Testing the accuracy of methods for reconstructing ancestral states of continuous characters.

Many methods are available for estimating ancestral values of continuous characteristics, but little is known about how well these methods perform. Here we compare six methods: linear parsimony, squared-change parsimony, one-parameter maximum likelihood (Brownian motion), two-parameter maximum likelihood (Ornstein-Uhlenbeck process), and independent comparisons with and without branch-length information. We apply these methods to data from 20 morphospecies of Pleistocene planktic Foraminifera in order to estimate ancestral size and shape variables, and compare these estimates with measurements on fossils close to the phylogenetic position of 13 ancestors. No method produced accurate estimates for any variable: estimates were consistently less good as predictors of the observed values than were the averages of the observed values. The two-parameter maximum-likelihood model consistently produces the most accurate size estimates overall. Estimation of ancestral sizes is confounded by an evolutionary trend towards increasing size. Shape showed no trend but was still estimated very poorly: we consider possible reasons. We discuss the implications of our results for the use of estimates of ancestral characteristics.     

Influence of arm position on measurement of blood pressure.

A series of measurements of blood pressure in normotensive and hypertensive subjects showed that measurements made with a sphygmomanometer with the arm dependent by the side were consistently higher than those made with the arm horizontal at heart level. The mean difference in a group of 90 hypertensive outpatients was 11/12 mm Hg. Failure to appreciate the importance of arm position may lead to erroneous measurements of blood pressure. This has important implications for clinical practice and research.     

Functional analysis of tryptophans alpha 62 and beta 120 on HLA-DM.

In the endocytic pathway of antigen-presenting cells, HLA-DM catalyzes the exchange between class II-associated invariant chain peptide (CLIP) and antigenic peptides onto major histocompatibility complex class II molecules. At low pH of lysosomal compartments, both HLA-DM and HLA-DR undergo conformational changes, and it was recently postulated that two partially exposed tryptophans on HLA-DM might be involved in the interaction between the two molecules. To define contact regions on HLA-DM, we have conducted site-directed mutagenesis on those two hydrophobic residues. The HLA-DM alphaW62A,betaW120A (DM(W62A/W120A)) double mutant was expressed in HLA-DR(+) HeLa cells expressing invariant chain, and the activity of this DM molecule was assessed. Flow cytometry analysis of cell surface DR-CLIP complexes revealed that DM(W62A/W120A) removes CLIP as efficiently as its wild-type counterpart. DM(W62A/W120A) was found in the endocytic pathway by immunofluorescence, and DM-DR complexes were immunoprecipitated from these cells at pH 5. Finally, mutations alphaW62A and betaW120A on HLA-DM did not affect the association with HLA-DO. The complex egresses the endoplasmic reticulum and accumulates in endocytic vesicles. Moreover, DO and DM(W62A/)W120A were co-immunoprecipitated at pH 7. We conclude that the alpha62 and beta120 tryptophan residues are not required for the activity of DM, nor are they directly implicated in the interaction with DR or DO.     

Genome Sequence of Staphylococcus epidermidis Strain AU12-03, Isolated from an Intravascular Catheter

In recent years, Staphylococcus epidermidis has become a major nosocomial pathogen and the most common cause of intravascular catheter-related bacteremia, which can increase morbidity and mortality and significantly affect patient recovery. We report a draft genome sequence of Staphylococcus epidermidis AU12-03, isolated from an intravascular catheter tip.     

Phagocytosis is coupled to the formation of phagosome-associated podosomes and a transient disruption of podosomes in human macrophages

Phagocytosis consists in ingestion and digestion of large particles, a process strictly dependent on actin re-organization. Using synchronized phagocytosis of IgG-coated latex beads (IgG-LB), zymosan or serum opsonized-zymosan, we report the formation of actin structures on both phagocytic cups and closed phagosomes in human macrophages. Their lifespan, size, protein composition and organization are similar to podosomes. Thus, we called these actin structures phagosome-associated podosomes (PAPs). Concomitantly to the formation of PAPs, a transient disruption of podosomes occurred at the ventral face of macrophages. Similarly to podosomes, which are targeted by vesicles containing proteases, the presence of PAPs correlated with the maturation of phagosomes into phagolysosomes. The ingestion of LB without IgG did not trigger PAPs formation, did not lead to podosome disruption and maturation to phagolysosomes, suggesting that these events are linked together. Although similar to podosomes, we found that PAPs differed by being resistant to the Arp2/3 inhibitor CK666. Thus, we describe a podosome subtype which forms on phagosomes where it probably serves several tasks of this multifunctional structure.     

Prenatal detection of a fetus hemizygous for the fragile X-chromosome

Summary A male fetus of a pregnancy known to be at risk for X-linked mental retardation with fragile site Xq27 was found to be affected by demonstrating the marker X-chromosome in five of 180 (2.8%) of metaphases derived from amniocytes cultured in medium 199. The results were confirmed in fetal lymphocytes (25 of 86 metaphases, i.e. 29%), and fetal fibroblasts (five of 100 metaphases when cultured in medium 199, and 14 of 100 after exposure to methotrexate for 43 h).This work was supported in part by a research grant from the Deutsche Forschungsgemeinschaft     

Predator detection and avoidance by starlings under differing scenarios of predation risk

Practically all animals must find food while avoiding predators.An individual's perception of predation risk may depend on manyfactors, such as distance to refuge and group size, but it isunclear whether individuals respond to different factors ina similar manner. We tested whether flocks of foraging starlingsresponded in the same way to an increased perception of predationrisk by assessing three factors: (1) neighbor distances, (2)habitat obstruction, and (3) recent exposure to a predator.We found that in all three scenarios of increased risk, starlingsreduced their interscan intervals (food-searching bouts), whichincreased the frequency of their vigilance periods. We thenexamined how one of these factors, habitat obstruction, affectedescape speed by simulating an attack with a model predator.Starlings were slower to respond in visually obstructed habitats(long grass swards) and slower when they had their head downin obstructed habitats than when they had their head down inopen habitats. In addition, reaction times were quicker whenstarlings could employ their peripheral fields of vision. Ourresults demonstrate that different sources of increased riskcan generate similar behavioral responses within a species.The degree of visibility in the physical and social environmentaffects both the actual and perceived risk of predation.     

Abortion is incommensurable with fetal alcohol syndrome

A recent article argued for the immorality of abortion regardless of personhood status by comparing the impairment caused by fetal alcohol syndrome to the impairment caused by abortion. I argue that two of the premises in this argument fail and that, as such, one cannot reasonably attribute moral harms to abortion on the basis of the moral harms caused by fetal alcohol syndrome. The impairment argument relies on an inconsistent instantiation, which undermines the claim that personhood is irrelevant, and it does not fulfill its own ceteris paribus clause, which demands that no additional benefit be gained from abortion that would not be gained from causing fetal alcohol syndrome.