Integrated constraints on explosive eruption intensification at Santiaguito dome complex, Guatemala

Protracted volcanic eruptions may exhibit unanticipated intensifications in explosive behaviour and attendant hazards. Santiaguito dome complex, Guatemala, has been characterised by century-long effusion interspersed with frequent, small-to-moderate (<2 km high plumes) gas-and-ash explosions. During 2015–2016, explosions intensified generating hazardous ash-rich plumes (up to 7 km high) and pyroclastic flows. Here, we integrate petrological, geochemical and geophysical evidence to evaluate the causes of explosion intensification. Seismic and infrasound signals reveal progressively longer repose intervals between explosions and deeper fragmentation levels as the seismic energy of these events increased by up to four orders of magnitude. Evidence from geothermobarometry, bulk geochemistry and groundmass microlite textures reveal that the onset of large explosions was concordant with a relatively fast ascent of a deeper-sourced (∼17–24 km), higher temperature (∼960–1020 °C) and relatively volatile-rich magma compared to the previous erupted lavas, which stalled at ∼2 km depth and mingled with the left-over mush that resided beneath the pre-2015 lava dome. We interpret that purging driven by the injection of this deep-sourced magma disrupted the long-term activity, driving a transition from low energy shallow shear-driven fragmentation, to high energy deeper overpressure-driven fragmentation that excavated significant portions of the conduit and intensified local volcanic hazards. Our findings demonstrate the value of multi-parametric approaches for understanding volcanic processes and the triggers for enigmatic shifts in eruption style, with the detection of vicissitudes in both monitoring signals and petrological signatures of the eruptive products proving paramount.

Wallace, Paul A.; Lamb, Oliver D.; De Angelis, Silvio; Kendrick, Jackie E.; Hornby, Adrian J.; Díaz-Moreno, Alejandro; González, Pablo J.; von Aulock, Felix W.; Lamur, Anthony; Utley, James E.P.; Rietbrock, Andreas; Chigna, Gustavo; Lavallée, Yan

Earth and Planetary Science Letters 536: 116139 (2020)

Six new non-native ants (Formicidae) in the Canary Islands and their possible impacts

Biological invasions are one of the main causes of biodiversity loss, especially on oceanic islands. Ants are among the most damaging pests in the world. After systematic sampling of more than 1,000 localities in the Canary Islands, six new exotic ant species are reported for the first time: Pheidole bilimeki (Myrmicinae), Pheidole navigans (Myrmicinae), Strumigenys membranifera (Myrmicinae), Brachymyrmex cordemoyi (Formicinae), Tapinoma darioi (Dolichoderinae) and Technomyrmex pallipes (Dolichoderinae). Moreover, another two recently reported species have been genetically confirmed. Morphological and genetic data were analysed to confirm the identity of the new records. For each species, information regarding identification, distribution, global invasive records and possible impacts is given. The arrival of these species may endanger local biodiversity.

Hernández-Teixidor, David; Pérez-Delgado, Antonio José; Suárez, Daniel; Reyes-López, Joaquin

Journal of Applied Entomology 1-8 (2020)

Genetic Diversity of Local Peach (Prunus persica) Accessions from La Palma Island (Canary Islands, Spain)

Peach (Prunus persica) is an economically important temperate fruit crop due to its edible fruits. Due to the need to develop new varieties better adapted to climate change, it is of great interest to find germplasm adapted to warmer conditions, such as those found in the Canary Islands. Peach was an important crop during the last century in one of those islands (La Palma), but its cultivation has been abandoned in recent years. Currently, commercial production is relict and isolated trees are relegated to family orchards with little management. With the objective to characterize and prevent the loss of local varieties of this crop, peach trees were sampled along La Palma. A total of 89 local peach accessions were prospected and analyzed with 10 single-sequence repeat (SSR) loci, which permitted 28 different genotype profiles to be detected. These genotypes were compared to 95 Spanish peach landraces conserved in an ex situ collection, and 26 additional samples from eight different countries. Results showed that the peach genetic diversity found in La Palma was low. In addition, a relation between La Palma samples and other Spanish peaches was observed, which could indicate the arrival of genetic material from the Iberian Peninsula and subsequent intercrossing and local selection of the genotypes more adapted to the subtropical climate of the island. The population structure reflects a grouping of the samples based on fruit type and geographic origin.

Pérez, Verónica; Larrañaga, Nerea; Abdallah, Donia; Wünsch, Ana; Hormaza Urroz, José Ignacio

Agronomy 10: 457 (2020)

Synthetic Approaches to Phosphasugars (2-oxo-1,2-oxaphosphacyclanes) Using the Anomeric Alkoxyl Radical β-Fragmentation Reaction as the Key Step

The anomeric alkoxyl radical β-fragmentation (ARF) of carbohydrates possessing an electron-withdrawing group (EWG) at C2, promoted by PhI(OAc)2/I2, gives rise to an acyclic iodide through which a pentavalent atom of phosphorus can be introduced via the Arbuzov reaction. After selective hydrolysis and subsequent cyclization, the phosphonate or phosphinate intermediates can be converted into 2-deoxy-1-phosphahexopyranose and 2-deoxy-1-phosphapentopyranose sugars. The ARF of carbohydrates with an electron-donor group (EDG) at C2 proceeds by a radical-polar crossover mechanism, and the cyclization occurs by nucleophilic attack of a conveniently positioned phosphonate or phosphinate group to the transient oxocarbenium ion. This alternative methodology leads to 5-phosphasugars with a 4-deoxy-5-phosphapentopyranose framework. The structure and conformation of the 2-oxo-1,2-oxaphosphinane and 2-oxo-1,2-oxaphospholane ring systems in different carbohydrate models have been studied by NMR and X-ray crystallography.

Hernández-Guerra, Daniel; Kennedy, Alan R.; León, Elisa I.; Martín, Ángeles; Pérez-Martín, Inés; Rodríguez Morales, María S.; Suárez, Ernesto

Journal of Organic Chemistry 85 (7): 4861-4880 (2020)

Use of glycerol and propylene glycol as additives in heat-treated goat colostrum

This experiment aimed to evaluate the suitability of glycerol and propylene glycol to reduce microbial count and preserve immune properties in heat-treated goat colostrum. Colostrum samples from 11 goats were each divided into 9 aliquots. Different concentrations (2, 6, 10, and 14%; vol/vol) of either glycerol or propylene glycol were added to the aliquots. Phosphate buffer solution was added to one aliquot, which was set as the control (CG). After the respective additions, all colostrum samples were heat treated at 56°C for 1 h. After cooling, aerobic mesophilic bacteria were cultured. The samples were frozen until free fatty acid, IgG, IgA, and IgM concentrations and chitotriosidase activity were measured. No differences were found in aerobic mesophilic bacteria counts between either 10 or 14% glycerol and propylene glycol additives. These additions reduced bacterial count to a greater extent than CG, and 2 or 6% additions. Colostrum IgG concentration was not affected by either of the additives or their concentrations. The propylene glycol additive reduced IgA and IgM concentrations and chitotriosidase activity, compared with CG. Conversely, glycerol did not affect any of the studied immune variables. In conclusion, glycerol addition to goat colostrum before heat treatment is suitable to enhance bacterial reduction, whereas colostrum immune properties were not affected.

Morales-delaNuez, Antonio; Hernández-Castellano, Lorenzo E.; Moreno-Indias, Isabel; Sánchez-Macías, Davinia; Argüello, Anastasio; Castro, Noemí

Journal of Dairy Science 103(3): 2756-2761 (2020)

Somatic cells: A potential tool to accelerate low-fat goat cheese ripening

Demand for healthy products has increased interest in low-fat caprine cheeses. These are characterised by higher hardness, cohesiveness and masticability, and lower odour and flavour intensities, than full-fat cheeses, which has led to evaluation of alternative manufacturing methods to improve sensory characteristics. Addition of milk somatic cells was used as a potential tool to improve the quality of fresh low-fat caprine cheese made with either raw or pasteurised milk. Proteolysis of α-CN, α-CN, and para-κ-CN was increased in low-fat cheeses made with raw milk when somatic cells were added. In contrast, reduced proteolysis was observed in low-fat cheeses made from pasteurised milk, except for that of β-CN, which was increased. Moreover, the addition of somatic cells increased the rate of lipolysis in low-fat pasteurised cheese. These changes in the rates of proteolysis and lipolysis could improve softness and flavour of low-fat cheeses.

Sánchez-Macías, Davinia; Hernández-Castellano, Lorenzo E.; Morales-delaNuez, Antonio; Herrera-Chávez, B.; Argüello, Anastasio; Castro, Noemí

International Dairy Journal 102: 104598 (2020)

Composition and biocidal properties of essential oil from pre-domesticated Spanish Satureja Montana

The aim of this study was to develop a chemically stable plant following a pre-domestication process and the valorization of its essential oil for the production of biopesticides. This study was conducted during four growing seasons to give a pre-domesticated population (SAMO-0). The resulting pre-domesticated population increased the hydrodistilled oil yield (average 0.45%) and maintained a stable yield of dry material (44.5%). The plant material was submitted to pilot plant scale steam distillation under three pressures (0.5, 1.0 and 1.5 bar) with lower yield (average 0.15%). The essential oil showed a carvacrol / p-cymene chemotype. The pre-domestication process increased β-myrcene, α- and γ-terpinene, p-cymene, thymol and β-bisabolene; and decreased α-thujene and carvacrol. The steam distillation increased the oil content in α-thujene, α-pinene, α-terpinene, p-cymene and trans-caryophyllene, and decreased borneol, thymoquinone thymol and β-bisabolene. Pressure increased α-terpinene, thymol and carvacrol Additionally, the study of the biocidal effects (against the insect pests Spodoptera littoralis, Myzus persicae and Leptinotarsa decemlineata and the phytopathogenic nematode Meloydogine javanica) of the EOs showed that overall, the most active oils were the hydrodistilled (to all insect species), followed by the steam distilled oils with higher carvacrol and thymol content (pressures of 1.5 and 1.0 bar). Carvacrol and thymol were responsible for the activity of these oils on M. persicae, and L. decemlineata but only partially on S. littoralis. The steam distilled oils showed strong nematicidal activity against M. javanica that could be partially explained by their content in active carvacrol and thymol.

Navarro-Rocha, Juliana; Andrés, María Fe; Díaz, Carmen E.; Burillo, Jesús; González-Coloma, Azucena

Industrial Crops and Products 145: 111958 (2020)

Unrest signals after 46 years of quiescence at Cumbre Vieja, La Palma, Canary Islands

Monogenetic eruptions are the most common volcanic activity in the world. However, unrest monitoring data are scarce due to the long intervening quiescence periods. This study analyzes unrest signals recorded in one of the largest monogenetic fields in the Canary Islands, Cumbre Vieja (La Palma). Two seismic swarms were registered in October 2017 and February 2018 with b-values of 1.6 ± 0.1 and 2.3 ± 0.2 respectively suggesting an intense magmatic fluids contribution, gas and/or magma. Both swarms were linked to changes in gas emissions. Increases in hydrogen concentration, and (R/R) up to 7.52 ± 0.05, were recorded before the first swarm, at the sampling point closest to where seismicity was located, indicating a deep gas input. After the second swarm, increases in (R/R) and thoron soil concentration were recorded at two locations. This dataset is compatible with a stalled magmatic intrusion at ca. 25 km depth, with an estimated volume between 5.5·10 km and 3·10 km.

Torres-González, Pedro A.; Luengo-Oroz, Natividad; Lamolda, Héctor; D'Alessandro, Walter; Albert, Helena; Iribarren, Ilazkiñe; Moure-García, David; Soler, Vicente

Journal of Volcanology and Geothermal Research 392: 106757 (2020)

Plant Growth Promotion Abilities of Phylogenetically Diverse Mesorhizobium Strains: Effect in the Root Colonization and Development of Tomato Seedlings

Mesorhizobium contains species widely known as nitrogen-fixing bacteria with legumes, but their ability to promote the growth of non-legumes has been poorly studied. Here, we analyzed the production of indole acetic acid (IAA), siderophores and the solubilization of phosphate and potassium in a collection of 24 strains belonging to different Mesorhizobium species. All these strains produce IAA, 46% solubilized potassium, 33% solubilize phosphate and 17% produce siderophores. The highest production of IAA was found in the strains Mesorhizobium ciceri CCANP14 and Mesorhizobium tamadayense CCANP122, which were also able to solubilize potassium. Moreover, the strain CCANP14 showed the maximum phosphate solubilization index, and the strain CCANP122 was able to produce siderophores. These two strains were able to produce cellulases and cellulose and to originate biofilms in abiotic surfaces and tomato root surface. Tomato seedlings responded positively to the inoculation with these two strains, showing significantly higher plant growth traits than uninoculated seedlings. This is the first report about the potential of different Mesorhizobium species to promote the growth of a vegetable. Considering their use as safe for humans, animals and plants, they are an environmentally friendly alternative to chemical fertilizers for non-legume crops in the framework of sustainable agriculture.

Menéndez, Esther; Pérez-Yépez, Juan; Hernández, Mercedes; Rodríguez-Pérez, Ana; Velázquez, Encarna; León-Barrios, Milagros

Microorganism 8(3): 412 (2020)

Climate drives community-wide divergence within species over a limited spatial scale: evidence from an oceanic island

Geographic isolation substantially contributes to species endemism on oceanic islands when speciation involves the colonisation of a new island. However, less is understood about the drivers of speciation within islands. What is lacking is a general understanding of the geographic scale of gene flow limitation within islands, and thus the spatial scale and drivers of geographical speciation within insular contexts. Using a community of beetle species, we show that when dispersal ability and climate tolerance are restricted, microclimatic variation over distances of only a few kilometres can maintain strong geographic isolation extending back several millions of years. Further to this, we demonstrate congruent diversification with gene flow across species, mediated by Quaternary climate oscillations that have facilitated a dynamic of isolation and secondary contact. The unprecedented scale of parallel species responses to a common environmental driver for evolutionary change has profound consequences for understanding past and future species responses to climate variation.

Salces-Castellano, Antonia; Patiño, Jairo; Alvarez, Nadir; Andújar, Carmelo; Arribas, Paula; Braojos-Ruiz, Juan José; del Arco-Aguilar, Marcelino; García-Olivares, Víctor; Karger, Dirk N.; López, Heriberto; Manolopoulou, Ioanna; Oromí, Pedro; Pérez-Delgado, Antonio J.; Peterman, William E.; Rijsdijk, Kenneth F.; Emerson, Brent C.

Ecology Letters 23(2): 305-315 (2020)