Several methods for the rapid determination of the degree of acetylation of chitin and related polymers have been evaluated, including the use of the infrared and the mass spectra.Chitin and chitosan have characteristic degradation temperatures and it is possible to determine the acetylation degree by the use of empirical correlations based on the weight losses associated with the main decomposition peaks.
Authors:S. Mestnik, J. Mengatti, W. Nieto, S. Yanagawa, L. Sumiya, C. Silva and J. Osso
These studies had the purpose of establishing the optimal conditions for the production of123I through the124Te (p, 2n)123I reaction, using the CV-28 Cyclotron (Emax=24 MeV for protons) at IPEN-CNEN/SP. Two different targets (TeO2 and TeO2+2% Al2O3) were irradiated in order to check their physical resistance against beam current (up to 12 A) and length of irradiation (10 min — 2h), and to evaluate the recovery of the radioiodine produced, by a dry distillation process with a high frequency induction furnace. Later on, enriched124TeO2 (96.2%) targets were irradiated, and123I was produced routinely with a production yield of (3. 31±0.07) mCi/Ah, 1.7% of124I at EOB and radiochemically pure.
Authors:J.L. Zárate-Castrejón, C.L. Aguirre-Mancilla, E. Solís-Moya, J.E. Ruiz-Nieto, J.C. Raya-Pérez, J.G. Ramírez-Pimentel and V. Montero-Tavera
Yellow rust is a wheat disease caused by Puccinia striiformis, this pathogen causes economic losses in susceptible materials, which represent up to 70% of wheat varieties. Currently, the incorporation of genetic resistance through molecular tools, is a process used in the generation of new varieties resistant to this pathogen. A strategy employed to identify genes involved in the resistance to yellow rust is to screen differential EST obtained by suppressive subtractive hybridization. In this research, cDNA was extracted from healthy and inoculated plants from the resistant line V-26 from INIFAP. A set of 200 differentially expressed EST were cloned and sequenced, and 31 of them were selected for expression profile analysis by RT-PCR; additionally, with the aim of validate RT-PCR results, five genes were selected for RT-qPCR analysis in genotypes inoculated by P. striiformis. The results showed high levels of expression of selected genes in genotypes classified as resistant in the field conditions (21, 143, 230, 242, 261 and 277), while in the susceptible genotype 16, few genes were induced by the rust. Expression profiles confirmed significant differences between resistant and susceptible lines.