Insect communities in saline waters consist of realized but not fundamental niche specialists
Considering how organisms adapt to stress is essential if we are to anticipate biological responses to global change in ecosystems. Communities in stressful environments can potentially be assembled by specialists (i.e. species that only occur in a limited range of environmental conditions) and/or generalist species with wider environmental tolerances. We review the existing literature on the salinity tolerance of aquatic insects previously identified as saline specialists because they were exclusively found in saline habitats, and explore if these saline realized niche specialists are also specialists in their fundamental niches or on the contrary are fundamental niche generalist species confined to the highest salinities they can tolerate. The results suggest that species inhabiting saline waters are generalists in their fundamental niches, with a predominant pattern of high survival in freshwater low salinity conditions, where their fitness tends to be similar or even higher than in saline waters. Additionally, their performance in freshwater tends to be similar to related strictly freshwater species, so no apparent trade-off of generalization is shown. These results are discussed in the framework of the ecological and evolutionary processes driving community assembly across the osmotic stress gradient, and their potential implications for predicting impacts from saline dilution and freshwater salinization. This article is part of the themed issue ‘Salt in freshwaters: causes, ecological consequences and future prospects’.
Arribas, Paula; Gutiérrez-Cánovas, Cayetano; Botella-Cruz, María; Cañedo-Argüelles, Miguel; Carbonell, José Antonio; Millán, Andrés; Pallarés, Susana; Velasco, Josefa; Sánchez-Fernández, David
Menadione Sodium Bisulphite (MSB): beyond seed-soaking. Root pretreatment with MSB primes salt stress tolerance in tomato plants
Salinity and drought are considered significant abiotic plant stressors with major impact on plant development that causes serious agricultural yield losses. Amongst the strategies to face this problem, the use of compounds capable of inducing abiotic stress tolerance is still little explored. Menadione sodium bisulphite (MSB), a water-soluble vitamin K3 derivative, was previously shown to prime salt stress tolerance when Arabidopsis seeds were pre-soaked with this compound. However, this method has some technical problems regarding seed storage and longevity. In order to overcome these handicaps, we assessed the effect of supplying MSB to roots to prime the response to salinity stress, analysing the effect of two NaCl concentrations (100 and 150¿mM). We selected tomato plants, the most economically important horticultural crop, as our biological model. In this new system, MSB primes salt tolerance in tomato plants by improving net photosynthesis, regulating stomatal aperture and maintaining water balance. Furthermore, MSB induces a faster proline accumulation and ion homeostasis by up-regulating several ion transporter genes, and increases antioxidant activity. As a result, a clear positive effect on plant growth was observed, indicated by the relative growth rate (RGR), These findings again highlight the potential usefulness of MSB as a priming agent for enhancing crop tolerance in the field under adverse environmental conditions.
Jiménez-Arias, David; Garcia Machado, Francisco Javier; Morales Sierra, Sarai; Suárez, Emma; Pérez, José A.; Luis, Juan C.; Garrido-Orduña, Cristina; Herrera, Antonio J. ; Valdés, Francisco; Sandalio, Luisa M.; Borges, Andrés A.
Synthesis of Chiral Polyhydroxylated Benzimidazoles by a Tandem Radical Fragmentation/Cyclization Reaction: A Straight Avenue to Fused Aromatic-Carbohydrate Hybrids
The synthesis of benzimidazole-fused iminosugars through a tandem β-fragmentation-intramolecular cyclization reaction is described. The use of the benzimidazole ring as the internal nucleophile and the use of phenyliodosophthalate (PhI(Phth)), a new metal-free and low toxic hypervalent iodine reagent, are the most remarkable novelties of this synthetic strategy. With this approach, we have demonstrated the usefulness of the fragmentation of anomeric alkoxyl radicals promoted by the PhI(Phth)/I system for the preparation of new compounds with potential interest for both medicinal and synthetic chemists.
André-Joyaux, Emy; Santana, Andrés G.; González Martín, Concepción C.
Babies, Bathwater, and Straw Men? Not Quite: A Response to Meiri et al.
Emerson, Brent C.; Patiño, Jairo
Metal- and Oxidant-Free Photoinduced Aromatic Trifluoromethylation Performed in Aerated Gel Media: Determining the Effects on Yield and Selectivity
In this work we have investigated the potential benefits of using supramolecular gel networks as reaction media to carry out air-sensitive metal-free light-induced trifluoromethylation of six-membered (hetero)arenes under aerobic conditions. This reaction was performed at room temperature (RT) using sodium triflinate (CF₃SO₂Na, Langlois' reagent) as a source of radicals and diacetyl as electron donor. The effects of confinement in gel media, concentration of reactants, and type of light source on yield and product distribution were evaluated and compared to the results obtained in homogeneous solution. Four different low molecular weight (LMW) gelators were employed in this study. The results confirmed the blocking effect of the gel medium against reaction quenching by external oxygen, as well as a certain control on the kinetics and selectivity.
Abramov, Alex; Vernickel, Hendrick; Saldías, César; Díaz Díaz, David
Benzofurans, benzoic acid derivatives, diterpenes and pyrrolizidine alkaloids from Peruvian Senecio
Sixteen compounds incluiding four benzofurans (1–4), three benzoic acid derivatives (6–8), one eremophilane (9), four diterpenes (10–13) and four pyrrolizidine alkaloids (14–17) were isolated from Senecio subcandidus, S. klugii and S. ayapatensis from Perú. Compounds 1–4 and 6–9 have not been previously reported as natural products. Their molecular structures were determined by NMR spectroscopic analysis, comparison with published NMR data and chemical transformations. The X-ray analysis of acetylated derivative 5 and compound 7 were also performed. Their insecticidal and antifungal activities were tested.
Ruiz-Vasquez, Liliana; Ruiz-Mesía, Lastenia; Renia, Matías; López-Rodríguez, Matías; González-Platas, Javier; Giménez, Cristina; Cabrera, Raimundo; González-Coloma, Azucena
Chemical constituents derived from the canaries marine sponge Myxilla sp.
Stigmasterols, ceramides, including ceramide-1-phosphates and pyrimidines were identified in an ethanol extract of the marine sponge Myxilla sp. The compounds were identified by MS and 1D- and 2D-NMR techniques. A simple method based on an ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry was developed to investigate the production of the aforementioned ceramides. This is the first report on ceramide-1-phosphates from a marine sponge.
Ferriol Bunyola, Pere; Toledo Marante, Francisco J.; León, Francisco; Brouard, Ignacio; Guedes Alonso, Guedes; Santana Rodríguez, José J.
On the verge of below-ground speciation: A new species complex of microendemic endogean carabid beetles, Typhlocharis Dieck, 1869 (Coleoptera: Carabidae: Anillini), from south-west Iberian Peninsula
A new species complex of genus Typhlocharis Dieck, 1869 (Coleoptera: Carabidae: Trechinae: Anillini: Typhlocharina) is described. Six populations from southern Badajoz (Spain), referred as the >coenobita species complex>, are the first documented case of an expected situation within Typhlocharina and potentially other lineages of endogean ground beetles: the presence of closely related allopatric populations within a reduced geographical range that, despite certain genetic isolation, show a gradient of morphological differences that challenge taxonomic assignment. Previous phylogenies of Typhlocharina recovered these populations as a monophyletic lineage, represented by three potential new species in need of further examination to validate their status. Here, we test the congruence of this taxonomic hypothesis through direct observation, statistical analyses applied to morphological characters and analysis of COI sequences. Such integrative approach, revealed as a powerful tool to solve situations where phenotypic differences are very subtle, is used for the first time to discriminate Anillini species. The results are coherent with the three species hypothesis, formally described as T. coenobita sp.n., T. eremita sp.n. and T. anachoreta sp.n. The implications of the internal variability within this species complex to the systematics of Typhlocharina and their affinities to other Typhlocharis species are discussed. The entity of T. eremita sp.n. as new species is well established within the standards of the genus. However, the populations of T. coenobita sp.n. show high variability and their relationship with T. anachoreta sp.n. is in the verge of what can be considered species-level differentiation, suggestive of an incipient speciation process. The proposed species boundaries maximize the consistence among the different sources of evidence. The intraspecific variability within T. coenobita sp.n. is properly described, contributing to elucidate the ongoing differentiation processes within this endogean lineage. Finally, an identification key for the coenobita species complex is provided.
Pérez-González, Sergio; Andújar, Carmelo; Lantero, Esther; Zaballos, Juan P.
Synthesis and Utility of 2,2-Dimethyl-2 H-pyrans: Dienes for Sequential Diels-Alder/Retro-Diels-Alder Reactions
The practical use of 2,2-dimethyl-2H-pyrans as electron-rich dienes in sequential Diels−Alder/retro-Diels−Alder (DA/rDA) domino processes to generate aromatic platforms has been demonstrated. Different polysubstituted alkyl 2-naphthoates have been synthesized by the DA/rDA reaction of benzynes and 2,2-dimethyl-2H-pyrans. The use of other activated alkynes allows the access of substituted alkyl benzoate derivatives.
Tejedor, David; Díaz-Díaz, Abián; Diana-Rivero, Raquel; Delgado-Hernández, Samuel; García-Tellado, Fernando
On the sensitivity of alginate rheology to composition
The linear response of alginate-phenyl boronic acid (Alg-PBA) esters shows a universal, composition-independent viscoelastic fluid-like behaviour. Reversible association of alginates governs their rheology at all compositions (viz. at all alginate concentrations and solution pH). However, their high strain behaviour is very sensitive to composition. Tuning composition affords liquids that neck to form filaments capable of being drawn to large elongations without failure. We interpret our data by invoking strain-dependent association and dissociation rates for the alginates. High association rates at high strain result in materials with viscoelastic liquid like behaviour.
Suresh, Karthika; Häring, Marleen; Kumaraswamy, Guruswamy; Díaz Díaz, David