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Transposable elements are one of the major contributors to genome-size differences in metazoans. Despite this, relatively little is known about the evolutionary patterns of element expansions and the element families involved. Here we report a broad genomic sampling within the genus Hydra, a freshwater cnidarian at the focal point of diverse research in regeneration, symbiosis, biogeography, and aging. We find that the genome of Hydra is the result of an expansion event involving long interspersed nuclear elements and in particular a single family of the chicken repeat 1 (CR1) class. This expansion is unique to a subgroup of the genus Hydra, the brown hydras, and is absent in the green hydra, which has a repeat landscape similar to that of other cnidarians. These features of the genome make Hydra attractive for studies of transposon-driven genome expansions and speciation.
Assuntos
Elementos de DNA Transponíveis , Evolução Molecular , Hydra/genética , Animais , Tamanho do Genoma , Hydra/classificação , FilogeniaRESUMO
OBJECTIVES: We examine the prevalence and sociodemographic risk factors of skeletal indicators of stress in forensic samples of undocumented migrants from Mexico and Central America. MATERIALS AND METHODS: Cranial and dental remains of 319 migrants recovered in the Arizona and Texas borderlands were assessed for porotic hyperostosis (PH), cribra orbitalia (CO), and linear enamel hypoplasias (LEH). Logistic regression models for each condition were estimated to test for associations with biological sex, age, recovery location, and whether individuals were identified. Additional models estimated for a subsample of identified migrants included region of origin, residential context, and community indigeneity. RESULTS: The full sample shows moderate crude prevalence of CO (9.6%) and LEH (34.1%), and a high prevalence of PH (49.6%). Significantly higher odds of PH are associated with being male (2.16 times higher), unidentified (1.89 times higher), and recovered in Arizona (3.76 times higher). Among identified migrants, we fail to find associations significant at the p < 0.05 level between skeletal stress and all sociodemographic variables except age. DISCUSSION: The factors associated with PH may be related to influences on decisions to migrate and diversity among migrant sending regions. The skeletal evidence for early life stress is generally consistent with common public health concerns among impoverished communities in the region. The lesions themselves are viewed as embodied risk of physiological disturbance when resource access is structured by higher-level social, economic, and political forces. Forensic anthropologists would benefit from increased sensitivity to embodied structural violence among the vulnerable individuals and communities they serve.
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Migrantes , América Central/epidemiologia , Humanos , Masculino , México/epidemiologia , Crânio , ViolênciaRESUMO
Senescence, the increase in mortality and decline in fertility with age after maturity, was thought to be inevitable for all multicellular species capable of repeated breeding. Recent theoretical advances and compilations of data suggest that mortality and fertility trajectories can go up or down, or remain constant with age, but the data are scanty and problematic. Here, we present compelling evidence for constant age-specific death and reproduction rates in Hydra, a basal metazoan, in a set of experiments comprising more than 3.9 million days of observations of individual Hydra. Our data show that 2,256 Hydra from two closely related species in two laboratories in 12 cohorts, with cohort age ranging from 0 to more than 41 y, have extremely low, constant rates of mortality. Fertility rates for Hydra did not systematically decline with advancing age. This falsifies the universality of the theories of the evolution of aging that posit that all species deteriorate with age after maturity. The nonsenescent life history of Hydra implies levels of maintenance and repair that are sufficient to prevent the accumulation of damage for at least decades after maturity, far longer than the short life expectancy of Hydra in the wild. A high proportion of stem cells, constant and rapid cell turnover, few cell types, a simple body plan, and the fact that the germ line is not segregated from the soma are characteristics of Hydra that may make nonsenescence feasible. Nonsenescence may be optimal because lifetime reproduction may be enhanced more by extending adult life spans than by increasing daily fertility.
Assuntos
Hydra/fisiologia , Animais , Evolução Biológica , Fertilidade , Expectativa de VidaRESUMO
Increased border enforcement efforts have redistributed unauthorized Mexican migration to the United States (US) away from traditional points of crossing, such as San Diego and El Paso, and into more remote areas along the US-Mexico border, including southern Arizona. Yet relatively little quantitative scholarly work exists examining Mexican migrants' crossing, apprehension, and repatriation experiences in southern Arizona. We contend that if scholars truly want to understand the experiences of unauthorized migrants in transit, such migrants should be interviewed either at the border after being removed from the US, or during their trajectories across the border, or both. This paper provides a methodological overview of the Migrant Border Crossing Study (MBCS), a unique data source on Mexican migrants who attempted an unauthorized crossing along the Sonora-Arizona border, were apprehended, and repatriated to Nogales, Sonora in 2007-09. We also discuss substantive and theoretical contributions of the MBCS.
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Emigração e Imigração/estatística & dados numéricos , Emigração e Imigração/tendências , Migrantes/psicologia , Migrantes/estatística & dados numéricos , Adulto , Arizona , Feminino , Humanos , Masculino , México , Pessoa de Meia-IdadeRESUMO
The freshwater cnidarian Hydra was first described in 1702 and has been the object of study for 300 years. Experimental studies of Hydra between 1736 and 1744 culminated in the discovery of asexual reproduction of an animal by budding, the first description of regeneration in an animal, and successful transplantation of tissue between animals. Today, Hydra is an important model for studies of axial patterning, stem cell biology and regeneration. Here we report the genome of Hydra magnipapillata and compare it to the genomes of the anthozoan Nematostella vectensis and other animals. The Hydra genome has been shaped by bursts of transposable element expansion, horizontal gene transfer, trans-splicing, and simplification of gene structure and gene content that parallel simplification of the Hydra life cycle. We also report the sequence of the genome of a novel bacterium stably associated with H. magnipapillata. Comparisons of the Hydra genome to the genomes of other animals shed light on the evolution of epithelia, contractile tissues, developmentally regulated transcription factors, the Spemann-Mangold organizer, pluripotency genes and the neuromuscular junction.
Assuntos
Genoma/genética , Hydra/genética , Animais , Antozoários/genética , Comamonadaceae/genética , Elementos de DNA Transponíveis/genética , Transferência Genética Horizontal/genética , Genoma Bacteriano/genética , Hydra/microbiologia , Hydra/ultraestrutura , Dados de Sequência Molecular , Junção Neuromuscular/ultraestruturaRESUMO
Hydra represents a unique model system for the study of senescence, with the opportunity for the comparison of non-aging and induced senescence. Hydra maintains three stem cell lineages, used for continuous tissue morphogenesis and replacement. Recent work has elucidated the roles of the insulin/IGF-1 signaling target FoxO, of Myc proteins, and of PIWI proteins in Hydra stem cells. Under laboratory culture conditions, Hydra vulgaris show no signs of aging even under long-term study. In contrast, Hydra oligactis can be experimentally induced to undergo reproduction-associated senescence. This provides a powerful comparative system for future studies.
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Mexicans in the United States have been reported to maintain practices of Mexican traditional medicine at comparably higher rates than most other populations, including other Latino sub-groups. In this cross-sectional study, we examined the pre- and post-migration traditional medicine practices of first-generation immigrants from Mexico living in southern Arizona. Our objective was to assess how migration affected Mexican immigrants' ethnomedical practices and to better understand the mechanisms and motivating factors for the post-migration maintenance of practice. We designed a survey instrument based off prior qualitative data on traditional medicine practices and translated it into Spanish. The survey measured the rates and frequency of six domains of lay healing practices: herbal medicine, healing foods, self-medication with over-the-counter medicine, and three types of specialty healers (curandero/a, and sobador/a, or partero/a), and asked questions about knowledge sources, reasons for maintaining practice post-migration, and to what extent participants believed the remedies were effective. The research team fielded the telephone-based survey from April 2022 to February 2023 to 300 first-generation adult Mexican immigrants residing in southern Arizona. A series of proportions tests were conducted to examine differences in reliance on lay healing pre- and post-migration as well as to assess differences between women's and men's lay practices. The data indicate a general, but moderated decline in lay medical practices post-migration, with the usage of expert healers declining at much higher rates than the three self-care domains. Women tend to use herbal medicine and healing foods at higher rates than men post-migration. This cross-sectional quantitative study confirms prior research indicating that traditional medicine practices are heavily relied upon by Mexican origin people both pre- and post-migration. These findings suggest that public health messaging and medical providers should better address and harness Mexican immigrants' lay medical practices in order to optimize health in this population.
Assuntos
Medicina Tradicional , Humanos , Arizona , Masculino , Feminino , Estudos Transversais , Medicina Tradicional/estatística & dados numéricos , Medicina Tradicional/métodos , Adulto , Pessoa de Meia-Idade , Emigrantes e Imigrantes/estatística & dados numéricos , Emigrantes e Imigrantes/psicologia , Americanos Mexicanos/estatística & dados numéricos , Americanos Mexicanos/psicologia , México/etnologia , Conhecimentos, Atitudes e Prática em Saúde , Inquéritos e Questionários , Idoso , População Norte-AmericanaRESUMO
BACKGROUND: Guided by Andersen's Behavioral Model of Health Services Use (BMHSU), this study aimed to identify determinants of post-migration healthcare use among a sample of Mexican immigrants in a US-Mexico border region in Southern Arizona, while considering pre-migration health and healthcare experiences. METHODS: A non-probabilistic convenience sample of 300 adult Mexican immigrants completed a telephone survey to assess healthcare practices. Multivariable logistic regressions were fitted to determine adjusted relationships between frequency of care and predisposing, enabling, need, and contextual factors as well as personal health practices. RESULTS: Overall, participants had a 79% probability of receiving healthcare "at least once a year" after migrating to Southern Arizona. Receiving post-migration healthcare was associated with predisposing, enabling, need, contextual factors, and personal health practices (p < 0.05). DISCUSSION: Consistent with BMHSU, our findings suggest that frequency of healthcare is not only a function of having post-migration health insurance but is also shaped by a complex array of other factors. The results of this study shed light onto potential areas to be leveraged by multifactorial sociocultural interventions to increase Mexican immigrants' frequency of healthcare services use.
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Recent studies and reports suggest an increased mortality rate of undocumented border crossers (UBCs) in Arizona is the result of heat extremes and climatic change. Conversely, others have shown that deaths have occurred in cooler environments than in previous years. We hypothesized that human locomotion plays a greater role in heat-related mortality and that such events are not simply the result of exposure. To test our hypothesis, we used a postmortem geographic application of the human heat balance equation for 2,746 UBC deaths between 1990 and 2022 and performed regression and cluster analyses to assess the impacts of ambient temperature and exertion. Results demonstrate exertion having greater explaining power, suggesting that heat-related mortality among UBCs is not simply a function of extreme temperatures, but more so a result of the required physical exertion. Additionally, the power of these variables is not static but changes with place, time, and policy.
Assuntos
Temperatura Alta , Esforço Físico , Humanos , Arizona/epidemiologia , Mudança Climática , Análise por ConglomeradosRESUMO
AbstractIntegrated chemo- and mechanosensory pathways, along with activated calcium influxes, regulate nematocyst discharge from sea anemone tentacles. Discharge from vibration-sensitive Type A cnidocyte supporting cell complexes use calcium-conducting transient receptor potential V4-like channels. Because calcium influxes often couple with calcium-activated, large-conductance potassium (BK) channels, we hypothesized that BK channels function in nematocyst discharge. To verify this hypothesis, we first tested five selective BK channel blockers on nematocyst-mediated prey killing in Diadumene lineata (aka Haliplanella luciae). All tested BK channel blockers inhibited prey killing at concentrations comparable to their inhibition of vertebrate BK channels. In addition, the BK channel blocker paxilline selectively inhibited prey killing mediated by vibration-sensitive Type A cnidocyte supporting cell complexes. We queried a mammalian BKα amino acid sequence to the Exaiptasia diaphena database, from which we identified a putative anemone, pore-forming BKα subunit sequence. Using the E. diaphena BKα sequence as a template, we assembled a BKα transcript from our assembled D. lineata transcriptome. In addition, the hydra homolog of D. lineata BKα localizes to nematocytes on the hydra single-cell RNA sequencing map. Our findings suggest that D. lineata expresses BK channels that play a role in vibration-sensitive nematocyst discharge from Type A cnidocyte supporting cell complexes. We believe this is the first functional demonstration of BK channels in nonbilaterians. Because stimulated chemoreceptors frequency tune Type A cnidocyte supporting cell complexes to frequencies matching swimming movements of prey via a protein kinase A signaling pathway and protein kinase A generally activates BK channels, we suggest that D. lineata BK channels may participate in protein kinase A-mediated frequency tuning.
Assuntos
Canais de Potássio Ativados por Cálcio de Condutância Alta , Nematocisto , Anêmonas-do-Mar , Animais , Anêmonas-do-Mar/fisiologia , Nematocisto/fisiologia , Canais de Potássio Ativados por Cálcio de Condutância Alta/metabolismo , VibraçãoRESUMO
In chlordecone (CLD)-contaminated soils of the French West Indies, if microbial remediation or a physicochemical remediation process, e.g., in situ chemical reduction, is implemented, concentrations of degradation byproducts, such as hydrochlordecones, are expected to increase in the ecosystems. To study their impact in mixtures with CLD, bioassays were carried out. They consisted in evaluating the regenerative capacity of hydra polyps, from a clone whose phylogenetic analysis confirmed that it belonged to the species Hydra vulgaris Pallas, 1766. Hydra gastric sections were exposed to CLD alone or CLD plus dechlorinated byproducts (CLD-BP) for 96 h to assess regeneration. Based on chromatographic analysis, the CLD-BP mix was composed of the 5-monohydrochlordecone isomer (CAS nomenclature), four dihydrochlordecone isomers, and one trihydrochlordecone isomer representing 50%, 47%, and 3% of the total chromatographic area, respectively. A total of 18 mixtures of CLD and CLD-BP were tested. Six environmental concentrations of CLD (2.10-4 µM to 4.10-2 µM) and a similar range of CLD-BP were used. Results from exposures to CLD alone showed the following: (i) a significant decrease in the regenerative capacity of hydra, except at the lowest concentration (2.10-4 µM); (ii) a concentration-independent deleterious effect. The regeneration scores obtained after the exposure to the addition of CLD-BP were not significantly different from those obtained after exposure to CLD alone. Using an experimental design, a modeling of the regeneration scores of hydra exposed to mixtures is proposed. Interpreted carefully, since they are limited to only one type of bioassay, the present results suggest that the situation in the aquatic environments should not become worse in terms of toxicity, if soil remediation programs resulting in the formation of hydrochlordecones are put in place.
Assuntos
Clordecona , Hydra , Animais , Projetos de Pesquisa , Ecossistema , Filogenia , Misturas ComplexasRESUMO
Animal genomes show networks of deeply conserved gene linkages whose phylogenetic scope and chromosomal context remain unclear. Here, we report chromosome-scale conservation of synteny among bilaterians, cnidarians, and sponges and use comparative analysis to reconstruct ancestral chromosomes across major animal groups. Comparisons among diverse metazoans reveal the processes of chromosome evolution that produced contemporary karyotypes from their Precambrian progenitors. On the basis of these findings, we introduce a simple algebraic representation of chromosomal change and use it to establish a unified systematic framework for metazoan chromosome evolution. We find that fusion-with-mixing, a previously unappreciated mode of chromosome change, has played a central role. We find that relicts of several metazoan chromosomal units are preserved in unicellular eukaryotes. These conserved pre-metazoan linkages include the chromosomal unit that encodes the most diverse set of metazoan homeobox genes, suggesting a candidate genomic context for the early diversification of this key gene family.
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Chemokines such as IL-8 are part of an important group of proinflammatory response molecules, as well as cell recruitment. However, it has been described in both higher vertebrates and fish that IL-8 has an additional functional role by acting as an antimicrobial effector, either directly or by cleavage of a peptide derived from its C-terminal end. Nevertheless, it is still unknown whether this fragment is released in the context of infection by bacterial pathogens and if it could be immunodetected in tissues of infected salmonids. Therefore, the objective of this research was to demonstrate that the C-terminal end of IL-8 from Oncorhynchus mykiss is cleaved, retaining its antibacterial properties, and that is detectable in tissues of infected rainbow trout. SDS-PAGE and mass spectrometry demonstrated the cleavage of a fragment of about 2 kDa when the recombinant IL-8 was subjected to acidic conditions. By chemical synthesis, it was possible to synthesize this fragment called omIL-8α80-97 peptide, which has antibacterial activity against Gram-negative and Gram-positive bacteria at concentrations over 10 µM. Besides, by fluorescence microscopy, it was possible to locate the omIL-8α80-97 peptide both on the cell surface and in the cytoplasm of the bacteria, as well as inside the monocyte/macrophage-like cell. Finally, by indirect ELISA, Western blot, and mass spectrometry, the presence of the fragment derived from the C-terminal end of IL-8 was detected in the spleen of trout infected with Piscirickettsia salmonis. The results reported in this work present the first evidence about the immunodetection of an antibacterial, and probably cell-penetrating peptide cleaved from the C-terminal end of IL-8 in monocyte/macrophage-like cell and tissue of infected rainbow trout.
Assuntos
Peptídeos Antimicrobianos/metabolismo , Infecções Bacterianas/veterinária , Doenças dos Peixes/imunologia , Interleucina-8/metabolismo , Oncorhynchus mykiss/imunologia , Aeromonas salmonicida/efeitos dos fármacos , Aeromonas salmonicida/fisiologia , Animais , Peptídeos Antimicrobianos/síntese química , Peptídeos Antimicrobianos/farmacologia , Infecções Bacterianas/imunologia , Hidrólise , Imunidade Inata , Macrófagos/metabolismo , Macrófagos/microbiologia , Piscirickettsia/fisiologia , Proteínas Recombinantes/metabolismo , Baço/imunologia , Distribuição Tecidual/imunologiaRESUMO
α-Enolase is an enzyme of the glycolytic pathway that has also been involved in vertebrate inflammatory processes through its interaction with plasminogen. However, its participation in the immune response of lower vertebrates during early life development is unknown. Opportunistic pathogens in salmon farming are the principal cause of mortality in the fry stage. For that reason, molecular indicators of their immunological status are required to ensure the success of the large-scale cultivation. Thus, the objective of this work was to analyze if ENO-1 is involved in the immune response of rainbow trout fry. For this purpose, the coding sequence of trout ENO-1 was characterized, identifying the plasminogen-binding domain that has been described for homologs of this enzyme in higher vertebrates. A peptide-epitope of α-enolase was used for producing mice antiserum. The specificity of polyclonal antibodies was confirmed by dot blot, ELISA and Western blot. Then, the antiserum was used to evaluate α-enolase expression in fry between 152 and 264 degree-days post-hatching after 2, 8, and 12 h of challenge with lipopolysaccharide from Pseudomona auroginosa. The expression of α-enolase at both transcriptional (RT-qPCR) and protein (ELISA) levels was significantly increased after 8 h post-challenge with lipopolysaccharide. These results were confirmed by proteomic analysis by 2D-difference gel electrophoresis (DIGE). This work provides the first evidence of the involvement of α-enolase in the early immune response of salmonids. Future research will be required to understand the possible interaction of α-enolase with plasminogen in cells and tissues of the salmonid immune system.
Assuntos
Biomarcadores/metabolismo , Proteínas de Peixes/metabolismo , Oncorhynchus mykiss/imunologia , Fosfopiruvato Hidratase/metabolismo , Animais , Doenças dos Peixes/imunologia , Proteínas de Peixes/genética , Imunidade Inata , Lipopolissacarídeos/imunologia , Fosfopiruvato Hidratase/genética , Plasminogênio/metabolismo , ProteômicaRESUMO
Wandering spleen is a rare condition, generally due to congenital abnormalities of the dorsal mesogastrium or splenic suspensory ligaments and not traumatic events. The most frequent complication is torsion of the splenic hilus with ischemia or splenic infarction and its association with pancreatic volvulus is extremely rare. There are no reported cases of wandering spleen with pancreatic volvulus in association with a post traumatic Grynfelt-Lesshaft haernia. We present a case of a 43-year-old female patient with an association of these three entities and a history of abdominal trauma.
El bazo errante es una afección rara que en general se debe a anomalías congénitas del mesogastrio dorsal o de los ligamentos suspensores esplénicos, y no a traumatismos. La complicación más frecuente es la torsión del hilio esplénico con isquemia o infarto esplénico, y su asociación a vólvulo pancreático es extremadamente rara. No existen ningún otro caso reportado de bazo errante con vólvulo pancreático en un paciente que presenta una hernia lumbar de Grynfelt-Lesshaft postraumática. Presentamos el caso de una paciente de 43 años con asociación de estas tres afecciones y antecedente de traumatismo abdominal.
Assuntos
Volvo Intestinal , Infarto do Baço , Baço Flutuante , Adulto , Feminino , Humanos , Esplenectomia , Infarto do Baço/diagnóstico por imagem , Infarto do Baço/etiologia , Anormalidade Torcional , Baço Flutuante/complicações , Baço Flutuante/diagnóstico por imagem , Baço Flutuante/cirurgiaRESUMO
The mid-latitude coastal area at the western South-Atlantic out of the tropics is under the combined effect of different atmospheric circulation patterns at different temporal scales, which can be shown by the isotope composition of precipitation. This pattern effect is more changing and complex than that for the well-studied tropical areas, the isotope studies being an interesting proxy for identifying major processes. This study is focused on the isotope composition of precipitation at a mid-latitude zone, in the western South-Atlantic coastal area of Argentina. δ18O and d-excess were analysed in a data series of 14 years, obtained from the integration of three neighbouring rain collectors at 38°S. A seasonality is observed in both parameters, but with some differences in the extreme months. δ18O showed a seasonality according to the temperature effect, but with a displacement of high values to spring months. Significant linear links between δ18O and Southern Annular Mode (SAM) index and Southern Oscillation Index (SOI) were recognised for the summer and spring seasons, respectively.
Assuntos
Atmosfera/química , Deutério/análise , Monitoramento Ambiental/métodos , Isótopos de Oxigênio/análise , Chuva/química , Ciclo Hidrológico , Argentina , Oceano Atlântico , Modelos Teóricos , Estações do AnoRESUMO
Eutrophication is a globally significant challenge facing aquatic ecosystems, mostly associated with human induced enrichment of these ecosystems with nitrogen and phosphorus. Given the complexity of assigning eutrophication issues to local primary N sources in field-based studies, this paper proposes a multi-stable isotope and biological framework to track nitrogen biogeochemical transformations, inputs and fate of nitrate in groundwater-dependent shallow lakes. Three representative freshwater ecosystems from the Pampa Plain (Argentina), with different land uses and topographic features were selected. Groundwater (N = 24), lake (N = 29) and stream (N = 20) samples were collected for isotope (δ15N-NO3- and δ18O-NO3-, δ18O-H2O) and hydrogeochemical (major ions and nutrients) determinations, and in the case of surface water, also for biological determinations (chlorophyll-a, fecal coliforms and nitrifying bacteria abundance). Both chemical and isotopic characteristics clearly indicated that denitrification was limited in lakes and streams, while evidence of assimilation in shallow lakes was confirmed. The results suggested that groundwater denitrification plays a role in the nitrate concentration pattern observed in the Pampeano Aquifer. The proportional contribution of nitrate sources to the inflow streams for all years were estimated by using Bayesian isotope mixing models, being ammonium nitrified in the system from soil and fertilizers ~50 - 75 %, sewage/manure ~20 - 40 % and atmospheric deposition ~5 - 15 %. In this sense, agricultural practices seem to have a relevant role in the eutrophication and water quality deterioration for these watersheds. However, limnological, bacterial and algal variables, assessed simultaneously with isotopic tracers, indicated spatio-temporal differences within and between these aquatic ecosystems. In the case of Nahuel Rucá Lake, animal manure was a significant source of nitrogen pollution, in contrast to La Brava Lake. In Los Padres Lake, agricultural practices were considered the main sources of nitrate input to the ecosystem.
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Eutrofização , Argentina , Teorema de Bayes , Ecossistema , Monitoramento Ambiental , Água Subterrânea , Nitratos , Isótopos de Nitrogênio , Poluentes Químicos da ÁguaRESUMO
Fluxes between fractured-karstified and detritic aquifers are commonly poorly understood in many environments. These two types of aquifers are in contact in the southeastern Pampean region in the Argentine Buenos Aires province, and the aim of this work is to analyze their relationship contributing to improve the hydrological model. A joint application of hydrochemical and multi-isotope (δ 2H, δ 18O, δ 13C-TDIC, δ 18O-TDIC, 87Sr/86Sr) tools was used. TDIC, δ 2H, δ 18O and δ 13C-TDIC allowed differentiating two main end members. Water in the Pampeano aquifer (PA) which is transferred from the fractured-karstic aquifer (F-KA) is characterised by high TDIC around 500-700â mg/L, isotopically depleted in 18O (about -5.5 ) and high δ 13C-TDIC (around -10.0 ). The other end member is direct recharge water infiltrated into the PA with TDIC ranging from 400 to 500â mg/L, slightly enriched in 18O (δ 18O = -4.8 ), and δ 13C-TDIC in the range of soil CO2 as a result of reactions with calcrete concretions (from -20.0 to -9.0 ). Dolomite dissolution is the main process controlling the chemistry of the low-mineralized (Mg-Ca-HCO3) waters, whereas high-mineralized (Na-HCO3) waters are strongly influenced by ion-exchange reactions with adsorbed Ca2+ and Mg2+ and by evaporation.
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Monitoramento Ambiental/métodos , Água Subterrânea/química , Isótopos/análise , Argentina , Carbonato de Cálcio/química , Magnésio/química , Solubilidade , Ciclo HidrológicoRESUMO
Despite the fact that Hydra has been studied for more than 200 years, we know surprisingly little about its life history. We show that Hydra vulgaris embryos hatch sporadically over a period ranging from a few days to nine months. We also report, for what seems to be the first time, the presence of Hydra in a vernal pool. Phylogenetic analysis and sexual crossing show that this Hydra is a member of the cosmopolitan Vulgaris clade and is not reproductively isolated from other members of the clade. Our findings lead us to hypothesize that Hydra evolved in an unstable freshwater habitat in which survival required that its life cycle include the use of a bet-hedging reproductive strategy and the formation of an embryo that is desiccation resistant and that can remain dormant for long periods of time.
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Hydra , Animais , Filogenia , Reprodução , Estações do AnoRESUMO
This study examines the risk factors predicting non-prescribed stimulant use (NPSU) among adolescents, with an emphasis on whether such factors are reflective of instrumental (e.g., studying) and/or recreational (e.g., partying) drug consumption settings. Using data from Monitoring the Future (2011), we employed a series of logistic regression models to establish predictors of 12-month self-reported Adderall or Ritalin use without a doctor's note among eighth and tenth graders. Whereas studies of college students have found NPSU to correlate with instrumental motives and productivity-related demands, we find no association between NPSU and indicators of academic strain for this younger sample. Rather, we find that the age of onset and current use of alcohol, tobacco, and marijuana are most predictive of NPSU, which are substances generally associated with social and recreational consumption settings. These findings have potential implications for practitioners concerned with mitigating the harms of general prescription drug misuse, as intervention efforts informed by research conducted among college students may not readily apply to younger populations. Drawing from central tenets of developmental and life course criminology, we call for continued inquiry into the broader socialization and developmental processes that influence NPSU and other prescription drug use patterns prior to early adulthood.