975 resultados para N-15 Natural-abundance


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Despite the wide use of plant regeneration for biotechnological purposes, the signals that allow cells to become competent to assume different fates remain largely unknown. Here, it is demonstrated that the Regeneration1 (Rg1) allele, a natural genetic variation from the tomato wild relative Solanum peruvianum, increases the capacity to form both roots and shoots in vitro; and that the gibberellin constitutive mutant procera (pro) presented the opposite phenotype, reducing organogenesis on either root-inducing medium (RIM) or shoot-inducing medium (SIM). Mutants showing alterations in the formation of specific organs in vitro were the auxin low-sensitivity diageotropica (dgt), the lateral suppresser (ls), and the KNOX-overexpressing Mouse ears (Me). dgt failed to form roots on RIM, Me increased shoot formation on SIM, and the high capacity for in vitro shoot formation of ls contrasted with its recalcitrance to form axillary meristems. Interestingly, Rg1 rescued the in vitro organ formation capacity in proRg1 and dgtRg1 double mutants and the ex vitro low lateral shoot formation in pro and ls. Such epistatic interactions were also confirmed in gene expression and histological analyses conducted in the single and double mutants. Although Me phenocopied the high shoot formation of Rg1 on SIM, it failed to increase rooting on RIM and to rescue the non-branching phenotype of ls. Taken together, these results suggest REGENERATION1 and the DELLA mutant PROCERA as controlling a common competence to assume distinct cell fates, rather than the specific induction of adventitious roots or shoots, which is controlled by DIAGEOTROPICA and MOUSE EARS, respectively.

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Clinical, epidemiological, and pathological aspects of trypanosomiasis caused by Trypanosoma vivax in calves were reported for the first time in northeast Brazil. Clinical and epidemiological data, packed cell volumes (PCV), and parasitemia were assessed in 150 calves in May 2009 (rainy season-survey 1) and in 153 calves in November 2009 (dry season-survey 2) in three farms (A, B, and C). Prevalence of T. vivax in calves examined in the survey 1 was 63.3%, 65.0%, and 80.0% in farms A, B, and C, respectively. Morbidity varied from 63.3% to 80%, mortality from 15% to 30% and lethality from 23% to 37.5%. In survey 1, for all farms, high parasitemia (from 30.3 to 26.2x10(6) parasites/mL), fever (from 39.8 to 40.3 degrees C), low PCV (from 15.7% to 18.1%), and body score (from 2.5 to 3.5) were detected. Calves showed depression, weight loss, pale mucous membranes, enlarged lymph nodes, edema of the dewlap, cough, coryza, and diarrhea. The animals from farms A and B were treated with diminazene aceturate. Six months after, in survey 2, non-treated calves from farm C showed values for prevalence (81.82), morbidity (81.82), mortality (12.73), and lethality (15.55) similar to those in survey 1 (P>0.05). Also in survey 2, four calves aging merely 1-3 days old presented high parasitemia levels (from 32x10(6) to 74x10(6) parasites/mL), suggesting transplacental transmission. In conclusion, trypanosomiasis by T. vivax constitutes high prevalent disease for calves raised in Brazilian semiarid and may have transplacental transmission.

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INTRODUCTION: This study analyzed the occurrence and the contamination of triatomines by trypanosomatids in Orbignya speciosa (babassu) specimens in the State of Rondônia, Brazil, in two different environments (pasture and woods). METHODS: Capture of triatomines on babassus and microscopic search for trypanosomatids in their digestive tube were carried out. RESULTS: Four hundred ninety-four (494) specimens were captured (Rhodnius prolixus and R.robustus), of which 35.6% of the triatomines were positive for trypanosomatids. CONCLUSIONS: The high index of natural infection along with the abundance of triatomines points out to the necessity to create an epidemiological surveillance system to monitor vector-borne transmission and deepen the studies on the ecology of such vectors in the Amazon.

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This study investigates the species richness and abundance of Drosophila Fallén, 1823 attracted to dung and carrion baited pitfall traps in natural areas with heterogeneous habitats at the Sierra de Minas, Eastern Serranías, southeastern Uruguay. Collecting was carried out on a monthly basis (May 2002 through April 2003). Drosophilids accounted for 0.84% (n = 131) and 3.61% (n = 158) of the Diptera collected from dung (n = 15,630) and carrion (n = 4,382) pitfall traps, respectively. A total of 12 species were identified, 11 of which belong to the subgenus Drosophila (the richest) and one to the subgenus Sophophora Sturtevant, 1939. Over 90% of the Drosophila specimens collected belong to five species of the subgenus Drosophila, namely D. gaucha Jaeger & Salzano, 1953, D. immigrans Sturtevant, 1921, D. mediovittata Frota-Pessoa, 1954, D. aff. nappae Vilela, Valente & Basso-da-Silva, 2004, and D. ornatifrons Duda, 1927. Drosophila cardini Sturtevant, 1916 is recorded for the first time from Uruguay. Drosophila abundance and species richness in the four habitats sampled in the Uruguayan Eastern Serranías, namely woodlands sierra, riparian forest, pine plantation and grazing grassland, were considered to be a function of habitat conservation. Diversity indices were low in all habitats. Different habitats supported particular coprophilous and necrophilous Drosophila species. The woodland sierra represents the most preserved habitat, and contributed with the highest species richness observed. Drosophila ornatifrons was the dominant species, with a restricted habitat distribution. On the other hand, grazed grassland, an environment modified by livestock management, had the lowest species richness: only a few specimens of D. repleta Wollaston, 1858. Regarding species composition, significant differences were found in some pairwise comparisons of groups of Drosophila species that included D. ornatifrons. Fly attraction to dung can be exploited as an alternative and/or complementary collecting method in ecological studies of Drosophila assemblages in natural areas.

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O estudo buscou avaliar diferenças florísticas e estruturais entre os componentes adulto e regenerante de trecho de Floresta Ombrófila Mista em Campos do Jordão, a fim de levantar hipóteses sobre sua trajetória sucessional. Para amostragem do componente adulto (CAP > 15 cm) foram instaladas 50 parcelas permanentes de 10 × 20 m e, em cada uma dessas, cinco subparcelas de 1 × 1 m para amostragem do componente regenerante (h > 30 cm e CAP < 15 cm). No componente adulto foram amostrados 1.770 indivíduos, distribuídos em 58 espécies, 38 gêneros e 26 famílias (H' = 3,08 e J = 0,73). Já entre os regenerantes foram observados 576 indivíduos, 55 espécies, 39 gêneros e 23 famílias (H' = 3,41 e J = 0,84). Constatou-se que são necessárias ações de manejo para a conservação in situ das coníferas locais.

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The Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA) is a long-term (20 years) research effort aimed at the understanding of the functioning of the Amazonian ecosystem. The strong biosphere-atmosphere interaction is a key component of the ecosystem functioning. Two aerosol components are the most visible: The natural biogenic emissions of particles and VOCs, and the biomass burning emissions. Two aerosol and trace gases monitoring stations were operated for 4 years in Manaus and Porto Velho, two very distinct sites, with different land use change. Manaus is a very clean and pristine site and Porto Velho is representative of heavy land use change in Amazonia. Aerosol composition, optical properties, size distribution, vertical profiling and optical depth were measured from 2008 to 2012. Aerosol radiative forcing was calculated over large areas. It was observed that the natural biogenic aerosol has significant absorption properties. Organic aerosol dominates the aerosol mass with 80 to 95%. Light scattering and light absorption shows an increase by factor of 10 from Manaus to Porto Velho. Very few new particle formation events were observed. Strong links between aerosols and VOC emissions were observed. Aerosol radiative forcing in Rondonia shows a high -15 watts/m² during the dry season of 2010, showing the large impacts of aerosol loading in the Amazonian ecosystem. The increase in diffuse radiation changes the forest carbon uptake by 20 to 35%, a large increase in this important ecosystem.

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In recent decades, Oceanography has been using a variety of radionuclides as tracers to understand the ocean dynamic processes, handling and disposal of sediments of seabed. In this context, the determination of natural radionuclides distributions (238U, 232Th and 40K) has been carried out with sediments samples from the shelf and upper slope off Southeast Brazil using a gamma spectrometry technique. The samples were sliced into strata of 2 cm, dried, ground and properly packed to be analysed. The concentration of activities was performed in a hyperpure Ge detector with a resolution of 1,9 keV for the peak of 1332,3 keV of 60Co, model GEM50P by EGG&ORTEC. The study area is located between latitudes 28°40'S and 23°00'S and extends from Cabo Frio (RJ) to Cabo de Santa Marta Grande (SC). The activity concentrations varied from 0,6 to 52,8 BqKg-1 for 238U, from 1,6 to 50,9BqKg-1 for 232Th and from 65,4 to 873,3 BqKg-1 for 40K. From these results it is possible to establish a correlation between the depositional area dynamics and the samples size parameters

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Abstract.- This study assessed the effects of human influences over the abundance and size patterns of five species of gastropods (top-shell snails and limpets) commonly collected in the Canarian Archipelago: ‘burgado hembra’ (Osilinus atrata), ‘burgado macho’ (Osilinus sauciatus), ‘lapa blanca’ (Patella aspera), ‘lapa negra’ (Patella candei crenata) and ‘lapa de sol’ (Patella rustica). We studied patterns of abundance and size of these species across three islands (Lanzarote, La Graciosa and Alegranza) corresponding to three levels of human influence: high, medium and low, respectively; which were quantified through three indicators: human pressure (inhabitants km-1 d-1), accessibility to the coast (km of sealed and unsealed roads), and volumes of capture (kg). The abundances of O. atrata and P. aspera were statistically higher at Alegranza than at La Graciosa and Lanzarote, whereas the density was 10 to 15 times larger at Alegranza for four of the five studied species. Significant differences in the size structure of the species among islands (= levels of human influence) were also observed. Not only all large-sized individuals disappeared at Lanzarote and La Graciosa, yet there was a decrease in numbers for the majority of size ranges. Thought populations of top-shell snails and limpets were affected by natural variability, human activities turned out to be the major driver for the observed differences among islands. These results seriously question the effectiveness of the current shellfish regulations contained in the Regional Fish Law. Resumen.- Este estudio determinó los efectos de la influencia humana sobre la abundancia y la estructura de talla de cinco especies de moluscos gasterópodos comúnmente recolectados en el Archipiélago Canario: el ‘burgado hembra’ (Osilinus atrata), el ‘burgado macho’ (Osilinus sauciatus), la ‘lapa blanca’ (Patella aspera), la ‘lapa negra’ (Patella candei crenata) y la ‘lapa de sol’ (Patella rustica). Se analizaron tres islas (Lanzarote, La Graciosa y Alegranza) correspondientes a tres categorías de influencia humana: alta, media y baja, respectivamente; cuantificadas a través de tres indicadores: la presión humana (hab km-1 d-1), la accesibilidad a la costa (km de red viaria) y los volúmenes de extracción de los recursos (kg). La abundancia de O. atrata y P. aspera fue estadísticamente mayor en Alegranza que en La Graciosa y Lanzarote, mientras que los valores de densidad fueron de 10 a 15 veces superiores en Alegranza para cuatro de las cinco especies estudiadas. Para la estructura de talla, se detectaron notables diferencias entre islas (= niveles de influencia humana). En Lanzarote y La Graciosa no sólo desaparecieron los ejemplares de mayor talla, sino que disminuyeron los ejemplares para la mayoría de rangos de talla. A pesar que la variabilidad natural de las poblaciones de burgados y lapas es alta, la actividad humana parece ser la causa principal de las diferencias observadas entre islas. Estos resultados cuestionan seriamente la efectividad de las normas sobre marisqueo de la actual Ley de Pesca de Canarias.

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[ES]La recarga al acuífero noreste de Gran Canaria ha sido calculada dentro del proyecto REDESAC mediante la realización de un balance diario de agua en el suelo. Para llevarlo a cabo ha sido necesario adaptar los datos de partida existentes referentes a la pluviometría, la evapotranspiración (ET0 y ETP) y los parámetros del suelo. La zona se ha dividido en subzonas según la situación de las estaciones pluviométricas y atendiendo a las características climáticas. Los cálculos realizados mediante la utilización del código Easy-Bal han arrojado una recarga de unos 15±4 hm3/a, lo que supone el 13±4% de la precipitación, la mayor parte de la misma concentrada en las zonas altas y de medianías

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[ES]Se pretende disponer de herramientas que midan calidades ambientales de playas vírgenes de arena, respecto a su uso sustentable como recursos de sol y baño. Estas herramientas son los Análisis DAFO cuantitativos y las Evaluaciones de Impactos heredados. Para rediseñarlas y calibrarlas, se opta por las playas del Parque Natural del Cabo de Gata-Níjar (Almería, España). Se recurre a la formulación de sus patrones de comportamiento morfodinámico para identificar y definir algunos de sus descriptores y factores ambientales del campo en consideración. Las medidas se harían a partir del árbol involucrado de objetivos, de observaciones in situ, de las variables aisladas, y del rescate de muchos descriptores y factores ambientales de las playas urbanas de sol y baño.

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The effector function of natural killer (NK) cells is regulated by activating and inhibitory receptors, termed killer immunoglobulin-like receptors (KIRs). In haploidentical T-cell depleted transplantation the donor/recipient KIR mismatch significantly impacts on NK-mediated tumor cell killing, particularly in acute myeloid leukaemia (AML). Thirty-four high risk AML patients entered a phase I-II study of adoptive NK-cell based immunotherapy and were screened for the availability of one haploidentical KIR ligand mismatched donor. Thirteen of them resulted as having one suitable donor. NK cells were enriched from steady-state leukaphereses by using a double-step immunomagnetic separation system, consisting in depletion of CD3+ T cells followed by positive selection of CD56+ NK cells. CD56+ cells were enriched from 7,70% (1,26-11,70) to 93,50% (66,41-99,20) (median recovery 53,05% (30,97-72,85), median T-depletion 3,03 log (2,15-4,52) viability >92%) and their citotoxic activity was inalterate. All patients (4 progressions, 1 partial remission and 8 complete remissions) received NK cell infusion which was preceeded by immunosuppressive chemotherapy (fludarabine and cyclophosphamide) and followed by interleukin 2 injections. The median number of reinfused NK cells was 2,74x10(e)6/kg(1,11-5,00) and contamining CD3+ T cells were always less than 1x10(e)5/kg. The procedure was well-tolerated and no significant toxicity, including GvHD, related to NK cell infusion was observed. The donor NK cells were demonstrated in 5/10 patients. Among the 8 patients in complete remission 5 patients are stable after 18, 15, 4, 2 months of follow-up. Three other patients relapsed after 2 and 7 months. The patient in partial remission obtained a complete remission, which lasted for 6 months. The 4 patients with active/progressive disease showed the persistence of disease. This clinical observation may be correlated with in vitro studies, indicating that AML cells are capable to induce NK cell apoptosis in a dose-depend manner. In summery, a two-step enrichment of CD56+ NK cells allows the collection of a suitable number of target cells to be used as adoptive immunotherapy in AML patients. Infusion of NK cells is feasible and safe and adoptively transferred NK cells can be detected after infusion.

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Marine soft bottom systems show a high variability across multiple spatial and temporal scales. Both natural and anthropogenic sources of disturbance act together in affecting benthic sedimentary characteristics and species distribution. The description of such spatial variability is required to understand the ecological processes behind them. However, in order to have a better estimate of spatial patterns, methods that take into account the complexity of the sedimentary system are required. This PhD thesis aims to give a significant contribution both in improving the methodological approaches to the study of biological variability in soft bottom habitats and in increasing the knowledge of the effect that different process (both natural and anthropogenic) could have on the benthic communities of a large area in the North Adriatic Sea. Beta diversity is a measure of the variability in species composition, and Whittaker’s index has become the most widely used measure of beta-diversity. However, application of the Whittaker index to soft bottom assemblages of the Adriatic Sea highlighted its sensitivity to rare species (species recorded in a single sample). This over-weighting of rare species induces biased estimates of the heterogeneity, thus it becomes difficult to compare assemblages containing a high proportion of rare species. In benthic communities, the unusual large number of rare species is frequently attributed to a combination of sampling errors and insufficient sampling effort. In order to reduce the influence of rare species on the measure of beta diversity, I have developed an alternative index based on simple probabilistic considerations. It turns out that this probability index is an ordinary Michaelis-Menten transformation of Whittaker's index but behaves more favourably when species heterogeneity increases. The suggested index therefore seems appropriate when comparing patterns of complexity in marine benthic assemblages. Although the new index makes an important contribution to the study of biodiversity in sedimentary environment, it remains to be seen which processes, and at what scales, influence benthic patterns. The ability to predict the effects of ecological phenomena on benthic fauna highly depends on both spatial and temporal scales of variation. Once defined, implicitly or explicitly, these scales influence the questions asked, the methodological approaches and the interpretation of results. Problem often arise when representative samples are not taken and results are over-generalized, as can happen when results from small-scale experiments are used for resource planning and management. Such issues, although globally recognized, are far from been resolved in the North Adriatic Sea. This area is potentially affected by both natural (e.g. river inflow, eutrophication) and anthropogenic (e.g. gas extraction, fish-trawling) sources of disturbance. Although few studies in this area aimed at understanding which of these processes mainly affect macrobenthos, these have been conducted at a small spatial scale, as they were designated to examine local changes in benthic communities or particular species. However, in order to better describe all the putative processes occurring in the entire area, a high sampling effort performed at a large spatial scale is required. The sedimentary environment of the western part of the Adriatic Sea was extensively studied in this thesis. I have described, in detail, spatial patterns both in terms of sedimentary characteristics and macrobenthic organisms and have suggested putative processes (natural or of human origin) that might affect the benthic environment of the entire area. In particular I have examined the effect of off shore gas platforms on benthic diversity and tested their effect over a background of natural spatial variability. The results obtained suggest that natural processes in the North Adriatic such as river outflow and euthrophication show an inter-annual variability that might have important consequences on benthic assemblages, affecting for example their spatial pattern moving away from the coast and along a North to South gradient. Depth-related factors, such as food supply, light, temperature and salinity play an important role in explaining large scale benthic spatial variability (i.e., affecting both the abundance patterns and beta diversity). Nonetheless, more locally, effects probably related to an organic enrichment or pollution from Po river input has been observed. All these processes, together with few human-induced sources of variability (e.g. fishing disturbance), have a higher effect on macrofauna distribution than any effect related to the presence of gas platforms. The main effect of gas platforms is restricted mainly to small spatial scales and related to a change in habitat complexity due to a natural dislodgement or structure cleaning of mussels that colonize their legs. The accumulation of mussels on the sediment reasonably affects benthic infauna composition. All the components of the study presented in this thesis highlight the need to carefully consider methodological aspects related to the study of sedimentary habitats. With particular regards to the North Adriatic Sea, a multi-scale analysis along natural and anthopogenic gradients was useful for detecting the influence of all the processes affecting the sedimentary environment. In the future, applying a similar approach may lead to an unambiguous assessment of the state of the benthic community in the North Adriatic Sea. Such assessment may be useful in understanding if any anthropogenic source of disturbance has a negative effect on the marine environment, and if so, planning sustainable strategies for a proper management of the affected area.

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Within this doctoral thesis, biogenic emissions of several globally relevant halocarbons (methyl chloride, methyl bromide, methyl iodide, dibromomethane, chloroform and bromoform) have been investigated in different environments. An airborne study was focused on the tropical rainforest ecosystem, while shipborne measurements investigated naturally occurring oceanic plankton blooms. Laboratory experiments using dried plant material were made to elucidate abiotic production mechanisms occurring in organic matter. Airborne measurements over the tropical rainforest of Suriname and French Guyana (3 - 6 °N, 51 - 59 °W) revealed net fluxes of 9.5 (± 3.8 2σ) µg m-2 h-1 methyl chloride and 0.35 (± 0.15 2σ) µg m-2 h-1 chloroform emitted in the long dry season (October) 2005. An extrapolation of these numbers to all tropical forests helped to narrow down the range of the recently discovered and poorly quantified methyl chloride source from tropical ecosystems. The value for methyl chloride obtained (1.5 (± 0.6 2σ) Tg yr-1) affirms that the contribution of the tropical forest ecosystem is the major source in the global budget of methyl chloride. The extrapolated global net chloroform flux from tropical forests (56 (± 23 2σ) Gg yr-1) is of minor importance (5 - 10 %) compared to the global sources. A source of methyl bromide from this region could not be verified. The abiotic formation of methyl chloride and methyl bromide from dead plant material was tested in a laboratory study. The release from plant tissue representative of grassland, deciduous forest, agricultural areas and coastal salt marshes (hay, ash, tomato and saltwort) has been monitored. Incubations at different temperatures (25 - 50 °C) revealed significant emissions even at ambient temperature, and that the emissions increased exponentially with temperature. The strength of the emission was found to be additionally dependent on the availability of halide and the methoxyl group within the plant tissue. However, high water content in the plant material was found to inhibit methyl halide emissions. The abiotic nature of the reaction yielding methyl halides was confirmed by its high activation energy calculated via Arrhenius plots. Shipborne measurements of the atmospheric mixing ratios of methyl chloride, methyl bromide, methyl iodide, dibromomethane and bromoform have been conducted along a South Atlantic transect from the 27.01. - 05.02.2007 to characterize halocarbon emissions from a large-scale natural algae bloom encountered off the coast of Argentina. Mixing ratios of methyl chloride and methyl bromide were not significantly affected by the occurrence of the phytoplankton bloom. Emissions of methyl iodide, dibromomethane and bromoform showed pronounced mixing ratio variations, triggered by phytoplankton abundance. Methyl iodide was strongly correlated with dimethyl sulfide throughout the sampled region. A new technique combining satellite derived biomass marker (chlorophyll a) data with back trajectory analysis was successfully used to attribute variations in mixing ratios to air masses, which recently passed over areas of enhanced biological production.

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Different codons encoding the same amino acid are not used equally in protein-coding sequences. In bacteria, there is a bias towards codons with high translation rates. This bias is most pronounced in highly expressed proteins, but a recent study of synthetic GFP-coding sequences did not find a correlation between codon usage and GFP expression, suggesting that such correlation in natural sequences is not a simple property of translational mechanisms. Here, we investigate the effect of evolutionary forces on codon usage. The relation between codon bias and protein abundance is quantitatively analyzed based on the hypothesis that codon bias evolved to ensure the efficient usage of ribosomes, a precious commodity for fast growing cells. An explicit fitness landscape is formulated based on bacterial growth laws to relate protein abundance and ribosomal load. The model leads to a quantitative relation between codon bias and protein abundance, which accounts for a substantial part of the observed bias for E. coli. Moreover, by providing an evolutionary link, the ribosome load model resolves the apparent conflict between the observed relation of protein abundance and codon bias in natural sequences and the lack of such dependence in a synthetic gfp library. Finally, we show that the relation between codon usage and protein abundance can be used to predict protein abundance from genomic sequence data alone without adjustable parameters.