July 2012 Greenland melt extent enhanced by low-level liquid clouds.

Melting of the world's major ice sheets can affect human and environmental conditions by contributing to sea-level rise. In July 2012, an historically rare period of extended surface melting was observed across almost the entire Greenland ice sheet, raising questions about the frequency and spatial extent of such events. Here we show that low-level clouds consisting of liquid water droplets ('liquid clouds'), via their radiative effects, played a key part in this melt event by increasing near-surface temperatures. We used a suite of surface-based observations, remote sensing data, and a surface energy-balance model. At the critical surface melt time, the clouds were optically thick enough and low enough to enhance the downwelling infrared flux at the surface. At the same time they were optically thin enough to allow sufficient solar radiation to penetrate through them and raise surface temperatures above the melting point. Outside this narrow range in cloud optical thickness, the radiative contribution to the surface energy budget would have been diminished, and the spatial extent of this melting event would have been smaller. We further show that these thin, low-level liquid clouds occur frequently, both over Greenland and across the Arctic, being present around 30-50 per cent of the time. Our results may help to explain the difficulties that global climate models have in simulating the Arctic surface energy budget, particularly as models tend to under-predict the formation of optically thin liquid clouds at supercooled temperatures--a process potentially necessary to account fully for temperature feedbacks in a warming Arctic climate.

Capillary electrophoresis as a probe of enantiospecific interactions between photoactive transition metal complexes and DNA.

Recently, we have demonstrated the capacity to separate chiral transition metal (TM) complexes of the type [M(diimine)(3)](n+) using CE buffers containing chiral tartrate salts. In separate work, several chromium(III)-tris-diimine complexes in particular have been shown to bind enantioselectively with calf-thymus (CT) DNA, and a qualitative assessment of the relative strength and enantiospecificity of this interaction is of significant interest in the characterization of these complexes as potential DNA photocleavage agents. Here, we describe two convenient approaches to investigate such binding behavior using chiral CE. For complexes with lower DNA affinities exhibiting primarily surface binding, DNA itself is used as the chiral resolving agent in the electrophoretic buffer. In this approach, resolution of the TM complexes into their Lambda and Delta isomers is achieved with the isomer eluting later exhibiting superior binding affinity toward DNA. For more strongly bound TM complexes containing ligands known to intercalate with DNA, the [Cr(diimine)(3)](3+) complexes are preincubated with oligonucleotide and subsequently enantiomerically resolved in a dibenzoyl-L-tartrate buffer system that facilitates analysis of the unbound TM species only. Differences in isomer binding affinity are distinguished by the relative peak areas of the Lambda- and Delta-isomers, and relative binding strengths of different complexes can be inferred from comparison of the total amount of unbound complex at equivalent DNA/TM ratios.

Persistent papillomavirus infection in a cat.

A seven-year-old, neutered male, crossbred Persian was diagnosed as having persistent, cutaneous papillomavirus infection. The skin lesions consisted of round, multifocal-to-confluent, raised, black plaques on the neck, thorax, shoulders, and forelegs. Papillomavirus virions were demonstrated in negative-stained, electron microscopic preparations of homogenized skin lesions and within the nuclei of cells from the stratum granulosum. Avidin-biotin immunoperoxidase stains were positive for papillomavirus in the same cells. The cat was euthanized due to a clinical diagnosis o concurrent, severe, chronic pancreatitis.

Inclusion body hepatitis in Gambel's quail (Callipepla gambelii).

An acute necrotizing hepatitis in 1- to 3-wk-old Gambel's quail (Callipepla gambelii) caused by an adenovirus is described. The infection caused high mortality in captive raised, orphan chicks at two wildlife rehabilitation facilities in Arizona (USA). Gross lesions varied from pale livers to multiple, pinpoint, white foci scattered throughout the livers. Microscopically, scattered foci of hepatocellular necrosis were present. Intact hepatocytes at teh periphery of necrotic foci had eosinophilic and basophilic intranuclear inclusion bodies.

Causes of adverse responses to soybean milk replacers in young calves.

Sixty Holstein bull calves were randomly assigned to one of three treatment groups following an initial 3-d colostrum feeding period. They were fed either whole cows' milk or ethanol-extracted or hexane-extracted soy flour in milk replacers to 6 wk of age. These products were used to identify possible causative factors associated with adverse responses to soybean in milk replacers. Average weight gains to 6 wk of age were 13.8, 7.3, and 2.8 kg and mortality was 0/20, 4/20, and 9/20 for calves fed milk, ethanol-extracted soy, and hexane-extracted soy, respectively. Heart rates (beats/min) were increased by the soy flours: 99.1 (ethanol extracted) and 116.3 (hexane extracted) versus 87.6 (milk). There was also an increased respiratory rate (breaths/min) with 67.6 and 61.1 versus 41.6 for the same treatment groups. Intradermal wheal growths verified an allergic sensitivity to the soybean products. Serum prostaglandin F2 alpha was 22% higher in the serum of calves fed the hexane-extracted soy milk replacer than in the serum of calves fed milk. Phenolic compounds in the soybean flour were implicated as possible causative factors in the adverse responses to the soybean milk replacers. Ethanol extraction of the soy flour was more effective than hexane extraction in removing phenolic compounds (2.19 vs. 1.00% phenolics).