The recordable cerebral activity (readiness-potential, RP) that precedes a freely voluntary, fully endogenous motor act was directly compared with the reportable time (W) for appearance of the subjective experience of 'wanting' or intending to act. The onset of cerebral activity clearly preceded by at least several hundred milliseconds the reported time of conscious intention to act. This relationship held even for those series (with 'type II' RPs) in which subjects reported that all of the 40 self-initiated movements in the series appeared 'spontaneously' and capriciously. Data were obtained in at least 6 different experimental sessions with each of 5 subjects. In series with type II RPs, onset of the main negative shift in each RP preceded the corresponding mean W value by an average of about 350 ms, and by a minimum of about 150 ms. In series with type I RPs, in which an experience of preplanning occurred in some of the 40 self-initiated acts, onset of RP preceded W by an average of about 800 ms (or by 500 ms, taking onset of RP at 90 per cent of its area). Reports of W time depended upon the subject's recall of the spatial 'clock-position' of a revolving spot at the time of his initial awareness of wanting or intending to move. Two different modes of recall produced similar values. Subjects distinguished awareness of wanting to move (W) from awareness of actually moving (M). W times were consistently and substantially negative to, in advance of, mean times reported for M and also those for S, the sensation elicited by a task-related skin stimulus delivered at irregular times that were unknown to the subject. It is concluded that cerebral initiation of a spontaneous, freely voluntary act can begin unconsciously, that is, before there is any (at least recallable) subjective awareness that a 'decision' to act has already been initiated cerebrally. This introduces certain constraints on the potentiality for conscious initiation and control of voluntary acts.

The inverse relationship between serum albumin concentration and its half-life suggested to early workers that albumin would be protected from a catabolic fate by a receptor-mediated mechanism much like that proposed for IgG. We show here that albumin binds FcRn in a pH dependent fashion, that the lifespan of albumin is shortened in FcRn-deficient mice, and that the plasma albumin concentration of FcRn-deficient mice is less than half that of wild-type mice. These results affirm the hypothesis that the major histocompatibility complex–related Fc receptor protects albumin from degradation just as it does IgG, prolonging the half-lives of both.

No abstract

The vast majority of phylogenetic models focus on resolution of gene trees, despite the fact that phylogenies of species in which gene trees are embedded are of primary interest. We analyze a Bayesian model for estimating species trees that accounts for the stochastic variation expected for gene trees from multiple unlinked loci sampled from a single species history after a coalescent process. Application of the model to a 106-gene data set from yeast shows that the set of gene trees recovered by statistically acknowledging the shared but unknown species tree from which gene trees are sampled is much reduced compared with treating the history of each locus independently of an overarching species tree. The analysis also yields a concentrated posterior distribution of the yeast species tree whose mode is congruent with the concatenated gene tree but can do so with less than half the loci required by the concatenation method. Using simulations, we show that, with large numbers of loci, highly resolved species trees can be estimated under conditions in which concatenation of sequence data will positively mislead phylogeny, and when the proportion of gene trees matching the species tree is <10%. However, when gene tree/species tree congruence is high, species trees can be resolved with just two or three loci. These results make accessible an alternative paradigm for combining data in phylogenomics that focuses attention on the singularity of species histories and away from the idiosyncrasies and multiplicities of individual gene histories.coalescent theory ͉ importance sampling ͉ molecular clock ͉ yeast M any biological disciplines have as their focus the phylogenetic relationships of species-species trees. With the advent of large-scale comparative genomic data sets and enhanced computational power, statistical methods such as maximum likelihood and Bayesian phylogenetic inference have provided sophisticated approaches to incorporation of heterogeneous models of sequence evolution in combined multilocus data sets (1-3). These methods have vastly increased the efficiency and statistical power that can be gleaned from DNA sequences and will greatly contribute to the ultimate goal of comprehending the full scope of Darwin's Tree of Life (4). The taxonomic units of the Tree of Life are species composed of large numbers of genes distributed across multiple independently segregating chromosomes and linkage groups. Thus, most phylogenetic studies in fact use methodologies that focus not on estimation of species trees per se but on estimation of gene trees, with the usual assumption being that the gene tree resolved by combining many genes is congruent with the species tree. This assumption will hold widely, except in cases when (i) horizontal gene transfer and other reticulate processes, such as interspecific gene flow, are common; (ii) gene duplication has caused gene lineage splits in the absence of splits in the history of species; and (iii) gene lineages fail to coalesce before divergence of species (looking backward i...