Urolithins are bioactive gut microbiota metabolites of ellagic acid. Here, we have identified four unknown urolithins in human feces after the intake of a pomegranate extract. The new metabolites ...occurred only in 19% of the subjects. 4,8,9,10-Tetrahydroxy urolithin, (urolithin M6R), was unambiguously identified by 1H NMR, UV, and HRMS. Three metabolites were tentatively identified by the UV, HRMS, and chromatographic behavior, as 4,8,10-trihydroxy (urolithin M7R), 4,8,9-trihydroxy (urolithin CR), and 4,8-dihydroxy (urolithin AR) urolithins. Phase II conjugates of the novel urolithins were detected in urine and confirmed their absorption, circulation, and urinary excretion. The production of the new urolithins was not specific of any of the known urolithin metabotypes A and B. The new metabolites needed a bacterial 3-dehydroxylase activity for their production, and this is a novel feature as all the previously known urolithins maintained the hydroxyl at 3 position. The ability of production of these “R” urolithins can be considered an additional metabolic feature for volunteer stratification.
We use the optimal foraging theory to study coexistence between two plant species and a generalist pollinator. We compare conditions for plant coexistence for non-adaptive vs. adaptive pollinators ...that adjust their foraging strategy to maximize fitness. When pollinators have fixed preferences, we show that plant coexistence typically requires both weak competition between plants for resources (e.g., space or nutrients) and pollinator preferences that are not too biased in favour of either plant. We also show how plant coexistence is promoted by indirect facilitation via the pollinator. When pollinators are adaptive foragers, pollinator's diet maximizes pollinator's fitness measured as the per capita population growth rate. Simulations show that this has two conflicting consequences for plant coexistence. On the one hand, when competition between pollinators is weak, adaptation favours pollinator specialization on the more profitable plant which increases asymmetries in plant competition and makes their coexistence less likely. On the other hand, when competition between pollinators is strong, adaptation promotes generalism, which facilitates plant coexistence. In addition, adaptive foraging allows pollinators to survive sudden loss of the preferred plant host, thus preventing further collapse of the entire community.
1. Seed dispersal is thought to be unpredictable and outside a plant's control. But directed seed dispersal by mutualistic birds can increase probabilities of germination and survival by the ...non-random deposition of seeds in suitable microhabitats. 2. In the Sonoran Desert grasslands of southern Arizona (USA), bird-dispersed wild chiltepin peppers (Capscium annuum var. glabriusculum) grow in non-random association under bird-dispersed nurse trees and shrubs that serve as perches. We tested the hypothesis that the pattern is maintained by directional avian seed-dispersal patterns. Alternatively, post-dispersal processes, such as differential seed predation and seedling mortality, could create the associations. 3. For 3 years, we sampled the bird-generated seed rain under desert trees in four chiltepin subpopulations, comparing seed dispersal into microhabitats of fleshy-fruited trees and non-fleshy-fruited trees. Celtis pallida (fleshy-fruited) and Prosopis vellutina (non-fleshy-fruited) trees accounted for > 90% of the cover available for chiltepin recruitment. We tracked seedling emergence and survival in the two microhabitats and conducted a controlled seed-addition experiment to measure the effects of microhabitat, seed-addition density and temporal seed deposition on chiltepin emergence, growth and survival. 4. Approximately twice as many bird-dispersed seeds arrived at fleshy-fruited microhabitats compared with non-fleshy microhabitats. The numbers of seeds arriving and the number of seedlings emerging in microhabitats the following year were positively correlated. Survival of naturally emerged seedlings was similar at both microhabitats, but the seed-addition experiment revealed that more seeds are able to emerge under the denser foliage of fleshy-fruited microhabitats. The experiment also shows a significant effect of temporal deposition: when seeds were added gradually in a microhabitat (emulating repeated avian seed deposition under perches) instead of all at once, seedling emergence increased twofold on average. 5. Synthesis: Birds dispersed disproportionally high quantities of chiltepin seeds into favourable recruitment microhabitats, showing a case of directed dispersal. Birds also increase seedling emergence through the temporal deposition of seeds under fleshy-fruited trees, most likely as a result of reducing the odds of seed predation. A coupling between directed seed dispersal with classic facilitative plant–plant interactions leads to the formation of pattern and self-organization in a plant community.
Aim Biological invasions pose one of the most severe threats to global biodiversity. Still, invasions can create positive ecological relationships and services, which can sometimes result in ...challenges for conservation efforts. A case in point is the invasion of alien plants that form mutualisms with native frugivorous birds. Here, we examined the correlation between honeysuckles (Lonicera spp.) and the bird communities in a landscape of central Pennsylvania during the fall months. Location State College area in central Pennsylvania, USA. Methods We conducted point counts to quantify the abundance of birds and fleshy-fruited plant species within a 187.5 km² landscape that included forested, urban and agricultural lands. We also compared fruit-removal rates for a native fruiting plant under low and high Lonicera densities. Results The abundance of birds showed a strong positive association with Lonicera fruits, with the abundance of Turdus migratorius and Dumetella carolinensis showing the strongest correlations. We also found that fruit-removal rates were 30% larger for a native plant species in areas of high Lonicera density compared to a site with low density of Lonicera. Main conclusions Our results suggest that Lonicera may currently serve as a main axis for the organization of bird communities and the networks of frugivore-plant interactions in central Pennsylvania. Since populations of key bird frugivores may be currently depending on Lonicera resources, we argue that control measures should account for the negative effects that the loss of this fruit resource could have on populations of native consumers in highly invaded regions.
Seabirds create fluxes of nutrients from marine to terrestrial ecosystems that influence the food webs of small islands. We investigated how guano inputs shape terrestrial food webs by comparing ...species of selected plant and animal species in a red-footed booby colony in Mona Island (Puerto Rico, Caribbean Sea), to sites of the island lacking guano inputs. We quantified guano deposition and its relationship to plant biomass production, fecundity and density, as well as the activity of native and introduced animal species. In general, guano inputs increased the gross primary plant productivity, size, and fecundity by twofold. Guano inputs were also associated with twofold increases in density of Anole lizards, but also to increases in the activity of introduced pigs (> 500%), goats (> 30%), and cats (> 500%), which negatively impact native species. In particular, elevated pig and cat activity within the booby colony was correlated with lower activity of endemic ground lizards and of introduced rats. Our results also suggest that severe droughts associated with climate change exacerbate the negative effects that introduced species have on vegetation and reduce the positive effects of seabird guano inputs. Our findings underscore the importance of allochthonous guano inputs in subsidizing plant productivity and native and endemic species in small oceanic islands, but also in increasing the negative impacts of introduced mammals. Management and conservation efforts should focus on the exclusion (or eradication) of introduced mammals, particularly pigs and goats, from remnant seabird colonies in Mona Island.
Ellagic acid (EA) is converted to urolithins by gut microbiota. Urolithins have beneficial biological effects in humans, but differences in urolithin production capacity among individuals have been ...shown. Therefore, the identification of the urolithin production pathways and the microorganisms implicated is of high interest. EA was incubated with gut microbiota from two volunteers able to produce urolithins but with different in vivo urolithin profiles (urolithin A and isourolithin A producers). The metabolic capabilities observed in vivo were retained in vitro. Both individuals showed a much higher abundance of Clostridium leptum group of Firmicutes phylum than Bacteroides/Prevotella. EA was either dissolved in DMSO or suspended in water. DMSO increased EA solubility but decreased urolithin production rate due to a delay in growth of some microbial groups, principally, Clostridium coccoides. This allowed the detection of catabolic intermediates urolithins M-5, M-6, M-7, C, and 2,3,8,10-tetrahydroxy urolithin (urolithin E). Bacteria from C. coccoides group (or genera co-occurring in vivo with this group) seem to be involved in production of different urolithins.
Mycorrhizal fungi form mutualistic associations with the roots of most land plants and provide them with mineral nutrients from the soil in exchange for fixed carbon derived from photosynthesis. The ...common symbiosis pathway (CSP) is a conserved molecular signaling pathway in all plants capable of associating with arbuscular mycorrhizal fungi. It is required not only for arbuscular mycorrhizal symbiosis but also for rhizobia-legume and actinorhizal symbioses. Given its role in such diverse symbiotic associations, we hypothesized that the CSP also plays a role in ectomycorrhizal associations. We showed that the ectomycorrhizal fungus
produces an array of lipochitooligosaccharides (LCOs) that can trigger both root hair branching in legumes and, most importantly, calcium spiking in the host plant
in a
-dependent manner. Nonsulfated LCOs enhanced lateral root development in
in a calcium/calmodulin-dependent protein kinase (
)-dependent manner, and sulfated LCOs enhanced the colonization of
by
Compared with the wild-type
, the colonization of
/
and
RNA interference lines by
was reduced. Our work demonstrates that similar to other root symbioses,
uses the CSP for the full establishment of its mutualistic association with
.
Many mutualisms involve inter-specific resource exchanges, making consumer–resource approaches ideal for studying their dynamics. Also in many cases these resources are short lived (e.g. flowers) ...compared with the population dynamics of their producers and consumers (e.g. plants and insects), which justifies a separation of time scales. As a result, we can derive the numerical response of one species with respect to the abundance of another. For resource consumers, the numerical responses can account for intra-specific competition for mutualistic resources (e.g. nectar), thus connecting competition theory and mutualism mechanistically. For species that depend on services (e.g. pollination, seed dispersal), the numerical responses display saturation of benefits, with service handling times related with rates of resource production (e.g. flower turnover time). In both scenarios, competition and saturation have the same underlying cause, which is that resource production occurs at a finite velocity per individual, but their consumption tracks the much faster rates of population growth characterizing mutualisms. The resulting models display all the basic features seen in many models of facultative and obligate mutualisms, and they can be generalized from species pairs to larger communities.
•Simple resource-based mechanisms of mutualism are proposed.•Resource ephemerality allows the derivation of mechanistic numerical responses.•Limitations in resource delivery cause diminishing returns of mutualistic service.•Consumers of mutualistic resources follow Schoener׳s competition equations.
Climate change can alter species phenologies and therefore disrupt species interactions. Habitat destruction can damage biodiversity and population viability. However, we still know very little about ...the potential effects of these two factors on the diversity and structure of interaction networks when both act simultaneously. Here we developed a mutualistic metacommunity model to explore the effects of habitat destruction and phenological changes on the diversity and structure of plant–pollinator networks. Using an empirical data set of plant and pollinator interactions and their duration in days, we simulated increasing levels of habitat destruction, under projected scenarios of phenological shifts as well for historically recorded changes in phenologies. On one hand, we found that habitat destruction causes catastrophic collapse in global diversity, as well as inducing alternative states. On the other hand, phenological shifts tend to make interactions weaker, increasing local extinction rates. Together, habitat destruction and phenological changes act synergistically, making metacommunities even more vulnerable to global collapse. Metacommunities are also more vulnerable to collapses under scenarios of historical change, in which phenologies are shortened, not just shifted. Furthermore, connectance and nestedness tends to decrease gradually with habitat destruction before the global collapse. Small phenological shifts can raise connectance slightly, due novel interactions appearing in a few generalist species, but larger shifts always reduce connectance. We conclude that the robustness of mutualistic metacommunities against habitat destruction can be greatly impaired by the weakening of positive interactions that results from the loss of phenological overlap.
The design of plant tissue culture media remains a complicated task due to the interactions of many factors. The use of computer-based tools is still very scarce, although they have demonstrated ...great advantages when used in large dataset analysis. In this study, design of experiments (DOE) and three machine learning (ML) algorithms, artificial neural networks (ANNs), fuzzy logic, and genetic algorithms (GA), were combined to decipher the key minerals and predict the optimal combination of salts for hardy kiwi (
)
micropropagation. A five-factor experimental design of 33 salt treatments was defined using DOE. Later, the effect of the ionic variations generated by these five factors on three morpho-physiological growth responses - shoot number (SN), shoot length (SL), and leaves area (LA) - and on three quality responses - shoots quality (SQ), basal callus (BC), and hyperhydricity (H) - were modeled and analyzed simultaneously. Neurofuzzy logic models demonstrated that just 11 ions (five macronutrients (N, K, P, Mg, and S) and six micronutrients (Cl, Fe, B, Mo, Na, and I)) out of the 18 tested explained the results obtained. The rules "IF - THEN" allow for easy deduction of the concentration range of each ion that causes a positive effect on growth responses and guarantees healthy shoots. Secondly, using a combination of ANNs-GA, a new optimized medium was designed and the desired values for each response parameter were accurately predicted. Finally, the experimental validation of the model showed that the optimized medium significantly promotes SQ and reduces BC and H compared to standard media generally used in plant tissue culture. This study demonstrated the suitability of computer-based tools for improving plant
micropropagation: (i) DOE to design more efficient experiments, saving time and cost; (ii) ANNs combined with fuzzy logic to understand the cause-effect of several factors on the response parameters; and (iii) ANNs-GA to predict new mineral media formulation, which improve growth response, avoiding morpho-physiological abnormalities. The lack of predictability on some response parameters can be due to other key media components, such as vitamins, PGRs, or organic compounds, particularly glycine, which could modulate the effect of the ions and needs further research for confirmation.
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