scholarly journals Quantifying the Importance of Abiotic and Biotic Factors Governing the Succession of Gut Microbiota Over Shrimp Ontogeny

2021 ◽  
Vol 12 ◽  
Author(s):  
Wenqian Zhang ◽  
Zidong Zhu ◽  
Jiong Chen ◽  
Qiongfen Qiu ◽  
Jinbo Xiong
Keyword(s):  
Gut Microbiota ◽  
Bacterial Communities ◽  
Structural Equation ◽  
Abiotic Factors ◽  
Age Factors ◽  
Equation Model ◽  
Shrimp Farming ◽  
Ecological Processes ◽  
Water Ph ◽  
Bacterioplankton Communities

Intensive studies have evaluated abiotic factors in shaping host gut microbiota. In contrast, little is known on how and to what extent abiotic (geochemical variables) and biotic (i.e., surrounding microbes, younger shrimp, and age) factors assemble the gut microbiota over shrimp ontogeny. Considering the functional importance of gut microbiota in improving host fitness, this knowledge is fundamental to sustain a desirable gut microbiota for a healthy aquaculture. Here, we characterized the successional rules of both the shrimp gut and rearing water bacterial communities over the entire shrimp farming. Both the gut and rearing water bacterial communities exhibited the time decay of similarity relationship, with significantly lower temporal turnover rate for the gut microbiota, which were primarily governed by shrimp age (days postlarval inoculation) and water pH. Gut commensals were primary sourced (averaged 60.3%) from their younger host, rather than surrounding bacterioplankton (19.1%). A structural equation model revealed that water salinity, pH, total phosphorus, and dissolve oxygen directly governed bacterioplankton communities but not for the gut microbiota. In addition, shrimp gut microbiota did not simply mirror the rearing bacterioplankton communities. The gut microbiota tended to be governed by variable selection over shrimp ontogeny, while the rearing bacterioplankton community was shaped by homogeneous selection. However, the determinism of rare and stochasticity of abundant subcommunities were consistent between shrimp gut and rearing water. These findings highlight the importance of independently interpreting host-associated and free-living communities, as well as their rare and abundant subcommunities for a comprehensive understanding of the ecological processes that govern microbial successions.

scholarly journals Abiotic factors influence patterns of bacterial diversity and community composition in the Dry Valleys of Antarctica

2020 ◽  
Vol 96 (5) ◽  
Author(s):  
Eric M Bottos ◽  
Daniel C Laughlin ◽  
Craig W Herbold ◽  
Charles K Lee ◽  
Ian R McDonald ◽  
...  
Keyword(s):  
Community Composition ◽  
Bacterial Communities ◽  
Structural Equation ◽  
Abiotic Factors ◽  
Biotic Interactions ◽  
Equation Modeling ◽  
Dry Valleys ◽  
Physicochemical Variables ◽  
Soil Conductivity ◽  
Community Dissimilarity

ABSTRACT The Dry Valleys of Antarctica are a unique ecosystem of simple trophic structure, where the abiotic factors that influence soil bacterial communities can be resolved in the absence of extensive biotic interactions. This study evaluated the degree to which aspects of topographic, physicochemical and spatial variation explain patterns of bacterial richness and community composition in 471 soil samples collected across a 220 square kilometer landscape in Southern Victoria Land. Richness was most strongly influenced by physicochemical soil properties, particularly soil conductivity, though significant trends with several topographic and spatial variables were also observed. Structural equation modeling (SEM) supported a final model in which variation in community composition was best explained by physicochemical variables, particularly soil water content, and where the effects of topographic variation were largely mediated through their influence on physicochemical variables. Community dissimilarity increased with distance between samples, and though most of this variation was explained by topographic and physicochemical variation, a small but significant relationship remained after controlling for this environmental variation. As the largest survey of terrestrial bacterial communities of Antarctica completed to date, this work provides fundamental knowledge of the Dry Valleys ecosystem, and has implications globally for understanding environmental factors that influence bacterial distributions.

Evaluating the Scale Dependence of Biodiversity-productivity Relationships: A Case Study in Mountain Meadow Habitat

2021 ◽  
Author(s):  
Jiajia Liu ◽  
Xue-Jun Ge
Keyword(s):  
Structural Equation ◽  
Abiotic Factors ◽  
Regional Scale ◽  
Chemical Properties ◽  
Elevational Gradient ◽  
Equation Model ◽  
Equation Modeling ◽  
Scale Dependency ◽  
Ecological Communities ◽  
Natural Habitats

Abstract Ecological scale has been widely assumed to influence various biodiversity-productivity relationships in ecological communities; however, its robustness has not been extensively studied. In this study, we tested the scale dependency of biodiversity-productivity relationships by evaluating their direct linkages while considering other confounders, and simultaneously incorporating functional traits and interspecific phylogenetic relationships. We surveyed sixty quadrats each with an area of 0.25 m2 in three different meadows located along an elevational gradient in Yulong Mountain, China. We calculated different biodiversity parameters (richness, evenness, functionality, and phylogeny), and evaluated the chemical properties of soil from all quadrats, correlating their relationships with plant productivity at the local and regional scale. The direct and indirect relationships of biodiversity and productivity were evaluated using structural equation modeling. The biodiversity-productivity relationships were weak and inconsistent at the local scale, whereas some biodiversity metrics (richness, functional, and phylogenetic) showed either strong positive or negative relationships with productivity at the regional scale. However, a direct correlation between productivity and variables such as soil pH and community-weighted mean leaf carbon content was observed in the structural equation model reconstructed. Our study indicates that the scale dependency of biodiversity-productivity relationships in natural habitats may not be as strong as it may have been previously perceived, in case of taxonomic, functional, and phylogenetic diversity, respectively. Our study emphasizes the necessity to account for the confounding effects of abiotic factors when evaluating biodiversity-productivity relationship in natural habitats at regional or even worldwide scales.

scholarly journals Interaction between Fungal Communities, Soil Properties, and the Survival of Invading E. coli O157:H7 in Soils

2020 ◽  
Vol 17 (10) ◽  
pp. 3516 ◽  
Author(s):  
Guannan Huang ◽  
Jiafen Liao ◽  
Ziming Han ◽  
Jiahang Li ◽  
Liyue Zhu ◽  
...  
Keyword(s):  
Soil Properties ◽  
Bacterial Communities ◽  
Structural Equation ◽  
Equation Model ◽  
Water Soluble ◽  
Fungal Communities ◽  
Human Beings ◽  
Human Pathogens ◽  
Bacterial Phyla ◽  
Log Reduction

Pathogens that invade into the soil cancontaminate food and water, andinfect animals and human beings. It is well documented that individual bacterial phyla are well correlated with the survival of E. coliO157 (EcO157), while the interaction betweenthe fungal communities and EcO157 survival remains largely unknown. In this study, soil samples from Tongliao, Siping, and Yanji in northeast China were collected and characterized. Total DNA was extracted for fungal and bacterial community characterization. EcO157 cells were spiked into the soils, and their survival behavior was investigated. Results showed that both fungal and bacterial communities were significantly correlated (p < 0.01) with the survival of EcO157 in soils, and the relative abundances of fungal groups (Dothideomycetes and Sordariomycetes) and some bacterial phyla (Acidobacteria, Firmicutes, gamma- and delta-Proteobacteria)weresignificantly correlated with ttds (p < 0.01). Soil pH, EC (electric conductance) salinity, and water-soluble nitrate nitrogen were significantly correlated with survival time (time to reach the detection limit, ttd) (p < 0.05). The structural equation model indicated that fungal communities could directly influence ttds, and soil properties could indirectly influence the ttds through fungal communities. The first log reduction time (δ) was mainly correlated with soil properties, while the shape parameter (p) was largely correlated with fungal communities. Our data indicated that both fungal and bacterial communities were closely correlated (p < 0.05)with the survival of EcO157 in soils, and different fungal and bacterial groups might play different roles. Fungal communities and bacterial communities explained 5.87% and 17.32% of the overall variation of survival parameters, respectively. Soil properties explained about one-third of the overall variation of survival parameters. These findings expand our current understanding of the environmental behavior of human pathogens in soils.

Application of Structural Equation Model for Exploring the influence of Environmental Factors on Phytoplankton in Bohai Bay

2011 ◽  
Vol 347-353 ◽  
pp. 1832-1835
Author(s):  
Xiao Fu Xu ◽  
Jian Hua Tao
Keyword(s):  
Structural Equation Model ◽  
Physical Environment ◽  
Phytoplankton Biomass ◽  
Structural Equation ◽  
Inorganic Nitrogen ◽  
Abiotic Factors ◽  
Equation Model ◽  
Bohai Bay ◽  
Dissolved Inorganic Nitrogen ◽  
Environment Temperature

In this paper, structural equation model (SEM) is used to explore the influence of coastal environment factors on phytoplankton in Bohai Bay. The SEM is a multivariate statistical method and by using it, a researcher can construct theoretical concepts, test their measurement reliability, hypothesize and evaluate of a network of relationships between variables. In our study, the hypothesized model considered the influence of the physical environment (temperature, salinity, and PH) and nitrogen (total dissolved inorganic nitrogen, total dissolved inorganic phosphate, and silicate) on total phytoplankton biomass. With the conclusions of this model, we find that nutrients have greater effect on phytoplankton biomass and there is a strong correlation between nutrients and physical environment. Additionally, salinity has greatest positive effect on phytoplankton, whereas total dissolved inorganic nitrogen has the greatest negative effect. Generally, the SEM gave plausible results and enabled the identification of the role of the abiotic factors on the phytoplankton.

scholarly journals Gut Microbial Succession Follows Acute Secretory Diarrhea in Humans

mBio ◽  
2015 ◽  
Vol 6 (3) ◽  
Author(s):  
Lawrence A. David ◽  
Ana Weil ◽  
Edward T. Ryan ◽  
Stephen B. Calderwood ◽  
Jason B. Harris ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Bacterial Communities ◽  
Diarrheal Disease ◽  
Secretory Diarrhea ◽  
Infectious Diarrhea ◽  
Microbial Succession ◽  
Ecological Processes ◽  
Bacterial Populations ◽  
Content Type ◽  
Carbohydrate Levels

ABSTRACTDisability after childhood diarrhea is an important burden on global productivity. Recent studies suggest that gut bacterial communities influence how humans recover from infectious diarrhea, but we still lack extensive data and mechanistic hypotheses for how these bacterial communities respond to diarrheal disease and its treatment. Here, we report that afterVibrio choleraeinfection, the human gut microbiota undergoes an orderly and reproducible succession that features transient reversals in relative levels of entericBacteroidesandPrevotella. Elements of this succession may be a common feature in microbiota recovery from acute secretory diarrhea, as we observed similar successional dynamics after enterotoxigenicEscherichia coli(ETEC) infection. Our metagenomic analyses suggest that multiple mechanisms drive microbial succession after cholera, including bacterial dispersal properties, changing enteric oxygen and carbohydrate levels, and phage dynamics. Thus, gut microbiota recovery after cholera may be predictable at the level of community structure but is driven by a complex set of temporally varying ecological processes. Our findings suggest opportunities for diagnostics and therapies targeting the gut microbiota in humans recovering from infectious diarrhea.IMPORTANCEDisability after diarrhea is a major burden on public health in the developing world. Gut bacteria may affect this recovery, but it remains incompletely understood how resident microbes in the digestive tract respond to diarrheal illness. Here, we observed an orderly and reproducible succession of gut bacterial groups after cholera in humans. Genomic analyses associated the succession with bacterial dispersal in food, an altered microbial environment, and changing phage levels. Our findings suggest that it may one day be feasible to manage resident bacterial populations in the gut after infectious diarrhea.

Idiographic Dynamics of Positive Affect in GAD

2020 ◽  
Vol 36 (3) ◽  
pp. 500-509
Author(s):  
Hannah G. Bosley ◽  
Devon B. Sandel ◽  
Aaron J. Fisher
Keyword(s):  
Positive Affect ◽  
Structural Equation ◽  
Alternative Hypothesis ◽  
Equation Model ◽  
Aggregated Data ◽  
Regulatory Strategy ◽  
Constant State ◽  
Automatic Search ◽  
Time Lagged ◽  
Exploratory Procedure

Abstract. Generalized anxiety disorder (GAD) is associated with worry and emotion regulation difficulties. The contrast-avoidance model suggests that individuals with GAD use worry to regulate emotion: by worrying, they maintain a constant state of negative affect (NA), avoiding a feared sudden shift into NA. We tested an extension of this model to positive affect (PA). During a week-long ecological momentary assessment (EMA) period, 96 undergraduates with a GAD analog provided four daily measurements of worry, dampening (i.e., PA suppression), and PA. We hypothesized a time-lagged mediation relationship in which higher worry predicts later dampening, and dampening predicts subsequently lower PA. A lag-2 structural equation model was fit to the group-aggregated data and to each individual time-series to test this hypothesis. Although worry and PA were negatively correlated in 87 participants, our model was not supported at the nomothetic level. However, idiographically, our model was well-fit for about a third (38.5%) of participants. We then used automatic search as an idiographic exploratory procedure to detect other time-lagged relationships between these constructs. While 46 individuals exhibited some cross-lagged relationships, no clear pattern emerged across participants. An alternative hypothesis about the speed of the relationship between variables is discussed using contemporaneous correlations of worry, dampening, and PA. Findings suggest heterogeneity in the function of worry as a regulatory strategy, and the importance of temporal scale for detection of time-lagged effects.

Differential Item Functioning in Brief Instruments of Disordered Eating

2019 ◽  
Vol 35 (6) ◽  
pp. 823-833 ◽  
Author(s):  
Desiree Thielemann ◽  
Felicitas Richter ◽  
Bernd Strauss ◽  
Elmar Braehler ◽  
Uwe Altmann ◽  
...  
Keyword(s):  
Differential Item Functioning ◽  
Disordered Eating ◽  
Structural Equation ◽  
Young Female ◽  
Eating Attitudes ◽  
Equation Model ◽  
German Population ◽  
Test Fairness ◽  
Item Functioning ◽  
Multiple Indicator

Abstract. Most instruments for the assessment of disordered eating were developed and validated in young female samples. However, they are often used in heterogeneous general population samples. Therefore, brief instruments of disordered eating should assess the severity of disordered eating equally well between individuals with different gender, age, body mass index (BMI), and socioeconomic status (SES). Differential item functioning (DIF) of two brief instruments of disordered eating (SCOFF, Eating Attitudes Test [EAT-8]) was modeled in a representative sample of the German population ( N = 2,527) using a multigroup item response theory (IRT) and a multiple-indicator multiple-cause (MIMIC) structural equation model (SEM) approach. No DIF by age was found in both questionnaires. Three items of the EAT-8 showed DIF across gender, indicating that females are more likely to agree than males, given the same severity of disordered eating. One item of the EAT-8 revealed slight DIF by BMI. DIF with respect to the SCOFF seemed to be negligible. Both questionnaires are equally fair across people with different age and SES. The DIF by gender that we found with respect to the EAT-8 as screening instrument may be also reflected in the use of different cutoff values for men and women. In general, both brief instruments assessing disordered eating revealed their strengths and limitations concerning test fairness for different groups.

The Influence of Cognitive and Affective Reactions to Feedback on Subsequent Goals

2010 ◽  
Vol 15 (2) ◽  
pp. 121-131 ◽  
Author(s):  
Remus Ilies ◽  
Timothy A. Judge ◽  
David T. Wagner
Keyword(s):  
Performance Feedback ◽  
Business School ◽  
Structural Equation ◽  
Emotional Reactions ◽  
Equation Model ◽  
Proposed Model ◽  
And Performance ◽  
Dispositional Measure ◽  
The Relationship ◽  
Reactions To Feedback

This paper focuses on explaining how individuals set goals on multiple performance episodes, in the context of performance feedback comparing their performance on each episode with their respective goal. The proposed model was tested through a longitudinal study of 493 university students’ actual goals and performance on business school exams. Results of a structural equation model supported the proposed conceptual model in which self-efficacy and emotional reactions to feedback mediate the relationship between feedback and subsequent goals. In addition, as expected, participants’ standing on a dispositional measure of behavioral inhibition influenced the strength of their emotional reactions to negative feedback.

Forced Zero Cross-Loading Misspecifications in Measurement Component of Structural Equation Models

Methodology ◽  
2014 ◽  
Vol 10 (4) ◽  
pp. 138-152 ◽  
Author(s):  
Hsien-Yuan Hsu ◽  
Susan Troncoso Skidmore ◽  
Yan Li ◽  
Bruce Thompson
Keyword(s):  
Structural Equation ◽  
Structural Model ◽  
Structural Equation Models ◽  
Equation Model ◽  
Model Fit ◽  
Model Specification ◽  
Simulation Design ◽  
Measurement Models ◽  
Fit Statistics ◽  
Path Coefficients

The purpose of the present paper was to evaluate the effect of constraining near-zero parameter cross-loadings to zero in the measurement component of a structural equation model. A Monte Carlo 3 × 5 × 2 simulation design was conducted (i.e., sample sizes of 200, 600, and 1,000; parameter cross-loadings of 0.07, 0.10, 0.13, 0.16, and 0.19 misspecified to be zero; and parameter path coefficients in the structural model of either 0.50 or 0.70). Results indicated that factor pattern coefficients and factor covariances were overestimated in measurement models when near-zero parameter cross-loadings constrained to zero were higher than 0.13 in the population. Moreover, the path coefficients between factors were misestimated when the near-zero parameter cross-loadings constrained to zero were noteworthy. Our results add to the literature detailing the importance of testing individual model specification decisions, and not simply evaluating omnibus model fit statistics.

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