Quantifying the efficiency of soil sampling designs: A multivariate approach

The objective of this paper is to quantify and compare the loss functions of the standard two-stage design and its composite sample alternative in the context of multivariate soil sampling. The loss function is defined (conceptually) as the ratio of cost over information and measures design inefficiency. The efficiency of the design is the reciprocal of the loss function. The focus of this paper is twofold: (a) we define a measure of multivariate information using the Kullback–Leibler distance, and (b) we derive the variance-covariance structure for two soil sampling designs: a standard two-stage design and its composite sample counterpart. Randomness in the mass of soil samples is taken into account in both designs. A pilot study in Slovenia is used to demonstrate the calculations of the loss function and to compare the efficiency of the two designs. The results show that the composite sample design is more efficient than the two-stage design. The efficiency ratio is 1.3 for pH, 2.0 for C, 2.1 for N, and 2.5 for CEC. The multivariate efficiency ratio is 2.3. These ratios primarily reflect cost ratios; influence of the information is small.     

The value of small size: loss of forest patches and ecological thresholds in southern Madagascar.

Many services generated by forest ecosystems provide essential support for human well-being. However, the vulnerability of these services to environmental change such as forest fragmentation are still poorly understood. We present spatial modeling of the generation of ecosystem services in a human-dominated landscape where forest habitat patches, protected by local taboos, are located in a matrix of cultivated land in southern Madagascar. Two ecosystem services dependent on the forest habitats were addressed: (1) crop pollination services by wild and semidomesticated bees (Apoidea), essential for local crop production of, for example, beans, and (2) seed dispersal services based on the presence of ring-tailed lemurs (Lemur catta). We studied the vulnerability of these ecosystem services to a plausible scenario of successive destruction of the smallest habitat patches. Our results indicate that, in spite of the fragmented nature of the landscape, the fraction of the landscape presently covered by both crop pollination and seed dispersal services is surprisingly high. It seems that the taboo system, though indirectly and unintentionally, contributes to upholding the generation of these services by protecting the forest patches. Both services are, however, predicted to be very vulnerable to the successive removal of small patches. For crop pollination, the rate of decrease in cover was significant even when only the smallest habitat patches were removed. The capacity for seed dispersal across the landscape displayed several thresholds with habitat patch removal. Our results suggest that, in order to maintain capacity for seed dispersal across the landscape and crop pollination cover in southern Androy, the geographical location of the remaining forest patches is more crucial than their size. We argue that in heavily fragmented production landscapes, small forest patches should increasingly be viewed as essential for maintaining ecosystem services, such as agricultural production, and also should be considered in the ongoing process of tripling the area of protected habitats in Madagascar.     

Mosaicism of autosomes and sex chromosomes in morphologically normal,monospermic preimplantation human embryos

We have previously detected chromosome abnormalities in human embryos whilst identifying the sex for preimplantation diagnosis of X-linked disease. In this study we assess the incidence of these abnormalities, both for sex chromosomes and autosomes 1 and 17, using dual fluorescent in situ hybridization (FISH). Sixty-nine normally fertilized embryos of good morphology at the 6–10 cell stage (day 3 post-insemination) were examined. The embryos were spread whole using HCl and Tween 20 to dissolve the cytoplasm. Thirty-four embryos were analysed for the sex chromosomes and 35 for autosomes 1 and 17. All probes were directly labelled with fluorochromes allowing analysis in 2 h. Control lymphocytes demonstrated that the probes were of high specificity. For the sex chromosomes, five embryos were mosaic (15 per cent) with the remaining 29 being uniformly XX or XY. In no case was an XX nucleus found in an otherwise XY embryo, indicating that even though mosaicism for the sex chromosomes is present, such abnormalities would not lead to a misdiagnosis of sex. For the autosomes, 16 embryos were abnormal (46 per cent); one embryo was triploid, one was monosomic for chromosome 1, and ten others were diploid mosaics (three diploid/aneuploid, three diploid/polyploid, and four diploid/haploid). A further four embryos had variable chromosome numbers in the majority of nuclei which appeared to be the result of uncontrolled mitotic division. The presence of haploidy or double monosomy, which occurred in 15 per cent of nuclei, has important implications for the diagnosis of trisomies and dominant disorders.     

Variation of cholinergic biomarkers in brain regions and blood components of captive mink

Studies are increasingly using cholinergic parameters as biomarkers of early neurotoxicity, but few have characterized this system in ecologically relevant model organisms. In the present study, key neurochemicals in the cholinergic pathway were measured and analyzed from discrete parts of brain and blood from captive mink (Mustela vison). Similar to other mammals, the regional distribution of cholinergic parameters in the brain could be ranked from highest to lowest as: basal ganglia > occipital cortex > brain stem > cerebellum (F _3,192?=?172.1, p?<?0.001). Higher variation in cholinergic parameters was found in the cerebellum (coefficient of variation = 34.9%), and the least variation was measured in the brain stem (19.7%). Variation was also assessed by calculating the difference between the lowest and highest measures among individual animals: choline acetyltransferase (1.6× fold difference), cholinesterase (2.0×), muscarinic receptor levels (2.4×), acetylcholine (3.7×), nicotinic receptor levels (3.9×), and choline transporter (5.0×). In blood samples, activity and inter-individual variation of cholinesterase was highest in whole blood and lowest in plasma and serum. By using captive mink of a common genetic source, age, gender, and rearing conditions, these data help establish normal levels, ranges, and variations of cholinergic biomarkers among brain regions, blood components, and individual animals. Such information may better enable the utility of cholinergic biomarkers in environmental assessments.