Chromium(III) Oxidation Coupled with Microbially Mediated Mn(II) Oxidation

Abstract

Reductive immobilization of Cr(VI) has been widely explored as a cost-effective approach for Cr-contaminated site remediation. In soils containing manganese oxides, however, the immobilized form of chromium, i.e., Cr(III), could potentially be reoxidized. In this study, batch experiments were conducted to assess whether there were any microbial processes that could accelerate Cr(III) oxidation in aerobic, manganese-containing systems. The results showed that in the presence of at least one species of manganese oxidizers, Pseudomonas putida, Cr(III) oxidation took place at low concentrations of Cr(III). About 30–50% of added Cr(III) (10–200 μ M) was oxidized to Cr(VI) within five days in the systems with P. putida and biogenic Mn oxides. The rate of Cr(III) oxidation was approximately proportional to the initial concentration of Cr(III) up to 100 μ M, but the growth of P. putida was partially inhibited by Cr(III) at 200 μ M and totally stopped when it reached 500 μ M. Cr(III) oxidation was dependent upon the biogenic formation of Mn oxides, though the oxidation rate was not directly proportional to the amount of Mn oxides formed. Chromium(III) oxidation took place through a catalytic pathway, in which the microbes mediated Mn(II) oxidation to form Mn-oxides, and Cr(III) was subsequently oxidized by the biogenic Mn-oxides.     

Egfr signaling controls the size of the stem cell precursor pool in the Drosophila ovary

In many animals, germline progenitors are kept undifferentiated to give rise to germline stem cells (GSCs), enabling continuous production of gametes throughout animal life. In the Drosophila ovary, GSCs arise from a subset of primordial germ cells (PGCs) that stay undifferentiated even after gametogenesis has started. How a certain population of PGCs is protected against differentiation, and the significance of its regulatory mechanisms on GSC establishment remain elusive. Here we show that epidermal growth factor receptor (Egfr) signaling in somatic stromal intermingled cells (ICs), activated by its ligand produced in germ cells, controls the size of the PGC pool at the onset of gametogenesis. Egfr signaling in ICs limits the number of cells that express the heparan sulfate proteoglycan Dally, which is required for the movement and stability of the locally-produced stromal morphogen, Decapentaplegic (Dpp, a BMP2/4 homologue). Dpp is received by PGCs and maintains them in an undifferentiated state. Altering Egfr signaling levels changes the size of the PGC pool and affects the number of GSCs established during development. While excess GSC formation is compensated by the adult stage, insufficient GSC formation can lead to adult ovarioles that completely lack GSCs, suggesting that ensuring an absolute size of the PGC pool is crucial for the GSC system.     

BIOLOGICAL RHYTHM RESEARCH,Circadian rhythms,monoamines and behaviorTitlepage and Contents

A spectral analysis of heart rate was carried out on 11 young female adults in order to evaluate the effects of bright light exposure on autonomic nervous activity. Bright light (5,000 lx) was provided by fluorescent lamps during the daytime (07:00–15:00) on day 1. Dim light (200 lx) was given on day 2. High frequency components (HF: 0.15–0.4Hz) were used as a marker of parasympathetic activity and the ratio of low frequency (LF: 0.04–0.15 HZ) to high frequency (LF/HF) as an indicator of sympathetic activity. The average value during the sleep period (23:30–06:30) was compared following diurnal exposure to bright or dim light. HF component was significantly greater from 23:30 to 02:00 after diurnal exposure of bright light, being accompanied by lower heart rate during these periods. There existed negative correlation between heart rate and HF component from 23:30 to 02:00 under diurnal exposure to bright and dim lights. The results indicate that bright light exposure during the daytime (07:00–15:00) could enhance parasympathetic activity around midnight.     

Pheno-Pub: a total support system for the publication of mouse phenotypic data on the web

We have developed an open-source database system named “Pheno-Pub” to support a series of data-handling and publication tasks, including statistical analyses, data review, and web site construction, for mouse phenotyping experiments. This system is composed of three applications. “Mou-Stat” provides semiautomatic statistical analyses for a batch of phenotypic data, including a variety of conditions for group comparisons (e.g., different scales of measurement parameters). “Genotype Viewer” and “Strain Viewer” provide representation of genotype-driven and measurement parameter-driven views of phenotypic data; they highlight significant differences in genotypes and between strains, respectively. Direct links from the Strain Viewer web site to the Genotype Viewer web site provide flexible navigation in the exploration of phenotypic data. With these publication tools, phenotypic data can be made available on the Internet by simple operations. This system is expandable for a wide range of uses in phenotypic comparative analyses, including comparisons among different genotypes and strains and comparisons among groups exposed to different environmental conditions. Finally, Pheno-Pub provides advanced usability for both producers of experimental data and consumers of phenotypic information. Therefore, Pheno-Pub contributes significantly to the publication of data in various fields of phenotyping research and to broad data sharing, thereby promoting the understanding of the functions of the entire mouse genome.     

A Stopped-Flow Method for the Determination of Ascorbic Acid in Orange Juice Containing Triose Reductone

The adsorption of uranium by chitin phosphate and chitosan phosphate was investigated to obtain information on uranium recovery from aqueous systems, especially sea water and uranium mine waste water. The adsorption of uranium by chitin phosphate and chitosan phosphate was much greater than copper, cadmium, manganese, zinc, cobalt, nickel, magnesium and calcium. The adsorption of uranium was very rapid during the first 10 min and was affected by pH of the solution, temperature, granule radius and the co-existence of carbonate ion. The amounts of uranium adsorbed on the adsorbents increased linearly as the external uranium concentration increased. Uranium adsorbed on chitin phosphate easily desorbed with diluted sodium carbonate solution. On the other hand, uranyl and cobalt ions were separated from each other by using chitin phosphate.     

Peptide-bound Lysinoalanine Absorbed and Transported to the Kidney—Observation in a Feeding Test with Rats

Specific interaction between green fluorescent protein (GFP)-tagged human α- or γ-enolase^97-242 (α or γENO^97-242) and the rhodamine-labeled DNA fragment containing the c-myc P2 promoter was detected by a fluorescence resonance energy transfer (FRET)-based assay, designated as a “real-time FRET assay.” The approach of donor (GFP) and acceptor (rhodamine) was caused by the association between ENO^97-242 and the c-myc P2 promoter, and the time-dependent increase in fluorescence intensity of the reaction mixture was observed at ex=400 nm and em=590 nm. The relative affinity (R_as) of ENO^97-242 mutants to the wild type was investigated with a real-time FRET assay, and it was clarified that the amino acids that participated in the interaction existed comparatively broadly. Although it was difficult to measure the absolute value of the affinity for the binding protein by using this method, it was possible to investigate the relative affinity of mutants for the wild type. A real-time FRET assay using the GFP-tagged protein could be used as not only a qualitative, but also as a quantitative analysis, this being the best for investigating the key amino acids in binding proteins.     

Changes in Glycolipid and Phospholipid Compositions in Cotyledons of Germinating Soybeans

This investigation was conducted to observe changes in the compositions of fatty acids, glycolipids (GL) and phospholipids (PL) in cotyledons of soybean seeds which were germinated either in the dark or the light at 28°C for 8 days. The patterns of changes in lipid composition depended on the germinating conditions tested. In general, non-polar lipids were metabolized at a faster rate than polar lipids. Changes in lipid contents in cotyledons were also observed more clearly with the polar lipids than with the non-polar ones, especially in the light-grown seedlings. The major component of lipid, GL in chloroplasts, appeared rapidly at an earlier stage in the cotyledons of light-grown seedlings. During germination of soybean seeds, acyl sterylglucoside in cotyledons decreased rapidly, but monogalactosyl diglyceride and digalactosyl diglyceride (DGD) increased in the light-grown seedlings, whereas sterylglucoside and DGD increased in the dark-grown seedlings.

The major PL present immediately after immersion were phosphatidyl ethanolamine (PE), phosphatidyl choline (PC) and phosphatidyl inositol (PI). During germination under both conditions, light and dark, PE in cotyledons decreased with PC or PI, while phosphatidic acid increased rapidly, and phosphatidyl glycerol and diphosphatidyl glycerol also increased slightly. These changes in glycolipid and phospholipid compositions during germination seem to occur from the formation of photosynthetic tissues and the metabolic interconversion of phospholipids.     

Fatty Acid Distribution in Glycolipids and Phospholipids in Cotyledons of Germinating Soybeans

This investigation was conducted to observe changes in the fatty acid distributions of glycolipids (GL) and phospholipids (PL) in cotyledons of soybean seeds which were germinated either in the dark or the light at 28°C for 8 days. The GL isolated from the total lipids of cotyledons at different germinating stages were : acyl sterylglycoside (ASG), monogalactosyl diglyceride (MGD), digalactosyl diglyceride (DGD) and sulfolipid (SL). The PL isolated from the same total lipids as described above were : diphosphatidyl glycerol (DPG), phosphatidic acid (PA), phosphatidyl ethanolamine (PE), phosphatidyl glycerol (PG), phosphatidyl choline (PC) and phosphatidyl inositol (PI).

During germination of soybean seeds, the content of linoleic and linolenic acids in MGD or DGD was markedly higher than that of the other GL. The positional distribution of fatty acids in PE, PC and PI was shown in all PL, in which saturated fatty acids, especially palmitic acid, were highly concentrated in position 1 and unsaturated fatty acids, especially linoleic acid, mainly occupied position 2. A remarkable difference in the changing patterns of fatty acid composition, which depended on the germinating conditions tested, was observed between GL and PL. The changes in fatty acid composition of GL were more marked in the light-grown seedlings than in the dark-grown, whereas those of PL were more remarkable in the latter than in the former. Therefore, the positional distribution of fatty acids in PL was more evident in the light-grown seedlings than in the dark-grown ones.

These results suggest the metabolic fate of GL and PL in cotyledons of soybean seeds, probably owing to the differences in the two germinating conditions tested.