Catálogo de publicaciones - revistas

<jats:p>Female chimpanzees often forage alone and do not display obvious linear dominance hierarchies; consequently, it has been suggested that dominance is not of great importance to them. However, with the use of data from a 35-year field study of chimpanzees, high-ranking females were shown to have significantly higher infant survival, faster maturing daughters, and more rapid production of young. Given the foraging behavior of chimpanzees, high rank probably influences reproductive success by helping females establish and maintain access to good foraging areas rather than by sparing them stress from aggression.</jats:p>

<jats:p> Most somatic cells die after a finite number of cell divisions, a phenomenon described as senescence. The p21 <jats:sup> <jats:italic>CIP1/WAF1</jats:italic> </jats:sup> gene encodes an inhibitor of cyclin-dependent kinases. Inactivation of p21 by two sequential rounds of targeted homologous recombination was sufficient to bypass senescence in normal diploid human fibroblasts. At the checkpoint between the prereplicative phase of growth and the phase of chromosome replication, cells lacking p21 failed to arrest the cell cycle in response to DNA damage, but their apoptotic response and genomic stability were unaltered. These results establish the feasibility of using gene targeting for genetic studies of normal human cells. </jats:p>

<jats:p> Naturally occuring polymorphisms in behavior are difficult to map genetically and thus are refractory to molecular characterization. An exception is the <jats:italic>foraging</jats:italic> gene ( <jats:italic>for</jats:italic> ), a gene that has two naturally occurring variants in <jats:italic>Drosophila melanogaster</jats:italic> food-search behavior: rover and sitter. Molecular mapping placed <jats:italic>for</jats:italic> mutations in the <jats:italic>dg2</jats:italic> gene, which encodes a cyclic guanosine monophosphate (cGMP)–dependent protein kinase (PKG). Rovers had higher PKG activity than sitters, and transgenic sitters expressing a <jats:italic>dg2</jats:italic> complementary DNA from rover showed transformation of behavior to rover. Thus, PKG levels affected food-search behavior, and natural variation in PKG activity accounted for a behavioral polymorphism. </jats:p>