scholarly journals Phototroph-heterotroph interactions during growth and long-term starvation across Prochlorococcus and Alteromonas diversity

2021 ◽  
Author(s):  
Daniel Jonathan Sher ◽  
Dikla Aharonovich ◽  
Osnat Weissberg
Keyword(s):  
Carrying Capacity ◽  
Death Rate ◽  
Nitrogen Starvation ◽  
Stringent Response ◽  
Decline Curve ◽  
Cell Mortality ◽  
Starvation Survival ◽  
Potential Impact ◽  
Over Time

Interactions among microorganisms are ubiquitous, yet to what extent strain-level diversity affects interactions is unclear. Phototroph-heterotroph interactions in marine environments have been studied intensively, due to their potential impact on ocean ecosystems and biogeochemistry. Here, we characterize the interactions between five strains each of two globally abundant marine bacteria, Prochlorococcus (a phototroph) and Alteromonas (a heterotroph), from the first encounter between individual strains and over more than a year of subsequent co-culturing. Prochlorococcus-Alteromonas interactions affected primarily the dynamics of culture decline, which we interpret as representing cell mortality and lysis. The shape of the decline curve and the carrying capacity of the co-cultures were determined by the phototroph and not the heterotroph strains involved. Comparing various models of culture mortality suggests that death rate increases over time in mono-cultures but decreases in co-cultures, with cells potentially becoming more resistant to stress. During 435 days of co-culture, mutations accumulated in one Prochlorococcus strain (MIT9313) in genes involved in nitrogen metabolism and the stringent response, indicating that these processes occur during long-term nitrogen starvation. Our results suggest potential mechanisms involved in long-term starvation survival in co-culture, and highlight the information-rich growth and death curves as a useful readout of the interaction phenotype.

scholarly journals The adaptive response to long-term nitrogen starvation in Escherichia coli requires the breakdown of allantoin

2020 ◽  
Author(s):  
Amy Switzer ◽  
Lynn Burchell ◽  
Josh McQuail ◽  
Sivaramesh Wigneshweraraj
Keyword(s):  
Escherichia Coli ◽  
Cell Function ◽  
Nitrogen Starvation ◽  
Nutrient Starvation ◽  
Continuous Growth ◽  
E Coli ◽  
Transcriptional Changes ◽  
N Starvation ◽  
Over Time

ABSTRACTBacteria initially respond to nutrient starvation by eliciting large-scale transcriptional changes. The accompanying changes in gene expression and metabolism allow the bacterial cells to effectively adapt to the nutrient starved state. How the transcriptome subsequently changes as nutrient starvation ensues is not well understood. We used nitrogen (N) starvation as a model nutrient starvation condition to study the transcriptional changes in Escherichia coli experiencing long-term N starvation. The results reveal that the transcriptome of N starved E. coli undergoes changes that are required to maximise chances of viability and to effectively recover growth when N starvation conditions become alleviated. We further reveal that, over time, N starved E. coli cells rely on the degradation of allantoin for optimal growth recovery when N becomes replenished. This study provides insights into the temporally coordinated adaptive responses that occur in E. coli experiencing sustained N starvation.IMPORTANCEBacteria in their natural environments seldom encounter conditions that support continuous growth. Hence, many bacteria spend the majority of their time in states of little or no growth due to starvation of essential nutrients. To cope with prolonged periods of nutrient starvation, bacteria have evolved several strategies, primarily manifesting themselves through changes in how the information in their genes is accessed. How these coping strategies change over time under nutrient starvation is not well understood and this knowledge is not only important to broaden our understanding of bacterial cell function, but also to potentially find ways to manage harmful bacteria. This study provides insights into how nitrogen starved Escherichia coli bacteria rely on different genes during long term nitrogen starvation.

scholarly journals The Adaptive Response to Long-Term Nitrogen Starvation in Escherichia coli Requires the Breakdown of Allantoin

2020 ◽  
Vol 202 (17) ◽  
Author(s):  
Amy Switzer ◽  
Lynn Burchell ◽  
Josh McQuail ◽  
Sivaramesh Wigneshweraraj
Keyword(s):  
Escherichia Coli ◽  
Nitrogen Starvation ◽  
Nutrient Starvation ◽  
Continuous Growth ◽  
Content Type ◽  
E Coli ◽  
Transcriptional Changes ◽  
N Starvation ◽  
Over Time

ABSTRACT Bacteria initially respond to nutrient starvation by eliciting large-scale transcriptional changes. The accompanying changes in gene expression and metabolism allow the bacterial cells to effectively adapt to the nutrient-starved state. How the transcriptome subsequently changes as nutrient starvation ensues is not well understood. We used nitrogen (N) starvation as a model nutrient starvation condition to study the transcriptional changes in Escherichia coli experiencing long-term N starvation. The results reveal that the transcriptome of N-starved E. coli undergoes changes that are required to maximize chances of viability and to effectively recover growth when N starvation conditions become alleviated. We further reveal that, over time, N-starved E. coli cells rely on the degradation of allantoin for optimal growth recovery when N becomes replenished. This study provides insights into the temporally coordinated adaptive responses that occur in E. coli experiencing sustained N starvation. IMPORTANCE Bacteria in their natural environments seldom encounter conditions that support continuous growth. Hence, many bacteria spend the majority of their time in states of little or no growth due to starvation of essential nutrients. To cope with prolonged periods of nutrient starvation, bacteria have evolved several strategies, primarily manifesting themselves through changes in how the information in their genes is accessed. How these coping strategies change over time under nutrient starvation is not well understood, and this knowledge is important not only to broaden our understanding of bacterial cell function but also to potentially find ways to manage harmful bacteria. This study provides insights into how nitrogen-starved Escherichia coli bacteria rely on different genes during long-term nitrogen starvation.

PARENTAL PREFERENCE FOR SONS AND DAUGHTERS IN A WESTERN INDUSTRIAL SETTING: EVIDENCE AND IMPLICATIONS

2007 ◽  
Vol 39 (4) ◽  
pp. 583-597 ◽  
Author(s):  
REBECCA KIPPEN ◽  
ANN EVANS ◽  
EDITH GRAY
Keyword(s):  
Census Data ◽  
Sex Selection ◽  
Same Sex ◽  
Sex Composition ◽  
Short Term ◽  
Parental Preference ◽  
Industrial Setting ◽  
Potential Impact ◽  
Over Time

SummaryThis paper considers whether sex composition of existing children in Australian families is an important factor in parity progression. Using census data from 1981, 1986, 1991, 1996 and 2001, women are linked with their co-resident children, allowing investigation of family sex composition and its changing impact over time on the propensity to have another child. The study finds that parents are much more likely to have a third and fourth birth if existing children are all of the same sex, indicating a strong preference for children of both sexes. This increased propensity has added around three per cent to the fertility of recent cohorts. The paper concludes with a discussion of the potential impact of sex-selection technologies on fertility. The authors argue that future widespread use of reliable sex-selection technologies might act to increase fertility in the short term, but would lead to a long-term reduction in fertility.

scholarly journals Emerging from the COVID-19 pandemic: impacts of variants, vaccines, and duration of immunity

2021 ◽  
Author(s):  
Ken Newcomb ◽  
Edwin Michael
Keyword(s):  
Effective Means ◽  
The State ◽  
Mass Vaccination ◽  
Data Driven ◽  
Vaccination Programs ◽  
Potential Impact ◽  
Over Time ◽  
Roll Out

The advent of vaccines against SARS-CoV-2 and the roll out of mass vaccination programs are thought to present the most effective means to control and even end the ongoing pandemic. However, uncertainties connected with the partial effectiveness of present vaccines, duration of immunity against SARS-CoV-2, and potential impact of variant dynamics, mean that it is still possible that the contagion could follow different future paths in different communities. Here, we use an extended SEIR for SARS-COV-2 transmission sequentially calibrated to data on cases and interventions implemented in the state of Florida to explore how these factors may interact to govern potential pandemic futures. Our data-driven forecasts indicate while the introduction of vaccinations could lead to the permanent, albeit drawn-out, ending of the pandemic if the immunity generated through vaccinations and natural infections acts over the long-term, additional futures could become possible if this immunity wanes over time. These futures will be marked by repeated waves of infection, the amplitude and periodicity of which will depend on the duration over which the immunity generated in a population will operate. We conclude that the possibility of these complex futures will require continual vigilance and perhaps fundamental changes in societal responses if we are to effectively control SARS-CoV-2.

Periprocedural risk and long-term outcome of intracranial angioplasty based on a single-centre experience

VASA ◽  
2013 ◽  
Vol 42 (4) ◽  
pp. 264-274
Author(s):  
Dagmar Krajíčková ◽  
Antonín Krajina ◽  
Miroslav Lojík ◽  
Martina Mulačová ◽  
Martin Vališ
Keyword(s):  
Death Rate ◽  
Long Term Outcomes ◽  
Single Centre ◽  
Intracranial Atherosclerotic Stenosis ◽  
Atherosclerotic Stenosis ◽  
Angioplasty And Stenting ◽  
Aggressive Medical Management ◽  
Stroke Death

Background: Intracranial atherosclerotic stenosis is a major cause of stroke and yet there are currently no proven effective treatments for it. The SAMMPRIS trial, comparing aggressive medical management alone with aggressive medical management combined with intracranial angioplasty and stenting, was prematurely halted when an unexpectedly high rate of periprocedural events was found in the endovascular arm. The goal of our study is to report the immediate and long-term outcomes of patients with ≥ 70 % symptomatic intracranial atherosclerotic stenosis treated with balloon angioplasty and stent placement in a single centre. Patients and methods: This is a retrospective review of 37 consecutive patients with 42 procedures of ballon angioplasty and stenting for intracranial atherosclerotic stenosis (≥ 70 % stenosis) treated between 1999 and 2012. Technical success (residual stenosis ≤ 50 %), periprocedural success (no vascular complications within 72 hours), and long-term outcomes are reported. Results: Technical and periprocedural success was achieved in 90.5 % of patients. The within 72 hours periprocedural stroke/death rate was 7.1 % (4.8 % intracranial haemorrhage), and the 30-day stroke/death rate was 9.5 %. Thirty patients (81 %) had clinical follow-up at ≥ 6 months. During follow-up, 5 patients developed 6 ischemic events; 5 of them (17 %) were ipsilateral. The restenosis rate was 27 %, and the retreatment rate was 12 %. Conclusions: Our outcomes of the balloon angioplasty/stent placement for intracranial atherosclerotic stenosis are better than those in the SAMMPRIS study and compare favourably with those in large registries and observational studies.

Enhancing community welfare through improved water quality: a case for applying staggered pollution charges in the river Musi sub-basin of Andhra Pradesh, India

Water Policy ◽  
2005 ◽  
Vol 7 (5) ◽  
pp. 469-483
Author(s):  
Tishya Chatterjee
Keyword(s):  
Andhra Pradesh ◽  
Relevant Literature ◽  
Pollution Prevention ◽  
Economic Benefits ◽  
Environmental Damage ◽  
Marginal Costs ◽  
Community Acceptance ◽  
Level Data ◽  
Over Time

In conditions of severe water-pollution and dormant community acceptance of accumulating environmental damage, the regulator's role goes beyond pollution prevention and more towards remediation and solutions based on the community's long-term expectations of economic benefits from clean water. This paper suggests a method to enable these benefits to become perceptible progressively, through participatory clean-up operations, supported by staggered pollution charges. It analyses the relevant literature on pollution prevention and applies a cost-based “willingness to pay” model, using primary basin-level data of total marginal costs. It develops a replicable demand-side approach imposing charge-standard targets over time in urban-industrial basins of developing countries.

The Short-Term and Long-Term Impacts of Sarbanes-Oxley Act on Composition and Characteristics of Corporate Board of Directors

2015 ◽  
Vol 5 (4) ◽  
Author(s):  
Halil Kaya ◽  
Gaurango Banerjee
Keyword(s):  
Board Composition ◽  
Corporate Boards ◽  
Corporate Accountability ◽  
Corporate Board ◽  
Short Term ◽  
Dual Roles ◽  
Board Characteristics ◽  
Sarbanes Oxley ◽  
Over Time

The paper examines the Sarbanes-Oxley (2002) Acts immediate impact on board composition and characteristics as well as possible reversals in its impact over time. Effects on directors age and tenure are analyzed over the 2001-06 sample period. Female participation in corporate boards is also studied in the pre-SOX and post-SOX periods. The dual roles of directors in being a member of the board as well as serving as either CEO, CFO, Chairman, Co-Chair, Founder, or Lead Director of their respective companies is also examined. We observe a short-term impact of SOX on board compositions due to changes seen in board characteristics between 2001 (pre-SOX), and 2003-05 short-term period (post-SOX). Also, we observe a reversal of board characteristics in 2006 to pre-SOX levels implying that the effects of SOX on board composition were short-lived, and needs to be monitored over time to ensure adherence to corporate accountability guidelines over the long-term.

A Downward Spiral? A Panel Study of Misinformation and Media Trust in Chile

2021 ◽  
pp. 194016122110252
Author(s):  
Sebastián Valenzuela ◽  
Daniel Halpern ◽  
Felipe Araneda
Keyword(s):  
News Media ◽  
Panel Study ◽  
Future Research ◽  
Panel Survey ◽  
Downward Spiral ◽  
The Media ◽  
Media Trust ◽  
People’S Attitudes ◽  
Over Time

Despite widespread concern, research on the consequences of misinformation on people's attitudes is surprisingly scant. To fill in this gap, the current study examines the long-term relationship between misinformation and trust in the news media. Based on the reinforcing spirals model, we analyzed data from a three-wave panel survey collected in Chile between 2017 and 2019. We found a weak, over-time relationship between misinformation and media skepticism. Specifically, initial beliefs on factually dubious information were negatively correlated with subsequent levels of trust in the news media. Lower trust in the media, in turn, was related over time to higher levels of misinformation. However, we found no evidence of a reverse, parallel process where media trust shielded users against misinformation, further reinforcing trust in the news media. The lack of evidence of a downward spiral suggests that the corrosive effects of misinformation on attitudes toward the news media are less serious than originally suggested. We close with a discussion of directions for future research.

scholarly journals Personality dynamics at work: The effects of form, time, and context of variability

2021 ◽  
pp. 089020702110173
Author(s):  
Nadin Beckmann ◽  
Damian P Birney ◽  
Amirali Minbashian ◽  
Jens F Beckmann
Keyword(s):  
Individual Differences ◽  
Cognitive Ability ◽  
Temporal Stability ◽  
Limited Evidence ◽  
Short Term ◽  
State Data ◽  
The Status ◽  
Over Time ◽  
Trait Variability

The study aimed to investigate the status of within-person state variability in neuroticism and conscientiousness as individual differences constructs by exploring their (a) temporal stability, (b) cross-context consistency, (c) empirical links to selected antecedents, and (d) empirical links to longer term trait variability. Employing a sample of professionals ( N = 346) from Australian organisations, personality state data together with situation appraisals were collected using experience sampling methodology in field and repeatedly in lab-like settings. Data on personality traits, cognitive ability, and motivational mindsets were collected at baseline and after two years. Contingent (situation contingencies) and non-contingent (relative SD) state variability indices were relatively stable over time and across contexts. Only a small number of predictive effects of state variability were observed, and these differed across contexts. Cognitive ability appeared to be associated with state variability under lab-like conditions. There was limited evidence of links between short-term state and long-term trait variability, except for a small effect for neuroticism. Some evidence of positive manifold was found for non-contingent variability. Systematic efforts are required to further elucidate the complex pattern of results regarding the antecedents, correlates and outcomes of individual differences in state variability.

scholarly journals Can we reestablish a self-sustaining population? A case study on reintroduced Crested Ibis with population viability analysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yashuai Zhang ◽  
Fang Wang ◽  
Zhenxia Cui ◽  
Min Li ◽  
Xia Li ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Population Size ◽  
Carrying Capacity ◽  
Wild Population ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Viability Analysis ◽  
Crested Ibis ◽  
Reintroduced Population

Abstract Background One of the most challenging tasks in wildlife conservation and management is clarifying which and how external and intrinsic factors influence wildlife demography and long-term viability. The wild population of the Crested Ibis (Nipponia nippon) has recovered to approximately 4400, and several reintroduction programs have been carried out in China, Japan and Korea. Population viability analysis on this endangered species has been limited to the wild population, showing that the long-term population growth is restricted by the carrying capacity and inbreeding. However, gaps in knowledge of the viability of the reintroduced population and its drivers in the release environment impede the identification of the most effective population-level priorities for aiding in species recovery. Methods The field monitoring data were collected from a reintroduced Crested Ibis population in Ningshan, China from 2007 to 2018. An individual-based VORTEX model (Version 10.3.5.0) was used to predict the future viability of the reintroduced population by incorporating adaptive patterns of ibis movement in relation to catastrophe frequency, mortality and sex ratio. Results The reintroduced population in Ningshan County is unlikely to go extinct in the next 50 years. The population size was estimated to be 367, and the population genetic diversity was estimated to be 0.97. Sensitivity analysis showed that population size and extinction probability were dependent on the carrying capacity and sex ratio. The carrying capacity is the main factor accounting for the population size and genetic diversity, while the sex ratio is the primary factor responsible for the population growth trend. Conclusions A viable population of the Crested Ibis can be established according to population viability analysis. Based on our results, conservation management should prioritize a balanced sex ratio, high-quality habitat and low mortality.

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