Aluminate flocculants are employed widely in water treatment for precipitating suspended solids and emergency treatment of algal blooms in eutrophic lake, but the residual aluminum (Al) may have phytotoxic effects on aquatic organisms after entering aquatic ecosystems. To elucidate the potential impacts of Al on turion germination and early growth in Potamogeton crispus , we conducted a mesocosm experiment using five Al concentrations (0 (control group), 0.3, 0.6, 1.2, and 1.5 mg/L) in alum solutions. The results showed that the germination of turions and the early growth of P. crispus were reduced and inhibited by Al. The maximum numbers of germinating turions and newly-formed seedlings occurred in the control group, and their numbers declined in the end of the experiment as the Al concentration increased. Al at a concentration of 1.5 mg/L decreased the number of germinating turions 3.0 times and the number of newly-formed seedlings 30.7 times compared with the control. The chlorophyll content and root activity decreased when the Al concentration increased. The maximum soluble protein contents in seedling tissues (1.953 mg/g fresh weight) occurred in the 0.6 mg/L treatment group, which differed significantly from the other treatment groups. The Al contents in the seedling tissues had a significant positive correlation with the Al treatment concentrations ( P < 0.05, r = 0.763), but negative correlations with the biomass, root number, stem weight, soluble protein, and root activity (r = −0.935, −0.975, −0.907, −0.721, −0.944, respectively). Persistent Al concentration ≥1.2 mg/L significantly decreased the germination of turions and seedling growth in P. crispus . These results may facilitate the restoration of aquatic macrophytes and ecological risk assessments in Al-exposed lakes.
Ling Qin,Yajing Yang,Jiejie Hao,Xiaoxi He,Shan Liu,Xiao Chu,Wenjun Mao
A water-soluble polysaccharide from the green alga Chaetomorpha linum , designated CHS2, was obtained by water extraction, preparative anion-exchange and size-exclusion chromatography. Results of chemical and spectroscopic analyses showed that CHS2 was a sulfated rhamnogalactoarabinan, and its backbone was mainly constituted by 4-linked and 3,4-linked β- l -arabinopyranose with sulfate groups at C-2/C-3 of 4-linked β- l -arabinopyranose. The branching contained 4-linked, 6-linked β- d -galactopyranose and terminal rhamnose residues. Based on the inhibition of human islet amyloid polypeptide (hIAPP) aggregation and morphology change of hIAPP aggregates in in vitro tests, it was proved that CHS2 effectively inhibited the hIAPP aggregation and possessed strong antidiabetic activity. CHS2 was nearly no toxicity in NIT-1 cells and could attenuate hIAPP-induced cytotoxicity. CHS2 may significantly reduce the generation of intracellular reactive oxygen species and hIAPP aggregation-induced oxidative stress in NIT-1 cells. CHS2 was co-localized with mitochondria, and largely protected mitochondria function from hIAPP aggregation-induced damage through stabilizing mitochondrial membrane potential and enhancing the mitochondrial complex I, II or III activity and ATP level. The data demonstrated that CHS2 could have potential prospect to become an antidiabetic drug for type 2 diabetes mellitus treatment.
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