Cyclohexanedione herbicides are inhibitors of rat heart acetyl-CoA carboxylase

Acetyl CoA carboxylase (ACC) catalyzes the carboxylation of acetyl CoA to form malonyl CoA. In skeletal muscle and heart, malonyl CoA functions to regulate lipid oxidation by inhibition of carnitine palmitoyltransferase-1, an enzyme which controls the entry of long chain fatty acids into mitochondria. We have found that several members of the cyclohexanedione class of herbicides are competitive inhibitors of rat heart ACC. These compounds constitute valuable reagents for drug development and the study of ACCbeta, a validated anti-obesity target.     

Structure identification and prophylactic antimalarial efficacy of 2-guanidinoimidazolidinedione derivatives

The reported synthetic procedure of WR182393, a 2-guanidinoimidazolidinedione derivative with high prophylactic antimalarial activity, was found to be a mixture of three closely related products. Poor solubility of WR182393 in both water and organic solvents and its impractical synthetic method have made the purification and structure identification of the reaction mixture a highly challenging task. The problems were circumvented by prodrug approach involving carbamate formation of the mixture, which enhances the solubility of the mixture in common organic solvents and facilitates the separation and structure determination of the two products. The structures of the two components were determined by X-ray crystallography and NMR of their corresponding carbamates 3a and 4a. Additional alkyl carbamates were prepared according to the same approach and two new carbamates 3b and 4d were found to possess higher intramuscular (im) efficacy than the parent compound WR182393 against Plasmodium cynomolgi in Rhesus monkey.     

Roles for kinesin and myosin during cytokinesis

Cytokinesis in higher plants involves the phragmoplast, a complex cytoplasmic structure that consists of microtubules (MTs), microfilaments (MFs) and membrane elements. Both MTs and MFs are essential for cell plate formation, although it is not clear which motor proteins are involved. Some candidate processes for motor proteins include transport of Golgi vesicles to the plane of the cell plate and the spatiotemporal organization of the cytoskeletal elements in order to achieve proper deposition and alignment of the cell plate. We have focused on the kinesin-like calmodulin binding protein (KCBP) and, more broadly, on myosins. Using an antibody that constitutively activates KCBP, we find that this MT motor, which is minus-end directed, contributes to the organization of the spindle and phragmoplast MTs. It does not participate in vesicle transport; rather, because of the orientation of the phragmoplast MTs, it is supposed that plus-end kinesins fill this role. Myosins, on the other hand, based on their inhibition with 2,3-butanedione monoxime and 1-(5-iodonaphthalene-1-sulphonyl)-1H-hexahydro-1,4-diazepine (ML-7), are associated with the process of post-mitotic spindle/phragmoplast alignment and with late lateral expansion of the cell plate. They are also not the principal motors involved in vesicle transport.     

PHOTOSYNTHESIS AND CARBON ALLOCATION IN TIPULARIA DISCOLOR (ORCHIDACEAE), A WINTERGREEN UNDERSTORY HERB

Seasonal patterns of photosynthesis and carbon allocation were determined for Tipularia discolor, a summer-deciduous wintergreen orchid of the southeastern United States, to assess the effects of environmental conditions and leaf age on carbon acquisition and allocation patterns. There was no shift in the optimum temperature for photosynthesis (T_opt) on a seasonal basis and T_opt (≈26 C) was at least 10 C higher than daily maximum air temperature during most of the growing season. Lack of photosynthetic adjustment in Tipularia to seasonal fluctuations in temperature and light suggested that the photosynthetic characteristics of this wintergreen were more similar to those of spring ephemerals than to those of evergreens and summer-active herbs. The decline in photosynthetic capacity during the winter growing season for Tipularia, largely due to leaf age effects, gradually reduced net photosynthetic rates in the field despite more favorable light and temperature conditions. Photosynthesis in the field was primarily limited by environmental conditions in early- and mid-season and by photosynthetic capacity in late-season. A ¹⁴CO₂ labelling experiment demonstrated that patterns of carbon allocation to vegetative structures were affected by the season of photosynthetic carbon fixation, whereas reproductive structures received 21% of the recovered labelled carbon regardless of the period of labelling. Carbon acquired and stored during all periods of the growing season was used to produce new vegetative and reproductive structures.     

TGF-beta 1 variants in chronic beryllium disease and sarcoidosis

Evidence suggests a genetic predisposition to chronic beryllium disease (CBD) and sarcoidosis, which are clinically and pathologically similar granulomatous lung diseases. TGF-beta1, a cytokine involved in mediating the fibrotic/Th1 response, has several genetic variants which might predispose individuals to these lung diseases. We examined whether certain TGF-beta1 variants and haplotypes are found at higher rates in CBD and sarcoidosis cases compared with controls and are associated with disease severity indicators for both diseases. Using DNA from sarcoidosis cases/controls from A Case Control Etiologic Study of Sarcoidosis Group (ACCESS) and CBD cases/controls, TGF-beta1 variants were analyzed by sequence-specific primer PCR. No significant differences were found between cases and controls for either disease in the TGF-beta1 variants or haplotypes. The -509C and codon 10T were significantly associated with disease severity indicators in both CBD and sarcoidosis. Haplotypes that included the -509C and codon 10T were also associated with more severe disease, whereas one or more copies of the haplotype containing the -509T and codon 10C was protective against severe disease for both sarcoidosis and CBD. These studies suggest that the -509C and codon 10T, implicated in lower levels of TGF-beta1 protein production, are shared susceptibility factors associated with more severe granulomatous disease in sarcoidosis and CBD. This association may be due to lack of down-regulation by TGF-beta1, although future studies will be needed to correlate TGF-beta1 protein levels with known TGF-beta1 genotypes and assess whether there is a shared mechanisms for TGF-beta1 in these two granulomatous diseases.     

The functional molecular mass of the Pasteurella hyaluronan synthase is a monomer

Hyaluronan (HA), a linear polysaccharide composed of beta1,3-GlcNAc-beta1,4-GlcUA repeats, is found in the extracellular matrix of vertebrate tissues as well as the capsule of several pathogenic bacteria. All known HA synthases (HASs) are dual-action glycosyltransferases that catalyze the addition of two different sugars from UDP-linked precursors to the growing HA chain. The bacterial hyaluronan synthase, PmHAS from Gram-negative Pasteurella multocida, is a 972-residue membrane-associated protein. Previously, the Gram-positive Streptococcus pyogenes enzyme, SpHAS (419 residues), and the vertebrate enzyme, XlHAS1 (588 residues), were found to function as monomers of protein, but the PmHAS is not similar at the protein sequence level and has quite different enzymological properties. We have utilized radiation inactivation to measure the target size of recombinant full-length and truncated PmHAS. The target size of HAS activity was confirmed using internal enzyme standards of known molecular weight. We found that the Pasteurella HA synthase protein functions catalytically as a monomer. Functional truncated soluble PmHAS also behaves as a polypeptide monomer as assessed by gel filtration chromatography and light scattering.     

Demographic and Spatiotemporal Patterns of Avian Influenza Infection at the Continental Scale,and in Relation to Annual Life Cycle of a Migratory Host

Since the spread of highly pathogenic avian influenza (HPAI) H5N1 in the eastern hemisphere, numerous surveillance programs and studies have been undertaken to detect the occurrence, distribution, or spread of avian influenza viruses (AIV) in wild bird populations worldwide. To identify demographic determinants and spatiotemporal patterns of AIV infection in long distance migratory waterfowl in North America, we fitted generalized linear models with binominal distribution to analyze results from 13,574 blue-winged teal (Anas discors, BWTE) sampled in 2007 to 2010 year round during AIV surveillance programs in Canada and the United States. Our analyses revealed that during late summer staging (July-August) and fall migration (September-October), hatch year (HY) birds were more likely to be infected than after hatch year (AHY) birds, however there was no difference between age categories for the remainder of the year (winter, spring migration, and breeding period), likely due to maturing immune systems and newly acquired immunity of HY birds. Probability of infection increased non-linearly with latitude, and was highest in late summer prior to fall migration when densities of birds and the proportion of susceptible HY birds in the population are highest. Birds in the Central and Mississippi flyways were more likely to be infected compared to those in the Atlantic flyway. Seasonal cycles and spatial variation of AIV infection were largely driven by the dynamics of AIV infection in HY birds, which had more prominent cycles and spatial variation in infection compared to AHY birds. Our results demonstrate demographic as well as seasonal, latitudinal and flyway trends across Canada and the US, while illustrating the importance of migratory host life cycle and age in driving cyclical patterns of prevalence.