143 research outputs found
Proposed Role for COUP-TFII in Regulating Fetal Leydig Cell Steroidogenesis, Perturbation of Which Leads to Masculinization Disorders in Rodents
Reproductive disorders that are common/increasing in prevalence in human males may arise because of deficient androgen production/action during a fetal âmasculinization programming windowâ. We identify a potentially important role for Chicken Ovalbumin Upstream Promoter-Transcription Factor II (COUP-TFII) in Leydig cell (LC) steroidogenesis that may partly explain this. In rats, fetal LC size and intratesticular testosterone (ITT) increased âŒ3-fold between e15.5-e21.5 which associated with a progressive decrease in the percentage of LC expressing COUP-TFII. Exposure of fetuses to dibutyl phthalate (DBP), which induces masculinization disorders, dose-dependently prevented the age-related decrease in LC COUP-TFII expression and the normal increases in LC size and ITT. We show that nuclear COUP-TFII expression in fetal rat LC relates inversely to LC expression of steroidogenic factor-1 (SF-1)-dependent genes (StAR, Cyp11a1, Cyp17a1) with overlapping binding sites for SF-1 and COUP-TFII in their promoter regions, but does not affect an SF-1 dependent LC gene (3ÎČ-HSD) without overlapping sites. We also show that once COUP-TFII expression in LC has switched off, it is re-induced by DBP exposure, coincident with suppression of ITT. Furthermore, other treatments that reduce fetal ITT in rats (dexamethasone, diethylstilbestrol (DES)) also maintain/induce LC nuclear expression of COUP-TFII. In contrast to rats, in mice DBP neither causes persistence of fetal LC COUP-TFII nor reduces ITT, whereas DES-exposure of mice maintains COUP-TFII expression in fetal LC and decreases ITT, as in rats. These findings suggest that lifting of repression by COUP-TFII may be an important mechanism that promotes increased testosterone production by fetal LC to drive masculinization. As we also show an age-related decline in expression of COUP-TFII in human fetal LC, this mechanism may also be functional in humans, and its susceptibility to disruption by environmental chemicals, stress and pregnancy hormones could explain the origin of some human male reproductive disorders
Seismic and geochemical evidence for large-scale mantle upwelling beneath the eastern Atlantic and western and central Europe
Seismic tomography and the isotope geochemistry of Cenozoic volcanic rocks suggest the existence of a large, sheet-like region of upwelling in the upper mantle which extends from the eastern Atlantic Ocean to central Europe and the western Mediterranean. A belt of extension and rifting in the latter two areas appears to lie above the intersection of the centre of the upwelling region with the base of the lithosphere. Lead, strontium and neodymium isotope data for all three regions converge on a restricted composition, inferred to be that of the upwelling mantle
Sexual Priming, Gender Stereotyping, and Likelihood to Sexually Harass: Examining the Cognitive Effects of Playing a Sexually-Explicit Video Game
The present study examines the short-term cognitive effects of playing a sexually explicit video game with female âobjectificationâ content on male players. Seventy-four male students from a university in California, U.S. participated in a laboratory experiment. They were randomly assigned to play either a sexually-explicit game or one of two control games. Participantsâ cognitive accessibility to sexual and sexually objectifying thoughts was measured in a lexical decision task. A likelihood-to-sexually-harass scale was also administered. Results show that playing a video game with the theme of female âobjectificationâ may prime thoughts related to sex, encourage men to view women as sex objects, and lead to self-reported tendencies to behave inappropriately towards women in social situations
Soda and Tobacco Industry Corporate Social Responsibility Campaigns: How Do They Compare?
In an article that forms part of the PLoS Medicine series on Big Food, Andrew Cheyne and colleagues compare soda companies' corporate social responsibility (CSR) campaigns - which are designed to bolster the image and popularity of their products and to prevent regulation - with the tobacco industry's CSR campaigning
Backpack-mounted satellite transmitters do not affect reproductive performance in a migratory bustard
Backpack-mounted satellite transmitters (PTTs) are used extensively in the study of avian habitat use and of the movements and demography of medium- to large-bodied species, but can affect individualsâ performance and fitness. Transparent assessment of potential transmitter effects is important for both ethical accountability and confidence in, or adjustment to, life history parameter estimates. We assessed the influence of transmitters on seven reproductive parameters in Asian houbara Chlamydotis macqueenii, comparing 114 nests of 38 females carrying PTTs to 184 nests of untagged birds (non-PTT) over seven breeding seasons (2012â2018) in Uzbekistan. There was no evidence of any influence of PTTs on: lay date (non-PTT xÌ
= 91.7 Julian day ± 12.3 SD; PTT xÌ
= 95.1 Julian day ± 15.7 SD); clutch size (non-PTT xÌ
= 3.30 ± 0.68 SD; PTT xÌ
= 3.25 ± 0.65 SD); mean egg weight at laying (non-PTT xÌ
= 66.1g ± 5.4 SD; PTT xÌ
= 66.4g ± 5.4 SD); nest success (non-PTT xÌ
= 57.08% ± 4.3 SE; PTT xÌ
= 58.24% ± 4.5 SE for nests started 2 April); egg hatchability (non-PTT xÌ
= 88.3% ± 2.2 SE; PTT xÌ
= 88.3% ± 2.6 SE); or chick survival to fledging from broods that had at least one surviving chick (non-PTT xÌ
= 63.4% ± 4.2 SE; PTT xÌ
= 64.4% ± 4.7 SE). High nesting propensity (97.3% year-1 ± 1.9% SE) of tagged birds indicated minimal PTT effect on breeding probability. These findings show harness-mounted transmitters can give unbiased measures of demographic parameters of this species, and are relevant to other large-bodied, cursorial, ground-nesting birds of open habitats, particularly other bustards
Timescales of Quartz Crystallization and the Longevity of the Bishop Giant Magma Body
Supereruptions violently transfer huge amounts (100 sâ1000 s km3) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted âŒ760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of <10,000 years, more typically within 500â3,000 years before eruption. We conclude that large-volume, crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies
The hidden curriculum and integrating cure- and care-based approaches to medicine
Although current literature about the âcure versus careâ issue tends to promote a patient-centered approach, the disease-centered approach remains the prevailing model in practice. The perceived dichotomy between the two approaches has created a barrier that could make it difficult for medical students and physicians to integrate psychosocial aspects of patient care into the prevailing disease-based model. This article examines the influence of the formal and hidden curricula on the perception of these two approaches and finds that the hidden curriculum perpetuates the notion that âcureâ and âcareâ based approaches are dichotomous despite significant changes in formal curricula that promote a more integrated approach. The authors argue that it is detrimental for clinicians to view the two approaches as oppositional rather than complementary and attempt to give recommendations on how the influence of the hidden curriculum can be reduced to get a both-cure-and-care-approach, rather than an either-cure-or-care-approach
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4
While the increasing availability of global databases on ecological communities has advanced our knowledge
of biodiversity sensitivity to environmental changes,5â7 vast areas of the tropics remain understudied.8â11 In
the American tropics, Amazonia stands out as the worldâs most diverse rainforest and the primary source of
Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13â15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazonâs biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus
crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced
environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian
Amazonia, while identifying the regionâs vulnerability to environmental change. 15%â18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by
2050. This means that unless we take immediate action, we will not be able to establish their current status,
much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio
- âŠ