109 research outputs found
Additional data to the stratigraphy and the chronology of the Kostenki 1 (Poliakov) sequence, Voronezh, Russia:Le Sungirien, Saint-Petersbourg 2016
Kostenki 1 is one of the many sites of the Kostenki- Borshchevo site cluster south of Voronezh, which has a long sequence covering the Early and Mid Upper Palaeo- lithic, including the Streletskian Cultural Layer V. Here we present stratigraphic data from our 1994 eldwork (sections of the 1981-1982 excavations) and radiocarbon dates for the CL IV and V. For dating we used our cross- dating approach on high quality conifer charcoal with ABA and ABOx-SC pre-treatment on sub-samples of the same charcoal sample. Our results show that the Strelets- kian CL V dates to ~42,500 14C uncal BP and is signi - cantly older than previously though
G-quadruplex DNA motifs in the malaria parasite Plasmodium falciparum and their potential as novel antimalarial drug targets
G-quadruplexes are DNA or RNA secondary structures that can be formed from guanine-rich nucleic acids. These four-stranded structures, composed of stacked quartets of guanine bases, can be highly stable and have been demonstrated to occur in vivo in the DNA of human cells and other systems, where they play important biological roles, influencing processes such as telomere maintenance, DNA replication and transcription, or, in the case of RNA G-quadruplexes, RNA translation and processing. We report for the first time that DNA G-quadruplexes can be detected in the nuclei of the malaria parasite Plasmodium falciparum, which has one of the most A/T-biased genomes sequenced and therefore possesses few guanine-rich sequences with the potential to form G-quadruplexes. We show that despite this paucity of putative G-quadruplex-forming sequences, P. falciparum parasites are sensitive to several G-quadruplex-stabilizing drugs, including quarfloxin, which previously reached phase 2 clinical trials as an anticancer drug. Quarfloxin has a rapid initial rate of kill and is active against ring stages as well as replicative stages of intraerythrocytic development. We show that several G-quadruplex-stabilizing drugs, including quarfloxin, can suppress the transcription of a G-quadruplex-containing reporter gene in P. falciparum but that quarfloxin does not appear to disrupt the transcription of rRNAs, which was proposed as its mode of action in both human cells and trypanosomes. These data suggest that quarfloxin has potential for repositioning as an antimalarial with a novel mode of action. Furthermore, G-quadruplex biology in P. falciparum may present a target for development of other new antimalarial drugs
Solution structures of the Bacillus cereus metallo-β-lactamase BcII and its complex with the broad spectrum inhibitor R-thiomandelic acid
Metallo-β-lactamases, enzymes which inactivate β-lactam antibiotics, are of increasing biological and clinical significance as a source of antibiotic resistance in pathogenic bacteria. In the present study we describe the high-resolution solution NMR structures of the Bacillus cereus metallo-β-lactamase BcII and of its complex with R-thiomandelic acid, a broad-spectrum inhibitor of metallo-β-lactamases. This is the first reported solution structure of any metallo-β-lactamase. There are differences between the solution structure of the free enzyme and previously reported crystal structures in the loops flanking the active site, which are important for substrate and inhibitor binding and catalysis. The binding of R-thiomandelic acid and the roles of active-site residues are defined in detail. Changes in the enzyme structure upon inhibitor binding clarify the role of the mobile β3–β4 loop. Comparisons with other metallo-β-lactamases highlight the roles of individual amino-acid residues in the active site and the β3–β4 loop in inhibitor binding and provide information on the basis of structure–activity relationships among metallo-β-lactamase inhibitors
Ligand Binding Study of Human PEBP1/RKIP: Interaction with Nucleotides and Raf-1 Peptides Evidenced by NMR and Mass Spectrometry
Background
Human Phosphatidylethanolamine binding protein 1 (hPEBP1) also known as Raf kinase inhibitory protein (RKIP), affects various cellular processes, and is implicated in metastasis formation and Alzheimer's disease. Human PEBP1 has also been shown to inhibit the Raf/MEK/ERK pathway. Numerous reports concern various mammalian PEBP1 binding ligands. However, since PEBP1 proteins from many different species were investigated, drawing general conclusions regarding human PEBP1 binding properties is rather difficult. Moreover, the binding site of Raf-1 on hPEBP1 is still unknown.
Methods/Findings
In the present study, we investigated human PEBP1 by NMR to determine the binding site of four different ligands: GTP, FMN, and one Raf-1 peptide in tri-phosphorylated and non-phosphorylated forms. The study was carried out by NMR in near physiological conditions, allowing for the identification of the binding site and the determination of the affinity constants KD for different ligands. Native mass spectrometry was used as an alternative method for measuring KD values.
Conclusions/Significance
Our study demonstrates and/or confirms the binding of hPEBP1 to the four studied ligands. All of them bind to the same region centered on the conserved ligand-binding pocket of hPEBP1. Although the affinities for GTP and FMN decrease as pH, salt concentration and temperature increase from pH 6.5/NaCl 0 mM/20°C to pH 7.5/NaCl 100 mM/30°C, both ligands clearly do bind under conditions similar to what is found in cells regarding pH, salt concentration and temperature. In addition, our work confirms that residues in the vicinity of the pocket rather than those within the pocket seem to be required for interaction with Raf-1.METASU
Palynological and chemical volatile components of tipically autumnal honeys of the western Mediterranean
[EN] Twenty-five samples of autumnal honeys from the western Mediterranean (Mallorca and Eivissa, Balearic Islands) were examined for pollen content (qualitative and quantitative melissopalynological analysis), moisture, electrical conductivity, colour, sensorial qualities and volatile components. Quantitative analysis showed that the honey contained Maurizio's Class II: 64%, Class III: 28%, Class IV: 4% and Class V: 4%. Fifty-four pollen types, with an average number of 16.68 per sample, were identified, belonging to 29 botanical families. Only two taxa (Ceratonia siliqua and Erica multiflora) were found in all samples. Seventeen samples were unifloral (68%) - ten (40%) of C. siliqua, six (24%) of E. multiflora and one (4%) of Hedera helix. All honeys have a low honeydew index (<?0.09%), while the values for electrical conductivity and water content were high. The major honey volatile components are: cis- and trans-linalool oxides (64.2%) and hotrienol (10.4%) for the carob (C. siliqua) and trans-linalool oxide (13.4%), p-menthane-1,8-diol (11.1%), safranal (9.7%), limonene (5,4%), -pinene (3.7%) and oxoisophorone (3.4%) for the winter heather (E. multiflora).The authors would like to extend their gratitude to the Mallorca Rural 'Leader plus' programme and the beekeepers of Mallorca and Eivissa for their support and friendly collaboration. The authors also thank an anonymous reviewer for useful comments and suggestions on an earlier version of the manuscript.Boi, M.; Llorens Molina, JA.; Cortés, L.; Lladó, G.; Llorens, L. (2013). Palynological and chemical volatile components of tipically autumnal honeys of the western Mediterranean. Grana. 52(2):93-105. doi:10.1080/00173134.2012.744774S93105522Andrade, P. B., Amaral, M. T., Isabel, P., Carvalho, J. C. M. F., Seabra, R. M., & Proença da Cunha, A. (1999). Physicochemical attributes and pollen spectrum of Portuguese heather honeys. Food Chemistry, 66(4), 503-510. doi:10.1016/s0308-8146(99)00100-4Anklam, E. (1998). A review of the analytical methods to determine the geographical and botanical origin of honey. Food Chemistry, 63(4), 549-562. doi:10.1016/s0308-8146(98)00057-0Bosch, J., Del Pino, F. G., Ramoneda, J., & Retana, J. (1996). FRUITING PHENOLOGY AND FRUIT SET OF CAROB, CERATONIA SILIQUA L. (CESALPINACEAE). Israel Journal of Plant Sciences, 44(4), 359-368. doi:10.1080/07929978.1996.10676657Bouseta, A., Collin, S., & Dufour, J.-P. (1992). Characteristic aroma profiles of unifloral honeys obtained with a dynamic headspace GC-MS system. Journal of Apicultural Research, 31(2), 96-109. doi:10.1080/00218839.1992.11101268Cajka, T., Hajslova, J., Pudil, F., & Riddellova, K. (2009). Traceability of honey origin based on volatiles pattern processing by artificial neural networks. Journal of Chromatography A, 1216(9), 1458-1462. doi:10.1016/j.chroma.2008.12.066Castro-Vázquez, L., Díaz-Maroto, M. C., González-Viñas, M. A., & Pérez-Coello, M. S. (2009). Differentiation of monofloral citrus, rosemary, eucalyptus, lavender, thyme and heather honeys based on volatile composition and sensory descriptive analysis. Food Chemistry, 112(4), 1022-1030. doi:10.1016/j.foodchem.2008.06.036Conti, M. E., Stripeikis, J., Campanella, L., Cucina, D., & Tudino, M. B. (2007). Characterization of Italian honeys (Marche Region) on the basis of their mineral content and some typical quality parameters. Chemistry Central Journal, 1(1). doi:10.1186/1752-153x-1-14Custódio, L., Serra, H., Nogueira, J. M. F., Gonçalves, S., & Romano, A. (2006). Analysis of the Volatiles Emitted by Whole Flowers and Isolated Flower Organs of the Carob Tree Using HS-SPME-GC/MS. Journal of Chemical Ecology, 32(5), 929-942. doi:10.1007/s10886-006-9044-9Cuevas-Glory, L., Ortiz-Vázquez, E., Pino, J. A., & Sauri-Duch, E. (2012). Floral classification of Yucatan Peninsula honeys by PCA & HS-SPME/GC-MS of volatile compounds. International Journal of Food Science & Technology, 47(7), 1378-1383. doi:10.1111/j.1365-2621.2012.02983.xDe Bolòs, O., & Molinier, R. (1984). Vegetation of the Pityusic Islands. Biogeography and Ecology of the Pityusic Islands, 185-221. doi:10.1007/978-94-009-6539-3_9De Maria, C. A. B., & Moreira, R. F. A. (2003). Compostos voláteis em méis florais. Química Nova, 26(1), 90-96. doi:10.1590/s0100-40422003000100016Guyot, C., Scheirman, V., & Collin, S. (1999). Floral origin markers of heather honeys: Calluna vulgaris and Erica arborea. Food Chemistry, 64(1), 3-11. doi:10.1016/s0308-8146(98)00122-8Herrera, J. (1988). Pollination Relationships in Southern Spanish Mediterranean Shrublands. The Journal of Ecology, 76(1), 274. doi:10.2307/2260469Jerković, I., & Marijanović, Z. (2010). Volatile Composition Screening of Salix spp. Nectar Honey: Benzenecarboxylic Acids, Norisoprenoids, Terpenes, and Others. Chemistry & Biodiversity, 7(9), 2309-2325. doi:10.1002/cbdv.201000021Jones, G. D., & Bryant, Jr, V. M. (2004). The use of ETOH for the dilution of honey. Grana, 43(3), 174-182. doi:10.1080/00173130410019497Kummerow, J. (1983). Comparative Phenology of Mediterranean-Type Plant Communities. Ecological Studies, 300-317. doi:10.1007/978-3-642-68935-2_17La‐Serna Ramos, I. E., & GÓmez Ferreras, C. (2006). Pollen and sensorial characterization of different honeys from El Hierro (Canary Islands). Grana, 45(2), 146-159. doi:10.1080/00173130600578658Del Carmen Llasat, M., Ramis, C., & Barrantes, J. (1996). The meteorology of high‐intensity rainfall events over the west Mediterranean region. Remote Sensing Reviews, 14(1-3), 51-90. doi:10.1080/02757259609532313Louveaux, J., Maurizio, A., & Vorwohl, G. (1978). Methods of Melissopalynology. Bee World, 59(4), 139-157. doi:10.1080/0005772x.1978.11097714Martins, R. C., Lopes, V. V., Valentão, P., Carvalho, J. C. M. F., Isabel, P., Amaral, M. T., … Silva, B. M. (2008). Relevant principal component analysis applied to the characterisation of Portuguese heather honey. Natural Product Research, 22(17), 1560-1582. doi:10.1080/14786410701825004Melliou, E., & Chinou, I. (2011). Chemical constituents of selected unifloral Greek bee-honeys with antimicrobial activity. Food Chemistry, 129(2), 284-290. doi:10.1016/j.foodchem.2011.04.047Pendleton, M. (2006). Descriptions of melissopalynological methods involving centrifugation should include data for calculating Relative Centrifugal Force (RCF) or should express data in units of RCF or gravities (g). Grana, 45(1), 71-72. doi:10.1080/00173130500520479Pérez, R. A., Sánchez-Brunete, C., Calvo, R. M., & Tadeo, J. L. (2002). Analysis of Volatiles from Spanish Honeys by Solid-Phase Microextraction and Gas Chromatography−Mass Spectrometry. Journal of Agricultural and Food Chemistry, 50(9), 2633-2637. doi:10.1021/jf011551rPersano Oddo, L., Piana, L., Bogdanov, S., Bentabol, A., Gotsiou, P., Kerkvliet, J., … von der Ohe, K. (2004). Botanical species giving unifloral honey in Europe. Apidologie, 35(Suppl. 1), S82-S93. doi:10.1051/apido:2004045Persano Oddo, L., & Piro, R. (2004). Main European unifloral honeys: descriptive sheets. Apidologie, 35(Suppl. 1), S38-S81. doi:10.1051/apido:2004049Piana, M. L., Persano Oddo, L., Bentabol, A., Bruneau, E., Bogdanov, S., & Guyot Declerck, C. (2004). Sensory analysis applied to honey: state of the art. Apidologie, 35(Suppl. 1), S26-S37. doi:10.1051/apido:2004048Piasenzotto, L., Gracco, L., & Conte, L. (2003). Solid phase microextraction (SPME) applied to honey quality control. Journal of the Science of Food and Agriculture, 83(10), 1037-1044. doi:10.1002/jsfa.1502Radovic, B. S., Careri, M., Mangia, A., Musci, M., Gerboles, M., & Anklam, E. (2001). Contribution of dynamic headspace GC–MS analysis of aroma compounds to authenticity testing of honey. Food Chemistry, 72(4), 511-520. doi:10.1016/s0308-8146(00)00263-6RAMÓN-LACA, L., & MABBERLEY, D. J. (2004). The ecological status of the carob-tree (Ceratonia siliqua, Leguminosae) in the Mediterranean. Botanical Journal of the Linnean Society, 144(4), 431-436. doi:10.1111/j.1095-8339.2003.00254.xRetana, J., Ramoneda, J., Garcia Del Pino, F., & Bosch, J. (1994). Flowering phenology of carob,Ceratonia siliquaL. (Cesalpinaceae). Journal of Horticultural Science, 69(1), 97-103. doi:10.1080/14620316.1994.11515254Ricciardelli d’Albore, G. & Vorwohl, G. (1979). Mieles monoflorales en el Mediterráneo documentado con ayuda del análisis microscópico de mieles. Actas de XXVII Congreso Internacional de Apicultura, Athens, Greece, 14–20 September 1979, 201–208.Pilar de Sá‐Otero, M., Armesto‐Baztan, S., & DÍaz‐Losada, E. (2006). A study of variation in the pollen spectra of honeys sampled from the Baixa Limia‐Serra do Xurés Nature Reserve in north‐west Spain. Grana, 45(2), 137-145. doi:10.1080/00173130600708537Seijo, M. C., Jato, M. V., Aira, M. J., & Iglesias, I. (1997). Unifloral honeys of Galicia (north-west Spain). Journal of Apicultural Research, 36(3-4), 133-140. doi:10.1080/00218839.1997.11100939Terrab, A., Diez, M. J., & Heredia, F. J. (2003). Palynological, physico-chemical and colour characterization of Moroccan honeys: III. Other unifloral honey types. International Journal of Food Science and Technology, 38(4), 395-402. doi:10.1046/j.1365-2621.2003.00713.xTERRAB, A., PONTES, A., HEREDIA, F. J., & DÍEZ, M. J. (2004). A preliminary palynological characterization of Spanish thyme honeys. Botanical Journal of the Linnean Society, 146(3), 323-330. doi:10.1111/j.1095-8339.2004.00335.xTerrab, A., Valdés, B., & Josefa Díez, M. (2003). Pollen analysis of honeys from the Mamora forest region (NW Morocco). Grana, 42(1), 47-54. doi:10.1080/00173130310008580Thompson, J. D. (2005). Plant Evolution in the Mediterranean. doi:10.1093/acprof:oso/9780198515340.001.0001Von Der Ohe, W., Persano Oddo, L., Piana, M. L., Morlot, M., & Martin, P. (2004). Harmonized methods of melissopalynology. Apidologie, 35(Suppl. 1), S18-S25. doi:10.1051/apido:2004050VORWOHL, G. (1964). DIE BEZIEHUNGEN ZWISCHEN DER ELEKTRISCHEN LEITFÄHIGKEIT DER HONIGE UND IHRER TRACHTMÄSSIGEN HERKUNFT. Annales de l’Abeille, 7(4), 301-309. doi:10.1051/apido:19640403Vorwohl, G. (1967). The microscopic analysis of honey, a comparison of its methods with those of the other branches of palynology. Review of Palaeobotany and Palynology, 3(1-4), 287-290. doi:10.1016/0034-6667(67)90061-
- …