Baccharis Salicifolia Research Articles

NaCl Modifies Biochemical Traits in Bacterial Endophytes Isolated from Halophytes: Towards Salinity Stress Mitigation Using Consortia.

Bacterial endophytes (120) were isolated from six halophytes (Distichlis spicata, Cynodon dactylon, Eragrostis obtusiflora, Suaeda torreyana, Kochia scoparia, and Baccharis salicifolia). These halophiles were molecularly identified and characterized with or without NaCl conditions. Characterization was based on tests such as indole acetic acid (IAA), exopolysaccharides (EPS), and siderophores (SID) production; solubilization of phosphate (P), potassium (K), zinc (Zn), and manganese (Mn); mineralization of phytate; enzymatic activity (acid and alkaline phosphatase, phytases, xylanases, and chitinases) and the mineralization/solubilization mechanisms involved (organic acids and sugars). Moreover, compatibility among bacteria was assessed. Eleven halophiles were characterized as highly tolerant to NaCl (2.5 M). The bacteria isolated were all different from each other. Two belonged to Bacillus velezensis and one to B. pumilus while the rest of bacteria were identified up to the genus level as belonging to Bacillus, Halobacillus, Halomonas, Pseudomonas, Nesterenkonia, and three strains of Oceanobacillus. The biochemical responses of nutrient solubilization and enzymatic activity were different between bacteria and were influenced by the presence of NaCl. Organic acids were involved in P mineralization and nutrient solubilization. Tartaric acid was common in the solubilization of P, Zn, and K. Maleic and vanillic acid were only detected in Zn and K solubilization, respectively. Furthermore, sugars appeared to be involved in the solubilization of nutrients; fructose was detected in the solubilization tests. Therefore, these biochemical bacterial characteristics should be corroborated in vivo and tested as a consortium to mitigate saline stress in glycophytes under a global climate change scheme that threatens to exacerbate soil salinity.

Influence of Baccharis salicifolia Extract on Iron Oxide Nanoparticles in MCM-41@IONP and Its Application in Room-Temperature-Fabricated Metal–Insulator–Semiconductor Diodes

This work presents the green synthesis of iron oxide nanoparticles (IONPs) using Baccharis salicifolia extract and their incorporation in mesoporous silica MCM-41, obtaining an MCM-41@IONP composite. The MCM-41@IONP composite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nitrogen adsorption and desorption, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The use of the natural reducing agent Baccharis salicifolia resulted in nanoparticles with an average size of 31 nm. Furthermore, we showcase the application of the MCM-41@IONP nanocomposite in a metal–insulator–semiconductor (MIS) diode, which was fabricated at room temperature. The current–voltage and capacitance–voltage curves of the MIS diode were carefully measured and subjected to detailed analysis. The results demonstrate the potential utility of MCM-41@IONP nanocomposite-based MIS diodes, suggesting their applicability in the design of biosensors or as discrete components in electronic devices.

Evaluating pole cutting survival and growth for riparian forest restoration during invasion by polyphagous shot hole borer

The investment to restore riparian systems necessitates employing data‐driven planning, implementation, and management. To evaluate the demography/growth of riparian plants established vegetatively, we measured 3 years of survival and biometrics for five tree/shrub species experimentally planted as pole cuttings within a large restoration program in a Mediterranean‐climate riparian system. During the experiment, a recently introduced ambrosia beetle, Euwallacea whitfordiodendrus (polyphagous shot hole borer), colonized pole cuttings, providing an opportunity to evaluate beetle establishment rates among species. Pole cutting survival varied significantly among species and reflected their relative ability to propagate vegetatively. Baccharis salicifolia had over 90% survival, while Salix lasiolepis and S. laevigata had intermediate, and Populus trichocarpa and P. fremontii had low survival. Canopy growth reflected species life histories. The small tree/shrub, S. lasiolepis, had robust early growth, while slower growing, larger tree species (S. laevigata, P. trichocarpa, and P. fremontii) filled in canopy later. Only S. lasiolepis was colonized by E. whitfordiodendrus during the second year and had the greatest infestation rates in all years. All species except B. salicifolia were infested by the third year. Beetles tended to colonize larger trees. Our observed survival and growth trends can serve as a guide for estimating planting density and vegetation structural development over time, and to inform adaptive management of riparian species of Mediterranean‐climate and other arid‐land systems. Ecosystem stressors, such as invasive insects and their impacts to plant growth, must be considered during restoration as introductions are anticipated to continue with increased severity with climate change.

First U.S. Records of the Mistletoe-Associated Micrutalis discalis (Walker) (Hemiptera: Membracidae), Description of the Male, and Redescription of the Female

The treehopper Micrutalis discalis (Walker), subfamily Smiliinae, tribe Micrutalini, was described in 1858 from Veracruz, Mexico. We report the first U.S. records from five counties in Arizona, describe the male and fifth instar for the first time, and redescribe the female. We collected nymphs and adults from desert mistletoe (Phoradendron californicum Nutt.; Viscaceae), which was hemiparasitic on trees and shrubs of the Fabaceae: yellow paloverde (Parkinsonia microphylla Torr.), velvet mesquite (Prosopis velutina Wooten), and catclaw acacia (Senegalia greggii [A. Gray] Britton and Rose). Our observations of nymphs in both late March to early May and in August suggest that M. discalis is bivoltine. We collected another adult, perhaps incidental, from the mistletoe Phoradendron villosum (Nutt.) Nutt. on Sonoran scrub oak (Quercus turbinella Greene; Fagaceae) and consider an adult from mule-fat (Baccharis salicifolia [Ruiz. and Pav.] Pers.; Asteraceae) an incidental occurrence.

Hydrologic and geomorphic effects on riparian plant species occurrence and encroachment: Remote sensing of 360 km of the Colorado River in Grand Canyon

AbstractA common impact on riparian ecosystem function following river regulation is the expansion and encroachment of riparian plant species in the active river channels and floodplain, which reduces flow of water and suspended sediment between the river, riparian area and upland ecosystems. We characterised riparian plant species occurrence and quantified encroachment within the dam‐regulated Colorado River in Grand Canyon, Arizona, USA. We mapped 10 riparian species with high‐resolution multispectral imagery and examined effects of river hydrology and geomorphology on the spatial distribution of plant species and open sand. Analysis spanned an image time series from 2002 to 2009 to 2013, a period when plant species and sand were spatially dynamic and operations of Glen Canyon Dam included daily hydro‐peaking and small episodic controlled flood releases. Plant species occurrence and encroachment rates varied with hydrology, geomorphology and local species pool. Encroachment was greatest on surfaces frequently inundated by hydro‐peaking. Seep willow (Baccharis spp.), tamarisk (Tamarix spp.) and arrowweed (Pluchea sericea) were the primary encroaching woody species. Common reed (Phragmites australis) and horsetail (Equisetum xferrissii) were the primary encroaching herbaceous species. Encroachment composition from 2002 to 2009 was similar to the entire riparian landscape, whereas encroachment from 2009 to 2013 primarily consisted of seep willow and early colonising herbaceous species. Emergence of seep willow and arrowweed after burial by sand deposited by controlled floods indicated that those species were resilient to this form of disturbance. Describing patterns of species encroachment is an important step towards designing flow regimes that favour riparian species and ecosystem functions valued by stakeholders.

Phytotoxic activity of aqueous extracts of ruderal plants and its potential application to tomato crop

Background: The application of synthetic pesticides to the tomato crop ( Solanum lycopersicum -Solanaceae-) increases fruit production, but also carries risks for the environment, human and animal health.
 Hypothesis: local ruderal plant extracts could be an alternative for weed control, with potential applications in agroecology and organic agriculture.
 Methods: Organic and aqueous extracts (1 and 10% w/v) were prepared with the fresh (FAE) and dry (DAE) aerial parts of five ruderal species from Tlaxcala, Mexico: Argemone mexicana L. (Papaveraceae), Baccharis salicifolia Pers. (Asteraceae), Lepidium virginicum L. (Brassicaceae), Leucena leucocephala S. Zárate (Fabaceae) and Reseda luteola L. (Resedaceae). Their phytotoxic activity was evaluated in vitro with the seeds of three model plants (amaranth, lettuce, and tomato).
 Results: DAE of B. salicifolia and L. virginicum (1 % w/v) showed the highest potential as natural herbicides. These inhibited 100 % seed germination and radicle elongation in the three model plants but did not affect the growth of tomato seedlings of 8 and 12 weeks in greenhouse conditions. Both extracts analyzed by HPLC-ESI-QTOF-MS showed two major peaks. Bacharis salicifolia with m/z 432.9 and 725.4. Lepidium virginicum with m/z 532.9 and 527.1.
 Conclusions:DAE of local ruderal plants B. salicifolia and L. virginicum (1 % w/v) are potential natural herbicides, without harmful effects on tomato cultivated seedlings, awaiting the precise identification of their active compounds.

Synthesis and characterization of chemically activated carbon from Passiflora ligularis, Inga feuilleei and native plants of South America

Activated carbons (ACs) play a key role in applications such as treatment and purification of water and polluting gases and new application as supercapacitators.The present work is related to the synthesis of new green adsorbents from the seeds and shells of Inga feuilleei and Passiflora ligularis, wood of Kageneckia lanceolata, Baccharis salicifolia and Baccharis latifolia. Both the porous texture and adsorption capacity of the new activated carbon were studied. The ACs were synthesized by conventional chemical activation using phosphoric acid.Results indicated that each synthesized AC presented a microporous/mesoporous texture and the three best iodine numbers obtained were 978.55, 905.8 and 865.9 mg.g−1. These results were achieved for the ACs from Passiflora ligularis, Kageneckia lanceolata and Baccharis salicifolia, respectively.The optimal conditions to achieve the best iodine number (978.55 mg.g−1) and BET surface area (1244.62 m2. g−1) were found for the Passiflora ligularis, at carbonization temperature of 500 °C, for 120 min, impregnation ratio of 1:4 (raw material/H3PO4) and concentration of activating agent H3PO4 of 60 %.The FT-IR spectroscopy method was used to characterize the functional groups present on the surface of the AC and the raw materials. On the other hand, the TGA analysis was carried out to show the AC mass loss as the temperature increased. Both analyzes showed that the activation was fully achieved under the optimal conditions described above. The results confirmed that the shell of Passiflora ligularis is a promising material as a highly adsorptive, low cost and renewable adsorbent.

Sexual and genotypic variation in terpene quantitative and qualitative profiles in the dioecious shrub Baccharis salicifolia

Terpenoids are secondary metabolites produced in most plant tissues and are often considered toxic or repellent to plant enemies. Previous work has typically reported on intra-specific variation in terpene profiles, but the effects of plant sex, an important axis of genetic variation, have been less studied for chemical defences in general, and terpenes in particular. In a prior study, we found strong genetic variation (but not sexual dimorphism) in terpene amounts in leaves of the dioecious shrub Baccharis salicifolia. Here we build on these findings and provide a more in-depth analysis of terpene chemistry on these same plants from an experiment consisting of a common garden with male (N = 19) and female (N = 20) genotypes sourced from a single population. Our goal in the present study was to investigate quantitative and qualitative differences in terpene profiles associated with plant sex and genotypic variation. For this, we quantified leaf mono- and sesquiterpene amount, richness, and diversity (quantitative profile), as well as the composition of compounds (qualitative profile). We found no evidence of sexual dimorphism in monoterpene or sesquiterpene profiles. We did, however, find significant genotypic variation in amount, diversity, and composition of monoterpenes, but no effects on sesquiterpenes. These findings indicated that genotypic variation in terpene profiles largely surpassed variation due to sexual dimorphism for the studied population of this species.

A new species of Scrobipalpula Povolný (Lepidoptera: Gelechiidae) associated with Baccharis salicifolia (Asteraceae) in the Atacama Desert of northern Chile

ABSTRACTMale and female adults of Scrobipalpula wilsoni sp. nov. are described and illustrated from the coastal valleys of the Atacama Desert of northern Chile, based on specimens reared from leaf tier larvae collected on the shrub Baccharis salicifolia (Ruiz & Pav.) Pers. (Asteraceae). The morphology of the male genitalia of S. wilsoni resembles that of S. transiens Povolný, 1987, endemic to central Chile; however, morphological details of the uncus, gnathos, valva, the paired process of the sacculus and the phallus enable separation of the two species. Pairwise distances of a DNA barcode sequence of S. wilsoni with congeneric species ranged from 7.4 to 9.2% (K2P).urn:lsid:zoobank.org:pub:28FFDB34-2BBF-4E99-B35A-8BD84DF33E96

Impacts of Tamarix (L.) Litter and Mycorrhizal Amendments on Baccharis salicifolia (Ruiz & Pav.) Pers. Competitiveness and Mycorrhizal Colonization

Tamarix spp. are ecological threats in the Southwest U.S.A. because they displace native vegetation, increase soil salinity, and negatively affect soil microbial communities. After Tamarix L. removal, legacy effects often necessitate restoration to improve ecosystem services of Tamarix-impacted communities. Commercial mycorrhizae fungal inoculation has been recommended to improve restoration success, although inoculation treatments are rarely tested on lesser-known facultative riparian species. Our study asked two questions: (1) Can a commercial mycorrhizal fungal inoculant increase native Baccharis salicifolia (Ruiz & Pav.) Pers. (mule-fat) performance against Tamarix chinensis Lour. (i.e., tamarisk) and is this influenced by tamarisk leaf litter? (2) Is mycorrhizal colonization of mule-fat roots influenced by tamarisk stem density and leaf litter? A greenhouse experiment was performed with mule-fat cuttings in soil collected from a tamarisk monoculture. Treatments were factorial combinations of tamarisk stem densities (0, 1, 2, 3, 4 stems pot−1) with or without mycorrhizal inoculation and tamarisk litter. There were five replications and two greenhouse runs. The total biomass of both species was determined and mule-fat arbuscular mycorrhizal colonization rates were determined via the magnified intersection method. Increasing tamarisk biomass negatively affected mule-fat biomass, but there were interactions with tamarisk biomass, litter and mycorrhizal inoculation, with litter and inoculation increasing mule-fat growth at high tamarisk biomass. Arbuscular mycorrhizal colonization was high in all treatments, yet at higher tamarisk stem densities, inoculation and litter improved colonization. Interestingly, litter did not negatively impact mule-fat as predicted. Moreover, litter and mycorrhizal inoculum interacted with tamarisk to improve mule-fat growth at higher tamarisk biomass, suggesting an opportunity to improve restoration success when in competition with tamarisk.

Chemical profile of the volatiles of Baccharis salicifolia (Asteraceae) and interaction with Macrodactylus nigripes (Coleoptera: Melolonthidae)

Plant products or substances mediate interactions among organisms from different trophic levels, including phytophagous insects. These interactions have been cited in a chemical-ecology context for species of Coleoptera Melolonthidae. However, there are no previous reports of these interactions among melolonthid beetles species distributed in Mexico and host plants. For the above, the interaction between adults of ‘rose chafer’ Macrodactylus nigripes Bates (Coleoptera:Melolonthidae) and ‘seep willow’ shrub Baccharis salicifolia (Ruíz and Pav.) Pers. (Asteraceae) was recorded and the leaves volatiles of seep willow that might be involved in the attraction of these insects were extracted and identified. The sequence of behavior patterns that conforms this interaction was described. Females of M. nigripes emerge from the soil and flight to the leaves of seep willow shrubs. Each female settled on leaf and they place their mandibles on the leaf margin and start moving them from right to left to obtain small leaf fragments to ingest. In addition, females exhibit a similar ‘calling’ behavior as well as the others species. Following the females, males emerge from the soil and repeat the females’ behavior, approaching them for mating. A list of the leaves volatiles of seep willow was generated by solid phase microextraction (SPME) and coupled gas chromatography – mass spectrometry (GC-MS), where the most abundant chemicals were α-pinene, trimethylindan and cyclohexylbenzene. These compounds have been previously reported in other plant species, including some species considered as host plants for Melolonthidae.

Assessing the feasibility of using a closed landfill for agricultural graze land.

Once landfills are closed and maintained according to the US Environmental Protection Agency's standards and regulations, they are potential sites for revitalization efforts, particularly via agricultural activities. This project was commissioned by the City of Tucson Environmental Services Department as part of an effort to explore ways to reuse one or more of the 16 landfills the department manages in the Tucson metropolitan area. The objective of this project was to assess the feasibility of using a closed landfill to support safe goat browsing. A site history and investigation was conducted at the Harrison Landfill in Tucson, Arizona, to characterize the soil quality and uptake of deleterious metals by the following plants observed at the landfill: Pennisetum ciliare (buffel grass), Baccharis sarothroides (desert broom), Salsola tragus L. (Russian thistle), Larrea tridentata (creosote), Tamarix ramosissima (salt cedar), and Atriplex canescens (fourwing saltbush). Site characterization data were combined with known goat browsing and plant consumption patterns to determine exposure risks. It was observed that soil concentrations of metals (Al, Ag, As, Be, Ba, Fe, Co, Cu, Cr, Cd, Fe, Mn, Ni, V, Se, Mo, Sn, Sb, Pb) did not exceed Arizona Department of Environmental Quality's soil remediation levels. Tamarix ramosissima, Baccharis salicifolia (willow baccharis), Pennisetum ciliare, Salsola tragus L., Baccharis sarothroides, Larrea tridentata, and Atriplex canescens contained metal concentrations that fell well within maximum tolerable levels. In general, this project determined that after soil and plant assessment, urban, arid landfills may be used effectively for economic development through agricultural grazing ventures.

Specificity of Plant-Plant Communication for Baccharis salicifolia Sexes but Not Genotypes

In order to identify the chemical mechanisms underlying sex-specificity in plant–plant communication, we used artificial emitters (right) to expose B. salicifolia to volatile compounds induced by U. macolai feeding (left) and compared the performance of U. macolai on the experimental plants. Of the seven compounds induced by U. macolai feeding (speaking), pinocarvone emission was ca. fivefold greater in female than in male plants. When plants were exposed to pinocarvone in isolation via artificial emitters (right), U. macolai performance was reduced, with aphids feeding on male and female plants affected equally (listening). These photographs illustrate the article “Specificity of plant–plant communication for Baccharis salicifolia sexes but not genotypes” by Xoaquín Moreira, Colleen S. Nell, Maria M. Meza-Lopez, Sergio Rasmann, and Kailen A. Mooney published in Ecology. https://doi.org/10.1002/ecy.2534

Specificity of plant-plant communication for Baccharis salicifolia sexes but not genotypes.

Plants are able to adjust their anti-herbivore defenses in response to the volatile organic compounds (VOCs) emitted by herbivore-damaged neighbors, and some of these changes increase resistance against subsequent herbivory. This phenomenon of plant-plant communication is thought to be widespread, but recent investigations have cautioned that it can be context dependent, including variation in the strength of communication based on the identity of plants and their associated herbivores. Here, we performed three greenhouse experiments using multiple male and female genotypes of the dioecious woody shrub Baccharis salicifolia and its specialist aphid Uroleucon macolai to test for specificity of plant-plant communication with respect to plant sex and genotype. Moreover, we evaluated plant sexual dimorphism and genotypic variation in VOC emissions (i.e., the "speaking" side of the interaction) and response of plants to VOC exposure (i.e., the "listening" side of the interaction) in order to identify the chemical mechanisms underlying such specificity. We did not find genotypic specificity of communication; emitter plants damaged by U.macolai significantly reduced subsequent U.macolai performance on receivers, but these effects were indistinguishable for communication within vs. among genotypes. In contrast, we found sex specificity of communication; male emitter plants reduced subsequent U.macolai performance on male and female receiver plants equally, while female emitter plants only did so for female receivers. We found sexual (but not genotypic) dimorphism in speaking but not listening; of the seven compounds induced by U.macolai feeding (speaking), pinocarvone was approximately fivefold greater in female than in male plants, while exposure of plants to pinocarvone emissions (listening) reduced U.macolai performance equally in both male and female plants. Together, our study demonstrates novel evidence for sexually dimorphic specificity of plant-plant communication and the chemical mechanism underlying this effect.

Allelopathyc potential of baccharis salicifolia against staphylococcus aureus

Allelopathyc potential of baccharis salicifolia against staphylococcus aureus

Relative effects of genetic variation sensu lato and sexual dimorphism on plant traits and associated arthropod communities.

Intraspecific plant trait variation can have cascading effects on plant-associated biotic communities. Sexual dimorphism is an important axis of genetic variation in dioecious plants, but the strength of such effects and the underlying mechanisms relative to genetic variation are unknown. We established a common garden with 39 genotypes of Baccharis salicifolia sampled from a single population that included male and female genotypes and measured plant traits and quantified associated arthropod communities. Genetic variation sensu lato (genotypic variation) had strong effects on most plant traits (flower number, relative growth rate, specific leaf area, percent water content, carbon-nitrogen ratio, monoterpene but not sesquiterpene concentrations) and on herbivore and predator density, and on arthropod community composition (relative abundance of 14 orders). In contrast, sexual dimorphism had weaker effects on only a few plant traits (flower number and relative growth rate), on predator density, and on arthropod community composition, but had no effect on herbivore density. Variation in flower number drove genetic variation sensu lato and sex dimorphism in predator density and arthropod community composition. There was unique genetic variation sensu lato in herbivore density (positively) associated with monoterpene concentration and in arthropod community composition associated with specific leaf area and carbon-nitrogen ratio. There was unique sexual dimorphism in arthropod community composition associated with plant relative growth rate. Together, these results demonstrate that genetic variation sensu lato and sexual dimorphism can shape plant-associated arthropod communities via both parallel and unique mechanisms, with greater overall effects of the former.

Traits underlying community consequences of plant intra-specific diversity.

A plant’s performance and interactions with other trophic levels are recorgnized to be contingent upon plant diversity and underlying associational dynamics, but far less is known about the plant traits driving such phenomena. We manipulated diversity in plant traits using pairs of plant and a substitutive design to elucidate the mechanisms underlying diversity effects operating at a fine spatial scale. Specifically, we measured the effects of diversity in sex (sexual monocultures vs. male and female genotypes together) and growth rate (growth rate monocultures vs. fast- and slow-growing genotypes together) on growth of the shrub Baccharis salicifolia and on above- and belowground consumers associated with this plant. We compared effects on associate abundance (# associates per plant) vs. density (# associates per kg plant biomass) to elucidate the mechanisms underlying diversity effects; effects on abundance but not density suggest diversity effects are mediated by resource abundance (i.e. plant biomass) alone, whereas effects on density suggest diversity effects are mediated by plant-based heterogeneity or quality. Sexual diversity increased root growth but reduced the density (but not abundance) of the dietary generalist aphid Aphis gossypii and its associated aphid-tending ants, suggesting sex mixtures were of lower quality to this herbivore (e.g. via reduced plant quality), and that this effect indirectly influenced ants. Sexual diversity had no effect on the abundance or density of parasitoids attacking A. gossypii, the dietary specialist aphid Uroleucon macolai, or mycorrhizae. In contrast, growth rate diversity did not influence plant growth or any associates except for the dietary specialist aphid U. macolai, which increased in both abundance and density at high diversity, suggesting growth rate mixtures were of higher quality to this herbivore. These results highlight that plant associational and diversity effects on consumers are contingent upon the source of plant trait variation, and that the nature of such dynamics may vary both within and among trophic levels.

Genetic divergence of a newly documented population of the cecidogenous micromoth Eugnosta azapaensis Vargas & Moreira (Lepidoptera: Tortricidae) in the Atacama Desert of northern Chile

Eugnosta azapaensis Vargas and Moreira, 2015 (Lepidoptera: Tortricidae) is a micromoth native to the Atacama Desert whose larvae induce fusiform galls in shoots of Baccharis salicifolia (Ruiz & Pav.) Pers. (Asteraceae). The presence of this cecidogenous tortricid was previously recorded only from the type locality, the Azapa Valley, Arica Province, northern Chile. However, fusiform galls on shoots of B. salicifolia were recently found in Chaca, another coastal valley of the Atacama Desert. The adults obtained from these galls were preliminarily identified as E. azapaensis based on morphology. Subsequently, to assess an additional source of evidence for the taxonomic identification of E. azapaensis in this new locality, sequences of the DNA barcode fragment of the cytochrome oxidase subunit I mitochondrial gene from the two localities were analyzed. Four haplotypes were detected, two restricted to Azapa and two restricted to Chaca. The genetic divergence (K2P) between haplotypes of each locality was 0.2–0.8%, while it was 1.1–1.4% between haplotypes of different localities, and 8.7–13.5% between the Chilean haplotypes and other species of Eugnosta Hübner, 1825. In addition, all the sequences of Azapa and Chaca were clustered in a well-supported group in a Maximum Likelihood (ML) analysis. Accordingly, divergence and ML analyses support the morphological identification of E. azapaensis in the Chaca Valley. Furthermore, although preliminary, the analyses suggest that the genetic variation of the populations of this insect could be geographically structured, a pattern that must be assessed in further studies.

Synchrotron based study of As mobility and speciation in tailings from a mining site in Mexico

Mine Tailings of “La Aurora”, a mining site located in central Mexico, display anomalous concentrations of As, Zn, Pb, Cu and Cd. However, data on their potential toxicity is not available. It is known that toxicity is related to elemental speciation. In this work, we evaluated the biogeochemical dynamics of As in terms of mobility and chemical nature. For this purpose, samples of soils, mine tailings, plants and water were collected. Synchrotron based techniques and chemical fractionation extractions were used to determine As speciation, potential mobility, and bioavailability. Our results showed that As is present in concentrations up to 12,672±34 and 326±10mgkg−1 in mine tailings and nearby soils, respectively. X-ray Absorption Spectroscopy (XAS) analysis demonstrated that As is present as AsV in a structure similar to that of kankite (FeAsO4·3.5H2O) and beudantite (PbFe3 (AsO4)(SO4)(OH)6). The presence of these mineral structures were confirmed by μ X-Ray Fluorescence and X-ray Absorption Near Edge Structure (μ-XRF/XANES). Arsenic was also detected in plant species growing in the tested soils. The highest As concentrations were determined in the roots of Baccharis salicifolia (up to 44mgkg−1). In a creek nearby the mine tailings, As levels of 163±15μgL−1 were quantified. In terms of phytoaccessibility and bioaccessibility, As levels can be considered toxic for both plants and humans. According to sequential extraction results, As is associated mainly with the crystalline Fe-Ox fraction.

Morfoanatomía e histoquímica de cuatro Asteraceae nativas del Bosque Chaqueño Serrano (Córdoba, Argentina)

El Bosque Chaqueño Serrano se caracteriza por un clima semiárido; las especies que habitan en él presentan una serie de modificaciones relacionadas principalmente al balance hídrico.En este hábitat la familia Asteraceae es una de las más numerosas, nucleando gran cantidad de especies con propiedades medicinales. Cuatro de ellas fueron estudiadas en el presente trabajo, ellasson: Austroeupatorium inulifolium, Baccharis salicifolia, Chromolaena hookeriana y Ophryosporus axilliflorus. Se indagó sobre los órganos vegetativos aéreos con el objetivo de comprender las estrategiasadaptativas que presentan en relación al ambiente en que viven, detectar estructuras productoras de principios activos e inferir los compuestos químicos que ellas producen. En las cuatro especiesestudiadas se observaron características consideradas xeromórficas, destacándose la presencia de tricomas, conductos y endodermis con banda de Caspary en los tallos. Además, resultaron positivaspara las pruebas de compuestos pécticos y lipídicos y B. salicifolia presentó taninos en la epidermis.Concluimos que las estructuras secretoras y los compuestos químicos encontrados estarían directamente relacionados con las propiedades medicinales de estas especies.