Unidirectional movement of flares of cells of Myxococcus xanthus

Amongst other modes, Myxococcal cells move in swarms that are flares or columns of cells. It has been argued that this is a strategy allowing a large enough number of them to encounter food bacteria. Then, the combined large amount of extracellular lytic enzymes from the mass of cells can provide adequate nutrient resources from the food bacteria for all the myxococci of the swarm. However, how they move as a coherent column has not been adequately explained. Here based on the idea that a rare cell can experience a special mutation such that it moves only unidirectionally, a proposal to account for this aspect of Myxococcus cell movement is suggested. Although wild type individual organisms of this species engage in forward and back movements, a mutant cell that moves unidirectionally can bias the movement of associated wild type cells and lead to the formation of a column of cells, headed by such a unique mutated cell. The non-mutated cells follow along it is suggested because of the S-motility (or social motility) system. This may link them to this single unidirectionally moving mutant cell to give a coherent movement to the column. This proposed type of mutation back mutates to wild type and the column no longer functions as such and only wild-type cells are present.     

Systematic isolation of transducing phages for Myxococcus xanthus.

Six new phages active on Myxococcus xanthus have been isolated from cultures of myxobacteria. The six are all capable of transduction, and they fall into three groups. Members of one group have long contractile tails, have a characteristic neutralization antigen, and resemble the previously described M×4. Members of a second group, exemplified by M×8, have very short tails and a characteristic antigen. M×9, the sole member of the third group, has a very short tail and a characteristic antigen. Phage M×8, which is active on fruiting as well as nonfruiting strains of M. xanthus, can transduce auxotrophic, antibiotic resistance and motility markers in M. xanthus. Although crude lysates of M×8 contain 58-nm diameter particles with a tail and 29-nm particles without tail, only 58-nm particles can form plaques and transduce. The plaque-forming particles of M×8 possess a single DNA molecule of 56,000 base pairs with a buoyant density of 1.726 g/cm³, virtually identical to that of the DNA from its host.     

Development-specific sigma-factor essential for late-stage differentiation of Myxococcus xanthus

The gene for a developmentally expressed sigma-factor, sigB, has been isolated from Myxococcus xanthus by use of the sigA gene (formerly rpoD) of the vegetative sigma-factor as a probe. The sequence of sigB has been determined, and an open reading frame of 193 amino acid residues (Mr = 21,551) was identified. The amino-terminal region of SigB contains 69 residues, of which 35 are identical (50% identity) to the region of SigA required for core RNA polymerase binding and initiation of RNA polymerization. SigB also possesses many features commonly found in other prokaryotic sigma-factors. Analysis of an M. xanthus strain carrying a sigB-lacZ fusion gene revealed that sigB is expressed from a middle to late stage of differentiation corresponding to the period from the onset of sporulation to late development. A sigB deletion mutant displayed normal mound formation and sporulation; however, production of the ops gene product in myxospores of the delta sigB strain was shown to be blocked. Myxospores from the sigB deletion strain also exhibited severe defects in stability and viability during late development. Our data indicate that sigB encodes a sigma-factor essential for the maturation of myxospores at a late stage of M. xanthus differentiation. Our results also suggest that differentiation of M. xanthus is regulated by development-specific sigma-factors.     

Unidirectional block in a computer model of partially coupled segments of cardiac Purkinje tissue

The initiation of a reentrant circuit requires a zone of slow conduction and a zone of unidirectional block. This study used computer model conditions under which partial coupling between segments of cardiac Purkinje tissue resulted in unidirectional block. The structure used was one-dimensional and divided into three segments: a middle segment of variable length coupled to two long (semi-infinite in concept) segments. The DiFrancesco-Noble equations represented the ionic currents of the membrane. The results show that the possibility of unidirectional block depends on the size of the middle segment and the coupling resistances between the segments. No combination of coupling resistances allowed unidirectional block for middle segments with a length of two space constants (4 mm) or longer. Unidirectional block occurred for many combinations of coupling resistances as the length of the middle segment decreased to around half a space constant (1 mm). The number of length combinations that caused unidirectional block decreased again as segment length further decreased. These results provide a possible mechanism of unidirectional block for situations where islands of viable tissue are connected through nonviable tissue, such as in a healed myocardial infarction.     

Modification of immune response by coats of Myxococcus xanthus myxospores

Treatment with coats of M. xanthus myxospores produced a marked modificatory effect on humoral response, depending on the inoculation model. Also we observed that the percentage of adherent phagocytes and phagocytic index were enhanced after treatment. These results were similar to the effect obtained by M. xanthus myxospores. Data showed that the immune response modifier properties of M. xanthus myxospores are principally present in the coats.     

Site of ATPase activity in Myxococcus xanthus: Lipid requirement for enzyme activity

Treatment of cells with lysophosphatidylcholine, lysozyme, and phospholipase D removed most of their phospholipids and reduced ATPase activity to near zero. Addition of a microdispersion of phospholipids restored enzyme activity to various degrees. Phosphatidylcholine was most effective in reconstitution experiments, less effective were phosphatidylethanolamine and phosphatidylserine. Lipid analyses of cell fractions were possible through separation of cell wall and cell membrane in a sucrose gradient after differentiated treatment of glutaraldehyde fixed cells with lysophosphatidylcholine, lysozyme, and pronase. Phosphatidylcholine was almost exclusively a component of the cell membrane, whereas phosphatidylethanolamine was that of the wall. It is concluded that lipids are necessary for in vivo function of a Mg-dependent ATPase, and that membrane-associated phosphatidylcholine may serve as a matrix for the enzyme. Lipid extracts made from cells or cell fractions contained plasmologens, not previously reported to occur in Gram-negative, aerobic bacteria.     

Movement programming depends on understanding of behavioral requirements

Use of programmed movements seems to depend on comprehension of the required behavior of which the movements are part. Once this understanding becomes evident by correct behavior, smooth movement take-offs and landings are programmed together. Monkeys were trained to perform a step-tracking task that required accurate self-paced elbow movements of moderate speed. Behavioral aspects of the task, such as correct successive movement directions and timing, were all learned at about the same rates. Use of programmed movements however, increased only after these behavioral requirements had been learned to near the 50% level, i.e., the beginning of behavioral sureness. Movements were programmed as a whole, accelerations together with decelerations, from earliest training onwards.     

Myxococcus CsgA,Drosophila Sniffer,and human HSD10 are cardiolipin phospholipases

Myxococcus xanthus development requires CsgA, a member of the short-chain alcohol dehydrogenase (SCAD) family of proteins. We show that CsgA and SocA, a protein that can replace CsgA function in vivo, oxidize the 2′-OH glycerol moiety on cardiolipin and phosphatidylglycerol to produce diacylglycerol (DAG), dihydroxyacetone, and orthophosphate. A lipid extract enriched in DAGs from wild-type cells initiates development and lipid body production in a csgA mutant to bypass the mutational block. This novel phospholipase C-like reaction is widespread. SCADs that prevent neurodegenerative disorders, such as Drosophila Sniffer and human HSD10, oxidize cardiolipin with similar kinetic parameters. HSD10 exhibits a strong preference for cardiolipin with oxidized fatty acids. This activity is inhibited in the presence of the amyloid β peptide. Three HSD10 variants associated with neurodegenerative disorders are inactive with cardiolipin. We suggest that HSD10 protects humans from reactive oxygen species by removing damaged cardiolipin before it induces apoptosis.     

Becoming bonded through Developmental Movement Play: review of a parent and child movement group incorporating the theory,practice and philosophy of Sherborne Developmental Movement

This paper is a reflection on a Developmental Movement Play (DMP) programme based on Sherborne Developmental Movement (SDM) for parents and their young children experiencing emotional, behavioural and/or mental health difficulties. A focus on embodiment through movement experiences, dance and relationship play (Sherborne, 2001 Sherborne, V. (2001) Developmental movement for children: Mainstream, special needs and pre-school (2nd ed.). London: Worth Publishing  [Google Scholar]) is described within the programme. This is then discussed in relation to the bonding between parent–child, which takes place through shared movement experiences. Participants in the programme were referred through multi-disciplinary agencies with concerns for the parent–child relationship. The final group comprised 10 children (aged 18 months to eight years) and their mothers. The study uses a combination of quantitative and qualitative research methods to investigate the effectiveness of using DMP/SDM to facilitate changes in attitudes, feelings, moods and parenting styles. Results of the research are discussed and an examination of theory underpinning SDM explores Laban's principles of human movement (1998) and attachment theories (Ainsworth, Bell, Blehar, & Main, 1971; Bowlby, 1951 Bowlby, J. (1951). Maternal care and mental health. World Health Organization, 3, 355--534  [Google Scholar]) in order to identify the psychotherapeutic nature of the programme. The limitations of the study are recognised alongside recommendations for further work.     

Pupillary Dilations in Movement Preparation and Execution

Movement-related pupillary responses (MRPRs) were examined during self-triggered finger flexions to determine the time course and extent of response-related effects on this measure of general processing demands. MRPRs to self-triggered finger movements began about 1.5 s before the response and peaked 0.5 s post-response for simple movements. This dilation increased in amplitude and latency with the complexity of the movement as determined by the number of flexions executed. Peak pupillary amplitude was also sensitive to the force of the movement. The data establish the very large contribution of motoric processing demands to the pupillary response both before and after the onset of the movement.     

Movement adaptation in the visual evoked response

Summary Visual evoked responses to sinusoidal movement before and after adaptation to linear movement were compared. Fourier analysis indicated that the responses evoked by sinusoidal movement were insensitive to direction of movement. Following adaptation, the harmonics describing the waveforms changed in magnitude and phase, and showed an asymmetry of waveshape not evident before adaptation. The data are consistent with the existence of movement-sensitive cells within the intact visual system which change in response characteristics as a result of adaptation to linear movement.     

Movement interference during action observation as emergent coordination

Previous research has demonstrated that when an actor coordinates with spatially incompatible movements of another individual that motor interference occurs-the rhythmic arm movements of the actor exhibit increased movement variability in the plane orthogonal (non-instructed) to the instructed plane of motion. Here we examine whether this motor contagion reflects not error but the spontaneous recruitment of additional task-specific movement degrees of freedom employed to withstand increasing task difficulty. Participants coordinated congruent and incongruent forearm movements with a confederate moving at a fast, moderate, and slow target frequency. Examining the variability in the non-instructed plane revealed oscillatory non-instructed plane movements that were coordinated with the instructed plane movements of the confederate. The results suggest motor interference during incongruent coordination can be understood as an emergent, task-specific property of the coordination goal.     

Embodiment and the supervisory task: The supervision of Dance Movement Psychotherapists in training

Supervision is an intimate act of creation and this article endeavours to understand the mercurial nature of this task, drawing on theoretical perspectives grounded in a Jungian framework. With a focus on training, supervisor and supervisee negotiate a labyrinth as they co-create a process within a triangular relationship, in which one key player, the client, is absent. The role of embodied knowing shapes a process involving the body as an active agent of change, whilst the wider matrix of the institution offers a multi-layered universe of parallel processes. The article offers composite vignettes to illustrate how unarticulated embodied wisdom transforms into a conceptualised understanding of clinical material through the transcendent function. The article illuminates the value of the body as radar for unconscious communication within the supervisory relationship.     

Kinaesthetic change in the professional development of Dance Movement Therapy trainees

The present study investigates changes in kinaesthetic ability among Dance Movement Therapy (DMT) trainees, as compared to Art Therapy trainees. A field study was conducted using a quasi-experimental pre-post group design. Participants were 42 graduate students. Kinaesthetic ability was evaluated using a table of movement dimensions, based on Laban Movement Analysis (LMA). Tutor evaluation was also included. Results indicated an increase among the DMT group in all areas of kinaesthetic ability. No change was found among the Art Therapy students. The particular combination of therapeutic elements and movement experience in DMT training may be the basis for changes in kinaesthesia. The study resulted in the development of an easy-to-use movement assessment tool based on LMA.     

Authentic Movement: A dance with the divine

Authentic Movement facilitates a descent into the inner world of the psyche through natural movement. Through the process we are reconnected with deeper instinctual resources and spiritual intelligence that dwell in the molecular structure of the cells, and recover unlived parts of our nature on intrapersonal, interpersonal and transpersonal levels. The practice develops a sense of embodied presence, of being ‘at home’ in the body. During a time when many of the patriarchal power structures that have given meaning to our existence for thousands of years are crumbling, Authentic Movement allows practitioners, within the context of a healing relationship, to discover a new paradigm that offers guidance from an inner source. Physical, psychological, spiritual, social, affective and aesthetic dimensions are included in this holistic practice. Authentic Movement is used in individual and group settings, is effective within the context of psychotherapy, medicine and meditative practices, and is a potent source for artistic expression.