Improving sample preparation to investigate lignin intensity of xylem at the cellular level by confocal Raman microspectroscopy of Populus tomentosa

Confocal Raman microspectroscopy(CRM)is an important tool for analyzing the compositional distribution of cell walls in situ.In this study,we improved the sample preparation method using paraffin-embedded sections combined with hexane dewaxing to obtain high resolution Raman images.We determined that the cell wall components of fiber cells were different from those of ray cells and vessel cells in the xylem of Populus tomentosa.Acetyl bromide and CRM methods produced similar trends when the difference in lignin intensity in the xylem region was compared between transgenic PtrLac4 and wild-type P.tomentosa.However,CRM proved more useful to analyze the lignin distribution in each cell type and distinguished the detailed difference in lignin intensity at the cellular level.Thus,CRM proved to be a useful in situ method to rapidly analyze the spatial variation of lignin content in the xylem of woody plants.

Raman Microspectroscopy as a Unique Method of the Investigation of Acid Proof Steel Foil Oxidation

In this paper, the results of the investigation of the morphology and phase composition of the oxide layers formed on the surface of the 1H18N9T acid proof steel foil by confocal Raman micro-spectroscopy with optical microscopy, SEM, XRD and TEM-EDS-SADP are presented. The foil oxidation was performed by thermo-programmed heating up to 823, 1023 or 1113 K and next annealing at the final temperatures in the air flow for 48 h, 4 h and 4 h, respectively. The great advantages of the use of the Raman spectroscopy for the phase determining in the oxide layers on the acid proof steel foil are shown. Moreover the possibility of applying the optical microscopy for investigation of the surface morphology of both the initial steel foil and the oxide layers is pointed out.

Trans-cinnamaldehyde inhibits Penicillium italicum by damaging mitochondria and inducing apoptosis mechanisms

Plant-derived essential oils have excellent antifungal effects and can be used for the preservation of fresh foods such as fruits and vegetables, but the detailed mechanism has not been fully elucidated. In this study, we investigated the inhibitory effects of trans-cinnamaldehyde on Penicillium italicum, a common pollution fungus in citrus, and explored the antifungal mechanism of trans-cinnamaldehyde by detecting fungal oxidative damage, mitochondrial metabolism, and cell apoptosis. These results showed that transcinnamaldehyde made the carboxylic acid cycle deregulated by altering the related enzyme activities(succinate dehydrogenase, malate dehydrogenase) and mid product. Moreover, the level of reactive oxygen species rose sharply while the redox level was out of regulation. The mitochondrial membrane potential collapsed, leading to the leakage of cytochrome c, and then triggering the activation of apoptotic protease, which was further confirmed by the significant increase in caspase-3 activity from(3.6 ± 0.6) U to(8.8 ± 1.1) U(P < 0.05). The cytochrome c in mitochondria was detected by confocal Raman microspectroscopy, the characteristic intensity index(I750/I2944) was decreased, indicating that the cytochrome c in mitochondria was reduced and leakage. Besides, the strong negative correlation between Raman intensity and the amount of cytochrome c leakage was established with the correlation coefficient of-0.981 7. This study revealed that destroying the integrity of the mitochondrial membrane, activating the mitochondrial-mediated apoptosis pathway was the in-depth antifungal mechanism of trans-cinnamaldehyde;and Raman spectroscopy technology provided new ideas to study this process with high sensitivity determination of cytochrome c.

Culture-free identification of fast-growing cyanobacteria cells by Raman-activated gravity-driven encapsulation and sequencing

By directly converting solar energy and carbon dioxide into biobased products,cyanobacteria are promising chassis for photosynthetic biosynthesis.To make cyanobacterial photosynthetic biosynthesis technology economically feasible on industrial scales,exploring and engineering cyanobacterial chassis and cell factories with fast growth rates and carbon fixation activities facing environmental stresses are of great significance.To simplify and accelerate the screening for fast-growing cyanobacteria strains,a method called Individual Cyanobacteria Vitality Tests and Screening(iCyanVS)was established.We show that the ^(13)C incorporation ratio of carotenoids can be used to measure differences in cell growth and carbon fixation rates in individual cyanobacterial cells of distinct genotypes that differ in growth rates in bulk cultivations,thus greatly accelerating the process screening for fastest-growing cells.The feasibility of this approach is further demonstrated by phenotypically and then genotypically identifying individual cyanobacterial cells with higher salt tolerance from an artificial mutant library via Raman-activated gravity-driven encapsulation and sequencing.Therefore,this method should find broad applications in growth rate or carbon intake rate based screening of cyanobacteria and other photosynthetic cell factories.