Black yeasts from the slope sediments of Bay of Bengal: phylogenetic and functional characterization

Occurrence of black yeasts in the slope sediments of Bay of Bengal was investigated during FORV Sagar Sampada cruises 236 and 245. The black yeast population was found to be very scanty in the area and the isolates could be obtained from 200m to 1000m depth regions in the slope sediments. The isolates were identified as Hortaea werneckii by Internal Transcribed Spacer (ITS) sequencing. The biodegradation potential of these strains was found to be very high with all the strains exhibiting protease, lipase and amylase production. The optimum growth conditions were pH 8, salinity 30 ppt and temperature 30oC. The pigment melanin, in these organisms was identified to be of dihydroxynaphthalene type by NMR. The melanin was found to exhibit inhibitory activity against different human and fish pathogens. Melanin degrading enzyme could also be extracted from these organisms

Strain induced anomalous red shift in mesoscopic iron oxide prepared by a novel technique

Nano magnetic oxides are promising candidates for high density magnetic storage and other applications. Nonspherical mesoscopic iron oxide particles are also candidate materials for studying the shape, size and strain induced modifications of various physical properties viz. optical, magnetic and structural. Spherical and nonspherical iron oxides having an aspect ratio, ~2, are synthesized by employing starch and ethylene glycol and starch and water, respectively by a novel technique. Their optical, structural, thermal and magnetic properties are evaluated. A red shift of 0⋅24 eV is observed in the case of nonspherical particles when compared to spherical ones. The red shift is attributed to strain induced changes in internal pressure inside the elongated iron oxide particles. Pressure induced effects are due to the increased overlap of wave functions. Magnetic measurements reveal that particles are superparamagnetic. The marked increase in coercivity in the case of elongated particles is a clear evidence for shape induced anisotropy. The decreased specific saturation magnetization of the samples is explained on the basis of weight percentage of starch, a nonmagnetic component and is verified by TGA and FTIR studies. This technique can be modified for tailoring the aspect ratio and these particles are promising candidates for drug delivery and contrast enhancement agents in magnetic resonance imaging

Ground and Excited State Electron Transfer Reaction Between a few Anthracene Appended Tertiary Amines and Suitable Electron Acceptors

the thesis entitled “Ground and Excited State Electron Transfer Reaction Between a few Anthracene Appended Tertiary Amines and Suitable Electron Acceptors” portrays our attempts to explore the solvent, concentration and temperature effect of the reaction between a few (anthracen-9- yl)methanamines with electron acceptors like DMAD, DBA and DBE. We have also studied the effect of solvent and percentage fluorescence quenching in the photoinduced electron transfer reactions of these ‘donor-spacer-acceptor’ systems. Finally we look in to the intramolecular electron transfer reactions of a few tertiary amine appended dibenzobarrelenes and bisdibenzobarrelenes

Modification of Unsaturated Polyester Resin by Polyurethane Prepolymers

Unsaturated polyester resins (UPRs) are extensively used by the fiber-reinforced plastic (FRPs) industry. These resins have the disadvantages of brittleness and poor resistance to crack propagation. In this study, UPRs were chemically modified by reactive blending with polyurethane prepolymers having terminal isocyanate groups. Hybrid networks were formed by copolymerisation of unsaturated polyesters with styrene and simultaneous reaction between terminal hydroxyl groups of unsaturated polyester and isocyanate groups of polyurethane prepolymer. The prepolymers were based on toluene diisocyanate (TDI) and each of hydroxy-terminated natural rubber (HTNR), hydroxy- terminated polybutadiene (HTPB), polyethylene glycol (PEG), and castor oil. Properties like tensile strength, toughness, impact resistance, and elongation-at-break of the modified UPRs show considerable improvement by this modification. The thermal stability of the copolymer is also marginally better

Block Copolymers of Unsaturated Polyesters and Functional Elastomers

Block copolymers of unsaturated polyester were prepared by condensation polymerization of hydroxyl or carboxyl terminated liquid rubbers with maleic anhydride, phthalic anhydride, and propylene glycol. The condensate obtained was mixed with styrene monomer to get an unsaturated polyester resin formulation. In this study, copolymers of unsaturated polyesters with hydroxy terminated polybutadiene, carboxy terminated nitrile rubber, and hydroxy terminated natural rubber were prepared. Mechanical properties such as tensile strength, tensile modulus, elongation at break, toughness, impact strength, surface hardness, abrasion resistance, and water absorption were evaluated after the resin was cured in appropriate molds for comparison with the control resin. The fracture toughness and impact resistance of CTBN-modified unsaturated polyester show substantial improvement by this copolymerization without seriously affecting any other property

Neue redoxfunktionalisierte Schwefel-Tripodliganden für selbstassemblierende monomolekulare Filme auf Goldoberflächen

Für die Entwicklung selbstorganisierter Monoschichten (SAMs) auf Gold(111)-Oberflächen wurden neue, redox-funktionalisierte Schwefel-Tripodliganden synthetisiert. Um die tripodale Struktur zu realisieren, wurde Adamantan als vierbindiges Zentrum eingesetzt. Die Anbindung an die Goldoberfläche wurde durch Thioethereinheiten ermöglicht, eventuelle laterale Wechselwirkungen durch Alkylseitenketten an den Thioethereinheiten, sowie durch lineare, rigide Spacereinheiten wurden untersucht. Als redoxaktive, funktionelle Einheit wurde ein Ferrocenylrest an den Liganden eingeführt. Gebildete monomolekulare Filme der Liganden auf Gold wurden mit Hilfe von Röntgenphotoelektronenspektroskopie (XPS), Nahkanten-Reflexions-Röntgenabsorptionsspektroskopie (NEXAFS) und Sum-Frequency-Generation (SFG) charakterisiert, um die Filmqualität, die Bindung ans Substrat und Orientierungsordnung im Film zu ermitteln.

Molekulare Studien zur Evolution der Myrmekophytie in der Gattung Macaranga (Euphorbiaceae)

Im Rahmen der vorliegenden Arbeit wurde eine detaillierte phylogenetische Analyse der Ameisenpflanzen aus der Gattung Macaranga (Euphorbiaceae) und ihres verwandtschaftlichen Umfelds mit Hilfe von AFLP-Fingerprinting („amplified fragment length polymorphisms“) sowie vergleichender Analyse von mehreren nichtkodierenden Chloroplasten-DNA-Loci vorgenommen. Anhand dieser Untersuchungen sollten im Wesentlichen die folgenden Fragen geklärt werden: (1) Wie stellen sich die Verwandtschaftsverhältnisse zwischen den myrmekophytischen Macaranga-Sektionen Pachystemon, Winklerianae und Pruinosae dar? (2) Wie sind die einzelnen Arten dieser Sektionen miteinander verwandt? (3) Wie oft ist die Lebensweise ”Myrmekophytie” unabhängig voneinander entstanden? Gibt es Hinweise auf Reversionen? (4) Wo liegt genealogisch und auch geographisch der Ursprung der Symbiose zwischen den myrmekophytischen Macaranga-Arten und ihren Partnerameisen? (5) Welche Bedeutung spielen koevolutive Entwicklungen für das Macaranga-Crematogaster-Symbiosesystem? Ist Myrmekophytie im Sinne einer Schlüsselinnovation (Givnish, 1997) als Stimulus für eine adaptive Radiation zu betrachten? (1) Für die AFLP-Analyse wurden 108 Proben aus 43 Macaranga-Arten und 5 unbeschriebenen Morphospezies in die phylogenetische Untersuchung einbezogen. Auf der Basis von 426 Merkmalen wurden Phänogramme sowie Kladogramme rekonstruiert. Zur statistischen Absicherung wurden Bootstrap-Analysen durchgeführt und im Falle der Kladogramme darüber hinaus der „consistency“-Index bestimmt. Die AFLP-Datensätze wurden zusätzlich einer Hauptkomponentenanalyse unterzogen. Mit Hilfe der verschiedenen Untersuchungsmethoden konnten weitgehend übereinstimmende Gruppierungen bzw. evolutive Linien identifiziert werden. Die Sektionen Pachystemon und Pruinosae bilden eine jeweils gut gestützte monophyletische Gruppe. Beide sind vermutlich Schwestergruppen und damit gleich alt. Für die Monophylie der nur aus zwei Arten bestehenden Sektion Winklerianae ergab sich keine Unterstützung. Die Arten der Sektion Pruinosae sind im AFLP-Baum gut aufgelöst. Die nicht myrmekophytische M. gigantea sitzt dabei an der Basis und ist Schwestergruppe zu den myrmekophytischen Arten. Innerhalb der Sektion Pachystemon wurden mit Hilfe der AFLP-Analyse vier gut gestützte Gruppen identifiziert. Für die puncticulata-Gruppe konnte hier erstmals auf molekularer Ebene eine Zugehörigkeit zur Sekt. Pachystemon nachgewiesen werden. Der von Davies (2001) vorgenommene Ausschluss von M. recurvata aus der Sekt. Pachystemon konnte bestätigt werden. Die Verwandtschaftsbeziehungen einzelner Arten zueinander sind in den AFLP-Bäumen nicht aufgelöst. (2) Für die vergleichende Chloroplasten-Sequenzierung wurden nach Maßgabe der Sequenzvariabilität in Testsequenzierungen die Bereiche atpB-rbcL und psbI-trnS für die phylogenetische Untersuchung ausgewählt. Für die Chloroplasten-Phylogenie wurden für jeden Locus mehr als 100 Sequenzen analysiert. Neben 29 Pachystemon-Arten inkl. vier unbekannter Morphospezies, acht Pruinosae-Arten inkl. eines möglichen Hybriden und den beiden Arten der Sekt. Winklerianae wurden 22 weitere Macaranga- und 10 Mallotus-Arten in die Untersuchung einbezogen. Zwischen den südostasiatischen Arten bestanden nur geringe Sequenzunterschiede. Maximum-Parsimonie-Kladogramme wurden rekonstruiert und die Sequenzen der beiden Loci wurden sowohl einzeln, als auch kombiniert ausgewertet. Indels wurden kodiert und als separate Merkmalsmatrix an die Sequenzdaten angehangen. Innerhalb von Macaranga konnten nur wenige abgesicherte Gruppen identifiziert werden. Deutlich war die Zusammengehörigkeit der afrikanischen Arten und ihr Entstehung aus den südostasiatischen Arten. Die von Davies (2001) der Sektion Pruinosae zugeordnete M. siamensis steht deutlich außerhalb dieser Sektion. Die Arten der Sektionen Pruinosae, Pachystemon und Winklerianae bilden keine statistisch gesicherten monophyletischen Gruppen. Während der Pilotstudien stellte sich heraus, dass die Chloroplastensequenzen nahe verwandter Arten der Sektion Pachystemon weniger nach den Artgrenzen, sondern vielmehr nach geographischen Kriterien gruppierten. (3) Es wurde daher zusätzlich eine phylogeographische Analyse der Chloroplasten-Sequenzen auf der Basis eines Parsimonie-Netzwerks durchgeführt. Neben dem atpB-rbcL-Spacer und einer Teilsequenze des psbI-trnS-Locus (ccmp2) wurde dafür zusätzlich der ccmp6-Locus (ein Abschnitt des ycf3-Introns) sequenziert. Die phylogeographische Untersuchung wurde mit 144 Proben aus 41 Macaranga-Arten durchgeführt. Darin enthalten waren 29 Arten (inkl. vier Morphospezies) mit 112 Proben der Sektion Pachystemon, sieben 7 Arten (inkl. eines potentiellen Hybriden) mit 22 Proben der Sekt. Pruinosae und zwei Arten mit 5 Proben der Sekt. Winklerianae. Das voll aufgelöste statistische Parsimonie-Netzwerk umfasste 88 Haplotypen. Die Sektionen Pachystemon und Pruinosae bilden jeweils eine monophyletische Gruppe. Das geographische Arrangement der Haplotypen unabhängig von der Artzugehörigkeit könnte durch Introgression und/oder „lineage sorting“ bedingt sein. Mit Hilfe der im Rahmen dieser Arbeit gewonnenen Ergebnisse kann man davon ausgehen, dass eine enge Ameisen-Pflanzen-Symbiose innerhalb der Gattung Macaranga mindestens drei-, möglicherweise viermal unabhängig voneinander entstanden ist Eine Reversion hat mindestens einmal, möglicherweise häufiger in der bancana-Gruppe stattgefunden. Ob sich die Symbiose dabei in Westmalaysia oder in Borneo entwickelt hat, kann man nicht sicher sagen; Ob und inwieweit die große Artenzahl in der bancana-Gruppe als eine Folge der Myrmekophytie anzusehen ist, bleibt zunächst offen. Wesentliche Teile der vorliegenden Arbeit liegen bereits in publizierter Form vor (AFLP-Analyse: Bänfer et al. 2004; Chloroplasten-Analyse: Vogel et al. 2003; Bänfer et al. 2006).

Systematics and evolution of the genus Deuterocohnia Mez (Bromeliaceae)

The present study investigates the systematics and evolution of the Neotropical genus Deuterocohnia Mez (Bromeliaceae). It provides a comprehensive taxonomic revision as well as phylogenetic analyses based on chloroplast and nuclear DNA sequences and presents a hypothesis on the evolution of the genus. A broad morphological, anatomical, biogeographical and ecological overview of the genus is given in the first part of the study. For morphological character assessment more than 700 herbarium specimens from 39 herbaria as well as living plant material in the field and in the living collections of botanical gardens were carefully examined. The arid habitats, in which the species of Deuterocohnia grow, are reflected by the morphological and anatomical characters of the species. Important characters for species delimitation were identified, like the length of the inflorescence, the branching order, the density of flowers on partial inflorescences, the relation of the length of the primary bracts to that of the partial inflorescence, the sizes of floral bracts, sepals and petals, flower colour, the presence or absence of a pedicel, the curvature of the stamina and the petals during anthesis. After scrutinizing the nomenclatural history of the taxa belonging to Deuterocohnia – including the 1992 syonymized genus Abromeitiella – 17 species, 4 subspecies and 4 varieties are accepted in the present revision. Taxonomic changes were made in the following cases: (I) New combinations: A. abstrusa (A. Cast.) N. Schütz is re-established – as defined by Castellanos (1931) – and transfered to D. abstrusa; D. brevifolia (Griseb.) M.A. Spencer & L.B. Sm. includes accessions of the former D. lorentziana (Mez) M.A. Spencer & L.B. Sm., which are not assigned to D. abstrusa; D. bracteosa W. Till is synonymized to D. strobilifera Mez; D. meziana Kuntze ex Mez var. carmineo-viridiflora Rauh is classified as a subspecies of D. meziana (ssp. carmineo-viridiflora (Rauh) N. Schütz); D. pedicellata W. Till is classified as a subspecies of D. meziana (ssp. pedicellata (W. Till) N. Schütz); D. scapigera (Rauh & L. Hrom.) M.A. Spencer & L.B. Sm ssp. sanctae-crucis R. Vásquez & Ibisch is classified as a species (D. sanctae-crucis (R. Vásquez & Ibisch) N. Schütz); (II) New taxa: a new subspecies of D. meziana Kuntze ex Mez is established; a new variety of D. scapigera is established; (the new taxa will be validly published elsewhere); (III) New type: an epitype for D. longipetala was chosen. All other species were kept according to Spencer and Smith (1992) or – in the case of more recently described species – according to the protologue. Beside the nomenclatural notes and the detailed descriptions, information on distribution, habitat and ecology, etymology and taxonomic delimitation is provided for the genus and for each of its species. An key was constructed for the identification of currently accepted species, subspecies and varieties. The key is based on easily detectable morphological characters. The former synonymization of the genus Abromeitiella into Deuterocohnia (Spencer and Smith 1992) is re-evalutated in the present study. Morphological as well as molecular investigations revealed Deuterocohnia incl. Abromeitiella as being monophyletic, with some indications that a monophyletic Abromeitiella lineage arose from within Deuterocohnia. Thus the union of both genera is confirmed. The second part of the present thesis describes and discusses the molecular phylogenies and networks. Molecular analyses of three chloroplast intergenic spacers (rpl32-trnL, rps16-trnK, trnS-ycf3) were conducted with a sample set of 119 taxa. This set included 103 Deuterocohnia accessions from all 17 described species of the genus and 16 outgroup taxa from the remainder of Pitcairnioideae s.str. (Dyckia (8 sp.), Encholirium (2 sp.), Fosterella (4 sp.) and Pitcairnia (2 sp.)). With its high sampling density, the present investigation by far represents the most comprehensive molecular study of Deuterocohnia up till now. All data sets were analyzed separately as well as in combination, and various optimality criteria for phylogenetic tree construction were applied (Maximum Parsimony, Maximum Likelihood, Bayesian inferences and the distance method Neighbour Joining). Congruent topologies were generally obtained with different algorithms and optimality criteria, but individual clades received different degrees of statistical support in some analyses. The rps16-trnK locus was the most informative among the three spacer regions examined. The results of the chloroplast DNA analyses revealed a highly supported paraphyly of Deuterocohnia. Thus, the cpDNA trees divide the genus into two subclades (A and B), of which Deuterocohnia subclade B is sister to the included Dyckia and Encholirium accessions, and both together are sister to Deuterocohnia subclade A. To further examine the relationship between Deuterocohnia and Dyckia/Encholirium at the generic level, two nuclear low copy markers (PRK exon2-5 and PHYC exon1) were analysed with a reduced taxon set. This set included 22 Deuterocohnia accessions (including members of both cpDNA subclades), 2 Dyckia, 2 Encholirium and 2 Fosterella species. Phylogenetic trees were constructed as described above, and for comparison the same reduced taxon set was also analysed at the three cpDNA data loci. In contrast to the cpDNA results, the nuclear DNA data strongly supported the monophyly of Deuterocohnia, which takes a sister position to a clade of Dyckia and Encholirium samples. As morphology as well as nuclear DNA data generated in the present study and in a former AFLP analysis (Horres 2003) all corroborate the monophyly of Deuterocohnia, the apparent paraphyly displayed in cpDNA analyses is interpreted to be the consequence of a chloroplast capture event. This involves the introgression of the chloroplast genome from the common ancestor of the Dyckia/ Encholirium lineage into the ancestor of Deuterocohnia subclade B species. The chloroplast haplotypes are not species-specific in Deuterocohnia. Thus, one haplotype was sometimes shared by several species, where the same species may harbour different haplotypes. The arrangement of haplotypes followed geographical patterns rather than taxonomic boundaries, which may indicate some residual gene flow among populations from different Deuteroccohnia species. Phenotypic species coherence on the background of ongoing gene flow may then be maintained by sets of co-adapted alleles, as was suggested by the porous genome concept (Wu 2001, Palma-Silva et al. 2011). The results of the present study suggest the following scenario for the evolution of Deuterocohnia and its species. Deuterocohnia longipetala may be envisaged as a representative of the ancestral state within the genus. This is supported by (1) the wide distribution of this species; (2) the overlap in distribution area with species of Dyckia; (3) the laxly flowered inflorescences, which are also typical for Dyckia; (4) the yellow petals with a greenish tip, present in most other Deuterocohnia species. The following six extant lineages within Deuterocohnia might have independently been derived from this ancestral state with a few changes each: (I) D. meziana, D. brevispicata and D. seramisiana (Bolivia, lowland to montane areas, mostly reddish-greenish coloured, very laxly to very densely flowered); (II) D. strobilifera (Bolivia, high Andean mountains, yellow flowers, densely flowered); (III) D. glandulosa (Bolivia, montane areas, yellow-greenish flowers, densely flowered); (IV) D. haumanii, D. schreiteri, D. digitata, and D. chrysantha (Argentina, Chile, E Andean mountains and Atacama desert, yellow-greenish flowers, densely flowered); (V) D. recurvipetala (Argentina, foothills of the Andes, recurved yellow flowers, laxly flowered); (VI) D. gableana, D. scapigera, D. sanctae-crucis, D. abstrusa, D. brevifolia, D. lotteae (former Abromeitiella species, Bolivia, Argentina, higher Andean mountains, greenish-yellow flowers, inflorescence usually simple). Originating from the lower montane Andean regions, at least four lineages of the genus (I, II, IV, VI) adapted in part to higher altitudes by developing densely flowered partial inflorescences, shorter flowers and – in at least three lineages (II, IV, VI) – smaller rosettes, whereas species spreading into the lowlands (I, V) developed larger plants, laxly flowered, amply branched inflorescences and in part larger flowers (I).

Optical Antennas for Biosensing Applications

The aim of the thesis is to theoretically investigate optical/plasmonic antennas for biosensing applications. The full 3-D numerical electromagnetic simulations have been performed by using finite integration technique (FIT). The electromagnetic properties of surface plasmon polaritons (SPPs) and the localized surface plasmons (LSPs) based devices are studied for sensing purpose. The surface plasmon resonance (SPR) biosensors offer high refractive index sensitivity at a fixed wavelength but are not enough for the detection of low concentrations of molecules. It has been demonstrated that the sensitivity of SPR sensors can be increased by employing the transverse magneto-optic Kerr effect (TMOKE) in combination with SPPs. The sensor based on the phenomena of TMOKE and SPPs are known as magneto-optic SPR (MOSPR) sensors. The optimized MOSPR sensor is analyzed which provides 8 times higher sensitivity than the SPR sensor, which will be able to detect lower concentration of molecules. But, the range of the refractive index detection is limited, due to the rapid decay of the amplitude of the MOSPR-signal with the increase of the refractive indices. Whereas, LSPs based sensors can detect lower concentrations of molecules, but their sensitivity is small at a fixed wavelength. Therefore, another device configuration known as perfect plasmonic absorber (PPA) is investigated which is based on the phenomena of metal-insulator-metal (MIM) waveguide. The PPA consists of a periodic array of gold nanoparticles and a thick gold film separated by a dielectric spacer. The electromagnetic modes of the PPA system are analyzed for sensing purpose. The second order mode of the PPA at a fixed wavelength has been proposed for the first time for biosensing applications. The PPA based sensor combines the properties of the LSPR sensor and the SPR sensor, for example, it illustrates increment in sensitivity of the LSPR sensor comparable to the SPR and can detect lower concentration of molecules due to the presence of nanoparticles.

A New Class of Nonionic Photosensitive Surfactants: Some Insights Concerning Conformations

We report on a new class of nonionic, photosensitive surfactants consisting of a polar di(ethylene oxide) head group attached to an alkyl spacer of between two and eight methylene groups, coupled through an ether linkage to an azobenzene moiety. Structural changes associated with the interconversion of the azobenzene group between its cis and trans forms as mediated by the wavelength of an irradiating light source cause changes in the surface tension and self-assembly properties. Differences in saturated surface tensions (surface tension at concentrations above the CMC) were as high as 14.4 mN/m under radiation of different wavelengths. The qualitative behavior of the surfactants changed as the spacer length changed, attributed to the different orientations adopted by the different surfactants depending on their isomerization states, as revealed by neutron reflection studies. The self-assembly of these photosensitive surfactants has been investigated by light scattering, small angle neutron scattering, and cryo-TEM under different illuminations. The significant change in the self-assembly in response to different illumination conditions was attributed to the sign change in Gaussian rigidity, which originated from the azobenzene photoisomerization.

Subcutaneous study on the controlled release of Etanidazole and Taxol for the treatment of Glioma

BALB/c nude mice 6 weeks old were inoculated with glioma C6 cell-line and the efficacy of the different amount of Etanidazole-discs and Taxol-microspheres was investigated. Poly (D,L-lactic-co-glycolic acid) (PLGA) was used as the main encapsulating polymer and polyethylene glycol was added to increase the porosity. The 1% drug loading microspheres of each drug were produced by spray drying and the discs were obtained by compressing the Etanidazole-microspheres. Intra-tumoral injection followed by irradiation resulted in high systemic dosage and thus systemic toxicity. Tumors grown for 6 days, 9 days and 16 days were implanted with 0.5 mg or 1.0 mg or 1.5 mg of the drug. A radiation dosage of 2 Gy each time for a number of times was given for animals implanted with Etanidazole and no irradiation was given for animals implanted with Taxol. Increasing the number of doses clearly decreased the rate of tumor growth. The increase in the amount of drug on smaller sized tumors controlled the tumor better and there was agglomeration of the microspheres resulting in deviation of release profile of the drug as compared to the in vitro studies. It was observed that 1.0 mg of Taxol given to a tumor grown for 6 days was able to suppress the tumor for a total period of approximately two months and no tumor resurrection was observed during the second month.

A "Trojan horse" strategy to reverse drug-resistance in brain tumors

Los gliomas malignos representan una de las formas más agresivas de los tumores del sistema nervioso central (SNC). De acuerdo con la clasificación de los tumores cerebrales de la Organización Mundial de la Salud (OMS), los astrocitomas han sido categorizados en cuatro grados, determinados por la patología subyacente. Es así como los gliomas malignos (o de alto grado) incluyen el glioma anaplásico (grado III) así como el glioblastoma multiforme (GBM, grado IV),estos últimos los más agresivos con el peor pronóstico (1). El manejo terapéutico de los tumores del SNC se basa en la cirugía, la radioterapia y la quimioterapia, dependiendo de las características del tumor, el estadio clínico y la edad (2),(3), sin embargo ninguno de los tratamientos estándar es completamente seguro y compatible con una calidad de vida aceptable (3), (4). En general, la quimioterapia es la primera opción en los tumores diseminados, como el glioblastoma invasivo y el meduloblastoma de alto riesgo o con metástasis múltiple, pero el pronóstico en estos pacientes es muy pobre (2),(3). Solamente nuevas terapias dirigidas (2) como las terapias anti-angiogénicas (4); o terapias génicas muestran un beneficio real en grupos limitados de pacientes con defectos moleculares específicos conocidos (4). De este modo, se hace necesario el desarrollo de nuevas terapias farmacológicas para atacar los tumores cerebrales. Frente a las terapias los gliomas malignos son con frecuencia quimioresistentes, y esta resistencia parece depender de al menos dos mecanismos: en primer lugar, la pobre penetración de muchas drogas anticáncer a través de la barrera hematoencefálica (BBB: Blood Brain Barrier), la barrera del fluido sangre-cerebroespinal (BCSFB: Blood-cerebrospinal fluid barrier) y la barrera sangre-tumor (BTB: blood-tumor barrier). Dicha resistencia se debe a la interacción de la droga con varios transportadores o bombas de eflujo de droga ABC (ABC: ATP-binding cassette) que se sobre expresan en las células endoteliales o epiteliales de estas barreras. En segundo lugar, estos transportadores de eflujo de drogas ABC propios de las células tumorales confieren un fenotipo conocido como resistencia a multidrogas (MDR: multidrug resistance), el cual es característico de varios tumores sólidos. Este fenotipo también está presente en los tumores del SNC y su papel en gliomas es objeto de investigación (5). Por consiguiente el suministro de medicamentos a través de la BBB es uno de los problemas vitales en los tratamientos de terapia dirigida. Estudios recientes han demostrado que algunas moléculas pequeñas utilizadas en estas terapias son sustratos de la glicoproteína P (Pgp: P-gycoprotein), así como también de otras bombas de eflujo como las proteínas relacionadas con la resistencia a multidrogas (MRPs: multidrug resistance-related proteins (MRPs) o la proteína relacionada con cáncer de seno (BCRP: breast-cancer resistance related protein)) que no permiten que las drogas de este tipo alcancen el tumor (1). Un sustrato de Pgp y BCRP es la DOXOrubicina (DOXO), un fármaco utilizado en la terapia anti cáncer, el cual es muy eficaz para atacar las células del tumor cerebral in vitro, pero con un uso clínico limitado por la poca entrega a través de la barrera hematoencefálica (BBB) y por la resistencia propia de los tumores. Por otra parte las células de BBB y las células del tumor cerebral tienen también proteínas superficiales, como el receptor de la lipoproteína de baja densidad (LDLR), que podría utilizarse como blanco terapéutico en BBB y tumores cerebrales. Es asi como la importancia de este estudio se basa en la generación de estrategias terapéuticas que promuevan el paso de las drogas a través de la barrera hematoencefalica y tumoral, y a su vez, se reconozcan mecanismos celulares que induzcan el incremento en la expresión de los transportadores ABC, de manera que puedan ser utilizados como blancos terapéuticos.Este estudio demostró que el uso de una nueva estrategia basada en el “Caballo de Troya”, donde se combina la droga DOXOrubicina, la cual es introducida dentro de un liposoma, salvaguarda la droga de manera que se evita su reconocimiento por parte de los transportadores ABC tanto de la BBB como de las células del tumor. La construcción del liposoma permitió utilizar el receptor LDLR de las células asegurando la entrada a través de la BBB y hacia las células tumorales a través de un proceso de endocitosis. Este mecanismo fue asociado al uso de estatinas o drogas anticolesterol las cuales favorecieron la expresión de LDLR y disminuyeron la actividad de los transportadores ABC por nitración de los mismos, incrementando la eficiencia de nuestro Caballo de Troya. Por consiguiente demostramos que el uso de una nueva estrategia o formulación denominada ApolipoDOXO más el uso de estatinas favorece la administración de fármacos a través de la BBB, venciendo la resistencia del tumor y reduciendo los efectos colaterales dosis dependiente de la DOXOrubicina. Además esta estrategia del "Caballo de Troya", es un nuevo enfoque terapéutico que puede ser considerado como una nueva estrategia para aumentar la eficacia de diferentes fármacos en varios tumores cerebrales y garantiza una alta eficiencia incluso en un medio hipóxico,característico de las células cancerosas, donde la expresión del transportador Pgp se vió aumentada. Teniendo en cuenta la relación entre algunas vías de señalización reconocidas como moduladores de la actividad de Pgp, este estudio presenta no solo la estrategia del Caballo de Troya, sino también otra propuesta terapéutica relacionada con el uso de Temozolomide más DOXOrubicina. Esta estrategia demostró que el temozolomide logra penetrar la BBB por que interviene en la via de señalización de la Wnt/GSK3/β-catenina, la cual modula la expresión del transportador Pgp. Se demostró que el TMZ disminuye la proteína y el mRNA de Wnt3 permitiendo plantear la hipótesis de que la droga al disminuir la transcripción del gen Wnt3 en células de BBB, incrementa la activación de la vía fosforilando la β-catenina y conduciendo a disminuir la β-catenina nuclear y por tanto su unión al promotor del gen mdr1. Con base en los resultados este estudio permitió el reconocimiento de tres mecanismos básicos relacionados con la expresión de los transportadores ABC y asociados a las estrategias empleadas: el primero fue el uso de las estatinas, el cual condujo a la nitración de los transportadores disminuyendo su actividad por la via del factor de transcripción NFκB; el segundo a partir del uso del temozolomide, el cual metila el gen de Wnt3 reduciendo la actividad de la via de señalización de la la β-catenina, disminuyendo la expresión del transportador Pgp. El tercero consistió en la determinación de la relación entre el eje RhoA/RhoA quinasa como un modulador de la via (no canónica) GSK3/β-catenina. Se demostró que la proteína quinasa RhoA promovió la activación de la proteína PTB1, la cual al fosforilar a GSK3 indujo la fosforilación de la β-catenina, lo cual dio lugar a su destrucción por el proteosoma, evitando su unión al promotor del gen mdr1 y por tanto reduciendo su expresión. En conclusión las estrategias propuestas en este trabajo incrementaron la citotoxicidad de las células tumorales al aumentar la permeabilidad no solo de la barrera hematoencefálica, sino también de la propia barrera tumoral. Igualmente, la estrategia del “Caballo de Troya” podría ser útil para la terapia de otras enfermedades asociadas al sistema nervioso central. Por otra parte estos estudios indican que el reconocimiento de mecanismos asociados a la expresión de los transportadores ABC podría constituir una herramienta clave en el desarrollo de nuevas terapias anticáncer.

A Validated Methodology for Genetic Identification of Tuna Species (Genus Thunnus)

Tuna species of the genus Thunnus, such as the bluefin tunas, are some of the most important and yet most endangered trade fish in the world. Identification of these species in traded forms, however, may be difficult depending on the presentation of the products, which may hamper conservation efforts on trade control. In this paper, we validated a genetic methodology that can fully distinguish between the eight Thunnus species from any kind of processed tissue. Methodology: After testing several genetic markers, a complete discrimination of the eight tuna species was achieved using Forensically Informative Nucleotide Sequencing based primarily on the sequence variability of the hypervariable genetic marker mitochondrial DNA control region (mtDNA CR), followed, in some specific cases, by a second validation by a nuclear marker rDNA first internal transcribed spacer (ITS1). This methodology was able to distinguish all tuna species, including those belonging to the subgenus Neothunnus that are very closely related, and in consequence can not be differentiated with other genetic markers of lower variability. This methodology also took into consideration the presence of introgression that has been reported in past studies between T. thynnus, T. orientalis and T. alalunga. Finally, we applied the methodology to cross-check the species identity of 26 processed tuna samples. Conclusions: Using the combination of two genetic markers, one mitochondrial and another nuclear, allows a full discrimination between all eight tuna species. Unexpectedly, the genetic marker traditionally used for DNA barcoding, cytochrome oxidase 1, could not differentiate all species, thus its use as a genetic marker for tuna species identification is questioned

Contribución al estudio de la extracción química del Fe3+ contaminante de la madera arqueológica subacuática impregnada con polietilenglicol

Due to the large quantity of contamination by Fe in the waterlogged wood and the composites previously processed with poliethilenglycol, PEG , we have thought the possible extraction and formation of complexes Fe-L (L= 2-Phosphonobuta-1,2,4- tricarboxylic acid, (PBTC)) and their effect on (i) structure of the wood, (ii) structure and physiques characteristics of PEG and (iii) post-treatment contamination by Fe coming from atmospheric agents. This work is a project for to study the formation of these complexes and possible modifications in structures.

Soluções sólidas vs. dispersões sólidas: impacto dos parâmetros de formulação

Filmes matriciais foram preparados com fármacos com diferentes solubilidades aquosas (tartarato de metoprolol, ibuprofeno e diclofenac Na) e diferentes polímeros (etilcelulose, Eudragit RS e Eudragit RL). Foram obtidas soluções sólidas (fármaco dissolvido) e dispersões sólidas (fármaco disperso). A libertação dos fármacos foi estudada em função do tipo de fármaco, doseamento, tipo e quantidade de aditivo e do tipo de polímero. A libertação dos fármacos não foi de acordo com a sua solubilidade aquosa, mas sim com o estado físico do fármaco na matriz. O incremento do conteúdo do fármaco na matriz aumentou a velocidade de libertação monotonicamente para a solução sólida. Em contraste, com a dispersão sólida, o aumento da dosagem de fármaco não originou quase nenhum efeito até 30 %, registando-se apenas, posteriormente, um acréscimo na sua velocidade. A inclusão de aditivos hidrofílicos aumentou principalmente a fase inicial do perfil de libertação do fármaco e não produziu efeito no plateau. Por outro lado, polietilenoglicol 1500 diminuiu a libertação de diclofenac Na devido ao aprisionamento do fármaco nos seus domínios. O efeito do tipo de polímero na libertação de ibuprofeno esteve relacionado com a partição do fármaco com o polímero. No caso do tartarato de metoprolol, a libertação foi muito mais rápida do da matriz de Eudragit RS do que de EC, devido à formação de uma mistura amorfa.