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  • Genetics Society of America (GSA)  (2)
  • Blackwell Publishing Ltd.  (1)
  • Canadian Society of Petroleum Geologists (CSPG)  (1)
  • Society for Sedimentary Geology (SEPM)
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  • 1
    Electronic Resource
    Electronic Resource
    Spatial correlation between weed species densities and soil properties (2002)
    Oxford UK : Blackwell Publishing Ltd.
    Weed research 42 (2002), S. 0 
    Details
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The spatial cross-correlation between weed species densities and six soil properties within fields was analysed using cross-semivariograms. The survey was carried out in three successive years in two fields. The most consistent relationship between weed species density (numbers m−2) and soil properties was negative cross-correlation between the density of Viola arvensis Murray and clay content. This correlation was found in both fields; however, the range of spatial dependence varied between fields. In one of the fields, the density of Lamium purpureum L. was positively cross-correlated with the phosphorus content in the soil in all years. The density of Veronica spp. and Poa annua L. was negatively cross-correlated with pH in all three years. Other spatial cross-correlations that were found in this study were inconsistent over time or field site. The densities of some of the weed species were spatially cross-correlated with more than one soil property. The results showed that the range of spatial dependence varied not only between fields, but also between weed species and soil properties, as well as between years. This study indicates that the weed pattern is field-specific and that the spatial variation in soil properties within a field is one of several factors affecting weed patchiness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3180.2002.00259.x
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Comparative Analysis of Wolbachia Genomes Reveals Streamlining and Divergence of Minimalist Two-Component Systems (2015)
    Genetics Society of America (GSA)
    Details
    Publication Date: 2015-05-12
    Description: Two-component regulatory systems are commonly used by bacteria to coordinate intracellular responses with environmental cues. These systems are composed of functional protein pairs consisting of a sensor histidine kinase and cognate response regulator. In contrast to the well-studied Caulobacter crescentus system, which carries dozens of these pairs, the streamlined bacterial endosymbiont Wolbachia pipientis encodes only two pairs: CckA/CtrA and PleC/PleD. Here, we used bioinformatic tools to compare characterized two-component system relays from C. crescentus , the related Anaplasmataceae species Anaplasma phagocytophilum and Ehrlichia chaffeensis , and 12 sequenced Wolbachia strains. We found the core protein pairs and a subset of interacting partners to be highly conserved within Wolbachia and these other Anaplasmataceae. Genes involved in two-component signaling were positioned differently within the various Wolbachia genomes, whereas the local context of each gene was conserved. Unlike Anaplasma and Ehrlichia , Wolbachia two-component genes were more consistently found clustered with metabolic genes. The domain architecture and key functional residues standard for two-component system proteins were well-conserved in Wolbachia , although residues that specify cognate pairing diverged substantially from other Anaplasmataceae. These findings indicate that Wolbachia two-component signaling pairs share considerable functional overlap with other α-proteobacterial systems, whereas their divergence suggests the potential for regulatory differences and cross-talk.
    Electronic ISSN: 2160-1836
    Topics: Biology
    Published by Genetics Society of America (GSA)
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  • 3
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    Predictive Genomic Analyses Inform the Basis for Vitamin Metabolism and Provisioning in Bacteria-Arthropod Endosymbioses (2017)
    Genetics Society of America (GSA)
    Details
    Publication Date: 2017-06-08
    Description: The requirement of vitamins for core metabolic processes creates a unique set of pressures for arthropods subsisting on nutrient-limited diets. While endosymbiotic bacteria carried by arthropods have been widely implicated in vitamin provisioning, the underlying molecular mechanisms are not well understood. To address this issue, standardized predictive assessment of vitamin metabolism was performed in 50 endosymbionts of insects and arachnids. The results predicted that arthropod endosymbionts overall have little capacity for complete de novo biosynthesis of conventional or active vitamin forms. Partial biosynthesis pathways were commonly predicted, suggesting a substantial role in vitamin provisioning. Neither taxonomic relationships between host and symbiont, nor the mode of host-symbiont interaction were clear predictors of endosymbiont vitamin pathway capacity. Endosymbiont genome size and the synthetic capacity of nonsymbiont taxonomic relatives were more reliable predictors. We developed a new software application that also predicted that last-step conversion of intermediates into active vitamin forms may contribute further to vitamin biosynthesis by endosymbionts. Most instances of predicted vitamin conversion were paralleled by predictions of vitamin use. This is consistent with achievement of provisioning in some cases through upregulation of pathways that were retained for endosymbiont benefit. The predicted absence of other enzyme classes further suggests a baseline of vitamin requirement by the majority of endosymbionts, as well as some instances of putative mutualism. Adaptation of this workflow to analysis of other organisms and metabolic pathways will provide new routes for considering the molecular basis for symbiosis on a comprehensive scale.
    Electronic ISSN: 2160-1836
    Topics: Biology
    Published by Genetics Society of America (GSA)
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  • 4
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    Comparison of McMurray Formation (Lower Cretaceous) and Grosmont Formation (Upper Devonian) bitumen reservoirs with some speculations, from a geological perspective, on the future of Canadian thermal recovery (2016)
    Canadian Society of Petroleum Geologists (CSPG)
    Details
    Publication Date: 2016-10-19
    Description: Using the data from over 8000 wells augmented by seismic and thermal response information, a comparison of McMurray Formation (Cretaceous) and Grosmont C member (Devonian) thermal recovery reservoirs of northeastern Alberta is provided along with a discussion of reservoir performance to date. Fluvial-estuarine McMurray Formation reservoirs perform best where bitumen-charged homogeneous lenticular sandstones at least 20 metres thick are found. These deposits are relatively rare as the formation is characterized by endemic heterogeneity mainly in the form of inclined heterolithic stratification (IHS). Most of the best McMurray steam-assisted gravity drainage (SAGD) reservoirs appear to be currently on-line and produce approximately 113 000 m 3 /day of bitumen from fourteen projects. Platform carbonate Grosmont C successions are blanket deposits 32–35 metres thick, with bitumen columns typically 15–24 metres thick, and are characterized by consistent reservoir properties facilitated by pervasive multi-scale fracturing. Although no reserves have yet to be assigned to Alberta’s bitumen-bearing carbonates by the province, recent pilot results derived from cyclic steam stimulation (CSS) operations suggest that Grosmont C reservoir performance could ultimately prove to be competitive with superior McMurray SAGD reservoirs. Under current technological and economic conditions, McMurray SAGD reservoirs appear incapable of providing the 15.9 billion m 3 of in-situ bitumen reserves (59% of Canada’s total oil reserves) ascribed to this formation by the province of Alberta as only circa 6 billion m 3 of oil-in place appears to reside within optimal reservoirs (i.e. those reservoirs at least 20 metres thick with average porosity and oil saturation values of 33% and 80%, respectively). Barring future technological breakthroughs and, or, economic improvements, future commercial development of both the Grosmont C and other carbonate reservoirs might be needed to make up for some of the potential reserve shortfall associated with McMurray Formation SAGD reservoirs.
    Print ISSN: 0007-4802
    Electronic ISSN: 0007-4802
    Topics: Geosciences
    Published by Canadian Society of Petroleum Geologists (CSPG)
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