Eotaxin/CCL11 is involved in acute,but not chronic,allergic airway responses to Aspergillus fumigatus

Eotaxin/CCL11 is a major chemoattractant for eosinophils and Th2 cells. As such, it represents an attractive target in the treatment of allergic disease. The present study addresses the role of eotaxin/CCL11 during acute and chronic allergic airway responses to the fungus Aspergillus fumigatus. Mice lacking the eotaxin gene (Eo-/-) and wild-type mice (Eo+/+) were sensitized to A. fumigatus and received either an intratracheal challenge with soluble A. fumigatus antigens (acute model) or an intratracheal challenge with live A. fumigatus spores or conidia (chronic model). Airway hyperresponsiveness and eosinophil, but not T cell, recruitment were significantly decreased at 24 h after the soluble allergen in A. fumigatus-sensitized Eo-/- mice compared with similarly sensitized Eo+/+ mice. In contrast, the development of chronic allergic airway disease due to A. fumigatus conidia was not altered by the lack of eotaxin. Together, these data suggest that eotaxin initiates allergic airway disease due to A. fumigatus, but this chemokine did not appear to contribute to the maintenance of A. fumigatus-induced allergic airway disease.     

Endogenous interferon-alpha production by differentiating human monocytes regulates expression and function of the IL-2/IL-4 receptor gamma chain

In vitro monocyte-derived macrophages (MDMac) and synovial fluid macrophages from inflamed joints differ from monocytes in their responses to interleukin 4 (IL-4). While IL-4 can suppress LPS-induced interleukin beta (IL-beta) and tumour necrosis factor alpha (TNF-alpha) production by monocytes, IL-4 can suppress LPS-induced IL-1 beta, but not TNFalpha production by the more differentiated cells. Recently we reported a correlation between the ability of IL-4 to regulate TNFalpha production by monocytes and the expression of the IL-4 receptor gamma chain or gamma common (gamma c chain). Like MDMac, interferon alpha (IFNalpha)-treated monocytes expressed less IL-4 receptor gamma c chain, reduced levels of IL-4-activated STAT6 and IL-4 could not suppress LPS-induced TNFalpha production. In addition, like monocytes and MDMac, IFNalpha-treated monocytes expressed normal levels of the IL-4 receptor alpha chain and IL-4 significantly suppressed LPS-induced IL-1 beta production. With addition of IFNalpha-neutralizing antibodies, the ability of IL-4 to suppress LPS-induced TNFalpha production with prolonged monocyte culture was restored. Detection of IFNalpha in synovial fluids from inflamed joints further implicates IFNalpha in the inability of IL-4 to suppress TNFalpha production by synovial fluid macrophages. This study identifies a mechanism for the differential expression of gamma c and varied responses to IL-4 by human monocytes compared with MDMac.     

A phylogenetic supertree of the bats (Mammalia: Chiroptera)

We present the first estimate of the phylogenetic relationships among all 916 extant and nine recently extinct species of bats Mammalia: Chiroptera), a group that accounts for almost one-quarter of extant mammalian diversity. This phylogeny was derived by combining 105 estimates of bat phylogenetic relationships published since 1970 using the supertree construction technique of Matrix Representation with Parsimony (MRP). Despite the explosive growth in the number of phylogenetic studies of bats since 1990, phylogenetic relationships in the order have been studied non-randomly. For example, over one-third of all bat systematic studies to date have locused on relationships within Phyllostomidae, whereas relationships within clades such as Kerivoulinae and Murinae have never been studied using cladistic methods. Resolution in the supertree similarly differs among clades: overall resolution is poor (46.4%, of a fully bifurcating solution) but reaches 100% in some groups (e.g. relationships within Mormoopidae). The supertree analysis does not support a recent proposal that Microchiroptera is paraphyletic with respect to Megachiroptera, as the majority of source topologies support microbat monophyly. Although it is not a substitute for comprehensive phylogenetic analyses of primary molecular and morphological data, the bat supertree provides a useful tool for future phylogenetic comparative and macroevolutionary studies. Additionally, it identifies clades that have been little studied, highlights groups within which relationships are controversial, and like all phylogenetic studies, provides preliminary hypotheses that can form starting points for future phylogenetic studies of bats.     

Sources of nitrate in rivers draining sixteen watersheds in the northeastern U.S.: Isotopic constraints

The feasibility of using nitrogen and oxygenisotope ratios of nitrate (NO₃ ^–) forelucidating sources and transformations ofriverine nitrate was evaluated in a comparativestudy of 16 watersheds in the northeastern U.S.A. Stream water was sampled repeatedly at theoutlets of the watersheds between January andDecember 1999 for determining concentrations,¹⁵N values, and ¹⁸Ovalues of riverine nitrate.In conjunction with information about land useand nitrogen fluxes,¹⁵N_nitrate and¹⁸O_nitrate values providedmainly information about sources of riverinenitrate. In predominantly forested watersheds,riverine nitrate had mean concentrations ofless than 0.4 mg NO₃ ^–-N L^–1,¹⁵N_nitrate values of lessthan +5, and ¹⁸O_nitratevalues between +12 and +19. This indicatesthat riverine nitrate was almost exclusivelyderived from soil nitrification processes withpotentially minor nitrate contributions fromatmospheric deposition in some catchments. Inwatersheds with significant agricultural andurban land use, concentrations of riverinenitrate were as high as 2.6 mg NO₃ ^–-NL^–1 with ¹⁵N_nitratevalues between +5 and +8 and¹⁸O_nitrate values generallybelow +15. Correlations between nitrateconcentrations, ¹⁵N_nitratevalues, and N fluxes suggest that nitrate inwaste water constituted a major, and nitrate inmanure a minor additional source of riverinenitrate. Atmospheric nitrate deposition ornitrate-containing fertilizers were not asignificant source of riverine nitrate inwatersheds with significant agricultural andurban land use. Although complementary studiesindicate that in-stream denitrification wassignificant in all rivers, the isotopiccomposition of riverine nitrate sampled at theoutlet of the 16 watersheds did not provideevidence for denitrification in the form ofelevated ¹⁵N_nitrate and¹⁸O_nitrate values. Relativelylow isotopic enrichment factors for nitrogenand oxygen during in-stream denitrification andcontinuous admixture of nitrate from theabove-described sources are thought to beresponsible for this finding.     

In vitro inhibition of Salmonella enterica serovars choleraesuis and typhimurium,Escherichia coli F-18, and Escherichia coli O157:H7 by a porcine continuous-flow competitive exclusion culture

A competitive exclusion (CE) culture of porcine cecal bacteria was developed as a continuous-flow culture in chemostats, was designated RPCF, and was used as a model to determine its usefulness against in vitro colonization by Salmonella enterica serovars Typhimurium and Choleraesuis, Escherichia coli strain F-18, and E. coli serotype O157:H7 (933). Chemostats with or without RPCF were inoculated with 10⁶ colony-forming units (CFU)/ml of Typhimurium, Choleraesuis, F-18, or O157:H7. Chemostats were sampled for salmonellae and E. coli at 15 min, 7 h, and every 24 h thereafter. In control chemostats without RPCF, Typhimurium, Choleraesuis, F-18, and O157:H7 rapidly established colonization and had concentrations of 10⁶ CFU/ml for 96–120 h post-inoculation. In the chemostats that contained RPCF, reductions (P < 0.05) of Choleraesuis, F-18, and O157:H7 were observed at 24 h post-inoculation. Typhimurium was decreased (P < 0.05) at 48 h post-inoculation, and by 120 h post-inoculation, all chemostats were negative for the four challenge microorganisms. These results demonstrate that RPCF cultures were able to inhibit the growth of Typhimurium, Choleraesuis, and E. coli strains F-18 and O157:H7 in vitro and suggest the potential for the use of CE in swine to prevent disease induced by these microorganisms. Received: 2 October 2001 / Accepted: 31 December 2001     

Numb inhibits membrane localization of Sanpodo,a four-pass transmembrane protein,to promote asymmetric divisions in Drosophila

Cellular diversity is a fundamental characteristic of complex organisms, and the Drosophila CNS has proved an informative paradigm for understanding the mechanisms that create cellular diversity. One such mechanism is the asymmetric localization of Numb to ensure that sibling cells respond differently to the extrinsic Notch signal and, thus, adopt distinct fates (A and B). Here we focus on the only genes known to function specifically to regulate Notch-dependent asymmetric divisions: sanpodo and numb. We demonstrate that sanpodo, which specifies the Notch-dependent fate (A), encodes a four-pass transmembrane protein that localizes to the cell membrane in the A cell and physically interacts with the Notch receptor. We also show that Numb, which inhibits Notch signaling to specify the default fate (B), physically associates with Sanpodo and inhibits Sanpodo membrane localization in the B cell. Our findings suggest a model in which Numb inhibits Notch signaling through the regulation of Sanpodo membrane localization.     

HBXIP functions as a cofactor of survivin in apoptosis suppression

Survivin is an anti-apoptotic protein that is overexpressed in most human cancers. We show that survivin forms complexes with a cellular protein, hepatitis B X-interacting protein (HBXIP), which was originally recognized for its association with the X protein of hepatitis B virus (HBX). Survivin-HBXIP complexes, but neither survivin nor HBXIP individually, bind pro-caspase-9, preventing its recruitment to Apaf1, and thereby selectively suppressing apoptosis initiated via the mitochondria/cytochrome c pathway. Viral HBX protein also interacts with the survivin- HBXIP complex and suppresses caspase activation in a survivin-dependent manner. Thus, HBXIP functions as a cofactor for survivin, and serves as a link between the cellular apoptosis machinery and a viral pathogen involved in hepatocellular carcinogenesis.     

Human skeletal muscle creatine transporter mRNA and protein expression in healthy,young males and females

The present study investigated whether there were any differences between males and females in respect to creatine transporter (CreaT) gene expression and/or total creatine (TCr) content in human vastus lateralis muscle. Skeletal muscle obtained from young healthy male (n = 13, age: 23.2 ± 5.0 years) and female subjects (n = 12, age: 21.7 ± 4.3 years) was analyzed for CreaT mRNA, CreaT protein and TCr content. Total CreaT protein content in the muscle was similar (p > 0.05) between the sexes. Two bands (~ 55 and 73 kDa) of the CreaT protein were detected in all muscle samples. Both the 55 and the 73 kDa bands were present in similar (p > 0.05) amounts in males compared with females. The 73 kDa band was in greater abundance (p < 0.05) than the 55 kDa band, irrespective of gender. In addition, CreaT mRNA expression relative to -actin mRNA and the TCr content (males: 117.8 ± 2.2, females: 125.3 ± 4.3 mmol.kg^–1 dry mass) were also unaffected (p > 0.05) by gender. These data demonstrate that gender does not influence skeletal muscle TCr content and CreaT gene expression in young human subjects.     

The impact of the paper of Edsall and Mehl (1940) on actin and actomyosin research

The paper of Edsall and Mehl, ‘The effect of denaturing agents on myosin, II. Viscosity and double refraction of flow’, J. Biol. Chem. 133 (1940) 409–429, inspired our research on actin and actomyosin. It led to the specific purification of actin with magnesium ions and to the demonstration of the central role of the Mg²⁺-activated actomyosin ATPase in contraction of live muscle.