Quantitative Proteomic Analysis Reveals the Key Molecular Events Driving Phaeocystis globosa Bloom and Dissipation.

Phaeocystis globosa is a marine-bloom-forming haptophyte with a polymorphic life cycle alternating between free-living cells and a colonial morphotype, that produces high biomass and impacts ecological structure and function. The mechanisms of P. globosa bloom formation have been extensively studied, and various environmental factors are believed to trigger these events. However, little is known about the intrinsic biological processes that drive the bloom process, and the mechanisms underlying P. globosa bloom formation remain enigmatic. Here, we investigated a P. globosa bloom occurring along the Chinese coast and compared the proteomes of in situ P. globosa colonies from bloom and dissipation phases using a tandem mass tag (TMT)-based quantitative proteomic approach. Among the 5540 proteins identified, 191 and 109 proteins displayed higher abundances in the bloom and dissipation phases, respectively. The levels of proteins involved in photosynthesis, pigment metabolism, nitrogen metabolism, and matrix substrate biosynthesis were distinctly different between these two phases. Ambient nitrate is a key trigger of P. globosa bloom formation, while the enhanced light harvest and multiple inorganic carbon-concentrating mechanisms support the prosperousness of colonies in the bloom phase. Additionally, colonies in the bloom phase have greater carbon fixation potential, with more carbon and energy being fixed and flowing toward the colonial matrix biosynthesis. Our study revealed the key biological processes underlying P. globosa blooms and provides new insights into the mechanisms behind bloom formation.

[Algicidal activity against red-tide algaes by marine bacterial strain N3 isolated from a HABs area, southern China].

A marine algicidal bacterium N3 was isolated from a HABs area in Mirs Bay, a subtropical bay, in southern China. Algicidal activity and algicidal mode against Phaeodactylum tricornutum, Scrippsiella trochoidea, Prorocentrum micans and Skeletonema costatum were observed by the liquid infection method. The results showed that there were no algicidal activities against P. tricornutum and S. costatum. However, when the bacterial volume fractions were 2% and 10% , S. trochoidea and P. micans could be killed, respectively. S. trochoidea cells which were exposed to strain N3 became irregular in shape and the cellular components lost their integrity and were decomposed. While, the P. micans cells became inflated and the cellular components aggregated, followed by cell lysis. Strain N3 killed S. trochoidea and P. micans directly, and the algicidal activities of the bacterial strain N3 was concentration-dependent. To S. trochoidea, 2% (V/V) of bacteria in algae showed the strongest algicidal activity, all of the S. trochoidea cells were killed within 120 h. But the growth rates of cells, in the 1% and 0. 1% treatment groups, were only slightly lower than that in the control group. In all treatment groups, the densities of strain N3 were in declining trends. While, to P. micans, 10% and 5% of bacteria in algae showed strong algicidal activities, 78% and 70% of the S. trochoidea were killed within 120 h, respectively. However, the number of S. trochoidea after exposure to 1% of bacterial cultures still increased up to 5 incubation days. And in the three treatment groups, the densities of strain N3 experienced a decrease process. The isolated strain N3 was identified as Bacillus sp. by morphological observation, physiological and biochemical characterization, and homology comparisons based on 16S rRNA sequences.

[Biomechanical study of new type two-head automatic pressure external fixator (TAPEF) for the treatment of intertrochanteric fracture].

OBJECTIVE: To investigate the mechanical characteristics of new type two-head automatic pressure external fixator in the view of biomechanics. METHODS: Fifteen fresh and humid specimens were selected and divided into experimental group (5 cases) and control group (10 cases). The control group were respectively applied with DHS (5 cases) and traditional external fixator (5 cases). In order to compare the different apparatus, the strength, stiffness and twist mechanical function of femoral intertrochanteric fracture with different device were measured respectively when the specimens were under the pressure of 0-1800 N and loading speed 1.4 mn/min. RESULTS: The strength, stiffness, twist mechanical function and maximum endurance of femora in the experimental group were obviously superior than that of DHS and traditional external fixator (P < 0.05). CONCLUSION: Two head automatic new type pressure external fixator can embed more tightly without sliding, also can prevent the occurrence of coxa vara effectively.