Significant differential gene duplication without ancestral tetraploidy in a genus of mexican fish

A comparison of the protein products of 20–25 structural gene loci among the known species of the goodeid fish genus Skiffia suggests that at least 4 loci (16–20%) have undergone species-specific duplications (or, in 1 case, apparent loss) during the evolution of the genus. The species are clearly diploids, and the data therefore indicate that even a large proportion of differentially duplicated loci within a group of related fish species is not critical evidence of common tetraploid ancestry. Differential duplication of structural gene loci may be an important component of the genetic differences that separate congeneric conventional diploid species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42725/1/18_2005_Article_BF01953797.pd

Effects of stimulus sequence on event-related potentials and reaction time during target detection in Alzheimer's disease

ObjectivesTo examine evoked potentials and behavior as a function of stimulus sequence in an auditory target detection paradigm in Alzheimer's disease (AD).MethodsEvoked potentials and reaction times were collected from 12 healthy elderly controls and 10 patients with mild AD. Subjects pressed a response button to high-pitched target tones (P=0.20) that were randomly intermixed with low-pitched frequent tones. We measured pre-stimulus readiness potential (RP), event-related potentials (P50, N100, P200, N200 and P300), and reaction time as a function of the stimulus sequence.ResultsAD subjects performed at comparable levels of accuracy as controls, but had significantly increased reaction times. Grand averaged potentials in AD showed a significant reduction of the amplitude of the RP, and an increase of P300 latency. Both controls and AD showed speeding of reaction time, increases in RP amplitude, and decreases in P300 latency as a function of the number of frequents preceding the target. Sequential changes of other components (P200 and N200) were found in controls but not AD.ConclusionsAD patients have systematic changes of both RT and certain of the evoked potential components as a function of stimulus sequence. Moment-by-moment changes in target expectancy are largely preserved in AD, even though overall performance and evoked potential measures of expectancy (RP) and stimulus classification (P300 latency) are abnormal

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Genetic algorithms for combinatorial optimization The assembly line balancing problem

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