Photophysical properties of 5-substituted 2-thiopyrimidines

The aim of the present work is to determine the influence of C5 substitution on the photophysical properties of 2-thiopyrimidines (2-TPyr). For this purpose, 2-thiouracil, 5-t-butyl-2-thiouracil and 2-thiothymine (TU, BTU and TT, respectively) have been selected as target thionucleobases for the experimental studies and, in parallel, for DFT theoretical calculations. The UV spectra displayed by TU, BTU and TT in EtOH were very similar to each other. They showed a maximum around 275 nm and a shoulder at ca. 290 nm. The three 2-TPyr exhibited a strong phosphorescence emission; from the recorded spectra, triplet excited state energies of ca. 307, 304 and 294 kJ mol(-1) were determined for TU, BTU and TT, respectively. Laser excitation at 308 nm gave rise to a broad transient absorption band from 500 nm to 700 nm, which was in principle assigned to triplet-triplet absorption. This assignment was confirmed by energy transfer experiments using biphenyl (E-T = 274 kJ mol(-1)) as an acceptor. The triplet lifetimes were 70 ns, 1.1 mu s and 2.3 mu s, for TU, BTU and TT, respectively. The obtained photophysical data, both in phosphorescence and transient absorption measurements, point to significantly different properties of the TT triplet excited state in spite of the structural similarities. Theoretical calculations at the B3LYP/aug-cc-pVDZ/PCM level agree well with the experimental range of excited state energies and support the pi pi(star) nature of the lowest triplet states.Financial support by the Spanish Government (CTQ2009-13699, CTQ2012-32621, RyC-2007-00476 to V. L.-V., and contracts JAE-Predoc 2011-00740 and JAE-Doc 2010-06204 to V. V.-C. and J. A. S. respectively) and the computing facilities provided by the Theoretical Organic Chemistry group at the Universitat de Valencia (http://utopia.uv.es) are acknowledged.Vendrell Criado, V.; Sáez Cases, JA.; Lhiaubet, VL.; Cuquerella Alabort, MC.; Miranda Alonso, MÁ. (2013). Photophysical properties of 5-substituted 2-thiopyrimidines. Photochemical & Photobiological Sciences Photochemical and Photobiological Sciences. 12(8):1460-1465. doi:10.1039/c3pp50058fS14601465128Kumar, R. (1997). Synthesis and studies on the effect of 2-thiouridine and 4-thiouridine on sugar conformation and RNA duplex stability. Nucleic Acids Research, 25(6), 1272-1280. doi:10.1093/nar/25.6.1272Sintim, H. O., & Kool, E. T. (2006). Enhanced Base Pairing and Replication Efficiency of Thiothymidines, Expanded-size Variants of Thymidine. Journal of the American Chemical Society, 128(2), 396-397. doi:10.1021/ja0562447Favre, A., & Fourrey, J.-L. (1995). Structural Probing of Small Endonucleolytic Ribozymes in Solution Using Thio-Substituted Nucleobases as Intrinsic Photolabels. Accounts of Chemical Research, 28(9), 375-382. doi:10.1021/ar00057a003Cooper, D. S. (2005). Antithyroid Drugs. New England Journal of Medicine, 352(9), 905-917. doi:10.1056/nejmra042972Reader, S. C. J., Carroll, B., Robertson, W. R., & Lambert, A. (1987). Assessment of the biopotency of anti-thyroid drugs using porcine thyroid cells. Biochemical Pharmacology, 36(11), 1825-1828. doi:10.1016/0006-2952(87)90245-0Massey, A., Xu, Y.-Z., & Karran, P. (2001). Photoactivation of DNA thiobases as a potential novel therapeutic option. Current Biology, 11(14), 1142-1146. doi:10.1016/s0960-9822(01)00272-xKuramochi, H., Kobayashi, T., Suzuki, T., & Ichimura, T. (2010). Excited-State Dynamics of 6-Aza-2-thiothymine and 2-Thiothymine: Highly Efficient Intersystem Crossing and Singlet Oxygen Photosensitization. The Journal of Physical Chemistry B, 114(26), 8782-8789. doi:10.1021/jp102067tHarada, Y., Okabe, C., Kobayashi, T., Suzuki, T., Ichimura, T., Nishi, N., & Xu, Y.-Z. (2009). Ultrafast Intersystem Crossing of 4-Thiothymidine in Aqueous Solution. The Journal of Physical Chemistry Letters, 1(2), 480-484. doi:10.1021/jz900276xFavre, A., Saintomé, C., Fourrey, J.-L., Clivio, P., & Laugâa, P. (1998). Thionucleobases as intrinsic photoaffinity probes of nucleic acid structure and nucleic acid-protein interactions. Journal of Photochemistry and Photobiology B: Biology, 42(2), 109-124. doi:10.1016/s1011-1344(97)00116-4Coleman, R. S., & Siedlecki, J. M. (1992). Synthesis of a 4-thio-2’-deoxyuridine containing oligonucleotide. Development of the thiocarbonyl group as a linker element. Journal of the American Chemical Society, 114(23), 9229-9230. doi:10.1021/ja00049a089Hafner, M., Landthaler, M., Burger, L., Khorshid, M., Hausser, J., Berninger, P., … Tuschl, T. (2010). Transcriptome-wide Identification of RNA-Binding Protein and MicroRNA Target Sites by PAR-CLIP. Cell, 141(1), 129-141. doi:10.1016/j.cell.2010.03.009Basnak, I., Balkan, A., Coe, P. L., & Walker, R. T. (1994). The Synthesis of Some 5-Substituted and 5,6-Disubstituted 2′-Deoxyuridines. Nucleosides and Nucleotides, 13(1-3), 177-196. doi:10.1080/15257779408013234Becke, A. D. (1988). Density-functional exchange-energy approximation with correct asymptotic behavior. Physical Review A, 38(6), 3098-3100. doi:10.1103/physreva.38.3098Lee, C., Yang, W., & Parr, R. G. (1988). Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Physical Review B, 37(2), 785-789. doi:10.1103/physrevb.37.785Yanai, T., Tew, D. P., & Handy, N. C. (2004). A new hybrid exchange–correlation functional using the Coulomb-attenuating method (CAM-B3LYP). Chemical Physics Letters, 393(1-3), 51-57. doi:10.1016/j.cplett.2004.06.011Chai, J.-D., & Head-Gordon, M. (2008). Systematic optimization of long-range corrected hybrid density functionals. The Journal of Chemical Physics, 128(8), 084106. doi:10.1063/1.2834918Zhao, Y., & Truhlar, D. G. (2007). The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals. Theoretical Chemistry Accounts, 120(1-3), 215-241. doi:10.1007/s00214-007-0310-xAdamo, C., & Barone, V. (1999). Toward reliable density functional methods without adjustable parameters: The PBE0 model. The Journal of Chemical Physics, 110(13), 6158-6170. doi:10.1063/1.478522Ditchfield, R., Hehre, W. J., & Pople, J. A. (1971). Self‐Consistent Molecular‐Orbital Methods. IX. An Extended Gaussian‐Type Basis for Molecular‐Orbital Studies of Organic Molecules. The Journal of Chemical Physics, 54(2), 724-728. doi:10.1063/1.1674902Dunning, T. H. (1989). Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen. The Journal of Chemical Physics, 90(2), 1007-1023. doi:10.1063/1.456153Bauernschmitt, R., & Ahlrichs, R. (1996). Treatment of electronic excitations within the adiabatic approximation of time dependent density functional theory. Chemical Physics Letters, 256(4-5), 454-464. doi:10.1016/0009-2614(96)00440-xCasida, M. E., Jamorski, C., Casida, K. C., & Salahub, D. R. (1998). Molecular excitation energies to high-lying bound states from time-dependent density-functional response theory: Characterization and correction of the time-dependent local density approximation ionization threshold. The Journal of Chemical Physics, 108(11), 4439-4449. doi:10.1063/1.475855Stratmann, R. E., Scuseria, G. E., & Frisch, M. J. (1998). An efficient implementation of time-dependent density-functional theory for the calculation of excitation energies of large molecules. The Journal of Chemical Physics, 109(19), 8218-8224. doi:10.1063/1.477483Van Caillie, C., & Amos, R. D. (1999). Geometric derivatives of excitation energies using SCF and DFT. Chemical Physics Letters, 308(3-4), 249-255. doi:10.1016/s0009-2614(99)00646-6Van Caillie, C., & Amos, R. D. (2000). Geometric derivatives of density functional theory excitation energies using gradient-corrected functionals. Chemical Physics Letters, 317(1-2), 159-164. doi:10.1016/s0009-2614(99)01346-9Furche, F., & Ahlrichs, R. (2002). Adiabatic time-dependent density functional methods for excited state properties. The Journal of Chemical Physics, 117(16), 7433-7447. doi:10.1063/1.1508368Scalmani, G., Frisch, M. J., Mennucci, B., Tomasi, J., Cammi, R., & Barone, V. (2006). Geometries and properties of excited states in the gas phase and in solution: Theory and application of a time-dependent density functional theory polarizable continuum model. The Journal of Chemical Physics, 124(9), 094107. doi:10.1063/1.2173258Cossi, M., Scalmani, G., Rega, N., & Barone, V. (2002). New developments in the polarizable continuum model for quantum mechanical and classical calculations on molecules in solution. The Journal of Chemical Physics, 117(1), 43-54. doi:10.1063/1.1480445Barone, V., Cossi, M., & Tomasi, J. (1997). A new definition of cavities for the computation of solvation free energies by the polarizable continuum model. The Journal of Chemical Physics, 107(8), 3210-3221. doi:10.1063/1.47467

What happens after spousal loss? Assessment of the impact on human dimensionality

La muerte de un ser querido tiene un gran impacto en las personas, pero es bien sabido que la muerte de un cónyuge es junto con la muerte de un hijo, una de las pérdidas más dolorosas que un ser humano puede experimentar. Es posible que esta pérdida repercuta tanto en la salud como en los aspectos psicosociales y económicos de la persona. El objetivo consiste en analizar la repercusión física y psicológica de la muerte en el cónyuge superviviente.The death of a loved one has a great impact on people, but it is well known that the death of a spouse is, together with the death of a child, one of the most painful losses that a human being can experience. It is possible that this loss also affects the health and the psychosocial and economic aspects of a person. The main objective of this study is to analyze the physical and psychological impact of death on the surviving spouse.Enfermerí

Transcriptomic profiles and diagnostic biomarkers in the Mediterranean seagrasses Posidonia oceanica and Cymodocea nodosa reveal mechanistic insights of adaptative strategies upon desalination brine stress

Seawater desalination by reverse osmosis is growing exponentially due to water scarcity. Byproducts of this process (e.g. brines), are generally discharged directly into the coastal ecosystem, causing detrimental effects, on benthic organisms. Understanding the cellular stress response of these organisms (biomarkers), could be crucial for establishing appropriate salinity thresholds for discharged brines. Early stress biomarkers can serve as valuable tools for monitoring the health status of brine-impacted organisms, enabling the prediction of long-term irreversible damage caused by the desalination industry. In this study, we conducted laboratory-controlled experiments to assess cellular and molecular biomarkers against brine exposure in two salinity-sensitive Mediterranean seagrasses: Posidonia oceanica and Cymodocea nodosa. Treatments involved exposure to 39, 41, and 43 psu, for 6 h and 7 days. Results indicated that photosynthetic performance remained unaffected across all treatments. However, under 43 psu, P. oceanica and C. nodosa exhibited lipid oxidative damage, which occurred earlier in P. oceanica. Additionally, P. oceanica displayed an antioxidant response at higher salinities by accumulating phenolic compounds within 6 h and ascorbate within 7 d; whereas for C. nodosa the predominant antioxidant mechanisms were phenolic compounds accumulation and total radical scavenging activity, which was evident after 7 d of brines exposure. Finally, transcriptomic analyses in P. oceanica exposed to 43 psu for 7 days revealed a poor up-regulation of genes associated with brassinosteroid response and abiotic stress response, while a high down-regulation of genes related to primary metabolism was detected. In C. nodosa, up-regulated genes were involved in DNA repair, cell cycle regulation, and reproduction, while down-regulated genes were mainly associated with photosynthesis and ribosome assembly. Overall, these findings suggest that 43 psu is a critical salinity-damage threshold for both seagrasses; and despite the moderate overexpression of several transcripts that could confer salt tolerance, genes involved in essential biological processes were severely downregulated.FRR was financed by Fondecyt #11220425 grant from ANID, Chile. CAS was financed by project ANID InES I + D 2021 (INID210013) and by Marie Skłodowska-Curie Action (888415). FBM was supported by a grant from Universidad de Alicante (Grant ID: FPUUA98)

Cycloreversion of beta-lactams via photoinduced electron transfer

The radical anions of beta-lactams, photogenerated in the presence of DABCO as an electron donor, undergo cycloreversion via N-C4 bond cleavage, back electron transfer and final C2-C3 bond cleavage, leading to olefins. The involved intermediates are 1,4-radical anions and 1,4-biradicals. The experimental observations are consistent with the results of DFT calculations.Financial support from the Spanish Government (CTQ2013-47872-C2-1-P, SEV-2012-0267, BES-2011-043706, JCI-2010-06204), from CSIC (JAEDOC 101-2011 co-funded by FSE) and from the Generalitat Valenciana (PROMETEOII/2013/005) is gratefully acknowledged. J. A. S. acknowledges the computational facilities provided by the Theoretical Computational Chemistry Group of Prof. L. R. Domingo at the Universitat de Valencia.Pérez Ruiz, R.; Sáez Cases, JA.; Jiménez Molero, MC.; Miranda Alonso, MÁ. (2014). Cycloreversion of beta-lactams via photoinduced electron transfer. Organic and Biomolecular Chemistry. 12(42):8428-8432. https://doi.org/10.1039/c4ob01416bS842884321242Von Nussbaum, F., Brands, M., Hinzen, B., Weigand, S., & Häbich, D. (2006). Antibacterial Natural Products in Medicinal Chemistry—Exodus or Revival? Angewandte Chemie International Edition, 45(31), 5072-5129. doi:10.1002/anie.200600350β-Lactams in the New Millennium. Part-I: Monobactams and Carbapenems. (2004). Mini-Reviews in Medicinal Chemistry, 4(1), 69-92. doi:10.2174/1389557043487501β-Lactams in the New Millennium. Part-II: Cephems, Oxacephems, Penams and Sulbactam. (2004). Mini-Reviews in Medicinal Chemistry, 4(1), 93-109. doi:10.2174/1389557043487547Buynak, J. (2004). The Discovery and Development of Modified Penicillin- and Cephalosporin- Derived β-Lactamase Inhibitors. Current Medicinal Chemistry, 11(14), 1951-1964. doi:10.2174/0929867043364847Veinberg, G., Vorona, M., Shestakova, I., Kanepe, I., & Lukevics, E. (2003). Design of β-Lactams with Mechanism Based Nonantibacterial Activities. Current Medicinal Chemistry, 10(17), 1741-1757. doi:10.2174/0929867033457089Chemistry and Biology of β-Lactam Antibiotics , ed. R. B. Morin and M. Gorman , Academic Press , New York , 1982 , pp. 1–3Nathwani, D., & Wood, M. J. (1993). Penicillins. Drugs, 45(6), 866-894. doi:10.2165/00003495-199345060-00002Fischer, M. (1968). Photochemische Reaktionen, IV. Photochemische Fragmentierungen von β-Lactamen. Chemische Berichte, 101(8), 2669-2678. doi:10.1002/cber.19681010809Fabre, H., Ibork, H., & Lerner, D. A. (1994). Photoisomerization Kinetics of Cefuroxime Axetil and Related Compounds. Journal of Pharmaceutical Sciences, 83(4), 553-558. doi:10.1002/jps.2600830422Rossi, E., Abbiati, G., & Pini, E. (1999). Substituted 1-benzyl-4-(benzylidenimino)-4-phenylazetidin-2-ones: Synthesis, thermal and photochemical reactions. Tetrahedron, 55(22), 6961-6970. doi:10.1016/s0040-4020(99)00325-7Gómez-Gallego, M., Alcázar, R., Ramírez, P., Vincente, R., J. Mancheño, M., & A. Sierra, M. (2001). A Study of the Photochemical Isomerization in b-Lactam Rings. HETEROCYCLES, 55(3), 511. doi:10.3987/com-00-9127MUKERJEE, A. K., & SINGH, A. K. (1975). Reactions of Natural and Synthetic β-Lactams. Synthesis, 1975(09), 547-589. doi:10.1055/s-1975-23842Mukerjee, A. K., & Singh, A. K. (1978). β-Lactams: retrospect and prospect. Tetrahedron, 34(12), 1731-1767. doi:10.1016/0040-4020(78)80209-9Pérez-Ruiz, R., Jiménez, M. C., & Miranda, M. A. (2014). Hetero-cycloreversions Mediated by Photoinduced Electron Transfer. Accounts of Chemical Research, 47(4), 1359-1368. doi:10.1021/ar4003224Pérez-Ruiz, R., Sáez, J. A., Domingo, L. R., Jiménez, M. C., & Miranda, M. A. (2012). Ring splitting of azetidin-2-ones via radical anions. Organic & Biomolecular Chemistry, 10(39), 7928. doi:10.1039/c2ob26528aRehm, D., & Weller, A. (1970). Kinetics of Fluorescence Quenching by Electron and H-Atom Transfer. Israel Journal of Chemistry, 8(2), 259-271. doi:10.1002/ijch.197000029Kavarnos, G. J., & Turro, N. J. (1986). Photosensitization by reversible electron transfer: theories, experimental evidence, and examples. Chemical Reviews, 86(2), 401-449. doi:10.1021/cr00072a005Gandon, V., Bertus, P., & Szymoniak, J. (2000). A Straightforward Synthesis of Cyclopropanes from Aldehydes and Ketones. European Journal of Organic Chemistry, 2000(22), 3713-3719. doi:10.1002/1099-0690(200011)2000:223.0.co;2-1Wang, S. C., Troast, D. M., Conda-Sheridan, M., Zuo, G., LaGarde, D., Louie, J., & Tantillo, D. J. (2009). Mechanism of the Ni(0)-Catalyzed Vinylcyclopropane−Cyclopentene Rearrangement. The Journal of Organic Chemistry, 74(20), 7822-7833. doi:10.1021/jo901525uKashima, C., Fukusaka, K., & Takahashi, K. (1997). Synthesis of optically active β-lactams by the reaction of 2-acyl-3-phenyl-l-menthopyrazoles with CN compounds. Journal of Heterocyclic Chemistry, 34(5), 1559-1565. doi:10.1002/jhet.5570340529Andreu, I., Delgado, J., Espinós, A., Pérez-Ruiz, R., Jiménez, M. C., & Miranda, M. A. (2008). Cycloreversion of Azetidines via Oxidative Electron Transfer. Steady-State and Time-Resolved Studies. Organic Letters, 10(22), 5207-5210. doi:10.1021/ol802181uBelger, C., Neisius, N. M., & Plietker, B. (2010). A Selective Ru-Catalyzed Semireduction of Alkynes to Z Olefins under Transfer-Hydrogenation Conditions. Chemistry - A European Journal, 16(40), 12214-12220. doi:10.1002/chem.201001143Eicher, T., Böhm, S., Ehrhardt, H., Harth, R., & Lerch, D. (1981). Zur Reaktion von Diphenylcyclopropenon, seinen funktionellen Derivaten und Imoniumsalzen mit Aminen. Liebigs Annalen der Chemie, 1981(5), 765-788. doi:10.1002/jlac.198119810503Mazzocchi, P. H., & Thomas, J. J. (1972). Photolysis of N-methyl-2-pyrrolidone. Journal of the American Chemical Society, 94(23), 8281-8282. doi:10.1021/ja00778a085Platz, M. S., & Burns, J. R. (1979). Heteroatomic biradicals. Electron spin resonance spectroscopy of a nitrogen analog of 1,8-naphthoquinodimethane. Journal of the American Chemical Society, 101(15), 4425-4426. doi:10.1021/ja00509a086Leo, E. A., Domingo, L. R., Miranda, M. A., & Tormos, R. (2006). Photogeneration and Reactivity of 1,n-Diphenyl-1,n-azabiradicals. The Journal of Organic Chemistry, 71(12), 4439-4444. doi:10.1021/jo0601967Miranda, M. A., Font-Sanchis, E., Pérez-Prieto, J., & Scaiano, J. C. (1999). Two-Photon Generation of the 1,4-Diphenyl-1,4-butanediyl Biradical:  Direct Detection and Product Studies. The Journal of Organic Chemistry, 64(21), 7842-7845. doi:10.1021/jo990872nR. M. Wilson , in Organic Photochemistry , ed. A. Padwa , Marcel Dekker , New York , 1985 , ch. 5, vol. 7 , pp. 339–467Adam, W., Grabowski, S., & Wilson, R. M. (1990). Localized cyclic triplet diradicals. Lifetime determination by trapping with oxygen. Accounts of Chemical Research, 23(5), 165-172. doi:10.1021/ar00173a00

Ring splitting of azetidin-2-ones via radical anions

The radical anions of azetidin-2-ones, generated by UV-irradiation in the presence of triethylamine, undergo ring-splitting via N-C4 or C3-C4 bond breaking, leading to open-chain amides. This reactivity diverges from that found for the neutral excited states, which is characterised by alpha-cleavage. The preference for beta-cleavage is supported by DFT theoretical calculations on the energy barriers associated with the involved transition states. Thus, injection of one electron into the azetidin-2-one moiety constitutes a complementary activation strategy which may be exploited to produce new chemistry.Financial support from the MICINN (Grants CTQ-2010-14882, CTQ-2009-13699 and JCI-2010-06204), Generalitat Valenciana (Prometeo 2008/90), from CSIC (JAEDOC 101-2011) and from the UPV (Grant No. 20100994 and MCI Program) is gratefully acknowledged.Pérez Ruiz, R.; Sáez Cases, JA.; Domingo, LR.; Jiménez Molero, MC.; Miranda Alonso, MÁ. (2012). Ring splitting of azetidin-2-ones via radical anions. Organic and Biomolecular Chemistry. 10(39):7928-7932. https://doi.org/10.1039/c2ob26528aS79287932103

El aprendizaje servicio (APS) como metodología de aprendizaje jurídico-pedagógico: la reinserción de presos a través de la justicia restaurativa para estudiantes de derecho y de educación social

Se trata de un proyecto innova-docencia que a través de la metodogía PIE-APS profundiza en la detección de las carencias y de los problemas reales que plantean la reinserción de presos, los derechos constitucionales afectados por el problema de la reinserción, y las propuestas actuales de justicia restaurativa que colaboran a dicha reinserción de la población penitenciaria

Efecto de la endozoocoría sobre la germinación, sobrevivencia y crecimiento de la cactácea columnar Eulychnia acida.

Biólogo con mención Medio AmbienteLa pérdida de frugívoros a nivel mundial representa una seria amenaza para la persistencia de las plantas, ya que las interacciones dispersor-planta son fundamentales para la reproducción de estas últimas. Sin embargo, en algunos lugares donde los frugívoros nativos han desaparecido, herbívoros introducidos de gran tamaño pueden actuar como dispersores sustitutos. Una vez que las semillas se han dispersado, pueden germinar inmediatamente o formar banco de semillas. Eulychnia acida es una cactácea columnar endémica que habita la región semiárida de Chile. Estudios previos indican que no hay frugívoros nativos asociados a la dispersión de semillas de este cactus dentro de la Reserva Nacional Las Chinchillas. Sin embargo, existen reportes de animales como la cabra (Capra aegagrus hircus) y el guanaco (Lama guanicoe) consumiendo sus frutos a lo largo del rango de distribución de esta cactácea. En este estudio se evaluó el efecto del paso de semillas de E. acida por el tracto digestivo de C. a. hircus y L. guanicoe, sobre la germinación, sobrevivencia y crecimiento de plántulas. Para ello se, alimentó directamente a C. a. hircus y L. guanicoe con frutos de E. acida para obtener semillas desde sus heces , las que posteriormente fueron usadas en experimentos de germinación y crecimiento. Adicionalmente, se evaluó la capacidad de E. acida de formar banco de semillas y si el paso por el tracto digestivo de las semillas afecta en la viabilidad del banco de semillas de E. acida. Para esto se llevaron a cabo experimentos adicionales un año después de que las semillas hubieran sido recuperadas de las heces de los mamíferos. Los resultados indican que el paso de las semillas por el tracto digestivo de C. a. hircus no tiene efecto sobre la germinación, sobrevivencia o crecimiento de E. acida, mientras que L. guanicoe tiene un efecto negativo sobre la germinación. C. a hircus podría actuar como dispersor al llevar las vii semillas lejos de la planta parental, donde la mortalidad debido a causas denso-dependientes es usualmente mayor. Se detectó un aumento en el porcentaje de germinación en ambos tratamientos para el segundo año del experimento, lo que indica que E. acida podría formar al menos a corto plazo un banco de semillas, lo que se traduciría en efectos positivos para poblaciones de esta especie que habitan en un ambiente altamente variable. Son necesarios estudios adicionales que evalúen la dirección y magnitud de las interacciones entre C. a. hircus y la vegetación nativa para poder generar planes de manejo adecuados para la capricultura en el Norte chico de Chile compatibles con la conservación de especies de plantas endémicas de la zona.Frugivore loss worldwide represents a serious threat for plant persistence because animal disperser-plant interactions are essential for plant reproduction. However, in some places where native frugivorous have disappeared, introduced large herbivore vertebrates may act as surrogate dispersal agents. Once seeds have been dispersed, they can germinate immediately or form a seed bank. Eulychnia acida is an endemic columnar cactus that inhabits the semiarid region of Chile. Previous studies indicate no native frugivorous associated with the dispersal of E. acida inside Las Chinchillas National Reserve. Notwithstanding, there have been reports of goats (Capra aegagrus hircus) and guanacos (Lama guanicoe) consuming its fruit throughout its distribution. In this study the effect of gut passage on the germination, growth and survival of seeds and seedlings of E. acida ingested by L. guanicoe and C. a. hircus was evaluated. To this end, no-choice feeding experiments were performed to obtain seeds consumed by L. guanicoe and C. a. hircus, which were later used in germination and growth experiments. The ability of E. acida to form a seed bank was also examined, and also if gut passage affects the viability of E. acida’s seed bank. To achieve this, additional germination experiments one year after seeds were retrieved from the tested mammals were carried out. Results indicate that C. a. hircus gut passage has no effect on germination, seedling survival or growth, while L. guanicoe had a negative effect on seed germination. C. a. hircus could be carry seeds away from the parent plant where density-dependent seed mortality is usually higher, thus acting as a seed disperser of E. acida. Germination increased the second year of the experiment for both treatments, which indicates that E. acida could form at least a short-term seed bank translating into a positive effect on populations of this species that inhabits a highly ix variable environment. Studies that evaluate the direction and magnitude of biotic interactions between C. a. hircus and the native vegetation are necessary for the generation of adequate programs for the management of C. a. hircus livestock in the North central region of Chile along with conservation of endemic plant species.Al FONDECYT 1140521 y 1150112

Análisis bibliométrico de la investigación realizada en el Departamento de Historia Contemporánea

Sin resume