Suchergebnisse

Plant–pollinator interactions are one of the most important and variable mutualisms having major implications for plant fitness. The present study evaluates the interactions between an endemic milkwort, Polygala vayredae, and its floral visitors by studying the temporal variability, foraging behaviour and effectiveness of floral visitors in three populations during three consecutive years. The flowers were visited by a diverse array of insects, totalling 24 different species. However, only four species were effective pollinators, depositing pollen on stigmas after one visit, while the remaining species behaved as nectar robbers, secondary nectar robbers or nectar thieves and were completely ineffective for pollination. Among the effective pollinators, two groups with distinct foraging behaviours were observed: the nectar collecting long-tongued bees Bombus pascuorum and Anthophora sp. and the pollen collectors Eucera longicornis and Halictus sp. No significant differences were observed among pollinators in their efficiency in pollen deposition on stigmas, but significant differences were observed in the foraging behaviour between nectarivorous and pollen collectors. Variation in the abundance and assemblage of floral visitors was observed at the temporal scale and among populations, with the effective pollinators being generally scarce. Consequently, the reproductive outcome in this species was low and significantly variable among populations and years. The results highlight the importance of studying floral visitor effectiveness when determining pollinator assemblages. ; The Portuguese Foundation for Science and Technology financed the work of Sılvia Castro (FCT/BD/10901/2002 and FCT/BPD/41200/2007). Victoria Ferrero was funded by a Xunta de Galicia postdoctoral contract. The work was partially financed under the grants from the Xunta de Galicia (INCITE09-3103009PR), CGL2009- 10466 of the Spanish Direccion General de Investigacion, Ciencia y Tecnologıca (DGICYT) and FEDER funds from the European Union to Luis Navarro.

Reproduction is a key factor for the successful establishment and spread of introduced species. Oxalis pes-caprae is a tristylous species with a self- and morph-incompatibility sexual system that, in the invaded range of the western Mediterranean Basin, has been found to reproduce asexually because only the pentaploid, short-styled morph (5x S-morph) was introduced. The objective of this study was to test the ability of the 5x S-morph of O. pes-caprae to produce viable offspring in the absence of compatible mates, exploring the hypothesis that new morphs could have emerged by sexual reproduction events of the initially introduced morph. Pollen germination, pollen tube development, fruit and seed production, seed germination and offspring ploidy levels were analysed after controlled hand-pollinations to assess self- and morph-incompatibility and production of viable gametes by the 5x S-morph. The self-incompatibility system is still operating, but a partial breakdown in the morph-incompatibility system combined with the production of viable gametes was observed, allowing sexual reproduction of the 5x S-morph in the invaded range. The ability of the 5x S-morph to reproduce sexually may have major consequences for the dynamics of invasive populations of O. pes-caprae and could be one of the factors involved in the occurrence of new floral morphs in this invaded range. ; This research was supported by Portuguese Foundation for Science and Technology (FCT) with the project PTDC/BIA-BIC/ 110824/2009, by CRUP Acc ~oes Integradas Luso-Espanholas 2010 with the project E10/10, by the Spanish DGICYT (CGL2009-10466), FEDER funds from the European Union, and the Xunta de Galicia (INCITE09-3103009PR). FCT also financed the work of Joana Costa (CB/C05/2009/209; PTDC/ BIA-BIC/110824/2009) and S ılvia Castro (FCT/BPD/41200/ 2007). Fundaci on Ram on Areces financed the work of Victoria Ferrero through a post-doctoral grant.

Removal of invasive species often benefits biological diversity allowing ecosystems' recovery. However, it is important to assess the functional roles that invaders may have established in their new areas to avoid unexpected results from species elimination. Invasive animal-pollinated plants may affect the plant–pollination interactions by changing pollinator availability and/or behaviour in the community. Thus, removal of an invasive plant may have important effects on pollinator community that may then be reflected positive or negatively on the reproductive success of native plants. The objective of this study was to assess the effect of removing Oxalis pescaprae, an invasive weed widely spread in the Mediterranean basin, on plant–pollinator interactions and on the reproductive success of co-flowering native plants. For this, a disturbed area in central Portugal, where this species is highly abundant, was selected. Visitation rates, natural pollen loads, pollen tube growth and natural fruit set of native plants were compared in the presence of O. pes-caprae and after manual removal of their flowers. Our results showed a highly resilient pollination network but also revealed some facilitative effects of O. pes-caprae on the reproductive success of co-flowering native plants. Reproductive success of the native plants seems to depend not only on the number and diversity of floral visitors, but also on their efficiency as pollinators. The information provided on the effects of invasive species on the sexual reproductive success of natives is essential for adequate management of invaded areas. ; This work is financed by FEDER funds through the COMPETE Program and by Portuguese Foundation for Science and Technology (FCT) funds in the ambit of the project PTDC/ BIA-BIC/110824/2009, by CRUP Acc¸o˜es Integradas Luso- Espanholas 2010 with the project E10/10, by MCI-Programa de Internacionalizacio´n de la I ? D (PT2009-0068) and by the Spanish DGICYT (CGL2009-10466), FEDER funds from the European Union, and the Xunta de Galicia (INCITE09- 3103009PR). FCT also supported the work of S. Castro (FCT/ BPD/41200/2007) and J. Costa (CB/C05/2009/209; PTDC/ BIA-BIC/110824/2009). The work of V. Ferrero was supported by the Fundacio´n Ramo´n Areces.

Protein kinase C (PKC) isozymes play major roles in human diseases, including cancer. Yet, the poor understanding of isozymes-specific functions and the limited availability of selective pharmacological modulators of PKC isozymes have limited the clinical translation of PKC-targeting agents. Here, we report the first small-molecule PKCd-selective activator, the 7a-acetoxy-6ß-benzoyloxy-12-O-benzoylroyleanone (Roy-Bz), which binds to the PKCd-C1-domain. Roy-Bz potently inhibited the proliferation of colon cancer cells by inducing a PKCd-dependent mitochondrial apoptotic pathway involving caspase-3 activation. In HCT116 colon cancer cells, Roy-Bz specifically triggered the translocation of PKCd but not other phorbol ester responsive PKCs. Roy-Bz caused a marked inhibition in migration of HCT116 cells in a PKCd-dependent manner. Additionally, the impairment of colonosphere growth and formation, associated with depletion of stemness markers, indicate that Roy-Bz also targets drug-resistant cancer stem cells, preventing tumor dissemination and recurrence. Notably, in xenograft mouse models, Roy-Bz showed a PKCd-dependent antitumor effect, through anti-proliferative, pro-apoptotic, and anti-angiogenic activities. Besides, Roy-Bz was non-genotoxic, and in vivo it had no apparent toxic side effects. Collectively, our findings reveal a novel promising anticancer drug candidate. Most importantly, Roy-Bz opens the way to a new era on PKC biology and pharmacology, contributing to the potential redefinition of the structural requirements of isozyme-selective agents, and to the re-establishment of PKC isozymes as feasible therapeutic targets in human diseases. ; We thank European Union (FEDER funds POCI/01/0145/FEDER/007728, FCOMP-01-0124-FEDER-028417 and POCI-01-0145-FEDER-007440, through Programa Operacional Factores de Competitividade—COMPETE) and National Funds (FCT/MEC, Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência) under the Partnership Agreement PT2020 UID/MULTI/ 04378/2013, UID/NEU/04539/2013, UID/DTP/04567/2016, and the project (3599-PPCDT) PTDC/DTP-FTO/1981/2014—POCI-01-0145-FEDER-016581, as well as Centro 2020 Regional Operational Programmes (CENTRO-01-0145-FEDER-000012: HealthyAging2020). FCT fellowships: SFRH/BD/87109/2012 (C. Bessa), SFRH/BD/117949/2016 (L. Raimundo), and SFRH/BD/128673/2017 (J. B. Loureiro).