Allergic contact dermatitis: epidemiology, molecular mechanisms, in vitro methods and regulatory aspects

Contact allergies are complex diseases, and one of the important challenges for public health and immunology. The German 'Federal Institute for Risk Assessment' hosted an 'International Workshop on Contact Dermatitis'. The scope of the workshop was to discuss new discoveries and developments in the field of contact dermatitis. This included the epidemiology and molecular biology of contact allergy, as well as the development of new in vitro methods. Furthermore, it considered regulatory aspects aiming to reduce exposure to contact sensitisers. An estimated 15-20% of the general population suffers from contact allergy. Workplace exposure, age, sex, use of consumer products and genetic predispositions were identified as the most important risk factors. Research highlights included: advances in understanding of immune responses to contact sensitisers, the importance of autoxidation or enzyme-mediated oxidation for the activation of chemicals, the mechanisms through which hapten-protein conjugates are formed and the development of novel in vitro strategies for the identification of skin-sensitising chemicals. Dendritic cell cultures and structure-activity relationships are being developed to identify potential contact allergens. However, the local lymph node assay (LLNA) presently remains the validated method of choice for hazard identification and characterisation. At the workshop the use of the LLNA for regulatory purposes and for quantitative risk assessment was also discussed.     

Cryptogamic soil crusts: recovery from grazing near Camp Floyd State Park, Utah, USA

The effects of grazing on the cryptogamic and vascular plant communities at two sites near Camp Floyd State Park, Utah County, Utah, were studied. The grazed site was subject to heavy grazing up until seven years prior to the study. The ungrazed site within the park boundaries had been protected from grazing for 20 years prior to the study and had a well-developed algal-lichen-moss crust. We found that the algae of the grazed site had recovered in terms of degree of crusting. There were no significant differences in the algal communities of the two sites when prevalent species were used as blocks in the ANOVAR analysis. However, when major algal groups were used as blocks, the analysis was significant, with the more recently grazed site having lower algal frequency. This difference, together with a few compositional differences, indicates that, although the algal community seven years following grazing is very similar to the algal community free of grazing for 20 years, the seven-year site is still in the process of recovery and community development. The diatom collections had a higher density in the grazed site, though the difference was not significant. Recovery of the lichen and moss community was not complete. The lichen Collema tenax and the mosses Bryum pallescens and Tortula ruralis were all significantly more abundant in the ungrazed area. Total cover of the lichen and moss components of the soil crusts was significantly lower in the more recently grazed area. Vascular cover was also lower.     

Nautilus pompilius: Branchial circulation enhanced by an auxiliary pumping mechanism

Summary Blood pressure recordings from the vena cava, afferent branchial and efferent branchial veins inNautilus showed that a significant increase in pressure of the gill circulation was achieved by the rhythmic contractions of the renal appendages and pericardial glands.We thank the Wilson Vailoces family and the other kind people of Bindoy, Negros Oriental, The Philippines for their unlimited generosity. This research was supported by NSF grant OCE 74-02888 to the Scripps Institution of Oceanography and BMS 75-01149 to Iowa State University, J. R. Redmond, principal investigator.     

Effect of soil microtopography on seed bank distribution in the shrub-steppe

The relationship between soil surface cryptogamic crusts and seed banks was investigated in the shrubsteppe in the Lower Columbia Basin. Seventy-four percent of the seeds in a disturbed bunchgrass community were found in crevices bordering cryptogamic crust polygons. In a sagebrush/bunchgrass community, 89% of the seeds were found in crevices. In a disturbed bunchgrass community, Bromus tectorum seeds were found in both the seed bank and aboveground vegetation communities. Bromus tectorum seeds were located in the seed bank of a sagebrush/bunchgrass community, although it had a minor presence in the aboveground community. Seeds of Artemisia tridentata Nutt. were not found in either the bunchgrass or sagebrush/bunchgrass communities. The high number of seeds found in crevices bordering the cryptogamic crust suggests that crevices play a role in determining the small-scale distributional pattern of shrub-steppe plants at the Fitzner-Eberhardt Arid Lands Ecology Reserve.     

The genome sequence of Atlantic cod reveals a unique immune system

Atlantic cod (Gadus morhua) is a large, cold-adapted teleost that sustains long-standing commercial fisheries and incipient aquaculture. Here we present the genome sequence of Atlantic cod, showing evidence for complex thermal adaptations in its haemoglobin gene cluster and an unusual immune architecture compared to other sequenced vertebrates. The genome assembly was obtained exclusively by 454 sequencing of shotgun and paired-end libraries, and automated annotation identified 22,154 genes. The major histocompatibility complex (MHC)?II is a conserved feature of the adaptive immune system of jawed vertebrates, but we show that Atlantic cod has lost the genes for MHC?II, CD4 and invariant chain (Ii) that are essential for the function of this pathway. Nevertheless, Atlantic cod is not exceptionally susceptible to disease under natural conditions. We find a highly expanded number of MHC?I genes and a unique composition of its Toll-like receptor (TLR) families. This indicates how the Atlantic cod immune system has evolved compensatory mechanisms in both adaptive and innate immunity in the absence of MHC?II. These observations affect fundamental assumptions about the evolution of the adaptive immune system and its components in vertebrates.     

Spatial patterns of plant communities and differential weathering in Navajo National Monument, Arizona

Vegetation patterns in Navajo National Monument, Arizona, were studied over a five-year period from 1977 to 1981. Twelve distinct plant community types occur within the boundaries of the park. These communities are characterized and the dominant plant species of each are recorded. The relationships of parent material, soils, and moisture to plant communities are also discussed. It appears that discrete communities occupy soils of different characteristics, particularly with respect to amount of weathering of parent material.         

Morphological variability and cell wall composition of Phaeodactylum tricornutum (Bacillariophyceae)

Five isolates of Phaeodactylum tricornutum Bohlin were examined in light and transmission electron microscopes. Although isolated from widely separated sites including both coastal marine and inland saline habitats, the morphology of the siliceous frustules of all isolates was very constant. The fusiform and triradiate forms, which have been reported as being non-siliceous in the past, were found to have an amorphous particulate nature in TEM. These forms were examined using EDAX SEM elemental analysis and were found to contain silica in their cell walls.     

Microbial spatial heterogeneity in microbiotic crusts in Colorado National Monument. II Bacteria

Microbial spatial heterogeneity and bacterial composition of homogeneous surface soils showing evident microbiotic crust development located under Utah juniper canopies in Colorado National Monument were studied. Four distinct homogeneous sampling sites positioned along a 12-m transect were compared on the basis of bacterial density and taxa composition. Bacterial densities showed a range differing by several orders of magnitude. In comparisons of adjacent soil samples or samples taken from two different sampling sites within close proximity, adjacent samples showed no more similarity to each other on the basis of bacterial density or taxa composition than did more widely separated samples. The bacterial composition of these soils included members of the genera Bacillus , Micrococcus , and Arthrobacter . Actinomycetes were also prevalent.