A central question is how much sequence data is required to reconstruct
a tree accurately? The answer depends on the lengths of the branches (edges) of the tree, with very short and very long edges requiring long sequences for accurate tree inference, particularly when these branch lengths are arranged in certain ways. For four-taxon trees, the sequence length question has been investigated for the case of a rapid speciation CHIR98014 molecular weight event in the distant past. Here, we generalize results from this earlier study, and show that the same sequence length requirement holds even when the speciation event is recent, provided that at least one of the four taxa is distantly related to the others. However, this equivalence disappears if a molecular clock applies, since the length of the long outgroup edge becomes largely irrelevant in the estimation of the tree topology for a recent divergence. We also discuss briefly some extensions of these results to models in which substitution rates vary across sites and to settings where more than four taxa are involved. (C) 2012 Elsevier Ltd. All rights reserved.”
“Although errant saccadic eye movements may mark genetic factors in schizophrenia, little is known about abnormal brain activity that precedes saccades in
individuals with genetic liability for schizophrenia. We investigated electrophysiological activity preceding prosaccades and antisaccades in schizophrenia patients, first-degree biological relatives of schizophrenia patients, and control subjects. Prior to antisaccades, patients had reduced potentials over lateral prefrontal cortex. Smaller selleck products potentials
were associated with worse antisaccade performance. Relatives also exhibited reduced pre-saccadic potentials over lateral frontal cortex but additionally had reduced potentials over parietal cortex. Both patients and relatives tended toward increased activity over orbital frontal cortex prior to saccades. Results are consistent with lateral prefrontal dysfunction marking genetic liability for schizophrenia and underlying deficient saccadic control.”
“The initiation of chromosomal replication is strictly controlled during the cell cycle. Its frequency needs to be well-matched to the proliferation Pyruvate dehydrogenase rate. In many bacteria, DnaA is the critical mediator in the regulation of replication initiation. In this work, the initiation probability is deduced based on the distribution of DnaA boxes at oriC in Escherichia coli. Taking into account more details, we develop a dynamic model to describe the oscillation of DnaA accompanied with the cell cycles. Our simulations show that the regulation of DnaA couples chromosomal replication to cell growth. We also discuss effects of other factors on DnaA oscillation. We propose that RNA polymerase is one of the candidates for harmonizing chromosomal replication and cell growth by adjusting dnaA transcriptional activity. (C) 2012 Elsevier Ltd. All rights reserved.