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41.
InNeurospora crassa thenit-2 andnmr-1 (ms-5) loci represent the major control genes encoding regulatory proteins that allow the coordinated expression of various systems involved with the utilization of a secondary nitrogen source. In this paper we examine the effect of thenit-2 andms-5 (nmr-1 locus) mutations on the regulation of the ammonium assimilation enzymes, glutamine synthetase and glutamate dehydrogenase, which are regulated by the products of these genes; however, glutamate synthase is not so regulated. Glutamine synthetase and glutamate dehydrogenase levels are also regulated by the amino nitrogen content. We present evidence that thems-5 andgln r strains, which behave very similarly in their resistance to glutamine repression, are different and map in different loci. 相似文献
42.
43.
Martina Ferraguti Sergio Magallanes Jéssica Jiménez-Peñuela Josué Martínez-de la Puente Luz Garcia-Longoria Jordi Figuerola Jaime Muriel Tamer Albayrak Staffan Bensch Camille Bonneaud Rohan H. Clarke Gábor Á. Czirják Dimitar Dimitrov Kathya Espinoza John G. Ewen Farah Ishtiaq Wendy Flores-Saavedra László Zsolt Garamszegi Olof Hellgren Dita Horakova Kathryn P. Huyvaert Henrik Jensen Asta Križanauskienė Marcos R. Lima Charlene Lujan-Vega Eyðfinn Magnussen Lynn B. Martin Kevin D. Matson Anders Pape Møller Pavel Munclinger Vaidas Palinauskas Péter L. Pap Javier Pérez-Tris Swen C. Renner Robert Ricklefs Sergio Scebba Ravinder N. M. Sehgal Manuel Soler Eszter Szöllősi Gediminas Valkiūnas Helena Westerdahl Pavel Zehtindjiev Alfonso Marzal 《Global Ecology and Biogeography》2023,32(5):809-823
Aim
The increasing spread of vector-borne diseases has resulted in severe health concerns for humans, domestic animals and wildlife, with changes in land use and the introduction of invasive species being among the main possible causes for this increase. We explored several ecological drivers potentially affecting the local prevalence and richness of avian malaria parasite lineages in native and introduced house sparrows (Passer domesticus) populations.Location
Global.Time period
2002–2019.Major taxa studied
Avian Plasmodium parasites in house sparrows.Methods
We analysed data from 2,220 samples from 69 localities across all continents, except Antarctica. The influence of environment (urbanization index and human density), geography (altitude, latitude, hemisphere) and time (bird breeding season and years since introduction) were analysed using generalized additive mixed models (GAMMs) and random forests.Results
Overall, 670 sparrows (30.2%) were infected with 22 Plasmodium lineages. In native populations, parasite prevalence was positively related to urbanization index, with the highest prevalence values in areas with intermediate urbanization levels. Likewise, in introduced populations, prevalence was positively associated with urbanization index; however, higher infection occurred in areas with either extreme high or low levels of urbanization. In introduced populations, the number of parasite lineages increased with altitude and with the years elapsed since the establishment of sparrows in a new locality. Here, after a decline in the number of parasite lineages in the first 30 years, an increase from 40 years onwards was detected.Main conclusions
Urbanization was related to parasite prevalence in both native and introduced bird populations. In invaded areas, altitude and time since bird introduction were related to the number of Plasmodium lineages found to be infecting sparrows. 相似文献44.
Paulino Bambi Alan M. Tonin Renan de Souza Rezende Fernando Carvalho Vieira Fernanda Gabriela Graciano Miranda Luz Boyero José F. Gonçalves Júnior 《Biotropica》2023,55(1):40-52
Riparian forests play an important role in stream ecosystems, as they support biodiversity, reduce water erosion, and provide litter that fuels aquatic biota. However, they are affected by great array of anthropogenic threats (e.g., fire, logging, and organic pollution), which alter species composition and their physical structure. Although forest recovery after disturbance such as logging can take decades, the legacy of forest clear-cut logging on key processes in tropical riparian ecosystems is mostly unknown. Here, we investigated how litter inputs (leaves, twigs, and reproductive parts) and storage, key processes for carbon and nutrient recycling and for forest and stream biota, are influenced by riparian vegetation undergoing succession (after 28 years from logging) through the comparison of reference and logged forest sites in the Cerrado biome. Litterfall was overall similar between forest types, but litterfall of twigs was twofold higher at logged than reference sites. Similarly, litter inputs from the bank to the stream (i.e., lateral inputs) and streambed storage were 50–60% higher at logged than reference sites. The higher litterfall observed in logged forests could be related to higher proportion of tree species that are characteristic of primary and secondary successional stages, including fast-growing and liana species, which often are more productive and common in anthropogenic areas. Our results showed that the legacy impact of clear-cut logging, even if residual woody vegetation is maintained in riparian buffers, can shift the type, quantity, and seasonality of litter subsidies to tropical streams. This knowledge should be considered within the context of management and conservation of communities and ecosystem processes in the forest-stream interfaces. 相似文献
45.
Stella Erdmann Dominic Edelmann Meinhard Kieser 《Biometrical journal. Biometrische Zeitschrift》2023,65(6):2200023
The gold standard for investigating the efficacy of a new therapy is a (pragmatic) randomized controlled trial (RCT). This approach is costly, time-consuming, and not always practicable. At the same time, huge quantities of available patient-level control condition data in analyzable format of (former) RCTs or real-world data (RWD) are neglected. Therefore, alternative study designs are desirable. The design presented here consists of setting up a prediction model for determining treatment effects under the control condition for future patients. When a new treatment is intended to be tested against a control treatment, a single-arm trial for the new therapy is conducted. The treatment effect is then evaluated by comparing the outcomes of the single-arm trial against the predicted outcomes under the control condition. While there are obvious advantages of this design compared to classical RCTs (increased efficiency, lower cost, alleviating participants’ fear of being on control treatment), there are several sources of bias. Our aim is to investigate whether and how such a design—the prediction design—may be used to provide information on treatment effects by leveraging external data sources. For this purpose, we investigated under what assumptions linear prediction models could be used to predict the counterfactual of patients precisely enough to construct a test and an appropriate sample size formula for evaluating the average treatment effect in the population of a new study. A user-friendly R Shiny application (available at: https://web.imbi.uni-heidelberg.de/PredictionDesignR/ ) facilitates the application of the proposed methods, while a real-world application example illustrates them. 相似文献
46.
Diana Villegas-Coronado Jesús Adriana Soto-Guzman Juan Manuel Martínez-Soto Nayelli Guadalupe Teran-Saavedra Ana Maria Guzman-Partida Luz Vazquez-Moreno Ana Gloria Villalba-Villalba Amir Maldonado Irlanda Lagarda-Diaz 《化学与生物多样性》2023,20(7):e202300051
Acute monocytic leukemia is a type of myeloid leukemia that develops in monocytes. The current clinical therapies for leukemia are unsatisfactory due to their side effects and nonspecificity toward target cells. Some lectins display antitumor activity and may specifically recognize cancer cells by binding to carbohydrate structures on their surface. Therefore, this study evaluated the response of the human monocytic leukemia cell lines THP-1 to the Olneya tesota PF2 lectin. The induction of apoptosis and reactive oxygen species production in PF2-treated cells was evaluated by flow cytometry, and the lectin-THP-1 cell interaction and mitochondrial membrane potential were evaluated by confocal fluorescence microscopy. PF2 genotoxicity was evaluated by DNA fragmentation analysis via gel electrophoresis. The results showed that PF2 binds to THP-1 cells, triggers apoptosis and DNA degradation, changes the mitochondrial membrane potential, and increases reactive oxygen species levels in PF2-treated THP-1 cells. These results suggest the potential use of PF2 for developing alternative anticancer treatments with enhanced specificity. 相似文献
47.
Lone Baunsgaard Kees Venema Kristian B. Axelsen José Manuel Villalba Annikki Welling Bernd Wollenweber Michael G. Palmgren 《The Plant journal : for cell and molecular biology》1996,10(3):451-458
Transport across the plasma membrane is driven by an electrochemical gradient of H+ ions generated by the plasma membrane proton pump (H+ -ATPase). Random mutants of Arabidopsis H+ -ATPase AHA1 were isolated by phenotypic selection of growth of transformed yeast cells in the absence of endogenous yeast H+ -ATPase (PMA1). A Trp-874-Leu substitution as well as a Trp-874 to Lys-935 deletion in the hydrophilic C-terminal domain of AHA1 conferred growth of yeast cells devoid of PMA1. A Trp-874-Phe substitution in AHA1 was produced by site-directed mutagenesis. The modified enzymes hydrolyzed ATP at 200–500% of wild-type level, had a sixfold increase in affinity for ATP (from 1.2 to 0.2 mM; pH 7.0), and had the acidic pH optimum shifted towards neutral pH. AHA1 did not contribute significantly to H+ extrusion by transformed yeast cells. The different species of aha1, however, displayed marked differences in initial rates of net H+ extrusion and in their ability to sustain an electrochemical H+ gradient. These results provide evidence that Trp-874 plays an important role in auto-inhibition of the plant H+ -ATPase and may be involved in controlling the degree of coupling between ATP hydrolysis and H+ pumping. Finally, these results demonstrate the usefulness of yeast as a generalized screening tool for isolating regulatory mutants of plants transporters. 相似文献
48.
J. C. Rodríguez-Aguilera F. Navarro A. Arroyo F. J. Alcaín J. M. Villalba P. Navas 《Protoplasma》1995,184(1-4):229-232
Summary Ascorbate is stabilized in the presence of HL-60 cells. Our results showed that cAMP derivatives and agents that increase cAMP stimulate the ability of HL-60 cells to stabilize ascorbate. On the other hand, tunicamycin, a glycosilation-interfering agent, inhibited this ability. The ascorbate stabilization in the presence of HL-60 cells has been questioned as a simple chemical effect. Further properties and controls about the enzymatic nature of this stabilization are described and discussed. This data, together with hormonal regulation, support the hypothesis that an enzymatic redox system located at the plasma membrane is responsible of the extracellular ascorbate stabilization by HL-60 cells.Abbreviations AFR
ascorbate free radicals
- FCS
fetal calf serum
- Sp-cAMPS
Sp-cyclic adenosine monophosphothionate
- Rp-cAMPS
Rp-cyclic adenosine monophosphothionate 相似文献
49.
Primate terminal complement inhibitor homologues of human CD59 总被引:6,自引:0,他引:6
William L. Fodor Scott A. Rollins Stella Bianco-Caron Willis V. Burton Edward R. Guilmette Russell P. Rother George B. Zavoico Stephen P. Squinto 《Immunogenetics》1995,41(1):51-51
The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers L22862 (African green monkey CD59) and L22863 (baboon CD59) 相似文献
50.