FIB-SEM combined with proteomics and modification omics clarified mechanisms of lipids synthesis in organelles of Chlorella pyrenoidosa cells with high CO2 concentration.

In order to explain reasons why flue-gas CO2 (normally containing high CO2) enhanced carbon fixation and lipids synthesis with increased photochemical electron production in microalgae cells. Focused ion beam scanning electron microscopy (FIB-SEM) was combined with proteomics and phosphorylation modification mics to clarify mechanisms of lipids synthesis at protein and organelle levels in Chlorella pyrenoidosa cells cultivated with high CO2 concentration (15 % v/v). The volumes of chloroplast and endoplasmic reticulum in subcellular organelles increased by 47 % and 306 %, respectively, compared with the control, which improved conversion efficiency of starch grains to lipids (lipid content increased by 57 %). Proteomics and modifications omics revealed that protein translation and ribosome structure and biogenesis-related enzymes were significantly modified by phosphorylation, which regulated protein biological functions. Glycolysis, pentose phosphate pathway and other carbohydrate metabolic pathways were markedly enriched and promoted the expression of lipid synthase, which was consistent with enhanced carbon fixation in photosynthesis, expansion of subcellular organelles and improved lipids synthesis.

Functional metabolism pathways of significantly regulated genes in Nannochloropsis oceanica with various nitrogen/phosphorus nutrients for CO2 fixation.

To determine the optimal CO2 concentration for microalgal biomass cultivated with industrial flue gas and improve carbon fixation capacity and biomass production. Functional metabolism pathways of significantly regulated genes in Nannochloropsis oceanica (N. oceanica) with various nitrogen/phosphorus (N/P) nutrients for CO2 fixation were comprehensively clarified. At 100 % N/P nutrients, the optimum CO2 concentration was 70 % and the maximum biomass production of microalgae was 1.57 g/L. The optimum CO2 concentration was 50 % for N or P deficiency and 30 % for both N and P deficiency. The optimal combination of CO2 concentration and N/P nutrients caused significant up regulation of proteins related to photosynthesis and cellular respiration in the microalgae, enhancing photosynthetic electron transfer efficiency and carbon metabolism. Microalgal cells with P deficiency and optimal CO2 concentration expressed many phosphate transporter proteins to enhance P metabolism and N metabolism to maintain a high carbon fixation capacity. However, inappropriate combination of N/P nutrients and CO2 concentrations caused more errors in DNA replication and protein synthesis, generating more lysosomes and phagosomes. This inhibited carbon fixation and biomass production in the microalgae with increased cell apoptosis.

Three-dimensional analysis of membrane structures associated with tomato spotted wilt virus infection.

To study viral infection, the direct structural visualization of the viral life cycle consisting of virus attachment, entry, replication, assembly and transport is essential. Although conventional electron microscopy (EM) has been extremely helpful in the investigation of virus-host cell interactions, three-dimensional (3D) EM not only provides important information at the nanometer resolution, but can also create 3D maps of large volumes, even entire virus-infected cells. Here, we determined the ultrastructural details of tomato spotted wilt virus (TSWV)-infected plant cells using focused ion beam scanning EM (FIB-SEM). The viral morphogenesis and dynamic transformation of paired parallel membranes (PPMs) were analyzed. The endoplasmic reticulum (ER) membrane network consisting of tubules and sheets was related to viral intracellular trafficking and virion storage. Abundant lipid-like bodies, clustering mitochondria, cell membrane tubules, and myelin-like bodies were likely associated with viral infection. Additionally, connecting structures between neighboring cells were found only in infected plant tissues and showed the characteristics of tubular structure. These novel connections that formed continuously in the cell wall or were wrapped by the cell membranes of neighboring cells appeared frequently in the large-scale 3D model, suggesting additional strategies for viral trafficking that were difficult to distinguish using conventional EM.

FIB-SEM analysis on three-dimensional structures of growing organelles in wild Chlorella pyrenoidosa cells.

To clarify dynamic changes of organelle microstructures in Chlorella pyrenoidosa cells during photosynthetic growth with CO2 fixation, three-dimensional (3D) organelle microstructures in three growth periods of meristem, elongation, and maturity were quantitatively determined and comprehensively reconstructed with focused ion beam scanning electron microscopy (FIB-SEM). The single round-pancake mitochondria in each cell split into a dumbbell and then into a circular ring, while the barycenter distance of mitochondria to chloroplast and nucleus was reduced to 45.5% and 88.3% to strengthen energy transfer, respectively. The single pyrenoid consisting of a large part and another small part in each chloroplast gradually developed to a mature state in which the two parts were nearly equal in size. The nucleolus progressively became larger with euchromatin replication. The number of starch grains gradually increased, but the mean grain volume remained nearly unchanged.

Hierarchical ultrastructure: An overview of what is known about tendons and future perspective for tendon engineering.

Abnormal tendons are rarely ever repaired to the natural structure and morphology of normal tendons. To better guide the repair and regeneration of injured tendons through a tissue engineering method, it is necessary to have insights into the internal morphology, organization, and composition of natural tendons. This review summarized recent researches on the structure and function of the extracellular matrix (ECM) components of tendons and highlight the application of multiple detection methodologies concerning the structure of ECMs. In addition, we look forward to the future of multi-dimensional biomaterial design methods and the potential of structural repair for tendon ECM components. In addition, focus is placed on the macro to micro detection methods for tendons, and current techniques for evaluating the extracellular matrix of tendons at the micro level are introduced in detail. Finally, emphasis is given to future extracellular matrix detection methods, as well as to how future efforts could concentrate on fabricating the biomimetic tendons.

A novel porous nickel-foam filled CO2 absorptive photobioreactor system to promote CO2 conversion by microalgal biomass.

In order to solve problems associated with a short residence time and low conversion efficiency when CO2 gas is aerated directly into raceway ponds, a novel porous nickel-foam filled CO2 absorptive photobioreactor system was developed to promote CO2 conversion to NaHCO3 in a short time to improve photosynthesis of microalgal cells. Numerical simulation showed that the porous nickel-foam promoted the Na2CO3 solution radial velocity and CO2 volume fraction in the CO2 absorption reactor, which enhanced the reaction rate of CO2 gas and soluble Na2CO3. The conversion efficiency of CO2 gas to soluble NaHCO3 gradually increased with an increasing nickel-foam pore diameter and a decreasing CO2 gas outflow rate, while it first increased and then decreased with an increasing relative nickel-foam height in the CO2 absorption reactor. The conversion efficiency from soluble NaHCO3 to microalgal biomass first increased and then decreased with an increasing nickel-foam pore diameter (peaking at 2 mm) and relative height (peaking at 0.24); and CO2 gas outflow rate (peaking at 2 L/min). The chlorophyll fluorescence measurements showed that a sufficient HCO3- supply promoted the quantum ratio used for electron transfer (from 0.19 to 0.23) and the maximum photochemical efficiency (from 0.48 to 0.52), resulting in an increased biomass growth rate (by 1.1 times) when the nickel-foam pore diameter increased from 0.1 to 2 mm.