Stimulation of human neutrophil phagocytosis of Candida albicans by a beta-glucan synthase inhibitor, cilofungin.

The effect of a lipopeptide antifungal agent, cilofungin, on serum opsonization and phagocytosis of Candida albicans yeast phase cells in human neutrophil monolayer assays was investigated. Simultaneous addition of fungicidal concentrations of cilofungin did not enhance or inhibit phagocytosis of C. albicans. Pretreatment of Candida blastospores with cilofungin in the absence of serum complement for 1 h did not affect phagocytosis. However, pretreatment of blastospores with cilofungin and complement promoted a significant increase in ingestion. Pretreatment of neutrophils with cilofungin in serum-free media did not affect neutrophil viability. In contrast, pre-exposure of neutrophils to cilofungin in the presence of complement inhibited ingestion of blastospores.     

Point–count method for estimating rock ptarmigan spring density in the Pyrenean chain

This paper describes a census technique that gives estimates of rock ptarmigan cocks’ number per unit area during the breeding season. This method originated from the need for an effective technique for estimating bird densities in mountainous and inaccessible zones like the Pyrenean chain. The bird census was carried out using a point–count method, which is recommended for uneven areas. To maximize sampling efficiency, we established sampling points at <500-m distances, in order to detect a maximum of calling birds within the sample areas. Birds localized at distances >250 m were excluded. We postulate that all birds are recorded in a 250-m radius around the observer. We carried out counts of calling rock ptarmigan cocks in the border between the Principality of Andorra and Ariège Department, France, from April to June during three consecutive years (2005–2007). The estimated spring density of 10.4 cocks per 100 ha was higher than densities reported in literature, in other parts of the Pyrénées and the Alps. Our study provides a useful reference for future monitoring of this species in its mountainous distribution range.     

Evaluating the role of inbreeding depression in heterozygosity‐fitness correlations: how useful are tests for identity disequilibrium?

Heterozygosity‐fitness correlations (HFCs) have been observed for several decades, but their causes are often elusive. Tests for identity disequilibrium (ID, correlated heterozygosity between loci) are commonly used to determine if inbreeding depression is a possible cause of HFCs. We used computer simulations to determine how often ID is detected when HFCs are caused by inbreeding depression. We also used ID in conjunction with HFCs to estimate the proportion of variation (r²) in fitness explained by the individual inbreeding coefficient (F). ID was not detected in a large proportion of populations with statistically significant HFCs (sample size = 120 individuals) unless the variance of F was high (σ²(F) ≥ 0.005) or many loci were used (100 microsatellites or 1000 SNPs). For example, with 25 microsatellites, ID was not detected in 49% of populations when HFCs were caused by six lethal equivalents and σ²(F) was typical of vertebrate populations (σ²(F) ≈ 0.002). Estimates of r² between survival and F based on ID and HFCs were imprecise unless ID was strong and highly statistically significant (P ≈ 0.01). These results suggest that failing to detect ID in HFC studies should not be taken as evidence that inbreeding depression is absent. The number of markers necessary to simultaneously detect HFC and ID depends strongly on σ²(F). Thus the mating system and demography of populations, which influence σ²(F), should be considered when designing HFC studies. ID should be used in conjunction with HFCs to estimate the correlation between fitness and F, because HFCs alone reveal little about the strength of inbreeding depression.     

Distribution of Daily Breathing Rates For Use in California's Air Toxics Hot Spots Program Risk Assessments

Data were combined from a study measuring breathing rates at various activities and two activity pattern studies to generate breathing rate distributions for children and adults. The children and adult breathing rate distributions were combined using a Monte Carlo technique to generate a breathing rate distribution for a lifetime spanning ages 0 to 70. The children's breathing rate distribution has a mean, standard deviation, median and 95^th percentile of 452, 67.7, 441, and 581 L/kg-day, respectively. The adult breathing rate distribution has a mean, standard deviation, median and 95^th percentile of 232, 64.6, 209, and 381 L/kg-day, respectively. The simulated 70-year distribution has a mean, standard deviation, median and 95^th percentile of 271, 57.9, 253, and 393 L/kg-day, respectively. The adult breathing rate distribution is based on 24-hour recall activity data that would not necessarily capture average activity patterns and therefore breathing rates. We utilized the human energy expenditure literature to validate the breathing rate distribution. We conclude that the breathing rate distribution is reasonable for chronic long-term risk assessment in California's Air Toxics Hot Spots program.     

Structural and chemical characterization of isolated centrosomes

A procedure adapted from that described by Mitchison and Kirschner [Nature 312:232-237, 1984] was used to isolate centrosomes from human lymphoid cells. High yields of homogeneous centrosomes (60% of the theoretical total, assuming one centrosome per cell) were obtained. Centrosomes were isolated as pairs of centrioles, plus their associated pericentriolar material. Ultrastructural investigation revealed: 1) a link between both centrioles in a centrosome formed by the gathering in of a unique bundle of thin filaments surrounding each centriole; 2) a stereotypic organization of the pericentriolar material, including a rim of constant width at the proximal end of each centriole and a disc of nine satellite arms organized according to a ninefold symmetry at the distal end and; 3) an axial hub in the lumen of each centriole at the distal end surrounded by some ill-defined material. The total protein content was 2 to 3 X 10(-2) pg per isolated centrosome, a figure that suggests that the preparations were close to homogeneity. The protein composition was complex but specific, showing proteins ranging from 180 to 300 kD, one prominent band at 130 kD, and a group of proteins between 50 and 65 kD. Actin was also present in centrosome preparations. Functional studies demonstrated that the isolated centrosomes were competent to nucleate microtubules in vitro from purified tubulin in conditions in which spontaneous assembly could not occur. They were also very effective at inducing cleavage when microinjected into unfertilized Xenopus eggs.