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Downstream Regions (downstream + regions)
Selected AbstractsPhylogenetic reconstruction of Gram-positive organisms based on comparative sequence analysis of molecular chaperones from the ruminal microorganism Ruminococcus flavefaciens FD-1FEMS MICROBIOLOGY LETTERS, Issue 1 2003Dionysios A. Antonopoulos Abstract Primers designed on the basis of nucleotide sequences conserved in DnaK and GroEL from Gram-positive organisms were used to PCR amplify internal regions of the cognate genes from the anaerobic ruminal cellulolytic bacterium Ruminococcus flavefaciens FD-1. Genome walking was then utilized to elucidate the remainder of the sequences in addition to upstream and downstream regions. The full sequence of the gene encoding the GroES protein (groES) was found directly upstream from groEL. The deduced amino acid sequence of the groEL gene showed the highest homology with the amino acid sequence of the Clostridium thermocellum GroEL protein (72% amino acid identity). Similarly, translation of the groES nucleotide sequence showed highest homology to the C. thermocellum GroES protein (61% amino acid identity). Analysis of the upstream region of this chaperonin operon revealed a CIRCE regulatory element 45 bp upstream from the putative start of the groES ORF. The deduced amino acid sequence of the putative dnaK gene showed the highest homology with the amino acid sequence of the Clostridium acetobutylicum DnaK protein (68% amino acid identity). Phylogenetic analyses based on the translated sequences reiterate this relationship between R. flavefaciens and the Clostridia. However, when the nucleotide sequences of Gram-positive organisms are analyzed, a different topology occurs of the relationship between high- and low-G+C Gram-positive organisms to the 16S rRNA interpretation. [source] The long-term effect of artificial destratification on phytoplankton species composition in a subtropical reservoirFRESHWATER BIOLOGY, Issue 6 2005JASON P. ANTENUCCI Summary 1. The response of phytoplankton to the installation of an artificial destratification system in North Pine Dam, Brisbane (Australia) was investigated over an 18 year period (1984,2002); 11 years before and 7 years after installation. 2. An overall increase in phytoplankton abundance was revealed for some groups (in particular, diatoms, cyanobacteria and chlorophytes), but not for others (chlorophytes). Changes in the abundance of chlorophyte functional groups was attributed to eutrophication. 3. A strong spatial gradient in phytoplankton abundance and chlorophyll a was observed, with low abundance in the downstream regions affected by the destratification system which was likely because of light limitation induced by vertical mixing. The upstream region acted as a surrogate for the unaltered state of the reservoir, particularly as an indicator of eutrophication without direct influence from the destratification system. Despite the continuous trend in eutrophication of the reservoir, there has been a definite decrease in the rate of eutrophication (approximately 30%) since the installation of the destratification system at the downstream locations. 4. Correlations of the dominant cyanobacteria Cylindrospermopsis raciborskii with other genera changed after destratification, indicating that prior to destratification the dominance of Cylindrospermopsis was because of its ability to compete for phosphorus, whereas after destratification its dominance was because of its ability to compete for light. [source] Natural convection heat transfer along a vertical flat plate with a projection in the turbulent regionHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2001Katsuo Komori Abstract In the present study, the heat transfer coefficients occurring with a projection in the turbulent region of a vertical flat plate were measured experimentally for various projection heights in the range of 0 to 20 mm. The wall temperature and fluid flow fields were also visualized using a liquid crystal sheet and nylon 12 powder, respectively. The average and local Nusselt numbers reach 1.07 to 1.22 and 1.2 to 1.7 times those for pure turbulent natural convection, respectively. The maximum enhancement rates of heat transfer are attained at a position of 2.3 to 3.3 times the projection height from the upper projection surface toward the downstream, and these positions are in good agreement with those of the reattachment of the fluid flow and with centers of dark red regions in the liquid crystal. On the other hand, the heat transfer coefficients in the just upstream and downstream regions of the projection are small compared with those for no projection. By introducing the nondimensional parameter R, the present experimental results are rearranged quantitatively and effectively. © 2001 Scripta Technica, Heat Trans Asian Res, 30(3): 222,233, 2001 [source] Characterization of core promoter elements for ecdysone receptor isoforms of the silkworm, Bombyx moriINSECT MOLECULAR BIOLOGY, Issue 2 2007H. Shirai Abstract Two ecdysone receptor (EcR) isoforms, EcR-A and EcR-B1, are expressed in a tissue- and stage-specific manner, although the details of their transcription mechanisms are unknown. We determined the transcription start sites of EcR-A and EcR-B1 isoforms of Bombyx mori and found that both core promoter regions consist of initiator (Inr) and downstream promoter elements (DPE) but not TATA boxes. Promoter truncation analysis performed using the luciferase reporter assays and BmN cells showed that, in both isoforms, the regions ,296 to ,74 for BmEcR-B1, ,104 to ,61 for BmEcR-A and downstream regions of +1 are essential for basal transcriptional activity. Mutation experiments revealed that both DPE and its 5,-flanking CGCGCG sequence are crucial but DPE of BmEcR-B1 is not important for BmEcR-A transcription. These results indicate that the basal promoter activities differ between the two BmEcR isoforms. [source] Hydro-meteorological variability in the greater Ganges,Brahmaputra,Meghna basinsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2004MD. Rashed Chowdhury Abstract The flows of the Ganges, Brahmaputra and Meghna (GBM) are highly seasonal, and heavily influenced by monsoon rainfall. As a result, these rivers swell to their banks and often overflow during the monsoon months. This is most pronounced in the downstream regions, particularly in Bangladesh, which is the lowest riparian country. The objective of this paper is to study this hydro-meteorological variability in the greater GBM regions, including the headwater regions in India and their role in streamflows in Bangladesh, and explore the large-scale oceanic factors affecting this hydro-meteorological variability. Global precipitation data, Bangladesh rainfall and streamflow records have been analysed and related to large-scale climate patterns, including upstream rainfall, regional atmospheric circulation and patterns of sea-surface temperature. The findings have quantified how the streamflows of these rivers in Bangladesh are highly correlated with the rainfall in the upper catchments with typically a lag of about 1 month. Therefore, streamflows in Bangladesh could be reasonably estimated for 1 to 3 months in advance (especially for the Ganges and Brahmaputra rivers) by employing simple correlation, if rainfall data from countries further up are available on a real-time and continuous basis. In the absence of rainfall data, streamflow forecasts are still possible from unusually warm or cold sea-surface temperatures in the tropics. The study concludes that hydro-meteorological information flow between Bangladesh and other neighbouring countries is essential for developing a knowledge base for evaluating the potential implications of seasonal streamflow forecast in the GBM basins in Bangladesh. Copyright © 2004 Royal Meteorological Society [source] Comparison of genomic and cDNA sequences of guinea pig CYP2B18 and rat CYP2B2: Absence of a phenobarbital-responsive enhancer module in the upstream region of the CYP2B18 geneJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 3 2004Midori Yamamoto Abstract Potential mechanisms were investigated whereby CYP2B18, a cytochrome P450 gene exhibiting high constitutive expression but only low levels of phenobarbital-inducibility in the guinea pig liver, may be differentially regulated versus the highly inducible rat CYP2B2 gene. To comparatively assess potential regulatory sequences associated with CYP2B18, a guinea pig genomic library was screened enabling isolation of the CYP2B18 gene. The genomic screening process resulted in the identification of at least four closely-related CYP2B18 genes, designated here as CYP2B18A-D. Of these isolates, CYP2B18A exhibited sequence identical to that of the CYP2B18 cDNA. Further, the deduced amino acid sequence of the CYP2B18 cDNA was identical to that of N-terminal and internally-derived peptide sequences obtained in this investigation from CYP2B18 protein isolated from guinea pig liver. Genomic structural sequences were derived for CYP2B18A, together with the respective 5,-upstream and intronic regions of the gene. Comparison of the CYP2B18A and CYP2B2 gene sequences revealed the lack of repetitive LINE gene sequences in CYP2B18A, putative silencing elements that effect neighboring genes, although these sequences were present in both 5,-upstream and 3,-downstream regions of CYP2B2. We determined that the phenobarbital-responsive enhancer module was absent from the 5,-upstream region as well as the intronic regions of CYP2B18A gene. We hypothesize that the compromised phenobarbital inducibility of CYP2B18A stems from its lack of a functional phenobarbital responsive enhancer module. © 2004 Wiley Periodicals, Inc. J Biochem Mol Toxicol 18:124,130, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20016 [source] An intranuclear bacilliform virus associated with near extirpation of Austropotamobius pallipes Lereboullet from the Nant watershed in Ardéche, FranceJOURNAL OF FISH DISEASES, Issue 9 2002B F Edgerton White-clawed crayfish, Austropotamobius pallipes, were endemic to the Nant watershed, Ardéche, France, until they were extirpated by epizootic mortality at the beginning of the twentieth century. A. pallipes were successfully reintroduced to the Nant watershed in the middle of the twentieth century. However, epizootic mortality was observed in the Nant watershed in the summer of 2000 during which time A. pallipes was extirpated from downstream regions. Dead and moribund crayfish were again detected in several episodes in summer 2001 and by October the range of A. pallipes was reduced to the headwaters of just one of the three streams in the watershed. Water quality for the watershed in summer 2001 was appropriate for crayfish habitation. Bacteriology and mycology on A. pallipes collected during several of the mortality episodes in 2001 failed to reveal a cause. However, histopathology revealed a high occurrence of intranuclear eosinophilic inclusions in hepatopancreatocytes of A. pallipes. The nuclei were hypertrophic and contained bacilliform virions consisting of a cylindrical nucleocapsid surrounded by a trilaminar envelope. Virions in section were approximately 63 × 258 nm and nucleocapsids were approximately 52 × 225 nm. It is unclear whether the intranuclear bacilliform virus was the cause of the mortality episodes or was a contributor to a disease complex involving one or several other undetected pathogens. [source] | |||||||||||||