Epsilon-tubulin is an essential component of the centriole

Centrioles and basal bodies are cylinders composed of nine triplet microtubule blades that play essential roles in the centrosome and in flagellar assembly. Chlamydomonas cells with the bld2-1 mutation fail to assemble doublet and triplet microtubules and have defects in cleavage furrow placement and meiosis. Using positional cloning, we have walked 720 kb and identified a 13.2-kb fragment that contains epsilon-tubulin and rescues the Bld2 defects. The bld2-1 allele has a premature stop codon and intragenic revertants replace the stop codon with glutamine, glutamate, or lysine. Polyclonal antibodies to epsilon-tubulin show peripheral labeling of full-length basal bodies and centrioles. Thus, epsilon-tubulin is encoded by the BLD2 allele and epsilon-tubulin plays a role in basal body/centriole morphogenesis.     

Inhibition of p38 MAP kinase by utilizing a novel allosteric binding site

The p38 MAP kinase plays a crucial role in regulating the production of proinflammatory cytokines, such as tumor necrosis factor and interleukin-1. Blocking this kinase may offer an effective therapy for treating many inflammatory diseases. Here we report a new allosteric binding site for a diaryl urea class of highly potent and selective inhibitors against human p38 MAP kinase. The formation of this binding site requires a large conformational change not observed previously for any of the protein Ser/Thr kinases. This change is in the highly conserved Asp-Phe-Gly motif within the active site of the kinase. Solution studies demonstrate that this class of compounds has slow binding kinetics, consistent with the requirement for conformational change. Improving interactions in this allosteric pocket, as well as establishing binding interactions in the ATP pocket, enhanced the affinity of the inhibitors by 12,000-fold. One of the most potent compounds in this series, BIRB 796, has picomolar affinity for the kinase and low nanomolar inhibitory activity in cell culture.     

Microarray profile of differentially expressed genes in a monkey model of allergic asthma

Background

Inhalation of Ascaris suum antigen by allergic monkeys causes an immediate bronchoconstriction and delayed allergic reaction, including a pulmonary inflammatory infiltrate. To identify genes involved in this process, the gene-expression pattern of allergic monkey lungs was profiled by microarrays. Monkeys were challenged by inhalation of A. suum antigen or given interleukin-4 (IL-4) treatment; lung tissue was collected at 4, 18 or 24 h after antigen challenge or 24 h after IL-4. Each challenged monkey lung was compared to a pool of normal, unchallenged monkey lungs.

Results

Of the approximately 40,000 cDNAs represented on the microarray, expression levels of 169 changed by more than 2.5-fold in at least one of the pairwise probe comparisons; these cDNAs encoded 149 genes, of which two thirds are known genes. The largest number of regulated genes was observed 4 h after challenge. Confirmation of differential expression in the original tissue was obtained for 95% of a set of these genes using real-time PCR. Cluster analysis revealed at least five groups of genes with unique expression patterns. One cluster contained genes for several chemokine mediators including eotaxin, PARC, MCP-1 and MCP-3. Genes involved in tissue remodeling and antioxidant responses were also identified as regulated by antigen and IL-4 or by antigen only.

Conclusion

This study provides a large-scale profile of gene expression in the primate lung following allergen or IL-4 challenge. It shows that microarrays, with real-time PCR, are a powerful tool for identifying and validating differentially expressed genes in a disease model.     

Gene expression studies on developing kernels of maize sucrose synthase (SuSy) mutants show evidence for a third SuSy gene

Previous studies have identified two tissue- and cell-specific, yet functionally redundant, sucrose synthase (SuSy) genes, Sh1 and Sus1, which encode biochemically similar isozymes, SH1 and SUS1 (previously referred to as SS1 and SS2, respectively). Here we report evidence for a third SuSy gene in maize, Sus3, which is more similar to dicot than to monocot SuSys. RNA and/or protein blot analyses on developing kernels and other tissues show evidence of expression of Sus3, although at the lowest steady-state levels of the three SuSy gene products and without a unique pattern of tissue specificity. Immunoblots of sh1sus1-1 embryos that are either lacking or deficient for the embryo-specific SUS1 protein have shown a protein band which we attribute to the Sus3 gene, and may contribute to the residual enzyme activity seen in embryos of the double mutant. We also studied developing seeds of the double mutant sh1sus1-1, which is missing 99.5% of SuSy enzyme activity, for evidence of co-regulation of several genes of sugar metabolism. We found a significant reduction in the steady-state levels of Miniature-1 encoded cell wall invertase2, and Sucrose transporter (Sut) mRNAs in the double mutant, relative to the lineage-related sh1Sus1 and sh1Sus1 kernels. Down-regulation of the Mn1 gene was also reflected in significant reductions in cell wall invertase activity. Co-regulatory changes were not seen in the expression of Sucrose phosphate synthase, UDP-glucose pyrophosphorylase, and ADP-glucose pyrophosphorylase.     

Analysis of Weather Effects on Variability in Lyme Disease Incidence in the Northeastern United States

In this study, variability in reported Lyme disease incidence between 1993 and 2001 was analyzed in seven states in the northeastern part of the USA. Positive significant correlations at p < 0.05 were found in all states between early summer disease incidence and the June moisture index in the region two years prior. These correlations may reflect an enhanced nymphal Ixodes scapularis survival under wetter conditions. In some states, significant correlations were observed related to warmer winter weather a year and a half prior to disease incidence, which may have been due to higher survival and activity levels of the white-footed mouse, an important host for I. scapularis ticks. This revised version was published online in July 2006 with corrections to the Cover Date.     

Regulation of acid secretion and paracellular permeability by F-actin in the bullfrog, Rana catesbeiana

Many studies have implicated F-actin in the regulation of gastric acid secretion using cytochalasin D (CD) to disrupt apical actin filaments in oxyntic cells. However, it is known that CD also affects mucosal permeability by disrupting tight junction structure. Here we investigated the contribution of F-actin to mucosal permeability and acid secretion in the stomach using CD. Stomachs were mounted in Ussing chambers and acid secretion (stimulated or inhibited), transepithelial resistance (TER), mannitol flux, bicarbonate transport, and dual mannitol/sodium fluxes were determined with or without CD. H(+) back diffusion was predicted from its diffusion coefficient. Incubation with CD resulted in a significant reduction in stimulated acid secretion. TER was unchanged in stimulated tissues but significantly reduced in inhibited tissues. Mannitol flux, bicarbonate transport, and H(+)-back diffusion increased significantly with CD. However, the rates of bicarbonate and H(+) flux were not large enough to account for the inhibition of acid secretion. These findings demonstrate that actin filaments regulate paracellular permeability and play an essential role in the regulation of acid secretion in the stomach.     

Role of glutamine and arginase in protection against ammonia-induced cell death in gastric epithelial cells

Ammonia is a cytotoxic factor produced during Helicobacter pylori infection that may reduce the survival of surface epithelial cells. Here we examine whether ammonia kills cells and whether L-glutamine (L-Gln) protects against cell death by stimulating ammonia detoxification pathways. Cell viability and vacuolation were quantified in rat gastric epithelial (RGM1) cells incubated with ammonium chloride at pH 7.4 in the presence or absence of L-Gln. Incubation of RGM1 cells with ammonium chloride caused a dose-dependent increase in cell death and vacuolation, which were both inhibited by L-Gln. We show that RGM1 cells metabolize ammonia to urea via arginase, a process that is stimulated by L-Gln and results in reduced ammonia cytotoxicity. L-Gln also inhibits the uptake and facilitates the extrusion of ammonia from cells. Blockade of glutamine synthetase did not reduce the survival of RGM1 cells, demonstrating that the conversion of L-glutamate and ammonia to L-Gln is not involved in ammonia detoxification. Thus our data support a role for L-Gln and arginase in protection against ammonia-induced cell death in gastric epithelial cells.     

Vasoactive intestinal peptide regulation of nerve growth factor in the embryonic mouse

Vasoactive intestinal peptide (VIP), a regulator of embryonic growth, increased the concentration of nerve growth factor (NGF)-like immunoreactivity in the conditioned medium of cultured explanted embryonic day (E) 9.5 neural tube preparations compared to control preparations. VIP treatment also induced an increase of NGF-like immunoreactivity (NGF-IR) within the neural tube preparation tissue. A 60 kDa isoform was the primary form of NGF detected. VIP is shown to be a regulator of NGF in the E9.5 embryonic mouse and stimulates the release of a high molecular weight isoform of NGF.