Production of an epidermal growth factor receptor-related protein

Human epidermoid carcinoma A431 cells in culture produce a soluble 105-kilodalton protein which, by the criteria of epidermal growth factor (EGF) binding, recognition by monoclonal and polyclonal antibodies to the EGF receptor, amino-terminal sequence analysis and carbohydrate content, is related to the cell surface domain of the EGF receptor. The high rate of production and the finding that with biosynthetic labeling the specific activity of this 105-kilodalton protein exceeds that of the intact receptor indicate that it is not derived from membrane-bound mature receptor but is separately produced by the cell. These cells thus separately synthesize an EGF receptor that is inserted into the membrane and an EGF receptor-related protein that is secreted.     

Determination of mercury methylation rates using A 203-HG radiotracer technique

A radiotracer method for the determination of mercury (Hg) methylation rates in bulk water and water overlying intact sediment cores has been developed. A sediment core with overlying water is collected in a core tube, the overlying water is spiked with high specific activity 203-Hg radiotracer, and the core is incubated at ambient temperature. Aliquots of the overlying water are removed, the Hg is extracted from the sample, and the activity in the extract is measured. A 10–25 fold sample preconcentration is achieved using a dithizone-chloroform extraction technique and a sodium nitrite back extraction step to separate inorganic Hg(II) from monomethylmercury (MMHg). The use of this technique, in conjunction with high specific activity 203-Hg, has allowed for spiking concentrations in the overlying water of approximately 1 ng Hg/L. This spiking level is about the same concentration as the ambient water overlying the core, thus not significantly perturbing the system. Our technique is a significant improvement over previous methodologies which used 203-Hg spike additions of 1 μg Hg/L or higher. The technique was used to measure Hg methylation rates at the Experimental Lakes Area (ELA) in Ontario, Canada during August of 1993 and at an extensively studied estuarine site in Gulf Breeze, Florida, USA during September, 1993 and June, 1994. Multiple cores were collected and spiked with a range of 1 to 11,800 ng Hg (as 203-Hg) into the overlying water. MMHg production at the ELA site indicated rates of 0.25 to 3.7 pg/cm²/day (0.08 to 2.5 % methylation/day). Results from Gulf Breeze were significantly higher at 1.5 to 425 pg/cm²/day or 0.06 to 18 % methylation/day. These rates are one to three orders of magnitude greater than previously measured “specific rates” in bulk water samples and sediments. A direct comparison of rates with previous sediment methylation assay techniques is not possible, however, because of the significant differences between our methodology and previous assay protocols.     

Ostertagia ostertagi infection in the calf: effects of a trickle challenge on the hormonal control of digestive and metabolic function

Metabolic effects of a trickle challenge with the equivalent of 10,000 infective Ostertagia ostertagi larvae per day were investigated in 12 calves allocated to infected, pair-fed control or ad libitum-fed control groups. Changes in hormone levels reflecting abomasal, pituitary and pancreatic function were monitored using radioimmunoassay techniques previously validated for use in cattle. A range of metabolic profile parameters and blood metabolites was also measured. Feed intake of the infected calves began to decline as blood gastrin and pepsinogen levels reached a peak. The depression in appetite recorded in this group was responsible for significant increases in plasma urea and non-esterified fatty acid levels and associated with an increase in growth hormone/insulin ratio. No significant difference in glucagon levels was recorded between groups. A decline in blood albumin values was also shown in the infected group and associated with a drop in nitrogen digestibility. A significant depression in circulating calcium levels was related to either the hypoalbuminaemia or impaired mineral absorption in the intestine. A decrease in plasma cholesterol values in the infected group was associated with changes in digestive function.     

Agroforestry practices of non-industrial private forest landowners in Washington State

A mail survey was conducted to gain understanding of the agroforestry practices of non-industrial private forest landowners (NIPF) in Washington State, located in the north-western USA. Although NIPF owners control 1.5 million hectares of the state's commercial forestland base, their diversity of forestland uses, land management practices and objectives as land managers are not well understood. Past NIPF surveys and anecdotal information suggest agroforestry is a major use of NIPF lands. We defined agroforestry as a potentially sustainable land use practice combining the deliberate growing of woody perennials with agricultural crops and/or animals. Objectives of this study were to:

1. determine the extent that agroforestry is used by Washington's NIPF owners,
2. develop insight into NIPF owners' motivations for practicing agroforestry,
3. describe the agroforestry practices within three distinct physiographic and agroecological zones in Washington, and
4. determine the agroforestry information needs of NIPF owners.

The target population consisted of NIPF owners in 4 counties within each of the three regions. Response to the August 1990 mail survey was 63.5%, yielding 296 useable questionnaires. Fifty-seven percent of all respondents practice agroforestry. Forestland grazing is the most common agroforestry practice (39% of all respondents), followed by windbreaks (34%), harvest of special forest products (12%), livestock enrichment plantings for forage or shelter (7%), orchard grazing (5%), orchard intercropping (2%), and Christmas tree grazing (0.34%). The most frequent motives for owning land were passing land on to children (80%), keeping it natural and income from timber (both 72%). Respondents saw aesthetics (77%), increasing land unit income (74%), and water conservation (70%) as possible advantages of practicing agroforestry. High establishment costs (66%) and livestock damage to trees or crops (64%) were the most frequently selected potential disadvantages to practicing agroforestry. Lack of technical and educational support (67%) and lack of access to livestock/livestock facilities (58%) were disincentives to practicing agroforestry. Landowners are interested in learning more about agroforestry and how agroforestry techniques might be incorporated in their land management tool kit. A significant number of non-industrial private forest land owners in Washington believe that management of forestland, balancing conservation and production goals, can be furthered by suitable agroforestry practices.     

Response of sorghum to moisture stress using line source sprinkler irrigation I. Plant-water relations

The response of sorghum (Sorghum bicolor L.) to moisture stress during the post-rainy season was studied at ICRISAT research center on a medium deep Alfisol using a line source sprinkler irrigation system. Changes in soil moisture content, stomatal conductance, leaf-water potential and leaf temperature of sorghum as a function of distance away from the line source sprinkler system were monitored throughout the season. Use of the line source technique facilitated the imposition of a range of moisture stress levels as indicated by increased water use by sorghum closer to the line source compared with the crop farther away from the line source. Canopy response measured in terms of stomatal conductance, leaf-water potential, and leaf temperature clearly reflected the gradient in moisture stress perpendicular to the line source.     

Polycystic kidney disease in goldfish (Cusrassius auratus)

Abstract Thirty percent of 60 goldfish in an outside pond showed progressive development of swollen abdomens and floatation problems. The occasional fish was found dead. Necropsy of an affected fish showed an abdomen almost filled with a large bilobed ventral mass comprised of masses of cysts filled with clear fluid. On histopathological examination, this mass appeared to be composed of large cystic spaces lined by a single flattened epithelium. Occasional remnants of normal kidney tissue were seen withen the mass.