Respiration and parturition affected by conditional overexpression of the Ca2+-activated K+ channel subunit, SK3

In excitable cells, small-conductance Ca2+-activated potassium channels (SK channels) are responsible for the slow after-hyperpolarization that often follows an action potential. Three SK channel subunits have been molecularly characterized. The SK3 gene was targeted by homologous recombination for the insertion of a gene switch that permitted experimental regulation of SK3 expression while retaining normal SK3 promoter function. An absence of SK3 did not present overt phenotypic consequences. However, SK3 overexpression induced abnormal respiratory responses to hypoxia and compromised parturition. Both conditions were corrected by silencing the gene. The results implicate SK3 channels as potential therapeutic targets for disorders such as sleep apnea or sudden infant death syndrome and for regulating uterine contractions during labor.     

Assessment of the bacteriological quality of rural groundwater supplies in Northern West Virginia

A bacteriological survey was performed on 155 untreated, individual, rural groundwater supplies which included drilled wells, dug wells, and springs. Of these, 105 exceeded the Environmental Protection Agency (EPA) maximum contaminant level of one total coliform per 100 mL. Repeat sampling for 87 of the unacceptable 105 supplies indicated that 76 again exceeded the EPA standard limit. Masked coliforms were detected through confirmation tests in 11 water supplies that exhibited excessive noncoliform colonies (> 50 CFUs/membrane filter). Also, 48% of the supplies contained fecal coliforms and 62% contained fecal streptococci. Bacterial densities were related to the type of water supply with drilled wells containing fewer total coliforms, fecal coliforms, fecal streptococci, and heterotrophic plate count bacteria than dug wells or springs. Water supplies that were shallower, older, and lacking adequate casing characteristically were more heavily contaminated with sanitary indicator bacteria than supplies that were deeper, of more recent construction, and with sufficient casing.     

Treatment of Domestic Wastewater by Three Plant Species in Constructed Wetlands

Three common Appalachian plant species (Juncus effusus L., Scirpus validus L., and Typha latifolia L.) were planted into small-scale constructed wetlands receivingprimary treated wastewater. The experimental design includedtwo wetland gravel depths (45 and 60 cm) and five plantingtreatments (each species in monoculture, an equal mixture of the three species, and controls without vegetation), with two replicates per depth × planting combination. Inflow rates (19 L day^-1) and frequency (3 times day^-1) were designed to simulate full-scale constructed wetlands as currently used for domestic wastewater treatmentin West Virginia. Influent wastewater and the effluent from each wetland were sampled monthly for ten physical, chemical and biological parameters, and plant demographic measurements were made. After passing through these trough wetlands, the average of all treatments showed a 70% reduction in total suspended solids (TSS) and biochemical oxygen demand (BOD), 50 to 60% reduction in nitrogen (TKN), ammonia and phosphate, anda reduction of fecal coliforms by three orders of magnitude. Depth of gravel (45 or 60 cm) had little effect on wetland treatment ability, but did influence Typha and Scirpus growth patterns. Gravel alone provided significant wastewater treatment, but vegetation further improved many treatment efficiencies. Typha significantly out-performedJuncus and Scirpus both in growth and in effluent quality improvement. There was also some evidence that the species mixture out-performed species monocultures.Typhawas the superior competitor in mixtures, but a decline in Typha growth with distance from the influent pipe suggested that nutrients became limiting or toxicities may have developed.     

Developing equations to estimate potato yield loss caused by early blight in Minnesota

Regression analyses were performed on field data from 1981 and 1982 to determine models for estimating yield loss caused by early blight in potato cvs. Norland and Russet Burbank. Percent yield loss (total tubers and US# 1 tubers) caused by early blight could not be satisfactorily explained by any regression model using only a single disease assessment as the input variable. Several multiple point models, which explained more than 70% of the variation in yield loss due to early blight, were determined for each cultivar. The models for cv. Norland used either early blight severity assessments on days 56, 66, 76 and 86 after sprout emergence, or blight severity increments for 10-day periods among days 46–86, as the input variables. The models for cv. Russet Burbank used the same input variables as for cv. Norland and additionally, blight severity on day 96. Yield loss in US#1 tubers was a more stable variable than loss in total tubers for estimating early blight effect.     

Administration of probiotics influences F4 (K88)-positive enterotoxigenic Escherichia coli attachment and intestinal cytokine expression in weaned pigs

ABSTRACT: This study evaluated the effect of the probiotics Pediococcus acidilactici and Saccharomyces cerevisiae boulardii on the intestinal colonization of O149 enterotoxigenic Escherichia coli harbouring the F4 (K88) fimbriae (ETEC F4) and on the expression of ileal cytokines in weaned pigs. At birth, different litters of pigs were randomly assigned to one of the following treatments: 1) control without antibiotics or probiotics (CTRL); 2) reference group in which chlortetracycline and tiamulin were added to weanling feed (ATB); 3) P. acidilactici; 4) S. cerevisiae boulardii; or 5) P. acidilactici + S. cerevisiae boulardii. Probiotics were administered daily (1 × 109 CFU per pig) during the lactation period and after weaning (day 21). At 28 days of age, all pigs were orally challenged with an ETEC F4 strain, and a necropsy was performed 24 h later. Intestinal segments were collected to evaluate bacterial colonization in the small intestine and ileal cytokine expressions. Attachment of ETEC F4 to the intestinal mucosa was significantly reduced in pigs treated with P. acidilactici or S. cerevisiae boulardii in comparison with the ATB group (P = 0.01 and P = 0.03, respectively). In addition, proinflammatory cytokines, such as IL-6, were upregulated in ETEC F4 challenged pigs treated with P. acidilactici alone or in combination with S. cerevisiae boulardii compared with the CTRL group. In conclusion, the administration of P. acidilactici or S. cerevisiae boulardii was effective in reducing ETEC F4 attachment to the ileal mucosa, whereas the presence of P. acidilactici was required to modulate the expression of intestinal inflammatory cytokines in pigs challenged with ETEC F4.     

Ammonia volatilization following surface application of urea to tilled and no-till soils: A laboratory comparison

Broadcasting of urea to agricultural soils can result in considerable losses by NH₃ volatilization. However, it is unclear if the impact of this practice on NH₃ emissions is further enhanced when performed on no-till (NT) soils. The objective of this study was to compare NH₃ volatilization following broadcasting of urea to NT and moldboard plowed (MP) soils. Intact soil cores were taken shortly after harvest from NT and MP plots of three long-term tillage experiments in Québec (Canada) and stored for 4.5 months prior to incubation. Urea (14 g N m⁻²) was applied at the soil surface and NH₃ volatilization was measured for 30 d using an open incubation system. Mean cumulative NH₃ losses were greater (P < 0.001) in NT (3.00 g N m⁻²) than in MP (0.52 g N m⁻²). Several factors may have contributed to the higher emissions from the NT soils. Urease activity in the top 1 cm of soils was on average 4.2 times higher in NT than in MP soils. As a result, hydrolysis of urea occurred very rapidly in NT soils as indicated by enhanced NH₃ emissions 4 h after application of urea. The presence of crop residues at the surface of NT soils also decreased contact of the urea granules with the soil, possibly reducing adsorption of NH₄⁺ on soil particles. Lower volatilization on the MP soils may also have partly resulted from a fraction of urea granules falling into shallow cracks. Field trials are needed to confirm our finding that NT soils bear greater potential for NH₃ volatilization following surface application of urea than MP soils.