Accumulation of cesium and radiocesium in forest litter in selected regions of poland and its influence on litter-to-mushroom transfer factor

The aim of this work was to check whether the stable cesium content in forest litter affects the value of radiocesium from litter-to-mushroom transfer factorTf or not. Total cesium in litter, measured by AAS, varied from 0.1–2.7 μg/g. These data, combined with earlier results for mushrooms, showed no simple correlation forTf. More complex relationships provided very high correlation coefficients, but their validity needs further investigation.     

Influence of nitric oxide on the secretory function of the bovine corpus luteum: dependence on cell composition and cell-to-cell communication

The objective of the present study was to investigate the role of cell-to-cell contact in the influence of nitric oxide (NO) on the secretory function of the bovine corpus luteum (CL). In Experiment 1, separate small luteal cells (SLC) or large (LLC) luteal cells were perfused with 100 micro M spermineNONOate, a NO donor, or with 100 micro M Nomega-nitro-L-arginine methyl ester (L-NAME), a NO synthase (NOS) inhibitor; in Experiment 2, a mixture of LLC and SLC and endothelial cells was cultured and incubated with spermineNONOate or L-NAME; in Experiment 3, spermineNONOate was perfused into the CL (100 mg/4 hr) by a microdialysis system in vivo. Perfusion of isolated SLC and LLC with the NO donor or NOS inhibitor (Experiment 1) did not affect (P > 0.05) secretion of progesterone (P(4)) or oxytocin (OT). L-NAME perfusion increased (P < 0.05) leukotriene C(4) (LTC(4)) secretion by both SLC and LLC cells. Treatment of mixtures of luteal cells with an NO donor (Experiment 2) significantly decreased (P < 0.001) secretion of P(4) and OT and increased (P < 0.001) production of prostaglandin F(2alpha) (PGF(2alpha)) and LTC(4). L-NAME stimulated (P < 0.001) P(4) secretion, but did not influence (P > 0.05) OT, PGF(2alpha) or LTC(4) production. Intraluteal administration (Experiment 3) of spermineNONOate increased (P < 0.001) LTC(4) and PGF(2alpha), decreased OT, but did not change P(4) levels in perfusate samples. These data indicate that cell-to-cell contact and cell composition play important roles in the response of bovine CL to treatment with NO donors or NOS inhibitors, and that paracrine mechanisms are required for the full secretory response of the CL in NO action. Endothelial cells appear to be required for the full secretory response of the CL to NO.     

Immunosuppressive activity of antamanide and some of its analogues

In connection with our discovery of a strong immunosuppressive activity of cyclolinopeptide A (CLA), we investigated immunosuppressive properties of antamanide and a number of its analogues, including symmetrical antamanide, and compared them with the activities of cyclosporin A and CLA. The peptides were investigated by using plaque forming cell (PFC), graft-versus-host (GvH), delayed type hypersensitivity (DTH), and autologous rosette formation cell (ARFC) tests. Antamanide and symmetrical antamanide exhibit an immunosuppressive activity lower than CLA. Linear antamanide fragments are also active. At higher concentrations of the latter peptides, toxic effects occur.     

Kinetic studies of ATP synthase: The case for the positional change mechanism

The mitochondrial ATP synthases shares many structural and kinetic properties with bacterial and chloroplast ATP synthases. These enzymes transduce the energy contained in the membrane's electrochemical proton gradients into the energy required for synthesis of high-energy phosphate bonds. The unusual three-fold symmetry of the hydrophilic domain, F₁, of all these synthases is striking. Each F₁ has three identical subunits and three identical subunits as well as three additional subunits present as single copies. The catalytic site for synthesis is undoubtedly contained in the subunit or an , interface, and thus each enzyme appears to contain three identical catalytic sites. This review summarizes recent isotopic and kinetic evidence in favour of the concept, originally proposed by Boyer and coworkers, that energy from the proton gradient is exerted not directly for the reaction at the catalytic site, but rather to release product from a single catalytic site. A modification of this binding change hypotheses is favored by recent data which suggest that the binding change is due to a positional change in all three subunits relative to the remaining subunits of F₁ and F₀ and that the vector of rotation is influenced by energy. The positional change, or rotation, appears to be the slow step in the process of catalysis and it is accelerated in all F₁F₀ ATPases studied by substrate binding and by the proton gradient. However, in the mammalian mitochondrial enzyme, other types of allosteric rate regulation not yet fully elucidated seem important as well.     

Histone H3 lysine 27 acetylation is altered in colon cancer

Background

Histone post-translational modifications (PTMs) play an important role in the regulation of the expression of genes, including those involved in cancer development and progression. However, our knowledge of PTM patterns in human tumours is limited.

Methods

MS-based analyses were used to quantify global alterations of histone PTMs in colorectal cancer (CRC) samples. Histones isolated from 12 CRCs and their corresponding normal mucosa by acidic extraction were separated by SDS-PAGE and analysed by liquid chromatography-mass spectrometry.

Results

Among 96 modified peptides, 41 distinct PTM sites were identified, of which 7, 13, 11, and 10 were located within the H2A, H2B, H3, and H4 sequences, respectively, and distributed among the amino-terminal tails and the globular domain of the four histones. Modification intensities were quantified for 33 sites, of which 4 showed significant (p-value ≤ 0.05) differences between CRC tissues and healthy mucosa samples. We identified histone H3 lysine 27 acetylation (H3K27Ac) as a modification upregulated in CRC, which had not been shown previously.

Conclusions

The present results indicate the usefulness of a bottom-up proteomic approach for the detection of histone modifications at a global scale. The differential abundance of H3K27Ac mark in CRC, a PTM associated with active enhancers, suggests its role in regulating genes whose expression changes in CRC.     

Ultrastructure of alimentary tract formation in embryos of two insect species: Melasoma saliceti and Chrysolina pardalina (Coleoptera, Chrysomelidae)

Embryogenesis of the alimentary tract in two chrysomelid species (Chrysolina pardalina and Melasoma saliceti) is described. The embryonic development of both species lasts 7days at room temperature. Stomodaeum and proctodaeum invaginate at the anterior and posterior ends of the germ band. Together with the ectodermal tissue the endoderm cells also enter into the embryo. The anterior and posterior parts of the alimentary tract wedge into the yolk in the form of conical structures. The endodermal cells remain at the yolk surface and start migration over the yolk mass as two lateral bands of cells. The endoderm is always accompanied by mesoderm. On the fifth day of development the endodermal cells together with the mesoderm layer spread over the ventral and dorsal sides of the yolk mass and form the single layered primordium of the midgut epithelium. On the sixth day of development a basal lamina appears between the endoderm and the mesoderm cells and differentiation of both tissues starts. The endodermal epithelium cells change shape from flat to cuboidal and eventually into columnar. Mesoderm cells differentiate into muscle and tracheae. On the 7thday of development stomodaeum and proctodaeum become lined with cuticle and the midgut becomes covered with microvilli. The yolk cells populating the yolk mass do not contribute to midgut formation in the species studied.     

Characterization of human DHRS6, an orphan short chain dehydrogenase/reductase enzyme: a novel, cytosolic type 2 R-beta-hydroxybutyrate dehydrogenase

Human DHRS6 is a previously uncharacterized member of the short chain dehydrogenases/reductase family and displays significant homologies to bacterial hydroxybutyrate dehydrogenases. Substrate screening reveals sole NAD(+)-dependent conversion of (R)-hydroxybutyrate to acetoacetate with K(m) values of about 10 mm, consistent with plasma levels of circulating ketone bodies in situations of starvation or ketoacidosis. The structure of human DHRS6 was determined at a resolution of 1.8 A in complex with NAD(H) and reveals a tetrameric organization with a short chain dehydrogenases/reductase-typical folding pattern. A highly conserved triad of Arg residues ("triple R" motif consisting of Arg(144), Arg(188), and Arg(205)) was found to bind a sulfate molecule at the active site. Docking analysis of R-beta-hydroxybutyrate into the active site reveals an experimentally consistent model of substrate carboxylate binding and catalytically competent orientation. GFP reporter gene analysis reveals a cytosolic localization upon transfection into mammalian cells. These data establish DHRS6 as a novel, cytosolic type 2 (R)-hydroxybutyrate dehydrogenase, distinct from its well characterized mitochondrial type 1 counterpart. The properties determined for DHRS6 suggest a possible physiological role in cytosolic ketone body utilization, either as a secondary system for energy supply in starvation or to generate precursors for lipid and sterol synthesis.     

In vitro activity of oxazaphosphorines in childhood acute leukemia: preliminary report

Glufosfamide (beta-D-glucosyl-ifosfamide mustard) is a new agent for cancer chemotherapy. Its pharmacology is similar to commonly used oxazaphosphorines, but it does not require activation by hepatic cytochrome P-450 and preclinically demonstrates lower nephrotoxicity and myelosuppression than ifosfamide. The aim of the study was a comparison of the drug resistance profiles of glufosfamide and other oxazaphosphorines in childhood acute leukemias. Leukemic cells, taken from children with ALL on diagnosis (n = 41), ALL on relapse (n = 12) and AML on diagnosis (n = 13) were analyzed by means of the MTT assay. The following drugs were tested: glufosfamide (GLU), 4-HOO-ifosfamide (IFO), 4-HOO-cyclophosphamide (CYC) and mafosfamide cyclohexylamine salt (MAF). In the group of initial ALL samples median cytotoxicity values for GLU, IFO, CYC and MAF were 15.5, 33.8, 15.7 and 7.8 microM, respectively. In comparison with initial ALL samples, the relative resistance for GLU and IFO in relapsed ALL samples was 1.9 (p = 0.049) and 1.3 (ns), and in initial AML samples 31 (p < 0.001) and 5 (p = 0.001), respectively. All oxazaphosphorines presented highly significant cross-resistance. Glufosfamide presented high activity against lymphoblasts both on diagnosis and on relapse.     

Localization of human chorionic gonadotropin beta subunit transcripts in ovarian cancer tissue

Recent studies demonstrated that besides placenta and malignant trophoblastic tumors, hCG and especially its beta-subunit is secreted by a varieties of tumors of different origin. The aim of the present investigation was to determine the expression pattern of human chorionic gonadotropin gene in ovarian cancer tissue. The study included 8 patients with epithelial ovarian carcinoma. The expression and distribution of hCGbeta mRNA was assessed by in situ RT-PCR method. The semi-quantitative assessment was performed using computer image analysis. Transformation of the images into the pseudocolour scale showed a clear difference in fluorescence intensity among individual cancer cells. The intensity of ISRT-PCR products corresponding with expression level of hCGbeta demonstrated that its production by individual cancer cells is different. In all studied specimens of the ovarian carcinoma tissue, cancer cells characterized by the presence of active hCGbeta gene were found, whereas noncancerous tissue demonstrated lack of the gene expression. Thus, the study clearly shows that the expression of hCGbeta is the feature of ovarian cancer tissue.