Xanthoria parietina as a biomonitor of airborne heavy metal pollution in forest sites in the North East of Morocco

Xanthoria parietina, common foliose lichen, growing in its natural habitat, was analysed for the concentration of five heavy metals (Fe, Cr, Zn, Pb and Cu) from different forest sites of North East of Morocco (Kenitra, Sidi Boughaba, Mkhinza, Ceinture Verte near Temara city, Skhirate, Bouznika and Mohammedia). The quantification was carried out by inductively coupled plasma - atomic emission spectrometry (ICP-AES). Results were highly significant p<0,001. The concentration of metals is correlated with the vehicular activity and urbanization. The total metal concentration is highest at the Kenitra area, followed by Ceinture Verte site near Temara city, which experience heavy traffic throughout the year. Scanning electron microscopy (SEM) of particulate matter on lichen of Xanthoria parietina was assessed as a complementary technique to wet chemical analysis for source apportionment of airborne contaminant. Analysis revealed high level of Cu, Cr, Zn and Pb in samples near roads.  

IN SITU AND IN VITRO IMMUNOLOCALIZATION OF OVIDUCTIN BINDING SITES ON HAMSTER UTERINE EPITHELIAL CELLS AND DETECTION OF A HAMSTER OVIDUCTIN HOMOLOGUE IN THE FEMALE RAT REPRODUCTIVE TRACT

Oviductin is an oviduct-specific and high-molecular-weight glycoprotein that has been suggested to play important roles in the early events of reproduction. The present study was undertaken to localize the oviductin binding sites in the uterine epithelial cells of the golden hamster (Mesocricetus auratus) both in situ and in vitro, and to detect a hamster oviductin homologue in the female rat reproductive tract. Immunohistochemical localization of oviductin in the hamster uterus revealed certain uterine epithelial cells reactive to the monoclonal anti-hamster oviductin antibody. In order to study the interaction between hamster oviductin and the endometrium in vitro, a method for culturing primary hamster uterine epithelial cells has been established and optimized. Study with confocal microscopy of the cell culture system showed a labeling pattern similar to what was observed using immunohistochemistry. Pre-embedding immunolabeling of cultured uterine epithelial cells also showed gold particles associated with the plasma membrane and microvilli. These results demonstrated that hamster oviductin can bind to the plasma membrane of certain hamster uterine epithelial cells, suggesting the presence of a putative oviductin receptor on the uterine epithelial cell surface. In the second part of the present study, using the monoclonal anti-hamster oviductin antibody that cross-reacts with the rat tissue, we have been able to detect an oviduct-specific glycoprotein, with a molecular weight of 180~300kDa, in the female rat reproductive tract. Immunohistochemical labeling of the female rat reproductive tract revealed a strong immunolabeling in the non-ciliated oviductal epithelial cells and a faint immunoreaction on the cell surface of some uterine epithelial cells. Ultrastructurally, immunogold labeling was restricted to the secretory granules, Golgi apparatus, and microvilli of the non-ciliated secretory cells of the oviduct. In the uterus, immunogold labeling was observed on the cell surface of some uterine epithelial cells. Furthermore, electron micrographs of ovulated oocytes showed an intense immunolabeling for rat oviductin within the perivitelline space surrounding the ovulated oocytes. The findings of the present study demonstrated that oviductin is present in the rat oviduct and uterus, and it appears that, in the rat, oviductin is secreted by the non-ciliated secretory cells of the oviduct.

Reversible Photocontrol of Deoxyribozyme-Catalyzed RNA Cleavage under Multiple-Turnover Conditions

Lights, camera, action! Photoswitchable nucleoside analogues containing o-, m-, or p-azobenzenes can be inserted in the catalytic core of RNA-cleaving 10-23 deoxyribozymes by replacing a nonconserved residue (see picture). Irradiation of the modified deoxyribozymes at 366 nm enhances RNA cleavage rates up to ninefold, thus achieving the rates observed for the unmodified deoxyribozyme.

Synthesis of N3- and 2-NH2-substituted 6,7-diphenylpterins and their use as intermediates for the preparation of oligonucleotide conjugates designed to target photooxidative damage on single-stranded DNA representing the bcr-abl chimeric gene

Two 17-mer oligodeoxynucleotide-5'-linked-(6,7-diphenylpterin) conjugates, 2 and 3, were prepared as photosensitisers for targeting photooxidative damage to a 34-mer DNA oligodeoxynucleotide (ODN) fragment 1 representing the chimeric bcr-abl gene that is implicated in the pathogenesis of chronic myeloid leukaemia (CML). The base sequence in the 17-mer was 3'G G T A G T T A T T C C T T C T T5'. In the first of these ODN conjugates (2) the pterin was attached at its N3 atom, via a -(CH2)3OPO(OH)- linker, to the 5'-OH group of the ODN. Conjugate 2 was prepared from 2-amino-3-(3-hydroxypropyl)-6,7-diphenyl-4(3H)-pteridinone 10, using phosphoramidite methodology. Starting material 10 was prepared from 5-amino-7-methylthiofurazano[3,4-d]pyrimidine 4 via an unusual highly resonance stabilised cation 8, incorporating the rare 2H,6H-pyrimido[6,1-b][1,3]oxazine ring system. In the characterisation of 10 two pteridine phosphazenes, 15 and 29, were obtained, as well as new products containing two uncommon tricyclic ring systems, namely pyrimido[2,1-b]pteridine (20 and 24) and pyrimido[1,2-c]pteridine (27). In the second ODN conjugate the linker was -(CH2)5CONH(CH2)6OPO(OH)- and was attached to the 2-amino group of the pterin. In the preparation of 3, the N-hydroxysuccinimide ester 37 of 2-(5-carboxypentylamino)-6,7-diphenyl-4(3H)-pteridinone was condensed with the hexylamino-modified 17-mer. Excitation of 36 with near UV light in the presence of the single-stranded target 34-mer, 5'T G A C C A T C A A T A A G14 G A A G18 A A G21 C C C T T C A G C G G C C3' 1 caused oxidative damage at guanine bases, leading to alkali-labile sites which were monitored by polyacrylamide gel electrophoresis. Cleavage was observed at all guanine sites with a marked preference for cleavage at G14. In contrast, excitation of ODN-pteridine conjugate 2 in the presence of 1 caused oxidation of the latter predominantly at G18, with a smaller extent of cleavage at G15 and G14 (in the double-stranded portion) and G21. These results contrast with our previous observation of specific cleavage at G21 with ruthenium polypyridyl sensitisers, and suggest that a different mechanism, probably one involving Type 1 photochemical electron transfer, is operative. Much lower yields were found with the ODN-pteridine conjugate 3, perhaps as a consequence of the longer linker between the ODN and the pteridine in this case.

The purification and characterization of phosphonopyruvate hydrolase, a novel carbon-phosphorus bond cleavage enzyme from Variovorax sp. Pal2.

Phosphonopyruvate hydrolase, a novel bacterial carbon-phosphorus bond cleavage enzyme, was purified to homogeneity by a series of chromatographic steps from cell extracts of a newly isolated environmental strain of Variovorax sp. Pal2. The enzyme was inducible in the presence of phosphonoalanine or phosphonopyruvate; unusually, its expression was independent of the phosphate status of the cell. The native enzyme had a molecular mass of 63 kDa with a subunit mass of 31.2 kDa. Activity of purified phosphonopyruvate hydrolase was Co2+-dependent and showed a pH optimum of 6.7–7.0. The enzyme had a Km of 0.53 mM for its sole substrate, phosphonopyruvate, and was inhibited by the analogues phosphonoformic acid, 3-phosphonopropionic acid, and hydroxymethylphosphonic acid. The nucleotide sequence of the phosphonopyruvate hydrolase structural gene indicated that it is a member of the phosphoenolpyruvate phosphomutase/isocitrate lyase superfamily with 41% identity at the amino acid level to the carbon-to-phosphorus bond-forming enzyme phosphoenolpyruvate phosphomutase from Tetrahymena pyriformis. Thus its apparently ancient evolutionary origins differ from those of each of the two carbon-phosphorus hydrolases that have been reported previously; phosphonoacetaldehyde hydrolase is a member of the haloacetate dehalogenase family, whereas phosphonoacetate hydrolase belongs to the alkaline phosphatase superfamily of zinc-dependent hydrolases. Phosphonopyruvate hydrolase is likely to be of considerable significance in global phosphorus cycling, because phosphonopyruvate is known to be a key intermediate in the formation of all naturally occurring compounds that contain the carbon-phosphorus bond.

Coronavirus Main Proteinase (3CLpro) Structure: Basis for Design of Anti-SARS Drugs

A novel coronavirus has been identified as the causative agent of severe acute respiratory syndrome (SARS). The viral main proteinase (Mpro, also called 3CLpro), which controls the activities of the coronavirus replication complex, is an attractive target for therapy. We determined crystal structures for human coronavirus (strain 229E) Mpro and for an inhibitor complex of porcine coronavirus [transmissible gastroenteritis virus (TGEV)] Mpro, and we constructed a homology model for SARS coronavirus (SARS-CoV) Mpro. The structures reveal a remarkable degree of conservation of the substrate-binding sites, which is further supported by recombinant SARS-CoV Mpro-mediated cleavage of a TGEV Mpro substrate. Molecular modeling suggests that available rhinovirus 3Cpro inhibitors may be modified to make them useful for treating SARS.