Biophysical Investigation of the 'Ironome' of Jurkat Cells and Saccharomyces cerevisiae

The speciation of iron in intact Jurkat cells and their isolated mitochondria was assessed using biophysical methods. [Fe4S4]^(2+) clusters, low-spin (LS) Fe^(II) heme centers, non-heme high-spin (NHHS) FeII species, ferritin-like material and FeIII oxyhydroxide nanoparticles were detected, via Mössbauer, in intact Jurkat cells and their isolated mitochondria. EPR spectroscopy was used to quantify Fe-containing species in the respiratory complexes. Contributions from heme a, b and c centers were quantified using electronic absorption spectroscopy. Results were collectively assessed to estimate the first “ironome” profile of a human cell. The Fe content of Jurkat cells grown on transferrin-bound iron (TBI) and Fe^(III) citrate (FC), and of isolated mitochondria therefrom, was characterized. On average, only 400 ± 100 Fe’s loaded per ferritin complex, regardless of the medium Fe concentration. The extent of nanoparticle formation scaled nonlinearly with the concentration of FC in the medium. Nanoparticle formation was not strongly correlated with ROS damage. Cells could utilize nanoparticles Fe, converting them into essential Fe forms. Cells grown on galactose rather than glucose respired faster, grew slower, exhibited more ROS damage, and generally contained more nanoparticles. Cells grown with TBI rather than FC contained lower Fe concentrations, more ferritin and fewer nanoparticles. Frataxin-deficient cells contained more nanoparticles than comparable WT cells. Data were analyzed by a chemically-based mathematical model. Fermenting Saccharomyces cerevisiae cells grown with varying [Fe] were also studied. The high-affinity Fe import pathway was active only in Fe-deficient cells. Whether Fe-deficient cells were grown under fermenting or respirofermenting conditions had no effect on Fe content; such cells prioritized their use of Fe to essential forms devoid of nanoparticles and vacuolar Fe. Fermenting cells grown on Fe-sufficient and Fe-overloaded medium contained 400 – 450 µM Fe. In these cells the concentration of nonmitochondrial NHHS Fe^(II) declined 3-fold, relative to in Fe-deficient cells, whereas the concentration of vacuolar NHHS Fe^(III) increased to a limiting cellular concentration of ~ 300 µM. Isolated mitochondria contained more NHHS Fe^(II) ions and substantial amounts of Fe^(III) nanoparticles. The Fe contents of cells grown with excessive Fe in the medium were similar over a 250-fold change of nutrient Fe levels

Aerosol optical depth studies during INDOEX: comparison of the spectral features over coastal India with the pristine southern hemispheric environment over Mauritius

Aerosol spectral optical depths, estimated using a ground-based network of multi wavelength radiometers (MWR) along the west coast of India [Trivandrum (TVM; 8.5°N, 77°E), and Minicoy (MCY; 8.3°N, 73.04°E)] and the pristine southern hemispheric environment at Mauritius (MRU; 20.26°S, 57.54°E) during the period January to June 1998 along with those obtained over the Arabian Sea and Indian Ocean during the INDOEX FFP-98 cruise (SK133) of ORV Sagar Kanya, are used to study the inter-hemispheric features of aerosols. Results indicate that there is a significant hemispherical difference for aerosol spectral optical depth (AOD) at shorter wavelengths (λ≤ 650 nm), while at the longer wavelengths (λ > 650 nm), AOD does not show any appreciable variation with location. The spectral variation of AOD at TVM and MCY (for March 1998) depicted a similar pattern with the AOD values between 0.5 and 0.6 at shorter wavelengths and between 0.2 and 0.4 at longer wavelengths. In contrast to this, the AOD at MRU are very low, lying in the range 0.1 to 0.2 in the shorter wavelengths, whereas at the longer wavelengths the AOD values are more or less comparable (in the range 0.2 to 0.4) with the northern hemispheric stations. The cruise data clearly showed that the transition occurs generally across the ITCZ. The increased AOD at shorter wavelengths in the northern hemisphere indicates higher concentration of sub-micron aerosols in these environments arising mainly due to anthropogenic activities, while the AOD at the longer wavelengths is attributed mainly to be of marine origin. In the post-cruise period, the spectral optical depths showed a gradual increase from March to June at MRU, while at TVM, the pattern followed more or less the climatological mean. By May the AOD at shorter wavelengths decreased at TVM (due to increased rainfall) and by June, the AOD at TVM are very much comparable with those seen at MRU, indicating a dominating marine aerosol influence at both these locations. The implications are discussed

Installation of an automatic spectrometer at Mauritius and preliminary results of NO2 over Mauritius

An automatic spectrometer developed at Indian Institute of Tropical Meteorology Pune is installed at the University of Mauritius, Reduit, Mauritius for monitoring total column density of NO2 and O3. The spectrometer is programmed for observations between 80° and 90° solar zenith angles in the spectral region 410-450 nm. The observations collected for few days during September and October 1998 are analysed, and total column densities of NO2 found to be of the order of 4* 1015 molecules per cm2. This preliminary result compares with similar southern latitude stations

Synthesis of Hydrophilic and Amphiphilic Acryl Sucrose Monomers and Their Copolymerisation with Styrene, Methylmethacrylate and α- and β-Pinenes

Herein, we report the synthesis of monomethacryloyl sucrose esters, and their successful free radical homo- and co-polymerisation with styrene, methylmethacrylate, α-and β-pinene. The chemical, physical, structural and surface chemical properties of these polymers, containing a hydrophobic olefin backbone and hydrophilic sugar moieties as side chains, have been investigated. Biodegradation tests of the copolymer samples by a microbial fungal culture (Aspergillus niger) method showed good biodegradability. The chemical structure and surface chemistry of the synthesized homo- and co-polymers demonstrate their potential technological relevance as amphiphilic and biodegradable polymers

Synthese et caracterisation de polymeres a base de sacharose

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 82441 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

A Review Of New Trends In Lactide Polymerisation Based On Metal Complexes

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