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Sample records for fibroblasts self-direct multicellular

  1. Cardiac fibroblasts support endothelial cell proliferation and sprout formation but not the development of multicellular sprouts in a fibrin gel co-culture model.

    PubMed

    Twardowski, Rachel L; Black, Lauren D

    2014-05-01

    A primary impediment to cardiac tissue engineering lies in the inability to adequately vascularize the constructs to optimize survival upon implantation. During normal angiogenesis, endothelial cells (ECs) require a support cell to form mature patent lumens and it has been demonstrated that pericytes, vascular smooth muscle cells and mesenchymal stem cells (MSCs) are all able to support the formation of mature vessels. In the heart, cardiac fibroblasts (CFs) provide important electrical and mechanical functions, but to date have not been sufficiently studied for their role in angiogenesis. To study CFs role in angiogenesis, we co-cultured different concentrations of various cell types in fibrin hemispheres with appropriate combinations of their specific media, to determine the optimal conditions for EC growth and sprout formation through DNA analysis, flow cytometry and immunohistology. ECs proliferated best when co-cultured with CFs and analysis of immunohistological images demonstrated that ECs formed the longest and most numerous sprouts with CFs as compared to MSCs. However, ECs were able to produce more multicellular sprouts when in culture with the MSCs. Moreover, these effects were dependent on the ratio of support cell to EC in co-culture. Overall, CFs provide a good support system for EC proliferation and sprout formation; however, MSCs allow for more multicellular sprouts, which is more indicative of the in vivo process.

  2. Synthetic multicellularity.

    PubMed

    Maharbiz, Michel M

    2012-12-01

    The ability to synthesize biological constructs on the scale of the organisms we observe unaided is probably one of the more outlandish, yet recurring, dreams humans have had since they began to modify genes. This review brings together recent developments in synthetic biology, cell and developmental biology, computation, and technological development to provide context and direction for the engineering of rudimentary, autonomous multicellular ensembles.

  3. Self-Directed Workplace Learning.

    ERIC Educational Resources Information Center

    1998

    This document contains four papers from a symposium on self-directed workplace learning. "Self-Directed Work Teams: Implementation and Performance" (Marcel van der Klink, Hilde ter Horst) discusses the results of a study examining the implementation and effects of self-directed work teams in a land register office and the role of the…

  4. Stabilizing multicellularity through ratcheting

    PubMed Central

    Libby, Eric; Conlin, Peter L.; Kerr, Ben; Ratcliff, William C.

    2016-01-01

    The evolutionary transition to multicellularity probably began with the formation of simple undifferentiated cellular groups. Such groups evolve readily in diverse lineages of extant unicellular taxa, suggesting that there are few genetic barriers to this first key step. This may act as a double-edged sword: labile transitions between unicellular and multicellular states may facilitate the evolution of simple multicellularity, but reversion to a unicellular state may inhibit the evolution of increased complexity. In this paper, we examine how multicellular adaptations can act as evolutionary ‘ratchets’, limiting the potential for reversion to unicellularity. We consider a nascent multicellular lineage growing in an environment that varies between favouring multicellularity and favouring unicellularity. The first type of ratcheting mutations increase cell-level fitness in a multicellular context but are costly in a single-celled context, reducing the fitness of revertants. The second type of ratcheting mutations directly decrease the probability that a mutation will result in reversion (either as a pleiotropic consequence or via direct modification of switch rates). We show that both types of ratcheting mutations act to stabilize the multicellular state. We also identify synergistic effects between the two types of ratcheting mutations in which the presence of one creates the selective conditions favouring the other. Ratcheting mutations may play a key role in diverse evolutionary transitions in individuality, sustaining selection on the new higher-level organism by constraining evolutionary reversion. This article is part of the themed issue ‘The major synthetic evolutionary transitions’. PMID:27431522

  5. Self-Directed Learning: Emerging Theory & Practice.

    ERIC Educational Resources Information Center

    Long, Huey B.; And Others

    This book contains the following collection of papers: "Self-Directed Learning: Emerging Theory and Practice" (Long); "Self-Directed Orientation toward Learning: A Learning Style" (Bonham); "Self-Direction and Problem Solving: Theory and Method" (Peters); "Facilitating Self-Directed Learning: Not a Contradiction…

  6. Expanding Horizons in Self-Directed Learning.

    ERIC Educational Resources Information Center

    Long, Huey B.; And Others

    The following papers are included: "Preface" (Huey B. Long); "Self-Directed Learning: Smoke and Mirrors?" (Huey B. Long); "From Self-Culture to Self-Direction: An Historical Analysis of Self-Directed Learning" (Amy D. Rose); "The Link between Self-Directed and Transformative Learning" (Jane Pilling-Cormick);…

  7. New Ideas about Self-Directed Learning.

    ERIC Educational Resources Information Center

    Long, Huey B.; And Others

    These 16 papers provide as complete a picture as possible of the current efforts in self-directed learning (SDL) application and research. The papers are: "Challenging Some Myths about Self-Directed Learning Research" (Long); "Childhood Experiences as Origins of Self-Directed Learning Experiences" (Long, Stubblefield);…

  8. Emerging Perspectives of Self-Directed Learning.

    ERIC Educational Resources Information Center

    Long, Huey B.; And Others

    These 17 papers attest to the deepening and broadening interest in self-directed learning as one solution to the lifelong learning needs of men and women in an increasingly dynamic society. The papers include the following: "Self-Directed Learning Knowledge: Some Issues" (Long); "Development of Self-Directed Learning Readiness: A…

  9. Self Directed Learning and Self Management. Symposium.

    ERIC Educational Resources Information Center

    2002

    This document contains three papers from a symposium on self-directed learning and self-management. "Validating a More-Dimensional Conception of Self-Directed Learning" (Gerald A. Straka, Cornelia Schaefer) discusses the development and validation of a conception of self-directed learning as a dynamic interplay between behavior,…

  10. Collective Calcium Signaling of Defective Multicellular Networks

    NASA Astrophysics Data System (ADS)

    Potter, Garrett; Sun, Bo

    2015-03-01

    A communicating multicellular network processes environmental cues into collective cellular dynamics. We have previously demonstrated that, when excited by extracellular ATP, fibroblast monolayers generate correlated calcium dynamics modulated by both the stimuli and gap junction communication between the cells. However, just as a well-connected neural network may be compromised by abnormal neurons, a tissue monolayer can also be defective with cancer cells, which typically have down regulated gap junctions. To understand the collective cellular dynamics in a defective multicellular network we have studied the calcium signaling of co-cultured breast cancer cells and fibroblast cells in various concentrations of ATP delivered through microfluidic devices. Our results demonstrate that cancer cells respond faster, generate singular spikes, and are more synchronous across all stimuli concentrations. Additionally, fibroblast cells exhibit persistent calcium oscillations that increase in regularity with greater stimuli. To interpret these results we quantitatively analyzed the immunostaining of purigenic receptors and gap junction channels. The results confirm our hypothesis that collective dynamics are mainly determined by the availability of gap junction communications.

  11. Intercellular mechanotransduction during multicellular morphodynamics

    PubMed Central

    Kim, Jin-Hong; Dooling, Lawrence J.; Asthagiri, Anand R.

    2010-01-01

    Multicellular structures are held together by cell adhesions. Forces that act upon these adhesions play an integral role in dynamically re-shaping multicellular structures during development and disease. Here, we describe different modes by which mechanical forces are transduced in a multicellular context: (i) indirect mechanosensing through compliant substratum, (ii) cytoskeletal ‘tug-of-war’ between cell–matrix and cell–cell adhesions, (iii) cortical contractility contributing to line tension, (iv) stresses associated with cell proliferation, and (v) forces mediating collective migration. These modes of mechanotransduction are recurring motifs as they play a key role in shaping multicellular structures in a wide range of biological contexts. Tissue morphodynamics may ultimately be understood as different spatio-temporal combinations of a select few multicellular transformations, which in turn are driven by these mechanotransduction motifs that operate at the bicellular to multicellular length scale. PMID:20356878

  12. Self-Directed Learning with Feedback

    ERIC Educational Resources Information Center

    Choi, Youngeun; Anderson, William

    2016-01-01

    This article describes a weekly writing assignment named SelFeed (Self-Directed Learning with Feedback), in which students are asked to identify their own questions relevant to the lecture content and provide logical answers.

  13. Biological soliton in multicellular movement

    NASA Astrophysics Data System (ADS)

    Kuwayama, Hidekazu; Ishida, Shuji

    2013-07-01

    Solitons have been observed in various physical phenomena. Here, we show that the distinct characteristics of solitons are present in the mass cell movement of non-chemotactic mutants of the cellular slime mould Dictyostelium discoideum. During starvation, D. discoideum forms multicellular structures that differentiate into spore or stalk cells and, eventually, a fruiting body. Non-chemotactic mutant cells do not form multicellular structures; however, they do undergo mass cell movement in the form of a pulsatile soliton-like structure (SLS). We also found that SLS induction is mediated by adhesive cell-cell interactions. These observations provide novel insights into the mechanisms of biological solitons in multicellular movement.

  14. Communication theory and multicellular biology.

    PubMed

    Mian, I S; Rose, C

    2011-04-01

    In this Perspective, we propose that communication theory--a field of mathematics concerned with the problems of signal transmission, reception and processing--provides a new quantitative lens for investigating multicellular biology, ancient and modern. What underpins the cohesive organisation and collective behaviour of multicellular ecosystems such as microbial colonies and communities (microbiomes) and multicellular organisms such as plants and animals, whether built of simple tissue layers (sponges) or of complex differentiated cells arranged in tissues and organs (members of the 35 or so phyla of the subkingdom Metazoa)? How do mammalian tissues and organs develop, maintain their architecture, become subverted in disease, and decline with age? How did single-celled organisms coalesce to produce many-celled forms that evolved and diversified into the varied multicellular organisms in existence today? Some answers can be found in the blueprints or recipes encoded in (epi)genomes, yet others lie in the generic physical properties of biological matter such as the ability of cell aggregates to attain a certain complexity in size, shape, and pattern. We suggest that Lasswell's maxim "Who says what to whom in what channel with what effect" provides a foundation for understanding not only the emergence and evolution of multicellularity, but also the assembly and sculpting of multicellular ecosystems and many-celled structures, whether of natural or human-engineered origin. We explore how the abstraction of communication theory as an organising principle for multicellular biology could be realised. We highlight the inherent ability of communication theory to be blind to molecular and/or genetic mechanisms. We describe selected applications that analyse the physics of communication and use energy efficiency as a central tenet. Whilst communication theory has and could contribute to understanding a myriad of problems in biology, investigations of multicellular biology

  15. The origins of multicellular organisms.

    PubMed

    Niklas, Karl J; Newman, Stuart A

    2013-01-01

    Multicellularity has evolved in several eukaryotic lineages leading to plants, fungi, and animals. Theoretically, in each case, this involved (1) cell-to-cell adhesion with an alignment-of-fitness among cells, (2) cell-to-cell communication, cooperation, and specialization with an export-of-fitness to a multicellular organism, and (3) in some cases, a transition from "simple" to "complex" multicellularity. When mapped onto a matrix of morphologies based on developmental and physical rules for plants, these three phases help to identify a "unicellular ⇒ colonial ⇒ filamentous (unbranched ⇒ branched) ⇒ pseudoparenchymatous ⇒ parenchymatous" morphological transformation series that is consistent with trends observed within each of the three major plant clades. In contrast, a more direct "unicellular ⇒ colonial or siphonous ⇒ parenchymatous" series is observed in fungal and animal lineages. In these contexts, we discuss the roles played by the cooptation, expansion, and subsequent diversification of ancestral genomic toolkits and patterning modules during the evolution of multicellularity. We conclude that the extent to which multicellularity is achieved using the same toolkits and modules (and thus the extent to which multicellularity is homologous among different organisms) differs among clades and even among some closely related lineages.

  16. Principal Development: Self-Directed Project Efficacy

    ERIC Educational Resources Information Center

    Piggot-Irvine, Eileen

    2011-01-01

    The inclusion of self-directed projects as an element within a New Zealand principal development programme was designed to reflect increasing support internationally for such a context-specific "inquiry" approach. The results reported in this article suggest that considerable clarity is required for such projects if they are to realize…

  17. Fostering Self-Directed Learners through Competitions

    ERIC Educational Resources Information Center

    Lafrenz, Lu Ann; Murray, Bernadine

    2005-01-01

    Educational programs are continually seeking ways to encourage students' independence, personal growth, and self-directed learning. Graduates should enter the fashion industry with the ability to engage in lifelong learning in order to ensure competence in professional practice. Competition experiences help students to achieve these goals. The…

  18. Student Perspectives on Self-Directed Learning

    ERIC Educational Resources Information Center

    Douglass, Carolinda; Morris, Sherrill R.

    2014-01-01

    Undergraduate student perspectives regarding specific factors associated with self-directed learning were collected through eight focus groups. A total of 80 upperclassmen provided input revealing three emergent themes in the focus groups responses: (1) Student-Controlled, (2) Faculty-Controlled, and (3) Administration-Controlled Facilitators and…

  19. Self-Directed Thinking in the Curriculum.

    ERIC Educational Resources Information Center

    Dirkes, M. Ann

    1988-01-01

    Gifted students can learn to direct their thinking to maximize learning and creative production. They do this by stating what they intend to do, choosing strategies and appropriate conditions for thinking, and self-monitoring. The article describes techniques for developing self-directed thinking and applies these techniques to a class assignment.…

  20. Cinegrams for Self-Directed Learning.

    ERIC Educational Resources Information Center

    Fischer, Detlev; Richards, Clive

    1995-01-01

    Presents potential uses of cinegrams for self-directed learning; shows how these interactive animated diagrams for technical documentation and training serve as browsing tools for the exploration of interrelated engine subsystems. Describes the development of a cinegram prototype implemented in HyperCard that shows the oil system of a Rolls Royce…

  1. Learners' Perceptions of Self-Directed Study.

    ERIC Educational Resources Information Center

    Toebe, Dianne M.; And Others

    1982-01-01

    Alaska nurses who participated in self-directed continuing education courses were surveyed to determine what factors encouraged their participation. The strongest factors reported were personal satisfaction and need to update knowledge. Personal motivation and personal study habits appeared to be paramount in successful course completion. (SK)

  2. Self-Directed Learning in Cultural Institutions.

    ERIC Educational Resources Information Center

    Carr, David

    1985-01-01

    Museums, libraries, zoos, parks, historical sites, and other cultural institutions can be vehicles for much self-directed learning. This article reviews these opportunities and efforts to utilize them. It discusses cultural institutions as invitational environments, conditions of learning in cultural institutions, and tools and initiatives for…

  3. Self-Directed Learning--Past and Present

    ERIC Educational Resources Information Center

    Roberson, Donald N., Jr.

    2005-01-01

    The purpose of this article is to present various findings on self-directed learning (SDL). The article contains three main parts: historical foundation of self-directed learning, a summary of various literature reviews on self-directed learning, and an analysis of current research on self-directed learning. SDL has been a significant factor in…

  4. Physician self-directed learning and education.

    PubMed

    Tagawa, Masami

    2008-07-01

    Physicians are expected to be life-long learners because updated and effective patient care should be provided while medical and clinical knowledge and skills and social requirements for patient care are rapidly changing. Also, qualified clinical competence needs long periods of training and each physician has to continually learn as long as he/she works as a professional. Self-directed learning is an important factor in adult learning. Medical students' readiness for self-directed learning is not high, and should be improved by medical school and postgraduate training curricula. Garrison proposed a comprehensive model of self-directed learning, and it has dimensions of motivation (entering and task), self-monitoring (responsibility), and self-management (responsibility). To teach individual self-directed learning competencies, the following are important: (1) situate learners to experience "real" problems; (2) encourage learners to reflect on their own performance; (3) create an educational atmosphere in clinical training situations. In 2005, a 2-year mandatory residency program was implemented in Japan, and fewer medical school graduates took residency programs in medical school hospitals and advanced specialty programs provided by medical school departments. Medical school departments provide traditional, but life-long clinical training opportunities. Under the new residency program, an additional postgraduate and continuing medical training system has to be built up to maintain and confirm a physician's competencies. If physicians do clinical work using a scholarly way of thinking with critical analysis of their own competencies and improvement by reflection, they will become an excellent life-long learner.

  5. On The Evolution of Bacterial Multicellularity

    PubMed Central

    Lyons, Nicholas A.; Kolter, Roberto

    2015-01-01

    Multicellularity is one of the most prevalent evolutionary innovations and nowhere is this more apparent than in the bacterial world, which contains many examples of multicellular organisms in a surprising array of forms. Due to their experimental accessibility and the large and diverse genomic data available, bacteria enable us to probe fundamental aspects of the origins of multicellularity. Here we discuss examples of multicellular behaviors in bacteria, the selective pressures that may have led to their evolution, possible origins and intermediate stages, and whether the ubiquity of apparently convergent multicellular forms argues for its inevitability. PMID:25597443

  6. Adult Participation in Self-Directed Learning Programs

    ERIC Educational Resources Information Center

    Abdullah, Muhammad Madi Bin; Koren, Sebastian Francis; Muniapan, Balakrishnan; Parasuraman, Balakrishnan; Rathakrishnan, Balan

    2008-01-01

    This paper attempts to explain the various concepts related to self-directed learning and also the various theories and models regarding adult participation and also non-participation in self-directed learning programs. Because of the extensive amount of previous literature and research findings dealing with self-directed learning, it is necessary…

  7. Conceptions of Self-Directed Learning: Theoretical and Conceptual Considerations. LOS, Learning Organized Self-Directed Researchgroup.

    ERIC Educational Resources Information Center

    Straka, Gerald A., Ed.

    This book consists of 15 papers addressing issues and conceptions of self-directed learning. The following are included: "Self-Directed Learning as a Political Idea" (Stephen D. Brookfield); "Social Influences on Individual Commitment to Self-Directed Learning at Work" (Alan J. Brown); "Goals of Self-Learning" (Rosemary S. Caffarella); "From…

  8. Advances in multicellular spheroids formation

    PubMed Central

    Cui, X.; Hartanto, Y.

    2017-01-01

    Three-dimensional multicellular spheroids (MCSs) have a complex architectural structure, dynamic cell–cell/cell–matrix interactions and bio-mimicking in vivo microenvironment. As a fundamental building block for tissue reconstruction, MCSs have emerged as a powerful tool to narrow down the gap between the in vitro and in vivo model. In this review paper, we discussed the structure and biology of MCSs and detailed fabricating methods. Among these methods, the approach in microfluidics with hydrogel support for MCS formation is promising because it allows essential cell–cell/cell–matrix interactions in a confined space. PMID:28202590

  9. Antimicrobial peptides of multicellular organisms

    NASA Astrophysics Data System (ADS)

    Zasloff, Michael

    2002-01-01

    Multicellular organisms live, by and large, harmoniously with microbes. The cornea of the eye of an animal is almost always free of signs of infection. The insect flourishes without lymphocytes or antibodies. A plant seed germinates successfully in the midst of soil microbes. How is this accomplished? Both animals and plants possess potent, broad-spectrum antimicrobial peptides, which they use to fend off a wide range of microbes, including bacteria, fungi, viruses and protozoa. What sorts of molecules are they? How are they employed by animals in their defence? As our need for new antibiotics becomes more pressing, could we design anti-infective drugs based on the design principles these molecules teach us?

  10. The multicellularity genes of dictyostelid social amoebas

    PubMed Central

    Glöckner, Gernot; Lawal, Hajara M.; Felder, Marius; Singh, Reema; Singer, Gail; Weijer, Cornelis J.; Schaap, Pauline

    2016-01-01

    The evolution of multicellularity enabled specialization of cells, but required novel signalling mechanisms for regulating cell differentiation. Early multicellular organisms are mostly extinct and the origins of these mechanisms are unknown. Here using comparative genome and transcriptome analysis across eight uni- and multicellular amoebozoan genomes, we find that 80% of proteins essential for the development of multicellular Dictyostelia are already present in their unicellular relatives. This set is enriched in cytosolic and nuclear proteins, and protein kinases. The remaining 20%, unique to Dictyostelia, mostly consists of extracellularly exposed and secreted proteins, with roles in sensing and recognition, while several genes for synthesis of signals that induce cell-type specialization were acquired by lateral gene transfer. Across Dictyostelia, changes in gene expression correspond more strongly with phenotypic innovation than changes in protein functional domains. We conclude that the transition to multicellularity required novel signals and sensors rather than novel signal processing mechanisms. PMID:27357338

  11. The Multiple Origins of Complex Multicellularity

    NASA Astrophysics Data System (ADS)

    Knoll, Andrew H.

    2011-05-01

    Simple multicellularity has evolved numerous times within the Eukarya, but complex multicellular organisms belong to only six clades: animals, embryophytic land plants, florideophyte red algae, laminarialean brown algae, and two groups of fungi. Phylogeny and genomics suggest a generalized trajectory for the evolution of complex multicellularity, beginning with the co-optation of existing genes for adhesion. Molecular channels to facilitate cell-cell transfer of nutrients and signaling molecules appear to be critical, as this trait occurs in all complex multicellular organisms but few others. Proliferation of gene families for transcription factors and cell signals accompany the key functional innovation of complex multicellular clades: differentiated cells and tissues for the bulk transport of oxygen, nutrients, and molecular signals that enable organisms to circumvent the physical limitations of diffusion. The fossil records of animals and plants document key stages of this trajectory.

  12. Founders' Continuing Roles in Schools Supporting Self-Directed Learning

    ERIC Educational Resources Information Center

    Nash, Carol

    2014-01-01

    What should be the continuing role of founders in schools supporting self-directed learning? To answer this, the founders' views of two North American schools for self-directed learners will be compared. One school is exam-focused and private; the other is, test-free and public. The founders of both schools have comparable beliefs regarding the…

  13. Views of Gifted Elementary Students about Self-Directed Learning

    ERIC Educational Resources Information Center

    Van Deur, Penny

    2011-01-01

    Despite the connection between independent learning and gifted students, little is known of the views these students hold about the process of being self-directed learners. This interview study examined views of ten gifted elementary school students in South Australia about Self-Directed Learning. The interview responses showed that these gifted…

  14. A Study of Barriers to Adult Self-Directed Learning

    ERIC Educational Resources Information Center

    Douglas, Edward

    2010-01-01

    Self-directed learning has contributed significantly to adult learners' personal and professional growth. Approximately 70% of adult learning is through a self-directed learning context (Heimstra, 2008). This quantitative correlational study involved an attempt to determine the nature of the relationship between situational, dispositional, and…

  15. Development of the Self-Directed Learning Skills Scale

    ERIC Educational Resources Information Center

    Ayyildiz, Yildizay; Tarhan, Leman

    2015-01-01

    The purpose of this study was to develop a valid and reliable scale for assessing high school students' self-directed learning skills. Based on a literature review and data obtained from similar instruments, all skills related to self-directed learning were identified. Next, an item pool was prepared and administered to 255 students from various…

  16. Modeling Spaces for Self-Directed Learning at University Courses

    ERIC Educational Resources Information Center

    Pata, Kai

    2009-01-01

    This paper conceptualizes the theoretical framework of modeling learning spaces for self-directed learning at university courses. It binds together two ideas: (a) self-directed learners' common learning spaces may be characterized as abstract niches, (b) niche characteristics are collectively determined through individually perceived affordances.…

  17. Multicellularity makes somatic differentiation evolutionarily stable

    PubMed Central

    Wahl, Mary E.; Murray, Andrew W.

    2016-01-01

    Many multicellular organisms produce two cell lineages: germ cells, whose descendants produce the next generation, and somatic cells, which support, protect, and disperse the germ cells. This germ-soma demarcation has evolved independently in dozens of multicellular taxa but is absent in unicellular species. A common explanation holds that in these organisms, inefficient intercellular nutrient exchange compels the fitness cost of producing nonreproductive somatic cells to outweigh any potential benefits. We propose instead that the absence of unicellular, soma-producing populations reflects their susceptibility to invasion by nondifferentiating mutants that ultimately eradicate the soma-producing lineage. We argue that multicellularity can prevent the victory of such mutants by giving germ cells preferential access to the benefits conferred by somatic cells. The absence of natural unicellular, soma-producing species previously prevented these hypotheses from being directly tested in vivo: to overcome this obstacle, we engineered strains of the budding yeast Saccharomyces cerevisiae that differ only in the presence or absence of multicellularity and somatic differentiation, permitting direct comparisons between organisms with different lifestyles. Our strains implement the essential features of irreversible conversion from germ line to soma, reproductive division of labor, and clonal multicellularity while maintaining sufficient generality to permit broad extension of our conclusions. Our somatic cells can provide fitness benefits that exceed the reproductive costs of their production, even in unicellular strains. We find that nondifferentiating mutants overtake unicellular populations but are outcompeted by multicellular, soma-producing strains, suggesting that multicellularity confers evolutionary stability to somatic differentiation. PMID:27402737

  18. Bacterial Ventures into Multicellularity: Collectivism through Individuality.

    PubMed

    van Vliet, Simon; Ackermann, Martin

    2015-06-01

    Multicellular eukaryotes can perform functions that exceed the possibilities of an individual cell. These functions emerge through interactions between differentiated cells that are precisely arranged in space. Bacteria also form multicellular collectives that consist of differentiated but genetically identical cells. How does the functionality of these collectives depend on the spatial arrangement of the differentiated bacteria? In a previous issue of PLOS Biology, van Gestel and colleagues reported an elegant example of how the spatial arrangement of differentiated cells gives rise to collective behavior in Bacillus subtilus colonies, further demonstrating the similarity of bacterial collectives to higher multicellular organisms.

  19. Myxobacteria, Polarity, and Multicellular Morphogenesis

    PubMed Central

    Kaiser, Dale; Robinson, Mark; Kroos, Lee

    2010-01-01

    Myxobacteria are renowned for the ability to sporulate within fruiting bodies whose shapes are species-specific. The capacity to build those multicellular structures arises from the ability of M. xanthus to organize high cell-density swarms, in which the cells tend to be aligned with each other while constantly in motion. The intrinsic polarity of rod-shaped cells lays the foundation, and each cell uses two polar engines for gliding on surfaces. It sprouts retractile type IV pili from the leading cell pole and secretes capsular polysaccharide through nozzles from the trailing pole. Regularly periodic reversal of the gliding direction was found to be required for swarming. Those reversals are generated by a G-protein switch which is driven by a sharply tuned oscillator. Starvation induces fruiting body development, and systematic reductions in the reversal frequency are necessary for the cells to aggregate rather than continue to swarm. Developmental gene expression is regulated by a network that is connected to the suppression of reversals. PMID:20610548

  20. The Evolution of Multicellular Plants and Animals.

    ERIC Educational Resources Information Center

    Valentine, James W.

    1978-01-01

    Traces the evolution of unicellular organisms to the multi-cellular plants and animals in existence today. Major events are depicted in a geologic timetable. Organisms, extinct and recent, are classified by taxonomic group. (MA)

  1. The simplest integrated multicellular organism unveiled.

    PubMed

    Arakaki, Yoko; Kawai-Toyooka, Hiroko; Hamamura, Yuki; Higashiyama, Tetsuya; Noga, Akira; Hirono, Masafumi; Olson, Bradley J S C; Nozaki, Hisayoshi

    2013-01-01

    Volvocine green algae represent the "evolutionary time machine" model lineage for studying multicellularity, because they encompass the whole range of evolutionary transition of multicellularity from unicellular Chlamydomonas to >500-celled Volvox. Multicellular volvocalean species including Gonium pectorale and Volvox carteri generally have several common morphological features to survive as integrated multicellular organisms such as "rotational asymmetry of cells" so that the cells become components of the individual and "cytoplasmic bridges between protoplasts in developing embryos" to maintain the species-specific form of the multicellular individual before secretion of new extracellular matrix (ECM). However, these morphological features have not been studied in the four-celled colonial volvocine species Tetrabaena socialis that is positioned in the most basal lineage within the colonial or multicellular volvocine greens. Here we established synchronous cultures of T. socialis and carried out immunofluorescence microscopic and ultrastructural observations to elucidate these two morphological attributes. Based on immunofluorescence microscopy, four cells of the mature T. socialis colony were identical in morphology but had rotational asymmetry in arrangement of microtubular rootlets and separation of basal bodies like G. pectorale and V. carteri. Ultrastructural observations clearly confirmed the presence of cytoplasmic bridges between protoplasts in developing embryos of T. socialis even after the formation of new flagella in each daughter protoplast within the parental ECM. Therefore, these two morphological attributes might have evolved in the common four-celled ancestor of the colonial volvocine algae and contributed to the further increase in cell number and complexity of the multicellular individuals of this model lineage. T. socialis is one of the simplest integrated multicellular organisms in which four identical cells constitute the individual.

  2. Beyond the classroom: self-direction in professional learning.

    PubMed

    Mayfield, M K

    1993-10-01

    Against the backdrop of a rapidly changing profession, the context for professional thinking among medical librarians is changing. Competent performance increasingly is linked with the educational efforts of self-directed adult learners. This paper examines strategies that facilitate self-direction, including skills development, organizational learning, learner-based decision making, and alternative teaching models. The analysis provides the basis for a recommended agenda for redesign and development of educational programs.

  3. Limits to Chemically Guided Multicellular Migration

    NASA Astrophysics Data System (ADS)

    Varennes, Julien; Han, Bumsoo; Mugler, Andrew

    Collective cell migration in response to a chemical cue requires both multicellular sensing of chemical gradients and coordinated mechanical action. Examples from morphogenesis and cancer metastasis demonstrate that clusters of migratory cells are extremely sensitive, responding to gradients of less than 1% difference in chemical concentration across a cell body. While the limits to multicellular sensing are becoming known, the ensuing consequences for coherent migration remain poorly understood. We develop a model of multicellular sensing and migration based on the cellular Potts model. Multicellular sensing of noisy chemical gradients is modeled as a process of local excitation and global inhibition (LEGI) among communicating cells. The output of the sensing process is coupled to individual cells' polarization to model migratory behavior. We find that larger clusters of cells detect the gradient direction with higher precision and thus achieve stronger polarization bias. At the same time, larger clusters are also accompanied by less coherent collective motion. The trade-off between these two effects leads to an optimally efficient cluster size. We discuss how our results relate to cancer metastasis.

  4. Bacterial biofilms: prokaryotic adventures in multicellularity.

    PubMed

    Webb, Jeremy S; Givskov, Michael; Kjelleberg, Staffan

    2003-12-01

    The development of bacterial biofilms includes both the initial social behavior of undifferentiated cells, as well as cell death and differentiation in the mature biofilm, and displays several striking similarities with higher organisms. Recent advances in the field provide new insight into differentiation and cell death events in bacterial biofilm development and propose that biofilms have an unexpected level of multicellularity.

  5. Developing Student Competence in Self-Directed IEPs

    ERIC Educational Resources Information Center

    Torgerson, C. W.; Miner, C. A.; Shen, H.

    2004-01-01

    Self-directed Individualized Education Programs (IEPs) allow students to assume leadership and become actively involved in the decisions made at their IEP meetings. This article describes how through direct instruction, social skills discussion, active practice, and role-playing students are prepared to facilitate their meeting. This active…

  6. Promoting Self-Directed Revision in EFL Writing Classes

    ERIC Educational Resources Information Center

    Coomber, Matthew

    2016-01-01

    Second language writers need to develop the ability to revise their writing independently of third party advice; thus, it is important that teachers devise methods by which to promote habits of self-directed revision. This quasi-experimental study investigates three classroom activities designed to encourage students to independently revise essays…

  7. Self-Directed Lifelong Learning in Hybrid Learning Configurations

    ERIC Educational Resources Information Center

    Cremers, Petra H. M.; Wals, Arjen E. J.; Wesselink, Renate; Nieveen, Nienke; Mulder, Martin

    2014-01-01

    Present-day students are expected to be lifelong learners throughout their working life. Higher education must therefore prepare students to self-direct their learning beyond formal education, in real-life working settings. This can be achieved in so-called hybrid learning configurations in which working and learning are integrated. In such a…

  8. Reorienting Self-Directed Learning for the Creative Digital Era

    ERIC Educational Resources Information Center

    Karakas, Fahri; Manisaligil, Alperen

    2012-01-01

    Purpose: The purpose of this paper is to identify the new role that human resource developers play in the globally connected workplace. Towards that end, this paper explores the changing landscape of self-directed learning (SDL) within the digital ecosystem based on the concept of World 2.0. Design/methodology/approach: This paper reviews and…

  9. The Self-Directed Learning Process of Older, Rural Adults

    ERIC Educational Resources Information Center

    Roberson, Donald N., Jr.; Merriam, Sharan B.

    2005-01-01

    Medical advances and lifestyle changes have resulted in older adults living longer and healthier lives. Nevertheless, older adulthood, as other life stages, requires change in work, family, and health. Self-directed learning (SDL) is one way of negotiating these transitions. The purpose of this study was to understand this process of learning.…

  10. A Study of Self-Directed Professionals of High Attainment.

    ERIC Educational Resources Information Center

    Bouchard, Paul

    The determinants of self-directed learning (SDL) among professionals of high attainment were examined through open-ended, semidirected interviews with a purposeful sample of eight professional men and women who have acquired identifiable, high-level professional knowledge/skills typically taught in postsecondary learning institutions without ever…

  11. Self-Directed Support Policy: Challenges and Possible Solutions

    ERIC Educational Resources Information Center

    Harkes, Mary A.; Brown, Michael; Horsburgh, Dorothy

    2014-01-01

    A systematic literature review was conducted between September 2010 and April 2011 and published earlier in this journal, paper 1. The findings indicated that few studies of Self-Directed Support focused specifically on people with intellectual disabilities. The range of individuals' ability and distinction between adults with or without…

  12. The Educational Affordances of Blogs for Self-Directed Learning

    ERIC Educational Resources Information Center

    Robertson, Judy

    2011-01-01

    To be successful university learners, students need to develop skills in self-directed learning. This encompasses a range of cognitive and meta-cognitive skills including generating one's own learning goals, planning how to tackle a problem, evaluating whether learning goals have been met, and re-planning based on this evaluation. The educational…

  13. Increasing self-directed training in neurorehabilitation patients through competition.

    PubMed

    Studer, B; Van Dijk, H; Handermann, R; Knecht, S

    2016-01-01

    This proof-of-concept study aimed to test whether competition could be a useful tool to increase intensity and amount of self-directed training in neurorehabilitation. Stroke patients undergoing inpatient neurorehabilitation (n=93) conducted self-directed endurance training on a (wheelchair-compatible) bicycle trainer under three experimental conditions: a "Competition" condition and two noncompetition control conditions (repeated randomized within-subject design). Training performance and perceived exertion were recorded and statistically analyzed. Three motivational effects of competition were found. First, competition led to an increase in self-directed training. Patients exercised significantly more intensively under competition than in the two noncompetition control conditions. Second, (winning a) competition had a positive influence on performance in the subsequent training session. Third, training performance was particularly high during rematch competitions; that is to say, during second encounter competitions against an opponent that the patient had just beaten. No systematic effect of competition upon perceived exertion (controlled for training performance) was found. Together, our results demonstrate that competition is a potent motivational tool to increase self-directed training in neurorehabilitation.

  14. Self-Directed Learning Dissertation Abstracts 1966-1991.

    ERIC Educational Resources Information Center

    Long, Huey B.; Redding, Terrence R.

    This index contains abstracts of 173 doctoral dissertations about the following aspects of adult self-directed learning: program areas of adult education (AE); instructional methods/techniques; institutional sponsors of AE; personnel and staffing in AE; education of particular clientele groups; processes of program planning and administration;…

  15. 42 CFR 441.452 - Self-direction: General.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... both traditional service delivery and the self-directed PAS service delivery option available in the... PAS service delivery option. (c) The State's assessment of an individual's needs must form the basis... Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN...

  16. Vocational Interests (The Self-Directed Search) of Female Carpenters

    ERIC Educational Resources Information Center

    Swan, Kathy C.

    2005-01-01

    In this national sample of female carpenters (N=411) who began their apprenticeship with the United Brotherhood of Carpenters during the 1990s in the United States, the author provides a profile of female carpenters' vocational interests (The Self-Directed Search). The vocational interests of 137 male carpenters also were gathered for comparison.…

  17. Portfolio: A Tool for Self-Directed Learning at Work.

    ERIC Educational Resources Information Center

    Lyons, Nona; Evans, Linda

    The Portfolio Project was conducted to promote lifelong, self-directed learning in the workplace. The project, which offered courses on basic skills, supervisory communications, and English as a second language, was initiated as a literacy demonstration project by the Casco Bay Partnership (CBP), which brought together government, educators, and…

  18. Personal Learning Environments: A Solution for Self-Directed Learners

    ERIC Educational Resources Information Center

    Haworth, Ryan

    2016-01-01

    In this paper I discuss "personal learning environments" and their diverse benefits, uses, and implications for life-long learning. Personal Learning Environments (PLEs) are Web 2.0 and social media technologies that enable individual learners the ability to manage their own learning. Self-directed learning is explored as a foundation…

  19. Implementing Self-Directed Work Teams at a College Newspaper

    ERIC Educational Resources Information Center

    de Pillis, Emmeline; Parsons, Blake

    2013-01-01

    The problem: Motivating and retaining staff had become an ongoing problem at the student newspaper. Student staffers would quit abruptly when overwhelmed or dissatisfied, leaving the newspaper with critical positions vacant. This affected the performance of the newspaper. Method: The newspaper was organized into self directed work teams (SDWTs).…

  20. Analysis of Self-Directed Mastery Learning of Honors Physics

    ERIC Educational Resources Information Center

    Athens, Wendy

    2011-01-01

    Self-directed learning (SDL) is an important life skill in a knowledge-based society and prepares students to persist, manage their time and resources, use logic to construct their knowledge, argue their views, and collaborate. The purpose of this study was to facilitate mastery of physics concepts through self-directedness in formative testing…

  1. Web Interface Design Principles for Adults' Self-Directed Learning

    ERIC Educational Resources Information Center

    Firat, Mehmet; Sakar, A. Nurhan; Kabakci Yurdakul, Isil

    2016-01-01

    One of the most important features which e-learning tools and environments must possess within the scope of lifelong learning is self-directed learning, which can be considered as a form of self-learning. The aim of this study was to determine, based on the views and recommendations of experts, interface design principles for the development of…

  2. Self-Directed Learning: A Tool for Lifelong Learning

    ERIC Educational Resources Information Center

    Boyer, Stefanie L.; Edmondson, Diane R.; Artis, Andrew B.; Fleming, David

    2014-01-01

    A meta-analytic review of self-directed learning (SDL) research over 30 years, five countries, and across multiple academic disciplines is used to explore its relationships with five key nomologically related constructs for effective workplace learning. The meta-analysis revealed positive relationships between SDL and internal locus of control,…

  3. Self-directed Learning to Educate Medical Educators. Part 1: How Do We Use Self-directed Learning?

    ERIC Educational Resources Information Center

    Hammond, Merryl; Collins, Rob

    1987-01-01

    Described are seven steps used to help self-directed learners to work through the Diploma in Primary Health Care (Education) course at the University of Witwatersrand. The steps are: situation analysis; compilation of a competency profile; self-assessment of learning needs; writing learning objectives; compilation of a learning agreement;…

  4. Developing the Self-Directed Learning Instructional Model to Enhance English Reading Ability and Self-Directed Learning of Undergraduate Students

    ERIC Educational Resources Information Center

    Wichadee, Saovapa

    2011-01-01

    The purposes of this study were to develop the instructional model for enhancing self-directed learning skills of Bangkok University students, study the impacts of the model on their English reading comprehension and self-directed learning ability as well as explore their opinion towards self-directed learning. The model development process…

  5. Analysis of self-directed mastery learning of honors physics

    NASA Astrophysics Data System (ADS)

    Athens, Wendy

    Self-directed learning (SDL) is an important life skill in a knowledge-based society and prepares students to persist, manage their time and resources, use logic to construct their knowledge, argue their views, and collaborate. The purpose of this study was to facilitate mastery of physics concepts through self-directedness in formative testing with feedback, a choice of learning activities, and multiple forms of support. This study was conducted within two sections of honors physics at a private high school (N=24). Students' learning activity choices, time investments, and perceptions (assessed through a post survey) were tracked and analyzed. SDL readiness was linked to success in mastering physics concepts. The three research questions pursued in this study were: What SDL activities did honors physics students choose in their self-directed mastery learning environment? How many students achieved concept mastery and how did they spend their time? Did successful and unsuccessful students perceive the self-directed mastery learning environment differently? Only seven of 24 students were successful in passing the similar concept-based unit tests within four tries, and these seven students were separated into a "successful" group and the other 17 into an "unsuccessful" group. Differences between the two groups were analyzed. A profile of a self-directed secondary honors physics student emerged. A successful self-directed student invested more time learning from activities rather than simply completing them, focused on learning concepts more than rote operations, intentionally selected activities to fill in gaps of knowledge and practice concepts, actively constructed knowledge into a cognitive framework, engaged in academic discourse with instructor and peers as they made repeated attempts to master content and pass the test given constructive feedback, used a wide variety of learning resources, and managed their workload to meet deadlines. This capstone study found

  6. Collective Chemotaxis through Noisy Multicellular Gradient Sensing

    NASA Astrophysics Data System (ADS)

    Varennes, Julien; Han, Bumsoo; Mugler, Andrew

    2016-08-01

    Collective cell migration in response to a chemical cue occurs in many biological processes such as morphogenesis and cancer metastasis. Clusters of migratory cells in these systems are capable of responding to gradients of less than 1% difference in chemical concentration across a cell length. Multicellular systems are extremely sensitive to their environment and while the limits to multicellular sensing are becoming known, how this information leads to coherent migration remains poorly understood. We develop a computational model of multicellular sensing and migration in which groups of cells collectively measure noisy chemical gradients. The output of the sensing process is coupled to individual cells polarization to model migratory behavior. Through the use of numerical simulations, we find that larger clusters of cells detect the gradient direction with higher precision and thus achieve stronger polarization bias, but larger clusters also induce more drag on collective motion. The trade-off between these two effects leads to an optimal cluster size for most efficient migration. We discuss how our model could be validated using simple, phenomenological experiments.

  7. Cooperation, clumping and the evolution of multicellularity.

    PubMed

    Biernaskie, Jay M; West, Stuart A

    2015-08-22

    The evolution of multicellular organisms represents one of the major evolutionary transitions in the history of life. A potential advantage of forming multicellular clumps is that it provides an efficiency benefit to pre-existing cooperation, such as the production of extracellular 'public goods'. However, this is complicated by the fact that cooperation could jointly evolve with clumping, and clumping could have multiple consequences for the evolution of cooperation. We model the evolution of clumping and a cooperative public good, showing that (i) when considered separately, both clumping and public goods production gradually increase with increasing genetic relatedness; (ii) in contrast, when the traits evolve jointly, a small increase in relatedness can lead to a major shift in evolutionary outcome—from a non-clumping state with low public goods production to a cooperative clumping state with high values of both traits; (iii) high relatedness makes it easier to get to the cooperative clumping state and (iv) clumping can be inhibited when it increases the number of cells that the benefits of cooperation must be shared with, but promoted when it increases relatedness between those cells. Overall, our results suggest that public goods sharing can facilitate the formation of well-integrated cooperative clumps as a first step in the evolution of multicellularity.

  8. Self-Directed Learning: A Cognitive and Computational Perspective.

    PubMed

    Gureckis, Todd M; Markant, Douglas B

    2012-09-01

    A widely advocated idea in education is that people learn better when the flow of experience is under their control (i.e., learning is self-directed). However, the reasons why volitional control might result in superior acquisition and the limits to such advantages remain poorly understood. In this article, we review the issue from both a cognitive and computational perspective. On the cognitive side, self-directed learning allows individuals to focus effort on useful information they do not yet possess, can expose information that is inaccessible via passive observation, and may enhance the encoding and retention of materials. On the computational side, the development of efficient "active learning" algorithms that can select their own training data is an emerging research topic in machine learning. This review argues that recent advances in these related fields may offer a fresh theoretical perspective on how people gather information to support their own learning.

  9. Supporting Reflection on Self-Directed Learning Process in Hyperspace

    NASA Astrophysics Data System (ADS)

    Kashihara, Akihiro; Sakamoto, Masanao; Hasegawa, Shinobu; Toyoda, Jun'ichi

    Hypermedia/hypertext-based resources for learning generally provide learners with hyperspace, which consists of pages and links among the pages. In the hyperspace, they can navigate the pages in a self-directed way to learn the domain concepts/knowledge. The navigation often involves constructing knowledge, in which they would make semantic relationships among the contents learned in the navigated pages. Such self-directed learning in hyperspace requires learners to reflect on their knowledge construction process, which they have carried out so far, since what and how they have learned becomes hazy as the navigation progresses. However, it is hard for them to keep reflection during navigating hyperspace. The main issue addressed in this paper is how to facilitate learners' reflection to promote their self-directed learning. Our approach to this issue is to provide learners with a learning tool, which allows learners to annotate their navigation history representation with their knowledge construction process. The annotated navigation history enables them to reflect on their knowledge construction process. This paper also demonstrates an interactive history, which generates the annotated navigation history from learners' annotation. It also generates a knowledge map that visualizes the semantic relationships among the pages learners have learned in hyperspace. This paper also describes a case study with the interactive history. The results indicate that it facilitates reflection on knowledge construction process carried out in hyperspace.

  10. Development of Three-Dimensional Multicellular Tissue-Like Constructs for Mutational Analysis Using Macroporous Microcarriers

    NASA Technical Reports Server (NTRS)

    Jordan, Jacqueline A.; Fraga, Denise N.; Gonda, Steve R.

    2002-01-01

    A three-dimensional (3-D), tissue-like model was developed for the genotoxic assessment of space environment. In previous experiments, we found that culturing mammalian cells in a NASA-designed bioreactor, using Cytodex-3 beads as a scaffold, generated 3-D multicellular spheroids. In an effort to generate scaffold-free spheroids, we developed a new 3-D tissue-like model by coculturing fibroblast and epithelial cell in a NASA bioreactor using macroporous Cultispher-S(TradeMark) microcarriers. Big Blue(Registered Trademark) Rat 2(Lambda) fibroblasts, genetically engineered to contain multiple copies (>60 copies/cell) of the Lac I target gene, were cocultured with radio-sensitive human epithelial cells, H184F5. Over an 8-day period, samples were periodically examined by microscopy and histology to confirm cell attachment, growth, and viability. Immunohistochemistry and western analysis were used to evaluate the expression of specific cytoskeletal and adhesion proteins. Key cell culture parameters (glucose, pH, and lactate concentrations) were monitored daily. Controls were two-dimensional mono layers of fibroblast or epithelial cells cultured in T-flasks. Analysis of 3-D spheroids from the bioreactor suggests fibroblast cells attached to and completely covered the bead surface and inner channels by day 3 in the bioreactor. Treatment of the 3-day spheroids with dispase II dissolved the Cultisphers(TradeMark) and produced multicellular, bead-less constructs. Immunohistochemistry confirmed the presence of vi.mentin, cytokeratin and E-cadherin in treated spheroids. Examination of the dispase II treated spheroids with transmission electron microscopy (TEM) also showed the presence of desmosomes. These results suggest that the controlled enzymatic degradation of an artificial matrix in the low shear environment of the NASA-designed bioreactor can produce 3-D tissue-like spheroids. 2

  11. Self-directed Learning and Its Impact on Menopausal Symptoms

    PubMed Central

    Yazdkhasti, Mansoureh; Keshavarz, Maryam; Mahmoodi, Zohreh; Hosseini, Agha Fatemeh

    2014-01-01

    Background: One of the main criteria to verify the effectiveness of a health training program is to measure quality of life in menopausal women. Objectives: Hence the aim of this review was to evaluate the effects of self-directed learning (SDL) on MENQOl. Patients and Methods: The present single blind field study was conducted in Saadatmandi Health Center of Robat Karim (Iran, Southwest of Tehran Province) from August to December 2010. One handred and ten menopausal women were selected using convenience sampling method and then divided into two experimental (Self-directed Learning) and control groups of 55 each. Four manuals were developed to guide the women in the experimental group containing practical ways to treat menopausal symptoms. They were distributed among the participants for four weeks on a specific day. Menopausal Specific Quality of Life Questionnaire (MENQOL) was used to determine and compare quality of life scores of these women (before and three months after intervention sessions). The control group did not receive any intervention. Statistical analysis was performed by SPSS/16 software using Kolmogorov-Sminov, ANOVA, independent paired t test and Chi-square test. Results: There were significant statistical differences between two groups regarding the age of subjects; age of menopause; economic, educational and employment status; number of dead and living children; BMI and vasomotor, physical, sexual and psycho-social postmenopausal symptoms. The implementation of Self-directed Learning (SDL) model leads to a significant statistical difference in scores of vasomotor symptoms (16.32 ± 5.92 to 13.26 ± 5.31), psychosocial symptoms (34.8 ± 11 to 27.18 ± 10.83), physical symptoms (75.02 ± 18.07 to 61.42 ± 15.49), sexual symptoms (15.36 ± 6.10 to 12.00 ± 4.97) and the overall score for quality of life (141.5 ± 41.09 to 113.86 ± 36.6) (P < 0.001). No significant changes were found in the QOL scores of the control group. Conclusions

  12. An Evo-Devo Perspective on Multicellular Development of Myxobacteria.

    PubMed

    Arias Del Angel, Juan A; Escalante, Ana E; Martínez-Castilla, León Patricio; Benítez, Mariana

    2017-01-01

    The transition to multicellularity, recognized as one the major transitions in evolution, has occurred independently several times. While multicellular development has been extensively studied in zygotic organisms including plant and animal groups, just a few aggregative multicellular organisms have been employed as model organisms for the study of multicellularity. Studying different evolutionary origins and modes of multicellularity enables comparative analyses that can help identifying lineage-specific aspects of multicellular evolution and generic factors and mechanisms involved in the transition to multicellularity. Among aggregative multicellular organisms, myxobacteria are a valuable system to explore the particularities that aggregation confers to the evolution of multicellularity and mechanisms shared with clonal organisms. Moreover, myxobacteria species develop fruiting bodies displaying a range of morphological diversity. In this review, we aim to synthesize diverse lines of evidence regarding myxobacteria development and discuss them in the context of Evo-Devo concepts and approaches. First, we briefly describe the developmental processes in myxobacteria, present an updated comparative analysis of the genes involved in their developmental processes and discuss these and other lines of evidence in terms of co-option and developmental system drift, two concepts key to Evo-Devo studies. Next, as has been suggested from Evo-Devo approaches, we discuss how broad comparative studies and integration of diverse genetic, physicochemical, and environmental factors into experimental and theoretical models can further our understanding of myxobacterial development, phenotypic variation, and evolution.

  13. Chinese baccalaureate nursing students' readiness for self-directed learning.

    PubMed

    Yuan, Hao Bin; Williams, Beverly A; Fang, Jin Bo; Pang, Dong

    2012-05-01

    This descriptive cross-sectional study was conducted with 536 Chinese nursing students to explore students' readiness for self-directed learning (SDL). The Self-Directed Learning Readiness (SDLR) Scale for nursing education (Chinese translation version) was used. The value of the content validity index tested by five experts was 0.915. A measure of internal consistency (Cronbach's alpha) was 0.925 on the total scale. Students possessed readiness for SDL with a mean score of 157.72 (S.D.=15.08, 62.3% in high level, and 37.7% in low level). The attributes of Chinese students, such as a strong sense of responsibility and perseverance, due diligence and rigorous self-discipline, enable students to take the initiative and responsibility for their own learning. The existing variation in students' readiness for SDL is helpful in identifying student characteristics that might be used to modify learning activities for these students. Senior students had higher scores for SDLR than junior students. This finding likely reflects the maturational process of developing self-directedness. Promoting SDL skills is a challenging process for faculty members and students. It is helpful if nurse educators assess the learning styles and preferences of their students in order to determine the level of SDL activities to include from year to year in the curriculum.

  14. The Influence of Complexity and Uncertainty on Self-Directed Team Learning

    ERIC Educational Resources Information Center

    Gray, David

    2012-01-01

    To help increase the effectiveness of self-directed teams, this paper studies the attitudes and behaviour of self-directed team members during the course of a computer simulated marketing strategy game. Self-directed teams are used widely throughout organisations yet receive little scrutiny when they undertake a task which is subject to conditions…

  15. Analysis of Self-Directed Learning upon Student of Mathematics Education Study Program

    ERIC Educational Resources Information Center

    Kleden, Maria Agustina

    2015-01-01

    Various studies have rendered self-directed learning disposition to be significant in the learning of mathematics, however several previous studies have pointed the level of self-directed learning disposition to be at a low point. This research is aimed to enhance self-directed learning through implementing a metacognitive strategy in learning…

  16. Self-Directed Professionals and Autodidactic Choice: A Framework for Analysis.

    ERIC Educational Resources Information Center

    Bouchard, Paul

    Studies of self-directed learning (SDL) have generally concentrated on who self-directed learners are and what/how they learn. In 1980, Gibbons et al. used biographies of 20 "expert" self-directed learners to explore the principles and determinants of SDL. Tough (1967), Guglielmino (1977), and Spear and Mocker (1984) have respectively…

  17. Finding self-directed learning readiness and fostering self-directed learning through weekly assessment of self-directed learning topics during undergraduate clinical training in ophthalmology

    PubMed Central

    Sahoo, Soumendra

    2016-01-01

    Background: To know the individual’s current level of readiness and to manage self-directed learning (SDL) not only help learners but also the instructors. The objectives of this study were to find SDL readiness among 4th year medical student and to analyze the effect of weekly assessment of SDL topics. Methodology: This was a cross-sectional study to analyze the effect of weekly assessment of SDL topics in fostering SDL. The 51 4th year students during a clinical posting in ophthalmology participated for this study. Each recruited student was tested for SDL readiness through the SDL readiness scale (SDLRS) developed by Lucy Guglielmino (1978), which was validated in our local setting and responses were collected from students on the 1st day of the clinical posting. The students chose SDL topics which were assessed on a weekly basis in the form of scenario-based multiple choice questionnaires. Written feedback was collected from each student regarding such activity during their clinical posting, especially to know the actual utilization of SDL hours provided in teaching schedule, satisfaction on the type of questions and motivation for SDL. Results: The mean SDLRS score in male students were 214.15 ± 19.73 and in female 207.95 ± 17.983, which falls under average score as defined in Guglielmino scale. The majority of study population expressed better utilization of SDL study hours because of weekly assessment than when they had no assessment for SDL. Conclusions: Majority of the study population were found to be ready for SDL. The weekly assessment of SDL topics was found to stimulate proper utilization of SDL slots in teaching schedule thereby fostering SDL habits. PMID:27563580

  18. Multicellular density fluctuations in epithelial monolayers

    NASA Astrophysics Data System (ADS)

    Zehnder, Steven M.; Wiatt, Marina K.; Uruena, Juan M.; Dunn, Alison C.; Sawyer, W. Gregory; Angelini, Thomas E.

    2015-09-01

    Changes in cell size often accompany multicellular motion in tissue, and cell number density is known to strongly influence collective migration in monolayers. Density fluctuations in other forms of active matter have been explored extensively, but not the potential role of density fluctuations in collective cell migration. Here we investigate collective motion in cell monolayers, focusing on the divergent component of the migration velocity field to probe density fluctuations. We find spatial patterns of diverging and converging cell groups throughout the monolayers, which oscillate in time with a period of approximately 3-4 h. Simultaneous fluorescence measurements of a cytosol dye within the cells show that fluid passes between groups of cells, facilitating these oscillations in cell density. Our findings reveal that cell-cell interactions in monolayers may be mediated by intercellular fluid flow.

  19. Simple systems that exhibit self-directed replication

    NASA Technical Reports Server (NTRS)

    Reggia, James A.; Armentrout, Steven L.; Chou, Hui-Hsien; Peng, Yun

    1993-01-01

    Biological experience and intuition suggest that self-replication is an inherently complex phenomenon, and early cellular automata models support that conception. More recently, simpler computational models of self-directed replication called sheathed loops have been developed. It is shown here that 'unsheathing' these structures and altering certain assumptions about the symmetry of their components leads to a family of nontrivial self-replicating structures some substantially smaller and simpler than those previously reported. The dependence of replication time and transition function complexity on initial structure size, cell state symmetry, and neighborhood are examined. These results support the view that self-replication is not an inherently complex phenomenon but rather an emergent property arising from local interactions in systems that can be much simpler than is generally believed.

  20. Multicellular computing using conjugation for wiring.

    PubMed

    Goñi-Moreno, Angel; Amos, Martyn; de la Cruz, Fernando

    2013-01-01

    Recent efforts in synthetic biology have focussed on the implementation of logical functions within living cells. One aim is to facilitate both internal "re-programming" and external control of cells, with potential applications in a wide range of domains. However, fundamental limitations on the degree to which single cells may be re-engineered have led to a growth of interest in multicellular systems, in which a "computation" is distributed over a number of different cell types, in a manner analogous to modern computer networks. Within this model, individual cell type perform specific sub-tasks, the results of which are then communicated to other cell types for further processing. The manner in which outputs are communicated is therefore of great significance to the overall success of such a scheme. Previous experiments in distributed cellular computation have used global communication schemes, such as quorum sensing (QS), to implement the "wiring" between cell types. While useful, this method lacks specificity, and limits the amount of information that may be transferred at any one time. We propose an alternative scheme, based on specific cell-cell conjugation. This mechanism allows for the direct transfer of genetic information between bacteria, via circular DNA strands known as plasmids. We design a multi-cellular population that is able to compute, in a distributed fashion, a Boolean XOR function. Through this, we describe a general scheme for distributed logic that works by mixing different strains in a single population; this constitutes an important advantage of our novel approach. Importantly, the amount of genetic information exchanged through conjugation is significantly higher than the amount possible through QS-based communication. We provide full computational modelling and simulation results, using deterministic, stochastic and spatially-explicit methods. These simulations explore the behaviour of one possible conjugation-wired cellular computing

  1. Geometry Shapes Evolution of Early Multicellularity

    PubMed Central

    Libby, Eric; Ratcliff, William; Travisano, Michael; Kerr, Ben

    2014-01-01

    Organisms have increased in complexity through a series of major evolutionary transitions, in which formerly autonomous entities become parts of a novel higher-level entity. One intriguing feature of the higher-level entity after some major transitions is a division of reproductive labor among its lower-level units in which reproduction is the sole responsibility of a subset of units. Although it can have clear benefits once established, it is unknown how such reproductive division of labor originates. We consider a recent evolution experiment on the yeast Saccharomyces cerevisiae as a unique platform to address the issue of reproductive differentiation during an evolutionary transition in individuality. In the experiment, independent yeast lineages evolved a multicellular “snowflake-like” cluster formed in response to gravity selection. Shortly after the evolution of clusters, the yeast evolved higher rates of cell death. While cell death enables clusters to split apart and form new groups, it also reduces their performance in the face of gravity selection. To understand the selective value of increased cell death, we create a mathematical model of the cellular arrangement within snowflake yeast clusters. The model reveals that the mechanism of cell death and the geometry of the snowflake interact in complex, evolutionarily important ways. We find that the organization of snowflake yeast imposes powerful limitations on the available space for new cell growth. By dying more frequently, cells in clusters avoid encountering space limitations, and, paradoxically, reach higher numbers. In addition, selection for particular group sizes can explain the increased rate of apoptosis both in terms of total cell number and total numbers of collectives. Thus, by considering the geometry of a primitive multicellular organism we can gain insight into the initial emergence of reproductive division of labor during an evolutionary transition in individuality. PMID:25233196

  2. Role of Multicellular Aggregates in Biofilm Formation

    PubMed Central

    Kragh, Kasper N.; Hutchison, Jaime B.; Melaugh, Gavin; Rodesney, Chris; Roberts, Aled E. L.; Irie, Yasuhiko; Jensen, Peter Ø.; Diggle, Stephen P.; Allen, Rosalind J.

    2016-01-01

    ABSTRACT In traditional models of in vitro biofilm development, individual bacterial cells seed a surface, multiply, and mature into multicellular, three-dimensional structures. Much research has been devoted to elucidating the mechanisms governing the initial attachment of single cells to surfaces. However, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process. This makes it likely that biofilms are often seeded by aggregates and single cells, yet how these aggregates impact biofilm initiation and development is not known. Here we use a combination of experimental and computational approaches to determine the relative fitness of single cells and preformed aggregates during early development of Pseudomonas aeruginosa biofilms. We find that the relative fitness of aggregates depends markedly on the density of surrounding single cells, i.e., the level of competition for growth resources. When competition between aggregates and single cells is low, an aggregate has a growth disadvantage because the aggregate interior has poor access to growth resources. However, if competition is high, aggregates exhibit higher fitness, because extending vertically above the surface gives cells at the top of aggregates better access to growth resources. Other advantages of seeding by aggregates, such as earlier switching to a biofilm-like phenotype and enhanced resilience toward antibiotics and immune response, may add to this ecological benefit. Our findings suggest that current models of biofilm formation should be reconsidered to incorporate the role of aggregates in biofilm initiation. PMID:27006463

  3. Promotion of Self-directed Learning Using Virtual Patient Cases

    PubMed Central

    Schonder, Kristine; McGee, James

    2013-01-01

    Objective. To assess the effectiveness of virtual patient cases to promote self-directed learning (SDL) in a required advanced therapeutics course. Design. Virtual patient software based on a branched-narrative decision-making model was used to create complex patient case simulations to replace lecture-based instruction. Within each simulation, students used SDL principles to learn course objectives, apply their knowledge through clinical recommendations, and assess their progress through patient outcomes and faculty feedback linked to their individual decisions. Group discussions followed each virtual patient case to provide further interpretation, clarification, and clinical perspective. Assessments. Students found the simulated patient cases to be organized (90%), enjoyable (82%), intellectually challenging (97%), and valuable to their understanding of course content (91%). Students further indicated that completion of the virtual patient cases prior to class permitted better use of class time (78%) and promoted SDL (84%). When assessment questions regarding material on postoperative nausea and vomiting were compared, no difference in scores were found between the students who attended the lecture on the material in 2011 (control group) and those who completed the virtual patient case on the material in 2012 (intervention group). Conclusion. Completion of virtual patient cases, designed to replace lectures and promote SDL, was overwhelmingly supported by students and proved to be as effective as traditional teaching methods. PMID:24052654

  4. Self-directed attention, awareness of bodily states, and suggestibility.

    PubMed

    Scheier, M F; Carver, C S; Gibbons, F X

    1979-09-01

    Two studies tested the hypothesis that self-directed attention would cause increased awareness of internal states and would thus reduce suggestibility effects. Experiment 1 applied this reasoning to the experience of an emotion. Males viewed moderately arousing slides of female nudes after being led to expect the slides to be either highly arousing or nonarousing. As predicted, ratings of the slides corresponded less with these experimentally-manipulated anticipations when self-focus was heightened by the presence of a mirror than when it was not. Experiment 2 examined a different internal experience: the perception of taste. Some subjects were led to expect a strong flavor as part of a test series, and other subjects were led to expect a weak flavor. Subjects high in private self-consciousness were less affected by this expectancy manipulation and more accurate in reporting their actual internal state than were subjects low in private self-consciousness. Discussion centers on the theoretical implications of the findings.

  5. Infection and cancer in multicellular organisms

    PubMed Central

    Ewald, Paul W.; Swain Ewald, Holly A.

    2015-01-01

    Evolutionary considerations suggest that oncogenic infections should be pervasive among animal species. Infection-associated cancers are well documented in humans and domestic animals, less commonly reported in undomesticated captive animals, and rarely documented in nature. In this paper, we review the literature associating infectious agents with cancer to evaluate the reasons for this pattern. Non-malignant infectious neoplasms occur pervasively in multicellular life, but oncogenic progression to malignancy is often uncertain. Evidence from humans and domestic animals shows that non-malignant infectious neoplasms can develop into cancer, although generally with low frequency. Malignant neoplasms could be difficult to find in nature because of a low frequency of oncogenic transformation, short survival after malignancy and reduced survival prior to malignancy. Moreover, the evaluation of malignancy can be ambiguous in nature, because criteria for malignancy may be difficult to apply consistently across species. The information available in the literature therefore does not allow for a definitive assessment of the pervasiveness of infectious cancers in nature, but the presence of infectious neoplasias and knowledge about the progression of benign neoplasias to cancer is consistent with a widespread but largely undetected occurrence. PMID:26056368

  6. Semiautomatic growth analysis of multicellular tumor spheroids.

    PubMed

    Rodday, Bjoern; Hirschhaeuser, Franziska; Walenta, Stefan; Mueller-Klieser, Wolfgang

    2011-10-01

    Multicellular tumor spheroids (MCTS) are routinely employed as three-dimensional in vitro models to study tumor biology. Cultivation of MCTS in spinner flasks provides better growing conditions, especially with regard to the availability of nutrients and oxygen, when compared with microtiter plates. The main endpoint of drug response experiments is spheroid size. It is common practice to analyze spheroid size manually with a microscope and an ocular micrometer. This requires removal of some spheroids from the flask, which entails major limitations such as loss of MCTS and the risk of contamination. With this new approach, the authors present an efficient and highly reproducible method to analyze the size of complete MCTS populations in culture containers with transparent, flat bottoms. MCTS sediments are digitally scanned and spheroid volumes are calculated by computerized image analysis. The equipment includes regular office hardware (personal computer, flatbed scanner) and software (Adobe Photoshop, Microsoft Excel, ImageJ). The accuracy and precision of the method were tested using industrial precision steel beads with known diameter. In summary, in comparison with other methods, this approach provides benefits in terms of semiautomation, noninvasiveness, and low costs.

  7. A confirmatory factor analysis of the Self-Directed Learning Readiness Scale.

    PubMed

    Williams, Brett; Brown, Ted

    2013-12-01

    The Self-Directed Learning Readiness Scale measures readiness for self-directed learning among undergraduate healthcare students. While several exploratory factor analyses and one confirmatory factor analysis have examined the psychometric properties of the Self-Directed Learning Readiness Scale, questions have been raised regarding the underlying latent constructs being measured. The objective of this study was to determine the best-fitting Self-Directed Learning Readiness Scale factorial structure among three models published in the literature. Data from the three-factor 40-item Self-Directed Learning Readiness Scale completed by 233 undergraduate paramedic students from four Australian universities (response rate of 26%) were analyzed using maximum likelihood confirmatory factor analysis. Comparison of model fit from the 40-item version was undertaken with the previously documented four-factor 36-item and three-factor 29-item Self-Directed Learning Readiness Scales. The model fit indices of the three one-factor congeneric models with maximum likelihood analysis demonstrate that the 40-item Self-Directed Learning Readiness Scale does not fit the data well. The best fitting model was the four-factor 36-item Self-Directed Learning Readiness Scale followed by the three-factor 29-item models. The confirmatory factor analysis results did not support the overall construct validity of the original 40-item Self-Directed Learning Readiness Scale.

  8. Carcinoma-associated fibroblasts: orchestrating the composition of malignancy

    PubMed Central

    Gascard, Philippe; Tlsty, Thea D.

    2016-01-01

    The tumor stroma is no longer seen solely as physical support for mutated epithelial cells but as an important modulator and even a driver of tumorigenicity. Within the tumor stromal milieu, heterogeneous populations of fibroblast-like cells, collectively termed carcinoma-associated fibroblasts (CAFs), are key players in the multicellular, stromal-dependent alterations that contribute to malignant initiation and progression. This review focuses on novel insights into the contributions of CAFs to disease progression, emergent events leading to the generation of CAFs, identification of CAF-specific biomarkers predictive of disease outcome, and recent therapeutic approaches aimed at blunting or reverting detrimental protumorigenic phenotypes associated with CAFs. PMID:27151975

  9. Ferritin nanocontainers that self-direct in synthetic polymer systems

    NASA Astrophysics Data System (ADS)

    Sengonul, Merih C.

    Currently, there are many approaches to introduce functionality into synthetic polymers. Among these, for example, are copolymerization, grafting, and blending methods. However, modifications made by such methods also change the thermodynamics and rheological properties of the polymer system of interest, and each new modification often requires a costly reoptimization of polymer processing. Such a reoptimalization would not be necessary if new functionality could be introduced via a container whose external surface is chemically and physically tuned to interact with the parent polymer. The contents of the container could then be changed without changing other important properties of the parent polymer. In this context this thesis project explores an innovative nanocontainer platform which can be introduced into phase-separating homopolymer blends. Ferritin is a naturally existing nanocontainer that can be used synthetically to package and selectively transport functional moieties to a particular phase that is either in the bulk or on the surface of a homopolymer blend system. The principal focus of this work centers on modifying the surface of wild ferritin to: (1) render modified ferritin soluble in a non-aqueous solvent; and (2) impart it with self-directing properties when exposed to a homopolymer blend surface or incorporated into the bulk of a homopolymer blend. Wild ferritin is water soluble, and this research project successfully modified wild ferritin by grafting either amine-functional poly(ethylene glycol) (PEG) or short-chain alkanes to carbodiimide activated carboxylate groups on ferritin's surface. Such modified ferritin is soluble in dichloromethane (DCM). Modification was confirmed by ion-exchange chromatography, zeta-potential measurements, and electrospray mass spectroscopy. FT-IR was used to quantify the extent of PEGylation of the reaction products through area ratios of the -C-O-C asymmetric stretching vibration of the grafted PEG chains to the

  10. Emotional Intelligence and Self-Directed Learning Readiness among College Students Participating in a Leadership Development Program

    ERIC Educational Resources Information Center

    Radnitzer, Karl David

    2010-01-01

    The purpose of this study was to investigate possible relationships between self-directed learning readiness and emotional intelligence in a leadership development program and if self-directed learning leads to greater self-directed learning capabilities. Prior research has examined self-directed learning and emotional intelligence but never have…

  11. Agent Based Modelling Helps in Understanding the Rules by Which Fibroblasts Support Keratinocyte Colony Formation

    PubMed Central

    Sun, Tao; McMinn, Phil; Holcombe, Mike; Smallwood, Rod; MacNeil, Sheila

    2008-01-01

    Background Autologous keratincoytes are routinely expanded using irradiated mouse fibroblasts and bovine serum for clinical use. With growing concerns about the safety of these xenobiotic materials, it is desirable to culture keratinocytes in media without animal derived products. An improved understanding of epithelial/mesenchymal interactions could assist in this. Methodology/Principal Findings A keratincyte/fibroblast o-culture model was developed by extending an agent-based keratinocyte colony formation model to include the response of keratinocytes to both fibroblasts and serum. The model was validated by comparison of the in virtuo and in vitro multicellular behaviour of keratinocytes and fibroblasts in single and co-culture in Greens medium. To test the robustness of the model, several properties of the fibroblasts were changed to investigate their influence on the multicellular morphogenesis of keratinocyes and fibroblasts. The model was then used to generate hypotheses to explore the interactions of both proliferative and growth arrested fibroblasts with keratinocytes. The key predictions arising from the model which were confirmed by in vitro experiments were that 1) the ratio of fibroblasts to keratinocytes would critically influence keratinocyte colony expansion, 2) this ratio needed to be optimum at the beginning of the co-culture, 3) proliferative fibroblasts would be more effective than irradiated cells in expanding keratinocytes and 4) in the presence of an adequate number of fibroblasts, keratinocyte expansion would be independent of serum. Conclusions A closely associated computational and biological approach is a powerful tool for understanding complex biological systems such as the interactions between keratinocytes and fibroblasts. The key outcome of this study is the finding that the early addition of a critical ratio of proliferative fibroblasts can give rapid keratinocyte expansion without the use of irradiated mouse fibroblasts and bovine

  12. Academic Performance and the Practice of Self-Directed Learning: The Adult Student Perspective

    ERIC Educational Resources Information Center

    Khiat, Henry

    2017-01-01

    The practice of self-directed learning is important to adult students as it allows them to learn effectively while juggling work, family and other commitments. This study set out to examine the self-directed learning characteristics present in the adult students' study process at the case university. The relationship between the adult students'…

  13. Self-Directed Teams in the Introductory Information Systems Course: Lessons Learned.

    ERIC Educational Resources Information Center

    Buffington, James R.

    Research clearly supports the efficacy of self-directed teams in the learning of information systems (IS) skills. This paper proposes that the use of self-directed teams demands a considerable amount of direction on the part of the instructor. Students in two sections of an introductory IS class were surveyed with explicit questions about their…

  14. Influence of Adult Goal-Setting Instruction on Students' Responsibility toward Self-Directed Competencies

    ERIC Educational Resources Information Center

    Apa Browne, Lynn Geri

    2014-01-01

    Elementary grade students in a mid-Atlantic state school district have not been meeting academic standards on state assessments. Research indicates that academic achievement is connected to self-directed readiness to learn; however, often the instruction in strategies for student self-directed readiness to learn remains teacher-centered. The…

  15. Exploring First-Year Undergraduate Medical Students' Self-Directed Learning Readiness to Physiology

    ERIC Educational Resources Information Center

    Abraham, Reem Rachel; Fisher, Murray; Kamath, Asha; Izzati, T. Aizan; Nabila, Saidatul; Atikah, Nik Nur

    2011-01-01

    Medical students are expected to possess self-directed learning skills to pursue lifelong learning. Previous studies have reported that the readiness for self-directed learning depends on personal attributes as well as the curriculum followed in institutions. Melaka Manipal Medical College of Manipal University (Karnataka, India) offers a Bachelor…

  16. Assessment of Animated Self-Directed Learning Activities Modules for Children's Number Sense Development

    ERIC Educational Resources Information Center

    Yang, Der-Ching; Li, Mao-Neng

    2013-01-01

    The purpose of this study was to examine the relative effectiveness of two different learning modes; namely, a computer animation self-directed learning approach and a paper version of the self-directed learning approach, to 5th-graders' number sense development. Two 5th-grade classes, 30 students each, were selected from a public elementary…

  17. Self-Directed Learning and Schooling: Identifying Pertinent Theories and Illustrative Research.

    ERIC Educational Resources Information Center

    Skager, Rodney

    1979-01-01

    Six theoretical positions on human learning are identified as relevant to the development of self-direction: modeling; reinforcement; curiosity motivation; competency motivation; attribution theory and personal causation; and humanism. Four approaches to educational practice associated with self-direction are identified: experimental learning;…

  18. Developing a Self-Directed Computer Training Program for El Camino College Faculty.

    ERIC Educational Resources Information Center

    McAllister, Donald F.

    The purposes of this study were to: (1) establish existing computer literacy levels among faculty members at El Camino College, California; (2) determine the principal obstacles to self-directed computer training, along with strategies designed to overcome these obstacles; and (3) develop recommendations concerning the structure of self-directed,…

  19. Preferences of a Traditional Extension Audience for Self-Directed Delivery Methods.

    ERIC Educational Resources Information Center

    Caldwell, Allen E.; Richardson, John G.

    1995-01-01

    North Carolina farmers growing barley (n=20) tested 3 self-directed information delivery methods: fact sheets, fact sheets plus audiocassettes, and an extension bulletin/pamphlet. The fact sheet/cassette was preferred by 17 of 20; they achieved significant knowledge gains with self-directed methods. The fact sheet/cassette was considered…

  20. Measuring Self-Directed Learning: A Diagnostic Tool for Adult Learners

    ERIC Educational Resources Information Center

    Khiat, Henry

    2015-01-01

    Self-directed learning is an important form of adult learning (Caffarella, 1993; Knowles, 1975; Knowles, Holton & Swanson, 2005; Merriam, 2001; Merriam & Caffarella, 1999). The strategies of self-directed learning allow adult learners to cope better with their studies while fulfilling family, work and other commitments. This study…

  1. I Feel, Therefore, I Learn: The Role of Emotion in Self-Directed Learning

    ERIC Educational Resources Information Center

    Rager, Kathleen B.

    2009-01-01

    It is rare to find the emotional component of self-directed learning discussed explicitly in the literature. This lack is particularly glaring given the interest sparked by recent brain research concerning the importance of emotion in all types of learning as well as by the dramatic increase in self-directed learning in the emotionally charged…

  2. Using Study Plans to Develop Self-Directed Learning Skills: Implications from a Pilot Project

    ERIC Educational Resources Information Center

    Du, Fengning

    2012-01-01

    Self-directed learning has been lauded as a powerful learner-centered approach to involve students in every aspect of their learning. This article depicts a pilot project utilizing study plan as a vehicle to promote self-directed learning in an intensive and teacher-dominant college language program. This article seeks to identify both the…

  3. The Readiness of Adults with Attention Deficit Hyperactivity Disorder for Self-Directed Learning

    ERIC Educational Resources Information Center

    Wright, Melissa Sue

    2011-01-01

    This study investigated the readiness for self-directed learning of adults with Attention Deficit Hyperactivity Disorder (ADHD), as well as their overall educational experiences. Using Guglielmino's Self-Directed Learning Readiness Scale for Adults (SDLRS-A), the researcher investigated whether the following factors were significantly related to…

  4. Self-Directed Learning: A 2-Year, 4-Year Collaboration for Engineering Students. Working Paper Series.

    ERIC Educational Resources Information Center

    Beston, William; Fellows, Sharon; Culver, Richard

    This paper describes the joint collaboration of Broome Community College (BCC) (New York) and the State University of New York at Binghamton to help their engineering students become self-directed learners (SDL). Gerald Grow's model for staged self-directed learning is presented as a framework for the collaboration, with its four stages of student…

  5. A Framework for Developing Self-Directed Technology Use for Language Learning

    ERIC Educational Resources Information Center

    Lai, Chun

    2013-01-01

    Critical to maximizing the potential of technology for learning is enhancing language learners' self-directed use of technology for learning purposes. This study aimed to enhance our understanding of the determinants of self-directed technology use through the construction of a structural equation modelling (SEM) framework of factors and…

  6. Conditions Enhancing Self-Directed Learning in the Workplace. A Report to the Participants.

    ERIC Educational Resources Information Center

    1992

    The appreciative inquiry process was used to identify conditions enhancing self-directed learning. Participants in the project did the following: (1) used the five-step process to identify factors/conditions/forces that seemed to cause self-directed learning to occur; (2) created a matrix by combining the factors/conditions/forces with six…

  7. The Relationship between Transformational Leadership and Knowledge Workers' Self-Directed Learning Readiness

    ERIC Educational Resources Information Center

    Aparicio, Ricardo Antonio

    2013-01-01

    The rapid pace of change for knowledge workers competing globally necessitates ongoing continuous learning. Increasingly, knowledge workers will need to be ready--willing and able--to engage in self-directed learning. This makes it important to understand what factors in the work environment might be related to the self-directed learning…

  8. Two Decades of Literature on Self-Directed Learning: A Content Analysis.

    ERIC Educational Resources Information Center

    Brockett, Ralph G.; Stockdale, Susan L.; Fogerson, Dewey L.; Cox, Barry F.; Canipe, James B.; Chuprina, Larissa A.; Donaghy, Robert C.; Chadwell, Nancy E.

    Using a quantitative content analysis approach, a study examined the literature on self direction, or self-directed learning (SDL), that appeared in 14 mainstream adult education journals between 1980-98. The procedure involved classifying, entering, and tallying information on each article through use of an Internet-based program. Results…

  9. The Effects of Self-Directed Teams in an Automotive Manufacturing Environment

    ERIC Educational Resources Information Center

    Shall, David W.

    2010-01-01

    This study compares self-directed work structures to more traditional supervised work structures in order to determine if the expenditures and efforts required to implement self-directed work teams are warranted. Multiple internal performance metrics are examined in comparing plant work structures in various degrees of implementation between…

  10. Self Directed Support and People with Learning Disabilities: A Review of the Published Research Evidence

    ERIC Educational Resources Information Center

    Harkes, Mary Anne; Brown, Michael; Horsburgh, Dorothy

    2014-01-01

    A systematic literature review was undertaken to determine the evidence base underpinning the strategy of Self Directed Support and whether evidence demonstrates that this policy is accessible to everyone with a learning disability. It also sought to identify whether there were any barriers to Self Directed Support for people with severe or…

  11. Knowledge and Attitudes Associated with Self-Directed and Interpersonal Violent Behaviors among Adolescents.

    ERIC Educational Resources Information Center

    Kotecki, Jerome E.; Torabi, Mohammad R.

    1997-01-01

    Analysis of data from the National Adolescent Student Health Survey examined relationships among knowledge, attitude, and behaviors related to interpersonal and self-directed violence. Results found significant relationships among self-directed violence and knowledge, belief, feeling, and intention to act and between interpersonal violent…

  12. Self-Directed Learning in Gross Human Anatomy: Assessment Outcomes and Student Perceptions

    ERIC Educational Resources Information Center

    Smythe, Gayle; Hughes, Diane

    2008-01-01

    Speech pathology students enrolled in a lecture-based gross human anatomy program completed two out of nine topics in self-directed mode. Student performance in quizzes was compared for the two modes, and the students completed questionnaires on their perceptions of the self-directed mode of delivery. Students performed as well in the first…

  13. SELF-DIRECTED LEARNING, TEAMWORK, HOLISTIC VIEW AND ORAL HEALTH.

    PubMed

    Leisnert, Leif

    2014-01-01

    The dental program at the Malmö Dental School, the so called Malmö-model, is guided by four linked principles: self-directed learning, teamwork, a holistic view of patient care, and oral health (Fig.1). Self-assessment ability is a critical competence for healthcare professionals, necessary for the successful adaptation to the modern life-long learning environment. Educational research seems to point out two critical factors for the development of such skills, continuous practice of self-assessment and constructive feedback. The first study presented in this thesis assessed students' self-assessment ability by means of the Interactive Examination in a cohort of senior dental students, who had gone through an identical assessment procedure during their second year of studies. The results indicated that self-assessment ability was not directly relevant to subject knowledge. Upon graduation, there were a number of students (10%) with significant self-assessment difficulties. Early detection of students with weak self-assessment abilities appears possible to achieve. The aim of the second study, concerning teamwork and holistic view, was to investigate if highlighting teamwork between dental and dental hygienist students could improve the students' holistic view on patients, as well as their knowledge of, and insight into, each other's future professions. This project showed that by initiating teamwork between dental and dental hygienist students, it was possible to increase students' knowledge on dental hygienists competence, develop students' perceived holistic view on patients, and prepare students for teamwork. The third study explored findings clinicians used when diagnosing chronic periodontitis. A questionnaire was distributed to students, dental teachers and clinical supervisors in the Public Dental Services. Within all categories of clinicians, the majority of the clinicians used deepened pocket, bone loss on x-rays, and bleeding as findings. There were

  14. Triassic origin and early radiation of multicellular volvocine algae.

    PubMed

    Herron, Matthew D; Hackett, Jeremiah D; Aylward, Frank O; Michod, Richard E

    2009-03-03

    Evolutionary transitions in individuality (ETIs) underlie the watershed events in the history of life on Earth, including the origins of cells, eukaryotes, plants, animals, and fungi. Each of these events constitutes an increase in the level of complexity, as groups of individuals become individuals in their own right. Among the best-studied ETIs is the origin of multicellularity in the green alga Volvox, a model system for the evolution of multicellularity and cellular differentiation. Since its divergence from unicellular ancestors, Volvox has evolved into a highly integrated multicellular organism with cellular specialization, a complex developmental program, and a high degree of coordination among cells. Remarkably, all of these changes were previously thought to have occurred in the last 50-75 million years. Here we estimate divergence times using a multigene data set with multiple fossil calibrations and use these estimates to infer the times of developmental changes relevant to the evolution of multicellularity. Our results show that Volvox diverged from unicellular ancestors at least 200 million years ago. Two key innovations resulting from an early cycle of cooperation, conflict and conflict mediation led to a rapid integration and radiation of multicellular forms in this group. This is the only ETI for which a detailed timeline has been established, but multilevel selection theory predicts that similar changes must have occurred during other ETIs.

  15. Multicellularity in green algae: upsizing in a walled complex

    PubMed Central

    Domozych, David S.; Domozych, Catherine E.

    2014-01-01

    Modern green algae constitute a large and diverse taxonomic assemblage that encompasses many multicellular phenotypes including colonial, filamentous, and parenchymatous forms. In all multicellular green algae, each cell is surrounded by an extracellular matrix (ECM), most often in the form of a cell wall. Volvocalean taxa like Volvox have an elaborate, gel-like, hydroxyproline rich glycoprotein covering that contains the cells of the colony. In “ulvophytes,” uronic acid-rich and sulfated polysaccharides are the likely adhesion agents that maintain the multicellular habit. Charophytes also produce polysaccharide-rich cell walls and in late divergent taxa, pectin plays a critical role in cell adhesion in the multicellular complex. Cell walls are products of coordinated interaction of membrane trafficking, cytoskeletal dynamics and the cell’s signal transduction machinery responding both to precise internal clocks and external environmental cues. Most often, these activities must be synchronized with the secretion, deposition and remodeling of the polymers of the ECM. Rapid advances in molecular genetics, cell biology and cell wall biochemistry of green algae will soon provide new insights into the evolution and subcellular processes leading to multicellularity. PMID:25477895

  16. A conceptual framework for the evolutionary origins of multicellularity

    NASA Astrophysics Data System (ADS)

    Libby, Eric; Rainey, Paul B.

    2013-06-01

    The evolution of multicellular organisms from unicellular counterparts involved a transition in Darwinian individuality from single cells to groups. A particular challenge is to understand the nature of the earliest groups, the causes of their evolution, and the opportunities for emergence of Darwinian properties. Here we outline a conceptual framework based on a logical set of possible pathways for evolution of the simplest self-replicating groups. Central to these pathways is the recognition of a finite number of routes by which genetic information can be transmitted between individual cells and groups. We describe the form and organization of each primordial group state and consider factors affecting persistence and evolution of the nascent multicellular forms. Implications arising from our conceptual framework become apparent when attempting to partition fitness effects at individual and group levels. These are discussed with reference to the evolutionary emergence of individuality and its manifestation in extant multicellular life—including those of marginal Darwinian status.

  17. Fungal Cell Cycle: A Unicellular versus Multicellular Comparison.

    PubMed

    Dörter, Ilkay; Momany, Michelle

    2016-12-01

    All cells must accurately replicate DNA and partition it to daughter cells. The basic cell cycle machinery is highly conserved among eukaryotes. Most of the mechanisms that control the cell cycle were worked out in fungal cells, taking advantage of their powerful genetics and rapid duplication times. Here we describe the cell cycles of the unicellular budding yeast Saccharomyces cerevisiae and the multicellular filamentous fungus Aspergillus nidulans. We compare and contrast morphological landmarks of G1, S, G2, and M phases, molecular mechanisms that drive cell cycle progression, and checkpoints in these model unicellular and multicellular fungal systems.

  18. Readiness for self-directed learning among nursing students in Thailand.

    PubMed

    Klunklin, Areewan; Viseskul, Nongkran; Sripusanapan, Acharaporn; Turale, Sue

    2010-06-01

    This study took place in Thailand where didactic and lecture-driven teaching styles are beginning to transform into student-centered methods. At Chiang Mai University Faculty of Nursing in Thailand, the readiness of 272 undergraduate students to undertake self-directed learning was investigated using two instruments: a demographic data questionnaire and Guglielmino's Self Directed Learning Readiness Scale. The study found that the overall self-directed learning readiness of participants was at a high level in the categories of openness to learning opportunities, self-concept as an effective learner, initiative and independence in learning, informed acceptance of responsibility for one's own learning, creativity, and the ability to use basic study and problem-solving skills. The findings provide encouragement to nurse educators to further apply self-directed learning in nursing courses, to improve teaching and learning methods, and promote life-long learning for nurses within Thailand and elsewhere.

  19. On the teaching model of website-based collaborated self-directed study

    NASA Astrophysics Data System (ADS)

    Jing, Zhihua; Zeng, Yingxiong; Wen, Chunyu

    2011-12-01

    Based on the theory of collaborated self-directed study and the strengths of modern education technology, the study explores application of websites for collaborated self-directed college English learning. It introduces the characteristics and functions of the website developed to assist college English teaching in China. It also points out the problems currently existing among teachers and students, and puts forward some suggestions and strategies for the improvement of the application of the website.

  20. Deconstructing the effect of self-directed study on episodic memory.

    PubMed

    Markant, Douglas; DuBrow, Sarah; Davachi, Lila; Gureckis, Todd M

    2014-11-01

    Self-directed learning is often associated with better long-term memory retention; however, the mechanisms that underlie this advantage remain poorly understood. This series of experiments was designed to "deconstruct" the notion of self-directed learning, in order to better identify the factors most responsible for these improvements to memory. In particular, we isolated the memory advantage that comes from controlling the content of study episodes from the advantage that comes from controlling the timing of those episodes. Across four experiments, self-directed learning significantly enhanced recognition memory, relative to passive observation. However, the advantage for self-directed learning was found to be present even under extremely minimal conditions of volitional control (simply pressing a button when a participant was ready to advance to the next item). Our results suggest that improvements to memory following self-directed encoding may be related to the ability to coordinate stimulus presentation with the learner's current preparatory or attentional state, and they highlight the need to consider the range of cognitive control processes involved in and influenced by self-directed study.

  1. Self-directed learning in gross human anatomy: assessment outcomes and student perceptions.

    PubMed

    Smythe, Gayle; Hughes, Diane

    2008-01-01

    Speech pathology students enrolled in a lecture-based gross human anatomy program completed two out of nine topics in self-directed mode. Student performance in quizzes was compared for the two modes, and the students completed questionnaires on their perceptions of the self-directed mode of delivery. Students performed as well in the first self-directed topic as they did in lecture-based material, but performance declined significantly on the second self-directed topic. Correlations showed that students who performed well in lecture-based topics also performed well on self-directed topics. The major issues that arose in the student questionnaires were primarily related to the amount of content in the topics and the length of time required for completion. We conclude that there is a strong need for appropriate design of distance education materials to reflect student perceptions of length, content, and time investment, and more importantly that there is a need to ensure extensive communication and support of students studying in distance education/self-directed modes for the first time.

  2. The Impact of Advanced Pharmacy Practice Experiences on Students' Readiness for Self-directed Learning

    PubMed Central

    Haines, Stuart T.; Plaza, Cecilia M.; Sturpe, Deborah A.; Williams, Greg; Rodriguez de Bittner, Magaly A.; Roffman, David S.

    2009-01-01

    Objective To evaluate the impact of advanced pharmacy practice experiences (APPEs) on doctor of pharmacy (PharmD) students' readiness for self-directed learning. Methods The Self-Directed Learning Readiness Scale (SDLRS) was administered to students prior to and after completing their APPEs. SDLRS is a validated instrument that determines the relative degree to which students have the attitudes and motivation to engage in self-directed learning. Results Seventy-seven (64%) students completed the SDLRS prior to starting their APPEs and 80 (67%) students completed the instrument after completing their APPEs. Forty-six (38%) students completed both. Prior to starting their APPEs, 74% of students scored greater than 150 on the SDLRS, indicating a high level of readiness for self-directed learning. No significant difference was found between the mean scores of students who took the SDLRS both prior to (159 ± 20) and after completing their APPEs (159 ± 24; p > 0.05). Conclusion Students at our institution appear to be ready for self-directed learning but APPEs had a minimal impact on their readiness for self-directed learning. PMID:19657498

  3. Regulated aggregative multicellularity in a close unicellular relative of metazoa

    PubMed Central

    Sebé-Pedrós, Arnau; Irimia, Manuel; del Campo, Javier; Parra-Acero, Helena; Russ, Carsten; Nusbaum, Chad; Blencowe, Benjamin J; Ruiz-Trillo, Iñaki

    2013-01-01

    The evolution of metazoans from their unicellular ancestors was one of the most important events in the history of life. However, the cellular and genetic changes that ultimately led to the evolution of multicellularity are not known. In this study, we describe an aggregative multicellular stage in the protist Capsaspora owczarzaki, a close unicellular relative of metazoans. Remarkably, transition to the aggregative stage is associated with significant upregulation of orthologs of genes known to establish multicellularity and tissue architecture in metazoans. We further observe transitions in regulated alternative splicing during the C. owczarzaki life cycle, including the deployment of an exon network associated with signaling, a feature of splicing regulation so far only observed in metazoans. Our results reveal the existence of a highly regulated aggregative stage in C. owczarzaki and further suggest that features of aggregative behavior in an ancestral protist may had been co-opted to develop some multicellular properties currently seen in metazoans. DOI: http://dx.doi.org/10.7554/eLife.01287.001 PMID:24368732

  4. Regulated aggregative multicellularity in a close unicellular relative of metazoa.

    PubMed

    Sebé-Pedrós, Arnau; Irimia, Manuel; Del Campo, Javier; Parra-Acero, Helena; Russ, Carsten; Nusbaum, Chad; Blencowe, Benjamin J; Ruiz-Trillo, Iñaki

    2013-12-24

    The evolution of metazoans from their unicellular ancestors was one of the most important events in the history of life. However, the cellular and genetic changes that ultimately led to the evolution of multicellularity are not known. In this study, we describe an aggregative multicellular stage in the protist Capsaspora owczarzaki, a close unicellular relative of metazoans. Remarkably, transition to the aggregative stage is associated with significant upregulation of orthologs of genes known to establish multicellularity and tissue architecture in metazoans. We further observe transitions in regulated alternative splicing during the C. owczarzaki life cycle, including the deployment of an exon network associated with signaling, a feature of splicing regulation so far only observed in metazoans. Our results reveal the existence of a highly regulated aggregative stage in C. owczarzaki and further suggest that features of aggregative behavior in an ancestral protist may had been co-opted to develop some multicellular properties currently seen in metazoans. DOI: http://dx.doi.org/10.7554/eLife.01287.001.

  5. Multicellular Secretory Trichome Development on Soybean and Related Glycine Gynoecia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multicellular glandular trichomes form on gynoecia of wild Glycine annual species, annual soybean cultivars, and wild perennial species. These trichomes occur on gynoecia of annual taxa from ovary base to style base, and along style of perennial species. Trichomes form at least two days prior to ant...

  6. Phenotypic Diversity of Multicellular Filamentation in Oral Streptococci

    PubMed Central

    Thurnheer, Thomas; Bagheri, Homayoun C.; Belibasakis, Georgios N.

    2013-01-01

    Filamentous multicellular bacteria are among the most ancient multicellular organisms. They inhabit a great variety of environments and are present in the human body, including the oral cavity. Beside the selective advantages related to the larger size achieved through filamentation, the development of multicellular bacteria can be also driven by simple ecological factors such as birth and death rates at the cellular level. In order to extend earlier results obtained in aquatic species, we investigate the filamentation process of four different strains of oral streptococci, namely S. mutans, S. salivarius, S. oralis and S. anginosus. The results indicate differences in the capacities of different streptococcus species to form filaments, manifested in terms of length and the time-scale of filament elongation. The filamentation pattern of these oral streptococci resembles that of aquatic bacteria, whereby filaments reach a peak length during exponential growth and become short when the population reaches a steady state. Hence, this study validates that multicellularity can be an emergent property of filamentous bacteria of different ecological niches, and that phenotypic differences in filamentation can occur within species of the same genus, in this case oral streptococci. Moreover, given the role that specific oral streptococci can play in the etiology of oral diseases, these results can possibly open new perspectives in the study of the virulence properties of these species. PMID:24086713

  7. Dynamics of self-directed learning in M.Sc. nursing students: A qualitative research

    PubMed Central

    SHIRAZI, FATEMEH; SHARIF, FARKHONDEH; MOLAZEM, ZAHRA; ALBORZI, MAHBOOBEH

    2017-01-01

    Introduction: Working in the complex and ever changing healthcare settings forces the nurses and nursing students to be equipped with lifelong learning skills. One of the lifelong learning skills is self-directed learning. This study aimed to explore the M.Sc. nursing students’ self-directed learning activities. Methods: A qualitative design using conventional content analysis approach was used in this study. Semi-structured interviews were conducted with twelve Iranian M.Sc. nursing students who were selected using purposive sampling. Results: Data analysis indicated that the M.Sc. nursing students performed different activities in their self-directed learning. These activities were categorized into four main themes and ten subthemes. The main themes were “sensory perceptions”, “knowledge construction”, “problem-centered orientation”, and “interaction with others”. Conclusion: According to the findings, the M.Sc. nursing students performed different intellectual and experiential self-directed activities for promoting their learning. Besides, the students’ perseverance and inquisitiveness played an important role in their self-directed learning in the challenging clinical environments. PMID:28124019

  8. Development of a supported self-directed learning approach for anatomy education.

    PubMed

    Findlater, Gordon S; Kristmundsdottir, Fanney; Parson, Simon H; Gillingwater, Thomas H

    2012-01-01

    The ability to deliver sufficient core anatomical knowledge and understanding to medical students with limited time and resources remains a major challenge for anatomy educators. Here, we report the results of switching from a primarily didactic method of teaching to supported self-directed learning for students studying anatomy as part of undergraduate medicine at the University of Edinburgh. The supported self-directed approach we have developed makes use of an integrated range of resources, including formal lectures and practical sessions (incorporating gross anatomy specimens, medical imaging technologies, anatomical models, clinical scenarios, and surface anatomy workstations). In practical sessions, students are provided with a custom-made workbook that guides them through each session, with academic staff, postgraduate tutors, and near-peer teaching assistants present to deal with misunderstandings and explain more complicated topics. This approach retains many of the best attributes of didactic teaching but blends them with the advantages associated with self-directed learning approaches. The switch to supported self-directed learning-initially introduced in 2005-resulted in a significant improvement in anatomy examination scores over the subsequent period of five years, manifesting as an increase in the average anatomy practical spot examination mark, less students failing to obtain the pass mark and more students passing with distinction. We conclude that the introduction of supported self-directed learning improved students' engagement, leading to deeper learning and better understanding and knowledge of anatomy.

  9. A multicellular view of cytokinesis in epithelial tissue.

    PubMed

    Herszterg, Sophie; Pinheiro, Diana; Bellaïche, Yohanns

    2014-05-01

    The study of cytokinesis in single-cell systems provided a wealth of knowledge on the molecular and biophysical mechanisms controlling daughter cell separation. In this review, we outline recent advances in the understanding of cytokinesis in epithelial tissues. These findings provide evidence for how the cytokinetic machinery adapts to a multicellular context and how the cytokinetic machinery is itself exploited by the tissue for the preservation of tissue function and architecture during proliferation. We propose that cytokinesis in epithelia should be viewed as a multicellular process, whereby the biochemical and mechanical interactions between the dividing cell and its neighbors are essential for successful daughter cell separation while defining epithelial tissue organization and preserving tissue integrity.

  10. Yeast biofilm colony as an orchestrated multicellular organism.

    PubMed

    Sťovíček, Vratislav; Váchová, Libuše; Palková, Zdena

    2012-03-01

    Although still often considered as simple unicellular organisms, in natural settings yeast cells tend to organize into intricate multicellular communities. Due to specific mechanisms only feasible at the population level, their capacity for social behavior is advantageous for their survival in a harmful environment. Feral Saccharomyces cerevisiae strains form complex structured colonies, which display many properties typical of natural biofilms causing (among others) serious infections in the human body. In our recent paper, we looked inside a growing colony using two-photon confocal microscopy. This allowed us to elucidate its three-dimensional colony architecture and some mechanisms responsible for community protection. Moreover, we showed how particular protective mechanisms complement each other during colony development and how each of them contributes to its defense against attacks from the environment. Our findings broaden current understanding of microbial multicellularity in general and also shed new light on the enormous resistance of yeast biofilms.

  11. Three-dimensional vertex model for simulating multicellular morphogenesis

    PubMed Central

    Okuda, Satoru; Inoue, Yasuhiro; Adachi, Taiji

    2015-01-01

    During morphogenesis, various cellular activities are spatiotemporally coordinated on the protein regulatory background to construct the complicated, three-dimensional (3D) structures of organs. Computational simulations using 3D vertex models have been the focus of efforts to approach the mechanisms underlying 3D multicellular constructions, such as dynamics of the 3D monolayer or multilayer cell sheet like epithelia as well as the 3D compacted cell aggregate, including dynamic changes in layer structures. 3D vertex models enable the quantitative simulation of multicellular morphogenesis on the basis of single-cell mechanics, with complete control of various cellular activities such as cell contraction, growth, rearrangement, division, and death. This review describes the general use of the 3D vertex model, along with its applications to several simplified problems of developmental phenomena. PMID:27493850

  12. Mechanical Control of Cell flow in Multicellular Spheroids

    NASA Astrophysics Data System (ADS)

    Delarue, Morgan; Montel, Fabien; Caen, Ouriel; Elgeti, Jens; Siaugue, Jean-Michel; Vignjevic, Danijela; Prost, Jacques; Joanny, Jean-François; Cappello, Giovanni

    2013-03-01

    Collective cell motion is observed in a wide range of biological processes. In tumors, physiological gradients of nutrients, growth factors, or even oxygen give rise to gradients of proliferation. We show using fluorescently labeled particles that these gradients drive a velocity field resulting in a cellular flow in multicellular spheroids. Under mechanical stress, the cellular flow is drastically reduced. We describe the results with a hydrodynamic model that considers only convection of the particles by the cellular flow.

  13. Multi-cellular, three-dimensional living mammalian tissue

    NASA Technical Reports Server (NTRS)

    Goodwin, Thomas J. (Inventor); Wolf, David A. (Inventor)

    1994-01-01

    The present invention relates to a multicellular, three-dimensional, living mammalian tissue. The tissue is produced by a co-culture process wherein two distinct types of mammalian cells are co-cultured in a rotating bioreactor which is completely filled with culture media and cell attachment substrates. As the size of the tissue assemblies formed on the attachment substrates changes, the rotation of the bioreactor is adjusted accordingly.

  14. Detecting tree-like multicellular life on extrasolar planets.

    PubMed

    Doughty, Christopher E; Wolf, Adam

    2010-11-01

    Over the next two decades, NASA and ESA are planning a series of space-based observatories to find Earth-like planets and determine whether life exists on these planets. Previous studies have assessed the likelihood of detecting life through signs of biogenic gases in the atmosphere or a red edge. Biogenic gases and the red edge could be signs of either single-celled or multicellular life. In this study, we propose a technique with which to determine whether tree-like multicellular life exists on extrasolar planets. For multicellular photosynthetic organisms on Earth, competition for light and the need to transport water and nutrients has led to a tree-like body plan characterized by hierarchical branching networks. This design results in a distinct bidirectional reflectance distribution function (BRDF) that causes differing reflectance at different sun/view geometries. BRDF arises from the changing visibility of the shadows cast by objects, and the presence of tree-like structures is clearly distinguishable from flat ground with the same reflectance spectrum. We examined whether the BRDF could detect the existence of tree-like structures on an extrasolar planet by using changes in planetary albedo as a planet orbits its star. We used a semi-empirical BRDF model to simulate vegetation reflectance at different planetary phase angles and both simulated and real cloud cover to calculate disk and rotation-averaged planetary albedo for a vegetated and non-vegetated planet with abundant liquid water. We found that even if the entire planetary albedo were rendered to a single pixel, the rate of increase of albedo as a planet approaches full illumination would be comparatively greater on a vegetated planet than on a non-vegetated planet. Depending on how accurately planetary cloud cover can be resolved and the capabilities of the coronagraph to resolve exoplanets, this technique could theoretically detect tree-like multicellular life on exoplanets in 50 stellar systems.

  15. Controllability in Hybrid Kinetic Equations Modeling Nonequilibrium Multicellular Systems

    PubMed Central

    Bianca, Carlo

    2013-01-01

    This paper is concerned with the derivation of hybrid kinetic partial integrodifferential equations that can be proposed for the mathematical modeling of multicellular systems subjected to external force fields and characterized by nonconservative interactions. In order to prevent an uncontrolled time evolution of the moments of the solution, a control operator is introduced which is based on the Gaussian thermostat. Specifically, the analysis shows that the moments are solution of a Riccati-type differential equation. PMID:24191137

  16. SKOLAR MD: A Model for Self-Directed, In-Context Continuing Medical Education

    PubMed Central

    Strasberg, Howard R.; Rindfleisch, Thomas C.; Hardy, Steven

    2003-01-01

    INTRODUCTION SKOLAR has implemented a web-based CME program with which physicians can earn AMA Category 1 credit for self-directed learning. METHODS Physicians researched their questions in SKOLAR and applied for CME. Physician auditors reviewed all requests across two phases of the project. A selection rule set was derived from phase one and used in phase two to flag a subset of requests for detailed review. The selection rule set is described. RESULTS In phase one, SKOLAR received 1039 CME applications. Applicants frequently found their answer (94%) and would apply it clinically (93%). A linear regression analysis comparing time awarded to time requested (capped at actual time spent) had R2=0.79. DISCUSSION We believe that hat this self-directed approach to CME is effective and an important complement to traditional CME programs. However, selective audit of self-directed CME requests is necessary to ensure validity of credits awarded. PMID:14728250

  17. Quantitative multivariate analysis of dynamic multicellular morphogenic trajectories.

    PubMed

    White, Douglas E; Sylvester, Jonathan B; Levario, Thomas J; Lu, Hang; Streelman, J Todd; McDevitt, Todd C; Kemp, Melissa L

    2015-07-01

    Interrogating fundamental cell biology principles that govern tissue morphogenesis is critical to better understanding of developmental biology and engineering novel multicellular systems. Recently, functional micro-tissues derived from pluripotent embryonic stem cell (ESC) aggregates have provided novel platforms for experimental investigation; however elucidating the factors directing emergent spatial phenotypic patterns remains a significant challenge. Computational modelling techniques offer a unique complementary approach to probe mechanisms regulating morphogenic processes and provide a wealth of spatio-temporal data, but quantitative analysis of simulations and comparison to experimental data is extremely difficult. Quantitative descriptions of spatial phenomena across multiple systems and scales would enable unprecedented comparisons of computational simulations with experimental systems, thereby leveraging the inherent power of computational methods to interrogate the mechanisms governing emergent properties of multicellular biology. To address these challenges, we developed a portable pattern recognition pipeline consisting of: the conversion of cellular images into networks, extraction of novel features via network analysis, and generation of morphogenic trajectories. This novel methodology enabled the quantitative description of morphogenic pattern trajectories that could be compared across diverse systems: computational modelling of multicellular structures, differentiation of stem cell aggregates, and gastrulation of cichlid fish. Moreover, this method identified novel spatio-temporal features associated with different stages of embryo gastrulation, and elucidated a complex paracrine mechanism capable of explaining spatiotemporal pattern kinetic differences in ESC aggregates of different sizes.

  18. Self-directed learning competence assessment within different healthcare professionals and amongst students in Italy.

    PubMed

    Cadorin, Lucia; Suter, Nicoletta; Dante, Angelo; Williamson, Swapna Naskar; Devetti, Angie; Palese, Alvisa

    2012-05-01

    In the last few years the significance of life-long learning skills has been greatly realised with regard to adult learning, which is based on self-motivation, engagement in learning and making full use of a person's resources. In this context, it is paramount that healthcare professionals take responsibility for their profession by being innovative, creative and flexible to change in order to facilitate the adaptation process and encourage responsiveness to change. The main principles can be summarized as lifelong learning, which are strictly linked to self-directed learning. The aims of this study were to describe (a) the self-directed learning competence of nurses (registered nurse, RN) and radiologist technicians (RT); (b) the self-directed learning competence of RN and RT students before their graduation. A comparative cross-sectional study approach was adopted; a consecutive sample of RNs and RTs attending continuing education seminars, workshops and other initiatives from 2009 to 2010 were considered for this study. Moreover, all nursing and radiology technicians students about to graduate in the same course and studying in the same region were included. The self-rating scale of self-directed learning (SRSSDL) was used to collect data for the purpose of the study. Eight hundred and forty-seven participants were involved (453 RNs, 141 RTs, 182 RN students and 68 RT students) who obtained an average SRSSDL score of 224.7 (±25.0). RNs and RTs got on average a medium-high score (229.1 ± 22.9 and 219.6 ± 29.2, respectively) and the majority of them (63.8-51.1%) reached a high level of self-directed learning. In order to promote tailored continuing education programs and interprofessional continuing education strategies, and identify the support to offer to healthcare workers according to their needs, educators should be aware of their self-directed learning skills. Therefore, individuals with high competence should adopt different strategies from those who

  19. Applying Self-Directed Learning Principles in the Technical Training of a High-Risk Industry.

    ERIC Educational Resources Information Center

    Blackwood, Constance C.

    1994-01-01

    Experience with nuclear power plant workers for whom continuing education is mandated yielded techniques for incorporating self-direction to overcome resistance: educate management, involve workers, know the audience, incorporate feedback in training plans, be consistent, use learning contracts, motivate learners, use alternative methods, build…

  20. Individually Guided Motivation: Goal-Setting Procedures to Develop Student Self-Direction and Prosocial Behaviors.

    ERIC Educational Resources Information Center

    Klausmeier, Herbert J.; And Others

    This paper describes research and development activities dealing with a system of individually guided motivation at a Wisconsin elementary school. Four general objectives for the project are stated. These deal with motivation for learning subject matter knowledge and skills, developing independence, assuming increasing self direction, and…

  1. Self-Directed Learning to Develop Autonomy in an Online ESP Community

    ERIC Educational Resources Information Center

    Yang, Yu-Fen

    2016-01-01

    Low foreign language achievers in vocational education often have a lack of learning strategies, a tendency to feel frustrated, and unwillingness to be involved. In order to develop vocational college students' autonomy, this study integrated on-site workshops with an online learning community by means of self-directed learning English for…

  2. Congruency between Occupational Daydreams and Self Directed Search (SDS) Scores among College Students

    ERIC Educational Resources Information Center

    Miller, Mark J.; Springer, Thomas P.; Tobacyk, Jerome; Wells, Don

    2004-01-01

    In this study, the relationship of expressed occupational daydreams and scores on the Self-Directed Search (SDS) were examined. Results were consistent with Holland's theory of careers. Implications for career counselors are discussed. Students were asked to provide specific biographical data (i. e., age, gender, race) and to write down their…

  3. Interests, Aspirations, Self-Estimates, and the Self-Directed Search.

    ERIC Educational Resources Information Center

    Gottfredson, Gary D.

    2002-01-01

    Self-beliefs are not measures of ability and skill but they are correlated with interests and activities and are useful predictors of occupational choices. Holland's theory of vocational personalities provides a framework compatible with Social Cognitive Career Theory and goal theory; the Self-Directed Search is a viable means of assessing…

  4. "The Plan(ner) Is Always Changing": Self-Directed Funding for Children with Hearing Loss

    ERIC Educational Resources Information Center

    Simpson, Andrea; Stewart, Lauryn; Douglas, Jacinta

    2016-01-01

    This study investigated the experience of families with young children with hearing loss participating in a self-directed funding scheme in Australia. Eleven hearing caregivers, one male, participated in qualitative semi-structured interviews. Analysis was undertaken using a phenomenological inspired thematic analysis approach. Major themes…

  5. The Influence of Job Characteristics and Self-Directed Learning Orientation on Workplace Learning

    ERIC Educational Resources Information Center

    Raemdonck, Isabel; Gijbels, David; van Groen, Willemijn

    2014-01-01

    Given the increasing importance of learning at work, we set out to examine the factors which influence workplace learning behaviour. The study investigated the influence of the job characteristics from Karasek's Job Demand Control Support model and the personal characteristic self-directed learning orientation on workplace learning. A total…

  6. Individualized Instruction in Science, Earth-Space Project, Self-Directed Activities.

    ERIC Educational Resources Information Center

    Kuczma, R. M.

    As a supplement to Learning Activity Packages (LAP) of the earth-space project, this manual presents self-directed activities especially designed for individualized instruction. Besides an introduction to LAP characteristics, sets of instructions are given in connection with the metric system, the earth's dimensions, indirect evidence for atomic…

  7. Asking Questions during Self-Directed Inductive Learning: Effects on Learning Outcome and Learning Processes

    ERIC Educational Resources Information Center

    Wilhelm, Pascal; Beishuizen, Jos J.

    2004-01-01

    Asking learners standardized questions during performance of a self-directed inductive learning task might be a useful way to complement think aloud protocol data. However, asking questions might also scaffold the learning process and thus influence the exact processes one wants to study. In the study described in this paper two groups of learners…

  8. e-Portfolios Enhancing Students' Self-Directed Learning: A Systematic Review of Influencing Factors

    ERIC Educational Resources Information Center

    Beckers, Jorrick; Dolmans, Diana; Van Merriënboer, Jeroen

    2016-01-01

    e-Portfolios have become increasingly popular among educators as learning tools. Some research even shows that e-portfolios can be utilised to facilitate the development of skills for self-directed learning. Such skills include self-assessment of performance, formulation of learning goals, and selection of future tasks. However, it is not yet…

  9. The Effect of Self-Directed Work Teams on Work Ethic

    ERIC Educational Resources Information Center

    Petty, Gregory C.; Lim, Doo Hun; Yoon, Seung Won; Fontan, Johnny

    2008-01-01

    This study examined the work ethic of manufacturing machine operators between self-directed work teams and traditional work groups using four work ethic subscales: dependable, considerate, ambitious, and cooperative (Dawson, [1999]; Petty, [1991]). Differences in measured work ethic scores were also compared across six demographic variables: age,…

  10. The Effect of Self-Directed Work Teams on Work Ethic

    ERIC Educational Resources Information Center

    Lim, Doo Hun; Petty, Gregory; Fontan, Johnny; Yoon, Seung Won

    2008-01-01

    The purpose of this study was to compare work ethic of manufacturing machine operators between a self-directed work team and a traditional work team based on four work ethic subscales and identify differences in work ethic based on six demographic factors. The major findings from the study indicated there were significant differences in the work…

  11. An Examination of Self-Directed Learning Readiness in Executive-Level Fire Officers

    ERIC Educational Resources Information Center

    Knight, Steven G.

    2012-01-01

    The purpose of this study was to examine the self-directed learning readiness in executive fire officers in relation to the independent variables of personality type, educational attainment, and professional designation. This research utilized a quantitative design. This study utilized the Myers-Briggs Type Indicator (MBTI) and the Self-Directed…

  12. Guideposts to Self-Directed Learning. Expert Commentary on Essential Concepts.

    ERIC Educational Resources Information Center

    Confessore, Gary J., Ed.; Confessore, Sharon J., Ed.

    The 15 chapters in this book include commentaries on 12 seminal works on self-directed learning (SDL) by Houle, Knowles, Tough, Spear and Mocker, Brookfield, Caffarella and O'Donnell, and Long et al. These works were identified by a Delphi panel of 49 experts. Chapter titles and authors are as follows: "An Introduction to the Study of…

  13. Supporting Students to Self-Direct Intentional Learning Projects with Social Media

    ERIC Educational Resources Information Center

    Valjataga, Terje; Fiedler, Sebastian

    2009-01-01

    In order to be able to cope with many authentic challenges in increasingly networked and technologically mediated life we need to construct opportunities for participants in higher educational settings to practice the advancement of self-directing intentional learning projects. In addition to teaching general strategies for carrying out these…

  14. Understanding Responsibility: A Self-Directed Learning Application of the Triangle Model of Responsibility

    ERIC Educational Resources Information Center

    Kohns, Jonathan W.; Ponton, Michael K.

    2006-01-01

    Personal responsibility has long been considered an important component in self-directed learning. And yet, a theoretical understanding of personal responsibility that could lead to meaningful instrumentation has eluded the field. The present study considers the merits of the Triangle Model of Responsibility (TMR) (Schlenker, Britt, Pennington,…

  15. Interpreting Self-Directed Search Profiles: Validity of the "Rule of Eight"

    ERIC Educational Resources Information Center

    Glavin, Kevin W.; Savickas, Mark L.

    2011-01-01

    Based on the standard error of measurement, Holland (1985) suggested the "rule of eight" for determining the meaningfulness of differences between two summary scores on the Self Directed Search. The present study empirically examined the rule's validity for practice. The participants were 2397 (1497 females and 900 males) undergraduate…

  16. Serious but Fun, Self-Directed yet Social: Blogging as a Form of Lifelong Learning

    ERIC Educational Resources Information Center

    Harju, Vilhelmiina; Pehkonen, Leila; Niemi, Hannele

    2016-01-01

    The article explores the role of digital media in supporting lifelong learning. In particular, it focuses on bloggers who write their blogs voluntarily in their own free time. The aim is to examine how lifelong learning--viewed as self-directed, nonformal learning and active participation that evolves from a desire for self-actualization--occurs…

  17. Self-Directed Learning and Prostate Cancer: A Thematic Analysis of the Experiences of Twelve Patients

    ERIC Educational Resources Information Center

    Rager, Kathleen B.

    2006-01-01

    Although self-directed learning is a common response for many of the 232,090 US men who are diagnosed with prostate cancer each year, very little is known about the nature of the experience for them. Four themes emerged from interviews with 12 prostate cancer patients describing their self-education efforts in regard to their disease. A…

  18. Encouraging Self-Directed Group Learning through an E-Portfolio System

    ERIC Educational Resources Information Center

    Fukuda, Eri; Suzuki, Mitsuko; Hashimoto, Shinichi; Okazak, Hironobu

    2014-01-01

    In this study, the researchers examined how 64 university students engaged in self-directed group learning and used a self-developed e-portfolio system. A sixweek event was held where the students made entries to the e-portfolio individually each week, received feedback from advisors, studied in groups on a voluntary basis, and reflected on their…

  19. On the Performance of Self-Directed Learning within the French Continuing Vocational Training System.

    ERIC Educational Resources Information Center

    Dif, M'Hamed

    Continuing vocational training (CVT) was officially introduced and codified in France in 1971 to promote individuals' employability, career development, and job flexibility. Self-directed learning was initially considered among the most important instruments for its implementation in addition to employer-directed CVT. Despite increased and…

  20. Personalisation of Adult Social Care: Self-Directed Support and the Choice and Control Agenda

    ERIC Educational Resources Information Center

    Kendall, Sophie; Cameron, Ailsa

    2014-01-01

    In 2007, "self-directed support" was introduced in adult social care in England to establish choice and control--in the assessment process itself and over service provision--for "all" service users. The personalisation agenda is underpinned by a range of ideologies, particularly a civil rights empowerment approach and…

  1. Verification of Accurate Technical Insight: A Prerequisite for Self-Directed Surgical Training

    ERIC Educational Resources Information Center

    Hu, Yinin; Kim, Helen; Mahmutovic, Adela; Choi, Joanna; Le, Ivy; Rasmussen, Sara

    2015-01-01

    Simulation-based surgical skills training during preclinical education is a persistent challenge due to time constraints of trainees and instructors alike. Self-directed practice is resource-efficient and flexible; however, insight into technical proficiency among trainees is often lacking. The purpose of this study is to prospectively assess the…

  2. The Effect of Formative Testing and Self-Directed Learning on Mathematics Learning Outcomes

    ERIC Educational Resources Information Center

    Sumantri, Mohamad Syarif; Satriani, Retni

    2016-01-01

    The purpose of this research was to determine the effect of formative testing and self-directed learning on mathematics learning outcomes. The research was conducted at an elementary school in central Jakarta during the 2014/2015 school year. Seventy-two fourth-grade students who were selected using random sampling participated in this study. Data…

  3. Enhancing Self-Directed Learning through a Content Quiz Group Learning Assignment

    ERIC Educational Resources Information Center

    Warburton, Natalie; Volet, Simone

    2013-01-01

    This article presents the findings of an empirical study that examined the learning value of a novel group assessment activity aimed at promoting first-year students' development of basic self-directed learning skills required for university study. A content quiz group learning assignment was designed to enhance students' capacity to ask…

  4. Fostering Postgraduate Student Engagement: Online Resources Supporting Self-Directed Learning in a Diverse Cohort

    ERIC Educational Resources Information Center

    Mello, Luciane V.

    2016-01-01

    The research question for this study was: "Can the provision of online resources help to engage and motivate students to become self-directed learners?" This study presents the results of an action research project to answer this question for a postgraduate module at a research-intensive university in the United Kingdom. The analysis of…

  5. New to Facilitating Self-Directed Learning: The Changing Perceptions of Teachers

    ERIC Educational Resources Information Center

    Lai, Conttia; Gardner, David; Law, Ellie

    2013-01-01

    This paper reports on a study examining the attitudes and perceptions of a group of in-service teachers who are new or relatively new to facilitating self-directed learning (SDL) before and after they taught a course with an integrated SDL component. The study also investigates the impact on those teachers' attitudes of an orientation package…

  6. Edmodo Use to Develop Saudi EFL Students' Self-Directed Learning

    ERIC Educational Resources Information Center

    Khodary, Manal Mohamed

    2017-01-01

    This study aimed at exploring the effect of Edmodo use on developing Saudi English as a Foreign Language (EFL) students' Self-Directed Learning (SDL). It employed a quasi-experimental design that included a one group design. The participants (n = 45) were all fifth level students at Languages and Translation Department, Arar Faculty of Education…

  7. Lifestyle and Learning Habits of Croatian College Students: Self-Directed Learners

    ERIC Educational Resources Information Center

    Roberson, Donald N., Jr.

    2012-01-01

    The purpose of this study was to understand more about the activities and learning habits of Croatian College students through the lens of self-directed learning. This research took place in the National Library of Zagreb University over a two year period. Researchers would ask available students for their opinion on a questionnaire; approximately…

  8. Assessing readiness for self-directed learning within a non-traditional nursing cohort.

    PubMed

    Phillips, Brian N; Turnbull, Beverley J; He, Flora X

    2015-03-01

    Increasing deregulation of the Australian tertiary system has led to changes in entry behaviours anticipated in non-traditional student cohorts. Many nursing students are returning to formal studies later in their lives seeking a career change. Accessibility and flexible study paths make external study increasingly attractive. However external studies require a level of commitment and willingness to develop self-direction and a capacity for resilience. This study sought to elicit the level of self-directed learning readiness (SDLR) among undergraduate nursing students currently enrolled at a bachelor level, and to elicit what differences existed in the levels of SDLR in relation to age, gender, academic year, and previous qualifications. An online survey questionnaire was utilised based on the Self-directed Learning Readiness Scale for Nursing Education. In contrast to earlier work, the participant profile in this study was predominantly non-traditional and captured participants from all three years of the nursing programme. Results found no significant age or gender differences. First year students demonstrated lower levels of self-directed learning readiness. However, unexpected results were demonstrated in the survey subscales in relation to previous qualifications. Participants who already held post-graduate qualifications showed lower scores for Self-Management than those who held diploma qualifications, while students who already held a bachelor's degree had the highest scores in Desire for Learning. The study findings suggest that universities should not assume that SDL capability is dependent on mature age or length of exposure to tertiary study.

  9. Self-Directed Learning and Academic Achievement in Secondary Online Students

    ERIC Educational Resources Information Center

    Carson, Elaine Hendricks

    2012-01-01

    This study examined attributes of self-directed learning (SDL) in students, grades 8 through 12, taking online courses through a state-wide online program in the Southeastern United States. The study investigated whether distinct latent classes of SDL exist; whether there was a significant difference in SDL according to gender, ethnicity, and…

  10. An Investigation of the Construct Validity of the Personality Trait of Self-Directed Learning

    ERIC Educational Resources Information Center

    Lounsbury, John W.; Levy, Levy J.; Park, Soo-Hee; Gibson, Lucy W.; Smith, Ryan

    2009-01-01

    Based on samples of 398 middle school students, 568 high school students, and 1159 college students, self-directed learning was found to be related to cumulative grade-point-average at all levels as well as to Big Five personality traits (Openness, Conscientiousness, Emotional Stability, and Extraversion), narrow personality traits (Optimism,…

  11. Development and Initial Validation of the Self-Directed Learning Inventory with Korean College Students

    ERIC Educational Resources Information Center

    Suh, Han Na; Wang, Kenneth T.; Arterberry, Brooke J.

    2015-01-01

    This article describes the development and psychometric evaluation of the Self-Directed Learning Inventory (SDLI) tailored to Korean college students, based on study evidences of differences in learning behavior across culture and educational level. With a sample of 605 female college students in Korea, exploratory factor analysis (EFA) results…

  12. Twin Similarities in Holland Types as Shown by Scores on the Self-Directed Search

    ERIC Educational Resources Information Center

    Chauvin, Ida; McDaniel, Janelle R.; Miller, Mark J.; King, James M.; Eddlemon, Ondie L. M.

    2012-01-01

    This study examined the degree of similarity between scores on the Self-Directed Search from one set of identical twins. Predictably, a high congruence score was found. Results from a biographical sheet are discussed as well as implications of the results for career counselors.

  13. The Power of Self-Directed Journals: Being a Temporary "Other" for Learning to Teach

    ERIC Educational Resources Information Center

    Matsumoto, Yumi

    2016-01-01

    This case study investigates how an ESL teacher's activity of self-directed journal writing can facilitate learning and function as a mediational tool for teacher professional development. The participant for this study is a native English speaker who taught an ESL freshman writing course in an American university. Since he had little time to…

  14. Relinquishing Power in the Classroom: A Case Study on Self-Directed Teams in the Classroom.

    ERIC Educational Resources Information Center

    Driskill, Gerald W.; Polansky, Brian

    The shift toward self-directed work teams in organizations is well documented and is further underscored by models that give teamwork an integral role in accomplishing organizational goals. The traditional classroom fails to mirror such shifts when it emphasizes instructor control and decision making with a premium placed on clarity in direction,…

  15. Individualized Instruction in Science, Time-Space-Matter, Self-Directed Activities.

    ERIC Educational Resources Information Center

    Kuczma, R. M.

    As a supplement to Learning Activity Packages (LAP) on the time-space-matter subject, details are presented for self-directed activities. Major descriptions are given on the background of LAP characteristics, metric system, profile graph construction, spectroscope operation, radiant energy measurement, sunspot effects, density determination,…

  16. Psychometric Properties of the Chinese Self-Directed Search (1994 Edition)

    ERIC Educational Resources Information Center

    Yang, Weiwei; Lance, Charles E.; Hui, Harry C.

    2006-01-01

    In this study, we (a) examined the measurement equivalence/invariance (ME/I) of the Chinese Self-Directed Search (SDS; 1994 edition) across gender and geographic regions (Mainland China vs. Hong Kong); (b) assessed the construct validity of the Chinese SDS using Widaman's (1985, 1992) MTMM framework; and (c) determined whether vocational interests…

  17. A Journey with Chronic Pain: Self-Directed Learning as Survival

    ERIC Educational Resources Information Center

    King, Kathleen P.

    2014-01-01

    Over the past 20 years in the USA, increased insurance control of healthcare decisions, litigation and regulations, have contributed to a dramatic shift in the doctor-patient relationship and respective responsibilities. This paper presents an autoethnographic study of the self-directed learning (SDL) strategies and patterns used by an individual…

  18. Promoting Self-Directed Learning in a Learning Organization: Tools and Practices

    ERIC Educational Resources Information Center

    Rana, Sowath; Ardichvili, Alexandre; Polesello, Daiane

    2016-01-01

    Purpose: The purpose of this paper is to examine a set of practices that can help promote self-directed learning (SDL) in congruence with the goals of developing and maintaining a learning organization. Design/methodology/approach Findings from this study were derived from an extensive review of the SDL and the learning organization literature, as…

  19. A Thematic Analysis of the Self-Directed Learning Experiences of 13 Breast Cancer Patients

    ERIC Educational Resources Information Center

    Rager, Kathleen

    2004-01-01

    Although self-directed learning is a common response for many of the 183000 American women who are diagnosed with breast cancer each year, very little is known about the nature of the experience for them. Four themes emerged from interviews with 13 breast cancer patients describing their self-education efforts in regard to their disease. A…

  20. Using Self-Directed Video Prompting to Teach Students with Intellectual Disabilities

    ERIC Educational Resources Information Center

    Cannella-Malone, Helen I.; Brooks, David G.; Tullis, Christopher A.

    2013-01-01

    This study examined the effects of self-directed video prompting presented via an iPod Touch on teaching four adolescents with moderate-to-severe intellectual and developmental disabilities two daily living tasks. Students were taught to wash a table using instructor-delivered video prompts. After reaching 80% correct for at least three…

  1. Evaluation of the Self-Directed Personal Services Program Operated through Enable.

    ERIC Educational Resources Information Center

    Walker, Pam; And Others

    This report evaluates a self-directed personal service (SDPS) program operated through the larger Enable Program for people with disabilities in Onondaga County, New York. First, it contrasts characteristics of traditional personal assistance services (such as low pay, agency-determined, limited types/levels of support, and program management…

  2. Development of a Supported Self-Directed Learning Approach for Anatomy Education

    ERIC Educational Resources Information Center

    Findlater, Gordon S.; Kristmundsdottir, Fanney; Parson, Simon H.; Gillingwater, Thomas H.

    2012-01-01

    The ability to deliver sufficient core anatomical knowledge and understanding to medical students with limited time and resources remains a major challenge for anatomy educators. Here, we report the results of switching from a primarily didactic method of teaching to supported self-directed learning for students studying anatomy as part of…

  3. Evaluating the Effects of Competency-Based Web Learning on Self-Directed Learning Aptitudes

    ERIC Educational Resources Information Center

    Chang, Chi-Cheng

    2007-01-01

    The main aim of the study is to evaluate the impact of the competency-based web learning material (CBWLM) on the self-directed learning aptitude (SDLA) of college students. Specifically, it seeks to investigate, statistically, the changes in SDLAs at different stages of competency-based web learning (CBWL) over an eight-week period. The sample of…

  4. Self-Directed Learning: College Students' Technology Preparedness Change in the Last 10 Years

    ERIC Educational Resources Information Center

    Caravello, Michael J.; Jiménez, Joel R.; Kahl, Lois J.; Brachio, Brian; Morote, Elsa-Sofia

    2015-01-01

    This study compares a sample of approximately 44 first year college students in 2005 and 2015 on Long Island, New York, in their technology preparedness and self-directed instruction. The researchers used a survey instrument including demographic information focused upon students' preparation for classroom technology in high school and college.…

  5. The Self-Directed Learning Experience of Mothers Whose Child Has Had a Paediatric Stroke

    ERIC Educational Resources Information Center

    Grover, Kenda S.

    2014-01-01

    This study employed qualitative research methodology to explore the experiences of mothers who self-directed their learning following their child's stroke diagnosis. Paediatric stroke, although rare, is among the top 10 causes of death in children in the USA, but information about the cause, treatment and long-term impact are difficult to…

  6. Developing and Piloting an App for Managing Self-Directed Language Learning: An Action Research Approach

    ERIC Educational Resources Information Center

    Lammons, Elizabeth; Momata, Yuko; Mynard, Jo; Noguchi, Junko; Watkins, Satoko

    2015-01-01

    Paper-based tools such as self-evaluation activities, learning plans, reflective journals and learning logs are commonplace for managing Self-Directed Language Learning (SDLL). Such tools not only promote ownership over learning and provide a sense of achievement to learners, but they also promote reflection and raise awareness of learning…

  7. Designing E-Portfolio with ARCS Motivational Design Strategies to Enhance Self-Directed Learning

    ERIC Educational Resources Information Center

    Mohamad, Syamsul Nor Azlan; Embi, Mohamed Amin; Nordin, Norazah Mohd

    2016-01-01

    This paper presents the instructional design effect on motivation towards the implementation of e-Portfolio with ARCS Motivational design strategies to enhance self-directed learning. The purpose of the study was to examine the learners' motivation level after the implementation of e-Portfolio. Initially, this paper was conducted to study a total…

  8. Stages of Learning during a Self-Directed Stress Management Experience

    ERIC Educational Resources Information Center

    Larson, Karl L.

    2015-01-01

    Purpose: The purpose of the study was to document the stages of learning reflected through student journaling during a self-directed experience in stress management, and the relationship of those stages to a historical model. Methods: College students participating in a full-semester course in stress management theory were required to select a…

  9. The Relationship between Self-Directed Learning Readiness and Student Retention in Nursing Education

    ERIC Educational Resources Information Center

    Larmon, Brandy H.

    2015-01-01

    Retention in higher education, especially nursing education, is a concern for nurse educators. Due to the needs of nurse graduates and practicing nurses, the characteristic of self-directed learning in students is often an educational goal of a rigorous nursing curriculum. Program retention is often impacted by such demands. This study, based upon…

  10. Design and Evaluation of a Development Portfolio: How to Improve Students' Self-Directed Learning Skills

    ERIC Educational Resources Information Center

    Kicken, Wendy; Brand-Gruwel, Saskia; van Merrienboer, Jeroen; Slot, Wim

    2009-01-01

    In on-demand education, students often experience problems with directing their own learning processes. A Structured Task Evaluation and Planning Portfolio (STEPP) was designed to help students develop 3 basic self-directed learning skills: Assessing the quality of own performance, formulating learning needs, and selecting future learning tasks. A…

  11. Determining a Difference in Self-Directed Learning Readiness Using the Survey of Adult Learning Traits

    ERIC Educational Resources Information Center

    Ezell, Diana

    2013-01-01

    The purpose of this study was to measure the self-directed learning of educators and explore the differences between and among the variables of age, level of education, position, school district ratings, levels of poverty and affluence, and gender. The Survey of Adult Learning Traits (SALT) authored by Hogg was used as the instrument to measure…

  12. Self-Directed Learning: Adult Learners' Perceptions and Their Study Materials.

    ERIC Educational Resources Information Center

    Greyling, E. S. G.; Geyser, H. C.; Fourie, C. M.

    2002-01-01

    Triggered by the poor performance of historically-disadvantaged students in a South African distance education course, examined students' perceptions of their self-directed learning (SDL). Also examined the SDL support contained in their study materials. Found that the students generally lacked readiness for SDL, suggesting several changes needed…

  13. Reflective Teaching as Self-Directed Professional Development: Building Practical or Work-Related Knowledge

    ERIC Educational Resources Information Center

    Minott, Mark A.

    2010-01-01

    The broad purpose of this self-study is two-fold: first, to aid in redressing the lack of attention given to the professional development of teacher educators; and second, to forward the idea that teaching reflectively is not only an excellent framework through which self-directed professional development can be enacted, but it is also an…

  14. The Influence of Item Response Indecision on the Self-Directed Search

    ERIC Educational Resources Information Center

    Sampson, James P., Jr.; Shy, Jonathan D.; Hartley, Sarah Lucas; Reardon, Robert C.; Peterson, Gary W.

    2009-01-01

    Students (N = 247) responded to Self-Directed Search (SDS) per the standard response format and were also instructed to record a question mark (?) for items about which they were uncertain (item response indecision [IRI]). The initial responses of the 114 participants with a (?) were then reversed and a second SDS summary code was obtained and…

  15. Effects of the Self-Directed Search on High School Students

    ERIC Educational Resources Information Center

    Zener, Thelma Baldwin; Schnuelle, Leslie

    1976-01-01

    This study compares effects on high school students (N=959) of the Self Directed Search (SDS), the Vocational Preference Inventory (VPI), and no treatment. Students taking the SDS or the VPI evaluated the instruments, felt more satisfied with current occupational choices, and considered more occupational alternatives. Differences between the…

  16. Self-Directed Learning Needs, Patterns, and Outcomes among General Surgeons

    ERIC Educational Resources Information Center

    Gagliardi, Anna R.; Wright, Frances C.; Victor, J. Charles; Brouwers, Melissa C.; Silver, Ivan L.

    2009-01-01

    Introduction: To explore the relationship between self-directed learning (SDL) needs, patterns, barriers, and outcomes among nonacademic general surgeons. Methods: Participants dictated details of SDL episodes associated with cancer patient management from October 2007 to March 2008. Transcripts were coded thematically. Frequencies were calculated…

  17. Predictors of Self-Directed Learning for Low-Qualified Employees: A Multi-Level Analysis

    ERIC Educational Resources Information Center

    Raemdonck, Isabel; van der Leeden, Rien; Valcke, Martin; Segers, Mien; Thijssen, Jo

    2012-01-01

    Purpose: This study aims to examine which variables at the level of the individual employee and at the company level are predictors of self-directed learning in low-qualified employees. Methodology: Results were obtained from a sample of 408 low-qualified employees from 35 different companies. The companies were selected from the energy sector,…

  18. The Design of a Web-Based Course for Self-Directed Learning

    ERIC Educational Resources Information Center

    Liu, Mingzhuo

    2009-01-01

    Purpose: The purpose of this paper is to explore how to design a web-based course in the context of China for self-directed learning from four perspectives--i.e. pedagogical, psychological, social and technological--and also to summarize the design principles for the web-based course. Design/methodology/approach: The paper reviews literature…

  19. An Examination of the Self-Directed Learning Practices of ESL Adult Language Learners

    ERIC Educational Resources Information Center

    Grover, Kendra S.; Miller, Michael T.; Swearingen, Brent; Wood, Nancy

    2014-01-01

    Self-directed learning is one of the preeminent theories in the field of adult education. This study explored how English as a Second Language learners directed their own learning outside of the formal classroom through the use of practices that potentially advance their English language proficiency. Results from a survey of over 400 ESL students…

  20. Self-Directed English Language Learning through Watching English Television Drama in China

    ERIC Educational Resources Information Center

    Wang, Danping

    2012-01-01

    This paper presents a case study of a group of Chinese ESL learners in China, who study English by immersing themselves regularly and rigorously in English television drama. A self-directed learning pedagogy has been developed and discussed, which seems to have signposted an effective and economic way for ESL learners to improve linguistic,…

  1. A Phenomenological Exploration of Self-Directed Learning among Successful Minority Entrepreneurs

    ERIC Educational Resources Information Center

    Alexander, Nancy Hope

    2013-01-01

    This transcendental, phenomenological study explored the Self-directed learning (SDL) of 10 successful minority entrepreneurs. Two SDL theories serve as lenses for the study, Spear and Mocker's (1984) Organizing Circumstance and Brockett and Heimstra's (1991) Personal Responsibility Orientation model. Five themes emerged from the data:…

  2. Effects of Self-Regulatory Instructional Aids on Self-Directed Study

    ERIC Educational Resources Information Center

    Bednall, Timothy C.; Kehoe, E. James

    2011-01-01

    This study examined the effectiveness of providing instructional support for the self-regulation of a self-directed homework assignment. Across four parallel experiments, university students completed an online module on critical thinking. In Experiment 1, participants who were prompted on a broad spectrum of study strategies showed superior…

  3. The Relative Influence of Different Domains of Social Connectedness on Self-Directed Violence in Adolescence

    ERIC Educational Resources Information Center

    Kaminski, Jennifer W.; Puddy, Richard W.; Hall, Diane M.; Cashman, Sandra Y.; Crosby, Alexander E.; Ortega, LaVonne A. G.

    2010-01-01

    Previous research has linked greater social connectedness with a lowered risk of self-directed violence among adolescents. However, few studies have analyzed the comparative strength of different domains of connectedness (e.g., family, peers and school) to determine where limited resources might best be focused. Data to address that gap were taken…

  4. Developing Self-Directed Executive Functioning: Recent Findings and Future Directions

    ERIC Educational Resources Information Center

    Barker, Jane E.; Munakata, Yuko

    2015-01-01

    How do children become increasingly self-directed across development, achieving their goals without help from others? How might such developments be impacted by societal changes in how children spend their time? Children's abilities to achieve their goals are supported by developing executive functions (EFs), cognitive processes that predict…

  5. Dynamic Training Elements in a Circuit Theory Course to Implement a Self-Directed Learning Process

    ERIC Educational Resources Information Center

    Krouk, B. I.; Zhuravleva, O. B.

    2009-01-01

    This paper reports on the implementation of a self-directed learning process in a circuit theory course, incorporating dynamic training elements which were designed on the basis of a cybernetic model of cognitive process management. These elements are centrally linked in a dynamic learning frame, created on the monitor screen, which displays the…

  6. How Older Rural Adults Utilize Self-Directed Learning in Late Life Adjustments

    ERIC Educational Resources Information Center

    Roberson, Donald N., Jr.

    2003-01-01

    The increasing numbers and influence of older adults is causing many segments of western society to re-evaluate the concept of old age. Medical advances and personal lifestyles have resulted in older adults living longer and healthier lives. As one ages, adjustments in work, family, and health must be made. Self-directed learning (SDL) is one way…

  7. Promoting Students' Self-Directed Learning Ability through Teaching Mathematics for Social Justice

    ERIC Educational Resources Information Center

    Voss, Richard; Rickards, Tony

    2016-01-01

    Mathematics is a subject which is often taught using abstract methods and processes. These methods by their very nature may for students alienate the relationship between Mathematics and real life situations. Further, these abstract methods and processes may disenfranchise students from becoming self-directed learners of Mathematics. A solution to…

  8. Using Two Different Self-Directed Search (SDS) Interpretive Materials: Implications for Career Assessment

    ERIC Educational Resources Information Center

    Dozier, V. Casey; Sampson, James P.; Reardon, Robert C.

    2013-01-01

    John Holland's Self-Directed Search (SDS) is a career assessment that consists of several booklets designed to be self-scored and self-administered. It simulates what a practitioner and an individual might do together in a career counseling session (e.g., review preferred activities and occupations; review competencies, abilities and possible…

  9. Transition from one- to two-dimensional development facilitates maintenance of multicellularity

    PubMed Central

    Manjarrez-Casas, Alejandra M.; Bagheri, Homayoun C.

    2016-01-01

    Filamentous organisms represent an example where incomplete separation after cell division underlies the development of multicellular formations. With a view to understanding the evolution of more complex multicellular structures, we explore the transition of multicellular growth from one to two dimensions. We develop a computational model to simulate multicellular development in populations where cells exhibit density-dependent division and death rates. In both the one- and two-dimensional contexts, multicellular formations go through a developmental cycle of growth and subsequent decay. However, the model shows that a transition to a higher dimension increases the size of multicellular formations and facilitates the maintenance of large cell clusters for significantly longer periods of time. We further show that the turnover rate for cell division and death scales with the number of iterations required to reach the stationary multicellular size at equilibrium. Although size and life cycles of multicellular organisms are affected by other environmental and genetic factors, the model presented here evaluates the extent to which the transition of multicellular growth from one to two dimensions contributes to the maintenance of multicellular structures during development. PMID:27703714

  10. Less-structured time in children's daily lives predicts self-directed executive functioning.

    PubMed

    Barker, Jane E; Semenov, Andrei D; Michaelson, Laura; Provan, Lindsay S; Snyder, Hannah R; Munakata, Yuko

    2014-01-01

    Executive functions (EFs) in childhood predict important life outcomes. Thus, there is great interest in attempts to improve EFs early in life. Many interventions are led by trained adults, including structured training activities in the lab, and less-structured activities implemented in schools. Such programs have yielded gains in children's externally-driven executive functioning, where they are instructed on what goal-directed actions to carry out and when. However, it is less clear how children's experiences relate to their development of self-directed executive functioning, where they must determine on their own what goal-directed actions to carry out and when. We hypothesized that time spent in less-structured activities would give children opportunities to practice self-directed executive functioning, and lead to benefits. To investigate this possibility, we collected information from parents about their 6-7 year-old children's daily, annual, and typical schedules. We categorized children's activities as "structured" or "less-structured" based on categorization schemes from prior studies on child leisure time use. We assessed children's self-directed executive functioning using a well-established verbal fluency task, in which children generate members of a category and can decide on their own when to switch from one subcategory to another. The more time that children spent in less-structured activities, the better their self-directed executive functioning. The opposite was true of structured activities, which predicted poorer self-directed executive functioning. These relationships were robust (holding across increasingly strict classifications of structured and less-structured time) and specific (time use did not predict externally-driven executive functioning). We discuss implications, caveats, and ways in which potential interpretations can be distinguished in future work, to advance an understanding of this fundamental aspect of growing up.

  11. Less-structured time in children's daily lives predicts self-directed executive functioning

    PubMed Central

    Barker, Jane E.; Semenov, Andrei D.; Michaelson, Laura; Provan, Lindsay S.; Snyder, Hannah R.; Munakata, Yuko

    2014-01-01

    Executive functions (EFs) in childhood predict important life outcomes. Thus, there is great interest in attempts to improve EFs early in life. Many interventions are led by trained adults, including structured training activities in the lab, and less-structured activities implemented in schools. Such programs have yielded gains in children's externally-driven executive functioning, where they are instructed on what goal-directed actions to carry out and when. However, it is less clear how children's experiences relate to their development of self-directed executive functioning, where they must determine on their own what goal-directed actions to carry out and when. We hypothesized that time spent in less-structured activities would give children opportunities to practice self-directed executive functioning, and lead to benefits. To investigate this possibility, we collected information from parents about their 6–7 year-old children's daily, annual, and typical schedules. We categorized children's activities as “structured” or “less-structured” based on categorization schemes from prior studies on child leisure time use. We assessed children's self-directed executive functioning using a well-established verbal fluency task, in which children generate members of a category and can decide on their own when to switch from one subcategory to another. The more time that children spent in less-structured activities, the better their self-directed executive functioning. The opposite was true of structured activities, which predicted poorer self-directed executive functioning. These relationships were robust (holding across increasingly strict classifications of structured and less-structured time) and specific (time use did not predict externally-driven executive functioning). We discuss implications, caveats, and ways in which potential interpretations can be distinguished in future work, to advance an understanding of this fundamental aspect of growing up

  12. Exploring first-year undergraduate medical students' self-directed learning readiness to physiology.

    PubMed

    Abraham, Reem Rachel; Fisher, Murray; Kamath, Asha; Izzati, T Aizan; Nabila, Saidatul; Atikah, Nik Nur

    2011-12-01

    Medical students are expected to possess self-directed learning skills to pursue lifelong learning. Previous studies have reported that the readiness for self-directed learning depends on personal attributes as well as the curriculum followed in institutions. Melaka Manipal Medical College of Manipal University (Karnataka, India) offers a Bachelor of Medicine and Bachelor of Surgery (MBBS) twinning program that is of 5 yr in duration. Keeping in mind the amount of time that the curriculum has devoted for self-directed learning, we explored the self-directed learning readiness of first-year MBBS students (n = 130) using a self-directed learning readiness scale (SDLRS) and explored the correlation between SDLRS scores of high achievers, medium achievers, and low achievers with their academic performance in physiology examinations. Students were requested to respond to each item of the SDLRS on a Likert scale. Median scores of the three scales of the SDLRS were compared across the three groups of students using a Kruskall-Wallis test. SDLRS scores of the students (n = 130) were correlated with their marks in theory papers of first, second, and third block-end examinations using Spearmann's correlation coefficient. The mean item score for desire for learning was found to be higher followed by self-control and self-management. Data analyses showed significantly high (P < 0.03) median scores for self-control for high achievers compared with medium and low achievers. Between the groups, high achievers had a higher score for all the three scales of the SDLRS followed by low and medium achievers. SDLRS scores and academic performance of the three groups of students were found to exhibit a weak correlation. This study threw light on the fact that despite having a high desire for learning and ability of self-control, students need to be supported in their self-management skills.

  13. Force communication in multicellular tissues addressed by laser nanosurgery.

    PubMed

    Colombelli, Julien; Solon, Jérôme

    2013-04-01

    Cell contractility is a prominent mechanism driving multicellular tissue development and remodeling. Forces originated by the actomyosin cytoskeleton not only act within the cell body but can also propagate many layers away from the contraction source and grant tissues the ability to organize collectively and to achieve robust remodeling through development. Tissue tension is being thoroughly investigated in model organisms and increasing evidence is revealing the major role played by the communication, dynamics and propagation of cell-to-cell physical forces in multicellular remodeling. Recently, pulsed-laser-based surgery has fostered in vivo experimental studies to investigate intracellular and supracellular forces in action. The technique offers a unique method to perturb mechanical equilibrium in a subpopulation of cells or in a single cell, while the overall tissue remains intact. In particular, improved ablation precision with short laser pulses and the combination of this technique with biophysical models now allow an in-depth understanding of the role of cellular mechanics in tissue morphogenesis. We first characterize laser ablation modes available to perform intracellular, cellular, or multi-cellular ablation via the example of the model monolayer tissue of the amnioserosa of Drosophila by relating subnanosecond laser pulse energy to ablation efficiency and the probability of cavitation bubble formation. We then review recent laser nanosurgery experiments that have been performed in cultured cells and that tackle actomyosin mechanics and provide molecular insights into force-sensing mechanisms. We finally review studies showing the central role of laser ablation in revealing the nature and orientation of forces involved in intracellular contractility and force mechanosensing in tissue development, e.g., axis elongation, branching morphogenesis, or tissue invagination. We discuss the perspectives offered by the technique in force-based cell

  14. Waltzing Volvox/: Orbiting Bound States of Flagellated Multicellular Algae

    NASA Astrophysics Data System (ADS)

    Drescher, K.; Leptos, K.; Pedley, T. J.; Goldstein, R. E.; Ishikawa, T.

    2008-11-01

    The spherical colonial alga Volvox swims by means of flagella on thousands of surface somatic cells. This geometry and its large size makes it a model organism for the fluid dynamics of multicellularity. Remarkably, when two nearby colonies swim close to a solid surface, they are attracted together and can form a stable bound state in which they continuously waltz around each other. A surface-mediated hydrodynamic attraction between colonies combined with the rotational motion of bottom-heavy Volvox are shown to explain the stability and dynamics of the bound state. This phenomenon is suggested to underlie observed clustering of colonies at surfaces.

  15. Complex Polarity: Building Multicellular Tissues Through Apical Membrane Traffic.

    PubMed

    Román-Fernández, Alvaro; Bryant, David M

    2016-12-01

    The formation of distinct subdomains of the cell surface is crucial for multicellular organism development. The most striking example of this is apical-basal polarization. What is much less appreciated is that underpinning an asymmetric cell surface is an equally dramatic intracellular endosome rearrangement. Here, we review the interplay between classical cell polarity proteins and membrane trafficking pathways, and discuss how this marriage gives rise to cell polarization. We focus on those mechanisms that regulate apical polarization, as this is providing a number of insights into how membrane traffic and polarity are regulated at the tissue level.

  16. Corelation between Complexity and Stability in Multicellular Organisms

    NASA Astrophysics Data System (ADS)

    Werman, Steven D.; Qaddour, Jihad; Deyoung, Gary; Misra, Prasanta K.

    1997-03-01

    We present a model to study the corelation between the complexity and stability of unicellular and multicellular organisms. We state the postulates made by us and define the thermodynamic functions and other parameters used to formulate the problem. We have also used several theorems based on reasonable assumptions to analyze the functional interactions which are non-symmetric, non-local and non-instantaneous. The mathematical model developed by using these hypotheses is explained in detail and a set of non-linear equations for each type of organism is presented. We present the results obtained by us by solving these equations.

  17. Cancer across the tree of life: cooperation and cheating in multicellularity

    PubMed Central

    Aktipis, C. Athena; Boddy, Amy M.; Jansen, Gunther; Hibner, Urszula; Hochberg, Michael E.; Maley, Carlo C.; Wilkinson, Gerald S.

    2015-01-01

    Multicellularity is characterized by cooperation among cells for the development, maintenance and reproduction of the multicellular organism. Cancer can be viewed as cheating within this cooperative multicellular system. Complex multicellularity, and the cooperation underlying it, has evolved independently multiple times. We review the existing literature on cancer and cancer-like phenomena across life, not only focusing on complex multicellularity but also reviewing cancer-like phenomena across the tree of life more broadly. We find that cancer is characterized by a breakdown of the central features of cooperation that characterize multicellularity, including cheating in proliferation inhibition, cell death, division of labour, resource allocation and extracellular environment maintenance (which we term the five foundations of multicellularity). Cheating on division of labour, exhibited by a lack of differentiation and disorganized cell masses, has been observed in all forms of multicellularity. This suggests that deregulation of differentiation is a fundamental and universal aspect of carcinogenesis that may be underappreciated in cancer biology. Understanding cancer as a breakdown of multicellular cooperation provides novel insights into cancer hallmarks and suggests a set of assays and biomarkers that can be applied across species and characterize the fundamental requirements for generating a cancer. PMID:26056363

  18. Innovation and constraint leading to complex multicellularity in the Ascomycota

    PubMed Central

    Nguyen, Tu Anh; Cissé, Ousmane H.; Yun Wong, Jie; Zheng, Peng; Hewitt, David; Nowrousian, Minou; Stajich, Jason E.; Jedd, Gregory

    2017-01-01

    The advent of complex multicellularity (CM) was a pivotal event in the evolution of animals, plants and fungi. In the fungal Ascomycota, CM is based on hyphal filaments and arose in the Pezizomycotina. The genus Neolecta defines an enigma: phylogenetically placed in a related group containing mostly yeasts, Neolecta nevertheless possesses Pezizomycotina-like CM. Here we sequence the Neolecta irregularis genome and identify CM-associated functions by searching for genes conserved in Neolecta and the Pezizomycotina, which are absent or divergent in budding or fission yeasts. This group of 1,050 genes is enriched for functions related to diverse endomembrane systems and their organization. Remarkably, most show evidence for divergence in both yeasts. Using functional genomics, we identify new genes involved in fungal complexification. Together, these data show that rudimentary multicellularity is deeply rooted in the Ascomycota. Extensive parallel gene divergence during simplification and constraint leading to CM suggest a deterministic process where shared modes of cellular organization select for similarly configured organelle- and transport-related machineries. PMID:28176784

  19. Transport by Collective Flagellar Beating Facilitates Evolutionary Transitions to Multicellularity

    NASA Astrophysics Data System (ADS)

    Short, Martin; Powers, Thomas

    2005-11-01

    A central problem underlying the evolution from single cells to multicellular organisms is the relationship between metabolic requirements and environmental metabolite exchange with increasing size. For organisms that form spherical colonies such as the volvocalean green algae, there is a bottleneck if diffusion alone governs nutrient uptake as they increase in size, for the diffusive flux is linear in the radius while the requirements of surface somatic cells grow quadratically. Using Volvox as a model organism, we examine experimentally and theoretically the role that advection of fluid by surface flagella plays in enhancing nutrient uptake. We show that the fluid flow driven by the coordinated beating of those flagella produces a boundary layer in the concentration of a diffusing solute which renders the metabolite exchange rate quadratic in the colony radius. This bypasses the diffusive bottleneck, facilitating evolutionary transitions to multicellularity which may be driven by other environmental factors. These results suggest that flagella may have evolved not only for motility, but also to enhance metabolite exchange.

  20. Innovation and constraint leading to complex multicellularity in the Ascomycota.

    PubMed

    Nguyen, Tu Anh; Cissé, Ousmane H; Yun Wong, Jie; Zheng, Peng; Hewitt, David; Nowrousian, Minou; Stajich, Jason E; Jedd, Gregory

    2017-02-08

    The advent of complex multicellularity (CM) was a pivotal event in the evolution of animals, plants and fungi. In the fungal Ascomycota, CM is based on hyphal filaments and arose in the Pezizomycotina. The genus Neolecta defines an enigma: phylogenetically placed in a related group containing mostly yeasts, Neolecta nevertheless possesses Pezizomycotina-like CM. Here we sequence the Neolecta irregularis genome and identify CM-associated functions by searching for genes conserved in Neolecta and the Pezizomycotina, which are absent or divergent in budding or fission yeasts. This group of 1,050 genes is enriched for functions related to diverse endomembrane systems and their organization. Remarkably, most show evidence for divergence in both yeasts. Using functional genomics, we identify new genes involved in fungal complexification. Together, these data show that rudimentary multicellularity is deeply rooted in the Ascomycota. Extensive parallel gene divergence during simplification and constraint leading to CM suggest a deterministic process where shared modes of cellular organization select for similarly configured organelle- and transport-related machineries.

  1. Modeling of Transmembrane Potential in Realistic Multicellular Structures before Electroporation.

    PubMed

    Murovec, Tomo; Sweeney, Daniel C; Latouche, Eduardo; Davalos, Rafael V; Brosseau, Christian

    2016-11-15

    Many approaches for studying the transmembrane potential (TMP) induced during the treatment of biological cells with pulsed electric fields have been reported. From the simple analytical models to more complex numerical models requiring significant computational resources, a gamut of methods have been used to recapitulate multicellular environments in silico. Cells have been modeled as simple shapes in two dimensions as well as more complex geometries attempting to replicate realistic cell shapes. In this study, we describe a method for extracting realistic cell morphologies from fluorescence microscopy images to generate the piecewise continuous mesh used to develop a finite element model in two dimensions. The preelectroporation TMP induced in tightly packed cells is analyzed for two sets of pulse parameters inspired by clinical irreversible electroporation treatments. We show that high-frequency bipolar pulse trains are better, and more homogeneously raise the TMP of tightly packed cells to a simulated electroporation threshold than conventional irreversible electroporation pulse trains, at the expense of larger applied potentials. Our results demonstrate the viability of our method and emphasize the importance of considering multicellular effects in the numerical models used for studying the response of biological tissues exposed to electric fields.

  2. The Nature of Self-Directed Learning and Transformational Learning in Self-Managing Bipolar Disorder to Stay Well

    ERIC Educational Resources Information Center

    Francik, Wendy A.

    2012-01-01

    The purpose of the research was to explore the self-directed learning and transformational learning experiences among persons with bipolar disorder. A review of previous research pointed out how personal experiences with self-directed learning and transformational learning facilitated individuals' learning to manage HIV, Methicillan-resitant…

  3. The Relationship between Engineering Students' Self-Directed Learning Abilities and Online Learning Performances: A Pilot Study

    ERIC Educational Resources Information Center

    Chou, Pao-Nan

    2012-01-01

    This study aimed to explore engineering students' self-directed learning abilities in an online learning environment. The research centered on the correlation relationship between students' self-directed learning abilities and learning outcomes. The instructional activity in one experimental study was to simulate an online learning task in the…

  4. Exploring Self-Directed Learning in the Online Learning Environment: Comparing Traditional versus Nontraditional Learner Populations a Qualitative Study

    ERIC Educational Resources Information Center

    Plews, Rachel Christine

    2016-01-01

    The purpose of this study was to explore self-directed learning in the online learning context. A sample of traditional and nontraditional learners, who were considered above average in their level of self-direction, participated in qualitative interviews to discuss their learning while engaged in an online course. The findings suggested no major…

  5. Understanding Faculty and Non-Traditional Student Perceptions of Self-Directed Learning in a Practical Nursing Program

    ERIC Educational Resources Information Center

    Rogers, Carmen

    2013-01-01

    This study was designed to identify and investigate nursing faculty and student perspectives of self-directed learning in a practical nursing program. It also explored the degree to which student's perceptions of self-directed learning exhibited factors consistent with that of critical thinking. This study is important because self-directed…

  6. Teachers' Self-Directed Professional Development: Science and Mathematics Teachers' Adoption of ICT as a Professional Development Strategy

    ERIC Educational Resources Information Center

    Mushayikwa, Emmanuel

    2013-01-01

    This paper is part of a larger study that was carried out to investigate the use of Information and Communication Technology (ICT) in the self-directed professional development on the self-directed professional development (SDPD) of mathematics and science teachers in Zimbabwe. The educational context provides an example of how teachers…

  7. A Preliminary Investigation of Self-Directed Learning Activities in a Non-Formal Blended Learning Environment

    ERIC Educational Resources Information Center

    Schwier, Richard A.; Morrison, Dirk; Daniel, Ben K.

    2009-01-01

    This research considers how professional participants in a non-formal self-directed learning environment (NFSDL) made use of self-directed learning activities in a blended face-to-face and on line learning professional development course. The learning environment for the study was a professional development seminar on teaching in higher education…

  8. Intergroup conflict, out-group derogation, and self-directed negative affect among Italian South Tyroleans.

    PubMed

    Costarelli, Sandro; Colloca, Pasquale

    2004-04-01

    In South Tyrol, a multiethnic Italian province, the authors examined the self-directed negative affect that members of an Italian group experienced after they evaluated members of the German and Albanian groups. The authors examined the affect as a function of out-group derogation. The authors argued that to the extent that out-group derogation may run counter to norms toward intergroup fairness, such normative nonconformity will elicit negative affect directed at the self as a function of perceived intergroup conflict. The findings support the authors' line of reasoning: among Italian South Tyroleans, those who expressed greater out-group derogation were led to experience stronger negative self-directed affect when they rated a low-conflict out-group, but not when they rated a high-conflict out-group, compared to participants whose out-group derogation was less.

  9. Self-Directed Learning in Physician Assistant Education: Learning Portfolios in Physician Assistant Programs.

    PubMed

    Neal, Jeremy H; Neal, Laura D M

    2016-12-01

    Self-directed learning (SDL) portfolios are underused in the educational process and should be considered by physician assistant (PA) programs. Clinicians such as PAs are responsible for self-identifying their learning needs, competencies, and ongoing educational requirements. This article introduces an outline for SDL in the PA profession, for direct use by learners and indirect use by educators. Without a plan, many professionals may lack the insight, motivation, and knowledge needed to improve their skill set and establish goals for individual lifelong learning. This study conducted a review of the literature. Then, by incorporating SDL portfolios into PA educational methodologies, it constructed a concept map for individuals to monitor, self-direct, and actively participate in their own learning in academic settings and throughout their career.

  10. The Effects of Case-Based Team Learning on Students’ Learning, Self Regulation and Self Direction

    PubMed Central

    Rezaee, Rita; Mosalanejad, Leili

    2015-01-01

    Introduction: The application of the best approaches to teach adults in medical education is important in the process of training learners to become and remain effective health care providers. This research aims at designing and integrating two approaches, namely team teaching and case study and tries to examine the consequences of these approaches on learning, self regulation and self direction of nursing students. Material & Methods: This is aquasi experimental study of 40 students who were taking a course on mental health. The lessons were designed by using two educational techniques: short case based study and team based learning. Data gathering was based on two valid and reliablequestionnaires: Self-Directed Readiness Scale (SDLRS) and the self-regulating questionnaire. Open ended questions were also designed for the evaluation of students’with points of view on educational methods. Results: The Results showed an increase in the students’ self directed learning based on their performance on the post-test. The results showed that the students’ self-directed learning increased after the intervention. The mean difference before and after intervention self management was statistically significant (p=0.0001). Also, self-regulated learning increased with the mean difference after intervention (p=0.001). Other results suggested that case based team learning can have significant effects on increasing students’ learning (p=0.003). Conclusion: This article may be of value to medical educators who wish to replace traditional learning with informal learning (student-centered-active learning), so as to enhance not only the students’ ’knowledge, but also the advancement of long- life learning skills. PMID:25946918

  11. Aging and health: Self-efficacy for Self-direction in Health Scale

    PubMed Central

    Oliveira, Albertina L; Silva, José T; Lima, Margarida P

    2016-01-01

    ABSTRACT OBJECTIVE To validate the Escala de Autoeficácia para a Autodireção na Saúde (EAAS – Self-efficacy for Self-direction in Health Scale). METHODS Non-experimental quantitative study of EAAS validation, by confirmatory factorial analyses, evaluating a sample of 508 older adults from the north and the center of Portugal with mean age of 71.67 (from 51 to 96 years), to whom the Self-efficacy for Self-direction in Health Scale, the Rosenberg Self-esteem Scale, the Positive and Negative Affect Schedule, the Satisfaction with Life Scale, and the Instrumental Activities of Daily Living Scale were applied. The EAAS was developed from the theoretical constructs of self-efficacy and from self-directed learning within the PALADIN European project framework, aiming to develop an instrument able to assess the extent to which older adults take good care of their health. RESULTS The internal consistency was 0.87 (Cronbach’s alpha) and confirmatory factorial analyses enabled to find a model near the one theoretically proposed, indicating a structure consisting of four dimensions: physical exercise, healthy diet, engaging in health-related learning, and visits to health professionals. From the psychometric point of view, the model in four factors showed quite satisfactory fit indicators. CONCLUSIONS The Self-efficacy for Self-direction in Health Scale, with 16 items, is adequate to evaluate to what extent older adults have confidence in their ability to take care of their own health, with high degree of autonomy. PMID:27384970

  12. Are self-directed work teams successful and effective tools for today`s organization?

    SciTech Connect

    Arnwine, A.D.

    1995-03-01

    The purpose of this research is to (1) show the effectiveness and success of self-directed work teams within the organization, (2) emphasize the importance of team building in the success of the team, and (3) assist organizations in building self-directed work teams. The researcher used a direct survey and studied the following team building techniques: (1) Is the team`s mission clearly defined to each team member? (2) Are the goals clearly defined and achievable by all team members? (3) Will empowerment (decision-making power) be given equally to all team members? (4) Will open and honest communication be allowed among team members? (5) Will each team member be respected and valued for his/her position on the team? (6) Are self-directed work teams effectively rewarded for accomplishments? (7) Have team members received adequate training to effectively complete their job tasks? Upon completion of the literature review and statistical data, and after analyzing the seven areas of team building techniques, it was determined three of the four teams were successful and effective. The only area of concern to the organization is that the participants felt they did not have true ownership of their teams; that is, team members were not given full empowerment. According to this study and the review of literature, full empowerment must be given to achieve successful and effective teams. If true empowerment is not given, the team will suffer in other areas of team building, and the organization will lose a valuable tool.

  13. Self-directed exploration provides a Ncs1-dependent learning bonus.

    PubMed

    Mun, Ho-Suk; Saab, Bechara J; Ng, Enoch; McGirr, Alexander; Lipina, Tatiana V; Gondo, Yoichi; Georgiou, John; Roder, John C

    2015-12-07

    Understanding the mechanisms of memory formation is fundamental to establishing optimal educational practices and restoring cognitive function in brain disease. Here, we show for the first time in a non-primate species, that spatial learning receives a special bonus from self-directed exploration. In contrast, when exploration is escape-oriented, or when the full repertoire of exploratory behaviors is reduced, no learning bonus occurs. These findings permitted the first molecular and cellular examinations into the coupling of exploration to learning. We found elevated expression of neuronal calcium sensor 1 (Ncs1) and dopamine type-2 receptors upon self-directed exploration, in concert with increased neuronal activity in the hippocampal dentate gyrus and area CA3, as well as the nucleus accumbens. We probed further into the learning bonus by developing a point mutant mouse (Ncs1(P144S/P144S)) harboring a destabilized NCS-1 protein, and found this line lacked the equivalent self-directed exploration learning bonus. Acute knock-down of Ncs1 in the hippocampus also decoupled exploration from efficient learning. These results are potentially relevant for augmenting learning and memory in health and disease, and provide the basis for further molecular and circuit analyses in this direction.

  14. Inspiring Climate Education Excellence (ICEE): Developing self-directed professional development modules for secondary science teachers

    NASA Astrophysics Data System (ADS)

    Buhr, S. M.; Lynds, S. E.; McCaffrey, M. S.; Morton, E.

    2010-12-01

    Inspiring Climate Education Excellence (ICEE) is a NASA-funded project to develop online course modules and self-directed learning resources aligned with the Essential Principles of Climate Science. Following a national needs assessment survey and a face to face workshop to pilot test topics, a suite of online modules is being developed suitable for self-directed learning by secondary science teachers. Modules are designed around concepts and topics in which teachers express the most interest and need for instruction. Module design also includes attention to effective teaching strategies, such as awareness of student misconceptions, strategies for forestalling controversy and advice from master teachers on implementation and curriculum development. The resources are being developed in partnership with GLOBE, and the National Science Digital Library (NSDL) and is informed by the work of the Climate Literacy and Energy Awareness Network (CLEAN) project. ICEE will help to meet the professional development needs of teachers, including those participating in the GLOBE Student Climate Research Campaign. Modules and self-directed learning resources will be developed and disseminated in partnership with the National Science Digital Library (NSDL). This presentation introduces the needs assessment and pilot workshop data upon which the modules are based, and describes the modules that are available and in development.

  15. Self-directed exploration provides a Ncs1-dependent learning bonus

    PubMed Central

    Mun, Ho-Suk; Saab, Bechara J.; Ng, Enoch; McGirr, Alexander; Lipina, Tatiana V.; Gondo, Yoichi; Georgiou, John; Roder, John C.

    2015-01-01

    Understanding the mechanisms of memory formation is fundamental to establishing optimal educational practices and restoring cognitive function in brain disease. Here, we show for the first time in a non-primate species, that spatial learning receives a special bonus from self-directed exploration. In contrast, when exploration is escape-oriented, or when the full repertoire of exploratory behaviors is reduced, no learning bonus occurs. These findings permitted the first molecular and cellular examinations into the coupling of exploration to learning. We found elevated expression of neuronal calcium sensor 1 (Ncs1) and dopamine type-2 receptors upon self-directed exploration, in concert with increased neuronal activity in the hippocampal dentate gyrus and area CA3, as well as the nucleus accumbens. We probed further into the learning bonus by developing a point mutant mouse (Ncs1P144S/P144S) harboring a destabilized NCS-1 protein, and found this line lacked the equivalent self-directed exploration learning bonus. Acute knock-down of Ncs1 in the hippocampus also decoupled exploration from efficient learning. These results are potentially relevant for augmenting learning and memory in health and disease, and provide the basis for further molecular and circuit analyses in this direction. PMID:26639399

  16. An Integrated In Vitro Imaging Platform for Characterizing Filarial Parasite Behavior within a Multicellular Microenvironment

    PubMed Central

    Kassis, Timothy; Skelton, Henry M.; Lu, Iris M.; Moorhead, Andrew R.; Dixon, J. Brandon

    2014-01-01

    Lymphatic Filariasis, a Neglected Tropical Disease, is caused by thread-like parasitic worms, including B. malayi, which migrate to the human lymphatic system following transmission. The parasites reside in collecting lymphatic vessels and lymph nodes for years, often resulting in lymphedema, elephantiasis or hydrocele. The mechanisms driving worm migration and retention within the lymphatics are currently unknown. We have developed an integrated in vitro imaging platform capable of quantifying B. malayi migration and behavior in a multicellular microenvironment relevant to the initial site of worm injection by incorporating the worm in a Polydimethylsiloxane (PDMS) microchannel in the presence of human dermal lymphatic endothelial cells (LECs) and human dermal fibroblasts (HDFs). The platform utilizes a motorized controllable microscope with CO2 and temperature regulation to allow for worm tracking experiments with high resolution over large length and time scales. Using post-acquisition algorithms, we quantified four parameters: 1) speed, 2) thrashing intensity, 3) percentage of time spent in a given cell region and 4) persistence ratio. We demonstrated the utility of our system by quantifying these parameters for L3 B. malayi in the presence of LECs and HDFs. Speed and thrashing increased in the presence of both cell types and were altered within minutes upon exposure to the anthelmintic drug, tetramisole. The worms displayed no targeted migration towards either cell type for the time course of this study (3 hours). When cells were not present in the chamber, worm thrashing correlated directly with worm speed. However, this correlation was lost in the presence of cells. The described platform provides the ability to further study B. malayi migration and behavior. PMID:25412444

  17. Validation of Immune Cell Modules in Multicellular Transcriptomic Data

    PubMed Central

    Heather, James M.; Byng-Maddick, Rachel; Guppy, Naomi; Ellis, Matthew; Turner, Carolin T.; Chain, Benjamin M.; Noursadeghi, Mahdad

    2017-01-01

    Numerous gene signatures, or modules have been described to evaluate the immune cell composition in transcriptomes of multicellular tissue samples. However, significant diversity in module gene content for specific cell types is associated with heterogeneity in their performance. In order to rank modules that best reflect their purported association, we have generated the modular discrimination index (MDI) score that assesses expression of each module in the target cell type relative to other cells. We demonstrate that MDI scores predict modules that best reflect independently validated differences in cellular composition, and correlate with the covariance between cell numbers and module expression in human blood and tissue samples. Our analyses demonstrate that MDI scores provide an ordinal summary statistic that reliably ranks the accuracy of gene expression modules for deconvolution of cell type abundance in transcriptional data. PMID:28045996

  18. Modeling a synthetic multicellular clock: Repressilators coupled by quorum sensing

    PubMed Central

    Garcia-Ojalvo, Jordi; Elowitz, Michael B.; Strogatz, Steven H.

    2004-01-01

    Diverse biochemical rhythms are generated by thousands of cellular oscillators that somehow manage to operate synchronously. In fields ranging from circadian biology to endocrinology, it remains an exciting challenge to understand how collective rhythms emerge in multicellular structures. Using mathematical and computational modeling, we study the effect of coupling through intercell signaling in a population of Escherichia coli cells expressing a synthetic biological clock. Our results predict that a diverse and noisy community of such genetic oscillators interacting through a quorum-sensing mechanism should self-synchronize in a robust way, leading to a substantially improved global rhythmicity in the system. As such, the particular system of coupled genetic oscillators considered here might be a good candidate to provide the first quantitative example of a synchronization transition in a population of biological oscillators. PMID:15256602

  19. Sorodiplophrys stercorea: Another Novel Lineage of Sorocarpic Multicellularity.

    PubMed

    Tice, Alexander K; Silberman, Jeffrey D; Walthall, Austin C; Le, Khoa N D; Spiegel, Frederick W; Brown, Matthew W

    2016-09-01

    Sorodiplophrys stercorea is a sorocarpic organism that utilizes filose pseudopodia for locomotion and absorptive nutrition. It has traditionally been considered to be a member of the Labyrinthulae based on its morphology. Its closest relatives were thought to be species in the taxon Diplophrys. Since the genus Diplophrys has been shown to be paraphyletic and S. stercorea has pseudopodia similar to some members of Rhizaria, we examined its relationship with other eukaryotes. We obtained four isolates from the dung of cow and horse, brought each into monoeukaryotic culture, and sequenced their SSU rRNA gene for phylogenetic analysis. All our isolates were shown to form a monophyletic group in the Labyrinthulae, nested in the Amphifiloidea clade. Our results demonstrate that Sorodiplophrys is more closely related to species of the genus Amphifila than to Diplophrys and represents an additional independent origin of sorocarpic multicellularity among eukaryotes. This study represents the first confirmed sorocarpic lifestyle in the Stramenopiles.

  20. Multicellular tumor spheroid interactions with bone cells and bone

    SciTech Connect

    Wezeman, F.H.; Guzzino, K.M.; Waxler, B.

    1985-10-01

    In vitro coculture techniques were used to study HSDM1C1 murine fibrosarcoma multicellular tumor spheroid (HSDM1C1-MTS) interactions with mouse calvarial bone cells having osteoblastic characteristics and mouse bone explants. HSDM1C1-MTS attached to confluent bone cell monolayers and their attachment rate was quantified. HSDM1C1-MTS interaction with bone cells was further demonstrated by the release of /sup 3/H-deoxyuridine from prelabeled bone cells during coculture with multicellular tumor spheroids. HSDM1C1-MTS-induced cytotoxicity was mimicked by the addition of 10(-5) M prostaglandin E2 (PGE2) to /sup 3/H-deoxyuridine-labeled bone cells. The effects of low (10(-9) M) and high (10(-5) M) concentrations of PGE2 on bone cell proliferation were also studied. Higher concentrations of PGE2 inhibited bone cell proliferation. HSDM1C1-MTS resorbed living explants in the presence of indomethacin, suggesting that other tumor cell products may also participate in bone resorption. HSDM1C1-MTS caused direct bone resorption as measured by the significantly elevated release of /sup 45/Ca from prelabeled, devitalized calvaria. However, the growth of a confluent bone cell layer on devitalized, /sup 45/Ca-prelabeled calvaria resulted in a significant reduction in the amount of /sup 45/Ca released subsequent to the seeding of HSDM1C1-MTS onto the explants. Bone cells at the bone surface may act as a barrier against invasion and tumor cell-mediated bone resorption. Violation of this cellular barrier is achieved, in part, by tumor cell products.

  1. Green Algae and the Origins of Multicellularity in the Plant Kingdom

    PubMed Central

    Umen, James G.

    2014-01-01

    The green lineage of chlorophyte algae and streptophytes form a large and diverse clade with multiple independent transitions to produce multicellular and/or macroscopically complex organization. In this review, I focus on two of the best-studied multicellular groups of green algae: charophytes and volvocines. Charophyte algae are the closest relatives of land plants and encompass the transition from unicellularity to simple multicellularity. Many of the innovations present in land plants have their roots in the cell and developmental biology of charophyte algae. Volvocine algae evolved an independent route to multicellularity that is captured by a graded series of increasing cell-type specialization and developmental complexity. The study of volvocine algae has provided unprecedented insights into the innovations required to achieve multicellularity. PMID:25324214

  2. Movement-related theta rhythm in humans: coordinating self-directed hippocampal learning.

    PubMed

    Kaplan, Raphael; Doeller, Christian F; Barnes, Gareth R; Litvak, Vladimir; Düzel, Emrah; Bandettini, Peter A; Burgess, Neil

    2012-01-01

    The hippocampus is crucial for episodic or declarative memory and the theta rhythm has been implicated in mnemonic processing, but the functional contribution of theta to memory remains the subject of intense speculation. Recent evidence suggests that the hippocampus might function as a network hub for volitional learning. In contrast to human experiments, electrophysiological recordings in the hippocampus of behaving rodents are dominated by theta oscillations reflecting volitional movement, which has been linked to spatial exploration and encoding. This literature makes the surprising cross-species prediction that the human hippocampal theta rhythm supports memory by coordinating exploratory movements in the service of self-directed learning. We examined the links between theta, spatial exploration, and memory encoding by designing an interactive human spatial navigation paradigm combined with multimodal neuroimaging. We used both non-invasive whole-head Magnetoencephalography (MEG) to look at theta oscillations and Functional Magnetic Resonance Imaging (fMRI) to look at brain regions associated with volitional movement and learning. We found that theta power increases during the self-initiation of virtual movement, additionally correlating with subsequent memory performance and environmental familiarity. Performance-related hippocampal theta increases were observed during a static pre-navigation retrieval phase, where planning for subsequent navigation occurred. Furthermore, periods of the task showing movement-related theta increases showed decreased fMRI activity in the parahippocampus and increased activity in the hippocampus and other brain regions that strikingly overlap with the previously observed volitional learning network (the reverse pattern was seen for stationary periods). These fMRI changes also correlated with participant's performance. Our findings suggest that the human hippocampal theta rhythm supports memory by coordinating exploratory

  3. Mirror-induced self-directed behaviors in rhesus monkeys after visual-somatosensory training.

    PubMed

    Chang, Liangtang; Fang, Qin; Zhang, Shikun; Poo, Mu-ming; Gong, Neng

    2015-01-19

    Mirror self-recognition is a hallmark of higher intelligence in humans. Most children recognize themselves in the mirror by 2 years of age. In contrast to human and some great apes, monkeys have consistently failed the standard mark test for mirror self-recognition in all previous studies. Here, we show that rhesus monkeys could acquire mirror-induced self-directed behaviors resembling mirror self-recognition following training with visual-somatosensory association. Monkeys were trained on a monkey chair in front of a mirror to touch a light spot on their faces produced by a laser light that elicited an irritant sensation. After 2-5 weeks of training, monkeys had learned to touch a face area marked by a non-irritant light spot or odorless dye in front of a mirror and by a virtual face mark on the mirroring video image on a video screen. Furthermore, in the home cage, five out of seven trained monkeys showed typical mirror-induced self-directed behaviors, such as touching the mark on the face or ear and then looking at and/or smelling their fingers, as well as spontaneously using the mirror to explore normally unseen body parts. Four control monkeys of a similar age that went through mirror habituation but had no training of visual-somatosensory association did not pass any mark tests and did not exhibit mirror-induced self-directed behaviors. These results shed light on the origin of mirror self-recognition and suggest a new approach to studying its neural mechanism.

  4. Movement-Related Theta Rhythm in Humans: Coordinating Self-Directed Hippocampal Learning

    PubMed Central

    Kaplan, Raphael; Doeller, Christian F.; Barnes, Gareth R.; Litvak, Vladimir; Düzel, Emrah; Bandettini, Peter A.; Burgess, Neil

    2012-01-01

    The hippocampus is crucial for episodic or declarative memory and the theta rhythm has been implicated in mnemonic processing, but the functional contribution of theta to memory remains the subject of intense speculation. Recent evidence suggests that the hippocampus might function as a network hub for volitional learning. In contrast to human experiments, electrophysiological recordings in the hippocampus of behaving rodents are dominated by theta oscillations reflecting volitional movement, which has been linked to spatial exploration and encoding. This literature makes the surprising cross-species prediction that the human hippocampal theta rhythm supports memory by coordinating exploratory movements in the service of self-directed learning. We examined the links between theta, spatial exploration, and memory encoding by designing an interactive human spatial navigation paradigm combined with multimodal neuroimaging. We used both non-invasive whole-head Magnetoencephalography (MEG) to look at theta oscillations and Functional Magnetic Resonance Imaging (fMRI) to look at brain regions associated with volitional movement and learning. We found that theta power increases during the self-initiation of virtual movement, additionally correlating with subsequent memory performance and environmental familiarity. Performance-related hippocampal theta increases were observed during a static pre-navigation retrieval phase, where planning for subsequent navigation occurred. Furthermore, periods of the task showing movement-related theta increases showed decreased fMRI activity in the parahippocampus and increased activity in the hippocampus and other brain regions that strikingly overlap with the previously observed volitional learning network (the reverse pattern was seen for stationary periods). These fMRI changes also correlated with participant's performance. Our findings suggest that the human hippocampal theta rhythm supports memory by coordinating exploratory

  5. Self-directed learning in the context of a nursing curriculum: development of a learning plan.

    PubMed

    Majumdar, B

    1996-06-01

    The rapid pace at which biological health breakthroughs and advancements in technology occur is creating unique challenges to health care programmes. The curricula of all health care programmes will need to be set in learning environments where students will be able to develop learning skills that are transportable across situations, over a whole lifetime. This article attempts to focus on self-directed learning (SDL) concepts and the development of a learning contract/plan, including the roles of both the student and faculty in self-learning approaches and contractual development.

  6. Self-directed learning readiness of Asian students: students perspective on a hybrid problem based learning curriculum

    PubMed Central

    Susilo, Astrid P.; van Berkel, Henk

    2016-01-01

    Objectives To identify the student’s readiness to perform self-directed learning and the underlying factors influencing it on the hybrid problem based learning curriculum. Methods A combination of quantitative and qualitative studies was conducted in five medical schools in Indonesia. In the quantitative study, the Self Directed Learning Readiness Scale was distributed to all students in all batches, who had experience with the hybrid problem based curriculum. They were categorized into low- and high -level based on the score of the questionnaire. Three focus group discussions (low-, high-, and mixed level) were conducted in the qualitative study with six to twelve students chosen randomly from each group to find the factors influencing their self-directed learning readiness. Two researchers analysed the qualitative data as a measure of triangulation. Results The quantitative study showed only half of the students had a high-level of self-directed learning readiness, and a similar trend also occurred in each batch. The proportion of students with a high level of self-directed learning readiness was lower in the senior students compared to more junior students. The qualitative study showed that problem based learning processes, assessments, learning environment, students’ life styles, students’ perceptions of the topics, and mood, were factors influencing their self-directed learning. Conclusion A hybrid problem based curriculum may not fully affect the students’ self-directed learning. The curriculum system, teacher’s experiences, student’s background and cultural factors might contribute to the difficulties for the student’s in conducting self-directed learning. PMID:27915308

  7. Medicaid program; self-directed personal assistance services program State Plan option (cash and counseling). Final rule.

    PubMed

    2008-10-03

    This final rule provides guidance to States that want to administer self-directed personal assistance services through their State Plans, as authorized by the Deficit Reduction Act of 2005. The State plan option allows beneficiaries, through an approved self-directed services plan and budget, to purchase personal assistance services. The rule also provides guidance to ensure beneficiary health and welfare and financial accountability of the State Plan option.

  8. Initial Validation of the Self-Directed Violence Picture System (SDVPS).

    PubMed

    Nazem, Sarra; Forster, Jeri E; Brenner, Lisa A

    2017-02-16

    A better understanding of factors that differentiate those who only experience suicidal ideation from those who engage in self-directed violence (SDV) is critical for suicide prevention efforts (Klonsky & May, 2014; May & Klonsky, 2016). To identify who is at greatest risk for death by suicide, it is imperative that new innovative assessment tools be created to facilitate behavioral measurement of key constructs associated with increased risk for SDV. The aim of the current study was to develop and validate a set of suicide-specific images, called the Self-Directed Violence Picture System (SDVPS), to help meet this need. A sample of 119 U.S. military veterans provided valence, arousal, and dominance ratings on the SDVPS. These ratings were compared to International Affective Picture System (IAPS) negative, neutral, and positive images. SDVPS images were rated with significantly greater negative valence and elicited decreased feelings of being in control than did IAPS positive (p < .001, p < .001), IAPS negative (p = .03, p = .001), and IAPS neutral (p < .001, p < .001) images. SDVPS images were also rated with significantly greater arousal than were IAPS neutral images (p < .001). Initial validation data support that the SDVPS images functioned as intended. Although continued validation of the SDVPS in other populations is necessary, the SDVPS may become a new tool by which researchers can begin to systematically and reliably examine reactions to suicide-related content using behavioral and/or experimental paradigms. (PsycINFO Database Record

  9. Constructive, collaborative, contextual, and self-directed learning in surface anatomy education.

    PubMed

    Bergman, Esther M; Sieben, Judith M; Smailbegovic, Ida; de Bruin, Anique B H; Scherpbier, Albert J J A; van der Vleuten, Cees P M

    2013-01-01

    Anatomy education often consists of a combination of lectures and laboratory sessions, the latter frequently including surface anatomy. Studying surface anatomy enables students to elaborate on their knowledge of the cadaver's static anatomy by enabling the visualization of structures, especially those of the musculoskeletal system, move and function in a living human being. A recent development in teaching methods for surface anatomy is body painting, which several studies suggest increases both student motivation and knowledge acquisition. This article focuses on a teaching approach and is a translational contribution to existing literature. In line with best evidence medical education, the aim of this article is twofold: to briefly inform teachers about constructivist learning theory and elaborate on the principles of constructive, collaborative, contextual, and self-directed learning; and to provide teachers with an example of how to implement these learning principles to change the approach to teaching surface anatomy. Student evaluations of this new approach demonstrate that the application of these learning principles leads to higher student satisfaction. However, research suggests that even better results could be achieved by further adjustments in the application of contextual and self-directed learning principles. Successful implementation and guidance of peer physical examination is crucial for the described approach, but research shows that other options, like using life models, seem to work equally well. Future research on surface anatomy should focus on increasing the students' ability to apply anatomical knowledge and defining the setting in which certain teaching methods and approaches have a positive effect.

  10. Synchronization of Eukaryotic Flagella and the Evolution of Multicellularity

    NASA Astrophysics Data System (ADS)

    Goldstein, Raymond

    2009-03-01

    Flagella, among the most highly conserved structures in eukaryotes, are responsible for such tasks as fluid transport, motility and phototaxis, establishment of embryonic left-right asymmetry, and intercellular communication, and are thought to have played a key role in the development of multicellularity. These tasks are usually performed by the coordinated action of groups of flagella (from pairs to thousands), which display various types of spatio-temporal organization. The origin and quantitative characterization of flagellar synchronization has remained an important open problem, involving interplay between intracellular biochemistry and interflagellar mechanical/hydrodynamic coupling. The Volvocine green algae serve as useful model organisms for the study of these phenomena, as they form a lineage spanning from unicellular Chlamydomonas to germ-soma differentiated Volvox, having as many as 50,000 biflagellated surface somatic cells. In this talk I will describe extensive studies [1], using micromanipulation and high-speed imaging, of the flagellar synchronization of two key species - Chlamydomonas reinhardtii and Volvox carteri - over tens of thousands of cycles. With Chlamydomonas we find that the flagellar dynamics moves back and forth between a stochastic synchronized state consistent with a simple model of hydrodynamically coupled noisy oscillators, and a deterministic one driven by a large interflagellar frequency difference. These results reconcile previously contradictory studies, based on short observations, showing only one or the other of these two states, and, more importantly, show that the flagellar beat frequencies themselves are regulated by the cell. Moreover, high-resolution three-dimensional tracking of swimming cells provides strong evidence that these dynamical states are related to reorientation events in the trajectories, yielding a eukaryotic equivalent of the ``run and tumble'' motion of peritrichously flagellated bacteria. The degree

  11. Development of cell differentiation in the transition to multicellularity: a dynamical modeling approach

    PubMed Central

    Mora Van Cauwelaert, Emilio; Arias Del Angel, Juan A.; Benítez, Mariana; Azpeitia, Eugenio M.

    2015-01-01

    Multicellularity has emerged and continues to emerge in a variety of lineages and under diverse environmental conditions. In order to attain individuality and integration, multicellular organisms must exhibit spatial cell differentiation, which in turn allows cell aggregates to robustly generate traits and behaviors at the multicellular level. Nevertheless, the mechanisms that may lead to the development of cellular differentiation and patterning in emerging multicellular organisms remain unclear. We briefly review two conceptual frameworks that have addressed this issue: the cooperation-defection framework and the dynamical patterning modules (DPMs) framework. Then, situating ourselves in the DPM formalism first put forward by S. A. Newman and collaborators, we state a hypothesis for cell differentiation and arrangement in cellular masses of emerging multicellular organisms. Our hypothesis is based on the role of the generic cell-to-cell communication and adhesion patterning mechanisms, which are two fundamental mechanisms for the evolution of multicellularity, and whose molecules seem to be well-conserved in extant multicellular organisms and their unicellular relatives. We review some fundamental ideas underlying this hypothesis and contrast them with empirical and theoretical evidence currently available. Next, we use a mathematical model to illustrate how the mechanisms and assumptions considered in the hypothesis we postulate may render stereotypical arrangements of differentiated cells in an emerging cellular aggregate and may contribute to the variation and recreation of multicellular phenotypes. Finally, we discuss the potential implications of our approach and compare them to those entailed by the cooperation-defection framework in the study of cell differentiation in the transition to multicellularity. PMID:26157427

  12. Development of cell differentiation in the transition to multicellularity: a dynamical modeling approach.

    PubMed

    Mora Van Cauwelaert, Emilio; Arias Del Angel, Juan A; Benítez, Mariana; Azpeitia, Eugenio M

    2015-01-01

    Multicellularity has emerged and continues to emerge in a variety of lineages and under diverse environmental conditions. In order to attain individuality and integration, multicellular organisms must exhibit spatial cell differentiation, which in turn allows cell aggregates to robustly generate traits and behaviors at the multicellular level. Nevertheless, the mechanisms that may lead to the development of cellular differentiation and patterning in emerging multicellular organisms remain unclear. We briefly review two conceptual frameworks that have addressed this issue: the cooperation-defection framework and the dynamical patterning modules (DPMs) framework. Then, situating ourselves in the DPM formalism first put forward by S. A. Newman and collaborators, we state a hypothesis for cell differentiation and arrangement in cellular masses of emerging multicellular organisms. Our hypothesis is based on the role of the generic cell-to-cell communication and adhesion patterning mechanisms, which are two fundamental mechanisms for the evolution of multicellularity, and whose molecules seem to be well-conserved in extant multicellular organisms and their unicellular relatives. We review some fundamental ideas underlying this hypothesis and contrast them with empirical and theoretical evidence currently available. Next, we use a mathematical model to illustrate how the mechanisms and assumptions considered in the hypothesis we postulate may render stereotypical arrangements of differentiated cells in an emerging cellular aggregate and may contribute to the variation and recreation of multicellular phenotypes. Finally, we discuss the potential implications of our approach and compare them to those entailed by the cooperation-defection framework in the study of cell differentiation in the transition to multicellularity.

  13. Cooperatively Generated Stresslet Flows Supply Fresh Fluid to Multicellular Choanoflagellate Colonies

    NASA Astrophysics Data System (ADS)

    Roper, Marcus; Dayel, Mark J.; Pepper, Rachel E.; Koehl, M. A. R.

    2013-05-01

    The flagellated protozoan Salpingoeca rosetta is one of the closest relatives of multicellular animals. Unicellular S. rosetta can be induced to form multicellular colonies, but colonies swim more slowly than individual cells so the advantages conferred by colony formation are uncertain. Here we use theoretical models to show that hydrodynamic cooperation between cells can increase the fluid supply to the colony, an important predictor of feeding rate. Our results suggest that hydrodynamic benefits may have been an important selective factor in the evolution of early multicellular animals.

  14. Sliding mode control for a three phase multicellular inverter dedicated to renewable energy systems

    NASA Astrophysics Data System (ADS)

    Hemici, K.; Zegaoui, A.; Djahbar, A.; Bokhtache, A. Aissa; Kessaissia, F. Z.; Allouache, H.; Mahmoudi, M. O.; Aillerie, M.

    2017-02-01

    In this paper, Sliding Mode controller has been sized to control multi-cell converters configured as a three-phase multicellular inverter. Unlike traditional inverters, multicellular inverters have the following advantages: lower switching frequency, high number of output levels, and less voltage constraints on the power switch. Significant performances are provided with this structure, which is constituted with flying capacitors. The main purpose of this paper is to present the model and generate commutation sliding-surfaces based on a Lyapunov function. The performed simulations point the efficiency of the proposed strategy with a three-phase multicellular inverters and allow to assess the performances and the robustness of the synthesized controller.

  15. Identification of Dictyostelium G alpha genes expressed during multicellular development.

    PubMed Central

    Hadwiger, J A; Wilkie, T M; Strathmann, M; Firtel, R A

    1991-01-01

    Guanine nucleotide-binding protein (G protein)-mediated signal transduction constitutes a common mechanism by which cells receive and respond to a diverse set of environmental signals. Many of the signals involved in the developmental life cycle of the slime mold Dictyostelium have been postulated to be transduced by such pathways and, in some cases, these pathways have been demonstrated to be dependent on specific G proteins. Using the polymerase chain reaction, we have identified two additional Dictyostelium G alpha genes, G alpha 4 and G alpha 5, that are developmentally regulated. Transcripts from both of these genes are primarily expressed during the multicellular stages of development, suggesting possible roles in cell differentiation or morphogenesis. The entire G alpha 4 gene was sequenced and found to encode a protein consisting of 345 amino acids. The G alpha 4 subunit is homologous to other previously identified G alpha subunits, including the Dictyostelium G alpha 1 (43% identity) and G alpha 2 (41% identity) subunits. However, the G alpha 4 subunit contains some unusual sequence divergences in residues highly conserved among most eukaryotic G alpha subunits, suggesting that G alpha 4 may be a member of another class of G alpha subunits. Images PMID:1910174

  16. Multicellularity and the Functional Interdependence of Motility and Molecular Transport

    NASA Astrophysics Data System (ADS)

    Solari, C.; Ganguly, S.; Kessler, J. O.; Michod, R.; Goldstein, R. E.

    2006-03-01

    Benefits, costs and requirements accompany the transition from motile totipotent unicellular organisms to multicellular organisms having cells specialized into reproductive (germ) and vegetative (sterile soma) functions such as motility. In flagellated colonial organisms such as the volvocalean green algae, organized beating by the somatic cells' flagella yields propulsion important in phototaxis and chemotaxis. It has not been generally appreciated that for the larger colonies, flagellar stirring of boundary layers and remote transport are fundamental for maintaining a sufficient rate of metabolite turnover, one not attainable by diffusive transport alone. We describe experiments that quantify the role of advective dynamics in enhancing productivity in germ-soma differentiated colonies. First, experiments with suspended deflagellated colonies of Volvox carteri show that forced advection improves productivity. Second, Particle Imaging Velocimetry of fluid motion around colonies reveals flow fields with very large characteristic velocities U extending to length scales comparable to the colony radius R. For a typical metabolite diffusion constant D, the Peclet number Pe=2UR/D 1, indicative of the dominance of advection over diffusion, with striking augmentation at the cell division stage.

  17. MicroRNAs in a multicellular green alga Volvox carteri.

    PubMed

    Li, Jingrui; Wu, Yang; Qi, Yijun

    2014-01-01

    microRNAs (miRNAs) have emerged as key components in the eukaryotic gene regulatory network. We and others have previously identified many miRNAs in a unicellular green alga, Chlamydomonas reinhardtii. To investigate whether miRNA-mediated gene regulation is a general mechanism in green algae and how miRNAs have been evolved in the green algal lineage, we examined small RNAs in Volvox carteri, a multicellular species in the same family with Chlamydomonas reinhardtii. We identified 174 miRNAs in Volvox, with many of them being highly enriched in gonidia or somatic cells. The targets of the miRNAs were predicted and many of them were subjected to miRNA-mediated cleavage in vivo, suggesting that miRNAs play regulatory roles in the biology of green algae. Our catalog of miRNAs and their targets provides a resource for further studies on the evolution, biological functions, and genomic properties of miRNAs in green algae.

  18. Origins of multicellular complexity: Volvox and the volvocine algae.

    PubMed

    Herron, Matthew D

    2016-03-01

    The collection of evolutionary transformations known as the 'major transitions' or 'transitions in individuality' resulted in changes in the units of evolution and in the hierarchical structure of cellular life. Volvox and related algae have become an important model system for the major transition from unicellular to multicellular life, which touches on several fundamental questions in evolutionary biology. The Third International Volvox Conference was held at the University of Cambridge in August 2015 to discuss recent advances in the biology and evolution of this group of algae. Here, I highlight the benefits of integrating phylogenetic comparative methods and experimental evolution with detailed studies of developmental genetics in a model system with substantial genetic and genomic resources. I summarize recent research on Volvox and its relatives and comment on its implications for the genomic changes underlying major evolutionary transitions, evolution and development of complex traits, evolution of sex and sexes, evolution of cellular differentiation and the biophysics of motility. Finally, I outline challenges and suggest future directions for research into the biology and evolution of the volvocine algae.

  19. Multicellular contractility contributes to the emergence of mesothelioma nodules

    NASA Astrophysics Data System (ADS)

    Czirok, Andras

    Malignant pleural mesothelioma (MPM) nodules arise from the mesothelial lining of the pleural cavity by a poorly understood mechanism. We demonstrate that macroscopic multicellular aggregates, reminiscent of the MPM nodules found in patients, develop when MPM cell lines are cultured at high cell densities for several weeks. Surprisingly, the nodule-like aggregates do not arise by excessive local cell proliferation, but by myosin II-driven cell contractility. Contractile nodules contain prominent actin cables that can span several cells. Several features of the in vitro MPM nodule development can be explained by a computational model that assumes uniform and steady intercellular contractile forces within a monolayer of cells, and a mechanical load-dependent lifetime of cell-cell contacts. The model behaves as a self-tensioned Maxwell fluid and exhibits an instability that leads to pattern formation. Altogether, our findings suggest that inhibition of the actomyosin system may provide a hitherto not utilized therapeutic approach to affect MPM growth. NIH R01-GM102801.

  20. Biocellion: accelerating computer simulation of multicellular biological system models

    PubMed Central

    Kang, Seunghwa; Kahan, Simon; McDermott, Jason; Flann, Nicholas; Shmulevich, Ilya

    2014-01-01

    Motivation: Biological system behaviors are often the outcome of complex interactions among a large number of cells and their biotic and abiotic environment. Computational biologists attempt to understand, predict and manipulate biological system behavior through mathematical modeling and computer simulation. Discrete agent-based modeling (in combination with high-resolution grids to model the extracellular environment) is a popular approach for building biological system models. However, the computational complexity of this approach forces computational biologists to resort to coarser resolution approaches to simulate large biological systems. High-performance parallel computers have the potential to address the computing challenge, but writing efficient software for parallel computers is difficult and time-consuming. Results: We have developed Biocellion, a high-performance software framework, to solve this computing challenge using parallel computers. To support a wide range of multicellular biological system models, Biocellion asks users to provide their model specifics by filling the function body of pre-defined model routines. Using Biocellion, modelers without parallel computing expertise can efficiently exploit parallel computers with less effort than writing sequential programs from scratch. We simulate cell sorting, microbial patterning and a bacterial system in soil aggregate as case studies. Availability and implementation: Biocellion runs on x86 compatible systems with the 64 bit Linux operating system and is freely available for academic use. Visit http://biocellion.com for additional information. Contact: seunghwa.kang@pnnl.gov PMID:25064572

  1. Dupuytren's Contracture: Fibroblast Contraction?

    PubMed Central

    Gabbiani, Giulio; Majno, Guido

    1972-01-01

    In 6 cases of Dupuytren's disease and 1 of Ledderhose's disease, the nodules of the palmar and plantar aponeurosis were examined by light and electron microscopy. The cells composing these nodules, presumably fibroblasts, showed three significant ultrastructural features: (1) a fibrillar system similar to that of smooth muscle cells; (2) nuclear deformations such as are found in contracted cells, the severest being recognizable by light microscopy (cross-banded nuclei); (3) cell-to-cell and cell-to-stroma attachments. Based on these data and on recent information about the biology of the fibroblasts, it is suggested that these cells are fibroblasts that have modulated into contractile cells (myofibroblasts), and that their contraction plays a role in the pathogenesis of the contracture observed clinically. ImagesFig 10Fig 5Fig 11Fig 6 and 7Fig 8Fig 1Fig 2Fig 9Fig 3Fig 4 PMID:5009249

  2. Requirements for the self-directed replication of flock house virus RNA 1.

    PubMed Central

    Ball, L A

    1995-01-01

    The larger segment (RNA 1) of the bipartite, positive-sense RNA genome of the nodavirus flock house virus encodes the viral RNA-dependent RNA polymerase. Two nonstructural viral proteins are made during the self-directed replication of this RNA: protein A (110 kDa), the translation product of RNA 1 itself, and protein B (11 kDa), the translation product of a subgenomic RNA (RNA 3) that is produced from RNA 1 during replication. To examine the roles of these proteins in RNA replication, specialized T7 transcription plasmids that contained wild-type or mutant copies of flock house virus RNA 1 cDNA were constructed and used in cells infected with the vaccinia virus-T7 RNA polymerase recombinant to make full-length transcripts that directed their own replication. Sequences in the primary transcripts that extended beyond the ends of the authentic RNA 1 sequence inhibited self-directed RNA replication, but plasmids that were constructed to minimize these terminal extensions produced primary transcripts that replicated as abundantly as authentic RNA 1. Truncation or mutation of the open reading frame for protein A eliminated self-directed replication, although the mutant RNA 1 remained a competent template for replication by wild-type protein A supplied in trans. These results showed that protein A was essential for RNA replication and that the process was not inseparably coupled to complete translation of the template. In contrast, protein B could be eliminated without inhibiting replication by mutations that disrupted the second of the two overlapping open reading frames on RNA 3. Furthermore, a mutant of RNA 1 in which the first nucleotide of the RNA 3 region was changed from G to U replicated at levels as high as those of the wild type without making either RNA 3 or protein B. However, diminishing replication levels were observed during subsequent replicative passages of RNA from both the mutants that could not make protein B. Roles for this protein that could account

  3. Improved use of a public good selects for the evolution of undifferentiated multicellularity.

    PubMed

    Koschwanez, John H; Foster, Kevin R; Murray, Andrew W

    2013-04-02

    We do not know how or why multicellularity evolved. We used the budding yeast, Saccharomyces cerevisiae, to ask whether nutrients that must be digested extracellularly select for the evolution of undifferentiated multicellularity. Because yeast use invertase to hydrolyze sucrose extracellularly and import the resulting monosaccharides, single cells cannot grow at low cell and sucrose concentrations. Three engineered strategies overcame this problem: forming multicellular clumps, importing sucrose before hydrolysis, and increasing invertase expression. We evolved populations in low sucrose to ask which strategy they would adopt. Of 12 successful clones, 11 formed multicellular clumps through incomplete cell separation, 10 increased invertase expression, none imported sucrose, and 11 increased hexose transporter expression, a strategy we had not engineered. Identifying causal mutations revealed genes and pathways, which frequently contributed to the evolved phenotype. Our study shows that combining rational design with experimental evolution can help evaluate hypotheses about evolutionary strategies. DOI:http://dx.doi.org/10.7554/eLife.00367.001.

  4. Activated hepatic stellate cells play pivotal roles in hepatocellular carcinoma cell chemoresistance and migration in multicellular tumor spheroids

    PubMed Central

    Song, Yeonhwa; Kim, Se-hyuk; Kim, Kang Mo; Choi, Eun Kyung; Kim, Joon; Seo, Haeng Ran

    2016-01-01

    Most Hepatocellular carcinoma (HCC) are resistant to conventional chemotherapeutic agents and remain an unmet medical need. Recently, multiple studies on the crosstalk between HCC and their tumor microenvironment have been conducted to overcome chemoresistance in HCC. In this study, we formed multicellular tumor spheroids (MCTS) to elucidate the mechanisms of environment-mediated chemoresistance in HCC. We observed that hepatic stellate cells (HSCs) in MCTS significantly increased the compactness of spheroids and exhibited strong resistance to sorafenib and cisplatin relative to other types of stromal cells. Increased collagen 1A1 (COL1A1) expression was apparent in activated HSCs but not in fibroblasts or vascular endothelial cells in MCTS. Additionally, COL1A1 deficiency, which was increased by co-culture with HSCs, decreased the cell-cell interactions and thereby increased the therapeutic efficacy of anticancer therapies in MCTS. Furthermore, losartan, which can inhibit collagen I synthesis, attenuated the compactness of spheroids and increased the therapeutic efficacy of anticancer therapies in MCTS. Meanwhile, activated HSCs facilitated HCC migration by upregulating matrix metallopeptidase 9 (MMP9) in MCTS. Collectively, crosstalk between HCC cells and HSCs promoted HCC chemoresistance and migration by increasing the expression of COL1A1 and MMP9 in MCTS. Hence, targeting HSCs might represent a promising therapeutic strategy for liver cancer therapy. PMID:27853186

  5. A Quasi-Linear Behavioral Model and an Application to Self-Directed Learning

    NASA Technical Reports Server (NTRS)

    Ponton, Michael K.; Carr, Paul B.

    1999-01-01

    A model is presented that describes the relationship between one's knowledge of the world and the concomitant personal behaviors that serve as a mechanism to obtain desired outcomes. Integrated within this model are the differing roles that outcomes serve as motivators and as modifiers to one's worldview. The model is dichotomized between general and contextual applications. Because learner self-directedness (a personal characteristic) involves cognition and affection while self-directed learning (a pedagogic process) encompasses conation, behavior and introspection, the model can be dichotomized again in another direction. Presented also are the roles that cognitive motivation theories play in moving an individual through this behavioral model and the roles of wishes, self-efficacy, opportunity and self-influence.

  6. Improving workplace safety training using a self-directed CPR-AED learning program.

    PubMed

    Mancini, Mary E; Cazzell, Mary; Kardong-Edgren, Suzan; Cason, Carolyn L

    2009-04-01

    Adequate training in cardiopulmonary resuscitation (CPR) and use of an automated external defibrillator (AED) is an important component of a workplace safety training program. Barriers to traditional in-classroom CPR-AED training programs include time away from work to complete training, logistics, learner discomfort over being in a classroom setting, and instructors who include information irrelevant to CPR. This study evaluated differences in CPR skills performance between employees who learned CPR using a self-directed learning (SDL) kit and employees who attended a traditional instructor-led course. The results suggest that the SDL kit yields learning outcomes comparable to those obtained with traditional instructor-led courses and is a more time-efficient tool for CPR-AED training. Furthermore, the SDL kit overcomes many of the barriers that keep individuals from learning CPR and appears to contribute to bystanders' confidently attempting resuscitation.

  7. The effect of self-directed learning abilities of student nurses on success in Turkey.

    PubMed

    Avdal, Elif Ünsal

    2013-08-01

    SDL-self-directed learning is a learning method used increasingly in adult education. This study was carried out as an instructive effort to examine the effects of SDL on the success of students from nursing school. The sample of this study was composed of 220 students attending in Nursing School of Dokuz Eyül University during the fall semester of 2006. SDL scale including 40 questions was used to obtain the data. Kocaman et al. verified and validated the reliability of scale in Turkey. The data was evaluated by using Pearson correlation analysis. As a result of research, a positive meaningful average relation was found between the points of SDL and success of the students. (p<0.01, r: .60).

  8. Hollow Superparamagnetic Microballoons from Lifelike, Self-Directed Pickering Emulsions Based on Patchy Nanoparticles.

    PubMed

    Granath, Tim; Sanchez-Sanchez, Angela; Shmeliov, Aleksey; Nicolosi, Valeria; Fierro, Vanessa; Celzard, Alain; Mandel, Karl

    2016-11-22

    Herein, the formation of hollow microballoons derived from superparamagnetic iron oxide nanoparticles with silica patches is reported. Depending on the experimental conditions, single- or multishelled superparamagnetic microballoons as well as multivesicular structures were obtained. We show how such structural changes follow a lifelike process that is based on self-directing Pickering emulsions. We further demonstrate that the key toward the formation of such complex architectures is the patchy nature of the nanoparticles. Interestingly, no well-defined ordering of patches on the particles surface is required, unlike what theorists formerly predicted. The resultant hollow microballoons may be turned into hollow carbonaceous magnetic microspheres by simple pyrolysis. This opens the way to additional potential applications for such ultralightweight (density: 0.16 g·cm(-3)) materials.

  9. The development and structure of thick-walled, multicellular, aerial spores in Diheterospora chlamydosporia (=Verticillium chlamydosporium).

    PubMed

    Cambell, W P; Griffiths, D A

    1975-07-01

    The aerial, thick-walled spores in Diheterospara chlamydosporia arose as terminal swellings on erect hyphae. Repeated septation of the continuously swelling spore resulted in a multicellular structure. Immediately after the onset of septation secondary wall material was laid down between the two-layered primary wall and the plasmalemma. The presence of secondary wall material indicates that the multicellular spore is a dictyochlamydospore and not an aleuriospore. The relationship between chlamydospores and aleuriospores in other fungi is discussed.

  10. Study guides: effective tools to improve self-directed learning skills of medical students.

    PubMed

    Khabaz Mafinejad, Mahboobeh; Aghili, Rokhsareh; Emami, Zahra; Malek, Mojtaba; Baradaran, Hamidreza; Taghavinia, Mansoureh; Khamseh, Mohammad E

    2014-01-01

    In medicine, there is a rapid development of a knowledge base. Medical professionals need to sustain and advance their competence to practice in response to these varieties. So, there is increased interest in self-directed learning methods. Study guides can make a major contribution to self-directed learning. This study was carried out to evaluate the effect of study guides on improving self-learning skills of medical students in the Iran University of Medical Sciences (IUMS). In this quasi-experimental study, 46 medical students were randomly assigned into two groups; the intervention group and the control group. Both groups participated in a diagnostic test at the beginning of the course (pre-test). The same test was taken at the end of the course (post-test). The intervention group was provided with study guides on thyroid disorders and diabetes. Meanwhile, they continued their routine clinical training. The control group was only involved in the conventional training program. Students in the intervention group were also asked to complete a designed questionnaire in regard to their attitude toward the study guides. At enrollment, there was no statistically significant difference between the two groups. The mean scores of the pre-test for the control group and the intervention group were 6.18 and 6.13 respectively (P=0.9). In the post-test, the mean score of the students in the intervention group was considerably higher: 9.25 vs. 12 (P=0.002). The students in the intervention group found the study guides useful. The study guides were potentially effective in motivating self-learning in this group of medical students and had a remarkable effect on their final score.

  11. Changes in self-directed learning readiness in dental students: a mixed-methods study.

    PubMed

    Premkumar, Kalyani; Pahwa, Punam; Banerjee, Ankona; Baptiste, Kellen; Bhatt, Hitesh; Lim, Hyun J

    2014-06-01

    The purpose of this study was to identify changes in dental students' self-directed learning (SDL) readiness during their education. Guglielmino's SDL readiness scale (SDLRS) was completed at admission by dental students at the University of Saskatchewan and at the end of each year of training. The response rates varied from year to year. Between twenty-seven and thirty students completed the questionnaire each year at admission (93-100 percent of the entering class). The numbers of participants were lower in succeeding years: numbers used for analysis ranged from eleven to twenty-six; years in which fewer than eleven students participated were not included in the analysis. At admission, the students' mean SDLRS score was 228.98 (on a scale from 58 to 290, with 290 the highest); this score was higher than that of the average adult population (214±25.59). There was no significant effect of years of predental education, prior unsuccessful applications to dental school, interview scores, age, or admission test scores. There was a significant drop in SDLRS scores at the end of the first year for most of the cohorts (p<0.001). In addition to the questionnaire part of the study, two instructors and five first- and second-year students participated in focus groups. Those results showed that the individuals defined SDL narrowly and had similar perceptions of curricular factors that affect SDL readiness. The drop in scores one year after admission and lack of change with increased training suggests that current educational interventions may require re-examination and alteration to those that promote self-direction.

  12. Educational strategies associated with development of problem-solving, critical thinking, and self-directed learning.

    PubMed

    Hendricson, William D; Andrieu, Sandra C; Chadwick, D Gregory; Chmar, Jacqueline E; Cole, James R; George, Mary C; Glickman, Gerald N; Glover, Joel F; Goldberg, Jerold S; Haden, N Karl; Meyerowitz, Cyril; Neumann, Laura; Pyle, Marsha; Tedesco, Lisa A; Valachovic, Richard W; Weaver, Richard G; Winder, Ronald L; Young, Stephen K; Kalkwarf, Kenneth L

    2006-09-01

    This article was developed for the Commission on Change and Innovation in Dental Education (CCI), established by the American Dental Education Association. CCI was created because numerous organizations within organized dentistry and the educational community have initiated studies or proposed modifications to the process of dental education, often working to achieve positive and desirable goals but without coordination or communication. The fundamental mission of CCI is to serve as a focal meeting place where dental educators and administrators, representatives from organized dentistry, the dental licensure community, the Commission on Dental Accreditation, the ADA Council on Dental Education and Licensure, and the Joint Commission on National Dental Examinations can meet and coordinate efforts to improve dental education and the nation's oral health. One of the objectives of the CCI is to provide guidance to dental schools related to curriculum design. In pursuit of that objective, this article summarizes the evidence related to this question: What are educational best practices for helping dental students acquire the capacity to function as an entry-level general dentist or to be a better candidate to begin advanced studies? Three issues are addressed, with special emphasis on the third: 1) What constitutes expertise, and when does an individual become an expert? 2) What are the differences between novice and expert thinking? and 3) What educational best practices can help our students acquire mental capacities associated with expert function, including critical thinking and self-directed learning? The purpose of this review is to provide a benchmark that faculty and academic planners can use to assess the degree to which their curricula include learning experiences associated with development of problem-solving, critical thinking, self-directed learning, and other cognitive skills necessary for dental school graduates to ultimately become expert performers as

  13. Self-directed Mindfulness Training and Improvement in Blood Pressure, Migraine Frequency, and Quality of Life

    PubMed Central

    Rempe, Margaret; Bradley, Ryan

    2013-01-01

    Background: Interest in case studies has undergone a resurgence concurrent with increasing prioritization of illustrations of patient-centered care. However, substantial inclusion of the patient in these reports remains limited. Here, a doctor and patient collaborate to present her case report of self-directed mindfulness training and the subsequent changes in blood pressure, migraine frequency, and quality of life. Methods: After receiving encouragement from her naturopathic doctor, the patient initiated an 8-week program in mindfulness training following the Kabat-Zinn protocol and logged her daily blood pressure and symptoms before and after meditation sessions over an 11-week period. Results: Patient-reported outcomes included decreased perceived stress, increased focus, and a newfound sense of centeredness and calm. Changes in objective outcomes were clinically and statistically significant, including reductions in mean systolic and diastolic blood pressure between week 1 and week 11 (P = .0001 and P = .0004 for systolic and diastolic, respectively, by paired, 2-sided t-tests). Self-reported frequency of chronic migraine was also reduced. Critical to the patient's success was that mindfulness training was first approached in a simple, accessible manner prior to embarking on a deeper, extended experience. Discussion and Conclusion: Self-directed mindfulness training can have a meaningful impact on both subjective and objective health outcomes. It may take years of encouragement from a healthcare provider before a patient is ready to adopt a mind-body practice; it is important to recognize and counsel patients with messages appropriate to their stage of change and self-efficacy. Additionally, case studies that combine the voice of the clinician and the patient can provide useful illustrations of truly patient-centered care. PMID:24278842

  14. Medical student preferences for self-directed study resources in gross anatomy.

    PubMed

    Choi-Lundberg, Derek L; Low, Tze Feng; Patman, Phillip; Turner, Paul; Sinha, Sankar N

    2016-01-01

    Gross anatomy instruction in medical curricula involve a range of resources and activities including dissection, prosected specimens, anatomical models, radiological images, surface anatomy, textbooks, atlases, and computer-assisted learning (CAL). These resources and activities are underpinned by the expectation that students will actively engage in self-directed study (SDS) to enhance their knowledge and understanding of anatomy. To gain insight into preclinical versus clinical medical students' preferences for SDS resources for learning gross anatomy, and whether these vary on demographic characteristics and attitudes toward anatomy, students were surveyed at two Australian medical schools, one undergraduate-entry and the other graduate-entry. Lecture/tutorial/practical notes were ranked first by 33% of 156 respondents (mean rank ± SD, 2.48 ± 1.38), textbooks by 26% (2.62 ± 1.35), atlases 20% (2.80 ± 1.44), videos 10% (4.34 ± 1.68), software 5% (4.78 ± 1.50), and websites 4% (4.24 ± 1.34). Among CAL resources, Wikipedia was ranked highest. The most important factor in selecting CAL resources was cost (ranked first by 46%), followed by self-assessment, ease of use, alignment with curriculum, and excellent graphics (each 6-9%). Compared with preclinical students, clinical students ranked software and Acland's Video Atlas of Human Anatomy higher and felt radiological images were more important in selecting CAL resources. Along with other studies reporting on the quality, features, and impact on learning of CAL resources, the diversity of students' preferences and opinions on usefulness and ease of use reported here can help guide faculty in selecting and recommending a range of CAL and other resources to their students to support their self-directed study.

  15. Evolution of multicellularity coincided with increased diversification of cyanobacteria and the Great Oxidation Event

    PubMed Central

    Schirrmeister, Bettina E.; de Vos, Jurriaan M.; Antonelli, Alexandre; Bagheri, Homayoun C.

    2013-01-01

    Cyanobacteria are among the most diverse prokaryotic phyla, with morphotypes ranging from unicellular to multicellular filamentous forms, including those able to terminally (i.e., irreversibly) differentiate in form and function. It has been suggested that cyanobacteria raised oxygen levels in the atmosphere around 2.45–2.32 billion y ago during the Great Oxidation Event (GOE), hence dramatically changing life on the planet. However, little is known about the temporal evolution of cyanobacterial lineages, and possible interplay between the origin of multicellularity, diversification of cyanobacteria, and the rise of atmospheric oxygen. We estimated divergence times of extant cyanobacterial lineages under Bayesian relaxed clocks for a dataset of 16S rRNA sequences representing the entire known diversity of this phylum. We tested whether the evolution of multicellularity overlaps with the GOE, and whether multicellularity is associated with significant shifts in diversification rates in cyanobacteria. Our results indicate an origin of cyanobacteria before the rise of atmospheric oxygen. The evolution of multicellular forms coincides with the onset of the GOE and an increase in diversification rates. These results suggest that multicellularity could have played a key role in triggering cyanobacterial evolution around the GOE. PMID:23319632

  16. Symbiotic Cell Differentiation and Cooperative Growth in Multicellular Aggregates

    PubMed Central

    Yamagishi, Jumpei F; Saito, Nen; Kaneko, Kunihiko

    2016-01-01

    As cells grow and divide under a given environment, they become crowded and resources are limited, as seen in bacterial biofilms and multicellular aggregates. These cells often show strong interactions through exchanging chemicals, as evident in quorum sensing, to achieve mutualism and division of labor. Here, to achieve stable division of labor, three characteristics are required. First, isogenous cells differentiate into several types. Second, this aggregate of distinct cell types shows better growth than that of isolated cells without interaction and differentiation, by achieving division of labor. Third, this cell aggregate is robust with respect to the number distribution of differentiated cell types. Indeed, theoretical studies have thus far considered how such cooperation is achieved when the ability of cell differentiation is presumed. Here, we address how cells acquire the ability of cell differentiation and division of labor simultaneously, which is also connected with the robustness of a cell society. For this purpose, we developed a dynamical-systems model of cells consisting of chemical components with intracellular catalytic reaction dynamics. The reactions convert external nutrients into internal components for cellular growth, and the divided cells interact through chemical diffusion. We found that cells sharing an identical catalytic network spontaneously differentiate via induction from cell-cell interactions, and then achieve division of labor, enabling a higher growth rate than that in the unicellular case. This symbiotic differentiation emerged for a class of reaction networks under the condition of nutrient limitation and strong cell-cell interactions. Then, robustness in the cell type distribution was achieved, while instability of collective growth could emerge even among the cooperative cells when the internal reserves of products were dominant. The present mechanism is simple and general as a natural consequence of interacting cells with

  17. Spatial self-organization in hybrid models of multicellular adhesion

    NASA Astrophysics Data System (ADS)

    Bonforti, Adriano; Duran-Nebreda, Salva; Montañez, Raúl; Solé, Ricard

    2016-10-01

    Spatial self-organization emerges in distributed systems exhibiting local interactions when nonlinearities and the appropriate propagation of signals are at work. These kinds of phenomena can be modeled with different frameworks, typically cellular automata or reaction-diffusion systems. A different class of dynamical processes involves the correlated movement of agents over space, which can be mediated through chemotactic movement or minimization of cell-cell interaction energy. A classic example of the latter is given by the formation of spatially segregated assemblies when cells display differential adhesion. Here, we consider a new class of dynamical models, involving cell adhesion among two stochastically exchangeable cell states as a minimal model capable of exhibiting well-defined, ordered spatial patterns. Our results suggest that a whole space of pattern-forming rules is hosted by the combination of physical differential adhesion and the value of probabilities modulating cell phenotypic switching, showing that Turing-like patterns can be obtained without resorting to reaction-diffusion processes. If the model is expanded allowing cells to proliferate and die in an environment where diffusible nutrient and toxic waste are at play, different phases are observed, characterized by regularly spaced patterns. The analysis of the parameter space reveals that certain phases reach higher population levels than other modes of organization. A detailed exploration of the mean-field theory is also presented. Finally, we let populations of cells with different adhesion matrices compete for reproduction, showing that, in our model, structural organization can improve the fitness of a given cell population. The implications of these results for ecological and evolutionary models of pattern formation and the emergence of multicellularity are outlined.

  18. Spatial self-organization in hybrid models of multicellular adhesion.

    PubMed

    Bonforti, Adriano; Duran-Nebreda, Salva; Montañez, Raúl; Solé, Ricard

    2016-10-01

    Spatial self-organization emerges in distributed systems exhibiting local interactions when nonlinearities and the appropriate propagation of signals are at work. These kinds of phenomena can be modeled with different frameworks, typically cellular automata or reaction-diffusion systems. A different class of dynamical processes involves the correlated movement of agents over space, which can be mediated through chemotactic movement or minimization of cell-cell interaction energy. A classic example of the latter is given by the formation of spatially segregated assemblies when cells display differential adhesion. Here, we consider a new class of dynamical models, involving cell adhesion among two stochastically exchangeable cell states as a minimal model capable of exhibiting well-defined, ordered spatial patterns. Our results suggest that a whole space of pattern-forming rules is hosted by the combination of physical differential adhesion and the value of probabilities modulating cell phenotypic switching, showing that Turing-like patterns can be obtained without resorting to reaction-diffusion processes. If the model is expanded allowing cells to proliferate and die in an environment where diffusible nutrient and toxic waste are at play, different phases are observed, characterized by regularly spaced patterns. The analysis of the parameter space reveals that certain phases reach higher population levels than other modes of organization. A detailed exploration of the mean-field theory is also presented. Finally, we let populations of cells with different adhesion matrices compete for reproduction, showing that, in our model, structural organization can improve the fitness of a given cell population. The implications of these results for ecological and evolutionary models of pattern formation and the emergence of multicellularity are outlined.

  19. Evaluation of interstitial protein delivery in multicellular layers model.

    PubMed

    Kim, Soo-Yeon; Kim, Tae Hyung; Choi, Jong Hoon; Lee, Kang Choon; Park, Ki Dong; Lee, Seung-Jin; Kuh, Hyo-Jeong

    2012-03-01

    The limited efficacy of anticancer protein drugs is related to their poor distribution in tumor tissue. We examined interstitial delivery of four model proteins of different molecular size and bioaffinity in multicellular layers (MCL) of human cancer cells. Model proteins were tumor necrosis factor-related apoptosis-including ligand (TRAIL), cetuximab, RNase A, and IgG. MCLs were cultured in Transwell inserts, exposed to drugs, then cryo-sectioned for image acquisition using fluorescence microscopy (fluorescent dye-labeled TRAIL, RNase A, IgG) or immunohistochemistry (cetuximab). TRAIL and cetuximab showed partial penetration into MCLs, whereas RNase A and IgG showed insignificant penetration. At 10-fold higher dose, a significant increase in penetration was observed for IgG only, while cetuximab showed an intense accumulation limited to the front layers. PEGylated TRAIL and RNase A formulated in a heparin-Pluronic (HP) nanogel showed significantly improved penetration attributable to increased stability and extracellular matrix binding, respectively. IgG penetration was significantly enhanced with paclitaxel pretreatment as a penetration enhancer. The present study suggests that MCL culture may be useful in evaluation of protein delivery in the tumor interstitium. Four model proteins showed limited interstitial penetration in MCL cultures. Bioaffinity, rather than molecular size, seems to have a positive effect on tissue penetration, although high binding affinity may lead to sequestration in the front cell layers. Polymer conjugation and nanoformulation, such as PEGylation and HP nanogel, or use of penetration enhancers are potential strategies to increase interstitial delivery of anticancer protein drugs.

  20. Point of care information services: a platform for self-directed continuing medical education for front line decision makers

    PubMed Central

    Moja, Lorenzo; Kwag, Koren Hyogene

    2015-01-01

    The structure and aim of continuing medical education (CME) is shifting from the passive transmission of knowledge to a competency-based model focused on professional development. Self-directed learning is emerging as the foremost educational method for advancing competency-based CME. In a field marked by the constant expansion of knowledge, self-directed learning allows physicians to tailor their learning strategy to meet the information needs of practice. Point of care information services are innovative tools that provide health professionals with digested evidence at the front line to guide decision making. By mobilising self-directing learning to meet the information needs of clinicians at the bedside, point of care information services represent a promising platform for competency-based CME. Several points, however, must be considered to enhance the accessibility and development of these tools to improve competency-based CME and the quality of care. PMID:25655251

  1. Self-Reported Usual Care for Self-Directed Violence during the Six Months Prior to Emergency Department Admission

    PubMed Central

    Comtois, Katherine Anne; Kerbrat, Amanda H.; Atkins, David C.; Roy-Byrne, Peter; Katon, Wayne J.

    2014-01-01

    Background The literature describing the health services individuals receive prior to and following self-directed violence is limited. Objectives This study examines services received for the six months preceding admission to an urban county medical center emergency department for self-directed violence. We predicted that individuals with at least one prior act of self-directed violence in the past six months would have received more services than those for whom the index admission was their only recent act. Method Participants were recruited from emergency department admissions during shifts selected to maximize representativeness. Participants (n=202) were interviewed using the Suicide Attempt Self-Injury Interview, Suicide Attempt Self-Injury Count, Treatment History Interview, MINI, Brief Symptom Index, and SF-12. Results The majority of index acts of self-directed violence (79%) were suicide attempts. The participants were characterized by low socio-economic status, substantial symptomatology, low physical and mental health functioning, and multiple psychiatric diagnoses. In the preceding six months, 34% were admitted to a hospital and 56% received crisis services (including 44% in the ED). While three quarters (76%) had seen an outpatient medical provider and most (70%) received psychotropic medications, less than half of the sample received psychiatric services (40%) or outpatient psychosocial treatment (48%). As predicted, utilization for most types of usual care was higher for those engaging in self-directed violence in the six months preceding the index admission. Conclusions Individuals admitted to this emergency department for self-directed violence received inadequate outpatient psychosocial and psychiatric services despite severe illness and disability. PMID:25494233

  2. Proliferation and motility of HaCaT keratinocyte derivatives is enhanced by fibroblast nemosis

    SciTech Connect

    Raesaenen, Kati; Vaheri, Antti

    2010-06-10

    The role of paracrine tumor-stroma regulation in the progression of cancer is under intense investigation. Activated fibroblasts are key components of the tumor microenvironment providing the soluble factors mediating the regulation. Nemosis is an experimental model to study these parameters: formation of a multicellular spheroid activates fibroblasts and leads to increased production of soluble factors involved in the promotion of growth and motility. Role of nemosis was investigated in the tumorigenesis of HaCaT derivatives representing skin carcinoma progression. Conditioned medium from fibroblast spheroids increased proliferation rate of HaCaT derivatives. Expression of proliferation marker Ki-67 increased significantly in benign A5 and low-grade malignant II-4 cells, but did not further increase in the metastatic RT3 cells. Expression of p63, keratinocyte stem cell marker linked to cancer progression, was augmented by medium from nemotic fibroblasts; this increase was also seen in RT3 cells. Scratch-wound healing of the keratinocytes was enhanced in response to fibroblast nemosis. Neutralizing antibodies against growth factors inhibited wound healing to some extent; the response varied between benign and malignant keratinocytes. Migration and invasion were enhanced by conditioned medium from nemotic fibroblasts in benign and low-grade malignant cells. RT3 keratinocyte migration was further augmented, but invasion was not, indicating their intrinsic capacity to invade. Our data demonstrate that fibroblast nemosis increases proliferation and motility of HaCaT keratinocyte derivatives, and thus nemosis can be used as a model to study the role of soluble factors secreted by fibroblasts in tumor progression.

  3. Spreading and spontaneous motility of multicellular aggregates on soft substrates

    NASA Astrophysics Data System (ADS)

    Brochard-Wyart, Françoise

    2013-03-01

    We first describe the biomechanics of multicellular aggregates, a model system for tissues and tumors. We first characterize the tissue mechanical properties (surface tension, elasticity, viscosity) by a new pipette aspiration technique. The aggregate exhibits a viscoelastic response but, unlike an inert fluid, we observe aggregate reinforcement with pressure, which for a narrow range of pressures results in pulsed contractions or shivering. We interpret this reinforcement as a mechanosensitive active response of the acto-myosin cortex. Such an active behavior has previously been found to cause tissue pulsation during dorsal closure of Drosophila embryo. We then describe the spreading of aggregates on rigid glass substrates, varying both intercellular and substrate adhesion. We find both partial and complete wetting regimes. For the dynamics, we find a universal spreading law at short time, analogous to that of a viscoelastic drop. At long time, we observe, for strong substrate adhesion, a precursor film spreading around the aggregate. Depending on aggregate cohesion, this precursor film can be a dense cellular monolayer (liquid state) or consist of individual cells escaping from the aggregate body (gas state). The transition from liquid to gas state appears also to be present in the progression of a tumor from noninvasive to metastatic, known as the epithelial-mesenchymal transition. Finally, we describe the effect of the substrate rigidity on the phase diagram of wetting. On soft gels decorated with fibronectin and strongly cohesive aggregates, we have observed a wetting transition induced by the substrate rigidity: on ultra soft gels, below an elastic modulus Ec the aggregates do not spread, whereas above Ec we observe a precursor film expending with a diffusive law. The diffusion coefficient D(E) present a maximum for E =Em. A maximum of mobility versus the substrate rigidity had also been observed for single cells. Near Em, we observe a new phenomenon: a cell

  4. A method of self-directed learning in continuing medical education with implications for recertification.

    PubMed

    Manning, P R; Clintworth, W A; Sinopoli, L M; Taylor, J P; Krochalk, P C; Gilman, N J; Denson, T A; Stufflebeam, D L; Knowles, M S

    1987-12-01

    A method of self-directed learning for physicians that can be used to satisfy a portion of specialty board recertification requirements integrates contract learning (self-formulated learning plans), information brokering (linking physicians with consultants and community resources), and collegial networking (discussion groups). The method encourages physicians to focus on educational objectives, supplies learning resources, and promotes interactions with colleagues in study groups. Fifty-nine (53%) of the 102 learning goals update physicians' knowledge. Print sources and discussions with experts were the commonest resources used. Forty-five (49%) of 91 participants completed their learning plans. Forty-nine (74%) completed projects were judged successful in achieving their goals. Twenty-five (45%) of 56 physicians responding to a questionnaire stated that the method was superior to traditional continuing medical education. Fifty-two percent of the participants found the method as effective as traditional continuing medical education. Proof of accomplishment allows the method to be used as part of a specialty board recertification process.

  5. The relative influence of different domains of social connectedness on self-directed violence in adolescence.

    PubMed

    Kaminski, Jennifer W; Puddy, Richard W; Hall, Diane M; Cashman, Sandra Y; Crosby, Alexander E; Ortega, Lavonne A G

    2010-05-01

    Previous research has linked greater social connectedness with a lowered risk of self-directed violence among adolescents. However, few studies have analyzed the comparative strength of different domains of connectedness (e.g., family, peers and school) to determine where limited resources might best be focused. Data to address that gap were taken from the Centers for Disease Control and Prevention's Student Health and Safety Survey, administered to 4,131 7th-12th graders (51.5% female; 43.8% Hispanic; 22.6% African American or Black). Logistic regressions (controlling for age, gender, race/ethnicity, family structure, academic performance, and depressive symptoms) suggest that family connectedness was a stronger predictor than connectedness to peers, school, or adults at school for non-suicidal self-harm, suicidal ideation, suicide plans, and non-fatal suicidal behavior. In some analyses, peer connectedness was unexpectedly a risk factor. Results have implications for prevention of suicide in adolescence, especially in the context of the current trend towards school-based prevention programs.

  6. A general allometric and life-history model for cellular differentiation in the transition to multicellularity.

    PubMed

    Solari, Cristian A; Kessler, John O; Goldstein, Raymond E

    2013-03-01

    The transition from unicellular, to colonial, to larger multicellular organisms has benefits, costs, and requirements. Here we present a model inspired by the volvocine green algae that explains the dynamics involved in the unicellular-multicellular transition using life-history theory and allometry. We model the two fitness components (fecundity and viability) and compare the fitness of hypothetical colonies of different sizes with varying degrees of cellular differentiation to understand the general principles that underlie the evolution of multicellularity. We argue that germ-soma separation may have evolved to counteract the increasing costs and requirements of larger multicellular colonies. The model shows that the cost of investing in soma decreases with size. For lineages such as the Volvocales, as reproduction costs increase with size for undifferentiated colonies, soma specialization benefits the colony indirectly by decreasing such costs and directly by helping reproductive cells acquire resources for their metabolic needs. Germ specialization is favored once soma evolves and takes care of vegetative functions. To illustrate the model, we use some allometric relationships measured in Volvocales. Our analysis shows that the cost of reproducing an increasingly larger group has likely played an important role in the transition to multicellularity and cellular differentiation.

  7. Students' Perceptions of Success in the Online Graduate-Level Classes: A Self-Directed Learning Perspective

    ERIC Educational Resources Information Center

    Chou, Pao-Nan

    2013-01-01

    The purpose of this study is to examine the phenomenon of successful online learning, defined as a higher academic performance (A or 90) and to find if there is the evidence to confirm the role of self-directed learning in the online graduate-level courses. A qualitative method was used to analyze learners' perceptions of online learning…

  8. Comparing the Chinese Career Key and the Self-Directed Search with High School Girls in Hong Kong

    ERIC Educational Resources Information Center

    Ting, Siu-Man Raymond

    2007-01-01

    A career interest inventory, the Chinese Career Key (CCK) adapted from the Career Key based on Holland's theory of vocational choice, was studied. The purpose of the study was to further examine the psychometric qualities and user satisfaction of the CCK by comparing it to the Self-Directed Search. Students at a girls' public high school (N = 130)…

  9. Practice-Based Research on the Development of Activating Instruction and Self-Directed Student Learning: Dutch Writing Instruction

    ERIC Educational Resources Information Center

    Imants, Jeroen; van de Ven, Piet-Hein

    2011-01-01

    A team of secondary school language teachers and a teacher trainer developed a new method for Dutch writing instruction. The principles underlying the method were derived from insights regarding activating instruction and self-directed student learning. The development entailed two phases. In the first phase, the exploration of actual problems in…

  10. Self-Perceived and Observable Self-Direction in an Online Asynchronous Programming Course Using Peer Learning Forums

    ERIC Educational Resources Information Center

    Gaspar, Alessio; Langevin, Sarah; Boyer, Naomi; Armitage, William

    2009-01-01

    This study broadens the objectives of previous work (Boyer, N., Langevin, S., Gaspar, A. (2008). "Self direction and constructivism in programming education." "Proceedings of the ACM Special Interest Group in IT Education Conference," 16-18 October 2008, Cincinnati, OH) in which we used a survey-based instrument, the Personal…

  11. The Self-Directed Violence Classification System and the Columbia Classification Algorithm for Suicide Assessment: A Crosswalk

    ERIC Educational Resources Information Center

    Matarazzo, Bridget B.; Clemans, Tracy A.; Silverman, Morton M.; Brenner, Lisa A.

    2013-01-01

    The lack of a standardized nomenclature for suicide-related thoughts and behaviors prompted the Centers for Disease Control and Prevention, with the Veterans Integrated Service Network 19 Mental Illness Research Education and Clinical Center, to create the Self-Directed Violence Classification System (SDVCS). SDVCS has been adopted by the…

  12. Self-Directed Support: Impact of Hiring Practices on Adults with Intellectual and Developmental Disabilities and Families

    ERIC Educational Resources Information Center

    Heller, Tamar; Arnold, Catherine K.; van Heumen, Lieke; McBride, Elizabeth L.; Factor, Alan

    2012-01-01

    The study examined the differential experiences and outcomes for people with intellectual and developmental disabilities and their families receiving self-directed services based on the type of personal support worker hired (parents, siblings, other relatives, friends, and agency staff). The sample consisted of 372 participants in a self-directed…

  13. Enhancing Learners' Self-Directed Use of Technology for Language Learning: The Effectiveness of an Online Training Platform

    ERIC Educational Resources Information Center

    Lai, Chun; Shum, Mark; Tian, Yan

    2016-01-01

    Enhancing self-directed use of technology for language learning is essential for maximizing the potential of technology for language learning. Understanding how to construct learner training to promote this critical competency is of great significance. This study examined the effectiveness of an online training platform aimed at enhancing the…

  14. Handbook Preparation as a Tool for Self-Directed Learning Process: A Case Study on Endocrine Topic

    ERIC Educational Resources Information Center

    Cerrah Ozsevgec, Lale; Ayas, Alipasa; Ozsevgec, Tuncay

    2010-01-01

    This study examines the effectiveness of handbook preparation as a method in the self-directed learning process of student teachers in teaching endocrine glands, and increasing their levels of knowledge. Thirty student teachers were selected from a biology department. A pencil and paper test and a clinical interview procedure were used to collect…

  15. It Takes Two to Tango: In Dynamic Inquiry, the Self-Directed Student Acts in Association with the Facilitating Teacher

    ERIC Educational Resources Information Center

    Zion, M.; Slezak, M.

    2005-01-01

    The current research presents a qualitative view of a teacher-student association within the context of dynamic inquiry, as encouraged by a new biology curriculum, ''Biomind''. This curriculum enables open inquiry learning through teacher guidance. We characterized the various aspects of the student's functioning as a self-directed student during…

  16. A Correlational Study of Self-Directed Learning Readiness and Learning Activity Preference for Continuing Medical Education among Family Physicians

    ERIC Educational Resources Information Center

    Barrett, Theresa J.

    2014-01-01

    This quantitative, nonexperimental, correlational study sought to determine whether a relationship exists between family physicians' levels of self-directed learning readiness (SDLR) and their preferences for continuing medical education (CME) activities. The study also sought to determine whether years in clinical practice or size of clinical…

  17. Relationship between Student's Self-Directed-Learning Readiness and Academic Self-Efficacy and Achievement Motivation in Students

    ERIC Educational Resources Information Center

    Saeid, Nasim; Eslaminejad, Tahere

    2017-01-01

    Self-directed learning readiness to expand and enhance learning, This is an important goal of higher education, Besides his academic self-efficacy can be improved efficiency and Achievement Motivation, so understanding how to use these strategies by students is very important. Because the purpose this study is determination of relationship between…

  18. Paraprofessionals' Perceptions on Delivering Infant Feeding Lessons to Disadvantaged Mothers via a Self-Directed Computer-Supported Method

    ERIC Educational Resources Information Center

    Singleterry, Lisa R.; Horodynski, Mildred A.

    2012-01-01

    Objective: To ascertain paraprofessionals' perceptions regarding a self-directed computer-supported nutrition educational intervention to disadvantaged mothers of infants. Design: Qualitative focus group study. Setting: Three county extension programs in a Midwestern state, which serve disadvantaged families. Method: Sixteen paraprofessional…

  19. Exploratory Study of the Relationship between Self-Directed Learning and Academic Performance in a Web-Based Learning Environment

    ERIC Educational Resources Information Center

    Chou, Pao-Nan; Chen, Wei-Fan

    2008-01-01

    Through literature review, this paper examines six empirical studies. Three cases are from the United States and the other three are from studies conducted in Asian. The purpose of this study is to identify whether or not self-directed learning is a key factor leading to successful academic performance in web-based learning environments. The…

  20. Effect of Instructor-Provided Concept Maps and Self-Directed Learning Ability on Students' Online Hypermedia Learning Performance

    ERIC Educational Resources Information Center

    Chou, Pao-Nan

    2013-01-01

    The purpose of this experimental study was to explore the instructional effectiveness of integrating varied instructor-provided concept maps into an online hypertext learning environment, and the effect of learners' self-directed learning abilities on their learning performance. The research adopted a randomized posttest with two-control-group…

  1. Effects of Project-Based Learning Strategy on Self-Directed Learning Skills of Educational Technology Students

    ERIC Educational Resources Information Center

    Bagheri, Mohsen; Ali, Wan Zah Wan; Abdullah, Maria Chong Binti; Daud, Shaffe Mohd

    2013-01-01

    Given the importance of globalization as well as the need to train skilled and knowledgeable employees for the 21st century workforce, higher education needs to take a more critical look at the educational practices and instructional methods which lead to improvements in students' essential skills such as self-directed learning. This study sought…

  2. Design Lessons about Participatory Self-Directed Online Learning in a Graduate-Level Instructional Technology Course

    ERIC Educational Resources Information Center

    Yamagata-Lynch, Lisa C.; Do, Jaewoo; Skutnik, Anne L.; Thompson, Duren J.; Stephens, Adam F.; Tays, Cheryl A.

    2015-01-01

    This article reports on a case of participatory self-directed online learning within the context of a graduate-level instructional technology course. The course was about online learning environments and relied on both asynchronous and synchronous technologies. In this case, the instructor and students engaged in collaborative course design…

  3. Developing a "Self-Directed Learning Preparation Skills Scale for Primary School Students": Validity and Reliability Analyses

    ERIC Educational Resources Information Center

    Gündüz, Gülten Feryal; Selvi, Kiymet

    2016-01-01

    The purpose of this study is to develop "Self-Directed Learning Preparation Skills Scale" for primary school students. Data were gathered according to the principles of descriptive research method. In order to develop this scale, draft items were developed through review of literature, interviews done with teachers, parents and students…

  4. Kanji Learning Attitudes and Self-Directed Learning by Learners of Japanese as a Foreign Language: A Case Study

    ERIC Educational Resources Information Center

    Gamage, Gayathri Haththotuwa

    2011-01-01

    This longitudinal qualitative study investigates how cultural experiences of staying in Japan may affect attitudes and self-directed learning of kanji among learners of Japanese as a foreign language. Six beginner learners pursued semester-long weekly kanji learning sessions and their diachronic behaviours were observed and recorded for attitudes…

  5. The Relationships of Learning Style Balance and Learning Dimensions to Self-Directed Learning Propensity among Adult Learners

    ERIC Educational Resources Information Center

    Hutto, Sarah Tullos

    2009-01-01

    The purpose of this study was to examine the relationships of learning style characteristics to self-directed learning propensity among adult learners. The learning style characteristics investigated were learning style balance as measured by a scoring method developed by Mainemelis, Boyatzis, and Kolb (2002) and learning style dimensions as…

  6. Interest Profile Elevation, Big Five Personality Traits, and Secondary Constructs on the Self-Directed Search: A Replication and Extension

    ERIC Educational Resources Information Center

    Bullock, Emily E.; Reardon, Robert C.

    2008-01-01

    The study used the Self-Directed Search (SDS) and the NEO-FFI to explore profile elevation, four secondary constructs, and the Big Five personality factors in a sample of college students in a career course. Regression model results showed that openness, conscientiousness, differentiation high-low, differentiation Iachan, and consistency accounted…

  7. Self-Directed Learning with Web-Based Sites: How Well Do Students' Perceptions and Thinking Match with Their Teachers?

    ERIC Educational Resources Information Center

    Ng, Wan

    2008-01-01

    With research consistently showing that students can be motivated to learn with ICT, this case study sought to investigate Year 7 students' learning about simple machines in an ICT-enhanced environment where they could self-direct their own learning with minimal intervention from the teacher. The study is focused on how well do students and…

  8. The Pause Model: A Qualitative Method of Self-Directed Continuing Education for Professionals with Social Practices.

    ERIC Educational Resources Information Center

    Liebowitz, Steven E.

    This paper introduces the Pause Model, an innovative means of integrating self-directed learning and continuing professional education. Since the method was developed for professionals such as counselors, educators, and managers who practice in social settings, the paper begins with an explanation of a few of the unique attributes of professional…

  9. Using the Self-Directed Search in Research: Selecting a Representative Pool of Items to Measure Vocational Interests

    ERIC Educational Resources Information Center

    Poitras, Sarah-Caroline; Guay, Frederic; Ratelle, Catherine F.

    2012-01-01

    Using Item Response Theory (IRT) and Confirmatory Factor Analysis (CFA), the goal of this study was to select a reduced pool of items from the French Canadian version of the Self-Directed Search--Activities Section (Holland, Fritzsche, & Powell, 1994). Two studies were conducted. Results of Study 1, involving 727 French Canadian students,…

  10. The Learning Exchange Network: An Evolutionary Step in Providing Support for Self-Directed Learning. Part I.

    ERIC Educational Resources Information Center

    Perkins, Allan Thomas

    1985-01-01

    The Learning Exchange Network is explored to show how it (1) takes advantage of the strong points of the previous models for self-directed learners; (2) counters the liabilities of the previous models; (3) serves the smaller populations of semirural areas; and (4) includes an implementation plan. The practicality of the network is discussed. (CT)

  11. Gender as a Context for Interpreting the Self-Directed Learning Experiences of Prostate and Breast Cancer Patients

    ERIC Educational Resources Information Center

    Rager, Kathleen B.

    2007-01-01

    This article reports the findings from a secondary analysis of the data from two qualitative studies conducted by the researcher regarding the self-directed learning experiences of prostate and breast cancer patients. Of interest were possible differences in the descriptions of the participants' experiences that appear to relate to gender.…

  12. Development of Competency-Based Web Learning Material and Effect Evaluation of Self-Directed Learning Aptitudes on Learning Achievements

    ERIC Educational Resources Information Center

    Chang, Chi-Cheng

    2006-01-01

    This study aims to develop and evaluate competency-based web learning material (CBWLM) for the college practicum Microprocessor Laboratory. After using the CBWLM for 8 weeks, this study investigates CBWL's learning effects and self-directed learning aptitudes (SDLAs) as well as exploring the influence of SDLA on learning effects based on the…

  13. Enabling Self-Directed Computer Use for Individuals with Cerebral Palsy: A Systematic Review of Assistive Devices and Technologies

    ERIC Educational Resources Information Center

    Davies, T. Claire; Mudge, Suzie; Ameratunga, Shanthi; Stott, N. Susan

    2010-01-01

    Aim: The purpose of this study was to systematically review published evidence on the development, use, and effectiveness of devices and technologies that enable or enhance self-directed computer access by individuals with cerebral palsy (CP). Methods: Nine electronic databases were searched using keywords "computer", "software", "spastic",…

  14. Understanding the Self-Directed Online Learning Preferences, Goals, Achievements, and Challenges of MIT OpenCourseWare Subscribers

    ERIC Educational Resources Information Center

    Bonk, Curtis J.; Lee, Mimi Miyoung; Kou, Xiaojing; Xu, Shuya; Sheu, Feng-Ru

    2015-01-01

    This research targeted the learning preferences, goals and motivations, achievements, challenges, and possibilities for life change of self-directed online learners who subscribed to the monthly OpenCourseWare (OCW) e-newsletter from MIT. Data collection included a 25-item survey of 1,429 newsletter subscribers; 613 of whom also completed an…

  15. Designing On-Demand Education for Simultaneous Development of Domain-Specific and Self-Directed Learning Skills

    ERIC Educational Resources Information Center

    Taminiau, E. M. C.; Kester, L.; Corbalan, G.; Spector, J. M.; Kirschner, P. A.; Van Merriënboer, J. J. G.

    2015-01-01

    On-demand education enables individual learners to choose their learning pathways according to their own learning needs. They must use self-directed learning (SDL) skills involving self-assessment and task selection to determine appropriate pathways for learning. Learners who lack these skills must develop them because SDL skills are prerequisite…

  16. The Effects of Portfolio-Based Advice on the Development of Self-Directed Learning Skills in Secondary Vocational Education

    ERIC Educational Resources Information Center

    Kicken, Wendy; Brand-Gruwel, Saskia; van Merrienboer, Jeroen J. G.; Slot, Wim

    2009-01-01

    This experimental study was designed to investigate whether supervision meetings, in which students receive specific advice on how to use a development portfolio to monitor their progress and plan their future learning, helps them to develop self-directed learning skills and improve their learning in the domain. In the first year of a hairdressing…

  17. Diffusion of an e-Portfolio to Assist in the Self-Directed Learning of Physicians: An Exploratory Study

    ERIC Educational Resources Information Center

    Goliath, Cheryl Lynn

    2009-01-01

    Professional societies in the field of medicine have recommended that the traditional model for lifelong medical learning, which had previously focused on attendance at weeklong didactic continuing medical education (CME) courses, should be replaced by individualized study. Self-directed and practice-linked learning are well accepted in principle,…

  18. Transformation for Adults in an Internet-Based Learning Environment--Is It Necessary to Be Self-Directed?

    ERIC Educational Resources Information Center

    Chu, Regina Juchun; Chu, Anita Zichun; Weng, Cathy; Tsai, Chin-Chung; Lin, Chia-chun

    2012-01-01

    This research explores the relationships between self-directed learning readiness and transformative learning theory (TLT) reflected by the Constructivist Internet-based Learning Environment Scale (CILES). A questionnaire survey about adult learner's perceptions of Internet-based learning was administered to adults enrolled in classes in community…

  19. An Analysis of Performance Differences between Self-Directed and Teacher-Directed Alternative Education Campuses in Texas

    ERIC Educational Resources Information Center

    Wimberley, Alan

    2010-01-01

    This study was conducted to analyze the performance differences between alternative education campuses in Texas that used teacher-directed strategies and those that used self-directed strategies. The study was also conducted to inform educators of the results these two strategies had achieved with at-risk students during the three years of…

  20. Paid Educational Leave and Self-Directed Learning: Implications for Legislation on the Learning Leave Scheme in South Korea

    ERIC Educational Resources Information Center

    Oh, Jeong Rok; Park, Cho Hyun; Jo, Sung Jun

    2016-01-01

    Purpose: The purposes of this study are to explore paid educational leave (PEL), self-directed learning (SDL) and the relationship between them; and to identify the implications for legislation on the learning leave scheme in South Korea. Design/Methodology/Approach: The research method of the study is a literature review. Articles were identified…

  1. Comparison of Self-Scoring Error Rate for SDS (Self Directed Search) (1970) and the Revised SDS (1977).

    ERIC Educational Resources Information Center

    Price, Gary E.; And Others

    A comparison of Self-Scoring Error Rate for Self Directed Search (SDS) and the revised SDS is presented. The subjects were college freshmen and sophomores who participated in career planning as a part of their orientation program, and a career workshop. Subjects, N=190 on first study and N=84 on second study, were then randomly assigned to the SDS…

  2. Self-Directed Work Teams in a Post-Apartheid Gold Mine: Perspectives from the Rock Face.

    ERIC Educational Resources Information Center

    Phatkathi, Timothy Sizwe

    2002-01-01

    A participant-observation study in a South African mining company that used self directed work team training identified organizational constraints that hindered training effectiveness: lack of materials, machinery breakdown, decentralized budget, and imposed standards. Miners more often used improvisation and initiative to solve daily problems,…

  3. A Comparison Study of the Paper-and-Pencil, Personal Computer, and Internet Versions of Holland's Self-Directed Search

    ERIC Educational Resources Information Center

    Lumsden, Jill A.; Sampson, James P., Jr.; Reardon, Robert C.; Lenz, Janet G.; Peterson, Gary W.

    2004-01-01

    The authors examined the extent to which the Realistic, Investigative, Artistic, Social, Enterprising, and Conventional scales and 3-point codes of the Self-Directed Search may be considered statistically and practically equivalent across 3 different modes of administration: paper-and-pencil, personal computer, and Internet. Student preferences…

  4. Understanding Self-Directed Learning in the Context of Mobile Web 2.0--Case Study with Workplace Learners

    ERIC Educational Resources Information Center

    Gu, Jia

    2016-01-01

    This paper presents the findings from a multiple-case study which has investigated the impact of mobile Web 2.0 technologies on self-directed learning (SDL) of workplace learners by exploring participants' learning experiences with a mobile App. Drawing on existing literatures, we examined learners' SDL personal attributes and process in the…

  5. #TwitterforTeachers: The Implications of Twitter as a Self-Directed Professional Development Tool for K-12 Teachers

    ERIC Educational Resources Information Center

    Visser, Ryan D.; Evering, Lea Calvert; Barrett, David E.

    2014-01-01

    This mixed-methods study explores how K-12 teachers use Twitter. An online survey was disseminated via Twitter to gauge their usage of, access to, and perceptions of Twitter. The results indicated that teachers highly value Twitter as a means of self-directed professional development. Respondents who reported using Twitter multiple times a day…

  6. Study of the Chemotactic Response of Multicellular Spheroids in a Microfluidic Device

    PubMed Central

    Ayuso, Jose M.; Basheer, Haneen A.; Monge, Rosa; Sánchez-Álvarez, Pablo; Doblaré, Manuel; Shnyder, Steven D.; Vinader, Victoria; Afarinkia, Kamyar

    2015-01-01

    We report the first application of a microfluidic device to observe chemotactic migration in multicellular spheroids. A microfluidic device was designed comprising a central microchamber and two lateral channels through which reagents can be introduced. Multicellular spheroids were embedded in collagen and introduced to the microchamber. A gradient of fetal bovine serum (FBS) was established across the central chamber by addition of growth media containing serum into one of the lateral channels. We observe that spheroids of oral squamous carcinoma cells OSC–19 invade collectively in the direction of the gradient of FBS. This invasion is more directional and aggressive than that observed for individual cells in the same experimental setup. In contrast to spheroids of OSC–19, U87-MG multicellular spheroids migrate as individual cells. A study of the exposure of spheroids to the chemoattractant shows that the rate of diffusion into the spheroid is slow and thus, the chemoattractant wave engulfs the spheroid before diffusing through it. PMID:26444904

  7. Educational Intervention on Undergraduate Cancer Awareness and Self-Directed Learning.

    PubMed

    Hwang, Lih-Lian

    2017-03-17

    Traditional lecture-based learning (LBL) can increase cancer awareness in undergraduates. However, because of the rapidly changing knowledge base in medicine, undergraduates must develop skills required for lifelong self-directed learning (SDL). Problem-based learning (PBL) has been suggested as an SDL approach. This study used a nonequivalent control group with a pretest-posttest design for comparing PBL and LBL for their effectiveness in increasing cancer awareness and SDL among nonmedicine or nonnursing major undergraduates in a health-related general education course. Experimental groups 1 and 2 were instructed using PBL while the control group was instructed using LBL. Cancer educational programs were offered to experimental group 1 and the control group but not to experimental group 2. Among the 325 undergraduates who completed a questionnaire regarding cancer awareness and SDL in the pretest, 223 completed the 12-week follow-up survey of the posttest. Cancer awareness significantly improved between the pretest and posttest in the control group (P < 0.001). No significant difference in cancer awareness improvement was observed between experimental group 1 and the control group (P = 0.934). Cancer awareness improvement in experimental group 2 was significantly less than in the control group (P = 0.010). No statistically significant change in SDL was observed in the control group during the study (P = 0.897). However, the SDL of experimental groups 1 and 2 improved more significantly than that of the control group (P = 0.049 and 0.023, respectively). Therefore, PBL is an effective method of increasing cancer awareness and SDL in undergraduates.

  8. Promoting self-directed learning skills in residency: a case study in program development.

    PubMed

    Nothnagle, Melissa; Goldman, Roberta; Quirk, Mark; Reis, Shmuel

    2010-12-01

    Self-directed learning (SDL) skills are essential for the formation and ongoing competence of today's physicians who work in the context of expanding scientific knowledge and changing health care systems. In 2007-2008, the authors developed a program to promote SDL in the Brown University Family Medicine Residency. Through an iterative process, the project team juggled learning theories (i.e., Knowles' SDL model, Collins' cognitive apprenticeship model, and Quirk's expertise development model) with curricular goals, instructional options, and local constraints to design a practical and theoretically robust intervention.The intervention that emerged from this process features a faculty physician serving as a learning coach who meets individually each month with all second-year residents to assist them in generating learning goals, reflecting on their learning experiences, and practicing evidence-based medicine (EBM) skills. An electronic portfolio serves as a documentation tool that supports reflection; residents record their goals and reflections in the portfolio, which also contains their formative assessments, procedure logs, and special projects. To address the hidden curriculum, the program designers took special care to avoid increasing faculty and resident workload and created a forum for discussion and group reflection. Program evaluation combines qualitative and quantitative methods, such as surveys of and interviews with residents and faculty, to assess changes in residents' SDL and EBM skills and in the program's educational culture. The authors use Kern and colleagues' six-step model for curriculum development to describe both the unfolding of this complex project and the choices that resulted in the current program design.

  9. Development of a Multicellular Three-dimensional Organotypic Model of the Human Intestinal Mucosa Grown Under Microgravity.

    PubMed

    Salerno-Goncalves, Rosangela; Fasano, Alessio; Sztein, Marcelo B

    2016-07-25

    Because cells growing in a three-dimensional (3-D) environment have the potential to bridge many gaps of cell cultivation in 2-D environments (e.g., flasks or dishes). In fact, it is widely recognized that cells grown in flasks or dishes tend to de-differentiate and lose specialized features of the tissues from which they were derived. Currently, there are mainly two types of 3-D culture systems where the cells are seeded into scaffolds mimicking the native extracellular matrix (ECM): (a) static models and (b) models using bioreactors. The first breakthrough was the static 3-D models. 3-D models using bioreactors such as the rotating-wall-vessel (RWV) bioreactors are a more recent development. The original concept of the RWV bioreactors was developed at NASA's Johnson Space Center in the early 1990s and is believed to overcome the limitations of static models such as the development of hypoxic, necrotic cores. The RWV bioreactors might circumvent this problem by providing fluid dynamics that allow the efficient diffusion of nutrients and oxygen. These bioreactors consist of a rotator base that serves to support and rotate two different formats of culture vessels that differ by their aeration source type: (1) Slow Turning Lateral Vessels (STLVs) with a co-axial oxygenator in the center, or (2) High Aspect Ratio Vessels (HARVs) with oxygenation via a flat, silicone rubber gas transfer membrane. These vessels allow efficient gas transfer while avoiding bubble formation and consequent turbulence. These conditions result in laminar flow and minimal shear force that models reduced gravity (microgravity) inside the culture vessel. Here we describe the development of a multicellular 3-D organotypic model of the human intestinal mucosa composed of an intestinal epithelial cell line and primary human lymphocytes, endothelial cells and fibroblasts cultured under microgravity provided by the RWV bioreactor.

  10. Case study: Comparison of motivation for achieving higher performance between self-directed and manager-directed aerospace engineering teams

    NASA Astrophysics Data System (ADS)

    Erlick, Katherine

    "The stereotype of engineers is that they are not people oriented; the stereotype implies that engineers would not work well in teams---that their task emphasis is a solo venture and does not encourage social aspects of collaboration" (Miner & Beyerlein, 1999, p. 16). The problem is determining the best method of providing a motivating environment where design engineers may contribute within a team in order to achieve higher performance in the organization. Theoretically, self-directed work teams perform at higher levels. But, allowing a design engineer to contribute to the team while still maintaining his or her anonymity is the key to success. Therefore, a motivating environment must be established to encourage greater self-actualization in design engineers. The purpose of this study is to determine the favorable motivational environment for design engineers and describe the comparison between two aerospace design-engineering teams: one self-directed and the other manager directed. Following the comparison, this study identified whether self-direction or manager-direction provides the favorable motivational environment for operating as a team in pursuit of achieving higher performance. The methodology used in this research was the case study focusing on the team's levels of job satisfaction and potential for higher performance. The collection of data came from three sources, (a) surveys, (b) researcher observer journal and (c) collection of artifacts. The surveys provided information regarding personal behavior characteristics, potentiality for higher performance and motivational attributes. The researcher journal provided information regarding team dynamics, individual interaction, conflict and conflict resolution. The milestone for performance was based on the collection of artifacts from the two teams. The findings from this study illustrated that whether the team was manager-directed or self-directed does not appear to influence the needs and wants of the

  11. The Quality of Questions and Use of Resources in Self-Directed Learning: Personal Learning Projects in the Maintenance of Certification

    ERIC Educational Resources Information Center

    Horsley, T.; O'Neill, J.; Campbell, C.

    2009-01-01

    Introduction: To engage effectively and efficiently in self-directed learning and knowledge-seeking practices, it is important that physicians construct well-formulated questions; yet, little is known about the quality of good questions and their relationship to self-directed learning or to change in practice behavior. Methods: Personal learning…

  12. Examining Motivational Orientation and Learning Strategies in Computer-Supported Self-Directed Learning (CS-SDL) for Mathematics: The Perspective of Intrinsic and Extrinsic Goals

    ERIC Educational Resources Information Center

    Lao, Andrew Chan-Chio; Cheng, Hercy N. H.; Huang, Mark C. L.; Ku, Oskar; Chan, Tak-Wai

    2017-01-01

    One-to-one technology, which allows every student to receive equal access to learning tasks through a personal computing device, has shown increasing potential for self-directed learning in elementary schools. With computer-supported self-directed learning (CS-SDL), students may set their own learning goals through the suggestions of the system…

  13. A Comparison of Students' Outcomes in Two Classes: Business Administration Students vs Communication Arts Students Based on Self-Directed Learning Activities

    ERIC Educational Resources Information Center

    Orawiwatnakul, Wiwat; Wichadee, Saovapa

    2011-01-01

    With research showing the benefits of self-directed learning, more activities are needed to provide learners opportunities for self-directed practice (Khomson, 1997; Lee, 1998; Phongnapharuk, 2007). A 12-week experimental study was performed with 80 EFL learners; one group contained 40 Communication Arts students and the other one consisted of 40…

  14. The Effect of TASC Wheel on Developing Self-Directed Learning Readiness and Academic Self Efficacy on a Sample of 7th Graders in Jordan

    ERIC Educational Resources Information Center

    Awwad, Ferial Mohammad Abu; Asha, Intisar Khalil; Jado, Saleh Mohammad Abu

    2014-01-01

    This study aimed to investigate the impact of Thinking Actively in Social Contexts (TASC Wheel) on developing self-directed learning readiness and academic self efficacy on a sample of seventh graders in Jordan. To achieve this objective, the researchers administered, after investigating their psychometric properties, a self-directed learning…

  15. What Students Think and What They Actually Do in a Mobile Assisted Language Learning Context: New Insights for Self-Directed Language Learning in Higher Education

    ERIC Educational Resources Information Center

    García Botero, Gustavo; Questier, Frederik

    2016-01-01

    In an attempt to understand whether Mobile-Assisted Language Learning (MALL) could foster students' self-directed learning, this paper analyzes a self-directed learning experience by means of a language app: Duolingo. In this study, higher education language students were encouraged to use Duolingo outside of the classroom. The data collected via…

  16. The Gonium pectorale genome demonstrates co-option of cell cycle regulation during the evolution of multicellularity

    PubMed Central

    Hanschen, Erik R.; Marriage, Tara N.; Ferris, Patrick J.; Hamaji, Takashi; Toyoda, Atsushi; Fujiyama, Asao; Neme, Rafik; Noguchi, Hideki; Minakuchi, Yohei; Suzuki, Masahiro; Kawai-Toyooka, Hiroko; Smith, David R.; Sparks, Halle; Anderson, Jaden; Bakarić, Robert; Luria, Victor; Karger, Amir; Kirschner, Marc W.; Durand, Pierre M.; Michod, Richard E.; Nozaki, Hisayoshi; Olson, Bradley J. S. C.

    2016-01-01

    The transition to multicellularity has occurred numerous times in all domains of life, yet its initial steps are poorly understood. The volvocine green algae are a tractable system for understanding the genetic basis of multicellularity including the initial formation of cooperative cell groups. Here we report the genome sequence of the undifferentiated colonial alga, Gonium pectorale, where group formation evolved by co-option of the retinoblastoma cell cycle regulatory pathway. Significantly, expression of the Gonium retinoblastoma cell cycle regulator in unicellular Chlamydomonas causes it to become colonial. The presence of these changes in undifferentiated Gonium indicates extensive group-level adaptation during the initial step in the evolution of multicellularity. These results emphasize an early and formative step in the evolution of multicellularity, the evolution of cell cycle regulation, one that may shed light on the evolutionary history of other multicellular innovations and evolutionary transitions. PMID:27102219

  17. Epigenetics decouples mutational from environmental robustness. Did it also facilitate multicellularity?

    PubMed

    Gombar, Saurabh; MacCarthy, Thomas; Bergman, Aviv

    2014-03-01

    The evolution of ever increasing complex life forms has required innovations at the molecular level in order to overcome existing barriers. For example, evolving processes for cell differentiation, such as epigenetic mechanisms, facilitated the transition to multicellularity. At the same time, studies using gene regulatory network models, and corroborated in single-celled model organisms, have shown that mutational robustness and environmental robustness are correlated. Such correlation may constitute a barrier to the evolution of multicellularity since cell differentiation requires sensitivity to cues in the internal environment during development. To investigate how this barrier might be overcome, we used a gene regulatory network model which includes epigenetic control based on the mechanism of histone modification via Polycomb Group Proteins, which evolved in tandem with the transition to multicellularity. Incorporating the Polycomb mechanism allowed decoupling of mutational and environmental robustness, thus allowing the system to be simultaneously robust to mutations while increasing sensitivity to the environment. In turn, this decoupling facilitated cell differentiation which we tested by evaluating the capacity of the system for producing novel output states in response to altered initial conditions. In the absence of the Polycomb mechanism, the system was frequently incapable of adding new states, whereas with the Polycomb mechanism successful addition of new states was nearly certain. The Polycomb mechanism, which dynamically reshapes the network structure during development as a function of expression dynamics, decouples mutational and environmental robustness, thus providing a necessary step in the evolution of multicellularity.

  18. Processing and characterization of multi-cellular monolithic bioceramics for bone regenerative scaffolds

    NASA Astrophysics Data System (ADS)

    Ari-Wahjoedi, Bambang; Ginta, Turnad Lenggo; Parman, Setyamartana; Abustaman, Mohd Zikri Ahmad

    2014-10-01

    Multicellular monolithic ceramic body is a ceramic material which has many gas or liquid passages partitioned by thin walls throughout the bulk material. There are many currently known advanced industrial applications of multicellular ceramics structures i.e. as supports for various catalysts, electrode support structure for solid oxide fuel cells, refractories, electric/electronic materials, aerospace vehicle re-entry heat shields and biomaterials for dental as well as orthopaedic implants by naming only a few. Multicellular ceramic bodies are usually made of ceramic phases such as mullite, cordierite, aluminum titanate or pure oxides such as silica, zirconia and alumina. What make alumina ceramics is excellent for the above functions are the intrinsic properties of alumina which are hard, wear resistant, excellent dielectric properties, resists strong acid and alkali attacks at elevated temperatures, good thermal conductivities, high strength and stiffness as well as biocompatible. In this work the processing technology leading to truly multicellular monolithic alumina ceramic bodies and their characterization are reported. Ceramic slip with 66 wt.% solid loading was found to be optimum as impregnant to the polyurethane foam template. Mullitic ceramic composite of alumina-sodium alumino disilicate-Leucite-like phases with bulk and true densities of 0.852 and 1.241 g cm-3 respectively, pore linear density of ±35 cm-1, linear and bulk volume shrinkages of 7-16% and 32 vol.% were obtained. The compressive strength and elastic modulus of the bioceramics are ≈0.5-1.0 and ≈20 MPa respectively.

  19. Prediction of the multicellular flow regime of natural convection in fenestration glazing cavities

    SciTech Connect

    Zhao, Y.; Goss, W.P.; Curcija, D.

    1997-12-31

    In this work, gas-filled tall rectangular cavities, typically found in insulating glazing units (IGUs) of fenestration systems, with constant temperatures at the side walls and zero heat flux at the top and bottom, were investigated. Critical Rayleigh numbers, Ra{sub c}, at which multicellular flow begins to form were determined for aspect ratios from 10.7 to 80. Using a general-purpose fluid flow and heat transfer finite-element analysis computer program (FDI 1993), numerical calculations were performed over the range of aspect ratios, A, from 10 to 80 with Rayleigh numbers, Ra, varying within the laminar flow regime. The calculations revealed that for aspect ratios between 10.7 and 30, the multicellular flow pattern dies out before the flow enters the turbulent flow regime. In addition, the lowest aspect ratio at which multicellular flow patterns existed was 10.7, which is lower than the lowest limit (A = 12) published by other researchers. The resulting critical Rayleigh numbers are plotted on a graph as a function of the aspect ratio and the Rayleigh numbers. The overall heat transfer results in terms of the average, or integrated, Nusselt numbers, Nu, are compared with available numerical and experimental data on multicellular flow in rectangular cavities, and good agreement was found. Also, streamline contour plots and temperature profiles are plotted for selected cases.

  20. Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics

    PubMed Central

    Cervera, Javier; Alcaraz, Antonio; Mafe, Salvador

    2016-01-01

    Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) the spatial distribution of an external biochemical agent can modify the conductances of the ion channels in a cell membrane and the multicellular electrical state. We focus on electrical effects in small multicellular ensembles, ignoring slow diffusional processes. The spatio-temporal patterns obtained for the local map of cell electric potentials illustrate the normalization of regions with abnormal cell electrical states. The effects of intercellular coupling and blocking of specific channels on the electrical patterns are described. These patterns can regulate the electrically-induced redistribution of charged nanoparticles over small regions of a model tissue. The inclusion of bioelectrical signals provides new insights for the modeling of cancer biophysics because collective multicellular states show electrical coupling mechanisms that are not readily deduced from biochemical descriptions at the individual cell level. PMID:26841954

  1. Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics.

    PubMed

    Cervera, Javier; Alcaraz, Antonio; Mafe, Salvador

    2016-02-04

    Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) the spatial distribution of an external biochemical agent can modify the conductances of the ion channels in a cell membrane and the multicellular electrical state. We focus on electrical effects in small multicellular ensembles, ignoring slow diffusional processes. The spatio-temporal patterns obtained for the local map of cell electric potentials illustrate the normalization of regions with abnormal cell electrical states. The effects of intercellular coupling and blocking of specific channels on the electrical patterns are described. These patterns can regulate the electrically-induced redistribution of charged nanoparticles over small regions of a model tissue. The inclusion of bioelectrical signals provides new insights for the modeling of cancer biophysics because collective multicellular states show electrical coupling mechanisms that are not readily deduced from biochemical descriptions at the individual cell level.

  2. A Novel Laboratory Activity for Teaching about the Evolution of Multicellularity

    ERIC Educational Resources Information Center

    Ratcliff, William C.; Raney, Allison; Westreich, Sam; Cotner, Sehoya

    2014-01-01

    The evolution of complexity remains one of the most challenging topics in biology to teach effectively. We present a novel laboratory activity, modeled on a recent experimental breakthrough, in which students experimentally evolve simple multicellularity using single-celled yeast ("Saccharomyces cerevisiae"). By simply selecting for…

  3. Sponge cell reaggregation: Cellular structure and morphogenetic potencies of multicellular aggregates.

    PubMed

    Lavrov, Andrey I; Kosevich, Igor A

    2016-02-01

    Sponges (phylum Porifera) are one of the most ancient extant multicellular animals and can provide valuable insights into origin and early evolution of Metazoa. High plasticity of cell differentiations and anatomical structure is characteristic feature of sponges. Present study deals with sponge cell reaggregation after dissociation as the most outstanding case of sponge plasticity. Dynamic of cell reaggregation and structure of multicellular aggregates of three demosponge species (Halichondria panicea (Pallas, 1766), Haliclona aquaeductus (Sсhmidt, 1862), and Halisarca dujardinii Johnston, 1842) were studied. Sponge tissue dissociation was performed mechanically. Resulting cell suspensions were cultured at 8-10°C for at least 5 days. Structure of multicellular aggregates was studied by light, transmission and scanning electron microscopy. Studied species share common stages of cell reaggregation-primary multicellular aggregates, early-stage primmorphs and primmorphs, but the rate of reaggregation varies considerably among species. Only cells of H. dujardinii are able to reconstruct functional and viable sponge after primmorphs formation. Sponge reconstruction in this species occurs due to active cell locomotion. Development of H. aquaeductus and H. panicea cells ceases at the stages of early primmorphs and primmorphs, respectively. Development of aggregates of these species is most likely arrested due to immobility of the majority of cells inside them. However, the inability of certain sponge species to reconstruct functional and viable individuals during cell reaggregation may be not a permanent species-specific characteristic, but depends on various factors, including the stage of the life cycle and experimental conditions.

  4. The evo-devo of multinucleate cells, tissues, and organisms, and an alternative route to multicellularity.

    PubMed

    Niklas, Karl J; Cobb, Edward D; Crawford, David R

    2013-01-01

    Multinucleate cells, tissues, or organisms occur in 60 families of land plants and in five otherwise diverse algal lineages (Rhodophyceae, Xanthophyceae, Chlorophyceae, Ulvophyceae, and Charophyceae). Inspection of a morphospace constructed out of eight developmental processes reveals a large number of possible variants of multinucleate cells and organisms that, with two exceptions, are represented by one or more plant species in one or more clades. Thus, most of these permutations of developmental processes exist in nature. Inspection of the morphospace also shows how the siphonous body plan (a multinucleate cell with the capacity for indeterminate growth in size) can theoretically serve as the direct progenitor of a multicellular organism by a process similar to segregative cell division observed in siphonocladean algae. Using molecular phylogenies of algal clades, different evolutionary scenarios are compared to see how the multicellular condition may have evolved from a multinucleate unicellular progenitor. We also show that the siphonous progenitor of a multicellular organism has previously passed through the alignment-of-fitness phase (in which genetic similarity among cells/nuclei minimizes internal genomic conflict) and the export-of-fitness phase (in which genetically similar cells/nuclei collaborate to achieve a reproductively integrated multicellular organism). All that is theoretically required is the evolutionary acquisition of the capacity to compartmentalize its cytoplasm.

  5. Social Work Field Training for the Community: A Student Self-Directed Approach in the Environmental Domain in Jordan.

    PubMed

    Al-Makhamreh, Sahar; Alnabulsi, Hana; Asfour, Hana

    2016-06-01

    This article outlines innovative field training methods that foster the abilities of undergraduate social work students so that they are able to empower the local community and raise awareness of environmental issues. In this study, students were engaged in a local community assessment that sought to understand their views on environmental and community impacts of the Synchrotron-Light for Experimental Science and Applications in the Middle East (SESAME) Project on the lives of the host village's residents. A students' self-directed approach was applied for the fieldwork out of which interventions were developed ( Garrison, 1997). Quantitative data were gathered by eighteen students through a survey of 361 questionnaires targeting Allan society. In addition to students' field notes, pre and post focus groups were used to collect qualitative information. Study findings highlighted the effectiveness of students' self-directed projects in cultivating culturally competent practices; ensuring sustainable development; and providing evidence-based knowledge on social work practice involving environmental issues.

  6. Chitosan Treatment Delays the Induction of Senescence in Human Foreskin Fibroblast Strains.

    PubMed

    Tsai, Ching-Wen; Kao, Yu-Ting; Chiang, I-Ni; Wang, Jyh-Horng; Young, Tai-Horng

    2015-01-01

    Fibroblasts have been extensively used as a model to study cellular senescence. The purpose of this study was to investigate whether the human foreskin fibroblast aging process could be regulated by using the biomaterial chitosan. Fibroblasts cultured on commercial tissue culture polystyrene (TCPS) entered senescence after 55-60 population doublings (PDs), and were accompanied by larger cell shape, higher senescence-associated β-galactosidase (SA β-gal) activity, lower proliferation capacity, and upregulation of senescence-associated molecular markers p21, p53, retinoblastoma (pRB), and p16. Before senescence was reached, PD48 cells were collected from TCPS and seeded on chitosan for three days (PD48-Cd3) to form multicellular spheroids. The protein expression of senescence-associated secretory phenotypes (SASPs) and senescence-associated molecular markers of these cells in PD48-Cd3 spheroids were downregulated significantly. Following chitosan treatment, fibroblasts reseeded on TCPS showed lower SA β-gal activity, increased cellular motility, and a higher proliferation ability of 70-75 PDs. These phenotypic changes were not accompanied by colonies forming in soft agar and a continuous decrease in the senescence-associated proteins p53 and pRB which act as a barrier to tumorigenesis. These results demonstrate that chitosan treatment could delay the induction of senescence which may be useful and safe for future tissue engineering applications.

  7. Benefits and limitations of an employer-led, structured logbook to promote self-directed learning in the clinical workplace.

    PubMed

    Dale, Vicki H M; Pierce, Stephanie E; May, Stephen A

    2013-01-01

    A structured logbook, consisting of a competency log and a learning contract, was designed and implemented as part of a two-week structured work placement for final-year veterinary students to help them become more self-directed in the workplace. The competency log encompassed 48 core skills and, along with the learning contract, was reviewed at the start and end of the placement. To assess their perceptions of the logbook in promoting self-directed learning, students and supervisors were asked to complete a questionnaire pre- and post-placement and to participate in focus groups (students) and interviews (supervisors) after the placement. The study found significant increases pre- to post-placement in students' perceived levels of competence in all 48 skills and their confidence in being self-directed. However, student attitudes toward the logbook significantly decreased in terms of it encouraging supervisors to take a clearly designed role in structuring learning and facilitating alignment of employer and student expectations. Although supervisors were generally positive about the logbook, some had not been able to review it with their students, which affected students' perceptions of the logbook's usefulness. Some supervisors felt they had not received enough training, and most, erroneously, believed the logbook to be an external research initiative rather than having been designed by the head of their own organization. This study demonstrated that a structured logbook may be useful in helping students become more self-directed; however, supervisor support for the logbook is critical. To facilitate this, supervisors require training and support from senior management.

  8. A longitudinal analysis of the self-directed learning readiness level of nursing students enrolled in a problem-based curriculum.

    PubMed

    Kocaman, Gülseren; Dicle, Aklime; Ugur, Aysen

    2009-05-01

    Self-directed learning is an important outcome of nursing education. Although problem-based learning is believed to facilitate self-directed learning, previous studies have reported conflicting results. This longitudinal survey explored the perceived changes in self-directed learning for 4 years in a baccalaureate nursing education program with an integrated problem-based learning curriculum. Fifty of 59 students (response rate, 85%) completed the Self-Directed Learning Readiness Scale at five different time points: at the beginning of each academic year and at program completion. Scores were significantly lower during the first academic year compared with other years, and fourth-year scores were significantly higher than in previous years. Scores on the three subscales (i.e., self-management, desire for learning, and self-control) increased significantly during the 4 years of the program. These findings support self-directed learning as a maturational process. Implications for nursing faculty and curriculum development are discussed.

  9. Influence of dominance rank and affiliation relationships on self-directed behavior in female Tibetan macaques (Macaca thibetana).

    PubMed

    Zhang, Qi-Xin; Li, Jin-Hua; Xia, Dong-Po; Zhu, Yong; Wang, Xi; Zhang, Dao

    2014-05-01

    Self-directed behavior (SDB) is characterized as an indicator of anxiety, frustration and stress in nonhuman primates. In this study, we collected self-directed behavior data from one group of free-ranging Tibetan macaques (Macaca thibetana) at Mt. Huangshan, China (September 2012-May 2013) using a combination of behavioral sampling methods including focal animal sampling, behavioral sampling, continuous sampling and instantaneous sampling. Our results showed that females engaged in significantly higher rates of self-directed behavior when they were in proximity to dominant individuals compared to subordinate ones. Conflict losers significantly increased their SDB rates after agonistic episodes, indicating that SDB might also serve as an index of anxiety in M. thibetana. We further found that females significantly increased their SDB rates when focal individual was proximity to weakly affiliation relationship higher rank members than to strongly affiliation relationship higher rank members. If conflicts were not reconciled, the postconflict SDB rates of losers were higher when they stayed with strongly affiliation opponents; if conflicts were reconciled, victims of strongly affiliation relationships opponents engaged in more SDB rates before reconciliation than after reconciliation, while victims of moderately affiliation relationships opponents did not engaged in more SDB rates before reconciliation than after reconciliation. We conclude that both of dominance rank and affiliation relationships might both influence the SDB rates of female Tibetan macaques significantly, suggesting that SDB is not only an index of anxiety in Tibetan macaques, but also can provide a new insight into evaluation of social relationships between individuals.

  10. Perseveration on a reversal-learning task correlates with rates of self-directed behavior in nonhuman primates.

    PubMed

    Judge, Peter G; Evans, David W; Schroepfer, Kara K; Gross, Alyssa C

    2011-09-12

    In humans and several nonhuman animals, repetitive behavior is associated with deficits on executive function tasks involving response inhibition. We tested for this relationship in nonhuman primates by correlating rates of normative behavior to performance on a reversal-learning task in which animals were required to inhibit a previously learned rule. We focused on rates of self-directed behavior (scratch, autogroom, self touch and manipulation) because these responses are known indicators of arousal or anxiety in primates, however, we also examined rates of other categories of behavior (e.g., locomotion). Behavior rates were obtained from 14 animals representing three nonhuman primate species (Macaca silenus, Saimiri sciureus, Cebus apella) living in separate social groups. The same animals were tested on a reversal-learning task in which they were presented with a black and a grey square on a touch screen and were trained to touch the black square. Once animals learned to select the black square, reward contingencies were reversed and animals were rewarded for selecting the grey square. Performance on the reversal-learning task was positively correlated to self-directed behavior in that animals that exhibited higher rates of self-directed behavior required more trials to achieve reversal. Reversal learning was not correlated to rates of any other category of behavior. Results indicate that rates of behavior associated with anxiety and arousal provide an indicator of executive function in nonhuman primates. The relationship suggests continuity between nonhuman primates and humans in the link between executive functioning and repetitive behavior.

  11. Transcriptional profiling of a yeast colony provides new insight into the heterogeneity of multicellular fungal communities.

    PubMed

    Traven, Ana; Jänicke, Amrei; Harrison, Paul; Swaminathan, Angavai; Seemann, Torsten; Beilharz, Traude H

    2012-01-01

    Understanding multicellular fungal structures is important for designing better strategies against human fungal pathogens. For example, the ability to form multicellular biofilms is a key virulence property of the yeast Candida albicans. C. albicans biofilms form on indwelling medical devices and are drug resistant, causing serious infections in hospital settings. Multicellular fungal communities are heterogeneous, consisting of cells experiencing different environments. Heterogeneity is likely important for the phenotypic characteristics of communities, yet it is poorly understood. Here we used colonies of the yeast Saccharomyces cerevisiae as a model fungal multicellular structure. We fractionated the outside colony layers from the cells in the center by FACS, using a Cit1-GFP marker expressed exclusively on the outside. Transcriptomics analysis of the two subpopulations revealed that the outside colony layers are actively growing by fermentative metabolism, while the cells residing on the inside are in a resting state and experience changes to mitochondrial activity. Our data shows several parallels with C. albicans biofilms providing insight into the contributions of heterogeneity to biofilm phenotypes. Hallmarks of C. albicans biofilms - the expression of ribosome and translation functions and activation of glycolysis and ergosterol biosynthesis occur on the outside of colonies, while expression of genes associates with sulfur assimilation is observed in the colony center. Cell wall restructuring occurs in biofilms, and cell wall functions are enriched in both fractions: the outside cells display enrichment of cell wall biosynthesis enzymes and cell wall proteins, while the inside cells express cell wall degrading enzymes. Our study also suggests that noncoding transcription and posttranscriptional mRNA regulation play important roles during growth of yeast in colonies, setting the scene for investigating these pathways in the development of multicellular

  12. Transcriptional Profiling of a Yeast Colony Provides New Insight into the Heterogeneity of Multicellular Fungal Communities

    PubMed Central

    Traven, Ana; Jänicke, Amrei; Harrison, Paul; Swaminathan, Angavai; Seemann, Torsten; Beilharz, Traude H.

    2012-01-01

    Understanding multicellular fungal structures is important for designing better strategies against human fungal pathogens. For example, the ability to form multicellular biofilms is a key virulence property of the yeast Candida albicans. C. albicans biofilms form on indwelling medical devices and are drug resistant, causing serious infections in hospital settings. Multicellular fungal communities are heterogeneous, consisting of cells experiencing different environments. Heterogeneity is likely important for the phenotypic characteristics of communities, yet it is poorly understood. Here we used colonies of the yeast Saccharomyces cerevisiae as a model fungal multicellular structure. We fractionated the outside colony layers from the cells in the center by FACS, using a Cit1-GFP marker expressed exclusively on the outside. Transcriptomics analysis of the two subpopulations revealed that the outside colony layers are actively growing by fermentative metabolism, while the cells residing on the inside are in a resting state and experience changes to mitochondrial activity. Our data shows several parallels with C. albicans biofilms providing insight into the contributions of heterogeneity to biofilm phenotypes. Hallmarks of C. albicans biofilms – the expression of ribosome and translation functions and activation of glycolysis and ergosterol biosynthesis occur on the outside of colonies, while expression of genes associates with sulfur assimilation is observed in the colony center. Cell wall restructuring occurs in biofilms, and cell wall functions are enriched in both fractions: the outside cells display enrichment of cell wall biosynthesis enzymes and cell wall proteins, while the inside cells express cell wall degrading enzymes. Our study also suggests that noncoding transcription and posttranscriptional mRNA regulation play important roles during growth of yeast in colonies, setting the scene for investigating these pathways in the development of multicellular

  13. MUC16 mucin (CA125) regulates the formation of multicellular aggregates by altering β-catenin signaling

    PubMed Central

    Giannakouros, Panagiota; Comamala, Marina; Matte, Isabelle; Rancourt, Claudine; Piché, Alain

    2015-01-01

    After shedding from the primary tumor site, ovarian cancer cells form three-dimensional multicellular aggregates that serve as vehicle for cancer cell dissemination in the peritoneal cavity. MUC16 mucin (CA125) is aberrantly expressed by most advanced serous ovarian cancers and can promote proliferation, migration and metastasis. MUC16 associates with E-cadherin and β-catenin, two proteins involved in regulation of cell adhesion and the formation of multicellular aggregates. However, the role of MUC16 in the formation of multicellular aggregates remains to be defined. Here, we show that MUC16 alters E-cadherin cellular localization and expression. Consistent with this, MUC16 knockdown inhibited the formation of multicellular aggregates and, conversely, forced expression of MUC16 C-terminal domain (CTD) enhanced the formation of multicellular aggregates. MUC16 knockdown induces β-catenin relocation from the cell membrane to the cytoplasm, decreases its expression by increasing degradation and decreases β-catenin target gene expression. MUC16 CTD inhibits GSK-3β-mediated phosphorylation and degradation of β-catenin, leading to increased β-catenin levels. Importantly, knockdown of β-catenin inhibited multicellular aggregation. These findings indicate that MUC16 promotes the formation of multicellular aggregates by inhibiting β-catenin degradation. PMID:25628932

  14. Fibroblast heterogeneity: more than skin deep.

    PubMed

    Sorrell, J Michael; Caplan, Arnold I

    2004-02-15

    Dermal fibroblasts are a dynamic and diverse population of cells whose functions in skin in many respects remain unknown. Normal adult human skin contains at least three distinct subpopulations of fibroblasts, which occupy unique niches in the dermis. Fibroblasts from each of these niches exhibit distinctive differences when cultured separately. Specific differences in fibroblast physiology are evident in papillary dermal fibroblasts, which reside in the superficial dermis, and reticular fibroblasts, which reside in the deep dermis. Both of these subpopulations of fibroblasts differ from the fibroblasts that are associated with hair follicles. Fibroblasts engage in fibroblast-epidermal interactions during hair development and in interfollicular regions of skin. They also play an important role in cutaneous wound repair and an ever-increasing role in bioengineering of skin. Bioengineered skin currently performs important roles in providing (1) a basic understanding of skin biology, (2) a vehicle for testing topically applied products and (3) a resource for skin replacement.

  15. [Fibroblast growth factor-2].

    PubMed

    Faitová, J

    2004-01-01

    Fibroblast growth factor-2 is a member of a large family of proteins that bind heparin and heparan sulfate and modulate the function of a wide range of cell types. FGF-2 occurs in several isoforms resulting from alternative initiations of traslation: an 18 kDa cytoplasmic isoform and four larger molecular weight nuclear isoforms (22, 22.5, 24 and 34 kDa). It acts mainly through a paracrine/autocrine mechanism involving high affinity transmembrane receptors and heparan sulfate proteoglycan low affinity receptors. It is expressed mostly in tissues of mesoderm and neuroectoderm origin, and plays an important role in mesoderm induction, stimulates the growth and development of the new blood vessels (angiogenesis), normal wound healing and tissue development. FGF-2 positively regulates hematopoiesis by acting on various cellular targets: stromal cells, early and committed hematopoietic progenitors and possibly some mature blood cells. FGF-2 is a potent hematopoietic growth factor that is likely to play an important role in physiological and pathological hematopoiesis.

  16. Prostacyclin analogs inhibit fibroblast migration.

    PubMed

    Kohyama, Tadashi; Liu, Xiangde; Kim, Hui Jung; Kobayashi, Tetsu; Ertl, Ronald F; Wen, Fu-Qiang; Takizawa, Hajime; Rennard, Stephen I

    2002-08-01

    The controlled accumulation of fibroblasts to sites of inflammation is crucial to effective tissue repair after injury. Either inadequate or excessive accumulation of fibroblasts could result in abnormal tissue function. Prostacyclin (PGI(2)) is a potent mediator in the coagulation and inflammatory processes. The aim of this study was to investigate the effect of PGI(2) on chemotaxis of human fetal lung fibroblasts (HFL-1). Using the blind well chamber technique, we found that the PGI(2) analog carbaprostacyclin (10(-6) M) inhibited HFL-1 chemotaxis to human plasma fibronectin (20 microg/ml) 58.0 +/- 13.2% (P < 0.05) and to platelet-derived growth factor (PDGF)-BB (10 ng/ml) 48.7 +/- 4.6% (P < 0.05). Checkerboard analysis demonstrated that carbaprostacyclin inhibits both directed and undirected migration. The inhibitory effect of the carbaprostacyclin was concentration dependent and blocked by the cAMP-dependent protein kinase (PKA) inhibitor KT-5720, suggesting that a cAMP-PKA pathway may be involved in the process. Two other PGI(2) analogs, ciprostene and dehydro-15-cyclohexyl carbaprostacyclin (both 10(-6) M), significantly inhibited fibroblast migration to fibronectin. In summary, PGI(2) appears to inhibit fibroblast chemotaxis to fibronectin and PDGF-BB. Such an effect may contribute to the regulation of fibroblasts in wound healing and could contribute to the pathogenesis of diseases characterized by abnormal tissue repair remodeling.

  17. Genomic analysis of organismal complexity in the multicellular green alga Volvox carteri.

    PubMed

    Prochnik, Simon E; Umen, James; Nedelcu, Aurora M; Hallmann, Armin; Miller, Stephen M; Nishii, Ichiro; Ferris, Patrick; Kuo, Alan; Mitros, Therese; Fritz-Laylin, Lillian K; Hellsten, Uffe; Chapman, Jarrod; Simakov, Oleg; Rensing, Stefan A; Terry, Astrid; Pangilinan, Jasmyn; Kapitonov, Vladimir; Jurka, Jerzy; Salamov, Asaf; Shapiro, Harris; Schmutz, Jeremy; Grimwood, Jane; Lindquist, Erika; Lucas, Susan; Grigoriev, Igor V; Schmitt, Rüdiger; Kirk, David; Rokhsar, Daniel S

    2010-07-09

    The multicellular green alga Volvox carteri and its morphologically diverse close relatives (the volvocine algae) are well suited for the investigation of the evolution of multicellularity and development. We sequenced the 138-mega-base pair genome of V. carteri and compared its approximately 14,500 predicted proteins to those of its unicellular relative Chlamydomonas reinhardtii. Despite fundamental differences in organismal complexity and life history, the two species have similar protein-coding potentials and few species-specific protein-coding gene predictions. Volvox is enriched in volvocine-algal-specific proteins, including those associated with an expanded and highly compartmentalized extracellular matrix. Our analysis shows that increases in organismal complexity can be associated with modifications of lineage-specific proteins rather than large-scale invention of protein-coding capacity.

  18. Sensitivity analysis of FBMC-based multi-cellular networks to synchronization errors and HPA nonlinearities

    NASA Astrophysics Data System (ADS)

    Elmaroud, Brahim; Faqihi, Ahmed; Aboutajdine, Driss

    2017-01-01

    In this paper, we study the performance of asynchronous and nonlinear FBMC-based multi-cellular networks. The considered system includes a reference mobile perfectly synchronized with its reference base station (BS) and K interfering BSs. Both synchronization errors and high-power amplifier (HPA) distortions will be considered and a theoretical analysis of the interference signal will be conducted. On the basis of this analysis, we will derive an accurate expression of signal-to-noise-plus-interference ratio (SINR) and bit error rate (BER) in the presence of a frequency-selective channel. In order to reduce the computational complexity of the BER expression, we applied an interesting lemma based on the moment generating function of the interference power. Finally, the proposed model is evaluated through computer simulations which show a high sensitivity of the asynchronous FBMC-based multi-cellular network to HPA nonlinear distortions.

  19. Mechanical guidance through cell-cell and cell-surface contact during multicellular streaming

    NASA Astrophysics Data System (ADS)

    Wang, Chenlu; Driscoll, Meghan; Gupta, Satyandra K.; Parent, Carole; Losert, Wolfgang

    2014-03-01

    During collective cell migration, mechanical forces arise from the extracellular matrix (ECM) through cell-surface contact and from other cells through cell-cell contact. These forces regulate the motion of migrating cell groups. To determine how these mechanical interactions balance during cell migration, we measured the shape dynamics of Dictyostelium discoideum cells at the multicellular streaming stage. We found that cells can coordinate their motion by synchronizing protrusion waves that travel along their membranes when they form proper cell-cell adhesion and cell-surface adhesion. In addition, our experiments on live actin labeled cells show that intracellular actin polymerization actively responds to the change of cell-cell/surface adhesion and helps to stabilize multicellular migration streams. Our finding suggests that the coordination of motion between neighboring cells in collective migration requires a balance between cell-cell adhesion and cell-surface adhesion, and that the cell cytoskeleton plays an important role in this balance.

  20. Imaging multicellular specimens with real-time optimized tiling light-sheet selective plane illumination microscopy

    PubMed Central

    Fu, Qinyi; Martin, Benjamin L.; Matus, David Q.; Gao, Liang

    2016-01-01

    Despite the progress made in selective plane illumination microscopy, high-resolution 3D live imaging of multicellular specimens remains challenging. Tiling light-sheet selective plane illumination microscopy (TLS-SPIM) with real-time light-sheet optimization was developed to respond to the challenge. It improves the 3D imaging ability of SPIM in resolving complex structures and optimizes SPIM live imaging performance by using a real-time adjustable tiling light sheet and creating a flexible compromise between spatial and temporal resolution. We demonstrate the 3D live imaging ability of TLS-SPIM by imaging cellular and subcellular behaviours in live C. elegans and zebrafish embryos, and show how TLS-SPIM can facilitate cell biology research in multicellular specimens by studying left-right symmetry breaking behaviour of C. elegans embryos. PMID:27004937

  1. The Dynamic Regulatory Genome of Capsaspora and the Origin of Animal Multicellularity.

    PubMed

    Sebé-Pedrós, Arnau; Ballaré, Cecilia; Parra-Acero, Helena; Chiva, Cristina; Tena, Juan J; Sabidó, Eduard; Gómez-Skarmeta, José Luis; Di Croce, Luciano; Ruiz-Trillo, Iñaki

    2016-05-19

    The unicellular ancestor of animals had a complex repertoire of genes linked to multicellular processes. This suggests that changes in the regulatory genome, rather than in gene innovation, were key to the origin of animals. Here, we carry out multiple functional genomic assays in Capsaspora owczarzaki, the unicellular relative of animals with the largest known gene repertoire for transcriptional regulation. We show that changing chromatin states, differential lincRNA expression, and dynamic cis-regulatory sites are associated with life cycle transitions in Capsaspora. Moreover, we demonstrate conservation of animal developmental transcription-factor networks and extensive network interconnection in this premetazoan organism. In contrast, however, Capsaspora lacks animal promoter types, and its regulatory sites are small, proximal, and lack signatures of animal enhancers. Overall, our results indicate that the emergence of animal multicellularity was linked to a major shift in genome cis-regulatory complexity, most notably the appearance of distal enhancer regulation.

  2. Bacterial Stigmergy: An Organising Principle of Multicellular Collective Behaviours of Bacteria

    PubMed Central

    Gloag, Erin S.; Whitchurch, Cynthia B.

    2015-01-01

    The self-organisation of collective behaviours often manifests as dramatic patterns of emergent large-scale order. This is true for relatively “simple” entities such as microbial communities and robot “swarms,” through to more complex self-organised systems such as those displayed by social insects, migrating herds, and many human activities. The principle of stigmergy describes those self-organised phenomena that emerge as a consequence of indirect communication between individuals of the group through the generation of persistent cues in the environment. Interestingly, despite numerous examples of multicellular behaviours of bacteria, the principle of stigmergy has yet to become an accepted theoretical framework that describes how bacterial collectives self-organise. Here we review some examples of multicellular bacterial behaviours in the context of stigmergy with the aim of bringing this powerful and elegant self-organisation principle to the attention of the microbial research community. PMID:25653882

  3. Noise-plasticity correlations of gene expression in the multicellular organism Arabidopsis thaliana.

    PubMed

    Hirao, Koudai; Nagano, Atsushi J; Awazu, Akinori

    2015-12-21

    Gene expression levels exhibit stochastic variations among genetically identical organisms under the same environmental conditions (called gene expression "noise" or phenotype "fluctuation"). In yeast and Escherichia coli, positive correlations have been found between such gene expression noise and "plasticity" with environmental variations. To determine the universality of such correlations in both unicellular and multicellular organisms, we focused on the relationships between gene expression "noise" and "plasticity" in Arabidopsis thaliana, a multicellular model organism. In recent studies on yeast and E. coli, only some gene groups with specific properties of promoter architecture, average expression levels, and functions exhibited strong noise-plasticity correlations. However, we found strong noise-plasticity correlations for most gene groups in Arabidopsis; additionally, promoter architecture, functional essentiality of genes, and circadian rhythm appeared to have only a weak influence on the correlation strength. The differences in the characteristics of noise-plasticity correlations may result from three-dimensional chromosomal structures and/or circadian rhythm.

  4. An innovative interdisciplinary approach to self-directed learning with a focus on the continuum of patient care.

    PubMed

    Faucher, Dina; Everson, Claire R

    2004-01-01

    Current regulatory review standards emphasize the hospital's role in providing continuum of care. Today, patient care staff must know more about the "continuum of care" concept so they can help patients more fully understand their treatment and take an active role in their own care. One of the challenges is finding creative and effective ways to get the message across to everyone on the staff. This article describes one approach to self-directed learning that takes into consideration individual learning styles and level of proficiency with a focus on the continuum of patient care.

  5. Processing and characterization of multi-cellular monolithic bioceramics for bone regenerative scaffolds

    SciTech Connect

    Ari-Wahjoedi, Bambang; Ginta, Turnad Lenggo; Parman, Setyamartana; Abustaman, Mohd Zikri Ahmad

    2014-10-24

    Multicellular monolithic ceramic body is a ceramic material which has many gas or liquid passages partitioned by thin walls throughout the bulk material. There are many currently known advanced industrial applications of multicellular ceramics structures i.e. as supports for various catalysts, electrode support structure for solid oxide fuel cells, refractories, electric/electronic materials, aerospace vehicle re-entry heat shields and biomaterials for dental as well as orthopaedic implants by naming only a few. Multicellular ceramic bodies are usually made of ceramic phases such as mullite, cordierite, aluminum titanate or pure oxides such as silica, zirconia and alumina. What make alumina ceramics is excellent for the above functions are the intrinsic properties of alumina which are hard, wear resistant, excellent dielectric properties, resists strong acid and alkali attacks at elevated temperatures, good thermal conductivities, high strength and stiffness as well as biocompatible. In this work the processing technology leading to truly multicellular monolithic alumina ceramic bodies and their characterization are reported. Ceramic slip with 66 wt.% solid loading was found to be optimum as impregnant to the polyurethane foam template. Mullitic ceramic composite of alumina-sodium alumino disilicate-Leucite-like phases with bulk and true densities of 0.852 and 1.241 g cm{sup −3} respectively, pore linear density of ±35 cm{sup −1}, linear and bulk volume shrinkages of 7-16% and 32 vol.% were obtained. The compressive strength and elastic modulus of the bioceramics are ≈0.5-1.0 and ≈20 MPa respectively.

  6. Fine-mapping of the woolly gene controlling multicellular trichome formation and embryonic development in tomato.

    PubMed

    Yang, Changxian; Li, Hanxia; Zhang, Junhong; Wang, Taotao; Ye, Zhibiao

    2011-08-01

    Trichomes are small hairs that originate from the epidermal cells of nearly all land plants, and they exist in unicellular and multicellular forms. The regulatory pathway of unicellular trichomes in Arabidopsis is well characterized. However, little is known about the multicellular trichome formation in tomato (Solanum lycopersicum). The woolly (Wo) gene controls multicellular trichome initiation and leads to embryonic lethality when homozygous in tomato. To clone and characterize Wo, the gene was fine-mapped to a DNA fragment of ~200 kb using the map-based cloning strategy. A series of sequence-based molecular markers, including simple sequence repeat, sequence characterized amplified region, and cleaved amplified polymorphic sequence were utilized in this study. Analysis of the sequence indicated that this region carries 19 putative open reading frames. These results will provide not only the important information for the isolation and characterization of Wo but also the starting point for studying the regulatory pathway responsible for trichome formation and embryonic lethality in tomato.

  7. Extended Time-lapse Intravital Imaging of Real-time Multicellular Dynamics in the Tumor Microenvironment

    PubMed Central

    Harney, Allison S.; Wang, Yarong; Condeelis, John S.; Entenberg, David

    2016-01-01

    In the tumor microenvironment, host stromal cells interact with tumor cells to promote tumor progression, angiogenesis, tumor cell dissemination and metastasis. Multicellular interactions in the tumor microenvironment can lead to transient events including directional tumor cell motility and vascular permeability. Quantification of tumor vascular permeability has frequently used end-point experiments to measure extravasation of vascular dyes. However, due to the transient nature of multicellular interactions and vascular permeability, the kinetics of these dynamic events cannot be discerned. By labeling cells and vasculature with injectable dyes or fluorescent proteins, high-resolution time-lapse intravital microscopy has allowed the direct, real-time visualization of transient events in the tumor microenvironment. Here we describe a method for using multiphoton microscopy to perform extended intravital imaging in live mice to directly visualize multicellular dynamics in the tumor microenvironment. This method details cellular labeling strategies, the surgical preparation of a mammary skin flap, the administration of injectable dyes or proteins by tail vein catheter and the acquisition of time-lapse images. The time-lapse sequences obtained from this method facilitate the visualization and quantitation of the kinetics of cellular events of motility and vascular permeability in the tumor microenvironment. PMID:27341448

  8. Directed self-assembly of large scaffold-free multi-cellular honeycomb structures.

    PubMed

    Tejavibulya, Nalin; Youssef, Jacquelyn; Bao, Brian; Ferruccio, Toni-Marie; Morgan, Jeffrey R

    2011-09-01

    A significant challenge to the field of biofabrication is the rapid construction of large three-dimensional (3D) living tissues and organs. Multi-cellular spheroids have been used as building blocks. In this paper, we create large multi-cellular honeycomb building blocks using directed self-assembly, whereby cell-to-cell adhesion, in the context of the shape and obstacles of a micro-mold, drives the formation of a 3D structure. Computer-aided design, rapid prototyping and replica molding were used to fabricate honeycomb-shaped micro-molds. Nonadhesive hydrogels cast from these micro-molds were equilibrated in the cell culture medium and seeded with two types of mammalian cells. The cells settled into the honeycomb recess were unable to attach to the nonadhesive hydrogel and so cell-to-cell adhesion drove the self-assembly of a large multi-cellular honeycomb within 24 h. Distinct morphological changes occurred to the honeycomb and its cells indicating the presence of significant cell-mediated tension. Unlike the spheroid, whose size is constrained by a critical diffusion distance needed to maintain cell viability, the overall size of the honeycomb is not limited. The rapid production of the honeycomb building unit, with its multiple rings of high-density cells and open lumen spaces, offers interesting new possibilities for biofabrication strategies.

  9. Transcriptome profiling of trichome-less reveals genes associated with multicellular trichome development in Cucumis sativus.

    PubMed

    Zhao, Jun-Long; Wang, Yun-Li; Yao, Dan-Qing; Zhu, Wen-Ying; Chen, Long; He, Huan-Le; Pan, Jun-Song; Cai, Run

    2015-10-01

    Trichomes on plants, similar to fine hairs on animal and human bodies, play important roles in plant survival and development. They also represent a useful model for the study of cell differentiation. Although the regulatory gene network of unicellular trichome development in Arabidopsis thaliana has been well studied, the genes that regulate multicellular trichome development remain unclear. We confirmed that Cucumis sativus (cucumber) trichomes are multicellular and unbranched, but identified a spontaneous mutant, trichome-less (tril), which presented a completely glabrous phenotype. We compared the transcriptome profilings of the tril mutant and wild type using the Illumina HiSeq 2000 sequencing technology. A total of 991 genes exhibited differential expression: 518 were up-regulated and 473 were down-regulated. We further identified 62 differentially expressed genes that encoded crucial transcription factors and were subdivided into seven categories: homeodomain, MADS, MYB, and WRKY domains, ethylene-responsive, zinc finger, and other transcription factor genes. We further analyzed the tissue-expression profiles of two candidate genes, GLABRA2-like and ATHB51-like, using qRT-PCR and found that these two genes were specifically expressed in the epidermis and trichomes, respectively. These results and the tril mutant provide useful tools to study the molecular networks associated with multicellular trichome development.

  10. Transcriptome analysis in Cucumis sativus identifies genes involved in multicellular trichome development.

    PubMed

    Zhao, Jun-Long; Pan, Jun-Song; Guan, Yuan; Nie, Jing-Tao; Yang, Jun-Jun; Qu, Mei-Ling; He, Huan-Le; Cai, Run

    2015-05-01

    The regulatory gene network of unicellular trichome development in Arabidopsis thaliana has been studied intensively, but that of multicellular remains unclear. In the present study, we characterized cucumber trichomes as representative multicellular and unbranched structures, but in a spontaneous mutant, mict (micro-trichome), all trichomes showed a micro-size and stunted morphologies. We revealed the transcriptome profile using Illumina HiSeq 2000 sequencing technology, and determined that a total of 1391 genes exhibited differential expression. We further validated the accuracy of the transcriptome data by RT-qPCR and found that 43 genes encoding critical transcription factors were likely involved in multicellular trichome development. These 43 candidate genes were subdivided into seven groups: homeodomain, MYB-domain, WRKY-domain, bHLH-domain, ethylene-responsive, zinc finger and other transcription factor genes. Our findings also serve as a powerful tool to further study the relevant molecular networks, and provide a new perspective for investigating this complex and species-specific developmental process.

  11. Genomic analysis of organismal complexity in the multicellular green alga Volvox carteri

    SciTech Connect

    Prochnik, Simon E.; Umen, James; Nedelcu, Aurora; Hallmann, Armin; Miller, Stephen M.; Nishii, Ichiro; Ferris, Patrick; Kuo, Alan; Mitros, Therese; Fritz-Laylin, Lillian K.; Hellsten, Uffe; Chapman, Jarrod; Simakov, Oleg; Rensing, Stefan A.; Terry, Astrid; Pangilinan, Jasmyn; Kapitonov, Vladimir; Jurka, Jerzy; Salamov, Asaf; Shapiro, Harris; Schmutz, Jeremy; Grimwood, Jane; Lindquist, Erika; Lucas, Susan; Grigoriev, Igor V.; Schmitt, Rudiger; Kirk, David; Rokhsar, Daniel S.

    2010-07-01

    Analysis of the Volvox carteri genome reveals that this green alga's increased organismal complexity and multicellularity are associated with modifications in protein families shared with its unicellular ancestor, and not with large-scale innovations in protein coding capacity. The multicellular green alga Volvox carteri and its morphologically diverse close relatives (the volvocine algae) are uniquely suited for investigating the evolution of multicellularity and development. We sequenced the 138 Mb genome of V. carteri and compared its {approx}14,500 predicted proteins to those of its unicellular relative, Chlamydomonas reinhardtii. Despite fundamental differences in organismal complexity and life history, the two species have similar protein-coding potentials, and few species-specific protein-coding gene predictions. Interestingly, volvocine algal-specific proteins are enriched in Volvox, including those associated with an expanded and highly compartmentalized extracellular matrix. Our analysis shows that increases in organismal complexity can be associated with modifications of lineage-specific proteins rather than large-scale invention of protein-coding capacity.

  12. PINOCYTOSIS IN FIBROBLASTS

    PubMed Central

    Steinman, Ralph M.; Silver, Jonathan M.; Cohn, Zanvil A.

    1974-01-01

    Horseradish peroxidase (HRP) was used as a marker to determine the rate of ongoing pinocytosis in several fibroblast cell lines. The enzyme was interiorized in the fluid phase without evidence of adsorption to the cell surface. Cytochemical reaction product was not found on the cell surface and was visualized only within intracellular vesicles and granules. Uptake was directly proportional to the administered concentration of HRP and to the duration of exposure. The rate of HRP uptake was 0.0032–0.0035% of the administered load per 106 cells per hour for all cells studied with one exception: L cells, after reaching confluence, progressively increased their pinocytic activity two- to fourfold. After uptake of HRP, L cells inactivated HRP with a half-life of 6–8 h. Certain metabolic requirements of pinocytosis were then studied in detail in L cells. Raising the environmental temperature increased pinocytosis over a range of 2–38°C. The Q10 was 2.7 and the activation energy, 17.6 kcal/mol. Studies on the levels of cellular ATP in the presence of various metabolic inhibitors (fluoride, 2-desoxyglycose, azide, and cyanide) showed that L cells synthesized ATP by both glycolytic and respiratory pathways. A combination of a glycolytic and a respiratory inhibitor was needed to depress cellular ATP levels as well as pinocytic activity to 10–20% of control values, whereas drugs administered individually had only partial effects. In spite of the availability of an accurate quantitative assay for fluid and solute uptake, the function of pinocytosis in tissue culture cells remains unknown. PMID:4140194

  13. Perceptions of self-determination by special education and rehabilitation practitioners based on viewing a self-directed IEP versus an external-directed IEP meeting.

    PubMed

    Branding, Dave; Bates, Paul; Miner, Craig

    2009-01-01

    This study investigated perception of self-determination by special education and rehabilitation practitioners following their exposure to a videotaped simulation of a self-directed IEP meeting and an external-directed IEP meeting involving an adolescent with mild mental retardation. Groups of special education practitioners and rehabilitation practitioners did not differ from each other in their perceptions of self-determination before or after viewing either the self-directed or external-directed IEP meeting simulation. However, both groups of respondents had higher perceptions of the self-determination capability of the confederate student when they viewed her in a self-directed meeting. In addition, respondents consistently rated the self-directed meeting simulation as being of higher overall quality than the external-directed meeting. Results are discussed in relation to practitioner recommendations and future research in regard to the development and enabling of self-determination skills involving persons with disabilities.

  14. A Multidisciplinary Self-Directed Learning Module Improves Knowledge of a Quality Improvement Instrument: The HEART Pathway.

    PubMed

    Hartman, Nicholas D; Harper, Erin N; Leppert, Lauren M; Browning, Brittany M; Askew, Kim; Manthey, David E; Mahler, Simon A

    2016-07-20

    We created and tested an educational intervention to support implementation of an institution wide QI project (the HEART Pathway) designed to improve care for patients with acute chest pain. Although online learning modules have been shown effective in imparting knowledge regarding QI projects, it is unknown whether these modules are effective across specialties and healthcare professions. Participants, including nurses, advanced practice clinicians, house staff and attending physicians (N = 486), were enrolled into an online, self-directed learning course exploring the key concepts of the HEART Pathway. The module was completed by 97% of enrollees (469/486) and 90% passed on the first attempt (422/469). Out of 469 learners, 323 completed the pretest, learning module and posttest in the correct order. Mean test scores across learners improved significantly from 74% to 89% from the pretest to the posttest. Following the intervention, the HEART Pathway was used for 88% of patients presenting to our institution with acute chest pain. Our data demonstrate that this online, self-directed learning module can improve knowledge of the HEART Pathway across specialties-paving the way for more efficient and informed care for acute chest pain patients.

  15. Social Work Field Training for the Community: A Student Self-Directed Approach in the Environmental Domain in Jordan

    PubMed Central

    Al-Makhamreh, Sahar; Alnabulsi, Hana; Asfour, Hana

    2016-01-01

    This article outlines innovative field training methods that foster the abilities of undergraduate social work students so that they are able to empower the local community and raise awareness of environmental issues. In this study, students were engaged in a local community assessment that sought to understand their views on environmental and community impacts of the Synchrotron-Light for Experimental Science and Applications in the Middle East (SESAME) Project on the lives of the host village's residents. A students' self-directed approach was applied for the fieldwork out of which interventions were developed ( Garrison, 1997). Quantitative data were gathered by eighteen students through a survey of 361 questionnaires targeting Allan society. In addition to students' field notes, pre and post focus groups were used to collect qualitative information. Study findings highlighted the effectiveness of students' self-directed projects in cultivating culturally competent practices; ensuring sustainable development; and providing evidence-based knowledge on social work practice involving environmental issues. PMID:27559202

  16. On eukaryotic intelligence: signaling system's guidance in the evolution of multicellular organization.

    PubMed

    Marijuán, Pedro C; del Moral, Raquel; Navarro, Jorge

    2013-10-01

    Communication with the environment is an essential characteristic of the living cell, even more when considering the origins and evolution of multicellularity. A number of changes and tinkering inventions were necessary in the evolutionary transition between prokaryotic and eukaryotic cells, which finally made possible the appearance of genuine multicellular organisms. In the study of this process, however, the transformations experimented by signaling systems themselves have been rarely object of analysis, obscured by other more conspicuous biological traits: incorporation of mitochondria, segregated nucleus, introns/exons, flagellum, membrane systems, etc. Herein a discussion of the main avenues of change from prokaryotic to eukaryotic signaling systems and a review of the signaling resources and strategies underlying multicellularity will be attempted. In the expansion of prokaryotic signaling systems, four main systemic resources were incorporated: molecular tools for detection of solutes, molecular tools for detection of solvent (Donnan effect), the apparatuses of cell-cycle control, and the combined system endocytosis/cytoskeleton. The multiple kinds of enlarged, mixed pathways that emerged made possible the eukaryotic revolution in morphological and physiological complexity. The massive incorporation of processing resources of electro-molecular nature, derived from the osmotic tools counteracting the Donnan effect, made also possible the organization of a computational tissue with huge information processing capabilities: the nervous system. In the central nervous systems of vertebrates, and particularly in humans, neurons have achieved both the highest level of molecular-signaling complexity and the highest degree of information-processing adaptability. Theoretically, it can be argued that there has been an accelerated pace of evolutionary change in eukaryotic signaling systems, beyond the other general novelties introduced by eukaryotic cells in their

  17. Radiosensitivity of different human tumor cells lines grown as multicellular spheroids determined from growth curves and survival data

    SciTech Connect

    Schwachoefer, J.H.C.; Crooijmans, R.P.; van Gasteren, J.J.; Hoogenhout, J.; Jerusalem, C.R.; Kal, H.B.; Theeuwes, A.G. )

    1989-11-01

    Five human tumor cell lines were grown as multicellular tumor spheroids (MTS) to determine whether multicellular tumor spheroids derived from different types of tumors would show tumor-type dependent differences in response to single-dose irradiation, and whether these differences paralleled clinical behavior. Multicellular tumor spheroids of two neuroblastoma, one lung adenocarcinoma, one melanoma, and a squamous cell carcinoma of the oral tongue, were studied in terms of growth delay, calculated cell survival, and spheroid control dose50 (SCD50). Growth delay and cell survival analysis for the tumor cell lines showed sensitivities that correlated well with clinical behavior of the tumor types of origin. Similar to other studies on melanoma multicellular tumor spheroids our spheroid control dose50 results for the melanoma cell line deviated from the general pattern of sensitivity. This might be due to the location of surviving cells, which prohibits proliferation of surviving cells and hence growth of melanoma multicellular tumor spheroids. This study demonstrates that radiosensitivity of human tumor cell lines can be evaluated in terms of growth delay, calculated cell survival, and spheroid control dose50 when grown as multicellular tumor spheroids. The sensitivity established from these evaluations parallels clinical behavior, thus offering a unique tool for the in vitro analysis of human tumor radiosensitivity.

  18. Fibroblast growth factors as tissue repair and regeneration therapeutics

    PubMed Central

    Kinnunen, Tarja K.

    2016-01-01

    Cell communication is central to the integration of cell function required for the development and homeostasis of multicellular animals. Proteins are an important currency of cell communication, acting locally (auto-, juxta-, or paracrine) or systemically (endocrine). The fibroblast growth factor (FGF) family contributes to the regulation of virtually all aspects of development and organogenesis, and after birth to tissue maintenance, as well as particular aspects of organism physiology. In the West, oncology has been the focus of translation of FGF research, whereas in China and to an extent Japan a major focus has been to use FGFs in repair and regeneration settings. These differences have their roots in research history and aims. The Chinese drive into biotechnology and the delivery of engineered clinical grade FGFs by a major Chinese research group were important enablers in this respect. The Chinese language clinical literature is not widely accessible. To put this into context, we provide the essential molecular and functional background to the FGF communication system covering FGF ligands, the heparan sulfate and Klotho co-receptors and FGF receptor (FGFR) tyrosine kinases. We then summarise a selection of clinical reports that demonstrate the efficacy of engineered recombinant FGF ligands in treating a wide range of conditions that require tissue repair/regeneration. Alongside, the functional reasons why application of exogenous FGF ligands does not lead to cancers are described. Together, this highlights that the FGF ligands represent a major opportunity for clinical translation that has been largely overlooked in the West. PMID:26793421

  19. Co-Culture of Tumor Spheroids and Fibroblasts in a Collagen Matrix-Incorporated Microfluidic Chip Mimics Reciprocal Activation in Solid Tumor Microenvironment

    PubMed Central

    Jeong, Su-Yeong; Lee, Ji-Hyun; Shin, Yoojin; Chung, Seok; Kuh, Hyo-Jeong

    2016-01-01

    Multicellular 3D culture and interaction with stromal components are considered essential elements in establishing a ‘more clinically relevant’ tumor model. Matrix-embedded 3D cultures using a microfluidic chip platform can recapitulate the microscale interaction within tumor microenvironments. As a major component of tumor microenvironment, cancer-associated fibroblasts (CAFs) play a role in cancer progression and drug resistance. Here, we present a microfluidic chip-based tumor tissue culture model that integrates 3D tumor spheroids (TSs) with CAF in proximity within a hydrogel scaffold. HT-29 human colorectal carcinoma cells grew into 3D TSs and the growth was stimulated when co-cultured with fibroblasts as shown by 1.5-folds increase of % changes in diameter over 5 days. TS cultured for 6 days showed a reduced expression of Ki-67 along with increased expression of fibronectin when co-cultured with fibroblasts compared to mono-cultured TSs. Fibroblasts were activated under co-culture conditions, as demonstrated by increases in α-SMA expression and migratory activity. When exposed to paclitaxel, a survival advantage was observed in TSs co-cultured with activated fibroblasts. Overall, we demonstrated the reciprocal interaction between TSs and fibroblasts in our 7-channel microfluidic chip. The co-culture of 3D TS-CAF in a collagen matrix-incorporated microfluidic chip may be useful to study the tumor microenvironment and for evaluation of drug screening and evaluation. PMID:27391808

  20. Cardiac Fibrosis: The Fibroblast Awakens

    PubMed Central

    Travers, Joshua G.; Kamal, Fadia A.; Robbins, Jeffrey; Yutzey, Katherine E.; Blaxall, Burns C.

    2016-01-01

    Myocardial fibrosis is a significant global health problem associated with nearly all forms of heart disease. Cardiac fibroblasts comprise an essential cell type in the heart that is responsible for the homeostasis of the extracellular matrix; however upon injury, these cells transform to a myofibroblast phenotype and contribute to cardiac fibrosis. This remodeling involves pathological changes that include chamber dilation, cardiomyocyte hypertrophy and apoptosis, and ultimately leads to the progression to heart failure. Despite the critical importance of fibrosis in cardiovascular disease, our limited understanding of this cell population impedes the development of potential therapies that effectively target this cell type and its pathological contribution to disease progression. This review summarizes current knowledge regarding the origins and roles of fibroblasts, mediators and signaling pathways known to influence fibroblast function after myocardial injury, as well as novel therapeutic strategies under investigation to attenuate cardiac fibrosis. PMID:26987915

  1. Effectiveness of hands-on tutoring and guided self-directed learning versus self-directed learning alone to educate critical care fellows on mechanical ventilation - a pilot project.

    PubMed

    Ramar, Kannan; De Moraes, Alice Gallo; Selim, Bernardo; Holets, Steven; Oeckler, Richard

    2016-01-01

    Background Physicians require extensive training to achieve proficiency in mechanical ventilator (MV) management of the critically ill patients. Guided self-directed learning (GSDL) is usually the method used to learn. However, it is unclear if this is the most proficient approach to teaching mechanical ventilation to critical care fellows. We, therefore, investigated whether critical care fellows achieve higher scores on standardized testing and report higher satisfaction after participating in a hands-on tutorial combined with GSDL compared to self-directed learning alone. Methods First-year Pulmonary and Critical Care Medicine (PCCM) fellows (n=6) and Critical Care Internal Medicine (CCIM) (n=8) fellows participated. Satisfaction was assessed using the Likert scale. MV knowledge assessment was performed by administering a standardized 25-question multiple choice pre- and posttest. For 2 weeks the CCIM fellows were exposed to GSDL, while the PCCM fellows received hands-on tutoring combined with GSDL. Results Ninety-three percentage (6 PCCM and 7 CCIM fellows, total of 13 fellows) completed all evaluations and were included in the final analysis. CCIM and PCCM fellows scored similarly in the pretest (64% vs. 52%, p=0.13). Following interventions, the posttest scores increased in both groups. However, no significant difference was observed based on the interventions (74% vs. 77%, p=0.39). The absolute improvement with the hands-on-tutoring and GSDL group was higher than GSDL alone (25% vs. 10%, p=0.07). Improved satisfaction scores were noted with hands-on tutoring. Conclusions Hands-on tutoring combined with GSDL and GSDL alone were both associated with an improvement in posttest scores. Absolute improvement in test and satisfaction scores both trended higher in the hands-on tutorial group combined with GSDL group.

  2. Genome duplication and mutations in ACE2 cause multicellular, fast-sedimenting phenotypes in evolved Saccharomyces cerevisiae

    PubMed Central

    Oud, Bart; Guadalupe-Medina, Victor; Nijkamp, Jurgen F.; de Ridder, Dick; Pronk, Jack T.; van Maris, Antonius J. A.; Daran, Jean-Marc

    2013-01-01

    Laboratory evolution of the yeast Saccharomyces cerevisiae in bioreactor batch cultures yielded variants that grow as multicellular, fast-sedimenting clusters. Knowledge of the molecular basis of this phenomenon may contribute to the understanding of natural evolution of multicellularity and to manipulating cell sedimentation in laboratory and industrial applications of S. cerevisiae. Multicellular, fast-sedimenting lineages obtained from a haploid S. cerevisiae strain in two independent evolution experiments were analyzed by whole genome resequencing. The two evolved cell lines showed different frameshift mutations in a stretch of eight adenosines in ACE2, which encodes a transcriptional regulator involved in cell cycle control and mother-daughter cell separation. Introduction of the two ace2 mutant alleles into the haploid parental strain led to slow-sedimenting cell clusters that consisted of just a few cells, thus representing only a partial reconstruction of the evolved phenotype. In addition to single-nucleotide mutations, a whole-genome duplication event had occurred in both evolved multicellular strains. Construction of a diploid reference strain with two mutant ace2 alleles led to complete reconstruction of the multicellular-fast sedimenting phenotype. This study shows that whole-genome duplication and a frameshift mutation in ACE2 are sufficient to generate a fast-sedimenting, multicellular phenotype in S. cerevisiae. The nature of the ace2 mutations and their occurrence in two independent evolution experiments encompassing fewer than 500 generations of selective growth suggest that switching between unicellular and multicellular phenotypes may be relevant for competitiveness of S. cerevisiae in natural environments. PMID:24145419

  3. Changes in P-glycoprotein activity are mediated by the growth of a tumour cell line as multicellular spheroids

    PubMed Central

    Valeria, Ponce de León; Raúl, Barrera-Rodríguez

    2005-01-01

    Background Expression of P-glycoprotein (P-gp), the multidrug resistance (MDR) 1 gene product, can lead to multidrug resistance in tumours. However, the physiological role of P-gp in tumours growing as multicellular spheroids is not well understood. Recent evidence suggests that P-gp activity may be modulated by cellular components such as membrane proteins, membrane-anchoring proteins or membrane-lipid composition. Since, multicellular spheroids studies have evidenced alterations in numerous cellular components, including those related to the plasma membrane function, result plausible that some of these changes might modulate P-gp function and be responsible for the acquisition of multicellular drug resistance. In the present study, we asked if a human lung cancer cell line (INER-51) grown as multicellular spheroids can modify the P-gp activity to decrease the levels of doxorubicin (DXR) retained and increase their drug resistance. Results Our results showed that INER-51 spheroids retain 3-folds lower doxorubicin than the same cells as monolayers however; differences in retention were not observed when the P-gp substrate Rho-123 was used. Interestingly, neither the use of the P-gp-modulating agent cyclosporin-A (Cs-A) nor a decrease in ATP-pools were able to increase DXR retention in the multicellular spheroids. Only the lack of P-gp expression throughout the pharmacological selection of a P-gp negative (P-gpneg) mutant clone (PSC-1) derived from INER-51 cells, allow increase of DXR retention in spheroids. Conclusion Thus, multicellular arrangement appears to alter the P-gp activity to maintain lower levels of DXR. However, the non expression of P-gp by cells forming multicellular spheroids has only a minor impact in the resistance to chemotherapeutic agents. PMID:16001980

  4. The Academic Half-Day redesigned: Improving generalism, promoting CanMEDS and developing self-directed learners

    PubMed Central

    Di Genova, Tanya; Valentino, Pamela L; Gosselin, Richard; Bhanji, Farhan

    2015-01-01

    BACKGROUND: The Montreal Children’s Hospital Pediatric Residency Program redesigned its Academic Half-Day based on program concerns consistent with the published literature. These concerns included inadequate preparation for general paediatric practice, gaps in CanMEDS education and exclusive use of didactic lectures. Novel instructional methods included monthly simulation sessions to learn CanMEDS competencies, increased use of general paediatricians as instructors, implementation of a ‘systems-based’ curriculum and development of self-directed learning skills through activities such as ‘Residents as Teachers’. METHOD: A postimplementation online survey was sent to all 18 residents who had been exposed to both curricula. The survey was designed to determine the impact of the new curriculum on their perceived ability to retain information and acquire the competencies of a general paediatrician, and to assess the effect on their self-directed learning. Responses were recorded on a five-point Likert scale ranging from ‘strongly disagree’ to ‘strongly agree’. RESULTS: Fourteen of 18 (78%) residents completed the survey. All residents preferred the ‘systems-based’ educational program. Seventy-nine percent of all residents agreed that the simulation sessions were an effective method of learning the CanMEDS competencies. Importantly, 64% of residents voluntarily read more about the topics presented and 71% agreed that they retained the content better. Moreover, 79% believed that changes made to the teaching curriculum better prepared them for a general paediatric practice and 64% of residents believed that it better ‘supplements’ learning in the clinical setting. CONCLUSION: The authors propose that the new curriculum is comprehensive, while developing the skills required for life-long learning as a general paediatrician. PMID:25722641

  5. Facilitators and barriers to informed choice in self-directed support for young people with disability in transition.

    PubMed

    Mitchell, Fraser

    2015-03-01

    The objective of this qualitative study was to explore the concept of 'informed choice' in the context of self-directed support (SDS) for young people with disability in transition from child to adult services. SDS is a major policy initiative introduced by the Scottish government to promote personalised services by redefining the relationship between the citizen and the state regarding social care supports. Informed choice is one of the underpinning principles of the Social Care (Self-directed Support) (Scotland) Act 2013. The theoretical approach to the research study was that of critical realism and, in particular, realistic evaluation. The research design used multiple qualitative methods involving secondary analysis of archived qualitative longitudinal interview data, and primary interviews with nine individuals, representing a wide range of stakeholders in Scotland. The study developed hypotheses concerning the facilitators and barriers to informed choice for young people with disability. Factors facilitating informed choice included supportive family and professional networks, advocacy, accessible information and experiential knowledge. Barriers to informed choice were seen to be low expectations, poor collaboration between child and adult services and bureaucratic organisational cultures. SDS is entering the implementation phase of the policy cycle in Scotland and this study will inform emerging policy, practice and future research into personalisation for young people with disability in transition. In particular, the findings point to the need to involve young people with disability at an early stage in choice-making, and to foster self-advocacy skills and supportive social networks. Informed choice for young people with disability needs to be seen as a process over time involving both information and emotions and both need to be supported to ensure successful transitions.

  6. External and internal factors influencing self-directed online learning of physiotherapy undergraduate students in Sweden: a qualitative study

    PubMed Central

    Hammarlund, Catharina Sjödahl; Nilsson, Maria H.; Gummesson, Christina

    2015-01-01

    Purpose: Online courses have become common in health sciences education. This learning environment can be designed using different approaches to support student learning. To further develop online environment, it is important to understand how students perceive working and learning online. The aim of this study is to identify aspects influencing students’ learning processes and their adaptation to self-directed learning online. Methods: Thirty-four physiotherapy students with a mean age of 25 years (range, 21 to 34 years) participated. Qualitative content analysis and triangulation was used when investigating the students’ self-reflections, written during a five week self-directed, problem-oriented online course. Results: Two categories emerged: ‘the influence of the structured framework’ and ‘communication and interaction with teachers and peers.’ The learning processes were influenced by external factors, e.g., a clear structure including a transparent alignment of assignments and assessment. Important challenges to over-come were primarily internal factors, e.g., low self-efficacy, difficulties to plan the work effectively and adapting to a new environment. Conclusion: The analyses reflected important perspectives targeting areas which enable further course development. The influences of external and internal factors on learning strategies and self-efficacy are important aspects to consider when designing online courses. Factors such as pedagogical design, clarity of purpose, goals, and guidelines were important as well as continuous opportunities for communication and collaboration. Further studies are needed to understand and scaffold the motivational factors among students with low self-efficacy. PMID:26101401

  7. Self-Directed Weight Loss Strategies: Energy Expenditure Due to Physical Activity Is Not Increased to Achieve Intended Weight Loss

    PubMed Central

    Elbelt, Ulf; Schuetz, Tatjana; Knoll, Nina; Burkert, Silke

    2015-01-01

    Reduced physical activity and almost unlimited availability of food are major contributors to the development of obesity. With the decline of strenuous work, energy expenditure due to spontaneous physical activity has attracted increasing attention. Our aim was to assess changes in energy expenditure, physical activity patterns and nutritional habits in obese subjects aiming at self-directed weight loss. Methods: Energy expenditure and physical activity patterns were measured with a portable armband device. Nutritional habits were assessed with a food frequency questionnaire. Results: Data on weight development, energy expenditure, physical activity patterns and nutritional habits were obtained for 105 patients over a six-month period from an initial cohort of 160 outpatients aiming at weight loss. Mean weight loss was −1.5 ± 7.0 kg (p = 0.028). Patients with weight maintenance (n = 75), with substantial weight loss (>5% body weight, n = 20) and with substantial weight gain (>5% body weight, n = 10) did not differ in regard to changes of body weight adjusted energy expenditure components (total energy expenditure: −0.2 kcal/kg/day; non-exercise activity thermogenesis: −0.3 kcal/kg/day; exercise-related activity thermogenesis (EAT): −0.2 kcal/kg/day) or patterns of physical activity (duration of EAT: −2 min/day; steps/day: −156; metabolic equivalent unchanged) measured objectively with a portable armband device. Self-reported consumption frequency of unfavorable food decreased significantly (p = 0.019) over the six-month period. Conclusions: An increase in energy expenditure or changes of physical activity patterns (objectively assessed with a portable armband device) are not employed by obese subjects to achieve self-directed weight loss. However, modified nutritional habits could be detected with the use of a food frequency questionnaire. PMID:26193310

  8. Proteus mirabilis mutants defective in swarmer cell differentiation and multicellular behavior.

    PubMed Central

    Belas, R; Erskine, D; Flaherty, D

    1991-01-01

    Proteus mirabilis is a dimorphic bacterium which exists in liquid cultures as a 1.5- to 2.0-microns motile swimmer cell possessing 6 to 10 peritrichous flagella. When swimmer cells are placed on a surface, they differentiate by a combination of events that ultimately produce a swarmer cell. Unlike the swimmer cell, the polyploid swarmer cell is 60 to 80 microns long and possesses hundreds to thousands of surface-induced flagella. These features, combined with multicellular behavior, allow the swarmer cells to move over a surface in a process called swarming. Transposon Tn5 was used to produce P. mirabilis mutants defective in wild-type swarming motility. Two general classes of mutants were found to be defective in swarming. The first class was composed of null mutants that were completely devoid of swarming motility. The majority of nonswarming mutations were the result of defects in the synthesis of flagella or in the ability to rotate the flagella. The remaining nonswarming mutants produced flagella but were defective in surface-induced elongation. Strains in the second general class of mutants, which made up more than 65% of all defects in swarming were motile but were defective in the control and coordination of multicellular swarming. Analysis of consolidation zones produced by such crippled mutants suggested that this pleiotropic phenotype was caused by a defect in the regulation of multicellular behavior. A possible mechanism controlling the cyclic process of differentiation and dediferentiation involved in the swarming behavior of P. mirabilis is discussed. Images PMID:1917860

  9. Differential penetration of targeting agents into multicellular spheroids derived from human neuroblastoma

    SciTech Connect

    Mairs, R.J.; Angerson, W.J.; Babich, J.W.; Murray, T. )

    1991-01-01

    The authors have used a multicellular tumour spheroid model for determination of the penetration of various targeting agents of potential use in the treatment of neuroblastoma. Both the radiopharmaceutical meta-iodobenzylguanidine (mIBG) and the {beta} subunit of nerve growth factor ({beta}-NGF) distributed uniformly throughout spheroids, though the latter was poorly concentrated relative to mIBG. In contrast, the anti-neuroectodermal monoclonal antibody. UJ13A bound only to peripheral cell layers with little accumulation in the spheroid interior. Differential penetration of targeting agents may influence the choice of conjugated radionuclide which is likely to achieve maximum therapeutic benefit.

  10. Multicellular natural convection of a low Prandlt number fluid between horizontal concentric cylinders

    SciTech Connect

    Joosik Yoo; Jun Young Choi; Moonuhn Kim . Dept. of Mechanical Engineering)

    1994-01-01

    Two-dimensional natural convection of a fluid of low Prandtl number (Pr = 0.02) in an annulus between two concentric horizontal cylinders is numerically investigated in a wide range of gap widths. For low Grashof numbers, a steady unicellular convection is obtained. Above a transition Grashof number that depends on the gap width, a steady bicellular flow occurs. With further increase of the Grashof number, steady or time-periodic multicellular convection occurs, and finally, complex unsteady convective flow appears. A plot is presented that predicts the type of flow patterns for various combination of gap widths and Grashof numbers.

  11. Examining tissue differentiation stability through large scale, multi-cellular pathway modeling.

    SciTech Connect

    May, Elebeoba Eni; Schiek, Richard Louis

    2005-03-01

    Using a multi-cellular, pathway model approach, we investigate the Drosophila sp. segmental differentiation network's stability as a function of initial conditions. While this network's functionality has been investigated in the absence of noise, this is the first work to specifically investigate how natural systems respond to random errors or noise. Our findings agree with earlier results that the overall network is robust in the absence of noise. However, when one includes random initial perturbations in intracellular protein WG levels, the robustness of the system decreases dramatically. The effect of noise on the system is not linear, and appears to level out at high noise levels.

  12. Anaerobic respiration using a complete oxidative TCA cycle drives multicellular swarming in Proteus mirabilis.

    PubMed

    Alteri, Christopher J; Himpsl, Stephanie D; Engstrom, Michael D; Mobley, Harry L T

    2012-10-30

    Proteus mirabilis rapidly migrates across surfaces using a periodic developmental process of differentiation alternating between short swimmer cells and elongated hyperflagellated swarmer cells. To undergo this vigorous flagellum-mediated motility, bacteria must generate a substantial proton gradient across their cytoplasmic membranes by using available energy pathways. We sought to identify the link between energy pathways and swarming differentiation by examining the behavior of defined central metabolism mutants. Mutations in the tricarboxylic acid (TCA) cycle (fumC and sdhB mutants) caused altered patterns of swarming periodicity, suggesting an aerobic pathway. Surprisingly, the wild-type strain swarmed on agar containing sodium azide, which poisons aerobic respiration; the fumC TCA cycle mutant, however, was unable to swarm on azide. To identify other contributing energy pathways, we screened transposon mutants for loss of swarming on sodium azide and found insertions in the following genes that involved fumarate metabolism or respiration: hybB, encoding hydrogenase; fumC, encoding fumarase; argH, encoding argininosuccinate lyase (generates fumarate); and a quinone hydroxylase gene. These findings validated the screen and suggested involvement of anaerobic electron transport chain components. Abnormal swarming periodicity of fumC and sdhB mutants was associated with the excretion of reduced acidic fermentation end products. Bacteria lacking SdhB were rescued to wild-type pH and periodicity by providing fumarate, independent of carbon source but dependent on oxygen, while fumC mutants were rescued by glycerol, independent of fumarate only under anaerobic conditions. These findings link multicellular swarming patterns with fumarate metabolism and membrane electron transport using a previously unappreciated configuration of both aerobic and anaerobic respiratory chain components. Bacterial locomotion and the existence of microbes were the first scientific

  13. [Self-organization in the ontogeny of multicellular organisms: a computer simulation].

    PubMed

    Markov, M A; Markov, A V

    2011-01-01

    The progress in understanding the patterns of evolution of ontogeny is hindered by the fact that many features of ontogeny are counterintuitive (as well as the features of other processes related to self-organization, self-assembly, and spontaneous increase in complexity). The basic principle of ontogeny of multicellular organisms is that it is the process of self-assembly of ordered multicellular structures by means of coordinated behavior of many individual modules (cells), each of which follows the same set of"rules" encoded in the genome. These rules are based on the genetic regulatory networks. We hypothesize that many specific features of ontogeny that seem nontrivial or enigmatic are, in fact, the inevitable consequences of this basic principle. If so, they do not need special explanations. In order to verify this hypothesis, we developed the computer program "Evo-Devo" based on the above principle. The program is designed to model the self-assembly of ordered multicellular structures from an aggregation of dividing cells that originate from a single original cell (zygote). Each cell follows a set of rules of behavior ("genotype") that can be specified arbitrarily by the experimenter, and is the same for all cells in the embryo (each cell is programmed in exactly the same way as all other cells). It is not allowed to specify rules for groups of cells or for the whole embryo: only local rules that should be followed at the level of a single cell are possible. The analysis of phenotypic implementation of different genotypes revealed several features which are present in the ontogeny of real organisms and are regularly reproduced in the model. These include: inherent stochasticity; inescapable necessity of development of stabilizing adaptations based on negative feedback in order to decrease this stochasticity; equifinality (noise resistance) resulting from these adaptations; the ability of ontogeny to respond to major perturbations by generating new

  14. Non-suicidal self-injury and other self-directed violent behaviors in India: A review of definitions and research.

    PubMed

    Gandhi, Amarendra; Luyckx, Koen; Maitra, Shubhada; Claes, Laurence

    2016-08-01

    The interpersonal theory of suicide suggests that most forms of self-directed violent behaviors lie on a continuum, with each behavior successively increasing the capability of committing suicide. There is increasing evidence to suggest that the continuum may begin with Non-Suicidal Self-Injury (NSSI). This theory can be important in developing interventions for suicide prevention. However, in India, consistent usage of definitions of various forms of self-directed violent behaviors is lacking. In the present study, we reviewed definitions of various forms of self-directed violent behaviors that have been investigated in India. Further, we compared the usage of these definitions with the usage by WHO. Additionally, we reviewed NSSI research in India. Thirty-eight publications were identified by a comprehensive electronic search undertaken in Indian psychiatry, psychology, and mental health-related databases. Inconsistent definitions of eight self-directed violent behaviors were observed in Indian literature. Agreement on consistent definitions of various forms of self-directed behaviors is essential. Based on the findings of the current review, it can be suggested that culturally relevant large-scale research on NSSI in India is required to confirm the limited evidence that suggests high prevalence of NSSI in India.

  15. Symplasmata are a clonal, conditional, and reversible type of bacterial multicellularity

    PubMed Central

    Tecon, Robin; Leveau, Johan H. J.

    2016-01-01

    Microorganisms are capable of remarkable social behaviours, such as forming transient multicellular assemblages with properties and adaptive abilities exceeding those of individual cells. Here, we report on the formation and structure of genets known as symplasmata produced by Pantoea eucalypti bacteria. Each symplasmatum develops clonally and stochastically from a single bacterium into a membrane-delimited, capsule-embedded cluster of progeny cells and with a frequency that depends on temperature, pH, and nutrient availability. Transposon mutagenesis identified several gene products required for symplasmata formation, including master regulator LrhA, replication inhibitor CspD, polysaccharide transporter RfbX3, and autoinducer synthase PhzI. We also show that bacteria inside symplasmata are shaped irregularly with punctuated cell-to-cell contacts, metabolically responsive to environmental stimuli, dispersal-ready, and transcriptionally reprogrammed to anticipate multiple alternative futures in terms of carbon source availability. The structured and conditionable nature of symplasmata offers exciting prospects towards a mechanistic understanding of multicellular behaviours and their ecological significance. PMID:27534795

  16. Quantification of Multicellular Organization, Junction Integrity, and Substrate Features in Collective Cell Migration.

    PubMed

    Canver, Adam C; Morss Clyne, Alisa

    2017-02-01

    Quantitative analysis of multicellular organization, cell-cell junction integrity, and substrate properties is essential to understand the mechanisms underlying collective cell migration. However, spatially and temporally defining these properties is difficult within collectively migrating cell groups due to challenges in accurate cell segmentation within the monolayer. In this paper, we present Matlab®-based algorithms to spatially quantify multicellular organization (migration distance, interface roughness, and cell alignment, area, and morphology), cell-cell junction integrity, and substrate features in confocal microscopy images of two-dimensional collectively migrating endothelial monolayers. We used novel techniques, including measuring the migrating front roughness using a parametric curve formulation, automatically binning cells to obtain data as a function of distance from the migrating front, using iterative morphological closings to fully define cell boundaries, quantifying β-catenin localization as a measure of cell-cell junction integrity, and skeletonizing fibronectin to determine fiber length and orientation. These algorithms are widely accessible, as they use common fluorescent markers and Matlab® functions, and provide high-throughput critical feature quantification within collectively migrating cell groups. These image analysis algorithms can help standardize feature quantification among different experimental techniques, cell types, and research groups studying collective cell migration.

  17. Bottom-up proteomic analysis of single HCT 116 colon carcinoma multicellular spheroids

    PubMed Central

    Feist, Peter; Sun, Liangliang; Liu, Xin; Dovichi, Norman J.; Hummon, Amanda B.

    2016-01-01

    Rationale Proteomic analysis of single multicellular spheroids has not been previously reported. As three-dimensional cell cultures are an increasingly popular model system for biological research, there is interest in obtaining proteomic profiles of these samples. We investigated the proteome of single HCT 116 multicellular spheroids using protocols optimized for small sample sizes. Methods Six biological replicates were analyzed via microscopy for size. Total protein content was assessed via the bicinchoninic acid assay (BCA assay). Five separate biological replicate spheroids were analyzed via mass spectrometry in technical duplicate. An ultra-performance liquid chromatography (UPLC) system coupled with an LTQ Orbitrap Velos was used for peptide separation, analysis, and identification. Results The average diameter of six replicate HCT 116 spheroids was 940 ± 30 μm and the average total protein amount was determined to be 39 ± 4 μg. At least 1300 protein groups were identified in each single LC-MS/MS run with ten percent of the material from single spheroid loaded. Database search results showed variation between spheroid protein group identifications. Pearson correlations show that the disparity in identifications is due to random variations in spectra and protocol. Conclusions We detected more than 1350 protein groups in each replicate HCT 116 spheroid. While some variation was detected between replicates, differences in the number of protein groups identified were determined to be the result of random variations in mass spectra acquisition. PMID:26212283

  18. Ability of multicellular salt glands in Tamarix species to secrete Na+ and K+ selectively.

    PubMed

    Ma, Haiyan; Tian, Changyan; Feng, Gu; Yuan, Junfeng

    2011-03-01

    The present study aimed to determine the mechanism of cation-selective secretion by multicellular salt glands. Using a hydroponic culture system, the secretion and accumulation of Na(+) and K(+) in Tamarix ramosissima and T. laxa under different salt stresses (NaCl, KCl and NaCl+KCl) were studied. Additionally, the effects of salt gland inhibitors (orthovanadate, Ba(2+), ouabain, tetraethylammonium (TEA) and verapamil) on Na(+) and K(+) secretion and accumulation were examined. Treatment with NaCl (at 0-200 mmol L(-1) levels) significantly increased Na(+) secretion, whereas KCl treatment (at 0-200 mmol L(-1) levels) significantly increased K(+) secretion. The ratio of secretion to accumulation of Na(+) was higher than that of K(+). The changes in Na(+) and K(+) secretion differed after adding different ions into the single-salt solutions. Addition of NaCl to the KCl solution (at 100 mmol L(-1) level, respectively) led to a significant decrease in K(+) secretion rate, whereas addition of KCl to the NaCl solution (at 100 mmol L(-1) level, respectively) had little impact on the Na(+) secretion rate. These results indicated that Na+ secretion in Tamarix was highly selective. In addition, Na(+) secretion was significantly inhibited by orthovanadate, ouabain, TEA and verapamil, and K(+) secretion was significantly inhibited by ouabain, TEA and verapamil. The different impacts of orthovanadate on Na(+) and K(+) secretion might be the primary cause for the different Na(+) and K(+) secretion abilities of multicellular salt glands in Tamarix.

  19. Symplasmata are a clonal, conditional, and reversible type of bacterial multicellularity

    SciTech Connect

    Tecon, Robin; Leveau, Johan H. J.

    2016-08-18

    Microorganisms are capable of remarkable social behaviours, such as forming transient multicellular assemblages with properties and adaptive abilities exceeding those of individual cells. Here, we report on the formation and structure of genets known as symplasmata produced by Pantoea eucalypti bacteria. Each symplasmatum develops clonally and stochastically from a single bacterium into a membrane-delimited, capsule-embedded cluster of progeny cells and with a frequency that depends on temperature, pH, and nutrient availability. Transposon mutagenesis identified several gene products required for symplasmata formation, including master regulator LrhA, replication inhibitor CspD, polysaccharide transporter RfbX3, and autoinducer synthase PhzI. We also show that bacteria inside symplasmata are shaped irregularly with punctuated cell-to-cell contacts, metabolically responsive to environmental stimuli, dispersal-ready, and transcriptionally reprogrammed to anticipate multiple alternative futures in terms of carbon source availability. In conclusion, the structured and conditionable nature of symplasmata offers exciting prospects towards a mechanistic understanding of multicellular behaviours and their ecological significance.

  20. Coherent angular motion in the establishment of multicellular architecture of glandular tissues

    PubMed Central

    Tanner, Kandice; Mori, Hidetoshi; Mroue, Rana; Bruni-Cardoso, Alexandre; Bissell, Mina J.

    2012-01-01

    Glandular tissues form ducts (tubes) and acini (spheres) in multicellular organisms. This process is best demonstrated in the organization of the ductal tree of the mammary gland and in 3D models of morphogenesis in culture. Here, we asked a fundamental question: How do single adult epithelial cells generate polarized acini when placed in a surrogate basement membrane 3D gel? Using human breast epithelial cells from either reduction mammoplasty or nonmalignant breast cell lines, we observed a unique cellular movement where single cells undergo multiple rotations and then maintain it cohesively as they divide to assemble into acini. This coherent angular motion (CAMo) was observed in both primary cells and breast cell lines. If CAMo was disrupted, the final geometry was not a sphere. The malignant counterparts of the human breast cell lines in 3D were randomly motile, did not display CAMo, and did not form spheres. Upon “phenotypic reversion” of malignant cells, both CAMo and spherical architecture were restored. We show that cell-cell adhesion and tissue polarity are essential for the formation of acini and link the functional relevance of CAMo to the establishment of spherical architecture rather than to multicellular aggregation or growth. We propose that CAMo is an integral step in the formation of the tissue architecture and that its disruption is involved in malignant transformation. PMID:22308439

  1. Inter-cell interference mitigation in multi-cellular visible light communications.

    PubMed

    Jung, Sun-Young; Kwon, Do-Hoon; Yang, Se-Hoon; Han, Sang-Kook

    2016-04-18

    Inter-cell interference hinders multi-cellular optical wireless communication to support various applications. We proposed and experimentally demonstrated a multicarrier-based cell partitioning scheme, combined with frequency reuse, which could be effective in optical communications although it is inefficient in RF wireless communications. For multicarrier-based cell partitioning, Orthogonal frequency division multiplexing-based multiple access (OFDMA) was employed to accommodate multi-cellular optical wireless communications without a large guard band between adjacent cells and without additional RF components. Moreover, we employed filter bank-based multicarrier (FBMC) to mitigate inter-cell interference generated in OFDMA-based cell partitioning due to asynchronous signals originated from RF path difference. By using FBMC-based cell partitioning, inter-cell interference could be effectively mitigated as well as capacity and spectral efficiency were improved about 1.5 times compared to those of OFDMA. Because no cyclic prefix (CP) is required in FBMC, the improvement factor could be increased if there is a large RF path difference between lighting cells. Moreover, it could be a stronger solution when many neighboring cells exist causing large interference. The proposed multicarrier-based cell partitioning combined with FBMC will effectively support visible light communication (VLC)-based localization-based services (LBS) and indoor positioning system by transparently providing trilateration-based positioning method.

  2. Dissolved Gases and Ice Fracturing During the Freezing of a Multicellular Organism: Lessons from Tardigrades

    PubMed Central

    Kletetschka, Gunther; Hruba, Jolana

    2015-01-01

    Abstract Three issues are critical for successful cryopreservation of multicellular material: gases dissolved in liquid, thermal conductivity of the tissue, and localization of microstructures. Here we show that heat distribution is controlled by the gas amount dissolved in liquids and that when changing the liquid into solid, the dissolved gases either form bubbles due to the absence of space in the lattice of solids and/or are migrated toward the concentrated salt and sugar solution at the cost of amount of heat required to be removed to complete a solid-state transition. These factors affect the heat distribution in the organs to be cryopreserved. We show that the gas concentration issue controls fracturing of ice when freezing. There are volumetric changes not only when changing the liquid into solid (volume increases) but also reduction of the volume when reaching lower temperatures (volume decreases). We discuss these issues parallel with observations of the cryosurvivability of multicellular organisms, tardigrades, and discuss their analogy for cryopreservation of large organs. PMID:26309797

  3. Kelps feature systemic defense responses: insights into the evolution of innate immunity in multicellular eukaryotes.

    PubMed

    Thomas, François; Cosse, Audrey; Le Panse, Sophie; Kloareg, Bernard; Potin, Philippe; Leblanc, Catherine

    2014-11-01

    Brown algae are one of the few eukaryotic lineages that have evolved complex multicellularity, together with Opisthokonts (animals, fungi) and Plantae (land plants, green and red algae). In these three lineages, biotic stresses induce similar local defense reactions. Animals and land plants also feature a systemic immune response, protecting the whole organism after an attack on one of its parts. However, the occurrence of systemic defenses has never been investigated in brown algae. We elicited selected parts of the kelp Laminaria digitata and monitored distant, nonchallenged areas of the same individual for subsequent defense reactions. A systemic reaction was detected following elicitation on a distant area, including an oxidative response, an increase in haloperoxidase activities and a stronger resistance against herbivory. Based on experiments with pharmacological inhibitors, the liberation of free fatty acids is proposed to play a key role in systemic signaling, reminiscent of what is known in land plants. This study is the first report, outside the phyla of Opisthokonts and Plantae, of an intraorganism communication leading to defense reactions. These findings indicate that systemic immunity emerged independently at least three times, as a consequence of convergent evolution in multicellular eukaryotic lineages.

  4. Inter-Specific Coral Chimerism: Genetically Distinct Multicellular Structures Associated with Tissue Loss in Montipora capitata

    PubMed Central

    Work, Thierry M.; Forsman, Zac H.; Szabó, Zoltán; Lewis, Teresa D.; Aeby, Greta S.; Toonen, Robert J.

    2011-01-01

    Montipora white syndrome (MWS) results in tissue-loss that is often lethal to Montipora capitata, a major reef building coral that is abundant and dominant in the Hawai'ian Archipelago. Within some MWS-affected colonies in Kane'ohe Bay, Oahu, Hawai'i, we saw unusual motile multicellular structures within gastrovascular canals (hereafter referred to as invasive gastrovascular multicellular structure-IGMS) that were associated with thinning and fragmentation of the basal body wall. IGMS were in significantly greater densities in coral fragments manifesting tissue-loss compared to paired normal fragments. Mesenterial filaments from these colonies yielded typical M. capitata mitochondrial haplotypes (CO1, CR), while IGMS from the same colony consistently yielded distinct haplotypes previously only found in a different Montipora species (Montipora flabellata). Protein profiles showed consistent differences between paired mesenterial filaments and IGMS from the same colonies as did seven microsatellite loci that also exhibited an excess of alleles per locus inconsistent with a single diploid organism. We hypothesize that IGMS are a parasitic cellular lineage resulting from the chimeric fusion between M. capitata and M. flabellata larvae followed by morphological reabsorption of M. flabellata and subsequent formation of cell-lineage parasites. We term this disease Montiporaiasis. Although intra-specific chimerism is common in colonial animals, this is the first suspected inter-specific example and the first associated with tissue loss. PMID:21829541

  5. Symplasmata are a clonal, conditional, and reversible type of bacterial multicellularity

    DOE PAGES

    Tecon, Robin; Leveau, Johan H. J.

    2016-08-18

    Microorganisms are capable of remarkable social behaviours, such as forming transient multicellular assemblages with properties and adaptive abilities exceeding those of individual cells. Here, we report on the formation and structure of genets known as symplasmata produced by Pantoea eucalypti bacteria. Each symplasmatum develops clonally and stochastically from a single bacterium into a membrane-delimited, capsule-embedded cluster of progeny cells and with a frequency that depends on temperature, pH, and nutrient availability. Transposon mutagenesis identified several gene products required for symplasmata formation, including master regulator LrhA, replication inhibitor CspD, polysaccharide transporter RfbX3, and autoinducer synthase PhzI. We also show that bacteriamore » inside symplasmata are shaped irregularly with punctuated cell-to-cell contacts, metabolically responsive to environmental stimuli, dispersal-ready, and transcriptionally reprogrammed to anticipate multiple alternative futures in terms of carbon source availability. In conclusion, the structured and conditionable nature of symplasmata offers exciting prospects towards a mechanistic understanding of multicellular behaviours and their ecological significance.« less

  6. Stigmergy co-ordinates multicellular collective behaviours during Myxococcus xanthus surface migration

    PubMed Central

    Gloag, Erin S.; Turnbull, Lynne; Javed, Muhammad A.; Wang, Huabin; Gee, Michelle L.; Wade, Scott A.; Whitchurch, Cynthia B.

    2016-01-01

    Surface translocation by the soil bacterium Myxococcus xanthus is a complex multicellular phenomenon that entails two motility systems. However, the mechanisms by which the activities of individual cells are coordinated to manifest this collective behaviour are currently unclear. Here we have developed a novel assay that enables detailed microscopic examination of M. xanthus motility at the interstitial interface between solidified nutrient medium and a glass coverslip. Under these conditions, M. xanthus motility is characterised by extensive micro-morphological patterning that is considerably more elaborate than occurs at an air-surface interface. We have found that during motility on solidified nutrient medium, M. xanthus forges an interconnected furrow network that is lined with an extracellular matrix comprised of exopolysaccharides, extracellular lipids, membrane vesicles and an unidentified slime. Our observations have revealed that M. xanthus motility on solidified nutrient medium is a stigmergic phenomenon in which multi-cellular collective behaviours are co-ordinated through trail-following that is guided by physical furrows and extracellular matrix materials. PMID:27225967

  7. In vitro spatially organizing the differentiation in individual multicellular stem cell aggregates.

    PubMed

    Qi, Hao; Huang, Guoyou; Han, Yu Long; Lin, Wang; Li, Xiujun; Wang, Shuqi; Lu, Tian Jian; Xu, Feng

    2016-01-01

    With significant potential as a robust source to produce specific somatic cells for regenerative medicine, stem cells have attracted increasing attention from both academia and government. In vivo, stem cell differentiation is a process under complicated regulations to precisely build tissue with unique spatial structures. Since multicellular spheroidal aggregates of stem cells, commonly called as embryoid bodies (EBs), are considered to be capable of recapitulating the events in early stage of embryonic development, a variety of methods have been developed to form EBs in vitro for studying differentiation of embryonic stem cells. The regulation of stem cell differentiation is crucial in directing stem cells to build tissue with the correct spatial architecture for specific functions. However, stem cells within the three-dimensional multicellular aggregates undergo differentiation in a less unpredictable and spatially controlled manner in vitro than in vivo. Recently, various microengineering technologies have been developed to manipulate stem cells in vitro in a spatially controlled manner. Herein, we take the spotlight on these technologies and researches that bring us the new potential for manipulation of stem cells for specific purposes.

  8. Inter-specific coral chimerism: Genetically distinct multicellular structures associated with tissue loss in Montipora capitata

    USGS Publications Warehouse

    Work, Thierry M.; Forsman, Zac H.; Szabo, Zoltan; Lewis, Teresa D.; Aeby, Greta S.; Toonen, Robert J.

    2011-01-01

    Montipora white syndrome (MWS) results in tissue-loss that is often lethal to Montipora capitata, a major reef building coral that is abundant and dominant in the Hawai'ian Archipelago. Within some MWS-affected colonies in Kane'ohe Bay, Oahu, Hawai'i, we saw unusual motile multicellular structures within gastrovascular canals (hereafter referred to as invasive gastrovascular multicellular structure-IGMS) that were associated with thinning and fragmentation of the basal body wall. IGMS were in significantly greater densities in coral fragments manifesting tissue-loss compared to paired normal fragments. Mesenterial filaments from these colonies yielded typical M. capitata mitochondrial haplotypes (CO1, CR), while IGMS from the same colony consistently yielded distinct haplotypes previously only found in a different Montipora species (Montipora flabellata). Protein profiles showed consistent differences between paired mesenterial filaments and IGMS from the same colonies as did seven microsatellite loci that also exhibited an excess of alleles per locus inconsistent with a single diploid organism. We hypothesize that IGMS are a parasitic cellular lineage resulting from the chimeric fusion between M. capitata and M. flabellata larvae followed by morphological reabsorption of M. flabellata and subsequent formation of cell-lineage parasites. We term this disease Montiporaiasis. Although intra-specific chimerism is common in colonial animals, this is the first suspected inter-specific example and the first associated with tissue loss.

  9. A parallel implementation of an off-lattice individual-based model of multicellular populations

    NASA Astrophysics Data System (ADS)

    Harvey, Daniel G.; Fletcher, Alexander G.; Osborne, James M.; Pitt-Francis, Joe

    2015-07-01

    As computational models of multicellular populations include ever more detailed descriptions of biophysical and biochemical processes, the computational cost of simulating such models limits their ability to generate novel scientific hypotheses and testable predictions. While developments in microchip technology continue to increase the power of individual processors, parallel computing offers an immediate increase in available processing power. To make full use of parallel computing technology, it is necessary to develop specialised algorithms. To this end, we present a parallel algorithm for a class of off-lattice individual-based models of multicellular populations. The algorithm divides the spatial domain between computing processes and comprises communication routines that ensure the model is correctly simulated on multiple processors. The parallel algorithm is shown to accurately reproduce the results of a deterministic simulation performed using a pre-existing serial implementation. We test the scaling of computation time, memory use and load balancing as more processes are used to simulate a cell population of fixed size. We find approximate linear scaling of both speed-up and memory consumption on up to 32 processor cores. Dynamic load balancing is shown to provide speed-up for non-regular spatial distributions of cells in the case of a growing population.

  10. A model for the origin of group reproduction during the evolutionary transition to multicellularity.

    PubMed

    Maliet, Odile; Shelton, Deborah E; Michod, Richard E

    2015-06-01

    During the evolution of multicellular organisms, the unit of selection and adaptation, the individual, changes from the single cell to the multicellular group. To become individuals, groups must evolve a group life cycle in which groups reproduce other groups. Investigations into the origin of group reproduction have faced a chicken-and-egg problem: traits related to reproduction at the group level often appear both to be a result of and a prerequisite for natural selection at the group level. With a focus on volvocine algae, we model the basic elements of the cell cycle and show how group reproduction can emerge through the coevolution of a life-history trait with a trait underpinning cell cycle change. Our model explains how events in the cell cycle become reordered to create a group life cycle through continuous change in the cell cycle trait, but only if the cell cycle trait can coevolve with the life-history trait. Explaining the origin of group reproduction helps us understand one of life's most familiar, yet fundamental, aspects-its hierarchical structure.

  11. Dissolved Gases and Ice Fracturing During the Freezing of a Multicellular Organism: Lessons from Tardigrades.

    PubMed

    Kletetschka, Gunther; Hruba, Jolana

    2015-01-01

    Three issues are critical for successful cryopreservation of multicellular material: gases dissolved in liquid, thermal conductivity of the tissue, and localization of microstructures. Here we show that heat distribution is controlled by the gas amount dissolved in liquids and that when changing the liquid into solid, the dissolved gases either form bubbles due to the absence of space in the lattice of solids and/or are migrated toward the concentrated salt and sugar solution at the cost of amount of heat required to be removed to complete a solid-state transition. These factors affect the heat distribution in the organs to be cryopreserved. We show that the gas concentration issue controls fracturing of ice when freezing. There are volumetric changes not only when changing the liquid into solid (volume increases) but also reduction of the volume when reaching lower temperatures (volume decreases). We discuss these issues parallel with observations of the cryosurvivability of multicellular organisms, tardigrades, and discuss their analogy for cryopreservation of large organs.

  12. Optical signature of multicellular tumor spheroid using index-mismatch-induced spherical aberrations

    NASA Astrophysics Data System (ADS)

    Le Corre, G.; Weiss, P.; Ducommun, B.; Lorenzo, C.

    2014-02-01

    The development of new cancer treatments and the early prediction of their therapeutic potential are often made difficult by the lack of predictive pharmacological models. The 3D multicellular tumor spheroid (MCTS) model offers a level of complexity that recapitulates the three-dimensional organization of a tumor and appears to be fairly predictive of therapeutic efficiency. The use of spheroids in large-scale automated screening was recently reported to link the power of a high throughput analysis to the predictability of a 3D cell model. The spheroid has a radial symmetry; this simple geometry allows establishing a direct correlation between structure and function. The outmost layers of MCTS are composed of proliferating cells and form structurally uniform domain with an approximate thickness of 100 microns. The innermost layers are composed of quiescent cells. Finally, cells in the center of the spheroid can form a necrotic core. This latest region is structurally heterogeneous and is poorly characterized. These features make the spheroid a model of choice and a paradigm to study the optical properties of various epithelial tissues. In this study, we used an in-vitro optical technique for label-free characterization of multicellular systems based on the index- mismatch induced spherical aberrations. We achieve to monitor and characterize the optical properties of MCTS. This new and original approach might be of major interest for the development of innovative screening strategies dedicated to the identification of anticancer drugs.

  13. Self-Directed Ostensions and Mediations of the Adult at the Age of 8-, 12- and 16 months.

    PubMed

    Dupertuis, Virginie; Moro, Christiane

    2016-12-01

    One of Vygotsky's main insights was to highlight the role of linguistic signs in psychological development. In this paper, following the works carried out through the Object Pragmatics paradigm, which is grounded in Vygotsky's cultural-historical and semiotic framework, we will explore non verbal signs addressed toward herself by the infant in the process of communication toward oneself, in relation to the appropriation of the objects' canonical uses by infants at 8-, 12- and 16 months in triadic infant-object-adult interaction. More specifically, our focus will concern the development of self-directed ostensions. We will examine how this movement, under the impulse related to other's people signs and public meanings of the object, endorse the status of sign during development and specifies itself in ostension. Ostension as a sign refers to a presentation of an object to someone and has been initially defined within the framework of communication toward other people in semiotic literature. In our works, this sign is studied in communication toward oneself and in its development. It should be noted that very few studies have been done on this topic. Following Vygotsky, we consider that turned toward oneself, ostension plays a crucial role in the formation of thought and consciousness (in the sense of awareness). This paper will focus on the social and semiotic conditions of production of this sign and, more precisely, on the role of the adult's non verbal and verbal mediations, which aim to elicit and sustain its realisation by the infant.

  14. Enhancement of couples' communication and dyadic coping by a self-directed approach: a randomized controlled trial.

    PubMed

    Bodenmann, Guy; Hilpert, Peter; Nussbeck, Fridtjof W; Bradbury, Thomas N

    2014-08-01

    Although prevention of relationship distress and dissolution has potential to strengthen the well-being of partners and any children they are raising, dissemination of prevention programs can be limited because couples face many barriers to in-person participation. An alternative strategy, providing couples with an instructional DVD, is tested in the present study, in which 330 Caucasian couples (N = 660 participants; mean age: men 41.4 years, women 40.0 years) were randomly assigned to a DVD group without any further support, a DVD group with technical telephone coaching, or a wait-list control group. Couples completed questionnaires at pretest, posttest, and 3 and 6 months after completion of the intervention. Self-report measures of dyadic coping, communication quality, ineffective arguing, and relationship satisfaction were used to test whether the intervention groups improved in comparison with the control group. Women in both intervention groups increased in dyadic coping, reduced conflict behavior, and were more satisfied with their relationship 6 months after the intervention. Effects for men were mixed. Participants with poorer skills reported stronger improvement. Intimate relationships can, within limits, be positively influenced by a self-directed approach. Effective dissemination of principles underlying successful relationships can be facilitated through the use of emerging low-cost tools and technologies.

  15. The relevance of moral norms in distinct relational contexts: Purity versus harm norms regulate self-directed actions

    PubMed Central

    Dungan, James A.; Chakroff, Alek; Young, Liane

    2017-01-01

    Recent efforts to partition the space of morality have focused on the descriptive content of distinct moral domains (e.g., harm versus purity), or alternatively, the relationship between the perpetrator and victim of moral violations. Across three studies, we demonstrate that harm and purity norms are relevant in distinct relational contexts. Moral judgments of purity violations, compared to harm violations, are relatively more sensitive to the negative impact perpetrators have on themselves versus other victims (Study 1). This pattern replicates across a wide array of harm and purity violations varying in severity (Studies 2 and 3). Moreover, while perceptions of harm predict moral judgment consistently across relational contexts, perceptions of purity predict moral judgment more for self-directed actions, where perpetrators violate themselves, compared to dyadic actions, where perpetrators violate other victims (Study 3). Together, these studies reveal how an action’s content and its relational context interact to influence moral judgment, providing novel insights into the adaptive functions of harm and purity norms. PMID:28278214

  16. The relevance of moral norms in distinct relational contexts: Purity versus harm norms regulate self-directed actions.

    PubMed

    Dungan, James A; Chakroff, Alek; Young, Liane

    2017-01-01

    Recent efforts to partition the space of morality have focused on the descriptive content of distinct moral domains (e.g., harm versus purity), or alternatively, the relationship between the perpetrator and victim of moral violations. Across three studies, we demonstrate that harm and purity norms are relevant in distinct relational contexts. Moral judgments of purity violations, compared to harm violations, are relatively more sensitive to the negative impact perpetrators have on themselves versus other victims (Study 1). This pattern replicates across a wide array of harm and purity violations varying in severity (Studies 2 and 3). Moreover, while perceptions of harm predict moral judgment consistently across relational contexts, perceptions of purity predict moral judgment more for self-directed actions, where perpetrators violate themselves, compared to dyadic actions, where perpetrators violate other victims (Study 3). Together, these studies reveal how an action's content and its relational context interact to influence moral judgment, providing novel insights into the adaptive functions of harm and purity norms.

  17. A Mixed-Method Study of Mobile Devices and Student Self-Directed Learning and Achievement during a Middle School STEM Activity

    ERIC Educational Resources Information Center

    Bartholomew, Scott

    2016-01-01

    With the increasingly ubiquitous nature of mobile devices among K-12 students, many argue for and against the inclusion of these devices in K-12 classrooms. Arguments in favor cite instant access to information and collaboration with others as positive affordances made possible through mobile devices. Self-directed learning, a process where…

  18. A Study of the Effects of Self-Directed Activity Upon Quantity, Quality, and Variety of Responses in a Group Directed Reading-Thinking Activity.

    ERIC Educational Resources Information Center

    Anderson, William Warner

    Many behavioral theorists have suggested that self-directed activity is central to the learning process (e.g., Dewey, Piaget, Wertheimer). Accordingly, it was predicted that such activity bears a significant positive relationship to the quantity, quality, and variety of responses in a reading lesson. Moreover, it was expected that selected…

  19. Preclinical Students' Predispositions towards Social Forms of Instruction and Self-Directed Learning: A Challenge for the Development of Autonomous and Collaborative Learners

    ERIC Educational Resources Information Center

    Raidal, S. L.; Volet, S. E.

    2009-01-01

    Self-directed and social forms of learning are fundamentally different from traditional didactic educational settings from which students are selected for veterinary, medical and other professional degree courses. It is therefore expected that a mismatch may emerge between students' conceptions of effective learning and expectations inherent to…

  20. The Investigation of the Level of Self-Directed Learning Readiness According to the Locus of Control and Personality Traits of Preschool Teacher Candidates

    ERIC Educational Resources Information Center

    Balaban Dagal, Asude; Bayindir, Dilan

    2016-01-01

    The aim of this study is to investigate the relationship between the level of self-directed learning readiness, locus of control and the personality traits of preschool teacher candidates. The survey method was used for this study. The study group consisted of 151 teacher candidates who volunteered to participate in the study from Preschool…

  1. Perceptions of Self-Determination by Special Education and Rehabilitation Practitioners Based on Viewing a Self-Directed IEP versus an External-Directed IEP Meeting

    ERIC Educational Resources Information Center

    Branding, Dave; Bates, Paul; Miner, Craig

    2009-01-01

    This study investigated perception of self-determination by special education and rehabilitation practitioners following their exposure to a videotaped simulation of a self-directed IEP meeting and an external-directed IEP meeting involving an adolescent with mild mental retardation. Groups of special education practitioners and rehabilitation…

  2. The Role of Self-Reflection, Emotional Management of Feedback, and Self-Regulation Processes in Self-Directed Leadership Development

    ERIC Educational Resources Information Center

    Nesbit, Paul L.

    2012-01-01

    This article presents and explores a framework of self-directed leadership development (SDLD) to advance conceptual understanding and practical applications for self-development approaches to development of leaders in organizations. Drawing on a diversified literature associated with experiential learning, emotion research, and social cognitive…

  3. Let's Tweet in Chinese! Exploring How Learners of Chinese as a Foreign Language Self-Direct Their Use of Microblogging to Learn Chinese

    ERIC Educational Resources Information Center

    Hsiao, Ya Ping; Broeder, Peter

    2014-01-01

    Twitter is becoming increasingly popular as a medium for language learning. This study explores self-directed learning via social interactions that use Twitter as an interactive learning environment. The participants in this study were thirty university students of Chinese as a foreign language at levels 1 and 2 of the "Hanyu Shuiping…

  4. Training Language Teachers to Sustain Self-Directed Language Learning: An Exploration of Advisers' Experiences on a Web-Based Open Virtual Learning Environment

    ERIC Educational Resources Information Center

    Bailly, Sophie; Ciekanski, Maud; Guély-Costa, Eglantine

    2013-01-01

    This article describes the rationale for pedagogical, technological and organizational choices in the design of a web-based and open virtual learning environment (VLE) promoting and sustaining self-directed language learning. Based on the last forty years of research on learner autonomy at the CRAPEL according to Holec's definition (1988), we…

  5. The Use of a Self-Directed Learning Program to Provide Introductory Training in Pivotal Response Treatment to Parents of Children with Autism

    ERIC Educational Resources Information Center

    Nefdt, Nicolette; Koegel, Robert; Singer, George; Gerber, Michael

    2010-01-01

    There is increasing demand for access to effective interventions for families who have children with autism. Self-directed learning models have been successfully used with other populations as a way to reduce the service-need discrepancy. The purpose of this study was to evaluate, through a randomized clinical trial, whether the use of a…

  6. An Introduction to "My Environmental Education Evaluation Resource Assistant" (MEERA), a Web-Based Resource for Self-Directed Learning about Environmental Education Program Evaluation

    ERIC Educational Resources Information Center

    Zint, Michaela

    2010-01-01

    My Environmental Education Evaluation Resource Assistant or "MEERA" is a web-site designed to support environmental educators' program evaluation activities. MEERA has several characteristics that set it apart from other self-directed learning evaluation resources. Readers are encouraged to explore the site and to reflect on the role that…

  7. A Study of the Relationship Between Self-Directed and Teacher-Directed Eighth-Grade Students Involved in an Open-Ended ESCP Laboratory Block.

    ERIC Educational Resources Information Center

    Kline, Arlyn Arthur

    Reported is a study to ascertain whether or not the open-ended laboratory activities in the Earth Science Curriculum Project (ESCP) program could be learned as effectively by self-directed students and to ascertain students' attitudes and interest toward learning science through a laboratory-block discovery approach. Ninety-seven junior high…

  8. The Impact of Curriculum Developed in Line with Authentic Learning on the Teacher Candidates' Success, Attitude and Self-Directed Learning Skills

    ERIC Educational Resources Information Center

    Hursen, Cigdem

    2016-01-01

    The purpose of this study is to determine the impact of the curriculum developed in line with authentic learning on the teacher candidates' success, attitudes towards courses and self-directed learning skills. The study, that is quantitative in nature, is carried out with 64 teacher candidates studying at Near East University and taking the course…

  9. Case-Based Learning in Endocrine Physiology: An Approach toward Self-Directed Learning and the Development of Soft Skills in Medical Students

    ERIC Educational Resources Information Center

    Gade, Shubhada; Chari, Suresh

    2013-01-01

    The Medical Council of India, in the recent "Vision 2015" document, recommended curricular reforms for undergraduates. Case-based learning (CBL) is one method where students are motivated toward self-directed learning and to develop analytic and problem-solving skills. An overview of thyroid physiology was given in a didactic lecture. A…

  10. Selbstgesteuertes Lernen und Modernisierungsimperative in der Erwachsenen- und Weiterbildung (Self-directed Learning and Modernization Imperatives in Adult and in Further Education).

    ERIC Educational Resources Information Center

    Forneck, Hermann J.

    2002-01-01

    Supports the thesis that constructivism and self controlled learning in adult education should be considered reactions to imperatives of modernization. Recognizes that concepts of self-directed learning are accompanied by a change in the forms of organization as well as the logic and structure of action in adult education. (CAJ)

  11. The Investigation of the Relationship between the Level of Metacognitive Awareness, Self-Directed Learning Readiness and Academic Achievement of Preschool Teacher Candidates

    ERIC Educational Resources Information Center

    Dagal, Asude Balaban; Bayindir, Dilan

    2016-01-01

    The aim of the study is to examine the relationship between the level of metacognitive awareness, self-directed learning readiness and academic achievement of preschool teacher candidates. The study group of the research, which was designed in survey method, included 151 teacher candidates from Atatürk Education Faculty, Preschool Teaching…

  12. Toward Understanding the Role of Web 2.0 Technology in Self-Directed Learning and Job Performance in a Single Organizational Setting: A Qualitative Case Study

    ERIC Educational Resources Information Center

    Caruso, Shirley J.

    2016-01-01

    This single instrumental qualitative case study explores and thickly describes job performance outcomes based upon the manner in which self-directed learning activities of a purposefully selected sample of 3 construction managers are conducted, mediated by the use of Web 2.0 technology. The data collected revealed that construction managers are…

  13. The Influence of Adult Learners' Self-Directed Learning Readiness and Network Literacy on Online Learning Effectiveness: A Study of Civil Servants in Taiwan

    ERIC Educational Resources Information Center

    Lai, Horng-Ji

    2011-01-01

    This study examined the effect of civil servants' Self-Directed Learning Readiness (SDLR) and network literacy on their online learning effectiveness in a web-based training program. Participants were 283 civil servants enrolled in an asynchronous online learning program through an e-learning portal provided by the Regional Civil Service…

  14. The Effect of Blended Learning and Social Media-Supported Learning on the Students' Attitude and Self-Directed Learning Skills in Science Education

    ERIC Educational Resources Information Center

    Akgunduz, Devrim; Akinoglu, Orhan

    2016-01-01

    The main purpose of this study is to investigate the effect of blended learning and social media supported learning on the students' attitude and self-directed learning skills in Science Education. This research took place with the 7th grade 74 students attending to a primary school in Kadikoy, Istanbul and carried out "Our Body Systems"…

  15. The Effect of Self-directed Exercise Using a Task Board on Pain and Function in the Upper Extremities of Stroke Patients

    PubMed Central

    Lee, Han Suk; Kim, Jin Ung

    2013-01-01

    [Purpose] We evaluated the effect of self-directed exercise using a task board on function and pain in the upper extremities of stroke patients [Subjects and Methods] We used the one group pre-post test design. Seven stroke patients who were selected based on the inclusion criteria participated in the program once a week for 10 weeks. The self-directed exercise comprised 5 stages that were divided according to the level of difficulty. The exercise was performed for 60 minutes using a special task board that we designed. The FMA (Fugl-Meyer Motor Assessment), VAS (Visual Analogue Scale), and speed of stacking were assessed to evaluate the amount of use of the affected arm at before and after intervention. [Results] The scores of the VAS and FMA, but not that of the speed of stacking cups, were improved. There was no significant correlation between the changes in VAS, FMA, and the speed of stacking cups. [Conclusion] The findings suggest that self-directed exercise with the task board could improve the levels of function and pain in the upper extremities. We suggest that self-directed exercise can be utilized as a clinical rehabilitation program and improve therapeutic effects. PMID:24259894

  16. Influencing Work-Related Learning: The Role of Job Characteristics and Self-Directed Learning Orientation in Part-Time Vocational Education

    ERIC Educational Resources Information Center

    Gijbels, David; Raemdonck, Isabel; Vervecken, Dries

    2010-01-01

    Based on the Demand-Control-Support (DCS) model, the present paper aims to investigate the influence of job characteristics such as job demands, job control, social support at work and self-directed learning orientation on the work-related learning behaviour of workers. The present study was conducted in a centre for part-time vocational education…

  17. Implementation of Complex Biological Logic Circuits Using Spatially Distributed Multicellular Consortia

    PubMed Central

    Urrios, Arturo; de Nadal, Eulàlia; Solé, Ricard; Posas, Francesc

    2016-01-01

    Engineered synthetic biological devices have been designed to perform a variety of functions from sensing molecules and bioremediation to energy production and biomedicine. Notwithstanding, a major limitation of in vivo circuit implementation is the constraint associated to the use of standard methodologies for circuit design. Thus, future success of these devices depends on obtaining circuits with scalable complexity and reusable parts. Here we show how to build complex computational devices using multicellular consortia and space as key computational elements. This spatial modular design grants scalability since its general architecture is independent of the circuit’s complexity, minimizes wiring requirements and allows component reusability with minimal genetic engineering. The potential use of this approach is demonstrated by implementation of complex logical functions with up to six inputs, thus demonstrating the scalability and flexibility of this method. The potential implications of our results are outlined. PMID:26829588

  18. Phenotypes on demand via switchable target protein degradation in multicellular organisms

    PubMed Central

    Faden, Frederik; Ramezani, Thomas; Mielke, Stefan; Almudi, Isabel; Nairz, Knud; Froehlich, Marceli S.; Höckendorff, Jörg; Brandt, Wolfgang; Hoehenwarter, Wolfgang; Dohmen, R. Jürgen; Schnittger, Arp; Dissmeyer, Nico

    2016-01-01

    Phenotypes on-demand generated by controlling activation and accumulation of proteins of interest are invaluable tools to analyse and engineer biological processes. While temperature-sensitive alleles are frequently used as conditional mutants in microorganisms, they are usually difficult to identify in multicellular species. Here we present a versatile and transferable, genetically stable system based on a low-temperature-controlled N-terminal degradation signal (lt-degron) that allows reversible and switch-like tuning of protein levels under physiological conditions in vivo. Thereby, developmental effects can be triggered and phenotypes on demand generated. The lt-degron was established to produce conditional and cell-type-specific phenotypes and is generally applicable in a wide range of organisms, from eukaryotic microorganisms to plants and poikilothermic animals. We have successfully applied this system to control the abundance and function of transcription factors and different enzymes by tunable protein accumulation. PMID:27447739

  19. A New Subcarrier Allocation Strategy for MIMO-OFDMA Multicellular Networks Based on Cooperative Interference Mitigation

    PubMed Central

    Gkonis, Panagiotis K.; Seimeni, Maria A.; Asimakis, Nikolaos P.; Kaklamani, Dimitra I.; Venieris, Iakovos S.

    2014-01-01

    The goal of the study presented in this paper is to investigate the performance of a new subcarrier allocation strategy for Orthogonal Frequency Division Multiple Access (OFDMA) multicellular networks which employ Multiple Input Multiple Output (MIMO) architecture. For this reason, a hybrid system-link level simulator has been developed executing independent Monte Carlo (MC) simulations in parallel. Up to two tiers of cells around the central cell are taken into consideration and increased loading per cell. The derived results indicate that this strategy can provide up to 12% capacity gain for 16-QAM modulation and two tiers of cells around the central cell in a symmetric 2 × 2 MIMO configuration. This gain is derived when comparing the proposed strategy to the traditional approach of allocating subcarriers that maximize only the desired user's signal. PMID:24683351

  20. From cat's eyes to disjoint multicellular natural convection flow in tall tilted cavities

    NASA Astrophysics Data System (ADS)

    Nicolás, Alfredo; Báez, Elsa; Bermúdez, Blanca

    2011-07-01

    Numerical results of two-dimensional natural convection problems, in air-filled tall cavities, are reported to study the change of the cat's eyes flow as some parameters vary, the aspect ratio A and the angle of inclination ϕ of the cavity, with the Rayleigh number Ra mostly fixed; explicitly, the range of the variation is given by 12⩽A⩽20 and 0°⩽ϕ⩽270°; about Ra=1.1×10. A novelty contribution of this work is the transition from the cat's eyes changes, as A varies, to a disjoint multicellular flow, as ϕ varies. These flows may be modeled by the unsteady Boussinesq approximation in stream function and vorticity variables which is solved with a fixed point iterative process applied to the nonlinear elliptic system that results after time discretization. The validation of the results relies on mesh size and time-step independence studies.

  1. Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms.

    PubMed

    Clausell-Tormos, Jenifer; Lieber, Diana; Baret, Jean-Christophe; El-Harrak, Abdeslam; Miller, Oliver J; Frenz, Lucas; Blouwolff, Joshua; Humphry, Katherine J; Köster, Sarah; Duan, Honey; Holtze, Christian; Weitz, David A; Griffiths, Andrew D; Merten, Christoph A

    2008-05-01

    High-throughput, cell-based assays require small sample volumes to reduce assay costs and to allow for rapid sample manipulation. However, further miniaturization of conventional microtiter plate technology is problematic due to evaporation and capillary action. To overcome these limitations, we describe droplet-based microfluidic platforms in which cells are grown in aqueous microcompartments separated by an inert perfluorocarbon carrier oil. Synthesis of biocompatible surfactants and identification of gas-permeable storage systems allowed human cells, and even a multicellular organism (C. elegans), to survive and proliferate within the microcompartments for several days. Microcompartments containing single cells could be reinjected into a microfluidic device after incubation to measure expression of a reporter gene. This should open the way for high-throughput, cell-based screening that can use >1000-fold smaller assay volumes and has approximately 500x higher throughput than conventional microtiter plate assays.

  2. Concentration-flux relations for a multicellular biological membrane with Metabolism

    SciTech Connect

    Auton, T.R. )

    1993-05-01

    A mathematical model is described for the simultaneous diffusion and metabolism of a chemical penetrating a multicellular biological membrane such as skin. Metabolism is assumed to follow saturable Michaelis-Menten kinetics, which leads to nonlinear relationships between the applied concentration and the metabolic and diffusive fluxes through the membrane. Approximate concentration flux relations are derived under limiting conditions, and a computational method is described for the general case. The major barrier to dermal penetration of very lipophilic molecules is thought to be the viable tissues (viable epidermis and some of the dermis) underlying the stratum corneum, and some molecules are known to be metabolized by enzymes within these tissues. It is proposed to use the model to describe penetration and metabolism os such lipophilic molecules within the viable tissues of the skin. 16 refs., 4 figs.

  3. The cellular Ising model: a framework for phase transitions in multicellular environments.

    PubMed

    Weber, Marc; Buceta, Javier

    2016-06-01

    Inspired by the Ising model, we introduce a gene regulatory network that induces a phase transition that coordinates robustly the behaviour of cell ensembles. The building blocks of the design are the so-called toggle switch interfaced with two quorum sensing modules, Las and Lux. We show that as a function of the transport rate of signalling molecules across the cell membrane the population undergoes a spontaneous symmetry breaking from cells individually switching their phenotypes to a global collective phenotypic organization. By characterizing the critical behaviour, we reveal some properties, such as phenotypic memory and hypersensitivity, with relevance in the field of synthetic biology. We argue that our results can be extrapolated to other multicellular systems and be a generic framework for collective decision-making processes.

  4. Principles of cooperation across systems: from human sharing to multicellularity and cancer.

    PubMed

    Aktipis, Athena

    2016-01-01

    From cells to societies, several general principles arise again and again that facilitate cooperation and suppress conflict. In this study, I describe three general principles of cooperation and how they operate across systems including human sharing, cooperation in animal and insect societies and the massively large-scale cooperation that occurs in our multicellular bodies. The first principle is that of Walk Away: that cooperation is enhanced when individuals can leave uncooperative partners. The second principle is that resource sharing is often based on the need of the recipient (i.e., need-based transfers) rather than on strict account-keeping. And the last principle is that effective scaling up of cooperation requires increasingly sophisticated and costly cheater suppression mechanisms. By comparing how these principles operate across systems, we can better understand the constraints on cooperation. This can facilitate the discovery of novel ways to enhance cooperation and suppress cheating in its many forms, from social exploitation to cancer.

  5. Complex multicellular systems and immune competition: new paradigms looking for a mathematical theory.

    PubMed

    Bellomo, Nicola; Forni, Guido

    2008-01-01

    This chapter deals with the modeling and simulation of large systems of interacting entities whose microscopic state includes not only geometrical and mechanical variables (typically position and velocity), but also biological functions or specific activities. The main issue looks at the development of a biological mathematical theory for multicellular systems. The first part is devoted to the derivation of mathematical structures to be properly used to model a variety of biological phenomena with special focus on immune competition. Then, some specific applications are proposed referring to the competition between neoplastic and immune cells. Finally, the last part is devoted to research perspectives towards the objective of developing a mathematical-biological theory. A critique is presented of what has already been achieved towards the above target and what is still missing with special focus on multiscale systems.

  6. Communication-induced multistability and multirhythmicity in a synthetic multicellular system

    NASA Astrophysics Data System (ADS)

    Yi, Qizhi; Zhou, Tianshou

    2011-05-01

    Traditionally, the main role of cell-to-cell communication was thought of as synchronizing a population of cells, thereby coordinating cellular behavior. Here we show that cell density, which quantifies cellular communication, can induce multistability and multirhythmicity in a synthetic multicellular system, where individual oscillators are a combination of repressillator and hysteresis-based oscillators and are coupled through a quorum-sensing mechanism. Specifically, for moderately small cell densities, the coupled system can exhibit multistability including stable homogenous and inhomogeneous steady states. For moderately large cell densities, it has the potential to generate multirhythmicity including multimode oscillations such as an in-phase periodic solution, antiphase periodic solution, asymmetric periodic solution, mixed-mode oscillations, coexistence of periodic orbits of several different modes, and bursting oscillations such as periodic bursting, torus quasiperiodic bursting, and chaotic bursting. Such versatility of cell-to-cell communication would be beneficial for cells or organisms to live in diversely changeable environments.

  7. Molecular regulation of the mitosis/meiosis decision in multicellular organisms.

    PubMed

    Kimble, Judith

    2011-08-01

    A major step in the journey from germline stem cell to differentiated gamete is the decision to leave the mitotic cell cycle and begin progression through the meiotic cell cycle. Over the past decade, molecular regulators of the mitosis/meiosis decision have been discovered in most of the major model multicellular organisms. Historically, the mitosis/meiosis decision has been closely linked with controls of germline self-renewal and the sperm/egg decision, especially in nematodes and mice. Molecular explanations of those linkages clarify our understanding of this fundamental germ cell decision, and unifying themes have begun to emerge. Although the complete circuitry of the decision is not known in any organism, the recent advances promise to impact key issues in human reproduction and agriculture.

  8. Virus-host arms race at the joint origin of multicellularity and programmed cell death.

    PubMed

    Iranzo, Jaime; Lobkovsky, Alexander E; Wolf, Yuri I; Koonin, Eugene V

    2014-01-01

    Unicellular eukaryotes and most prokaryotes possess distinct mechanisms of programmed cell death (PCD). How an "altruistic" trait, such as PCD, could evolve in unicellular organisms? To address this question, we developed a mathematical model of the virus-host co-evolution that involves interaction between immunity, PCD and cellular aggregation. Analysis of the parameter space of this model shows that under high virus load and imperfect immunity, joint evolution of cell aggregation and PCD is the optimal evolutionary strategy. Given the abundance of viruses in diverse habitats and the wide spread of PCD in most organisms, these findings imply that multiple instances of the emergence of multicellularity and its essential attribute, PCD, could have been driven, at least in part, by the virus-host arms race.

  9. Overproduction and easy recovery of biofuels from engineered cyanobacteria, autolyzing multicellular cells.

    PubMed

    Yoshida, Satomi; Takahashi, Masatoshi; Ikeda, Ayae; Fukuda, Hirofumi; Kitazaki, Chifumi; Asayama, Munehiko

    2015-06-01

    The semi-filamentous multicellular cyanobacterium Limnothrix/Pseudanabaena sp. strain ABRG5-3 undergoes autolysis, which involves the accumulation of polyphosphate compounds and disintegration of thylakoid membranes in cells, as a unique feature that occurs due to growth conditions. In this study, the overexpression and easy recovery of alkane (a saturated hydrocarbon, C17H36) as a biofuel were examined in recombinants of the cyanobacteria ABRG5-3 and Synechocystis sp. strain PCC6803. The results obtained indicated that the accumulated mass of alkane accounted for ∼50 or 60% of the dry weight of ABRG5-3 or PCC6803 recombinant cells, respectively. Furthermore, cultivating cells in liquid medium BG11 in which the nitrogen resource had been depleted promoted the production of alkane and cell lysis, resulting in the easy recovery of target products from the supernatant.

  10. Rapid Engineering of Three-Dimensional, Multicellular Tissues With Polymeric Scaffolds

    NASA Technical Reports Server (NTRS)

    Gonda, Steve R.; Jordan, Jacqueline; Fraga, Denise N.

    2007-01-01

    A process has been developed for the rapid tissue engineering of multicellular-tissue-equivalent assemblies by the controlled enzymatic degradation of polymeric beads in a low-fluid-shear bioreactor. In this process, the porous polymeric beads serve as temporary scaffolds to support the assemblies of cells in a tissuelike 3D configuration during the critical initial growth phases of attachment of anchorage-dependent cells, aggregation of the cells, and formation of a 3D extracellular matrix. Once the cells are assembled into a 3D array and enmeshed in a structural supportive 3D extracellular matrix (ECM), the polymeric scaffolds can be degraded in the low-fluid-shear environment of the NASA-designed bioreactor. The natural 3D tissuelike assembly, devoid of any artificial support structure, is maintained in the low-shear bioreactor environment by the newly formed natural cellular/ECM. The elimination of the artificial scaffold allows normal tissue structure and function.

  11. Quantification of DNA synthesis in multicellular organisms by a combined DAPI and BrdU technique.

    PubMed

    Knobloch, Jürgen; Kunz, Werner; Grevelding, Christoph G

    2002-12-01

    The development of a novel method to detect and quantify mitotic activity in multicellular organisms is reported. The method is based on the combinatorial use of 4',6-diamidino-2-phenylindole (DAPI) as a dye for the specific staining of DNA and the thymidine analog 5-bromo-2'-deoxyuridine (BrdU) as a marker for DNA synthesis. It is shown that on nitrocellulose filters, the amount of DNA can be determined by DAPI as a prerequisite for the subsequent quantification of mitotic activity by BrdU. As a model system to prove the applicability of this technique, the blood fluke Schistosoma mansoni has been used. It is demonstrated that the DNA synthesis rate is higher in adult female schistosomes than in adult males. Furthermore, dimethyl sulfoxide, a widely used solvent for many mitogens and inhibitors of mitosis, has no influence on mitotic activity in adult schistosomes.

  12. Seeking the ultimate and proximate causes of volvox multicellularity and cellular differentiation.

    PubMed

    Kirk, David L

    2003-04-01

    Volvox and its relatives provide an exceptional model for integrative studies of the evolution of multicellularity and cellular differentiation. The volvocine algae range in complexity from unicellular Chlamydomonas through several colonial genera with a single cell type, to multicellular Volvox with its germ-soma division of labor. Within the monophyletic family Volvocaceae, several species of Volvox have evolved independently in different lineages, the ultimate cause presumably being the advantage that large size and cellular differentiation provide in competing for limiting resources such as phosphorous. The proximate causes of this type of evolutionary transition are being studied in V. carteri. All volvocine algae except Volvox exhibit biphasic development: cells grow during a motile, biflagellate phase, then they lose motility and divide repeatedly during the reproductive phase. In V. carteri three kinds of genes transform this ancestral biphasic program into a dichotomous one that generates non-motile reproductive cells and biflagellate somatic cells with no reproductive potential: first the gls genes act in early embryos to cause asymmetric division and production of large-small sister-cell pairs; then lag genes act in the large cells to repress the biflagellate half of the ancestral program, while regA acts in the small cells to repress the reproductive half of the program. Molecular-genetic analysis of these genes is progressing, as will be illustrated with regA, which encodes a transcription factor that acts in somatic cells to repress nuclear genes encoding chloroplast proteins. Repression of chloroplast biogenesis prevents these obligately photoautotrophic cells from growing, and since they cannot grow, they cannot reproduce.

  13. Cellular differentiation and individuality in the “minor” multicellular taxa

    PubMed Central

    Herron, Matthew D.; Rashidi, Armin; Shelton, Deborah E.; Driscoll, William W.

    2014-01-01

    Biology needs a concept of individuality in order to distinguish organisms from parts of organisms and from groups of organisms, to count individuals and compare traits across taxa, and to distinguish growth from reproduction. Most of the proposed criteria for individuality were designed for ‘unitary’ or ‘paradigm’ organisms: contiguous, functionally and physiologically integrated, obligately sexually reproducing multicellular organisms with a germ line sequestered early in development. However, the vast majority of the diversity of life on Earth does not conform to all of these criteria. We consider the issue of individuality in the ‘minor’ multicellular taxa, which collectively span a large portion of the eukaryotic tree of life, reviewing their general features and focusing on a model species for each group. When the criteria designed for unitary organisms are applied to other groups, they often give conflicting answers or no answer at all to the question of whether or not a given unit is an individual. Complex life cycles, intimate bacterial symbioses, aggregative development, and strange genetic features complicate the picture. The great age of some of the groups considered shows that ‘intermediate’ forms, those with some but not all of the traits traditionally associated with individuality, cannot reasonably be considered ephemeral or assumed transitional. We discuss a handful of recent attempts to reconcile the many proposed criteria for individuality and to provide criteria that can be applied across all the domains of life. Finally, we argue that individuality should be defined without reference to any particular taxon and that understanding the emergence of new kinds of individuals requires recognizing individuality as a matter of degree. PMID:23448295

  14. A Duo of Potassium-Responsive Histidine Kinases Govern the Multicellular Destiny of Bacillus subtilis

    PubMed Central

    de Oña, Paula; Kunert, Maritta; Leñini, Cecilia; Gallegos-Monterrosa, Ramses; Mhatre, Eisha; Vileta, Darío; Donato, Verónica; Hölscher, Theresa; Boland, Wilhelm; Kuipers, Oscar P.

    2015-01-01

    ABSTRACT Multicellular biofilm formation and surface motility are bacterial behaviors considered mutually exclusive. However, the basic decision to move over or stay attached to a surface is poorly understood. Here, we discover that in Bacillus subtilis, the key root biofilm-controlling transcription factor Spo0A~Pi (phosphorylated Spo0A) governs the flagellum-independent mechanism of social sliding motility. A Spo0A-deficient strain was totally unable to slide and colonize plant roots, evidencing the important role that sliding might play in natural settings. Microarray experiments plus subsequent genetic characterization showed that the machineries of sliding and biofilm formation share the same main components (i.e., surfactin, the hydrophobin BslA, exopolysaccharide, and de novo-formed fatty acids). Sliding proficiency was transduced by the Spo0A-phosphorelay histidine kinases KinB and KinC. We discovered that potassium, a previously known inhibitor of KinC-dependent biofilm formation, is the specific sliding-activating signal through a thus-far-unnoticed cytosolic domain of KinB, which resembles the selectivity filter sequence of potassium channels. The differential expression of the Spo0A~Pi reporter abrB gene and the different levels of the constitutively active form of Spo0A, Sad67, in Δspo0A cells grown in optimized media that simultaneously stimulate motile and sessile behaviors uncover the spatiotemporal response of KinB and KinC to potassium and the gradual increase in Spo0A~Pi that orchestrates the sequential activation of sliding, followed by sessile biofilm formation and finally sporulation in the same population. Overall, these results provide insights into how multicellular behaviors formerly believed to be antagonistic are coordinately activated in benefit of the bacterium and its interaction with the host. PMID:26152584

  15. Dynamical patterning modules: a "pattern language" for development and evolution of multicellular form.

    PubMed

    Newman, Stuart A; Bhat, Ramray

    2009-01-01

    This article considers the role played by a core set of "dynamical patterning modules" (DPMs) in the origination, development and evolution of complex organisms. These consist of the products of a subset of the genes of what has come to be known as the "developmental-genetic toolkit" in association with physical processes they mobilize. The physical processes are those characteristic of chemically and mechanically excitable mesoscopic systems like cell aggregates: cohesion, viscoelasticity, diffusion, spatiotemporal heterogeneity based on activator-inhibitor interaction, and multistable and oscillatory dynamics. We focus on the emergence of the Metazoa, and show how toolkit gene products and pathways that pre-existed the metazoans acquired novel morphogenetic functions simply by virtue of the change in scale and context inherent to multicellularity. We propose that DPMs, acting singly and in combination with each other, constitute a "pattern language" capable of generating all metazoan body plans and organ forms. This concept implies that the multicellular organisms of the late Precambrian-early Cambrian were phenotypically plastic, fluently exploring morphospace in a fashion decoupled from both function-based selection and genotypic change. The relatively stable developmental trajectories and morphological phenotypes of modern organisms, then, are considered to be products of stabilizing selection. This perspective solves the apparent "molecular homology-analogy paradox," whereby widely divergent modern animal types utilize the same molecular toolkit during development, but it does so by inverting the neo-Darwinian principle that phenotypic disparity was generated over long periods of time in concert with, and in proportion to genotypic change.

  16. Three dimensional multi-cellular muscle-like tissue engineering in perfusion-based bioreactors.

    PubMed

    Cerino, Giulia; Gaudiello, Emanuele; Grussenmeyer, Thomas; Melly, Ludovic; Massai, Diana; Banfi, Andrea; Martin, Ivan; Eckstein, Friedrich; Grapow, Martin; Marsano, Anna

    2016-01-01

    Conventional tissue engineering strategies often rely on the use of a single progenitor cell source to engineer in vitro biological models; however, multi-cellular environments can better resemble the complexity of native tissues. Previous described co-culture models used skeletal myoblasts, as parenchymal cell source, and mesenchymal or endothelial cells, as stromal component. Here, we propose instead the use of adipose tissue-derived stromal vascular fraction cells, which include both mesenchymal and endothelial cells, to better resemble the native stroma. Percentage of serum supplementation is one of the crucial parameters to steer skeletal myoblasts toward either proliferation (20%) or differentiation (5%) in two-dimensional culture conditions. On the contrary, three-dimensional (3D) skeletal myoblast culture often simply adopts the serum content used in monolayer, without taking into account the new cell environment. When considering 3D cultures of mm-thick engineered tissues, homogeneous and sufficient oxygen supply is paramount to avoid formation of necrotic cores. Perfusion-based bioreactor culture can significantly improve the oxygen access to the cells, enhancing the viability and the contractility of the engineered tissues. In this study, we first investigated the influence of different serum supplementations on the skeletal myoblast ability to proliferate and differentiate during 3D perfusion-based culture. We tested percentages of serum promoting monolayer skeletal myoblast-proliferation (20%) and differentiation (5%) and suitable for stromal cell culture (10%) with a view to identify the most suitable condition for the subsequent co-culture. The 10% serum medium composition resulted in the highest number of mature myotubes and construct functionality. Co-culture with stromal vascular fraction cells at 10% serum also supported the skeletal myoblast differentiation and maturation, hence providing a functional engineered 3D muscle model that resembles

  17. Cell motility and local viscoelasticity of fibroblasts.

    PubMed

    Park, S; Koch, D; Cardenas, R; Käs, J; Shih, C K

    2005-12-01

    Viscoelastic changes of the lamellipodial actin cytoskeleton are a fundamental element of cell motility. Thus, the correlation between the local viscoelastic properties of the lamellipodium (including the transitional region to the cell body) and the speed of lamellipodial extension is studied for normal and malignantly transformed fibroblasts. Using our atomic force microscopy-based microrheology technique, we found different mechanical properties between the lamellipodia of malignantly transformed fibroblasts (H-ras transformed and SV-T2 fibroblasts) and normal fibroblasts (BALB 3T3 fibroblasts). The average elastic constants, K, in the leading edge of SV-T2 fibroblasts (0.48 +/- 0.51 kPa) and of H-ras transformed fibroblasts (0.42 +/- 0.35 kPa) are significantly lower than that of BALB 3T3 fibroblasts (1.01 +/- 0.40 kPa). The analysis of time-lapse phase contrast images shows that the decrease in the elastic constant, K, for malignantly transformed fibroblasts is correlated with the enhanced motility of the lamellipodium. The measured mean speeds are 6.1 +/- 4.5 microm/h for BALB 3T3 fibroblasts, 13.1 +/- 5.2 microm/h for SV-T2 fibroblasts, and 26.2 +/- 11.5 microm/h for H-ras fibroblasts. Furthermore, the elastic constant, K, increases toward the cell body in many instances which coincide with an increase in actin filament density toward the cell body. The correlation between the enhanced motility and the decrease in viscoelastic moduli supports the Elastic Brownian Ratchet model for driving lamellipodia extension.

  18. Gastrointestinal Fibroblasts Have Specialized, Diverse Transcriptional Phenotypes: A Comprehensive Gene Expression Analysis of Human Fibroblasts

    PubMed Central

    Ishii, Genichiro; Aoyagi, Kazuhiko; Sasaki, Hiroki; Ochiai, Atsushi

    2015-01-01

    Background Fibroblasts are the principal stromal cells that exist in whole organs and play vital roles in many biological processes. Although the functional diversity of fibroblasts has been estimated, a comprehensive analysis of fibroblasts from the whole body has not been performed and their transcriptional diversity has not been sufficiently explored. The aim of this study was to elucidate the transcriptional diversity of human fibroblasts within the whole body. Methods Global gene expression analysis was performed on 63 human primary fibroblasts from 13 organs. Of these, 32 fibroblasts from gastrointestinal organs (gastrointestinal fibroblasts: GIFs) were obtained from a pair of 2 anatomical sites: the submucosal layer (submucosal fibroblasts: SMFs) and the subperitoneal layer (subperitoneal fibroblasts: SPFs). Using hierarchical clustering analysis, we elucidated identifiable subgroups of fibroblasts and analyzed the transcriptional character of each subgroup. Results In unsupervised clustering, 2 major clusters that separate GIFs and non-GIFs were observed. Organ- and anatomical site-dependent clusters within GIFs were also observed. The signature genes that discriminated GIFs from non-GIFs, SMFs from SPFs, and the fibroblasts of one organ from another organ consisted of genes associated with transcriptional regulation, signaling ligands, and extracellular matrix remodeling. Conclusions GIFs are characteristic fibroblasts with specific gene expressions from transcriptional regulation, signaling ligands, and extracellular matrix remodeling related genes. In addition, the anatomical site- and organ-dependent diversity of GIFs was also discovered. These features of GIFs contribute to their specific physiological function and homeostatic maintenance, and create a functional diversity of the gastrointestinal tract. PMID:26046848

  19. Asymmetries in the production of self-directed behavior by chimpanzees and gorillas during a computerized cognitive test.

    PubMed

    Wagner, Katherine E; Hopper, Lydia M; Ross, Stephen R

    2016-03-01

    Self-directed behaviors (SDBs) are a commonly used behavioral indicator of arousal in nonhuman primates. Experimental manipulations, designed to increase arousal and uncertainty, have been used to elicit SDB production in primates. Beyond measuring rates of SDB production, researchers have also recorded their lateralized production by primates, thought to reflect laterality of hemispheric brain control and response to emotion. Although a handful of such studies exist, all have been conducted with chimpanzees. Expanding on this line of inquiry, we tested both chimpanzees (N = 3) and gorillas (N = 3) in a serial learning task presented on a touchscreen interface that incorporated both EASY (two-item list) and HARD (four-item list) versions of the task. Although SDB production by the apes did not differ across the two levels of task complexity, both species produced higher rates of SDB when they made an error, regardless of task difficulty. Furthermore, the apes made more SDB with the left hand-directed to the right side of their body (contralateral SDB) and left side of their body (ipsilateral SDB)-when they made an incorrect response. There was no difference in the rate of SDB produced with the right hand across correct compared to incorrect trials. The apes' responses reflect previous reports that show humans are quicker at selecting negative emotional stimuli when using their left, compared to their right, hand (the reverse is true for positive stimuli). However, previous work has shown that chimpanzees are more likely to produce (contralateral) SDB with their right hand when aroused and so we discuss our results in relation to these findings and consider how they relate to the 'right hemisphere' and 'valence' models of emotional processing in apes.

  20. Loosely-guided, self-directed learning versus strictly-guided, station-based learning in gross anatomy laboratory sessions.

    PubMed

    Kooloos, Jan G M; de Waal Malefijt, Maarten C; Ruiter, Dirk J; Vorstenbosch, Marc A T M

    2012-01-01

    Anatomy students studying dissected anatomical specimens were subjected to either a loosely-guided, self-directed learning environment or a strictly-guided, preformatted gross anatomy laboratory session. The current study's guiding questions were: (1) do strictly-guided gross anatomy laboratory sessions lead to higher learning gains than loosely-guided experiences? and (2) are there differences in the recall of anatomical knowledge between students who undergo the two types of laboratory sessions after weeks and months? The design was a randomized controlled trial. The participants were 360 second-year medical students attending a gross anatomy laboratory course on the anatomy of the hand. Half of the students, the experimental group, were subjected without prior warning to station-based laboratory sessions; the other half, the control group, to loosely-guided laboratory sessions, which was the course's prevailing educational method at the time. The recall of anatomical knowledge was measured by written reproduction of 12 anatomical names at four points in time: immediately after the laboratory experience, then one week, five weeks, and eight months later. The strictly-guided group scored higher than the loosely-guided group at all time-points. Repeated ANOVA showed no interaction between the results of the two types of laboratory sessions (P = 0.121) and a significant between-subject effect (P ≤ 0.001). Therefore, levels of anatomical knowledge retrieved were significantly higher for the strictly-guided group than for the loosely-guided group at all times. It was concluded that gross anatomy laboratory sessions with strict instructions resulted in the recall of a larger amount of anatomical knowledge, even after eight months.

  1. Are self-directed parenting interventions sufficient for externalising behaviour problems in childhood? A systematic review and meta-analysis.

    PubMed

    Tarver, Joanne; Daley, David; Lockwood, Joanna; Sayal, Kapil

    2014-12-01

    Externalising behaviour in childhood is a prevalent problem in the field of child and adolescent mental health. Parenting interventions are widely accepted as efficacious treatment options for reducing externalising behaviour, yet practical and psychological barriers limit their accessibility. This review aims to establish the evidence base of self-directed (SD) parenting interventions for externalising behaviour problems. Electronic searches of PubMed, Web of Knowledge, Psychinfo, Embase and CENTRAL databases and manual searches of reference lists of relevant reviews identified randomised controlled trials and cluster randomised controlled trials examining the efficacy of SD interventions compared to no-treatment or active control groups. A random-effect meta-analysis estimated pooled standard mean difference (SMD) for SD interventions on measures of externalising child behaviour. Secondary analyses examined their effect on measures of parenting behaviour, parental stress and mood and parenting efficacy. Eleven eligible trials were included in the analyses. SD interventions had a large effect on parent report of externalising child behaviour (SMD = 1.01, 95 % CI: 0.77-1.24); although this effect was not upheld by analyses of observed child behaviour. Secondary analyses revealed effects of small to moderate magnitude on measures of parenting behaviour, parental mood and stress and parenting efficacy. An analysis comparing SD interventions with therapist-led parenting interventions revealed no significant difference on parent-reported measures of externalising child behaviour. SD interventions are associated with improvements in parental perception of externalising child behaviour and parental behaviour and well-being. Future research should further investigate the relative efficacy and cost-effectiveness of SD interventions compared to therapist-led interventions.

  2. Mechanochemical switching between growth and differentiation during fibroblast growth factor-stimulated angiogenesis in vitro: role of extracellular matrix

    PubMed Central

    1989-01-01

    The angiogenic factor, basic fibroblast growth factor (FGF), either stimulates endothelial cell growth or promotes capillary differentiation depending upon the microenvironment in which it acts. Analysis of various in vitro models of spontaneous angiogenesis, in combination with time-lapse cinematography, demonstrated that capillary tube formation was greatly facilitated by promoting multicellular retraction and cell elevation above the surface of the rigid culture dish or by culturing endothelial cells on malleable extracellular matrix (ECM) substrata. These observations suggested to us that mechanical (i.e., tension-dependent) interactions between endothelial cells and ECM may serve to regulate capillary development. To test this hypothesis, FGF-stimulated endothelial cells were grown in chemically defined medium on bacteriological (nonadhesive) dishes that were precoated with different densities of fibronectin. Extensive cell spreading and growth were promoted by fibronectin coating densities that were highly adhesive (greater than 500 ng/cm2), whereas cell rounding, detachment, and loss of viability were observed on dishes coated with low fibronectin concentrations (less than 100 ng/cm2). Intermediate fibronectin coating densities (100-500 ng/cm2) promoted cell extension, but they could not completely resist cell tractional forces. Partial retraction of multicellular aggregates resulted in cell shortening, cessation of growth, and formation of branching tubular networks within 24-48 h. Multicellular retraction and subsequent tube formation also could be elicited on highly adhesive dishes by overcoming the mechanical resistance of the substratum using higher cell plating numbers. Dishes coated with varying concentrations of type IV collagen or gelatin produced similar results. These results suggest that ECM components may act locally to regulate the growth and pattern- regulating actions of soluble FGF based upon their ability to resist cell-generated mechanical

  3. Murine Dermal Fibroblast Isolation by FACS.

    PubMed

    Walmsley, Graham G; Maan, Zeshaan N; Hu, Michael S; Atashroo, David A; Whittam, Alexander J; Duscher, Dominik; Tevlin, Ruth; Marecic, Owen; Lorenz, H Peter; Gurtner, Geoffrey C; Longaker, Michael T

    2016-01-07

    Fibroblasts are the principle cell type responsible for secreting extracellular matrix and are a critical component of many organs and tissues. Fibroblast physiology and pathology underlie a spectrum of clinical entities, including fibroses in multiple organs, hypertrophic scarring following burns, loss of cardiac function following ischemia, and the formation of cancer stroma. However, fibroblasts remain a poorly characterized type of cell, largely due to their inherent heterogeneity. Existing methods for the isolation of fibroblasts require time in cell culture that profoundly influences cell phenotype and behavior. Consequently, many studies investigating fibroblast biology rely upon in vitro manipulation and do not accurately capture fibroblast behavior in vivo. To overcome this problem, we developed a FACS-based protocol for the isolation of fibroblasts from the dorsal skin of adult mice that does not require cell culture, thereby preserving the physiologic transcriptional and proteomic profile of each cell. Our strategy allows for exclusion of non-mesenchymal lineages via a lineage negative gate (Lin(-)) rather than a positive selection strategy to avoid pre-selection or enrichment of a subpopulation of fibroblasts expressing specific surface markers and be as inclusive as possible across this heterogeneous cell type.

  4. Role of human pulp fibroblasts in angiogenesis.

    PubMed

    Tran-Hung, L; Mathieu, S; About, I

    2006-09-01

    After pulp amputation, complete pulp healing requires not only reparative dentin production but also fibroblast proliferation, nerve fiber growth, and neoangiogenesis. This study was designed to investigate the role of pulp fibroblasts in angiogenesis. Human pulp fibroblasts from third molars co-cultured with human umbilical vein endothelial cells induced the organization of endothelial cells and the formation of tubular structures corresponding to capillaries in vivo. The direct contact between both cells was not necessary to induce angiogenesis, and the observed effect was due to soluble factors. This was confirmed with neutralizing antibodies against FGF-2 and VEGF, which decreased the angiogenic effects of these soluble factors. Immunohistochemistry showed that both FGF-2 and VEGF were expressed in human dental pulp fibroblasts, and this expression increased after injury. These results suggest that the pulp fibroblasts secrete angiogenic factors, which are necessary for complete pulp healing, particularly at the pulp injury site.

  5. A molecular timescale of eukaryote evolution and the rise of complex multicellular life

    NASA Technical Reports Server (NTRS)

    Hedges, S. Blair; Blair, Jaime E.; Venturi, Maria L.; Shoe, Jason L.

    2004-01-01

    BACKGROUND: The pattern and timing of the rise in complex multicellular life during Earth's history has not been established. Great disparity persists between the pattern suggested by the fossil record and that estimated by molecular clocks, especially for plants, animals, fungi, and the deepest branches of the eukaryote tree. Here, we used all available protein sequence data and molecular clock methods to place constraints on the increase in complexity through time. RESULTS: Our phylogenetic analyses revealed that (i) animals are more closely related to fungi than to plants, (ii) red algae are closer to plants than to animals or fungi, (iii) choanoflagellates are closer to animals than to fungi or plants, (iv) diplomonads, euglenozoans, and alveolates each are basal to plants+animals+fungi, and (v) diplomonads are basal to other eukaryotes (including alveolates and euglenozoans). Divergence times were estimated from global and local clock methods using 20-188 proteins per node, with data treated separately (multigene) and concatenated (supergene). Different time estimation methods yielded similar results (within 5%): vertebrate-arthropod (964 million years ago, Ma), Cnidaria-Bilateria (1,298 Ma), Porifera-Eumetozoa (1,351 Ma), Pyrenomycetes-Plectomycetes (551 Ma), Candida-Saccharomyces (723 Ma), Hemiascomycetes-filamentous Ascomycota (982 Ma), Basidiomycota-Ascomycota (968 Ma), Mucorales-Basidiomycota (947 Ma), Fungi-Animalia (1,513 Ma), mosses-vascular plants (707 Ma), Chlorophyta-Tracheophyta (968 Ma), Rhodophyta-Chlorophyta+Embryophyta (1,428 Ma), Plantae-Animalia (1,609 Ma), Alveolata-plants+animals+fungi (1,973 Ma), Euglenozoa-plants+animals+fungi (1,961 Ma), and Giardia-plants+animals+fungi (2,309 Ma). By extrapolation, mitochondria arose approximately 2300-1800 Ma and plastids arose 1600-1500 Ma. Estimates of the maximum number of cell types of common ancestors, combined with divergence times, showed an increase from two cell types at 2500 Ma to

  6. Comparison of a Self-Directed and Therapist-Assisted Telehealth Parent-Mediated Intervention for Children with ASD: A Pilot RCT.

    PubMed

    Ingersoll, Brooke; Wainer, Allison L; Berger, Natalie I; Pickard, Katherine E; Bonter, Nicole

    2016-07-01

    This pilot RCT compared the effect of a self-directed and therapist-assisted telehealth-based parent-mediated intervention for young children with ASD. Families were randomly assigned to a self-directed or therapist-assisted program. Parents in both groups improved their intervention fidelity, self-efficacy, stress, and positive perceptions of their child; however, the therapist-assisted group had greater gains in parent fidelity and positive perceptions of child. Children in both groups improved on language measures, with a trend towards greater gains during a parent-child interaction for the therapist-assisted group. Only the children in the therapist-assisted group improved in social skills. Both models show promise for delivering parent-mediated intervention; however, therapist assistance provided an added benefit for some outcomes. A full-scale comparative efficacy trial is warranted.

  7. Self-directed and interpersonal male violence in adolescence and young adulthood: a 30-year follow up of a Stockholm cohort.

    PubMed

    Rojas, Yerko

    2012-01-01

    In line with Wilkinson's theory on inequality and health, this study simultaneously analyses self-directed and interpersonal violence among men in a Stockholm birth cohort born in 1953 with respect to their early life experiences of stress, their lack of social connectedness and their relative deprivation. Multinomial logistic regressions with cluster-robust variance estimates were used. Self-directed violence was found to be related to self-rated loneliness and non-membership of voluntary associations but not to a lack of friendship in school at the age of 12-13, while the opposite was shown to be true for interpersonal violence. Growing up in a family that received means-tested social assistance at least once during the period 1953-1965 was taken as an objective indicator of relative deprivation and proved to be correlated with both self-directed and interpersonal violence. Disadvantaged social comparison at the age of 12-13, taken as a subjective indicator of relative deprivation, was only statistically related to a subsequent risk of interpersonal violence. It is suggested that different types of social connectedness and relative deprivation, respectively, explain these different patterns of violence. Furthermore, the study speculates on the possibility of frequent social comparison itself being a factor to consider when trying understanding violence in general.

  8. Aragonite crystallization in primary cell cultures of multicellular isolates from a hard coral, Pocillopora damicornis.

    PubMed

    Domart-Coulon, I J; Elbert, D C; Scully, E P; Calimlim, P S; Ostrander, G K

    2001-10-09

    The foundation of marine coral reef ecosystems is calcium carbonate accumulated primarily by the action of hard corals (Coelenterata: Anthozoa: Scleractinia). Colonial hard coral polyps cover the surface of the reef and deposit calcium carbonate as the aragonite polymorph, stabilized into a continuous calcareous skeleton. Scleractinian coral skeleton composition and architecture are well documented; however, the cellular mechanisms of calcification are poorly understood. There is little information on the nature of the coral cell types involved or their cooperation in biocalcification. We report aragonite crystallization in primary cell cultures of a hard coral, Pocillopora damicornis. Cells of apical coral colony fragments were isolated by spontaneous in vitro dissociation. Single dissociated cell types were separated by density in a discontinuous Percoll gradient. Primary cell cultures displayed a transient increase in alkaline phosphatase (ALP) activity, to the level observed in intact corals. In adherent multicellular isolate cultures, enzyme activation was followed by precipitation of aragonite. Modification of the ionic formulation of the medium prolonged maintenance of isolates, delayed ALP activation, and delayed aragonite precipitation. These results demonstrate that in vitro crystallization of aragonite in coral cell cultures is possible, and provides an innovative approach to investigate reef-building coral calcification at the cellular level.

  9. Multicellular development in Myxococcus xanthus is stimulated by predator-prey interactions.

    PubMed

    Berleman, James E; Kirby, John R

    2007-08-01

    Myxococcus xanthus is a predatory bacterium that exhibits complex social behavior. The most pronounced behavior is the aggregation of cells into raised fruiting body structures in which cells differentiate into stress-resistant spores. In the laboratory, monocultures of M. xanthus at a very high density will reproducibly induce hundreds of randomly localized fruiting bodies when exposed to low nutrient availability and a solid surface. In this report, we analyze how M. xanthus fruiting body development proceeds in a coculture with suitable prey. Our analysis indicates that when prey bacteria are provided as a nutrient source, fruiting body aggregation is more organized, such that fruiting bodies form specifically after a step-down or loss of prey availability, whereas a step-up in prey availability inhibits fruiting body formation. This localization of aggregates occurs independently of the basal nutrient levels tested, indicating that starvation is not required for this process. Analysis of early developmental signaling relA and asgD mutants indicates that they are capable of forming fruiting body aggregates in the presence of prey, demonstrating that the stringent response and A-signal production are surprisingly not required for the initiation of fruiting behavior. However, these strains are still defective in differentiating to spores. We conclude that fruiting body formation does not occur exclusively in response to starvation and propose an alternative model in which multicellular development is driven by the interactions between M. xanthus cells and their cognate prey.

  10. Agent-based model of angiogenesis simulates capillary sprout initiation in multicellular networks.

    PubMed

    Walpole, J; Chappell, J C; Cluceru, J G; Mac Gabhann, F; Bautch, V L; Peirce, S M

    2015-09-01

    Many biological processes are controlled by both deterministic and stochastic influences. However, efforts to model these systems often rely on either purely stochastic or purely rule-based methods. To better understand the balance between stochasticity and determinism in biological processes a computational approach that incorporates both influences may afford additional insight into underlying biological mechanisms that give rise to emergent system properties. We apply a combined approach to the simulation and study of angiogenesis, the growth of new blood vessels from existing networks. This complex multicellular process begins with selection of an initiating endothelial cell, or tip cell, which sprouts from the parent vessels in response to stimulation by exogenous cues. We have constructed an agent-based model of sprouting angiogenesis to evaluate endothelial cell sprout initiation frequency and location, and we have experimentally validated it using high-resolution time-lapse confocal microscopy. ABM simulations were then compared to a Monte Carlo model, revealing that purely stochastic simulations could not generate sprout locations as accurately as the rule-informed agent-based model. These findings support the use of rule-based approaches for modeling the complex mechanisms underlying sprouting angiogenesis over purely stochastic methods.

  11. Simulated evolution of the vertebral body based on basic multicellular unit activities.

    PubMed

    Wang, Chao; Zhang, Chunqiu; Han, Jingyun; Wu, Han; Fan, Yubo

    2011-07-01

    A numerical model based on the theory of bone remodeling is proposed to predict the evolution of trabecular bone architecture within the vertebral body and to investigate the process of degeneration in vertebral bone. In this study, particular attention is paid on the description of microstructure changes during the aging process. To take into account the effect of basic multicellular units (BMUs), a set of computational algorithms has been developed. It is assumed that BMU activation probability depends on the state of damaged bone tissue (damage accumulation, ω), which is evaluated according to previous research concerning bone fatigue damage. Combining these algorithms with the finite-element method (FEM), the microstructure of vertebral bone has been predicted for up to 8 simulated years. Moreover, biomechanical material properties have been monitored to investigate the changes of vertebral bone with age. This study shows that the simulation based on BMU activities has the potential to define and predict the morphological evolution of the vertebral body. It can be concluded that the novel algorithms incorporating the coupled effects of both adaptive remodeling and microdamage remodeling could be utilized to gain greater insight into the mechanism of bone loss in the elderly population.

  12. A Novel Computer-Assisted Approach to evaluate Multicellular Tumor Spheroid Invasion Assay

    PubMed Central

    Cisneros Castillo, Liliana R.; Oancea, Andrei-Dumitru; Stüllein, Christian; Régnier-Vigouroux, Anne

    2016-01-01

    Multicellular tumor spheroids (MCTSs) embedded in a matrix are re-emerging as a powerful alternative to monolayer-based cultures. The primary information gained from a three-dimensional model is the invasiveness of treatment-exposed MCTSs through the acquisition of light microscopy images. The amount and complexity of the acquired data and the bias arisen by their manual analysis are disadvantages calling for an automated, high-throughput analysis. We present a universal algorithm we developed with the scope of being robust enough to handle images of various qualities and various invasion profiles. The novelty and strength of our algorithm lie in: the introduction of a multi-step segmentation flow, where each step is optimized for each specific MCTS area (core, halo, and periphery); the quantification through the density of the two-dimensional representation of a three-dimensional object. This latter offers a fine-granular differentiation of invasive profiles, facilitating a quantification independent of cell lines and experimental setups. Progression of density from the core towards the edges influences the resulting density map thus providing a measure no longer dependent on the sole area size of MCTS, but also on its invasiveness. In sum, we propose a new method in which the concept of quantification of MCTS invasion is completely re-thought. PMID:27731418

  13. Rapid Generation of In Vitro Multicellular Spheroids for the Study of Monoclonal Antibody Therapy

    PubMed Central

    Phung, Yen T.; Barbone, Dario; Broaddus, V. Courtney; Ho, Mitchell

    2011-01-01

    Tumor microenvironments present significant barriers to penetration by antibodies and immunoconjugates and are difficult to study in vitro. Cells cultured as monolayers typically exhibit less resistance to therapy than those grown in vivo. Therefore, it is important to develop an alternative research model that better represents in vivo tumors. We have developed a protocol to produce multicellular spheroids, a simple and more relevant model of in vivo tumors that allows for further investigations of the microenvironmental effects on drug penetration and tumor cell killing. The protocol is used to produce in vitro three-dimensional tumor spheroids from established human cancer cell lines and primary cancer cells isolated from patients without the use of any extracellular components. To study the ability of tumor-targeting immunoconjugates to penetrate these tumor spheroids in vitro, we have used an immunotoxin targeting mesothelin, a surface protein expressed in malignant mesotheliomas. This method for producing consistent, reproducible 3D spheroids may allow for improved testing of novel monoclonal antibodies and other agents for their ability to penetrate solid tumors for cancer therapy. PMID:22043235

  14. Imaging of bacterial multicellular behaviour in biofilms in liquid by atmospheric scanning electron microscopy

    PubMed Central

    Sugimoto, Shinya; Okuda, Ken-ichi; Miyakawa, Reina; Sato, Mari; Arita-Morioka, Ken-ichi; Chiba, Akio; Yamanaka, Kunitoshi; Ogura, Teru; Mizunoe, Yoshimitsu; Sato, Chikara

    2016-01-01

    Biofilms are complex communities of microbes that attach to biotic or abiotic surfaces causing chronic infectious diseases. Within a biofilm, microbes are embedded in a self-produced soft extracellular matrix (ECM), which protects them from the host immune system and antibiotics. The nanoscale visualisation of delicate biofilms in liquid is challenging. Here, we develop atmospheric scanning electron microscopy (ASEM) to visualise Gram-positive and -negative bacterial biofilms immersed in aqueous solution. Biofilms cultured on electron-transparent film were directly imaged from below using the inverted SEM, allowing the formation of the region near the substrate to be studied at high resolution. We visualised intercellular nanostructures and the exocytosis of membrane vesicles, and linked the latter to the trafficking of cargos, including cytoplasmic proteins and the toxins hemolysin and coagulase. A thick dendritic nanotube network was observed between microbes, suggesting multicellular communication in biofilms. A universal immuno-labelling system was developed for biofilms and tested on various examples, including S. aureus biofilms. In the ECM, fine DNA and protein networks were visualised and the precise distribution of protein complexes was determined (e.g., straight curli, flagella, and excreted cytoplasmic molecular chaperones). Our observations provide structural insights into bacteria-substratum interactions, biofilm development and the internal microbe community. PMID:27180609

  15. Surface acoustic streaming in microfluidic system for rapid multicellular tumor spheroids generation

    NASA Astrophysics Data System (ADS)

    AlHasan, Layla; Qi, Aisha; Al-Aboodi, Aswan; Rezk, Amged; Shilton, Richie R.; Chan, Peggy P. Y.; Friend, James; Yeo, Leslie

    2013-12-01

    In this study, we developed a novel and rapid method to generate in vitro three-dimensional (3D) multicellular tumor spheroids using a surface acoustic wave (SAW) device. A SAW device with single-phase unidirectional transducer electrodes (SPUTD) on lithium niobate substrate was fabricated using standing UV photolithography and wet-etching techniques. To generate spheroids, the SAW device was loaded with medium containing human breast carcinoma (BT474) cells, an oscillating electrical signal at resonant frequency was supplied to the SPUDT to generate acoustic radiation in the medium. Spheroids with uniform size and shape can be obtained using this method in less than 1 minute, and the size of the spheroids can be controlled through adjusting the seeding density. The resulting spheroids were used for further cultivation and were monitored using an optical microscope in real time. The viability and actin organization of the spheroids were assessed using live/dead viability staining and actin cytoskeleton staining, respectively. Compared to spheroids generated using the liquid overlay method, the SAW generated spheroids exhibited higher circularity and higher viability. The F-actin filaments of spheroids appear to aggregate compared to that of untreated cells, indicating that mature spheroids can be obtained using this method. This spheroid generating method can be useful for a variety of biological studies and clinical applications.

  16. Response of human neuroblastoma and melanoma multicellular tumor spheroids (MTS) to single dose irradiation

    SciTech Connect

    Evans, S.M.; Labs, L.M.; Yuhas, J.M.

    1986-06-01

    The growth characteristics of 6 human cell line derived multicellular tumor spheroids (MTS) were studied. Melanoma MTS (C32, HML-A, HML-B) were slow growing with baseline growth rates of 13.9 to 27.3 microns diameter/day. Neuroblastoma MTS (Lan-1, NB-100, NB-134) grew rapidly, with baseline growth rates of 32.1 to 40.3 microns diameter/day, that is, 1.2 to 2.9 times as fast as the melanomas. Delay constants were calculated for all six lines. The neuroblastomas were more sensitive to radiation than melanomas, as reflected in a greater value for the radiation-induced growth delay constant. One neuroblastoma line, Lan-1, was highly radioresponsive; that is, after a subcurative dose of radiation, the MTS diameter decreased beyond the original diameter, which was followed by recovery and regrowth. Irrespective of these initial changes in diameter, growth delay sensitivity (value of delay constant) was the same for Lan-1 and NB-100, an MTS line that did not show the responsive pattern.

  17. A multicellular spheroid array to realize spheroid formation, culture, and viability assay on a chip.

    PubMed

    Torisawa, Yu-suke; Takagi, Airi; Nashimoto, Yuji; Yasukawa, Tomoyuki; Shiku, Hitoshi; Matsue, Tomokazu

    2007-01-01

    We describe a novel multicellular spheroid culture system that facilitates the easy preparation and culture of a spheroid microarray for the long-term monitoring of cellular activity. A spheroid culture device with an array of pyramid-like microholes was constructed in a silicon chip that was equipped with elastomeric microchannels. A cell suspension was introduced via the microfluidic channel into the microstructure that comprised silicon microholes and elastomeric microwells. A single spheroid can be formed and localized precisely within each microstructure. Since the culture medium could be replaced via the microchannels, a long-term culture (of approximately 2 weeks) is available on the chip. Measurement of albumin production in the hepatoma cell line (HepG2) showed that the liver-specific functions were maintained for 2 weeks. Based on the cellular respiratory activity, the cellular viability of the spheroid array on the chip was evaluated using scanning electrochemical microscopy. Responses to four different chemical stimulations were simultaneously detected on the same chip, thus demonstrating that each channel could be evaluated independently under various stimulation conditions. Our spheroid culture system facilitated the understanding of spheroid formation, culture, and viability assay on a single chip, thus functioning as a useful drug-screening device for cancer and liver cells.

  18. Electrical behavior and pore accumulation in a multicellular model for conventional and supra-electroporation

    SciTech Connect

    Gowrishankar, T.R.; Weaver, James C. . E-mail: jcw@mit.edu

    2006-10-20

    Extremely large but very short (20 kV/cm, 300 ns) electric field pulses were reported recently to non-thermally destroy melanoma tumors. The stated mechanism for field penetration into cells is pulse characteristic times faster than charge redistribution (displacement currents). Here we use a multicellular model with irregularly shaped, closely spaced cells to show that instead overwhelming pore creation (supra-electroporation) is dominant, with field penetration due to pores (ionic conduction currents) during most of the pulse. Moreover, the model's maximum membrane potential (about 1.2 V) is consistent with recent experimental observations on isolated cells. We also use the model to show that conventional electroporation resulting from 100 microsecond, 1 kV/cm pulses yields a spatially heterogeneous electroporation distribution. In contrast, the melanoma-destroying pulses cause nearly homogeneous electroporation of cells and their nuclear membranes. Electropores can persist for times much longer than the pulses, and are likely to be an important mechanism contributing to cell death.

  19. Study of the tensile properties of individual multicellular fibres generated by Bacillus subtilis

    PubMed Central

    Ye, Xuan; Zhao, Liang; Liang, Jiecun; Li, Xide; Chen, Guo-Qiang

    2017-01-01

    Multicellular fibres formed by Bacillus subtilis (B. subtilis) are attracting interest because of their potential application as degradable biomaterials. However, mechanical properties of individual fibres remain unknown because of their small dimensions. Herein, a new approach is developed to investigate the tensile properties of individual fibres with an average diameter of 0.7 μm and a length range of 25.7–254.3 μm. Variations in the tensile strengths of fibres are found to be the result of variable interactions among pairs of microbial cells known as septa. Using Weibull weakest-link model to study this mechanical variability, we predict the length effect of the sample. Moreover, the mechanical properties of fibres are found to depend highly on relative humidity (RH), with a brittle–ductile transition occurring around RH = 45%. The elastic modulus is 5.8 GPa in the brittle state, while decreases to 62.2 MPa in the ductile state. The properties of fibres are investigated by using a spring model (RH < 45%) for its elastic behaviour, and the Kelvin–Voigt model (RH > 45%) for the time-dependent response. Loading-unloading experiments and numerical calculations demonstrate that necking instability comes from structural changes (septa) and viscoelasticity dominates the deformation of fibres at high RH. PMID:28378797

  20. Induction of hypoxia and necrosis in multicellular tumor spheroids is associated with resistance to chemotherapy treatment

    PubMed Central

    Calabrese, Diego; Ivanek, Robert; Turrini, Eleonora; Droeser, Raoul A.; Zajac, Paul; Fimognari, Carmela; Spagnoli, Giulio C.; Iezzi, Giandomenica; Mele, Valentina; Muraro, Manuele G.

    2017-01-01

    Culture of cancerous cells in standard monolayer conditions poorly mirrors growth in three-dimensional architectures typically observed in a wide majority of cancers of different histological origin. Multicellular tumor spheroid (MCTS) culture models were developed to mimic these features. However, in vivo tumor growth is also characterized by the presence of ischemic and necrotic areas generated by oxygenation gradients and differential access to nutrients. Hypoxia and necrosis play key roles in tumor progression and resistance to treatment. To provide in vitro models recapitulating these events in highly controlled and standardized conditions, we have generated colorectal cancer (CRC) cell spheroids of different sizes and analyzed their gene expression profiles and sensitivity to treatment with 5FU, currently used in therapeutic protocols. Here we identify three MCTS stages, corresponding to defined spheroid sizes, characterized by normoxia, hypoxia, and hypoxia plus necrosis, respectively. Importantly, we show that MCTS including both hypoxic and necrotic areas most closely mimic gene expression profiles of in vivo-developing tumors and display the highest resistance to 5FU. Taken together, our data indicate that MCTS may mimic in vitro generation of ischemic and necrotic areas in highly standardized and controlled conditions, thereby qualifying as relevant models for drug screening purposes. PMID:27965457

  1. A novel genus of multicellular magnetotactic prokaryotes from the Yellow Sea.

    PubMed

    Zhou, Ke; Zhang, Wen-Yan; Yu-Zhang, Kui; Pan, Hong-Miao; Zhang, Sheng-Da; Zhang, Wei-Jia; Yue, Hai-Dong; Li, Ying; Xiao, Tian; Wu, Long-Fei

    2012-02-01

    Multicellular magnetotactic prokaryotes (MMPs) are a group of magnetotactic microorganisms composed of 10-40 Gram-negative cells. Currently, all the identified MMPs show a spherical morphology and synthesize mainly iron sulfide magnetosomes. In this study, we report a novel genus of MMPs with peculiar ellipsoidal morphology and iron oxide magnetosomes, which were discovered in intertidal sediment of the Yellow Sea in China. Optical and fluorescence microscopy revealed that this organism was ~10 × 8 µm in size and composed of ~40 cells enveloped by an outer layer. Scanning electron microscopy showed that the cells were arranged in 4-6 interlaced circles. Bullet-shaped magnetite magnetosomes were organized in chains roughly parallel to the long axis of the ellipsoidal MMPs when analysed by transmission electron microscopy. These MMPs displayed special escape motility, i.e. swimming rapidly from the edge to the centre of the droplet and then slowly back to the edge. In addition, they exhibited negative phototaxis. Light microscopy observations showed that the ellipsoidal MMPs reproduced by division along the body long axis. Both analysis of 16S rRNA gene sequence and fluorescence in situ hybridization revealed the ellipsoidal MMPs as a new genus of the Deltaproteobacteria. In summary, this novel genus of MMPs exhibit unique morphology, peculiar division process and distinct phylogenetic affiliation compared with the other MMPs.

  2. Characterization of Hydrogen Metabolism in the Multicellular Green Alga Volvox carteri

    SciTech Connect

    Cornish, Adam J.; Green, Robin; Gärtner, Katrin; Mason, Saundra; Hegg, Eric L.

    2015-04-30

    Hydrogen gas functions as a key component in the metabolism of a wide variety of microorganisms, often acting as either a fermentative end-product or an energy source. The number of organisms reported to utilize hydrogen continues to grow, contributing to and expanding our knowledge of biological hydrogen processes. Here we demonstrate that Volvox carteri f. nagariensis, a multicellular green alga with differentiated cells, evolves H2 both when supplied with an abiotic electron donor and under physiological conditions. The genome of Volvox carteri contains two genes encoding putative [FeFe]-hydrogenases (HYDA1 and HYDA2), and the transcripts for these genes accumulate under anaerobic conditions. The HYDA1 and HYDA2 gene products were cloned, expressed, and purified, and both are functional [FeFe]-hydrogenases. Additionally, within the genome the HYDA1 and HYDA2 genes cluster with two putative genes which encode hydrogenase maturation proteins. This gene cluster resembles operon-like structures found within bacterial genomes and may provide further insight into evolutionary relationships between bacterial and algal [FeFe]-hydrogenase genes.

  3. Aragonite crystallization in primary cell cultures of multicellular isolates from a hard coral, Pocillopora damicornis

    PubMed Central

    Domart-Coulon, Isabelle J.; Elbert, David C.; Scully, Erik P.; Calimlim, Precilia S.; Ostrander, Gary K.

    2001-01-01

    The foundation of marine coral reef ecosystems is calcium carbonate accumulated primarily by the action of hard corals (Coelenterata: Anthozoa: Scleractinia). Colonial hard coral polyps cover the surface of the reef and deposit calcium carbonate as the aragonite polymorph, stabilized into a continuous calcareous skeleton. Scleractinian coral skeleton composition and architecture are well documented; however, the cellular mechanisms of calcification are poorly understood. There is little information on the nature of the coral cell types involved or their cooperation in biocalcification. We report aragonite crystallization in primary cell cultures of a hard coral, Pocillopora damicornis. Cells of apical coral colony fragments were isolated by spontaneous in vitro dissociation. Single dissociated cell types were separated by density in a discontinuous Percoll gradient. Primary cell cultures displayed a transient increase in alkaline phosphatase (ALP) activity, to the level observed in intact corals. In adherent multicellular isolate cultures, enzyme activation was followed by precipitation of aragonite. Modification of the ionic formulation of the medium prolonged maintenance of isolates, delayed ALP activation, and delayed aragonite precipitation. These results demonstrate that in vitro crystallization of aragonite in coral cell cultures is possible, and provides an innovative approach to investigate reef-building coral calcification at the cellular level. PMID:11593000

  4. Characterization of Hydrogen Metabolism in the Multicellular Green Alga Volvox carteri.

    PubMed

    Cornish, Adam J; Green, Robin; Gärtner, Katrin; Mason, Saundra; Hegg, Eric L

    2015-01-01

    Hydrogen gas functions as a key component in the metabolism of a wide variety of microorganisms, often acting as either a fermentative end-product or an energy source. The number of organisms reported to utilize hydrogen continues to grow, contributing to and expanding our knowledge of biological hydrogen processes. Here we demonstrate that Volvox carteri f. nagariensis, a multicellular green alga with differentiated cells, evolves H2 both when supplied with an abiotic electron donor and under physiological conditions. The genome of Volvox carteri contains two genes encoding putative [FeFe]-hydrogenases (HYDA1 and HYDA2), and the transcripts for these genes accumulate under anaerobic conditions. The HYDA1 and HYDA2 gene products were cloned, expressed, and purified, and both are functional [FeFe]-hydrogenases. Additionally, within the genome the HYDA1 and HYDA2 genes cluster with two putative genes which encode hydrogenase maturation proteins. This gene cluster resembles operon-like structures found within bacterial genomes and may provide further insight into evolutionary relationships between bacterial and algal [FeFe]-hydrogenase genes.

  5. Low-temperature plasma-induced antiproliferative effects on multi-cellular tumor spheroids

    NASA Astrophysics Data System (ADS)

    Plewa, Joseph-Marie; Yousfi, Mohammed; Frongia, Céline; Eichwald, Olivier; Ducommun, Bernard; Merbahi, Nofel; Lobjois, Valérie

    2014-04-01

    Biomedical applications of low-temperature plasmas are of growing interest, especially in the field of plasma-induced anti-tumor effects. The present work is aimed at investigating the regionalized antiproliferative effects of low-temperature plasmas on a multicellular tumor spheroid (MCTS), a model that mimics the 3D organization and regionalization of a microtumor region. We report that a low-temperature plasma jet, using helium flow in open air, inhibits HCT116 colon carcinoma MCTS growth in a dose-dependent manner. This growth inhibition is associated with the loss of Ki67, and the regionalized accumulation of DNA damage detected by histone H2AX phosphorylation. This regionalized genotoxic effect leads to massive cell death and loss of the MCTS proliferative region. The use of reactive oxygen species (ROS), scavenger N-acetyl cysteine (NAC) and plasma-conditioned media demonstrate that the ROS generated in the media after exposure to low-temperature plasma play a major role in these observed effects. These findings strengthen the interest in the use of MCTS for the evaluation of antiproliferative strategies, and open new perspectives for studies dedicated to demonstrate the potential of low-temperature plasma in cancer therapy.

  6. Evolution of an ancient protein function involved in organized multicellularity in animals

    PubMed Central

    Anderson, Douglas P; Whitney, Dustin S; Hanson-Smith, Victor; Woznica, Arielle; Campodonico-Burnett, William; Volkman, Brian F; King, Nicole; Thornton, Joseph W; Prehoda, Kenneth E

    2016-01-01

    To form and maintain organized tissues, multicellular organisms orient their mitotic spindles relative to neighboring cells. A molecular complex scaffolded by the GK protein-interaction domain (GKPID) mediates spindle orientation in diverse animal taxa by linking microtubule motor proteins to a marker protein on the cell cortex localized by external cues. Here we illuminate how this complex evolved and commandeered control of spindle orientation from a more ancient mechanism. The complex was assembled through a series of molecular exploitation events, one of which – the evolution of GKPID’s capacity to bind the cortical marker protein – can be recapitulated by reintroducing a single historical substitution into the reconstructed ancestral GKPID. This change revealed and repurposed an ancient molecular surface that previously had a radically different function. We show how the physical simplicity of this binding interface enabled the evolution of a new protein function now essential to the biological complexity of many animals. DOI: http://dx.doi.org/10.7554/eLife.10147.001 PMID:26740169

  7. A Novel Computer-Assisted Approach to evaluate Multicellular Tumor Spheroid Invasion Assay

    NASA Astrophysics Data System (ADS)

    Cisneros Castillo, Liliana R.; Oancea, Andrei-Dumitru; Stüllein, Christian; Régnier-Vigouroux, Anne

    2016-10-01

    Multicellular tumor spheroids (MCTSs) embedded in a matrix are re-emerging as a powerful alternative to monolayer-based cultures. The primary information gained from a three-dimensional model is the invasiveness of treatment-exposed MCTSs through the acquisition of light microscopy images. The amount and complexity of the acquired data and the bias arisen by their manual analysis are disadvantages calling for an automated, high-throughput analysis. We present a universal algorithm we developed with the scope of being robust enough to handle images of various qualities and various invasion profiles. The novelty and strength of our algorithm lie in: the introduction of a multi-step segmentation flow, where each step is optimized for each specific MCTS area (core, halo, and periphery); the quantification through the density of the two-dimensional representation of a three-dimensional object. This latter offers a fine-granular differentiation of invasive profiles, facilitating a quantification independent of cell lines and experimental setups. Progression of density from the core towards the edges influences the resulting density map thus providing a measure no longer dependent on the sole area size of MCTS, but also on its invasiveness. In sum, we propose a new method in which the concept of quantification of MCTS invasion is completely re-thought.

  8. [The ESCRT complex: from endosomal transport to the development of multicellular organisms].

    PubMed

    Juan, Thomas; Fürthauer, Maximilian

    2015-01-01

    Since its discovery more than 50 years ago, the endo-lysosomal system has emerged as a central integrator of different cellular activities. This vesicular trafficking apparatus governs processes as diverse as the transduction of stimuli by growth factor receptors, the recycling and secretion of signaling molecules and the regulation of cellular homeostasis through autophagy. Accordingly, dysfunctions of the vesicular transport machinery have been linked to a growing number of pathologies. In this review we take the "Endosomal Sorting Complex Required for Transport" (ESCRT) as an example to illustrate the multiple functions of an evolutionarily conserved endosomal transport machinery. We describe the major concepts that have emerged from the study of this machinery at the level of the development and the physiology of multi-cellular organisms. In particular, we highlight the essential contributions of ESCRT proteins on the regulation of three biological processes: the endocytic regulation of cell signaling, autophagy and its role in neuronal morphogenesis and finally the biogenesis and function of extracellular vesicles.

  9. The Demosponge Amphimedon queenslandica: Reconstructing the Ancestral Metazoan Genome and Deciphering the Origin of Animal Multicellularity.

    PubMed

    Degnan, Bernard M; Adamska, Maja; Craigie, Alina; Degnan, Sandie M; Fahey, Bryony; Gauthier, Marie; Hooper, John N A; Larroux, Claire; Leys, Sally P; Lovas, Erica; Richards, Gemma S

    2008-12-01

    INTRODUCTIONSponges are one of the earliest branching metazoans. In addition to undergoing complex development and differentiation, they can regenerate via stem cells and can discern self from nonself ("allorecognition"), making them a useful comparative model for a range of metazoan-specific processes. Molecular analyses of these processes have the potential to reveal ancient homologies shared among all living animals and critical genomic innovations that underpin metazoan multicellularity. Amphimedon queenslandica (Porifera, Demospongiae, Haplosclerida, Niphatidae) is the first poriferan representative to have its genome sequenced, assembled, and annotated. Amphimedon exemplifies many sessile and sedentary marine invertebrates (e.g., corals, ascidians, bryozoans): They disperse during a planktonic larval phase, settle in the vicinity of conspecifics, ward off potential competitors (including incompatible genotypes), and ensure that brooded eggs are fertilized by conspecific sperm. Using genomic and expressed sequence tag (EST) resources from Amphimedon, functional genomic approaches can be applied to a wide range of ecological and population genetic processes, including fertilization, dispersal, and colonization dynamics, host-symbiont interactions, and secondary metabolite production. Unlike most other sponges, Amphimedon produce hundreds of asynchronously developing embryos and larvae year-round in distinct, easily accessible brood chambers. Embryogenesis gives rise to larvae with at least a dozen cell types that are segregated into three layers and patterned along the body axis. In this article, we describe some of the methods currently available for studying A. queenslandica, focusing on the analysis of embryos, larvae, and post-larvae.

  10. Realistic multi-cellular dosimetry for 177Lu-labelled antibodies: model and application

    NASA Astrophysics Data System (ADS)

    Marcatili, S.; Pichard, A.; Courteau, A.; Ladjohounlou, R.; Navarro-Teulon, I.; Repetto-Llamazares, A.; Heyerdahl, H.; Dahle, J.; Pouget, J. P.; Bardiès, M.

    2016-10-01

    Current preclinical dosimetric models often fail to take account of the complex nature of absorbed dose distribution typical of in vitro clonogenic experiments in targeted radionuclide therapy. For this reason, clonogenic survival is often expressed as a function of added activity rather than the absorbed dose delivered to cells/cell nuclei. We designed a multi-cellular dosimetry model that takes into account the realistic distributions of cells in the Petri dish, for the establishment of survival curves as a function of the absorbed dose. General-purpose software tools were used for the generation of realistic, randomised 3D cell culture geometries based on experimentally determined parameters (cell size, cell density, cluster density, average cluster size, cell cumulated activity). A mixture of Monte Carlo and analytical approaches was implemented in order to achieve as accurate as possible results while reducing calculation time. The model was here applied to clonogenic survival experiments carried out to compare the efficacy of Betalutin®, a novel 177Lu-labelled antibody radionuclide conjugate for the treatment of non-Hodgkin lymphoma, to that of 177Lu-labelled CD20-specific (rituximab) and non-specific antibodies (Erbitux) on lymphocyte B cells. The 3D cellular model developed allowed a better understanding of the radiative and non-radiative processes associated with cellular death. Our approach is generic and can also be applied to other radiopharmaceuticals and cell distributions.

  11. Nuclear DNA Content Estimates in Multicellular Green, Red and Brown Algae: Phylogenetic Considerations

    PubMed Central

    KAPRAUN, DONALD F.

    2005-01-01

    • Background and Aims Multicellular eukaryotic algae are phylogenetically disparate. Nuclear DNA content estimates have been published for fewer than 1 % of the described species of Chlorophyta, Phaeophyta and Rhodophyta. The present investigation aims to summarize the state of our knowledge and to add substantially to our database of C-values for theses algae. • Methods The DNA-localizing fluorochrome DAPI (4′, 6-diamidino-2-phenylindole) and RBC (chicken erythrocyte) standard were used to estimate 2C values with static microspectrophotometry. • Key Results 2C DNA contents for 85 species of Chlorophyta range from 0·2–6·1 pg, excluding the highly polyploidy Charales and Desmidiales with DNA contents of up to 39·2 and 20·7 pg, respectively. 2C DNA contents for 111 species of Rhodophyta range from 0·1–2·8 pg, and for 44 species of Phaeophyta range from 0·2–1·8 pg. • Conclusions New availability of consensus higher-level molecular phylogenies provides a framework for viewing C-value data in a phylogenetic context. Both DNA content ranges and mean values are greater in taxa considered to be basal. It is proposed that the basal, ancestral genome in each algal group was quite small. Both mechanistic and ecological processes are discussed that could have produced the observed C-value ranges. PMID:15596456

  12. Clonal yeast biofilms can reap competitive advantages through cell differentiation without being obligatorily multicellular.

    PubMed

    Regenberg, Birgitte; Hanghøj, Kristian Ebbesen; Andersen, Kaj Scherz; Boomsma, Jacobus J

    2016-11-16

    How differentiation between cell types evolved is a fundamental question in biology, but few studies have explored single-gene phenotypes that mediate first steps towards division of labour with selective advantage for groups of cells. Here, we show that differential expression of the FLO11 gene produces stable fractions of Flo11(+) and Flo11(-) cells in clonal Saccharomyces cerevisiae biofilm colonies on medium with intermediate viscosity. Differentiated Flo11(+/-) colonies, consisting of adhesive and non-adhesive cells, obtain a fourfold growth advantage over undifferentiated colonies by overgrowing glucose resources before depleting them, rather than depleting them while they grow as undifferentiated Flo11(-) colonies do. Flo11(+/-) colonies maintain their structure and differentiated state by switching non-adhesive cells to adhesive cells with predictable probability. Mixtures of Flo11(+) and Flo11(-) cells from mutant strains that are unable to use this epigenetic switch mechanism produced neither integrated colonies nor growth advantages, so the condition-dependent selective advantages of differentiated FLO11 expression can only be reaped by clone-mate cells. Our results show that selection for cell differentiation in clonal eukaryotes can evolve before the establishment of obligate undifferentiated multicellularity, and without necessarily leading to more advanced organizational complexity.

  13. Synchrotron Radiation μ-X Ray Fluorescence on Multicellular Tumor Spheroids

    NASA Astrophysics Data System (ADS)

    Burattini, E.; Cinque, G.; Bellisola, G.; Fracasso, G.; Monti, F.; Colombatti, M.

    2003-01-01

    Synchrotron Radiation micro X-Ray Fluorescence (SR μ-XRF) was applied for the first time to map the trace element content on Multicellular Tumor Spheroids (MTS), i.e. human cell clusters used as an in vitro model for testing micrometastases responses to antitumoral drugs. In particular, immunotoxin molecules composed of a carrier protein (Transferrin) bound to a powerful cytotoxin (Ricin A), were here considered as representatives of a class of therapheutic macromolecules used in cancer theraphy. Spheroids included in polyacrylamide gel and placed inside quartz capillaries were studied at the ESRF ID22 beamline using a 15 keV monochromatic photon microbeam. Elemental maps (of Fe, Cu, Zn and Pb) on four groups of spheroids grown under different conditions were studied: untreated, treated only with the carrier molecule or with the toxin alone, and with the complete immunotoxin molecule (carrier+toxin). The results indicate that the distribution of Zn and, to some extent, Cu in the spheroid cells is homogeneous and independent of the treatment type. Total Reflection X-Ray Fluorescence (TR-XRF) was also applied to quantify the average trace element content in the spheroids. Future developments of the technique are finally outlined on the basis of these preliminary results.

  14. Synchrotron Radiation {mu}-X Ray Fluorescence on Multicellular Tumor Spheroids

    SciTech Connect

    Burattini, E.; Cinque, G.; Bellisola, G.; Fracasso, G.; Colombatti, M.; Monti, F.

    2003-01-24

    Synchrotron Radiation micro X-Ray Fluorescence (SR {mu}-XRF) was applied for the first time to map the trace element content on Multicellular Tumor Spheroids (MTS), i.e. human cell clusters used as an in vitro model for testing micrometastases responses to antitumoral drugs. In particular, immunotoxin molecules composed of a carrier protein (Transferrin) bound to a powerful cytotoxin (Ricin A), were here considered as representatives of a class of therapheutic macromolecules used in cancer theraphy. Spheroids included in polyacrylamide gel and placed inside quartz capillaries were studied at the ESRF ID22 beamline using a 15 keV monochromatic photon microbeam. Elemental maps (of Fe, Cu, Zn and Pb) on four groups of spheroids grown under different conditions were studied: untreated, treated only with the carrier molecule or with the toxin alone, and with the complete immunotoxin molecule (carrier+toxin). The results indicate that the distribution of Zn and, to some extent, Cu in the spheroid cells is homogeneous and independent of the treatment type. Total Reflection X-Ray Fluorescence (TR-XRF) was also applied to quantify the average trace element content in the spheroids. Future developments of the technique are finally outlined on the basis of these preliminary results.

  15. Adaptation of spherical multicellular magnetotactic prokaryotes to the geochemically variable habitat of an intertidal zone.

    PubMed

    Zhou, Ke; Zhang, Wen-Yan; Pan, Hong-Miao; Li, Jin-Hua; Yue, Hai-Dong; Xiao, Tian; Wu, Long-Fei

    2013-05-01

    A combination of microscopic, molecular and biogeochemical methods was used to study the structure, phylogenetics and vertical distribution of spherical multicellular magnetotactic prokaryotes (MMPs) of intertidal sediments in the Yellow Sea. These MMPs were 5.5 μm in diameter and composed of approximately 15-30 cells. They synthesized bullet-shaped magnetites in chains or clusters. Phylogenetic analysis of 16S rRNA gene sequences suggested that these MMPs represent a novel species affiliated to the Deltaproteobacteria. To study their vertical distribution and the relationship to geochemical parameters, sediment cores were collected after the redox potential was measured in situ. The sediments were composed of yellow, grey and black layers from the surface to depth. The spherical MMPs were concentrated near the grey-black layer transition at a depth of 8-12 cm, while coccoid-shaped magnetotactic bacteria near the yellow-grey layer transition at a depth of 3-5 cm. The intertidal MMPs showed a deeper distribution at more reduced environments than coccoid-shaped magnetotactic bacteria, and MMPs in lagoon sediments. Additionally the MMPs were concentrated significantly in layers with high proportion of fine sand and total organic carbon, rich in leachable iron but poor in nitrate. These results show an adaptation of spherical MMPs to the peculiar intertidal sediment habitat.

  16. Characterization of Hydrogen Metabolism in the Multicellular Green Alga Volvox carteri

    DOE PAGES

    Cornish, Adam J.; Green, Robin; Gärtner, Katrin; ...

    2015-04-30

    Hydrogen gas functions as a key component in the metabolism of a wide variety of microorganisms, often acting as either a fermentative end-product or an energy source. The number of organisms reported to utilize hydrogen continues to grow, contributing to and expanding our knowledge of biological hydrogen processes. Here we demonstrate that Volvox carteri f. nagariensis, a multicellular green alga with differentiated cells, evolves H2 both when supplied with an abiotic electron donor and under physiological conditions. The genome of Volvox carteri contains two genes encoding putative [FeFe]-hydrogenases (HYDA1 and HYDA2), and the transcripts for these genes accumulate under anaerobicmore » conditions. The HYDA1 and HYDA2 gene products were cloned, expressed, and purified, and both are functional [FeFe]-hydrogenases. Additionally, within the genome the HYDA1 and HYDA2 genes cluster with two putative genes which encode hydrogenase maturation proteins. This gene cluster resembles operon-like structures found within bacterial genomes and may provide further insight into evolutionary relationships between bacterial and algal [FeFe]-hydrogenase genes.« less

  17. Transcriptional control of cardiac fibroblast plasticity.

    PubMed

    Lighthouse, Janet K; Small, Eric M

    2016-02-01

    Cardiac fibroblasts help maintain the normal architecture of the healthy heart and are responsible for scar formation and the healing response to pathological insults. Various genetic, biomechanical, or humoral factors stimulate fibroblasts to become contractile smooth muscle-like cells called myofibroblasts that secrete large amounts of extracellular matrix. Unfortunately, unchecked myofibroblast activation in heart disease leads to pathological fibrosis, which is a major risk factor for the development of cardiac arrhythmias and heart failure. A better understanding of the molecular mechanisms that control fibroblast plasticity and myofibroblast activation is essential to develop novel strategies to specifically target pathological cardiac fibrosis without disrupting the adaptive healing response. This review highlights the major transcriptional mediators of fibroblast origin and function in development and disease. The contribution of the fetal epicardial gene program will be discussed in the context of fibroblast origin in development and following injury, primarily focusing on Tcf21 and C/EBP. We will also highlight the major transcriptional regulatory axes that control fibroblast plasticity in the adult heart, including transforming growth factor β (TGFβ)/Smad signaling, the Rho/myocardin-related transcription factor (MRTF)/serum response factor (SRF) axis, and Calcineurin/transient receptor potential channel (TRP)/nuclear factor of activated T-Cell (NFAT) signaling. Finally, we will discuss recent strategies to divert the fibroblast transcriptional program in an effort to promote cardiomyocyte regeneration. This article is a part of a Special Issue entitled "Fibrosis and Myocardial Remodeling".

  18. Evolution of multicellular animals as deduced from 5S rRNA sequences: a possible early emergence of the Mesozoa.

    PubMed

    Ohama, T; Kumazaki, T; Hori, H; Osawa, S

    1984-06-25

    The nucleotide sequences of 5S rRNA from a mesozoan Dicyema misakiense and three metazoan species, i.e., an acorn-worm Saccoglossus kowalevskii, a moss-animal Bugula neritina, and an octopus Octopus vulgaris have been determined. A phylogenic tree of multicellular animals has been constructed from 73 5S rRNA sequences available at present including those from the above four sequences. The tree suggests that the mesozoan is the most ancient multicellular animal identified so far, its emergence time being almost the same as that of flagellated or ciliated protozoans. The branching points of planarians and nematodes are a little later than that of the mesozoan but are clearly earlier than other metazoan groups including sponges and jellyfishes. Many metazoan groups seem to have diverged within a relatively short period.

  19. Fibroblast migration in fibrin gel matrices.

    PubMed Central

    Brown, L. F.; Lanir, N.; McDonagh, J.; Tognazzi, K.; Dvorak, A. M.; Dvorak, H. F.

    1993-01-01

    In healing wounds and many solid tumors, locally increased microvascular permeability results in extravasation of fibrinogen and its extravascular coagulation to form a fibrin gel, with concomitant covalent cross-linking of fibrin by factor XIIIa. Subsequently, inflammatory cells, fibroblasts, and endothelial cells migrate into the gel and organize it into granulation tissue and later into mature collagenous connective tissue. To gain insight into some of the cell migration events associated with these processes, we developed a quantitative in vitro assay that permits the study of fibroblast migration in fibrin gels. Early passage human or rat fibroblasts were allowed to attach to tissue culture dishes and then were overlaid with a thin layer of fibrinogen that was clotted with thrombin. Fibroblasts began to migrate upwards into the fibrin within 24 hours and their numbers and the distance migrated were quantified over several days. The extent of fibroblast migration was affected importantly by the nature of the fibrin clot. Fibroblasts migrated optimally into gels prepared from fibrinogen at concentrations of -3 mg/ml; ie, near normal plasma fibrinogen levels. Migration was greatly enhanced by extensive cross-linking of the fibrin alpha-chains by factor XIIIa, as occurs when clotting takes place in vivo. When fibrinogen was clotted in Dulbecco's modified Eagle's medium, gamma-chains were cross-linked, but alpha-chain cross-linking was strikingly inhibited, and fibroblasts migrated poorly. Gels prepared from factor XIII-depleted fibrinogen exhibited neither alpha-nor gamma-chain cross-linking and did not support fibroblast migration. Further purification of fibrinogen by anion exchange high pressure liquid chromatography depleted fibrinogen of fibronectin, plasminogen, and other impurities; this purified fibrinogen clotted to form fibrin gels that supported reproducible fibroblast migration. Images Figure 1 Figure 2 Figure 4 Figure 6 PMID:8424460

  20. Multicellular structures developing during maize microspore culture express endosperm and embryo-specific genes and show different embryogenic potentialities.

    PubMed

    Massonneau, Agnes; Coronado, Maria-José; Audran, Arthur; Bagniewska, Agnieszka; Mòl, Rafal; Testillano, Pilar S; Goralski, Grzegorz; Dumas, Christian; Risueño, Maria-Carmen; Matthys-Rochon, Elisabeth

    2005-07-01

    During maize pollen embryogenesis, a range of multicellular structures are formed. Using different approaches, the "nature" of these structures has been determined in terms of their embryogenic potential. In situ molecular identification techniques for gene transcripts and products, and a novel cell tracking system indicated the presence of embryogenic (embryo-like structures, ELS) and non-embryogenic (callus-like structures, CLS) structures that occurred for short periods within the cultures. Some multicellular structures with a compact appearance generated embryos. RT-PCR and fluorescence in situ hybridization (FISH) with confocal microscopy techniques using specific gene markers of the endosperm (ZmESR2, ZmAE3) and embryo (LTP2 and ZmOCL1, ZmOCL3) revealed "embryo" and "endosperm" potentialities in these various multicellular structures present in the cultures. The results presented here showed distinct and specific patterns of gene expression. Altogether, the results demonstrate the presence of different molecules on both embryonic and non-embryonic structures. Their possible roles are discussed in the context of a parallel between embryo/endosperm interactions in planta and embryonic and non-embryonic structure interrelations under in vitro conditions.