Observation Of Zn Research Articles

Chemical imaging of molecular changes in a hydrated single cell by dynamic secondary ion mass spectrometry and super-resolution microscopy.

Chemical imaging of single cells at the molecular level is important in capturing biological dynamics. Single cell correlative imaging is realized between super-resolution microscopy, namely, structured illumination microscopy (SIM), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) using a multimodal microreactor (i.e., System for Analysis at the Liquid Vacuum Interface, SALVI). SIM characterized cells and guided subsequent ToF-SIMS analysis. Lipid fragments were identified in the cell membrane via dynamic ToF-SIMS depth profiling. Positive SIMS spectra show intracellular potassium and sodium ion transport due to exposure to nanoparticles. Spectral principal component analysis elucidates differences in chemical composition among healthy alveolar epithelial mouse lung C10 cells, cells that uptake zinc oxide nanoparticles, and various wet and dry control samples. The observation of Zn(+) gives the first direct evidence of ZnO NP uptake and dissolution by the cell membrane. Our results provide submicron chemical mapping for investigating cell dynamics at the molecular level.

TSQ (6-Methoxy-8-p-Toluenesulfonamido-Quinoline), a Common Fluorescent Sensor for Cellular Zinc, Images Zinc Proteins

Zn(2+) is a necessary cofactor for thousands of mammalian proteins. Research has suggested that transient fluxes of cellular Zn(2+) are also involved in processes such as apoptosis. Observations of Zn(2+) trafficking have been collected using Zn(2+) responsive fluorescent dyes. A commonly used Zn(2+) fluorophore is 6-methoxy-8-p-toluenesulfonamido-quinoline (TSQ). The chemical species responsible for TSQ's observed fluorescence in resting or activated cells have not been characterized. Parallel fluorescence microscopy and spectrofluorometry of LLC-PK(1) cells incubated with TSQ demonstrated punctate staining that concentrated around the nucleus and was characterized by an emission maximum near 470 nm. Addition of cell permeable Zn-pyrithione resulted in greatly increased, diffuse fluorescence that shifted the emission peak to 490 nm, indicative of the formation of Zn(TSQ)(2). TPEN (N,N,N'N'-tetrakis(-)[2-pyridylmethyl]-ethylenediamine), a cell permeant Zn(2+) chelator, largely quenched TSQ fluorescence returning the residual fluorescence to the 470 nm emission maximum. Gel filtration chromatography of cell supernatant from LLC-PK(1) cells treated with TSQ revealed that TSQ fluorescence (470 nm emission) eluted with the proteome fractions. Similarly, addition of TSQ to proteome prior to chromatography resulted in 470 nm fluorescence emission that was not observed in smaller molecular weight fractions. It is hypothesized that Zn-TSQ fluorescence, blue-shifted from the 490 nm emission maximum of Zn(TSQ)(2), results from ternary complex, TSQ-Zn-protein formation. As an example, Zn-carbonic anhydrase formed a ternary adduct with TSQ characterized by a fluorescence emission maximum of 470 nm and a dissociation constant of 1.55 × 10(-7) M. Quantification of TSQ-Zn-proteome fluorescence indicated that approximately 8% of cellular Zn(2+) was imaged by TSQ. These results were generalized to other cell types and model Zn-proteins.

First Observation of Zn−CN Bond in “Highly Coordinated” Mixed Organozincates by EXAFS Spectroscopy

First Observation of Zn−CN Bond in “Highly Coordinated” Mixed Organozincates by EXAFS Spectroscopy

High-Resolution [ITAL]Hubble Space Telescope[/ITAL] Observations of Zn [CSC]ii[/CSC] and Cr [CSC]ii[/CSC] Absorption toward the Magellanic Clouds

We present high-resolution (3.5 km s-1) spectra of Zn II and Cr II absorption obtained with the Hubble Space Telescope toward four Magellanic Cloud stars. We have detected absorption from the full extent of the Milky Way disk + halo with an average depletion measure of [Cr/Zn] = -1.07 ? 0.05. In addition, we identify absorption from the LMC toward two stars and from the SMC toward one of our targets. We find that the depletion of Cr relative to Zn in the Magellanic Clouds is comparable to that of the Milky Way interstellar medium (ISM). Assuming similar dust composition, the dust-to-metals ratio in the Galactic or Magellanic Cloud ISM is at least a factor of 2 higher than in damped Ly? QSO absorbers.