Mercury stress on juvenile bay scallops,Argopecten irradians,under various salinity-temperature regimes

Survival of juvenile bay scallops, Argopecten irradians, after 96 h of exposure to mercury at various salinity and temperature regimes was studied. Scallop survival was significantly affected by mercury concentration and by salinity, as well as by the interaction between temperature and concentration and between temperature and salinity. Toxicity of mercury at low concentrations was enhanced by high temperature and low salinity, whereas at high mercury concentrations this effect diminished.     

A 10-year survey, 1980–1990, of prenatally diagnosed small supernumerary marker chromosomes,identified by fish analysis. Outcome and follow-up of 14 cases diagnosed in a series of 12 699 prenatal samples

A cytogenetic survey and follow-up studies were made of 14 cases with supernumerary marker chromosomes, identified among 12 699 prenatal samples, investigated at our institution over a 10-year period from 1980 to 1990. FISH (fluorescence in situ hybridization) techniques were employed to identify the chromosomal origin of the marker chromosomes. Five cases were familial, all derived from acrocentric chromosomes, and all without apparent phenotypic effects in the children. Nine cases represented de novo aberrations. In two cases (one with a marker from chromosome 14 or 22, the other with a ring-like marker derived from chromosome 17), the pregnancies continued and apparently normal babies were delivered at term, but the child with a marker derived from chromosome 17 showed slight psychomotor retardation at 2 years of age. All other pregnancies with de novo markers were terminated. In three cases, significant abnormalities were found at autopsy. One of these had an isochromosome 12p and the phenotype was consistent with Pallister-Killian syndrome. In conclusion, marker chromosome identification, as well as clinical follow-up, is essential for the purpose of improving genetic counselling.     

The ultrasonic detection of an isolated craniosynostosis

The prenatal detection of scaphocephaly, an isolated form of craniosynostosis, is presented. The diagnosis was made at 34 weeks of gestation in a woman with polyhydramnios. The ultrasound appearance and postnatal follow-up are presented.     

Duplex auditory distance assessment in a small passerine bird (Pipilo erythrophthalmus)

Eastern towhees, Pipilo erythrophthalmus, (Emberizidae, Passeriformes) in Florida estimate source sound-pressure level (SPL; i.e., sound amplitude) and often misjudge speaker distance in the field when vocalization source SPL is varied experimentally. Sound frequencies below ~3.5 kHz attenuate reliably with distance in comparison with higher sound frequencies in Florida scrub habitat. As a result, I predicted that towhees should use SPL as an auditory distance cue when they hear stimuli produced with sound frequencies below ~3.5 kHz but use another cue when they hear stimuli produced with sound frequencies above ~3.5 kHz. Subjects often misjudged speaker distance when approaching playbacks of SPL-altered stimuli produced with sound frequencies below ~3.5 kHz but rarely misjudged speaker distance when played SPL-altered stimuli produced with sound frequencies above ~3.5 kHz. I discuss the possibility that towhees employ a duplex sound localization strategy.     

The association between ‘faint-positive’ amniotic fluid acetylcholinesterase and fetal malformations

The finding of a ‘faint-positive’ acetylcholinesterase band in amniotic fluid samples of women at 15 weeks' gestation or above is associated with an increased risk of fetal abnormalities, most commonly gastroschisis. This finding warrants a targeted sonographic evaluation, in order to rule out significant fetal malformations.     

Prenatal molecular diagnosis of gaucher disease

Prenatal diagnosis of Gaucher disease, the most prevalent glycolipid storage disease, is based on a reliable enzyme assay of cells from amniocentesis or chorionic villous samples. However, this method cannot differentiate among the various forms of the disease. This report details four cases of prenatal diagnosis of Gaucher disease, three of which predate the use of molecular diagnosis. DNA mutation analysis to determine the genotype was predictive of the phenotypic status of the fetus and conformed to the genotype of an affected proband where available.     

Perceptions of Species Abundance,Distribution, and Diversity: Lessons from Four Decades of Sampling on a Government-Managed Reserve

/ We examined data relative to species abundance, distribution, anddiversity patterns of reptiles and amphibians to determine how perceptionschange over time and with level of sampling effort. Location data werecompiled on more than one million individual captures or observations of 98species during a 44-year study period on the US Department of Energy's(DOE) Savannah River Site National Environmental Research Park (SRS-NERP) inSouth Carolina. We suggest that perceptions of herpetofaunal speciesdiversity are strongly dependent on level of effort and that land managementdecisions based on short-term data bases for some faunal groups could resultin serious errors in environmental management. We provide evidence thatacquiring information on biodiversity distribution patterns is compatiblewith multiyear spatially extensive research programs and also provide aperspective of what might be achieved if long-term, coordinated researchefforts were instituted nationwide.To conduct biotic surveys on government-managed lands, we recommend revisionsin the methods used by government agencies to acquire and report biodiversitydata. We suggest that government and industry employees engaged inbiodiversity survey efforts develop proficiency in field identification forone or more major taxonomic groups and be encouraged to measure the status ofpopulations quantitatively with consistent and reliable methodologies. Wealso suggest that widespread academic cooperation in the dissemination ofinformation on regional patterns of biodiversity could result byestablishment of a peer-reviewed, scientifically rigorous journal concernedwith status and trends of the biota of the United States. KEY WORDS: Abundance; Amphibian; Biodiversity; Distribution; Landmanagement; Reptile     

An evaluation of the tapered element oscillating microbalance method for measuring diesel particulate emissions

We determined the usefulness of tapered element oscillating microbalances (TEOMs) for researchers and engineers involved with measuring diesel particulate mass. Two different test facilities were used for generating diesel particulates and comparing the TEOM to the commonly used U.S. Environmental Protection Agency (EPA) manual filter method. The EPA method is very labor-intensive and requires long periods of time to complete. The TEOM is an attractive approach because it has the potential to reduce the amount of time and labor required in diesel testing, as well as to provide real-time particulate-mass data that are not obtainable with the EPA method. It was found that the TEOM was a precise and easy-to-operate instrument that could measure the mass concentration (MC) of diesel particulate emissions in real time. Although the TEOM diesel particulate MC measurements were highly correlated with the manual filter measurements, the two techniques were not equivalent because the TEOM consistently reported MC results that were 20-25% lower than those obtained using the manual filter technique. In conclusion, the TEOM can be used to increase test-cell throughput and to measure transient values of diesel particulate emissions at sites performing diesel-engine testing. However, unless EPA is able to certify the TEOM as an equivalent method, it cannot replace the manual filter method for diesel certification work.     

Development of emission factors for polycarbonate processing

Emission factors for selected volatile organic compounds (VOCs) and particulate emissions were developed while processing eight commercial grades of polycarbonate (PC) and one grade of a PC/acrylonitrile-butadiene-styrene (ABS) blend. A small commercial-type extruder was used, and the extrusion temperature was held constant at 304 degrees C. An emission factor was calculated for each substance measured and is reported as pounds released to the atmosphere/million pounds of polymer resin processed [ppm (wt/wt)]. Scaled to production volumes, these emission factors can be used by processors to estimate emission quantities from similar PC processing operations.     

Transformation products distribution of atrazine in corn plants treated with radiolabelled herbicide

Roots of whole plants at four leaf stage grown in specialized soil treatment vessels were treated with ¹⁴C-atrazine. Plant tissues were exhaustively extracted with methanol and extracts were separated by preparative thin layer chromatography (TLC). The extracted material was separated in two TLC bands at Rf0.00 and Rf0.18 containing 33% and 67% of plant ¹⁴C-residues, respectively. Methanol extracts of these bands subjected to derivatization, hydrolysis and analysis by TLC, revealed the presence of a number of transformation products consisting of hydroxy analogues of atrazine and their dealkylated metabolites. The transformation products had variable distribution patterns amongst leaf, stalk and root tissues. Diaminohydroxyatrazine, hydroxyatrazine, and deethylhydroxyatrazine were the main ¹⁴C-residues. Stalk tissue contained more ¹⁴C-residues which were largely located at and just below the ligule. The significance of ¹⁴C-residue accumulation at the ligule and the transformation product compartmentalization are discussed.