Physiological effects on demography: a long-term experimental study of testosterone's effects on fitness.

Understanding physiological and behavioral mechanisms underlying the diversity of observed life-history strategies is challenging because of difficulties in obtaining long-term measures of fitness and in relating fitness to these mechanisms. We evaluated effects of experimentally elevated testosterone on male fitness in a population of dark-eyed juncos studied over nine breeding seasons using a demographic modeling approach. Elevated levels of testosterone decreased survival rates but increased success of producing extra-pair offspring. Higher overall fitness for testosterone-treated males was unexpected and led us to consider indirect effects of testosterone on offspring and females. Nest success was similar for testosterone-treated and control males, but testosterone-treated males produced smaller offspring, and smaller offspring had lower postfledging survival. Older, more experienced females preferred to mate with older males and realized higher reproductive success when they did so. Treatment of young males increased their ability to attract older females yet resulted in poor reproductive performance. The higher fitness of testosterone-treated males in the absence of a comparable natural phenotype suggests that the natural phenotype may be constrained. If this phenotype were to arise, the negative social effects on offspring and mates suggest that these effects might prevent high-testosterone phenotypes from spreading in the population.

Hemiplegic mutations in AraC protein.

We have isolated mutations in AraC protein that specifically block either induction or repression at the ara pBAD promoter. These hemiplegic mutations identify amino acid residues that, correspondingly, are involved only in the induction or only in the repression activities of the protein. Residues key only for induction are 13, 15, and 18, which are located in the N-terminal arm of AraC, and residues 80 and 82 which lie in the arabinose-binding pocket of the protein's sugar-binding and dimerization domain. Alteration of residues 157, 244 and 257 can leave the protein able to activate transcription but not able to repress transcription. The behavior of the mutant proteins is consistent with the light switch mechanism for AraC action in which the presence of arabinose pulls the N-terminal arms of the protein off the DNA-binding domains, thereby freeing them to assume a direct-repeat orientation, bind to adjacent direct-repeat DNA half-sites, and activate transcription.

Enhanced recovery of solavetivone from Agrobacterium transformed root cultures of Hyoscyamus muticus using integrated product extraction.

The integrated recovery of solavetivone from fungus elicited "hairy root" cultures of Hyoscyamus muticus is examined using volatile organic solvents and solid-phase adsorbents in an external loop extraction configuration. Hexane and pentane are shown to be toxic when added directly to the culture; however, growth of roots is not inhibited when cultures are exposed to media saturated with these hydrocarbons. Solid-phase neutral adsorbents, XAD-7 and XAD-16, display higher capacity and better solavetivone partitioning capability than the hydrocarbons; however, their selectivity for the sesquiterpene solavetivone is poor in comparison with hexane. In both cases, the integration of product recovery through extraction resulted in a doubling of product formation by alleviating feedback repression. Implications of these results to the recovery of secondary metabolites from plant root cultures are discussed. .

Social well-being of institutionalized elderly persons.

This article describes the development of a scale, the Social Well-Being Scale, to measure the extent to which institutionalized older persons perceive their social needs as being met. For persons over sixty-five years of age, the scale score is not affected by age or sex, but it does distinguish them by race, health, and type of living arrangement. Further, the Social Well-Being Scale predicts the level of psychological well-being.

Physical health status as a consequence of health practices.

The relationship between health practices and physical health status was examined in a sample of 542 adults. A sub-sample of these individuals were also studied prospectively. Strong relationships were found in the cross-sectional data. "Good" health practices were correlated with higher health status. The analysis of the prospective data collected 18 months after the first interview also revealed a strong relationship between previous health practices and subsequent physical health status. The relationship still obtains when previous health status is controlled.

Racial differences in blood pressure levels of adolescents.

Although essential hypertension is more prevalent among Black adults than White adults, results of an extensive high school blood pressure screening program reveal that this relationship does not obtain among adolescents. In fact, the blood pressure levels of White youths equal or exceed that of Black youths. This race effect still exists when age, sex, weight, and socioeconomic status are controlled.