Photosynthetic characteristics and inferred changes in thylakoid membrane fluidity determine bloom succession between Anabaena and Microcystis in eutrophic lakes

Abstract

Anabaena and Microcystis are common dominant cyanobacterial genera and frequently form blooms in large shallow eutrophic lakes in China. There is usually a quick succession between these two cyanobacterial blooms in early summer; however, there is currently no solid evidence based on photosynthesis and population competition to explain this phenomenon. This study compared the photosynthetic parameters and the indirectly measured thylakoid membrane fluidity characteristics between Anabaena and Microcystis. The results showed that the growth rate, the maximum photochemical efficiency of PSII (F v /F m ), and the maximum relative electron transport rate (rETR max ) of Microcystis cultured at 25°C were significantly lower than those from cells grown at 15°C, indirectly suggesting a marked limitation of thylakoid membrane fluidity at low temperatures. Chlorophyll fluorescence dynamics also indicated inhibition of NPQ formation and membrane fluidity when Microcystis was cultured at low temperatures; however, this inhibition was not significant for Anabaena. Fourier transition infrared (FT-IR) spectrometry indicated that the thylakoid membrane of Anabaena can maintain homeostasis fluidity through the upregulation of unsaturated fatty acids when exposed to chilling stress. Increasing the temperature significantly promoted the growth rate of Microcystis, while it had little effect on Anabaena. Moreover, photoinhibition of Anabaena was more easily induced by high light, thus accelerating the bloom succession from Anabaena to Microcystis during warm seasons. An activation-energy model was used to deduce that the threshold temperature of bloom succession was 15.4°C, which would increase to 16.2°C and decrease to 14.9°C under conditions of N-limitation and P-limitation.

Proteome Profiling of Paulownia Seedlings Infected with Phytoplasma

“…In this study, the TLP was down-regulated in the diseased seedlings. Evidences showed that the reduction of TLP not only damaged the thylakoid electron flow, but also decreased chlorophyll a content and further slacked the photosynthesis (Wang et al, 2016 ; Zhu, 2016 ), this result is consistent with the previous RNA-seq results, which showed that a reduction in photosynthesis of phytoplasma-infected plants could be attributed to the loss of several thylakoid membrane proteins (Mou et al, 2013 ). At the same time, the expression of LHCI was reduced, which severely affected the light reactions in Photosystem I (PSI) (Bressan et al, 2016 ).…”

Mutual Dependence of Nitrogen and Phosphorus as Key Nutrient Elements: One Facilitates Dolichospermum flos-aquae to Overcome the Limitations of the Other

“…To avoid light limitation and the interactive effects between P availability and irradiance, we chose a suitable irradiance of 30 μmol photons m –2 s –1 for D. flos-aquae according to the suggestion from the FACHB-collection and our previous experience with this genus . In light of our results, we predict that the paradigm of N loading reduction stimulating N 2 -fixing cyanobacterial blooms occurs only when P loading is high.…”

E2F1 mediates competition, proliferation and response to cisplatin in cohabitating resistant and sensitive ovarian cancer cells

“…Similarly, cells deficient in ribosomal proteins and slower proliferating, have been shown to be eliminated by neighboring faster proliferating cells in the Drosophila wing (26). This phenomenon can also be observed in the interaction between species, applicable to cohabiting plants or microbes (27,28). Formulas of species interaction have been used to determine the dynamics of species proliferation in a cohabiting milieu.…”