Cyanogenesis in glucosinolate-producing plants: Carica papaya and Carica quercifolia

(R)-2-(beta-D-Glucopyranosyloxy)-2-phenylacetonitrile (prunasin) was isolated from Carica papaya L. and C. quercifolia (A. St.-Hil.) Hieron. (syn. C. hastata Brign.). Earlier reported presence of cyclopentanoid cyanohydrin glycosides in C. papaya could not be confirmed, and no cyclopentanoid amino acids could be detected in extracts of C. papaya and C. quercifolia. Conversion of [2,3,4,5,6-3H]phenylalanine into tritiated prunasin was demonstrated in both species. On the other hand, when the plants were administered [2-14C]-2-(2'cyclopentenyl)glycine, extracted, and the extracts hydrolyzed with beta-glucosidase (Helix pomatia), formation of labelled cyanide was not observed. The absence of cyclopentanoids, which are typical for the Passifloraceae, and the inability of Carica species to utilize 2-(2'-cyclopentenyl)glycine as a precursor of cyanogenic glycosides are in agreement with the relative phylogenetic position of the Caricaceae and the Passifloraceae. Carica species are thus rare examples of taxa in which glucosinolates and cyanogenic glycosides co-occur, both types of natural products being derived from the same amino acid, phenylalanine.     

Stimulation of oxygen evolution in photosystem II by copper(II) ions

We have found that copper(II) ions at about equimolar Cu2+/photosystem II (PS II) reaction center proportions stimulate oxygen evolution nearly twofold. This high affinity Cu-binding site is different from the binding sites of Mn and Ca ions. The analysis of the Cu2+ content in PS II preparations isolated from wild-type tobacco and a tobacco mutant deficient in light-harvesting complex suggests that Cu2+ may be a native component of PS II and may take part in the oxygen evolution process. At higher concentrations, Cu2+ ions inhibit oxygen evolution and quench fluorescence.     

Calcium transients in the model of rapidly induced anoxic tolerance in rat cortical slices: involvement of NMDA receptors

In this study, we investigated the effects of NMDA receptor antagonists on calcium transients induced by a single 2-min preconditioning anoxia (PA) in rat olfactory cortical slices, and on the ability of PA to prevent pathological calcium overload induced by subsequent 10-min test anoxia (TA). Relative changes in the intracellular Ca(2+) concentration (Ca(i)) and in the level of Ca(2+) bound to intracellular hydrophobic domains (Ca(b)) were monitored using fura-2 and chlortetracycline, respectively. Our results confirmed that TA induces prominent long-lasting increases in Ca(i) and Ca(b), reflecting cellular calcium overload. It was found that PA produces moderate increases in both Ca(2+) pools and prevents Ca(2+) overload induced by TA carried out 90 min later. Calcium transients and the protective effects of PA were significantly suppressed in slices treated with NMDA receptor antagonists during and 30 min after PA. These results indicate that moderate activation of the NMDA receptors participates in the mechanism of the PA-induced anoxic tolerance of cortical neurons.     

Ex vivo apoptotic potential of peripheral blood mononuclear cells of the elderly human subject

Studies of immunosenescence have led to a detailed knowledge of immune system dysfunctions in the ageing human being. Apoptosis seems to be one of the process regulating an immune response after the antigenic stimulation. We examined whether commonly used methods of assessing apoptosis in the elderly human subject produce comparable results to young subjects. PBMC of young and elderly volunteers were isolated from the venous blood and cultured for 6 or 24 h with antigens of anti-influenza vaccine or PMA. The intensity of apoptosis was measured using the annexinV test, flow cytometric evaluation of DNA content (sub-G1 peak in DNA histograms), 'ladder' by DNA gel electrophoresis, and fluorescence microscope. Apoptosis in 6 h-lasting cultures of the elderly was more intense in annexinV test, while it was decreased assessing subG1 peak. Additionally, in the aged group, those changes were associated with cell cycle arrest. Our results suggest that the apoptosis after the stimulation with the vaccine antigens seems to be some kind of activation-induced cell death (AICD). Different patterns of apoptosis after stimulation may be associated with the cell cycle arrest of the PBMC in the elderly.     

Deletion of deoxyribonucleic acid binding domain of the vitamin D receptor abrogates genomic and nongenomic functions of vitamin D

The vitamin D hormone 1,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)], the biologically active form of vitamin D, is essential for an intact mineral metabolism. Using gene targeting, we sought to generate vitamin D receptor (VDR) null mutant mice carrying the reporter gene lacZ driven by the endogenous VDR promoter. Here we show that our gene-targeted mutant mice express a VDR with an intact hormone binding domain, but lacking the first zinc finger necessary for DNA binding. Expression of the lacZ reporter gene was widely distributed during embryogenesis and postnatally. Strong lacZ expression was found in bones, cartilage, intestine, kidney, skin, brain, heart, and parathyroid glands. Homozygous mice are a phenocopy of mice totally lacking the VDR protein and showed growth retardation, rickets, secondary hyperparathyroidism, and alopecia. Feeding of a diet high in calcium, phosphorus, and lactose normalized blood calcium and serum PTH levels, but revealed a profound renal calcium leak in normocalcemic homozygous mutants. When mice were treated with pharmacological doses of vitamin D metabolites, responses in skin, bone, intestine, parathyroid glands, and kidney were absent in homozygous mice, indicating that the mutant receptor is nonfunctioning and that vitamin D signaling pathways other than those mediated through the classical nuclear receptor are of minor physiological importance. Furthermore, rapid, nongenomic responses to 1,25-(OH)(2)D(3) in osteoblasts were abrogated in homozygous mice, supporting the conclusion that the classical VDR mediates the nongenomic actions of 1,25-(OH)(2)D(3).     

Assessment of RAPD markers for barley doubled haploid lines resistant and susceptible to Fusarium culmorum at seedling and adult plant growth stages

Thirty doubled haploid (DH) lines of barley derived from F(1) of a cross between the six-rowed cultivar Pomo and two-rowed cultivar Maresi were examined for susceptibility to Fusarium seedling blight (SB) and head blight (FHB), measured by mycotoxin (nivalenol) content of kernels. RAPD (random amplified polymorphic DNA) polymorphism was analysed by using 53 decamer primers. Amplification products (APs) were 200 bp up to 2000 bp in size on average 5.7 per primer and the total number of APs was 284, 51.06% of which were polymorphic. Only 32 APs differentiated the examined DH lines - 19 APs for nivalenol content of kernels and 13 for seedling resistance. DH lines segregated with continuous distribution of resistance to FHB and SB. At the seedling stage all DH lines exhibited lower susceptibility than parental cultivars, but in the adult stage only two lines (MP 2 and MP 7) appeared to be more resistant to FHB, i.e. accumulated in kernels a lower amount of mycotoxin than cultivars Maresi and Pomo.     

Morphometric classification of hairy cell leukemia in bone marrow trephine biopsy

OBJECTIVE: To analyze cytologic and histologic parameters in bone marrow trephine biopsy in an attempt to define heterogeneity of hairy cell leukemia cells. STUDY DESIGN: The study group consisted of 28 trephine biopsies. Immunohistochemistry for CD20 antigen was used. Image processing and measurements were performed with AnalySIS 3.0 image analysis system (Soft Imaging System GmbH, Germany) and custom built programs. For planimetric measurements of nuclei, automatic segmentation was implemented. The measured parameters were: surface area, perimeter, minimum, mean and maximum diameter, and a set of form factors. Relative volumes of bone trabeculae, adipose tissue, hematopoietic tissue and neoplastic infiltrate were assessed by the point counting method. Nuclear volume was measured by the point sampled intercept method. Bone marrow fibrosis was assessed using a curvilinear line test system. RESULTS: Significant variability of cell nuclei was found, and their classification into 3 types was possible. The relative frequency of those types was different in various cases and allowed subdivision of cases into 3 groups that differed in some clinical and histologic manifestations. CONCLUSION: The present study demonstrated the heterogeneity of cell populations of hairy cell leukemia.     

Plastoquinones are effectively reduced by ferredoxin:NADP+ oxidoreductase in the presence of sodium cholate micelles. Significance for cyclic electron transport and chlororespiration

The effect of sodium cholate and other detergents (Triton X-100, sodium dodecyl sulphate, octyl glucoside, myristyltrimethylammonium bromide) on the reduction of plastoquinones (PQ) with a different length of the side-chain by spinach ferredoxin:NADP(+) oxidoreductase (FNR) in the presence of NADPH has been studied. Both NADPH oxidation and oxygen uptake due to plastosemiquinone autoxidation were highly stimulated only in the presence of sodium cholate among the used detergents. Sodium cholate at the concentration of 20 mM was found to be the most effective on both PQ-4 and PQ-9-mediated oxygen uptake. The FNR-dependent reduction of plastoquinones incorporated into sodium cholate micelles was stimulated by spinach ferredoxin but inhibited by Mg(2+) ions. It was concluded that the structure of sodium cholate micelles facilitates contact of plastoquinone molecules with the enzyme and creates favourable conditions for the reaction similar to those found in thylakoid membranes for PQ-9 reduction. The obtained results were discussed in terms of the function of FNR as a ferredoxin:plastoquinone reductase both in cyclic electron transport and chlororespiration.