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The results presented here provide the first single-cell genetic assay for Tay-Sachs disease based on real-time PCR. Individual lymphoblasts were lysed with an optimized lysis buffer and assayed using one pair of primers that amplifies both the wild type and 1278 + TATC Tay-Sachs alleles. The resulting amplicons were detected in real time with two molecular beacons each with a different colored fluorochrome. The kinetics of amplicon accumulation generate objective criteria by which to evaluate the validity of each reaction. The assay had an overall utility of 95%, based on the detection of at least one signal in 235 of the 248 attempted tests and an efficiency of 97%, as 7 of the 235 samples were excluded from further analysis for objective quantitative reasons. The accuracy of the assay was 99.1%, because 228 of 230 samples gave signals consistent with the genotype of the cells. Only two of the 135 heterozygous samples were allele drop-outs, a rate far lower than previously reported for single-cell Tay-Sachs assays using conventional methods of PCR. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
794.
Andrea L. Jaeger Miehls Doran M. Mason Kenneth A. Frank Ann E. Krause Scott D. Peacor William W. Taylor 《Ecological modelling》2009,220(22):3182
As invasion rates of exotic species increase, an ecosystem level understanding of their impacts is imperative for predicting future spread and consequences. We have previously shown that network analyses are powerful tools for understanding the effects of exotic species perturbation on ecosystems. We now use the network analysis approach to compare how the same perturbation affects another ecosystem of similar trophic status. We compared food web characteristics of the Bay of Quinte, Lake Ontario (Canada), to previous research on Oneida Lake, New York (USA) before and after zebra mussel (Dreissena polymorpha) invasion. We used ecological network analysis (ENA) to rigorously quantify ecosystem function through an analysis of direct and indirect food web transfers. We used a social network analysis method, cohesion analysis (CA), to assess ecosystem structure by organizing food web members into subgroups of strongly interacting predators and prey. Together, ENA and CA allowed us to understand how food web structure and function respond simultaneously to perturbation. In general, zebra mussel effects on the Bay of Quinte, when compared to Oneida Lake, were similar in direction, but greater in magnitude. Both systems underwent functional changes involving focused flow through a small number of taxa and increased use of benthic sources of production; additionally, both systems structurally changed with subgroup membership changing considerably (33% in Oneida Lake) or being disrupted entirely (in the Bay of Quinte). However, the response of total ecosystem activity (as measured by carbon flow) differed between both systems, with increasing activity in the Bay of Quinte, and decreasing activity in Oneida Lake. Thus, these analyses revealed parallel effects of zebra mussel invasion in ecosystems of similar trophic status, yet they also suggested that important differences may exist. As exotic species continue to disrupt the structure and function of our native ecosystems, food web network analyses will be useful for understanding their far-reaching effects. 相似文献
795.
Kenneth Strzepek David Yates Gary Yohe Richard Tol Nicholas Mader 《Integrated Assessment》2001,2(3):139-157
A space of “not-implausible” scenarios for Egypt's future under climate change is defined along two dimensions. One depicts
representative climate change and climate variability scenarios that span the realm of possibility. Some would not be very
threatening. Others portend dramatic reductions in average flows into Lake Nassar and associated increases in the likelihood
of year to year shortfalls below critical coping thresholds; these would be extremely troublesome, especially if they were
cast in the context of increased political instability across the entire Nile Basin. Still others depict futures along which
relatively routine and relatively inexpensive adaptation might be anticipated. The ability to adapt to change and to cope
with more severe extremes would, however, be linked inexorably to the second set of social–political–economic scenarios. The
second dimension, defined as “anthropogenic” social/economic/political scenarios describe the holistic environment within
which the determinants of adaptive capacity for water management, agriculture, and coastal zone management must be assessed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
796.
Debra L. Bisson Danny R. Jackson Kenneth R. Williams Walter E. Grube 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1348-1354
WILT, ANS 16.1 and TCLP leach tests were performed on solidified/stabilized (s/s) wastes treated by Soliditech, Inc. of Houston, Texas as part of a U.S. EPA SITE demonstration project conducted in December 1988 at the Imperial Oil Company/ Champion Chemical Company Superfund site in Morganville, New Jersey. All three leaching tests performed on the s/s wastes indicated that the primary contaminants of concern (lead and PCBs) were not leachable. The ANS 16.1 static leach test for the s/s wastes provided diffusion coefficients (De) for Al, Ca, and Na that were comparable to those obtained from the WILT test. However, plots of the ANS 16.1 data indicated that wetting of the samples confounded the static leaching process. The large column WILT De was used to estimate that less than 0.8 μg/cm2 lead would leach from a one-cubic yard block of s/s waste in contact with groundwater over a 60-month leaching period. This corresponds to concentrations less than 10 μg/L lead in the water contacting the block of s/s waste. 相似文献
797.