A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

Meiotic Recombination Initiated by a Double-Strand Break in Rad50Δ Yeast Cells Otherwise Unable to Initiate Meiotic Recombination

Meiotic recombination in Saccharomyces cerevisiae is initiated by double-strand breaks (DSBs). We have developed a system to compare the properties of meiotic DSBs with those created by the site-specific HO endonuclease. HO endonuclease was expressed under the control of the meiotic-specific SPO13 promoter, creating a DSB at a single site on one of yeast's 16 chromosomes. In Rad(+) strains the times of appearance of the HO-induced DSBs and of subsequent recombinants are coincident with those induced by normal meiotic DSBs. Physical monitoring of DNA showed that SPO13::HO induced gene conversions both in Rad(+) and in rad50Δ cells that cannot initiate normal meiotic DSBs. We find that the RAD50 gene is important, but not essential, for recombination even after a DSB has been created in a meiotic cell. In rad50Δ cells, some DSBs are not repaired until a broken chromosome has been packaged into a spore and is subsequently germinated. This suggests that a broken chromosome does not signal an arrest of progression through meiosis. The recombination defect in rad50Δ diploids is not, however, meiotic specific, as mitotic rad50 diploids, experiencing an HO-induced DSB, exhibit similar departures from wild-type recombination.     

Comparison of the action of carminomycin and rubomycin on the dynamics of the primary and secondary immune responses

The effect of rubomycin and carminomycin on the dynamics of the primary and secondary immune response and formation of the immunologic memory to sheep red cells in mice was studied. Differences in the character of the antibiotics effect indicative of the higher selective action of carminomycin on multiplying cells, precursors of the antibody-forming plasmids, were found. Theoretically interesting discrepancies in the effect of the antibiotics on the content of the antibodies in the serum and the antibody-producing cells in the spleen were shown. It was demonstrated that carminomycin had no effect on formation of the immunologic memory inspite of a noticeable decrease in the total number of the spleen nuclear cells and the number of the antibody-forming cells at the moment of immunization under the effect of the antibiotic.     

Interaction of synthetic decapeptide SLTCLVKGFY with human T lymphocytes

The synthetic peptide SLTCLVKGFY, corresponding to the 364-373 amino acid sequence of the human IgG heavy chain (Immunorphin), was found to compete with [125I] beta-endorphin for binding by high-affinity receptors on T lymphocytes isolated from the blood of healthy donors (Ki 0.6 nM). The fragments 3-10, 4-10, 5-10, and 6-10 of Immunorphin also inhibited the binding (Ki 2.2, 3.4, 8.0, and 15 nM, respectively). Specificity of these receptors was studied: they turned out to be insensitive to naloxone and, therefore, are not opioid. The Kd values of the specific binding of 125I-labeled Immunorphin and its 6-10 fragment to the receptor were found to be 7.4 and 36.3 nM, respectively.     

beta-Endorphin-like peptide SLTCLVKGFY is a selective agonist of nonopioid beta-endorphin receptor

It has been found that beta-endorphin (beta-END) and a synthetic beta-END-like decapeptide Ser-Leu-Thr-Cys-Leu-Val-Lys-Gly-Phe-Tyr (termed immunorphin, IMN) corresponding to the sequence 364-373 of human IgG heavy chain stimulate Con A-induced proliferation of T lymphocytes from the blood of healthy donors. [Met(5)]enkephalin ([Met(5)]ENK) and an antagonist of opioid receptors naloxone (NAL) tested in parallel were not active. The stimulating effect of beta-END and IMN on T lymphocyte proliferation was not inhibited by NAL. Studies on receptor binding of (125)I-labeled IMN to T lymphocytes revealed that it binds with high affinity to NAL-insensitive binding sites (K(d) = 7.0 +/- 0.3 nM). Unlabeled beta-END completely inhibited the specific binding of (125)I-labeled IMN to NAL-insensitive binding sites on T lymphocytes (K(i) = 1.1 +/- 0.2 nM). Thus, beta-END and IMN bind to common NAL-insensitive binding sites on T lymphocytes and enhance Con A-induced proliferation of these cells.     

Gene conversion and crossing over along the 405-kb left arm of Saccharomyces cerevisiae chromosome VII

Gene conversions and crossing over were analyzed along 10 intervals in a 405-kb region comprising nearly all of the left arm of chromosome VII in Saccharomyces cerevisiae. Crossover interference was detected in all intervals as measured by a reduced number of nonparental ditypes. We have evaluated interference between crossovers in adjacent intervals by methods that retain the information contained in tetrads as opposed to single segregants. Interference was seen between intervals when the distance in the region adjacent to a crossover was < approximately 35 cM (90 kb). At the met13 locus, which exhibits approximately 9% gene conversions, those gene conversions accompanied by crossing over exerted interference in exchanges in an adjacent interval, whereas met13 gene conversions without an accompanying exchange did not show interference. The pattern of exchanges along this chromosome arm can be represented by a counting model in which there are three nonexchange events between adjacent exchanges; however, maximum-likelihood analysis suggests that approximately 8-12% of the crossovers on chromosome VII arise by a separate, noninterfering mechanism.     

Large inverted repeats in the vicinity of a single double-strand break strongly affect repair in yeast diploids lacking Rad51

DNA double-strand breaks (DSBs) are critical lesions that can lead to cell death or chromosomal rearrangements. Rad51 is necessary for most mitotic and meiotic DSB repair events, although a number of RAD51-independent pathways exist. Previously, we described DSB repair in rad51Delta yeast diploids that was stimulated by a DNA region termed "facilitator of break-induced replication" (FBI) located approximately 30kb from the site of an HO-induced DSB. Here, we demonstrate that FBI is a large inverted DNA repeat that channels the repair of DSBs into the single-strand annealing-gross chromosomal rearrangements (SSA-GCR) pathway. Further, analysis of DSB repair in rad54Delta cells allowed us to propose that the SSA-GCR repair pathway is suppressed in the presence of Rad51p. Therefore, an additional role of Rad51 might be to protect eukaryotic genomes from instabilities by preventing chromosomal rearrangements.     

Spectral and spectral-temporal heart rate analysis in newborns

Spectral (in 3-min segments) and spectral-temporal (in 36-s windows with a 9-s step) analyses were carried out on the basis of cardiointerval recordings of newborns (full-term and preterm) during 24 h. It was found that each of the 3-min intervals of the 24-h cardiointerval recordings in the newborns had a unique spectrum; the spectra could be combined into several types. During 24 h, a spectrum with a marked LF component prevailed in the newborns. A spectrum with a peak in the HF region recorded in the newborns in the range from 0.4 to ～1 Hz was an indicator of the rhythmic pattern of the variation of cardiointervals related to respiratory waves. Owing to the diversity of patterns of the spectral behavior of cardiointervals in a newborn during 24 h, no single short segment of the cardiointerval recording could serve as an unambiguous characteristic of the newborn’s physiological state. The actual heart rate variability pattern could be seen by means of the spectraltemporal analysis, visualizing the dynamics of conversion of one spectral type to another, i.e., the change of the dominant system of regulation.     

RAD50 Is Required for Efficient Initiation of Resection and Recombinational Repair at Random, γ-Induced Double-Strand Break Ends

Resection of DNA double-strand break (DSB) ends is generally considered a critical determinant in pathways of DSB repair and genome stability. Unlike for enzymatically induced site-specific DSBs, little is known about processing of random “dirty-ended” DSBs created by DNA damaging agents such as ionizing radiation. Here we present a novel system for monitoring early events in the repair of random DSBs, based on our finding that single-strand tails generated by resection at the ends of large molecules in budding yeast decreases mobility during pulsed field gel electrophoresis (PFGE). We utilized this “PFGE-shift” to follow the fate of both ends of linear molecules generated by a single random DSB in circular chromosomes. Within 10 min after γ-irradiation of G2/M arrested WT cells, there is a near-synchronous PFGE-shift of the linearized circular molecules, corresponding to resection of a few hundred bases. Resection at the radiation-induced DSBs continues so that by the time of significant repair of DSBs at 1 hr there is about 1–2 kb resection per DSB end. The PFGE-shift is comparable in WT and recombination-defective rad52 and rad51 strains but somewhat delayed in exo1 mutants. However, in rad50 and mre11 null mutants the initiation and generation of resected ends at radiation-induced DSB ends is greatly reduced in G2/M. Thus, the Rad50/Mre11/Xrs2 complex is responsible for rapid processing of most damaged ends into substrates that subsequently undergo recombinational repair. A similar requirement was found for RAD50 in asynchronously growing cells. Among the few molecules exhibiting shift in the rad50 mutant, the residual resection is consistent with resection at only one of the DSB ends. Surprisingly, within 1 hr after irradiation, double-length linear molecules are detected in the WT and rad50, but not in rad52, strains that are likely due to crossovers that are largely resection- and RAD50-independent.     

Hormone activity of a synthetic decapeptide with the adrenocorticotropin-like sequence of human immunoglobulin G1

The antiproliferative and immunosuppressivein vitro effects ofimmunocortin, a synthetic adrenocorticotropin-like (ACTH-like) decapeptide H-Val-Lys-Lys-Pro-Gly-Ser-Ser-Val-Lys-Val-OH, whose sequence corresponds to segment 11–20 of the variable part of the human IgG1 heavy chain, were studied. At concentrations of 10⁻¹¹−10⁻⁷ M, immunocortin was found to inhibit the growth of the human MT-4 T-lymphoblastoid cell line, to suppress the blast transformation of thymocytes, and to decrease the spontaneous mobility of peritoneal macrophages and their bactericidal action toward the virulent strainSalmonella typhimurium 415. By using a¹²⁵I-labeled “addressing” fragment of ACTH {[¹²⁵I]ACTH (13–24)}, we showed that MT-4 cells express specific receptors for ACTH (K _d 97 pM). Immunocortin and human ACTH (but not the heavy chain of IgG1) competitively inhibited the binding of [¹²⁵I]ACTH-(13–24) to these receptors withK _i1 of 0.38 andK _i2 of 0.34 nM, respectively. Specific receptors for ACTH (K _d 5.8 nM) on mouse thymocytes were detected and characterized. The unlabeled immunocortin was shown to compete with labeled ACTH-(13–24) for binding to these receptors (K _i=1.8 nM), and this binding of immunocortin to receptors on thymocytes activates adenylate cyclase from these cells and increases the intracellular concentration of cAMP.