Continuous live cell imaging of cellulose attachment by microbes under anaerobic and thermophilic conditions using confocal microscopy

Live cell imaging methods provide important insights into the dynamics of cellular processes that cannot be derived easily from population-averaged datasets.In the bioenergy field,much research is focused on fermentation of cellulosic biomass by thermophilic microbes to produce biofuels;however,little effort is dedicated to the development of imaging tools to monitor this dynamic biological process.This is,in part,due to the experimental challenges of imaging cells under both anaerobic and thermophilic conditions.Here an imaging system is described that integrates confocal microscopy,a flow cell device,and a lipophilic dye to visualize cells.Solutions to technical obstacles regarding suitable fluorescent markers,photodamage during imaging,and maintenance of environmental conditions during imaging are presented.This system was utilized to observe cellulose colonization by Clostridium thermocellum under anaerobic conditions at 60℃.This method enables live cell imaging of bacterial growth under anaerobic and thermophilic conditions and should be widely applicable to visualizing different cell types or processes in real time.     

Cantilever nanobiosensor using tyrosinase to detect atrazine in liquid medium

The aim of this study was to develop a cantilever nanobiosensor for atrazine detection in liquid medium by immobilising the biological recognition element (tyrosinase vegetal extract) on its surface with self-assembled monolayers using gold, 16-mercaptohexadecanoic acid, 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/n-hydroxysuccinimide. Cantilever nanobiosensors presented a surface compression tension increase when atrazine concentrations were increased, with a limit of detection and limit of quantification of 7.754 ppb (parts per billion) and 22.792 ppb, respectively. From the voltage results obtained, the evaluation of atrazine contamination in river and drinking water were very close to those of the reference sample and ultrapure water, demonstrating the ability of the cantilever nanobiosensor to distinguish different water samples and different concentrations of atrazine. Cantilever nanosensor surface functionalization was characterised by combining polarisation modulation infrared reflection-absorption spectroscopy and atomic force microscopy and indicating film thickness in nanometric scale (80.2 ± 0.4 nm). Thus, the cantilever nanobiosensor developed for this study using low cost tyrosinase vegetal extract was adequate for atrazine detection, a potential tool in the environmental field.     

Novel method for in situ visualization of polycyclic aromatic hydrocarbons in mangrove plants

Two-photon laser confocal scanning microscopy (TPLCSM) was first used to visualize the uptake and movement of naphthalene (NAP), phenanthrene (PHE), and pyrene (PYR), from separately contaminated hydroponics solutions into living Kandelia candel (L.) Druce seedlings. With this non-destructive and non-chemical extraction technique, the experimental results revealed that three types of polycyclic aromatic hydrocarbons (PAH) were observed moving into the K. candel and its translocation to radicle, hypocotyl and leaf, and the transmission rates of these PAH in the K. candel were in the order of NAP?>?PHE?>?PYR. Data demonstrate the manner in which PAH enter, transport, and distribute within the K. candel, and provided us some valuable information on uptake and translocation mechanism of PAH. These findings may help to optimize the phytoremediation strategies of PAH in mangrove wetlands.     

Noise exposure of pregnant mice induces heart defects in their fetuses

To determine the effects of noise exposure on hearts of newborn mice, 48 pregnant mice were exposed to recorded aircraft flight noise (100?dB) for 150?min from the 2nd day of pregnancy to 7th day after delivery. Mice of the same age were selected as control group. The weights and crown-rump lengths of the fetuses and the newborns were measured, and their hearts were removed under deep anesthesia on the 1st, 7th, and 14th days after birth and prepared histologically. Quantitative changes of the hearts were measured stereologically by the Cavalieri method. The ultrastructural changes of cardiac myocytes were examined using transmission electron microscopy. No histological changes were observed, but the volumes of newborns’ hearts in the experimental groups increased significantly compared to the control group. Photomicrographs of cardiac muscle cells revealed nuclear envelope changes, chromatin condensation, and increased mitochondria and myofibrils in noise-exposed newborns. It is concluded that the newborns of pregnant mice exposed to noise stress have hypertrophic hearts with ultrastructural changes.     

Effect of Cd++ on germination,growth and active principles of Datura metel L.∗

The effects of Cd⁺⁺ concentration increment in soil and/or in atmosphere, on germination, growth and alkaloid contents of Datura metel L. were investigated. We observed a significant reduction of growth following addition of Cd⁺⁺ in soil. Minor effects on growth were evident when the plants were sprayed with CdCl₂ solution (10mgCd⁺⁺/l).

Scanning electron microscope observation showed stomata widely open and conspicuous cuticular striations in the foliar epidermis of polluted plants.

GLC analysis of extracts evidenced a significant variation in active principle content among plants undergoing different treatments.     

硫酸根离子与聚合铝的反应过程及其产物形态

对不同Al/SO2-4比及碱化度条件下PACl与SO₄^2-的反应过程进行研究,分析了体系中总铝浓度及形态分布变化规律,测定了各沉淀/结晶产物的组成,并对其形貌进行了扫描电镜观察.实验结果表明:碱化度对PACl/SO₄^2-反应体系有较大影响,随着碱化度(B值)的增加,沉淀/结晶的析出速率加快,结果析出物中OH含量逐渐增加,而SO₄^2-/Al比率从0.45～0.30逐渐降低.各聚合铝水解形态与SO₄^2-反应速率上存在明显差异,从而为其混凝优势形态的分离纯化创造了条件.     

Changes of Surface Properties of Yeast Cell Wall Under Exposure of Electromagnetic Field (40.68 MHz) and Action of Nystatin

Summary Changes of the surface properties were studied in the cell wall of the yeast Saccharomyces cerevisiae Y-517 under influence of the electromagnetic field (EMF) (40.68 MHz) and lethal doses of the fungicidal antibiotic nystatin (10 μg/10⁶ cells). Atomic force microscopy was used to study surface topography and visco-elastic properties of the cell walls. Surface carbohydrates were detected by lectins marked with gold with the help of the scanning electron microscope. Additional polysaccharide layer appeared over cell surface after EMF exposure. We suggest that electromagnetic fields resulted in the change of the cell surface, and, accordingly, the sensitivity of organisms to the antifungal antibiotics.     

Visualization of the Malleability of the Rubber Core of Rubber Particles from Parthenium argentatum Gray and Other Rubber-Producing Species Under Extremely Cold Temperatures

Rubber particles from Parthenium argentatum Gray (guayule) were frozen in liquid nitrogen (–196°C), fractured, and visualized using cryo-scanning electron microscopy. We observed that the rubber polymer core of the rubber particles was still malleable at this extremely cold temperature, and the core stretched substantially during separation of the fracture planes. This malleability was observed in situ in tissue sections, as well as in purified rubber particles, and was found to be independent of purification procedure, guayule line, tissue age, or season. The malleability or stretching phenomenon suggests that P. argentatum rubber has some unique properties because rubber particles from Hevea brasiliensis Müll. Arg. and Ficus elastica Roxb. were brittle at this temperature, fractured cleanly, or showed only tiny threads of material pulling out of the core.     

Biochemical and histopathological ultrastructural changes caused by ZnO nanoparticles in mice

Five week-old mice were divided into a vehicle control group, and groups exposed to ZnO nanoparticles at low (0.5 g/kg), middle (1 g/kg), high (3 g/kg), and exceptionally high-dose (5 g/kg). After the first, second, third, and fourth weeks’ of exposure, blood biochemistry, histopathology, and electron microscopic ultrastructural changes in liver, kidney and spleen were investigated. Increased alkaline phosphatase activities were observed in all treated mice being statistically significant at higher dose. No changes were observed in the serum glutamic pyruvic transaminase, serum glutamic oxaloacetic transaminase, creatinine, blood urea nitrogen, and lipid levels. During the first and second weeks of the treatment, effects on the cytoarchitecture of liver, kidney, and spleen were not perceived while during the third and fouth weeks of treatment sporadic mild effects were seen. Ultrastructural electron microscopic changes in liver, kidney, and spleen were not observed for the low-dose group on the first, second, third, and fourth weeks, suggesting that exposure to ZnO nanoparticles at low dose is safe. Long-term (i.e., more than 28 days) exposure to the exceptionally high-dose resulted in sporadic changes in nuclear chromatin condensation, irregular nuclear membrane, polymorphic mitochondria, mitochondrial swelling, and vacuolation. ZnO nanoparticles could be well tolerated and no death occurred in any group of treated mice.