Publications by authors named "Sara Rivera"

The predatory firefly is common throughout the Atlantic Forest and has been proposed as a biomonitor due to the species' narrow niche and elevational range. However, the species is only known from adults, and a more effective monitoring of its populations hinges on the lack of knowledge on their immature stages. Recent sampling in ferruginous caves and inserted in other lithologies, on sites in the Atlantic Forest and Cerrado, have led to the capture of firefly larvae later reared to adults in the lab.

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  • Nutrient pollution from nitrogen inputs causes harmful blooms of the cyanobacterium Microcystis, which poses risks to public health and ecosystems.
  • This study explored how different forms of organic nitrogen affect Microcystis growth and toxin production, revealing that the type of nitrogen available significantly influences the associated microbial community and Microcystis' nutrient uptake.
  • Findings indicate that while Microcystis can directly absorb amino acids, the presence of certain bacteria can either compete with or enhance its nitrogen uptake, potentially supporting harmful blooms under low inorganic nitrogen conditions.
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  • Cyanobacterial harmful algal blooms (cyanoHABs) led by Microcystis spp. pose serious health and economic risks due to their production of toxic compounds like microcystins, which impact fishing, tourism, and drinking water safety.
  • The study focused on isolating and sequencing 21 Microcystis cultures from western Lake Erie, revealing substantial genetic diversity and highlighting that only a few strains possess the full set of genes necessary for microcystin production.
  • Results showed that cultures with complete microcystin biosynthesis genes produced high toxin levels, while also identifying diverse bacteria within these cultures, emphasizing their role in bloom dynamics and the potential effects on toxin production and degradation.
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Too hot to handle: The surroundings of magnetic nanoparticles can be heated by applying a magnetic field. Polymer-coated magnetic nanoparticles were functionalized with single-stranded DNA molecules and further hybridized with DNA modified with different fluorophores. By correlating the denaturation profiles of the DNA with the local temperature, temperature gradients for the vicinity of the excited nanoparticles were determined.

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A facile solvothermal route has been developed for the preparation of europium doped gadolinium orthovanadate nanoparticles (~70 nm) with tetragonal structure, based on a homogenous precipitation reaction at 120 °C from rare earth precursors (yttrium nitrate and europium nitrate) and sodium orthovanadate solutions using an ethylene glycol-water mixture as the solvent. The effects of the doping level on the luminescence properties were evaluated in order to find the optimum nanophosphors. These nanocrystals were successfully functionalized with amino (two step process) and carboxylate (one-pot process) groups provided by amino-dextran polymers (AMD) and polyacrylic acid (PAA), respectively.

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Transfer RNA (tRNA) genes and other RNA polymerase III transcription units are dispersed in high copy throughout nuclear genomes, and can antagonize RNA polymerase II transcription in their immediate chromosomal locus. Previous work in Saccharomyces cerevisiae found that this local silencing required subnuclear clustering of the tRNA genes near the nucleolus. Here we show that the silencing also requires nucleosome participation, though the nature of the nucleosome interaction appears distinct from other forms of transcriptional silencing.

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In this study, we show the use of direct external electrical stimulation of a jellyfish luminescent calcium-activated protein, aequorin, expressed in a transgenic yeast strain. Yeast cultures were electrically stimulated through two electrodes coupled to a standard power generator. Even low (1.

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Unlabelled: This study investigated the acoustical and perceptual characteristics of vowels in speech produced during simultaneous communication (SC). Twelve normal hearing, experienced sign language users were recorded under SC and speech alone (SA) conditions speaking a set of sentences containing monosyllabic words designed for measurement of vowel duration, formant frequencies, and fundamental frequency in consonant-vowel-consonant (CVC) syllables and 60 listeners audited the speech samples. Although results indicated longer sentence and vowel durations for SC than SA, the data showed no difference in spectral characteristics of vowels produced during SC versus SA, indicating no degradation of vowel spectrum by rate alteration during SC.

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