Stress regulation of photosynthetic system of Phaeocystis globosa and their hemolytic activity

Blooms of Phaeocystis globosa have been reported accountable for massive fi sh mortality worldwide.The toxigenic mechanisms of P.globosa,however,remain largely unclear due to the multiple structures and/or synergistic or antagonistic ef fects of hemolytic compounds.External stressors could lead to the regulation of photoprotective or antioxidative defense system,as well as the potential hemolytic activity.Therefore,the light-induced photosynthetic system,including the accessory photosynthetic growth,the relative electron transfer rate(ETR),photosynthetic e ffi ciency(F_(v)/F_(m)),quantum yield of photosystem II(Yield),together with the hemolytic activity of P.globosa were investigated under variable environmental conditions in the present study.Results confirmed that hemolytic activity of P.globosa was initiated by the light,but inhibited by low temperature(16℃),high light intensity(>100μmol/(m^(2)·s)),and iron-limited conditions.Interestingly,the hemolytic activity was not impacted by photosynthetic electron inhibitors(Diuron,atrazine,paraquat,and dibromothymoquinone),which signifi cantly inhibited the photosynthetic activity of P.globosa.The correlated response of hemolytic and photosynthetic activity of P.globosa under those environmental factors suggested that the hemolytic compounds of P.globosa would be involved in the photosynthetic process but not in the electron transfer chain of P.globosa.

Efficient harvesting of green microalgae cells by magnetic flocculated Fe_(3)O_(4)nanoparticles combined with chitosan

Microalgae harvesting remains a challenging step in microalgae industrialization,thereby provoking the necessity to explore sustainable and economically feasible approaches.This research investigated the use of magnetic flocculated nanoparticles in the harvesting of the common microalgae Chlorella pyrenoidosa and Scenedesmus obliquus.The results showed that magnetic flocculated nanoparticles efficiently adsorbed negatively charged microalgae cells,and a magnetic field could adsorb the magnetic flocculated nanoparticles,thereby harvesting the microalgae cells.Harvesting efficiency was remarkably increased at the optimum magnetic field strength of 0.5 T with the magnetic flocculated nanoparticles at 0.738 g/L,and microalgae broth at pH 9.0,whereas the recovery rates of both C.pyrenoidosa and S.obliquus were around 97%and the sedimentation speed of both was above 2.63 cm/min.This study exemplified the magnetic flocculated nanoparticles-based approach to effectively harvest the microalgae cells.

ROS is essential for initiation of energy deprivation-induced autophagy

Autophagy is a highly conserved degradation process in which intracellular components are engulfed into a double membrane structure,known as the autophagosomes,and then delivered to lysosomes/vacuoles for degradation(Ohsumi,2014).Recently,autophagy has been found to be responsible for maintaining glucose homeostasis in adult animals(Karsli-Uzunbas et al.,2014).However,the molecular mechanism underlying energy deprivation-induced autophagy remains relatively unclear.