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Prevalence of the Chloroflexi-Related SAR202 Bacterioplankton Cluster throughout the Mesopelagic Zone and Deep Ocean. R. M. Morris, 2004.Since their initial discovery in samples from the north Atlantic Ocean, 16S rRNA genes related to the environmental gene clone cluster known as SAR202 have been recovered from pelagic freshwater, marine sediment, soil, and deep subsurface terrestrial environments . Together, these clones form a major, monophyletic subgroup of the phylum Chloroflexi . While members of this diverse group are consistently identified in the marine environment, there are currently no cultured representatives, and very little is known about their distribution or abundance in the world's oceans . In this study, published and newly identified SAR202-related 16S rRNA gene sequences were used to further resolve the phylogeny of this cluster and to design taxon-specific oligonucleotide probes for fluorescence in situ hybridization . Direct cell counts from the Bermuda Atlantic time series study site in the north Atlantic Ocean, the Hawaii ocean time series site in the central Pacific Ocean, and along the Newport hydroline in eastern Pacific coastal waters showed that SAR202 cluster cells were most abundant below the deep chlorophyll maximum and that they persisted to 3,600 m in the Atlantic Ocean and to 4,000 m in the Pacific Ocean, the deepest samples used in this study . On average, members of the SAR202 group accounted for 10.2% (±5.7%) of all DNA-containing bacterioplankton between 500 and 4,000 m . Context-Dependent Functions of the PII and GlnK Signal Transduction Proteins in Escherichia coli. Mariette R. Atkinson, 2002.Two closely related signal transduction proteins, PII and GlnK, have distinct physiological roles in the regulation of nitrogen assimilation . Here, we examined the physiological roles of PII and GlnK when these proteins were expressed from various regulated or constitutive promoters . The results indicate that the distinct functions of PII and GlnK were correlated with the timing of expression and levels of accumulation of the two proteins . GlnK was functionally converted into PII when its expression was rendered constitutive and at the appropriate level, while PII was functionally converted into GlnK by engineering its expression from the nitrogen-regulated glnK promoter . Also, the physiological roles of both proteins were altered by engineering their expression from the nitrogen-regulated glnA promoter . We hypothesize that the use of two functionally identical PII-like proteins, which have distinct patterns of expression, may allow fine control of Ntr genes over a wide range of environmental conditions . In addition, we describe results suggesting that an additional, unknown mechanism may control the cellular level of GlnK . Definition of the Escherichia coli MC4100 Genome by Use of a DNA Array. Joseph E. Peters, 2003.We have used an Escherichia coli K-12 whole-genome array based on the DNA sequence of strain MG1655 as a tool to identify deletions in another E . coli K-12 strain, MC4100, by probing the array with labeled chromosomal DNA . Despite the continued widespread use of MC4100 as an experimental system, the specific genetic relationship of this strain to the sequenced K-12 derivative MG1655 has not been resolved . MC4100 was found to contain four deletions, ranging from 1 to 97 kb in size . The exact nature of three of the deletions was previously unresolved, and the fourth deletion was altogether unknown . Overexpression of the Gene Encoding GTP:Mannose-1-Phosphate Guanyltransferase, mpg1, Increases Cellular GDP-Mannose Levels and Protein Mannosylation in Trichoderma reesei. Anna Zakrzewska, 2003.To elucidate the regulation and limiting factors in the glycosylation of secreted proteins, the mpg1 and dpm1 genes from Trichoderma reesei (Hypocrea jecorina) encoding GTP:  -D-mannose-1-phosphate guanyltransferase and dolichyl phosphate mannose synthase (DPMS), respectively, were overexpressed in T . reesei . No significant increases were observed in DPMS activity or protein secretion in dpm1-overexpressing transformants, whereas overexpression of mpg1 led to a twofold increase in GDP-mannose (GDPMan) levels . GDPMan was effectively utilized by mannnosyltransferases and resulted in hypermannosylation of secreted proteins in both N and O glycosylation . Overexpression of the mpg1 gene also increased the transcription of the dpm1 gene and DPMS activity . Our data indicate that the level of cellular GDPMan can play a major regulatory role in protein glycosylation in T . reesei .
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