The Rt. Honble. John George Lambton, Baron Durham [Material gráfico]

Resumen: Descripción: retrato del Barón de Durham de 3/4 de figura, con el torso de frente y mirando hacia la izqda. Viste elegantemente con capa y cuello de piel

John Deere 6215R, sobresaliente en el análisis de vibraciones

El 16 de marzo tuvimos ocasión de volver a la comarca de la Sagra para trabajar con los técnicos de John Deere en la prueba de campo del modelo 6215R. En este ensayo se ha trabajado con un minichísel de 5,74 m de anchura útil, se ha efectuado un transporte con un remolque cargado con 14.860 kg de cebada y se ha trazado un pequeño recorrido con el apero suspendido, comparando el modo de cambio manual y la gestión automática de la transmisión y comprobando el funcionamiento de la suspensión hidráulica de la cabina HCS Plus

John Deere 8R, directo al mundo digital

El pasado 10 de diciembre volvimos al concesionario John Deere de Olías del Rey (Toledo). En esta ocasión para ensayar un modelo de la nueva serie 8R, el 824R, en el que comprobamos la facilidad de uso, el confort, y la conectividad global (fabricante, concesionario, operador y dueño de la explotación unidos en tiempo real)

Identification of morc (microrchidia), a mutation that results in arrest of spermatogenesis at an early meiotic stage in the mouse

The microrchidia, or morc, autosomal recessive mutation results in the arrest of spermatogenesis early in prophase I of meiosis. The morc mutation arose spontaneously during the development of a mouse strain transgenic for a tyrosinase cDNA construct. Morc −/− males are infertile and have grossly reduced testicular mass, whereas −/− females are normal, indicating that the Morc gene acts specifically during male gametogenesis. Immunofluorescence to synaptonemal complex antigens demonstrated that −/− male germ cells enter meiosis but fail to progress beyond zygotene or leptotene stage. An apoptosis assay revealed massive numbers of cells undergoing apoptosis in testes of −/− mice. No other abnormal phenotype was observed in mutant animals, with the exception of eye pigmentation caused by transgene expression in the retina. Spermatogenesis is normal in +/− males, despite significant transgene expression in germ cells. Genomic analysis of −/− animals indicates the presence of a deletion adjacent to the transgene. Identification of the gene inactivated by the transgene insertion may define a novel biochemical pathway involved in mammalian germ cell development and meiosis.

Spindle Dynamics and the Role of γ-Tubulin in Early Caenorhabditis elegans EmbryosV⃞

γ-Tubulin is a ubiquitous and highly conserved component of centrosomes in eukaryotic cells. Genetic and biochemical studies have demonstrated that γ-tubulin functions as part of a complex to nucleate microtubule polymerization from centrosomes. We show that, as in other organisms, Caenorhabditis elegans γ-tubulin is concentrated in centrosomes. To study centrosome dynamics in embryos, we generated transgenic worms that express GFP::γ-tubulin or GFP::β-tubulin in the maternal germ line and early embryos. Multiphoton microscopy of embryos produced by these worms revealed the time course of daughter centrosome appearance and growth and the differential behavior of centrosomes destined for germ line and somatic blastomeres. To study the role of γ-tubulin in nucleation and organization of spindle microtubules, we used RNA interference (RNAi) to deplete C. elegans embryos of γ-tubulin. γ-Tubulin (RNAi) embryos failed in chromosome segregation, but surprisingly, they contained extensive microtubule arrays. Moderately affected embryos contained bipolar spindles with dense and long astral microtubule arrays but with poorly organized kinetochore and interpolar microtubules. Severely affected embryos contained collapsed spindles with numerous long astral microtubules. Our results suggest that γ-tubulin is not absolutely required for microtubule nucleation in C. elegans but is required for the normal organization and function of kinetochore and interpolar microtubules.