The six‐satellite Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) mission makes routine ionospheric measurements over the entire globe using occultation techniques. These observations have been used in this study to develop global‐scale climate maps of NmF2 and hmf2 during the southern (northern) summer (winter). Enhanced electron densities that appear to be associated with the southern, equatorial (Appleton) anomaly are displaced far southward at dusk and, within about an hour, form the Weddell Sea anomaly. Coincidentally, the height of the F2 peak increases on the northern boundary of this anomaly. This height increase is also displaced southward as the enhanced electron densities are displaced southward, suggesting that the electron density increases are associated with the F2 peak rising. As well as being an interesting phenomenon in its own right, this behavior may shed new light on the formation of the Weddell Sea anomaly. No unambiguous explanation for this behavior can be determined from the data presently available, but an examination of some possibilities suggests that an evening downward flux of plasma from the plasmasphere may be at least partly responsible for the phenomenon.

Increased glutathione (GSH) level occurs early during liver regeneration and in many drug and/or radiation-resistant tumors. Whether GSH level is elevated in liver cancer is unknown. GSH levels and expression of GSH synthetic enzymes were measured in hepatocellular carcinoma (HCC) and normal liver. GSH levels doubled in HCC. The mRNA levels of g-glutamylcysteine synthetase heavy subunit (GCS-HS) and GSH synthetase (GS) doubled, whereas the expression of GCS light subunit was unchanged. Nuclear run-on assay showed that the rate of gene transcription doubled for both GCS-HS and GS. In HCC, there is increased binding to anti-oxidant response, AP-1 and NF-kB, three cis-acting elements in the 5'-flanking region of the human GCS-HS important for its transcriptional regulation. The role of GSH in cell growth was examined by using HepG2 cells. Cell GSH level was varied by treating cells with cystine (0 to 0.2 mM) with or without GSH ester or buthionine sulfoximine. Cell GSH level correlated directly with growth rate. Finally, preventing the increase in GSH after two-thirds partial hepatectomy blunted liver regeneration. Thus, GSH level is increased during liver growth as a result of up-regulation of GCS-HS and GS. This increase, in turn, facilitates growth.

Lasso peptides, a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) secreted by bacteria, have antimicrobial activity. Here, a novel lasso peptide, microcin Y (MccY), was discovered and characterized. The gene cluster for MccY synthesis was cloned for expression in Escherichia coli. This peptide was purified by HPLC and characterized by Q-TOF. MIC assays showed that some Bacillus, Staphylococcus, Pseudomonas, Shigella, and Salmonella strains were sensitive to MccY. Interestingly, Salmonellatyphimurium and Salmonella infantis were efficiently inhibited by MccY, while they were not affected by MccJ25, a lasso peptide that has antibacterial effects on many Salmonella strains. Furthermore, MccY-resistant strains of S. typhimurium were screened, and mutations were found in FhuA and SbmA, indicating the importance of these transporters for MccY absorption. This novel peptide can greatly broaden the antimicrobial spectrum of MccJ25 in Salmonella and is expected to be used in food preservation and animal feed additive areas.

Methionine adenosyltransferase (MAT), an essential enzyme that catalyzes the formation of S-adenosylmethionine (SAM), is encoded by two genes, MAT1A (liver-specific) and MAT2A (non-liver-specific). We showed a switch from MAT1A to MAT2A expression in human liver cancer, which facilitates cancer cell growth. The present work examined the role of methylation in MAT2A transcriptional regulation. We found that the human MAT2A promoter is hypomethylated in hepatocellular carcinoma, in which the gene is upregulated transcriptionally, but hypermethylated in normal liver, in which the gene is minimally expressed. Luciferase activities driven by in vitro methylated MAT2A promoter constructs were 75-95% lower than activities driven by unmethylated constructs. SAM treatment of Hep G2 cells reduced MAT2A endogenous expression by 75%, hypermethylated the MAT2A promoter, and reduced luciferase activities driven by MAT2A promoter constructs by 65-75% while not affecting MAT1A's promoter activity. Treatment of adult rat and human hepatocytes with trichostatin A, an inhibitor of histone deacetylase, upregulated MAT2A expression by more than fourfold. Collectively, these results suggest that MAT2A expression is regulated by promoter methylation and histone acetylation.

No abstract

No abstract

This paper comparatively investigated the removal efficiency and mechanisms of rice straw biochars prepared under three pyrolytic temperatures for two kinds of tetracycline and quinolone antibiotics (doxycycline and ciprofloxacin). The influencing factors of antibiotic adsorption (including biochar dosage, pH, background electrolytes, humic acid, initial antibiotics concentration, contact time, and temperature) were comprehensively studied. The results suggest that biochars produced at high-temperature [i.e., 700°C (BC700)], have higher adsorption capacity for the two antibiotics than low-temperature (i.e., 300–500°C) biochars (BC300 and BC500). Higher surface area gives rise to greater volume of micropores and mesopores, and higher graphitic surfaces of the BC700 contributed to its higher functionality. The maximum adsorption capacity was found to be in the following order: DOX > CIP. The π-π EDA interaction and hydrogen bonding might be the predominant adsorption mechanisms. Findings in this study highlight the important roles of high-temperature biochars in controlling the contamination of tetracycline and quinolone antibiotics in the environment.

No abstract