Joel Domínguez-Viveros

Rumen microorganisms and fermentation

El rumen es un ecosistema complejo donde los nutrientes consumidos por los rumiantes son digeridos mediante un proceso de ferme ntacion realizado por los microorganismos ruminales (bacterias, protozoos y hongos). Dichos microorganismos estan en simbiosis, debido a su capacidad de adaptacion e interaccion, y mientras el rumiante proporciona el ambiente necesario para su establecimiento estos proporcionan energia al animal, la que proviene de los productos finales de la fermentacion. Dentro del rumen, los microorganismos coexisten en un entorno reducido y a un pH cercano a la neutralidad. Estos microorganismos fermentan los sustratos presentes en la dieta del rumiante (azucares, proteinas y lipidos). Sin embargo, el proceso de fermentacion no es 100% eficaz, ya que durante la fermentacion existen perdidas de energia, principalmente en forma de gas metano (CH 4 ), el que representa un problema medioambiental, ya que es un gas de efecto invernadero. Por consiguiente, para mejorar la eficiencia de los sistemas de produccion de rumiantes se han establecido estrategias nutricionales que tienen como objetivo manipular la fermentacion ruminal mediante el uso de aditivos en la dieta, como monensina, sebo, tampones, compuestos de nitrogeno, probioticos, etc. Estos aditivos permiten cambiar el proceso de fermentacion y mejorar la eficiencia animal, ademas disminuyen la perdida de energia. El objetivo de este trabajo es revisar los procesos fermentativos que tienen lugar en el rumen y aplicar los fundamentos de estos en el desarrollo de nuevas estrategias nutricionales que pudieran ayudar a mejorar los procesos de digestion, de manera que se alcance una maxima produccion

Identification of miRNA from Bouteloua gracilis, a drought tolerant grass, by deep sequencing and their in silico analysis

BACKGROUND MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate signal transduction, development, metabolism, and stress responses in plants through post-transcriptional degradation and/or translational repression of target mRNAs. Several studies have addressed the role of miRNAs in model plant species, but miRNA expression and function in economically important forage crops, such as Bouteloua gracilis (Poaceae), a high-quality and drought-resistant grass distributed in semiarid regions of the United States and northern Mexico remain unknown. RESULTS We applied high-throughput sequencing technology and bioinformatics analysis and identified 31 conserved miRNA families and 53 novel putative miRNAs with different abundance of reads in chlorophyllic cell cultures derived from B. gracilis. Some conserved miRNA families were highly abundant and possessed predicted targets involved in metabolism, plant growth and development, and stress responses. We also predicted additional identified novel miRNAs with specific targets, including B. gracilis ESTs, which were detected under drought stress conditions. CONCLUSIONS Here we report 31 conserved miRNA families and 53 putative novel miRNAs in B. gracilis. Our results suggested the presence of regulatory miRNAs involved in modulating physiological and stress responses in this grass species.

Consanguinidad y estimación de parámetros genéticos para morfología del caballo Lusitano en México

The Lusitano horse breeders association in Mexico proposed the development of genetic evaluation for morphological traits (VM: head-neck (CC), withers (CR), chest (PC), back and loin (DR) and croup (GR)) considered in the selection criteria; however, in earlier studies found high levels of inbreeding (F; 6,6 % average), with constant trend. The objectives were to analyze the effects of F through three indicators (IDF: F of animal (IF); average correlation coefficient (CRP); and, change rate of F (DF)) on the average performance, the estimate of heritability (h2) and genetic correlation (rg) for the VM. Including alternately the IDF as covariate of first order were performed four univariate analysis (UNV) for each VM, and four multivariate analyses with the five VM. The covariate solutions of IDF were equal to zero (p>0,05). The h2 with the UNV ranged from 0,08 (DR) to 0,30 (CC), the general average was 0,18. The maximum change with IDF was 0,01. In the MUV, the h2 ranged from 0,11 to 0,35, the general average was 0,198; in the rg, the average without IDF was 0,53, in the interval of 0,01 to 0,97; with IDF the average was 0,59, with estimates above 0,20. The h2 of UNV vs. MUV without IDF were similar. For PC and GR the h2 decreased 0,03 of UNV to MUV with IDF; to contrast of CC, CR y DR with increments of 0,06. Inside MUV, for CC, CR and DR the h2 increased with IDF, with more effect CRP; however, in PC and GR decreased, with more effect of F.