Biology subjects

Harvey, M.

Publications and source records attributed to Harvey, M..

3 recordsLinked to original sources

bioRxiv2018

Basal Forebrain Deep Brain Stimulation Impacts the Regulation of Extracellular Vesicle Related Proteins in the Rat Brain

Extracellular vesicle (EV) signaling has attracted considerable attention in recent years because EVs play a key role in long distance cellular communication functions. EV studies have begun to reveal aspects of physiological and physiopathological regulation in numerous applications, although many areas remain to date largely unexplored. Deep brain stimulation (DBS) has shown remarkable therapeutic benefits of patients with neuropsychiatric disorders, but despite of the long and successful history of use, the mechanisms of action on neural ensemble activity are not yet fully understood. Here we explore how DBS of the basal forebrain impacts EV signaling in the rat brain. We employed differential centrifugations to isolate the EVs prefrontal cortex (PFC), hippocampus and striatum. We then performed quantitative analysis of EV-associated proteins using an MS-based proteomics method. We identified a considerable number of EV-associated proteins are modulated by DBS in three brain regions, some of which have been previously linked with central nervous system disorders. Particularly, neurofilament proteins NFL and NFM were both significantly changed in EVs of PFC, hippocampus and striatum after DBS stimulation compared with controls. The SOD1 protein, associated previously with neurodegenerative diseases, was significantly increased only in PFC. Our study is the first, to our knowledge, to use EV protein analysis to examine DBS effects on brain physiological regulation. Our findings open an entirely new perspective on brain area specific DBS effects.

neuroscience↗

bioRxiv2016

Habitat preference predicts genetic diversity and population divergence in Amazonian birds

The ecological traits of organisms may predict important evolutionary parameters such as genetic diversity, population genetic structure, and demographic history. Making these ecological-evolutionary links is difficult because robust, comparable genetic estimates are required from many species with differing ecologies. In Amazonian birds, differences in habitat preference are an important component of ecological diversity. A subset of Amazonian birds is restricted to forest edge and open forest along floodplains, whereas another subset occurs only in the interior of tall, upland forest. Here, we examine the link between habitat and evolutionary metrics using 20 pairs of closely related and co-distributed bird species in which one member of the pair occurs primarily in forest edge and floodplains, and the other occurs in upland forest interior. We use standardized geographic sampling and genomic data from the same set of 2,416 independent markers to estimate genetic diversity, population structure, and demographic history in each species. We find that species of upland forest have higher genetic diversity, greater divergence across the landscape, more genetically distinct populations, and deeper gene histories than floodplain species. Our results reveal that species ecology in the form of habitat preference is an important predictor of genetic diversity and divergence and suggest that floodplain and upland avifaunas in the Amazon may be on separate evolutionary trajectories and require different conservation strategies.

evolutionary biology↗

bioRxiv2016

A positive association between population genetic differentiation and speciation rates in New World birds

Although an implicit assumption of speciation biology is that population differentiation is an important stage of evolutionary diversification, its true significance remains largely untested. If population differentiation within a species is related to its speciation rate over evolutionary time, the causes of differentiation could also be driving dynamics of organismal diversity across time and space. Alternatively, geographic variants might be short-lived entities with rates of formation that are unlinked to speciation rates, in which case the causes of differentiation would have only ephemeral impacts. Combining population genetics datasets including 17,746 individuals from 176 New World bird species with speciation rates estimated from phylogenetic data, we show that the population differentiation rates within species predict their speciation rates over long timescales. Although relatively little variance in speciation rate is explained by population differentiation rate, the relationship between the two is robust to diverse strategies of sampling and analyzing both population-level and species-level datasets. Population differentiation occurs at least three to five times faster than speciation, suggesting that most populations are ephemeral. Population differentiation and speciation rates are more tightly linked in tropical species than temperate species, consistent with a history of more stable diversification dynamics through time in the Tropics. Overall, our results suggest investigations into the processes responsible for population differentiation can reveal factors that contribute to broad-scale patterns of diversity.

evolutionary biology↗