Cytogenetic experience in prenatal fra(X) detection on amniotic fluid cultures

Since 1987, we have had experience with 13 prenatal diagnoses of 11 women at risk for the fragile X syndrome by cytogenetic studies on amniotic fluid cultures. The induction method included TC 199 medium and methotrexate. Results were obtained in all cases. Ten were males and three were prenatally diagnosed as being affected. Three were females and none of them was fra(X)-positive. Results were confirmed in 10/13 cases. In these cases, we had neither false-positive nor false-negative results.     

Scanning Electron Microscopy of Humic Substances Produced During Cellulose Decomposition

Humic substances (HS) produced during the aerobic decomposition of polysaccharides still need to be recognized as such and characterized. Humic (HA) and fulvic (FA) acids extracted at different time intervals during composting of cotton residues from carding, where no decomposition of lignin occurred, were investigated by scanning electron microscopy (SEM) size exclusion chromatography and infrared spectroscopy. Throughout the experiment, fulvic acids possessed a larger number of carboxyl groups but a lower number of weak acidic groups (negatively charged acid groups at pH 11) than humic acids. the number of carboxyl groups increased with time in both fulvic and humic acids, while that of phenolic groups decreased. Infrared spectra showed that the ratio between carboxyl and methyl groups decreased from 8.5 to 4 in FA after 18 days. This change corresponded with the disappearance of flat sheet structures observed by SEM at pH 6. Our results suggest that the shape of humic molecules as observed by SEM reflects the strength of hydrophilic/hydrophobic interactions with the solvent molecules. About 80% of FA molecules had a molecular weight lower than 3500 as deduced from column calibration with HS standards obtained by ultrafiltration. About 40% of humic acids were composed of small molecules; only 20% HA had a molecular weight larger than 45000. Polysaccharide-derived HS may not be limited to the high molecular weight poorly transformed fraction containing bonded polysaccharide structures, but may also consist of low molecular weight components with no structural similarity to the original material.     

Diagnosing Units of Conservation Management

Species-oriented conservation programs attempt to analyze and maintain intra-specific variation in order to maximally preserve biological diversity. The "evolutionarily significant unit" has become an operational term for a group of organisms that should be the minimial unit for conservation management. No generally accepted definition for this term exists that would be the basis for the evaluation of these units in practical conservation situations. Currently, taxonomic decisions in species conservation are mostly based on the biological species concept. But the universal application of criteria of reproductive isolation or phenetic similarity to delimit conservation units is problematical. We favor a definition for evolutionarily significant units based on patterns of variation. In the theoretical framework of the phylogenetic species concept, conservation units are delimited by characters that diagnose clusters of individuals or populations to the exclusion of other such clusters. Characters are used for cladistic analysis to infer hypotheses of the phylogenetic relationships of individuals, and differentiated populations are diagnosed using population aggregation analysis. Characters can be based on genetic, morphological, ecological, or behavioral information, provided they are inferred to be heritable. The use of cladistics and population aggregation analysis has the potential to make the evaluation of evoluntionarily significant units objective and testable, an important consideration in politically controversial cases. Our cladistic approach is demonstrated by the evaluation of potential conservation units in the endangered tiger beetles Cicindela dorsalis and C. puritana .     

Thermal hazard in a batch process involving hydrogen peroxide

Hydrogen peroxide is a versatile and interesting reagent for many industrial processes; nevertheless, it is very sensitive to impurities that can catalyze its decomposition, so that the desired reaction could be accompanied by undesired parallel and consecutive reactions. As an example, the butadiene free radical polymerization with hydrogen peroxide in the presence of an organic solvent was studied. Batch polymerization occurs in the liquid phase at about 120 °C. Because of the involved reactive compounds and the relatively high temperature, this is an intrinsically dangerous reaction. Therefore calorimetric data can give important information about safety and process optimization during the scale-up. The aim of this research project was to study the influence of impurities on the overall heat of reaction. The experiments were made in a high-pressure reaction calorimeter. The study has revealed that impurities do indeed affect the reaction course. Most importantly, the presence of carboxylic acids and/or ionic iron must be avoided and the recycle of unreacted reagents must be carefully controlled to minimize the build-up of these impurities.     

A correlation study between multiple sclerosis and type 1 diabetes incidences and geochemical data in Europe

Complex multifactorial disorders usually arise in individuals genetically at risk in the presence of permissive environmental factors. For many of these diseases, predisposing gene variants are partly known while the identification of the environmental component is much more difficult. This study aims to investigate whether there are correlations between the incidence of two complex traits, multiple sclerosis and type 1 diabetes, and some chemical elements and compounds present in soils and stream sediments in Europe. Data were obtained from the published literature and analyzed by calculating the mean values of each element and of disease incidence for each Country, respectively, 17 for multiple sclerosis and 21 for type 1 diabetes. Correlation matrices and regression analyses were used in order to compare incidence data and geochemical data. R correlation index and significance were evaluated. The analyses performed in this study have revealed significant positive correlations between barium and sodium oxide on one hand and multiple sclerosis and diabetes incidences on the other hand that may suggest interactions to be evaluated between silicon-rich lithologies and/or marine environments. The negative correlations shown by cobalt, chromium and nickel (typical of silicon-poor environment), which in this case can be interpreted as protective effects against the two diseases onset, make the split between favorable and protective environments even more obvious. In conclusion, if other studies will confirm the involvement of the above elements and compounds in the etiology of these pathologies, then it will be possible to plan strategies to reduce the spread of these serious pandemics.     

Evaluation of flow injection analysis method with spectrophotometric detection for the determination of atrazine in soil extracts

A method for determining atrazine in soil extracts was evaluated by flow injection analysis with spectrophotometric detection. The method is based on the reaction of atrazine with pyridine in an acid medium followed by the reaction with NaOH and sulfanilic acid. Several analytical conditions were previously studied and optimized. Under the best conditions of analysis, the limits of detection and quantification were 0.15 and 0.45 mg L^?1, respectively, for a linear response between 0.50 and 2.50 mg L^?1, and a sampling throughput of 21 determinations per hour. Using the standard addition method, the maximum relative standard deviation of 17% and recovery values between 80 and 100% were observed for three extracts from soil samples with different composition. The proposed method is simple, low-cost and easy to use, and can be employed for studies involving atrazine in soil samples or for screening of atrazine in soils.     

A framework for habitat monitoring and climate change modelling: construction and validation of the Environmental Stratification of Estonia

Environmental stratifications provide the framework for efficient surveillance and monitoring of biodiversity and ecological resources, as well as modelling exercises. An obstacle for agricultural landscape monitoring in Estonia has been the lack of a framework for the objective selection of monitoring sites. This paper describes the construction and testing of the Environmental Stratification of Estonia (ESE). Principal components analysis was used to select the variables that capture the most amount of variation. Seven climate variables and topography were selected and subsequently subjected to the ISODATA clustering routine in order to produce relatively homogeneous environmental strata. The ESE contains eight strata, which have been described in terms of soil, land cover and climatic parameters. In order to assess the reliability of the stratification procedure for the selection of monitoring sites, the ESE was compared with the previous map of Landscape Regions of Estonia and correlated with five environmental data sets. All correlations were significant. The stratification has therefore already been used to extend the current series of samples in agricultural landscapes into a more statistically robust series of monitoring sites. The potential for applying climate change scenarios to assess the shifts in the strata and associated ecological impacts is also examined.     

Governing water in federal river basins

Regional Environmental Change -