scholarly journals Alkanes increase the stability of early life membrane models under extreme pressure and temperature conditions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Loreto Misuraca ◽  
Bruno Demé ◽  
Philippe Oger ◽  
Judith Peters
Keyword(s):  
Early Life ◽  
Hydrothermal Vents ◽  
Time Window ◽  
Extreme Temperature ◽  
Adaptive Strategy ◽  
Multilamellar Vesicle ◽  
Chain Dynamics ◽  
Terrestrial Life ◽  
Temperature And Pressure ◽  
Membrane Components

AbstractTerrestrial life appeared on our planet within a time window of [4.4–3.5] billion years ago. During that time, it is suggested that the first proto-cellular forms developed in the surrounding of deep-sea hydrothermal vents, oceanic crust fractures that are still present nowadays. However, these environments are characterized by extreme temperature and pressure conditions that question the early membrane compartment’s capability to endure a stable structural state. Recent studies proposed an adaptive strategy employed by present-day extremophiles: the use of apolar molecules as structural membrane components in order to tune the bilayer dynamic response when needed. Here we extend this hypothesis on early life protomembrane models, using linear and branched alkanes as apolar stabilizing molecules of prebiotic relevance. The structural ordering and chain dynamics of these systems have been investigated as a function of temperature and pressure. We found that both types of alkanes studied, even the simplest linear ones, impact highly the multilamellar vesicle ordering and chain dynamics. Our data show that alkane-enriched membranes have a lower multilamellar vesicle swelling induced by the temperature increase and are significantly less affected by pressure variation as compared to alkane-free samples, suggesting a possible survival strategy for the first living forms.

A symbiotic view of the origin of life at hydrothermal impact crater-lakes

2016 ◽  
Vol 18 (30) ◽  
pp. 20033-20046 ◽  
Author(s):  
Sankar Chatterjee
Keyword(s):  
Origin Of Life ◽  
Early Life ◽  
Hydrothermal Vents ◽  
Impact Crater ◽  
Crater Lakes ◽  
Origin And Evolution ◽  
The Origin Of Life ◽  
Life On Earth

Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth.

scholarly journals Conserved serotonergic background of experience-dependent challenge-responding in zebrafish (Danio rerio)

2019 ◽  
Author(s):  
Zoltán K Varga ◽  
Diána Pejtsik ◽  
László Biró ◽  
Áron Zsigmond ◽  
Máté Varga ◽  
...  
Keyword(s):  
Danio Rerio ◽  
Stress Responses ◽  
Early Life ◽  
Time Window ◽  
Life Experiences ◽  
Partial Agonist ◽  
Social Stimuli ◽  
Behavioral Impairment ◽  
Behavioral Responsiveness ◽  
Stress Dependent

AbstractForming effective responses to threatening stimuli requires the adequate and coordinated emergence of stress-related internal states. Such ability depends on early-life experiences and, in connection, the adequate formation of neuromodulatory systems, particularly serotonergic signaling. Here, we assess the serotonergic background of experience-dependent behavioral responsiveness employing a zebrafish (Danio rerio) model. For the first time, we have characterized a period during the behavioral metamorphosis in which zebrafish are highly reactive to their environment. Absence of social stimuli during this phase established by isolated rearing fundamentally altered the behavioral phenotype of post-metamorphic zebrafish in a challenge-specific manner, partially due to a decline in responsiveness and an inability to develop stress-associated arousal state. In line with this, isolation differently affected whole-brain 5-HT signaling in resting and stress-induced conditions, an effect that was present at the level of the dorsal pallium and was negatively associated with responsiveness. Administration of the 5HT1AR partial agonist buspirone prevented the isolation-induced serotonin response to novelty in the forebrain and rescued stress-induced arousal along with challenge-induced behaviors, which altogether indicates a functional connection between these changes. In summary, there is a consistent negative association between behavioral responsiveness and serotonergic signaling in zebrafish, which is well recognizable through the modifying effects of developmental perturbation and pharmacological manipulations as well. Our results imply a conserved serotonergic mechanism that context-dependently modulates environmental reactivity and is highly sensitive to experiences acquired during a specific early-life time-window, a phenomenon that was previously only suggested in mammals.Significance statementThe ability to respond to challenges is a fundamental factor in survival. We show that zebrafish that lack appropriate social stimuli in a sensitive developmental period show exacerbated alertness in non-stressful conditions while failing to react adequately to stressors. This shift is reflected inversely by central serotonergic signaling, a system that is implicated in numerous mental disorders in humans. Serotonergic changes in brain regions modulating responsivity and behavioral impairment were both prevented by the pharmacological blockade of serotonergic function. These results imply a serotonergic mechanism in zebrafish that transmits early-life experiences to the later phenotype by shaping stress-dependent behavioral reactivity, a phenomenon that was previously only suggested in mammals. Zebrafish provide new insights into early-life-dependent neuromodulation of behavioral stress-responses.

scholarly journals Early-life exposure to severe famine and subsequent risk of depressive symptoms in late adulthood: the China Health and Retirement Longitudinal Study

2018 ◽  
Vol 213 (4) ◽  
pp. 579-586 ◽  
Author(s):  
Changwei Li ◽  
Toni Miles ◽  
Luqi Shen ◽  
Ye Shen ◽  
Tingting Liu ◽  
...  
Keyword(s):  
Depressive Symptoms ◽  
Longitudinal Study ◽  
Poisson Regression ◽  
Early Life ◽  
Time Window ◽  
Critical Time ◽  
Symptom Burden ◽  
Late Adulthood ◽  
Great Famine ◽  
Famine Exposure

BackgroundThe Chinese Great Famine caused widespread starvation in 1959–1961. Its long-term association with depressive symptoms has not been studied.AimsTo estimate the burden of depressive symptoms and the association of famine exposure with depressive symptoms.MethodThe China Health and Retirement Longitudinal Study is a nationwide representative survey of 17 708 Chinese adults aged ≥45. Propensity score matching and modified Poisson regression were used to evaluate the association between self-reported famine exposure in early life and depressive symptoms among the overall participants. Such associations were also assessed by developmental stage using modified Poisson regression and logistic regression.ResultsThe prevalence of depressive symptoms was 26.2% (95% CI 25.1–27.3%) in 2011. As defined by loss of family members because of starvation, 11.6% (95% CI 10.1–13.1%) of this population experienced severe famine. When compared with participants who did not experience starvation, those who had experienced severe famine during fetal, mid-childhood, young-teenage and early-adulthood stages had 1.87 (95% CI 1.36–2.55), 1.54 (95% CI 1.23–1.94), 1.47 (95% CI 1.09–2.00) and 1.77 (95% CI 1.42–2.21) times higher odds of having depressive symptoms in late adulthood, respectively. The first two trimesters of pregnancy were a critical time window during the fetal stage when severe famine had a stronger association with depressive symptoms. Famine during infant, toddler, preschool or teenage stages was not associated with depressive symptoms. Overall, famine contributed to 13.6% of the depressive symptom burden in this population.ConclusionsThe Chinese Great Famine contributed substantially to the burden of depressive symptoms in China.Declaration of interestNone.

scholarly journals Intestinal CD8αα IELs derived from two distinct thymic precursors have staggered ontogeny

2020 ◽  
Vol 217 (8) ◽  
Author(s):  
Roland Ruscher ◽  
S. Thera Lee ◽  
Oscar C. Salgado ◽  
Elise R. Breed ◽  
Sara H. Osum ◽  
...  
Keyword(s):  
Early Life ◽  
Time Window ◽  
Type A ◽  
Intraepithelial Lymphocytes ◽  
Time Stamp ◽  
Type B ◽  
Initial Wave ◽  
Gut Epithelium ◽  
Insight Into ◽  
Young Mice

CD8αα intraepithelial lymphocytes (IELs) are abundant T cells that protect the gut epithelium. Their thymic precursors (IELps) include PD-1+ type A and Tbet+ type B populations, which differ in their antigen-receptor specificities. To better understand CD8αα IEL ontogeny, we performed “time-stamp” fate mapping experiments and observed that it seeds the intestine predominantly during a narrow time window in early life. Adoptively transferred IELps parked better in the intestines of young mice than in adults. In young mice, both type A and type B IELps had an S1PR1+ and α4β7+ emigration- and mucosal-homing competent phenotype, while this was restricted to type A IELps in adults. Only CD8αα IELs established in early life were enriched in cells bearing type B IELp TCR usage. Together, our results suggest that the young intestine facilitates CD8αα IEL establishment and that early IELs are distinct from IELs established after this initial wave. These data provide novel insight into the ontogeny of CD8αα IELs.

scholarly journals A post-decisional neural marker of confidence predicts information-seeking in decision-making

2018 ◽  
Author(s):  
Kobe Desender ◽  
Peter Murphy ◽  
Annika Boldt ◽  
Tom Verguts ◽  
Nick Yeung
Keyword(s):  
Information Seeking ◽  
Time Window ◽  
Adaptive Strategy ◽  
Theoretical Work ◽  
Confidence Judgment ◽  
Final Decision ◽  
Time Resolved ◽  
Perceptual Decision ◽  
Scalp Eeg ◽  
Neural Marker

AbstractTheoretical work predicts that decisions made with low confidence should lead to increased information-seeking. This is an adaptive strategy because it can increase the quality of a decision, and previous behavioral work has shown that decision-makers engage in such confidence-driven information seeking. The present study aimed to characterize the neural markers that mediate the relationship between confidence and information-seeking. A paradigm was used in which human participants made an initial perceptual decision, and then decided whether or not they wanted to sample more evidence before committing to a final decision and confidence judgment. Pre-decisional and post-decisional ERP components were similarly modulated by the level of confidence and by information-seeking choices. Time-resolved multivariate decoding of scalp EEG signals first revealed that information-seeking choices could be decoded from the time of the initial decision to the time of the subsequent information-seeking choice (within-condition decoding). No above-chance decoding was visible in the pre-response time window. Crucially, a classifier trained to decode high versus low confidence predicted information-seeking choices after the initial perceptual decision (across-condition decoding). This time window corresponds to that of a post-decisional neural marker of confidence. Collectively, our findings demonstrate for the first time that neural indices of confidence are functionally involved in information-seeking decisions.

Design Optimization of Compact Superalloy Heat Exchangers for Extreme Temperature and Pressure Conditions

2021 ◽  
Author(s):  
Kaiyuan Jin ◽  
Akshay Bharadwaj Krishna ◽  
Zachary Wong ◽  
Timothy Fisher ◽  
Ivan Catton ◽  
...  
Keyword(s):  
Design Optimization ◽  
Heat Exchangers ◽  
Extreme Temperature ◽  
Temperature And Pressure

Volume-translated cubic EoS and PC-SAFT density models and a free volume-based viscosity model for hydrocarbons at extreme temperature and pressure conditions

2013 ◽  
Vol 359 ◽  
pp. 38-44 ◽  
Author(s):  
Ward A. Burgess ◽  
Deepak Tapriyal ◽  
Bryan D. Morreale ◽  
Yee Soong ◽  
Hseen O. Baled ◽  
...  
Keyword(s):  
Free Volume ◽  
Extreme Temperature ◽  
Viscosity Model ◽  
Temperature And Pressure

High-Temperature Steam Supply: Configuration Design for Temperature Control Stability

1991 ◽  
Vol 113 (1) ◽  
pp. 12-19 ◽  
Author(s):  
J. P. Mumm ◽  
J. Orozco
Keyword(s):  
Extreme Temperature ◽  
Temperature Stability ◽  
Numerical Code ◽  
Operating Characteristics ◽  
Test Specifications ◽  
Process Operation ◽  
Temperature And Pressure ◽  
High Temperature Steam ◽  
Control Stability ◽  
Nominal Temperature

The main objective of this investigation is to report on the development and testing of a numerical code to simulate the operating characteristics of a steam-powered propulsion system. The test specifications permitted a temperature variation of 135 K (75°F) from the nominal temperature 1144 K (1600°F). Due to the extreme temperature and pressure involved, any overshoot would severly shorten the life of the facility. The predicted performance of the system was then evaluated for temperature stability. The code was also used to determine the modifications required to stabilize temperature variations. Testing was performed to better understand the dynamics of the process operation. The experimental data verified the predictions of the numerical code.

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