Detoxification strategy of Microcystis aeruginosa to the toxicity of Cd(Ⅱ):role of EPS in alleviating toxicity

Although many studies have found that cadmium(Cd)can be toxic to microalgae,only a few reports focused on the role of extracellular polymeric substances(EPS)in Cd(Ⅱ)detoxification.The biochemical and physiological endpoints of Microcystis aeruginosa,including the composition and functional groups of soluble EPS(SL-EPS),loosely bound EPS(LB-EPS),and tightly bound EPS(TB-EPS),were detected to elucidate the toxicity and detoxification mechanisms of Cd(Ⅱ)for cyanobacteria.Toxicological and physiological assays on M.aeruginosa showed that the 0.25-mg/L Cd(Ⅱ)resulted in a larger inhibition on growth and F_(v)/F_(m).Nevertheless,Cd(Ⅱ)significantly induced much higher contents of superoxide dismutase(SOD),intracellular microcystin LR(MC-LR),extracellular MC-LR,and EPS.Scanning electron microscopy with energy dispersive X-ray spectroscopy confirmed that Cd(Ⅱ)was absorbed into the EPS layer.Fourier transform infrared spectrum analysis revealed that the functional groups bound with Cd(Ⅱ)of algae biomass,SL-EPS,LB-EPS,and TB-EPS were somewhat different.The C=O/C=N groups ofδ-lactam or protein were their prominent functional groups,suggesting that amide or proteins in the EPS played a key role in the adsorption in Cd(Ⅱ).The concentration of 0.25 mg/L of Cd(Ⅱ)may change the chemical structure of EPS by altering the production of protein-like substances containing tryptophan.This study indicated that M.aeruginosa could detoxify Cd(Ⅱ)stress via induction of antioxidant capacity(higher SOD activity and MC synthesis),EPS production,and modification in chemical structure of EPS.

Effect of light intensity on bound EPS characteristics of two Microcystis morphospecies:the role of bEPS in the proliferation of Microcystis

Bound extracellular polymeric substances(bEPS)play an important role in the proliferation of Microcystis.However,the understanding of bEPS characterization remains limited.In this study,threedimensional fluorescence excitation-emission matrix(3D-EEM)spectroscopy and zeta potentiometer were used to characterize the loosely bound EPS(LB-EP S)and tightly bound EPS(TB-EPS)from two dominant Microcystis morphospecies from Taihu Lake(China)at different light intensities.Physiochemical analysis showed that the growth and TB-EPS or bEPS contents in Microcystis aeruginosa were higher than those in Microcystisfl os-aquae at each light intensity.The 3D-EEM contour demonstrated that the intensities of peak B(tryptophan-like substances)in the TB-EPS from M.aeruginosa were stronger than those from M.flosaquae when the light intensity was higher than 10μE/(m^(2)·s).Zeta potential analysis showed that the absolute values of the zeta potential of TB-EPS in the two species both increased with rising light intensity,except those of TB-EPS in M.aeruginosa at 105μE/(m^(2)·s).Moreover,the absolute values of the zeta potential of M.aeruginosa were higher than tho se of M.flos-aquae at each light intensity.All these re sults indicated that M.aeruginosa may more quickly proliferate than M.flos-aquae through increased negative charges,bEPS contents.growth.and tryptophan-like substance contents at certain light intensities.

Coal Rock Condition Detection Model Using Acoustic Emission and Light Gradient Boosting Machine

Coal rock mass instability fracture may result in serious hazards to underground coal mining.Acoustic emissions(AE)stimulated by internal structure fracture should carry lots of favorable information about health condition of rock mass.AE as a sensitive non-destructive test method is gradually utilized to detect anomaly conditions of coal rock.This paper proposes an improved multi-resolution feature to extract AE waveform at different frequency resolutions using Coilflet Wavelet Transform method(CWT).It is further adopt an efficient Light Gradient Boosting Machine(LightGBM)by several cascaded sub weak classifier models to merge AE features at different views of frequency for coal rock anomaly damage recognition.The results denote that the proposed method achieves excellent recognition performance on anomaly damage levels of coal rock.It is an effective method to detect the critical stability further to predict the rock mass bursting in time.

A haplotype block associated with thousand-kernel weight on chromosome 5DS in common wheat(Triticum aestivum L.)

Spike number per unit area, number of grains per spike, and thousand-kernel weight（TKW） are important yield components for wheat（Triticum aestivum L.）. TKW has the highest heritability among the three components. We validated 27 simple sequence repeat（SSR） loci associated with TKW in an F2：5breeding population grown in four environments. A cfd78265 bpmarker on chromosome 5DS showed the strongest association with TKW and had a significantly positive effect on TKW compared to allele cfd78259 bp, with mean increases of 5.17, 3.63, 4.11, and 5.16 g in the four environments. Markers cfd67 and cfd40 flanking cfd78 also showed significantly positive associations with TKW with increases of 5.11, 3.29, 4.31, and 4.50 g for cfd67205, and4.98, 3.49, 4.06, and 4.84 g for cfd40187 compared with cfd67203 and cfd40190in the four environments, respectively. A major quantitative trait locus for TKW spanning 2.94 c M on chromosome 5DS was detected by association mapping.Strong linkage disequilibrium（LD）（r2〉 0.2） was detected Resear among the three linked markers, which formed three haplotype blocks in the F2：5breeding population. Mean TKW differences between Hap B-I and Hap B-II were 5.80, 4.41, 4.02,and 5.06 g in the four environments, respectively. Moreover,significant LD was detected only between cfd78 and cfd67 and between cfd67 and cfd40 in a germplasm collection. This study provides a base for cloning genes related to TKW on chromosome 5DS.