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It is well known that MVA 1 is required for growth of mammalian cells (1-4) as well as constituting the key metabolite in the biosynthesis of cholesterol and a variety of nonsterol isoprenoid derivatives (e.g. dolichyl-phosphate, farnesyl pyrophosphate, isopentenyladenine, and ubiquinone). The formation of MVA from HMG-CoA, which is catalyzed by HMG-CoA reductase, is the principal regulatory step in the pathway (1). Increasing evidence suggests that the MVA-derived product critical for cell growth is an isoprene of nonsterol type (1-4).A possible mechanism for MVA-regulated cell growth is the involvement of dolichyl-phosphate in N-linked glycosylation. De novo synthesized dolichyl-phosphate acts as a carrier of oligosaccharides in the assembly of glycoproteins in the lumen of the endoplasmic reticulum (ER) (5, 6). In a recent study we investigated the potential regulatory role of N-linked glycosylation in initiation of DNA synthesis in human fibroblasts stimulated by serum (7). Our results suggested that N-linked glycosylation of proteins of 90 -240 kDa in the prereplicative phase may be critical for induction of DNA replication. These high molecular mass glycoproteins may include growth factor receptors. This raises the possibility that MVA may regulate the expression of growth factor receptors through limiting the biosynthesis of dolichyl-phosphate. The existence of such a mechanism would constitute a substantial link between HMGCoA reductase and cell growth. The aim of the present study was to investigate this issue in detail. Our experiments provide evidence that MVA is critical for the translocation of insulinlike growth factor-1 receptor (IGF-1R) to the cell surface.

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Microbial communities of the Chinese marginal seas have rarely been reported. Here, bacterial and archaeal community structures and abundance in the surface sediment of four sea areas including the Bohai Sea (BS), North Yellow Sea (NYS), South Yellow Sea (SYS), and the north East China Sea (NECS) were surveyed by 16S ribosomal RNA (rRNA) gene pyrosequencing and quantitative PCR. The results showed that microbial communities of the four geographic areas were distinct from each other at the operational taxonomic unit (OTU) level, whereas the microbial communities of the BS, NYS, and SYS were more similar to each other than to the NECS at higher taxonomic levels. Across all samples, Bacteria were numerically dominant relative to Archaea, and among them, Gammaproteobacteria and Euryarchaeota were predominant in the BS, NYS, and SYS, while Deltaproteobacteria and Thaumarchaeota were prevalent in the NECS. The most abundant bacterial genera were putative sulfur oxidizer and sulfate reducer, suggesting that sulfur cycle processes might prevail in these areas, and the high abundance of dsrB (10(7)-10(8) copies g(-1)) in all sites verified the dominance of sulfate reducer in the north Chinese marginal seas. The differences in sediment sources among the sampling areas were potential explanations for the observed microbial community variations. Furthermore, temperature and dissolved oxygen of bottom water were significant environmental factors in determining both bacterial and archaeal communities, whereas chlorophyll a in sediment was significant only in structuring archaeal community. This study presented an outline of benthic microbial communities and provided insights into understanding the biogeochemical cycles in sediments of the north Chinese marginal seas.

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ABSTRACTThe Gram-negative bacteriumCronobacter sakazakiiis an emerging food-borne pathogen that causes severe invasive infections in neonates. Variation in the O-antigen lipopolysaccharide in the outer membrane provides the basis for Gram-negative bacteria serotyping. The O-antigen serotyping scheme forC. sakazakii, which includes seven serotypes (O1 to O7), has been recently established, and the O-antigen gene clusters and specific primers for threeC. sakazakiiserotypes (O1, O2, and O3) have been characterized. In this study, theC. sakazakiiO4, O5, O6, and O7 O-antigen gene clusters were sequenced, and gene functions were predicted on the basis of homology.C. sakazakiiO4 shared a similar O-antigen gene cluster withEscherichia coliO103. The general features and anomalies of all sevenC. sakazakiiO-antigen gene clusters were evaluated and the relationship between O-antigen structures and their gene clusters were investigated. Serotype-specific genes for O4 to O7 were identified, and a molecular serotyping method for allC. sakazakiiO serotypes, a multiplex PCR assay, was developed by screening against 136 strains ofC. sakazakiiand closely related species. The sensitivity of PCR-based serotyping method was determined to be 0.01 ng of genomic DNA and 103CFU of each strain/ml. This study completes the elucidation ofC. sakazakiiO-antigen genetics and provides a molecular method suitable for the identification ofC. sakazakiiO1 to O7 strains.

A novel dielectric barrier discharge reactor (DBDR) was utilized to trap/release arsenic coupled to hydride generation atomic fluorescence spectrometry (HG-AFS). On the DBD principle, the precise and accurate control of trap/release procedures was fulfilled at ambient temperature, and an analytical method was established for ultratrace arsenic in real samples. Moreover, the effects of voltage, oxygen, hydrogen, and water vapor on trapping and releasing arsenic by DBDR were investigated. For trapping, arsenic could be completely trapped in DBDR at 40 mL/min of O2 input mixed with 600 mL/min Ar carrier gas and 9.2 kV discharge potential; prior to release, the Ar carrier gas input should be changed from the upstream gas liquid separator (GLS) to the downstream GLS and kept for 180 s to eliminate possible water vapor interference; for arsenic release, O2 was replaced by 200 mL/min H2 and discharge potential was adjusted to 9.5 kV. Under optimized conditions, arsenic could be detected as low as 1.0 ng/L with an 8-fold enrichment factor; the linearity of calibration reached R(2) > 0.995 in the 0.05 μg/L-5 μg/L range. The mean spiked recoveries for tap, river, lake, and seawater samples were 98% to 103%; and the measured values of the CRMs including GSB-Z50004-200431, GBW08605, and GBW(E)080390 were in good agreement with the certified values. These findings proved the feasibility of DBDR as an arsenic preconcentration tool for atomic spectrometric instrumentation and arsenic recycling in industrial waste gas discharge.