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41.
Mark?A?HerbertEmail author Catriona?JE?Beveridge David?McCormick Emmelien?Aten Nicola?Jones Lori?AS?Snyder Nigel?J?Saunders 《BMC microbiology》2005,5(1):31
Background
Streptococcus agalactiae (Group B Streptococcus; GBS) is a major contributor to obstetric and neonatal bacterial sepsis. Serotype III strains cause the majority of late-onset sepsis and meningitis in babies, and thus appear to have an enhanced invasive capacity compared with the other serotypes that cause disease predominantly in immunocompromised pregnant women. We compared the serotype III and V whole genome sequences, strains NEM316 and 2603VR respectively, in an attempt to identify genetic attributes of strain NEM316 that might explain the propensity of strain NEM316 to cause late-onset disease in babies. Fourteen putative pathogenicity islands were described in the strain NEM316 whole genome sequence. Using PCR- and targeted microarray- strategies, the presence of these islands were assessed in a diverse strain collection including 18 colonizing isolates from healthy pregnant women, and 13 and 8 invasive isolates from infants with early- and late-onset sepsis, respectively. 相似文献42.
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Ryder E Blows F Ashburner M Bautista-Llacer R Coulson D Drummond J Webster J Gubb D Gunton N Johnson G O'Kane CJ Huen D Sharma P Asztalos Z Baisch H Schulze J Kube M Kittlaus K Reuter G Maroy P Szidonya J Rasmuson-Lestander A Ekström K Dickson B Hugentobler C Stocker H Hafen E Lepesant JA Pflugfelder G Heisenberg M Mechler B Serras F Corominas M Schneuwly S Preat T Roote J Russell S 《Genetics》2004,167(2):797-813
We describe a collection of P-element insertions that have considerable utility for generating custom chromosomal aberrations in Drosophila melanogaster. We have mobilized a pair of engineered P elements, p[RS3] and p[RS5], to collect 3243 lines unambiguously mapped to the Drosophila genome sequence. The collection contains, on average, an element every 35 kb. We demonstrate the utility of the collection for generating custom chromosomal deletions that have their end points mapped, with base-pair resolution, to the genome sequence. The collection was generated in an isogenic strain, thus affording a uniform background for screens where sensitivity to genetic background is high. The entire collection, along with a computational and genetic toolbox for designing and generating custom deletions, is publicly available. Using the collection it is theoretically possible to generate >12,000 deletions between 1 bp and 1 Mb in size by simple eye color selection. In addition, a further 37,000 deletions, selectable by molecular screening, may be generated. We are now using the collection to generate a second-generation deficiency kit that is precisely mapped to the genome sequence. 相似文献
44.
CMA Iwegbue OV Beecroft JE Ogala FE Egobueze GO Tesi GE Nwajei 《African Journal of Aquatic Science》2018,43(3):241-253
The concentrations of nine metals were measured by atomic absorption spectrophotometry in surface sediments of three coastal creeks, namely, the Ifie, Egbokodo and Ubeji creeks, in the Niger Delta of Nigeria, from August 2012 to January 2013. The aim of the study was to provide information on the spatial and seasonal distribution patterns, degree of contamination, and ecological risks of metals in these sediments. The mean concentrations of the nine metals in these creek sediments ranged from 0.30 to 3.20?mg kg?1 Cd; 10.7 to 24.7?mg kg?1 Pb, 125 to 466?mg kg?1 Cr; 3.1.10 to 14.9?mg kg?1 Cu; 4.7 to 14.3?mg kg?1 Co; 61.1 to 115?mg kg?1 Ni; 106 to 183?mg kg?1 Mn; 52.0 to 170?mg kg?1 Zn and 5 469 to 20 639?mg kg?1 Fe. In general, the metal concentrations were higher in the dry season than the wet season, except for Cr. The concentrations of Cd, Cr, Ni and Zn were above their regulatory control limits in sediment as specified by the Nigerian Regulatory Authority and Cd was identified as the main ecological risk factor. The enrichment factors for the studied metals followed the order: Cd > Cr > Ni > Zn > Pb > Co > Mn > Cu. The average multiple pollution index values indicated that these sediments were severely polluted with significant inputs from Cd, Ni and Cr. 相似文献
45.
By means of indirect double immunofluorescent staining,the coordination of PI antigen and perichromonucleolin(PCN),the constituent of nuclear periphery and nucleolus respectively,in the assembly and disassembly of chromosome pellicle during mitosis was studied.It was found that in 3T3 cells,during mitosis PI antigen began to coat the condensing chromosome surface earlier than PCN did.However,both of them completed their coating on chromosome at approximately the same stage of mitosis,prometaphase metaphase,The dissociation of mitosis,Prometaphase metaphase.The dissociation of PI antigen from chromosome pellicle to participate the formation of nuclear periphery took place also ahead of that of PCN,At early telophase PI antigen had been extensively involved in the formation of nuclear periphery,while PCN remained in association with the surface of decondensing chromosomes.At late telophase,when PI antigen was localized in an fairly well formed nuclear periphery,PCN was in a stage of forming prenucleolar bodies. 相似文献
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Zivanai Tsvuura Megan E. Griffiths Richard M. Gunton Peter J. Franks Michael J. Lawes 《Oecologia》2010,164(4):861-870
The regeneration niche is commonly partitioned along a gradient from shade-tolerant to shade-intolerant species to explain
plant community assembly in forests. We examined the shade tolerance of tree seedlings in a subtropical coastal forest to
determine whether the ecological filtering effect of a dominant, synchronously monocarpic herb (Isoglossa woodii) selects for species at either end of the light response continuum during the herb’s vegetative and reproductive phases.
Photosynthetic characteristics of seedlings of 20 common tree species and the herb were measured. Seedlings were grown in
the greenhouse at 12–14% irradiance, and their light compensation points measured using an open-flow gas exchange system.
The light compensation points for the tree species were low, falling within a narrow range from 2.1 ± 0.8 μmol m−2 s−1 in Celtis africana to 6.4 ± 0.7 μmol m−2 s−1 in Allophylus natalensis, indicating general shade tolerance, consistent with a high and narrow range of apparent quantum yield among species (0.078 ± 0.002 mol
CO2 mol−1 photon). Rates of dark respiration were significantly lower in a generalist pioneer species (Acacia karroo) than in a forest pioneer (C. africana), or in late successional phase forest species. We argue that the general shade tolerance, and phenotypic clustering of shade
tolerance, in many tree species from several families in this system, is a result of ecological filtering by the prevailing
low light levels beneath the I. woodii understorey, which excludes most light-demanding species from the seedling community. 相似文献
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