Molecular and biochemical characterization of extracellular tannin acyl hydrolase activity from a Mexican isolate of Aspergillus niger

"Microbial tannase, a hydrolysable tannin-degrading enzyme, is extensively used in manufacture of instant tea, beer, wine, and gallic acid. Aspergillus niger strain, obtained from a Mexican tannery wastewaters rich in gallic acid [Quebracho Phenolics-rich Tannery Wastewaters, (QPTW)], displayed a good growth and tannase activity in a minimal medium added with 1% (w/v) QPTW (Kr= 0.451 mm.h-1). Using PCR and RACE 3´ and 5´methodologies, a complete cDNA of a tannase was cloned from this isolate.Nucleotide sequence of complete cDNA was of 4690 bp with a complete ORF of 1833 bp encoding 611 amino acids. Transcriptionalinduction was observed in mineral medium added with carbon sources as tannic acid alone (1 and 10 g/l), as well as mix of glucose(1 and 10 g/l) and tannic acid (1 g/l) in the media. However, neither glucose (1 and 10 g/l) and sucrose (1 and 10 g/l) nor (+)-catechin(1 and 10 g/l) as sole carbon sources displayed gene induction in in vitro assays. A. niger-GTO is a new strain with interesting characteristics for industrial tannase production purposes.

HLA-C genotype and TCR vβ expression analysis in Mexican patients with Psoriasis

"Genetic background and T-cell expansion have been associated as the most important factors for psoriasis susceptibility in the Caucasian population. This study was performed to identify the T cell receptor Vβ repertoire and HLA-Cw genotype in two Mexican groups with severe chronic plaque-type psoriasis. HLA-C typing was performed to detect the allele pattern associated with the disease by sequence-specific primer-polymerase chain reaction. In parallel, RT-PCR and Western blot were used for the identification of the TCR Vβ repertoire. We found a wide variety of HLA-C alleles displayed with a preference to HLA-Cw *07 as the most representative allele in the group of patients. TCR Vβ-2 and Vβ-7 clone-type frequencies were statistically significant (p of 0.0280) when compared to other TCR Vβ expressed in the two groups. We found notable differences both in the HLA-C genotype and TCR Vβ repertoire in the groups of patients studied. Since Mexican individuals are genetically different from the Caucasian population, we suggest that due to these differences the susceptibility to disease and activation of T-cells for a proper immune response may be affected.

Perfil de expresión a nivel transcripcional en cáncer cervicouterino y su relación con la vía de señalización Notch

Tesis (Doctorado en Ciencias en Biología Molecular)"El cáncer cervicouterino (CaCU) es la primer causa de mortalidad en mujeres en México, y la segunda a nivel mundial. Entre las causas principales para el desarrollo de cáncer se encuentran la presencia de mutaciones, deleciones, translocaciones e inserciones virales en los genes. El Virus de Papiloma Humano (VPH) está asociado en el 99% de los casos diagnosticados, aunque no es el único factor determinante. El sistema de señalización Notch está implicado en eventos celulares esenciales como el desarrollo, diferenciación, proliferación y apoptosis, esta vía está involucrada en varias de enfermedades humanas principalmente en cáncer, se ha reportado que la desregulación de los genes Notch, sin embargo el mecanismo exacto de participación de esta vía para la generación de neoplasia no es claro, se desconoce aún la existencia de componentes que puedan interactuar con la vía y que además pueden estar involucrados en la diferenciación tumoral. Se ha demostrado que dependiendo del nivel de expresión y del contexto celular, los receptores de membrana Notch contribuyen claramente en la resistencia a apoptosis en células tumorales. En este trabajo, se evaluó el perfil del transcriptoma de CaCU para la identificación de los genes que se inducen y/o reprimen en presencia de fenotipo neoplásico y la posible participación que tiene en la regulación de la vía Notch. El estudio se realizó en biopsias de pacientes con cáncer cervicouterino en los diferentes estadios de la enfermedad (NIC I, NIC II, NIC III y cáncer Invasor).""The cervical cancer (CC) is the first cause of death in women in Mexico and the second worldwide. 99% of the cases diagnosed with CC are affected by the Human Papilloma Virus (HPV), however other factors are involved. In the last years, there are reports about over expression of the Notch signaling pathway elements in a great variety of a human tumors including CC. However, the exact mechanism of the participation of this pathway is not clear. It is unknown yet the existence of elements that could interact with this pathway and that possibly involved in the tumor differentiation. Among the main causes for the development of CC are the presence of mutations, deletions, translocations, and insertions of viral genes. The Notch signaling pathway is involved in essential cellular events such as development, differentiation, proliferation, and apoptosis. In addition, this pathway has been involved in several human diseases, mainly in cancer. It has been demonstrated that depending of the expression level and the cellular context, the Notch receptors contribute clearly in the resistances to apoptosis in tumor cells. In this work, we study the transcriptome profile in CC for identification of genes that are induced and /or repressed in the present of a neoplastic phenotype and the possible participation in the Notch via. In this study we used biopsies from patients with CC in the different stages of the disease (CIN I, CIN II, CIN III, and invasive cancer).

Identification of differential expressed transcripts in cervical cancer of Mexican patients

"The aim of this study was to identify the gene expression profile in biopsies of patients with cervical intraepithelial neoplasia (CIN) 1, CIN 2, CIN 3, and microinvasive cancer by suppression subtractive hybridization and Southern blotting. After analyzing 1,800 cDNA clones, we found 198 upregulated genes, 166 downregulated, and no significant change of gene expression in 86 clones (p = 0.005). These results were validated by Northern blot analysis (p = 0.0001) in the identification of 28 overexpressed and 7 downregulated transcripts. We observed a set of genes related to the Notch signaling pathway that may be involved in the transformation of cervical cells and in the development to malignancy. The differentially expressed genes may provide useful information about the molecular mechanisms involved in human cervical carcinoma and as diagnostic markers.

Identification of calcium stress induced genes in amaranth leaves through suppression subtractive hybridization

"Calcium (Ca2+) is a critical ion for the growth and development of plants and plays an important role in signal transduction pathways in response to biotic and abiotic stresses. We investigated the Ca2+ stress responsive-genes in amaranth leaves by using the suppression subtractive hybridization technique. Screening of the libraries generated 420 up-regulated transcripts and 199 down-regulated transcripts. The differentially expressed transcripts were associated with general stress response, transcription factors, gene regulation, signal transduction, and some other with unknown function. Selected genes were used to study their differential regulation by sqRT-PCR. Among the up-regulated transcripts, a fragment containing the motif of C3HC4-type RING-Zinc family was further characterized. The ORF of amaranth zinc finger protein (AhZnf) has a closer relationship with its ortholog from Ricinus communis while is distantly related to the Arabidopsis thaliana C3HC4-type ortholog. We have identified a novel putative zinc finger protein along with other novel proteins such as the wall associated kinase, phosphoinositide binding protein, and rhomboid protease involved in response to Ca2+ stress in amaranth leaves.