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1.
Nature ; 610(7933): 687-692, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-36049503

RESUMEN

The social cost of carbon dioxide (SC-CO2) measures the monetized value of the damages to society caused by an incremental metric tonne of CO2 emissions and is a key metric informing climate policy. Used by governments and other decision-makers in benefit-cost analysis for over a decade, SC-CO2 estimates draw on climate science, economics, demography and other disciplines. However, a 2017 report by the US National Academies of Sciences, Engineering, and Medicine1 (NASEM) highlighted that current SC-CO2 estimates no longer reflect the latest research. The report provided a series of recommendations for improving the scientific basis, transparency and uncertainty characterization of SC-CO2 estimates. Here we show that improved probabilistic socioeconomic projections, climate models, damage functions, and discounting methods that collectively reflect theoretically consistent valuation of risk, substantially increase estimates of the SC-CO2. Our preferred mean SC-CO2 estimate is $185 per tonne of CO2 ($44-$413 per tCO2: 5%-95% range, 2020 US dollars) at a near-term risk-free discount rate of 2%, a value 3.6 times higher than the US government's current value of $51 per tCO2. Our estimates incorporate updated scientific understanding throughout all components of SC-CO2 estimation in the new open-source Greenhouse Gas Impact Value Estimator (GIVE) model, in a manner fully responsive to the near-term NASEM recommendations. Our higher SC-CO2 values, compared with estimates currently used in policy evaluation, substantially increase the estimated benefits of greenhouse gas mitigation and thereby increase the expected net benefits of more stringent climate policies.


Asunto(s)
Dióxido de Carbono , Modelos Climáticos , Factores Socioeconómicos , Dióxido de Carbono/análisis , Dióxido de Carbono/economía , Clima , Gases de Efecto Invernadero/análisis , Gases de Efecto Invernadero/economía , Incertidumbre , Descuento por Demora , Riesgo , Formulación de Políticas , Política Ambiental
2.
Demography ; 60(3): 915-937, 2023 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-37212712

RESUMEN

Population projections provide predictions of future population sizes for an area. Historically, most population projections have been produced using deterministic or scenario-based approaches and have not assessed uncertainty about future population change. Starting in 2015, however, the United Nations (UN) has produced probabilistic population projections for all countries using a Bayesian approach. There is also considerable interest in subnational probabilistic population projections, but the UN's national approach cannot be used directly for this purpose, because within-country correlations in fertility and mortality are generally larger than between-country ones, migration is not constrained in the same way, and there is a need to account for college and other special populations, particularly at the county level. We propose a Bayesian method for producing subnational population projections, including migration and accounting for college populations, by building on but modifying the UN approach. We illustrate our approach by applying it to the counties of Washington State and comparing the results with extant deterministic projections produced by Washington State demographers. Out-of-sample experiments show that our method gives accurate and well-calibrated forecasts and forecast intervals. In most cases, our intervals were narrower than the growth-based intervals issued by the state, particularly for shorter time horizons.


Asunto(s)
Fertilidad , Pronóstico de Población , Humanos , Teorema de Bayes , Predicción , Dinámica Poblacional , Mortalidad
3.
Int J Forecast ; 39(1): 73-97, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36568848

RESUMEN

Population forecasts are used by governments and the private sector for planning, with horizons up to about three generations (around 2100) for different purposes. The traditional methods are deterministic using scenarios, but probabilistic forecasts are desired to get an idea of accuracy, assess changes, and make decisions involving risks. In a significant breakthrough, since 2015, the United Nations has issued probabilistic population forecasts for all countries using a Bayesian methodology that we review here. Assessment of the social cost of carbon relies on long-term forecasts of carbon emissions, which in turn depend on even longer-range population and economic forecasts, to 2300. We extend the UN method to very-long range population forecasts by combining the statistical approach with expert review and elicitation. While the world population is projected to grow for the rest of this century, it will likely stabilize in the 22nd century and decline in the 23rd century.

4.
Physiol Plant ; 167(3): 365-377, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30536419

RESUMEN

Rate of photosynthesis and related plant carbohydrate status are crucial factors affecting plant vigor. Sugars providing carbon and energy sources serve also as important signaling molecules governing plant growth and development through a complex regulatory network. These facts are often neglected when mixotrophic cultivation of plants in vitro is used, where artificial exogenous sugar supply hinders studies of metabolism as well as sugar-driven developmental processes. We compared the growth, selected gas-exchange parameters and sugar metabolism characteristics in four model plants, potato (Solanum tuberosum 'Lada'), tobacco (Nicotiana tabacum 'Samsun'), rapeseed (Brassica napus 'Asgard') and strawberry (Fragaria vesca), under both photomixotrophic (PM) and photoautotrophic (PA) conditions. To ensure PA conditions, we used our improved sun caps that serve as gas and light permeable covers for cultivation vessels. We found bigger biomass accumulation, larger leaf areas, higher stomatal conductance and higher instantaneous water use efficiency and lower root sugar contents in PA plants compared to PM ones. However, for other characteristics (root biomass, root/shoot ratio, pigment contents, leaf sugar and starch levels and transpiration rates), a strong species-dependent reactions to the exogenous sugar supply was noted, which does not allow to create a general view on the overall impact of PM nutrition under in vitro conditions.


Asunto(s)
Fotosíntesis/fisiología , Hojas de la Planta/metabolismo , Hojas de la Planta/fisiología , Raíces de Plantas/metabolismo , Raíces de Plantas/fisiología , Brassica napus/genética , Brassica napus/metabolismo , Brassica napus/fisiología , Fragaria/genética , Fragaria/metabolismo , Fragaria/fisiología , Fotosíntesis/genética , Hojas de la Planta/genética , Raíces de Plantas/genética , Nicotiana/genética , Nicotiana/metabolismo , Nicotiana/fisiología
5.
Proc Natl Acad Sci U S A ; 113(23): 6460-5, 2016 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-27217571

RESUMEN

We produce probabilistic projections of population for all countries based on probabilistic projections of fertility, mortality, and migration. We compare our projections to those from the United Nations' Probabilistic Population Projections, which uses similar methods for fertility and mortality but deterministic migration projections. We find that uncertainty in migration projection is a substantial contributor to uncertainty in population projections for many countries. Prediction intervals for the populations of Northern America and Europe are over 70% wider, whereas prediction intervals for the populations of Africa, Asia, and the world as a whole are nearly unchanged. Out-of-sample validation shows that the model is reasonably well calibrated.


Asunto(s)
Predicción , Migración Humana , Modelos Estadísticos , Humanos , Reproducibilidad de los Resultados , Incertidumbre
6.
Demogr Res ; 38: 1843-1884, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-31942164

RESUMEN

BACKGROUND: We consider the problem of probabilistic projection of the total fertility rate (TFR) for subnational regions. OBJECTIVE: We seek a method that is consistent with the UN's recently adopted Bayesian method for probabilistic TFR projections for all countries and works well for all countries. METHODS: We assess various possible methods using subnational TFR data for 47 countries. RESULTS: We find that the method that performs best in terms of out-of-sample predictive performance and also in terms of reproducing the within-country correlation in TFR is a method that scales each national trajectory from the national predictive posterior distribution by a region-specific scale factor that is allowed to vary slowly over time. CONCLUSIONS: Probabilistic projections of TFR for subnational units are best produced by scaling the national projection by a slowly time-varying region-specific scale factor. This supports the hypothesis of Watkins (1990, 1991) that within-country TFR converges over time in response to country-specific factors, and thus extends the Watkins hypothesis to the last 50 years and to a much wider range of countries around the world. CONTRIBUTION: We have developed a new method for probabilistic projection of subnational TFR that works well and outperforms other methods. This also sheds light on the extent to which within-country TFR converges over time.

7.
Sydowia ; 69: 229-264, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-29386695

RESUMEN

The present study introduces seven new species, one new combination, one new variety and several interesting taxonomical notes and/or geographical records. Most of the new taxa are Ascomycetes, but the study also includes a new variety of a Basidiomycete. Novel species include Gyromitra khanspurensis (Discinaceae, Pezizales, Pezizomycetes) from Pakistan growing near Cedrus deoadara and Paramyrothecium guiyangense and Paramyrothecium verruridum (Stachybotriaceae, Hypocreales, Sordariomycetes) both isolated from soil in China. New species from South Africa are Sclerostagonospora elegiae on culm litter of Elegia equisetacea, Sclerostagonospora fusiformis on culm litter of Thamnochortus spicigerus, Sclerostagonospora pinguis on culm litter of Cannomois virgata and Sclerostagonospora sulcata on culm litter of Ischyrolepis subverticellata (Phaeosphaeriaceae, Pleosporales, Dothideomycetes). Hapalocystis berkeleyi var. kickxii with its basionym Hypoxylon kickxii is shown to be a taxon on species level and thus recombined as Hapalocystis kickxii (Sydowiellaceae, Diaporthales, Sordariomycetes), and it is lecto- and epitypified. The new variety Pluteus romellii var. luteoalbus (Pluteaceae, Agaricales, Agaricomycetes) growing on a mossy fallen stem of a deciduous tree is described from Czech Republic. Cortinarius scaurocaninus (Cortinariaceae, Agaricales, Agaricomycetes) is new for Austria, Humicola grisea (Chaetomiaceae, Sordariales, Sordariomycetes) is an interesting new record for Chile. Two taxa are reported as new for Turkey: the lichenicolous fungus Opegrapha parasitica (Opegraphaceae, Arthoniales, Arthoniomycetes) growing partly immersed in the thallus of Aspicilia and the lichen Rinodina zwackhiana (Physciaceae, Teloschistales, Lecanoromycetes) from calcareous rock. Finally, Xerula strigosa (Physalacriaceae, Agaricales, Agaricomycetes), described from China, is confirmed to be present also in Pakistan.

8.
J Stat Softw ; 752016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28077933

RESUMEN

We describe bayesPop, an R package for producing probabilistic population projections for all countries. This uses probabilistic projections of total fertility and life expectancy generated by Bayesian hierarchical models. It produces a sample from the joint posterior predictive distribution of future age- and sex-specific population counts, fertility rates and mortality rates, as well as future numbers of births and deaths. It provides graphical ways of summarizing this information, including trajectory plots and various kinds of probabilistic population pyramids. An expression language is introduced which allows the user to produce the predictive distribution of a wide variety of derived population quantities, such as the median age or the old age dependency ratio. The package produces aggregated projections for sets of countries, such as UN regions or trading blocs. The methodology has been used by the United Nations to produce their most recent official population projections for all countries, published in the World Population Prospects.

9.
Proc Natl Acad Sci U S A ; 109(35): 13915-21, 2012 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-22908249

RESUMEN

Projections of countries' future populations, broken down by age and sex, are widely used for planning and research. They are mostly done deterministically, but there is a widespread need for probabilistic projections. We propose a bayesian method for probabilistic population projections for all countries. The total fertility rate and female and male life expectancies at birth are projected probabilistically using bayesian hierarchical models estimated via Markov chain Monte Carlo using United Nations population data for all countries. These are then converted to age-specific rates and combined with a cohort component projection model. This yields probabilistic projections of any population quantity of interest. The method is illustrated for five countries of different demographic stages, continents and sizes. The method is validated by an out of sample experiment in which data from 1950-1990 are used for estimation, and applied to predict 1990-2010. The method appears reasonably accurate and well calibrated for this period. The results suggest that the current United Nations high and low variants greatly underestimate uncertainty about the number of oldest old from about 2050 and that they underestimate uncertainty for high fertility countries and overstate uncertainty for countries that have completed the demographic transition and whose fertility has started to recover towards replacement level, mostly in Europe. The results also indicate that the potential support ratio (persons aged 20-64 per person aged 65+) will almost certainly decline dramatically in most countries over the coming decades.


Asunto(s)
Tasa de Natalidad/tendencias , Censos , Demografía/métodos , Predicción/métodos , Naciones Unidas/estadística & datos numéricos , Adulto , Distribución por Edad , Anciano , Anciano de 80 o más Años , Teorema de Bayes , Brasil/epidemiología , China/epidemiología , Femenino , Humanos , India/epidemiología , Esperanza de Vida/tendencias , Modelos Logísticos , Madagascar/epidemiología , Masculino , Persona de Mediana Edad , Países Bajos/epidemiología , Distribución por Sexo , Adulto Joven
10.
J Fungi (Basel) ; 9(9)2023 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-37755006

RESUMEN

We studied the taxonomy of Pluteus podospileus and similar species using morphological and molecular (nrITS, TEF1-α) data, including a detailed study of the type collections of P. inflatus var. alneus, Pluteus minutissimus f. major, and P. granulatus var. tenellus. Within the P. podospileus complex, we phylogenetically confirmed six species in Europe, five in Asia, and eight in North America. Based on our results, we recognize P. seticeps as a separate species occurring in North America, while P. podospileus is limited to Eurasia. We describe six new species and a new variety: P. absconditus, P. fuscodiscus, P. gausapatus, P. inexpectatus, P. millsii, and P. notabilis and its variety, P. notabilis var. insignis. We elevate Pluteus seticeps var. cystidiosus to species rank as Pluteus cystidiosus. Based on the holotype of P. inflatus var. alneus, collections of P. inflatus identified by Velenovský, and several modern collections, we resurrect the name P. inflatus. Based on molecular analyses of syntypes of Pluteus minutissimus f. major and a holotype of Pluteus granulatus var. tenellus, we synonymize them under P. inflatus. We also increase our knowledge about the morphology and distribution of P. cutefractus.

11.
J Fungi (Basel) ; 8(8)2022 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-35893141

RESUMEN

We studied the taxonomy of Pluteus romellii, and morphologically similar Holarctic species in the /romellii clade of section Celluloderma, using morphological and molecular data (nrITS, TEF1-α). Pluteus romellii is lectotypified and epitypified and accepted as an exclusively Eurasian species. Pluteus lutescens and P. pallescens are considered synonyms of P. romellii. Pluteus fulvibadius is accepted as a related, but separate, North American species. Five species in the /romellii clade are described as new to science: two from North America (P. austrofulvus and P. parvisporus), one from Asia (P. parvicarpus), one from Europe (P. siccus), and one widely distributed across the Holarctic region (P. vellingae). Basidioma size, pileus color, lamellae color, basidiospore size, hymenial cystidia shape and size, habitat and geographical distribution help separate the species described here, but in some instances only molecular data allows for confident identification. The current status of P. californicus, P. melleipes, P. romellii var. luteoalbus, P. splendidus, P. sternbergii and P.sulphureus is discussed.

12.
J Fungi (Basel) ; 8(6)2022 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-35736106

RESUMEN

We studied the taxonomy of Pluteus insidiosus and similar species using morphological and molecular (nrITS, TEF1-α) data, including a detailed study of the type collection of P. insidiosus. Based on our results, we recognize five species in this group: P. insidiosus sensu stricto and four other taxa: P. assimilatus; P. farensis; P. flavostipitatus; and P. pseudoinsidiosus; described here as new. All these taxa are distinct from each other based on molecular data, but some of them are semi-cryptic based on morphology and co-occur in the Palaearctic region. An additional molecular lineage, phylogenetically separates from the P. insidiosus complex, but with many morphological similarities, was recognized in the molecular phylogenies. Based on the revision of available type collections, the name Pluteus reisneri Velen., was adopted for this Clade. Pluteus reisneri was validly published in 1921, but it has barely been used since its original description. A modern epitype, with molecular data, was selected for P. reisneri.

13.
J Stat Softw ; 43(1): 1-29, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-27818617

RESUMEN

The bayesTFR package for R provides a set of functions to produce probabilistic projections of the total fertility rate (TFR) for all countries. In the model, a random walk with drift is used to project the TFR during the fertility transition, using a Bayesian hierarchical model to estimate the parameters of the drift term. The TFR is modeled with a first order autoregressive process during the post-transition phase. The computationally intensive part of the projection model is a Markov chain Monte Carlo algorithm for estimating the parameters of the drift term. This article summarizes the projection model and describes the basic steps to generate probabilistic projections, as well as other functionalities such as projecting aggregate outcomes and dealing with missing values.

14.
Cent Eur J Public Health ; 19(2): 98-101, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21739900

RESUMEN

402 subjects with diabetes mellitus have been vaccinated of the total of 34,000 vaccinees immunized during the study period of 9 and half months. Altogether 229 diabetic patients (56.97%) have been vaccinated'against tick-borne encephalitis (TBE) and 74 (18.4%) against viral hepatitis (41 types A+B, 30 type A, 3 type B). The average age in four most commonly administered vaccines (FSME IMMUN 0.5 ML, Twinrix Adult, Typhim Vi, and Havrix 1440) was 65, 52, 56, and 54 years, respectively. Live attenuated vaccines have been given to 6 patients with diabetes (1.49%)--- 5 travellers to endemic countries received the yellow fever vaccine Stamaril (1 female, 4 male) and one male patient varicella vaccine Varilrix. Among the least common vaccines in diabetic patients were those against invasive pneumococcal and meningococcal infections. Not a single unexpected side effect has been observed following the vaccination procedure in any diabetic patient. Based on the results of this retrospective study we can conclude that vaccination in diabetic patients is free of any ri-k- provided that there are no other contraindications, e.g. allergy to vaccine components or severe acute febrile illness. In the case of unstable glycaemia and significantly impaired immune system due to diabetes mellitus, vaccination with live attenuated vaccines should be carefully considered and measured against the risks of exposure to each and every specific infectious agent. There is no reason to be afraid of vaccination in diabetic patients provided that general contraindications are respected. On the contrary, this risk group can benefit from vaccination more remarkably since it may have some life-saving potential.


Asunto(s)
Diabetes Mellitus/inmunología , Vacunación/estadística & datos numéricos , Vacunas Atenuadas/administración & dosificación , Vacunas Virales/administración & dosificación , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , República Checa , Diabetes Mellitus/tratamiento farmacológico , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Encefalitis Transmitida por Garrapatas/inmunología , Encefalitis Transmitida por Garrapatas/prevención & control , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Vacunación/efectos adversos , Vacunas Atenuadas/efectos adversos , Vacunas Virales/efectos adversos , Adulto Joven
15.
J Fungi (Basel) ; 7(3)2021 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-33800519

RESUMEN

Melanoleuca is one of the taxonomically most complicated genera of Agaricomycetes with several taxonomically lineages. The subgenus Urticocystis of the genus Melanoleuca contains species with either urticoid or absent cheilocystidia. In this paper, three new European species, Melanoleuca galbuserae, Melanoleuca fontenlae, and Melanoleuca acystidiata are described as new to science. Melanoleuca galbuserae, related to Melanoleuca stepposa and Melanoleuca tristis, was discovered in alpine grasslands in North Italy. The type specimens and recent collections of Melanoleuca angelesiana, Melanoleuca castaneofusca, Melanoleuca luteolosperma, Melanoleuca pseudopaedida, and Melanoleuca robertiana were sequenced and morphologically examined. Moreover, the related Melanoleuca microcephala and Melanoleuca paedida were included in morphological examination and DNA sequence analyses. All the species were delimited by macro- and micromorphological characters and the multigene phylogenetic analyses of a combined (ITS, rpb2, and tef1) dataset on the basis of the species tree estimation. In accordance with new molecular and morphological data, we suggest taxonomic reappraisal of M. pseudopaedida and M. robertiana, and M. fontenlae and M. acystidiata are proposed as new species. The differences between the type material of M. angelesiana from the USA and European M. angelesiana specimens are discussed.

16.
J Plant Physiol ; 245: 153091, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31887556

RESUMEN

Potato (Solanum tuberosum) mutant (ST) lacking one isoform of manganese-stabilizing protein (MSPI) of photosystem II exhibited besides spontaneous tuberization also growth changes with strongly impaired root system development. Previous studies revealed marked changes in carbohydrate levels and allocation within ST plant body. To verify causal relationship between changed carbohydrate balance and root growth restriction we engaged dark grown sucrose-supplied root organ-cultures of ST plants to exclude/confirm shoot effects. Unexpectedly, in ST root cultures we observed large alterations in growth and architecture as well as saccharide status similar to those found in the intact plant roots. The gene expression analysis, however, proved PsbO1 transcript (coding MSPI protein) neither in ST nor in WT root-organ cultures. Therefore, the results point to indirect effects of PsbO1 allele absence connected possibly with some epigenetic modulations.


Asunto(s)
Fotosíntesis/genética , Complejo de Proteína del Fotosistema II/metabolismo , Proteínas de Plantas/genética , Raíces de Plantas/metabolismo , Solanum tuberosum/genética , Alelos , Metabolismo de los Hidratos de Carbono/genética , Células Cultivadas , Regulación de la Expresión Génica de las Plantas/genética , Regulación de la Expresión Génica de las Plantas/fisiología , Manganeso/metabolismo , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Mutación , Fotosíntesis/efectos de la radiación , Complejo de Proteína del Fotosistema II/genética , Proteínas de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Tubérculos de la Planta/genética , Tubérculos de la Planta/crecimiento & desarrollo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Solanum tuberosum/crecimiento & desarrollo , Sacarosa/metabolismo
17.
Sci Rep ; 9(1): 8695, 2019 06 18.
Artículo en Inglés | MEDLINE | ID: mdl-31213651

RESUMEN

WEE1 regulates the cell cycle by inactivating cyclin dependent protein kinases (CDKs) via phosphorylation. In yeast and animal cells, CDC25 phosphatase dephosphorylates the CDK releasing cells into mitosis, but in plants, its role is less clear. Expression of fission yeast CDC25 (Spcdc25) in tobacco results in small cell size, premature flowering and increased shoot morphogenetic capacity in culture. When Arath;WEE1 is over-expressed in Arabidopsis, root apical meristem cell size increases, and morphogenetic capacity of cultured hypocotyls is reduced. However expression of Arath;WEE1 in tobacco plants resulted in precocious flowering and increased shoot morphogenesis of stem explants, and in BY2 cultures cell size was reduced. This phenotype is similar to expression of Spcdc25 and is consistent with a dominant negative effect on WEE1 action. Consistent with this putative mechanism, WEE1 protein levels fell and CDKB levels rose prematurely, coinciding with early mitosis. The phenotype is not due to sense-mediated silencing of WEE1, as overall levels of WEE1 transcript were not reduced in BY2 lines expressing Arath;WEE1. However the pattern of native WEE1 transcript accumulation through the cell cycle was altered by Arath;WEE1 expression, suggesting feedback inhibition of native WEE1 transcription.


Asunto(s)
Proteínas de Arabidopsis/genética , Flores/genética , Nicotiana/genética , Brotes de la Planta/genética , Tallos de la Planta/genética , Proteínas Serina-Treonina Quinasas/genética , Proteínas de Arabidopsis/metabolismo , Tamaño de la Célula , Células Cultivadas , Flores/metabolismo , Regulación de la Expresión Génica de las Plantas , Mitosis/genética , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Brotes de la Planta/metabolismo , Tallos de la Planta/metabolismo , Plantas Modificadas Genéticamente , Proteínas Serina-Treonina Quinasas/metabolismo , Nicotiana/citología , Nicotiana/metabolismo
18.
Biophys Chem ; 132(1): 9-17, 2008 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17988785

RESUMEN

Starving cells of Dictyostelium discoideum undergo a developmental cycle where cAMP is autocatalytically produced and relayed from cell to cell, resulting in the propagation of excitation waves over a spatially extended population. Later on the homogeneous cell layer transforms into a pattern of cell streams directed perpendicular to the cAMP waves. Here we chemically influence aggregation competent cells by isopropylidenadenosin (IPA), an adenosine derivative. It can be assumed, that IPA acts via specific adenosine binding sites localized in the cellular membrane. We find, however, that pattern formation and cellular aggregation under the influence of IPA differ considerably compared to experiments with adenosine. In particular, our observations point towards an inhibitory effect on adenylate cyclase (ACA), the key enzyme in the autocatalytic production process of cAMP inside the cell. Our results suggest the existence of a direct coupling (via intracellular affection) or indirect coupling (via inhibition of cAMP binding) of the specific adenosine receptors to the regulatory circuit that controls cyclic intra- and extracellular cAMP concentration.


Asunto(s)
Adenosina/análogos & derivados , Inhibidores de Adenilato Ciclasa , Dictyostelium/efectos de los fármacos , Adenosina/farmacología , Animales , Agregación Celular/efectos de los fármacos , AMP Cíclico/metabolismo , Dictyostelium/citología , Dictyostelium/enzimología
20.
J Plant Physiol ; 214: 53-63, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28441523

RESUMEN

Potato represents the third most important crop worldwide and therefore to understand regulations of tuber onset is crucial from both theoretical and practical points of view. Photosynthesis and related carbohydrate status along with phytohormone balance belong to the essential factors in regulation of plant development including storage organ formation. In our work we used potato (Solanum tuberosum) cv. Lada and its spontaneously tuberizing mutant (ST plants) grown in vitro under low carbohydrate availability (non-inductive conditions). Small plant phenotype and readiness to tuberization of ST plants was, however, not accompanied by lower gibberellins levels, as determined by UHPLC-MS/MS. Therefore, we focused on the other inducing factor, carbohydrate status. Using HPLC, we followed changes in carbohydrate distribution under mixotrophic (2.5% sucrose in medium) and photoautotrophic conditions (no sucrose addition and higher gas and light availability) and observed changes in soluble carbohydrate allocation and starch deposition, favouring basal stem part in mutants. In addition, the determination of tuber-inducing marker gene expressions revealed increased levels of StSP6A in ST leaves. Collectively these data point towards the possibility of two parallel cross-talking pathways (carbohydrate - and gibberellin- dependent ones) with the power of both to outcompete the other one when its signal is for some reason extraordinary strong.


Asunto(s)
Giberelinas/metabolismo , Tubérculos de la Planta/metabolismo , Plantas Modificadas Genéticamente/metabolismo , Solanum tuberosum/metabolismo , Metabolismo de los Hidratos de Carbono/genética , Metabolismo de los Hidratos de Carbono/fisiología , Regulación de la Expresión Génica de las Plantas/genética , Regulación de la Expresión Génica de las Plantas/fisiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Tubérculos de la Planta/genética , Plantas Modificadas Genéticamente/genética , Solanum tuberosum/genética , Espectrometría de Masas en Tándem
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