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.     

Expression of multidrug resistance (mdr) gene(s) in primary lymphoid organs of chicken immune system during embryonic development

The presence of a multidrug resistance (MDR) related protein, P-170, in normal and pathological lymphoid cells has been described. The present report evaluates the expression of themdr 1 gene by using the reverse Polymerase Chain Reaction (PCR) on cells obtained from the thymus and bursa of chicken embryos starting from day 12 until hatching. Results show that the thymic cells are positive from day 12 to the end of the observation period. In contrast,mdr mRNA was detected in the bursa from day 14 to day 17 of embryonic life. Possible relationships between the expression ofmdr and the development of T and B lymphocytes are discussed.     

Regional changes of acetylcholine and choline acetylase activity in the guinea-pig's brain after scopolamine

Riassunto La scopolamina riduce la acetilcolina totale nella corteccia cerebrale, bulbo olfattorio, nucleo caudato, ma non nel talamo e cervelletto. La attività colinacetilasica aumenta nelle zone dove si manifesta la riduzione di neurormone. Ciò suggerisce che la scopolamina stimoli soprattutto strutture colinergiche telencefaliche.