Y chromosome detection by Real Time PCR and pyrophosphorolysis-activated polymerisation using free fetal DNA isolated from maternal plasma

Objectives To validate the use of Real Time PCR, a widely used technique that can detect very low levels of Y chromosomal sequence, and to assess the use of a highly sensitive PCR technique, pyrophosphorolysis-activated polymerisation (PAP), for fetal sex determination using free fetal DNA (ffDNA). Methods The fetal sex was determined by Real Time PCR in 58 pregnancies using ffDNA isolated from maternal plasma. In parallel with the Real Time PCR experiments, the presence of Y chromosome sequence was also determined using PAP on 54 isolated ffDNA samples. Results Both techniques detected Y chromosome sequence at very low levels with 98% specificity and 100% sensitivity (Real Time n = 44, PAP n = 54). Furthermore, the PAP technique was shown to be more robust than the Real Time PCR as none of the samples tested failed to meet the acceptance criteria. Combining the two techniques for male fetal sex detection from maternal blood plasma increases the sensitivity and specificity to 100% in this series. Conclusions This study shows that both Real Time PCR and PAP can be used for Y chromosome detection on ffDNA. Furthermore, by using PAP in combination with Real Time PCR more reliable early prenatal sexing can be performed using ffDNA. Copyright © 2007 John Wiley & Sons, Ltd.     

Toxikologische Bewertung von Rüstungsaltlasten

A method was developed for the risk assessment of a military waste site. The method consists of two steps: 1. evaluation of the exposure through different pathways and 2. derivation of substance-specific tolerable intake levels. In this first part of the paper the quantitative exposure analysis will be discussed. Exposure depends on the conditions at the contaminated site (e.g. soil characteristics), the type of utilisation (residential area, industrial area etc.) and the substance properties. In a specific utilisation scenario, e.g. as residential area, different exposure pathways are contributing to the total contaminant uptake. Because of the properties of nitroaromatic compounds like 2,4,6-trinitrotoluene (good resorption through skin and accumulation in plants) exposure via dermal soil contact and via consumption of plants gains special importance. With these two exposure pathways as examples we explain the quantification of the exposure through different pathways by so-called exposure factors. By comparing the total exposure with tolerable intake levels for the compounds, waste site specific soil pollutant levels can be established (see second part of the paper in UWSF 6/94).     

The Sustainable Use of Sensitive Countryside Sites for Sport and Active Recreation

Sport and active recreation, as an important area of leisure activity that can take place in the countryside, has recently been the subject of much discussion both in central government reports and statutory agencies' studies. This paper examines principles for their planning and management, particularly in sensitive areas such as National Parks, Areas of Outstanding Natural Beauty and Sites of Special Scientific Interest. It takes the view that effective recreation management should be promoted, suggesting that the designation of countryside areas should not imply that they are unchanging, or that environmental policies should be applied uniformly. The Government's UK Sustainable Development Strategy 1994 emphasizes the importance of assessing capacity and of management and monitoring in providing for leisure. Yet knowledge of recreation impacts is incomplete. A number of principles for the management of countryside recreation are given, and examples given of such principles in use. These stress the need for effective participation by the various interests involved at sites and the importance of voluntary approaches to the resolution of conflicts.     

Integrating economic costs into the analysis of flexible conservation management strategies.

Flexible conservation management, where measures (e.g., mowing of meadows, removing invasive species) are selected in each decision period depending on the current state of the ecological system, is generally perceived as superior to fixed management, where the same measure is applied in each decision period independent of the current state of the system. In past comparisons of fixed and flexible conservation strategies the additional costs that arise only in flexible strategies have usually been ignored. In this paper, we present a framework to integrate costs of flexible management into the evaluation of flexible conservation strategies. Using the example of an endangered butterfly species we demonstrate that the costs of flexible management may reverse the rank order of flexible and fixed conservation strategies, such that fixed strategies may lead to better ecological results than flexible ones for the same financial budget.     

Regional assessment of plant growth problems for colliery spoil reclamation

Possibilities for greater variation in landscaping during the reclamation of derelict colliery spoil heaps and the potential of a regional approach to the survey of revegetation problems are introduced. A survey method for assessing plant growth problems is described which incorporates rapid measurement of physical and chemical constraints to plant growth and which uses bioassay trials as an index of plant growth potential. The use of the survey method on 34 closed and disused sites in the Barnsley and South Yorkshire areas of the National Coal Board is outlined and suggestions for the incorporation of such data in recommendations for the reclamation of individual sites are made.     

A mathematical model for the distribution and abundance of benthic algae in a Norwegian fjord

A mathematical model has been developed to study the distribution and abundance of benthic algae species in a Norwegian fjord. The main forcing functions are the physical factors which have well defined gradients in this area, but biotic interactions are also accounted for in the model.The distribution of algae along vertical transects in the intermediate fjord area has been simulated, and the observed distribution is reproduced fairly well. This indicates that the major factors determining the equilibrium elevation between intertidal and subtidal vegetations in this area are adequately represented in the model.Based on observations in a fjord branch with a high level of freshwater influx and polluted by heavy metals, assumptions are made of the combined influence of these contaminants on growth characteristics of the species considered. The resulting effects on community development and community patterns are simulated. For a certain level of contamination, the decrease in abundance, community development rate and species separation have been determined. It is also shown that the fluctuations in biomass during a year are more pronounced than under unaffected conditions.The relative importance of external growth regulating factors and self-shading is demonstrated for different degrees of community development, and we have indicated that this may be an important factor in the assessment of transient and long-term responses to “natural” and man-made influences on the shore-line vegetation.One of the main problems during model development was the formulation of the interaction function for factors influencing growth parameters. Several alternatives were examined.The differences between the most frequently used forms were small with respect to abundance and not very large with respect to possible changes in distribution. It was noted that even by including only the most limiting factor at each instant, (Liebig's form) a high percentage of the potentially limiting factors did actually limit growth during periods of the year.The model is intended as a working tool for the studies of changes in the shore-line vegetation caused by man-made interferences like heavy metal and oil pollution, and we believe that the results presented demonstrate that it can successfully be used for this purpose.