Tumor-promoting phorbol esters stimulate hematopoietic colony formation in vitro

Tumor-promoting phorbol esters stimulated mouse bone marrow cells to form myeloid colonies in agar cultures without added colony-stimulating factors. The colony-stimulating ability of various phorbol esters correlated well with their ability to promote skin tumors in vivo. These results suggest that phorbol esters mimic the action of specific colony-stimulating factors that regulate growth.     

Simulation of corn yields in the Upper Great Lakes Region of the US using a modeling framework

We examined the utility of a site-based simulation model for corn (MAIZE) applied to the Upper Great Lakes Region (UGLR) of the United States for 1992–1996. To evaluate model outputs, we used a modeling applications system integrative framework (MASIF) to simulate corn yields in the UGLR. We divided the region into two ecological zones (upper UGLR-1 and lower UGLR-2) and compared MAIZE and USDA National Agriculture Statistics Service (NASS) yield estimates in each zone. There was greater agreement between MAIZE and NASS yields at lower yield values. As NASS yields increased, MAIZE yields also increased, but to a greater extent than did NASS yields. We conducted a mean spatial analysis of maize yield from 1992 to 1996. We also conducted a spatial analysis of 1994, 1995 and 1996. There are both spatial and temporal differences when yields are mapped.     

The genomic sequence of the accidental pathogen Legionella pneumophila

We present the genomic sequence of Legionella pneumophila, the bacterial agent of Legionnaires' disease, a potentially fatal pneumonia acquired from aerosolized contaminated fresh water. The genome includes a 45-kilobase pair element that can exist in chromosomal and episomal forms, selective expansions of important gene families, genes for unexpected metabolic pathways, and previously unknown candidate virulence determinants. We highlight the genes that may account for Legionella's ability to survive in protozoa, mammalian macrophages, and inhospitable environmental niches and that may define new therapeutic targets.     

A Burkholderia pseudomallei toxin inhibits helicase activity of translation factor eIF4A

The structure of BPSL1549, a protein of unknown function from Burkholderia pseudomallei, reveals a similarity to Escherichia coli cytotoxic necrotizing factor 1. We found that BPSL1549 acted as a potent cytotoxin against eukaryotic cells and was lethal when administered to mice. Expression levels of bpsl1549 correlate with conditions expected to promote or suppress pathogenicity. BPSL1549 promotes deamidation of glutamine-339 of the translation initiation factor eIF4A, abolishing its helicase activity and inhibiting translation. We propose to name BPSL1549 Burkholderia lethal factor 1.     

Seemingly anomalous angular distributions in H + D₂ reactive scattering

When a hydrogen (H) atom approaches a deuterium (D(2)) molecule, the minimum-energy path is for the three nuclei to line up. Consequently, nearly collinear collisions cause HD reaction products to be backscattered with low rotational excitation, whereas more glancing collisions yield sideways-scattered HD products with higher rotational excitation. Here we report that measured cross sections for the H + D(2) → HD(v' = 4, j') + D reaction at a collision energy of 1.97 electron volts contradict this behavior. The anomalous angular distributions match closely fully quantum mechanical calculations, and for the most part quasiclassical trajectory calculations. As the energy available in product recoil is reduced, a rotational barrier to reaction cuts off contributions from glancing collisions, causing high-j' HD products to become backward scattered.