Transmission of equine influenza virus to dogs

Molecular and antigenic analyses of three influenza viruses isolated from outbreaks of severe respiratory disease in racing greyhounds revealed that they are closely related to H3N8 equine influenza virus. Phylogenetic analysis indicated that the canine influenza virus genomes form a monophyletic group, consistent with a single interspecies virus transfer. Molecular changes in the hemagglutinin suggested adaptive evolution in the new host. The etiologic role of this virus in respiratory disease was supported by the temporal association of rising antibody titers with disease and by experimental inoculation studies. The geographic expansion of the infection and its persistence for several years indicate efficient transmission of canine influenza virus among greyhounds. Evidence of infection in pet dogs suggests that this infection may also become enzootic in this population.     

Proton magnetic resonance of proteins fully deuterated except for 1H-leucine side chains

The fully deuterated proteins C-phycocyanin, C-phycoerythrin, and cytochrome c have been obtained by biosynthesis with the leucine side chains, and only the leucine side chains, of normal ((1)H) isotopic composition. In these (isotopic hybrid) proteins, proton magnetic resonance analysis shows that the (1)H-leucine side chains are in a variety of environments. During protein biosynthesis, the alpha hydrogen of leucine is exchanged with a hydrogen ((2)H) from the aqueous medium.     

Enduring learning deficits and cerebral synaptic malformation from exposure to 10 parts of halothane per million

Chronic exposure of rats to 10 parts of halothane per million during early life produced later deficits in learning a shock-motivated light-dark discrimination and a food-motivated maze pattern, correlated with enduring synaptic nembrane malformation in cerebral cortex. Adult exposure had no effect. Halothane may provide a useful analytical tool for study of brain. The behavioral-ultrastructural techniques also suggest a standard for assessing the safety of trace toxicants with central nervous system effects.     

Direct observation of native DNA structures with the scanning tunneling microscope

Uncoated double-stranded DNA dissolved in a salt solution was deposited on graphite and imaged in air with the scanning tunneling microscope (STM). The resolution was such that the major and minor grooves could be distinguished. The pitch of the helix varied between 27 and 63 angstroms in the images obtained. Thus the STM can be useful for structural studies of a variety of uncoated and isolated biomolecules.     

The rise of oxygen over the past 205 million years and the evolution of large placental mammals

On the basis of a carbon isotopic record of both marine carbonates and organic matter from the Triassic-Jurassic boundary to the present, we modeled oxygen concentrations over the past 205 million years. Our analysis indicates that atmospheric oxygen approximately doubled over this period, with relatively rapid increases in the early Jurassic and the Eocene. We suggest that the overall increase in oxygen, mediated by the formation of passive continental margins along the Atlantic Ocean during the opening phase of the current Wilson cycle, was a critical factor in the evolution, radiation, and subsequent increase in average size of placental mammals.     

Broadband modulation of light by using an electro-optic polymer

A major challenge to increasing bandwidth in optical telecommunications is to encode electronic signals onto a lightwave carrier by modulating the light up to very fast rates. Polymer electro-optic materials have the necessary properties to function in photonic devices beyond the 40-GHz bandwidth currently available. An appropriate choice of polymers is shown to effectively eliminate the factors contributing to an optical modulator's decay in the high-frequency response. The resulting device modulates light with a bandwidth of 150 to 200 GHz and produces detectable modulation signal at 1.6 THz. These rates are faster than anticipated bandwidth requirements for the foreseeable future.     

Clear-air turbulence: simultaneous observations by radar and aircraft

Ultrasensitive radars and uninstrumented jet aircraft in concert have probed regions of the clear atmosphere in search of clear-air turbulence. All sources of clear-air radar echoes above 6 kilometers that were probed simultaneously by the aircraft were found to be turbulent.     

Photoinduced nucleation of water vapor

Strong photoinduced nucleation of pure water vapor was found to occur in a wavelength range where no ultraviolet absorption of water vapor has been reported. Systematic studies were made of the dependence of the nucleation rate and the delay time for the initiation of nucleation on light intensity. The results obtained were accurately fitted by a phenomenological mechanism whereby the nucleation is initiated by clusters accumulating an appropriate number of photoexcited water molecules.     

Characterization of the reconstructed 1918 Spanish influenza pandemic virus

The pandemic influenza virus of 1918-1919 killed an estimated 20 to 50 million people worldwide. With the recent availability of the complete 1918 influenza virus coding sequence, we used reverse genetics to generate an influenza virus bearing all eight gene segments of the pandemic virus to study the properties associated with its extraordinary virulence. In stark contrast to contemporary human influenza H1N1 viruses, the 1918 pandemic virus had the ability to replicate in the absence of trypsin, caused death in mice and embryonated chicken eggs, and displayed a high-growth phenotype in human bronchial epithelial cells. Moreover, the coordinated expression of the 1918 virus genes most certainly confers the unique high-virulence phenotype observed with this pandemic virus.