Spatio-temporal variation and environmental drivers of chlorophyll a concentration and diatom community in four small urban lakes of Kunming, China.

Chlorophyll a (Chla) and diatom community structure are two indicators of lake water quality. In this study, we investigated the environmental parameters, chlorophyll a, and diatom community of four small urban lakes in Kunming (Beitan, Beihu, Nanhu and Longtan lakes in the campus of Yunnan Normal University) between March 2017 and December 2019. The results showed that the concentrations of total nitrogen (TN), total phosphorus (TP), and Chla in the four lakes showed significant seasonal fluctuation. The Chla concentration in Nanhu Lake, which had the highest nutrient level among the four lakes, was significantly higher than that in the other three lakes and largely affected by TN. In comparison, water temperature significantly contributed to the increases in Chla concentration in the other three lakes. Water temperature and TN were significantly correlated with Chla across the four lakes. Diatom assemblages in Beitan, Nanhu, and Longtan lakes were dominated by planktonic diatoms, and benthic diatoms were dominant in the shallowest lake Beihu, suggesting that water depth significantly affected the proportion of planktonic diatoms and dominant taxa. Water depth, TN, TP, transparency, and water temperature affected the spatio-temporal changes of diatom community structure, with water temperature as the major factor in causing the seasonal variation in diatom community, and TN and TP as the major drivers for community variation among lakes within the same season.

In Silico Genome-Wide Analysis of B3 Transcription Factors in Cannabis sativa L.

Introduction: The B3 transcription factor has been identified in Arabidopsis thaliana, Oryza sativa, and Solanum lycopersicum, among other species. This family of transcription factors regulates seed growth, development, and stress. Cannabis is a valuable crop with numerous applications; however, no B3 transcription factors have been identified in this plant. Materials and Methods: The cannabis B3 gene family was identified and analyzed using bioinformatics analysis tools, such as the NCBI database, plantTFDB website, TBtools, and MEGA software. Quantitative real-time polymerase chain reaction (qRT-PCR) experiments were used to confirm its function. Results: The cannabis B3 family contains 65 members spread across 10 chromosomes. The isoelectric point ranged from 10.03 to 4.65, and the molecular weight ranged from 99,542.88 to 14,310.9 Da. Most of the members were found in the nucleus. The upstream promoter region of the gene contains a variety of cis-acting elements related to the stress response. RNA-seq data and qRT-PCR results showed that CsB3 genes were expressed differently in five organs of female Diku plants and in glandular hairs of nine distinct types of female cannabis inflorescences. Collinearity analysis revealed that there were more homologous genes between cannabis and dicotyledons than monocotyledonous plants, which was consistent with the evolutionary relationship. Conclusions: Hormones and external environmental factors might influence CsB3 expression. Furthermore, some genes such as CsB3-02, CsB3-07, CsB3-50, CsB3-62, and CsB3-65 may participate in cannabis growth and development and play a role in secondary metabolite synthesis. This study provides a solid foundation for further research into the gene function of the cannabis B3 family.

[Seasonal variations and driving factors of phytoplankton community shift in Datun Lake with long-term stress of arsenic contamination.] / é•¿æœŸç ·èƒè¿«ä¸‹å¤§å±¯æµ·æµ®æ¸¸æ¤ç‰©ç¾¤è½çš„å­£èŠ‚æ€§ç‰¹å¾åŠå ¶é©±åŠ¨å› å­.

Heavy metal is an important environmental stress that threatens water quality and ecological health of surface waters. Therefore, it is vital to identify the responses of lake community to long-term pollution for sustainable ecological restoration of polluted lakes. From June 2017 to March 2018, we conducted a seasonal survey of phytoplankton and environmental factors in Datun Lake, which had a decadal history of tailing-related arsenic contamination. Consistent with results from previous studies, phytoplankton were dominated by As-tolerant taxa such as Cyanophyta. Results of the analysis of similarities and analysis of variance showed that there were significant temporal variations in phytoplankton community structure and biomass, but without spatial variation. Results of the Pearson correlation analysis demonstrated that the total phytoplankton biomass was positively related to lake-water soluble orthophosphate and arsenic, which was consistent with the differential effect of arsenic on algae growth (e.g. promotion at low concentration and suppression at high concentration). The increases of phosphate might alleviate the toxic impacts of arsenic on phytoplankton. Redundancy analysis showed that the soluble nutrients and arsenic were significant factors driving phytoplankton community variations. The results of variation partitioning demonstrated that nutrients and water temperature explained 17.6% and 3.8% of community variations, respectively, with strong interaction with arsenic (15.1%). Arsenic did not affect phytoplankton community assembly, indicating that the dominant algae were tolerant to arsenic and thus highly insensitive to the arsenic stress. Therefore, the seasonal variations of phytoplankton dominated by As-tolerant algae in Datun demonstrated that the low-As promotion effect on phytoplankton should be considered in ecological restoration of polluted lakes.

Long-term succession of diatom community under hydro-climatic fluctuations in Taiping Reservoir, Yunnan Province, China.

Under the background of regional climate warming, frequent fluctuation of water level caused by drought events and pollutant influx due to catchment development can directly threaten the ecological safety of reservoirs. Through the analysis of physical (particle size, loss on ignition), chemical (carbon, nitrogen), biological (diatom community) and other substitute indicators of sediment, combined with monitoring data and investigation data, we reconstructed the environmental changes in Taiping Reservoir in Yunnan Province from 1937 to 2018, and analyzed the succession characteristics of diatom community and its environmental impact factors. The grain size records indicated that the hydrodynamic condition of Taiping Reservoir was increased during the impounding period (1956-1984) and was steadily reduced thereafter, corresponding well with the documented history of reservoir construction and hydrologic regulation. Changes of total nitrogen, total carbon and organic matter contents indicated the decline of water nutrient level during the construction of the reservoir and the rising process of primary productivity and endogenous organic matter after the completion of the reservoir. The dominant taxa of diatom community shifted from planktonic species to benthic species and then to planktonic ones. The main factors driving the succession of diatom community in Taiping Reservoir were climate change, hydrodynamic condition, and nutrient level. Under the background of long-term climate warming, strict controlling exogenous nutrition input, and reasonable hydrological regulation would be the important premise to maintain ecological health and environmental safety of reservoir water.

[Spatial distribution of cladoceran assemblages in surface sediments of shallow lakes in Yunnan.] / æµ æ°´æ¹–æ³Šè¡¨å±‚æ²‰ç§¯ç‰©è®°å½•çš„æžè§’ç±»ç¾¤è½ç©ºé—´åˆ†å¸ƒç‰¹å¾.

Shallow lakes, sensitive to environmental changes due to low environmental carrying capacity, generally experience decreases in ecosystem function and even regime shifts after over-exploitation. Surface sediments of 18 shallow lakes in Yunnan were collected and analyzed to identify the spatial pattern and the influencing factors of cladoceran communities. The results showed that there was significant heterogeneity in the spatial distribution of cladocera in those lakes. For example, the cladoceran community was generally dominated by benthic taxa in alpine lakes, while there was a clear replacement of benthic cladocerans by planktonic ones with increasing nutrient levels across lakes from Southeast Yunnan. Altitude and total phosphorus were the main driving factors, which independently explained 22.0% and 7.7% of the change in cladocera communities, respectively. The altitude gradient and related changes in climate and catchment features were the main factors in structuring cladocerans for shallow lakes of Yunnan, while the anthropogenic impacts on cladoceran distribution was significant via the processes such as catchment development, pollutant input and macrophyte changes. Meanwhile, the interaction between elevation and total phosphorus explained 26.3% of the total variance in cladoceran community shift, indicating that the increase in human activity intensity in lakes at lower altitudes would have stronger impact on cladocerans through anthropogenic nutrient inputs.