Natural antibodies to interferon-gamma

Natural antibodies to interferon (IFN)-γ were detected in the serum of virus-infected patients and also, at a low titre, in the serum of healthy subjects. The increased titre of antibodies to IFN-γ in the sera of virus-infected patients, and its decrease with clinical resolution, indicate that these antibodies are related to viral infection and probably reflect IFN-γ production as a result of antigenic stimulationin vivo. Natural antibodies to IFN-γ were affinity purified and studied for their capability to interferein vitro with the multiple activities of the lymphokine. Data obtained show that these human anti-IFN-γ antibodies have no inhibitory effect on the antiviral and antiproliferative activity of IFN-γ and do not interfere with the binding of the lymphokine to its specific cell receptor. Instead, they can inhibit the expression of HLA-DR antigens induced by IFN-γ on U937 cells and interfere, in mixed lymphocyte culture, with the proliferation of lymphocytes and the generation of cytotoxic lymphocytes. Experiments in animal models suggest that natural antibodies to IFN-γ may have a role in the immunoregulatory process limiting the intensity and/or duration of immune response. As they can interfere only with the immunomodulating activities of IFN-γ, these antibodies might open up new therapeutic approaches to diseases with evidence of activated cell-mediated immunity.     

NanoDam identifies Homeobrain (ARX) and Scarecrow (NKX2.1) as conserved temporal factors in the Drosophila central brain and visual system

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Effect of Conditioned Media from Several Cell Types on Invasion by Eimeria adenoeides Sporozoites1

ABSTRACT. The effect of conditioned media (media aspirated from a variety of cell cultures after 4 d of growth) on cellular invasion by sporozoites of the turkey coccidium, Eimeria adenoeides, was examined. Conditioned medium from turkey kidney cells and baby hamster kidney cells failed to alter invasion. However, conditioned medium from turkey cecal cell cultures produced a significant (P ≤ 0.05), two-fold increase in invasion over control medium in a variety of cell types. Retentates of conditioned medium from the turkey cecal cells that were passed through microconcentrators having molecular mass cutoffs of 50, 100, and 300 kDa similarly enhanced invasion over retentates from control medium. However, retentates from microconcentrators with a cutoff of 1,000 kDa failed to enhance invasion. Pretreatment in conditioned medium, followed by washing of sporozoites prior to inoculation into cultures, did not result in enhanced invasion. Moreover, when the interval between inoculation of sporozoites into cells and fixation of cultures was reduced to less than 3 h, no enhancement of invasion occurred. Conditioned medium from turkey cecal cells that were grown in the presence of ³⁵S-translabel had at least two labeled bands at 150 kDa and > 200 kDa that were absent in conditioned media from turkey kidney and baby hamster kidney cells.     

Protein kinase A inhibitors enhance radiation-induced apoptosis

In addition to a role for de novo protein synthesis in apoptosis we have previously shown that activation of a protein phosphatase or loss of activity of a kinase is also important in radiation-induced apoptosis in human cells [Baxter, and Lavin (1992): J Immunol 148:149–1954]. We show here that some inhibitors of protein kinases exacerbate radiation-induced apoptosis in the human cell line BM13674. The specific protein kinase A inhibitor isoquinoline sulfonamide (20 μM) gave rise to significantly increased levels of apoptosis at 2–6 h postirradiation compared to values after radiation exposure only. The same concentration of isoquinolinesulfonamide, which was effective in increasing apoptosis, reduced activity markedly. A 66% inhibition of cyclic AMP-dependent protein kinase A activity occurred in unirradiated cells at this concentration of H89 and activity was reduced to 58% in irradiated cells. Calphostin C, a specific inhibitor of protein kinase C, at a concentration of 0.1 μM, which caused 68% inhibition of enzyme activity in irradiated cells, failed to enhance the level of radiation-induced apoptosis. Other kinase inhibitors did not lead to an additional increase in apoptosis over and above that observed after irradiation. The results obtained here provide further support for an important role for modification of existing proteins during radiation-induced apoptosis.     

Correlation of open cell-attached and excised patch clamp techniques

The excised patch clamp configuration provides a unique technique for some types of single channel analyses, but maintenance of stable, long-lasting preparations may be confounded by rundown and/or rapid loss of seal. Studies were performed on the amiloride-sensitive Na⁺ channel, located on the apical surface of A₆ cells, to determine whether the nystatininduced open cell-attached patch could serve as an alternative configuration.Compared to excised inside-out patches, stable preparations were achieved more readily with the open cell-attached patch (9% vs. 56% of attempts). In both preparations, the current voltage (I-V) relation was linear, current amplitudes were equal at opposite equivalent clamped voltages, and E _rev was zero in symmetrical Na⁺ solutions, indicating similar Na⁺ activities on the cytosolic and external surfaces of the patch. Moreover, there was no evidence that nystatin altered channel activity in the patch because slope conductance (3–4pS) and E _rev (75 mV), when the bath was perfused with a high K:low Na solution (E _Na=80 mV), were nearly equal in both patch configurations.Our results therefore indicate that the nystatininduced open cell-attached patch can serve as an alternative approach to the excised inside-out patch when experiments require modulation of univalent ions in the cytosol.We thank Dr. Olaf S. Andersen for his suggestions in the development of the open cell-attached recording technique. This work was supported by a National Institutes of Health grant (DK-18061)     

Adaptation to salinity at the plant cell level

Summary Various mechanisms of adaptation of plant cells to salinity are reviewed: (1) protection of enzymes and maintenance of turgor by organic solutes; (2) prevention of ion toxicity by compartmentation; and (3) energization of solute transport by the proton pump. All these mechanisms seem to play a role in adaptation. The particular advantages of using salt-adapted cells in suspension culture to identify mechanisms of adaptation are pointed out.     

Development of membrane-potential responsiveness by myeloid leukemia cells during neutrophilic differentiation

The ability of a myeloid leukemia cell line (HL-60) to undergo membrane electrical potential changes was followed during neutrophilic differentiation induced by 2 compounds. Membrane-potential changes were induced with 12-O-tetradecanoylphorbol 13-acetate (TPA) or formyl-methionyl-leucyl-phenylalanine (FMLP) and were monitored by flow cytometry. The magnitude of the membrane-potential response to TPA increased in a more uniform manner as the population of cells matured than did acquisition of mature morphology or ability to undergo the respiratory burst in response to TPA. The response to TPA and FMLP of HL-60 cells, maximally induced to differentiate by dimethylsulfoxide, closely resembled that of neutrophils. Thus, HL-60 cells may be a useful tool in the study of the relation between membrane depolarization and subsequent cellular activation.     

The insertion of mesenchyme cells into the ectoderm during differentiation in Sea urchin embryos

Summary During the course of sea urchin development, from early blastula to pluteus larva, there are two major visible processes toward which all activities seem to be focused. They are the differentiation of the larval skeleton by the primary mesenchyme cells and the differentiation of the primitive gut by the secondary mesenchyme cells. These activities take place within the shell-like layer of epithelial cells, or ectodermal wall. The interactive role of the ectodermal wall with the mesenchyme cells is not yet clearly understood. A number of earlier studies have proposed that the ectoderm may have an inductive influence on the mesenchyme cells and that its inner surface forms a molecular template for guiding the mesenchyme cells. In this report, we suggest an additional role for the ectodermal wall. We show that some primary mesenchyme cells and secondary mesenchyme cells insert between the cells of the ectodermal wall in order to firmly anchor the anlage of the larval skeleton and primitive gut during differentiation. This mechanism may provide a physical basis for maintaining the stable positional relationship of the anlage during development.     

The performance of morphological characters in broad-scale phylogenetic analyses

In view of their propositional content (i.e. they can be right or wrong), character statements (i.e. statements that predicate characters of organisms) are treated as low-level hypotheses. The thesis of the present study is that such character statements, as do more complex scientific theories, come with variable scope. The scope of a hypothesis, or theory, is the domain of discourse over which the hypothesis, or theory, ranges. A character statement is initially introduced within the context of a certain domain of discourse that is defined by the scale of the initial phylogenetic analysis. The doctrine of 'total evidence' requires the inclusion of previously introduced characters in subsequent studies. As a consequence, the initial scope of character statements is widened to the extent that the scale of subsequent analyses is broadened. Scope expansion for character statements may result in incomplete characters, in the subdivision of characters, or in ambiguity of reference (indeterminacy of the extension of anatomical terms). Character statements with a wide scope are desirable because they refer to characters with the potential to resolve deep nodes in phylogenetic analyses. Care must be taken to preserve referential unambiguity of anatomical terms if the originally restricted scope of a character statement is expanded to match a broad-scale phylogenetic analysis.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 297–308.