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Irregular Distribution (irregular + distribution)
Selected AbstractsQuantification of microbial communities in near-surface and deeply buried marine sediments on the Peru continental margin using real-time PCRENVIRONMENTAL MICROBIOLOGY, Issue 7 2006Axel Schippers Summary Deeply buried marine sediments harbour a large fraction of all prokaryotes on Earth but it is still unknown which phylogenetic and physiological microbial groups dominate the deep biosphere. In this study real-time PCR allowed a comparative quantitative microbial community analysis in near-surface and deeply buried marine sediments from the Peru continental margin. The 16S rRNA gene copy numbers of prokaryotes and Bacteria were almost identical with a maximum of 108,1010 copies cm,3 in the near-surface sediments. Archaea exhibited one to three orders of magnitude lower 16S rRNA gene copy numbers. The 18S rRNA gene of Eukarya was always at least three orders of magnitude less abundant than the 16S rRNA gene of prokaryotes. The 16S rRNA gene of the Fe(III)- and Mn(IV)-reducing bacterial family Geobacteraceae and the dissimilatory (bi)sulfite reductase gene (dsrA) of sulfate-reducing prokaryotes were abundant with 106,108 copies cm,3 in near-surface sediments but showed lower numbers and an irregular distribution in the deep sediments. The copy numbers of all genes decreased with sediment depth exponentially. The depth gradients were steeper for the gene copy numbers than for numbers of total prokaryotes (acridine orange direct counts), which reflects the ongoing degradation of the high-molecular-weight DNA with sediment age and depth. The occurrence of eukaryotic DNA also suggests DNA preservation in the deeply buried sediments. [source] Randomness test of signal generated by microwave chaotic Colpitts oscillatorMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2007Zhiguo Shi Abstract Randomness test was conducted on signal sampled from the output of a microwave chaotic Colpitts oscillator operating with fundamental frequency of 960 MHz. Experimental data analysis shows the signal has an irregular distribution and a low degree of autocorrelation. Binary sequences converted from the signal can pass the four but one randomness tests in FIPS standard. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1981,1984, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22565 [source] Several distinct localization patterns for penicillin-binding proteins in Bacillus subtilisMOLECULAR MICROBIOLOGY, Issue 3 2004Dirk-Jan Scheffers Summary Bacterial cell shape is determined by a rigid external cell wall. In most non-coccoid bacteria, this shape is also determined by an internal cytoskeleton formed by the actin homologues MreB and/or Mbl. To gain further insights into the topological control of cell wall synthesis in bacteria, we have constructed green fluorescent protein (GFP) fusions to all 11 penicillin-binding proteins (PBPs) expressed during vegetative growth of Bacillus subtilis. The localization of these fusions was studied in a wild-type background as well as in strains deficient in FtsZ, MreB or Mbl. PBP3 and PBP4a localized specifically to the lateral wall, in distinct foci, whereas PBP1 and PBP2b localized specifically to the septum. All other PBPs localized to both the septum and the lateral cell wall, sometimes with irregular distribution along the lateral wall or a preference for the septum. This suggests that cell wall synthesis is not dispersed but occurs at specific places along the lateral cell wall. The results implicate PBP3, PBP5 and PBP4a, and possibly PBP4, in lateral wall growth. Localization of PBPs to the septum was found to be dependent on FtsZ, but the GFP,PBP fluorescence patterns were not detectably altered in the absence of MreB or Mbl. [source] Bean dwarf mosaic virus: a model system for the study of viral movementMOLECULAR PLANT PATHOLOGY, Issue 4 2010AVNER LEVY SUMMARY Taxonomy:Bean dwarf mosaic virus -[Colombia:1987] (BDMV-[CO:87]) is a single-stranded plant DNA virus, a member of the genus Begomovirus of the family Geminiviridae. Physical properties: BDMV virions are twinned incomplete isosahedra measuring 18 × 30 nm. The viral particle is composed of 110 subunits of coat protein, organized as 22 pentameric capsomers. Each subunit has a molecular mass of ,29 kDa. BDMV possesses two DNA components (designated DNA-A and DNA-B), each ,2.6 kb in size. Host range: The natural and most important host of BDMV is the common bean (Phaseolus vulgaris). Nicotiana benthamiana is often used as an experimental host. Common bean germplasm can be divided into two major gene pools: Andean materials, which are mostly susceptible to BDMV, and Middle American materials, which are mostly resistant to BDMV. Disease symptoms: The symptom intensity in common bean plants depends on the stage of infection. Early infection of susceptible bean seedlings will result in severe stunting and dwarfing, leaf distortion and mottling or mosaic, as well as chlorotic or yellow spots or blotches. BDMV-infected plants usually abort their flowers or produce severely distorted pods. Late infection of susceptible plants or early infection of moderately resistant genotypes may show a mild mosaic, mottle and crumpling or an irregular distribution of variegated patches. Biological properties: As a member of the Begomovirus group, BDMV is transmitted from plant to plant by the whitefly Bemisia tabaci. BDMV is a nonphloem-limited virus and can replicate and move in the epidermal, cortical and phloem cells. As a nonphloem-limited virus, it is sap-transmissible. [source] Reassessment of histopathology and dermoscopy findings in 145 Japanese cases of melanocytic nevus of the sole: Toward a pathological diagnosis of early-stage malignant melanoma in situPATHOLOGY INTERNATIONAL, Issue 2 2010Ling Jin Recently, dermoscopic visualization has been improved, allowing for the identification of malignant melanoma (MM) of the sole in situ. When the parallel ridge pattern is evident on dermoscopy, the proliferation of solitarily arranged melanocytes in the crista profunda intermedia should be examined histologically, since this may be a clue to the early diagnosis of MM in situ. We reviewed 145 Japanese cases of melanocytic nevus on the sole, and investigated several useful histological features for the diagnosis of MM in situ using a recent proposal as well as several standard histological criteria of MM in situ. Five cases were considered to be an early-stage MM in situ out of 145 cases previously diagnosed as melanocytic nevi of the sole. These cases showed several specific features, including solitarily arranged melanocytes or melanocyte nests comprising fewer than four cells. Our findings indicate that early-stage MM of the sole in situ can be diagnosed by using new dermoscopy-related histological findings. They are (i) irregular distribution of solitary melanocytes at the crista profunda intermedia with or without small nests (up to three melanocytes) on the slope of rete ridges; and (ii) larger melanocytes with a halo around the nucleus. [source] Conservation importance of semi-arid streams in north-eastern Brazil: implications of hydrological disturbance and species diversityAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2006L. Maltchik Abstract 1.Intermittent streams in the semi-arid region of Brazil are distinctive landscape features existing as dry watercourses for most of the time. It has been recognized that the extremes of flooding and total absence of water flow are the principal hydrological characteristics of rivers and streams in this region. This is a consequence of complex climatic patterns that lead to an irregular distribution of the small amount of rainfall and low thermal amplitude. The latter is the main climatic difference between the Brazilian semi-arid region and other semi-arid lands. 2.The expansion of water resource development has been a threat to the natural flow regime and the ecological integrity of rivers and streams in semi-arid Brazil. Efforts to manage and conserve the natural flow regime of these systems are hampered by limited scientific information on the ecological processes driving their flora and fauna and the responses of biota to the high natural variability in flow regime. 3.The most important issues in the conservation of streams in semi-arid Brazil are the need for their recognition as important sites of biodiversity and that this diversity is closely associated with natural patterns of flow and the hydrological disturbances. Without the understanding of how the extremes of flooding and drought affect the aquatic fauna, the conservation strategies for Brazilian semi-arid streams and their fauna will not be effective. 4.Therefore, conservation efforts in semi-arid Brazil must ensure that the processes sustaining biodiversity are maintained at multiple-scale and landscape levels and that the natural integrity of the riparian zone is maintained Copyright © 2006 John Wiley & Sons, Ltd. [source] Consideration of the Effect of Irregular Catalytic Active Component Distributions in Mesopores , Extension of a Model for Wall Catalyzed Reactions in Microchannel ReactorsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2003B. Platzer Abstract Data available from the literature and experimental results have shown that the distribution of the catalytic active components can be irregular already for fresh catalysts. The determination of the local concentrations of the catalytic active components using wavelength dispersive X-ray spectroscopy confirms this for microstructured wafers used in microchannel reactors. Considering this nonuniform distribution, the used model gives the relation between the local concentration profiles of the reactants inside the pores and the product yield in the entire pore. These results were used in an equation for the diffusion flux at the pore mouth, which is useful for a microchannel model developed in a recent paper [1]. The theoretical considerations deal with cylindrical pores with known reactant concentrations at the pore mouth and known distribution of the catalytic active component within the pore. Beside numerical results, some analytical solutions with low mathematical expense, applicable to special cases, are discussed. The nonconsideration of the irregular distribution of the catalytic active component can be the reason for difficulties during the extrapolation of experimental results to slightly different conditions and can have a great influence on the reaction results. The regarded examples are typical of wall-catalyzed reactions in microchannel reactors with mesopores. [source] | ||||||||||