Effect of Soil Dose on Bioavailability of Lead from Mining Waste Soil in Rats

Abstract

The purpose of this study was to determine the extent of absorption of lead (Pb) in mining waste soil from Butte, Montana. It is the first study to fully investigate the bioavailability of lead in soils containing mine waste using a soil dose response approach. Young 7–8 week-old male and female Sprague-Dawley rats (5 animals/sex/group) were given mining waste soil [810 ppm lead (Test Soil I) or 3,908 ppm lead (Test Soil III)] mixed in a purified diet (AIN—76?) at four different dose levels (0.2, 0.5, 2 and 5% dietary soil) for 30 consecutive days. The test soil dose levels at 2 and 5% were chosen to bracket a pica-for-soil child's soil exposure levels. A pica-for-soil child is a young child who eats large quantities of soil (10 g day^?1). Standard groups included untreated controls and dosed feed soluble lead acetate groups (1, 10, 25, 100 and 250 μg Pb g^?1 feed). The concentrations of lead acetate were chosen to bracket the test soil dose levels of lead. Liver, blood and femur, representing the three compartments in which lead is distributed in the body, were analyzed for total lead concentration using graphite furnace atomic absorption spectroscopy. Clinical signs, body weight, food consumption and liver weights for treated and standard groups were similar to control. Tissue lead concentrations from test soil animals were significantly lower than the tissue concentrations for the dosed feed lead acetate group. Group mean whole blood, bone and liver lead concentrations increased with increasing dose levels for most treatment groups. The increases in blood, bone and liver lead concentrations were not proportional with increasing dose levels and plateaued at the high dose levels. Relative percent bioavailability values, based on dosed feed soluble lead as the standard, were independent of the two different test soils, dose levels or sex, and only slightly dependent on the tissue (blood > bone, liver). Overall relative percent bioavailability values were 20% based on the blood data; 9% based on the bone data; and 8% based on the liver data (2 and 5% dose levels only). The results of this study will provide the scientific validity needed to determine the significance of lead exposure from Butte soils in assessing human health risks as part of the Superfund Remedial Investigation/Feasibility Study process.     

Stable isotopes of Lithosiini and lichens in Hong Kong show the biodindicator potential of lichenivorous moths

Urban landscapes provide unique environments for a wide variety of plants and animals, but their suitability may be limited by anthropogenic impacts such as pollution. We examined the potential utility of lichen and lichen-feeding moths as biodindicators of air pollution in Hong Kong by comparing carbon (C) and nitrogen (N) stable isotope values in lichens, lichenivorous and non-lichenivorous moths (Lepidoptera: Erebidae) and a moth outgroup (Lepidoptera: Geometridae). Our results show that stable isotope values for C and N were similar for lichens and lichen feeding moths, while non-lichen feeding moths formed a distinct group. In addition, we found consistent δ¹³C and δ¹⁵N values across moth body parts, indicating that any portion of the specimen is suitable for isotopic fingerprinting. Our results highlight that lichen feeding moths may be useful for integrating signals of atmospheric nitrogen pollution and could therefore have utility in monitoring and quantifying air quality over time and space.     

Photocontrol of anthocyanin biosynthesis in tomato

Juvenile anthocyanin biosynthesis has been studied in dark-grown seedlings of tomato (Lycopersicon esculentum Mill.) wild types (WTs) and photomorphogenic mutants. During a subsequent 24-hr period of monochromatic irradiation at different fluence rates of red light (R) the fluence-rate response relationships for induction of anthocyanin in all the WTs are similar, yet complex, showing a response at low fluence rates (LFRR) followed by a fluence rate-dependent high irradiance response (HIR). In the hypocotyl this response is restricted to the sub-epidermal layer of cells. The high-pigment-1 (hp-1) mutant exhibits a strong amplification of both response components. Theatroviolacea (atv) mutant shows strongest amplification of the HIR component. In contrast, a transgenic line overexpressing an oat phytochrome A gene (PHYA3 ⁺) shows a most dramatic amplification of the LFRR component. The far-red light (FR)-insensitive (fri) mutant, deficient in phytochrome A (phyA), lacks the LFRR component whilst retaining a normal HIR. The temporarily R-insensitive (tri) mutant, deficient in phytochrome B1 (phyB1) retains the LFRR, but lacks the HIR. Thehp-1,fri andhp-1,tri double mutant, exhibit amplified, yet qualitatively similar responses to the monogenicfri andtri mutants. Thefri,tri double mutant lacks both response components in R, but a residual response to blue light (B) remains. Similarly, theaurea (au) mutant deficient in phytochrome chromophore biosynthesis and presumably all phytochromes, lacks both response components in the R and FR regions of the spectrum. Experiments at other wavelengths demonstrate that while there is only a small response in the FR spectral region (729 nm) in tomato, there is an appreciable HIR response in the near FR at 704 nm, which is retained in thetri mutant. This suggests that the labile phyA pool participates in the HIR at this wavelength. The intense pigmentation (Ip) mutant appears to be specifically deficient in the B1 induced anthocyanin biosynthesis. Adult plants, grown under fluorescent light/dark cycles, show a reduction of anthocyanin content of young developing leaves upon application of supplemtary or end-of-day FR. The involvement of different phytochrome species in anthocyanin biosynthesis based on micro-injection studies into theau mutant and studies using type specific phytochrome mutants is discussed.     

Characterisation of the procera mutant of tomato and the interaction of gibberellins with end-of-day far-red light treatments

The tomato ( Solanum lycopersicum L.) slender mutant procera ( pro ) was analysed for its relationship with gibberellin (GA) by combining it with GA deficiency due to the gib-1 mutation. The sensitivity to GA biosynthesis inhibitors and the GA content were measured in the pro gib-1 double mutant. In the gib-1 mutant background, the pro mutation strongly reduced the GA requirement for seed germination and stem growth and almost fully restored the morphological leaf defects of the gib-1 mutant. An end-of-day far-red light treatment, when applied to the various genotypes, indicated that GAs are required for a response to this treatment, but that it act independently of the Pro gene product.     

Disturbance and reef topography maintain high local diversity in Ecklonia radiata kelp forests

Disturbance of competitive‐dominant plant and algae canopies often lead to increased diversity of the assemblage. Kelp forests, particularly those of temperate Western Australia, are habitats with high alpha diversity. This study investigated the roles of broad‐scale canopy loss and local scale reef topography on structuring the kelp‐dominated macroalgal forests in Western Australia. Eighteen 314 m² circular areas were cleared of their Ecklonia radiata canopy and eighteen controls were established across three locations. The patterns of macroalgal recolonisation in replicate clearances were observed over a 34 month period. Macroalgal species richness initially increased after canopy removal with a turf of filamentous and foliose macroalgae dominating cleared areas for up to seven months. A dense Sargassum canopy dominated cleared areas from 11 to 22 months. By 34 months, partial recovery of the kelp canopy into cleared areas had occurred. Some cleared areas did not follow this trajectory but remained dominated by turfing, foliose and filamentous algae. As kelp canopies developed, the initial high species diversity declined but still remained elevated relative to undisturbed controls, even after 34 months. More complex reef topography was associated with greater variability in the algal assemblage between replicate quadrats suggesting colonising algae had a greater choice of microhabitats available to them on topographically complex reefs. Shading by canopies of either Sargassum spp. and E. radiata are proposed to highly influence the abundance of algae through competitive exclusion that is relaxed by disturbance of the canopy. Disturbance of the canopy in E. radiata kelp forests created a mosaic of different patch types (turf, Sargassum‐dominated, kelp‐dominated). These patch types were both transient and stable over the 34 months of this study, and are a potential contemporary process that maintains high species diversity in temperate kelp‐dominated reefs.     

Longitudinal investigation of neuroinflammation and metabolite profiles in the APPswe×PS1Δe9 transgenic mouse model of Alzheimer's disease

There is increasing evidence linking neuroinflammation to many neurological disorders including Alzheimer's disease (AD); however, its exact contribution to disease manifestation and/or progression is poorly understood. Therefore, there is a need to investigate neuroinflammation in both health and disease. Here, we investigate cognitive decline, neuroinflammatory and other pathophysiological changes in the APP_swe×PS1_Δe9 transgenic mouse model of AD. Transgenic (TG) mice were compared to C57BL/6 wild type (WT) mice at 6, 12 and 18 months of age. Neuroinflammation was investigated by [¹⁸F]DPA‐714 positron emission tomography and myo‐inositol levels using ¹H magnetic resonance spectroscopy (MRS) in vivo. Neuronal and cellular dysfunction was investigated by looking at N‐acetylaspartate (NAA), choline‐containing compounds, taurine and glutamate also using MRS. Cognitive decline was first observed at 12 m of age in the TG mice as assessed by working memory tests . A significant increase in [¹⁸F]DPA‐714 uptake was seen in the hippocampus and cortex of 18 m‐old TG mice when compared to age‐matched WT mice and 6 m‐old TG mice. No overall effect of gene was seen on metabolite levels; however, a significant reduction in NAA was observed in 18 m‐old TG mice when compared to WT. In addition, age resulted in a decrease in glutamate and an increase in choline levels. Therefore, we can conclude that increased neuroinflammation and cognitive decline are observed in TG animals, whereas NAA alterations occurring with age are exacerbated in the TG mice. These results support the role of neuroinflammation and metabolite alteration in AD and in ageing.

     

Allozymic, morphological, and phenological diversity in cultivatedLuffa acutangula (Cucurbitaceae) from China, Laos, and Nepal, and Allozyme Divergence betweenL. acutangula andL. Aegyptiaca

The immature fruits of domesticated Luffa acutangula (L.) Roxb. are a common vegetable in Asia and India. To learn more about traditional cultivars, accessions were collected from southern Yunnan Province of China, northern Laos, and southeastern Nepal, and assessed for various parameters of genetic diversity. The size and shape of the fruits and seeds varied considerably. A form that we found cultivated only in Nepal bore clusters of small fruits that are produced by hermaphrodite flowers. Plants produced male flowers first, and the first node to bear flowers varied from the second to the twenty-seventh. Twenty-nine allozyme loci were assayed. Within L. acutangula one allozyme locus was polymorphic. Luffa acutangula andL. aegyptiaca are fixed for different alleles at nine loci, indicating that they are completely reproductively isolated from each other.