Differential Susceptibility of Human Peripheral Blood T Cells to Suppression by Environmental Levels of Sodium Arsenite and Monomethylarsonous Acid

Human exposure to arsenic in drinking water is known to contribute to many different health outcomes such as cancer, diabetes, and cardiopulmonary disease. Several epidemiological studies suggest that T cell function is also altered by drinking water arsenic exposure. However, it is unclear how individual responses differ to various levels of exposure to arsenic. Our laboratory has recently identified differential responses of human peripheral blood mononuclear cell (HPMBC) T cells as measured by polyclonal T cell activation by mitogens during sodium arsenite exposure. T cells from certain healthy individuals exposed to various concentrations (1–100 nM) of arsenite in vitro showed a dose-dependent suppression at these extremely low concentrations (∼0.1–10 ppb) of arsenite, whereas other individuals were not suppressed at low concentrations. In a series of more than 30 normal donors, two individuals were found to be sensitive to low concentration (10 nM equivalent ∼1 ppb drinking water exposure) to sodium arsenite-induced inhibition of T cell proliferation produced by phytohemagglutinin (PHA) and anti-CD3/anti-CD28. In an arsenite-susceptible individual, arsenite suppressed the activation of Th1 (Tbet) cells, and decreased the percentage of cells in the double positive Th17 (RORγt) and Treg (FoxP3) population. While the majority of normal blood donors tested were not susceptible to inhibition of proliferation at the 1–100 nM concentrations of As⁺³, it was found that all donors were sensitive to suppression by 100 nM monomethylarsonous acid (MMA⁺³), a key metabolite of arsenite. Thus, our studies demonstrate for the first time that low ppb-equivalent concentrations of As⁺³ are immunosuppressive to HPBMC T cells in some individuals, but that most donor HPBMC are sensitive to suppression by MMA⁺³ at environmentally relevant exposure levels.     

Effect of variety and location on growth and yield components of Roselle,HIbiscus sabdariffa L. and its infestation with the spiny bollworm Earias insulana (BOISD.)

Three roselle, Hibiscus sabdariffa L. varieties (Sudani, Masri and White) were cultivated at three different locations to recognize the transportation ability of roselle cultivation from the narrow old valley land to broad new land in Egypt. Qena as origin in situ old land, El-Kanater as ex situ old land and Nubaria as ex situ new land were the considered locations. Six growth quantitative characters and bolls infestation by spiny bollworm, Earias insulana were evaluated. Growth characters of roselle plants were affected significantly by either variety or location. Qena region was more suitable for roselle plant growth as judged with plant height, number of branches, number of fruits and sepals dry weight, followed by Nubaria followed by El-Kanater. Whereas, plants grown at Nubaria produced more fresh sepals weight than Qena or El-Kanater grown plants. As for Sudani, Nubaria exhibited the tallest plants, with the highest number of fruits and the heaviest fresh sepals as compared with the corresponding plants in Qena or El-Kanater. Values of broad sense heritability were highest for all characters in Qena. While the number of fruits per plant had the highest heritability in all locations. Dry sepals yield had highly significant correlation with all studied characters except percentage of water loss in Qena and Nubaria. Path coefficient analysis confirmed that fresh sepals yield had the highest direct and indirect effects on dried sepals yield. Chemical constituents responsible to sepal quality tended to produce significant variations due to the changes in varieties or locations. The highest levels of anthocyanins and sugars were achieved by Sudani variety, but the highest levels of free amino acids and total soluble solids were recorded for Masri variety. Moreover, Nubaria region was the most favourable for the accumulation of more anthocyanins in the sepals of all varieties followed by Qena. Plants grown at Qena produced sepals with the highest levels of sugars, free amino acids, organic acids and total soluble solids, followed by Nubaria followed by El-Kanater plants. Infestation with spiny bollworm Earias insulana was increased from Sudani up to Masri up to White varieties. Plants grown at Nubaria had the lowest number of attacks by bolls in all varieties, followed by those at El-Kanater followed by Qena plants. Spiny bollworm infestation was positively correlated with the number of branches and dry sepals weight, but negatively correlated with sepal moisture loss and anthocyanin contents. These findings clearly indicated that the Nubaria region was considered as a promising reclaimed area suitable for roselle cultivation, especially for Sudani, the most economic variety.     

Supramolecular Organization of the α121-α565 Collagen IV Network

Collagen IV is a family of 6 chains (α1-α6), that form triple-helical protomers that assemble into supramolecular networks. Two distinct networks with chain compositions of α121 and α345 have been established. These oligomerize into separate α121 and α345 networks by a homotypic interaction through their trimeric noncollagenous (NC1) domains, forming α121 and α345 NC1 hexamers, respectively. These are stabilized by novel sulfilimine (SN) cross-links, a covalent cross-link that forms between Met⁹³ and Hyl²¹¹ at the trimer-trimer interface. A third network with a composition of α1256 has been proposed, but its supramolecular organization has not been established. In this study we investigated the supramolecular organization of this network by determining the chain identity of sulfilimine-cross-linked NC1 domains derived from the α1256 NC1 hexamer. High resolution mass spectrometry analyses of peptides revealed that sulfilimine bonds specifically cross-link α1 to α5 and α2 to α6 NC1 domains, thus providing the spatial orientation between interacting α121 and α565 trimers. Using this information, we constructed a three-dimensional homology model in which the α565 trimer shows a good chemical and structural complementarity to the α121 trimer. Our studies provide the first chemical evidence for an α565 protomer and its heterotypic interaction with the α121 protomer. Moreover, our findings, in conjunction with our previous studies, establish that the six collagen IV chains are organized into three canonical protomers α121, α345, and α565 forming three distinct networks: α121, α345, and α121-α565, each of which is stabilized by sulfilimine bonds between their C-terminal NC1 domains.     

Modeling and dynamic simulation of a two-stage pre-denitrification MBBR system under increasing organic loading rates

Bioprocess and Biosystems Engineering - Biofilm-based wastewater treatment systems have become attractive due to their numerous advantages when compared to other suspended growth processes....     

Conceptual Issues and Methodology in Kin-recognition Research: A Critical Discussion

We operationally define kin-recognition and discuss methodological and conceptual issues that arise in its study, citing examples from the literature that illustrate particular points. We define and examine three components of kin-recognition (expression, perception, and action), and discuss why some experimental designs fail to distinguish among the components. We also point out ways that experimental designs might be modified to unlink the components. We discuss three general issues central to assays of kin-recognition: the functional significance of assays, multiple- and single-behavior assays, and potential biases in assays. The potential biases we consider are nonblind behavioral assays and the pooling of dependent data. We also examine negative results and, in particular, those factors that can produce negative results when recognition ability is present. Finally, we discuss kin-recognition in natural contexts, emphasizing the potential dangers of uncritically extrapolating the results of laboratory studies to field contexts.     

Territorial status and survival in red grouse Lagopus lagopus scoticus: hope for the doomed surplus?

A previous study of survival in territorial and non-territorial red grouse Lagopus lagopus scoticus conducted between 1957 and 1967 found that territorial status in the autumn pre-determined over-winter survival. A very high proportion of territorial birds survived and virtually all non-territorial birds died or emigrated. We tested the hypothesis that over-winter survival was dependent on territorial status within four grouse populations in Scotland between 1986 and 1993. In contrast to the previous study, 66% of non-territorial birds survived over winter compared to approximately 70% of territorial birds. There was no significant effect of territorial status on the survival estimates. Moreover, some of the birds considered to be non-territorial during autumn went on to successfully raise a brood. We suggest that on our study sites, territory ownership in autumn did not greatly influence over-winter survival, and territorial behaviour did not determine breeding density as previously supposed. We postulate differences with other studies may reflect variations in scale and predation pressure.     

ECOTYPIC DIVERGENCE IN ALPINE POLEMONIUM VISCOSUM: GENETIC STRUCTURE,QUANTITATIVE VARIATION,AND LOCAL ADAPTATION

Polemonium viscosum has a continuous distribution from 3,500 m in the krummholz to 4,025 m on the summit ridges of Pennsylvania Mountain, Colorado. Seeds produced by plants at opposite ends of this cline, 1.5 km apart, differed significantly at allozyme loci in two consecutive breeding seasons. Mean multilocus F_st values for both years (0.015 and 0.069) were significantly different from zero, indicating restricted gene exchange between subpopulations. Average allele frequencies at two individual loci also differed significantly between families comprising krummholz and summit subpopulations. Progeny of plants growing on the summit had higher leaf production rates, more densely packed leaflets, and lower resistance to aphids than progeny of plants growing in the krummholz site, when tested under greenhouse conditions. These differences probably reflect the restricted opportunities for growth and severe exposure at high elevations, and the increased risk from herbivores near timberline. The two subpopulations did not differ in leaf length (stature), leaf width, or pubescence. Reciprocal transplanting of seedlings between krummholz and summit sites confirmed that the differences were adaptive, since progeny from each subpopulation performed significantly better in their parent's habitat. Coordinated studies of genetic structure, quantitative variation, and local adaptation across the elevational range of P. viscosum provide a comprehensive view of ecotypic divergence in this widespread alpine plant.