RESUMO
Leaf shape, a spectacularly diverse plant trait, varies across taxonomic levels, geography and in response to environmental differences. However, comprehensive intraspecific analyses of leaf shape variation across variable environments is surprisingly absent. Here, we performed a multilevel analysis of leaf shape using diverse accessions of sweet potato (Ipomoea batatas), and uncovered the role of genetics, environment, and G×E on this important trait. We examined leaf shape using a variety of morphometric analyses, and complement this with a transcriptomic survey to identify gene expression changes associated with shape variation. Additionally, we examined the role of genetics and environment on leaf shape by performing field studies in two geographically separate common gardens. We showed that extensive leaf shape variation exists within I. batatas, and identified promising candidate genes associated with this variation. Interestingly, when considering traditional measures, we found that genetic factors are largely responsible for most of leaf shape variation, but that the environment is highly influential when using more quantitative measures via leaf outlines. This extensive and multilevel examination of leaf shape shows an important role of genetics underlying a potentially important agronomic trait, and highlights that the environment can be a strong influence when using more quantitative measures of leaf shape.
Assuntos
Ipomoea batatas , Folhas de Planta/anatomia & histologia , Meio Ambiente , Interação Gene-Ambiente , Ipomoea batatas/genéticaRESUMO
Plants that use crassulacean acid metabolism (CAM) have the potential to meet growing agricultural resource demands using land that is considered unsuitable for many common crop species. Agave americana L., an obligate CAM plant, has potential as an advanced biofuel crop in water-limited regions, and has greater cold tolerance than other high-yielding CAM species, but physiological tolerances have not been completely resolved. We developed a model to estimate the growth responses of A. americana to water input, temperature, and photosynthetically active radiation (PAR). The photosynthetic response to PAR was determined experimentally by measuring the integrated leaf gas exchange over 24 h after acclimation to six light levels. Maximum CO2 fixation rates were observed at a PAR intensity of 1250 µmol photons m-2 s-1. Growth responses of A. americana to water and temperature were also determined, and a monthly environmental productivity index (EPI) was derived that can be used to predict biomass growth. The EPI was calculated as the product of water, temperature, and light indices estimated for conditions at a site in Maricopa (Arizona), and compared with measured biomass at the same site (where the first field trial of A. americana as a crop was completed). The monthly EPI summed over the lifetime of multi-year crops was highly correlated with the average measured biomass of healthy 2- and 3-year-old plants grown in the field. The resulting relationship between EPI and biomass provides a simple model for estimating the production of A. americana at a monthly time step according to light, temperature, and precipitation inputs, and is a useful tool for projecting the potential geographic range of this obligate CAM species in future climatic conditions.
Assuntos
Agave/crescimento & desenvolvimento , Biocombustíveis , Produtos Agrícolas/crescimento & desenvolvimento , Clima Desértico , Modelos Biológicos , Agave/efeitos da radiação , Biomassa , Produtos Agrícolas/efeitos da radiação , Luz , Temperatura , ÁguaRESUMO
Photosynthetic efficiency is a critical determinant of crop yield potential, although it remains below the theoretical optimum in modern crop varieties. Enhancing mesophyll conductance (i.e. the rate of carbon dioxide diffusion from substomatal cavities to the sites of carboxylation) may increase photosynthetic and water use efficiencies. To improve water use efficiency, mesophyll conductance should be increased without concomitantly increasing stomatal conductance. Here, we partition the variance in mesophyll conductance to within- and among-cultivar components across soybean (Glycine max) grown under both controlled and field conditions and examine the covariation of mesophyll conductance with photosynthetic rate, stomatal conductance, water use efficiency, and leaf mass per area. We demonstrate that mesophyll conductance varies more than 2-fold and that 38% of this variation is due to cultivar identity. As expected, mesophyll conductance is positively correlated with photosynthetic rates. However, a strong positive correlation between mesophyll and stomatal conductance among cultivars apparently impedes positive scaling between mesophyll conductance and water use efficiency in soybean. Contrary to expectations, photosynthetic rates and mesophyll conductance both increased with increasing leaf mass per area. The presence of genetic variation for mesophyll conductance suggests that there is potential to increase photosynthesis and mesophyll conductance by selecting for greater leaf mass per area. Increasing water use efficiency, though, is unlikely unless there is simultaneous stabilizing selection on stomatal conductance.
Assuntos
Glycine max/metabolismo , Células do Mesofilo/metabolismo , Fotossíntese , Estômatos de Plantas/metabolismo , Água/metabolismo , Algoritmos , Dióxido de Carbono/metabolismo , Clorofila/metabolismo , Difusão , Modelos Biológicos , Folhas de Planta/citologia , Folhas de Planta/genética , Folhas de Planta/metabolismo , Estômatos de Plantas/genética , Glycine max/classificação , Glycine max/genética , Especificidade da EspécieRESUMO
A greater understanding of natural variation in photosynthesis will inform strategies for crop improvement by revealing overlooked opportunities. We use Arabidopsis thaliana ecotypes as a model system to assess (i) how photosynthesis and photorespiration covary and (ii) how mesophyll conductance influences water use efficiency (WUE). Phenotypic variation in photorespiratory CO2 efflux was correlated with assimilation rates and two metrics of photosynthetic capacity (i.e. VCmax and Jmax); however, genetic correlations were not detected between photosynthesis and photorespiration. We found standing genetic variation-as broad-sense heritability-for most photosynthetic traits, including photorespiration. Genetic correlation between photosynthetic electron transport and carboxylation capacities indicates that these traits are genetically constrained. Winter ecotypes had greater mesophyll conductance, maximum carboxylation capacity, maximum electron transport capacity, and leaf structural robustness when compared with spring ecotypes. Stomatal conductance varied little in winter ecotypes, leading to a positive correlation between integrated WUE and mesophyll conductance. Thus, variation in mesophyll conductance can modulate WUE among A. thaliana ecotypes without a significant loss in assimilation. Genetic correlations between traits supplying energy and carbon to the Calvin-Benson cycle are consistent with biochemical models, suggesting that selection on either of these traits would improve all of them. Similarly, the lack of a genetic correlation between photosynthesis and photorespiration suggests that the positive scaling of these two traits can be broken.
Assuntos
Arabidopsis/fisiologia , Carbono/metabolismo , Metabolismo Energético , Fotossíntese/fisiologia , Estômatos de Plantas/fisiologia , Transpiração Vegetal/fisiologia , Ecótipo , Células do Mesofilo/fisiologia , Água/metabolismoRESUMO
The atmospheric [CO2 ] in which crops grow today is greater than at any point in their domestication history and represents an opportunity for positive effects on seed yield that can counteract the negative effects of greater heat and drought this century. In order to maximize yields under future atmospheric [CO2 ], we need to identify and study crop cultivars that respond most favorably to elevated [CO2 ] and understand the mechanisms contributing to their responsiveness. Soybean (Glycine max Merr.) is a widely grown oilseed crop and shows genetic variation in response to elevated [CO2 ]. However, few studies have studied the physiological basis for this variation. Here, we examined canopy light interception, photosynthesis, respiration and radiation use efficiency along with yield and yield parameters in two cultivars of soybean (Loda and HS93-4118) previously reported to have similar seed yield at ambient [CO2 ], but contrasting responses to elevated [CO2 ]. Seed yield increased by 26% at elevated [CO2 ] (600 µmol/mol) in the responsive cultivar Loda, but only by 11% in HS93-4118. Canopy light interception and leaf area index were greater in HS93-4118 in ambient [CO2 ], but increased more in response to elevated [CO2 ] in Loda. Radiation use efficiency and harvest index were also greater in Loda than HS93-4118 at both ambient and elevated [CO2 ]. Daily C assimilation was greater at elevated [CO2 ] in both cultivars, while stomatal conductance was lower. Electron transport capacity was also greater in Loda than HS93-4118, but there was no difference in the response of photosynthetic traits to elevated [CO2 ] in the two cultivars. Overall, this greater understanding of leaf- and canopy-level photosynthetic traits provides a strong conceptual basis for modeling genotypic variation in response to elevated [CO2 ].
Assuntos
Dióxido de Carbono , Glycine max , Fotossíntese , Folhas de Planta , Sementes , Glycine max/genética , Glycine max/crescimento & desenvolvimentoRESUMO
Extensive evidence shows that increasing carbon dioxide concentration ([CO2]) stimulates, and increasing temperature decreases, both net photosynthetic carbon assimilation (A) and biomass production for C3 plants. However the [CO2]-induced stimulation in A is projected to increase further with warmer temperature. While the influence of increasing temperature and [CO2], independent of each other, on A and biomass production have been widely investigated, the interaction between these two major global changes has not been tested on field-grown crops. Here, the interactive effect of both elevated [CO2] (approximately 585 µmol mol(-1)) and temperature (+3.5°C) on soybean (Glycine max) A, biomass, and yield were tested over two growing seasons in the Temperature by Free-Air CO2 Enrichment experiment at the Soybean Free Air CO2 Enrichment facility. Measurements of A, stomatal conductance, and intercellular [CO2] were collected along with meteorological, water potential, and growth data. Elevated temperatures caused lower A, which was largely attributed to declines in stomatal conductance and intercellular [CO2] and led in turn to lower yields. Increasing both [CO2] and temperature stimulated A relative to elevated [CO2] alone on only two sampling days during 2009 and on no days in 2011. In 2011, the warmer of the two years, there were no observed increases in yield in the elevated temperature plots regardless of whether [CO2] was elevated. All treatments lowered the harvest index for soybean, although the effect of elevated [CO2] in 2011 was not statistically significant. These results provide a better understanding of the physiological responses of soybean to future climate change conditions and suggest that the potential is limited for elevated [CO2] to mitigate the influence of rising temperatures on photosynthesis, growth, and yields of C3 crops.
Assuntos
Dióxido de Carbono/farmacologia , Aquecimento Global , Glycine max/fisiologia , Fotossíntese/efeitos dos fármacos , Transpiração Vegetal/efeitos dos fármacos , Biomassa , Meio-Oeste dos Estados Unidos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Chuva , Glycine max/efeitos dos fármacos , Glycine max/crescimento & desenvolvimento , Luz Solar , TemperaturaRESUMO
The heterotrimeric G-protein complex provides signal amplification and target specificity. The Arabidopsis (Arabidopsis thaliana) Gß-subunit of this complex (AGB1) interacts with and modulates the activity of target cytoplasmic proteins. This specificity resides in the structure of the interface between AGB1 and its targets. Important surface residues of AGB1, which were deduced from a comparative evolutionary approach, were mutated to dissect AGB1-dependent physiological functions. Analysis of the capacity of these mutants to complement well-established phenotypes of Gß-null mutants revealed AGB1 residues critical for specific AGB1-mediated biological processes, including growth architecture, pathogen resistance, stomata-mediated leaf-air gas exchange, and possibly photosynthesis. These findings provide promising new avenues to direct the finely tuned engineering of crop yield and traits.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Subunidades beta da Proteína de Ligação ao GTP/metabolismo , Transdução de Sinais , Ácido Abscísico/farmacologia , Agricultura , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/microbiologia , Flagelina/farmacologia , Glucose/farmacologia , Modelos Moleculares , Mutagênese Sítio-Dirigida , Proteínas Mutantes/metabolismo , Mutação/genética , Fenótipo , Plantas Geneticamente Modificadas , Dobramento de Proteína/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos , Propriedades de Superfície/efeitos dos fármacosRESUMO
Globally, photosynthesis accounts for the largest flux of CO2 from the atmosphere into ecosystems and is the driving process for terrestrial ecosystem function. The importance of accurate predictions of photosynthesis over a range of plant growth conditions led to the development of a C3 photosynthesis model by Farquhar, von Caemmerer & Berry that has become increasingly important as society places greater pressures on vegetation. The photosynthesis model has played a major role in defining the path towards scientific understanding of photosynthetic carbon uptake and the role of photosynthesis on regulating the earth's climate and biogeochemical systems. In this review, we summarize the photosynthesis model, including its continued development and applications. We also review the implications these developments have on quantifying photosynthesis at a wide range of spatial and temporal scales, and discuss the model's role in determining photosynthetic responses to changes in environmental conditions. Finally, the review includes a discussion of the larger-scale modelling and remote-sensing applications that rely on the leaf photosynthesis model and are likely to open new scientific avenues to address the increasing challenges to plant productivity over the next century.
Assuntos
Carbono/metabolismo , Cloroplastos/metabolismo , Ecossistema , Modelos Biológicos , Fotossíntese , Ribulose-Bifosfato Carboxilase/metabolismoRESUMO
BACKGROUND: Biochemical models predict that photosynthesis in C(3) plants is most frequently limited by the slower of two processes, the maximum capacity of the enzyme Rubisco to carboxylate RuBP (V(c,max)), or the regeneration of RuBP via electron transport (J). At current atmospheric [CO(2)] levels Rubisco is not saturated; consequently, elevating [CO(2)] increases the velocity of carboxylation and inhibits the competing oxygenation reaction which is also catalyzed by Rubisco. In the future, leaf photosynthesis (A) should be increasingly limited by RuBP regeneration, as [CO(2)] is predicted to exceed 550 ppm by 2050. The C(3) cycle enzyme sedoheptulose-1,7 bisphosphatase (SBPase, EC 3.1.3.17) has been shown to exert strong metabolic control over RuBP regeneration at light saturation. RESULTS: We tested the hypothesis that tobacco transformed to overexpressing SBPase will exhibit greater stimulation of A than wild type (WT) tobacco when grown under field conditions at elevated [CO(2)] (585 ppm) under fully open air fumigation. Growth under elevated [CO(2)] stimulated instantaneous A and the diurnal photosynthetic integral (A') more in transformants than WT. There was evidence of photosynthetic acclimation to elevated [CO(2)] via downregulation of V(c,max) in both WT and transformants. Nevertheless, greater carbon assimilation and electron transport rates (J and J(max)) for transformants led to greater yield increases than WT at elevated [CO(2)] compared to ambient grown plants. CONCLUSION: These results provide proof of concept that increasing content and activity of a single photosynthesis enzyme can enhance carbon assimilation and yield of C(3) crops grown at [CO(2)] expected by the middle of the 21st century.
Assuntos
Dióxido de Carbono/metabolismo , Nicotiana/enzimologia , Monoéster Fosfórico Hidrolases/metabolismo , Fotossíntese , Folhas de Planta/enzimologia , Biomassa , Carbono/metabolismo , Plantas Geneticamente Modificadas/enzimologia , Nicotiana/genética , Nicotiana/crescimento & desenvolvimentoRESUMO
Woody plants native to mesic habitats tend to be more vulnerable to drought-induced cavitation than those in xeric habitats. Cavitation resistance in herbaceous plants, however, is rarely studied and whether or not annual plants in arid habitats conform to the trends observed in woody plants is unknown. This question is addressed by comparing the hydraulic properties of annual plants endemic to relatively mesic and seasonally xeric habitats in the Great Basin Desert, in both native and experimental settings. Vulnerability to cavitation between species differed as predicted when vulnerability curves of similar-sized native individuals were compared. Contrary to expectations, Helianthus anomalus from the relatively mesic dune sites, on average, exhibited higher native embolism, lower soil-to-leaf hydraulic conductance (k(L)) and lower transpiration rates, than its xeric analogue, H. deserticola. In transplant gardens, H. anomalus' vulnerability to cavitation was unaffected by transplant location or watering treatment. In H. deserticola, however, vulnerability to cavitation varied significantly in response to watering in transplant gardens and varied as a function of stem water potential (Psi(stem)). H. deserticola largely avoided cavitation through its higher water status and generally more resistant xylem, traits consistent with a short life cycle and typical drought-escape strategy. By contrast, H. anomalus' higher native embolism is likely to be adaptive by lowering plant conductance and transpiration rate, thus preventing the loss of root-to-soil hydraulic contact in the coarse sand dune soils. For H. anomalus this dehydration avoidance strategy is consistent with its relatively long 3-4 month life cycle and low-competition habitat. We conclude that variance of hydraulic parameters in herbaceous plants is a function of soil moisture heterogeneity and is consistent with the notion that trait plasticity to fine-grained environmental variation can be adaptive.
Assuntos
Adaptação Fisiológica , Clima Desértico , Secas , Helianthus/fisiologia , Hibridização Genética , Análise de Variância , Ecossistema , Helianthus/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Transpiração Vegetal/fisiologia , Pressão , Chuva , Estações do Ano , Especificidade da Espécie , Água/fisiologia , Xilema/fisiologiaRESUMO
Viola pubescens is a perennial, mixed breeding herb that produces both chasmogamous and cleistogamous flowers at different times of the season. Once bud type is specified, it does not convert from one form to the other. While temporal production of the two flowers is known to be influenced by environmental factors, the specific environmental cues that signal emergence of each flower type have not been empirically studied. To investigate the environmental parameters driving seasonal development of chasmogamous versus cleistogamous flowers, a native V. pubescens population was examined during the spring and summer of 2016 and 2017. Measurements of light quantity, canopy cover, photoperiod, temperature, soil moisture, soil pH, and the number of chasmogamous and cleistogamous buds were collected on either a weekly or biweekly basis. Independent zero-inflated negative binomial (ZINB) regressions were used to model the odds of bud production (0 versus 1 bud) and bud counts (≥ 1 bud) as a function of the environmental variables. Results of the ZINB models highlight key differences between the environmental variables that influence chasmogamous versus cleistogamous bud development and counts. In addition to the ZINB regressions, individual logistic regressions were fit to the bud data. The logistic models support results of the ZINB models and, more crucially, identify specific environmental thresholds at which each bud type is probable. Collectively, this work offers novel insight into how environmental variables shape temporal development of chasmogamous and cleistogamous flowers, suggests distinct threshold values that may aid in selectively inducing each flower type, and provides insight into how climatic change may impact mixed breeding species.
Assuntos
Cruzamento , Meio Ambiente , Flores/fisiologia , Viola/fisiologia , Luz , Fotoperíodo , Probabilidade , Análise de Regressão , Estações do Ano , Solo , Temperatura , Fatores de TempoRESUMO
It is plain that an individual's being conscious and an individual's being conscious of various things are both crucial for successful functioning. But it is far less clear how, if at all, it is also useful for a person's psychological states to occur consciously, as against those states occurring but without being conscious. Restricting attention to cognitive and desiderative states, a number of suggestions are current about how the consciousness of those states may be useful. It has been held that such consciousness enhances processes of rational thought and planning, intentional action, executive function, and the correction of complex reasoning. I examine these and related proposals in the light of various empirical findings and theoretical considerations and conclude that the consciousness of cognitive and desiderative states is unlikely to be useful in these or related ways. This undermines a reliance on evolutionary selection pressures in explaining why such states so often occur consciously in humans. I propose an alternative explanation, on which cognitive and desiderative states come to be conscious as a result of other highly useful psychological developments, some involving language. But on this explanation the consciousness of these states itself adds no significant function to that of those other developments.
Assuntos
Estado de Consciência/fisiologia , Teoria Psicológica , Humanos , Intenção , Resolução de ProblemasRESUMO
We compared the levels and distribution of genetic diversity in Eurasian and North American populations of Brachypodium sylvaticum (Huds.) Beauv. (false brome), a newly invasive perennial bunchgrass in western North America. Our goals were to identify source regions for invasive populations, determine the number of independent invasion events, and assess the possibility that postinvasion bottlenecks and hybridization have affected patterns of genetic diversity in the invaded range. We tested the hypothesis that this Eurasian grass was accidentally introduced into two areas in Oregon and one site in California by examining nuclear microsatellites and chloroplast haplotype variation in 23 introduced and 25 native populations. In the invaded range, there was significantly lower allelic richness (R(S)), observed heterozygosity (H(O)) and within-population gene diversity (H(S)), although a formal test failed to detect a significant genetic bottleneck. Most of the genetic variation existed among populations in the native range but within populations in the invaded range. All of the allelic variation in the invaded range could be explained based on alleles found in western European populations. The distribution of identified genetic clusters in the North American populations and the unique alleles associated with them is consistent with two historical introductions in Oregon and a separate introduction to California. Further analyses of population structure indicate that intraspecific hybridization among genotypes from geographically distinct regions of western Europe occurred following colonization in Oregon. The California populations, however, are more likely to be derived from one or perhaps several genetically similar regions in the native range. The emergence and spread of novel recombinant genotypes may be facilitating the rapid spread of this invasive species in Oregon.
Assuntos
Genética Populacional , Hibridização Genética , Poaceae/genética , Alelos , California , DNA de Cloroplastos/genética , Variação Genética , Haplótipos , Repetições de Microssatélites , Oregon , Dinâmica PopulacionalRESUMO
OBJECTIVES: To compare the outcomes of total laparoscopic hysterectomy (TLH) and vaginal hysterectomy (VH) in a community teaching hospital. METHODS: A retrospective chart review of all women who underwent TLH and VH at North York General Hospital between January 2002 and December 2004 was conducted. Groups were compared with respect to demographic data, and intraoperative and postoperative outcomes. RESULTS: One hundred nine women underwent TLH, and 43 women underwent VH. There was no statistically significant difference between groups in the mean age of patients, estimated blood loss, or mean postoperative hemoglobin change. TLH took significantly longer to perform (104.4 vs. 54.4 minutes, P < 0.001); however, the mean postoperative duration of hospital stay was greater in the VH group (2.2 vs. 1.2 days, P < 0.001). Mean uterine mass was significantly greater in the TLH group (290.9 vs. 151.6 g, P < 0. 001). The incidence of intraoperative and postoperative complications was slightly higher in the TLH group than in the VH group, but the difference did not reach statistical significance. CONCLUSIONS: TLH was associated with significantly longer operative time and shorter hospital stay than VH. There was a trend towards more intraoperative and postoperative complications in the TLH group than in the VH group.
Assuntos
Histerectomia/métodos , Laparoscopia , Estudos de Coortes , Feminino , Humanos , Tempo de Internação , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de TempoRESUMO
OBJECTIVE: To review the surgical outcomes of total laparoscopic hysterectomy (TLH) over a five-year period in a teaching community hospital. METHODS: We reviewed demographic data, intraoperative and postoperative outcomes, and morbidity data on 175 women who underwent TLH between January 2001 and December 2005. RESULTS: No bowel or urinary tract injury occurred in any of the patients. The major and minor complication rates were 4% and 2.9% respectively. The mean operating time was 108.2 minutes, standard deviation (SD) 29.6 minutes, range 60-199 minutes, and the mean length of hospital stay was 1.2 days, SD 0.4 days. The mean uterine weight was 292.9 g, SD 206.3 g, with the largest specimen weighing 1126 g. CONCLUSION: The cases reported here had operating times and lengths of hospital stay that were similar to those in previously published reports. TLH is a safe and acceptable alternative to standard hysterectomy.
Assuntos
Doenças dos Genitais Femininos/epidemiologia , Doenças dos Genitais Femininos/cirurgia , Histerectomia/estatística & dados numéricos , Laparoscopia/estatística & dados numéricos , Avaliação de Resultados em Cuidados de Saúde , Feminino , Doenças dos Genitais Femininos/etiologia , Hospitais Universitários , Humanos , Complicações Intraoperatórias , Tempo de Internação , Prontuários Médicos , Pessoa de Meia-Idade , Ontário/epidemiologia , Complicações Pós-Operatórias , Estudos RetrospectivosRESUMO
Much of our knowledge of speciation genetics stems from quantitative trait locus (QTL) studies. However, interpretations of the size and distribution of QTL underlying species differences are complicated by differences in the way QTL magnitudes are estimated. Also, many studies fail to exploit information about QTL directions or to compare inter- and intraspecific QTL variation. Here, we comprehensively analyze an extensive QTL data set for an interspecific backcross between two wild annual sunflowers, Helianthus annuus and H. petiolaris, interpret different estimates of QTL magnitudes, identify trait groups that have diverged through selection, and compare inter- and intraspecific QTL magnitudes. Our results indicate that even minor QTL (in terms of backcross variance) may be surprisingly large compared to levels of standing variation in the parental species or phenotypic differences between them. Morphological traits, particularly flower morphology, were more strongly or consistently selected than life history or physiological traits. Also, intraspecific QTL were generally smaller than interspecific ones, consistent with the prediction that larger QTL are more likely to spread to fixation across a subdivided population. Our results inform the genetics of species differences in Helianthus and suggest an approach for the simultaneous mapping of inter- and intraspecific QTL.
Assuntos
Helianthus/genética , Locos de Características Quantitativas , Alelos , Mapeamento Cromossômico , Cruzamentos Genéticos , Epistasia Genética , Genes de Plantas , Marcadores Genéticos , Variação Genética , Genética Populacional , Modelos Genéticos , Fenótipo , Característica Quantitativa Herdável , Especificidade da Espécie , Estatística como AssuntoRESUMO
INTRODUCTION: Naloxone, an opiate antagonist that can avert opiate overdose morality, has long been prescribed to drug users in Europe and in a few US cities. However, there has been little documented evidence of naloxone distribution programs and their feasibility in the peer reviewed literature in the US. METHODS: A pilot overdose prevention and reversal program was implemented in a New York City syringe exchange program. We assessed demographics, drug use, and overdose history, experience, and behavior at baseline, when participants returned for prescription refills, and 3 months after baseline assessment. RESULTS: 25 participants were recruited. 22 (88%) participants were successfully followed-up in the first 3 months; of these, 11 (50%) participants reported witnessing a total of 26 overdoses during the follow-up period. Among 17 most-recent overdoses witnessed, naloxone was administered 10 times; all persons who had naloxone administered lived. DISCUSSION: Naloxone administration by injection drug users is feasible as part of a comprehensive overdose prevention strategy and may be a practicable way to reduce overdose deaths on a larger scale.
Assuntos
Naloxona/uso terapêutico , Antagonistas de Entorpecentes/uso terapêutico , Abuso de Substâncias por Via Intravenosa/reabilitação , Overdose de Drogas/prevenção & controle , Overdose de Drogas/terapia , Uso de Medicamentos/estatística & dados numéricos , Feminino , Seguimentos , Humanos , Masculino , Programas de Troca de Agulhas , Projetos Piloto , Avaliação de Programas e Projetos de Saúde , Abuso de Substâncias por Via Intravenosa/complicaçõesRESUMO
We investigated the effects of historic soil chemistry changes associated with acid rain, i.e., reduced soil pH and a shift from nitrogen (N)- to phosphorus (P)-limitation, on the coordination of leaf water demand and xylem hydraulic supply traits in two co-occurring temperate tree species differing in growth rate. Using a full-factorial design (Nâ ×â Pâ ×â pH), we measured leaf nutrient content, water relations, leaf-level and canopy-level gas exchange, total biomass and allocation, as well as stem xylem anatomy and hydraulic function for greenhouse-grown saplings of fast-growing Acer rubrum (L.) and slow-growing Quercus alba (L.). We used principle component analysis to characterize trait coordination. We found that N-limitation, but not P-limitation, had a significant impact on plant water relations and hydraulic coordination of both species. Fast-growing A. rubrum made hydraulic adjustments in response to N-limitation, but trait coordination was variable within treatments and did not fully compensate for changing allocation across N-availability. For slow-growing Q. alba, N-limitation engendered more strict coordination of leaf and xylem traits, resulting in similar leaf water content and hydraulic function across all treatments. Finally, low pH reduced the propensity of both species to adjust leaf water relations and xylem anatomical traits in response to nutrient manipulations. Our data suggest that a shift from N- to P-limitation has had a negative impact on the water relations and hydraulic function of A. rubrum to a greater extent than for Q. alba We suggest that current expansion of A. rubrum populations could be tempered by acidic N-deposition, which may restrict it to more mesic microsites. The disruption of hydraulic acclimation and coordination at low pH is emphasized as an interesting area of future study.