Influence of the activation of the immune system cells on the parameters of lipid metabolism in macrophages

The influence of tumor necrosis factor a (TNF-alpha) and media, conditioned by activated macrophages and lymphocytes and containing a complex of biologically active compounds (including cytokines), on the parameters of lipid metabolism in macrophages was studied. The addition of recombinant TNF-alpha and immunocompetent cell-conditioned media to mouse peritoneal macrophages culture stimulated labelled oleate incorporation into cholesterol esters and triglycerides, as well as labelled glycerine incorporation into cholesterol esters, but inhibited labelled cholesterol incorporation into cholesterol esters. One of the mechanisms of the influence of activated immunocompetent cells on cholesterol metabolism in macrophages was, supposedly, the stimulation of sphigmomyelinase activity by a complex of anti-inflammatory cytokines produced by these cells on their activation.     

Pleiotropic effects on mandibular morphology II: differential epistasis and genetic variation in morphological integration

The evolution of morphological modularity through the sequestration of pleiotropy to sets of functionally and developmentally related traits requires genetic variation in the relationships between traits. Genetic variation in relationships between traits can result from differential epistasis, where epistatic relationships for pairs of loci are different for different traits. This study maps relationship quantitative trait loci (QTLs), specifically QTLs that affect the relationship between individual mandibular traits and mandible length, across the genome in an F2 intercross of the LG/J and SM/J inbred mouse strains (N = 1045). We discovered 23 relationship QTLs scattered throughout the genome. All mandibular traits were involved in one or more relationship QTL. When multiple traits were affected at a relationship QTL, the traits tended to come from a developmentally restricted region of the mandible, either the muscular processes or the alveolus. About one-third of the relationship QTLs correspond to previously located trait QTLs affecting the same traits. These results comprise examples of genetic variation necessary for an evolutionary response to selection on the range of pleiotropic effects.     

A critical role of tropomyosins in TGF-beta regulation of the actin cytoskeleton and cell motility in epithelial cells

We have investigated transforming growth factor beta (TGF-beta)-mediated induction of actin stress fibers in normal and metastatic epithelial cells. We found that stress fiber formation requires de novo protein synthesis, p38Mapk and Smad signaling. We show that TGF-beta via Smad and p38Mapk up-regulates expression of actin-binding proteins including high-molecular-weight tropomyosins, alpha-actinin and calponin h2. We demonstrate that, among these proteins, tropomyosins are both necessary and sufficient for TGF-beta induction of stress fibers. Silencing of tropomyosins with short interfering RNAs (siRNAs) blocks stress fiber assembly, whereas ectopic expression of tropomyosins results in stress fibers. Ectopic-expression and siRNA experiments show that Smads mediate induction of tropomyosins and stress fibers. Interestingly, TGF-beta induction of stress fibers was not accompanied by changes in the levels of cofilin phosphorylation. TGF-beta induction of tropomyosins and stress fibers are significantly inhibited by Ras-ERK signaling in metastatic breast cancer cells. Inhibition of the Ras-ERK pathway restores TGF-beta induction of tropomyosins and stress fibers and thereby reduces cell motility. These results suggest that induction of tropomyosins and stress fibers play an essential role in TGF-beta control of cell motility, and the loss of this TGF-beta response is a critical step in the acquisition of metastatic phenotype by tumor cells.     

Characteristics of antitoxic and antibacterial immune response in nontoxic forms of oropharyngeal diphtheria

The enzyme immunoassay system (EIA) for differentiation of antibodies in therapeutic heterogeneous antitoxic serum and antibodies to Corynebacterium diphtheriae toxigenic strains in patients and carriers was developed. The use of EIA permitted the dynamic evaluation of the characteristics of humoral antitoxic and antibacterial immune response in 50 patients with the localized and disseminated forms of stomatopharyngeal diphtheria and 14 "healthy" carriers of toxigenic C. diphtheriae. As revealed in this study, the symptoms of the disease in patients with disseminated forms of stomatopharyngeal diphtheria developed in the presence of statistically significant low quantitative values of antitoxic and antibacterial antibodies to C. diphtheriae antigens. In the group of patients with the localized forms of the disease the initially low level of antitoxic antibodies was detected with the concentration of antibacterial antibodies remaining unchanged. During the period of convalescence the levels of antitoxic antibodies in both groups reached those of healthy persons. In case of localized forms of the disease the level of antibacterial antibodies decreased as compared with healthy persons, starting from the second week of the disease. The period of convalescence in the disseminated forms was characterized by the low concentration of antibacterial antibodies. Carrier state was formed in the presence of high levels of antitoxic antibodies and significantly low levels of antibacterial ones.     

Noncompetitive immunochemical determination of ribonuclease using transition metal ions and the effect of catalytic hydrogen release

A noncompetitive variant of immunochemical ribonuclease (RNase) determination has been developed, involving the use of Co(II) as a label. A variety of approaches to labeling the immunological reagent with the metal have been assessed. In the variant proposed, catalytic hydrogen release was used as a means of detecting the label, the amount of which was proportional to RNase concentration. Conditions making it possible to record catalytic hydrogen release fluxes were determined. In the presence of RNase, the electrocatalytic effect was maximum at a concentration of Co(II) in the ammoniac buffer, equal to 2 x 10(-4) M (pH 10.0). The dependence was linear in the range 4-2000 ng/ml RNase concentrations (threshold concentration, 2 ng/ml).     

Microinjection of pollen‐specific actin‐depolymerizing factor, ZmADF1, reorientates F‐actin strands in Tradescantia stamen hair cells

Maize actin-depolymerizing factor (ADF) binds both monomeric and filamentous actin and increases actin dynamics in vitro. To test its effects in vivo, recombinant pollen ADF1 was expressed in bacteria and microinjected into Tradescantia stamen hair cells. Initially, all cytoplasmic streaming ceased and the central, longitudinal transvacuolar strands were disrupted. After 20–45 min, streaming resumed but in the form of conspicuous transverse pathways of movement in the cortex. Staining the actin filaments by a second injection of fluorescein-conjugated phalloidin showed that the longitudinal actin cables seen in controls had been replaced by a thickening of the transverse cortical arrays, whose orientation matched the new pattern of streaming. Microinjection of rhodamine–tubulin confirmed that the microtubules also formed a transverse cortical array and it is suggested that the spatial cues for re-modelling the actin after ADF1 injection may be provided by the microtubular system.     

Evolution of spore release mechanisms in the saprolegniaceae (Oomycetes): evidence from a phylogenetic analysis of internal transcribed spacer sequences

Classical studies on spore release within the Saprolegniaceae (Oomycetes) led to the proposition that different mechanisms of sporangial emptying represent steps in an evolutionary transition series. We have reevaluated this idea in a phylogenetic framework using internal transcribed spacer sequences of four genera. These data were compared with the response to osmotic stress exhibited by each taxon. Saprolegnia emerges as the most basal genus, sister to Achlya, Thraustotheca, and Dictyuchus. Achlya and Thraustotheca are most closely related, while Dictyuchus appears to have evolved along a separate evolutionary lineage. The resulting phylogenetic framework is consistent with the idea that the mechanism of sporangial emptying exhibited by Saprolegnia represents the plesiomorphic condition from which the other mechanisms were derived independently. These alternative mechanisms of spore release may have resulted from a small number of mutations that inhibited axonemal development and altered the temporal and spatial expression of lytic enzymes that degrade the sporangial wall. Copyright 1998 Academic Press.