Biology subjects

Quevedo, A.

Publications and source records attributed to Quevedo, A..

3 recordsLinked to original sources

bioRxiv2024

Pollination services to crops of watermelon (Citrullus lanatus) and green tomato (Physalis ixocarpa) in the coastal region of Jalisco, Mexico

Bees play a pivotal role as pollinators in crops crucial for human consumption. However, the global decline in bee populations poses a significant threat to pollination services and food security worldwide. The loss and fragmentation of habitats due to land-use change are primary factors contributing to bee declines, particularly in tropical forests facing high deforestation rates. Here we evaluate the pollination services on crops of watermelon (Citrullus lanatus) and green tomato (Physalis ixocarpa) in the Tropical Dry Forest of Jalisco, Mexico during 2008, and 2014 to 2017. We describe pollinator community composition and visitation frequency and evaluate pollinator contribution to plant reproductive success and degree of pollinator dependence for each crop species. We also assess how landscape configuration influences the abundance and richness of pollinators, and we use the model Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) to map and value the pollination service in both crops. Our findings reveal that the main pollinator of both crops was Apis mellifera, one of the few abundant pollinators in the study region during the dry season, when watermelon and green tomato are cultivated. Results revealed that in the absence of pollinators, watermelon yielded no fruits, while green tomato experienced a 65% reduction in production. For green tomato, fruit set was positively correlated with pollinator abundance. A positive association between forest cover and total pollinator abundance was observed in green tomato in 2008, but not in watermelon. We also found a positive relationship between the abundance of bees predicted by the InVEST model and the abundance of bees observed in green tomato flowers in 2008. In the study region, green tomato and watermelon rely on pollinators for fruit production, with honeybees (from feral and managed colonies) acting as the most importante provider of pollination services for these crops. Consequently, the conservation of natural protected areas is crucial for sustaining pollinators and ensuring food security.

ecology↗

bioRxiv2020

Experimental Evolution of Pseudomonas putida under Silver Ion versus Nanoparticle Stress

Whether the antibacterial properties of silver nanoparticles (AgNPs) are simply due to the release of silver ions (Ag+) or, additionally, nanoparticle-specific effects, has been debated for over a decade. We used experimental evolution of the model environmental bacterium Pseudomonas putida to ask whether bacteria respond differently to Ag+ or AgNP treatment. We pre-evolved five cultures of strain KT2440 for 70 d without Ag to reduce confounding adaptations before dividing the fittest pre-evolved culture into five cultures each, evolving in the presence of low concentrations of Ag+, well-defined AgNPs or Ag-free controls for a further 75 d. The mutations in the Ag+ or AgNP evolved populations displayed different patterns that were statistically significant. The non-synonymous mutations in AgNP-treated populations were mostly associated with cell surface proteins, including cytoskeletal membrane protein (FtsZ), membrane sensor and regulator (EnvZ and GacS) and periplasmic protein (PP_2758). In contrast, Ag+ treatment selected for mutations linked to cytoplasmic proteins, including metal ion transporter (TauB) and those with metal binding domains (ThiL and PP_2397). These results suggest the existence of AgNP-specific effects, either caused by sustained delivery of Ag+ from AgNP-dissolution, more proximate delivery from cell-surface bound AgNPs, or by direct AgNP action on the cells outer membrane. Originality-Significance StatementThe increasing use of silver nanoparticles (AgNPs) and their release into the environment may affect environmental microorganisms and their communities and evolution. It has long been debated whether the toxicity of AgNPs towards microorganisms is solely due to their dissolution into toxic Ag+ or whether distinct nanoparticle related toxicity exists. We set up an evolution experiment to explore the adaptation of the environmental model bacterium Pseudomonas putida to Ag+ versus AgNP stress in order to elucidate the potentially different toxicity mechanisms of ionic and nanoparticulate Ag. We found novel mutations and distinct mutation patterns under Ag+ and AgNP treatment by whole genome sequencing. Our work highlights the association of the mutations selected by Ag+ stress with metal ion metabolism inside the cells and the mutations specific to AgNP stress with the cells surface. The finding that P. putida cells evolved in different directions under selection by Ag+ and AgNPs demonstrates a need for assessing the toxicity of nanomaterials separately in any environmental risk assessments.

pharmacology and toxicology↗

bioRxiv2020

Dpp and Hedgehog promote the Glial response to neuronal damage in the developing Drosophila Visual system

Damage in the nervous system induces a stereotypical response that is mediated by glial cells. Here, we use the eye disc to explore the mechanisms involved in promoting glial cell response after neural injuries. We demonstrate that eye glia cells rapidly respond to neuronal injury by increasing in number and undergoing morphological changes, which grant them phagocytic abilities. We found that this glial response is controlled by the activity of the long-range signalling pathways, decapentaplegic (dpp) and hedgehog (hh). These pathways are activated in the damaged region and their functions are necessary for inducing glial cell proliferation and migration to the eye discs. The latter of these two processes depends on the function of the JNK pathway, which is cooperatively activated by dpp and hh signalling.

neuroscience↗