Smoke and pollution aerosol effect on cloud cover

Pollution and smoke aerosols can increase or decrease the cloud cover. This duality in the effects of aerosols forms one of the largest uncertainties in climate research. Using solar measurements from Aerosol Robotic Network sites around the globe, we show an increase in cloud cover with an increase in the aerosol column concentration and an inverse dependence on the aerosol absorption of sunlight. The emerging rule appears to be independent of geographical location or aerosol type, thus increasing our confidence in the understanding of these aerosol effects on the clouds and climate. Preliminary estimates suggest an increase of 5% in cloud cover.     

Recurrent herpes in the rabbit and man

Herpesvirus was present in secretory glands and frequently in tears of rabbits with recurrent herpetic keratitis even in the absence of corneal lesions. In normal people, herpesvirus could be cultured from saliva and tears. Chronic virus multiplication in structures such as the lacrimal and salivary glands, rather than latency, may cause recurrent herpetic disease.     

Enzyme activity in soils showing enhanced degradation of organophosphate insecticides

Summary Studies were conducted to determine whether soils that showed enhanced biodegradation of organophosphate insecticides had significantly different enzyme activities from those in the same soils with no previous exposure to the insecticides. Twenty-one pairs of soils were collected from farms in the Midwest where chlorpyrifos, terbufos, fonofos, or phorate had failed to protect corn (Zea mays L) from corn rootworm (Diabrotica sp). Each soil was analyzed for acid and alkaline phosphatase, phosphodiesterase, phosphotriesterase, and dehydrogenase activities. Over 40% of the insecticide-treated soils had higher acid phosphatase activity than the fence row soils which had no previous exposure to the insecticide. Over twothirds of the soils treated with fonofos had higher acid phosphatase and phosphotriesterase activity than the fence row soils. If these enzymes are not directly involved in the biodegradation of the insecticitde, they may be indicative of enhanced biodegradation and may be used to predict which soils may be prone to insecticide failure.Contribution from the Soil-Microbial Systems Laboratory, Natural Resources Institute, USDA-ARS, Beltsville, MD 20705, USA     

An Empirical Model for Estimating Remediation Costs at Contaminated Sites

A model for estimating the remediation costs at contaminated sites is developed, in which the predictor variable is a composite of surface, subsurface, and contaminant risk factors. Calibration of the model is performed at 83 sites in an urbanized watershed with diverse surface geology in southeastern Michigan. These test sites exhibited different extents of contamination, including some where only soil was contaminated, and others where soil and groundwater were contaminated. The model was then applied to 79 sites with multiple contamination extents within different watersheds in North America, Europe, Australia, and Africa. The results indicate a very high correlation between the estimated and actual remediation costs at these sites. This model thus has the potential for providing reliable estimates of remediation costs across a broad array of soil and groundwater contamination scenarios, including dense nonaqueous phase liquid (DNAPL) contamination in sandy soil and lead in clay soil.     

RNA metabolism in tracheal epithelium: alteration in hamsters deficient in vitamin A

The electrophoretic pattern of RNA molecules that are synthesized in vitro in tracheal epithelium from hamsters deficient in vitamin A differs from that of RNA synthesized in normal, pair-fed control hamsters. There is less RNA of low electrophoretic mobility in the epithelial cells deficient in vitamin A. This alteration is reversed after the deficient animals have been treated with vitamin A.     

家禽体外寄生虫的控制

编者按:虱子、恙虫、家禽壁虱和鸡蚤是家禽业中常见的体外寄生虫.虽然禽舍苍蝇不是寄生虫,但是备受家禽生产者的关注,尤其对于笼养蛋鸡生产者.这些体外寄生虫对家禽业的危害日益得到重视.本专题就上述几种体外寄生虫的生活习性和药物控制措施进行总结,希望为广大读者提供借鉴.     

Improvement of the Culture Conditions for In Vitro Production of Cattle Embryos in a Portable CO2 Incubator

The effects of different concentrations of growth hormone (GH) on in vitro maturation (IVM), fertilization (IVF) and culture (IVC) of bovine oocyte/embryos in CR1aa or CR2aa media using a simple CO₂ incubator were investigated. The IVM/IVF/IVC of oocytes were carried out in the presence of 0, 50, 100 and 200 ng/ml GH in the medium. The proportion of metaphase II oocytes was significantly higher (p < 0.05) in 200 ng/ml compared with 0 ng/ml GH in CR1aa medium (59 versus 85%, respectively), but this effect was not observed under CR2aa. Higher concentrations of GH yielded lower rates of unfertilized ova and thus superior cleavage rates (36.5 ± 0.2 and 63.5 ± 2.0% versus 17.5 ± 0.2 and 82.5 ± 1.5% or 40.4 ± 0.6 and 59.6 ± 1.4% versus 16.6 ± 1.2 and 83.4 ± 6.2% for 0 and 200 ng/ml GH in portable or ordinary incubator, respectively) in CR1aa. This dose‐dependent effect was also observed in the percentages of transferable embryos, although not statistically different (17.2 ± 1.7 versus 27.3 ± 1.8% and 16.6 ± 3.1 versus 26.0 ± 1.4%, for 0 versus 200 ng/ml GH in portable and ordinary incubator, respectively). In contrast to the CR1aa, different concentrations of GH in CR2aa medium did not increase either fertilization or cleavage rates. In fact, higher concentrations of GH in this medium negatively affected the rate of transferable embryos. Hence, percentages of transferable embryos obtained in the portable incubator under 0 or 50 ng/ml GH were higher (p < 0.05) compared with those obtained in 100 or 200 ng/ml GH (35.4 ± 5.7 or 40.5 ± 5.4% versus 22.4 ± 2.4 or 15.5 ± 2.1%, respectively). There was however, no significant difference in the rate of transferable embryos in an ordinary incubator employing CR2aa medium, but the trend was more or less similar to that observed in the portable incubator. Despite the fact that relatively fewer oocytes were employed for the culture in the ordinary incubator, overall results observed employing the simple portable CO₂ incubator were within the range of those obtained in an ordinary incubator; implying that the simple portable incubator can effectively be employed for the in vitro production of bovine embryos under field conditions.