Investigation of ovicell hyperplasia in bryozoans chronically exposed to natural oil seepage

Systemic collection and examination of bryozoans from surface, subsurface and benthic kelp fronds in an area chronically exposed to natural oil seepage revealed no instances of ovicell hyperplasia. Reasons are presented to explain the contrast between these findings and reported ovicell hyperplasia in other species exposed to creosote and petroleum hydrocarbons.     

Crop and soil response to subsoil loosening, deep incorporation of phosphorus and potassium fertilizer and subsequent soil management on a range of soil types.: Part 2: Soil structural conditions

Abstract. In a series of experiments on 16 sites both a power-driven rotary-tine Wye Double Digger and a rigid tine winged subsoiler produced significant subsoil loosening and fissuring. The Double Digger consistently produced the greatest clod breakdown together with the least soil bulk densities and cone penetration resistances. Management strategies after loosening had an important influence on the longevity of the loosening effect. The rate of recompaction was least with controlled traffic and bed systems and increased with random traffic and with the growing of root crops. No significant differences in crop response were monitored between the two loosening treatments, yield response depending largely on the extent of moisture stress experienced by the crop. Loosening on silty soils reduced yields in wet seasons and this was associated with soil structural instability. Visual soil profile examination is necessary to support bulk density and cone penetration resistance measurements when assessing soil compaction.     

Impact of coal combustion waste on the microbiology of a model aquifer

The effects of water infiltration into an alkaline coal combustion waste burial site on the chemical and microbiological aspects of a meso-scale (2.44 m diameter × 4.6 m, height, 65 tonne) model aquifer were analyzed. The spatial and temporal effects of the alkaline leachate on microbial activity, numbers and diversity were examined in the model and compared with uncontaminated control materials. Within the saturated zone below the waste there was a pH gradient from 12.4 at the water table, immediately below the waste, to 6.0 at 3.5 meters from the waste, and elevated levels of arsenic and strontium in the pore waters. Microtox testing of the contaminated pore waters indicated high toxicity (a gamma value of 1 at dilutions of 45 to 110 fold). The leachate contamination was associated with a reduction in bacterial [³H] leucine incorporation from a high of 267 fmol g^?1 h^?1 in sediments below the contaminant plume to undetectable in the contaminated zone. In comparison, leucine incorporation rates in control column sediments were 899 fmol g^?1 h^?1. Similar toxic effects were evident in reduced total direct and culturable counts of bacteria. Observations also indicated a reduction in microbial diversity and development of alkaline-tolerant microbial communities. These results indicated that any failure of confinement technologies at disposal sites would adversely affect both the chemistry and microbiology of the underlying saturated zone.     

Response of two western Canadian conifers to simulated acidic precipitation

Ready-to-plant nursery stock of jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) were subjected to simulated acid rains of pH 5.6 (control), 4.6, 3.6, and 2.6 under controlled growth room conditions to determine the threshold for damage. The two species exhibited contrasting response patterns to simulated acid rain treatments. Growth and chlorophyll content of jack pine were not adversely affected at any of the levels applied. Furthermore, no macroscopic foliar injury symptoms were evident and foliar nutrient levels remained unaffected. White spruce showed no statistically significant reduction in growth rate at any of the treatments. Needle chlorophyll a content of white spruce was not affected by any of the treatments, while chlorophyll b level was significantly reduced at pH 2.6. Symptoms of visible injury were observed to increase with rain acidity. No statistically significant change in the levels of foliar nutrients of white spruce were found, with the exception of the elevated S concentration at pH 2.6.     

Two molecular transitions influence cardiac sodium channel gating

Sodium channels from diverse excitable membranes are very similar in their structure, yet surprisingly heterogeneous in their behavior. The processes that govern the opening and closing of sodium channels have appeared difficult to describe in terms of a single, unifying molecular scheme. Now cardiac sodium channels have been analyzed by high-resolution single-channel recordings over a broad range of potentials. Channels exhibited both complex and simple gating patterns at different voltages. Such behavioral diversity can be explained by the balance between two molecular transitions whereby channels can exit the open state.     

Lymphocyte stimulation: transfer of cellular hypersensitivity to antigen in vitro

Tuberculin-sensitive human lymphocytes cultured for 36 hours with tuberculin elaborate a soluble material which causes nonsensitive lymphocytes to respond to tuberculin in vitro by transformation and proliferation.