Role of Organic Carbon Sources and Sulfate in Controlling Net Methylmercury Production in Riverbank Sediments of the South River,VA (USA)

Mercury (Hg) transport and methylmercury (MeHg) production in riverbank sediments are complex processes influenced by site-specific physical and biogeochemical conditions. The South River watershed in VA, USA, contains elevated concentrations of Hg in riverbank and floodplain sediments, which has the potential to methylate. The role of specific organic carbon sources in promoting methylation reactions in natural sediments under dynamic flow conditions is not well understood. Four saturated column experiments were conducted, including a control column, which received South River water as an influent solution, and three columns that received South River water amended with: acetate (5.8 mM); lactate (5.7 mM); and lactate (5.7 mM) with SO₄^2? (10.1 mM). The amendments were selected to promote growth of different microorganisms to gain an understanding of the microbial processes, controlling rates of methylation. The column receiving lactate and SO₄^2? had the highest MeHg concentrations in the effluent and in the pore water near the effluent at 1.8 and 4.9 μg L^?1, respectively. At the cessation of the column experiments, the lactate–sulfate column sediments contained the highest populations of enumerable sulfur-reducing bacteria and the highest solid-phase MeHg at 530 ± 100 ng g^?1 dry wt. from the interval closest to the influent. The results suggest that the form and availability of electron donors and acceptors are primary factors controlling rates of methylation in the South River sediment.     

Agroenergy Crops Influence the Diversity, Biomass, and Guild Structure of Terrestrial Arthropod Communities

Expanded production of contemporary bioenergy crops (e.g., corn) is considered a threat to the conservation of biodiversity, yet next-generation perennially based crops (switchgrass, mixed-grass?Cforb prairie) may represent an opportunity for enhancing biodiversity in agricultural landscapes. We employed a multi-scaled approach to investigate the relative importance of feedstock selection, forb content, patch size, and landscape-scale habitat structure and composition as factors shaping the diversity and abundance of terrestrial arthropod communities and the biomass of functional groups of arthropods associated with the provisioning of ecosystem services. Compared to intensively managed annual corn fields, switchgrass and mixed-grass?Cforb prairie plantings were associated with a 230% and 324% increase in arthropod family diversity and a 750% and 2,700% increase in arthropod biomass, respectively. Biomass of arthropod pollinators, herbivores, predators, and parasites were similarly the highest in mixed-grass?Cforb prairie, intermediate in switchgrass plantings, and the lowest in cornfields. Community-wide biomass and that of several functional arthropod groups were positively linked to increasing forest cover and land cover diversity surrounding biomass plantings, while pollinator and detritivore biomass was lower in smaller fields. Results not only suggest that the choice of biomass feedstock will play an important role in shaping within-field arthropod diversity but also indicate an important role for the composition of this surrounding landscape. Collectively, our results suggest that selection of perennially based biomass feedstocks along with careful attention to crop placement have important potential to enhance biodiversity conservation and the provisioning of ecologically and economically important arthropod-mediated ecosystem services in future agricultural landscapes.     

Cortical motion deafness

The extent to which the auditory system, like the visual system, processes spatial stimulus characteristics such as location and motion in separate specialized neuronal modules or in one homogeneously distributed network is unresolved. Here we present a patient with a selective deficit for the perception and discrimination of auditory motion following resection of the right anterior temporal lobe and the right posterior superior temporal gyrus (STG). Analysis of stimulus identity and location within the auditory scene remained intact. In addition, intracranial auditory evoked potentials, recorded preoperatively, revealed motion-specific responses selectively over the resected right posterior STG, and electrical cortical stimulation of this region was experienced by the patient as incoming moving sounds. Collectively, these data present a patient with cortical motion deafness, providing evidence that cortical processing of auditory motion is performed in a specialized module within the posterior STG.     

Comparative life cycle assessment of reused versus disposable dental burs

Purpose

Health care infection control has led to increased utilization of disposable medical devices, which has subsequently led to adverse environmental effects attributed to health care and its supply chain. In dental practice, the dental bur is a commonly used instrument that can be either reused or used once and then disposed. To evaluate the disparities in environmental impacts of disposable and reusable dental burs, a comparative life cycle assessment (LCA) was performed.

Methods

The functional unit was defined as one reusable dental bur, where the maximum instances reused was 30 (or in the case of a disposable, the equivalent functional unit would be 30 disposable dental burs). The system boundary included all cradle-to-grave aspects of both single-use and reused burs, including raw material extraction, manufacturing, packaging, distribution, reuse, and disposal. Primary data included the following: operating parameters for ultrasonic cleaning, manual cleaning, and autoclaving of the burs. The secondary data for raw material extraction and production of dental bur and packaging were obtained directly from life cycle inventory databases. Sensitivity analyses were also performed with respect to ultrasonic and autoclave loading.

Results and discussion

Findings from this research showed that when the ultrasonic and autoclave were loaded optimally, reusable burs had 40 % less of an environmental impact than burs used on a disposable basis. When the autoclave and ultrasonic were loaded to approximately two-third capacity, four environmental impact categories favored reusable burs (i.e., ozone depletion, smog, respiratory effects, exotoxicity), and four impact categories environmentally favored disposables (i.e., acidification, eutrophication, carcinogenics, and non-carcinogenics). When the autoclave and ultrasonic were loaded to approximately one-third capacity, reusable dental burs posed more negative environmental impacts in eight of nine environmental impact categories when compared to disposable burs.

Conclusions

Operational efficiency of ultrasonic and autoclave cleaning equipment should be emphasized to enhance the environmental performance of bur reuse. In fact, improper loading of the ultrasonic and autoclave can lead to greater adverse environmental impacts than if the burs were treated as disposables. The environmental and economic impacts associated with bur reuse are expected to be similar with other dental devices that are designated as disposable but are capable of being reused (e.g., scalpels, forceps).     

Cerebrospinal fluid,plasma, and urinary MHPG in children

Cerebrospinal fluid (CSF) free MHPG levels for six autistic and four medicated Tourette Syndrome (TS) patients are in the usual adult range, but levels are elevated in two recently medicated TS patients. Plasma free MHPG levels in unmedicated autistic and TS patients are similar to those in normal boys, but are increased in two of seven medicated TS patients. There is a strong association between plasma free MHPG and urinary total MHPG levels in normal boys. Age and total urinary MHPG are positively correlated in autistic children. MHPG appears to be a useful index of noradrenergic function in childhood neuropsychiatric disorders.     

TNF-alpha, IL-4, and IFN-gamma regulate differential expression of P- and E-selectin expression by porcine aortic endothelial cells

P- and E-selectin are surface glycoproteins that mediate leukocyte rolling on the surface of endothelium in inflammation. We have cloned porcine P-selectin cDNA and generated a mAb, 12C5, with which to examine P-selectin expression by porcine aortic endothelial cells (PAEC) in comparison with that of E-selectin. Basal expression by PAEC of P-selectin was greater than that of E-selectin, whereas E-selectin expression was more prominently enhanced than that of P-selectin by stimulation with TNF-alpha or IL-1alpha. Both human or porcine IL-4 led to an increase in P-selectin expression, with kinetics that were delayed compared with those seen following stimulation with TNF-alpha or IL-1alpha, but IL-4 did not stimulate expression of E-selectin. When cells were stimulated with TNF-alpha in the presence of IL-4, we observed enhanced P-selectin expression with a parallel reduction in E-selectin expression. Finally, the increase in P-selectin expression due to human IL-4 was reduced in the presence of porcine but not human IFN-gamma. These observations show that E-selectin and P-selectin expression are differentially regulated in PAEC, and that IL-4 leads to a shift in the relative surface density of the two molecules toward P-selectin. The ability of porcine IFN-gamma to inhibit IL-4-induced P-selectin expression suggests that the balance between Th1 and Th2 cytokine production may determine the relative densities of the two selectins in chronic immune-mediated inflammation. Because the increased expression of P-selectin induced by human IL-4 was not inhibited by human IFN-gamma, this balance may be shifted toward P-selectin expression in porcine xenografts infiltrated by human lymphocytes.     

High-performance liquid chromatographic separation of ascorbic acid,erythorbic acid,dehydroascorbic acid,dehydroerythorbic acid,diketogulonic acid,and diketogluconic acid

High-performance liquid chromatography on a Zorbax NH₂ analytical column, with acetonitrile: 0.05 m KH₂PO₄ (75:25, $\text{w}\text{w}$) used as eluant, has allowed the separation, in less than 14 min, of ascorbic acid, erythorbic acid, dehydroascorbic acid, dehydroerythorbic acid, diketogulonic acid, and diketogluconic acid. Ultraviolet monitoring at 268 nm allows ascorbic acid and erythorbic acid to be detected at the 25-ng level, while refractive index detection monitors the elution of all six compounds. Tyrosine is a good internal standard, being well separated from the other compounds and having an adequate ultraviolet absorption at 268 nm. We have found dithiothreitol to be effective in rapidly reducing dehydroascorbic acid to ascorbic acid, providing the basis for indirectly determining dehydroascorbic acid after its reduction. The potential of this high-performance liquid chromatographic procedure for evaluating the levels of these compounds in orange juice and urine is demonstrated.     

Membrane properties of cultured rat sympathetic neurons: Morphological studies of adrenergic and cholinergic differentiation

Dissociated neurons from the newborn rat superior cervical ganglion were grown under conditions which lead to either adrenergic or cholinergic differentiation. Lectins and toxins were used to detect differences in the cell membrane associated with transmitter status, age of the neurons, or location on the neurons. These ligands were made visible in the light or electron microscope by coupling to rhodamine or colloidal gold. The density of binding sites for concanavalin A (Con A), ricin (RCA₆₀), and wheat germ agglutinin (WGA) increased with age in culture on both adrenergic and cholinergic cells. Soybean agglutinin (SBA) binding increased about threefold on adrenergic axons, but failed to increase on neurons induced to become cholinergic by medium conditioned by rat heart cells (CM). The effect of CM on SBA binding paralleled previously described effects of CM on transmitter production; the CM binding pattern developed slowly and was not readily reversible. Mature adrenergic neurons also appeared to bind more WGA than neurons in CM cultures. Tetanus toxin gold binding was uniform, but low, on axons of adrenergic and cholinergic neurons at all ages. In contrast, cholera toxin binding decreased with age on adrenergic axons. Binding sites for SBA and tetanus toxin were found to be less numerous on the cell body surface than on the axonal surface. Thus growth in CM induces fundamental changes in the phenotype of developing sympathetic neurons involving the cell membrane as well as transmitter choice. Differences also appear with maturation and between axonal and somatic cell surface membranes.     

An updated classification for the hyper-diverse genus Corydalis (Papaveraceae: Fumarioideae) based on phylogenomic and morphological evidence

The genus Corydalis, with ca. 530 species, has long been considered taxonomically challenging because of its great variability. Previous molecular analyses, based on a few molecular markers and incomplete taxonomic sampling, were clearly inadequate to delimit sections and subgenera. We have performed phylogenetic analyses of Corydalis and related taxa, using 65 shared protein-coding plastid genes from 313 accessions (including 280 samples of ca. 226 species of Corydalis) and 152 universal low-copy nuclear genes from 296 accessions (including 271 samples of Corydalis) covering all 42 previously recognized sections and five independent “series”. Phylogenetic trees were inferred using Bayesian Inference and Maximum Likelihood. Eight selected morphological characters were estimated using ancestral state reconstructions. Results include: (i) of the three subgenera of Corydalis, two are fully supported by both the plastid and nuclear data; the third, subg. Cremnocapnos, is weakly supported by plastid DNA only, whereas in the nuclear data the two included sections form successive outgroups to the rest of the genus; (ii) among all 42 sections and five “series”, 25 sections and one “series” are resolved as monophyletic in both data sets; (iii) the common ancestor of Corydalis is likely to be a perennial plant with a taproot, yellow flowers with a short saccate spur, linear fruits with recurved fruiting pedicels, and seeds with elaiosomes; (iv) we provide a new classification of Corydalis with four subgenera (of which subg. Bipapillatae is here newly described), 39 sections, 16 of which are consistent with the previous classification, 16 sections have been recircumscribed, one section has been reinstated and six new sections are established. Characters associated with lifespan, underground structures, floral spur, fruit and elaiosomes are important for the recognition of subgenera and sections. These new phylogenetic analyses combined with ancestral character reconstructions uncovered previously unrecognized relationships, and greatly improved our understanding of the evolution of the genus.