18 research outputs found
Differential Regulation of the Variations Induced by Environmental Richness in Adult Neurogenesis as a Function of Time: A Dual Birthdating Analysis
Adult hippocampal neurogenesis (AHN) augments after environmental enrichment (EE) and it has been related to some of the anxiolytic, antidepressant and neuroprotective effects of EE. Indeed, it has been suggested that EE specifically modulates hippocampal neurogenic cell populations over the course of time. Here we have used dual-birthdating to study two subpopulations of newborn neuron in mice (Mus musculus): those born at the beginning and at the end of enrichment. In this way, we demonstrate that while short-term cell survival is upregulated after an initial 1 week period of enrichment in 2 month old female mice, after long-term enrichment (2 months) neither cell proliferation nor the survival of the younger newly born cell populations are distinguishable from that observed in non-enriched control mice. In addition, we show that the survival of older newborn neurons alone (i.e. those born at the beginning of the enrichment) is higher than in controls, due to the significantly lower levels of cell death. Indeed, these parameters are rapidly adjusted to the sudden cessation of the EE conditions. These findings suggest both an early selective, long-lasting effect of EE on the neurons born in the initial stages of enrichment, and a quick response when the environment again becomes impoverished. Therefore, EE induces differential effects on distinct subpopulations of newborn neurons depending on the age of the immature cells and on the duration of the EE itself. The interaction of these two parameters constitutes a new, specific regulation of these neurogenic populations that might account for the long-term enrichment's behavioral effects
Mifepristone Prevents Stress-Induced Apoptosis in Newborn Neurons and Increases AMPA Receptor Expression in the Dentate Gyrus of C57/BL6 Mice
Chronic stress produces sustained elevation of corticosteroid levels, which is why it is considered one of the most potent negative regulators of adult hippocampal neurogenesis (AHN). Several mood disorders are accompanied by elevated glucocorticoid levels and have been linked to alterations in AHN, such as major depression (MD). Nevertheless, the mechanism by which acute stress affects the maturation of neural precursors in the dentate gyrus is poorly understood. We analyzed the survival and differentiation of 1 to 8 week-old cells in the dentate gyrus of female C57/BL6 mice following exposure to an acute stressor (the Porsolt or forced swimming test). Furthermore, we evaluated the effects of the glucocorticoid receptor (GR) antagonist mifepristone on the cell death induced by the Porsolt test. Forced swimming induced selective apoptotic cell death in 1 week-old cells, an effect that was abolished by pretreatment with mifepristone. Independent of its antagonism of GR, mifepristone also induced an increase in the percentage of 1 week-old cells that were AMPA+. We propose that the induction of AMPA receptor expression in immature cells may mediate the neuroprotective effects of mifepristone, in line with the proposed antidepressant effects of AMPA receptor potentiators
Speciation and ecological success in dimly lit waters: horizontal gene transfer in a green sulfur bacteria bloom unveiled by metagenomic assembly
11 páginas, 6 figuras.A natural planktonic bloom of a brown-pigmented photosynthetic green sulfur bacteria (GSB) from the
disphotic zone of karstic Lake Banyoles (NE Spain) was studied as a natural enrichment culture from
which a nearly complete genome was obtained after metagenomic assembly. We showed in situ a case
where horizontal gene transfer (HGT) explained the ecological success of a natural population unveiling
ecosystem-specific adaptations. The uncultured brown-pigmented GSB was 99.7% identical in the 16S
rRNA gene sequence to its green-pigmented cultured counterpart Chlorobium luteolum DSM 273T.
Several differences were detected for ferrous iron acquisition potential, ATP synthesis and gas vesicle
formation, although the most striking trait was related to pigment biosynthesis strategy. Chl. luteolum
DSM 273T synthesizes bacteriochlorophyll (BChl) c, whereas Chl. luteolum CIII incorporated by HGT a
18-kbp cluster with the genes needed for BChl e and specific carotenoids biosynthesis that provided
ecophysiological advantages to successfully colonize the dimly lit waters. We also genomically
characterized what we believe to be the first described GSB phage, which based on the metagenomic
coverage was likely in an active state of lytic infection. Overall, we observed spread HGT and we
unveiled clear evidence for virus-mediated HGT in a natural population of photosynthetic GSB.This research was funded by grant DARKNESS CGL2012-
32747 from the Spanish Office of Science (MINECO) to
EOC and by the Global Ocean Sampling Project supported
by the Beyster Family Foundation Fund of the San Diego
Foundation and the Life Technology Foundation (to JCVI).
Work on BChl e biosynthesis and the genomics of GSB in
the laboratory of DAB was supported by the Division of
Chemical Sciences, Geosciences, and Biosciences, Office
of Basic Energy Sciences of the U.S. Department of Energy
through Grant DE-FG02-94ER20137.Peer reviewe
Gender bias in academia: a lifetime problem that needs solutions
Despite increased awareness of the lack of gender equity in academia and a growing number of initiatives
to address issues of diversity, change is slow and inequalities remain. A major source of inequity is gender
bias, which has a substantial negative impact on the careers, work-life balance, and mental health of
underrepresented groups in science. Here, we argue that gender bias is not a single problem but manifests
as a collection of distinct issues that impact researchers' lives. We disentangle these facets and propose
concrete solutions that can be adopted by individuals, academic institutions, and society