Differences in hemoglobin adduct levels of acrylamide in the general population with respect to dietary intake, smoking habits and gender

The variation in dietary exposure to acrylamide (AA) has been studied through measurement of hemoglobin adduct levels from AA, as a measurement of internal dose, in a sample from the blood bank of the Malm? Diet and Cancer Cohort (n=28,098). The blood donors are well characterised with regard to their food habits, and 142 individuals were selected to obtain highest possible variation in the adduct levels from AA (none, random or high intake of coffee, fried potato, crisp bread and snacks, food items estimated to have high levels of AA). Among 70 non-smokers the AA-adduct levels varied by a factor of 5, and ranged between 0.02 and 0.1 nmol/g, with considerable overlap in AA-adduct levels between the different dietary groups. There was a significant difference between men with high dietary exposure to AA compared to men with low dietary exposure (P=0.04). No such difference was found for women. As expected a higher level (range: 0.03-0.43 nmol/g) of the AA-adduct, due to AA in tobacco smoke, was found in smokers. Smoking women with high dietary exposure to AA had significantly higher AA-adduct levels compared to smoking women with low dietary exposure (P=0.01). No such significant difference was found in smoking men. The median hemoglobin (Hb) adduct level in the randomly selected group of non-smokers was compatible with earlier studies (0.031 nmol/g). The variation in the average internal dose, measured as Hb adducts, was somewhat smaller than estimated for daily intake by food consumption questionnaires in other studies. Thus, the observed relatively narrow inter-individual variation in AA-adduct levels means that estimates of individual dietary AA intake have to be very precise if they should be useful in future cancer epidemiology.     

Src tyrosine kinase-dependent migratory effects of antithrombin in leukocytes

Tyrosine kinases are known to play a critical role in the regulation of leukocyte function. Antithrombin mediates its effects via syndecan-4 which is known to be linked to the Src tyrosine kinases. In this study, we investigated the role of Src tyrosine kinases in antithrombin-regulated leukocyte migration and Src tyrosine kinase phosphorylation in response to stimulation with antithrombin. Neutrophils and monocytes obtained from forearm venous blood were pre-treated by various Src-family selective tyrosine kinase inhibitors with or without antithrombin followed by washing and assessment of their migratory response toward antithrombin, interleukin-8, or RANTES using Boyden microchemotaxis chambers. Activation status of the two major Src tyrosine kinase phosphorylation sides Tyr416 and Tyr527 was tested using Western blot analysis. Dose-dependent reversal of the antithrombin-mediated effects on neutrophil and monocyte migration was induced by the selective Src kinase inhibitors PP1 and PP2. In Western blot analyses, antithrombin increased Tyr416 and decreased Tyr527 phosphorylation of Src tyrosine kinases in a time- and dose-dependent manner. Moreover, co-incubation with antithrombin lowered the level of RANTES-induced Tyr416 phosphorylation. Therefore, Src tyrosine kinases linked to signaling of antithrombin-binding sites on leukocytes may play an important role in modulating effects on cells function.     

Volatile composition, emission pattern, and localization of floral scent emission in Mirabilis jalapa (Nyctaginaceae)

We elucidated scent components, daily emission patterns, and the localization of floral scent release of Mirabilis jalapa. Volatiles emitted by the whole plant as well as by detached flowers were investigated using dynamic headspace analysis and gas chromatography/ mass spectrometry. Among several constituents including (Z)-3-hexenyl acetate, β-myrcene, (Z)-ocimene, and benzyl benzoate, the monoterpene (E)-β-ocimene was the major fragrance component. Fragrance release occurred in a time-dependent manner. The emission of volatiles, including (E)-β-ocimene, showed an evening-specific maximum (1700-2000 pm). The emission of (Z)-3-hexenyl acetate reached its maximum 3 h later. Histological (neutral red staining) and morphological studies (electron and light microscopy) of the flower surface and tissues of M. jalapa revealed differences in surface structures and tissue characteristics. The flower could be divided into four main sections, including the tube, the transition zone between tube and limb, a star-shaped center of the limb, and petaloid lobes of the limb. These petaloid lobes are the site of (E)-β-ocimene release. Stomata and trichomes found on the abaxial flower surface were not directly involved in fragrance release. Clear indications of osmophores involved in scent release could not be found. Thus, the results indicate that floral volatiles probably are released by diffuse emission in M. jalapa.     

The N-terminus of Drosophila SU(VAR)3-9 mediates dimerization and regulates its methyltransferase activity

In most eukaryotes, the histone methyltransferase SU(VAR)3-9 and its orthologues play a major role in the function of centromeric heterochromatin. Although the methyltransferase domain is required for the formation of a fully functional centromere, mutations within other regions of the gene such as the N-terminus also have a strong impact on its in vivo function. To analyze the contribution of the N-terminus on the methyltransferase activity, we have expressed the full-length Drosophila SU(VAR)3-9 (dSU(VAR)3-9) together with various N-terminal deletions in Escherichia coli and analyzed the structural and enzymatic properties of the purified recombinant enzymes. Full-length dSU(VAR)3-9 specifically methylates lysine 9 within histone H3 on peptides, on intact histones, and, to a lesser extent, on nucleosomes. A detailed analysis of the reaction products shows that dSU(VAR)3-9 adds two methyl groups to an unmethylated H3 tail peptide in a nonprocessive manner. The full-length enzyme elutes with an apparent molecular weight of 160 kDa from a gel filtration column, which indicates the formation of a dimer. This property is dependent on an intact N-terminus. In contrast to the full-length enzymes, proteins lacking the N-terminus fail to dimerize, and show a 10-fold lower specific activity and a linear dependence of methyltransferase activity on enzyme concentration. A N-terminal peptide containing amino acids 1-152 of dSU(VAR)3-9 is sufficient to mediate this interaction in vitro. The dimerization of dSU(VAR)3-9 and the subsequent increase of its methyltransferase activity provide a starting point to understand the molecular details of the formation of heterochromatic structures in vivo.     

IL-2 induces a competitive survival advantage in T lymphocytes

The acquisition of long-term survival potential by activated T lymphocytes is essential to ensure the successful development of a memory population in the competitive environment of the lymphoid system. The factors that grant competitiveness for survival to primed T cells are poorly defined. We examined the role of IL-2 signals during priming of CD4(+) T cells in the induction of a long-lasting survival program. We show that Ag-induced cycling of CD4(+) IL-2(-/-) T cells is independent of IL-2 in vitro. However, IL-2(-/-) T cells failed to accumulate in large numbers and develop in effector cells when primed in the absence of IL-2. More importantly, Ag-activated IL-2(-/-) T cells were unable to survive for prolonged periods of time after adoptive transfer in unmanipulated, syngeneic mice. IL-2(-/-) T cells exposed to IL-2 signals during priming, however, acquired a robust and long-lasting survival advantage over cells that cycled in the absence of IL-2. Interestingly, this IL-2-induced survival program was required for long-term persistence of primed IL-2(-/-) T cells in an intact lymphoid compartment, but was unnecessary in a lymphopenic environment. Therefore, IL-2 enhances competitiveness for survival in CD4(+) T cells, thereby facilitating the development of a memory population.     

Chicken Ig-like receptor B2, a member of a multigene family, is mainly expressed on B lymphocytes, recruits both Src homology 2 domain containing protein tyrosine phosphatase (SHP)-1 and SHP-2, and inhibits proliferation

Ig-like inhibitory receptors have been the focus of intensive research particularly in mouse and human. We report the cloning and characterization of three novel inhibitory chicken Ig-like receptors (CHIR) that display a two Ig-domain extracellular structure, a transmembrane region lacking charged residues and a cytoplasmic domain containing two ITIM. The localization of all receptors to a small genomic region and the hybridization pattern indicated that they belong to a multigene family. The genomic structure of the extracellular domain with two exons encoding the signal peptide and single exons for each Ig domain resembled that of all human leukocyte Ig-like receptors and killer cell Ig-like receptors, whereas the exons encoding the C terminus displayed a structure closely resembling killer cell Ig-like receptor genes. A mAb generated against one receptor designated CHIR-B2 reacted with all B cells and a small T cell subset, but not with monocytes, thrombocytes, or various leukocyte-derived cell lines. The mAb immunoprecipitated a 46-kDa protein from bursal cells and transfected cells. The Src homology 2 domain containing protein tyrosine phosphatase (SHP)-2 bound to CHIR-B2 even in unstimulated cells, whereas pervanadate treatment induced the tyrosine phosphorylation and recruitment of several CHIR-B2-associated proteins including SHP-1 and increased levels of SHP-2. Moreover, mAb cross-linking of CHIR-B2 reduced the proliferation of a stable transfected cell line. Together, we have identified a multigene family containing multiple CHIR including one receptor designated CHIR-B2 that is mainly expressed on B lymphocytes and inhibits cellular proliferation by recruitment of SHP-1 and SHP-2.     

Biochemical evidence for interaction between smoothelin and filamentous actin

The two major isoforms of smoothelin (A and B) contain a calponin homology (CH) domain, colocalize with alpha-smooth muscle actin (alpha-SMA) in stress fibers and are only expressed in contractile smooth muscle cells (SMCs). Based on these findings, we hypothesized that smoothelins are involved in smooth muscle cell contraction, presumably via interaction with actin. The interaction between smoothelins and three different actin isoforms (alpha- and gamma-smooth muscle and alpha-skeletal actin [alpha-SKA]) was investigated using several in vitro assays. Smoothelin-B co-immunoprecipitated with alpha-smooth muscle actin from pig aorta extracts. In rat embryonic fibroblasts, transfected smoothelins-A and -B associated with stress fibers. In vitro dot blot assays, in which immobilized actin was overlaid with radio-labeled smoothelin, showed binding of smoothelin-A to actin filaments, but not to monomeric G-actin. A truncated smoothelin, containing the calponin homology domain, associated with stress fibers when transfected and bound to actin filaments in overlay, but to a lesser extent. ELISA results showed that the binding of smoothelin to actin has no significant isoform specificity. Our results indicate an interaction between smoothelin and actin filaments. Moreover, the calponin homology domain and its surrounding sequences appear to be sufficient to accomplish this interaction, although the presence of other domains is apparently necessary to facilitate and/or strengthen the binding to actin.     

Cremation--biological source for gender research

This article presents a project designed for prehistoric gender research. It focuses on the late Bronze Age to early Iron Age urnfield in Cottbus "Alvensleben-Kaserne", Brandenburg. The cremation remains were emptied from the urns layer by layer. This provided excellent conditions for a critical reconstruction of the funeral rituals related to the cremation. Detailed recording of each bone fragment in each layer made possible the discovery of the ritual deposition of burnt bones according to the anatomical order. Cremated bones, a primarily biological source, are also a substantial resource for cultural historical research, e.g., on funeral practices as well as social structures.