Variation in tyrosine aminotrasferase induction in HTC cell clones

Examination of tyrosine aminotransferase induction in many HTC cell subclones revealed a wide and unstable distribution of inducibility. The instability of this phenotype cannot easily be explained by classical mutation rates. These observations may be important in interpreting certain cell fusion experiments.     

The little ice age as recorded in the stratigraphy of the tropical quelccaya ice cap

The analyses of two ice cores from a southern tropical ice cap provide a record of climatic conditions over 1000 years for a region where other proxy records are nearly absent. Annual variations in visible dust layers, oxygen isotopes, microparticle concentrations, conductivity, and identification of the historical (A.D. 1600) Huaynaputina ash permit accurate dating and time-scale verification. The fact that the Little Ice Age (about A.D. 1500 to 1900) stands out as a significant climatic event in the oxygen isotope and electrical conductivity records confirms the worldwide character of this event.     

Transovarial transmission of LaCrosse virus (California encephalitis group) in the mosquito, Aedes triseriatus

LaCrosse virus (California encephalitis group) was recovered from F(1) eggs, larvae, and adults produced by experimentally infected Aedes triseriatus. The F(1) females transmitted the virus by bite to suckling mice and chipmunks. This, plus isolations of LaCrosse virus from larvae collected from their natural habitats in enzootic areas and from males and females reared from them, suggests that transovarial transmission is the overwintering mechanism for this arbovirus in northern United States.     

Absence of binding and impermeability to ferritins of gill endothelium in marine teleosts

The surface binding characteristics and permeability properties of the endothelium of secondary lamellae from the gills of several species of marine teleosts were investigated by introducing cationized ferritin and native ferritin into the microcirculation under normal environmental conditions. Neither type of ferritin bound to the luminal surface of the gill endothelium. No transcellular movement of cationized ferritin was detected, either via transendothelial channels or individual vesicles, nor was passage of cationized ferritin through the tight intercellular junctions of the endothelium observed. Anionic binding sites in the endothelial basement membranes could not be identified. Binding and transport of ferritin were unaffected by normal changes in environmental temperatures over the range of -2 to + 15°C. These findings suggest that the endothelial cell surface of the gills from these fishes is a primary barrier to the extracapillary movement of blood borne constituents.     

Measuring responses of harbour seals to potential aversive acoustic mitigation signals using controlled exposure behavioural response studies

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Controlling the moisture absorption capacity in a fiber-reinforced thermoplastic starch using sodium trimetaphosphate

A novel biodegradable material derived from thermoplastic potato starch was prepared with intended uses in high moisture environments where its high water sorption characteristics are beneficial, such as wound dressing, transdermal patches or food packaging. A modified composite was prepared for this purpose by reactive extrusion whereby potato starch and 2.5-25% (w/w) sisal cellulose fibers were compounded together in the presence of 2.7% (w/w) sodium trimetaphosphate. The fibers were included to increase the wet strength of the material. A low degree of substitution (0.088-0.113) was sought by bound phosphate groups with anionic character in order to overcome a reduction in moisture absorption capacity resulting from fiber incorporation, yet being insufficient to cause embrittlement via crosslinking. The results showed the approach has sufficient merit to minimize the influence of the hydrophobic fibers on the water absorption capacity of the starch material but adhering to so low of a degree of substitution could not fully prevent a reduction. The results also suggested that the fibers may have participated in the crosslinking reaction.     

New Rangeland Residents in Wyoming? A Survey of Exurban Landowners

Rapid conversion of rural land to exurban development and the ensuing impacts on natural resources have been well-documented, but information about exurban landowners is lacking. To address this knowledge gap, we surveyed exurban landowners in six Wyoming counties and documented demographic characteristics, motivations, knowledge, and attitudes about natural resources and land management. The overall response rate was 55.6%. Generally, respondents were of retirement age, had lived in Wyoming for about 13 yr, and were raised in areas with a population < 10 000. Wyoming respondents lived in exurbia for the lifestyle and aesthetic values and did not expect economic gains from their property. Most respondents had knowledge about, and interest in, invasive species, water quality, landscaping, and gardening. More than half of respondents (54%) had never looked for information regarding land management. Information from this study can be used to strengthen the development and delivery of educational programs. Programs that focus on water quality or weed control likely will appeal to more exurban landowners than those that focus solely on grazing management. Our findings provide an accurate characterization of this audience and their motivations and attitudes regarding land management, and suggest that using a multipronged approach for outreach efforts, which includes both cost- and time-efficient ways to conduct important land management practices, might increase participation in educational programs.     

Effects of fescue toxicosis on reproduction in livestock.

Fescue toxicosis in livestock is due to ingestion of endophyte (Acremonium coenophialum) -infected tall fescue. Understanding mechanisms responsible for decreased calving and growth rates, delayed onset of puberty, and impaired function of corpora lutea in heifers at puberty consuming endophyte-infected fescue is an emerging field in reproductive toxicology. The condition decreases overall productivity through a reduction in reproductive efficiency, reduced weight gains, and lowered milk production. Reproduction in cattle may be further compromised by winter coat retention, increased susceptibility to high environmental temperatures, and light intolerance. Endocrine effects in steers associated with infected tall fescue include reduced prolactin and melatonin secretions and altered neurotransmitter metabolism in the hypothalamus, the pituitary, and pineal glands. Ewes have decreased prolactin and lengthened intervals from introduction of the ram until conception. The endophyte induces prolonged gestation, thickened placentas, large, weak foals, dystocia, and agalactia in pregnant mares. Ergot peptide alkaloids, produced by the endophyte, are suggested as the primary cause of fescue toxicosis. These compounds reduce prolactin, increase body temperatures, and have powerful vasoconstrictive effects. Neurohormonal imbalances of prolactin and melatonin, with restricted blood flow to internal organs, may be the principal causes of aberrant reproduction, growth, and maturation in livestock consuming endophyte-infected tall fescue.