Distribution records and comments on fleas in southwestern South Dakota

From October 2003 through April 2006, we collected 565 fleas incidental to a distribution survey of mammals in southwestern South Dakota. Sixty-one specimens, representing 18 species of mammals, possessed 20 species of fleas. The geographic distributions of these flea species revealed 8 new records for the Black Hills and its adjacent grasslands. Four species— Megarthroglossus divisus, Stenoponia americana, Odontopsyllus dentatus, and Amaradix euphorbi —constitute new records for South Dakota, thus increasing the state’s known flea fauna to 42 species. Hunters, trappers, and field biologists should be aware that serosurveillance during the 1990s revealed the presence of sylvatic plague and tularemia in the Black Hills area. Desde octubre de 2003 hasta abril de 2006, colectamos 565 pulgas de manera incidental durante un estudio de la distribución de mamíferos en el suroeste del estado de Dakota del Sur. Los 61 especímenes, que representaban 18 especies de mamíferos, albergaban 20 especies de pulgas. Sus distribuciones geográficas revelaron 8 nuevos registros para las Colinas Negras (Black Hills) y las praderas adyacentes. Cuatro de estas especies ( Megarthroglossus divisus, Stenoponia americana, Odontopsyllus dentatus y Amaradix euphorbi ) constituyen nuevos registros para Dakota del Sur. Esto aumenta el número de especies de pulgas conocidas del estado a 42 especies. Los cazadores, tramperos y biólogos de campo deben estar conscientes de que la vigilancia serológica durante la década de los 1990 reveló la presencia de la plaga silvática y la tularemia en el área de las Colinas Negras.     

Bacillus thuringiensis delta-endotoxin: evidence that toxin acts at the surface of susceptible cells

Enzymically activated delta-endotoxin of Bacillus thuringiensis covalently bound to Sephadex beads, has the same effect on insect cells in tissue culture as free toxin. The effect is prevented by antitoxin antibody and heat denaturation and is not due to a nonspecific protein effect, the beads, or toxin released from the beads. The toxin, therefore, probably acts at the cell surface.     

Distribution records and comments on mammals in western South Dakota

The mammal fauna of western South Dakota is imperfectly known; in particular there is a notable paucity of data from Indian reservations in the region. We collected mammals from January 2003 through May 2006 using a variety of standard methodologies, including trapping with snap-traps and Macabee traps, shooting, and salvaging road- and hunter-killed animals. Herein we provide 23 specimen-based county records representing 17 species of mammals. In addition, a photo record constitutes the first report of Dasypus novemcinctus from South Dakota and the northernmost record in the United States. The possible local extirpation of Marmota flaviventris in the southern Black Hills is discussed.     

Bacillus thuringiensis δ-endotoxin: Evidence that toxin acts at the surface of susceptible cells

Summary Enzymically activated -endotoxin ofBacillus thuringiensis covalently bound to Sephadex beads, has the same effect on insect cells in tissue culture as free toxin. The effect is prevented by antitoxin antibody and heat denaturation and is not due to a nonspecific protein effect, the beads, or toxin released from the beads. The toxin, therefore, probably acts at the cell surface.     

Heterogeneous chemistry in the atmosphere of Mars

Hydrogen radicals are produced in the martian atmosphere by the photolysis of water vapour and subsequently initiate catalytic cycles that recycle carbon dioxide from its photolysis product carbon monoxide. These processes provide a qualitative explanation for the stability of the atmosphere of Mars, which contains 95 per cent carbon dioxide. Balancing carbon dioxide production and loss based on our current understanding of the gas-phase chemistry in the martian atmosphere has, however, proven to be difficult. Interactions between gaseous chemical species and ice cloud particles have been shown to be key factors in the loss of polar ozone observed in the Earth's stratosphere, and may significantly perturb the chemistry of the Earth's upper troposphere. Water-ice clouds are also commonly observed in the atmosphere of Mars and it has been suggested previously that heterogeneous chemistry could have an important impact on the composition of the martian atmosphere. Here we use a state-of-the-art general circulation model together with new observations of the martian ozone layer to show that model simulations that include chemical reactions occurring on ice clouds lead to much improved quantitative agreement with observed martian ozone levels in comparison with model simulations based on gas-phase chemistry alone. Ozone is readily destroyed by hydrogen radicals and is therefore a sensitive tracer of the chemistry that regulates the atmosphere of Mars. Our results suggest that heterogeneous chemistry on ice clouds plays an important role in controlling the stability and composition of the martian atmosphere.