Alloantigen-specific suppressor t cells can also suppress the in vivo immune response to unrelated alloantigens

Delayed-type hypersensitivity (DTH) to both major histocompatibility complex (H-2) and non-H-2-coded antigens can be induced by subcutaneous immunization with allogeneic lymphoid cells in the mouse. While subcutaneous immunization with allogeneic cells preferentially induces DTH reactivity, intravenous immunization, especially with irradiated allogeneic cells, induces a state of suppression. Suppression is manifest both in direct host-versus-graft (HvG) assays and under graft-versus-host (GvH) conditions, where spleen cells of suppressed mice are used to reconstitute irradiated allogeneic hosts. The suppression is mediated by T cells. We have now studied the specificity of the suppressive effect by subcutaneous immunization of 'suppressed' mice with a combination of alloantigens comprising the antigen(s) used to induce the suppressor T cells as well as unrelated alloantigens. We report here that reaction against the third party alloantigens was effectively suppressed, provided these antigens were presented in combination with the antigen(s) that had induced the suppressor T cells. Both sets of alloantigens do not need to be physically associated.     

Chromosome replication in cells of a continuous line derived fromAedes albopictus (Skuse) larvae

Resumen El análisis del cuadro de duplicación cromosómica en una linea celular derivada del mosquitoAedes albopictus (Skuse) reveló un período G2 de 3 horas y la presencia de varias areas de duplicación tardía. La mayor parte de estas aread correspondieron a la heterocromatina constitutiva. Sin embargo, la porción distal de ambos brazos en los pares 2 y 3 mostraron duplicación tardía no asociada con la heterocromatina constitutiva. Se sugiere que estas regiones corresponden al a heterocromatina facultative.     

Cytogenetics of South American akodont rodents (Cricetidae). V. Segregation of chromosome No. 1 polymorphism inAkodon molinae

Summary Akodon molinae is polymorphic with 2n=42, 43, 44, where the metacentric autosome No. 1 is homologous to 2 acrocentrics 1a and 1b. Matings between 2n=43 heterozygotes 1/1a, 1b gave a surplus of 1/1 offspring, a moderate reduction of heterozygous and a strong reduction of homozygous 1a, 1b/1a, 1b offspring. The latter type also has a highly reduced fertility.This work was supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas, the Comisión de Investigaciones Científicas de la Provincia de Buenos Aires and the Organización de Estados Americanos.     

浅谈流体在流管出口下游形成“缩脉”的物理实质

一般流体,在流出管口后均有形成“缩脉”的现象.该文就流体在流出管口后,形成“缩脉”的物理实质进行了定性的分析,将其归结为在流管出口附近,流体受管口发出的扰动波的影响,而形成“缩脉”.