Observations on the preferential biodegradation of selected components of polyaromatic hydrocarbon mixtures

The capacity of the naphthalene degrading enzyme (NAH) system of Pseudomonas fluorescens 5R and a number of other NAH system bacterial isolates to degrade mixtures of polyaromatic hydrocarbons (PAHs) and heterocyclic compounds were examined. It was found that all the examined organisms displayed similar patterns of preferential compound degradation when presented with the same mixture. Using strains that possess portions of the NAH system, this preferential degradation was localized to the activity of naphthalene dioxygenase. Comparisons of the first-order rates of compound degradation with the structures of the mixture components indicated that increased deviation from the base structure of naphthalene led to slower disappearance. Structural features that were found to decrease the rate of compound degradation include an increase in the number of methyl substituents and an increase in the size of a substituent.     

Mutagenicity tests with gallic and tannic acid in the Salmonella/mammalian microsome assay

Gallic acid, tannic acid mixture and a purified fraction of tannic acid were evaluated for possible mutagenic activity in three strains of Salmonella typhimurium, TA98, TA100, and TA1535. These chemicals were not mutagenic either before or after activation with rat and woodchuck microsomal and cytosolic enzymes. However, tannic acid mixture and tannic acid fraction both gave a significantly (p = 0.05) dose-related reduction in the number of the revertant colonies, compared to the normal spontaneous revertants with no apparent toxic effects in the background lawn. With an agar diffusion assay, the chemicals exhibited toxic effects at 5000 micrograms/disc.     

Lack of innate preference for morph and species identity in mate-searching <Emphasis Type="Italic">Enallagma</Emphasis> damselflies

Insect mate recognition is often viewed as stereotypic, innate, and species-specific. However, male damselflies can learn to identify female-specific color morphs as potential mates. A suite of male mimicry hypotheses assume that heteromorphic females, which differ from males in color pattern, are more easily recognized as “female” and thus lack the inherent, anti-harassment advantage that the more male-like signal provides for andromorphs. Using two measures of male preference, we investigated whether naïve males have a preexisting sensory bias for a given morph color in Enallagma civile, a species that appeared to exhibit extreme plasticity in morph expression across generations within a breeding season. E. civile males raised in the absence of females exhibited no preference for either morph, whereas males raised with one female type exhibited a learned sensory bias for that morph. Male Enallagma also lacked a bias toward conspecific females over a congeneric sister species. In a naturally naïve population of Enallagma ebrium, males reacted sexually to both morphs of Enallagma hageni as often as they did to conspecific females, whose thoracic spectra were nearly identical with those of E. hageni. Moreover, despite the similar thoracic spectra of males and andromorphs, both of which reflected UV, males rarely reacted sexually to other males. Our results falsified implicit assumptions of male mimicry hypotheses, supported learned mate recognition, and suggested a scenario for speciation via sexual conflict.     

Biomarker responses of <Emphasis Type="Italic">Peromyscus leucopus</Emphasis> exposed to lead and cadmium in the Southeast Missouri Lead Mining District

Biomarker responses and histopathological lesions have been documented in laboratory mammals exposed to elevated concentrations of lead and cadmium. The exposure of white-footed mice (Peromyscus leucopus) to these metals and the potential associated toxic effects were examined at three contaminated sites in the Southeast Missouri Lead Mining District and at a reference site in MO, USA. Mice from the contaminated sites showed evidence of oxidative stress and reduced activity of red blood cell δ-aminolevulinic acid dehydratase (ALAD). Histological examinations of the liver and kidney, cytologic examination of blood smears, and biomarkers of lipid peroxidation and DNA damage failed to show indications of toxic effects from lead. The biomagnification factor of cadmium (hepatic concentration/soil concentration) at a site with a strongly acid soil was 44 times the average of the biomagnification factors at two sites with slightly alkaline soils. The elevated concentrations of cadmium in the mice did not cause observable toxicity, but were associated with about a 50% decrease in expected tissue lead concentrations and greater ALAD activity compared to the activity at the reference site. Lead was associated with a decrease in concentrations of hepatic glutathione and thiols, whereas cadmium was associated with an increase. In addition, to support risk assessment efforts, we developed linear regression models relating both tissue lead dosages (based on a previously published a laboratory study) and tissue lead concentrations in Peromyscus to soil lead concentrations.     

Sorption, desorption and mineralisation of the herbicides glyphosate and MCPA in samples from two Danish soil and subsurface profiles

The vertical distribution of the sorption, desorption and mineralisation of glyphosate and MCPA was examined in samples from two contrasting soil and subsurface profiles, obtained from a sandy agricultural site and a non-agricultural clay rich site. The highest mineralisation of [14C-methylen]glyphosate, with 9.3-14.7% degraded to 14CO2 within 3 months was found in the deepest sample from the clay site. In the deeper parts of the sandy profile high sorption and low desorption of glyphosate coincided with no or minor mineralisation indicating a limited glyphosate bioavailability. MCPA was readily mineralised except in the deepest samples from both sites. The highest MCPA mineralisation was detected just below the surface layers with 72% or 44% degraded to 14CO2 at the sandy or the clay sites, respectively. MCPA sorped to a minor extent in all samples and no indications of sorption-controlled mineralisation was revealed. None of the herbicides were mineralised under anoxic conditions.     

Unusual sonographic features of ARPKD

The classic sonographic appearance of the kidneys in fetuses with autosomal recessive polycystic kidney disease (ARPKD) has been well described. We report a case of enlarged kidneys with pyramidal hyperechogenicity quite similar to medullary nephrocalcinosis found in a fetus at 34 weeks' gestation. At 39 weeks, a female neonate was delivered and died after 22 h due to pulmonary insufficiency secondary to severe oligohydramnios. On pathological analysis, the gross and microscopic findings were typical of ARPKD with diffuse dilatation of tubules throughout. The fetal renal lobulation was prominent and on section, the pyramids were delineated within each lobule, accounting for the clear image of the pyramids observed on sonography. Copyright © 2006 John Wiley & Sons, Ltd.     

Polychlorodibenzo-p-dioxins and dibenzofurans in technical pentachlorophenol - results of a collaborative analytical exercise

Results of analyses of eight samples of technical pentachlorophenol conducted by three different analytical methods are presented and discussed.