The behavior of sex chromosomes in two human X-autosome translocations: failure of extensive X-inactivation spreading

Two patients, one adult male and one infant girl, bearing different X-autosome translocations, were studied with cytogenetical, ultrastructural and chromosome-painting techniques. The adult male, is a carrier of a reciprocal, balanced translocation involving the X and #2 chromosomes: 46,Y,t(X;2) (q13;p21). This man showed infertility with spermatogenesis arrest at the spermatocyte stage. Synaptonemal complex analysis at pachytene showed the quadrivalent structure and the putative breakage points. Sex-chromatin condensation did not spread towards the autosomal regions of the quadrivalent. The female infant showed diminished body growth and multiple somatic anomalies. She is a 45,Xp-,t(X;21)(p11;p13) carrier, an unbalanced translocation involving chromosomes X and #21, which leads to a monosomy of almost all Xp. The translocated #21 is practically complete, and its centromere is the active one in the rearranged product. The analysis of interphase nuclei with the X-centromere probe shows that the Xq region of the rearranged chromosome is the late -replicating and inactive element. However, X-inactivation does not spread to the attached #21, as shown by the R-banding pattern. Thus, both in the male adult and in the female infant there is a barrier to the spreading effect of X-chromosome inactivation, which is probably due to different mechanisms.

Efecto tóxico del óxido de etileno en individuos expuestos / Toxic effect of the ethylene oxide in exposed individuals

El óxido de etileno es un potente inductor de daño al material genético ensayado en sistemas tales como vegetales, Drosophila, rata y líneas celulares humanas. Al ser usado como esterilizante en instrumental de cirugía, se realiza el estudio del personal expuesto al mismo, detectándose un aumento significativo en la frecuencia de aberraciones cromosómicas hepático en los mencionados individuos

Accion clastogenica de un compuesto antraquinonico en linfocitos humanos. / Clastogenic action of an anthraquinone compound in human lymphocytes

Algunos autores han senalado una accion mutagenica para los compuestos antraquinonicos en sistemas microbianos, ya sea en forma directa o por activacion metabolica por sistema microsomal. Los compuestos mencionados tienen una amplia difusion como colarantes alimenticios, cosmeticos, farmacos y laxantes. En el presente trabajo se realizo un estudio in vitro del efecto clastogenico de un derivado antraquinonico sintetico, la l-8 Dihidroxiantraquinona y el solvente en el que se solubiliza la droga, el Dimetilsulfoxido, en cultivo de linfocitos de sangre periferica humanos Los resultados obtenidos permiten concluir que la droga ensayada presenta accion clastogenica en el sistema de ensayo aqui utilizad