Investigation of histone proteins in plant nuclei possessing different ultrastructural organization

Summary According to Nagl and Fusenig (1979) the structure and ultrastructure of plant nuclei is species-specific and is determined by the DNA (2C) value and the amount of the repetitive DNA. Light and electron microscopic observations ofZea mays L.,Pisum sativum L., andPhaseolus vulgaris L. nuclei led us to define their organization as chromonematic, chronomeric and chromocentric, respectively. Nuclear proteins, soluble in 0.4N H₂SO₄ and 0.74M HC1O₄, were extracted from isolated nuclei and resolved according to their solubility and mobility in SDS and acetic acid-urea PAGE and 2D-Triton X 100 PAGE. Differences in the variants (and modifications) of the H 1 histone class and the nucleosomal H 2 A, H 2 B, and H 3 isoforms probably reflect that species-specific nuclear ultrastructure is based, not only on the heterogeneity and the quantity of DNA, but also on the diversity of the protein component of chromatin.Abbreviations MES Morpholinoethane sulfonic acid - PMSF phenylmethylsulphonyl fluoride - DMSO dimethylsulfoxid - SDS sodium dodecylsulfate - TEMED N, N, N N-tetramethylethylen-diamin - PAGE polyacrylamide gel electrophoresis     

Fertility of male and female mice heterozygous for the reciprocal translocation T(7;17)3BKM.

The present paper describes the fertility of male and female mice heterozygous for the reciprocal translocation T(7;17)3BKM. This translocation was induced by gamma rays in the spermatozoa of an irradiated parent. It is characterized by "asymmetrical" localization of the breakpoints, distally in Chromosome 7 (7F5) and proximally in Chromosome 17 (17B1). The data presented here relate only those matings in which, for both partners, heterozygosity or normality could be confirmed cytogenetically. The results indicate that both male and female translocation heterozygotes are fertile, their mean litter size being reduced to about 50% of that of normal littermates. This leads to the conclusion that the multivalents mainly undergo either alternate or adjacent-1 2:2 segregation. No viable tertiary trisomics were observed among the progeny of the translocation carriers. Analysis of the frequency of the different types of multivalents in diakinesis-metaphase I spermatocytes showed a significant predominance of chain-type figures (CIV and CIII+I), with chains of four elements (CIV) being more frequent than other configurations. This demonstrates that the small marker chromosome remains attached by one of its segments to the tetravalent.     

Biological peculiarities of someYersinia species: strain-dependent virulence and strain-dependent stress proteins

A pair ofYersinia enterocolitica serotype O∶3 strains — incubated in growth medium with 10% NaCl and 2 mM glycin betaine at 4 °C, were used to study the plasmid role in the infection of BALB/c mice. The isogenic plasmid-bearing strain, but not its plasmidless derivative, caused enteric infection and histological changes in intestines, stomach and liver of the mice. Two strainsY. enterocolitica andYersinia pseudotuberculosis were incubated at different temperatures (4 and 25 °C) in media, supplemented with different concentrations of NaCl. Two concentrations of betaine as osmoprotector were tested. The initial strains and their substrains were characterised by protein profiles using sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Results show that in salinity conditions, the presence of osmoprotectant (betaine) as well as the temperature of cultivation plays a great role in the expression of some bacterial proteins. The manner in which the different strains answer to the stress situations is specific for each of them.     

Restriction of de novo pyrimidine biosynthesis inhibits Th1 cell activation and promotes Th2 cell differentiation

Leflunomide, an inhibitor of de novo pyrimidine biosynthesis, has recently been introduced as a treatment for rheumatoid arthritis in an attempt to ameliorate inflammation by inhibiting lymphocyte activation. Although the immunosuppressive ability of leflunomide has been well described in several experimental animal models, the precise effects of a limited pyrimidine supply on T cell differentiation and effector functions have not been elucidated. We investigated the impact of restricted pyrimidine biosynthesis on the activation and differentiation of CD4 T cells in vivo and in vitro. Decreased activation of memory CD4 T cells in the presence of leflunomide resulted in impaired generation and outgrowth of Th1 effectors without an alteration of Th2 cell activation. Moreover, priming of naive T cells in the presence of leflunomide promoted Th2 differentiation from uncommitted precursors in vitro and enhanced Th2 effector functions in vivo, as indicated by an increase in Ag-specific Th2 cells and in the Th2-dependent Ag-specific Ig responses (IgG1) in immunized mice. The effects of leflunomide on T cell proliferation and differentiation could be antagonized by exogenous UTP, suggesting that they were related to a profound inhibition of de novo pyrimidine biosynthesis. These results indicate that leflunomide might exert its anti-inflammatory activities in the treatment of autoimmune diseases by preventing the generation of proinflammatory Th1 effectors and promoting Th2 cell differentiation. Moreover, the results further suggest that differentiation of CD4 T cells can be regulated at the level of nucleotide biosynthesis.     

Structure–activity relationship of dihydroxy-4-methylcoumarins as powerful antioxidants: Correlation between experimental & theoretical data and synergistic effect

The chain-breaking antioxidant activities of eight coumarins [7-hydroxy-4-methylcoumarin (1), 5,7-dihydroxy-4-methylcoumarin (2), 6,7-dihydroxy-4-methylcoumarin (3), 6,7-dihydroxycoumarin (4), 7,8-dihydroxy-4-methylcoumarin (5), ethyl 2-(7,8-dihydroxy-4-methylcoumar-3-yl)-acetate (6), 7,8-diacetoxy-4-methylcoumarin (7) and ethyl 2-(7,8-diacetoxy-4-methylcoumar-3-yl)-acetate (8)] during bulk lipid autoxidation at 37 °C and 80 °C in concentrations of 0.01–1.0 mM and their radical scavenging activities at 25 °C using TLC–DPPH test have been studied and compared. It has been found that the o-dihydroxycoumarins 3–6 demonstrated excellent activity as antioxidants and radical scavengers, much better than the m-dihydroxy analogue 2 and the monohydroxycoumarin 1. The substitution at the C-3 position did not have any effect either on the chain-breaking antioxidant activity or on the radical scavenging activity of the 7,8-dihydroxy- and 7,8-diacetoxy-4-methylcoumarins 6 and 8. The comparison with DL-α-tocopherol (TOH), caffeic acid (CA) and p-coumaric acid (p-CumA) showed that antioxidant efficiency decreases in the following sequence:     

BANMOKI: a searchable database of homology-based 3D models and their electrostatic properties of five bacterial nucleoside monophosphate kinase families

The nucleoside monophosphate kinases (NMPK) are important enzymes that control the ratio of mono- and di-phosphate nucleosides and participate in gene regulation and signal transduction in the cell. However, despite their importance only several 3D structures were experimentally determined in contrast to the wealth of sequences available for each of the NMPK families. To fill this gap we present a Web-based database containing structural models for all proteins of the five bacterial nucleoside monophosphate kinase (bNMPK) families. The models were computed by means of homology-based approach using a few experimentally determined bNMPK structures. The database also contains pK(a) values and their components calculated for the homology-based 3D models, which is a unique feature of the database. The BActerial Nucleoside MOnophosphate KInases (BANMOKI) database is freely accessible (http://www.ces.clemson.edu/compbio/banmoki) and offers an easy user-friendly interface for browsing, searching and downloading content of the database. The users can investigate, using the searching tools of the database, the properties of the bNMP kinases in respect to sequence composition, electrostatic interactions and structural differences.     

A mitochondrial stratigraphy for island southeast Asia

Island Southeast Asia (ISEA) was first colonized by modern humans at least 45,000 years ago, but the extent to which the modern inhabitants trace their ancestry to the first settlers is a matter of debate. It is widely held, in both archaeology and linguistics, that they are largely descended from a second wave of dispersal, proto-Austronesian-speaking agriculturalists who originated in China and spread to Taiwan approximately 5,500 years ago. From there, they are thought to have dispersed into ISEA approximately 4,000 years ago, assimilating the indigenous populations. Here, we demonstrate that mitochondrial DNA diversity in the region is extremely high and includes a large number of indigenous clades. Only a fraction of these date back to the time of first settlement, and the majority appear to mark dispersals in the late-Pleistocene or early-Holocene epoch most likely triggered by postglacial flooding. There are much closer genetic links to Taiwan than to the mainland, but most of these probably predated the mid-Holocene "Out of Taiwan" event as traditionally envisioned. Only approximately 20% at most of modern mitochondrial DNAs in ISEA could be linked to such an event, suggesting that, if an agriculturalist migration did take place, it was demographically minor, at least with regard to the involvement of women.     

Intravenous Immunoglobulin with Enhanced Polyspecificity Improves Survival in Experimental Sepsis and Aseptic Systemic Inflammatory Response Syndromes

Sepsis is a major cause for death worldwide. Numerous interventional trials with agents neutralizing single proinflammatory mediators have failed to improve survival in sepsis and aseptic systemic inflammatory response syndromes. This failure could be explained by the widespread gene expression dysregulation known as “genomic storm” in these patients. A multifunctional polyspecific therapeutic agent might be needed to thwart the effects of this storm. Licensed pooled intravenous immunoglobulin preparations seemed to be a promising candidate, but they have also failed in their present form to prevent sepsis-related death. We report here the protective effect of a single dose of intravenous immunoglobulin preparations with additionally enhanced polyspecificity in three models of sepsis and aseptic systemic inflammation. The modification of the pooled immunoglobulin G molecules by exposure to ferrous ions resulted in their newly acquired ability to bind some proinflammatory molecules, complement components and endogenous “danger” signals. The improved survival in endotoxemia was associated with serum levels of proinflammatory cytokines, diminished complement consumption and normalization of the coagulation time. We suggest that intravenous immunoglobulin preparations with additionally enhanced polyspecificity have a clinical potential in sepsis and related systemic inflammatory syndromes.     

Candida albicans double-stranded DNA can participate in the host defense against disseminated candidiasis

In the present work, we studied the in vitro immunomodulatory properties of double-stranded Candida albicans DNA and its protective effect in murine disseminated candidiasis. DNA induced the production of TNF-alpha by peritoneal macrophages and splenocytes in vitro through a chloroquine-dependent mechanism. Yeast DNA acted synergistically with IFN-gamma in triggering the secretion of nitric oxide by macrophages and enabled them to stimulate the proliferation of T cells in response to soluble anti-CD3. The effect of DNA on splenocytes is associated with an enhanced synthesis of IFN-gamma, IL-2 and IL-10. In vivo, DNA decreased the mortality and lowered the kidney contamination in mice intraperitoneally inoculated with C. albicans simultaneously with an increase in the specific proliferative response and cytokine production. The present results indicate that C. albicans DNA can provide protection against disseminated infection.