scholarly journals Hidden paths to endless forms most wonderful: Ecology latently shapes evolution of multicellular development in predatory bacteria

2021 ◽  
Author(s):  
Marco La Fortezza ◽  
Olaya Rendueles ◽  
Heike Keller ◽  
Gregory Jon Velicer
Keyword(s):  
Soft Agar ◽  
Life Cycles ◽  
Multicellular Development ◽  
Surface Stiffness ◽  
Predatory Bacteria ◽  
Evolution Experiment ◽  
Developmental Phases ◽  
Open Question ◽  
Evo Devo

Ecological causes of developmental-system evolution, for example from predation, remain under intense investigation. An important open question is the role of latent phenotypes in eco-evo-devo. The predatory bacterium Myxococcus xanthus undergoes aggregative multicellular development upon starvation. Here we use M. xanthus to test whether evolution in several distinct growth environments that do not induce development latently alters developmental phenotypes, including morphology and plasticity, in environments that do induce development. In the MyxoEE-3 evolution experiment, growing M. xanthus populations swarmed across agar surfaces while adapting to distinct conditions varying at factors such as surface stiffness or prey identity. All examined developmental phenotypes underwent extensive and ecologically specific latent evolution, with surface stiffness, prey presence and prey identity all strongly impacting the latent evolution of development. Evolution on hard agar allowed retention of developmental proficiency and extensive stochastic phenotypic radiation, including of reaction norms, with instances of both increased plasticity and canalization. In contrast, evolution on soft agar latently led to systematic loss of development, revealing an ecologically-contingent fitness trade-off between the growth and developmental phases of a multicellular life cycle that is likely determined by details of motility behavior. Similar contingency was observed after evolution during predatory growth in distinct prey environments, with Bacillus subtilis causing greater loss of development and lower stochastic diversification than Escherichia coli. Our results have implications for understanding evolutionary interactions among predation, development and motility in myxobacterial life cycles, and, more broadly, the importance of latent phenotypes for the diversification of developmental systems.

scholarly journals Dynamic structures in evo-devo: From morphogenetic fields to evolving organisms

2021 ◽  
Author(s):  
Johannes Jaeger
Keyword(s):  
Active Role ◽  
Life Cycles ◽  
Evolutionary Change ◽  
Phenotypic Change ◽  
Agent Based ◽  
Theory Of Evolution ◽  
Dynamic Structures ◽  
Evo Devo ◽  
Morphogenetic Fields

Evolution does not act on particular stages in the life of an organism. Instead, it alters developmental processes and life cycles in response to environmental conditions to bring about phenotypic change. The structure of these processes determines evolvability, the capacity of organisms to adapt. These structures are intrinsically dynamic. The organisational principles underlying organisms and the morphogenetic fields that constitute their ontogeny actively remodel themselves over time. How this occurs, and how it influences the rate and direction of evolutionary change, are central questions for biology. They lead us to fundamentally reconsider the active role of organisms in evolutionary change, which raises the possibility of a new agent-based theory of evolution in which organisms and their perceived environments co-construct each other in a radically innovative dialectic dynamic.

scholarly journals hfqPlays Important Roles in Virulence and Stress Adaptation in Cronobacter sakazakii ATCC 29544

2015 ◽  
Vol 83 (5) ◽  
pp. 2089-2098 ◽  
Author(s):  
Seongok Kim ◽  
Hyelyeon Hwang ◽  
Kwang-Pyo Kim ◽  
Hyunjin Yoon ◽  
Dong-Hyun Kang ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Soft Agar ◽  
Host Cells ◽  
Neonatal Meningitis ◽  
Animal Cells ◽  
Content Type ◽  
Flagellar Biosynthesis

Cronobacterspp. are opportunistic pathogens that cause neonatal meningitis and sepsis with high mortality in neonates. Despite the peril associated withCronobacterinfection, the mechanisms of pathogenesis are still being unraveled. Hfq, which is known as an RNA chaperone, participates in the interaction with bacterial small RNAs (sRNAs) to regulate posttranscriptionally the expression of various genes. Recent studies have demonstrated that Hfq contributes to the pathogenesis of numerous species of bacteria, and its roles are varied between bacterial species. Here, we tried to elucidate the role of Hfq inC. sakazakiivirulence. In the absence ofhfq,C. sakazakiiwas highly attenuated in disseminationin vivo, showed defects in invasion (3-fold) into animal cells and survival (103-fold) within host cells, and exhibited low resistance to hydrogen peroxide (102-fold). Remarkably, the loss ofhfqled to hypermotility on soft agar, which is contrary to what has been observed in other pathogenic bacteria. The hyperflagellated bacteria were likely to be attributable to the increased transcription of genes associated with flagellar biosynthesis in a strain lackinghfq. Together, these data strongly suggest thathfqplays important roles in the virulence ofC. sakazakiiby participating in the regulation of multiple genes.

scholarly journals The distribution of myosin II in Dictyostelium discoideum slug cells.

1991 ◽  
Vol 115 (5) ◽  
pp. 1267-1274 ◽  
Author(s):  
S Eliott ◽  
P H Vardy ◽  
K L Williams
Keyword(s):  
Cell Motility ◽  
Dictyostelium Discoideum ◽  
Immunofluorescence Microscopy ◽  
Molecular Genetic ◽  
Myosin Ii ◽  
Three Dimensional ◽  
Homogeneous Distribution ◽  
Multicellular Development ◽  
Insight Into

While the role of myosin II in muscle contraction has been well characterized, less is known about the role of myosin II in non-muscle cells. Recent molecular genetic experiments on Dictyostelium discoideum show that myosin II is necessary for cytokinesis and multicellular development. Here we use immunofluorescence microscopy with monoclonal and polyclonal antimyosin antibodies to visualize myosin II in cells of the multicellular D. discoideum slug. A subpopulation of peripheral and anterior cells label brightly with antimyosin II antibodies, and many of these cells display a polarized intracellular distribution of myosin II. Other cells in the slug label less brightly and their cytoplasm displays a more homogeneous distribution of myosin II. These results provide insight into cell motility within a three-dimensional tissue and they are discussed in relation to the possible roles of myosin II in multicellular development.

Health determinants in Canadian northern environmental impact assessment

Polar Record ◽  
2006 ◽  
Vol 42 (4) ◽  
pp. 315-324 ◽  
Author(s):  
Jackie Bronson ◽  
Bram F. Noble
Keyword(s):  
Decision Making ◽  
Environmental Impact ◽  
Impact Assessment ◽  
Environmental Impact Assessment ◽  
Health Impact ◽  
Life Cycles ◽  
Local Context ◽  
Health Determinants ◽  
Limited Attention

The need to address the human health implications of northern development is well founded, and the role of health determinants in environmental impact assessment is increasingly recognised; however, there is limited understanding of the nature of health determinants and current practices in northern project assessment and decision making. This paper reports on a study of the nature and use of health determinants in Canadian northern environmental impact assessment, and discusses the key challenges to, and opportunities for, improved practice. Four themes emerged from this study. First, the consideration of health is limited to physical environments and the physical determinants of health, with limited attention to broader social and cultural health determinants. Second, when health is considered in northern project impact assessments such considerations rarely carry forward to post-project approval monitoring of health determinants and evaluation of health impact management programmes. Third, while there is general consensus that health determinants should be an integral part of northern impact assessment, there exist different expectations of the role of health determinants in project evaluation and decision making due in large part to different understandings and interpretations of health. Finally, a broader conceptualisation of health and health determinants in northern environmental impact assessment is required; one that takes into consideration northern cultures and knowledge systems, and is adaptive to local context, geography and life cycles.

scholarly journals Ralstonia solanacearum Needs Motility for Invasive Virulence on Tomato

2001 ◽  
Vol 183 (12) ◽  
pp. 3597-3605 ◽  
Author(s):  
Julie Tans-Kersten ◽  
Huayu Huang ◽  
Caitilyn Allen
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Soft Agar ◽  
Cell Protein ◽  
In Planta ◽  
Tomato Plants ◽  
Bacterial Wilt Disease ◽  
Virulence Assay ◽  
Flagellar Filament

ABSTRACT Ralstonia solanacearum, a widely distributed and economically important plant pathogen, invades the roots of diverse plant hosts from the soil and aggressively colonizes the xylem vessels, causing a lethal wilting known as bacterial wilt disease. By examining bacteria from the xylem vessels of infected plants, we found thatR. solanacearum is essentially nonmotile in planta, although it can be highly motile in culture. To determine the role of pathogen motility in this disease, we cloned, characterized, and mutated two genes in the R. solanacearum flagellar biosynthetic pathway. The genes for flagellin, the subunit of the flagellar filament (fliC), and for the flagellar motor switch protein (fliM) were isolated based on their resemblance to these proteins in other bacteria. As is typical for flagellins, the predicted FliC protein had well-conserved N- and C-terminal regions, separated by a divergent central domain. The predicted R. solanacearum FliM closely resembled motor switch proteins from other proteobacteria. Chromosomal mutants lackingfliC or fliM were created by replacing the genes with marked interrupted constructs. Since fliM is embedded in the fliLMNOPQR operon, the aphAcassette was used to make a nonpolar fliM mutation. Both mutants were completely nonmotile on soft agar plates, in minimal broth, and in tomato plants. The fliC mutant lacked flagella altogether; moreover, sheared-cell protein preparations from the fliC mutant lacked a 30-kDa band corresponding to flagellin. The fliM mutant was usually aflagellate, but about 10% of cells had abnormal truncated flagella. In a biologically representative soil-soak inoculation virulence assay, both nonmotile mutants were significantly reduced in the ability to cause disease on tomato plants. However, the fliC mutant had wild-type virulence when it was inoculated directly onto cut tomato petioles, an inoculation method that did not require bacteria to enter the intact host from the soil. These results suggest that swimming motility makes its most important contribution to bacterial wilt virulence in the early stages of host plant invasion and colonization.

scholarly journals From Culture 1.0 to Culture 3.0: Three Socio-Technical Regimes of Social and Economic Value Creation through Culture, and Their Impact on European Cohesion Policies

2018 ◽  
Vol 10 (11) ◽  
pp. 3923 ◽  
Author(s):  
Pier Sacco ◽  
Guido Ferilli ◽  
Giorgio Tavano Blessi
Keyword(s):  
Cultural Production ◽  
Value Creation ◽  
Cultural Policy ◽  
Policy Design ◽  
Economic Value ◽  
Cultural Participation ◽  
Social Value Creation ◽  
Open Question ◽  
The Relationship

We develop a new conceptual framework to analyze the evolution of the relationship between cultural production and different forms of economic and social value creation in terms of three alternative socio-technical regimes that have emerged over time. We show how, with the emergence of the Culture 3.0 regime characterized by novel forms of active cultural participation, where the distinction between producers and users of cultural and creative contents is increasingly blurred, new channels of social and economic value creation through cultural participation acquire increasing importance. We characterize them through an eight-tier classification, and argue on this basis why cultural policy is going to acquire a central role in the policy design approaches of the future. Whether Europe will play the role of a strategic leader in this scenario in the context of future cohesion policies is an open question.

scholarly journals Oncogenic Role of Epstein-Barr Virus-Encoded RNAs in Burkitt’s Lymphoma Cell Line Akata

1999 ◽  
Vol 73 (12) ◽  
pp. 9827-9831 ◽  
Author(s):  
Jun Komano ◽  
Seiji Maruo ◽  
Koichi Kurozumi ◽  
Takanori Oda ◽  
Kenzo Takada
Keyword(s):  
Cell Line ◽  
Small Rnas ◽  
Epstein Barr Virus ◽  
Burkitt’S Lymphoma ◽  
Soft Agar ◽  
Burkitt's Lymphoma ◽  
Malignant Phenotype ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Our previous reports indicated that Epstein-Barr virus (EBV) contributes to the malignant phenotype and resistance to apoptosis in Burkitt’s lymphoma (BL) cell line Akata (N. Shimizu, A. Tanabe-Tochikura, Y. Kuroiwa, and K. Takada, J. Virol. 68:6069–6073, 1994; J. Komano, M. Sugiura, and K. Takada, J. Virol. 72:9150–9156, 1998). Here we report that the EBV-encoded small RNAs (EBERs) are responsible for these phenotypes. Transfection of the EBER genes into EBV-negative Akata clones restored the capacity for growth in soft agar, tumorigenicity in SCID mice, resistance to apoptotic inducers, and upregulated expression of bcl-2 oncoprotein that were originally retained in parental EBV-positive Akata cells and lost in EBV-negative subclones. This is the first report which provides evidence that virus-encoded RNAs (EBERs) have oncogenic functions in BL cells.

The Development of Social Capital in Different life Cycles of Tunisian Agritourism Entrepreneur

2021 ◽  
Author(s):  
Nesrine Khazami ◽  
Zoltan Lakner
Keyword(s):  
Social Capital ◽  
Risk Analysis ◽  
Family Business ◽  
Concept Formation ◽  
Life Cycles ◽  
Remote Areas ◽  
Phases Of Development ◽  
Early Phases

Abstract The role of social capital in the early phases of development of a family business is well documented, but the dynamism of the entrepreneur's social capital in the agritourism business remains is relatively lesser studied area. The current research on an inductive, exploratory, and qualitative base aims to uncover the place and role of social capital in the establishment of agritourism enterprise, from concept formation to stabilisation. Results of the study highlight the importance of governmental help in financial and networking help for launching the enterprise especially in remote areas, where these additional activities are relatively lesser known. The role of the network is relatively weak in the risk analysis of the business. This fact enhances the vulnerability of enterprises.

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