scholarly journals EXPERIMENTAL EVOLUTION OF FEMALE TRAITS UNDER DIFFERENT LEVELS OF INTERSEXUAL CONFLICT INDROSOPHILA MELANOGASTER

Evolution ◽  
2013 ◽  
Vol 68 (2) ◽  
pp. 412-425 ◽  
Author(s):  
B. Nandy ◽  
V. Gupta ◽  
N. Udaykumar ◽  
M. A. Samant ◽  
S. Sen ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Intersexual Conflict ◽  
Different Levels

scholarly journals History, chance and selection during phenotypic and genomic experimental evolution: replaying the tape of life at different levels

2015 ◽  
Vol 6 ◽  
Author(s):  
Margarida Matos ◽  
Pedro Simões ◽  
Marta A. Santos ◽  
Sofia G. Seabra ◽  
Gonçalo S. Faria ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Different Levels

scholarly journals Experimental evolution to identify undescribed mechanisms of resistance to a novel cationic peptide antibiotic

2020 ◽  
Author(s):  
Alfonso Santos Lopez ◽  
Melissa J Fritz ◽  
Jeffrey Lombardo ◽  
Ansen HP Burr ◽  
Victoria A Heinrich ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Antimicrobial Properties ◽  
New Drugs ◽  
Peptide Antibiotic ◽  
Mechanisms Of Resistance ◽  
Cationic Antimicrobial Peptide ◽  
Gram Positive Bacteria ◽  
Single Target ◽  
New Antibiotics ◽  
Different Levels

A key strategy for resolving the antibiotic resistance crisis is the development of new drugs with antimicrobial properties. The engineered cationic antimicrobial peptide WLBU2 (also known as PLG0206) is a promising broad-spectrum antimicrobial compound that has completed Phase I clinical studies. It has activity against Gram-negative and Gram-positive bacteria including infections associated with biofilm. No definitive mechanisms of resistance to WLBU2 have been identified. Here, we used experimental evolution under different levels of mutation supply and whole genome sequencing (WGS) to detect the genetic pathways and probable mechanisms of resistance to this peptide. We propagated populations of wild-type and mutator Pseudomonas aeruginosa in the presence of WLBU2 and performed WGS of evolved populations and clones. Populations that survived WLBU2 treatment acquired a minimum of two mutations, making the acquisition of resistance more difficult than for most antibiotics, which can be tolerated by mutation of a single target. Major targets of resistance to WLBU2 included the orfN and pmrB genes, previously described to confer resistance to other cationic peptides. More surprisingly, mutations that increase aggregation such as the wsp pathway were also selected despite the ability of WLBU2 to kill cells growing in a biofilm. The results show how the experimental evolution and WGS can identify genetic targets and actions of new antimicrobial compounds and predict pathways to resistance of new antibiotics in clinical practice. 

scholarly journals Patterns of selection reveal shared molecular targets over short and long evolutionary timescales

2017 ◽  
Author(s):  
Jing Li ◽  
Ignacio Vázquez-García ◽  
Karl Persson ◽  
Asier González ◽  
Jia-Xing Yue ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Genetic Variants ◽  
Environmental Changes ◽  
De Novo ◽  
Functional Divergence ◽  
Molecular Targets ◽  
Time Resolved ◽  
Standing Variation ◽  
Dynamic View ◽  
Different Levels

AbstractStanding and de novo genetic variants can both drive adaptation to environmental changes, but their relative contributions and interplay remain poorly understood. Here we investigated the dynamics of drug adaptation in yeast populations with different levels of standing variation by experimental evolution coupled with time-resolved sequencing and phenotyping. We found a doubling of standing variation alone boost the adaptation by 64.1% and 51.5% in hydroxyuea and rapamycin respectively. The causative standing and de novo variants were selected on shared targets of RNR4 in hydroxyurea and TOR1, TOR2 in rapamycin. The standing and de novo TOR variants map to different functional domains and act via distinct mechanisms. Interestingly, standing TOR variants from two domesticated strains exhibited opposite resistance effects, reflecting lineage-specific functional divergence. This study provides a dynamic view on how standing and de novo variants interactively drive adaptation and deepens our understanding of clonally evolving diseases.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Immunoenzymatic demonstration of the simultaneous presence of transferrin, hemopexin and albumin in a same hepatocyte and their ultrastructural localization

1978 ◽  
Vol 36 (2) ◽  
pp. 88-89
Author(s):  
M. Kraemer ◽  
J. Foucrier ◽  
J. Vassy ◽  
M.T. Chalumeau
Keyword(s):  
Plasma Proteins ◽  
Rat Hepatocytes ◽  
Ultrastructural Localization ◽  
Carrier Proteins ◽  
Normal Cells ◽  
Adult Rat ◽  
Adult Rat Hepatocytes ◽  
Monospecific Antisera ◽  
Different Levels

Some authors using immunofluorescent techniques had already suggested that some hepatocytes are able to synthetize several plasma proteins. In vitro studies on normal cells or on cells issued of murine hepatomas raise the same conclusion. These works could be indications of an hepatocyte functionnal non-specialization, meanwhile the authors never give direct topographic proofs suitable with this hypothesis.The use of immunoenzymatic techniques after obtention of monospecific antisera had seemed to us useful to bring forward a better knowledge of this problem. We have studied three carrier proteins (transferrin = Tf, hemopexin = Hx, albumin = Alb) operating at different levels in iron metabolism by demonstrating and localizing the adult rat hepatocytes involved in their synthesis.Immunological, histological and ultrastructural methods have been described in a previous work.

Memory Processes, Aging, Cognitive Decline, and Neurodegenerative Diseases

2006 ◽  
Vol 11 (4) ◽  
pp. 304-311 ◽  
Author(s):  
Lars-Göran Nilsson
Keyword(s):  
Cognitive Impairment ◽  
Cognitive Decline ◽  
Neurodegenerative Disease ◽  
Genetic Markers ◽  
Brain Activity ◽  
Memory Performance ◽  
Modeling And Simulations ◽  
Aging And Health ◽  
Explained Variance ◽  
Different Levels

This paper presents four domains of markers that have been found to predict later cognitive impairment and neurodegenerative disease. These four domains are (1) data patterns of memory performance, (2) cardiovascular factors, (3) genetic markers, and (4) brain activity. The critical features of each domain are illustrated with data from the longitudinal Betula Study on memory, aging, and health ( Nilsson et al., 1997 ; Nilsson et al., 2004 ). Up to now, early signs regarding these domains have been examined one by one and it has been found that they are associated with later cognitive impairment and neurodegenerative disease. However, it was also found that each marker accounts for only a very small part of the total variance, implying that single markers should not be used as predictors for cognitive decline or neurodegenerative disease. It is discussed whether modeling and simulations should be used as tools to combine markers at different levels to increase the amount of explained variance.

Implications of Person Fluctuation for the Stability and Validity of Test Scores

Methodology ◽  
2006 ◽  
Vol 2 (4) ◽  
pp. 142-148 ◽  
Author(s):  
Pere J. Ferrando
Keyword(s):  
Item Response ◽  
Test Scores ◽  
Temporal Stability ◽  
Person Fit ◽  
Item Parameters ◽  
Individual Trait ◽  
The Stability ◽  
The Individual ◽  
Different Levels ◽  
Fluctuation Model

In the IRT person-fluctuation model, the individual trait levels fluctuate within a single test administration whereas the items have fixed locations. This article studies the relations between the person and item parameters of this model and two central properties of item and test scores: temporal stability and external validity. For temporal stability, formulas are derived for predicting and interpreting item response changes in a test-retest situation on the basis of the individual fluctuations. As for validity, formulas are derived for obtaining disattenuated estimates and for predicting changes in validity in groups with different levels of fluctuation. These latter formulas are related to previous research in the person-fit domain. The results obtained and the relations discussed are illustrated with an empirical example.

The Emergence and Maintenance of Ethical Leadership in Organizations

2012 ◽  
Vol 11 (1) ◽  
pp. 7-19 ◽  
Author(s):  
Silke Astrid Eisenbeiß ◽  
Steffen R. Giessner
Keyword(s):  
Cultural Values ◽  
Ethical Leadership ◽  
Leadership Behavior ◽  
Peer Group ◽  
Organizational Characteristics ◽  
Future Research ◽  
Environmental Complexity ◽  
Group Influence ◽  
Analysis Society ◽  
Different Levels

The present paper gives a review of empirical research on ethical leadership and shows that still little is known known about the contextual antecedents of ethical leadership. To address this important issue, a conceptual framework is developed that analyzes the embeddedness of organizational ethical leadership. This framework identifies manifest and latent contextual factors on three different levels of analysis – society, industry, and organization – which can affect the development and maintenance of ethical leadership. In particular, propositions are offered about how (1) societal characteristics, notably the implementation and the spirit of human rights in a society and societal cultural values of responsibility, justice, humanity, and transparency; (2) industry characteristics such as environmental complexity, the content of the organizational mandate, and the interests of stakeholder networks; and (3) intra-organizational characteristics, including the organizational ethical infrastructure and the ethical leadership behavior of a leader’s peer group, influence the development and maintenance of ethical leadership in organizations. This list of factors is not exhaustive, but illustrates how the three levels may impact ethical leadership. Implications for managerial practice and future research are discussed.

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