The putative eukaryotic translation initiation factor 5A (eIF5A) is a highly conserved protein among archaea and eukaryotes that has recently been implicated in the elongation step of translation. eIF5A undergoes an essential and conserved posttranslational modification at a specific lysine to generate the residue hypusine. The enzymes deoxyhypusine synthase (Dys1) and deoxyhypusine hydroxylase (Lia1) catalyze this two-step modification process. Although several Saccharomyces cerevisiae eIF5A mutants have importantly contributed to the study of eIF5A function, no conditional mutant of Dys1 has been described so far. In this study, we generated and characterized the dys1-1 mutant, which showed a strong depletion of mutated Dys1 protein, resulting in more than 2-fold decrease in hypusine levels relative to the wild type. The dys1-1 mutant demonstrated a defect in total protein synthesis, a defect in polysome profile indicative of a translation elongation defect and a reduced association of eIF5A with polysomes. The growth phenotype of dys1-1 mutant is severe, growing only in the presence of 1 M sorbitol, an osmotic stabilizer. Although this phenotype is characteristic of Pkc1 cell wall integrity mutants, the sorbitol requirement from dys1-1 is not associated with cell lysis. We observed that the dys1-1 genetically interacts with the sole yeast protein kinase C (Pkc1) and Asc1, a component of the 40S ribosomal subunit. The dys1-1 mutant was synthetically lethal in combination with asc1Δ and overexpression of TIF51A (eIF5A) or DYS1 is toxic for an asc1Δ strain. Moreover, eIF5A is more associated with translating ribosomes in the absence of Asc1 in the cell. Finally, analysis of the sensitivity to cell wall-perturbing compounds revealed a more similar behavior of the dys1-1 and asc1Δ mutants in comparison with the pkc1Δ mutant. These data suggest a correlated role for eIF5A and Asc1 in coordinating the translational control of a subset of mRNAs associated with cell integrity.
Binders based on mixtures of polymers and waxes are suitable both for solvent
combined with thermal extraction, as well as for pure thermal debinding. The recently developed
plasma-assisted debinding and sintering (PADS) process has been targeted, for historical reasons,
on a wax-polymer system, appropriated for solvent combined with thermal extraction processes.
This paper shows experimental results related to the debinding rate of parts produced by metal
powder injection molding using the recently developed Plasma Assisted Debinding process.
Influence of temperature and the ratio of cathodic area on the mass loss were studied.
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O objetivo deste trabalho foi a avaliação da cinética de adsorção do corante azul de metileno utilizando carvão ativado impregnado com óxido de grafeno. Realizou-se a síntese do óxido de grafeno pelo método Hummers usando o grafite de pilhas zincocarbono exauridas e a impregnação do óxido de grafeno no carvão ativado por evaporação/calcinação. Foram realizados ensaios cinéticos de adsorção em batelada, com pH inicial 5, concentração inicial de corante de 100 mg L-1, agitação constante, temperatura ambiente e amostragem de 5 à 360 min. Pela análise dos dados cinéticos, verificou-se tempo de equilíbrio para o carvão ativado e o carvão ativado impregnado com óxido de grafeno de 240 e 90 min, respectivamente. Reportam-se alterações nas etapas de transferência de massa em decorrência da impregnação do óxido de grafeno destacando-se ausência da difusão intrapartícula nos microporos e indicativo da etapa limitante para este adsorvente ser a difusão intrapartícula na superfície externa. As alterações no adsorvente, apesar de não aumentarem a eficiência global de adsorção do corante, conferiram maior velocidade ao processo. Estes resultados sugerem que o carvão ativado com óxido de grafeno apresenta potencial de emprego na remoção de corantes.
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