Landscape context on generalist and specialist aphid natural enemies

Report for the scientific sojourn at the University of Lund, Sweden, between May and September 2007. A landscape-scale research approach has been highlighted by a growing body of literature as essential for understanding important ecosystem services as biological control. Aphids are victims of a diversity of enemies making the aphid-enemy interaction a nice example for the role of enemy diversity for the functioning of biological control. Here it is examined the effects of landscape complexity on cereal aphids and associated natural enemies that varied in the degree of specialization. Parasitoids wasps abundance did not differ between landscape types but was strongly negatively related to the percentage of arable land. In contrast, abundances of generalist predators like Coccinellidae were significantly higher in simple landscapes since can benefit from the high availability of a variety of alternative resources within cropping systems. Consequently coccinellidae-to-aphid ratio was significantly higher in fields in homogenous landscapes as compared to fields included in an heterogeneous landscape, suggesting that enemy pressure on cereal aphids increases with landscape simplification. The landscape effect will depend mainly on the degree of specialization of functionally dominant natural enemies, so that the results imply that conservation actions aiming to optimise abundance for one taxonomic group in the agricultural landscape will not automatically increase abundance of other groups. Given that the strength of natural enemy impact on biocontrol depends on landscape features and the role of functionally dominant natural enemies. So, therefore it is essential to focus the future empirical work in examining the schedule of agricultural landscapes that maintain a diversity of generalist and specialist natural enemies.

Identificació de noves dianes terapèutiques en neoplàsies limfoides

El limfoma de cèl•lules de mantell (LCM) és un limfoma de cèl•lules B incurable que presenta sobreexpressió de ciclina D1. Això fa necessari el desenvolupament de noves teràpies. Els gens supressors de tumors estan alterats en càncer pel silenciament epigenètic aberrant, com a conseqüència de la desacetilació de les histones dels seus promotors. Els inhibidors de les desacetilases d'histones (HDACi) són nous compostos amb resultats prometedors per al tractament de tumors. L'objectiu principal, i que ha durat 7 mesos, va ser analitzar l'activitat antitumoral de l'àcid hidroxàmic suberoilanílid (SAHA, vorinostat), un HDACi en fase d'assajos clínics per al tractament de varis tumors, en cèl•lules de LCM. Es va analitzar la sensibilitat al SAHA (Merck Pharmaceuticals) en nou línies cel•lulars humanes de LCM, que es diferenciaven en les alteracions genètiques, les característiques replicatives i la sensibilitat als fàrmacs; i cèl•lules primàries de 6 pacients. El SAHA va presentar un efecte citotòxic heterogeni amb DL50 (Dosi Letal 50) de 3.25 μM a &25 μM amb 24 d'incubació. Aquest efecte citotòxic s'incrementava notablement després de 48 hores d'incubació assolint una DL50 de 0.34 a 5.69 μM. Cal destacar que 5 dels 6 casos de les mostres primàries de LCM van mostrar una elevada sensibilitat (DL50 & 8.07 μM). A nivell mecanistic, el SAHA va augmentar l'acetilació de les histones H3 i H4, i va disminuir els nivells de proteïna de la ciclina D1 i c-Flip. La citometria de flux i els anàlisis per Western Blot van posar de manifest que l'efecte citotòxic del SAHA es dóna a través de l'activació de la via mitocondrial de mort cel•lular i la cascada de caspases. El SAHA indueix l'expressió transcripcional de la proteïna proapoptòtica Bmf. Aquests resultats suggereixen que el SAHA podria ser una nova teràpia prometedora per al tractament del LCM.

The Electoral Determinants of Collective Remittances: The Mexican 3x1 Program for Migrants

The 3x1 Program for Migrants is a matching grant scheme that seeks to direct the money sent by migrant organizations abroad to the provision of public and social infrastructure, and to productive projects in migrants’ communities of origin. To do so, the municipal, state, and federal administrations match the amount sent by hometown associations by 3 to 1. This opens the door to the political manipulation of the program. We explore the impact of a particular facet of Mexican political life on the operation of the 3x1: its recent democratization and the increasing political competition at the municipal level. Relying on the literature on redistributive politics, we posit that an increasing number of effective parties in elections may have two different effects. On the one hand, the need to cater to more heterogeneous constituencies may increase the provision of public projects. On the other hand, since smaller coalitions are needed to win elections under tighter competition, fewer public and more private (clientelistic) projects could be awarded. Using a unique dataset on the 3x1 Program for Migrants for over 2,400 municipalities in the period 2002 through 2007, we find a lower provision of public goods in electorally competitive jurisdictions. Thus, we remain sceptical about the program success in promoting public goods in politically competitive locations with high migration levels.