Role of lysine and acidic amino acid residues on the insecticidal activity of Jackbean urease

AbstractCanavalia ensiformis has three isoforms of urease: Jackbean urease (JBU), Jackbean urease II and canatoxin. These isoforms present several biological activities, independent from the enzymatic property, such as entomotoxicity and antifungal properties. The entomotoxic activity is a property of the whole protein, as well as of a 10 kDa peptide released by insect digestive enzymes. Here we have used chemical modification to observe the influence of lysines and acidic residues on JBU enzymatic and insecticidal activities. Chemical modification of lysine residues was performed with dimethylamine–borane complex and formaldehyde, and acidic residues were modified by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and ethylenediamine. Derivatized ureases, called JBU-Lys (lysine-modified) and JBU-Ac (acidic residues-modified), were assayed for their biochemical and insecticidal properties. Neither modification altered significantly the kinetic parameters analyzed, indicating that no residue critical for the enzyme activity was affected and that the modifications did not incur in any significant structural alteration. On the other hand, both modifications reduced the toxic activity of the native protein fed to Dysdercus peruvianus. The changes observed in the entomotoxic property of the derivatized proteins reflect alterations in different steps of JBU's toxicity towards insects. JBU-Ac is not susceptible to hydrolysis by insect digestive enzymes, hence impairing the release of toxic peptide(s), while JBU-Lys is processed as the native protein. On the other hand, the antidiuretic effect of JBU on Rhodnius prolixus is altered in JBU-Lys, but not in JBU-Ac. Altogether, these data emphasize the role of lysine and acidic residues on the insecticidal properties of ureases

Diferenças no processamento proteolítico de urease vegetal entre ninfas e adultos de Dysdercus peruvianus (hemíptera : Pyrrhocoridae)

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The 100,000 most influential scientists rank : the underrepresentation of Brazilian women in academia

Despite the progress observed in recent years, women are still underrepresented in science worldwide, especially at top positions. Many factors contribute to women progressively leaving academia at different stages of their career, including motherhood, harassment and conscious and unconscious discrimination. Implicit bias plays a major negative role in recognition, promotions and career advancement of female scientists. Recently, a rank of the most influential scientists in the world was created based on several metrics, including the number of published papers and citations. Here, we analyzed the representation of Brazilian scientists in this rank, focusing on gender. Female Brazilian scientists are greatly underrepresented in the rank (11% in the Top 100,000; 18% in the Top 2%). Possible reasons for this observed scenario are related to the metrics used to rank scientists, which reproduce and amplify the well-known implicit bias in peer-review and citations. Male scientists have more self-citation than female scientists and positions in the rank varied when self-citations were included, suggesting that self-citation by male scientists increases their visibility. Discussions on the repercussions of such ranks are pivotal to avoid deepening the gender gap in science

Silicones in controlled drug delivery systems

Sistemas de liberação controlada de fármacos oferecem muitas vantagens em relação às formas farmacêuticas convencionais, como a redução na freqüência da dose, melhora na biodisponibilidade, redução dos efeitos colaterais e maior conveniência e cooperação do paciente. A proposta dessas formulações é manter uma concentração apropriada do fármaco no organismo por um longo período de tempo tendo, como ideal, uma formulação que libere o fármaco a uma velocidade constante. Esses sistemas têm explorado as propriedades de barreira e características de degradação de polímeros sintéticos, como silicones, para alcançar uma liberação controlada de agentes bioativos no organismo. O silicone, um polímero inerte e biocompatível, é empregado em sistemas de liberação controlada do tipo implantes, sistemas intravaginais, adesivos transdérmicos, inserções oculares e sistemas de liberação gastrintestinais. O objetivo do presente trabalho é revisar o uso do silicone nestes sistemas, como mecanismo limitante na velocidade de liberação dos fármacos.Controlled drug delivery (CDD) systems offer several advantages over conventional dosage forms, namely, reduce dose frequency, improve bioavailability, decrease the incidence of side effects and improve patient compliance. These systems have exploited the barrier properties and degradation characteristics of synthetic polymers, like silicones, to achieve controlled release of bioactive agents in organism. The silicone, a biocompatible and inert polymer, is used in CDD systems incluiding implants, intravaginal devices, transdermal patches, ocular inserts and controlled peroral delivery systems. The aim of the present article is to review the use of silicone in CDD systems as a rate-controlling device to deliver the drug

Parentalidad y carrera científica : el impacto no es el mismo para todos

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Bias against parents in science hits women harder

Worldwide, parenthood remains a major driver for the reduced participation of women in the job market, where discrimination stems from people’s biases against mothers, based on stereotypes and misconceptions surrounding the vision of motherhood in our society. In academia, parenthood may be perceived as negatively affecting scientists’ commitment and dedication, especially women’s. We conducted a survey amongst Brazilian scientists and found that mothers self-reported a higher prevalence of negative bias in their workplace when compared to fathers. The perception of a negative bias was influenced by gender and career status, but not by race, scientific field or number of children. Regarding intersections, mothers with less than 15 years of hiring reported having suffered a higher rate of negative bias against themselves. We discuss implications of these results and suggest how this negative bias should be addressed in order to promote an equitable environment that does not harm women in science

Ionic liquid-loaded microcapsules doped into dental resin infiltrants

Resin infiltrants have been effectively applied in dentistry to manage non-cavitated carious lesions in proximal dental surfaces. However, the common formulations are composed of inert methacrylate monomers. In this study, we developed a novel resin infiltrant with microcapsules loaded with an ionic liquid (MC-IL), and analyzed the physical properties and cytotoxicity of the dental resin. First, the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI.NTf2) was synthesized. BMI.NTf2 has previously shown antibacterial activity in a dental resin. Then, MC-IL were synthesized by the deposition of a preformed polymer. The MC-IL were analyzed for particle size and de-agglomeration effect via laser diffraction analysis and shape via scan ning electron microscopy (SEM). The infiltrants were formulated, and the MC-IL were incorporated at 2.5%, 5%, and 10 wt%. A group without MC-IL was used as a control. The infiltrants were evaluated for ultimate tensile strength (UTS), contact angle, surface free energy (SFE), and cytotoxicity. The MC-IL showed a mean particle size of 1.64 (±0.08) μm, shriveled aspect, and a de-agglomeration profile suggestive of nanoparticles’ presence in the synthesized powder. There were no differences in UTS among groups (p > 0.05). The incorporation of 10 wt% of MC-IL increased the contact angle (p 0.05). The incorpo ration of microcapsules as a drug-delivery system for ionic liquids may be a promising strategy to improve dental restorative materials