RESUMO
Abstract A new silver coordination compound [Ag(sac) (pbi)] was synthesized by reaction of silver(I) saccharinate with 2-(2-pyridyl)benzimidazole (pbi) in 64% yield. The characterization was performed by elemental analysis, IR, UV-Visible, XPS, 1H-NMR, and 13C-NMR spectroscopy. According to the results, silver is coordinating through three nitrogen atoms: one from saccharinate and the others from 2-(2-pyridyl) benzimidazole forming with this ligand a five-membered chelate ring.
Resumen Se sintetizó un nuevo compuesto de coordinación de plata, [Ag(sac)(pbi)], por reacción de sacarinato de plata(I) con 2-(2-piridil)bencimidazol (pbi) con un rendimiento de 64%. La caracterización se realizó por análisis elemental, espectroscopia IR, UV-Visible, XPS, 1H-RMN y 13C-RMN. De acuerdo con los resultados obtenidos la plata está coordinada a través de tres átomos de nitrógeno, uno del sacarinato y los dos restantes del 2-(2-piridil)-bencimidazol formando con este ligando un anillo quelato de cinco miembros.
Resumo O presente trabalho compreende a síntese de um novo composto de coordenação de prata, [Ag(sac)(pbi)], por reação de sacarinato de prata(I) com 2-(2-piridil)benzimidazol (pbi) com 64% de rendimento. A caracterização foi realizada por análise elementar, espectroscopia IV, UV-Visível, XPS, 1H-RMN e 13C-RMN. De acordo com os resultados obtidos, a prata é coordenada através de três átomos de nitrogênio, um do sacarinato e os outros dois do 2-(2-piridil)benzimidazol que formam com este ligando um anel de quelato de cinco membros.
RESUMO
KEY MESSAGE : The study determined the tolerance of Aloe vera to high temperature, focusing on the expression of hsp70 , hsp100 and ubiquitin genes. These were highly expressed in plants acclimated at 35 °C prior to a heat shock of 45 °C. Aloe barbadensis Miller (Aloe vera), a CAM plant, was introduced into Chile in the semiarid IV and III Regions, which has summer diurnal temperature fluctuations of 25 to 40 °C and annual precipitation of 40 mm (dry years) to 170 mm (rainy years). The aim of this study was to investigate how Aloe vera responds to water and heat stress, focusing on the expression of heat shock genes (hsp70, hsp100) and ubiquitin, which not studied before in Aloe vera. The LT(50) of Aloe vera was determined as 53.2 °C. To study gene expression by semi-quantitative RT-PCR, primers were designed against conserved regions of these genes. Sequencing the cDNA fragments for hsp70 and ubiquitin showed a high identity, over 95 %, with the genes from cereals. The protein sequence of hsp70 deduced from the sequence of the cDNA encloses partial domains for binding ATP and the substrate. The protein sequence of ubiquitin deduced from the cDNA encloses a domain for interaction with the enzymes E2, UCH and CUE. The expression increased with temperature and water deficit. Hsp70 expression at 40-45 °C increased 50 % over the controls, while the expression increased by 150 % over the controls under a water deficit of 50 % FC. The expression of all three genes was also studied under 2 h of acclimation at 35 or 40 °C prior to a heat shock at 45 °C. Under these conditions, the plants showed greater expression of all genes than when they were subjected to direct heat stress.