Plasma F2-isoprostane level and cognitive function over eight years in non-demented older adults: Findings from the Health ABC Study

F2-isoprostanes (F2-IsoP) are reportedly increased in dementia patients, and are considered a reliable biomarker of oxidation. However, few studies have examined the predictive value of peripheral F2-IsoP levels in non-demented older adults. This study assesses the association between plasma F2-IsoP and change in cognitive function in non-demented elderly over eight years. Plasma F2-IsoP was measured by gas chromatography-mass spectrometry in a biracial cohort of 726 elderly men and women. Digit Symbol Substitution test and the Modified Mini-Mental State Exam were administered over time. No association was found between F2-IsoP tertile and baseline or change (slope) in cognitive function over eight years. Plasma F2-IsoP is not a valuable biomarker in predicting cognitive change over years in non-demented older adults.     

hsp26 of Saccharomyces cerevisiae is related to the superfamily of small heat shock proteins but is without a demonstrable function.

Analysis of the cloned gene confirms that hsp26 of Saccharomyces cerevisiae is a member of the small heat shock protein superfamily. Previous mutational analysis failed to demonstrate any function for the protein. Further experiments presented here demonstrate that hsp26 has no obvious regulatory role and no major effect on thermotolerance. It is possible that the small heat shock protein genes originated as primitive viral or selfish DNA elements.     

Biodiversity mitigates trade-offs among species functional traits underpinning multiple ecosystem services

Biodiversity loss and its effects on humanity is of major global concern. While a growing body of literature confirms positive relationships between biodiversity and multiple ecological functions, the links between biodiversity, ecological functions and multiple ecosystem services is yet unclear. Studies of biodiversity–functionality relationships are mainly based on computer simulations or controlled field experiments using only few species. Here, we use a trait-based approach to integrate plant functions into an ecosystem service assessment to address impacts of restoration on species-rich grasslands over time. We found trade-offs among functions and services when analysing contributions from individual species. At the community level, these trade-offs disappeared for almost all services with time since restoration as an effect of increased species diversity and more evenly distributed species. Restoration to enhance biodiversity also in species-rich communities is therefore essential to secure higher functional redundancy towards disturbances and sustainable provision of multiple ecosystem services over time.     

CellProfiler Analyst: data exploration and analysis software for complex image-based screens

Background  

Image-based screens can produce hundreds of measured features for each of hundreds of millions of individual cells in a single experiment.     

Testosterone changes during the period of adolescence in male rhesus monkeys (Macaca mulatta)

Testosterone levels of 59 male rhesus monkeys were monitored over a period of 5 years. Longitudinal comparisons revealed consistent rises in mid-morning levels of circulating hormone in successive years from age 2.5 to 6.5 years of age, whereas cross-sectional comparisons failed to detect significant differences among the older subjects. The first mid-morning hormonal elevation could be detected in some males as young as 2.5 years of age, whereas other males showed no detectable rises until age 5.5 years. Males showing first rises at later ages did not show hormonal levels consistently below age peers who had shown earlier rises. Extreme month-to-month variability and a failure to manifest the seasonal normal curve of fully adult males was characteristic of younger males, but some of these males, nonetheless, proved capable of fertilizing females. Although hormonal and agonistic dominance measures failed to show consistent correlations, the alpha male in an age cohort significantly more often had the highest testosterone levels. These data are used to argue that adolescence is a process that takes place over several years and that classification of adolescent animals as adults, based on a single criterion like fertility, has confounded many prior studies involving cross taxa comparisons as well as developmental variables.     

Cooperative kinetics of both Hsp104 ATPase domains and interdomain communication revealed by AAA sensor-1 mutants.

AAA proteins share a conserved active site for ATP hydrolysis and regulate many cellular processes. AAA proteins are oligomeric and often have multiple ATPase domains per monomer, which is suggestive of complex allosteric kinetics of ATP hydrolysis. Here, using wild-type Hsp104 in the hexameric state, we demonstrate that its two AAA modules (NBD1 and NBD2) have very different catalytic activities, but each displays cooperative kinetics of hydrolysis. Using mutations in the AAA sensor-1 motif of NBD1 and NBD2 that reduce the rate of ATP hydrolysis without affecting nucleotide binding, we also examine the consequences of keeping each site in the ATP-bound state. In vitro, reducing k(cat) at NBD2 significantly alters the steady-state kinetic behavior of NBD1. Thus, Hsp104 exhibits allosteric communication between the two sites in addition to homotypic cooperativity at both NBD1 and NBD2. In vivo, each sensor-1 mutation causes a loss-of-function phenotype in two assays of Hsp104 function (thermotolerance and yeast prion propagation), demonstrating the importance of ATP hydrolysis as distinct from ATP binding at each site for Hsp104 function.