA1, HOXC7, and HOXD10 of clone 2-mothers in the 40%M + 60%S food treatment were 2.9-22.5 times as high as in the 100%S food treatment, whereas the expressions of CDX-1, HOX-1, HOXB3, and HOXD10 of clone 1-mothers were 4.8-13.1 times at same food level. The expression of HOXA2, HOXC7, HOXC8, and HOXD10 of clone 1-F1 in the 40%M + 60%S food treatment was 8.2-21.1 times as high as in the 100%S food treatment. However, compared with the 100%S food treatment, the expressions of CDX-1 in the mothers and F1 of clone 2 and HOXB7 in the mothers of clone 1 in the food treatments containing M. aeruginosa were significantly lower (p < .05). Our results suggest that the offspring (F1) produced by D. similoides sinensis mother pre-exposed to toxic M. aeruginosa had stronger adaptability to M. aeruginosa than their mothers. Moreover, Hox gene expressions of D. similoides sinensis had obvious differences between clones under stress of toxic M. aeruginosa.

The impact of withdrawing aquaculture facilities on metazooplankton communities in the lakes are connected to the Yangtze River, China.

The withdrawal of aquaculture facilities has an important impact on the aquatic ecosystem of the lakes connected to the Yangtze River. In order to elucidate the response mechanism of metazooplankton to the changes in water environment after the removal of aquaculture facilities, we collected metazooplankton samples and investigated the water environment in the Huayanghe Lakes from the summer of 2018 to the spring of 2019. Aquatic plants recovered quickly, and water eutrophication was relieved, especially in Lake Huangda, followed by Lake Bo. During our study, the highest regional (γ) diversity was 71 in summer, while the lowest was 32 in winter. Species turnover in space (ß diversity) varied between 10.01 and 56.52, which was highest in summer. Based on redundancy analysis, environmental factors such as transparency, Chl α, water temperature and water depth, had greatly effects on the metazooplankton community structure. The results showed that the restoration of aquatic plants increased species diversity and metazooplankton density. This study provides a data basis for lakes restoration and a scientific basis for the management and protection of lakes water ecosystem.

Effect of fast restoration of aquatic vegetation on phytoplankton community after removal of purse seine culture in Huayanghe Lakes.

The disappearance of submerged aquatic vegetation caused by the use of purse seine in productive fishery has aroused the attention of the national government. In order to restore aquatic vegetation, the government has removed the seine nets on the Huayanghe Lake's surface. Here, fourteen cruises were conducted in the Huayanghe Lakes from 2016 to 2019 to study the response of water quality and phytoplankton communities to rapidly recovering aquatic vegetation. The results showed that the restoration of aquatic vegetation increased the Secchi depth (from 65.36 to 105.52 cm) and dissolved oxygen (from 8.98 to 12.17 mg/L), while the concentration of total nitrogen (from 0.98 to 0.53 mg/L), and total phosphorus (from 0.04 to 0.02 mg/L) decreased, resulting in a 35.3% and 11.6% reduction in the total phytoplankton density and chlorophyll ɑ, respectively. In addition, the restoration of aquatic vegetation significantly increased Shannon-Wiener diversity, Margalef richness indices by 51.6% and 40.1%. We also observed that phytoplankton density exhibited significant changes based on nonmetric multidimensional scaling analysis (NMDS). In Lake Huangda, the coverage of aquatic vegetation was as high as 80%. We also observed that after the restoration of aquatic vegetation, the proportion of cyanobacteria decreased significantly by 21%. Our study emphasizes that aquatic plants can alleviate eutrophication and increase the diversity of phytoplankton, thus providing guidance for the restoration and protection of water ecosystems in the lakes connected to the Yangtze River.

Ecological stoichiometric characteristics of Carbon (C), Nitrogen (N) and Phosphorus (P) in leaf, root, stem, and soil in four wetland plants communities in Shengjin Lake, China.

Ecological stoichiometric should be incorporated into management and nutrient impacted ecosystems dynamic to understand the status of ecosystems and ecological interaction. The present study focused on ecological stoichiometric characteristics of soil, and leaves, stems, and roots of different macrophytes after the banning of seine fishing in Shengjin Lake. For C, N, and P analysis from leaves, stems, roots, and soil to explore their stoichiometric ratio and deriving environmental forces, four dominant plant communities (Vallisneria natans, Zizania latifolia, Trapa natans and Carex schmidtii) were collected. The concentration of C, N, P and C: N: P ratio in leaves, stems, roots, and soil among the plant communities varied significantly. Along the depth gradient high C: N was measured in C.schmidtii soil (7.08±1.504) but not vary significantly (P >0.05). High C: P result was found in T.natans (81.14±43.88) and in V.natans soil (81.40±42.57) respectively with no significant difference (p>0.05). Besides, N: P ratio measured high in V. natans (13.7±4.05) and showed significant variation (P<0.05). High leaf C: N and N: P ratio was measured in C. schmidtii and V. natans respectively. Nevertheless, high leaf C: P ratio was measured in Z. latifolia. From the three studied organs, leaf C: N and N: P ratio showed high values compared to root and stems. The correlation analysis result showed that at 0-10cm depth soil organic carbon (SOC) correlated negatively with stem total phosphorus (STP), and root total nitrogen (RTN) (P<0.05) but positively strongly with leaf total phosphorus (LTP) and leaf total nitrogen (LTN) (P<0.01) respectively. Soil total nitrogen (STN) at 0-10cm strongly positively correlated with leaf total phosphorus (LTP) (P<0.01) and positively with RN: P and leaf total carbon (LTC) (P<0.05). Soil basic properties such as soil moisture content (SMC), bulky density (BD) and pH positively correlated with soil ecological stoichiometric characteristics. Redundancy analysis (RDA) result showed available nitrogen (AN), soil total nitrogen (STN), and available phosphorus (AP) were the potential determinants variables on plants stoichiometric characteristics.

Temporal and spatial variations in zooplankton communities in relation to environmental factors in four floodplain lakes located in the middle reach of the Yangtze River, China.

A comparative limnological study of the zooplankton communities and their relationship with environmental factors was conducted to test the temporal and spatial changes among lake groups. In our study of four lakes, the lowest gamma (γ) diversity was recorded in January 2017, with a total of 25 zooplankton taxa. The highest γ diversity was recorded in May 2016, with a total of 55 zooplankton taxa. Species turnover in space (ß) were from 14.98 to 25.81. Markedly temporal and spatial variations were observed in the zooplankton community. The higher mean cladocera density (57.70 ind. L-1 and 39.85 ind. L-1) was observed in May and August, then decreased gradually with the lowest in January. The mean copepoda density ranged from 8.71 ind. L-1 in January 2017 to 32.04 ind. L-1 in August 2016. The mean rotifera density was significantly higher than that of the other two crustacean zooplankton (p < 0.01), within the range of 89.36-1139.2 ind. L-1. We also observed that zooplankton density exhibited significant seasonal changes from NMDS (Nonmetric multidimensional scaling analysis). Redundancy analysis revealed that environmental factors, such as water temperature and transparency, have significantly influenced the zooplankton community structure.

Genetic diversity and phylogeography of Daphnia similoides sinensis located in the middle and lower reaches of the Yangtze River.

Geographical patterns, climate, and environmental change have important influences on the distribution and spread of aquatic organisms. However, the relationships between the geographical pattern and phylogenetics of Daphnia as well as environmental change are not well known. The genetic diversity and phylogeography of seven D. similoides sinensis populations located in the middle and lower reaches of the Yangtze River were investigated based on the combination of mitochondrial (COI gene) and nuclear (14 microsatellite primers) markers. Based on the mitochondrial gene markers, D. similoides sinensis from the middle and lower reaches of the Yangtze River had one ancestral haplotype and two evolutionary clades. In addition, D. similoides sinensis population deviated from neutral evolution, showing signs of a bottleneck effect followed by population expansion. Based on the microsatellite markers, the seven D. similoides sinensis populations formed three main groups. The dendrogram (NJ/ME) showed that D. similoides sinensis based on the mitochondrial genes marker were obviously clustered two main clades, whereas there were three clades based on the microsatellite markers. Our results suggested that the habitat fragmentation due to the barrier of the dams and sluices promoted the genetic differentiation and phylogeography of D. similoides sinensis populations in the middle and lower reaches of the Yangtze River.

The response of zooplankton communities to the 2016 extreme hydrological cycle in floodplain lakes connected to the Yangtze River in China.

The Huayanghe Lakes play an important role in the Yangtze floodplain in China and had extremely high water levels during the summer of 2016. Monitoring data was collected in an effort to understand the impact of this change on the crustacean zooplankton composition and abundance and the biomass variation in the Huayanghe Lakes between a regular hydrological cycle (RHC) and an extreme hydrological cycle (EHC). The crustacean zooplankton community composition, abundance, and biomass in the floodplain lakes were markedly affected by the water-level disturbance. The number of species was lower in the RHC, but the mean density and biomass decreased from 93.84 ± 13.29 ind./L and 6.11 ± 0.89 mg/L, respectively, in the RHC to 66.62 ± 10.88 ind./L and 1.22 ± 0.26 mg/L, respectively, in the EHC. Pearson correlations and redundancy analyses revealed the environmental factors with the most significant impact on the crustacean zooplankton community differed between the RHC and EHC cycles. Little previous information exists on the zooplankton in these lakes, and the present study provides data on the zooplankton composition, abundance, and biomass, both at baseline and in response to hydrological changes.

Effects of Microcystis aeruginosa on the expression of nuclear receptor genes in Daphnia similoides sinensis.

Nuclear receptor (NR) genes form a conserved superfamily, which is involved in organism metabolism, reproduction, development, homeostasis, and resource allocation. Microcystis aeruginosa can inhibit the growth and reproduction of Daphnia. However, whether M. aeruginosa can affect the expression of Daphnia NR genes is unknown. In total, 18 NRs were identified in this study based on previous Daphnia similoides sinensis transcriptome data. In treatments containing M. aeruginosa, the gene expression of the NR1 subfamily (E75a, E75b, HR3, HR96, NHR-1, HR97a, HR97g, and NHR97) and the NR2 subfamily (RXR, TLL, PNR, and SVP) were down-regulated 59% and 79%, respectively. In treatments containing M. aeruginosa, although the expression of 78% of the genes showed a similar trend in clones 1 and 2, the expression of 42% of the genes in clone 3 showed the opposite trend compared to clones 1 and 2, suggesting that the adaptability and molecular mechanism differ in individuals with different Microcystis tolerance genotypes.

Temporal and spatial variations in rotifer correlations with environmental factors in Shengjin Lake, China.

Shengjin Lake is an important wintering and stopover habitat for migratory birds en route from East Asia to Australia. The authors investigated the rotifer community structure and environmental factors in upper Shengjin Lake from February to July of 2014. A total of 17 genera and 31 species of rotifers were identified, the dominant species being Brachionus angularis, Brachionus calyciflorus, Asplanchna priodonta, and Schizocerca diversicornis. Rotifer density and the nutrient salt content were higher in the areas inhabited by migratory birds. The highest density (176.0 ind./L) was recorded in June, the lowest (14.0 ind./L) in April. Canonical correspondence analysis (CCA) and correlation analysis showed that some environmental factors, such as temperature, pH, water depth, Secchi depth (SD), and chlorophyll a concentration, had a considerable effect on the lake's rotifer community structure.

Temporal and spatial variations in phytoplankton: correlations with environmental factors in Shengjin Lake, China.

Temporal and spatial variations in the phytoplankton community and environmental variables were investigated from February to July 2014, in the upper lake of Shengjin Lake, China. We identified 192 species of phytoplankton belonging to 8 phyla and 84 genera, of which 46.4% of Chlorophyta, 29.2% of Bacillariophyta, and 12.5% of Cyanophyta. There were 14 predominant species. Marked temporal and spatial variations were observed in the phytoplankton community. The total abundance of phytoplankton ranged from 3.66 × 10(5) to 867.93 × 10(5) cells/L and total biomass ranging from 0.40 to 20.89 mg/L. The Shannon-Wiener diversity index varied from 3.50 to 8.35 with an average of 5.58, revealing high biodiversity in the phytoplankton community. There were substantial temporal changes in the dominant species, from Bacillariophyta and Cryptophyta to Cyanophyta and Chlorophyta. Phytoplankton biomass and abundance showed a similar increasing trend from February to July. Pearson correlations and Redundancy analysis revealed that the most significant environmental factors influencing phytoplankton community were water temperature (T), transparency (SD), and nutrient concentration. The positive correlation between the key water bird areas and phytoplankton biomass indicated that the droppings of wintering water birds had an important influence on the phytoplankton community in the upper lake of Shengjin Lake.

Effects of Fructus ligustri lucidi on the growth, cell integrity, and metabolic activity of the Microcystis aeruginosa.

Agricultural waste has been used in the treatment of cyanobacterial bloom because of its environmental friendly and cost-efficient characteristics. In this work, the effects of Fructus ligustri lucidi (FLL) on the growth inhibition, physiological properties, algicidal property, and cell ultrastructure of Microcystis aeruginosa were investigated for the first time. The alga was efficiently inhibited by FLL at the dosages from 0.25 to 4.0 g L(-1), and the Chl-a fluorescence and metabolic activity of cells also declined gradually. During 25 days incubation time, the inhibition ratio of 0.25 g L(-1) dosage increased from 8 to 68 %, the percentage of intact cells decreased from 94.4 to 59.8 %, the inhibition ratio of 2.0 and 4.0 g L(-1) dosages was nearly 100 %, and the cell membranes were completely broken. The results of Chl-a, propidium iodide (PI) staining, fluorescein diacetate (FDA) staining, and transmission electron microscopy (TEM) assays were consistent with that of growth inhibition tests. The new medium test with the PI staining test suggested that FLL may act as an algicidal agent which can inhibit the growth of M. aeruginosa in the acute time. Consequently, FLL could be an excellent choice in the treatment of eutrophic water.

[Medicinal species of genus Polygonum s. lat. distributed in Anhui Province].

OBJECTIVE: To clarify the resource of medicinal plants of genus Polygonum s. lat. distributed in Anhui Province. METHOD: Conducting field investigation and consulting related specimens and data. RESULT AND CONCLUSION: The distribution, growing environment and medicinal use of 32 taxa have been clarified. A scientific basis for further study for these medicinal plants has been provided.

Investigation of the reaction of magnesium with p-nitro-o-carboxylazochromotropic acid and the determination of magnesium in plants and in water.

The formation of a novel complex between magnesium and p-nitro-o-carboxylazochromotropic acid (NCBAC) has been observed which is sensitive and selective at pH 10.4 in the presence of ethylenediamine and fluoride. The constants of formation of this complex have been determined by a spectral correction technique, and the complexation reaction has been applied to the spectrophotometric determination of trace magnesium in plants and in water with satisfactory results.