Presence of the functional CASPASE-12 allele in Indian subpopulations.

Most humans lack a functional CASP12 gene, with the nonfunctional variant (CASP12p1), found in 100% of the Caucasian and east Asian population, and in approximately 80% of people of African descent. However, 20% of Africans carry an intact allele of CASP12, which produces a full-length pro-enzyme and increases the risk of sepsis. We examined CASP12 allele distribution in persons from central and southern Asia and found that CASP12 was significantly present in members of the Dravidian language group, particularly in persons from the Indian state of Tamil Nadu.

A possible mechanism for maintenance of the deleterious allele of human CASPASE-12.

In humans, a functional CASPASE-12 (CASP12) gene has been identified only in persons of African heritage and has been suggested to play a regulatory role in response to bacterial pathogens and in promoting and increased susceptibility to sepsis. The existence of a gene whose effect is deleterious, and which has been the subject of extensive negative selection in the rest of the human population, implies the simultaneous presence of some selective benefit for persons having CASP12. Given the importance of inflammatory immune responses in controlling the initial stages of infection, and the role that CASP12 plays in down-regulating inflammation, we hypothesize that pathogens which exploit the inflammatory response are restrained by an active CASP12 gene product.

Physics of RecA-mediated homologous recognition.

To accomplish its DNA strand exchange activities, the Escherichia coli protein RecA polymerizes onto DNA to form a stiff helical nucleoprotein filament within which the DNA is extended by 50%. Homology search and recognition occurs between ssDNA within the filament and an external dsDNA molecule. We show that stretching the internal DNA greatly enhances homology recognition by increasing the probability that the homologous regions of a stretched DNA molecule and a parallel, unstretched DNA molecule will be "in register" at some position.

RecA force generation by hydrolysis waves.

We present a simple theory of the dynamics of force generation by RecA during homologous strand exchange and a continuous, deterministic mathematical model of the proposed process. Calculations show that force generation is possible in this model for certain reasonable values of the parameters. We predict the shape of the force-velocity curve for the Holliday junction, which exhibits a distinctive kink at large retarding force, and suggest experiments which should distinguish between the proposed model and other models in the literature.

Glucose effectiveness is the major determinant of intravenous glucose tolerance in the rat.

To determine the importance of insulin for glucose disposal during an intravenous glucose tolerance test in rats, experiments were performed in four cohorts of conscious unrestrained rats fasted overnight. In cohorts 1-3, a bolus of tracer ([3-3H]glucose, 50 microCi) was given alone, with glucose (0.3 g/kg) to induce an endogenous insulin response (approximately 1,100 pmol/l), or with exogenous insulin to give physiological (1,700 pmol/l) or supraphysiological (12,000 pmol/l) plasma levels.