Post-fire regeneration in Pinus halepensis' forests, one of the most abundant vegetation types in the Mediterranean basin, often generates overstocked and vulnerable stands. They accumulate a high ...fuel load, increasing the risk of further fires, and present high levels of vulnerability due to their reduced seed production. In addition, these dense stands substantially reduce the availability of light and nutrients, which may hinder the recruitment of other species, often generating mono-specific and homogeneous stands, which potentially supply fewer ecosystem services than mixed forests with more heterogeneous structures. In these dense pine stands, management is of high priority to reduce fire hazards and promote their functionality. In overstocked pine stands (>75,000 trees·ha−1), we assessed the long-term effects (10 years) of two thinning levels (600 and 1200 trees·ha−1), in combination with the plantation of Quercus faginea (a resprouter species typical of advanced successional stages in our study area) on 28 above and belowground ecosystem attributes, including fire hazard. After ten years, thinning and plantation interacted to enhance ecosystem attributes associated with disturbance regulation and biodiversity conservation (up to 200%) and food production (up to 90%), while no effects were observed on those attributes related to carbon sequestration and supporting services. These effects were mainly driven by aboveground attributes, as they responded more strongly to our treatments than those belowground. Our results are relevant for the restoration of Mediterranean degraded ecosystems, and show that tree thinning in overstocked pine stands, combined with the plantation of resprouter species, may not only reduce fire risks and accelerate post-fire succession but also enhance the supply of multiple ecosystem services in the long run.
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•The combination of thinning and resprouter plantation improved ecosystem functions.•Moderate thinning suffices to enhance individual aboveground attributes.•Plantation of resprouter species helps to maximize ecosystem services.•Ecosystem responses to management are driven by aboveground but not belowground attributes.
• Recent observations suggest that repeated fires could drive Mediterranean forests to shrublands, hosting flammable vegetation that regrows quickly after fire. This feedback supposedly favours ...shrubland persistence and may be strengthened in the future by predicted increased aridity. An assessment was made of how fires and aridity in combination modulated the dynamics of Mediterranean ecosystems and whether the feedback could be strong enough to maintain shrubland as an alternative stable state to forest.
• A model was developed for vegetation dynamics, including stochastic fires and different plant fire-responses. Parameters were calibrated using observational data from a period up to 100 yr ago, from 77 sites with and without fires in Southeast Spain and Southern France.
• The forest state was resilient to the separate impact of fires and increased aridity. However, water stress could convert forests into open shrublands by hampering post-fire recovery, with a possible tipping point at intermediate aridity.
• Projected increases in aridity may reduce the resilience of Mediterranean forests against fires and drive post-fire ecosystem dynamics toward open shrubland. The main effect of increased aridity is the limitation of post-fire recovery. Including plant fire-responses is thus fundamental when modelling the fate of Mediterranean-type vegetation under climate-change scenarios.
The ecological stability of Mediterranean ecosystems is being threatened by climate change. One of the impacts that is expected to be aggravated is the effect of summer drought prolongation toward ...previous or subsequent seasons by becoming more frequent. This, along with wildfires, could trigger synergistic negative effects on ecosystem regeneration capacity. Here we assessed how extending summer drought in two different ways (to autumn, AutExcl treatment, or bringing it forward to the following spring, SprExcl treatment) would affect plant recovery after an experimental fire carried out in summer in a Mediterranean seeder community. By installing rainout shelters, we assessed differences in seedling emergence, survival and establishment in the main families (Cistaceae, Labiatae, Leguminosae), and the effect on species richness and community composition. We observed that these post-fire dry season extensions reduced the total number of established seedlings and species richness. The most impacting drought treatment was AutExcl. However, the regeneration response was variable depending on the studied family. SprExcl was also determinant for Labiate survival rates. These results suggest that drought events which prolong the usual summer season may have a permanent drought legacy effect on seeder communities as practically all the seeder species populations were established in the first post-fire year. This fact is relevant for Mediterranean ecosystems dominated by seeder species as severer and longer droughts are increasingly recorded and are expected to become more frequent in forthcoming decades.
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•Climate change alters the recurrence, prolongation or temporality of summer droughts.•Prolonged summer-droughts events in critical periods negatively impacts the post-fire regeneration.•Seedling emergence, survival and establishment are affected differently depending on the plant family.•Extended summer drought after a fire may have a permanent drought legacy.
The extensive abandonment of agricultural lands in the Mediterranean basin has led to large landscapes being dominated by early-successional species, characterized by high flammability and an ...increasing fire risk. This fact promotes fire occurrence and places ecosystems in a state of arrested succession. In this work, we assessed the effectiveness of several restoration actions in redirecting these ecosystems toward more resilient communities dominated by resprouting species. These actions included the mechanical clearing of early-successional species, the plantation of resprouting species, and the combination of both treatments. For 13 years, we assessed shifts in the successional trajectory and ecosystem flammability by changes in: species composition, species richness, ecosystem evenness, the natural colonization of resprouting species, total biomass and proportion of dead biomass. We observed that the plantation and clearing combination was a suitable strategy to promote resilience. Species richness increased as well as the presence of the resprouting species introduced by planting. The natural colonization of the resprouting species was also enhanced. These changes in the successional trajectory were accompanied by a possible reduction of fire risk by reducing dead fuel proportion. These findings are relevant for the management of Mediterranean basin areas, but also suggest new tools for redirecting systems in fire-prone areas worldwide.
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•Large landscapes are dominated by highly flammable species with high fire risk.•Clearing and planting key species can be suitable management strategies.•Restoration actions displace the system towards a more resilient community.•The introduction of resprouters to the detriment of seeder species is a key step.
Chagas disease is caused by the protozoan Trypanosoma cruzi, affecting around 8 million people worldwide. After host cell invasion, the infective trypomastigote form remains 2-4 hours inside acidic ...phagolysosomes to differentiate into replicative amastigote form. In vitro acidic-pH-induced axenic amastigogenesis was used here to study this step of the parasite life cycle. After three hours of trypomastigote incubation in amastigogenesis promoting acidic medium (pH 5.0) or control physiological pH (7.4) medium samples were subjected to three rounds of centrifugation followed by ultrafiltration of the supernatants. The resulting exoproteome samples were trypsin digested and analysed by nano flow liquid chromatography coupled to tandem mass spectrometry. Computational protein identification searches yielded 271 and 483 protein groups in the exoproteome at pH 7.4 and pH 5.0, respectively, with 180 common proteins between both conditions. The total amount and diversity of proteins released by parasites almost doubled upon acidic incubation compared to control. Overall, 76.5% of proteins were predicted to be secreted by classical or non-classical pathways and 35.1% of these proteins have predicted transmembrane domains. Classical secretory pathway analysis showed an increased number of mucins and mucin-associated surface proteins after acidic incubation. However, the number of released trans-sialidases and surface GP63 peptidases was higher at pH 7.4. Trans-sialidases and mucins are anchored to the membrane and exhibit an enzyme-substrate relationship. In general, mucins are glycoproteins with immunomodulatory functions in Chagas disease, present mainly in the epimastigote and trypomastigote surfaces and could be enzymatically cleaved and released in the phagolysosome during amastigogenesis. Moreover, evidence for flagella discard during amastigogenesis are addressed. This study provides the first comparative analysis of the exoproteome during amastigogenesis, and the presented data evidence the dynamism of its profile in response to acidic pH-induced differentiation.
The Pharmacopea within Triatomine Salivary Glands Santiago, Paula B.; de Araújo, Carla N.; Charneau, Sébastien ...
Trends in parasitology,
March 2020, 2020-Mar, 2020-03-00, 20200301, Volume:
36, Issue:
3
Journal Article
Peer reviewed
Triatomines are blood-feeding insects that prey on vertebrate hosts. Their saliva is largely responsible for their feeding success. The triatomine salivary content has been studied over the past ...decades, revealing multifunctional bioactive proteins targeting the host´s hemostasis and immune system. Recently, sequencing of salivary-gland mRNA libraries revealed increasingly complex and complete transcript databases that have been used to validate the expression of deduced proteins through proteomics. This review provides an insight into the journey of discovery and characterization of novel molecules in triatomine saliva.
There are currently nine annotated sialotranscriptomes, six descriptive sialoproteomes, and seven sialomes from triatomine bugs.Gene duplication events generated many salivary protein families.There are at least 100 salivary proteins produced by a single species, with substantial interspecies diversity.These proteins inhibit blood coagulation, platelet aggregation, and complement activation, and they induce vasodilation and immune modulation.Many protein families remain enigmatic, without similarities to known proteins or motifs, and without a known function.
Determining the structure and fuel load is key to know the flammability of vegetation in the Mediterranean Basin where forest fires are frequent. Determine which plant structural variable is best ...related to living and dead fuel to develop allometric equations in nine species in the Western Mediterranean Basin. In the east of the Iberian Peninsula (Valencia Province), we measured four structural variables (basal stem diameter, height, maximum diameter and perpendicular diameter) that were related, by means of allometric equations, to the living and dead fuel separated into different size classes. We also analyze fuel changes across developmental states of the studied species, and the vertical distribution of dead fuel. General equations that consider all development states can be used to determine living fuel. However to obtain dead fuel, we recommend using specific equations for each development state and fuel fraction for better accuracy. The basal stem diameter was the best structural variable in almost all cases for estimating fuel in the studied species. Dead fuel load throughout species’ ontological development is a key factor to manage Mediterranean plant communities.
We studied the soil seed bank in a possible scenario of fire regime shift and asked: (1) Does high fire frequency impact the density of seeds stored, species richness and evenness? (2) Overall, does ...high fire frequency produce changes in the presence–absence and abundance of species? The study was implemented in a Mediterranean Basin ecosystem in plots with increasing fire frequency (unburned, burned once and burned twice in the last 66 years). The number of seeds increased with fire frequency for all life forms (shrub, scrub, perennial forb, annual forb and perennial graminoid). Species richness of annual forbs also increased. Evenness of shrubs diminished because the number of seeds in all the species decreased, except C. albidus, which increased. Overall, differences in the abundance of species were found, mainly by depleting shrubs and increasing forbs. There were no differences in the presence–absence data. In conclusion, high fire frequencies act as a filtering factor for species of a larger size and advanced maturity age. In contrast, life forms of small size and rapid onset of reproductive maturity can be enhanced. This community conversion from woody to herbaceous soil seed banks is fundamental to identify vegetation changes in future regimes of high fire frequency.
Chagas disease is a debilitating and neglected disease caused by the protozoan
. Soon after infection, interactions among
and host innate immunity cells can drive/contribute to disease outcome. ...Dendritic cells (DCs), present in all tissues, are one of the first immune cells to interact with
metacyclic trypomastigotes. Elucidating the immunological events triggered immediately after parasite-human DCs encounter may aid in understanding the role of DCs in the establishment of infection and in the course of the disease. Therefore, we performed a transcriptomic analysis of a 12 h interaction between
and MoDCs (monocyte-derived DCs) from three human donors. Enrichment analyses of the 468 differentially expressed genes (DEGs) revealed viral infection response as the most regulated pathway. Additionally, exogenous antigen processing and presentation through MHC-I, chemokine signaling, lymphocyte co-stimulation, metallothioneins, and inflammasome activation were found up-regulated. Notable, we were able to identify the increased gene expression of alternative inflammasome sensors such as AIM2, IFI16, and RIG-I for the first time in a
infection. Both transcript and protein expression levels suggest proinflammatory cytokine production during early
-DCs contact. Our transcriptome data unveil antiviral pathways as an unexplored process during
-DC initial interaction, disclosing a new panorama for the study of Chagas disease outcomes.
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