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Sample records for absent dynein arms

  1. Axonemal Dynein Arms.

    PubMed

    King, Stephen M

    2016-11-01

    Axonemal dyneins form the inner and outer rows of arms associated with the doublet microtubules of motile cilia. These enzymes convert the chemical energy released from adenosine triphosphate (ATP) hydrolysis into mechanical work by causing the doublets to slide with respect to each other. Dyneins form two major groups based on the number of heavy-chain motors within each complex. In addition, these enzymes contain other components that are required for assembly of the complete particles and/or for the regulation of motor function in response to phosphorylations status, ligands such as Ca(2+), changes in cellular redox state and which also apparently monitor and respond to the mechanical state or curvature in which any given motor finds itself. It is this latter property, which is thought to result in waves of motor function propagating along the axoneme length. Here, I briefly describe our current understanding of axonemal dynein structure, assembly, and organization.

  2. Substructure of the outer dynein arm

    PubMed Central

    1982-01-01

    The substructure of the outer dynein arm has been analyzed in quick- frozen deep-etch replicas of Tetrahymena and Chlamydomonas axonemes. Each arm is found to be composed of five morphologically discrete components: an elliptical head; two spherical feet; a slender stalk; and an interdynein linker. The feet make contact with the A microtubule of each doublet; the stalk contacts the B microtubule; the head lies between the feet and stalk; and the linker associates each arm with its neighbor. The spatial relationships between these five components are found to be distinctly different in rigor (ATP-depleted) versus relaxed (ATP- or vanadate plus ATP-treated) axonemes, and the stalk appears to alter its affinity for the B microtubule in the relaxed state. Images of living cilia attached to Tetrahymena cells show that the relaxed configuration is adopted in vivo. We relate our observations to morphological and experimental studies reported by others and propose several models that suggest how this newly described dynein morphology may relate to dynein function. PMID:6218174

  3. The ciliary inner dynein arm, I1 dynein, is assembled in the cytoplasm and transported by IFT before axonemal docking.

    PubMed

    Viswanadha, Rasagnya; Hunter, Emily L; Yamamoto, Ryosuke; Wirschell, Maureen; Alford, Lea M; Dutcher, Susan K; Sale, Winfield S

    2014-10-01

    To determine mechanisms of assembly of ciliary dyneins, we focused on the Chlamydomonas inner dynein arm, I1 dynein, also known as dynein f. I1 dynein assembles in the cytoplasm as a 20S complex similar to the 20S I1 dynein complex isolated from the axoneme. The intermediate chain subunit, IC140 (IDA7), and heavy chains (IDA1, IDA2) are required for 20S I1 dynein preassembly in the cytoplasm. Unlike I1 dynein derived from the axoneme, the cytoplasmic 20S I1 complex will not rebind I1-deficient axonemes in vitro. To test the hypothesis that I1 dynein is transported to the distal tip of the cilia for assembly in the axoneme, we performed cytoplasmic complementation in dikaryons formed between wild-type and I1 dynein mutant cells. Rescue of I1 dynein assembly in mutant cilia occurred first at the distal tip and then proceeded toward the proximal axoneme. Notably, in contrast to other combinations, I1 dynein assembly was significantly delayed in dikaryons formed between ida7 and ida3. Furthermore, rescue of I1 dynein assembly required new protein synthesis in the ida7 × ida3 dikaryons. On the basis of the additional observations, we postulate that IDA3 is required for 20S I1 dynein transport. Cytoplasmic complementation in dikaryons using the conditional kinesin-2 mutant, fla10-1 revealed that transport of I1 dynein is dependent on kinesin-2 activity. Thus, I1 dynein complex assembly depends upon IFT for transport to the ciliary distal tip prior to docking in the axoneme.

  4. Structural comparison of purified dynein proteins with in situ dynein arms.

    PubMed

    Goodenough, U; Heuser, J

    1984-12-25

    Using the quick-freeze deep-etch technique, we describe the structure of outerarm dynein proteins from Chlamydomonas and Tetrahymena after adsorption to a mica surface, after high-salt dissociation, and after glutaraldehyde fixation, and compare these images to the configuration of outer arms bound to microtubules. After adsorption to mica, the extracted dyneins from both organisms look like three-headed "bouquets", as reported for Tetrahymena by Johnson & Wall (1983b). High magnification images demonstrate that each head carries a slender "stalk" and a long "stem", and that small subunits decorate the stems and create a "flowerpot" domain at the base of the bouquet. Exposure to high salt induces this trimer to dissociate into a two-headed species and a single-headed species; it also stimulates the decorative elements to dissociate from the stems. Dynein is thus constructed on the same general plan as myosin, with large globular heads, narrow stems and additional small subunits that associate with the stems. The splayed-out image of the bouquet appears to be a distortion arising during adsorption to mica since, after brief glutaraldehyde fixation, the three heads remain closely associated as vertices of a triangular unit. In situ, the three heads also adopt this trigonal configuration. Two of the three are visible from the exterior of the axoneme and constitute the bilobed rigor head we described previously (Goodenough & Heuser, 1982). The third head faces the interior of the axoneme where, we propose, it forms the "hook" of the outer arm as seen in thin section. We further propose that the decorative elements associated with the stem coalesce to form the two outer-arm "feet" seen in situ, and that at least one of the in vitro stalks is equivalent to the in situ stalk, which extends from the head to the B microtubule. Deep-etch images of stretched axonemes, partially extracted axonemes, and dynein-decorated brain microtubules indicate that each outer arm, as

  5. Differential Light Chain Assembly Influences Outer Arm Dynein Motor Function

    PubMed Central

    DiBella, Linda M.; Gorbatyuk, Oksana; Sakato, Miho; Wakabayashi, Ken-ichi; Patel-King, Ramila S.; Pazour, Gregory J.; Witman, George B.; King, Stephen M.

    2005-01-01

    Tctex1 and Tctex2 were originally described as potential distorters/sterility factors in the non-Mendelian transmission of t-haplotypes in mice. These proteins have since been identified as subunits of cytoplasmic and/or axonemal dyneins. Within the Chlamydomonas flagellum, Tctex1 is a subunit of inner arm I1. We have now identified a second Tctex1-related protein (here termed LC9) in Chlamydomonas. LC9 copurifies with outer arm dynein in sucrose density gradients and is missing only in those strains completely lacking this motor. Zero-length cross-linking of purified outer arm dynein indicates that LC9 interacts directly with both the IC1 and IC2 intermediate chains. Immunoblot analysis revealed that LC2, LC6, and LC9 are missing in an IC2 mutant strain (oda6-r88) that can assemble outer arms but exhibits significantly reduced flagellar beat frequency. This defect is unlikely to be due to lack of LC6, because an LC6 null mutant (oda13) exhibits only a minor swimming abnormality. Using an LC2 null mutant (oda12-1), we find that although some outer arm dynein components assemble in the absence of LC2, they are nonfunctional. In contrast, dyneins from oda6-r88, which also lack LC2, retain some activity. Furthermore, we observed a synthetic assembly defect in an oda6-r88 oda12-1 double mutant. These data suggest that LC2, LC6, and LC9 have different roles in outer arm assembly and are required for wild-type motor function in the Chlamydomonas flagellum. PMID:16195342

  6. Torque generation by axonemal outer-arm dynein.

    PubMed

    Yamaguchi, Shin; Saito, Kei; Sutoh, Miki; Nishizaka, Takayuki; Toyoshima, Yoko Y; Yajima, Junichiro

    2015-02-17

    Outer-arm dynein is the main engine providing the motive force in cilia. Using three-dimensional tracking microscopy, we found that contrary to previous reports Tetrahymena ciliary three-headed outer-arm dynein (αβγ) as well as proteolytically generated two-headed (βγ) and one-headed (α) subparticles showed clockwise rotation of each sliding microtubule around its longitudinal axis in microtubule corkscrewing assays. By measuring the rotational pitch as a function of ATP concentration, we also found that the microtubule corkscrewing pitch is independent of ATP concentration, except at low ATP concentrations where the pitch generated by both three-headed αβγ and one-headed α exhibited significantly longer pitch. In contrast, the pitch driven by two-headed βγ did not display this sensitivity. In the assays on lawns containing mixtures of α and βγ at various ratios, the corkscrewing pitch increased dramatically in a nonlinear fashion as the ratio of α in the mixture increased. Even small proportions of α-subparticle could significantly increase the corkscrewing pitch of the mixture. Our data show that torque generation does not require the three-headed outer-arm dynein (αβγ) but is an intrinsic property of the subparticles of axonemal dyneins and also suggest that each subparticle may have distinct mechanical properties.

  7. Is outer arm dynein intermediate chain 1 multifunctional?

    PubMed Central

    Ogawa, K; Takai, H; Ogiwara, A; Yokota, E; Shimizu, T; Inaba, K; Mohri, H

    1996-01-01

    The outer arm dynein of sea urchin sperm axoneme contains three intermediate chains (IC1, IC2, and IC3; M(r) 128,000, 98,000, and 74,000, respectively). IC2 and IC3 are members of the WD family; the WD motif is responsible for a protein-protein interaction. We describe here the molecular cloning of IC1. IC1 has a unique primary structure, the N-terminal part is homologous to the sequence of thioredoxin, the middle part consists of three repetitive sequences homologous to the sequence of nucleoside diphosphate kinase, and the C-terminal part contains a high proportion of negatively charged glutamic acid residues. Thus, IC1 is a novel dynein intermediate chain distinct from IC2 and IC3 and may be a multifunctional protein. The thioredoxin-related part of IC1 is more closely related to those of two redox-active Chlamydomonas light chains than thioredoxin. Antibodies were prepared against the N-terminal and middle domains of IC1 expressed as His-tagged proteins in bacteria. These antibodies cross-reacted with some dynein polypeptides (potential homologues of IC1) from distantly related species. We propose here that the three intermediate chains are the basic core units of sperm outer arm dynein because of their ubiquitous existence. The recombinant thioredoxin-related part of IC1 and outer arm dyneins from sea urchin and distantly related species were specifically bound to and eluted from a phenylarsine oxide affinity column with 2-mercaptoethanol, indicating that they contain vicinal dithiols competent to undergo reversible oxidation/reduction. Images PMID:8970153

  8. Functional Architecture of the Outer Arm Dynein Conformational Switch*

    PubMed Central

    King, Stephen M.; Patel-King, Ramila S.

    2012-01-01

    Dynein light chain 1 (LC1/DNAL1) is one of the most highly conserved components of ciliary axonemal outer arm dyneins, and it associates with both a heavy chain motor unit and tubulin located within the A-tubule of the axonemal outer doublet microtubules. In a variety of model systems, lack of LC1 or expression of mutant forms leads to profound defects in ciliary motility, including the failure of the hydrodynamic coupling needed for ciliary metachronal synchrony, random stalling during the power/recovery stroke transition, an aberrant response to imposed viscous load, and in some cases partial failure of motor assembly. These phenotypes have led to the proposal that LC1 acts as part of a mechanical switch to control motor function in response to alterations in axonemal curvature. Here we have used NMR chemical shift mapping to define the regions perturbed by a series of mutations in the C-terminal domain that yield a range of phenotypic effects on motility. In addition, we have identified the subdomain of LC1 involved in binding microtubules and characterized the consequences of an Asn → Ser alteration within the terminal leucine-rich repeat that in humans causes primary ciliary dyskinesia. Together, these data define a series of functional subdomains within LC1 and allow us to propose a structural model for the organization of the dynein heavy chain-LC1-microtubule ternary complex that is required for the coordinated activity of dynein motors in cilia. PMID:22157010

  9. Phosphoregulation of an Inner Dynein Arm Complex in Chlamydomonas reinhardtii Is Altered in Phototactic Mutant Strains

    PubMed Central

    King, Stephen J.; Dutcher, Susan K.

    1997-01-01

    To gain a further understanding of axonemal dynein regulation, mutant strains of Chlamydomonas reinhardtii that had defects in both phototactic behavior and flagellar motility were identified and characterized. ptm1, ptm2, and ptm3 mutant strains exhibited motility phenotypes that resembled those of known inner dynein arm region mutant strains, but did not have biochemical or genetic phenotypes characteristic of other inner dynein arm mutations. Three other mutant strains had defects in the f class of inner dynein arms. Dynein extracts from the pf9-4 strain were missing the entire f complex. Strains with mutations in pf9/ida1, ida2, or ida3 failed to assemble the f dynein complex and did not exhibit phototactic behavior. Fractionated dynein from mia1-1 and mia2-1 axonemes exhibited a novel f class inner dynein arm biochemical phenotype; the 138-kD f intermediate chain was present in altered phosphorylation forms. In vitro axonemal dynein activity was reduced by the mia1-1 and mia2-1 mutations. The addition of kinase inhibitor restored axonemal dynein activity concomitant with the dephosphorylation of the 138-kD f intermediate chain. Dynein extracts from uni1-1 axonemes, which specifically assemble only one of the two flagella, contained relatively high levels of the altered phosphorylation forms of the 138-kD intermediate chain. We suggest that the f dynein complex may be phosphoregulated asymmetrically between the two flagella to achieve phototactic turning. PMID:9008712

  10. Identification of the t Complex–encoded Cytoplasmic Dynein Light Chain Tctex1 in Inner Arm I1 Supports the Involvement of Flagellar Dyneins in Meiotic Drive

    PubMed Central

    Harrison, Alistair; Olds-Clarke, Patricia; King, Stephen M.

    1998-01-01

    The cytoplasmic dynein light chain Tctex1 is a candidate for one of the distorter products involved in the non-Mendelian transmission of mouse t haplotypes. It has been unclear, however, how the t-specific mutations in this protein, which is found associated with cytoplasmic dynein in many tissues, could result in a male germ cell–specific phenotype. Here, we demonstrate that Tctex1 is not only a cytoplasmic dynein component, but is also present both in mouse sperm and Chlamydomonas flagella. Genetic and biochemical dissection of the Chlamydomonas flagellum reveal that Tctex1 is a previously undescribed component of inner dynein arm I1. Combined with the recent identification of another putative t complex distorter, Tctex2, within the outer dynein arm, these results support the hypothesis that transmission ratio distortion (meiotic drive) of mouse t haplotypes involves dysfunction of both flagellar inner and outer dynein arms but does not require the cytoplasmic isozyme. PMID:9490726

  11. Identification of the t complex-encoded cytoplasmic dynein light chain tctex1 in inner arm I1 supports the involvement of flagellar dyneins in meiotic drive.

    PubMed

    Harrison, A; Olds-Clarke, P; King, S M

    1998-03-09

    The cytoplasmic dynein light chain Tctex1 is a candidate for one of the distorter products involved in the non-Mendelian transmission of mouse t haplotypes. It has been unclear, however, how the t-specific mutations in this protein, which is found associated with cytoplasmic dynein in many tissues, could result in a male germ cell-specific phenotype. Here, we demonstrate that Tctex1 is not only a cytoplasmic dynein component, but is also present both in mouse sperm and Chlamydomonas flagella. Genetic and biochemical dissection of the Chlamydomonas flagellum reveal that Tctex1 is a previously undescribed component of inner dynein arm I1. Combined with the recent identification of another putative t complex distorter, Tctex2, within the outer dynein arm, these results support the hypothesis that transmission ratio distortion (meiotic drive) of mouse t haplotypes involves dysfunction of both flagellar inner and outer dynein arms but does not require the cytoplasmic isozyme.

  12. High speed sliding of axonemal microtubules produced by outer arm dynein.

    PubMed

    Seetharam, Raviraja N; Satir, Peter

    2005-02-01

    To study dynein arm activity at high temporal resolution, axonemal sliding was measured field by field for wild type and dynein arm mutants of Tetrahymena thermophila. For wt SB255 cells, when the rate of data acquisition was 60 fps, about 5x greater than previously published observations, sliding was observed to be discontinuous with very high velocity sliding (average 196 microm/sec) for a few msec (1 or 2 fields) followed by a pause of several fields. The sliding velocities measured were an order of magnitude greater than rates previously measured by video analysis. However, when the data were analyzed at 12 fps for the same axonemes, consistent with previous observations, sliding was linear as the axonemes extended several times their original length with an average velocity of approximately 10 microm/sec. The pauses or stops occurred at approximately 200 and 300% of the initial length, suggesting that dynein arms on one axonemal doublet were initially active to the limit of extension, and then the arms on the next doublet became activated. In contrast, in a mutant where OADs are missing, sliding observed at 60 fps was continuous and slow (5 microm/sec), as opposed to the discontinuous high-velocity sliding of SB255 and of the mutant at the permissive temperature where OADs are present. High-velocity step-wise sliding was also present in axonemes from an inner arm dynein mutant (KO6). These results indicate that the high-speed discontinuous pattern of sliding is produced by the mechanochemical activity of outer arm dynein. The rate of sliding is consistent with a low duty ratio of the outer arm dynein and with the operation of each arm along a doublet once per beat.

  13. Three Members of the LC8/DYNLL Family Are Required for Outer Arm Dynein Motor Function

    PubMed Central

    Tanner, Christopher A.; Rompolas, Panteleimon; Patel-King, Ramila S.; Gorbatyuk, Oksana; Wakabayashi, Ken-ichi; Pazour, Gregory J.

    2008-01-01

    The highly conserved LC8/DYNLL family proteins were originally identified in axonemal dyneins and subsequently found to function in multiple enzyme systems. Genomic analysis uncovered a third member (LC10) of this protein class in Chlamydomonas. The LC10 protein is extracted from flagellar axonemes with 0.6 M NaCl and cofractionates with the outer dynein arm in sucrose density gradients. Furthermore, LC10 is specifically missing only from axonemes of those strains that fail to assemble outer dynein arms. Previously, the oda12-1 insertional allele was shown to lack the Tctex2-related dynein light chain LC2. The LC10 gene is located ∼2 kb from that of LC2 and is also completely missing from this mutant but not from oda12-2, which lacks only the 3′ end of the LC2 gene. Although oda12-1 cells assemble outer arms that lack only LC2 and LC10, this strain exhibits a flagellar beat frequency that is consistently less than that observed for strains that fail to assemble the entire outer arm and docking complex (e.g., oda1). These results support a key regulatory role for the intermediate chain/light chain complex that is an integral and highly conserved feature of all oligomeric dynein motors. PMID:18579685

  14. An Outer Arm Dynein Conformational Switch Is Required for Metachronal Synchrony of Motile Cilia in Planaria

    PubMed Central

    Rompolas, Panteleimon; Patel-King, Ramila S.

    2010-01-01

    Motile cilia mediate the flow of mucus and other fluids across the surface of specialized epithelia in metazoans. Efficient clearance of peri-ciliary fluids depends on the precise coordination of ciliary beating to produce metachronal waves. The role of individual dynein motors and the mechanical feedback mechanisms required for this process are not well understood. Here we used the ciliated epithelium of the planarian Schmidtea mediterranea to dissect the role of outer arm dynein motors in the metachronal synchrony of motile cilia. We demonstrate that animals that completely lack outer dynein arms display a significant decline in beat frequency and an inability of cilia to coordinate their oscillations and form metachronal waves. Furthermore, lack of a key mechanosensitive regulatory component (LC1) yields a similar phenotype even though outer arms still assemble in the axoneme. The lack of metachrony was not due simply to a decrease in ciliary beat frequency, as reducing this parameter by altering medium viscosity did not affect ciliary coordination. In addition, we did not observe a significant temporal variability in the beat cycle of impaired cilia. We propose that this conformational switch provides a mechanical feedback system within outer arm dynein that is necessary to entrain metachronal synchrony. PMID:20844081

  15. CCDC103 mutations cause primary ciliary dyskinesia by disrupting assembly of ciliary dynein arms

    PubMed Central

    Panizzi, Jennifer R.; Becker-Heck, Anita; Castleman, Victoria H.; Al-Mutairi, Dalal; Liu, Yan; Loges, Niki T.; Pathak, Narendra; Austin-Tse, Christina; Sheridan, Eamonn; Schmidts, Miriam; Olbrich, Heike; Werner, Claudius; Häffner, Karsten; Hellman, Nathan; Chodhari, Rahul; Gupta, Amar; Kramer-Zucker, Albrecht; Olale, Felix; Burdine, Rebecca D.; Schier, Alexander F.; O’Callaghan, Christopher; Chung, Eddie MK; Reinhardt, Richard; Mitchison, Hannah M.; King, Stephen M.; Omran, Heymut; Drummond, Iain A.

    2012-01-01

    Cilia are essential for fertilization, respiratory clearance, cerebrospinal fluid circulation, and to establish laterality1. Cilia motility defects cause Primary Ciliary Dyskinesia (PCD, MIM 242650), a disorder affecting 1:15-30,000 births. Cilia motility requires the assembly of multisubunit dynein arms that drive cilia bending2. Despite progress in understanding the genetic basis of PCD, mutations remain to be identified for several PCD linked loci3. Here we show that the zebrafish cilia paralysis mutant schmalhanstn222 (smh) mutant encodes the coiled-coil domain containing 103 protein (Ccdc103), a foxj1a regulated gene. Screening 146 unrelated PCD families identified patients in six families with reduced outer dynein arms, carrying mutations in CCDC103. Dynein arm assembly in smh mutant zebrafish was rescued by wild-type but not mutant human CCDC103. Chlamydomonas Ccdc103 functions as a tightly bound, axoneme-associated protein. The results identify Ccdc103 as a novel dynein arm attachment factor that when mutated causes Primary Ciliary Dyskinesia. PMID:22581229

  16. An outer arm Dynein conformational switch is required for metachronal synchrony of motile cilia in planaria.

    PubMed

    Rompolas, Panteleimon; Patel-King, Ramila S; King, Stephen M

    2010-11-01

    Motile cilia mediate the flow of mucus and other fluids across the surface of specialized epithelia in metazoans. Efficient clearance of peri-ciliary fluids depends on the precise coordination of ciliary beating to produce metachronal waves. The role of individual dynein motors and the mechanical feedback mechanisms required for this process are not well understood. Here we used the ciliated epithelium of the planarian Schmidtea mediterranea to dissect the role of outer arm dynein motors in the metachronal synchrony of motile cilia. We demonstrate that animals that completely lack outer dynein arms display a significant decline in beat frequency and an inability of cilia to coordinate their oscillations and form metachronal waves. Furthermore, lack of a key mechanosensitive regulatory component (LC1) yields a similar phenotype even though outer arms still assemble in the axoneme. The lack of metachrony was not due simply to a decrease in ciliary beat frequency, as reducing this parameter by altering medium viscosity did not affect ciliary coordination. In addition, we did not observe a significant temporal variability in the beat cycle of impaired cilia. We propose that this conformational switch provides a mechanical feedback system within outer arm dynein that is necessary to entrain metachronal synchrony.

  17. The Chlamydomonas reinhardtii ODA3 Gene Encodes a Protein of the Outer Dynein Arm Docking Complex

    PubMed Central

    Koutoulis, Anthony; Pazour, Gregory J.; Wilkerson, Curtis G.; Inaba, Kazuo; Sheng, Hong; Takada, Saeko; Witman, George B.

    1997-01-01

    We have used an insertional mutagenesis/ gene tagging technique to generate new Chlamydomonas reinhardtii mutants that are defective in assembly of the outer dynein arm. Among 39 insertional oda mutants characterized, two are alleles of the previously uncloned ODA3 gene, one is an allele of the uncloned ODA10 gene, and one represents a novel ODA gene (termed ODA12). ODA3 is of particular interest because it is essential for assembly of both the outer dynein arm and the outer dynein arm docking complex (ODA-DC) onto flagellar doublet microtubules (Takada, S., and R. Kamiya. 1994. J. Cell Biol. 126:737– 745). Beginning with the inserted DNA as a tag, the ODA3 gene and a full-length cDNA were cloned. The cloned gene rescues the phenotype of oda3 mutants. The cDNA sequence predicts a novel 83.4-kD protein with extensive coiled-coil domains. The ODA-DC contains three polypeptides; direct amino acid sequencing indicates that the largest of these polypeptides corresponds to ODA3. This protein is likely to have an important role in the precise positioning of the outer dynein arms on the flagellar axoneme. PMID:9166407

  18. Components of a "dynein regulatory complex" are located at the junction between the radial spokes and the dynein arms in Chlamydomonas flagella

    PubMed Central

    1994-01-01

    Previous studies of flagellar mutants have identified six axonemal polypeptides as components of a "dynein regulatory complex" (DRC). The DRC is though to coordinate the activity of the multiple flagellar dyneins, but its location within the axoneme has been unknown (Huang et al., 1982; Piperno et al., 1992). We have used improved chromatographic procedures (Kagami and Kamiya, 1992) and computer averaging of EM images (Mastronarde et al., 1992) to analyze the relationship between the DRC and the dynein arms. Our results suggest that some of the DRC components are located at the base of the second radial spoke in close association with the inner dynein arms. (a) Averages of axoneme cross- sections indicate that inner arm structures are significantly reduced in three DRC mutants (pf3 < pf2 < sup-pf-3 < wt). (b) These defects are more pronounced in distal/medial regions of the axoneme than in proximal regions. (c) Analysis of flagellar extracts by fast protein liquid chromatography and SDS-PAGE indicates that a specific dynein I2 isoform is missing in pf3 and reduced in pf2 and sup-pf-3. Comparison with ida4 and pf3ida4 extracts reveals that this isoform differs from those missing in ida4. (d) When viewed in longitudinal section, all three DRC mutants lack a crescent-shaped density above the second radial spoke, and pf3 axonemes lack additional structures adjacent to the crescent. We propose that the crescent corresponds in part to the location of the DRC, and that this structure is also directly associated with a subset of the inner dynein arms. This position is appropriate for a complex that is thought to mediate signals between the radial spokes and the dynein arms. PMID:7962092

  19. Silencing of a putative inner arm dynein heavy chain results in flagellar immotility in Trypanosoma brucei

    PubMed Central

    Springer, Amy L.; Bruhn, David F.; Kinzel, Kathryn W.; Rosenthal, Noël F.; Zukas, Randi; Klingbeil, Michele M.

    2010-01-01

    The Trypanosoma brucei flagellum controls motility and is crucial for cell polarity and division. Unique features of trypanosome motility suggest that flagellar beat regulation in this organism is unusual and worthy of study. The flagellar axoneme, required for motility, has a structure that is highly conserved among eukaryotes. Of the several dyneins in the axonemal inner arm complex, dynein f is thought to control flagellar waveform shape. A T. brucei gene predicted to encode the dynein f alpha heavy chain, TbDNAH10, was silenced using RNA interference in procyclic T. brucei cells. This resulted in immotile flagella, showing no movement except for occasional slight twitches at the tips. Cell growth slowed dramatically and cells were found in large clusters. Microscopic analysis of silenced cultures showed many cells with detached flagella, sometimes entangled between multiple cells. DAPI staining showed an increased frequency of mis-positioned kinetoplasts and multinucleate cells, suggesting that these cells experience disruption at an early cell cycle stage, probably secondary to the motility defect. TEM images showed apparently normal axonemes and no discernable defects in inner arm structure. This study demonstrates use of RNAi as an effective method to study very large genes such as dynein heavy chains (HCs), and the immotility phenotype of these dynein knockdowns suggests that an intact inner arm is necessary for flagellar beating in T. brucei. Since analogous mutants in Chlamydomonas reinhardtii retain motility, this phenotype likely reflects differences in requirements for motility and/or dynein assembly between the two organisms and these comparative studies will help elucidate the mechanisms of flagellar beat regulation. PMID:20888370

  20. Deletions and Point Mutations of LRRC50 Cause Primary Ciliary Dyskinesia Due to Dynein Arm Defects

    PubMed Central

    Loges, Niki Tomas; Olbrich, Heike; Becker-Heck, Anita; Häffner, Karsten; Heer, Angelina; Reinhard, Christina; Schmidts, Miriam; Kispert, Andreas; Zariwala, Maimoona A.; Leigh, Margaret W.; Knowles, Michael R.; Zentgraf, Hanswalter; Seithe, Horst; Nürnberg, Gudrun; Nürnberg, Peter; Reinhardt, Richard; Omran, Heymut

    2009-01-01

    Genetic defects affecting motility of cilia and flagella cause chronic destructive airway disease, randomization of left-right body asymmetry, and, frequently, male infertility in primary ciliary dyskinesia (PCD). The most frequent defects involve outer and inner dynein arms (ODAs and IDAs) that are large multiprotein complexes responsible for cilia-beat generation and regulation, respectively. Here, we demonstrate that large genomic deletions, as well as point mutations involving LRRC50, are responsible for a distinct PCD variant that is characterized by a combined defect involving assembly of the ODAs and IDAs. Functional analyses showed that LRRC50 deficiency disrupts assembly of distally and proximally DNAH5- and DNAI2-containing ODA complexes, as well as DNALI1-containing IDA complexes, resulting in immotile cilia. On the basis of these findings, we assume that LRRC50 plays a role in assembly of distinct dynein-arm complexes. PMID:19944400

  1. An outer arm dynein light chain acts in a conformational switch for flagellar motility

    PubMed Central

    Patel-King, Ramila S.

    2009-01-01

    A system distinct from the central pair–radial spoke complex was proposed to control outer arm dynein function in response to alterations in the mechanical state of the flagellum. In this study, we examine the role of a Chlamydomonas reinhardtii outer arm dynein light chain that associates with the motor domain of the γ heavy chain (HC). We demonstrate that expression of mutant forms of LC1 yield dominant-negative effects on swimming velocity, as the flagella continually beat out of phase and stall near or at the power/recovery stroke switchpoint. Furthermore, we observed that LC1 interacts directly with tubulin in a nucleotide-independent manner and tethers this motor unit to the A-tubule of the outer doublet microtubules within the axoneme. Therefore, this dynein HC is attached to the same microtubule by two sites: via both the N-terminal region and the motor domain. We propose that this γ HC–LC1–microtubule ternary complex functions as a conformational switch to control outer arm activity. PMID:19620633

  2. Chlamydomonas Outer Arm Dynein Alters Conformation in Response to Ca2+

    PubMed Central

    Sakato, Miho; Sakakibara, Hitoshi

    2007-01-01

    We have previously shown that Ca2+ directly activates ATP-sensitive microtubule binding by a Chlamydomonas outer arm dynein subparticle containing the β and γ heavy chains (HCs). The γ HC–associated LC4 light chain is a member of the calmodulin family and binds 1-2 Ca2+ with KCa = 3 × 10−5 M in vitro, suggesting it may act as a Ca2+ sensor for outer arm dynein. Here we investigate interactions between the LC4 light chain and γ HC. Two IQ consensus motifs for binding calmodulin-like proteins are located within the stem domain of the γ heavy chain. In vitro experiments indicate that LC4 undergoes a Ca2+-dependent interaction with the IQ motif domain while remaining tethered to the HC. LC4 also moves into close proximity of the intermediate chain IC1 in the presence of Ca2+. The sedimentation profile of the γ HC subunit changed subtly upon Ca2+ addition, suggesting that the entire complex had become more compact, and electron microscopy of the isolated γ subunit revealed a distinct alteration in conformation of the N-terminal stem in response to Ca2+ addition. We propose that Ca2+-dependent conformational change of LC4 has a direct effect on the stem domain of the γ HC, which eventually leads to alterations in mechanochemical interactions between microtubules and the motor domain(s) of the outer dynein arm. PMID:17634291

  3. ida4-1, ida4-2, and ida4-3 are intron splicing mutations affecting the locus encoding p28, a light chain of Chlamydomonas axonemal inner dynein arms.

    PubMed Central

    LeDizet, M; Piperno, G

    1995-01-01

    We recently determined the nucleotide sequence of the gene encoding p28, a light chain of inner dynein arms of Chlamydomonas axonemes. Here, we show that p28 is the protein encoded by the IDA4 locus. p28, and the dynein heavy chains normally associated with it, are completely absent from the flagella and cell bodies of three allelic strains of ida4, named ida4-1, ida4-2, and ida4-3. We determined the nucleotide sequence of the three alleles of the p28 gene and found in each case a single nucleotide change, affecting the splice sites of the first, second, and fourth introns, respectively. Reverse transcriptase-polymerase chain reaction amplification of RNAs prepared from ida4 cells confirmed that these mutations prevent the correct splicing of the affected introns, thereby blocking the synthesis of full-length p28. These are the first intron splicing mutations described in Chlamydomonas and the first inner dynein arm mutations characterized at the molecular level. The absence in ida4 axonemes of the dynein heavy chains normally found in association with p28 suggests that p28 is necessary for stable assembly of a subset of inner dynein arms or for the binding of these arms to the microtubule doublets. Images PMID:7579690

  4. Functional analysis of an individual IFT protein: IFT46 is required for transport of outer dynein arms into flagella.

    PubMed

    Hou, Yuqing; Qin, Hongmin; Follit, John A; Pazour, Gregory J; Rosenbaum, Joel L; Witman, George B

    2007-02-26

    Intraflagellar transport (IFT), which is the bidirectional movement of particles within flagella, is required for flagellar assembly. IFT particles are composed of approximately 16 proteins, which are organized into complexes A and B. We have cloned Chlamydomonas reinhardtii and mouse IFT46, and show that IFT46 is a highly conserved complex B protein in both organisms. A C. reinhardtii insertional mutant null for IFT46 has short, paralyzed flagella lacking dynein arms and with central pair defects. The mutant has greatly reduced levels of most complex B proteins, indicating that IFT46 is necessary for complex B stability. A partial suppressor mutation restores flagellar length to the ift46 mutant. IFT46 is still absent, but levels of the other IFT particle proteins are largely restored, indicating that complex B is stabilized in the suppressed strain. Axonemal ultrastructure is restored, except that the outer arms are still missing, although outer arm subunits are present in the cytoplasm. Thus, IFT46 is specifically required for transporting outer arms into the flagellum.

  5. Insights into the Structural Organization of the I1 Inner Arm Dynein from a Domain Analysis of the 1β Dynein Heavy Chain

    PubMed Central

    Perrone, Catherine A.; Myster, Steven H.; Bower, Raqual; O'Toole, Eileen T.; Porter, Mary E.

    2000-01-01

    To identify domains in the dynein heavy chain (Dhc) required for the assembly of an inner arm dynein, we characterized a new motility mutant (ida2-6) obtained by insertional mutagenesis. ida2-6 axonemes lack the polypeptides associated with the I1 inner arm complex. Recovery of genomic DNA flanking the mutation indicates that the defects are caused by plasmid insertion into the Dhc10 transcription unit, which encodes the 1β Dhc of the I1 complex. Transformation with Dhc10 constructs encoding <20% of the Dhc can partially rescue the motility defects by reassembly of an I1 complex containing an N-terminal 1β Dhc fragment and a full-length 1α Dhc. Electron microscopic analysis reveals the location of the missing 1β Dhc motor domain within the axoneme structure. These observations, together with recent studies on the 1α Dhc, identify a Dhc domain required for complex assembly and further demonstrate that the intermediate and light chains are associated with the stem regions of the Dhcs in a distinct structural location. The positioning of these subunits within the I1 structure has significant implications for the pathways that target the assembly of the I1 complex into the axoneme and modify the activity of the I1 dynein during flagellar motility. PMID:10888669

  6. DNAH11 Localization in the Proximal Region of Respiratory Cilia Defines Distinct Outer Dynein Arm Complexes

    PubMed Central

    Dougherty, Gerard W.; Loges, Niki T.; Klinkenbusch, Judith A.; Olbrich, Heike; Pennekamp, Petra; Menchen, Tabea; Raidt, Johanna; Wallmeier, Julia; Werner, Claudius; Westermann, Cordula; Ruckert, Christian; Mirra, Virginia; Hjeij, Rim; Memari, Yasin; Durbin, Richard; Kolb-Kokocinski, Anja; Praveen, Kavita; Kashef, Mohammad A.; Kashef, Sara; Eghtedari, Fardin; Häffner, Karsten; Valmari, Pekka; Baktai, György; Aviram, Micha; Bentur, Lea; Amirav, Israel; Davis, Erica E.; Katsanis, Nicholas; Brueckner, Martina; Shaposhnykov, Artem; Pigino, Gaia; Dworniczak, Bernd

    2016-01-01

    Primary ciliary dyskinesia (PCD) is a recessively inherited disease that leads to chronic respiratory disorders owing to impaired mucociliary clearance. Conventional transmission electron microscopy (TEM) is a diagnostic standard to identify ultrastructural defects in respiratory cilia but is not useful in approximately 30% of PCD cases, which have normal ciliary ultrastructure. DNAH11 mutations are a common cause of PCD with normal ciliary ultrastructure and hyperkinetic ciliary beating, but its pathophysiology remains poorly understood. We therefore characterized DNAH11 in human respiratory cilia by immunofluorescence microscopy (IFM) in the context of PCD. We used whole-exome and targeted next-generation sequence analysis as well as Sanger sequencing to identify and confirm eight novel loss-of-function DNAH11 mutations. We designed and validated a monoclonal antibody specific to DNAH11 and performed high-resolution IFM of both control and PCD-affected human respiratory cells, as well as samples from green fluorescent protein (GFP)–left–right dynein mice, to determine the ciliary localization of DNAH11. IFM analysis demonstrated native DNAH11 localization in only the proximal region of wild-type human respiratory cilia and loss of DNAH11 in individuals with PCD with certain loss-of-function DNAH11 mutations. GFP–left–right dynein mice confirmed proximal DNAH11 localization in tracheal cilia. DNAH11 retained proximal localization in respiratory cilia of individuals with PCD with distinct ultrastructural defects, such as the absence of outer dynein arms (ODAs). TEM tomography detected a partial reduction of ODAs in DNAH11-deficient cilia. DNAH11 mutations result in a subtle ODA defect in only the proximal region of respiratory cilia, which is detectable by IFM and TEM tomography. PMID:26909801

  7. DNAH11 Localization in the Proximal Region of Respiratory Cilia Defines Distinct Outer Dynein Arm Complexes.

    PubMed

    Dougherty, Gerard W; Loges, Niki T; Klinkenbusch, Judith A; Olbrich, Heike; Pennekamp, Petra; Menchen, Tabea; Raidt, Johanna; Wallmeier, Julia; Werner, Claudius; Westermann, Cordula; Ruckert, Christian; Mirra, Virginia; Hjeij, Rim; Memari, Yasin; Durbin, Richard; Kolb-Kokocinski, Anja; Praveen, Kavita; Kashef, Mohammad A; Kashef, Sara; Eghtedari, Fardin; Häffner, Karsten; Valmari, Pekka; Baktai, György; Aviram, Micha; Bentur, Lea; Amirav, Israel; Davis, Erica E; Katsanis, Nicholas; Brueckner, Martina; Shaposhnykov, Artem; Pigino, Gaia; Dworniczak, Bernd; Omran, Heymut

    2016-08-01

    Primary ciliary dyskinesia (PCD) is a recessively inherited disease that leads to chronic respiratory disorders owing to impaired mucociliary clearance. Conventional transmission electron microscopy (TEM) is a diagnostic standard to identify ultrastructural defects in respiratory cilia but is not useful in approximately 30% of PCD cases, which have normal ciliary ultrastructure. DNAH11 mutations are a common cause of PCD with normal ciliary ultrastructure and hyperkinetic ciliary beating, but its pathophysiology remains poorly understood. We therefore characterized DNAH11 in human respiratory cilia by immunofluorescence microscopy (IFM) in the context of PCD. We used whole-exome and targeted next-generation sequence analysis as well as Sanger sequencing to identify and confirm eight novel loss-of-function DNAH11 mutations. We designed and validated a monoclonal antibody specific to DNAH11 and performed high-resolution IFM of both control and PCD-affected human respiratory cells, as well as samples from green fluorescent protein (GFP)-left-right dynein mice, to determine the ciliary localization of DNAH11. IFM analysis demonstrated native DNAH11 localization in only the proximal region of wild-type human respiratory cilia and loss of DNAH11 in individuals with PCD with certain loss-of-function DNAH11 mutations. GFP-left-right dynein mice confirmed proximal DNAH11 localization in tracheal cilia. DNAH11 retained proximal localization in respiratory cilia of individuals with PCD with distinct ultrastructural defects, such as the absence of outer dynein arms (ODAs). TEM tomography detected a partial reduction of ODAs in DNAH11-deficient cilia. DNAH11 mutations result in a subtle ODA defect in only the proximal region of respiratory cilia, which is detectable by IFM and TEM tomography.

  8. Sensing the Mechanical State of the Axoneme and Integration of Ca2+ Signaling by Outer Arm Dynein

    PubMed Central

    King, Stephen M.

    2010-01-01

    Axonemal dyneins have been demonstrated to monitor the mechanical state of the axoneme and must also alter activity in response to various signaling pathways. The central pair/radial spoke systems are clearly involved in controlling inner dynein arm function; however, the mechanisms by which the outer dynein arm transduces regulatory signals appear quite distinct at the molecular level. In Chlamydomonas, these regulatory components include thioredoxins involved in response to redox changes, molecules that tether the γ heavy chain motor unit to the A-tubule of the outer doublet and a Ca2+-binding protein that controls the structure of the γ heavy chain N-terminal domain. Together, these studies now suggest that the γ heavy chain acts as a key regulatory node for controlling outer arm function in response to alterations in curvature and ligand binding. Furthermore, they allow us to propose a testable molecular mechanism by which altered Ca2+ levels might lead to a change in ciliary waveform by controlling whether one heavy chain of outer arm dynein acts as a microtubule translocase or as an ATP-dependent brake that limits the amount of inter-doublet sliding. PMID:20186692

  9. Partially Functional Outer-Arm Dynein in a Novel Chlamydomonas Mutant Expressing a Truncated γ Heavy Chain▿

    PubMed Central

    Liu, Zhongmei; Takazaki, Hiroko; Nakazawa, Yuki; Sakato, Miho; Yagi, Toshiki; Yasunaga, Takuo; King, Stephen M.; Kamiya, Ritsu

    2008-01-01

    The outer dynein arm of Chlamydomonas flagella contains three heavy chains (α, β, and γ), each of which exhibits motor activity. How they assemble and cooperate is of considerable interest. Here we report the isolation of a novel mutant, oda2-t, whose γ heavy chain is truncated at about 30% of the sequence. While the previously isolated γ chain mutant oda2 lacks the entire outer arm, oda2-t retains outer arms that contain α and β heavy chains, suggesting that the N-terminal sequence (corresponding to the tail region) is necessary and sufficient for stable outer-arm assembly. Thin-section electron microscopy and image analysis localize the γ heavy chain to a basal region of the outer-arm image in the axonemal cross section. The motility of oda2-t is lower than that of the wild type and oda11 (lacking the α heavy chain) but higher than that of oda2 and oda4-s7 (lacking the motor domain of the β heavy chain). Thus, the outer-arm dynein lacking the γ heavy-chain motor domain is partially functional. The availability of mutants lacking individual heavy chains should greatly facilitate studies on the structure and function of the outer-arm dynein. PMID:18487347

  10. Structure and function of outer dynein arm intermediate and light chain complex

    PubMed Central

    Oda, Toshiyuki; Abe, Tatsuki; Yanagisawa, Haruaki; Kikkawa, Masahide

    2016-01-01

    The outer dynein arm (ODA) is a molecular complex that drives the beating motion of cilia/flagella. Chlamydomonas ODA is composed of three heavy chains (HCs), two ICs, and 11 light chains (LCs). Although the three-dimensional (3D) structure of the whole ODA complex has been investigated, the 3D configurations of the ICs and LCs are largely unknown. Here we identified the 3D positions of the two ICs and three LCs using cryo–electron tomography and structural labeling. We found that these ICs and LCs were all localized at the root of the outer-inner dynein (OID) linker, designated the ODA-Beak complex. Of interest, the coiled-coil domain of IC2 extended from the ODA-Beak to the outer surface of ODA. Furthermore, we investigated the molecular mechanisms of how the OID linker transmits signals to the ODA-Beak, by manipulating the interaction within the OID linker using a chemically induced dimerization system. We showed that the cross-linking of the OID linker strongly suppresses flagellar motility in vivo. These results suggest that the ICs and LCs of the ODA form the ODA-Beak, which may be involved in mechanosignaling from the OID linker to the HCs. PMID:26864626

  11. Association of Lis1 with outer arm dynein is modulated in response to alterations in flagellar motility

    PubMed Central

    Rompolas, Panteleimon; Patel-King, Ramila S.; King, Stephen M.

    2012-01-01

    The cytoplasmic dynein regulatory factor Lis1, which induces a persistent tight binding to microtubules and allows for transport of cargoes under high-load conditions, is also present in motile cilia/flagella. We observed that Lis1 levels in flagella of Chlamydomonas strains that exhibit defective motility due to mutation of various axonemal substructures were greatly enhanced compared with wild type; this increase was absolutely dependent on the presence within the flagellum of the outer arm dynein α heavy chain/light chain 5 thioredoxin unit. To assess whether cells might interpret defective motility as a “high-load environment,” we reduced the flagellar beat frequency of wild-type cells through enhanced viscous load and by reductive stress; both treatments resulted in increased levels of flagellar Lis1, which altered the intrinsic beat frequency of the trans flagellum. Differential extraction of Lis1 from wild-type and mutant axonemes suggests that the affinity of outer arm dynein for Lis1 is directly modulated. In cytoplasm, Lis1 localized to two punctate structures, one of which was located near the base of the flagella. These data reveal that the cell actively monitors motility and dynamically modulates flagellar levels of the dynein regulatory factor Lis1 in response to imposed alterations in beat parameters. PMID:22855525

  12. Protein-Protein Interactions between Intermediate Chains and the Docking Complex of Chlamydomonas Flagellar Outer Arm Dynein

    PubMed Central

    Ide, Takahiro; Owa, Mikito; King, Stephen M.; Kamiya, Ritsu; Wakabayashi, Ken-ichi

    2013-01-01

    Outer arm dynein (OAD) is bound to specific loci on outer-doublet-microtubules by interactions at two sites: via intermediate chain 1 (IC1) and the outer dynein arm docking complex (ODA-DC). Studies using Chlamydomonas mutants have suggested that the individual sites have rather weak affinities for microtubules, and therefore strong OAD attachment to microtubules is achieved by their cooperation. To test this idea, we examined interactions between IC1, IC2 (another intermediate chain) and ODA-DC using recombinant proteins. Recombinant IC1 and IC2 were found to form a 1:1 complex, and this complex associated with ODA-DC in vitro. Binding of IC1 to mutant axonemes revealed that there are specific binding sites for IC1. From these data, we propose a novel model of OAD-outer doublet association. PMID:23747306

  13. Docking-complex-independent alignment of Chlamydomonas outer dynein arms with 24-nm periodicity in vitro.

    PubMed

    Oda, Toshiyuki; Abe, Tatsuki; Yanagisawa, Haruaki; Kikkawa, Masahide

    2016-04-15

    The docking complex is a molecular complex necessary for assembly of outer dynein arms (ODAs) on the axonemal doublet microtubules (DMTs) in cilia and flagella. The docking complex is hypothesized to be a 24-nm molecular ruler because ODAs align along the DMTs with 24-nm periodicity. In this study, we rigorously tested this hypothesis using structural and genetic methods. We found that the ODAs can bind to DMTs and porcine microtubules with 24-nm periodicities even in the absence of the docking complexin vitro Using cryo-electron tomography and structural labeling, we observed that the docking complex took an unexpectedly flexible conformation and did not lie along the length of DMTs. In the absence of docking complex, ODAs were released from the DMT at relatively low ionic strength conditions, suggesting that the docking complex strengthens the electrostatic interactions between the ODA and DMT. Based on these results, we conclude that the docking complex serves as a flexible stabilizer of the ODA rather than as a molecular ruler.

  14. The Oligomeric Outer Dynein Arm Assembly Factor CCDC103 Is Tightly Integrated within the Ciliary Axoneme and Exhibits Periodic Binding to Microtubules*

    PubMed Central

    King, Stephen M.; Patel-King, Ramila S.

    2015-01-01

    CCDC103 is an ∼29-kDa protein consisting of a central RPAP3_C domain flanked by N- and C-terminal coiled coils. Defects in CCDC103 lead to primary ciliary dyskinesia caused by the loss of outer dynein arms. This protein is present along the entire length of the ciliary axoneme and does not require other dynein or docking complex components for its integration. Unlike other known dynein assembly factors within the axoneme, CCDC103 is not solubilized by 0.6 m NaCl and requires more chaotropic conditions, such as 0.5 m KI. Alternatively, it can be extracted using 0.3% sarkosyl. CCDC103 forms stable dimers and other oligomers in solution through interactions involving the central domain. The smallest particle observed by dynamic light scattering has a hydrodynamic diameter of ∼25 nm. Furthermore, CCDC103 binds microtubules directly, forming ∼9-nm diameter particles that exhibit a 12-nm spacing on the microtubule lattice, suggesting that there may be two CCDC103 units per outer arm dynein repeat. Although the outer dynein arm docking complex is necessary to form arrays of dyneins along microtubules, it is not sufficient to set up a single array in a precise location on each axonemal doublet. We propose that CCDC103 helps generate a high-affinity site on the doublets for outer arm assembly, either through direct interactions or indirectly, perhaps by modifying the underlying microtubule lattice. PMID:25572396

  15. Cooperative binding of the outer arm-docking complex underlies the regular arrangement of outer arm dynein in the axoneme

    PubMed Central

    Owa, Mikito; Furuta, Akane; Usukura, Jiro; Arisaka, Fumio; King, Stephen M.; Witman, George B.; Kamiya, Ritsu; Wakabayashi, Ken-ichi

    2014-01-01

    Outer arm dynein (OAD) in cilia and flagella is bound to the outer doublet microtubules every 24 nm. Periodic binding of OADs at specific sites is important for efficient cilia/flagella beating; however, the molecular mechanism that specifies OAD arrangement remains elusive. Studies using the green alga Chlamydomonas reinhardtii have shown that the OAD-docking complex (ODA-DC), a heterotrimeric complex present at the OAD base, functions as the OAD docking site on the doublet. We find that the ODA–DC has an ellipsoidal shape ∼24 nm in length. In mutant axonemes that lack OAD but retain the ODA-DC, ODA-DC molecules are aligned in an end-to-end manner along the outer doublets. When flagella of a mutant lacking ODA-DCs are supplied with ODA-DCs upon gamete fusion, ODA-DC molecules first bind to the mutant axonemes in the proximal region, and the occupied region gradually extends toward the tip, followed by binding of OADs. This and other results indicate that a cooperative association of the ODA-DC underlies its function as the OAD-docking site and is the determinant of the 24-nm periodicity. PMID:24979786

  16. A Chlamydomonas Homologue of the Putative Murine t Complex Distorter Tctex-2 Is an Outer Arm Dynein Light Chain

    PubMed Central

    Patel-King, Ramila S.; Benashski, Sharon E.; Harrison, Alistair; King, Stephen M.

    1997-01-01

    Molecular analysis of a 19,000-Mr protein from the Chlamydomonas flagellum reveals that it is homologous to the t complex–encoded protein Tctex-2, which is a candidate for one of the distorter products that cause the extreme transmission ratio distortion (meiotic drive) of the murine t complex. The 19,000-Mr protein is extracted from the axoneme with 0.6 M NaCl and comigrates with the outer dynein arm in sucrose density gradients. This protein also is specifically missing in axonemes prepared from a mutant that does not assemble the outer arm. These data raise the possibility that Tctex-2 is a sperm flagellar dynein component. Combined with the recent identification of Tctex-1 (another distorter candidate) as a light chain of cytoplasmic dynein, these results lead to a biochemical model for how differential defects in spermiogenesis that result in the phenomenon of meiotic drive might be generated in wild-type vs t-bearing sperm. PMID:9166408

  17. Distinct roles of 1α and 1β heavy chains of the inner arm dynein I1 of Chlamydomonas flagella

    PubMed Central

    Toba, Shiori; Fox, Laura A.; Sakakibara, Hitoshi; Porter, Mary E.; Oiwa, Kazuhiro; Sale, Winfield S.

    2011-01-01

    The Chlamydomonas I1 dynein is a two-headed inner dynein arm important for the regulation of flagellar bending. Here we took advantage of mutant strains lacking either the 1α or 1β motor domain to distinguish the functional role of each motor domain. Single- particle electronic microscopic analysis confirmed that both the I1α and I1β complexes are single headed with similar ringlike, motor domain structures. Despite similarity in structure, however, the I1β complex has severalfold higher ATPase activity and microtubule gliding motility compared to the I1α complex. Moreover, in vivo measurement of microtubule sliding in axonemes revealed that the loss of the 1β motor results in a more severe impairment in motility and failure in regulation of microtubule sliding by the I1 dynein phosphoregulatory mechanism. The data indicate that each I1 motor domain is distinct in function: The I1β motor domain is an effective motor required for wild-type microtubule sliding, whereas the I1α motor domain may be responsible for local restraint of microtubule sliding. PMID:21148301

  18. CCDC151 Mutations Cause Primary Ciliary Dyskinesia by Disruption of the Outer Dynein Arm Docking Complex Formation

    PubMed Central

    Hjeij, Rim; Onoufriadis, Alexandros; Watson, Christopher M.; Slagle, Christopher E.; Klena, Nikolai T.; Dougherty, Gerard W.; Kurkowiak, Małgorzata; Loges, Niki T.; Diggle, Christine P.; Morante, Nicholas F.C.; Gabriel, George C.; Lemke, Kristi L.; Li, You; Pennekamp, Petra; Menchen, Tabea; Konert, Franziska; Marthin, June Kehlet; Mans, Dorus A.; Letteboer, Stef J.F.; Werner, Claudius; Burgoyne, Thomas; Westermann, Cordula; Rutman, Andrew; Carr, Ian M.; O’Callaghan, Christopher; Moya, Eduardo; Chung, Eddie M.K.; Sheridan, Eamonn; Nielsen, Kim G.; Roepman, Ronald; Bartscherer, Kerstin; Burdine, Rebecca D.; Lo, Cecilia W.; Omran, Heymut; Mitchison, Hannah M.

    2014-01-01

    A diverse family of cytoskeletal dynein motors powers various cellular transport systems, including axonemal dyneins generating the force for ciliary and flagellar beating essential to movement of extracellular fluids and of cells through fluid. Multisubunit outer dynein arm (ODA) motor complexes, produced and preassembled in the cytosol, are transported to the ciliary or flagellar compartment and anchored into the axonemal microtubular scaffold via the ODA docking complex (ODA-DC) system. In humans, defects in ODA assembly are the major cause of primary ciliary dyskinesia (PCD), an inherited disorder of ciliary and flagellar dysmotility characterized by chronic upper and lower respiratory infections and defects in laterality. Here, by combined high-throughput mapping and sequencing, we identified CCDC151 loss-of-function mutations in five affected individuals from three independent families whose cilia showed a complete loss of ODAs and severely impaired ciliary beating. Consistent with the laterality defects observed in these individuals, we found Ccdc151 expressed in vertebrate left-right organizers. Homozygous zebrafish ccdc151ts272a and mouse Ccdc151Snbl mutants display a spectrum of situs defects associated with complex heart defects. We demonstrate that CCDC151 encodes an axonemal coiled coil protein, mutations in which abolish assembly of CCDC151 into respiratory cilia and cause a failure in axonemal assembly of the ODA component DNAH5 and the ODA-DC-associated components CCDC114 and ARMC4. CCDC151-deficient zebrafish, planaria, and mice also display ciliary dysmotility accompanied by ODA loss. Furthermore, CCDC151 coimmunoprecipitates CCDC114 and thus appears to be a highly evolutionarily conserved ODA-DC-related protein involved in mediating assembly of both ODAs and their axonemal docking machinery onto ciliary microtubules. PMID:25192045

  19. LC2, the Chlamydomonas Homologue of the t Complex-encoded Protein Tctex2, Is Essential for Outer Dynein Arm Assembly

    PubMed Central

    Pazour, Gregory J.; Koutoulis, Anthony; Benashski, Sharon E.; Dickert, Bethany L.; Sheng, Hong; Patel-King, Ramila S.; King, Stephen M.; Witman, George B.

    1999-01-01

    Tctex2 is thought to be one of the distorter genes of the mouse t haplotype. This complex greatly biases the segregation of the chromosome that carries it such that in heterozygous +/t males, the t haplotype is transmitted to >95% of the offspring, a phenomenon known as transmission ratio distortion. The LC2 outer dynein arm light chain of Chlamydomonas reinhardtii is a homologue of the mouse protein Tctex2. We have identified Chlamydomonas insertional mutants with deletions in the gene encoding LC2 and demonstrate that the LC2 gene is the same as the ODA12 gene, the product of which had not been identified previously. Complete deletion of the LC2/ODA12 gene causes loss of all outer arms and a slow jerky swimming phenotype. Transformation of the deletion mutant with the cloned LC2/ODA12 gene restores the outer arms and rescues the motility phenotype. Therefore, LC2 is required for outer arm assembly. The fact that LC2 is an essential subunit of flagellar outer dynein arms allows us to propose a detailed mechanism whereby transmission ratio distortion is explained by the differential binding of mutant (t haplotype encoded) and wild-type dyneins to the axonemal microtubules of t-bearing or wild-type sperm, with resulting differences in their motility. PMID:10512883

  20. Loss-of-Function Mutations in the Human Ortholog of Chlamydomonas reinhardtii ODA7 Disrupt Dynein Arm Assembly and Cause Primary Ciliary Dyskinesia

    PubMed Central

    Duquesnoy, Philippe; Escudier, Estelle; Vincensini, Laetitia; Freshour, Judy; Bridoux, Anne-Marie; Coste, André; Deschildre, Antoine; de Blic, Jacques; Legendre, Marie; Montantin, Guy; Tenreiro, Henrique; Vojtek, Anne-Marie; Loussert, Céline; Clément, Annick; Escalier, Denise; Bastin, Philippe; Mitchell, David R.; Amselem, Serge

    2009-01-01

    Cilia and flagella are evolutionarily conserved structures that play various physiological roles in diverse cell types. Defects in motile cilia result in primary ciliary dyskinesia (PCD), the most prominent ciliopathy, characterized by the association of respiratory symptoms, male infertility, and, in nearly 50% of cases, situs inversus. So far, most identified disease-causing mutations involve genes encoding various ciliary components, such those belonging to the dynein arms that are essential for ciliary motion. Following a candidate-gene approach based on data from a mutant strain of the biflagellated alga Chlamydomonas reinhardtii carrying an ODA7 defect, we identified four families with a PCD phenotype characterized by the absence of both dynein arms and loss-of-function mutations in the human orthologous gene called LRRC50. Functional analyses performed in Chlamydomonas reinhardtii and in another flagellated protist, Trypanosoma brucei, support a key role for LRRC50, a member of the leucine-rich-repeat superfamily, in cytoplasmic preassembly of dynein arms. PMID:19944405

  1. Establishment of a mutation system in Tetrahymena outer arm dynein and P-loop functions of the alpha heavy chain (Dyh3p).

    PubMed

    Edamatsu, Masaki

    2017-01-29

    Axonemal dyneins are large AAA+ type motor proteins that exhibit unique motor properties during ciliary beating. This study established a mutation system for Tetrahymena outer arm dynein and characterized four nucleotide-binding loops (P-loops; P1-P4) in the alpha heavy chain (Dyh3p). Macronuclear transformation of the mutant DYH3 genes in DYH3-knockout (KO-DYH3) cells enabled P-loop mutations that abolish the ability of nucleotide binding to be stably maintained in the polyploid genome. This mutation system revealed that the P3 and P4 mutant dyneins rescued lethality in macronuclear KO-DYH3 cells and exhibited normal ciliary localization. Intriguingly, however, an in vitro motility assay showed that the P3 mutation abolished the motor activity of Dyh3p, whereas the P4 mutation did not affect the gliding velocity or gliding index of Dyh3p. In contrast, no P1 or P2 mutant cells were isolated from the KO-DYH3 cells, which suggests that nucleotide binding at the P1 and P2 sites is required for the intracellular function of Dyh3p. This mutation system will be useful for further molecular studies of diverse axonemal dyneins and ciliary motility.

  2. Characterization of a new oda3 allele, oda3-6, defective in assembly of the outer dynein arm-docking complex in Chlamydomonas reinhardtii

    PubMed Central

    Montes-Berrueta, Daniela; Hou, Yuqing; Yang, Fan; Scarbrough, Chasity; Witman, George B.

    2017-01-01

    We have used an insertional mutagenesis approach to generate new C. reinhardtii motility mutants. Of 56 mutants isolated, one is a new allele at the ODA3 locus, called oda3-6. Similar to the previously characterized oda3 alleles, oda3-6 has a slow-jerky swimming phenotype and reduced swimming speed. The oda3-6 mutant fails to assemble the outer dynein arm motor and outer dynein arm—docking complex (ODA-DC) in the ciliary axoneme due to an insertion in the 5’ end of the DCC1 gene, which encodes the DC1 subunit of the ODA-DC. Transformation of oda3-6 with the wild-type DCC1 gene rescues the mutant swimming phenotype and restores assembly of the ODA-DC and the outer dynein arm in the cilium. This is the first oda3 mutant to be characterized at the molecular level and is likely to be very useful for further analysis of DC1 function. PMID:28291812

  3. Cytoplasmic dynein.

    PubMed

    Allan, Victoria J

    2011-10-01

    The organization and function of eukaryotic cells rely on the action of many different molecular motor proteins. Cytoplasmic dynein drives the movement of a wide range of cargoes towards the minus ends of microtubules, and these events are needed, not just at the single-cell level, but are vital for correct development. In the present paper, I review recent progress on understanding dynein's mechanochemistry, how it is regulated and how it binds to such a plethora of cargoes. The importance of a number of accessory factors in these processes is discussed.

  4. Integrated Control of Axonemal Dynein AAA+ Motors

    PubMed Central

    King, Stephen M.

    2012-01-01

    Axonemal dyneins are AAA+ enzymes that convert ATP hydrolysis to mechanical work. This leads to the sliding of doublet microtubules with respect to each other and ultimately the generation of ciliary/flagellar beating. However, in order for useful work to be generated, the action of individual dynein motors must be precisely controlled. In addition, cells modulate the motility of these organelles through a variety of second messenger systems and these signals too must be integrated by the dynein motors to yield an appropriate output. This review describes the current status of efforts to understand dynein control mechanisms and their connectivity focusing mainly on studies of the outer dynein arm from axonemes of the unicellular biflagellate green alga Chlamydomonas. PMID:22406539

  5. TTC25 Deficiency Results in Defects of the Outer Dynein Arm Docking Machinery and Primary Ciliary Dyskinesia with Left-Right Body Asymmetry Randomization.

    PubMed

    Wallmeier, Julia; Shiratori, Hidetaka; Dougherty, Gerard W; Edelbusch, Christine; Hjeij, Rim; Loges, Niki T; Menchen, Tabea; Olbrich, Heike; Pennekamp, Petra; Raidt, Johanna; Werner, Claudius; Minegishi, Katsura; Shinohara, Kyosuke; Asai, Yasuko; Takaoka, Katsuyoshi; Lee, Chanjae; Griese, Matthias; Memari, Yasin; Durbin, Richard; Kolb-Kokocinski, Anja; Sauer, Sascha; Wallingford, John B; Hamada, Hiroshi; Omran, Heymut

    2016-08-04

    Multiprotein complexes referred to as outer dynein arms (ODAs) develop the main mechanical force to generate the ciliary and flagellar beat. ODA defects are the most common cause of primary ciliary dyskinesia (PCD), a congenital disorder of ciliary beating, characterized by recurrent infections of the upper and lower airways, as well as by progressive lung failure and randomization of left-right body asymmetry. Using a whole-exome sequencing approach, we identified recessive loss-of-function mutations within TTC25 in three individuals from two unrelated families affected by PCD. Mice generated by CRISPR/Cas9 technology and carrying a deletion of exons 2 and 3 in Ttc25 presented with laterality defects. Consistently, we observed immotile nodal cilia and missing leftward flow via particle image velocimetry. Furthermore, transmission electron microscopy (TEM) analysis in TTC25-deficient mice revealed an absence of ODAs. Consistent with our findings in mice, we were able to show loss of the ciliary ODAs in humans via TEM and immunofluorescence (IF) analyses. Additionally, IF analyses revealed an absence of the ODA docking complex (ODA-DC), along with its known components CCDC114, CCDC151, and ARMC4. Co-immunoprecipitation revealed interaction between the ODA-DC component CCDC114 and TTC25. Thus, here we report TTC25 as a new member of the ODA-DC machinery in humans and mice.

  6. Control of cytoplasmic dynein force production and processivity by its C-terminal domain

    PubMed Central

    Nicholas, Matthew P.; Höök, Peter; Brenner, Sibylle; Wynne, Caitlin L.; Vallee, Richard B.; Gennerich, Arne

    2015-01-01

    Cytoplasmic dynein is a microtubule motor involved in cargo transport, nuclear migration and cell division. Despite structural conservation of the dynein motor domain from yeast to higher eukaryotes, the extensively studied S. cerevisiae dynein behaves distinctly from mammalian dyneins, which produce far less force and travel over shorter distances. However, isolated reports of yeast-like force production by mammalian dynein have called interspecies differences into question. We report that functional differences between yeast and mammalian dynein are real and attributable to a C-terminal motor element absent in yeast, which resembles a ‘cap’ over the central pore of the mammalian dynein motor domain. Removal of this cap increases the force generation of rat dynein from 1 pN to a yeast-like 6 pN and greatly increases its travel distance. Our findings identify the CT-cap as a novel regulator of dynein function. PMID:25670086

  7. Control of cytoplasmic dynein force production and processivity by its C-terminal domain

    NASA Astrophysics Data System (ADS)

    Nicholas, Matthew P.; Höök, Peter; Brenner, Sibylle; Wynne, Caitlin L.; Vallee, Richard B.; Gennerich, Arne

    2015-02-01

    Cytoplasmic dynein is a microtubule motor involved in cargo transport, nuclear migration and cell division. Despite structural conservation of the dynein motor domain from yeast to higher eukaryotes, the extensively studied S. cerevisiae dynein behaves distinctly from mammalian dyneins, which produce far less force and travel over shorter distances. However, isolated reports of yeast-like force production by mammalian dynein have called interspecies differences into question. We report that functional differences between yeast and mammalian dynein are real and attributable to a C-terminal motor element absent in yeast, which resembles a ‘cap’ over the central pore of the mammalian dynein motor domain. Removal of this cap increases the force generation of rat dynein from 1 pN to a yeast-like 6 pN and greatly increases its travel distance. Our findings identify the CT-cap as a novel regulator of dynein function.

  8. Are the local adjustments of the relative spatial frequencies of the dynein arms and the beta-tubulin monomers involved in the regulation of the "9+2" axoneme?

    PubMed

    Cibert, Christian

    2008-07-07

    The "9+2" axoneme is a highly specific cylindrical machine whose periodic bending is due to the cumulative shear of its 9 outer doublets of microtubules. Because of the discrete architecture of the tubulin monomers and the active appendices that the outer doublets carry (dynein arms, nexin links and radial spokes), this movement corresponds to the relative shear of these topological verniers, whose characteristics depend on the geometry of the wave train. When an axonemal segment bends, this induces the compressed and dilated conformations of the tubulin monomers and, consequently, the modification of the spatial frequencies of the appendages that the outer doublets carry. From a dynamic point of view, the adjustments of the spatial frequencies of the elements of the two facing verniers that must interact create different longitudinal periodic patterns of distribution of the joint probability of the molecular interaction as a function of the location of the doublet pairs around the axonemal cylinder and their spatial orientation within the axonemal cylinder. During the shear, these patterns move along the outer doublet intervals at a speed that ranges from one to more than a thousand times that of sliding, in two opposite directions along the two opposite halves of the axoneme separated by the bending plane, respecting the polarity of the dynein arms within the axoneme. Consequently, these waves might be involved in the regulation of the alternating activity of the dynein arms along the flagellum, because they induce the necessary intermolecular dialog along the axoneme since they could be an element of the local dynamic stability/instability equilibrium of the axoneme. This complements the geometric clutch model [Lindemann, C., 1994. A "geometric clutch" hypothesis to explain oscillations of the axoneme of cilia and flagella. J. Theor. Biol. 168, 175-189].

  9. Absent Apologies

    ERIC Educational Resources Information Center

    Drew, Paul; Hepburn, Alexa

    2016-01-01

    Absent apologies--apologies that were expected but are not forthcoming--are quite frequently identified and commented on, for instance in the media. In this article we discuss two kinds of evidence that apologies can be "noticeably" absent for participants in ordinary interactions. The first kind is the delays that can occur in the…

  10. Cytoplasmic dynein nomenclature

    PubMed Central

    Pfister, K. Kevin; Fisher, Elizabeth M.C.; Gibbons, Ian R.; Hays, Thomas S.; Holzbaur, Erika L.F.; McIntosh, J. Richard; Porter, Mary E.; Schroer, Trina A.; Vaughan, Kevin T.; Witman, George B.; King, Stephen M.; Vallee, Richard B.

    2005-01-01

    A variety of names has been used in the literature for the subunits of cytoplasmic dynein complexes. Thus, there is a strong need for a more definitive consensus statement on nomenclature. This is especially important for mammalian cytoplasmic dyneins, many subunits of which are encoded by multiple genes. We propose names for the mammalian cytoplasmic dynein subunit genes and proteins that reflect the phylogenetic relationships of the genes and the published studies clarifying the functions of the polypeptides. This nomenclature recognizes the two distinct cytoplasmic dynein complexes and has the flexibility to accommodate the discovery of new subunits and isoforms. PMID:16260502

  11. The LC7 Light Chains of Chlamydomonas Flagellar Dyneins Interact with Components Required for Both Motor Assembly and Regulation

    PubMed Central

    DiBella, Linda M.; Sakato, Miho; Patel-King, Ramila S.; Pazour, Gregory J.; King, Stephen M.

    2004-01-01

    Members of the LC7/Roadblock family of light chains (LCs) have been found in both cytoplasmic and axonemal dyneins. LC7a was originally identified within Chlamydomonas outer arm dynein and associates with this motor's cargo-binding region. We describe here a novel member of this protein family, termed LC7b that is also present in the Chlamydomonas flagellum. Levels of LC7b are reduced ∼20% in axonemes isolated from strains lacking inner arm I1 and are ∼80% lower in the absence of the outer arms. When both dyneins are missing, LC7b levels are diminished to <10%. In oda9 axonemal extracts that completely lack outer arms, LC7b copurifies with inner arm I1, whereas in ida1 extracts that are devoid of I1 inner arms it associates with outer arm dynein. We also have observed that some LC7a is present in both isolated axonemes and purified 18S dynein from oda1, suggesting that it is also a component of both the outer arm and inner arm I1. Intriguingly, in axonemal extracts from the LC7a null mutant, oda15, which assembles ∼30% of its outer arms, LC7b fails to copurify with either dynein, suggesting that it interacts with LC7a. Furthermore, both the outer arm γ heavy chain and DC2 from the outer arm docking complex completely dissociate after salt extraction from oda15 axonemes. EDC cross-linking of purified dynein revealed that LC7b interacts with LC3, an outer dynein arm thioredoxin; DC2, an outer arm docking complex component; and also with the phosphoprotein IC138 from inner arm I1. These data suggest that LC7a stabilizes both the outer arms and inner arm I1 and that both LC7a and LC7b are involved in multiple intradynein interactions within both dyneins. PMID:15304520

  12. Diverse Roles of Axonemal Dyneins in Drosophila Auditory Neuron Function and Mechanical Amplification in Hearing

    PubMed Central

    Karak, Somdatta; Jacobs, Julie S.; Kittelmann, Maike; Spalthoff, Christian; Katana, Radoslaw; Sivan-Loukianova, Elena; Schon, Michael A.; Kernan, Maurice J.; Eberl, Daniel F.; Göpfert, Martin C.

    2015-01-01

    Much like vertebrate hair cells, the chordotonal sensory neurons that mediate hearing in Drosophila are motile and amplify the mechanical input of the ear. Because the neurons bear mechanosensory primary cilia whose microtubule axonemes display dynein arms, we hypothesized that their motility is powered by dyneins. Here, we describe two axonemal dynein proteins that are required for Drosophila auditory neuron function, localize to their primary cilia, and differently contribute to mechanical amplification in hearing. Promoter fusions revealed that the two axonemal dynein genes Dmdnah3 (=CG17150) and Dmdnai2 (=CG6053) are expressed in chordotonal neurons, including the auditory ones in the fly’s ear. Null alleles of both dyneins equally abolished electrical auditory neuron responses, yet whereas mutations in Dmdnah3 facilitated mechanical amplification, amplification was abolished by mutations in Dmdnai2. Epistasis analysis revealed that Dmdnah3 acts downstream of Nan-Iav channels in controlling the amplificatory gain. Dmdnai2, in addition to being required for amplification, was essential for outer dynein arms in auditory neuron cilia. This establishes diverse roles of axonemal dyneins in Drosophila auditory neuron function and links auditory neuron motility to primary cilia and axonemal dyneins. Mutant defects in sperm competition suggest that both dyneins also function in sperm motility. PMID:26608786

  13. Mutations in axonemal dynein assembly factor DNAAF3 cause primary ciliary dyskinesia

    PubMed Central

    Mitchison, Hannah M.; Schmidts, Miriam; Loges, Niki T.; Freshour, Judy; Dritsoula, Athina; Hirst, Rob A.; O’Callaghan, Christopher; Blau, Hannah; Dabbagh, Maha Al; Olbrich, Heike; Beales, Philip L.; Yagi, Toshiki; Mussaffi, Huda; Chung, Eddie M.K.; Omran, Heymut; Mitchell, David R.

    2012-01-01

    Primary Ciliary Dyskinesia (PCD) most often arises from loss of the dynein motors that power ciliary beating. Here we show that PF22/DNAAF3, a previously uncharacterized protein, is essential for the preassembly of dyneins into complexes prior to their transport into cilia. We identified loss-of-function mutations in the human DNAAF3 gene in patients from families with situs inversus and defects in assembly of inner and outer dynein arms. Zebrafish dnaaf3 knockdown likewise disrupts dynein arm assembly and ciliary motility, causing PCD phenotypes including hydrocephalus and laterality malformations. Chlamydomonas reinhardtii PF22 is exclusively cytoplasmic, and a null mutant fails to assemble outer and some inner dynein arms. Altered abundance of dynein subunits in mutant cytoplasm suggests PF22/DNAAF3 acts at a similar stage to other preassembly proteins, PF13/KTU and ODA7/LRRC50, in the dynein preassembly pathway. These results support the existence of a conserved multi-step pathway for cytoplasmic formation of assembly-competent ciliary dynein complexes. PMID:22387996

  14. A solid-state control system for dynein-based ciliary/flagellar motility

    PubMed Central

    2013-01-01

    Ciliary and flagellar beating requires the coordinated action of multiple dyneins with different enzymatic and motor properties. In this issue, Yamamoto et al. (2013. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201211048) identify the MIA (modifier of inner arms) complex within the Chlamydomonas reinhardtii axoneme that physically links to a known regulatory structure and provides a signaling conduit from the radial spokes to an inner arm dynein essential for waveform determination. PMID:23569213

  15. Dynein-deficient flagella respond to increased viscosity with contrasting changes in power and recovery strokes.

    PubMed

    Wilson, Kate S; Gonzalez, Olivia; Dutcher, Susan K; Bayly, Philip V

    2015-09-01

    Changes in the flagellar waveform in response to increased viscosity were investigated in uniflagellate mutants of Chlamydomonas reinhardtii. We hypothesized that the waveforms of mutants lacking different dynein arms would change in different ways as viscosity was increased, and that these variations would illuminate the feedback pathways from force to dynein activity. Previous studies have investigated the effects of viscosity on cell body motion, propulsive force, and power in different mutants, but the effect on waveform has not yet been fully characterized. Beat frequency decreases with viscosity in wild-type uniflagellate (uni1) cells, and outer dynein arm deficient (oda2) mutants. In contrast, the inner dynein arm mutant ida1 (lacking I1/f) maintains beat frequency at high viscosity but alters its flagellar waveform more than either wild-type or oda2. The ida1 waveform is narrower than wild-type, primarily due to an abbreviated recovery stroke; this difference is amplified at high viscosity. The oda2 mutant in contrast, maintains a consistent waveform at high and low viscosity with a slightly longer power stroke than wild-type. Analysis of the delays and shear displacements between bends suggest that direct force feedback in the outer dynein arm system may initiate switching of dynein activity. In contrast, I1/f dynein appears to delay switching, most markedly at the initiation of the power stroke, possibly by controlling inter-doublet separation.

  16. Analyses of Dynein Heavy Chain Mutations Reveal Complex Interactions Between Dynein Motor Domains and Cellular Dynein Functions

    PubMed Central

    Sivagurunathan, Senthilkumar; Schnittker, Robert R.; Razafsky, David S.; Nandini, Swaran; Plamann, Michael D.; King, Stephen J.

    2012-01-01

    Cytoplasmic dynein transports cargoes for a variety of crucial cellular functions. However, since dynein is essential in most eukaryotic organisms, the in-depth study of the cellular function of dynein via genetic analysis of dynein mutations has not been practical. Here, we identify and characterize 34 different dynein heavy chain mutations using a genetic screen of the ascomycete fungus Neurospora crassa, in which dynein is nonessential. Interestingly, our studies show that these mutations segregate into five different classes based on the in vivo localization of the mutated dynein motors. Furthermore, we have determined that the different classes of dynein mutations alter vesicle trafficking, microtubule organization, and nuclear distribution in distinct ways and require dynactin to different extents. In addition, biochemical analyses of dynein from one mutant strain show a strong correlation between its in vitro biochemical properties and the aberrant intracellular function of that altered dynein. When the mutations were mapped to the published dynein crystal structure, we found that the three-dimensional structural locations of the heavy chain mutations were linked to particular classes of altered dynein functions observed in cells. Together, our data indicate that the five classes of dynein mutations represent the entrapment of dynein at five separate points in the dynein mechanochemical and transport cycles. We have developed N. crassa as a model system where we can dissect the complexities of dynein structure, function, and interaction with other proteins with genetic, biochemical, and cell biological studies. PMID:22649085

  17. Dynein prevents erroneous kinetochore-microtubule attachments in mitosis.

    PubMed

    Barisic, Marin; Maiato, Helder

    2015-01-01

    Equal distribution of the genetic material during cell division relies on efficient congression of chromosomes to the metaphase plate. Prior to their alignment, the Dynein motor recruited to kinetochores transports a fraction of laterally-attached chromosomes along microtubules toward the spindle poles. By doing that, Dynein not only contributes to chromosome movements, but also prevents premature stabilization of end-on kinetochore-microtubule attachments. This is achieved by 2 parallel mechanisms: 1) Dynein-mediated poleward movement of chromosomes counteracts opposite polar-ejection forces (PEFs) on chromosome arms by the microtubule plus-end-directed motors chromokinesins. Otherwise, they could stabilize erroneous syntelic kinetochore-microtubule attachments and lead to the random ejection of chromosomes away from the spindle poles; and 2) By transporting chromosomes to the spindle poles, Dynein brings the former to the zone of highest Aurora A kinase activity, further destabilizing kinetochore-microtubule attachments. Thus, Dynein plays an important role in keeping chromosome segregation error-free by preventing premature stabilization of kinetochore-microtubule attachments near the spindle poles.

  18. How dynein moves along microtubules

    PubMed Central

    Bhabha, Gira; Johnson, Graham T.; Schroeder, Courtney M.; Vale, Ronald D.

    2015-01-01

    Cytoplasmic dynein, a member of the AAA family of ATPases, drives the processive movement of numerous intracellular cargos towards the minus end of microtubules. Here, we summarize the structural and motile properties of dynein and highlight features that distinguish this motor from kinesin-1 and myosin V, two well-studied transport motors. Integrating information from recent crystal and cryo-EM structures as well as high-resolution single molecule studies, we also discuss models for how dynein biases its movement in one direction along a microtubule track, and present a movie that illustrates these principles. PMID:26678005

  19. Mechanosignaling between central apparatus and radial spokes controls axonemal dynein activity

    PubMed Central

    Oda, Toshiyuki; Yanagisawa, Haruaki; Yagi, Toshiki

    2014-01-01

    Cilia/flagella are conserved organelles that generate fluid flow in eukaryotes. The bending motion of flagella requires concerted activity of dynein motors. Although it has been reported that the central pair apparatus (CP) and radial spokes (RSs) are important for flagellar motility, the molecular mechanism underlying CP- and RS-mediated dynein regulation has not been identified. In this paper, we identified nonspecific intermolecular collision between CP and RS as one of the regulatory mechanisms for flagellar motility. By combining cryoelectron tomography and motility analyses of Chlamydomonas reinhardtii flagella, we show that binding of streptavidin to RS heads paralyzed flagella. Moreover, the motility defect in a CP projection mutant could be rescued by the addition of exogenous protein tags on RS heads. Genetic experiments demonstrated that outer dynein arms are the major downstream effectors of CP- and RS-mediated regulation of flagellar motility. These results suggest that mechanosignaling between CP and RS regulates dynein activity in eukaryotic flagella. PMID:24590175

  20. Fine-Tuning Motile Cilia and Flagella: Evolution of the Dynein Motor Proteins from Plants to Humans at High Resolution

    PubMed Central

    Kollmar, Martin

    2016-01-01

    The flagellum is a key innovation linked to eukaryogenesis. It provides motility by regulated cycles of bending and bend propagation, which are thought to be controlled by a complex arrangement of seven distinct dyneins in repeated patterns of outer- (OAD) and inner-arm dynein (IAD) complexes. Electron tomography showed high similarity of this axonemal repeat pattern across ciliates, algae, and animals, but the diversity of dynein sequences across the eukaryotes has not yet comprehensively been resolved and correlated with structural data. To shed light on the evolution of the axoneme I performed an exhaustive analysis of dyneins using the available sequenced genome data. Evidence from motor domain phylogeny allowed expanding the current set of nine dynein subtypes by eight additional isoforms with, however, restricted taxonomic distributions. I confirmed the presence of the nine dyneins in all eukaryotic super-groups indicating their origin predating the last eukaryotic common ancestor. The comparison of the N-terminal tail domains revealed a most likely axonemal dynein origin of the new classes, a group of chimeric dyneins in plants/algae and Stramenopiles, and the unique domain architecture and origin of the outermost OADs present in green algae and ciliates but not animals. The correlation of sequence and structural data suggests the single-headed class-8 and class-9 dyneins to localize to the distal end of the axonemal repeat and the class-7 dyneins filling the region up to the proximal heterodimeric IAD. Tracing dynein gene duplications across the eukaryotes indicated ongoing diversification and fine-tuning of flagellar functions in extant taxa and species. PMID:27880711

  1. Recombinant human cytoplasmic dynein heavy chain 1 and 2: observation of dynein-2 motor activity in vitro.

    PubMed

    Ichikawa, Muneyoshi; Watanabe, Yuta; Murayama, Takashi; Toyoshima, Yoko Yano

    2011-08-04

    Cytoplasmic dynein is a microtubule (MT) motor protein comprising two classes: dynein-1 and dynein-2. We purified recombinant human dynein-1 and dynein-2 from HEK-293 cells by expressing the streptavidin-binding peptide-tagged human cytoplasmic dynein-1 and dynein-2 heavy chains (HCs), respectively. Electron microscopy of the purified molecules revealed a two-headed structure composed of characteristic dynein motor domains. In an in vitro MT gliding assay, both dynein-1 and dynein-2 showed minus-end-directed motor activities. This is the first demonstration of dynein-2 motor activity, which supports the retrograde intraflagellar transport role of dynein-2. Our expression system of dynein HCs provides a useful means to investigate dynein functions.

  2. Subunit organization in cytoplasmic dynein subcomplexes

    PubMed Central

    King, Stephen J.; Bonilla, Myriam; Rodgers, Michael E.; Schroer, Trina A.

    2002-01-01

    Because cytoplasmic dynein plays numerous critical roles in eukaryotic cells, determining the subunit composition and the organization and functions of the subunits within dynein are important goals. This has been difficult partly because of accessory polypeptide heterogeneity of dynein populations. The motor domain containing heavy chains of cytoplasmic dynein are associated with multiple intermediate, light intermediate, and light chain accessory polypeptides. We examined the organization of these subunits within cytoplasmic dynein by separating the molecule into two distinct subcomplexes. These subcomplexes were competent to reassemble into a molecule with dynein-like properties. One subcomplex was composed of the dynein heavy and light intermediate chains whereas the other subcomplex was composed of the intermediate and light chains. The intermediate and light chain subcomplex could be further separated into two pools, only one of which contained dynein light chains. The two pools had distinct intermediate chain compositions, suggesting that intermediate chain isoforms have different light chain–binding properties. When the two intermediate chain pools were characterized by analytical velocity sedimentation, at least four molecular components were seen: intermediate chain monomers, intermediate chain dimers, intermediate chain monomers with bound light chains, and a mixture of intermediate chain dimers with assorted bound light chains. These data provide new insights into the compositional heterogeneity and assembly of the cytoplasmic dynein complex and suggest that individual dynein molecules have distinct molecular compositions in vivo. PMID:11967380

  3. Modeling of Single Molecule Cytoplasmic Dynein

    NASA Astrophysics Data System (ADS)

    Yu, Clare

    2010-03-01

    A living cell has an infrastructure much like that of a city. We will describe the transportation system that consists of roads (filaments) and molecular motors (proteins) that haul cargo along these roads. Dynein is one type of motor protein that walks along microtubules towards the nucleus of the cell. Dynein is more complicated in its structure and function than other motors. Experiments have found that, unlike other motors, dynein can take different size steps along microtubules depending on load and ATP concentration. We use Monte Carlo simulations to model the molecular motor function of cytoplasmic dynein at the single molecule level. The theory relates dynein's enzymatic properties to its mechanical force production. Our simulations reproduce the main features of recent single molecule experiments. We make testable predictions that should guide future experiments related to dynein function.

  4. Cytoplasmic dynein and early endosome transport

    PubMed Central

    Xiang, Xin; Qiu, Rongde; Yao, Xuanli; Arst, Herbert N.; Peñalva, Miguel A.; Zhang, Jun

    2015-01-01

    Microtubule-based distribution of organelles/vesicles is crucial for the function of many types of eukaryotic cells and the molecular motor cytoplasmic dynein is required for transporting a variety of cellular cargos toward the microtubule minus ends. Early endosomes represent a major cargo of dynein in filamentous fungi, and dynein regulators such as LIS1 and the dynactin complex are both required for early endosome movement. In fungal hyphae, kinesin-3 and dynein drive bi-directional movements of early endosomes. Dynein accumulates at microtubule plus ends; this accumulation depends on kinesin-1 and dynactin, and it is important for early endosome movements towards the microtubule minus ends. The physical interaction between dynein and early endosome requires the dynactin complex, and in particular, its p25 component. The FTS-Hook-FHIP (FHF) complex links dynein-dynactin to early endosomes, and within the FHF complex, Hook interacts with dynein-dynactin, and Hook-early endosome interaction depends on FHIP and FTS. PMID:26001903

  5. Structural biology of cytoplasmic and axonemal dyneins.

    PubMed

    Ishikawa, Takashi

    2012-08-01

    Dyneins are microtubule-based, ATP-driven motor proteins with six tandemly linked AAA+ domains, a long N-terminal tail and a coiled-coil stalk. Cytoplasmic dyneins function as individual homodimers and are responsible for minus-end-oriented transport along microtubules. Axonemal dyneins of flagella/cilia are anchored in arrays to peripheral microtubule doublets by their N-terminal tails, and generate sliding motions of adjacent microtubule doublets toward the plus end. The coiled-coil stalk is responsible for communication between the AAA+ domains and the microtubule binding domain. A number of isoforms of axonemal dyneins are integrated to generate bending motion. In this article I will review recent structural studies and address the question as to how dyneins generate force and cause bending in flagella/cilia.

  6. A conserved CaM- and radial spoke associated complex mediates regulation of flagellar dynein activity.

    PubMed

    Dymek, Erin E; Smith, Elizabeth F

    2007-11-05

    For virtually all cilia and eukaryotic flagella, the second messengers calcium and cyclic adenosine monophosphate are implicated in modulating dynein- driven microtubule sliding to regulate beating. Calmodulin (CaM) localizes to the axoneme and is a key calcium sensor involved in regulating motility. Using immunoprecipitation and mass spectrometry, we identify members of a CaM-containing complex that are involved in regulating dynein activity. This complex includes flagellar-associated protein 91 (FAP91), which shares considerable sequence similarity to AAT-1, a protein originally identified in testis as an A-kinase anchor protein (AKAP)- binding protein. FAP91 directly interacts with radial spoke protein 3 (an AKAP), which is located at the base of the spoke. In a microtubule sliding assay, the addition of antibodies generated against FAP91 to mutant axonemes with reduced dynein activity restores dynein activity to wild-type levels. These combined results indicate that the CaM- and spoke-associated complex mediates regulatory signals between the radial spokes and dynein arms.

  7. A Mouse Neurodegenerative Dynein Heavy Chain Mutation Alters Dynein Motility and Localization in Neurospora crassa

    PubMed Central

    Sivagurunathan, Senthilkumar; Schnittker, Robert R.; Nandini, Swaran; Plamann, Michael D.; King, Stephen J.

    2013-01-01

    Cytoplasmic dynein is responsible for the transport and delivery of cargoes in organisms ranging from humans to fungi. Dysfunction of dynein motor machinery due to mutations in dynein or its activating complex dynactin can result in one of several neurological diseases in mammals. The mouse Legs at odd angles (Loa) mutation in the tail domain of the dynein heavy chain has been shown to lead to progressive neurodegeneration in mice. The mechanism by which the Loa mutation affects dynein function is just beginning to be understood. In this work, we generated the dynein tail mutation observed in Loa mice into the Neurospora crassa genome and utilized cell biological and complementing biochemical approaches to characterize how that tail mutation affected dynein function. We determined that the Loa mutation exhibits several subtle defects upon dynein function in N. crassa that were not seen in mice, including alterations in dynein localization, impaired velocity of vesicle transport, and in the biochemical properties of purified motors. Our work provides new information on the role of the tail domain on dynein function and points out areas of future research that will be of interest to pursue in mammalian systems. PMID:22991199

  8. Dynein Light Intermediate Chain 2 Facilitates the Metaphase to Anaphase Transition by Inactivating the Spindle Assembly Checkpoint

    PubMed Central

    Mahale, Sagar P.; Sharma, Amit; Mylavarapu, Sivaram V. S.

    2016-01-01

    The multi-functional molecular motor cytoplasmic dynein performs diverse essential roles during mitosis. The mechanistic importance of the dynein Light Intermediate Chain homologs, LIC1 and LIC2 is unappreciated, especially in the context of mitosis. LIC1 and LIC2 are believed to exist in distinct cytoplasmic dynein complexes as obligate subunits. LIC1 had earlier been reported to be required for metaphase to anaphase progression by inactivating the kinetochore-microtubule attachment-sensing arm of the spindle assembly checkpoint (SAC). However, the functional importance of LIC2 during mitosis remains elusive. Here we report prominent novel roles for the LIC2 subunit of cytoplasmic dynein in regulating the spindle assembly checkpoint. LIC2 depletion in mammalian cells led to prolonged metaphase arrest in the presence of an active SAC and also to stretched kinetochores, thus implicating it in SAC inactivation. Quantitative fluorescence microscopy of SAC components revealed accumulation of both attachment- and tension-sensing checkpoint proteins at metaphase kinetochores upon LIC2 depletion. These observations support a stronger and more diverse role in checkpoint inactivation for LIC2 in comparison to its close homolog LIC1. Our study uncovers a novel functional hierarchy during mitotic checkpoint inactivation between the closely related but homologous LIC subunits of cytoplasmic dynein. These subtle functional distinctions between dynein subpopulations could be exploited to study specific aspects of the spindle assembly checkpoint, which is a key mediator of fidelity in eukaryotic cell division. PMID:27441562

  9. Heterogeneity of dynein structure implies coordinated suppression of dynein motor activity in the axoneme.

    PubMed

    Maheshwari, Aditi; Ishikawa, Takashi

    2012-08-01

    Axonemal dyneins provide the driving force for flagellar/ciliary bending. Nucleotide-induced conformational changes of flagellar dynein have been found both in vitro and in situ by electron microscopy, and in situ studies demonstrated the coexistence of at least two conformations in axonemes in the presence of nucleotides (the apo and the nucleotide-bound forms). The distribution of the two forms suggested cooperativity between adjacent dyneins on axonemal microtubule doublets. Although the mechanism of such cooperativity is unknown it might be related to the mechanism of bending. To explore the mechanism by which structural heterogeneity of axonemal dyneins is induced by nucleotides, we used cilia from Tetrahymena thermophila to examine the structure of dyneins in a) the intact axoneme and b) microtubule doublets separated from the axoneme, both with and without additional pure microtubules. We also employed an ATPase assay on these specimens to investigate dynein activity functionally. Dyneins on separated doublets show more activation by nucleotides than those in the intact axoneme, both structurally and in the ATPase assay, and this is especially pronounced when the doublets are coupled with added microtubules, as expected. Paralleling the reduced ATPase activity in the intact axonemes, a lower proportion of these dyneins are in the nucleotide-bound form. This indicates a coordinated suppression of dynein activity in the axoneme, which could be the key for understanding the bending mechanism.

  10. Dynein at kinetochores: Making the connection.

    PubMed

    McHugh, Toni; Welburn, Julie P I

    2017-04-03

    Dynein removes the checkpoint proteins from kinetochores once chromosomes are bioriented. In this issue, Gama et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201610108) and Mosalaganti et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201611060) reveal the molecular basis for how dynein and its adaptor protein Spindly are recruited to the ROD-Zw10-Zwilch complex in the fibrous corona of unattached kinetochores.

  11. CNS Myelination Requires Cytoplasmic Dynein Function

    PubMed Central

    Yang, Michele L.; Shin, Jimann; Kearns, Christina A.; Langworthy, Melissa M.; Snell, Heather; Walker, Macie B.; Appel, Bruce

    2014-01-01

    Background Cytoplasmic dynein provides the main motor force for minus-end-directed transport of cargo on microtubules. Within the vertebrate central nervous system (CNS), proliferation, neuronal migration and retrograde axon transport are among the cellular functions known to require dynein. Accordingly, mutations of DYNC1H1, which encodes the heavy chain subunit of cytoplasmic dynein, have been linked to developmental brain malformations and axonal pathologies. Oligodendrocytes, the myelinating glial cell type of the CNS, migrate from their origins to their target axons and subsequently extend multiple long processes that ensheath axons with specialized insulating membrane. These processes are filled with microtubules, which facilitate molecular transport of myelin components. However, whether oligodendrocytes require cytoplasmic dynein to ensheath axons with myelin is not known. Results We identified a mutation of zebrafish dync1h1 in a forward genetic screen that caused a deficit of oligodendrocytes. Using in vivo imaging and gene expression analyses, we additionally found evidence that dync1h1 promotes axon ensheathment and myelin gene expression. Conclusions In addition to its well known roles in axon transport and neuronal migration, cytoplasmic dynein contributes to neural development by promoting myelination. PMID:25488883

  12. A Unified Taxonomy for Ciliary Dyneins

    PubMed Central

    Hom, Erik F.Y.; Witman, George B.; Harris, Elizabeth H.; Dutcher, Susan K.; Kamiya, Ritsu; Mitchell, David R.; Pazour, Gregory J.; Porter, Mary E.; Sale, Winfield S.; Wirschell, Maureen; Yagi, Toshiki; King, Stephen M.

    2011-01-01

    The formation and function of eukaryotic cilia/flagella require the action of a large array of dynein microtubule motor complexes. Due to genetic, biochemical, and microscopic tractability, Chlamydomonas reinhardtii has become the premier model system in which to dissect the role of dyneins in flagellar assembly, motility, and signaling. Currently, fifty-four proteins have been described as components of various Chlamydomonas flagellar dyneins or as factors required for their assembly in the cytoplasm and/or transport into the flagellum; orthologues of nearly all these components are present in other ciliated organisms including humans. For historical reasons, the nomenclature of these diverse dynein components and their corresponding genes, mutant alleles and orthologues has become extraordinarily confusing. Here, we unify Chlamydomonas dynein gene nomenclature and establish a systematic classification scheme based on structural properties of the encoded proteins. Furthermore, we provide detailed tabulations of the various mutant alleles and protein aliases that have been used and explicitly define the correspondence with orthologous components in other model organisms and humans. PMID:21953912

  13. X-linked primary ciliary dyskinesia due to mutations in the cytoplasmic axonemal dynein assembly factor PIH1D3.

    PubMed

    Olcese, Chiara; Patel, Mitali P; Shoemark, Amelia; Kiviluoto, Santeri; Legendre, Marie; Williams, Hywel J; Vaughan, Cara K; Hayward, Jane; Goldenberg, Alice; Emes, Richard D; Munye, Mustafa M; Dyer, Laura; Cahill, Thomas; Bevillard, Jeremy; Gehrig, Corinne; Guipponi, Michel; Chantot, Sandra; Duquesnoy, Philippe; Thomas, Lucie; Jeanson, Ludovic; Copin, Bruno; Tamalet, Aline; Thauvin-Robinet, Christel; Papon, Jean-François; Garin, Antoine; Pin, Isabelle; Vera, Gabriella; Aurora, Paul; Fassad, Mahmoud R; Jenkins, Lucy; Boustred, Christopher; Cullup, Thomas; Dixon, Mellisa; Onoufriadis, Alexandros; Bush, Andrew; Chung, Eddie M K; Antonarakis, Stylianos E; Loebinger, Michael R; Wilson, Robert; Armengot, Miguel; Escudier, Estelle; Hogg, Claire; Amselem, Serge; Sun, Zhaoxia; Bartoloni, Lucia; Blouin, Jean-Louis; Mitchison, Hannah M

    2017-02-08

    By moving essential body fluids and molecules, motile cilia and flagella govern respiratory mucociliary clearance, laterality determination and the transport of gametes and cerebrospinal fluid. Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder frequently caused by non-assembly of dynein arm motors into cilia and flagella axonemes. Before their import into cilia and flagella, multi-subunit axonemal dynein arms are thought to be stabilized and pre-assembled in the cytoplasm through a DNAAF2-DNAAF4-HSP90 complex akin to the HSP90 co-chaperone R2TP complex. Here, we demonstrate that large genomic deletions as well as point mutations involving PIH1D3 are responsible for an X-linked form of PCD causing disruption of early axonemal dynein assembly. We propose that PIH1D3, a protein that emerges as a new player of the cytoplasmic pre-assembly pathway, is part of a complementary conserved R2TP-like HSP90 co-chaperone complex, the loss of which affects assembly of a subset of inner arm dyneins.

  14. X-linked primary ciliary dyskinesia due to mutations in the cytoplasmic axonemal dynein assembly factor PIH1D3

    PubMed Central

    Olcese, Chiara; Patel, Mitali P.; Shoemark, Amelia; Kiviluoto, Santeri; Legendre, Marie; Williams, Hywel J.; Vaughan, Cara K.; Hayward, Jane; Goldenberg, Alice; Emes, Richard D.; Munye, Mustafa M.; Dyer, Laura; Cahill, Thomas; Bevillard, Jeremy; Gehrig, Corinne; Guipponi, Michel; Chantot, Sandra; Duquesnoy, Philippe; Thomas, Lucie; Jeanson, Ludovic; Copin, Bruno; Tamalet, Aline; Thauvin-Robinet, Christel; Papon, Jean- François; Garin, Antoine; Pin, Isabelle; Vera, Gabriella; Aurora, Paul; Fassad, Mahmoud R.; Jenkins, Lucy; Boustred, Christopher; Cullup, Thomas; Dixon, Mellisa; Onoufriadis, Alexandros; Bush, Andrew; Chung, Eddie M. K.; Antonarakis, Stylianos E.; Loebinger, Michael R.; Wilson, Robert; Armengot, Miguel; Escudier, Estelle; Hogg, Claire; Al-Turki, Saeed; Anderson, Carl; Antony, Dinu; Barroso, Inês; Beales, Philip L.; Bentham, Jamie; Bhattacharya, Shoumo; Carss, Keren; Chatterjee, Krishna; Cirak, Sebahattin; Cosgrove, Catherine; Allan, Daly; Durbin, Richard; Fitzpatrick, David; Floyd, Jamie; Foley, A. Reghan; Franklin, Chris; Futema, Marta; Humphries, Steve E.; Hurles, Matt; McCarthy, Shane; Muddyman, Dawn; Muntoni, Francesco; Parker, Victoria; Payne, Felicity; Plagnol, Vincent; Raymond, Lucy; Savage, David B.; Scambler, Peter J.; Schmidts, Miriam; Semple, Robert; Serra, Eva; Stalker, Jim; van Kogelenberg, Margriet; Vijayarangakannan, Parthiban; Walter, Klaudia; Amselem, Serge; Sun, Zhaoxia; Bartoloni, Lucia; Blouin, Jean-Louis; Mitchison, Hannah M.

    2017-01-01

    By moving essential body fluids and molecules, motile cilia and flagella govern respiratory mucociliary clearance, laterality determination and the transport of gametes and cerebrospinal fluid. Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder frequently caused by non-assembly of dynein arm motors into cilia and flagella axonemes. Before their import into cilia and flagella, multi-subunit axonemal dynein arms are thought to be stabilized and pre-assembled in the cytoplasm through a DNAAF2–DNAAF4–HSP90 complex akin to the HSP90 co-chaperone R2TP complex. Here, we demonstrate that large genomic deletions as well as point mutations involving PIH1D3 are responsible for an X-linked form of PCD causing disruption of early axonemal dynein assembly. We propose that PIH1D3, a protein that emerges as a new player of the cytoplasmic pre-assembly pathway, is part of a complementary conserved R2TP-like HSP90 co-chaperone complex, the loss of which affects assembly of a subset of inner arm dyneins. PMID:28176794

  15. Ciliobrevins as tools for studying dynein motor function

    PubMed Central

    Roossien, Douglas H.; Miller, Kyle E.; Gallo, Gianluca

    2015-01-01

    Dyneins are a small class of molecular motors that bind to microtubules and walk toward their minus ends. They are essential for the transport and distribution of organelles, signaling complexes and cytoskeletal elements. In addition dyneins generate forces on microtubule arrays that power the beating of cilia and flagella, cell division, migration and growth cone motility. Classical approaches to the study of dynein function in axons involve the depletion of dynein, expression of mutant/truncated forms of the motor, or interference with accessory subunits. By necessity, these approaches require prolonged time periods for the expression or manipulation of cellular dynein levels. With the discovery of the ciliobrevins, a class of cell permeable small molecule inhibitors of dynein, it is now possible to acutely disrupt dynein both globally and locally. In this review, we briefly summarize recent work using ciliobrevins to inhibit dynein and discuss the insights ciliobrevins have provided about dynein function in various cell types with a focus on neurons. We temper this with a discussion of the need for studies that will elucidate the mechanism of action of ciliobrevin and as well as the need for experiments to further analyze the specificity of ciliobreviens for dynein. Although much remains to be learned about ciliobrevins, these small molecules are proving themselves to be valuable novel tools to assess the cellular functions of dynein. PMID:26217180

  16. Interaction of SQSTM1 with the motor protein dynein--SQSTM1 is required for normal dynein function and trafficking.

    PubMed

    Calderilla-Barbosa, Luis; Seibenhener, M Lamar; Du, Yifeng; Diaz-Meco, Maria-Theresa; Moscat, Jorge; Yan, Jin; Wooten, Marie W; Wooten, Michael C

    2014-09-15

    The dynein motor protein complex is required for retrograde transport of vesicular cargo and for transport of aggregated proteins along microtubules for processing and degradation at perinuclear aggresomes. Disruption of this process leads to dysfunctional endosome accumulation and increased protein aggregation in the cell cytoplasm, both pathological features of neurodegenerative diseases. However, the exact mechanism of dynein functionality in these pathways is still being elucidated. Here, we show that the scaffolding protein SQSTM1 directly interacts with dynein through a previously unidentified dynein-binding site. This interaction is independent of HDAC6, a known interacting protein of both SQSTM1 and dynein. However, knockdown of HDAC6 increases the interaction of SQSTM1 with dynein, indicating a possible competitive interaction. Using different dynein cargoes, we show that SQSTM1 is required for proper dynein motility and trafficking along microtubules. Based on our results, we propose a new model of competitive interaction between SQSTM1 and HDAC6 with dynein. In this model, SQSTM1 would not only affect the association of polyubiquitylated protein aggregates and endosomes with dynein, but would also be required for normal dynein function.

  17. Single cytoplasmic dynein molecule movements: characterization and comparison with kinesin.

    PubMed Central

    Wang, Z; Khan, S; Sheetz, M P

    1995-01-01

    Cytoplasmic dynein is a major microtubule motor for minus-end directed movements including retrograde axonal transport. To better understand the mechanism by which cytoplasmic dynein converts ATP energy into motility, we have analyzed the nanometer-level displacements of latex beads coated with low numbers of cytoplasmic dynein molecules. Cytoplasmic dynein-coated beads exhibited greater lateral movements among microtubule protofilaments (ave. 5.1 times/microns of displacement) compared with kinesin (ave. 0.9 times/micron). In addition, dynein moved rearward up to 100 nm over several hundred milliseconds, often in correlation with off-axis movements from one protofilament to another. We suggest that single molecules of cytoplasmic dynein move the beads because 1) there is a linear dependence of bead motility on dynein/bead ratio, 2) the binding of beads to microtubules studied by laser tweezers is best fit by a first-order Poisson, and 3) the run length histogram of dynein beads follows a first-order decay. At the cellular level, the greater disorder of cytoplasmic dynein movements may facilitate transport by decreasing the duration of collisions between kinesin and cytoplasmic dynein-powered vesicles. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 6 FIGURE 9 PMID:8580344

  18. Regulation of Cytoplasmic Dynein ATPase by Lis1

    PubMed Central

    Mesngon, Mariano T.; Tarricone, Cataldo; Hebbar, Sachin; Guillotte, Aimee M.; Schmitt, E. William; Lanier, Lorene; Musacchio, Andrea; King, Stephen J.; Smith, Deanna S.

    2015-01-01

    Mutations in Lis1 cause classical lissencephaly, a developmental brain abnormality characterized by defects in neuronal positioning. Over the last decade, a clear link has been forged between Lis1 and the microtubule motor cytoplasmic dynein. Substantial evidence indicates that Lis1 functions in a highly conserved pathway with dynein to regulate neuronal migration and other motile events. Yeast two-hybrid studies predict that Lis1 binds directly to dynein heavy chains (Sasaki et al., 2000; Tai et al., 2002), but the mechanistic significance of this interaction is not well understood. We now report that recombinant Lis1 binds to native brain dynein and significantly increases the microtubule-stimulated enzymatic activity of dynein in vitro. Lis1 does this without increasing the proportion of dynein that binds to microtubules, indicating that Lis1 influences enzymatic activity rather than microtubule association. Dynein stimulation in vitro is not a generic feature of microtubule-associated proteins, because tau did not stimulate dynein. To our knowledge, this is the first indication that Lis1 or any other factor directly modulates the enzymatic activity of cytoplasmic dynein. Lis1 must be able to homodimerize to stimulate dynein, because a C-terminal fragment (containing the dynein interaction site but missing the self-association domain) was unable to stimulate dynein. Binding and colocalization studies indicate that Lis1 does not interact with all dynein complexes found in the brain. We propose a model in which Lis1 stimulates the activity of a subset of motors, which could be particularly important during neuronal migration and long-distance axonal transport. PMID:16481446

  19. The dynein cortical anchor Num1 activates dynein motility by relieving Pac1/LIS1-mediated inhibition

    PubMed Central

    Lammers, Lindsay G.

    2015-01-01

    Cortically anchored dynein orients the spindle through interactions with astral microtubules. In budding yeast, dynein is offloaded to Num1 receptors from microtubule plus ends. Rather than walking toward minus ends, dynein remains associated with plus ends due in part to its association with Pac1/LIS1, an inhibitor of dynein motility. The mechanism by which dynein is switched from “off” at the plus ends to “on” at the cell cortex remains unknown. Here, we show that overexpression of the coiled-coil domain of Num1 specifically depletes dynein–dynactin–Pac1/LIS1 complexes from microtubule plus ends and reduces dynein-Pac1/LIS1 colocalization. Depletion of dynein from plus ends requires its microtubule-binding domain, suggesting that motility is required. An enhanced Pac1/LIS1 affinity mutant of dynein or overexpression of Pac1/LIS1 rescues dynein plus end depletion. Live-cell imaging reveals minus end–directed dynein–dynactin motility along microtubules upon overexpression of the coiled-coil domain of Num1, an event that is not observed in wild-type cells. Our findings indicate that dynein activity is directly switched “on” by Num1, which induces Pac1/LIS1 removal. PMID:26483554

  20. Coordination of outer arm dynein activity along axonemal doublet microtubules.

    PubMed

    Seetharam, Raviraja N; Satir, Peter

    2008-07-01

    This study considers the mechanism by which ODA based sliding is produced and the relationship of that mechanism to the determination of beat frequency. Two models of activity have been examined: a stochastic model, where ODA activity is random and a metachronal model, where activity is sequentially triggered along a doublet. Inactivation of a few ODAs would have virtually no effect on stochastic activity, but would completely block metachronal activity. We (Seetharam and Satir [2005]: Cell Motil Cytoskeleton 60:96-103) previously demonstrated that ODAs produce high speed sliding of about 200 mum/s, followed by a pause. IDAs produce slow, 5 mum/s, continuous sliding. We have examined the effects of nM concentrations of vanadate on sliding, measuring velocity and extent of high speed sliding and pause distribution or sliding cessation. In 5 nM vanadate, where photocleavage experiments show about 16/270 ODAs per doublet are affected, no differences from control are seen, but at 10 and 25 nM vanadate, high speed velocity is greatly reduced and pause distribution changes. The results support a model, in which high speed sliding is produced by metachronal activity. Blockage of two or more heavy chains of one ODA or a small group of adjacent ODAs produces cessation of sliding, but cessation is only temporary, probably because IDA activity continues, allowing ODA activity re-initiation beyond the block. These conclusions are consistent with Sugino and Naitoh's [1982; Nature 295:609-611] proposal, whereby during each beat, every ODA along a doublet becomes activated in succession, with repetitive activation determining beat frequency.

  1. Cytoplasmic dynein: a key player in neurodegenerative and neurodevelopmental diseases.

    PubMed

    Chen, Xiang-Jun; Xu, Huan; Cooper, Helen M; Liu, Yaobo

    2014-04-01

    Cytoplasmic dynein is the most important molecular motor driving the movement of a wide range of cargoes towards the minus ends of microtubules. As a molecular motor protein, dynein performs a variety of basic cellular functions including organelle transport and centrosome assembly. In the nervous system, dynein has been demonstrated to be responsible for axonal retrograde transport. Many studies have revealed direct or indirect evidence of dynein in neurodegenerative diseases such as amyotrophic lateral sclerosis, Charcot-Marie-Tooth disease, Alzheimer's disease, Parkinson's disease and Huntington's disease. Among them, a number of mutant proteins involved in various neurodegenerative diseases interact with dynein. Axonal transport disruption is presented as a common feature occurring in neurodegenerative diseases. Dynein heavy chain mutant mice also show features of neurodegenerative diseases. Moreover, defects of dynein-dependent processes such as autophagy or clearance of aggregation-prone proteins are found in most of these diseases. Lines of evidence have also shown that dynein is associated with neurodevelopmental diseases. In this review, we focus on dynein involvement in different neurological diseases and discuss potential underlying mechanisms.

  2. Structure of the microtubule-binding domain of flagellar dynein.

    PubMed

    Kato, Yusuke S; Yagi, Toshiki; Harris, Sarah A; Ohki, Shin-ya; Yura, Kei; Shimizu, Youské; Honda, Shinya; Kamiya, Ritsu; Burgess, Stan A; Tanokura, Masaru

    2014-11-04

    Flagellar dyneins are essential microtubule motors in eukaryotes, as they drive the beating motions of cilia and flagella. Unlike myosin and kinesin motors, the track binding mechanism of dyneins and the regulation between the strong and weak binding states remain obscure. Here we report the solution structure of the microtubule-binding domain of flagellar dynein-c/DHC9 (dynein-c MTBD). The structure reveals a similar overall helix-rich fold to that of the MTBD of cytoplasmic dynein (cytoplasmic MTBD), but dynein-c MTBD has an additional flap, consisting of an antiparallel b sheet. The flap is positively charged and highly flexible. Despite the structural similarity to cytoplasmic MTBD, dynein-c MTBD shows only a small change in the microtubule- binding affinity depending on the registry change of coiled coil-sliding, whereby lacks the apparent strong binding state. The surface charge distribution of dynein-c MTBD also differs from that of cytoplasmic MTBD, which suggests a difference in the microtubule-binding mechanism.

  3. Vanadate-sensitized cleavage of dynein heavy chains by 365-nm irradiation of demembranated sperm flagella and its effect on the flagellar motility

    SciTech Connect

    Gibbons, B.H.; Gibbons, I.R.

    1987-06-15

    Irradiation of demembranated flagella of sea urchin sperm at 365 nm in the presence of 0.05-1 mM MgATP and 5-10 microM vanadate (Vi) cleaves the alpha and beta heavy chains of the outer arm dynein at the same site and at about the same rate as reported previously for the solubilized dynein. The decrease in intact alpha and beta heavy chain material is biphasic, with about 80% being lost with a half-time of 8-10 min, and the remainder more slowly. Five other axonemal polypeptides of Mr greater than 350,000 are lost similarly, concomitant with the appearance of at least 9 new peptides of Mr 150,000-250,000. The motility of irradiated sperm flagella upon subsequent dilution into reactivation medium containing 1 mM ATP and 2.5 mM catechol shows a progressive decrease in flagellar beat frequency for irradiation times that produce up to about 50% cleavage of the dynein heavy chains; more prolonged irradiation causes irreversible loss of motility. Competition between photocleaved and intact outer arm dynein for rebinding to dynein-depleted sperm flagella shows that cleavage has little effect upon the ability for rebinding, although the cleaved dynein partially inhibits subsequent motility. Substitution of MnATP for the MgATP in the irradiation medium prevents the loss of all of the axonemal polypeptides during irradiation for up to 60 min and also protects the potential for subsequent flagellar motility.

  4. Quantitative Analysis of Pac1/LIS1-mediated Dynein Targeting: Implications for Regulation of Dynein Activity in Budding Yeast

    PubMed Central

    Markus, Steven M.; Plevock, Karen M.; St. Germain, Bryan J.; Punch, Jesse J.; Meaden, Christopher W.; Lee, Wei-Lih

    2011-01-01

    LIS1 is a critical regulator of dynein function during mitosis and organelle transport. Here, we investigated how Pac1, the budding yeast LIS1 homologue, regulates dynein targeting and activity during nuclear migration. We show that Pac1 and Dyn1 (dynein heavy chain) are dependent upon each other and upon Bik1 (budding yeast CLIP-170 homologue) for plus end localization, whereas Bik1 is independent of either. Dyn1, Pac1 and Bik1 interact in vivo at the plus ends, where an excess amount of Bik1 recruits approximately equal amounts of Pac1 and Dyn1. Overexpression of Pac1 enhanced plus end targeting of Dyn1 and vice versa, while affinity-purification of Dyn1 revealed that it exists in a complex with Pac1 in the absence of Bik1, leading us to conclude that the Pac1-Dyn1 complex preassembles in the cytoplasm prior to loading onto Bik1-decorated plus ends. Strikingly, we found that Pac1-overexpression augments cortical dynein activity through a mechanism distinct from loss of She1, a negative regulator of dynein-dynactin association. While Pac1-overexpression enhances the frequency of cortical targeting for dynein and dynactin, the stoichiometry of these complexes remains relatively unchanged at the plus ends compared to that in wild-type cells (~3 dynein to 1 dynactin). Loss of She1, however, enhances dynein-dynactin association at the plus ends and the cell cortex, resulting in an apparent 1:1 stoichiometry. Our results reveal differential regulation of cortical dynein activity by She1 and Pac1, and provide a potentially new regulatory step in the off-loading model for dynein function. PMID:21294277

  5. Structure of human cytoplasmic dynein-2 primed for its powerstroke

    PubMed Central

    Urnavicius, Linas; Carter, Andrew P.

    2014-01-01

    Members of the dynein family, consisting of cytoplasmic and axonemal isoforms, are motors that move towards the minus ends of microtubules. Cytoplasmic dynein-1 (dynein-1) plays roles in mitosis and cellular cargo transport1, and is implicated in viral infections2 and neurodegenerative diseases3. Cytoplasmic dynein-2 (dynein-2) carries out intraflagellar transport4 and is associated with human skeletal ciliopathies5. Dyneins share a conserved motor domain that couples cycles of ATP hydrolysis with conformational changes to produce movement6-9. Here we present the crystal structure of the human cytoplasmic dynein-2 motor bound to the ATP-hydrolysis transition state analogue ADP.vanadate (ADP.Vi)10. The structure reveals a closure of the motor’s ring of six AAA+ domains (ATPases associated with various cellular activites: AAA1-AAA6). This induces a steric clash with the linker, the key element for the generation of movement, driving it into a conformation that is primed to produce force. Ring closure also changes the interface between the stalk and buttress coiled-coil extensions of the motor domain. This drives helix sliding in the stalk that causes the microtubule binding domain (MTBD) at its tip to release from the microtubule. Our structure answers the key questions of how ATP hydrolysis leads to linker remodelling and microtubule affinity regulation. PMID:25470043

  6. Functional Asymmetry in Kinesin and Dynein Dimers

    PubMed Central

    Rank, Katherine C.; Rayment, Ivan

    2012-01-01

    Active transport along the microtubule lattice is a complex process that involves both the Kinesin and Dynein superfamily of motors. Transportation requires sophisticated regulation much of which occurs through the motor’s tail domain. However, a significant portion of this regulation also occurs through structural changes that arise in the motor and the microtubule upon binding. The most obvious structural change being the manifestation of asymmetry. To a first approximation in solution, kinesin dimers exhibit two-fold symmetry, and microtubules, helical symmetry. The higher symmetries of both the kinesin dimers and microtubule lattice are lost on formation of the kinesin-microtubule complex. Loss of symmetry has functional consequences such as an asymmetric hand-over-hand mechanism in plus-end directed kinesins, asymmetric microtubule binding in the Kinesin-14 family, spatially biased stepping in dynein, and cooperative binding of additional motors to the microtubule. This review focuses on how the consequences of asymmetry affect regulation of motor heads within a dimer, dimers within an ensemble of motors, and suggests how these asymmetries may affect regulation of active transport within the cell. PMID:23066835

  7. Cytoplasmic dynein is associated with slow axonal transport.

    PubMed Central

    Dillman, J F; Dabney, L P; Pfister, K K

    1996-01-01

    Neuronal function is dependent on the transport of materials from the cell body to the synapse via anterograde axonal transport. Anterograde axonal transport consists of several components that differ in both rate and protein composition. In fast transport, membranous organelles are moved along microtubules by the motor protein kinesin. The cytoskeleton and the cytomatrix proteins move in the two components of slow transport. While the mechanisms underlying slow transport are unknown, it has been hypothesized that the movement of microtubules in slow transport is generated by sliding. To determine whether dynein, a motor protein that causes microtubule sliding in flagella, may play a role in slow axonal transport, we identified the transport rate components with which cytoplasmic dynein is associated in rat optic nerve. Nearly 80% of the anterogradely moving dynein was associated with slow transport, whereas only approximately 15% of the dynein was associated with the membranous organelles of anterograde fast axonal transport. A segmental analysis of the transport of dynein through contiguous regions of the optic nerve and tract showed that dynein is associated with the microfilaments and other proteins of slow component b. Dynein from this transport component has the capacity to bind microtubules in vitro. These results are consistent with the hypothesis that cytoplasmic dynein generates the movement of microtubules in slow axonal transport. A model is presented to illustrate how dynein attached to the slow component b complex of proteins is appropriately positioned to generate force of the correct polarity to slide microtubules down the axon. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8552592

  8. A monoclonal antibody against the dynein IC1 peptide of sea urchin spermatozoa inhibits the motility of sea urchin, dinoflagellate, and human flagellar axonemes.

    PubMed Central

    Gagnon, C; White, D; Huitorel, P; Cosson, J

    1994-01-01

    To investigate the role of axonemal components in the mechanics and regulation of flagellar movement, we have generated a series of monoclonal antibodies (mAb) against sea urchin (Lytechinus pictus) sperm axonemal proteins, selected for their ability to inhibit the motility of demembranated sperm models. One of these antibodies, mAb D1, recognizes an antigen of 142 kDa on blots of sea urchin axonemal proteins and of purified outer arm dynein, suggesting that it acts by binding to the heaviest intermediate chain (IC1) of the dynein arm. mAb D1 blocks the motility of demembranated sea urchin spermatozoa by modifying the beating amplitude and shear angle without affecting the ATPase activity of purified dynein or of demembranated immotile spermatozoa. Furthermore, mAb D1 had only a marginal effect on the velocity of sliding microtubules in trypsin-treated axonemes. This antibody was also capable of inhibiting the motility of flagella of Oxyrrhis marina, a primitive dinoflagellate, and those of demembranated human spermatozoa. Localization of the antigen recognized by mAb D1 by immunofluorescence reveals its presence on the axonemes of flagella from sea urchin spermatozoa and O. marina but not on the cortical microtubule network of the dinoflagellate. These results are consistent with a dynamic role for the dynein intermediate chain IC1 in the bending and/or wave propagation of flagellar axonemes. Images PMID:7841521

  9. Absent or occult pulmonary artery.

    PubMed Central

    Presbitero, P; Bull, C; Haworth, S G; de Leval, M R

    1984-01-01

    Of 12 patients with angiographically absent pulmonary artery, 11 were investigated surgically. The previously occult pulmonary artery was found in 10 patients, in five of whom a vestige of an intrapericardial artery was present and in five the artery was patent only at the hilus, a gap existing between the main pulmonary artery and the hilar vessel, and no artery was found in one. All patients with an intrapericardial artery had right ventricular outflow tract obstruction and a ductus descending vertically from underneath the aortic arch. In those without an intrapericardial vessel the occult artery was on the side opposite the aortic arch, and there was evidence of a ductus coming from the innominate artery on the side of the interruption. The occult pulmonary artery, where identified at operation, was usually joined initially to the systemic circulation. Ultimately, continuity between the hilar and main pulmonary artery may be established surgically. Where no intrapericardial vessel exists, however, a conduit may be required to bridge the gap. It seems advisable to search for the occult artery as early in life as is feasible in the hope that providing a blood supply will ensure development of the vessel and normal lung growth. Images PMID:6743435

  10. Structure-function analysis of dynein light chain 1 identifies viable motility mutants in bloodstream-form Trypanosoma brucei.

    PubMed

    Ralston, Katherine S; Kisalu, Neville K; Hill, Kent L

    2011-07-01

    The flagellum of Trypanosoma brucei is an essential and multifunctional organelle that is receiving increasing attention as a potential drug target and as a system for studying flagellum biology. RNA interference (RNAi) knockdown is widely used to test the requirement for a protein in flagellar motility and has suggested that normal flagellar motility is essential for viability in bloodstream-form trypanosomes. However, RNAi knockdown alone provides limited functional information because the consequence is often loss of a multiprotein complex. We therefore developed an inducible system that allows functional analysis of point mutations in flagellar proteins in T. brucei. Using this system, we identified point mutations in the outer dynein light chain 1 (LC1) that allow stable assembly of outer dynein motors but do not support propulsive motility. In procyclic-form trypanosomes, the phenotype of LC1 mutants with point mutations differs from the motility and structural defects of LC1 knockdowns, which lack the outer-arm dynein motor. Thus, our results distinguish LC1-specific functions from broader functions of outer-arm dynein. In bloodstream-form trypanosomes, LC1 knockdown blocks cell division and is lethal. In contrast, LC1 point mutations cause severe motility defects without affecting viability, indicating that the lethal phenotype of LC1 RNAi knockdown is not due to defective motility. Our results demonstrate for the first time that normal motility is not essential in bloodstream-form T. brucei and that the presumed connection between motility and viability is more complex than might be interpreted from knockdown studies alone. These findings open new avenues for dissecting mechanisms of flagellar protein function and provide an important step in efforts to exploit the potential of the flagellum as a therapeutic target in African sleeping sickness.

  11. Subunit Heterogeneity of Cytoplasmic Dynein: Differential Expression of 14 kDa Dynein Light Chains in Rat Hippocampus

    PubMed Central

    Chuang, Jen-Zen; Milner, Teresa A.; Sung, Ching-Hwa

    2013-01-01

    Cytoplasmic dynein is a multi-subunit protein complex in which each subunit is encoded by a few genes. How these subunit isoforms are assembled and regulated to mediate the diverse functions of cytoplasmic dynein is unknown. We previously have shown that two highly conserved 14 kDa dynein light chains, Tctex-1 and RP3, have different cargo-binding abilities. In this report, coimmunoprecipitation revealed that Tctex-1 and RP3 were present in mutually exclusive dynein complexes of brain. Two specific antibodies were used to examine the localization of these two dynein light chains in adult rat hippocampal formation and cerebral cortex. By light microscopy, Tctex-1 and RP3 immunoreactivities exhibited distinct and almost complementary distribution patterns in both brain regions. In hippocampal formation, Tctex-1 immunoreactivity was most enriched in somata of newly generated granule cells and scant in the mature granule and pyramidal cell somata. In contrast, RP3 immunoreactivity was abundant in pyramidal and granule cell somata. Ultrastructural analysis of the dentate gyrus revealed both dynein light chains were associated with various membranous organelles that often were affiliated with microtubules. In addition, Tctex-1 and RP3 immunoreactivities were preferentially and highly enriched on membranous organelles and/or vesicles of axon terminals and dendritic spines, respectively. These results suggest that dynein complexes with different subunit composition, and possibly function, are expressed differentially in a spatially and temporally regulated manner. Furthermore, Tctex-1 and RP3 may play important roles in synaptic functions. PMID:11466421

  12. Dynein Transmits Polarized Actomyosin Cortical Flows to Promote Centrosome Separation.

    PubMed

    De Simone, Alessandro; Nédélec, François; Gönczy, Pierre

    2016-03-08

    The two centrosomes present at the onset of mitosis must separate in a timely and accurate fashion to ensure proper bipolar spindle assembly. The minus-end-directed motor dynein plays a pivotal role in centrosome separation, but the underlying mechanisms remain elusive, particularly regarding how dynein coordinates this process in space and time. We addressed these questions in the one-cell C. elegans embryo, using a combination of 3D time-lapse microscopy and computational modeling. Our analysis reveals that centrosome separation is powered by the joint action of dynein at the nuclear envelope and at the cell cortex. Strikingly, we demonstrate that dynein at the cell cortex acts as a force-transmitting device that harnesses polarized actomyosin cortical flows initiated by the centrosomes earlier in the cell cycle. This mechanism elegantly couples cell polarization with centrosome separation, thus ensuring faithful cell division.

  13. Molecular mechanism of motion and force generation by cytoplasmic dynein

    NASA Astrophysics Data System (ADS)

    Gennerich, Arne

    2013-03-01

    Cytoplasmic dynein is an intricate microtubule (MT) motor with four AAA (ATPase associated with various cellular activities) ATPases per head domain. Dynein homodimers take hundreds of consecutive steps, during which the leading and trailing heads experience intramolecular tension in opposite directions. We hypothesize that this asymmetry may differentially regulate the MT-binding and ATPase functions in each head, thereby facilitating processive movement. Here, we elucidate the function of tension in regulating dynein-MT interactions, and dissect the roles of its multiple AAA subunits in effecting and modulating this behavior. Using optical tweezers to measure unbinding forces of single S. cerevisiae dynein heads in the absence of nucleotide, we show that intrinsic dynein-MT binding is significantly weaker under forward (MT-minus-end directed) tension than under rearward tension. Thus, forward tension likely promotes rear head detachment in the dimeric motor. The nucleotide states of specific AAA sites modify this intrinsic behavior. Mutational analysis shows that ATP binding to AAA1 substantially weakens MT binding. Moreover, ADP binding to AAA3 `locks' dynein in a previously undescribed, weak MT-binding state with a relatively symmetric response to tension. Interestingly, tension also affects nucleotide affinity: ADP affinity is lower under rearward than under forward load, suggesting that the front head preferentially releases ADP (likely from AAA3), perhaps driving a transition from an ADP state with relatively weak MT attachment to a strongly MT-attached, nucleotide-free state. Our analysis suggests that intramolecular tension is key to dynein motility, and highlights the importance of including multiple AAA ATPases in models for dynein mechanochemistry. NIH R01GM098469

  14. A neuron-specific cytoplasmic dynein isoform preferentially transports TrkB signaling endosomes

    PubMed Central

    Ha, Junghoon; Lo, Kevin W.-H.; Myers, Kenneth R.; Carr, Tiffany M.; Humsi, Michael K.; Rasoul, Bareza A.; Segal, Rosalind A.; Pfister, K. Kevin

    2008-01-01

    Cytoplasmic dynein is the multisubunit motor protein for retrograde movement of diverse cargoes to microtubule minus ends. Here, we investigate the function of dynein variants, defined by different intermediate chain (IC) isoforms, by expressing fluorescent ICs in neuronal cells. Green fluorescent protein (GFP)–IC incorporates into functional dynein complexes that copurify with membranous organelles. In living PC12 cell neurites, GFP–dynein puncta travel in both the anterograde and retrograde directions. In cultured hippocampal neurons, neurotrophin receptor tyrosine kinase B (TrkB) signaling endosomes are transported by cytoplasmic dynein containing the neuron-specific IC-1B isoform and not by dynein containing the ubiquitous IC-2C isoform. Similarly, organelles containing TrkB isolated from brain by immunoaffinity purification also contain dynein with IC-1 but not IC-2 isoforms. These data demonstrate that the IC isoforms define dynein populations that are selectively recruited to transport distinct cargoes. PMID:18559670

  15. Analysis of the Dynein-Dynactin Interaction In Vitro and In Vivo

    PubMed Central

    King, Stephen J.; Brown, Christa L.; Maier, Kerstin C.; Quintyne, Nicholas J.; Schroer, Trina A.

    2003-01-01

    Cytoplasmic dynein and dynactin are megadalton-sized multisubunit molecules that function together as a cytoskeletal motor. In the present study, we explore the mechanism of dynein-dynactin binding in vitro and then extend our findings to an in vivo context. Solution binding assays were used to define binding domains in the dynein intermediate chain (IC) and dynactin p150Glued subunit. Transient overexpression of a series of fragments of the dynein IC was used to determine the importance of this subunit for dynein function in mammalian tissue culture cells. Our results suggest that a functional dynein-dynactin interaction is required for proper microtubule organization and for the transport and localization of centrosomal components and endomembrane compartments. The dynein IC fragments have different effects on endomembrane localization, suggesting that different endomembranes may bind dynein via distinct mechanisms. PMID:14565986

  16. Polo-like kinase1 is required for recruitment of dynein to kinetochores during mitosis.

    PubMed

    Bader, Jason R; Kasuboski, James M; Winding, Michael; Vaughan, Patricia S; Hinchcliffe, Edward H; Vaughan, Kevin T

    2011-06-10

    Kinetochore dynein has been implicated in microtubule capture, correcting inappropriate microtubule attachments, chromosome movement, and checkpoint silencing. It remains unclear how dynein coordinates this diverse set of functions. Phosphorylation is responsible for some dynein heterogeneity (Whyte, J., Bader, J. R., Tauhata, S. B., Raycroft, M., Hornick, J., Pfister, K. K., Lane, W. S., Chan, G. K., Hinchcliffe, E. H., Vaughan, P. S., and Vaughan, K. T. (2008) J. Cell Biol. 183, 819-834), and phosphorylated and dephosphorylated forms of dynein coexist at prometaphase kinetochores. In this study, we measured the impact of inhibiting polo-like kinase 1 (Plk1) on both dynein populations. Phosphorylated dynein was ablated at kinetochores after inhibiting Plk1 with a small molecule inhibitor (5-Cyano-7-nitro-2-(benzothiazolo-N-oxide)-carboxamide) or chemical genetic approaches. The total complement of kinetochore dynein was also reduced but not eliminated, reflecting the presence of some dephosphorylated dynein after Plk1 inhibition. Although Plk1 inhibition had a profound effect on dynein, kinetochore populations of dynactin, spindly, and zw10 were not reduced. Plk1-independent dynein was reduced after p150(Glued) depletion, consistent with the binding of dephosphorylated dynein to dynactin. Plk1 phosphorylated dynein intermediate chains at Thr-89 in vitro and generated the phospho-Thr-89 phospho-epitope on recombinant dynein intermediate chains. Finally, inhibition of Plk1 induced defects in microtubule capture and persistent microtubule attachment, suggesting a role for phosphorylated dynein in these functions during prometaphase. These findings suggest that Plk1 is a dynein kinase required for recruitment of phosphorylated dynein to kinetochores.

  17. Dendrite arborization requires the dynein cofactor NudE.

    PubMed

    Arthur, Ashley L; Yang, Sihui Z; Abellaneda, Allison M; Wildonger, Jill

    2015-06-01

    The microtubule-based molecular motor dynein is essential for proper neuronal morphogenesis. Dynein activity is regulated by cofactors, and the role(s) of these cofactors in shaping neuronal structure are still being elucidated. Using Drosophila melanogaster, we reveal that the loss of the dynein cofactor NudE results in abnormal dendrite arborization. Our data show that NudE associates with Golgi outposts, which mediate dendrite branching, suggesting that NudE normally influences dendrite patterning by regulating Golgi outpost transport. Neurons lacking NudE also have increased microtubule dynamics, reflecting a change in microtubule stability that is likely to also contribute to abnormal dendrite growth and branching. These defects in dendritogenesis are rescued by elevating levels of Lis1, another dynein cofactor that interacts with NudE as part of a tripartite complex. Our data further show that the NudE C-terminus is dispensable for dendrite morphogenesis and is likely to modulate NudE activity. We propose that a key function of NudE is to enhance an interaction between Lis1 and dynein that is crucial for motor activity and dendrite architecture.

  18. Dynein-mediated trafficking negatively regulates LET-23 EGFR signaling

    PubMed Central

    Skorobogata, Olga; Meng, Jassy; Gauthier, Kimberley; Rocheleau, Christian E.

    2016-01-01

    Epidermal growth factor receptor (EGFR) signaling is essential for animal development, and increased signaling underlies many human cancers. Identifying the genes and cellular processes that regulate EGFR signaling in vivo will help to elucidate how this pathway can become inappropriately activated. Caenorhabditis elegans vulva development provides an in vivo model to genetically dissect EGFR signaling. Here we identified a mutation in dhc-1, the heavy chain of the cytoplasmic dynein minus end–directed microtubule motor, in a genetic screen for regulators of EGFR signaling. Despite the many cellular functions of dynein, DHC-1 is a strong negative regulator of EGFR signaling during vulva induction. DHC-1 is required in the signal-receiving cell and genetically functions upstream or in parallel to LET-23 EGFR. LET-23 EGFR accumulates in cytoplasmic foci in dhc-1 mutants, consistent with mammalian cell studies in which dynein is shown to regulate late endosome trafficking of EGFR with the Rab7 GTPase. However, we found different distributions of LET-23 EGFR foci in rab-7 versus dhc-1 mutants, suggesting that dynein functions at an earlier step of LET-23 EGFR trafficking to the lysosome than RAB-7. Our results demonstrate an in vivo role for dynein in limiting LET-23 EGFR signaling via endosomal trafficking. PMID:27654944

  19. Disruption of the murine dynein light chain gene Tcte3-3 results in asthenozoospermia.

    PubMed

    Rashid, Sajid; Grzmil, Pawel; Drenckhahn, Joerg-Detlef; Meinhardt, Andreas; Adham, Ibrahim; Engel, Wolfgang; Neesen, Juergen

    2010-01-01

    To elucidate the role of the mouse gene Tcte3 (Tctex2), which encodes a putative light chain of the outer dynein arm of cilia and sperm flagella, we have inactivated this gene in mice using targeted disruption. Breeding of heterozygous males and females resulted in normal litter size; however, we were not able to detect homozygous Tcte3-deficent mice using standard genotype techniques. In fact, our results indicate the presence of at least three highly similar copies of the Tcte3 gene (Tcte3-1, Tcte3-2, and Tcte3-3) in the murine genome. Therefore, quantitative real-time PCR was established to differentiate between mice having one or two targeted Tcte3-3 alleles. By this approach, Tcte3-3(-/-) animals were identified, which were viable and revealed no obvious malformation. Interestingly, some homozygous Tcte3-3-deficient male mice bred with wild-type female produced no offspring while other Tcte3-3-deficient males revealed decreased sperm motility but were fertile. In infertile Tcte3-3(-/-) males, spermatogenesis was affected and sperm motility was reduced, too, resulting in decreased ability of Tcte3-3-deficient spermatozoa to move from the uterus into the oviduct. Impaired flagellar motility is not correlated with any gross defects in the axonemal structure, since outer dynein arms are detectable in sperm of Tcte3-3(-/-) males. However, in infertile males, deficient Tcte3-3 function is correlated with increased apoptosis during male germ cell development, resulting in a reduction of sperm number. Moreover, multiple malformations in developing haploid germ cells are present. Our results support a role of Tcte3-3 in generation of sperm motility as well as in male germ cell differentiation.

  20. Genetic Analysis of the Cytoplasmic Dynein Subunit Families

    PubMed Central

    Pfister, K. Kevin; Shah, Paresh R; Hummerich, Holger; Russ, Andreas; Cotton, James; Annuar, Azlina Ahmad; King, Stephen M; Fisher, Elizabeth M. C

    2006-01-01

    Cytoplasmic dyneins, the principal microtubule minus-end-directed motor proteins of the cell, are involved in many essential cellular processes. The major form of this enzyme is a complex of at least six protein subunits, and in mammals all but one of the subunits are encoded by at least two genes. Here we review current knowledge concerning the subunits, their interactions, and their functional roles as derived from biochemical and genetic analyses. We also carried out extensive database searches to look for new genes and to clarify anomalies in the databases. Our analysis documents evolutionary relationships among the dynein subunits of mammals and other model organisms, and sheds new light on the role of this diverse group of proteins, highlighting the existence of two cytoplasmic dynein complexes with distinct cellular roles. PMID:16440056

  1. Dynein Regulators Are Important for Ecotropic Murine Leukemia Virus Infection

    PubMed Central

    Valle-Tenney, Roger; Opazo, Tatiana; Cancino, Jorge; Goff, Stephen P.

    2016-01-01

    ABSTRACT During the early steps of infection, retroviruses must direct the movement of the viral genome into the nucleus to complete their replication cycle. This process is mediated by cellular proteins that interact first with the reverse transcription complex and later with the preintegration complex (PIC), allowing it to reach and enter the nucleus. For simple retroviruses, such as murine leukemia virus (MLV), the identities of the cellular proteins involved in trafficking of the PIC in infection are unknown. To identify cellular proteins that interact with the MLV PIC, we developed a replication-competent MLV in which the integrase protein was tagged with a FLAG epitope. Using a combination of immunoprecipitation and mass spectrometry, we established that the microtubule motor dynein regulator DCTN2/p50/dynamitin interacts with the MLV preintegration complex early in infection, suggesting a direct interaction between the incoming viral particles and the dynein complex regulators. Further experiments showed that RNA interference (RNAi)-mediated silencing of either DCTN2/p50/dynamitin or another dynein regulator, NudEL, profoundly reduced the efficiency of infection by ecotropic, but not amphotropic, MLV reporters. We propose that the cytoplasmic dynein regulators are a critical component of the host machinery needed for infection by the retroviruses entering the cell via the ecotropic envelope pathway. IMPORTANCE Retroviruses must access the chromatin of host cells to integrate the viral DNA, but before this crucial event, they must reach the nucleus. The movement through the cytoplasm—a crowded environment where diffusion is slow—is thought to utilize retrograde transport along the microtubule network by the dynein complex. Different viruses use different components of this multisubunit complex. We found that the preintegration complex of murine leukemia virus (MLV) interacts with the dynein complex and that regulators of this complex are essential for

  2. The primary structure of rat brain (cytoplasmic) dynein heavy chain, a cytoplasmic motor enzyme.

    PubMed Central

    Zhang, Z; Tanaka, Y; Nonaka, S; Aizawa, H; Kawasaki, H; Nakata, T; Hirokawa, N

    1993-01-01

    Overlapping cDNA clones encoding the heavy chain of rat brain cytoplasmic dynein have been isolated. The isolated cDNA clones contain an open reading frame of 13,932 bp encoding 4644 aa (M(r), 532,213). The deduced protein sequence of the heavy chain of rat brain dynein shows significant similarity to sea urchin flagellar beta-dynein (27.0% identical) and to Dictyostelium cytoplasmic dynein (53.5% identical) throughout the entire sequence. The heavy chain of rat brain (cytoplasmic) dynein contains four putative nucleotide-binding consensus sequences [GX4GK(T/S)] in the central one-third region that are highly similar to those of sea urchin and Dictyostelium dyneins. The N-terminal one-third of the heavy chain of rat brain (cytoplasmic) dynein shows high similarity (43.8% identical) to that of Dictyostelium cytoplasmic dynein but poor similarity (19.4% identical) to that of sea urchin flagellar dynein. These results suggested that the C-terminal two-thirds of the dynein molecule is conserved and plays an essential role in microtubule-dependent motility activity, whereas the N-terminal regions are different between cytoplasmic and flagellar dyneins. Images Fig. 1 PMID:7690137

  3. Dynein's C-terminal Domain Plays a Novel Role in Regulating Force Generation

    NASA Astrophysics Data System (ADS)

    Gennerich, Arne; Nicholas, Matthew; Brenner, Sibylle; Lazar, Caitlin; Weil, Sarah; Vallee, Richard; Hook, Peter; Gennerich Lab Collaboration; Vallee Lab Collaboration

    2014-03-01

    Cytoplasmic dynein is a microtubule motor involved in a wide range of low and high force requiring functions in metazoans. In contrast, yeast dynein is involved in a single, nonessential function, nuclear positioning. Interestingly, the single-molecule function of yeast dynein is also unique: whereas mammalian dyneins generate forces of 1-2 pN, S. cerevisiae dynein stalls at 5-7 pN. The basis for this functional difference is unknown. However, the major structural difference between mammalian and yeast dyneins is a ~30 kDa C-terminal extension (CT) present in higher eukaryotic dyneins, but missing in yeast. To test whether the CT accounts for the differences in function, we produced recombinant rat dynein motor domains (MD) with (WT-MD) and without (ΔCT-MD) the CT, using baculovirus expression. To define motor function, we performed single-molecule optical trapping studies. Dimerized WT-MD stalls at ~1 pN and detaches from microtubules after brief stalls, in agreement with previous studies on native mammalian dynein. In sharp contrast, but similar to yeast dynein, ΔCT-MD stalls at ~6 pN, with stall durations up to minutes. These results identify the CT as a new regulatory element for controlling dynein force generation. Supported by NIH GM094415 (A.G.) and GM102347 (R.B.V.)

  4. Congenitally absent lumbar pedicle: a reappraisal

    SciTech Connect

    Wortzman, G.; Steinhardt, M.I.

    1984-09-01

    Three patients who had a diagnosis of congenitally absent lumbar pedicle underwent CT examination. Findings showed that each patient had an aberrant hypoplastic pedicle plus a retroisthmic defect in their ipsilateral lamina rather than an absent pedicle. Axial CT was the diagnostic modality of choice; reformated images were of little value. The differential diagnosis to be considered from the findings of plain film radiography includes pediculate thinning, neoplastic disease, neurofibroma, mesodermal dysplasia associated with neurofibromatosis, and vascular anomalies.

  5. Differential phosphorylation in vivo of cytoplasmic dynein associated with anterogradely moving organelles

    PubMed Central

    1994-01-01

    Two microtubule-stimulated ATPases, cytoplasmic dynein, and kinesin, are believed to be responsible for the intracellular movement of membrane-bound organelles in opposite directions along microtubules. An unresolved component of this model is the mechanism by which cells regulate these two motors to direct various membrane-bound organelles to their proper locations. To determine if phosphorylation may play a role in the regulation of cytoplasmic dynein, the in vivo phosphorylation state of cytoplasmic dynein from two cellular pools was examined. The entire cellular pool of brain cytoplasmic dynein was metabolically labeled by the infusion of [32P]orthophosphate into the cerebrospinal fluid of rat brain ventricles. To characterize the phosphorylation of dynein associated with anterograde membrane-bound organelles, the optic nerve fast axonal transport system was used. Using a monoclonal antibody to the 74-kD polypeptide of brain cytoplasmic dynein, the native dynein complex was immunoprecipitated from the radiolabled tissue extracts. Autoradiographs of one and two dimensional gels showed labeling of nearly all of the polypeptide isoforms of cytoplasmic dynein from rat brain. These polypeptides are phosphorylated on serine residues. Comparison of the amount of 32P incorporated into the dynein polypeptides revealed differences in the phosphorylation of dynein polypeptides from the anterograde and the cellular pools. Most interestingly, the 530-kD heavy chain of dynein appears to be phosphorylated to a lesser extent in the anterograde pool than in the cellular pool. Since the anterograde pool contains inactive dynein, while the entire cellular pool contains both inactive and active dynein, these results are consistent with the hypothesis that phosphorylation regulates the functional activity of cytoplasmic dynein. PMID:7528220

  6. In vitro motility from recombinant dynein heavy chain.

    PubMed Central

    Mazumdar, M; Mikami, A; Gee, M A; Vallee, R B

    1996-01-01

    The dyneins are a class of motor protein involved in ciliary and flagellar motility, organelle transport, and chromosome segregation. Because of their large size and subunit complexity, relatively little is known about their mechanisms of force production and regulation. We report here on the expression and analysis of the entire rat cytoplasmic dynein heavy chain (Mr 532,000). Full-length cDNAs were constructed from a series of partial clones and tagged at the C terminus with either a FLAG-epitope tag or a His6-tag. The recombinant polypeptides were expressed either in insect cells by baculovirus infection or in COS-7 cells by transient transfection. The recombinant protein was mostly soluble and showed good microtubule binding. It exhibited a broad sedimentation profile, indicative of the formation of dimers as well as higher order multimers. Good microtubule gliding motility activity was observed in assays of heavy chain expressed in either insect or COS-7 cells. Average microtubule gliding velocities of 1.2-1.8 microm/sec were observed, comparable with the rates determined for calf brain cytoplasmic dynein. These results represent the first indication that recombinant heavy chain alone is capable of force production, and should lead to rapid progress in defining the dynein motor domain. Images Fig. 1 Fig. 2 Fig. 3 PMID:8692854

  7. The third P-loop domain in cytoplasmic dynein heavy chain is essential for dynein motor function and ATP-sensitive microtubule binding.

    PubMed

    Silvanovich, Andre; Li, Min-Gang; Serr, Madeline; Mische, Sarah; Hays, Thomas S

    2003-04-01

    Sequence comparisons and structural analyses show that the dynein heavy chain motor subunit is related to the AAA family of chaperone-like ATPases. The core structure of the dynein motor unit derives from the assembly of six AAA domains into a hexameric ring. In dynein, the first four AAA domains contain consensus nucleotide triphosphate-binding motifs, or P-loops. The recent structural models of dynein heavy chain have fostered the hypothesis that the energy derived from hydrolysis at P-loop 1 acts through adjacent P-loop domains to effect changes in the attachment state of the microtubule-binding domain. However, to date, the functional significance of the P-loop domains adjacent to the ATP hydrolytic site has not been demonstrated. Our results provide a mutational analysis of P-loop function within the first and third AAA domains of the Drosophila cytoplasmic dynein heavy chain. Here we report the first evidence that P-loop-3 function is essential for dynein function. Significantly, our results further show that P-loop-3 function is required for the ATP-induced release of the dynein complex from microtubules. Mutation of P-loop-3 blocks ATP-mediated release of dynein from microtubules, but does not appear to block ATP binding and hydrolysis at P-loop 1. Combined with the recent recognition that dynein belongs to the family of AAA ATPases, the observations support current models in which the multiple AAA domains of the dynein heavy chain interact to support the translocation of the dynein motor down the microtubule lattice.

  8. Ensemble and single-molecule dynamics of IFT dynein in Caenorhabditis elegans cilia.

    PubMed

    Mijalkovic, Jona; Prevo, Bram; Oswald, Felix; Mangeol, Pierre; Peterman, Erwin J G

    2017-02-23

    Cytoplasmic dyneins drive microtubule-based, minus-end directed transport in eukaryotic cells. Whereas cytoplasmic dynein 1 has been widely studied, IFT dynein has received far less attention. Here, we use fluorescence microscopy of labelled motors in living Caenorhabditis elegans to investigate IFT-dynein motility at the ensemble and single-molecule level. We find that while the kinesin composition of motor ensembles varies along the track, the amount of dynein remains relatively constant. Remarkably, this does not result in directionality changes of cargo along the track, as has been reported for other opposite-polarity, tug-of-war motility systems. At the single-molecule level, IFT-dynein trajectories reveal unexpected dynamics, including diffusion at the base, and pausing and directional switches along the cilium. Stochastic simulations show that the ensemble IFT-dynein distribution depends upon the probability of single-motor directional switches. Our results provide quantitative insight into IFT-dynein dynamics in vivo, shedding light on the complex functioning of dynein motors in general.

  9. Drosophila cytoplasmic dynein, a microtubule motor that is asymmetrically localized in the oocyte

    PubMed Central

    1994-01-01

    The unidirectional movements of the microtubule-associated motors, dyneins, and kinesins, provide an important mechanism for the positioning of cellular organelles and molecules. An intriguing possibility is that this mechanism may underlie the directed transport and asymmetric positioning of morphogens that influence the development of multicellular embryos. In this report, we characterize the Drosophila gene, Dhc64C, that encodes a cytoplasmic dynein heavy chain polypeptide. The primary structure of the Drosophila cytoplasmic dynein heavy chain polypeptide has been determined by the isolation and sequence analysis of overlapping cDNA clones. Drosophila cytoplasmic dynein is highly similar in sequence and structure to cytoplasmic dynein isoforms reported for other organisms. The Dhc64C dynein transcript is differentially expressed during development with the highest levels being detected in the ovaries of adult females. Within the developing egg chambers of the ovary, the dynein gene is predominantly transcribed in the nurse cell complex. In contrast, the encoded dynein motor protein displays a striking accumulation in the single cell that will develop as the oocyte. The temporal and spatial pattern of dynein accumulation in the oocyte is remarkably similar to that of several maternal effect gene products that are essential for oocyte differentiation and axis specification. This distribution and its disruption by specific maternal effect mutations lends support to recent models suggesting that microtubule motors participate in the transport of these morphogens from the nurse cell cytoplasm to the oocyte. PMID:8089180

  10. Regulation of the processivity and intracellular localization of Saccharomyces cerevisiae dynein by dynactin

    PubMed Central

    Kardon, Julia R.; Reck-Peterson, Samara L.; Vale, Ronald D.

    2009-01-01

    Dynactin, a large multisubunit complex, is required for intracellular transport by dynein; however, its cellular functions and mechanism of action are not clear. Prior studies suggested that dynactin increases dynein processivity by tethering the motor to the microtubule through its own microtubule binding domains. However, this hypothesis could not be tested without a recombinant source of dynactin. Here, we have produced recombinant dynactin and dynein in Saccharomyces cerevisiae, and examined the effect of dynactin on dynein in single-molecule motility assays. We show that dynactin increases the run length of single dynein motors, but does not alter the directionality of dynein movement. Enhancement of dynein processivity by dynactin does not require the microtubule (MT) binding domains of Nip100 (the yeast p150Glued homolog). Dynactin lacking these MT binding domains also supports the proper localization and function of dynein during nuclear segregation in vivo. Instead, a segment of the coiled-coil of Nip100 is required for these activities. Our results directly demonstrate that dynactin increases the processivity of dynein through a mechanism independent of microtubule tethering. PMID:19293377

  11. BICD2, dynactin, and LIS1 cooperate in regulating dynein recruitment to cellular structures

    PubMed Central

    Splinter, Daniël; Razafsky, David S.; Schlager, Max A.; Serra-Marques, Andrea; Grigoriev, Ilya; Demmers, Jeroen; Keijzer, Nanda; Jiang, Kai; Poser, Ina; Hyman, Anthony A.; Hoogenraad, Casper C.; King, Stephen J.; Akhmanova, Anna

    2012-01-01

    Cytoplasmic dynein is the major microtubule minus-end–directed cellular motor. Most dynein activities require dynactin, but the mechanisms regulating cargo-dependent dynein–dynactin interaction are poorly understood. In this study, we focus on dynein–dynactin recruitment to cargo by the conserved motor adaptor Bicaudal D2 (BICD2). We show that dynein and dynactin depend on each other for BICD2-mediated targeting to cargo and that BICD2 N-terminus (BICD2-N) strongly promotes stable interaction between dynein and dynactin both in vitro and in vivo. Direct visualization of dynein in live cells indicates that by itself the triple BICD2-N–dynein–dynactin complex is unable to interact with either cargo or microtubules. However, tethering of BICD2-N to different membranes promotes their microtubule minus-end–directed motility. We further show that LIS1 is required for dynein-mediated transport induced by membrane tethering of BICD2-N and that LIS1 contributes to dynein accumulation at microtubule plus ends and BICD2-positive cellular structures. Our results demonstrate that dynein recruitment to cargo requires concerted action of multiple dynein cofactors. PMID:22956769

  12. Ensemble and single-molecule dynamics of IFT dynein in Caenorhabditis elegans cilia

    PubMed Central

    Mijalkovic, Jona; Prevo, Bram; Oswald, Felix; Mangeol, Pierre; Peterman, Erwin J. G.

    2017-01-01

    Cytoplasmic dyneins drive microtubule-based, minus-end directed transport in eukaryotic cells. Whereas cytoplasmic dynein 1 has been widely studied, IFT dynein has received far less attention. Here, we use fluorescence microscopy of labelled motors in living Caenorhabditis elegans to investigate IFT-dynein motility at the ensemble and single-molecule level. We find that while the kinesin composition of motor ensembles varies along the track, the amount of dynein remains relatively constant. Remarkably, this does not result in directionality changes of cargo along the track, as has been reported for other opposite-polarity, tug-of-war motility systems. At the single-molecule level, IFT-dynein trajectories reveal unexpected dynamics, including diffusion at the base, and pausing and directional switches along the cilium. Stochastic simulations show that the ensemble IFT-dynein distribution depends upon the probability of single-motor directional switches. Our results provide quantitative insight into IFT-dynein dynamics in vivo, shedding light on the complex functioning of dynein motors in general. PMID:28230057

  13. Expansion and Polarity Sorting in Microtubule-Dynein Bundles

    NASA Astrophysics Data System (ADS)

    Zemel, A.; Mogilner, A.

    Interactions of multiple molecular motors with dynamicpolymers, such as actin and microtubules, form the basis for many processes in the cell cytoskeleton. One example is the active `sorting' of microtubule bundles by dynein molecular motors into aster-like arrays of microtubules; in these bundles dynein motors cross-link and slide neighboring microtubules apart. A number of models have been suggested to quantify the active dynamics of cross-linked bundles of polar filaments. In the case of densely packed bundles, however, a major complication arises from the fact that each microtubule interacts with multiple neighboring filaments. To explicitly take these interactions into account we performed detailed computer simulations in which the equations of motion for all microtubules in the bundle were iteratively solved. Our simulations demonstrate the phenomenon of polarity sorting and reveal the variable-rate of the concurrent bundle expansion and its dependence on the nature of the microtubule-motor interactions.

  14. Time-Dependent Measure of a Nano-Scale Force-Pulse Driven by the Axonemal Dynein Motors in Individual Live Sperm Cells

    SciTech Connect

    Allen, M J; Rudd, R E; McElfresh, M W; Balhorn, R

    2009-04-23

    Nano-scale mechanical forces generated by motor proteins are crucial to normal cellular and organismal functioning. The ability to measure and exploit such forces would be important to developing motile biomimetic nanodevices powered by biological motors for Nanomedicine. Axonemal dynein motors positioned inside the sperm flagellum drive microtubule sliding giving rise to rhythmic beating of the flagellum. This force-generating action makes it possible for the sperm cell to move through viscous media. Here we report new nano-scale information on how the propulsive force is generated by the sperm flagellum and how this force varies over time. Single cell recordings reveal discrete {approx}50 ms pulses oscillating with amplitude 9.8 {+-} 2.6 nN independent of pulse frequency (3.5-19.5 Hz). The average work carried out by each cell is 4.6 x 10{sup -16} J per pulse, equivalent to the hydrolysis of {approx}5,500 ATP molecules. The mechanochemical coupling at each active dynein head is {approx}2.2 pN/ATP, and {approx}3.9 pN per dynein arm, in agreement with previously published values obtained using different methods.

  15. Importance of absent ductus arteriosus in tetralogy of Fallot with absent pulmonary valve syndrome.

    PubMed

    Qureshi, Muhammad Yasir; Burkhart, Harold M; Julsrud, Paul; Cetta, Frank

    2014-12-01

    Tetralogy of Fallot without pulmonary valve syndrome is almost always associated with an absent ductus arteriosus. Patients with right aortic arch and retroesophageal left subclavian artery have a vascular ring if the left ductus arteriosus or its remnant and the Kommerell diverticulum are present. We report the cases of 2 infants in whom the role of an absent ductus arteriosus or its remnant is noteworthy. Both patients had a combination of tetralogy of Fallot with absent pulmonary valve syndrome and right aortic arch with retroesophageal left subclavian artery without a vascular ring. The absence of the ductus arteriosus has a role in the pathogenesis of tetralogy of Fallot with absent pulmonary valve syndrome. The absence of a ductus arteriosus in the right aortic arch with retroesophageal left subclavian artery precludes a vascular ring.

  16. Interactions of Yeast Dynein with Dynein Light Chain and Dynactin: GENERAL IMPLICATIONS FOR INTRINSICALLY DISORDERED DUPLEX SCAFFOLDS IN MULTIPROTEIN ASSEMBLIES.

    PubMed

    Jie, Jing; Löhr, Frank; Barbar, Elisar

    2015-09-25

    Intrinsically disordered protein (IDP) duplexes composed of two IDP chains cross-linked by bivalent partner proteins form scaffolds for assembly of multiprotein complexes. The N-terminal domain of dynein intermediate chain (N-IC) is one such IDP that forms a bivalent scaffold with multiple dynein light chains including LC8, a hub protein that promotes duplex formation of diverse IDP partners. N-IC also binds a subunit of the dynein regulator, dynactin. Here we characterize interactions of a yeast ortholog of N-IC (N-Pac11) with yeast LC8 (Dyn2) or with the intermediate chain-binding subunit of yeast dynactin (Nip100). Residue level changes in Pac11 structure are monitored by NMR spectroscopy, and binding energetics are monitored by isothermal titration calorimetry (ITC). N-Pac11 is monomeric and primarily disordered except for a single α-helix (SAH) at the N terminus and a short nascent helix, LH, flanked by the two Dyn2 recognition motifs. Upon binding Dyn2, the only Pac11 residues making direct protein-protein interactions are in and immediately flanking the recognition motifs. Dyn2 binding also orders LH residues of Pac11. Upon binding Nip100, only Pac11 SAH residues make direct protein-protein interactions, but LH residues at a distant sequence position and L1 residues in an adjacent linker are also ordered. The long distance, ligand-dependent ordering of residues reveals new elements of dynamic structure within IDP linker regions.

  17. Gene knockouts reveal separate functions for two cytoplasmic dyneins in Tetrahymena thermophila.

    PubMed

    Lee, S; Wisniewski, J C; Dentler, W L; Asai, D J

    1999-03-01

    In many organisms, there are multiple isoforms of cytoplasmic dynein heavy chains, and division of labor among the isoforms would provide a mechanism to regulate dynein function. The targeted disruption of somatic genes in Tetrahymena thermophila presents the opportunity to determine the contributions of individual dynein isoforms in a single cell that expresses multiple dynein heavy chain genes. Substantial portions of two Tetrahymena cytoplasmic dynein heavy chain genes were cloned, and their motor domains were sequenced. Tetrahymena DYH1 encodes the ubiquitous cytoplasmic dynein Dyh1, and DYH2 encodes a second cytoplasmic dynein isoform, Dyh2. The disruption of DYH1, but not DYH2, resulted in cells with two detectable defects: 1) phagocytic activity was inhibited, and 2) the cells failed to distribute their chromosomes correctly during micronuclear mitosis. In contrast, the disruption of DYH2 resulted in a loss of regulation of cell size and cell shape and in the apparent inability of the cells to repair their cortical cytoskeletons. We conclude that the two dyneins perform separate tasks in Tetrahymena.

  18. Emergence of flagellar beating from the collective behavior of individual ATP-powered dyneins

    NASA Astrophysics Data System (ADS)

    Namdeo, S.; Onck, P. R.

    2016-10-01

    Flagella are hair-like projections from the surface of eukaryotic cells, and they play an important role in many cellular functions, such as cell-motility. The beating of flagella is enabled by their internal architecture, the axoneme, and is powered by a dense distribution of motor proteins, dyneins. The dyneins deliver the required mechanical work through the hydrolysis of ATP. Although the dynein-ATP cycle, the axoneme microstructure, and the flagellar-beating kinematics are well studied, their integration into a coherent picture of ATP-powered flagellar beating is still lacking. Here we show that a time-delayed negative-work-based switching mechanism is able to convert the individual sliding action of hundreds of dyneins into a regular overall beating pattern leading to propulsion. We developed a computational model based on a minimal representation of the axoneme consisting of two representative doublet microtubules connected by nexin links. The relative sliding of the microtubules is incorporated by modeling two groups of ATP-powered dyneins, each responsible for sliding in opposite directions. A time-delayed switching mechanism is postulated, which is key in converting the local individual sliding action of multiple dyneins into global beating. Our results demonstrate that an overall nonreciprocal beating pattern can emerge with time due to the spatial and temporal coordination of the individual dyneins. These findings provide insights in the fundamental working mechanism of axonemal dyneins and could possibly open new research directions in the field of flagellar motility.

  19. The retrograde IFT machinery of C. elegans cilia: two IFT dynein complexes?

    PubMed

    Hao, Limin; Efimenko, Evgeni; Swoboda, Peter; Scholey, Jonathan M

    2011-01-01

    We analyzed the relatively poorly understood IFT-dynein (class DYNC2)-driven retrograde IFT pathway in C. elegans cilia, which yielded results that are surprising in the context of current models of IFT. Assays of C. elegans dynein gene expression and intraflagellar transport (IFT) suggest that conventional IFT-dynein contains essential heavy (CHE-3), light-intermediate (XBX-1), plus three light polypeptide chains that participate in IFT, but no "essential" intermediate chain. IFT assays of XBX-1::YFP suggest that IFT-dynein is transported as cargo to the distal tip of the cilium by kinesin-2 motors, but independent of the IFT-particle/BBSome complexes. Finally, we were surprised to find that the subset of cilia present on the OLQ (outer labial quadrant) neurons assemble independently of conventional "CHE-3" IFT-dynein, implying that there is a second IFT-dynein acting in these cilia. We have found a novel gene encoding a dynein heavy chain, DHC-3, and two light chains, in OLQ neurons, which could constitute an IFT-dynein complex in OLQ neuronal cilia. Our results underscore several surprising features of retrograde IFT that require clarification.

  20. A mammalian NudC-like protein essential for dynein stability and cell viability.

    PubMed

    Zhou, Tianhua; Zimmerman, Wendy; Liu, Xiaoqi; Erikson, Raymond L

    2006-06-13

    Cytoplasmic dynein, a minus-end-directed microtubule motor, has been implicated in many fundamental cellular processes; however, little is known regarding the underlying molecular machinery that regulates its stability. In Aspergillus nidulans, nuclear distribution gene C (nudC) has been implicated in the regulation of dynein-mediated nuclear migration. Here, we characterize a previously undescribed mammalian NudC-like protein (NudCL). The expression and phosphorylation of NudCL are increased during mitosis. Depletion of NudCL by RNA interference in HeLa cells inhibits cell growth and induces mitotic arrest with multiple mitotic defects, which subsequently result in cell death. Unexpectedly, the majority of NudCL depletion-induced mitotic defects may result from loss of dynein function; this interpretation is supported by the failure to recruit sufficient gamma-tubulin to spindle poles and the mislocalization of the dynein complex from kinetochores, spindle microtubules, and spindle poles during mitosis. Depletion of NudCL also results in the aggregation of dynein intermediate chain throughout the cytoplasm during mitosis. NudCL was shown to bind to the dynein complex, and its depletion induces degradation of dynein intermediate chain, a process suppressed by MG132, a proteasome inhibitor. Taken together, these data suggest a previously undescribed mechanism whereby NudCL appears to influence the stabilization of dynein intermediate chain.

  1. ATP-Driven Remodeling of the Linker Domain in the Dynein Motor

    PubMed Central

    Roberts, Anthony J.; Malkova, Bara; Walker, Matt L.; Sakakibara, Hitoshi; Numata, Naoki; Kon, Takahide; Ohkura, Reiko; Edwards, Thomas A.; Knight, Peter J.; Sutoh, Kazuo; Oiwa, Kazuhiro; Burgess, Stan A.

    2012-01-01

    Summary Dynein ATPases are the largest known cytoskeletal motors and perform critical functions in cells: carrying cargo along microtubules in the cytoplasm and powering flagellar beating. Dyneins are members of the AAA+ superfamily of ring-shaped enzymes, but how they harness this architecture to produce movement is poorly understood. Here, we have used cryo-EM to determine 3D maps of native flagellar dynein-c and a cytoplasmic dynein motor domain in different nucleotide states. The structures show key sites of conformational change within the AAA+ ring and a large rearrangement of the “linker” domain, involving a hinge near its middle. Analysis of a mutant in which the linker “undocks” from the ring indicates that linker remodeling requires energy that is supplied by interactions with the AAA+ modules. Fitting the dynein-c structures into flagellar tomograms suggests how this mechanism could drive sliding between microtubules, and also has implications for cytoplasmic cargo transport. PMID:22863569

  2. N-Acetyl-D-Glucosamine Kinase Interacts with Dynein-Lis1-NudE1 Complex and Regulates Cell Division

    PubMed Central

    Sharif, Syeda Ridita; Islam, Ariful; Moon, Il Soo

    2016-01-01

    N-acetyl-D-glucosamine kinase (GlcNAc kinase or NAGK) primarily catalyzes phosphoryl transfer to GlcNAc during amino sugar metabolism. Recently, it was shown NAGK interacts with dynein light chain roadblock type 1 (DYNLRB1) and upregulates axo-dendritic growth, which is an enzyme activity-independent, non-canonical structural role. The authors examined the distributions of NAGK and NAGK-dynein complexes during the cell cycle in HEK293T cells. NAGK was expressed throughout different stages of cell division and immunocytochemistry (ICC) showed NAGK was localized at nuclear envelope, spindle microtubules (MTs), and kinetochores (KTs). A proximity ligation assay (PLA) for NAGK and DYNLRB1 revealed NAGK-dynein complex on nuclear envelopes in prophase cells and on chromosomes in metaphase cells. NAGK-DYNLRB1 PLA followed by Lis1/NudE1 immunostaining showed NAGK-dynein complexes were colocalized with Lis1 and NudE1 signals, and PLA for NAGK-Lis1 showed similar signal patterns, suggesting a functional link between NAGK and dynein-Lis1 complex. Subsequently, NAGK-dynein complexes were found in KTs and on nuclear membranes where KTs were marked with CENP-B ICC and nuclear membrane with lamin ICC. Furthermore, knockdown of NAGK by small hairpin (sh) RNA was found to delay cell division. These results indicate that the NAGK-dynein interaction with the involvements of Lis1 and NudE1 plays an important role in prophase nuclear envelope breakdown (NEB) and metaphase MT-KT attachment during eukaryotic cell division. PMID:27646688

  3. Effects of iodide on the coupling between ATP hydrolysis and motile activity in axonemal dynein.

    PubMed

    Nakano, Izumi; Fujiwara, Rin; Wada, Mikiyo; Shingyoji, Chikako

    2011-05-01

    Dynein transduces the chemical energy of ATP hydrolysis into mechanical work through conformational changes. To identify the factors governing the coupling between the ATPase activity and the motile activity of the dynein molecule, we examined the effects of potassium iodide, which can unfold protein tertiary structures, on dynein activity in reactivated sea urchin sperm flagella. The presence of low concentrations of KI (0.05-0.1 M) in the reactivating solution did not influence the stable beating of demembranated flagella at 0.02-1 mM ATP, when the total concentration of potassium was kept at 0.15 M by adding K-acetate. However, double-reciprocal plots of ATP concentration and beat frequency showed a mixed type of inhibition by KI, indicating the possibility that KI inhibits the ATP hydrolysis and decreases the maximum sliding velocity. The ATPase activity of 21S dynein with or without microtubules did not decrease with the KI concentration. In the elastase-treated axonemes, KI decreased the velocity of sliding disintegration, while it increased the frequency of occurrence of axonemes showing no sliding. This may be related to some defect in the coordination of dynein activities. On 21S dynein adsorbed on a glass surface, however, the velocity of microtubule sliding was increased by KI, while KI lowered the dynein-microtubule affinity. The velocity further increased under lower salt conditions enhancing the dynein-microtubule interactions. The results suggest the importance of organized regulation of the dynamic states of dynein-microtubule interactions through the stalk for the coupling between the ATPase activity and the motile activity of dynein in beating flagella.

  4. The intraflagellar transport dynein complex of trypanosomes is made of a heterodimer of dynein heavy chains and of light and intermediate chains of distinct functions.

    PubMed

    Blisnick, Thierry; Buisson, Johanna; Absalon, Sabrina; Marie, Alexandra; Cayet, Nadège; Bastin, Philippe

    2014-09-01

    Cilia and flagella are assembled by intraflagellar transport (IFT) of protein complexes that bring tubulin and other precursors to the incorporation site at their distal tip. Anterograde transport is driven by kinesin, whereas retrograde transport is ensured by a specific dynein. In the protist Trypanosoma brucei, two distinct genes encode fairly different dynein heavy chains (DHCs; ∼40% identity) termed DHC2.1 and DHC2.2, which form a heterodimer and are both essential for retrograde IFT. The stability of each heavy chain relies on the presence of a dynein light intermediate chain (DLI1; also known as XBX-1/D1bLIC). The presence of both heavy chains and of DLI1 at the base of the flagellum depends on the intermediate dynein chain DIC5 (FAP133/WDR34). In the IFT140(RNAi) mutant, an IFT-A protein essential for retrograde transport, the IFT dynein components are found at high concentration at the flagellar base but fail to penetrate the flagellar compartment. We propose a model by which the IFT dynein particle is assembled in the cytoplasm, reaches the base of the flagellum, and associates with the IFT machinery in a manner dependent on the IFT-A complex.

  5. Dynactin 3D structure: implications for assembly and dynein binding.

    PubMed

    Imai, Hiroshi; Narita, Akihiro; Maéda, Yuichiro; Schroer, Trina A

    2014-09-23

    The multisubunit protein complex, dynactin, is an essential component of the cytoplasmic dynein motor. High-resolution structural work on dynactin and the dynein/dynactin supercomplex has been limited to small subunits and recombinant fragments that do not report fully on either ≈1MDa assembly. In the present study, we used negative-stain electron microscopy and image analysis based on random conical tilt reconstruction to obtain a three-dimensional (3D) structure of native vertebrate dynactin. The 35-nm-long dynactin molecule has a V-shaped shoulder at one end and a flattened tip at the other end, both offset relative to the long axis of the actin-related protein (Arp) backbone. The shoulder projects dramatically away from the Arp filament core in a way that cannot be appreciated in two-dimensional images, which has implications for the mechanism of dynein binding. The 3D structure allows the helical parameters of the entire Arp filament core, which includes the actin capping protein, CP, to be determined for the first time. This structure exhibits near identity to F-actin and can be well fitted into the dynactin envelope. Molecular fitting of modeled CP-Arp polymers into the envelope shows that the filament contains between 7 and 9 Arp protomers and is capped at both ends. In the 7 Arp model, which agrees best with measured Arp stoichiometry and other structural information, actin capping protein (CP) is not present at the distal tip of the structure, unlike what is seen in the other models. The 3D structure suggests a mechanism for dynactin assembly and length specification.

  6. A screen for dynein synthetic lethals in Aspergillus nidulans identifies spindle assembly checkpoint genes and other genes involved in mitosis.

    PubMed Central

    Efimov, V P; Morris, N R

    1998-01-01

    Cytoplasmic dynein is a ubiquitously expressed microtubule motor involved in vesicle transport, mitosis, nuclear migration, and spindle orientation. In the filamentous fungus Aspergillus nidulans, inactivation of cytoplasmic dynein, although not lethal, severely impairs nuclear migration. The role of dynein in mitosis and vesicle transport in this organism is unclear. To investigate the complete range of dynein function in A. nidulans, we searched for synthetic lethal mutations that significantly reduced growth in the absence of dynein but had little effect on their own. We isolated 19 sld (synthetic lethality without dynein) mutations in nine different genes. Mutations in two genes exacerbate the nuclear migration defect seen in the absence of dynein. Mutations in six other genes, including sldA and sldB, show a strong synthetic lethal interaction with a mutation in the mitotic kinesin bimC and, thus, are likely to play a role in mitosis. Mutations in sldA and sldB also confer hypersensitivity to the microtubule-destabilizing drug benomyl. sldA and sldB were cloned by complementation of their mutant phenotypes using an A. nidulans autonomously replicating vector. Sequencing revealed homology to the spindle assembly checkpoint genes BUB1 and BUB3 from Saccharomyces cerevisiae. Genetic interaction between dynein and spindle assembly checkpoint genes, as well as other mitotic genes, indicates that A. nidulans dynein plays a role in mitosis. We suggest a model for dynein motor action in A. nidulans that can explain dynein involvement in both mitosis and nuclear distribution. PMID:9584089

  7. Requirement for Nudel and dynein for assembly of the lamin B spindle matrix.

    PubMed

    Ma, Li; Tsai, Ming-Ying; Wang, Shusheng; Lu, Bingwen; Chen, Rong; Iii, John R Yates; Zhu, Xueliang; Zheng, Yixian

    2009-03-01

    The small guanosine triphosphatase Ran loaded with GTP (RanGTP) can stimulate assembly of the type V intermediate filament protein lamin B into a membranous lamin B spindle matrix, which is required for proper microtubule organization during spindle assembly. Microtubules in turn enhance assembly of the matrix. Here we report that the isolated matrix contains known spindle assembly factors such as dynein and Nudel. Using spindle assembly assays in Xenopus egg extracts, we show that Nudel regulates microtubule organization during spindle assembly independently of its function at kinetochores. Importantly, Nudel interacts directly with lamin B to facilitate the accumulation and assembly of lamin-B-containing matrix on microtubules in a dynein-dependent manner. Perturbing either Nudel or dynein inhibited the assembly of lamin B matrix. However, depleting lamin B still allowed the formation of matrices containing dynein and Nudel. Therefore, dynein and Nudel regulate assembly of the lamin B matrix. Interestingly, we found that whereas depleting lamin B resulted in disorganized spindle and spindle poles, disrupting the function of Nudel or dynein caused a complete lack of spindle pole focusing. We suggest that Nudel regulates microtubule organization in part by facilitating assembly of the lamin B spindle matrix in a dynein-dependent manner.

  8. Effect of fuel concentration and force on collective transport by a team of dynein motors.

    PubMed

    Takshak, Anjneya; Roy, Tanushree; Tandaiya, Parag; Kunwar, Ambarish

    2017-02-01

    Motor proteins are essential components of intracellular transport inside eukaryotic cells. These protein molecules use chemical energy obtained from hydrolysis of ATP to produce mechanical forces required for transporting cargos inside cells, from one location to another, in a directed manner. Of these motors, cytoplasmic dynein is structurally more complex than other motor proteins involved in intracellular transport, as it shows force and fuel (ATP) concentration dependent step-size. Cytoplasmic dynein motors are known to work in a team during cargo transport and force generation. Here, we use a complete Monte-Carlo model of single dynein constrained by in vitro experiments, which includes the effect of both force and ATP on stepping as well as detachment of motors under force. We then use our complete Monte-Carlo model of single dynein motor to understand collective cargo transport by a team of dynein motors, such as dependence of cargo travel distance and velocity on applied force and fuel concentration. In our model, cargos pulled by a team of dynein motors do not detach rapidly under higher forces, confirming the experimental observation of longer persistence time of dynein team on microtubule under higher forces.

  9. Reconstitution of dynein transport to the microtubule plus end by kinesin

    PubMed Central

    Roberts, Anthony J; Goodman, Brian S; Reck-Peterson, Samara L

    2014-01-01

    Cytoplasmic dynein powers intracellular movement of cargo toward the microtubule minus end. The first step in a variety of dynein transport events is the targeting of dynein to the dynamic microtubule plus end, but the molecular mechanism underlying this spatial regulation is not understood. Here, we reconstitute dynein plus-end transport using purified proteins from S. cerevisiae and dissect the mechanism using single-molecule microscopy. We find that two proteins–homologs of Lis1 and Clip170–are sufficient to couple dynein to Kip2, a plus-end-directed kinesin. Dynein is transported to the plus end by Kip2, but is not a passive passenger, resisting its own plus-end-directed motion. Two microtubule-associated proteins, homologs of Clip170 and EB1, act as processivity factors for Kip2, helping it overcome dynein's intrinsic minus-end-directed motility. This reveals how a minimal system of proteins transports a molecular motor to the start of its track. DOI: http://dx.doi.org/10.7554/eLife.02641.001 PMID:24916158

  10. Mutations in the gene encoding IFT dynein complex component WDR34 cause Jeune asphyxiating thoracic dystrophy.

    PubMed

    Schmidts, Miriam; Vodopiutz, Julia; Christou-Savina, Sonia; Cortés, Claudio R; McInerney-Leo, Aideen M; Emes, Richard D; Arts, Heleen H; Tüysüz, Beyhan; D'Silva, Jason; Leo, Paul J; Giles, Tom C; Oud, Machteld M; Harris, Jessica A; Koopmans, Marije; Marshall, Mhairi; Elçioglu, Nursel; Kuechler, Alma; Bockenhauer, Detlef; Moore, Anthony T; Wilson, Louise C; Janecke, Andreas R; Hurles, Matthew E; Emmet, Warren; Gardiner, Brooke; Streubel, Berthold; Dopita, Belinda; Zankl, Andreas; Kayserili, Hülya; Scambler, Peter J; Brown, Matthew A; Beales, Philip L; Wicking, Carol; Duncan, Emma L; Mitchison, Hannah M

    2013-11-07

    Bidirectional (anterograde and retrograde) motor-based intraflagellar transport (IFT) governs cargo transport and delivery processes that are essential for primary cilia growth and maintenance and for hedgehog signaling functions. The IFT dynein-2 motor complex that regulates ciliary retrograde protein transport contains a heavy chain dynein ATPase/motor subunit, DYNC2H1, along with other less well functionally defined subunits. Deficiency of IFT proteins, including DYNC2H1, underlies a spectrum of skeletal ciliopathies. Here, by using exome sequencing and a targeted next-generation sequencing panel, we identified a total of 11 mutations in WDR34 in 9 families with the clinical diagnosis of Jeune syndrome (asphyxiating thoracic dystrophy). WDR34 encodes a WD40 repeat-containing protein orthologous to Chlamydomonas FAP133, a dynein intermediate chain associated with the retrograde intraflagellar transport motor. Three-dimensional protein modeling suggests that the identified mutations all affect residues critical for WDR34 protein-protein interactions. We find that WDR34 concentrates around the centrioles and basal bodies in mammalian cells, also showing axonemal staining. WDR34 coimmunoprecipitates with the dynein-1 light chain DYNLL1 in vitro, and mining of proteomics data suggests that WDR34 could represent a previously unrecognized link between the cytoplasmic dynein-1 and IFT dynein-2 motors. Together, these data show that WDR34 is critical for ciliary functions essential to normal development and survival, most probably as a previously unrecognized component of the mammalian dynein-IFT machinery.

  11. Ndel1 palmitoylation: a new mean to regulate cytoplasmic dynein activity

    PubMed Central

    Shmueli, Anat; Segal, Michal; Sapir, Tamar; Tsutsumi, Ryouhei; Noritake, Jun; Bar, Avi; Sapoznik, Sivan; Fukata, Yuko; Orr, Irit; Fukata, Masaki; Reiner, Orly

    2010-01-01

    Regulated activity of the retrograde molecular motor, cytoplasmic dynein, is crucial for multiple biological activities, and failure to regulate this activity can result in neuronal migration retardation or neuronal degeneration. The activity of dynein is controlled by the LIS1–Ndel1–Nde1 protein complex that participates in intracellular transport, mitosis, and neuronal migration. These biological processes are subject to tight multilevel modes of regulation. Palmitoylation is a reversible posttranslational lipid modification, which can dynamically regulate protein trafficking. We found that both Ndel1 and Nde1 undergo palmitoylation in vivo and in transfected cells by specific palmitoylation enzymes. Unpalmitoylated Ndel1 interacts better with dynein, whereas the interaction between Nde1 and cytoplasmic dynein is unaffected by palmitoylation. Furthermore, palmitoylated Ndel1 reduced cytoplasmic dynein activity as judged by Golgi distribution, VSVG and short microtubule trafficking, transport of endogenous Ndel1 and LIS1 from neurite tips to the cell body, retrograde trafficking of dynein puncta, and neuronal migration. Our findings indicate, to the best of our knowledge, for the first time that Ndel1 palmitoylation is a new mean for fine-tuning the activity of the retrograde motor cytoplasmic dynein. PMID:19927128

  12. Absent in Melanoma 2 proteins in SLE.

    PubMed

    Choubey, Divaker; Panchanathan, Ravichandran

    2017-03-01

    Type I interferons (IFN-α/β)-inducible PYRIN and HIN domain-containing protein family includes Absent in Melanoma 2 (murine Aim2 and human AIM2), murine p202, and human PYRIN-only protein 3 (POP3). The generation of Aim2-deficient mice indicated that the Aim2 protein is essential for inflammasome activation, resulting in the secretion of interleukin-1β (IL-1β) and IL-18 and cell death by pyroptosis. Further, Aim2-deficiency also increased constitutive expression of the IFN-β and expression of the p202 protein. Notably, an increased expression of p202 protein in female mice associated with the development of systemic lupus erythematosus (SLE). SLE in patients is characterized by a constitutive increase in serum levels of IFN-α and an increase in the expression IFN-stimulated genes. Recent studies indicate that p202 and POP3 proteins inhibit activation of the Aim2/AIM2 inflammasome and promote IFN-β expression. Therefore, we discuss the role of Aim2/AIM2 proteins in the suppression of type I IFNs production and lupus susceptibility.

  13. Genetic Influences Are Virtually Absent for Trust

    PubMed Central

    Van Lange, Paul A. M.; Vinkhuyzen, Anna A. E.; Posthuma, Danielle

    2014-01-01

    Over the past decades, numerous twin studies have revealed moderate to high heritability estimates for individual differences in a wide range of human traits, including cognitive ability, psychiatric disorders, and personality traits. Even factors that are generally believed to be environmental in nature have been shown to be under genetic control, albeit modest. Is such heritability also present in social traits that are conceptualized as causes and consequences of social interactions or in other ways strongly shaped by behavior of other people? Here we examine a population-based sample of 1,012 twins and relatives. We show that the genetic influence on generalized trust in other people (trust-in-others: h2 = 5%, ns), and beliefs regarding other people’s trust in the self (trust-in-self: h2 = 13%, ns), is virtually absent. As test-retest reliability for both scales were found to be moderate or high (r = .76 and r = .53, respectively) in an independent sample, we conclude that all variance in trust is likely to be accounted for by non-shared environmental influences. We show that, relative to cognitive abilities, psychiatric disorders, and classic personality variables, genetic influences are smaller for trust, and propose that experiences with or observations of the behavior of other people shape trust more strongly than other traits. PMID:24709897

  14. Regulation of dynein localization and centrosome positioning by Lis-1 and asunder during Drosophila spermatogenesis

    PubMed Central

    Sitaram, Poojitha; Anderson, Michael A.; Jodoin, Jeanne N.; Lee, Ethan; Lee, Laura A.

    2012-01-01

    Dynein, a microtubule motor complex, plays crucial roles in cell-cycle progression in many systems. The LIS1 accessory protein directly binds dynein, although its precise role in regulating dynein remains unclear. Mutation of human LIS1 causes lissencephaly, a developmental brain disorder. To gain insight into the in vivo functions of LIS1, we characterized a male-sterile allele of the Drosophila homolog of human LIS1. We found that centrosomes do not properly detach from the cell cortex at the onset of meiosis in most Lis-1 spermatocytes; centrosomes that do break cortical associations fail to attach to the nucleus. In Lis-1 spermatids, we observed loss of attachments between the nucleus, basal body and mitochondria. The localization pattern of LIS-1 protein throughout Drosophila spermatogenesis mirrors that of dynein. We show that dynein recruitment to the nuclear surface and spindle poles is severely reduced in Lis-1 male germ cells. We propose that Lis-1 spermatogenesis phenotypes are due to loss of dynein regulation, as we observed similar phenotypes in flies null for Tctex-1, a dynein light chain. We have previously identified asunder (asun) as another regulator of dynein localization and centrosome positioning during Drosophila spermatogenesis. We now report that Lis-1 is a strong dominant enhancer of asun and that localization of LIS-1 in male germ cells is ASUN dependent. We found that Drosophila LIS-1 and ASUN colocalize and coimmunoprecipitate from transfected cells, suggesting that they function within a common complex. We present a model in which Lis-1 and asun cooperate to regulate dynein localization and centrosome positioning during Drosophila spermatogenesis. PMID:22764052

  15. Communication about absent entities in great apes and human infants.

    PubMed

    Bohn, Manuel; Call, Josep; Tomasello, Michael

    2015-12-01

    There is currently debate about the extent to which non-linguistic beings such as human infants and great apes are capable of absent reference. In a series of experiments we investigated the flexibility and specificity of great apes' (N=36) and 12 month-old infants' (N=40) requests for absent entities. Subjects had the choice between requesting visible objects directly and using the former location of a depleted option to request more of these now-absent entities. Importantly, we systematically varied the quality of the present and absent options. We found that great apes as well as human infants flexibly adjusted their requests for absent entities to these contextual variations and only requested absent entities when the visible option was of lower quality than the absent option. These results suggest that the most basic cognitive capacities for absent reference do not depend on language and are shared by humans and their closest living relatives.

  16. Dynein light intermediate chains maintain spindle bipolarity by functioning in centriole cohesion.

    PubMed

    Jones, Laura A; Villemant, Cécile; Starborg, Toby; Salter, Anna; Goddard, Georgina; Ruane, Peter; Woodman, Philip G; Papalopulu, Nancy; Woolner, Sarah; Allan, Victoria J

    2014-11-24

    Cytoplasmic dynein 1 (dynein) is a minus end-directed microtubule motor protein with many cellular functions, including during cell division. The role of the light intermediate chains (LICs; DYNC1LI1 and 2) within the complex is poorly understood. In this paper, we have used small interfering RNAs or morpholino oligonucleotides to deplete the LICs in human cell lines and Xenopus laevis early embryos to dissect the LICs' role in cell division. We show that although dynein lacking LICs drives microtubule gliding at normal rates, the LICs are required for the formation and maintenance of a bipolar spindle. Multipolar spindles with poles that contain single centrioles were formed in cells lacking LICs, indicating that they are needed for maintaining centrosome integrity. The formation of multipolar spindles via centrosome splitting after LIC depletion could be rescued by inhibiting Eg5. This suggests a novel role for the dynein complex, counteracted by Eg5, in the maintenance of centriole cohesion during mitosis.

  17. Cytoplasmic Dynein Transports Cargos via Load-Sharing between the Heads

    PubMed Central

    Belyy, Vladislav; Hendel, Nathan L.; Chien, Alexander; Yildiz, Ahmet

    2014-01-01

    Cytoplasmic dynein is a motor protein that walks along microtubules (MTs) and performs mechanical work to power a variety of cellular processes. It remains unclear how a dynein dimer is able to transport cargos against load without coordinating the stepping cycles of its two heads. Here, by using a DNA-tethered optical trapping geometry, we find that the force-generating step of a head occurs in the MT-bound state, while the ‘primed’ unbound state is highly diffusional and only weakly biased to step towards the MT minus end. The stall forces of the individual heads are additive, with both heads contributing equally to the maximal force production of the dimer. Based on these results, we propose that the heads of dynein utilize a ‘load-sharing’ mechanism, unlike kinesin and myosin. This mechanism may allow dynein to work against hindering forces larger than the maximal force produced by a single head. PMID:25424027

  18. Mouse Cytoplasmic Dynein Intermediate Chains: Identification of New Isoforms, Alternative Splicing and Tissue Distribution of Transcripts

    PubMed Central

    Kuta, Anna; Deng, Wenhan; Morsi El-Kadi, Ali; Banks, Gareth T.; Hafezparast, Majid; Pfister, K. Kevin; Fisher, Elizabeth M. C.

    2010-01-01

    Background Intracellular transport of cargoes including organelles, vesicles, signalling molecules, protein complexes, and RNAs, is essential for normal function of eukaryotic cells. The cytoplasmic dynein complex is an important motor that moves cargos along microtubule tracks within the cell. In mammals this multiprotein complex includes dynein intermediate chains 1 and 2 which are encoded by two genes, Dync1i1 and Dync1i2. These proteins are involved in dynein cargo binding and dynein complexes with different intermediate chains bind to specific cargoes, although the mechanisms to achieve this are not known. The DYNC1I1 and DYNC1I2 proteins are translated from different splice isoforms, and specific forms of each protein are essential for the function of different dynein complexes in neurons. Methodology/Principal Findings Here we have undertaken a systematic survey of the dynein intermediate chain splice isoforms in mouse, basing our study on mRNA expression patterns in a range of tissues, and on bioinformatics analysis of mouse, rat and human genomic and cDNA sequences. We found a complex pattern of alternative splicing of both dynein intermediate chain genes, with maximum complexity in the embryonic and adult nervous system. We have found novel transcripts, including some with orthologues in human and rat, and a new promoter and alternative non-coding exon 1 for Dync1i2. Conclusions/Significance These data, including the cloned isoforms will be essential for understanding the role of intermediate chains in the cytoplasmic dynein complex, particularly their role in cargo binding within individual tissues including different brain regions. PMID:20657784

  19. Cytoplasmic dynein participates in the centrosomal localization of the Golgi complex

    PubMed Central

    1992-01-01

    The localization of the Golgi complex depends upon the integrity of the microtubule apparatus. At interphase, the Golgi has a restricted pericentriolar localization. During mitosis, it fragments into small vesicles that are dispersed throughout the cytoplasm until telophase, when they again coalesce near the centrosome. These observations have suggested that the Golgi complex utilizes a dynein-like motor to mediate its transport from the cell periphery towards the minus ends of microtubules, located at the centrosome. We utilized semi-intact cells to study the interaction of the Golgi complex with the microtubule apparatus. We show here that Golgi complexes can enter semi-intact cells and associate stably with cytoplasmic constituents. Stable association, termed here "Golgi capture," requires ATP hydrolysis and intact microtubules, and occurs maximally at physiological temperature in the presence of added cytosolic proteins. Once translocated into the semi-intact cell cytoplasm, exogenous Golgi complexes display a distribution similar to endogenous Golgi complexes, near the microtubule-organizing center. The process of Golgi capture requires cytoplasmic tubulin, and is abolished if cytoplasmic dynein is immunodepleted from the cytosol. Cytoplasmic dynein, prepared from CHO cell cytosol, restores Golgi capture activity to reactions carried out with dynein immuno-depleted cytosol. These results indicate that cytoplasmic dynein can interact with isolated Golgi complexes, and participate in their accumulation near the centrosomes of semi-intact, recipient cells. Thus, cytoplasmic dynein appears to play a role in determining the subcellular localization of the Golgi complex. PMID:1387874

  20. Characterization of ciliobrevin A mediated dynein ATPase inhibition on flagellar motility of Leishmania donovani.

    PubMed

    Reddy, G Srinivas; Mukhopadhyay, Aakash Gautam; Dey, Chinmoy Sankar

    2017-04-04

    Axonemal dyneins are members of AAA+ proteins involved in force generation and are responsible for flagellar motility in eukaryotes. In this study, we characterized the effects of ciliobrevin A (CbA), a dynein ATPase inhibitor, on flagella driven motility of the protozoan parasite Leishmania donovani. Using fast-capture video microscopy, we observed that CbA decreased flagellar beat frequency of swimming parasites in a concentration-dependent manner. Beat frequency of live and reactivated L. donovani decreased by approximately 89% and 41% respectively in the presence of 250μM CbA. This inhibition was lost when CbA was removed, suggesting its effects were reversible. CbA also altered wavelength and amplitude of the flagellum of live parasites. Waveform analysis of live and reactivated L. donovani revealed that CbA significantly affected flagellar waveform by inducing non-uniform bends with the flagellum beating away from the cell axis. These results suggest that CbA sensitive dynein ATPases possibly are responsible for power generation and waveform maintenance of the flagellum of L. donovani. This ability to inhibit axonemal dyneins also emphasizes the use of dynein inhibitors as valuable tools in studying functional roles of axonemal dyneins of flagellated eukaryotes.

  1. MCRS1 associates with cytoplasmic dynein and mediates pericentrosomal material recruitment

    PubMed Central

    Lee, Si-Hyung; Lee, Mi-Sun; Choi, Tae-Ik; Hong, Hyowon; Seo, Jun-Young; Kim, Cheol-Hee; Kim, Joon

    2016-01-01

    MCRS1 is involved in multiple cellular activities, including mitotic spindle assembly, mTOR signaling and tumorigenesis. Although MCRS1 has been reported to bind to the dynein regulator NDE1, a functional interaction between MCRS1 and cytoplasmic dynein remains unaddressed. Here, we demonstrate that MCRS1 is required for dynein-dependent cargo transport to the centrosome and also plays a role in primary cilium formation. MCRS1 localized to centriolar satellites. Knockdown of MCRS1 resulted in a dispersion of centriolar satellites whose establishment depends on cytoplasmic dynein. By contrast, NDE1 was not necessary for the proper distribution of centriolar satellites, indicating a functional distinction between MCRS1 and NDE1. Unlike NDE1, MCRS1 played a positive role for the initiation of ciliogenesis, possibly through its interaction with TTBK2. Zebrafish with homozygous mcrs1 mutants exhibited a reduction in the size of the brain and the eye due to excessive apoptosis. In addition, mcrs1 mutants failed to develop distinct layers in the retina, and showed a defect in melatonin-induced aggregation of melanosomes in melanophores. These phenotypes are reminiscent of zebrafish dynein mutants. Reduced ciliogenesis was also apparent in the olfactory placode of mcrs1 mutants. Collectively, our findings identify MCRS1 as a dynein-interacting protein critical for centriolar satellite formation and ciliogenesis. PMID:27263857

  2. The native structure of cytoplasmic dynein at work translocating vesicles in Paramecium.

    PubMed

    Ishida, Masaki; Aihara, Marilynn S; Allen, Richard D; Fok, Agnes K

    2011-01-01

    In Paramecium multimicronucleatum, the discoidal vesicles, the acidosomes and the 100-nm carrier vesicles are involved in phagosome formation, phagosome acidification and endosomal processing, respectively. Numerous cross bridges link these vesicles to the kinetic side of the microtubules of a cytopharyngeal microtubular ribbon. Vesicles are translocated along these ribbons in a minus-end direction towards the cytopharynx. A monoclonal antibody specific for the light vanadate-photocleaved fragment of the heavy chain of cytoplasmic dynein was used to show that this dynein is located between the discoidal vesicles and the ribbons as well as on the cytosolic surface of the acidosomes and the 100-nm carrier vesicles. This antibody inhibited the docking of the vesicles to the microtubular ribbons so that the transport of discoidal vesicles and acidosomes were reduced by 60% and 70%, respectively. It had little effect on the dynein's velocity of translocation. These results show that cytoplasmic dynein is the motor for vesicle translocation and its location, between the vesicles and the ribbons, indicates that the cross bridges seen at this location in thin sections and in quick-frozen, deep-etched replicas are apparently the working dyneins. Such a working dynein cross bridge, as preserved by ultra-rapid freezing, is 54 nm long and has two legs arising from a globular head that appears to be firmly bound to its cargo vesicle and each leg consists of ≥3 beaded subunits with the last subunit making contact with the microtubular ribbon.

  3. Fluorescent ATP analog mant-ATP reports dynein activity in the isolated Chlamydomonas axoneme

    NASA Astrophysics Data System (ADS)

    Feofilova, Maria; Howard, Jonathon

    Eukaryotic flagella are long rod-like extensions of cells, which play a fundamental role in single cell movement, as well as in fluid transport. Flagella contain a highly evolutionary conserved mechanical structure called the axoneme. The motion of the flagellum is generated by dynein motor proteins located all along the length of the axoneme. How the force production of motors is controlled spatially and temporally is still an open question. Therefore, monitoring dynein activity in the axonemal structure is expected to provide novel insights in regulation of the beat. We use high sensitivity fluorescence microscopy to monitor the binding and hydrolysis kinetics of the fluorescently labeled ATP analogue mant-ATP (2'(3')-O-(N-methylanthraniloyl) adenosine 5'-triphosphate), which is known to support dynein activity. By studying the kinetics of mant-ATP fluorescence, we identified distinct mant-ATP binding sites in the axoneme. The application of this method to axonemes with reduced amounts of dynein, showed evidence that one of the sites is associated with binding to dynein. In the future, we would like to use this method to find the spatial distribution of dynein activity in the axoneme.

  4. Interplay between kinesin-1 and cortical dynein during axonal outgrowth and microtubule organization in Drosophila neurons

    PubMed Central

    del Castillo, Urko; Winding, Michael; Lu, Wen; Gelfand, Vladimir I

    2015-01-01

    In this study, we investigated how microtubule motors organize microtubules in Drosophila neurons. We showed that, during the initial stages of axon outgrowth, microtubules display mixed polarity and minus-end-out microtubules push the tip of the axon, consistent with kinesin-1 driving outgrowth by sliding antiparallel microtubules. At later stages, the microtubule orientation in the axon switches from mixed to uniform polarity with plus-end-out. Dynein knockdown prevents this rearrangement and results in microtubules of mixed orientation in axons and accumulation of microtubule minus-ends at axon tips. Microtubule reorganization requires recruitment of dynein to the actin cortex, as actin depolymerization phenocopies dynein depletion, and direct recruitment of dynein to the membrane bypasses the actin requirement. Our results show that cortical dynein slides ‘minus-end-out’ microtubules from the axon, generating uniform microtubule arrays. We speculate that differences in microtubule orientation between axons and dendrites could be dictated by differential activity of cortical dynein. DOI: http://dx.doi.org/10.7554/eLife.10140.001 PMID:26615019

  5. Behavioural and other phenotypes in a cytoplasmic dynein light intermediate chain 1 mutant mouse

    PubMed Central

    Banks, Gareth T.; Haas, Matilda A.; Line, Samantha; Shepherd, Hazel L.; AlQatari, Mona; Stewart, Sammy; Rishal, Ida; Philpott, Amelia; Kalmar, Bernadett; Kuta, Anna; Groves, Michael; Parkinson, Nicholas; Acevedo-Arozena, Abraham; Brandner, Sebastian; Bannerman, David; Greensmith, Linda; Hafezparast, Majid; Koltzenburg, Martin; Deacon, Robert; Fainzilber, Mike; Fisher, Elizabeth M.C.

    2011-01-01

    The cytoplasmic dynein complex is fundamentally important to all eukaryotic cells for transporting a variety of essential cargoes along microtubules within the cell. This complex also plays more specialised roles in neurons. The complex consists of 11 types of protein that interact with each other and with external adaptors, regulators and cargoes. Despite the importance of the cytoplasmic dynein complex, we know comparatively little of the roles of each component protein, and in mammals few mutants exist that allow us to explore the effects of defects in dynein controlled processes in the context of the whole organism. Here we have taken a genotype-driven approach in mouse (Mus musculus) to analyse the role of one subunit, the dynein light intermediate chain 1 (Dync1li1). We find that, surprisingly, an N235Y point mutation in this protein results in altered neuronal development, as shown from in vivo studies in the developing cortex, and analyses of electrophysiological function. Moreover, mutant mice display increased anxiety, thus linking dynein functions to a behavioural phenotype in mammals for the first time. These results demonstrate the important role that dynein controlled processes play in the correct development and function of the mammalian nervous system. PMID:21471385

  6. Insulin signaling regulates a functional interaction between adenomatous polyposis coli and cytoplasmic dynein.

    PubMed

    Gao, Feng J; Shi, Liang; Hines, Timothy; Hebbar, Sachin; Neufeld, Kristi L; Smith, Deanna S

    2017-03-01

    Diabetes is linked to an increased risk for colorectal cancer, but the mechanistic underpinnings of this clinically important effect are unclear. Here we describe an interaction between the microtubule motor cytoplasmic dynein, the adenomatous polyposis coli tumor suppressor protein (APC), and glycogen synthase kinase-3β (GSK-3β), which could shed light on this issue. GSK-3β is perhaps best known for glycogen regulation, being inhibited downstream in an insulin-signaling pathway. However, the kinase is also important in many other processes. Mutations in APC that disrupt the regulation of β-catenin by GSK-3β cause colorectal cancer in humans. Of interest, both APC and GSK-3β interact with microtubules and cellular membranes. We recently demonstrated that dynein is a GSK-3β substrate and that inhibition of GSK-3β promotes dynein-dependent transport. We now report that dynein stimulation in intestinal cells in response to acute insulin exposure (or GSK-3β inhibition) is blocked by tumor-promoting isoforms of APC that reduce an interaction between wild-type APC and dynein. We propose that under normal conditions, insulin decreases dynein binding to APC to stimulate minus end-directed transport, which could modulate endocytic and secretory systems in intestinal cells. Mutations in APC likely impair the ability to respond appropriately to insulin signaling. This is exciting because it has the potential to be a contributing factor in the development of colorectal cancer in patients with diabetes.

  7. Robotic arm

    DOEpatents

    Kwech, Horst

    1989-04-18

    A robotic arm positionable within a nuclear vessel by access through a small diameter opening and having a mounting tube supported within the vessel and mounting a plurality of arm sections for movement lengthwise of the mounting tube as well as for movement out of a window provided in the wall of the mounting tube. An end effector, such as a grinding head or welding element, at an operating end of the robotic arm, can be located and operated within the nuclear vessel through movement derived from six different axes of motion provided by mounting and drive connections between arm sections of the robotic arm. The movements are achieved by operation of remotely-controllable servo motors, all of which are mounted at a control end of the robotic arm to be outside the nuclear vessel.

  8. Absent Aortic Valve in DiGeorge Syndrome.

    PubMed

    Bertsch, Elizabeth C; Minturn, Lucy; Gotteiner, Nina L; Ernst, Linda M

    2016-01-01

    A 20-week-old fetus with the 22q11.2 deletion characteristic of DiGeorge syndrome is described with vertebral segmentation abnormalities and complex cardiovascular anomalies including an absent aortic valve. This is only the second known case of absent aortic valve in association with DiGeorge syndrome. We discuss the association of absent aortic valve with other conotruncal defects and the utility of fetal echocardiography in the diagnosis of DiGeorge syndrome.

  9. Misfolded Gβ is recruited to cytoplasmic dynein by Nudel for efficient clearance

    PubMed Central

    Wan, Yihan; Yang, Zhenye; Guo, Jing; Zhang, Qiangge; Zeng, Liyong; Song, Wei; Xiao, Yue; Zhu, Xueliang

    2012-01-01

    The Gβγ heterodimer is an important signal transducer. Gβ, however, is prone to misfolding due to its requirement for Gγ and chaperones for proper folding. How cells dispose of misfolded Gβ (mfGβ) is not clear. Here, we showed that mfGβ was able to be polyubiquitinated and subsequently degraded by the proteasome. It was sequestered in aggresomes after the inhibition of the proteasome activity with MG132. Sustained activation of Gβγ signaling further elevated cellular levels of the ubiquitinated Gβ. Moreover, Nudel, a regulator of cytoplasmic dynein, the microtubule minus end-directed motor, directly interacted with both the unubiquitinated and ubiquitinated mfGβ. Increasing the levels of both mfGβ and Nudel promoted the association of Gβ with both Nudel and dynein, resulting in robust aggresome formation in a dynein-dependent manner. Depletion of Nudel by RNAi reduced the dynein-associated mfGβ, impaired the MG132-induced aggresome formation, and markedly prolonged the half-life of nascent Gβ. Therefore, cytosolic mfGβ is recruited to dynein by Nudel and transported to the centrosome for rapid sequestration and degradation. Such a process not only eliminates mfGβ efficiently for the control of protein quality, but may also help to terminate the Gβγ signaling. PMID:22430153

  10. Tuning microtubule-based transport via filamentous MAPs: the problem of dynein

    PubMed Central

    Vershinin, Michael; Xu, Jing; Razafsky, David S.; King, Stephen J.; Gross, Steven P.

    2010-01-01

    We recently proposed that regulating the single-to-multiple motor transition was a likely strategy for regulating kinesin-based transport in vivo. Here, we use an in vitro bead assay coupled with an optical trap to investigate how this proposed regulatory mechanism affects dynein-based transport. We show that tau’s regulation of kinesin function can proceed without interfering with dynein-based transport. Surprisingly, at extremely high tau levels—where kinesin cannot bind microtubules—dynein can still contact microtubules. The difference between tau’s effects on kinesin- and dynein-based motility suggests that tau can be used to tune relative amounts of plus-end and minus-end directed transport. As in the case of kinesin, we find that the 3RS isoform of tau is a more potent inhibitor of dynein binding to microtubules. We show that this isoform-specific effect is not due to steric interference of tau’s projection domains, but rather due to tau’s interactions with the motor at the microtubule surface. Nonetheless, we do observe a modest steric interference effect of tau away from the microtubule and discuss the potential implications of this for molecular motor structure. PMID:18373727

  11. DRC3 connects the N-DRC to dynein g to regulate flagellar waveform

    PubMed Central

    Awata, Junya; Song, Kangkang; Lin, Jianfeng; King, Stephen M.; Sanderson, Michael J.; Nicastro, Daniela; Witman, George B.

    2015-01-01

    The nexin-dynein regulatory complex (N-DRC), which is a major hub for the control of flagellar motility, contains at least 11 different subunits. A major challenge is to determine the location and function of each of these subunits within the N-DRC. We characterized a Chlamydomonas mutant defective in the N-DRC subunit DRC3. Of the known N-DRC subunits, the drc3 mutant is missing only DRC3. Like other N-DRC mutants, the drc3 mutant has a defect in flagellar motility. However, in contrast to other mutations affecting the N-DRC, drc3 does not suppress flagellar paralysis caused by loss of radial spokes. Cryo–electron tomography revealed that the drc3 mutant lacks a portion of the N-DRC linker domain, including the L1 protrusion, part of the distal lobe, and the connection between these two structures, thus localizing DRC3 to this part of the N-DRC. This and additional considerations enable us to assign DRC3 to the L1 protrusion. Because the L1 protrusion is the only non-dynein structure in contact with the dynein g motor domain in wild-type axonemes and this is the only N-DRC–dynein connection missing in the drc3 mutant, we conclude that DRC3 interacts with dynein g to regulate flagellar waveform. PMID:26063732

  12. Dynein mutations associated with hereditary motor neuropathies impair mitochondrial morphology and function with age.

    PubMed

    Eschbach, Judith; Sinniger, Jérôme; Bouitbir, Jamal; Fergani, Anissa; Schlagowski, Anna-Isabel; Zoll, Joffrey; Geny, Bernard; René, Frédérique; Larmet, Yves; Marion, Vincent; Baloh, Robert H; Harms, Matthew B; Shy, Michael E; Messadeq, Nadia; Weydt, Patrick; Loeffler, Jean-Philippe; Ludolph, Albert C; Dupuis, Luc

    2013-10-01

    Mutations in the DYNC1H1 gene encoding for dynein heavy chain cause two closely related human motor neuropathies, dominant spinal muscular atrophy with lower extremity predominance (SMA-LED) and axonal Charcot-Marie-Tooth (CMT) disease, and lead to sensory neuropathy and striatal atrophy in mutant mice. Dynein is the molecular motor carrying mitochondria retrogradely on microtubules, yet the consequences of dynein mutations on mitochondrial physiology have not been explored. Here, we show that mouse fibroblasts bearing heterozygous or homozygous point mutation in Dync1h1, similar to human mutations, show profoundly abnormal mitochondrial morphology associated with the loss of mitofusin 1. Furthermore, heterozygous Dync1h1 mutant mice display progressive mitochondrial dysfunction in muscle and mitochondria progressively increase in size and invade sarcomeres. As a likely consequence of systemic mitochondrial dysfunction, Dync1h1 mutant mice develop hyperinsulinemia and hyperglycemia and progress to glucose intolerance with age. Similar defects in mitochondrial morphology and mitofusin levels are observed in fibroblasts from patients with SMA-LED. Last, we show that Dync1h1 mutant fibroblasts show impaired perinuclear clustering of mitochondria in response to mitochondrial uncoupling. Our results show that dynein function is required for the maintenance of mitochondrial morphology and function with aging and suggest that mitochondrial dysfunction contributes to dynein-dependent neurological diseases, such as SMA-LED.

  13. Dynactin, a conserved, ubiquitously expressed component of an activator of vesicle motility mediated by cytoplasmic dynein

    PubMed Central

    1991-01-01

    Although cytoplasmic dynein is known to attach to microtubules and translocate toward their minus ends, dynein's ability to serve in vitro as a minus end-directed transporter of membranous organelles depends on additional soluble factors. We show here that a approximately 20S polypeptide complex (referred to as Activator I; Schroer, T. A., and M.P. Sheetz. 1991a. J. Cell Biol. 115:1309-1318.) stimulates dynein- mediated vesicle transport. A major component of the activator complex is a doublet of 150-kD polypeptides for which we propose the name dynactin (for dynein activator). The 20S dynactin complex is required for in vitro vesicle motility since depletion of it with a mAb to dynactin eliminates vesicle movement. Cloning of a brain specific isoform of dynactin from chicken reveals a 1,053 amino acid polypeptide composed of two coiled-coil alpha-helical domains interrupted by a spacer. Both this structural motif and the underlying primary sequence are highly conserved in vertebrates with 85% sequence identity within a central 1,000-residue domain of the chicken and rat proteins. As abundant as dynein, dynactin is ubiquitously expressed and appears to be encoded by a single gene that yields at least three alternative isoforms. The probable homologue in Drosophila is the gene Glued, whose protein product shares 50% sequence identity with vertebrate dynactin and whose function is essential for viability of most (and perhaps all) cells in the organism. PMID:1836789

  14. An analytical solution describing the propagation of positive injury signals in an axon: effect of dynein velocity distribution.

    PubMed

    Kuznetsov, A V

    2013-01-01

    A model describing the propagation of positive injury signals from the lesion site in an axon towards the neuron soma is described. It is assumed that these signals are driven by dynein molecular motors. An analytical solution that accounts for the probability density function (pdf) of a dynein velocity distribution is obtained. Two examples of pdf of dynein velocity distributions that follow from the results published in Ross et al. (2006, Processive bidirectional motion of dynein-dynactin complexes in vitro. Nat Cell Biol. 8:562-570) and Deinhardt et al. (2006, Rab5 and Rab7 control endocytic sorting along the axonal retrograde transport pathway. Neuron 52:293-305) are considered. The effect of dynein velocity distribution on the rate of spreading of the signal wave is discussed. It is demonstrated that the obtained solution can be applied to the problem of how neurons measure the distance between the lesion site and the neuron soma.

  15. Dynein Clusters into Lipid Microdomains on Phagosomes to Drive Rapid Transport toward Lysosomes

    PubMed Central

    Rai, Ashim; Pathak, Divya; Thakur, Shreyasi; Singh, Shampa; Dubey, Alok Kumar; Mallik, Roop

    2016-01-01

    Summary Diverse cellular processes are driven by motor proteins that are recruited to and generate force on lipid membranes. Surprisingly little is known about how membranes control the force from motors and how this may impact specific cellular functions. Here, we show that dynein motors physically cluster into microdomains on the membrane of a phagosome as it matures inside cells. Such geometrical reorganization allows many dyneins within a cluster to generate cooperative force on a single microtubule. This results in rapid directed transport of the phagosome toward microtubule minus ends, likely promoting phagolysosome fusion and pathogen degradation. We show that lipophosphoglycan, the major molecule implicated in immune evasion of Leishmania donovani, inhibits phagosome motion by disrupting the clustering and therefore the cooperative force generation of dynein. These findings appear relevant to several pathogens that prevent phagosome-lysosome fusion by targeting lipid microdomains on phagosomes. PMID:26853472

  16. Direct observation shows superposition and large scale flexibility within cytoplasmic dynein motors moving along microtubules

    NASA Astrophysics Data System (ADS)

    Imai, Hiroshi; Shima, Tomohiro; Sutoh, Kazuo; Walker, Matthew L.; Knight, Peter J.; Kon, Takahide; Burgess, Stan A.

    2015-09-01

    Cytoplasmic dynein is a dimeric AAA+ motor protein that performs critical roles in eukaryotic cells by moving along microtubules using ATP. Here using cryo-electron microscopy we directly observe the structure of Dictyostelium discoideum dynein dimers on microtubules at near-physiological ATP concentrations. They display remarkable flexibility at a hinge close to the microtubule binding domain (the stalkhead) producing a wide range of head positions. About half the molecules have the two heads separated from one another, with both leading and trailing motors attached to the microtubule. The other half have the two heads and stalks closely superposed in a front-to-back arrangement of the AAA+ rings, suggesting specific contact between the heads. All stalks point towards the microtubule minus end. Mean stalk angles depend on the separation between their stalkheads, which allows estimation of inter-head tension. These findings provide a structural framework for understanding dynein's directionality and unusual stepping behaviour.

  17. Direct observation shows superposition and large scale flexibility within cytoplasmic dynein motors moving along microtubules

    PubMed Central

    Imai, Hiroshi; Shima, Tomohiro; Sutoh, Kazuo; Walker, Matthew L.; Knight, Peter J.; Kon, Takahide; Burgess, Stan A.

    2015-01-01

    Cytoplasmic dynein is a dimeric AAA+ motor protein that performs critical roles in eukaryotic cells by moving along microtubules using ATP. Here using cryo-electron microscopy we directly observe the structure of Dictyostelium discoideum dynein dimers on microtubules at near-physiological ATP concentrations. They display remarkable flexibility at a hinge close to the microtubule binding domain (the stalkhead) producing a wide range of head positions. About half the molecules have the two heads separated from one another, with both leading and trailing motors attached to the microtubule. The other half have the two heads and stalks closely superposed in a front-to-back arrangement of the AAA+ rings, suggesting specific contact between the heads. All stalks point towards the microtubule minus end. Mean stalk angles depend on the separation between their stalkheads, which allows estimation of inter-head tension. These findings provide a structural framework for understanding dynein's directionality and unusual stepping behaviour. PMID:26365535

  18. asunder is required for dynein localization and dorsal fate determination during Drosophila oogenesis.

    PubMed

    Sitaram, Poojitha; Merkle, Julie A; Lee, Ethan; Lee, Laura A

    2014-02-01

    We previously showed that asunder (asun) is a critical regulator of dynein localization during Drosophila spermatogenesis. Because the expression of asun is much higher in Drosophila ovaries and early embryos than in testes, we herein sought to determine whether ASUN plays roles in oogenesis and/or embryogenesis. We characterized the female germline phenotypes of flies homozygous for a null allele of asun (asun(d93)). We find that asun(d93) females lay very few eggs and contain smaller ovaries with a highly disorganized arrangement of ovarioles in comparison to wild-type females. asun(d93) ovaries also contain a significant number of egg chambers with structural defects. A majority of the eggs laid by asun(d93) females are ventralized to varying degrees, from mild to severe; this ventralization phenotype may be secondary to defective localization of gurken transcripts, a dynein-regulated step, within asun(d93) oocytes. We find that dynein localization is aberrant in asun(d93) oocytes, indicating that ASUN is required for this process in both male and female germ cells. In addition to the loss of gurken mRNA localization, asun(d93) ovaries exhibit defects in other dynein-mediated processes such as migration of nurse cell centrosomes into the oocyte during the early mitotic divisions, maintenance of the oocyte nucleus in the anterior-dorsal region of the oocyte in late-stage egg chambers, and coupling between the oocyte nucleus and centrosomes. Taken together, our data indicate that asun is a critical regulator of dynein localization and dynein-mediated processes during Drosophila oogenesis.

  19. Arm CT scan

    MedlinePlus

    CAT scan - arm; Computed axial tomography scan - arm; Computed tomography scan - arm; CT scan - arm ... scanners can perform the exam without stopping.) A computer creates separate images of the arm area, called ...

  20. Molecular mechanism of dynein recruitment to kinetochores by the Rod-Zw10-Zwilch complex and Spindly.

    PubMed

    Gama, José B; Pereira, Cláudia; Simões, Patrícia A; Celestino, Ricardo; Reis, Rita M; Barbosa, Daniel J; Pires, Helena R; Carvalho, Cátia; Amorim, João; Carvalho, Ana X; Cheerambathur, Dhanya K; Gassmann, Reto

    2017-04-03

    The molecular motor dynein concentrates at the kinetochore region of mitotic chromosomes in animals to accelerate spindle microtubule capture and to control spindle checkpoint signaling. In this study, we describe the molecular mechanism used by the Rod-Zw10-Zwilch complex and the adaptor Spindly to recruit dynein to kinetochores in Caenorhabditis elegans embryos and human cells. We show that Rod's N-terminal β-propeller and the associated Zwilch subunit bind Spindly's C-terminal domain, and we identify a specific Zwilch mutant that abrogates Spindly and dynein recruitment in vivo and Spindly binding to a Rod β-propeller-Zwilch complex in vitro. Spindly's N-terminal coiled-coil uses distinct motifs to bind dynein light intermediate chain and the pointed-end complex of dynactin. Mutations in these motifs inhibit assembly of a dynein-dynactin-Spindly complex, and a null mutant of the dynactin pointed-end subunit p27 prevents kinetochore recruitment of dynein-dynactin without affecting other mitotic functions of the motor. Conservation of Spindly-like motifs in adaptors involved in intracellular transport suggests a common mechanism for linking dynein to cargo.

  1. Disruption of the dynein-dynactin complex unveils motor-specific functions in osteoclast formation and bone resorption.

    PubMed

    Ng, Pei Ying; Cheng, Tak Sum; Zhao, Haibo; Ye, Shiqiao; Sm Ang, Estabelle; Khor, Ee Cheng; Feng, Hao-Tian; Xu, Jiake; Zheng, Ming H; Pavlos, Nathan J

    2013-01-01

    Osteoclastic bone resorption requires strict interplay between acidified carrier vesicles, motor proteins, and the underlying cytoskeleton in order to sustain the specialized structural and functional polarization of the ruffled border. Cytoplasmic dynein, a large processive mechanochemical motor comprising heavy, intermediate, and light chains coupled to the dynactin cofactor complex, powers unilateral motility of diverse cargos to microtubule minus-ends. We have recently shown that regulators of the dynein motor complex constitute critical components of the osteoclastic bone resorptive machinery. Here, by selectively modulating endogenous dynein activity, we show that the integrity of the dynein-dynactin motor complex is an essential requirement for both osteoclast formation and function. Systematic dissection of the osteoclast dynein-dynactin complex revealed that it is differentially localized throughout RANKL-induced osteoclast formation and activation, undergoing microtubule-coupled reorganization upon the establishment of cellular polarization. In osteoclasts actively resorbing bone, dynein-dynactin intimately co-localizes with the CAP-Gly domain-containing microtubule plus-end protein CLIP-170 at the resorptive front, thus orientating the ruffled border as a microtubule plus-end domain. Unexpectedly, disruption of the dynein-dynactin complex by exogenous p50/dynamitin expression retards osteoclast formation in vitro, owing largely to prolonged mitotic stasis of osteoclast progenitor cells. More importantly, loss of osteoclastic dynein activity results in a drastic redistribution of key intracellular organelles, including the Golgi and lysosomes, an effect that coincides with impaired cathepsin K secretion and diminished bone resorptive function. Collectively, these data unveil a previously unrecognized role for the dynein-dynactin motor complex in osteoclast formation and function, serving not only to regulate their timely maturation but also the delivery

  2. DYNC1H1 mutations associated with neurological diseases compromise processivity of dynein-dynactin-cargo adaptor complexes.

    PubMed

    Hoang, Ha Thi; Schlager, Max A; Carter, Andrew P; Bullock, Simon L

    2017-02-28

    Mutations in the human DYNC1H1 gene are associated with neurological diseases. DYNC1H1 encodes the heavy chain of cytoplasmic dynein-1, a 1.4-MDa motor complex that traffics organelles, vesicles, and macromolecules toward microtubule minus ends. The effects of the DYNC1H1 mutations on dynein motility, and consequently their links to neuropathology, are not understood. Here, we address this issue using a recombinant expression system for human dynein coupled to single-molecule resolution in vitro motility assays. We functionally characterize 14 DYNC1H1 mutations identified in humans diagnosed with malformations in cortical development (MCD) or spinal muscular atrophy with lower extremity predominance (SMALED), as well as three mutations that cause motor and sensory defects in mice. Two of the human mutations, R1962C and H3822P, strongly interfere with dynein's core mechanochemical properties. The remaining mutations selectively compromise the processive mode of dynein movement that is activated by binding to the accessory complex dynactin and the cargo adaptor Bicaudal-D2 (BICD2). Mutations with the strongest effects on dynein motility in vitro are associated with MCD. The vast majority of mutations do not affect binding of dynein to dynactin and BICD2 and are therefore expected to result in linkage of cargos to dynein-dynactin complexes that have defective long-range motility. This observation offers an explanation for the dominant effects of DYNC1H1 mutations in vivo. Collectively, our results suggest that compromised processivity of cargo-motor assemblies contributes to human neurological disease and provide insight into the influence of different regions of the heavy chain on dynein motility.

  3. Minimal Absent Words in Four Human Genome Assemblies

    PubMed Central

    Garcia, Sara P.; Pinho, Armando J.

    2011-01-01

    Minimal absent words have been computed in genomes of organisms from all domains of life. Here, we aim to contribute to the catalogue of human genomic variation by investigating the variation in number and content of minimal absent words within a species, using four human genome assemblies. We compare the reference human genome GRCh37 assembly, the HuRef assembly of the genome of Craig Venter, the NA12878 assembly from cell line GM12878, and the YH assembly of the genome of a Han Chinese individual. We find the variation in number and content of minimal absent words between assemblies more significant for large and very large minimal absent words, where the biases of sequencing and assembly methodologies become more pronounced. Moreover, we find generally greater similarity between the human genome assemblies sequenced with capillary-based technologies (GRCh37 and HuRef) than between the human genome assemblies sequenced with massively parallel technologies (NA12878 and YH). Finally, as expected, we find the overall variation in number and content of minimal absent words within a species to be generally smaller than the variation between species. PMID:22220210

  4. Recruitment of CG-NAP to the Golgi apparatus through interaction with dynein-dynactin complex.

    PubMed

    Kim, Hon-Song; Takahashi, Mikiko; Matsuo, Kazuhiko; Ono, Yoshitaka

    2007-03-01

    The structural organization and position of the Golgi apparatus are highly regulated by microtubule cytoskeleton and microtubule motor proteins. The mechanisms linking these proteins to the Golgi apparatus remain elusive. Here, we found that centrosome and Golgi-localized PKN associated protein (CG-NAP) was localized to the Golgi apparatus in a microtubule-dependent manner. Microtubule-binding experiments revealed that CG-NAP possessed two microtubule-binding domains. We also found that CG-NAP was well co-localized with cytoplasmic dynein subunits during recovery from the on-ice treatment of cells that induced dissociation of CG-NAP from the Golgi. Similar co-localization was observed during recovery from the acetate treatment, which has been reported to inhibit the dynein-mediated transport. CG-NAP was co-immunoprecipitated with a dynactin subunit p150(Glued). Expressing the p150(Glued)-binding region of CG-NAP fused with mitochondria-targeting sequence induced recruitment of mitochondria to the pericentriolar area, suggesting that this region interacts with functional cytoplasmic dynein in vivo. Moreover, over-expression of this region caused fragmentation of the Golgi similar to that of dynamitin. These results suggest that CG-NAP is recruited to the minus ends of microtubules by interacting with cytoplasmic dynein, thereby localizes to the Golgi apparatus in a microtubule-dependent manner and possibly involved in the formation of the Golgi near the centrosomes.

  5. End-on microtubule-dynein interactions and pulling-based positioning of microtubule organizing centers

    PubMed Central

    Laan, Liedewij; Roth, Sophie; Dogterom, Marileen

    2012-01-01

    During important cellular processes such as centrosome and spindle positioning, dynein at the cortex interacts with dynamic microtubules in an apparent “end-on” fashion. It is well-established that dynein can generate forces by moving laterally along the microtubule lattice, but much less is known about dynein’s interaction with dynamic microtubule ends. In this paper, we review recent in vitro experiments that show that dynein, attached to an artificial cortex, is able to capture microtubule ends, regulate microtubule dynamics and mediate the generation of pulling forces on shrinking microtubules. We further review existing ideas on the involvement of dynein-mediated cortical pulling forces in the positioning of microtubule organizing centers such as centrosomes. Recent in vitro experiments have demonstrated that cortical pulling forces in combination with pushing forces can lead to reliable centering of microtubule asters in quasi two-dimensional microfabricated chambers. In these experiments, pushing leads to slipping of microtubule ends along the chamber boundaries, resulting in an anisotropic distribution of cortical microtubule contacts that favors centering, once pulling force generators become engaged. This effect is predicted to be strongly geometry-dependent, and we therefore finally discuss ongoing efforts to repeat these experiments in three-dimensional, spherical and deformable geometries. PMID:22895049

  6. Dynein light intermediate chains maintain spindle bipolarity by functioning in centriole cohesion

    PubMed Central

    Jones, Laura A.; Villemant, Cécile; Starborg, Toby; Salter, Anna; Goddard, Georgina; Ruane, Peter; Woodman, Philip G.; Papalopulu, Nancy

    2014-01-01

    Cytoplasmic dynein 1 (dynein) is a minus end–directed microtubule motor protein with many cellular functions, including during cell division. The role of the light intermediate chains (LICs; DYNC1LI1 and 2) within the complex is poorly understood. In this paper, we have used small interfering RNAs or morpholino oligonucleotides to deplete the LICs in human cell lines and Xenopus laevis early embryos to dissect the LICs’ role in cell division. We show that although dynein lacking LICs drives microtubule gliding at normal rates, the LICs are required for the formation and maintenance of a bipolar spindle. Multipolar spindles with poles that contain single centrioles were formed in cells lacking LICs, indicating that they are needed for maintaining centrosome integrity. The formation of multipolar spindles via centrosome splitting after LIC depletion could be rescued by inhibiting Eg5. This suggests a novel role for the dynein complex, counteracted by Eg5, in the maintenance of centriole cohesion during mitosis. PMID:25422374

  7. Neuromuscular junction defects in mice with mutation of dynein heavy chain 1.

    PubMed

    Courchesne, Stephanie L; Pazyra-Murphy, Maria F; Lee, Daniel J; Segal, Rosalind A

    2011-02-04

    Disruptions in axonal transport have been implicated in a wide range of neurodegenerative diseases. Cramping 1 (Cra1/+) and Legs at odd angles (Loa/+) mice, with hypomorphic mutations in the dynein heavy chain 1 gene, which encodes the ATPase of the retrograde motor protein dynein, were originally reported to exhibit late onset motor neuron disease. Subsequent, conflicting reports suggested that sensory neuron disease without motor neuron loss underlies the phenotypes of Cra1/+ and Loa/+ mice. Here, we present behavioral and anatomical analyses of Cra1/+ mice. We demonstrate that Cra1/+ mice exhibit early onset, stable behavioral deficits, including abnormal hindlimb posturing and decreased grip strength. These deficits do not progress through 24 months of age. No significant loss of primary motor neurons or dorsal root ganglia sensory neurons was observed at ages where the mice exhibited clear symptomatology. Instead, there is a decrease in complexity of neuromuscular junctions. These results indicate that disruption of dynein function in Cra1/+ mice results in abnormal morphology of neuromuscular junctions. The time course of behavioral deficits, as well as the nature of the morphological defects in neuromuscular junctions, suggests that disruption of dynein function in Cra1/+ mice causes a developmental defect in synapse assembly or stabilization.

  8. Neuromuscular Junction Defects in Mice with Mutation of dynein heavy chain 1

    PubMed Central

    Lee, Daniel J.; Segal, Rosalind A.

    2011-01-01

    Disruptions in axonal transport have been implicated in a wide range of neurodegenerative diseases. Cramping 1 (Cra1/+) and Legs at odd angles (Loa/+) mice, with hypomorphic mutations in the dynein heavy chain 1 gene, which encodes the ATPase of the retrograde motor protein dynein, were originally reported to exhibit late onset motor neuron disease. Subsequent, conflicting reports suggested that sensory neuron disease without motor neuron loss underlies the phenotypes of Cra1/+ and Loa/+ mice. Here, we present behavioral and anatomical analyses of Cra1/+ mice. We demonstrate that Cra1/+ mice exhibit early onset, stable behavioral deficits, including abnormal hindlimb posturing and decreased grip strength. These deficits do not progress through 24 months of age. No significant loss of primary motor neurons or dorsal root ganglia sensory neurons was observed at ages where the mice exhibited clear symptomatology. Instead, there is a decrease in complexity of neuromuscular junctions. These results indicate that disruption of dynein function in Cra1/+ mice results in abnormal morphology of neuromuscular junctions. The time course of behavioral deficits, as well as the nature of the morphological defects in neuromuscular junctions, suggests that disruption of dynein function in Cra1/+ mice causes a developmental defect in synapse assembly or stabilization. PMID:21346813

  9. Exploitation of microtubule cytoskeleton and dynein during parvoviral traffic toward the nucleus.

    PubMed

    Suikkanen, Sanna; Aaltonen, Tuula; Nevalainen, Marjukka; Välilehto, Outi; Lindholm, Laura; Vuento, Matti; Vihinen-Ranta, Maija

    2003-10-01

    Canine parvovirus (CPV), a model virus for the study of parvoviral entry, enters host cells by receptor-mediated endocytosis, escapes from endosomal vesicles to the cytosol, and then replicates in the nucleus. We examined the role of the microtubule (MT)-mediated cytoplasmic trafficking of viral particles toward the nucleus. Immunofluorescence and immunoelectron microscopy showed that capsids were transported through the cytoplasm into the nucleus after cytoplasmic microinjection but that in the presence of MT-depolymerizing agents, viral capsids were unable to reach the nucleus. The nuclear accumulation of capsids was also reduced by microinjection of an anti-dynein antibody. Moreover, electron microscopy and light microscopy experiments demonstrated that viral capsids associate with tubulin and dynein in vitro. Coprecipitation studies indicated that viral capsids interact with dynein. When the cytoplasmic transport process was studied in living cells by microinjecting fluorescently labeled capsids into the cytoplasm of cells containing fluorescent tubulin, capsids were found in close contact with MTs. These results suggest that intact MTs and the motor protein dynein are required for the cytoplasmic transport of CPV capsids and contribute to the accumulation of the capsid in the nucleus.

  10. Exploitation of Microtubule Cytoskeleton and Dynein during Parvoviral Traffic toward the Nucleus

    PubMed Central

    Suikkanen, Sanna; Aaltonen, Tuula; Nevalainen, Marjukka; Välilehto, Outi; Lindholm, Laura; Vuento, Matti; Vihinen-Ranta, Maija

    2003-01-01

    Canine parvovirus (CPV), a model virus for the study of parvoviral entry, enters host cells by receptor-mediated endocytosis, escapes from endosomal vesicles to the cytosol, and then replicates in the nucleus. We examined the role of the microtubule (MT)-mediated cytoplasmic trafficking of viral particles toward the nucleus. Immunofluorescence and immunoelectron microscopy showed that capsids were transported through the cytoplasm into the nucleus after cytoplasmic microinjection but that in the presence of MT-depolymerizing agents, viral capsids were unable to reach the nucleus. The nuclear accumulation of capsids was also reduced by microinjection of an anti-dynein antibody. Moreover, electron microscopy and light microscopy experiments demonstrated that viral capsids associate with tubulin and dynein in vitro. Coprecipitation studies indicated that viral capsids interact with dynein. When the cytoplasmic transport process was studied in living cells by microinjecting fluorescently labeled capsids into the cytoplasm of cells containing fluorescent tubulin, capsids were found in close contact with MTs. These results suggest that intact MTs and the motor protein dynein are required for the cytoplasmic transport of CPV capsids and contribute to the accumulation of the capsid in the nucleus. PMID:12970411

  11. SNX4 in Complex with Clathrin and Dynein: Implications for Endosome Movement

    PubMed Central

    Skånland, Sigrid S.; Wälchli, Sébastien; Brech, Andreas; Sandvig, Kirsten

    2009-01-01

    Background Sorting nexins (SNXs) constitute a family of proteins classified by their phosphatidylinositol (PI) binding Phox homology (PX) domain. Some members regulate intracellular trafficking. We have here investigated mechanisms underlying SNX4 mediated endosome to Golgi transport. Methodology/Principal Findings We show that SNX4 forms complexes with clathrin and dynein. The interactions were inhibited by wortmannin, a PI3-kinase inhibitor, suggesting that they form when SNX4 is associated with PI(3)P on endosomes. We further localized the clathrin interacting site on SNX4 to a clathrin box variant. A short peptide containing this motif was sufficient to pull down both clathrin and dynein. Knockdown studies demonstrated that clathrin is not required for the SNX4/dynein interaction. Moreover, clathrin knockdown led to increased Golgi transport of the toxin ricin, as well as redistribution of endosomes. Conclusions/Significance We discuss the possibility of clathrin serving as a regulator of SNX4-dependent transport. Upon clathrin release, dynein may bind SNX4 and mediate retrograde movement. PMID:19529763

  12. The role of the dynein light intermediate chain in retrograde IFT and flagellar function in Chlamydomonas.

    PubMed

    Reck, Jaimee; Schauer, Alexandria M; VanderWaal Mills, Kristyn; Bower, Raqual; Tritschler, Douglas; Perrone, Catherine A; Porter, Mary E

    2016-08-01

    The assembly of cilia and flagella depends on the activity of two microtubule motor complexes, kinesin-2 and dynein-2/1b, but the specific functions of the different subunits are poorly defined. Here we analyze Chlamydomonas strains expressing different amounts of the dynein 1b light intermediate chain (D1bLIC). Disruption of D1bLIC alters the stability of the dynein 1b complex and reduces both the frequency and velocity of retrograde intraflagellar transport (IFT), but it does not eliminate retrograde IFT. Flagellar assembly, motility, gliding, and mating are altered in a dose-dependent manner. iTRAQ-based proteomics identifies a small subset of proteins that are significantly reduced or elevated in d1blic flagella. Transformation with D1bLIC-GFP rescues the mutant phenotypes, and D1bLIC-GFP assembles into the dynein 1b complex at wild-type levels. D1bLIC-GFP is transported with anterograde IFT particles to the flagellar tip, dissociates into smaller particles, and begins processive retrograde IFT in <2 s. These studies demonstrate the role of D1bLIC in facilitating the recycling of IFT subunits and other proteins, identify new components potentially involved in the regulation of IFT, flagellar assembly, and flagellar signaling, and provide insight into the role of D1bLIC and retrograde IFT in other organisms.

  13. Steady dynein forces induce flutter instability and propagating waves in mathematical models of flagella.

    PubMed

    Bayly, P V; Dutcher, S K

    2016-10-01

    Cilia and flagella are highly conserved organelles that beat rhythmically with propulsive, oscillatory waveforms. The mechanism that produces these autonomous oscillations remains a mystery. It is widely believed that dynein activity must be dynamically regulated (switched on and off, or modulated) on opposite sides of the axoneme to produce oscillations. A variety of regulation mechanisms have been proposed based on feedback from mechanical deformation to dynein force. In this paper, we show that a much simpler interaction between dynein and the passive components of the axoneme can produce coordinated, propulsive oscillations. Steady, distributed axial forces, acting in opposite directions on coupled beams in viscous fluid, lead to dynamic structural instability and oscillatory, wave-like motion. This 'flutter' instability is a dynamic analogue to the well-known static instability, buckling. Flutter also occurs in slender beams subjected to tangential axial loads, in aircraft wings exposed to steady air flow and in flexible pipes conveying fluid. By analysis of the flagellar equations of motion and simulation of structural models of flagella, we demonstrate that dynein does not need to switch direction or inactivate to produce autonomous, propulsive oscillations, but must simply pull steadily above a critical threshold force.

  14. The role of the dynein light intermediate chain in retrograde IFT and flagellar function in Chlamydomonas

    PubMed Central

    Reck, Jaimee; Schauer, Alexandria M.; VanderWaal Mills, Kristyn; Bower, Raqual; Tritschler, Douglas; Perrone, Catherine A.; Porter, Mary E.

    2016-01-01

    The assembly of cilia and flagella depends on the activity of two microtubule motor complexes, kinesin-2 and dynein-2/1b, but the specific functions of the different subunits are poorly defined. Here we analyze Chlamydomonas strains expressing different amounts of the dynein 1b light intermediate chain (D1bLIC). Disruption of D1bLIC alters the stability of the dynein 1b complex and reduces both the frequency and velocity of retrograde intraflagellar transport (IFT), but it does not eliminate retrograde IFT. Flagellar assembly, motility, gliding, and mating are altered in a dose-dependent manner. iTRAQ-based proteomics identifies a small subset of proteins that are significantly reduced or elevated in d1blic flagella. Transformation with D1bLIC-GFP rescues the mutant phenotypes, and D1bLIC-GFP assembles into the dynein 1b complex at wild-type levels. D1bLIC-GFP is transported with anterograde IFT particles to the flagellar tip, dissociates into smaller particles, and begins processive retrograde IFT in <2 s. These studies demonstrate the role of D1bLIC in facilitating the recycling of IFT subunits and other proteins, identify new components potentially involved in the regulation of IFT, flagellar assembly, and flagellar signaling, and provide insight into the role of D1bLIC and retrograde IFT in other organisms. PMID:27251063

  15. WD60/FAP163 is a dynein intermediate chain required for retrograde intraflagellar transport in cilia

    PubMed Central

    Patel-King, Ramila S.; Gilberti, Renée M.; Hom, Erik F. Y.; King, Stephen M.

    2013-01-01

    Retrograde intraflagellar transport (IFT) is required for assembly of cilia. We identify a Chlamydomonas flagellar protein (flagellar-associated protein 163 [FAP163]) as being closely related to the D1bIC(FAP133) intermediate chain (IC) of the dynein that powers this movement. Biochemical analysis revealed that FAP163 is present in the flagellar matrix and is actively trafficked by IFT. Furthermore, FAP163 copurified with D1bIC(FAP133) and the LC8 dynein light chain, indicating that it is an integral component of the retrograde IFT dynein. To assess the functional role of FAP163, we generated an RNA interference knockdown of the orthologous protein (WD60) in planaria. The Smed-wd60(RNAi) animals had a severe ciliary assembly defect that dramatically compromised whole-organism motility. Most cilia were present as short stubs that had accumulated large quantities of IFT particle–like material between the doublet microtubules and the membrane. The few remaining approximately full-length cilia had a chaotic beat with a frequency reduced from 24 to ∼10 Hz. Thus WD60/FAP163 is a dynein IC that is absolutely required for retrograde IFT and ciliary assembly. PMID:23864713

  16. WD60/FAP163 is a dynein intermediate chain required for retrograde intraflagellar transport in cilia.

    PubMed

    Patel-King, Ramila S; Gilberti, Renée M; Hom, Erik F Y; King, Stephen M

    2013-09-01

    Retrograde intraflagellar transport (IFT) is required for assembly of cilia. We identify a Chlamydomonas flagellar protein (flagellar-associated protein 163 [FAP163]) as being closely related to the D1bIC(FAP133) intermediate chain (IC) of the dynein that powers this movement. Biochemical analysis revealed that FAP163 is present in the flagellar matrix and is actively trafficked by IFT. Furthermore, FAP163 copurified with D1bIC(FAP133) and the LC8 dynein light chain, indicating that it is an integral component of the retrograde IFT dynein. To assess the functional role of FAP163, we generated an RNA interference knockdown of the orthologous protein (WD60) in planaria. The Smed-wd60(RNAi) animals had a severe ciliary assembly defect that dramatically compromised whole-organism motility. Most cilia were present as short stubs that had accumulated large quantities of IFT particle-like material between the doublet microtubules and the membrane. The few remaining approximately full-length cilia had a chaotic beat with a frequency reduced from 24 to ∼10 Hz. Thus WD60/FAP163 is a dynein IC that is absolutely required for retrograde IFT and ciliary assembly.

  17. Building Blocks of the Nexin-Dynein Regulatory Complex in Chlamydomonas Flagella*

    PubMed Central

    Lin, Jianfeng; Tritschler, Douglas; Song, Kangkang; Barber, Cynthia F.; Cobb, Jennifer S.; Porter, Mary E.; Nicastro, Daniela

    2011-01-01

    The directional flow generated by motile cilia and flagella is critical for many processes, including human development and organ function. Normal beating requires the control and coordination of thousands of dynein motors, and the nexin-dynein regulatory complex (N-DRC) has been identified as an important regulatory node for orchestrating dynein activity. The nexin link appears to be critical for the transformation of dynein-driven, linear microtubule sliding to flagellar bending, yet the molecular composition and mechanism of the N-DRC remain largely unknown. Here, we used proteomics with special attention to protein phosphorylation to analyze the composition of the N-DRC and to determine which subunits may be important for signal transduction. Two-dimensional electrophoresis and MALDI-TOF mass spectrometry of WT and mutant flagellar axonemes from Chlamydomonas identified 12 N-DRC-associated proteins, including all seven previously observed N-DRC components. Sequence and PCR analyses identified the mutation responsible for the phenotype of the sup-pf-4 strain, and biochemical comparison with a radial spoke mutant revealed two components that may link the N-DRC and the radial spokes. Phosphoproteomics revealed eight proteins with phosphorylated isoforms for which the isoform patterns changed with the genotype as well as two components that may play pivotal roles in N-DRC function through their phosphorylation status. These data were assembled into a model of the N-DRC that explains aspects of its regulatory function. PMID:21700706

  18. Overexpression of cytoplasmic dynein's globular head causes a collapse of the interphase microtubule network in Dictyostelium.

    PubMed Central

    Koonce, M P; Samsó, M

    1996-01-01

    Cytoplasmic dynein is a minus-end directed microtubule-based motor. Using a molecular genetic approach, we have begun to dissect structure-function relationships of dynein in the cellular slime mold Dictyostelium. Expression of a carboxy-terminal 380-kDa fragment of the heavy chain produces a protein that approximates the size and shape of the globular, mechanochemical head of dynein. This polypeptide cosediments with microtubules in an ATP-sensitive fashion and undergoes a UV-vanadate cleavage reaction. The deleted amino-terminal region appears to participate in dimerization of the native protein and in binding the intermediate and light chains. Overexpression of the 380-kDa carboxy-terminal construct in Dictyostelium produces a distinct phenotype in which the interphase radial microtubule array appears collapsed. In many cells, the microtubules form loose bundles that are whorled around the nucleus. Similar expression of a central 107-kDa fragment of the heavy chain does not produce this result. The data presented here suggest that dynein may participate in maintaining the spatial pattern of the interphase microtubule network. Images PMID:8816999

  19. FHIP and FTS proteins are critical for dynein-mediated transport of early endosomes in Aspergillus

    PubMed Central

    Yao, Xuanli; Wang, Xiangfeng; Xiang, Xin

    2014-01-01

    The minus end–directed microtubule motor cytoplasmic dynein transports various cellular cargoes, including early endosomes, but how dynein binds to its cargo remains unclear. Recently fungal Hook homologues were found to link dynein to early endosomes for their transport. Here we identified FhipA in Aspergillus nidulans as a key player for HookA (A. nidulans Hook) function via a genome-wide screen for mutants defective in early-endosome distribution. The human homologue of FhipA, FHIP, is a protein in the previously discovered FTS/Hook/FHIP (FHF) complex, which contains, besides FHIP and Hook proteins, Fused Toes (FTS). Although this complex was not previously shown to be involved in dynein-mediated transport, we show here that loss of either FhipA or FtsA (A. nidulans FTS homologue) disrupts HookA–early endosome association and inhibits early endosome movement. Both FhipA and FtsA associate with early endosomes, and interestingly, while FtsA–early endosome association requires FhipA and HookA, FhipA–early endosome association is independent of HookA and FtsA. Thus FhipA is more directly linked to early endosomes than HookA and FtsA. However, in the absence of HookA or FtsA, FhipA protein level is significantly reduced. Our results indicate that all three proteins in the FtsA/HookA/FhipA complex are important for dynein-mediated early endosome movement. PMID:24870033

  20. Alcohol-induced defects in hepatic transcytosis may be explained by impaired dynein function

    PubMed Central

    Groebner, Jennifer L.; Fernandez, David J.; Tuma, Dean J.; Tuma, Pamela L.

    2016-01-01

    Alcoholic liver disease has been clinically well described, but the molecular mechanisms leading to hepatotoxicity have not been fully elucidated. Previously, we determined that microtubules are hyperacetylated and more stable in ethanol-treated WIF-B cells, VL-17A cells, liver slices, and in livers from ethanol-fed rats. From our recent studies, we believe that these modifications can explain alcohol-induced defects in microtubule motor-dependent protein trafficking including nuclear translocation of a subset of transcription factors. Since cytoplasmic dynein/dynactin is known to mediate both microtubule-dependent translocation and basolateral to apical/canalicular transcytosis, we predicted that transcytosis is impaired in ethanol-treated hepatic cells. We monitored transcytosis of three classes of newly synthesized canalicular proteins in polarized, hepatic WIF-B cells, an emerging model system for the study of liver disease. As predicted, canalicular delivery of all proteins tested was impaired in ethanol-treated cells. Unlike in control cells, transcytosing proteins were observed in discrete sub-canalicular puncta en route to the canalicular surface that aligned along acetylated microtubules. We further determined that the stalled transcytosing proteins colocalized with dynein/dynactin in treated cells. No changes in vesicle association were observed for either dynein or dynactin in ethanol-treated cells, but significantly enhanced dynein binding to micro-tubules was observed. From these results, we propose that enhanced dynein binding to microtubules in ethanol-treated cells leads to decreased motor processivity resulting in vesicle stalling and in impaired canalicular delivery. Our studies also importantly indicate that modulating cellular acetylation levels with clinically tolerated deacetylase agonists may be a novel therapeutic strategy for treating alcoholic liver disease. PMID:25148871

  1. Absent and Accounted For: Absenteeism and Cooperative Learning

    ERIC Educational Resources Information Center

    Koppenhaver, G. D.

    2006-01-01

    In a small section collaborative learning environment where student work teams promote mutual learning about investments, students limit the opportunity to learn from other students if they are absent from class. Absenteeism not only denies the student the opportunity to learn from others but also denies other members of the student's work team…

  2. The Production of Present and Absent Presences in Education

    ERIC Educational Resources Information Center

    Frelin, Anneli; Grannäs, Jan

    2013-01-01

    Drawing on the distinction between absent and present presences, this article contributes to our understanding of how new managerial and performative discourses are played out in a secondary school context in Sweden. The consequences of numerous educational reforms during the last 20 years include a surge of new independent schools and increased…

  3. Vampire Selfie: A Curious Case of an Absent Reflection

    ERIC Educational Resources Information Center

    Grossman, Joshua M.

    2014-01-01

    This article presents a puzzle for the optics section of an introductory course on reflections. A teacher could ask students to explain the phenomenon of the "vampire selfie" or the absent reflection. How could that be? What physics caused this curious phenomenon? The article explains light refraction and its effect on what we see and…

  4. PHACE syndrome and congenitally absent thyroid gland at MR imaging.

    PubMed

    Mamlouk, Mark D; Yu, John-Paul J; Asch, Sarah; Mathes, Erin F

    2016-01-01

    PHACE syndrome is a rare neurocutaneous disorder characterized by posterior fossa malformations, hemangiomas, arterial anomalies, cardiac defects, and abnormalities of the eye. Thyroid disorders associated with PHACE syndrome have been described, although there are limited reports of this rare occurrence. We report a case of PHACE syndrome with congenital hypothyroidism in an infant, for which absent thyroid gland was diagnosed at magnetic resonance imaging.

  5. Kaufman oculo-cerebro-facial syndrome in a child with small and absent terminal phalanges and absent nails.

    PubMed

    Kariminejad, Ariana; Ajeawung, Norbert Fonya; Bozorgmehr, Bita; Dionne-Laporte, Alexandre; Molidperee, Sirinart; Najafi, Kimia; Gibbs, Richard A; Lee, Brendan H; Hennekam, Raoul C; Campeau, Philippe M

    2017-04-01

    Kaufman oculo-cerebro-facial syndrome (KOS) is caused by recessive UBE3B mutations and presents with microcephaly, ocular abnormalities, distinctive facial morphology, low cholesterol levels and intellectual disability. We describe a child with microcephaly, brachycephaly, hearing loss, ptosis, blepharophimosis, hypertelorism, cleft palate, multiple renal cysts, absent nails, small or absent terminal phalanges, absent speech and intellectual disability. Syndromes that were initially considered include DOORS syndrome, Coffin-Siris syndrome and Dubowitz syndrome. Clinical investigations coupled with karyotype analysis, array-comparative genomic hybridization, exome and Sanger sequencing were performed to characterize the condition in this child. Sanger sequencing was negative for the DOORS syndrome gene TBC1D24 but exome sequencing identified a homozygous deletion in UBE3B (NM_183415:c.3139_3141del, p.1047_1047del) located within the terminal portion of the HECT domain. This finding coupled with the presence of characteristic features such as brachycephaly, ptosis, blepharophimosis, hypertelorism, short palpebral fissures, cleft palate and developmental delay allowed us to make a diagnosis of KOS. In conclusion, our findings highlight the importance of considering KOS as a differential diagnosis for patients under evaluation for DOORS syndrome and expand the phenotype of KOS to include small or absent terminal phalanges, nails, and the presence of hallux varus and multicystic dysplastic kidneys.

  6. Inositol hexakisphosphate kinase 1 (IP6K1) activity is required for cytoplasmic dynein-driven transport

    PubMed Central

    Chanduri, Manasa; Rai, Ashim; Malla, Aushaq Bashir; Wu, Mingxuan; Fiedler, Dorothea; Mallik, Roop; Bhandari, Rashna

    2016-01-01

    Inositol pyrophosphates, such as diphosphoinositol pentakisphosphate (IP7), are conserved eukaryotic signaling molecules that possess pyrophosphate and monophosphate moieties. Generated predominantly by inositol hexakisphosphate kinases (IP6Ks), inositol pyrophosphates can modulate protein function by posttranslational serine pyrophosphorylation. Here, we report inositol pyrophosphates as novel regulators of cytoplasmic dynein-driven vesicle transport. Mammalian cells lacking IP6K1 display defects in dynein-dependent trafficking pathways, including endosomal sorting, vesicle movement, and Golgi maintenance. Expression of catalytically active but not inactive IP6K1 reverses these defects, suggesting a role for inositol pyrophosphates in these processes. Endosomes derived from slime mold lacking inositol pyrophosphates also display reduced dynein-directed microtubule transport. We demonstrate that Ser51 in the dynein intermediate chain (IC) is a target for pyrophosphorylation by IP7, and this modification promotes the interaction of the IC N-terminus with the p150Glued subunit of dynactin. IC–p150Glued interaction is decreased, and IC recruitment to membranes is reduced in cells lacking IP6K1. Our study provides the first evidence for the involvement of IP6Ks in dynein function and proposes that inositol pyrophosphate-mediated pyrophosphorylation may act as a regulatory signal to enhance dynein-driven transport. PMID:27474409

  7. Apes Communicate about Absent and Displaced Objects: Methodology Matters

    PubMed Central

    Lyn, Heidi; Russell, Jamie L.; Leavens, David A.; Bard, Kim A.; Boysen, Sarah T.; Schaeffer, Jennifer A.; Hopkins, William D.

    2013-01-01

    Displaced reference is the ability to refer to an item that has been moved (displaced) in space and/or time, and has been called one of the true hallmarks of referential communication. Several studies suggest that nonhuman primates have this capability, but a recent experiment concluded that in a specific situation (absent entities) human infants display displaced reference but chimpanzees do not. Here we show that chimpanzees and bonobos of diverse rearing histories are capable of displaced reference to absent and displaced objects. It is likely that some of the conflicting findings from animal cognition studies are due to relatively minor methodological differences, but are compounded by interpretation errors. Comparative studies are of great importance in elucidating the evolution of human cognition, however, greater care must be taken with methodology and interpretation for these studies to accurately reflect species differences. PMID:23681052

  8. Congenital hypogonadotropic hypogonadism: implications of absent mini-puberty.

    PubMed

    Dwyer, Andrew A; Jayasena, Channa N; Quinton, Richard

    2016-06-01

    The phenomenon known as "mini-puberty" refers to activation of the neonatal hypothalamo-pituitary axis causing serum concentrations of gonadotrophins and testosterone (T) to approach adult male levels. This early neonatal period is a key proliferative window for testicular germ cells and immature Sertoli cells. Although failure to spontaneously initiate (adolescent) puberty is the most evident consequence of a defective gonadotropin-releasing hormone (GnRH) neurosecretory network, absent mini-puberty is also likely to have a major impact on the reproductive phenotype of men with congenital hypogonadotrophic hypogonadism (CHH). Furthermore, the phase of male mini-puberty represents a key window-of-opportunity to identify congenital GnRH deficiency (either isolated CHH, or as part of combined pituitary hormone deficiency) in childhood. Among male neonates exhibiting "red flag" indicators for CHH (i.e. maldescended testes with or without cryptorchidism) a single serum sample (between 4-8 weeks of life) can pinpoint congenital GnRH deficiency far more rapidly and with much greater accuracy than dynamic tests performed in later childhood or adolescence. Potential consequences for missing absent mini-puberty in a male neonate include the lack of monitoring of pubertal progression/lack of progression, and the missed opportunity for early therapeutic intervention. This article will review our current understanding of the mechanisms and clinical consequences of mini-puberty. Furthermore, evidence for the optimal clinical management of patients with absent mini-puberty will be discussed.

  9. Creating biomolecular motors based on dynein and actin-binding proteins

    NASA Astrophysics Data System (ADS)

    Furuta, Akane; Amino, Misako; Yoshio, Maki; Oiwa, Kazuhiro; Kojima, Hiroaki; Furuta, Ken'ya

    2016-11-01

    Biomolecular motors such as myosin, kinesin and dynein are protein machines that can drive directional movement along cytoskeletal tracks and have the potential to be used as molecule-sized actuators. Although control of the velocity and directionality of biomolecular motors has been achieved, the design and construction of novel biomolecular motors remains a challenge. Here we show that naturally occurring protein building blocks from different cytoskeletal systems can be combined to create a new series of biomolecular motors. We show that the hybrid motors—combinations of a motor core derived from the microtubule-based dynein motor and non-motor actin-binding proteins—robustly drive the sliding movement of an actin filament. Furthermore, the direction of actin movement can be reversed by simply changing the geometric arrangement of these building blocks. Our synthetic strategy provides an approach to fabricating biomolecular machines that work along artificial tracks at nanoscale dimensions.

  10. Drosophila Dynein intermediate chain gene, Dic61B, is required for spermatogenesis.

    PubMed

    Fatima, Roshan

    2011-01-01

    This study reports the identification and characterization of a novel gene, Dic61B, required for male fertility in Drosophila. Complementation mapping of a novel male sterile mutation, ms21, isolated in our lab revealed it to be allelic to CG7051 at 61B1 cytogenetic region, since two piggyBac insertion alleles, CG7051(c05439) and CG7051(f07138) failed to complement. CG7051 putatively encodes a Dynein intermediate chain. All three mutants, ms21, CG7051(c05439) and CG7051(f07138), exhibited absolute recessive male sterility with abnormally coiled sperm axonemes causing faulty sperm individualization as revealed by Phalloidin staining in Don Juan-GFP background. Sequencing of PCR amplicons uncovered two point mutations in ms21 allele and confirmed the piggyBac insertions in CG7051(c05439) and CG7051(f07138) alleles to be in 5'UTR and 4(th) exon of CG7051 respectively, excision of which reverted the male sterility. In situ hybridization to polytene chromosomes demonstrated CG7051 to be a single copy gene. RT-PCR of testis RNA revealed defective splicing of the CG7051 transcripts in mutants. Interestingly, expression of cytoplasmic dynein intermediate chain, α, β, γ tubulins and α-spectrin was normal in mutants while ultra structural studies revealed defects in the assembly of sperm axonemes. Bioinformatics further highlighted the homology of CG7051 to axonemal dynein intermediate chain of various organisms, including DNAI1 of humans, mutations in which lead to male sterility due to immotile sperms. Based on these observations we conclude that CG7051 encodes a novel axonemal dynein intermediate chain essential for male fertility in Drosophila and rename it as Dic61B. This is the first axonemal Dic gene of Drosophila to be characterized at molecular level and shown to be required for spermatogenesis.

  11. Localization of dynein light chains 1 and 2 and their pro-apoptotic ligands.

    PubMed Central

    Day, Catherine L; Puthalakath, Hamsa; Skea, Gretchen; Strasser, Andreas; Barsukov, Igor; Lian, Lu-Yun; Huang, David C S; Hinds, Mark G

    2004-01-01

    The dynein and myosin V motor complexes are multi-protein structures that function to transport molecules and organelles within the cell. DLC (dynein light-chain) proteins, found as components of both dynein and myosin V motor complexes, connect the complexes to their cargoes. One of the roles of these motor complexes is to selectively sequester the pro-apoptotic 'BH3-only' (Bcl-2 homology 3-only) proteins, Bim (Bcl-2-interacting mediator of cell death) and Bmf (Bcl-2-modifying factor), and so regulate their cell death-inducing function. In vivo DLC2 is found exclusively as a component of the myosin V motor complex and Bmf binds DLC2 selectively. On the other hand, Bim interacts with DLC1 (LC8), an integral component of the dynein motor complex. The two DLCs share 93% sequence identity yet show unambiguous in vivo specificity for their respective BH3-only ligands. To investigate this specificity the three-dimensional solution structure of DLC2 was elucidated using NMR spectroscopy. In vitro structural and mutagenesis studies show that Bmf and Bim have identical binding characteristics to recombinant DLC2 or DLC1. Thus the selectivity shown by Bmf and Bim for binding DLC1 or DLC2, respectively, does not reside in their DLC-binding domains. Remarkably, mutational analysis of DLC1 and DLC2 indicates that a single surface residue (residue 41) determines the specific localization of DLCs with their respective motor complexes. These results suggest a molecular mechanism for the specific compartmentalization of DLCs and their pro-apoptotic cargoes and implicate other protein(s) in defining the specificity between the cargoes and the DLC proteins. PMID:14561217

  12. Elastic properties of dynein motor domain obtained from all-atom molecular dynamics simulations.

    PubMed

    Kamiya, Narutoshi; Mashimo, Tadaaki; Takano, Yu; Kon, Takahide; Kurisu, Genji; Nakamura, Haruki

    2016-08-01

    Dyneins are large microtubule motor proteins that convert ATP energy to mechanical power. High-resolution crystal structures of ADP-bound cytoplasmic dynein have revealed the organization of the motor domain, comprising the AAA(+) ring, the linker, the stalk/strut and the C sequence. Recently, the ADP.vanadate-bound structure, which is similar to the ATP hydrolysis transition state, revealed how the structure of dynein changes upon ATP binding. Although both the ADP- and ATP-bound state structures have been resolved, the dynamic properties at the atomic level remain unclear. In this work, we built two models named 'the ADP model' and 'the ATP model', where ADP and ATP are bound to AAA1 in the AAA(+) ring, respectively, to observe the initial procedure of the structural change from the unprimed to the primed state. We performed 200-ns molecular dynamics simulations for both models and compared their structures and dynamics. The motions of the stalk, consisting of a long coiled coil with a microtubule-binding domain, significantly differed between the two models. The elastic properties of the stalk were analyzed and compared with the experimental results.

  13. Interaction of the Rabies Virus P Protein with the LC8 Dynein Light Chain

    PubMed Central

    Raux, Hélène; Flamand, Anne; Blondel, Danielle

    2000-01-01

    The rabies virus P protein is involved in viral transcription and replication but its precise function is not clear. We investigated the role of P (CVS strain) by searching for cellular partners by using a two-hybrid screening of a PC12 cDNA library. We isolated a cDNA encoding a 10-kDa dynein light chain (LC8). LC8 is a component of cytoplasmic dynein involved in the minus end-directed movement of organelles along microtubules. We confirmed that this molecule interacts with P by coimmunoprecipitation in infected cells and in cells transfected with a plasmid encoding P protein. LC8 was also detected in virus particles. Series of deletions from the N- and C-terminal ends of P protein were used to map the LC8-binding domain to the central part of P (residues 138 to 172). These results are relevant to speculate that dynein may be involved in the axonal transport of rabies virus along microtubules through neuron cells. PMID:11024151

  14. Microtubule minus end motors kinesin-14 and dynein drive nuclear congression in parallel pathways

    PubMed Central

    Scheffler, Kathleen; Minnes, Refael; Fraisier, Vincent; Paoletti, Anne

    2015-01-01

    Microtubules (MTs) and associated motors play a central role in nuclear migration, which is crucial for diverse biological functions including cell division, polarity, and sexual reproduction. In this paper, we report a dual mechanism underlying nuclear congression during fission yeast karyogamy upon mating of haploid cells. Using microfluidic chambers for long-term imaging, we captured the precise timing of nuclear congression and identified two minus end–directed motors operating in parallel in this process. Kinesin-14 Klp2 associated with MTs may cross-link and slide antiparallel MTs emanating from the two nuclei, whereas dynein accumulating at spindle pole bodies (SPBs) may pull MTs nucleated from the opposite SPB. Klp2-dependent nuclear congression proceeds at constant speed, whereas dynein accumulation results in an increase of nuclear velocity over time. Surprisingly, the light intermediate chain Dli1, but not dynactin, is required for this previously unknown function of dynein. We conclude that efficient nuclear congression depends on the cooperation of two minus end–directed motors. PMID:25869666

  15. Local synthesis of dynein cofactors matches retrograde transport to acutely changing demands

    PubMed Central

    Villarin, Joseph M.; McCurdy, Ethan P.; Martínez, José C.; Hengst, Ulrich

    2016-01-01

    Cytoplasmic dynein mediates retrograde transport in axons, but it is unknown how its transport characteristics are regulated to meet acutely changing demands. We find that stimulus-induced retrograde transport of different cargos requires the local synthesis of different dynein cofactors. Nerve growth factor (NGF)-induced transport of large vesicles requires local synthesis of Lis1, while smaller signalling endosomes require both Lis1 and p150Glued. Lis1 synthesis is also triggered by NGF withdrawal and required for the transport of a death signal. Association of Lis1 transcripts with the microtubule plus-end tracking protein APC is required for their translation in response to NGF stimulation but not for their axonal recruitment and translation upon NGF withdrawal. These studies reveal a critical role for local synthesis of dynein cofactors for the transport of specific cargos and identify association with RNA-binding proteins as a mechanism to establish functionally distinct pools of a single transcript species in axons. PMID:28000671

  16. Microtubule minus end motors kinesin-14 and dynein drive nuclear congression in parallel pathways.

    PubMed

    Scheffler, Kathleen; Minnes, Refael; Fraisier, Vincent; Paoletti, Anne; Tran, Phong T

    2015-04-13

    Microtubules (MTs) and associated motors play a central role in nuclear migration, which is crucial for diverse biological functions including cell division, polarity, and sexual reproduction. In this paper, we report a dual mechanism underlying nuclear congression during fission yeast karyogamy upon mating of haploid cells. Using microfluidic chambers for long-term imaging, we captured the precise timing of nuclear congression and identified two minus end-directed motors operating in parallel in this process. Kinesin-14 Klp2 associated with MTs may cross-link and slide antiparallel MTs emanating from the two nuclei, whereas dynein accumulating at spindle pole bodies (SPBs) may pull MTs nucleated from the opposite SPB. Klp2-dependent nuclear congression proceeds at constant speed, whereas dynein accumulation results in an increase of nuclear velocity over time. Surprisingly, the light intermediate chain Dli1, but not dynactin, is required for this previously unknown function of dynein. We conclude that efficient nuclear congression depends on the cooperation of two minus end-directed motors.

  17. Low dietary protein content alleviates motor symptoms in mice with mutant dynactin/dynein-mediated neurodegeneration

    PubMed Central

    Wiesner, Diana; Sinniger, Jérome; Henriques, Alexandre; Dieterlé, Stéphane; Müller, Hans-Peter; Rasche, Volker; Ferger, Boris; Dirrig-Grosch, Sylvie; Soylu-Kucharz, Rana; Petersén, Asa; Walther, Paul; Linkus, Birgit; Kassubek, Jan; Wong, Philip C.; Ludolph, Albert C.; Dupuis, Luc

    2015-01-01

    Mutations in components of the molecular motor dynein/dynactin lead to neurodegenerative diseases of the motor system or atypical parkinsonism. These mutations are associated with prominent accumulation of vesicles involved in autophagy and lysosomal pathways, and with protein inclusions. Whether alleviating these defects would affect motor symptoms remain unknown. Here, we show that a mouse model expressing low levels of disease linked-G59S mutant dynactin p150Glued develops motor dysfunction >8 months before loss of motor neurons or dopaminergic degeneration is observed. Abnormal accumulation of autophagosomes and protein inclusions were efficiently corrected by lowering dietary protein content, and this was associated with transcriptional upregulations of key players in autophagy. Most importantly this dietary modification partially rescued overall neurological symptoms in these mice after onset. Similar observations were made in another mouse strain carrying a point mutation in the dynein heavy chain gene. Collectively, our data suggest that stimulating the autophagy/lysosomal system through appropriate nutritional intervention has significant beneficial effects on motor symptoms of dynein/dynactin diseases even after symptom onset. PMID:25552654

  18. The Absent Interpreter in Administrative Detention Center Medical Units.

    PubMed

    Rondeau-Lutz, Murielle; Weber, Jean-Christophe

    2017-03-01

    The particular situation of the French administrative detention center (ADC) medical units appears to be an exemplary case to study the difficulties facing medical practice. Indeed, the starting point of our inquiry was an amazing observation that needed to be addressed and understood: why are professional interpreters so seldom requested in ADC medical units, where one would expect that they would be "naturally" present? Aiming to fully explore the meanings of the "absent interpreter", this article takes into account the possible meanings of this situation: the recourse to professional interpreters in France is far from expected given cumulative evidence of its benefits; perceptions of illegal immigrants and medical habitus itself may both hamper the use of a third party; the ADCs are a very stressful place for healthcare professionals, with conflicting missions, political issues enmeshed with medical goals, and heavy affective burden that may lead to self-protection. Silencing voices of suffering others might be seen as the hidden indecent truth of the "absent interpreter". These reflections open a window to a larger issue with regard to the full range of medicine: what are the place, the role and the function of patient's words and narratives in contemporary medicine? The highly invested somatic perspective and its political corollary giving primacy to bare life harbor potential risks of obscuring speeches and undervaluing narratives.

  19. Absent without leave; a neuroenergetic theory of mind wandering

    PubMed Central

    Killeen, Peter R.

    2013-01-01

    Absent minded people are not under the control of task-relevant stimuli. According to the Neuroenergetics Theory of attention (NeT), this lack of control is often due to fatigue of the relevant processing units in the brain caused by insufficient resupply of the neuron's preferred fuel, lactate, from nearby astrocytes. A simple drift model of information processing accounts for response-time statistics in a paradigm often used to study inattention, the Sustained Attention to Response Task (SART). It is suggested that errors and slowing in this fast-paced, response-engaging task may have little to due with inattention. Slower-paced and less response-demanding tasks give greater license for inattention—aka absent-mindedness, mind-wandering. The basic NeT is therefore extended with an ancillary model of attentional drift and recapture. This Markov model, called NEMA, assumes probability λ of lapses of attention from 1 s to the next, and probability α of drifting back to the attentional state. These parameters measure the strength of attraction back to the task (α), or away to competing mental states or action patterns (λ); their proportion determines the probability of the individual being inattentive at any point in time over the long run. Their values are affected by the fatigue of the brain units they traffic between. The deployment of the model is demonstrated with a data set involving paced responding. PMID:23847559

  20. Formation of excitatory and inhibitory associations between absent events

    PubMed Central

    Holland, Peter C.; Sherwood, Andrew

    2010-01-01

    Considerable evidence indicates that associations may be formed between two events even when one or both of them is absent at the time of learning. Previously, some researchers asserted that excitatory associations are formed when associatively-activated representations for two events are paired, whereas others claimed that inhibitory associations are formed. In three experiments we investigated the nature of tone-sucrose learning when associatively-activated representations of those events were paired in the absence of either of the events themselves. Experiment 1 found substantial excitatory learning when the tone surrogate preceded the sucrose surrogate in training. Experimental 2 evaluated other accounts for the results of Experiment 1, and Experiment 3 found evidence for inhibitory tone-sucrose learning when the tone and sucrose surrogates were presented in simultaneous or backward order. The results indicated that the nature of representation-mediated learning is influenced by some of the same variables as more standard associative learning. PMID:18665716

  1. Probing the role of IFT particle complex A and B in flagellar entry and exit of IFT-dynein in Chlamydomonas.

    PubMed

    Williamson, Shana M; Silva, David A; Richey, Elizabeth; Qin, Hongmin

    2012-07-01

    Mediating the transport of flagellar precursors and removal of turnover products, intraflagellar transport (IFT) is required for flagella assembly and maintenance. The IFT apparatus is composed of the anterograde IFT motor kinesin II, the retrograde IFT motor IFT-dynein, and IFT particles containing two complexes, A and B. In order to have a balanced two-way transportation, IFT-dynein has to be carried into flagella and transported to the flagellar tip by kinesin II, where it is activated to drive the retrograde IFT back to the flagellar base. In this study, we investigated the role of complex A and complex B in the flagellar entry and exit of IFT-dynein. We showed that regardless of the amount of complex A, IFT-dynein accumulated proportionally to the amount of complex B in the flagella of fla15/ift144 and fla17-1/ift139, two complex A temperature-sensitive mutants. Complex A was depleted from both cellular and flagellar compartments in fla15/ift144 mutant. However, in fla17-1/ift139 mutant, the flagellar level of complex A was at the wild-type level, which was in radical contrast to the significantly reduced cellular amount of complex A. These results support that complex A is not required for the flagellar entry of IFT-dynein, but might be essential for the lagellar exit of IFT-dynein. Additionally, we confirmed the essential role of IFT172, a complex B subunit, in the flagellar entry of IFT-dynein. These results indicate that complexes A and B play complementary but distinct roles for IFT-dynein, with complex B carrying IFT-dynein into the flagella while complex A mediates the flagellar exit of IFT-dynein.

  2. Dynein Function and Protein Clearance Changes in Tumor Cells Induced by a Kunitz-Type Molecule, Amblyomin-X

    PubMed Central

    Pacheco, Mario T. F.; Berra, Carolina M.; Morais, Kátia L. P.; Sciani, Juliana M.; Branco, Vania G.; Bosch, Rosemary V.; Chudzinski-Tavassi, Ana M.

    2014-01-01

    Amblyomin-X is a Kunitz-type recombinant protein identified from the transcriptome of the salivary glands of the tick Amblyomma cajennense and has anti-coagulant and antitumoral activity. The supposed primary target of this molecule is the proteasome system. Herein, we elucidated intracellular events that are triggered by Amblyomin-X treatment in an attempt to provide new insight into how this serine protease inhibitor, acting on the proteasome, could be comparable with known proteasome inhibitors. The collective results showed aggresome formation after proteasome inhibition that appeared to occur via the non-exclusive ubiquitin pathway. Additionally, Amblyomin-X increased the expression of various chains of the molecular motor dynein in tumor cells, modulated specific ubiquitin linkage signaling and inhibited autophagy activation by modulating mTOR, LC3 and AMBRA1 with probable dynein involvement. Interestingly, one possible role for dynein in the mechanism of action of Amblyomin-X was in the apoptotic response and its crosstalk with autophagy, which involved the factor Bim; however, we observed no changes in the apoptotic response related to dynein in the experiments performed. The characteristics shared among Amblyomin-X and known proteasome inhibitors included NF-κB blockage and nascent polypeptide-dependent aggresome formation. Therefore, our study describes a Kunitz-type protein that acts on the proteasome to trigger distinct intracellular events compared to classic known proteasome inhibitors that are small-cell-permeable molecules. In investigating the experiments and literature on Amblyomin-X and the known proteasome inhibitors, we also found differences in the structures of the molecules, intracellular events, dynein involvement and tumor cell type effects. These findings also reveal a possible new target for Amblyomin-X, i.e., dynein, and may serve as a tool for investigating tumor cell death associated with proteasome inhibition. PMID:25479096

  3. Arm Injuries and Disorders

    MedlinePlus

    ... of them are in your arm; the humerus, radius and ulna. Your arms are also made up of muscles, joints, tendons and other connective tissue. Injuries to any of these parts of the arm can occur during sports, a fall or an accident. Types of arm injuries ...

  4. A Low Affinity Ground State Conformation for the Dynein Microtubule Binding Domain*

    PubMed Central

    McNaughton, Lynn; Tikhonenko, Irina; Banavali, Nilesh K.; LeMaster, David M.; Koonce, Michael P.

    2010-01-01

    Dynein interacts with microtubules through a dedicated binding domain that is dynamically controlled to achieve high or low affinity, depending on the state of nucleotide bound in a distant catalytic pocket. The active sites for microtubule binding and ATP hydrolysis communicate via conformational changes transduced through a ∼10-nm length antiparallel coiled-coil stalk, which connects the binding domain to the roughly 300-kDa motor core. Recently, an x-ray structure of the murine cytoplasmic dynein microtubule binding domain (MTBD) in a weak affinity conformation was published, containing a covalently constrained β+ registry for the coiled-coil stalk segment (Carter, A. P., Garbarino, J. E., Wilson-Kubalek, E. M., Shipley, W. E., Cho, C., Milligan, R. A., Vale, R. D., and Gibbons, I. R. (2008) Science 322, 1691–1695). We here present an NMR analysis of the isolated MTBD from Dictyostelium discoideum that demonstrates the coiled-coil β+ registry corresponds to the low energy conformation for this functional region of dynein. Addition of sequence encoding roughly half of the coiled-coil stalk proximal to the binding tip results in a decreased affinity of the MTBD for microtubules. In contrast, addition of the complete coiled-coil sequence drives the MTBD to the conformationally unstable, high affinity binding state. These results suggest a thermodynamic coupling between conformational free energy differences in the α and β+ registries of the coiled-coil stalk that acts as a switch between high and low affinity conformations of the MTBD. A balancing of opposing conformations in the stalk and MTBD enables potentially modest long-range interactions arising from ATP binding in the motor core to induce a relaxation of the MTBD into the stable low affinity state. PMID:20351100

  5. Distribution of tubulin, kinesin, and dynein in light- and dark-adapted octopus retinas.

    PubMed

    Martinez, J M; Elfarissi, H; De Velasco, B; Ochoa, G H; Miller, A M; Clark, Y M; Matsumoto, B; Robles, L J

    2000-01-01

    Cephalopod retinas exhibit several responses to light and dark adaptation, including rhabdom size changes, photopigment movements, and pigment granule migration. Light- and dark-directed rearrangements of microfilament and microtubule cytoskeletal transport pathways could drive these changes. Recently, we localized actin-binding proteins in light-/dark-adapted octopus rhabdoms and suggested that actin cytoskeletal rearrangements bring about the formation and degradation of rhabdomere microvilli subsets. To determine if the microtubule cytoskeleton and associated motor proteins control the other light/dark changes, we used immunoblotting and immunocytochemical procedures to map the distribution of tubulin, kinesin, and dynein in dorsal and ventral halves of light- and dark-adapted octopus retinas. Immunoblots detected alpha- and beta-tubulin, dynein intermediate chain, and kinesin heavy chain in extracts of whole retinas. Epifluorescence and confocal microscopy showed that the tubulin proteins were distributed throughout the retina with more immunoreactivity in retinas exposed to light. Kinesin localization was heavy in the pigment layer of light- and dark-adapted ventral retinas but was less prominent in the dorsal region. Dynein distribution also varied in dorsal and ventral retinas with more immunoreactivity in light- and dark-adapted ventral retinas and confocal microscopy emphasized the granular nature of this labeling. We suggest that light may regulate the distribution of microtubule cytoskeletal proteins in the octopus retina and that position, dorsal versus ventral, also influences the distribution of motor proteins. The microtubule cytoskeleton is most likely involved in pigment granule migration in the light and dark and with the movement of transport vesicles from the photoreceptor inner segments to the rhabdoms.

  6. Thrombocytopenia-absent radius syndrome: a clinical genetic study

    PubMed Central

    Greenhalgh, K; Howell, R; Bottani, A; Ancliff, P; Brunner, H; Verschuuren-Bemel..., C; Vernon, E; Brown, K; Newbury-Ecob, R

    2002-01-01

    The thrombocytopenia-absent radius (TAR) syndrome is a congenital malformation syndrome characterised by bilateral absence of the radii and a thrombocytopenia. The lower limbs, gastrointestinal, cardiovascular, and other systems may also be involved. Shaw and Oliver in 1959 were the first to describe this condition, but it was Hall et al in 1969 who reported the first major series of patients. Since then most reports have been based on single or small numbers of cases. We report the results of a clinical study looking at the phenotype of 34 patients with TAR syndrome. All cases had a documented thrombocytopenia and bilateral radial aplasia, 47% had lower limb anomalies, 47% cow's milk intolerance, 23% renal anomalies, and 15% cardiac anomalies. Congenital anomalies not previously described in association with TAR syndrome included facial capillary haemangiomata, intracranial vascular malformation, sensorineural hearing loss, and scoliosis. Karyotype analysis, chromosome breakage studies including premature centromeric separation and fluorescence in situ hybridisation studies looking for a deletion of chromosome 22q11 were undertaken. Two abnormal karyotypes were identified. PMID:12471199

  7. Absent in melanoma 2 proteins in the development of cancer.

    PubMed

    Choubey, Divaker

    2016-12-01

    Recent studies utilizing chemical-induced colitis-associated and sporadic colon cancer in mouse models indicated a protective role for absent in melanoma 2 (Aim2) in colon epithelial cells. Accordingly, mutations in the human AIM2 gene have been found in colorectal cancer (CRC), and reduced expression of AIM2 in CRC is associated with its progression. Furthermore, the overexpression of AIM2 protein in human cancer cell lines inhibits cell proliferation. Interferon-inducible Aim2 and AIM2 are members of the PYHIN (PYRIN and HIN domain-containing) protein family and share ~57 % amino acid identity. The family also includes murine p202, human PYRIN-only protein 3, and IFI16, which negatively regulate Aim2/AIM2 functions. Because the CRC incidence and mortality rates are higher among men compared with women and the expression of Aim2/AIM2 proteins and their regulators is dependent upon age, gender, and sex hormones, we discuss the potential roles of Aim2/AIM2 in the development of cancer. An improved understanding of the biological functions of the AIM2 in the development of CRC will likely identify new therapeutic approaches to treat patients.

  8. Distinct Biochemical Activities of Eyes absent During Drosophila Eye Development.

    PubMed

    Jin, Meng; Mardon, Graeme

    2016-03-16

    Eyes absent (Eya) is a highly conserved transcriptional coactivator and protein phosphatase that plays vital roles in multiple developmental processes from Drosophila to humans. Eya proteins contain a PST (Proline-Serine-Threonine)-rich transactivation domain, a threonine phosphatase motif (TPM), and a tyrosine protein phosphatase domain. Using a genomic rescue system, we find that the PST domain is essential for Eya activity and Dac expression, and the TPM is required for full Eya function. We also find that the threonine phosphatase activity plays only a minor role during Drosophila eye development and the primary function of the PST and TPM domains is transactivation that can be largely substituted by the heterologous activation domain VP16. Along with our previous results that the tyrosine phosphatase activity of Eya is dispensable for normal Eya function in eye formation, we demonstrate that a primary function of Eya during Drosophila eye development is as a transcriptional coactivator. Moreover, the PST/TPM and the threonine phosphatase activity are not required for in vitro interaction between retinal determination factors. Finally, this work is the first report of an Eya-Ey physical interaction. These findings are particularly important because they highlight the need for an in vivo approach that accurately dissects protein function.

  9. Microtubule-dependent movement of late endocytic vesicles in vitro: requirements for Dynein and Kinesin.

    PubMed

    Bananis, Eustratios; Nath, Sangeeta; Gordon, Kristie; Satir, Peter; Stockert, Richard J; Murray, John W; Wolkoff, Allan W

    2004-08-01

    Our previous studies demonstrated that fluorescent early endocytic vesicles prepared from rat liver after injection of Texas red asialoorosomucoid contain asialoglycoprotein and its receptor and move and undergo fission along microtubules using kinesin I and KIFC2, with Rab4 regulating KIFC2 activity (J. Cell Sci. 116, 2749, 2003). In the current study, procedures to prepare fluorescent late endocytic vesicles were devised. In addition, flow cytometry was utilized to prepare highly purified fluorescent endocytic vesicles, permitting validation of microscopy-based experiments as well as direct biochemical analysis. These studies revealed that late vesicles bound to and moved along microtubules, but in contrast to early vesicles, did not undergo fission. As compared with early vesicles, late vesicles had reduced association with receptor, Rab4, and kinesin I but were highly associated with dynein, Rab7, dynactin, and KIF3A. Dynein and KIF3A antibodies inhibited late vesicle motility, whereas kinesin I and KIFC2 antibodies had no effect. Dynamitin antibodies prevented the association of late vesicles with microtubules. These results indicate that acquisition and exchange of specific motor and regulatory proteins characterizes and may regulate the transition of early to late endocytic vesicles. Flow cytometric purification should ultimately facilitate detailed proteomic analysis and mapping of endocytic vesicle-associated proteins.

  10. Impact-Free Measurement of Microtubule Rotations on Kinesin and Cytoplasmic-Dynein Coated Surfaces

    PubMed Central

    Mitra, Aniruddha; Ruhnow, Felix; Nitzsche, Bert; Diez, Stefan

    2015-01-01

    Knowledge about the three-dimensional stepping of motor proteins on the surface of microtubules (MTs) as well as the torsional components in their power strokes can be inferred from longitudinal MT rotations in gliding motility assays. In previous studies, optical detection of these rotations relied on the tracking of rather large optical probes present on the outer MT surface. However, these probes may act as obstacles for motor stepping and may prevent the unhindered rotation of the gliding MTs. To overcome these limitations, we devised a novel, impact-free method to detect MT rotations based on fluorescent speckles within the MT structure in combination with fluorescence-interference contrast microscopy. We (i) confirmed the rotational pitches of MTs gliding on surfaces coated by kinesin-1 and kinesin-8 motors, (ii) demonstrated the superiority of our method over previous approaches on kinesin-8 coated surfaces at low ATP concentration, and (iii) identified MT rotations driven by mammalian cytoplasmic dynein, indicating that during collective motion cytoplasmic dynein side-steps with a bias in one direction. Our novel method is easy to implement on any state-of-the-art fluorescence microscope and allows for high-throughput experiments. PMID:26368807

  11. Dynein axonemal heavy chain 8 promotes androgen receptor activity and associates with prostate cancer progression

    PubMed Central

    Wang, Yu; Ledet, Russell J.; Imberg-Kazdan, Keren; Logan, Susan K.; Garabedian, Michael J.

    2016-01-01

    To gain insight into cellular factors regulating AR action that could promote castration resistant prostate cancer (CRPC), we performed a genome-wide RNAi screen for factors that promote ligand-independent AR transcriptional activity and integrated clinical databases for candidate genes that are positively associated with prostate cancer metastasis and recurrence. From this analysis, we identified Dynein Axonemal Heavy Chain 8 (DNAH8) as an AR regulator that displayed higher mRNA expression in metastatic than in primary tumors, and showed high expression in patients with poor prognosis. Axonemal dyneins function in cellular motility, but the function of DNAH8 in prostate cancer or other cell types has not been reported. DNAH8 is on chromosome 6q21.2, a cancer-associated amplicon, and is primarily expressed in prostate and testis. Its expression is higher in primary tumors compared to normal prostate, and is further increased in metastatic prostate cancers. Patients expressing high levels of DNAH8 have a greater risk of relapse and a poor prognosis after prostatectomy. Depletion of DNAH8 in prostate cancer cells suppressed AR transcriptional activity and proliferation. Androgen treatment increased DNAH8 mRNA expression, and AR bound the DNAH8 promoter sequence indicating DNAH8 is an AR target gene. Thus, DNAH8 is a new regulator of AR associated with metastatic tumors and poor prognosis. PMID:27363033

  12. Dynein light chain family genes in 15 plant species: Identification, evolution and expression profiles.

    PubMed

    Cao, Jun; Li, Xiangyang; Lv, Yueqing

    2017-01-01

    Dynein light chain (DLC) is one important component of the dynein complexes, which have been proved involving in a variety of cellular functions. However, higher plants lack all other components of the complexes except DLCs, suggesting that in plants, the DLC protein does not carry out the same function as it in animals. Therefore, the function of this family in plants is mysterious. In this study, we investigated the DLC gene family in 15 plant species and analyzed their expression profiles. In total, 128 DLC genes were identified from the 15 studied plant species and were divided into eight groups by their phylogenetic relation. Highly conserved gene structure and motif arrangement was discovered within each group, indicating their functional correlation. Genetic variation and recombination events were also detected in DLC genes. Through selection analyses, we also identified some significant site-specific constraints in most of the DLC paralogs. In addition, DLC genes presented various expression profiles in different development stages, or under different abiotic stresses or phytohormone treatments. This may be associated with a variety of cis-elements responding to stress and phytohormone in the upstream sequences of the DLC genes. Functional network analysis exhibited 123 physical or functional interactions. The results provide a foundation for exploring the characterization of the DLC genes in plants and offer insights for additional functional studies.

  13. Proteomic Analysis of Dynein-Interacting Proteins in Amyotrophic Lateral Sclerosis Synaptosomes Reveals Alterations in the RNA-Binding Protein Staufen1*

    PubMed Central

    Gershoni-Emek, Noga; Mazza, Arnon; Chein, Michael; Gradus-Pery, Tal; Xiang, Xin; Li, Ka Wan; Sharan, Roded; Perlson, Eran

    2016-01-01

    Synapse disruption takes place in many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). However, the mechanistic understanding of this process is still limited. We set out to study a possible role for dynein in synapse integrity. Cytoplasmic dynein is a multisubunit intracellular molecule responsible for diverse cellular functions, including long-distance transport of vesicles, organelles, and signaling factors toward the cell center. A less well-characterized role dynein may play is the spatial clustering and anchoring of various factors including mRNAs in distinct cellular domains such as the neuronal synapse. Here, in order to gain insight into dynein functions in synapse integrity and disruption, we performed a screen for novel dynein interactors at the synapse. Dynein immunoprecipitation from synaptic fractions of the ALS model mSOD1G93A and wild-type controls, followed by mass spectrometry analysis on synaptic fractions of the ALS model mSOD1G93A and wild-type controls, was performed. Using advanced network analysis, we identified Staufen1, an RNA-binding protein required for the transport and localization of neuronal RNAs, as a major mediator of dynein interactions via its interaction with protein phosphatase 1–beta (PP1B). Both in vitro and in vivo validation assays demonstrate the interactions of Staufen1 and PP1B with dynein, and their colocalization with synaptic markers was altered as a result of two separate ALS-linked mutations: mSOD1G93A and TDP43A315T. Taken together, we suggest a model in which dynein's interaction with Staufen1 regulates mRNA localization along the axon and the synapses, and alterations in this process may correlate with synapse disruption and ALS toxicity. PMID:26598648

  14. Novel dynein DYNC1H1 neck and motor domain mutations link distal SMA and abnormal cortical development

    PubMed Central

    Fiorillo, Chiara; Moro, Francesca; Yi, Julie; Weil, Sarah; Brisca, Giacomo; Astrea, Guja; Severino, Mariasavina; Romano, Alessandro; Battini, Roberta; Rossi, Andrea; Minetti, Carlo; Bruno, Claudio; Santorelli, Filippo M.; Vallee, Richard

    2014-01-01

    DYNC1H1 encodes the heavy chain of cytoplasmic dynein 1, a motor protein complex implicated in retrograde axonal transport, neuronal migration, and other intracellular motility functions. Mutations in DYNC1H1 have been described in autosomal dominant Charcot-Marie-Tooth type 2 and in families with distal spinal muscular atrophy (SMA) predominantly affecting the legs (SMA-LED). Recently, defects of cytoplasmic dynein 1 were also associated with a form of mental retardation and neuronal migration disorders. Here we describe two unrelated patients presenting a combined phenotype of congenital motor neuron disease associated with focal areas of cortical malformation. In each patient we identified a novel de novo mutation in DYNC1H1: c.3581A>G (p.Gln1194Arg) in one case and c.9142G>A (p.Glu3048Lys) in the other. The mutations lie in different domains of the dynein heavy chain, and are deleterious to protein function as indicated by assays for Golgi recovery after nocodazole washout in patient fibroblasts. Our results expand the set of pathological mutations in DYNC1H1, reinforce the role of cytoplasmic dynein in disorders of neuronal migration and provide evidence for a syndrome including spinal nerve degeneration and brain developmental problems. PMID:24307404

  15. Dynein light chain binding to a 3′-untranslated sequence mediates parathyroid hormone mRNA association with microtubules

    PubMed Central

    Epstein, Eyal; Sela-Brown, Alin; Ringel, Israel; Kilav, Rachel; King, Stephen M.; Benashski, Sharon E.; Yisraeli, Joel K.; Silver, Justin; Naveh-Many, Tally

    2000-01-01

    The 3′-untranslated region (UTR) of mRNAs binds proteins that determine mRNA stability and localization. The 3′-UTR of parathyroid hormone (PTH) mRNA specifically binds cytoplasmic proteins. We screened an expression library for proteins that bind the PTH mRNA 3′-UTR, and the sequence of 1 clone was identical to that of the dynein light chain LC8, a component of the dynein complexes that translocate cytoplasmic components along microtubules. Recombinant LC8 binds PTH mRNA 3′-UTR, as shown by RNA electrophoretic mobility shift assay. We showed that PTH mRNA colocalizes with microtubules in the parathyroid gland, as well as with a purified microtubule preparation from calf brain, and that this association was mediated by LC8. To our knowledge, this is the first report of a dynein complex protein binding an mRNA. The dynein complex may be the motor that is responsible for transporting mRNAs to specific locations in the cytoplasm and for the consequent is asymmetric distribution of translated proteins in the cell. PMID:10683380

  16. Twelve- and 16-Month-Old Infants Recognize Properties of Mentioned Absent Things

    ERIC Educational Resources Information Center

    Saylor, Megan M.

    2004-01-01

    Absent reference comprehension is a critical achievement of early development, yet little is known about its emergence. In the current study, 12- and 16-month-old infants' recognition of properties of mentioned absent things was used as an index of absent reference comprehension. Infants were presented with displays matching the color and prior…

  17. A role for the Golgi matrix protein giantin in ciliogenesis through control of the localization of dynein-2

    PubMed Central

    Asante, David; MacCarthy-Morrogh, Lucy; Townley, Anna K.; Weiss, Matthew A.; Katayama, Kentaro; Palmer, Krysten J.; Suzuki, Hiroetsu; Westlake, Chris J.; Stephens, David J.

    2013-01-01

    Summary The correct formation of primary cilia is central to the development and function of nearly all cells and tissues. Cilia grow from the mother centriole by extension of a microtubule core, the axoneme, which is then surrounded with a specialized ciliary membrane that is continuous with the plasma membrane. Intraflagellar transport moves particles along the length of the axoneme to direct assembly of the cilium and is also required for proper cilia function. The microtubule motor, cytoplasmic dynein-2 mediates retrograde transport along the axoneme from the tip to the base; dynein-2 is also required for some aspects of cilia formation. In most cells, the Golgi lies adjacent to the centrioles and key components of the cilia machinery localize to this organelle. Golgi-localized proteins have also been implicated in ciliogenesis and in intraflagellar transport. Here, we show that the transmembrane Golgi matrix protein giantin (GOLGB1) is required for ciliogenesis. We show that giantin is not required for the Rab11–Rabin8–Rab8 pathway that has been implicated in the early stages of ciliary membrane formation. Instead we find that suppression of giantin results in mis-localization of WDR34, the intermediate chain of dynein-2. Highly effective depletion of giantin or WDR34 leads to an inability of cells to form primary cilia. Partial depletion of giantin or of WDR34 leads to an increase in cilia length consistent with the concept that giantin acts through dynein-2. Our data implicate giantin in ciliogenesis through control of dynein-2 localization. PMID:24046448

  18. Evolution of robotic arms.

    PubMed

    Moran, Michael E

    2007-01-01

    The foundation of surgical robotics is in the development of the robotic arm. This is a thorough review of the literature on the nature and development of this device with emphasis on surgical applications. We have reviewed the published literature and classified robotic arms by their application: show, industrial application, medical application, etc. There is a definite trend in the manufacture of robotic arms toward more dextrous devices, more degrees-of-freedom, and capabilities beyond the human arm. da Vinci designed the first sophisticated robotic arm in 1495 with four degrees-of-freedom and an analog on-board controller supplying power and programmability. von Kemplen's chess-playing automaton left arm was quite sophisticated. Unimate introduced the first industrial robotic arm in 1961, it has subsequently evolved into the PUMA arm. In 1963 the Rancho arm was designed; Minsky's Tentacle arm appeared in 1968, Scheinman's Stanford arm in 1969, and MIT's Silver arm in 1974. Aird became the first cyborg human with a robotic arm in 1993. In 2000 Miguel Nicolalis redefined possible man-machine capacity in his work on cerebral implantation in owl-monkeys directly interfacing with robotic arms both locally and at a distance. The robotic arm is the end-effector of robotic systems and currently is the hallmark feature of the da Vinci Surgical System making its entrance into surgical application. But, despite the potential advantages of this computer-controlled master-slave system, robotic arms have definite limitations. Ongoing work in robotics has many potential solutions to the drawbacks of current robotic surgical systems.

  19. Worldwide Report, Arms Control.

    DTIC Science & Technology

    2007-11-02

    Research Service, 1000 North Glebe Road, Arlington, Virginia 22201. JPRS-TAC-86-023 11 March 1986 WORLDWIDE REPORT ARMS CONTROL CONTENTS SDI AND SPACE ...ARMS Soviet Journal Reviews SIPRI Books on Arms Race in Outer Space (I. Kuznetsova, Yu. Orlov; Moscow INTERNATIONAL AFFAIRS, No 12, Dec 85) 1...Moscow KRASNAYA ZVEZDA, 8 Feb 86) 59 TASS: INF Accord Possible Without Space Arms Connection (Moscow TASS, 7 Feb 86) 62 TASS: U.S. Officials

  20. Worldwide Report, Arms Control

    DTIC Science & Technology

    2007-11-02

    on nuclear and space arms cannot be described as "equitable" even with most unrestrained imagination. ’Gray Hawk’ PM131006 Moscow IZVESTIYA in...WORLDWIDE REPORT ARMS CONTROL CONTENTS SDI AND SPACE ARMS Effectiveness of U.S. SDI Effort Downplayed ’ (Peter Bretschneider; Karl-Marx-Stadt...MEZHDUNARODNYYE OTNOSHENIYA, No 7, Jul 85) 53 - b - JPRS-TAO85-064 13 December 1985 SDI AND SPACE ARMS EFFECTIVENESS OF U.S. SDI EFFORT

  1. TCLS Arm for Space

    NASA Astrophysics Data System (ADS)

    Leroy, Benoit; Helfers, Tim; Poupat, Jean-Luc

    2015-09-01

    The TCLS ARM FOR SPACE proposal was an answer to the H2020 topic “COMPET-6-2014: Bottom-up Space Technologies at low TRL”. This paper presents this H2020 TCLS ARM FOR SPACE initiative led by Airbus DS and which aims at fostering the use of European technology such as ARM processing for Space.

  2. Whacked and Rab35 polarize dynein motor complex-dependent seamless tube growth

    PubMed Central

    Schottenfeld-Roames, Jodi; Ghabrial, Amin S.

    2012-01-01

    Seamless tubes form intracellularly without cell-cell or autocellular junctions. Such tubes have been described across phyla, but remain mysterious despite their simple architecture. In Drosophila, seamless tubes are found within tracheal terminal cells, which have dozens of branched protrusions extending hundreds of microns. We find that mutations in multiple components of the dynein motor complex block seamless tube growth, raising the possibility that the lumenal membrane forms through minus-end directed transport of apical membrane components along microtubules. Growth of seamless tube is polarized along the proximodistal axis by Rab35 and its apical membrane-localized GAP, Whacked. Strikingly, loss of whacked (or constitutive activation of Rab35) leads to tube overgrowth at terminal cell branch tips, while over-expression of whacked (or dominant negative Rab35) causes formation of ectopic tubes surrounding the terminal cell nucleus. Thus, vesicle trafficking plays key roles in making and shaping seamless tubes. PMID:22407366

  3. Dynein-Based Accumulation of Membranes Regulates Nuclear Expansion in Xenopus laevis Egg Extracts.

    PubMed

    Hara, Yuki; Merten, Christoph A

    2015-06-08

    Nuclear size changes dynamically during development and has long been observed to correlate with the space surrounding the nucleus, as well as with the volume of the cell. Here we combine an in vitro cell-free system of Xenopus laevis egg extract with microfluidic devices to systematically analyze the effect of spatial constraints. The speed of nuclear expansion depended on the available space surrounding the nucleus up to a threshold volume in the nanoliter range, herein referred to as the nuclear domain. Under spatial constraints smaller than this nuclear domain, the size of microtubule-occupied space surrounding the nucleus turned out to be limiting for the accumulation of membranes around the nucleus via the motor protein dynein, therefore determining the speed of nuclear expansion. This mechanism explains how spatial information surrounding the nucleus, such as the positioning of the nucleus inside the cell, can control nuclear expansion.

  4. Role of Recycling Endosomes and Lysosomes in Dynein-Dependent Entry of Canine Parvovirus

    PubMed Central

    Suikkanen, Sanna; Sääjärvi, Katja; Hirsimäki, Jonna; Välilehto, Outi; Reunanen, Hilkka; Vihinen-Ranta, Maija; Vuento, Matti

    2002-01-01

    Canine parvovirus (CPV) is a nonenveloped virus with a 5-kb single-stranded DNA genome. Lysosomotropic agents and low temperature are known to prevent CPV infection, indicating that the virus enters its host cells by endocytosis and requires an acidic intracellular compartment for penetration into the cytoplasm. After escape from the endocytotic vesicles, CPV is transported to the nucleus for replication. In the present study the intracellular entry pathway of the canine parvovirus in NLFK (Nordisk Laboratory feline kidney) cells was studied. After clustering in clathrin-coated pits and being taken up in coated vesicles, CPV colocalized with coendocytosed transferrin in endosomes resembling recycling endosomes. Later, CPV was found to enter, via late endosomes, a perinuclear vesicular compartment, where it colocalized with lysosomal markers. There was no indication of CPV entry into the trans-Golgi or the endoplasmic reticulum. Similar results were obtained both with full and with empty capsids. The data thus suggest that CPV or its DNA was released from the lysosomal compartment to the cytoplasm to be then transported to the nucleus. Electron microscopy analysis revealed endosomal vesicles containing CPV to be associated with microtubules. In the presence of nocodazole, a microtubule-disrupting drug, CPV entry was blocked and the virus was found in peripheral vesicles. Thus, some step(s) of the entry process were dependent on microtubules. Microinjection of antibodies to dynein caused CPV to remain in pericellular vesicles. This suggests an important role for the motor protein dynein in transporting vesicles containing CPV along the microtubule network. PMID:11932407

  5. Role of recycling endosomes and lysosomes in dynein-dependent entry of canine parvovirus.

    PubMed

    Suikkanen, Sanna; Sääjärvi, Katja; Hirsimäki, Jonna; Välilehto, Outi; Reunanen, Hilkka; Vihinen-Ranta, Maija; Vuento, Matti

    2002-05-01

    Canine parvovirus (CPV) is a nonenveloped virus with a 5-kb single-stranded DNA genome. Lysosomotropic agents and low temperature are known to prevent CPV infection, indicating that the virus enters its host cells by endocytosis and requires an acidic intracellular compartment for penetration into the cytoplasm. After escape from the endocytotic vesicles, CPV is transported to the nucleus for replication. In the present study the intracellular entry pathway of the canine parvovirus in NLFK (Nordisk Laboratory feline kidney) cells was studied. After clustering in clathrin-coated pits and being taken up in coated vesicles, CPV colocalized with coendocytosed transferrin in endosomes resembling recycling endosomes. Later, CPV was found to enter, via late endosomes, a perinuclear vesicular compartment, where it colocalized with lysosomal markers. There was no indication of CPV entry into the trans-Golgi or the endoplasmic reticulum. Similar results were obtained both with full and with empty capsids. The data thus suggest that CPV or its DNA was released from the lysosomal compartment to the cytoplasm to be then transported to the nucleus. Electron microscopy analysis revealed endosomal vesicles containing CPV to be associated with microtubules. In the presence of nocodazole, a microtubule-disrupting drug, CPV entry was blocked and the virus was found in peripheral vesicles. Thus, some step(s) of the entry process were dependent on microtubules. Microinjection of antibodies to dynein caused CPV to remain in pericellular vesicles. This suggests an important role for the motor protein dynein in transporting vesicles containing CPV along the microtubule network.

  6. Renal tubular dysgenesis, absent nipples, and multiple malformations in three brothers: a new, lethal syndrome.

    PubMed

    Hisama, F M; Reyes-Mugica, M; Wargowski, D S; Thompson, K J; Mahoney, M J

    1998-12-04

    We report on three brothers with renal tubular dysgenesis and absent nipples, each also had other malformations including pre-auricular pits and a preauricular tag, branchial clefts, choanal atresia, pulmonary lobation anomaly, ventricular septal defect, type IIB interrupted aortic arch, absent gallbladder, absent thymus, parathyroid gland, accessory spleen, imperforate anus, clinodactyly, and broad digits and small nails. All three infants died neonatally. This pattern of clinical malformations appears to be a previously unreported syndrome.

  7. Turner Syndrome and apparent absent uterus: a case report and review of the literature.

    PubMed

    Akierman, Sarah V; Skappak, Christopher D; Girgis, Rose; Ho, Josephine

    2013-01-01

    We report on a patient who initially presented with delayed puberty and an absent uterus on imaging with ultrasound and MRI. She was subsequently diagnosed with Turner Syndrome. Turner Syndrome typically presents with early loss of ovarian function and should be considered when primary ovarian insufficiency is present with apparent absent uterus on imaging. Follow-up imaging of the apparent absent uterus post-estrogen replacement therapy is important to confirm a normal uterus. A diagnosis of an absent uterus can be psychologically traumatic for patients and families, and can have significant implications for future fertility options.

  8. The arms race

    SciTech Connect

    Sheehan, M.

    1983-01-01

    This book presents a comprehensive examination of the nature of the contemporary arms race, the forces that encourage arms competition, and the means by which these forces can be controlled. The author provides analyses of such specific issues as the viability of arms control agreements; the possibilities for nuclear disarmament; the means of deterrence, detection, and defense; and the methods of destruction themselves - nuclear, conventional, chemical, and space weapons.

  9. Worldwide Report, Arms Control

    DTIC Science & Technology

    2007-11-02

    North Glebe Road, Arlington, Virginia 22201. JPRS-TAC-85-065 16 December 1985 WORLDWIDE REPORT ARMS CONTROL CONTENTS SDI AND SPACE ARMS French...34U.S.-USSR Geneva Talks" for "European Conferences". JPRS-TAO85-065 16 December 1985 SDI AND SPACE ARMS FRENCH PRIME MINISTER DISCUSSES SDI...imbalances in conventional weapons can really be discussed. As far as space is concerned, we want to avoid the emergence of weapons which are highly

  10. Radial arm strike rail

    DOEpatents

    McKeown, Mark H.; Beason, Steven C.

    1991-01-01

    The radial arm strike rail assembly is a system for measurement of bearings, directions, and stereophotography for geologic mapping, particularly where magnetic compasses are not appropriate. The radial arm, pivoting around a shaft axis, provides a reference direction determination for geologic mapping and bearing or direction determination. The centerable and levelable pedestal provide a base for the radial arm strike rail and the telescoping camera pedestal. The telescoping feature of the radial arm strike rail allows positioning the end of the rail for strike direction or bearing measurement with a goniometer.

  11. Sometimes two arms are enough--an unusual life-stage in brittle stars (Echinodermata: Ophiuroidea).

    PubMed

    Stöhr, Sabine; Alme, Øydis

    2015-08-03

    Off West Africa (Angola-Morocco), benthos samples were collected in the years 2005-2012. These contained 124 specimens of brittle stars with two long arms and three extremely short or absent arms and an elongated, narrow disc. These unusual brittle stars, as well as 33 specimens with five fully developed arms, were identified as Amphiura ungulata. The specimens with unequal arms were juvenile stages, whereas adults had five equal arms. The large number of specimens with unequal arms suggests that this condition is not the result of damage and regeneration, but a normal growth pattern in this species. This study documents the morphology by SEM, amends the species description, and discusses possible explanations for the evolution of this condition. Although brittle star species with unequal arm growth have been reported, this is an extreme case that was unknown before this study.

  12. Tug-of-war of microtubule filaments at the boundary of a kinesin- and dynein-patterned surface

    NASA Astrophysics Data System (ADS)

    Ikuta, Junya; Kamisetty, Nagendra K.; Shintaku, Hirofumi; Kotera, Hidetoshi; Kon, Takahide; Yokokawa, Ryuji

    2014-06-01

    Intracellular cargo is transported by multiple motor proteins. Because of the force balance of motors with mixed polarities, cargo moves bidirectionally to achieve biological functions. Here, we propose a microtubule gliding assay for a tug-of-war study of kinesin and dynein. A boundary of the two motor groups is created by photolithographically patterning gold to selectively attach kinesin to the glass and dynein to the gold surface using a self-assembled monolayer. The relationship between the ratio of two antagonistic motor numbers and the velocity is derived from a force-velocity relationship for each motor to calculate the detachment force and motor backward velocity. Although the tug-of-war involves >100 motors, values are calculated for a single molecule and reflect the collective dynein and non-collective kinesin functions when they work as a team. This assay would be useful for detailed in vitro analysis of intracellular motility, e.g., mitosis, where a large number of motors with mixed polarities are involved.

  13. Dynein-2 affects the regulation of ciliary length but is not required for ciliogenesis in Tetrahymena thermophila.

    PubMed

    Rajagopalan, Vidyalakshmi; Subramanian, Aswati; Wilkes, David E; Pennock, David G; Asai, David J

    2009-01-01

    Eukaryotic cilia and flagella are assembled and maintained by the bidirectional intraflagellar transport (IFT). Studies in alga, nematode, and mouse have shown that the heavy chain (Dyh2) and the light intermediate chain (D2LIC) of the cytoplasmic dynein-2 complex are essential for retrograde intraflagellar transport. In these organisms, disruption of either dynein-2 component results in short cilia/flagella with bulbous tips in which excess IFT particles have accumulated. In Tetrahymena, the expression of the DYH2 and D2LIC genes increases during reciliation, consistent with their roles in IFT. However, the targeted elimination of either DYH2 or D2LIC gene resulted in only a mild phenotype. Both knockout cell lines assembled motile cilia, but the cilia were of more variable lengths and less numerous than wild-type controls. Electron microscopy revealed normally shaped cilia with no swelling and no obvious accumulations of material in the distal ciliary tip. These results demonstrate that dynein-2 contributes to the regulation of ciliary length but is not required for ciliogenesis in Tetrahymena.

  14. Load-induced enhancement of Dynein force production by LIS1–NudE in vivo and in vitro

    PubMed Central

    Reddy, Babu J. N.; Mattson, Michelle; Wynne, Caitlin L.; Vadpey, Omid; Durra, Abdo; Chapman, Dail; Vallee, Richard B.; Gross, Steven P.

    2016-01-01

    Most sub-cellular cargos are transported along microtubules by kinesin and dynein molecular motors, but how transport is regulated is not well understood. It is unknown whether local control is possible, for example, by changes in specific cargo-associated motor behaviour to react to impediments. Here we discover that microtubule-associated lipid droplets (LDs) in COS1 cells respond to an optical trap with a remarkable enhancement in sustained force production. This effect is observed only for microtubule minus-end-moving LDs. It is specifically blocked by RNAi for the cytoplasmic dynein regulators LIS1 and NudE/L (Nde1/Ndel1), but not for the dynactin p150Glued subunit. It can be completely replicated using cell-free preparations of purified LDs, where duration of LD force production is more than doubled. These results identify a novel, intrinsic, cargo-associated mechanism for dynein-mediated force adaptation, which should markedly improve the ability of motor-driven cargoes to overcome subcellular obstacles. PMID:27489054

  15. Dynein Heavy Chain, Encoded by Two Genes in Agaricomycetes, Is Required for Nuclear Migration in Schizophyllum commune

    PubMed Central

    Gube, Matthias; Ring, Christiane; Hanisch, Lisa; Linde, Jörg; Krause, Katrin; Kothe, Erika

    2015-01-01

    The white-rot fungus Schizophyllum commune (Agaricomycetes) was used to study the cell biology of microtubular trafficking during mating interactions, when the two partners exchange nuclei, which are transported along microtubule tracks. For this transport activity, the motor protein dynein is required. In S. commune, the dynein heavy chain is encoded in two parts by two separate genes, dhc1 and dhc2. The N-terminal protein Dhc1 supplies the dimerization domain, while Dhc2 encodes the motor machinery and the microtubule binding domain. This split motor protein is unique to Basidiomycota, where three different sequence patterns suggest independent split events during evolution. To investigate the function of the dynein heavy chain, the gene dhc1 and the motor domain in dhc2 were deleted. Both resulting mutants were viable, but revealed phenotypes in hyphal growth morphology and mating behavior as well as in sexual development. Viability of strain Δdhc2 is due to the higher expression of kinesin-2 and kinesin-14, which was proven via RNA sequencing. PMID:26284622

  16. Causal Attributions as Predictors of Academic Achievement in Father-Absent Children.

    ERIC Educational Resources Information Center

    Salzman, Stephanie A.

    The purpose of this study was to examine the potential impact of maternal attributions and self-attributions on the academic achievement of father-absent children in comparison to commonly identified family interaction and demographic variables. Subjects included 33 male and 34 female father-absent sixth graders (mean age of 11.6 years) and their…

  17. Asymmetrical Sample Training Produces Asymmetrical Retention Functions in Feature-Present/Feature-Absent Matching in Pigeons

    ERIC Educational Resources Information Center

    Grant, Douglas S.; Blatz, Craig W.

    2004-01-01

    Pigeons were trained in a matching task in which samples involved presentation of a white line on a green background (feature-present) or on an otherwise dark key (feature-absent). After asymmetrical training in which one group was initially trained with the feature-present sample and another was initially trained with the feature-absent sample,…

  18. 42 CFR 410.175 - Alien absent from the United States.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Alien absent from the United States. 410.175... Alien absent from the United States. (a) Medicare does not pay Part B benefits for services furnished to... during the first full calendar month the alien is back in the United States....

  19. 42 CFR 410.175 - Alien absent from the United States.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Alien absent from the United States. 410.175... Alien absent from the United States. (a) Medicare does not pay Part B benefits for services furnished to... during the first full calendar month the alien is back in the United States....

  20. 42 CFR 410.175 - Alien absent from the United States.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Alien absent from the United States. 410.175... Alien absent from the United States. (a) Medicare does not pay Part B benefits for services furnished to... during the first full calendar month the alien is back in the United States....

  1. 42 CFR 410.175 - Alien absent from the United States.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Alien absent from the United States. 410.175... Alien absent from the United States. (a) Medicare does not pay Part B benefits for services furnished to... during the first full calendar month the alien is back in the United States....

  2. 42 CFR 410.175 - Alien absent from the United States.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Alien absent from the United States. 410.175... Alien absent from the United States. (a) Medicare does not pay Part B benefits for services furnished to... during the first full calendar month the alien is back in the United States....

  3. Successful Black Men from Absent-Father Homes and Their Resilient Single Mothers: A Phenomenological Study

    ERIC Educational Resources Information Center

    Wilson, Angie D.; Henriksen, Richard C.; Bustamante, Rebecca; Irby, Beverly

    2016-01-01

    The phenomenon of absent fathers is a common occurrence in today's homes that appears to be escalating, especially in Black households across the United States. The purpose of this study was to describe the lived experiences of successful Black men who were raised in absent-father homes as well as the lived experiences of their resilient single…

  4. Disneyland Dads, Disneyland Moms? How Nonresident Parents Spend Time with Absent Children.

    ERIC Educational Resources Information Center

    Stewart, Susan D.

    1999-01-01

    Examines gender differences in how nonresident parents spend time with their absent children. Results suggest that nonresident mothers and fathers exhibit a similar pattern of participation in activities with their absent children. Most nonresident parents either engage in only leisure activities with their children or have no contact. (Author/MKA)

  5. ARM Mentor Selection Process

    SciTech Connect

    Sisterson, D. L.

    2015-10-01

    The Atmospheric Radiation Measurement (ARM) Program was created in 1989 with funding from the U.S. Department of Energy (DOE) to develop several highly instrumented ground stations to study cloud formation processes and their influence on radiative transfer. In 2003, the ARM Program became a national scientific user facility, known as the ARM Climate Research Facility. This scientific infrastructure provides for fixed sites, mobile facilities, an aerial facility, and a data archive available for use by scientists worldwide through the ARM Climate Research Facility—a scientific user facility. The ARM Climate Research Facility currently operates more than 300 instrument systems that provide ground-based observations of the atmospheric column. To keep ARM at the forefront of climate observations, the ARM infrastructure depends heavily on instrument scientists and engineers, also known as lead mentors. Lead mentors must have an excellent understanding of in situ and remote-sensing instrumentation theory and operation and have comprehensive knowledge of critical scale-dependent atmospheric processes. They must also possess the technical and analytical skills to develop new data retrievals that provide innovative approaches for creating research-quality data sets. The ARM Climate Research Facility is seeking the best overall qualified candidate who can fulfill lead mentor requirements in a timely manner.

  6. HP-Lattice QSAR for dynein proteins: experimental proteomics (2D-electrophoresis, mass spectrometry) and theoretic study of a Leishmania infantum sequence.

    PubMed

    Dea-Ayuela, María Auxiliadora; Pérez-Castillo, Yunierkis; Meneses-Marcel, Alfredo; Ubeira, Florencio M; Bolas-Fernández, Francisco; Chou, Kuo-Chen; González-Díaz, Humberto

    2008-08-15

    The toxicity and inefficacy of actual organic drugs against Leishmaniosis justify research projects to find new molecular targets in Leishmania species including Leishmania infantum (L. infantum) and Leishmaniamajor (L. major), both important pathogens. In this sense, quantitative structure-activity relationship (QSAR) methods, which are very useful in Bioorganic and Medicinal Chemistry to discover small-sized drugs, may help to identify not only new drugs but also new drug targets, if we apply them to proteins. Dyneins are important proteins of these parasites governing fundamental processes such as cilia and flagella motion, nuclear migration, organization of the mitotic splinde, and chromosome separation during mitosis. However, despite the interest for them as potential drug targets, so far there has been no report whatsoever on dyneins with QSAR techniques. To the best of our knowledge, we report here the first QSAR for dynein proteins. We used as input the Spectral Moments of a Markov matrix associated to the HP-Lattice Network of the protein sequence. The data contain 411 protein sequences of different species selected by ClustalX to develop a QSAR that correctly discriminates on average between 92.75% and 92.51% of dyneins and other proteins in four different train and cross-validation datasets. We also report a combined experimental and theoretic study of a new dynein sequence in order to illustrate the utility of the model to search for potential drug targets with a practical example. First, we carried out a 2D-electrophoresis analysis of L. infantum biological samples. Next, we excised from 2D-E gels one spot of interest belonging to an unknown protein or protein fragment in the region M<20,200 and pI<4. We used MASCOT search engine to find proteins in the L. major data base with the highest similarity score to the MS of the protein isolated from L. infantum. We used the QSAR model to predict the new sequence as dynein with probability of 99.99% without

  7. Sweating - absent

    MedlinePlus

    ... diseases or scarring of the skin that block sweat glands Trauma to sweat glands Use of certain drugs Home Care If there ... Miller JL. Diseases of the eccrine and apocrine sweat glands. In: Bolognia JL, Jorizzo JL, Schaffer JV, eds. ...

  8. Thirst - absent

    MedlinePlus

    ... to drink fluids, even when the body is low on water or has too much salt. ... do a detailed nervous system exam if a head injury or problem ... are dehydrated, fluids will likely be given through a vein (IV).

  9. A High-Throughput Screening Method for Small-Molecule Inhibitors of the Aberrant Mutant SOD1 and Dynein Complex Interaction

    PubMed Central

    Tang, Xiaohu; Seyb, Kathleen I.; Huang, Mickey; Schuman, Eli R.; Shi, Ping; Zhu, Haining; Glicksman, Marcie A.

    2013-01-01

    Aberrant protein-protein interactions are attractive drug targets in a variety of neurodegenerative diseases due to the common pathology of accumulation of protein aggregates. In amyotrophic lateral sclerosis, mutations in SOD1 cause the formation of aggregates and inclusions that may sequester other proteins and disrupt cellular processes. It has been demonstrated that mutant SOD1, but not wild-type SOD1, interacts with the axonal transport motor dynein and that this interaction contributes to motor neuron cell death, suggesting that disrupting this interaction may be a potential therapeutic target. However, it can be challenging to configure a high-throughput screening (HTS)–compatible assay to detect inhibitors of a protein-protein interaction. Here we describe the development and challenges of an HTS for small-molecule inhibitors of the mutant SOD1-dynein interaction. We demonstrate that the interaction can be formed by coexpressing the A4V mutant SOD1 and dynein intermediate complex in cells and that this interaction can be disrupted by compounds added to the cell lysates. Finally, we show that some of the compounds identified from a pilot screen to inhibit the protein-protein interaction with this method specifically disrupt the interaction between the dynein complex and mtSOD1 but not the dynein complex itself when applied to live cells. PMID:22140121

  10. Cloning and characterization of cytoplasmic dynein intermediate chain in Fenneropenaeus chinensis and its essential role in white spot syndrome virus infection.

    PubMed

    Feng, Jixing; Tang, Xiaoqian; Zhan, Wenbin

    2014-08-01

    To investigate the role of cytoplasmic dynein in white spot syndrome virus (WSSV) infection, the full-length cDNA of cytoplasmic dynein intermediate chain (FcDYNCI) was cloned in Fenneropenaeus chinensis, which consists of 2582 bp and encodes a polypeptide of 660 amino acids. Sequence analysis and multiple sequence alignment displayed that FcDYNCI was a member of cytoplasmic dynein 1 family. The FcDYNCI mRNA was most highly expressed in hemocytes, which was significantly up-regulated post WSSV infection. At 12 h post infection (hpi), confocal microscopic observation showed that WSSV could be co-localized with cytoplasmic dynein in hemocytes. After silencing by specific FcDYNCI dsRNA, the FcDYNCI mRNA level and the protein amount of FcDYNCI in hemocytes both exhibited a significant reduction, and the expression levels of three WSSV genes ie1, wsv477 and vp28 all exhibited the greatest decreases at 24 hpi. These results suggested that cytoplasmic dynein was involved in WSSV infection.

  11. Katanin p80, NuMA and cytoplasmic dynein cooperate to control microtubule dynamics

    PubMed Central

    Jin, Mingyue; Pomp, Oz; Shinoda, Tomoyasu; Toba, Shiori; Torisawa, Takayuki; Furuta, Ken’ya; Oiwa, Kazuhiro; Yasunaga, Takuo; Kitagawa, Daiju; Matsumura, Shigeru; Miyata, Takaki; Tan, Thong Teck; Reversade, Bruno; Hirotsune, Shinji

    2017-01-01

    Human mutations in KATNB1 (p80) cause severe congenital cortical malformations, which encompass the clinical features of both microcephaly and lissencephaly. Although p80 plays critical roles during brain development, the underlying mechanisms remain predominately unknown. Here, we demonstrate that p80 regulates microtubule (MT) remodeling in combination with NuMA (nuclear mitotic apparatus protein) and cytoplasmic dynein. We show that p80 shuttles between the nucleus and spindle pole in synchrony with the cell cycle. Interestingly, this striking feature is shared with NuMA. Importantly, p80 is essential for aster formation and maintenance in vitro. siRNA-mediated depletion of p80 and/or NuMA induced abnormal mitotic phenotypes in cultured mouse embryonic fibroblasts and aberrant neurogenesis and neuronal migration in the mouse embryonic brain. Importantly, these results were confirmed in p80-mutant harboring patient-derived induced pluripotent stem cells and brain organoids. Taken together, our findings provide valuable insights into the pathogenesis of severe microlissencephaly, in which p80 and NuMA delineate a common pathway for neurogenesis and neuronal migration via MT organization at the centrosome/spindle pole. PMID:28079116

  12. Miro-1 links mitochondria and microtubule Dynein motors to control lymphocyte migration and polarity.

    PubMed

    Morlino, Giulia; Barreiro, Olga; Baixauli, Francesc; Robles-Valero, Javier; González-Granado, José M; Villa-Bellosta, Ricardo; Cuenca, Jesús; Sánchez-Sorzano, Carlos O; Veiga, Esteban; Martín-Cófreces, Noa B; Sánchez-Madrid, Francisco

    2014-04-01

    The recruitment of leukocytes to sites of inflammation is crucial for a functional immune response. In the present work, we explored the role of mitochondria in lymphocyte adhesion, polarity, and migration. We show that during adhesion to the activated endothelium under physiological flow conditions, lymphocyte mitochondria redistribute to the adhesion zone together with the microtubule-organizing center (MTOC) in an integrin-dependent manner. Mitochondrial redistribution and efficient lymphocyte adhesion to the endothelium require the function of Miro-1, an adaptor molecule that couples mitochondria to microtubules. Our data demonstrate that Miro-1 associates with the dynein complex. Moreover, mitochondria accumulate around the MTOC in response to the chemokine CXCL12/SDF-1α; this redistribution is regulated by Miro-1. CXCL12-dependent cell polarization and migration are reduced in Miro-1-silenced cells, due to impaired myosin II activation at the cell uropod and diminished actin polymerization. These data point to a key role of Miro-1 in the control of lymphocyte adhesion and migration through the regulation of mitochondrial redistribution.

  13. Miro-1 Links Mitochondria and Microtubule Dynein Motors To Control Lymphocyte Migration and Polarity

    PubMed Central

    Morlino, Giulia; Barreiro, Olga; Baixauli, Francesc; Robles-Valero, Javier; González-Granado, José M.; Villa-Bellosta, Ricardo; Cuenca, Jesús; Sánchez-Sorzano, Carlos O.; Veiga, Esteban; Martín-Cófreces, Noa B.

    2014-01-01

    The recruitment of leukocytes to sites of inflammation is crucial for a functional immune response. In the present work, we explored the role of mitochondria in lymphocyte adhesion, polarity, and migration. We show that during adhesion to the activated endothelium under physiological flow conditions, lymphocyte mitochondria redistribute to the adhesion zone together with the microtubule-organizing center (MTOC) in an integrin-dependent manner. Mitochondrial redistribution and efficient lymphocyte adhesion to the endothelium require the function of Miro-1, an adaptor molecule that couples mitochondria to microtubules. Our data demonstrate that Miro-1 associates with the dynein complex. Moreover, mitochondria accumulate around the MTOC in response to the chemokine CXCL12/SDF-1α; this redistribution is regulated by Miro-1. CXCL12-dependent cell polarization and migration are reduced in Miro-1-silenced cells, due to impaired myosin II activation at the cell uropod and diminished actin polymerization. These data point to a key role of Miro-1 in the control of lymphocyte adhesion and migration through the regulation of mitochondrial redistribution. PMID:24492963

  14. Katanin p80, NuMA and cytoplasmic dynein cooperate to control microtubule dynamics.

    PubMed

    Jin, Mingyue; Pomp, Oz; Shinoda, Tomoyasu; Toba, Shiori; Torisawa, Takayuki; Furuta, Ken'ya; Oiwa, Kazuhiro; Yasunaga, Takuo; Kitagawa, Daiju; Matsumura, Shigeru; Miyata, Takaki; Tan, Thong Teck; Reversade, Bruno; Hirotsune, Shinji

    2017-01-12

    Human mutations in KATNB1 (p80) cause severe congenital cortical malformations, which encompass the clinical features of both microcephaly and lissencephaly. Although p80 plays critical roles during brain development, the underlying mechanisms remain predominately unknown. Here, we demonstrate that p80 regulates microtubule (MT) remodeling in combination with NuMA (nuclear mitotic apparatus protein) and cytoplasmic dynein. We show that p80 shuttles between the nucleus and spindle pole in synchrony with the cell cycle. Interestingly, this striking feature is shared with NuMA. Importantly, p80 is essential for aster formation and maintenance in vitro. siRNA-mediated depletion of p80 and/or NuMA induced abnormal mitotic phenotypes in cultured mouse embryonic fibroblasts and aberrant neurogenesis and neuronal migration in the mouse embryonic brain. Importantly, these results were confirmed in p80-mutant harboring patient-derived induced pluripotent stem cells and brain organoids. Taken together, our findings provide valuable insights into the pathogenesis of severe microlissencephaly, in which p80 and NuMA delineate a common pathway for neurogenesis and neuronal migration via MT organization at the centrosome/spindle pole.

  15. Worldwide Report, Arms Control

    DTIC Science & Technology

    2007-11-02

    by S. Kulik U.S. Commitment to Space Arms Reagan Cited Weinberger Hit on ABM Treaty SDI, ABM Testing Violates Accords Said to Undermine ABM Treaty...that the creation of a large scale ABM system with outer space based elements is "a justified approach" to arms control. Yet the implementation of...countries agree that this is a new, long-term round of the arms race, and that the development of ABM weapons and the defense" system as a whole will

  16. Worldwide Report, Arms Control.

    DTIC Science & Technology

    2007-11-02

    Service, 1000 North Glebe Road, Arlington, Virginia 22201. JPRS-TAC-86-013 1 February 1986 WORLDWIDE REPORT ARMS CONTROL CONTENTS SDI AND SPACE ...ARMS LE SOIR on Possible European Space Defense (Pierre Lefevre; Brussels LE SOIR, 12 Dec 85) 1 SALT/START ISSUES USSR Hits U.S. Accusations of...PRS«TAO86*013 1 February 1986 SDI AND SPACE ARMS LE SOIR ON POSSIBLE EUROPEAN SPACE DEFENSE Brussels LE SOIR in French 12 Dec 85 p 8 [Article by

  17. MVACS Robotic Arm

    NASA Technical Reports Server (NTRS)

    Bonitz, R.; Slostad, J.; Bon, B.; Braun, D.; Brill, R.; Buck, C.; Fleischner, R.; Haldeman, A.; Herman, J.; Hertzel, M.; Noon, D.; Pixler, G.; Schenker, P.; Ton, T.; Tucker, C.; Zimmerman, W.

    2000-01-01

    The primary purpose of the Mars Volatiles and Climate Surveyor (MVACS) Robotic Arm is to support to the other MVACS science instruments by digging trenches in the Martian soil; acquiring and dumping soil samples into the thermal evolved gas analyzer (TEGA); positioning the Soil Temperature Probe (STP) in the soil: positioning the Robotic Arm Air Temperature Sensor (RAATS) at various heights above the surface, and positioning the Robotic Arm Camera (RAC) for taking images of the surface, trench, soil samples, magnetic targets and other objects of scientific interest within its workspace.

  18. Arm MRI scan

    MedlinePlus

    ... arm MRI (magnetic resonance imaging) scan uses strong magnets to create pictures of the upper and lower ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed into the room ...

  19. JPRS Report, Arms Control

    DTIC Science & Technology

    1990-02-23

    GDR, handguns , ammunition, explo- sives, communications and pioneer technology, certain ships, and military supplies are produced. In 1989, 1...appointed by the interior minister, and the defense, trade, and foreign ministers can issue licenses for arms traders to sign contracts. In disputed...Impossible Thought The group of politicians, diplomats, and soldiers who want to use arms control and disarmament to further their Own concealed

  20. Worldwide Report, Arms Control.

    DTIC Science & Technology

    2007-11-02

    ABM (Moscow TASS, 9, 10 Nov 85) 5 .U.S. ’New Interpretation’ 5 U.S. Posture Unchanged 5 PRAVDA 27 Oct Review of Week’s International Events...Space Arms Race (Beijing XINHUA, 8 Nov 85) ........................... 34 Briefs Senators Hit ABM Change 35 CSSR Representative Addresses UN...SDI AND SPACE ARMS TASS REPORTS NITZE NOVEMBER REMARKS ON SDI, ABM U.S. ’New Interpretation’ LD901421 Moscow TASS in English 1334 GMT 9 Nov 85

  1. Worldwide Report. Arms Control.

    DTIC Science & Technology

    2007-11-02

    knowledgeable people and came to the conclusion that the Pentagon official who has taught his son from infancy to fear and hate the USSR has influenced...missile. The U.S. Administration fears that defeat of the. MX in Congress could undermine the U.S. position>at the arms talks here. The Soviet delegation...swaggering. Behind this there is not only the fear that the gigantic arms ex- penditure could bring about a deficit crisis of enormous proportions

  2. ARM for Platform Application

    NASA Astrophysics Data System (ADS)

    Patte, Mathieu; Poupat, Jean-Luc; Le Meur, Patrick

    2015-09-01

    The activities described in this paper are part of the CNES R&T “Study of a Cortex-R ARM based architecture” performed by Airbus DS Space System & Electronics in 2014. With the support of CNES, Airbus DS has performed the porting of a representative space application software on an ARM based demonstration platform. This paper presents the platform itself, the activities performed at software level and the first results on this evaluation study.

  3. JPRS Report, Arms Control

    DTIC Science & Technology

    2007-11-02

    past 23 years, Senate President Jovito Salonga said yesterday. In an interview on government television, Salonga said the presence of nuclear arms...date and place not given] [Excerpts] The Bulgarian Government recently announced that it will reduce its armed forces by 10,000 soldiers, 200 tanks...unambiguous and does not leave any room for any kind of speculation, not even in Bonn’s government statement. Corresponding to the GDR’s peace

  4. Hello to Arms

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This image highlights the hidden spiral arms (blue) that were discovered around the nearby galaxy NGC 4625 by the ultraviolet eyes of NASA's Galaxy Evolution Explorer.

    The image is composed of ultraviolet and visible-light data, from the Galaxy Evolution Explorer and the California Institute of Technology's Digitized Sky Survey, respectively. Near-ultraviolet light is colored green; far-ultraviolet light is colored blue; and optical light is colored red.

    As the image demonstrates, the lengthy spiral arms are nearly invisible when viewed in optical light while bright in ultraviolet. This is because they are bustling with hot, newborn stars that radiate primarily ultraviolet light.

    The youthful arms are also very long, stretching out to a distance four times the size of the galaxy's core. They are part of the largest ultraviolet galactic disk discovered so far.

    Located 31 million light-years away in the constellation Canes Venatici, NGC 4625 is the closest galaxy ever seen with such a young halo of arms. It is slightly smaller than our Milky Way, both in size and mass. However, the fact that this galaxy's disk is forming stars very actively suggests that it might evolve into a more massive and mature galaxy resembling our own.

    The armless companion galaxy seen below NGC 4625 is called NGC 4618. Astronomers do not know why it lacks arms but speculate that it may have triggered the development of arms in NGC 4625.

  5. Look at my Arms!

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This image shows the hidden spiral arms that were discovered around the galaxy called NGC 4625 (top) by the ultraviolet eyes of NASA's Galaxy Evolution Explorer. An armless companion galaxy called NGC 4618 is pictured below.

    Though the lengthy spiral arms are nearly invisible when viewed in optical light, they glow brightly in ultraviolet. This is because they are bustling with hot, newborn stars that radiate primarily ultraviolet light.

    The youthful arms are also very long, stretching out to a distance four times the size of the galaxy's core. They are part of the largest ultraviolet galactic disk discovered so far.

    Located 31 million light-years away in the constellation Canes Venatici, NGC 4625 is the closest galaxy ever seen with such a young halo of arms. It is slightly smaller than our Milky Way, both in size and mass. However, the fact that this galaxy's disk is forming stars very actively suggests that it might evolve into a more massive and mature galaxy resembling our own.

    Astronomers do not know why NGC 4618 lacks arms but speculate that it may have triggered the development of arms in NGC 4625.

  6. Kinematically redundant arm formulations for coordinated multiple arm implementations

    NASA Technical Reports Server (NTRS)

    Bailey, Robert W.; Quiocho, Leslie J.; Cleghorn, Timothy F.

    1990-01-01

    Although control laws for kinematically redundant robotic arms were presented as early as 1969, redundant arms have only recently become recognized as viable solutions to limitations inherent to kinematically sufficient arms. The advantages of run-time control optimization and arm reconfiguration are becoming increasingly attractive as the complexity and criticality of robotic systems continues to progress. A generalized control law for a spatial arm with 7 or more degrees of freedom (DOF) based on Whitney's resolved rate formulation is given. Results from a simulation implementation utilizing this control law are presented. Furthermore, results from a two arm simulation are presented to demonstrate the coordinated control of multiple arms using this formulation.

  7. Photosensitized cleavage of dynein heavy chains. Cleavage at the V1 site by irradiation at 365 nm in the presence of ATP and vanadate

    SciTech Connect

    Gibbons, I.R.; Lee-Eiford, A.; Mocz, G.; Phillipson, C.A.; Tang, W.J.; Gibbons, B.H.

    1987-02-25

    Irradiation of soluble dynein 1 from sea urchin sperm flagella at 365 nm in the presence of MgATP and 0.05-50 microM vanadate (Vi) cleaves the alpha and beta heavy chains (Mr 428,000) at their V1 sites to give peptides of Mr 228,000 and 200,000, without the nonspecific side effects produced by irradiation at 254 nm as described earlier. The decrease in intact heavy chain material is biphasic; in 10 microM Vi, approximately 80% occurs with a half-time of 7 min and the remainder with a half-time of about 90 min, and the yield of cleavage peptides is better than 90%. Loss of dynein ATPase activity appears to be a direct result of the cleavage process and is not significantly affected by the presence of up to 0.1 M cysteamine (CA, 60-23-1) or 2-aminoethyl carbamimidothioic acid dihydrobromide (CA, 56-10-0) as free radical trapping agents. The concentration of Vi required for 50% maximal initial cleavage rate is 4.5 microM, while that for 50% ATPase inhibition is 0.8 microM, both in a 0.6 M NaCl medium. In the presence of 20 microM Vi, CTP and UTP support cleavage at about half the rate of ATP, whereas GTP and ITP support cleavage only if the Vi concentration is raised to about 200 microM. Substitution of any of the transition metal cations Cr2+, Mn2+, Fe2+, or Co2+ for the usual Mg2+ suppresses the photocleavage, presumably by quenching the excited chromophore prior to scission of the heavy chain. The photocleaved dynein 1 binds to dynein-depleted flagella similarly to intact dynein 1, but upon reactivation of the flagella with 1 mM ATP their motility is partially inhibited, rather than being augmented as with intact dynein.

  8. Residual structure and dynamics in DMSO-d6 denatured dynein light chain protein.

    PubMed

    Chakraborty, Swagata; Mohan, P M Krishna; Hosur, Ramakrishna V

    2012-01-01

    Structural and motional features in the denatured state of a protein dictate the early folding events starting from that state and these features vary depending upon the nature of the denaturant used. Here, we have attempted to decipher the early events in the folding of Dynein Light Chain protein (DLC8), starting from DMSO-d6 denatured state. Multinuclear NMR experiments were used to obtain the full spectral assignment. The HSQC spectrum shows the presence of two sets of peaks for the residues Met 1, Ser 2, Arg 4, Ala 11, Met 17, Thr 26, Lys 44, Tyr 50, Asn 51, Trp 54, His 55, Val 58, Gly 59, Ser 64, Tyr 65, His 68, Phe 86, Lys 87 indicating the presence of slow conformational transition in the heterogeneous ensemble. Analysis of residual structural propensities with secondary (13)C chemical shifts, (3)J(H(N)(-)H(α)) coupling constants and (1)H-(1)H NOE revealed the presence of local preferences which encompass both native and non-native like structures. The spectral density calculations, as obtained from measured R(1), R(2) and (1)H-(15)N steady state NOE values provide insights into the backbone dynamics on the milli to picosecond timescale. The segment Ser 14 - His 55 exhibits slow motions on the milli- to microsecond timescale arising from conformational exchange. The presence of native like structural preference, as well as conformational exchange classifies the above segment as the nucleation site of folding. Based on the observations, we propose here, the probable hierarchy of folding of DLC8 on dilution of denaturant: the two helices are formed first followed by the formation of β2 and β5.

  9. PHACE without face? Infantile hemangiomas of the upper body region with minimal or absent facial hemangiomas and associated structural malformations.

    PubMed

    Nabatian, Adam S; Milgraum, Sandy S; Hess, Christopher P; Mancini, Anthony J; Krol, Alfons; Frieden, Ilona J

    2011-01-01

    Infantile hemangiomas can be associated with congenital anomalies such as PHACE syndrome with facial hemangiomas and genitourinary and spinal anomalies in the setting of lower body hemangiomas. We describe five infants in whom segmental hemangiomas involving the upper torso and extremities with absent or small facial hemangiomas were associated with structural anomalies similar to those reported with PHACE syndrome, including three with structural arterial anomalies of the subclavian arteries, three with aortic arch anomalies (right sided or narrowed arch), two with congenital heart disease (atrial septal defect and ventricular septal defect; tetralogy of Fallot), one with a retinal scar, and one with a sternal defect (scar). Two of five had small facial hemangiomas of the lower lip, but none had large segmental hemangiomas of the face. Three of five would have met diagnostic criteria for PHACE but lacked a facial hemangioma of 5 cm in diameter or greater. Patients with segmental arm and thorax hemangiomas may have associated structural abnormalities with overlapping features of PHACE, suggesting that a similar syndrome can occur in this clinical setting.

  10. Mystery Spiral Arms Explained?

    NASA Astrophysics Data System (ADS)

    2007-04-01

    Using a quartet of space observatories, University of Maryland astronomers may have cracked a 45-year mystery surrounding two ghostly spiral arms in the galaxy M106. The Maryland team, led by Yuxuan Yang, took advantage of the unique capabilities of NASA's Chandra X-ray Observatory, NASA's Spitzer Space Telescope, the European Space Agency's XMM-Newton X-ray observatory, and data obtained almost a decade ago with NASA's Hubble Space Telescope. NGC X-ray Image NGC 4258 X-ray Image M106 (also known as NGC 4258) is a stately spiral galaxy 23.5 million light-years away in the constellation Canes Venatici. In visible-light images, two prominent arms emanate from the bright nucleus and spiral outward. These arms are dominated by young, bright stars, which light up the gas within the arms. "But in radio and X-ray images, two additional spiral arms dominate the picture, appearing as ghostly apparitions between the main arms," says team member Andrew Wilson of the University of Maryland. These so-called "anomalous arms" consist mostly of gas. "The nature of these anomalous arms is a long-standing puzzle in astronomy," says Yang. "They have been a mystery since they were first discovered in the early 1960s." By analyzing data from XMM-Newton, Spitzer, and Chandra, Yang, Bo Li, Wilson, and Christopher Reynolds, all at the University of Maryland at College Park, have confirmed earlier suspicions that the ghostly arms represent regions of gas that are being violently heated by shock waves. Previously, some astronomers had suggested that the anomalous arms are jets of particles being ejected by a supermassive black hole in M106's nucleus. But radio observations by the National Radio Astronomy Observatory's Very Long Baseline Array, and the Very Large Array in New Mexico, later identified another pair of jets originating in the core. "It is highly unlikely that an active galactic nucleus could have more than one pair of jets," says Yang. In 2001, Wilson, Yang, and Gerald Cecil

  11. Arms Industry limited

    SciTech Connect

    Wulf, H.

    1993-12-31

    The intent of this study is to give an overview of the present state of the world arms industry. It is an empirical account of the size of the industry and particularly its present problems. The authors examine the economic pressures that affect the international arms trade. Specifically, it raises the question of how dependent the industry is on weapons production and exports, and whether there are any alternatives. Export dependence of the major weapons producing countries is a major focus. The book focus`s on private industry as opposed to examination of national governments. Despite the passing of the Cold War and some brief post-Gulf War euphoria about the possibility of greater restrain on the part of weapons exporters, the conventional arms trade is alive and well, albeit with new variations.

  12. Robotic Arm Unwrapped

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This image, taken shortly after NASA's Phoenix Mars Lander touched down on the surface of Mars, shows the spacecraft's robotic arm in its stowed configuration, with its biobarrier successfully unpeeled. The 'elbow' of the arm can be seen at the top center of the picture, and the biobarrier is the shiny film seen to the left of the arm.

    The biobarrier is an extra precautionary measure for protecting Mars from contamination with any bacteria from Earth. While the whole spacecraft was decontaminated through cleaning, filters and heat, the robotic arm was given additional protection because it is the only spacecraft part that will directly touch the ice below the surface of Mars.

    Before the arm was heated, it was sealed in the biobarrier, which is made of a trademarked film called Tedlar that holds up to baking like a turkey-basting bag. This ensures that any new bacterial spores that might have appeared during the final steps before launch and during the journey to Mars will not contact the robotic arm.

    After Phoenix landed, springs were used to pop back the barrier, giving it room to deploy.

    The base of the lander's Meteorological Station can be seen in this picture on the upper left. Because only the base of the station is showing, this image tells engineers that the instrument deployed successfully.

    The image was taken on landing day, May 25, 2008, by the spacecraft's Surface Stereo Imager.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  13. Worldwide Report, Arms Control.

    DTIC Science & Technology

    2007-11-02

    means and ofI large-scale system of so-called ABM defense coupled with the buildup of strategic offensive arms is also aimed at smashing the strategic...strategic defense". On this basis they assert, firstly, that there is as yet no real threat of an all-embracing ABM system being deployed, and, se- PnlifUÜf...States is not violating any of its commitments on arms limitations, above all those envisaged under the ABM treaty. It is common knowledge that

  14. Worldwide Report Arms Control

    DTIC Science & Technology

    1987-02-04

    GMT 4 Jan 87 LD] /9738 CSO: 5200/1128 11 U.S.«-USSR NUCLEAR AND SPACE ARMS TALKS GORBACHEV, REAGAN NEW YEAR MESSAGES ON DISARMAMENT Reagan to...Moscow PRAVDA in Russian 28 Dec 86 First Edition p 4 [Vitaliy Korionov "International Review"] [Excerpts] Only a few days remain until the New Year...105063 JPRS-TAC-87-OlO 4 FEBRUARY 1987 Worldwide Report ARMS CONTROL ’DUO QUALITY BFSPSSTEP * 19980515 022 FBIS FOREIGN BROADCAST■1NFORMAtlÖN

  15. JAM-A regulates cortical dynein localization through Cdc42 to control planar spindle orientation during mitosis.

    PubMed

    Tuncay, Hüseyin; Brinkmann, Benjamin F; Steinbacher, Tim; Schürmann, Annika; Gerke, Volker; Iden, Sandra; Ebnet, Klaus

    2015-08-26

    Planar spindle orientation in polarized epithelial cells depends on the precise localization of the dynein-dynactin motor protein complex at the lateral cortex. The contribution of cell adhesion molecules to the cortical localization of the dynein-dynactin complex is poorly understood. Here we find that junctional adhesion molecule-A (JAM-A) regulates the planar orientation of the mitotic spindle during epithelial morphogenesis. During mitosis, JAM-A triggers a transient activation of Cdc42 and PI(3)K, generates a gradient of PtdIns(3,4,5)P3 at the cortex and regulates the formation of the cortical actin cytoskeleton. In the absence of functional JAM-A, dynactin localization at the cortex is reduced, the mitotic spindle apparatus is misaligned and epithelial morphogenesis in three-dimensional culture is compromised. Our findings indicate that a PI(3)K- and cortical F-actin-dependent pathway of planar spindle orientation operates in polarized epithelial cells to regulate epithelial morphogenesis, and we identify JAM-A as a junctional regulator of this pathway.

  16. Dynactin-dependent cortical dynein and spherical spindle shape correlate temporally with meiotic spindle rotation in Caenorhabditis elegans

    PubMed Central

    Crowder, Marina E.; Flynn, Jonathan R.; McNally, Karen P.; Cortes, Daniel B.; Price, Kari L.; Kuehnert, Paul A.; Panzica, Michelle T.; Andaya, Armann; Leary, Julie A.; McNally, Francis J.

    2015-01-01

    Oocyte meiotic spindles orient with one pole juxtaposed to the cortex to facilitate extrusion of chromosomes into polar bodies. In Caenorhabditis elegans, these acentriolar spindles initially orient parallel to the cortex and then rotate to the perpendicular orientation. To understand the mechanism of spindle rotation, we characterized events that correlated temporally with rotation, including shortening of the spindle in the pole-to pole axis, which resulted in a nearly spherical spindle at rotation. By analyzing large spindles of polyploid C. elegans and a related nematode species, we found that spindle rotation initiated at a defined spherical shape rather than at a defined spindle length. In addition, dynein accumulated on the cortex just before rotation, and microtubules grew from the spindle with plus ends outward during rotation. Dynactin depletion prevented accumulation of dynein on the cortex and prevented spindle rotation independently of effects on spindle shape. These results support a cortical pulling model in which spindle shape might facilitate rotation because a sphere can rotate without deforming the adjacent elastic cytoplasm. We also present evidence that activation of spindle rotation is promoted by dephosphorylation of the basic domain of p150 dynactin. PMID:26133383

  17. Worldwide Report, Arms Control

    DTIC Science & Technology

    1985-12-28

    Dec 85 [Text] Moscow, December 3 TASS —TASS political news analyst valerity Vavilov writes: The defence ministers of the twelve West European NATO...that during the second Taiwan crisis of 1958, the use of nuclear arms against China was very close to reality. (In August of that year, the U.S. 7th

  18. JPRS Report, Arms Control

    DTIC Science & Technology

    2007-11-02

    34military activities, whether in the armed forces, their civilian sectors, or in the ’defence’ indus- try". In another paper Professor Carl Sagan ...spurring the development of new weapons. Star Wars is a case in point. As Carl Sagan puts it, the idea is doomed: "SDI is ruinously expensive, it can

  19. Worldwide Report, Arms Control.

    DTIC Science & Technology

    1985-08-12

    thai, in the long run one cannot oven tell to willy frandi’and fgon fahr . ’r’ho Soviets arc thus evoking the suspicion that they are playing dirty...material resources and the knowledge of scientists in combatting diseases , if the resources were spent on it that are taken up by the arms race

  20. JPRS Report, Arms Control.

    DTIC Science & Technology

    2007-11-02

    Joint-Stock Company"] [Text] A constituent conference of the "Ural- Kosmos " closed joint-stock company [aktsionernoye obshchestvo zakrytogo tipa] has...due to be destroyed under arms cuts. Their warheads will be replaced by communications satellites. The founders of the "Ural- Kosmos " company note

  1. Effectiveness of a dynein team in a tug of war helped by reduced load sensitivity of detachment: evidence from the study of bidirectional endosome transport in D. discoideum

    NASA Astrophysics Data System (ADS)

    Bhat, Deepak; Gopalakrishnan, Manoj

    2012-08-01

    Bidirectional cargo transport by molecular motors in cells is a complex phenomenon in which the cargo (usually a vesicle) alternately moves in retrograde and anterograde directions. In this case, teams of oppositely pulling motors (e.g., kinesin and dynein) bind to the cargo, simultaneously, and ‘coordinate’ their activity such that the motion consists of spells of positively and negatively directed segments, separated by pauses of varying duration. A set of recent experiments have analyzed the bidirectional motion of endosomes in the amoeba D. discoideum in detail. It was found that in between directional switches, a team of five to six dyneins stall a cargo against a stronger kinesin in a tug of war, which lasts for almost a second. As the mean detachment time of a kinesin under its stall load was also observed to be ˜1 s, we infer that the collective detachment time of the dynein assembly must also be similar. Here, we analyze this inference from a modeling perspective, using experimentally measured single-molecule parameters as inputs. We find that the commonly assumed exponential load-dependent detachment rate is inconsistent with observations, as it predicts that a five-dynein assembly will detach under its combined stall load in less than a hundredth of a second. A modified model where the load-dependent unbinding rate is assumed to saturate at stall-force level for super-stall loads gives results which are in agreement with experimental data. Our analysis suggests that the load-dependent detachment of a dynein in a team is qualitatively different at sub-stall and super-stall loads, a conclusion which is likely to have implications in other situations involving collective effects of many motors.

  2. Effectiveness of a dynein team in a tug of war helped by reduced load sensitivity of detachment: evidence from the study of bidirectional endosome transport in D. discoideum.

    PubMed

    Bhat, Deepak; Gopalakrishnan, Manoj

    2012-08-01

    Bidirectional cargo transport by molecular motors in cells is a complex phenomenon in which the cargo (usually a vesicle) alternately moves in retrograde and anterograde directions. In this case, teams of oppositely pulling motors (e.g., kinesin and dynein) bind to the cargo, simultaneously, and 'coordinate' their activity such that the motion consists of spells of positively and negatively directed segments, separated by pauses of varying duration. A set of recent experiments have analyzed the bidirectional motion of endosomes in the amoeba D. discoideum in detail. It was found that in between directional switches, a team of five to six dyneins stall a cargo against a stronger kinesin in a tug of war, which lasts for almost a second. As the mean detachment time of a kinesin under its stall load was also observed to be ∼1 s, we infer that the collective detachment time of the dynein assembly must also be similar. Here, we analyze this inference from a modeling perspective, using experimentally measured single-molecule parameters as inputs. We find that the commonly assumed exponential load-dependent detachment rate is inconsistent with observations, as it predicts that a five-dynein assembly will detach under its combined stall load in less than a hundredth of a second. A modified model where the load-dependent unbinding rate is assumed to saturate at stall-force level for super-stall loads gives results which are in agreement with experimental data. Our analysis suggests that the load-dependent detachment of a dynein in a team is qualitatively different at sub-stall and super-stall loads, a conclusion which is likely to have implications in other situations involving collective effects of many motors.

  3. Inhibition of microtubules and dynein rescues human immunodeficiency virus type 1 from owl monkey TRIMCyp-mediated restriction in a cellular context-specific fashion.

    PubMed

    Pawlica, Paulina; Dufour, Caroline; Berthoux, Lionel

    2015-04-01

    IFN-induced restriction factors can significantly affect the replicative capacity of retroviruses in mammals. TRIM5α (tripartite motif protein 5, isoform α) is a restriction factor that acts at early stages of the virus life cycle by intercepting and destabilizing incoming retroviral cores. Sensitivity to TRIM5α maps to the N-terminal domain of the retroviral capsid proteins. In several New World and Old World monkey species, independent events of retrotransposon-mediated insertion of the cyclophilin A (CypA)-coding sequence in the trim5 gene have given rise to TRIMCyp (also called TRIM5-CypA), a hybrid protein that is active against some lentiviruses in a species-specific fashion. In particular, TRIMCyp from the owl monkey (omkTRIMCyp) very efficiently inhibits human immunodeficiency virus type 1 (HIV-1). Previously, we showed that disrupting the integrity of microtubules (MTs) and of cytoplasmic dynein complexes partially rescued replication of retroviruses, including HIV-1, from restriction mediated by TRIM5α. Here, we showed that efficient restriction of HIV-1 by omkTRIMCyp was similarly dependent on the MT network and on dynein complexes, but in a context-dependent fashion. When omkTRIMCyp was expressed in human HeLa cells, restriction was partially counteracted by pharmacological agents targeting MTs or by small interfering RNA-mediated inhibition of dynein. The same drugs (nocodazole and paclitaxel) also rescued HIV-1 from restriction in cat CRFK cells, although to a lesser extent. Strikingly, neither nocodazole, paclitaxel nor depletion of the dynein heavy chain had a significant effect on the restriction of HIV-1 in an owl monkey cell line. These results suggested the existence of cell-specific functional interactions between MTs/dynein and TRIMCyp.

  4. Case Study: The Perception of Online Tutorials--Habitually Absent Students with Familial or Socioeconomic Circumstances

    ERIC Educational Resources Information Center

    Hudson, Glyniss A.

    2013-01-01

    This case study explored the perception of online tutorials by habitually absent students with familial or socioeconomic circumstances. Researched literature confirmed a link between absenteeism, and academic achievement. Research Questions were designed to determine (a) student perception of online tutorials, and (b) motivation to achieve…

  5. Eyeless initiates the expression of both sine oculis and eyes absent during Drosophila compound eye development.

    PubMed

    Halder, G; Callaerts, P; Flister, S; Walldorf, U; Kloter, U; Gehring, W J

    1998-06-01

    The Drosophila Pax-6 gene eyeless acts high up in the genetic hierarchy involved in compound eye development and can direct the formation of extra eyes in ectopic locations. Here we identify sine oculis and eyes absent as two mediators of the eye-inducing activity of eyeless. We show that eyeless induces and requires the expression of both genes independently during extra eye development. During normal eye development, eyeless is expressed earlier than and is required for the expression of sine oculis and eyes absent, but not vice versa. Based on the results presented here and those of others, we propose a model in which eyeless induces the initial expression of both sine oculis and eyes absent in the eye disc. sine oculis and eyes absent then appear to participate in a positive feedback loop that regulates the expression of all three genes. In contrast to the regulatory interactions that occur in the developing eye disc, we also show that in the embryonic head, sine oculis acts in parallel to eyeless and twin of eyeless, a second Pax-6 gene from Drosophila. Recent studies in vertebrate systems indicate that the epistatic relationships among the corresponding vertebrate homologs are very similar to those observed in Drosophila.

  6. When Familiar Is Not Better: 12-Month-Old Infants Respond to Talk about Absent Objects

    ERIC Educational Resources Information Center

    Osina, Maria A.; Saylor, Megan M.; Ganea, Patricia A.

    2013-01-01

    Three experiments that demonstrate a novel constraint on infants' language skills are described. Across the experiments it is shown that as babies near their 1st birthday, their ability to respond to talk about an absent object is influenced by a referent's spatiotemporal history: familiarizing infants with an object in 1 or several nontest…

  7. Reconstruction of a congenitally absent flexor pollicis longus in an adult

    PubMed Central

    Shamsian, Negin; Exton, Rebecca; Shibu, MM

    2010-01-01

    Congenital absence of the flexor pollicis longus (FPL) is an unusual finding that is frequently associated with thumb hypoplasia. Isolated FPL absence is the rarest of the congenital thumb anomalies. The present article describes a patient with a congenitally absent FPL, and discusses the chosen method of reconstruction. PMID:22131842

  8. Robotic Arm of Rover 1

    NASA Technical Reports Server (NTRS)

    2003-01-01

    JPL engineers examine the robotic arm of Mars Exploration Rover 1. The arm is modeled after a human arm, complete with joints, and holds four devices on its end, the Rock Abrasion Tool which can grind into Martian rocks, a microscopic imager, and two spectrometers for elemental and iron-mineral identification.

  9. Cytoskeletal architecture of isolated mitotic spindle with special reference to microtubule-associated proteins and cytoplasmic dynein.

    PubMed

    Hirokawa, N; Takemura, R; Hisanaga, S

    1985-11-01

    We have studied cytoskeletal architectures of isolated mitotic apparatus from sea urchin eggs using quick-freeze, deep-etch electron microscopy. This method revealed the existence of an extensive three-dimensional network of straight and branching crossbridges between spindle microtubules. The surface of the spindle microtubules was almost entirely covered with hexagonally packed, small, round button-like structures which were very uniform in shape and size (approximately 8 nm in diameter), and these microtubule buttons frequently provided bases for crossbridges between adjacent microtubules. These structures were removed from the surface of microtubules by high salt (0.6 M NaCl) extraction. Microtubule-associated proteins (MAPs) and microtubules isolated from mitotic spindles which were mainly composed of a large amount of 75-kD protein and some high molecular mass (250 kD, 245 kD) proteins were polymerized in vitro and examined by quick-freeze, deep-etch electron microscopy. The surfaces of microtubules were entirely covered with the same hexagonally packed round buttons, the arrangement of which is intimately related to that of tubulin dimers. Short crossbridges and some longer crossbridges were also observed. High salt treatment (0.6 M NaCl) extracted both 75-kD protein and high molecular weight proteins and removed microtubule buttons and most of crossbridges from the surface of microtubules. Considering the relatively high amount of 75-kD protein among MAPs isolated from mitotic spindles, it is concluded that these microtubule buttons probably consist of 75-kD MAP and that some of the crossbridges in vivo could belong to MAPs. Another kind of granule, larger in size (11-26 nm in diameter), was also on occasion associated with the surface of microtubules of mitotic spindles. A fine sidearm sometimes connected the larger granule to adjacent microtubules. Localization of cytoplasmic dynein ATPase in the mitotic spindle was investigated by electron microscopic

  10. ARM User Survey Report

    SciTech Connect

    Roeder, LR

    2010-06-22

    The objective of this survey was to obtain user feedback to, among other things, determine how to organize the exponentially growing data within the Atmospheric Radiation Measurement (ARM) Climate Research Facility, and identify users’ preferred data analysis system. The survey findings appear to have met this objective, having received approximately 300 responses that give insight into the type of work users perform, usage of the data, percentage of data analysis users might perform on an ARM-hosted computing resource, downloading volume level where users begin having reservations, opinion about usage if given more powerful computing resources (including ability to manipulate data), types of tools that would be most beneficial to them, preferred programming language and data analysis system, level of importance for certain types of capabilities, and finally, level of interest in participating in a code-sharing community.

  11. Microelectromechanical safe arm device

    DOEpatents

    Roesler, Alexander W [Tijeras, NM

    2012-06-05

    Microelectromechanical (MEM) apparatus and methods for operating, for preventing unintentional detonation of energetic components comprising pyrotechnic and explosive materials, such as air bag deployment systems, munitions and pyrotechnics. The MEM apparatus comprises an interrupting member that can be moved to block (interrupt) or complete (uninterrupt) an explosive train that is part of an energetic component. One or more latching members are provided that engage and prevent the movement of the interrupting member, until the one or more latching members are disengaged from the interrupting member. The MEM apparatus can be utilized as a safe and arm device (SAD) and electronic safe and arm device (ESAD) in preventing unintentional detonations. Methods for operating the MEM apparatus include independently applying drive signals to the actuators coupled to the latching members, and an actuator coupled to the interrupting member.

  12. Robot arm apparatus

    DOEpatents

    Nachbar, Henry D.

    1992-12-01

    A robot arm apparatus is provided for inspecting and/or maintaining an interior of a steam generator which has an outside wall and a port for accessing the interior of the steam generator. The robot arm apparatus includes a flexible movable conduit for conveying inspection and/or maintenance apparatus from outside the steam generator to the interior of the steam generator. The flexible conduit has a terminal working end which is translated into and around the interior of the steam generator. Three motors located outside the steam generator are employed for moving the terminal working end inside the steam generator in "x", "y", and "z" directions, respectively. Commonly conducted inspection and maintenance operations include visual inspection for damaged areas, water jet lancing for cleaning sludge deposits, core boring for obtaining sludge deposits, and scrubbing of internal parts.

  13. Robot arm apparatus

    DOEpatents

    Nachbar, Henry D.

    1992-01-01

    A robot arm apparatus is provided for inspecting and/or maintaining an interior of a steam generator which has an outside wall and a port for accessing the interior of the steam generator. The robot arm apparatus includes a flexible movable conduit for conveying inspection and/or maintenance apparatus from outside the steam generator to the interior of the steam generator. The flexible conduit has a terminal working end which is translated into and around the interior of the steam generator. Three motors located outside the steam generator are employed for moving the terminal working end inside the steam generator in "x", "y", and "z" directions, respectively. Commonly conducted inspection and maintenance operations include visual inspection for damaged areas, water jet lancing for cleaning sludge deposits, core boring for obtaining sludge deposits, and scrubbing of internal parts.

  14. Robot arm apparatus

    SciTech Connect

    Nachbar, H.D.

    1990-12-31

    A robot arm apparatus is provided for inspecting and/or maintaining an interior of a steam generator which has an outside wall and a port for accessing the interior of the steam generator. The robot arm apparatus includes a flexible movable conduit for conveying inspection and/or maintenance apparatus from outside the steam generator to the interior of the steam generator. The flexible conduit has a terminal working end which is translated into and around the interior of the steam generator. Three motors located outside the steam generator are employed for moving the terminal working end inside the steam generator in ``x,`` ``y,`` and ``z`` directions, respectively. Commonly conducted inspection and maintenance operations include visual inspection for damaged areas, water jet lancing for cleaning sludge deposits, core boring for obtaining sludge deposits, and scrubbing of internal parts.

  15. Worldwide Report, Arms Control

    DTIC Science & Technology

    2007-11-02

    of its missiles in Western Europe is a continuation of the policy of upsetting the established approximate equilibrium in the illusory hope of...measures in Europe. The Soviet Union advocates a sharp reduction in the level of medium-range nuclear means, with strict observance of equilibrium ...maintaining strategic equilibrium and its stability. But if this happens, the case in point will be a new round of the arms race. As is known, there were no

  16. Small arms ammunition

    DOEpatents

    Huerta, Joseph

    1992-01-01

    An elongate projectile for small arms use has a single unitary mass with a hollow nose cavity defined by a sharp rigid cutting edge adapted to make initial contact with the target surface and cut therethrough. The projectile then enters the target mass in an unstable flight mode. The projectile base is substantially solid such that the nose cavity, while relatively deep, does not extend entirely through the base and the projectile center of gravity is aft of its geometric center.

  17. JPRS Report, Arms Control.

    DTIC Science & Technology

    2007-11-02

    negotiations on all weapons categories. He said on Sunday in the ZDF [second German television] program "Bonn Direkt " that German foreign policy has...JPRS-TAC-89-021 25 MAY 1989 fflflBBl FOREIGN BROADCAST INFORMATION SERVICE JPRS Report— Arms Control A99S07A51® REPRODUCED BY U.S...Libyan Envoy Requests Meeting [THAI RAT 14 May] 16 Paper Criticizes U.S. Warning [MATICHON 13 May] 17 Foreign Minister Interviewed [Bangkok Radio

  18. JPRS Report, Arms Control

    DTIC Science & Technology

    2007-11-02

    19980715 176 REPRODUCED BY U.S. DEPARTMENT OF COMMERCE NATIONAL TECHNICAL INFORMATION SERVICE SPRINGFIELD, VA. 22161 DTIC QUALITY INSPECTED X Arms...South Korean authorities are not in a position, for some reasons, to respond to our proposal right now, they should take at least practical measures...prevented, he said, nuclear weapons and their delivery vehicles should be removed. But, if the United States is not prepared for this right now, we

  19. Coat of Arms.

    ERIC Educational Resources Information Center

    Smith, Bryan

    1998-01-01

    Describes an activity, the "coat of arms," that can serve as an ice-breaker or warm-up for the first day of an English-as-a-Second/Foreign-Language class, as a motivating start to the week, or act as an innovative segue between skill lessons. The technique can be adapted for students ranging from elementary school to adult language learners of all…

  20. Robotic Arm End Effector

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Image illustrates the tools on the end of the arm that are used to acquire samples, image the contents of the scoop, and perform science experiments.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  1. JPRS Report, Arms Control.

    DTIC Science & Technology

    2007-11-02

    have to be comprehensively reduced before NATo cuts back on its arms. Those in the West, who attribute all progress to Gor- bachev’s behavior , have...disarmament expert Werner Hoyer stressed that there should not be any delay in beginning negotiations on this, from the German point of view. All...information or assistance, call FBIS, (202) 338-6735,or write to PO Box 2604, Washington, D.C. 20013. Department of Defense consumers are required to

  2. Worldwide Report, Arms Control.

    DTIC Science & Technology

    1985-07-30

    Viewed, by Tang Tianri 29 Issues Assessed, by Tang Xiushan 31 SPACE ARMS USSR: Reports, Comments on Bush Trip to Europe To Push SDI (Various...85) 99 Indian Prime Minister Criticizes ’Star Wars’ (Bombay THE TIMES OF INDIA, 7 Jun 85) 101 Briefs USSR: U.S. Laser Test Planned 103 TASS...a tangible political disagree- ment. The Norwegian defense minister does not think that an attack will come of out of the blue . The foreign

  3. Worldwide Report, Arms Control.

    DTIC Science & Technology

    2007-11-02

    effective measures to feelings of those Americans who are demanding effective measures to limit the arms race, Weinberger hypocritically said that the...way to conduct effective negotiations." Mr Weinberger knows very well that speaking the language of diktat to the Soviet Union is an activity with...the ABM Treaty"] [Text] The Soviet-American Treaty on the Limitation of ABM Systems, concluded in May 1972, has now been in effect for more than 13

  4. JPRS Report, Arms Control.

    DTIC Science & Technology

    2007-11-02

    JPRS-TAC-89-025 21 JUNE 1989 !■■■■■ FOREIGN BROADCAST INFORMATION SERVICE -/P/? S #;# Arms Control \\ɘIÜ REPRODUCED BY U.S. DEPARTMENT OF...Compromise on SNF Issue [ S . Gjoka; ZERIIPOPULLIT 31 May] 11 U.S. Troop Reduction Proposals Critiqued [ S . Beqari; ZERI I POPULLIT 7 Jun] 12 BULGARIA...Petrov; RABOTNICHESKO DELO 7 Jun] 16 CZECHOSLOVAKIA Commentary Critiques Bush CFE, SNF Proposals [B. Zagar ; Bratislava PRAVDA 3 Jun] 18

  5. JPRS Report, Arms Control

    DTIC Science & Technology

    2007-11-02

    dangerous because the measure of control by central political organs of the state over conventional weapons and their military use is substan...It is always under the control and guidance of governments of the interested parties, it is the most manageable and has the least inertia. It...JPRS-TAC-89-001 10 JANUARY 1989 —JPRS Report— Arms Control nTSTRJBUTlON STATEMfcwTA Approved for public release; Distribution Unlimited n

  6. Sdi and arms control

    SciTech Connect

    DeWolf, H.G.

    1989-11-01

    President Reagan's Strategic Defense Initiative, or SDI, and the pursuit of defenses to protect against ballistic missile attack are issues of significant debate. Some praise the proposal, first made in a presidential address to the nation on 23 March 1983, as a grand vision that will abolish nuclear blackmail by adopting a totally defensive posture. Others condemn it as being destabilizing, a Pandora's box of strategic transition that could precipitate armed conflict.

  7. Phoenix Robotic Arm

    NASA Technical Reports Server (NTRS)

    2007-01-01

    A vital instrument on NASA's Phoenix Mars Lander is the robotic arm, which will dig into the icy soil and bring samples back to the science deck of the spacecraft for analysis. In September 2006 at a Lockheed Martin Space Systems clean room facility near Denver, spacecraft technician Billy Jones inspects the arm during the assembly phase of the mission.

    Using the robotic arm -- built by the Jet Propulsion Laboratory, Pasadena -- the Phoenix mission will study the history of water and search for complex organic molecules in the ice-rich soil.

    The Phoenix mission is led by Principal Investigator Peter H. Smith of the University of Arizona, Tucson, with project management at NASA's Jet Propulsion Laboratory and development partnership with Lockheed Martin Space Systems. International contributions for Phoenix are provided by the Canadian Space Agency, the University of Neuchatel (Switzerland), the University of Copenhagen, and the Max Planck Institute in Germany. JPL is a division of the California Institute of Technology in Pasadena.

  8. Languages of arms control

    SciTech Connect

    Sherr, A.B.

    1985-11-01

    The author points out that the distinction between a component and subcomponent and a matter of Russian-English translation must be resolved if the Reagan-Gorbachev talks were to progress. The Reagan Administration did not create the problem of what is a component and what is a subcomponent; that was left unresolved in 1972. But the Strategic Defense Initiative Organization approach surely exacerbates it at a most inopportune time for arms control. US protestations that SDI does nothing to undermine the ABM Treaty ring hollow indeed when the professed aim of developing and testing various subcomponents is to arrive at a point of full systems development. If the Soviets were taking this same approach, no US arms control expert, in or out of government, would condone it once the activity had been identified by national technical means as probably ABM-related. The US would place the burden on the Soviets to explain, if they could, why it was not. The scope of the SDI program throws an entirely new factor into the equation. The price for pursuing SDI will be a stalemate in arms control negotiations for an indefinite future, increasing charges of cheating by both sides, and continuation of the chill in US-Soviet relations. Unless this prospect is reversed, good intentions and hopes for peace will be illusory. 7 references.

  9. Armed conflict and child health

    PubMed Central

    Rieder, Michael; Choonara, Imti

    2012-01-01

    Summary Armed conflict has a major impact on child health throughout the world. One in six children worldwide lives in an area of armed conflict and civilians are more likely to die than soldiers as a result of the conflict. In stark contrast to the effect on children, the international arms trade results in huge profits for the large corporations involved in producing arms, weapons and munitions. Armed conflict is not inevitable but is an important health issue that should be prevented. PMID:21393303

  10. bicoid mRNA localises to the Drosophila oocyte anterior by random Dynein-mediated transport and anchoring

    PubMed Central

    Trovisco, Vítor; Belaya, Katsiaryna; Nashchekin, Dmitry; Irion, Uwe; Sirinakis, George; Butler, Richard; Lee, Jack J; Gavis, Elizabeth R; St Johnston, Daniel

    2016-01-01

    bicoid mRNA localises to the Drosophila oocyte anterior from stage 9 of oogenesis onwards to provide a local source for Bicoid protein for embryonic patterning. Live imaging at stage 9 reveals that bicoid mRNA particles undergo rapid Dynein-dependent movements near the oocyte anterior, but with no directional bias. Furthermore, bicoid mRNA localises normally in shot2A2, which abolishes the polarised microtubule organisation. FRAP and photo-conversion experiments demonstrate that the RNA is stably anchored at the anterior, independently of microtubules. Thus, bicoid mRNA is localised by random active transport and anterior anchoring. Super-resolution imaging reveals that bicoid mRNA forms 110–120 nm particles with variable RNA content, but constant size. These particles appear to be well-defined structures that package the RNA for transport and anchoring. DOI: http://dx.doi.org/10.7554/eLife.17537.001 PMID:27791980

  11. Fast track, dynein-dependent nuclear targeting of human immunodeficiency virus Vpr protein; impaired trafficking in a clinical isolate.

    PubMed

    Caly, Leon; Kassouf, Vicki T; Moseley, Gregory W; Diefenbach, Russell J; Cunningham, Anthony L; Jans, David A

    2016-02-12

    Nuclear import of the accessory protein Vpr is central to infection by human immunodeficiency virus (HIV). We previously identified the Vpr F72L mutation in a HIV-infected, long-term non-progressor, showing that it resulted in reduced Vpr nuclear accumulation and altered cytoplasmic localisation. Here we demonstrate for the first time that the effects of nuclear accumulation of the F72L mutation are due to impairment of microtubule-dependent-enhancement of Vpr nuclear import. We use high resolution imaging approaches including fluorescence recovery after photobleaching and other approaches to document interaction between Vpr and the dynein light chain protein, DYNLT1, and impaired interaction of the F72L mutant with DYNLT1. The results implicate MTs/DYNLT1 as drivers of Vpr nuclear import and HIV infection, with important therapeutic implications.

  12. Loss-of-Function GAS8 Mutations Cause Primary Ciliary Dyskinesia and Disrupt the Nexin-Dynein Regulatory Complex

    PubMed Central

    Olbrich, Heike; Cremers, Carolin; Loges, Niki T.; Werner, Claudius; Nielsen, Kim G.; Marthin, June K.; Philipsen, Maria; Wallmeier, Julia; Pennekamp, Petra; Menchen, Tabea; Edelbusch, Christine; Dougherty, Gerard W.; Schwartz, Oliver; Thiele, Holger; Altmüller, Janine; Rommelmann, Frank; Omran, Heymut

    2015-01-01

    Multiciliated epithelial cells protect the upper and lower airways from chronic bacterial infections by moving mucus and debris outward. Congenital disorders of ciliary beating, referred to as primary ciliary dyskinesia (PCD), are characterized by deficient mucociliary clearance and severe, recurrent respiratory infections. Numerous genetic defects, most of which can be detected by transmission electron microscopy (TEM), are so far known to cause different abnormalities of the ciliary axoneme. However, some defects are not regularly discernable by TEM because the ciliary architecture of the axoneme remains preserved. This applies in particular to isolated defects of the nexin links, also known as the nexin-dynein regulatory complex (N-DRC), connecting the peripheral outer microtubular doublets. Immunofluorescence analyses of respiratory cells from PCD-affected individuals detected a N-DRC defect. Genome-wide exome sequence analyses identified recessive loss-of-function mutations in GAS8 encoding DRC4 in three independent PCD-affected families. PMID:26387594

  13. Defects in the ratio of the dynein isoform, DHC11 in the long-flagella mutants of Chlamydomonas reinhardtii.

    PubMed

    Sequeira, Marilyn P; Sinha, Sapna; Motiwalla, Mustafa J; Rao, Venkatramanan G; D'Souza, Jacinta S

    2017-01-22

    The long-flagella mutants (lf1, lf2, lf3 and lf4) of Chlamydomonas reinhardtii are defective in proteins that are required for the assembly of normal flagella, their phenotype being long flagella. In a previous study, we biophysically characterized these mutants for their waveform patterns, swimming speeds, beat frequencies and correlated these parameters with their flagellar lengths. We found an anomaly in this correlation and set out to explore the underlying molecular significance, if any. The diverse inner dynein isoforms are the flagellar motors that convert the chemical energy of ATP into the mechanical energy of motility; we probed the presence of one of these isoforms (DHC11, which might help in bend initiation) in the lf mutants and compared it with the wild-type. Our studies show that the ratio of DHC11 is defective in the long-flagella mutants of Chlamydomonas reinhardtii.

  14. FhCaBP3: a Fasciola hepatica calcium binding protein with EF-hand and dynein light chain domains.

    PubMed

    Banford, Samantha; Drysdale, Orla; Hoey, Elizabeth M; Trudgett, Alan; Timson, David J

    2013-04-01

    A DNA sequence encoding a protein with predicted EF-hand and dynein light chain binding domains was identified in a Fasciola hepatica EST library. Sequence analysis of the encoded protein revealed that the most similar known protein was the Fasciola gigantica protein FgCaBP3 and so this newly identified protein was named FhCaBP3. Molecular modelling of FhCaBP3 predicted a highly flexible N-terminal region, followed by a domain containing two EF-hand motifs the second of which is likely to be a functioning divalent ion binding site. The C-terminal domain of the protein contains a dynein light chain like region. Interestingly, molecular modelling predicts that calcium ion binding to the N-terminal domain destabilises the β-sheet structure of the C-terminal domain. FhCaBP3 can be expressed in, and purified from, Escherichia coli. The recombinant protein dimerises and the absence of calcium ions appeared to promote dimerisation. Native gel shift assays demonstrated that the protein bound to calcium and manganese ions, but not to magnesium, barium, zinc, strontium, nickel, copper or cadmium ions. FhCaBP3 interacted with the calmodulin antagonists trifluoperazine, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide and chlorpromazine as well as the myosin regulatory light chain-binding drug praziquantel. Despite sequence and structural similarities to other members of the same protein family from F. hepatica, FhCaBP3 has different biochemical properties to the other well characterised family members, FH22 and FhCaBP4. This suggests that each member of this trematode calcium-binding family has discrete functional roles within the organism.

  15. Mayer Rokitansky Kuster Hauser (MRKH) syndrome with absent thumbs and big toes.

    PubMed

    Yunus, Mahira

    2014-01-01

    Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome is a rare developmental failure of Müllerian ducts. Principle clinical features of MRKH syndrome are primary amenorrhoea associated with congenital absence of vagina, uterine anomalies, normal ovaries, 46 XX karyotype with normal female secondary sexual characteristics and frequent association with renal, skeletal, and other congenital anomalies. A case of a 3-year-old child with congenitally absent thumbs and big toes is reported herein; she was brought in with complaints of urinary incontinence. Radiological investigation (ultrasound and magnetic resonance imaging (MRI) scan) revealed absent uterus and vagina while both ovaries were normal. Intravenous urography (IVU) study showed bifid pelvicalyceal systems bilaterally. Karyotyping revealed a 46 XX female phenotype. Laparoscopy confirmed normal ovaries bilaterally and small unfused uterine buds lying beside both ovaries on each side of pelvis. Early diagnosis of MRKH syndrome is essential for timely planning of vaginal and (if possible) uterine reconstructive surgeries.

  16. Integrated proteomics identified novel activation of dynein IC2-GR-COX-1 signaling in neurofibromatosis type I (NF1) disease model cells.

    PubMed

    Hirayama, Mio; Kobayashi, Daiki; Mizuguchi, Souhei; Morikawa, Takashi; Nagayama, Megumi; Midorikawa, Uichi; Wilson, Masayo M; Nambu, Akiko N; Yoshizawa, Akiyasu C; Kawano, Shin; Araki, Norie

    2013-05-01

    Neurofibromatosis type 1 (NF1) tumor suppressor gene product, neurofibromin, functions in part as a Ras-GAP, and though its loss is implicated in the neuronal abnormality of NF1 patients, its precise cellular function remains unclear. To study the molecular mechanism of NF1 pathogenesis, we prepared NF1 gene knockdown (KD) PC12 cells, as a NF1 disease model, and analyzed their molecular (gene and protein) expression profiles with a unique integrated proteomics approach, comprising iTRAQ, 2D-DIGE, and DNA microarrays, using an integrated protein and gene expression analysis chart (iPEACH). In NF1-KD PC12 cells showing abnormal neuronal differentiation after NGF treatment, of 3198 molecules quantitatively identified and listed in iPEACH, 97 molecules continuously up- or down-regulated over time were extracted. Pathway and network analysis further revealed overrepresentation of calcium signaling and transcriptional regulation by glucocorticoid receptor (GR) in the up-regulated protein set, whereas nerve system development was overrepresented in the down-regulated protein set. The novel up-regulated network we discovered, "dynein IC2-GR-COX-1 signaling," was then examined in NF1-KD cells. Validation studies confirmed that NF1 knockdown induces altered splicing and phosphorylation patterns of dynein IC2 isomers, up-regulation and accumulation of nuclear GR, and increased COX-1 expression in NGF-treated cells. Moreover, the neurite retraction phenotype observed in NF1-KD cells was significantly recovered by knockdown of the dynein IC2-C isoform and COX-1. In addition, dynein IC2 siRNA significantly inhibited nuclear translocation and accumulation of GR and up-regulation of COX-1 expression. These results suggest that dynein IC2 up-regulates GR nuclear translocation and accumulation, and subsequently causes increased COX-1 expression, in this NF1 disease model. Our integrated proteomics strategy, which combines multiple approaches, demonstrates that NF1-related neural

  17. Integrated Proteomics Identified Novel Activation of Dynein IC2-GR-COX-1 Signaling in Neurofibromatosis Type I (NF1) Disease Model Cells*

    PubMed Central

    Hirayama, Mio; Kobayashi, Daiki; Mizuguchi, Souhei; Morikawa, Takashi; Nagayama, Megumi; Midorikawa, Uichi; Wilson, Masayo M.; Nambu, Akiko N.; Yoshizawa, Akiyasu C.; Kawano, Shin; Araki, Norie

    2013-01-01

    Neurofibromatosis type 1 (NF1) tumor suppressor gene product, neurofibromin, functions in part as a Ras-GAP, and though its loss is implicated in the neuronal abnormality of NF1 patients, its precise cellular function remains unclear. To study the molecular mechanism of NF1 pathogenesis, we prepared NF1 gene knockdown (KD) PC12 cells, as a NF1 disease model, and analyzed their molecular (gene and protein) expression profiles with a unique integrated proteomics approach, comprising iTRAQ, 2D-DIGE, and DNA microarrays, using an integrated protein and gene expression analysis chart (iPEACH). In NF1-KD PC12 cells showing abnormal neuronal differentiation after NGF treatment, of 3198 molecules quantitatively identified and listed in iPEACH, 97 molecules continuously up- or down-regulated over time were extracted. Pathway and network analysis further revealed overrepresentation of calcium signaling and transcriptional regulation by glucocorticoid receptor (GR) in the up-regulated protein set, whereas nerve system development was overrepresented in the down-regulated protein set. The novel up-regulated network we discovered, “dynein IC2-GR-COX-1 signaling,” was then examined in NF1-KD cells. Validation studies confirmed that NF1 knockdown induces altered splicing and phosphorylation patterns of dynein IC2 isomers, up-regulation and accumulation of nuclear GR, and increased COX-1 expression in NGF-treated cells. Moreover, the neurite retraction phenotype observed in NF1-KD cells was significantly recovered by knockdown of the dynein IC2-C isoform and COX-1. In addition, dynein IC2 siRNA significantly inhibited nuclear translocation and accumulation of GR and up-regulation of COX-1 expression. These results suggest that dynein IC2 up-regulates GR nuclear translocation and accumulation, and subsequently causes increased COX-1 expression, in this NF1 disease model. Our integrated proteomics strategy, which combines multiple approaches, demonstrates that NF1-related neural

  18. A surviving infant with sirenomelia (Mermaid syndrome) associated with absent bladder.

    PubMed

    Stanton, Michael P; Penington, Elizabeth C; Hutson, John M

    2003-08-01

    The authors report a case of a surviving infant with sirenomelia (Mermaid syndrome). The child is now 4 years of age. The authors believe that this is only the fourth reported case of an infant with sirenomelia surviving beyond the neonatal period and the first associated with absent bladder. The abnormal distal aorta shown in this case supports the theory that sirenomelia is an extreme form of caudal dysgenesis rather than occurring secondary to vascular steal.

  19. Surgical treatment of tetralogy of Fallot with absent pulmonary valve syndrome.

    PubMed

    Tanaka, Yuki; Miyamoto, Takashi; Naito, Yuji; Yoshitake, Shuichi

    2016-06-01

    The patient was a 3-month-old girl weighting 3.6 kg, diagnosed with tetralogy of Fallot and absent pulmonary valve syndrome. We surgically repaired the tetralogy of Fallot by patch closure of the ventricular septal defect, right ventricular outflow tract reconstruction using an expanded polytetrafluoroethylene monocusp patch with a bulging sinus, and removal of the bronchial obstruction by anterior translocation of the pulmonary artery using the Lecompte maneuver.

  20. Electromyographic investigation of hypnotic arm levitation: differences between voluntary arm elevation and involuntary arm levitation.

    PubMed

    Peter, Burkhard; Schiebler, Philipp; Piesbergen, Christoph; Hagl, Maria

    2012-01-01

    Thirty-three volunteers were randomly exposed to 3 conditions: hypnotic arm levitation, holding up the arm voluntarily without hypnosis, and imagined arm lifting without hypnosis. Trapezius, deltoid, extensor digitorum, flexor digitorum profundus, biceps brachii, and triceps brachii muscles were measured. Strain and muscle activity during lifting and holding up the right arm for 3 minutes were used as dependent variables. During hypnotic arm levitation, the total muscle activity was lower than during holding it up voluntarily (p < .01); the activity in the deltoid was 27% lower (p < .001). Without hypnosis, the muscle activity showed a positive correlation with strain. However, there was no such correlation in the hypnotic condition. Apparently, it is possible to reduce strain and to objectively measure muscle activity in an uplifted arm through hypnotic arm levitation.

  1. The bulk and the tail of minimal absent words in genome sequences

    NASA Astrophysics Data System (ADS)

    Aurell, Erik; Innocenti, Nicolas; Zhou, Hai-Jun

    2016-04-01

    Minimal absent words (MAW) of a genomic sequence are subsequences that are absent themselves but the subwords of which are all present in the sequence. The characteristic distribution of genomic MAWs as a function of their length has been observed to be qualitatively similar for all living organisms, the bulk being rather short, and only relatively few being long. It has been an open issue whether the reason behind this phenomenon is statistical or reflects a biological mechanism, and what biological information is contained in absent words. In this work we demonstrate that the bulk can be described by a probabilistic model of sampling words from random sequences, while the tail of long MAWs is of biological origin. We introduce the concept of a core of a MAW, which are sequences present in the genome and closest to a given MAW. We show that in E. faecalis, E. coli and yeast the cores of the longest MAWs, which exist in two or more copies, are located in highly conserved regions the most prominent example being ribosomal RNAs. We also show that while the distribution of the cores of long MAWs is roughly uniform over these genomes on a coarse-grained level, on a more detailed level it is strongly enhanced in 3’ untranslated regions (UTRs) and, to a lesser extent, also in 5’ UTRs. This indicates that MAWs and associated MAW cores correspond to fine-tuned evolutionary relationships, and suggest that they can be more widely used as markers for genomic complexity.

  2. Gender-based violence and absent fathers: a scoping review protocol

    PubMed Central

    Sikweyiya, Yandisa; Nduna, Mzikazi; Khuzwayo, Nelisiwe; Mthombeni, Andile; Mashamba-Thompson, Tivani Phosa

    2016-01-01

    Introduction Gender-based violence (GBV) and absent fathers are two epidemics that affect women and children in sub-Saharan Africa. However, the understanding of the complex links between GBV and absent fathers is currently inadequate. The aim of the study is to provide an overview of documented evidence that links GBV and absent fathers as well as identifies areas that require systematic review and where more primary research is needed. Methods and analysis The search strategy for this scoping review study will involve electronic databases including: Academic Search Premier, Ingenta, Kluwer Online, PsycARTICLES (EBSCO), PsycINFO (EBSCO), Social Work Abstracts and Sociological Collection. The studies will be mapped in 2 stages: stage 1 will map studies descriptively by focus and method; stage 2 will involve additional inclusion criteria, quality assessment and data extraction undertaken by two reviewers in parallel. A thematic analysis of the studies will be carried out to extract relevant outcomes using NVIVO. Discussion We anticipate finding a large number of studies on GBV diagnostic interventions in sub-Saharan Africa which, once summarised, will be useful to guide future research. The protocol for the scoping review has been registered in PROSPERO. Dissemination The study will be disseminated electronically and in print. It will also be presented to conferences related to GBV, Father Connections and Children's Health. PROSPERO registration number CRD42015022094. PMID:27297007

  3. Cardiac-locked bursts of muscle sympathetic nerve activity are absent in familial dysautonomia

    PubMed Central

    Macefield, Vaughan G; Norcliffe-Kaufmann, Lucy; Axelrod, Felicia B; Kaufmann, Horacio

    2013-01-01

    Familial dysautonomia (Riley–Day syndrome) is an hereditary sensory and autonomic neuropathy (HSAN type III), expressed at birth, that is associated with reduced pain and temperature sensibilities and absent baroreflexes, causing orthostatic hypotension as well as labile blood pressure that increases markedly during emotional excitement. Given the apparent absence of functional baroreceptor afferents, we tested the hypothesis that the normal cardiac-locked bursts of muscle sympathetic nerve activity (MSNA) are absent in patients with familial dysautonomia. Tungsten microelectrodes were inserted percutaneously into muscle or cutaneous fascicles of the common peroneal nerve in 12 patients with familial dysautonomia. Spontaneous bursts of MSNA were absent in all patients, but in five patients we found evidence of tonically firing sympathetic neurones, with no cardiac rhythmicity, that increased their spontaneous discharge during emotional arousal but not during a manoeuvre that unloads the baroreceptors. Conversely, skin sympathetic nerve activity (SSNA), recorded in four patients, appeared normal. We conclude that the loss of phasic bursts of MSNA and the loss of baroreflex modulation of muscle vasoconstrictor drive contributes to the poor control of blood pressure in familial dysautonomia, and that the increase in tonic firing of muscle vasoconstrictor neurones contributes to the increase in blood pressure during emotional excitement. PMID:23165765

  4. Controller arm for a remotely related slave arm

    NASA Technical Reports Server (NTRS)

    Salisbury, J. K., Jr. (Inventor)

    1979-01-01

    A segmented controller arm configured and dimensioned to form a miniature kinematic replica of a remotely related slave arm is disclosed. The arm includes: (1) a plurality of joints for affording segments of the arm simultaneous angular displacement about a plurality of pairs of intersecting axes, (2) a plurality of position sensing devices for providing electrical signals indicative of angular displacement imparted to corresponding segments of the controller shaft about the axes, and (3) a control signal circuit for generating control signals to be transmitted to the slave arm. The arm is characterized by a plurality of yokes, each being supported for angular displacement about a pair of orthogonally related axes and counterbalanced against gravitation by a cantilevered mass.

  5. ARM Data Integrator

    SciTech Connect

    2014-02-06

    The Atmospheric Radiation Measurement (ARM) Data Integrator (ADI) streamlines the development of scientific algorithms and analysis of time-series NetCDF data, and improves the content and consistency of the output data products produced by these algorithms. The framework automates the process of retrieving and preparing data for analysis, and allows users to design output data products through a graphical interface. It also provides a modular, flexible software development architecture that scientists can use to generate C, Python, and IDL source code templates that embed the pre and post processing logic allowing the scientist to focus on only their science. The input data, preprocessing, and output data specifications of algorithms are defined through a graphical interface and stored in a database. ADI implements workflow for data integration and supports user access to data through a library of software modules. Data preprocess capabilities supported include automated retrieval of data from input files, merging the retrieved data into appropriately sized chunks, and transformation of the data onto a common coordinate system grid. Through the graphical interface, users can view the details of both their data products and those in the ARM catalog and allows developers to use existing data product to build new data products. Views of the output data products include an overlay of how the design meets ARM archive’s data standards providing the user with a visual cue indicating where their output violates an archive standard. The ADI libraries access the information provided through the GUI via a Postgres database. The ADI framework and its supporting components can significantly decrease the time and cost of implementing scientific algorithms while improving the ability of scientists to disseminate their results.

  6. Worldwide Report, Arms Control

    DTIC Science & Technology

    2007-11-02

    n r JPRS-TAC-85-057 25 November 1985 Worldwide Report ARMS CONTROL f-—*lf^ S ;.řS », ;r%^V; ,*’ \\i.*? 19980728 ■£*V’:: FBIS FOREIGN BROADCAST...why he had decided to extend a programme launched last year of aid to penetration techniques. He had asked the Atomic Energy Commisariat (CEA) for...ICBM s , i.e. for those systems which constitute the basis of the strategic potential of the USSR. No though restrictions are set for the systems in

  7. Phoenix Robotic Arm Rasp

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This photograph shows the rasp protruding from the back of the scoop on NASA's Phoenix Mars Lander's Robotic Arm engineering model in the Payload Interoperability Testbed at the University of Arizona, Tucson.

    This is the position the rasp will assume when it drills into the Martian soil to acquire an icy soil sample for analysis.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  8. Sliding of microtubules by a team of dynein motors: Understanding the effect of spatial distribution of motor tails and mutual exclusion of motor heads on microtubules

    NASA Astrophysics Data System (ADS)

    Singh, Hanumant Pratap; Takshak, Anjneya; Mall, Utkarsh; Kunwar, Ambarish

    2016-06-01

    Molecular motors are natural nanomachines that use the free energy released from ATP hydrolysis to generate mechanical forces. Cytoplasmic dynein motors often work collectively as a team to drive important processes such as axonal growth, proplatelet formation and mitosis, as forces generated by single motors are insufficient. A large team of dynein motors is used to slide cytoskeletal microtubules with respect to one another during the process of proplatelet formation and axonal growth. These motors attach to a cargo microtubule via their tail domains, undergo the process of detachment and reattachment of their head domains on another track microtubule, while sliding the cargo microtubule along the track. Traditional continuum/mean-field approaches used in the past are not ideal for studying the sliding mechanism of microtubules, as they ignore spatial and temporal fluctuations due to different possible distributions of motor tails on cargo filament, as well as binding/unbinding of motors from their track. Therefore, these models cannot be used to address important questions such as how the distribution of motor tails on microtubules, or how the mutual exclusion of motor heads on microtubule tracks affects the sliding velocity of cargo microtubule. To answer these, here we use a computational stochastic model where we model each dynein motor explicitly. In our model, we use both random as well as uniform distributions of dynein motors on cargo microtubule, as well as mutual exclusion of motors on microtubule tracks. We find that sliding velocities are least affected by the distribution of motor tails on microtubules, whereas they are greatly affected by mutual exclusion of motor heads on microtubule tracks. We also find that sliding velocity depends on the length of cargo microtubule if mutual exclusion among motor heads is considered.

  9. Linking cytoplasmic dynein and transport of Rab8 vesicles to the midbody during cytokinesis by the doublecortin domain-containing 5 protein.

    PubMed

    Kaplan, Anna; Reiner, Orly

    2011-12-01

    Completion of mitosis requires microtubule-dependent transport of membranes to the midbody. Here, we identified a role in cytokinesis for doublecortin domain-containing protein 5 (DCDC5), a member of the doublecortin protein superfamily. DCDC5 is a microtubule-associated protein expressed in both specific and dynamic fashions during mitosis. We show that DCDC5 interacts with cytoplasmic dynein and Rab8 (also known as Ras-related protein Rab-8A), as well as with the Rab8 nucleotide exchange factor Rabin8 (also known as Rab-3A-interacting protein). Following DCDC5 knockdown, the durations of the metaphase to anaphase transition and cytokinesis, and the proportion of multinucleated cells increases, whereas cell viability decreases. Furthermore, knockdown of DCDC5 or addition of a dynein inhibitor impairs the entry of Golgi-complex-derived Rab8-positive vesicles to the midbody. These findings suggest that DCDC5 plays an important role in mediating dynein-dependent transport of Rab8-positive vesicles and in coordinating late cytokinesis.

  10. The dynein inhibitor Ciliobrevin D inhibits the bidirectional transport of organelles along sensory axons and impairs NGF-mediated regulation of growth cones and axon branches.

    PubMed

    Sainath, Rajiv; Gallo, Gianluca

    2015-07-01

    The axonal transport of organelles is critical for the development, maintenance, and survival of neurons, and its dysfunction has been implicated in several neurodegenerative diseases. Retrograde axon transport is mediated by the motor protein dynein. In this study, using embryonic chicken dorsal root ganglion neurons, we investigate the effects of Ciliobrevin D, a pharmacological dynein inhibitor, on the transport of axonal organelles, axon extension, nerve growth factor (NGF)-induced branching and growth cone expansion, and axon thinning in response to actin filament depolymerization. Live imaging of mitochondria, lysosomes, and Golgi-derived vesicles in axons revealed that both the retrograde and anterograde transport of these organelles was inhibited by treatment with Ciliobrevin D. Treatment with Ciliobrevin D reversibly inhibits axon extension and transport, with effects detectable within the first 20 min of treatment. NGF induces growth cone expansion, axonal filopodia formation and branching. Ciliobrevin D prevented NGF-induced formation of axonal filopodia and branching but not growth cone expansion. Finally, we report that the retrograde reorganization of the axonal cytoplasm which occurs on actin filament depolymerization is inhibited by treatment with Ciliobrevin D, indicating a role for microtubule based transport in this process, as well as Ciliobrevin D accelerating Wallerian degeneration. This study identifies Ciliobrevin D as an inhibitor of the bidirectional transport of multiple axonal organelles, indicating this drug may be a valuable tool for both the study of dynein function and a first pass analysis of the role of axonal transport.

  11. Anal atresia, abnormal genitalia, and absent thumb: congenital malformations associated with mosaic ring chromosome 13.

    PubMed

    Ocak, Z; Ozlu, T; Vural, M

    2013-01-01

    Because of the deletion of a segment of the chromosome during the formation of a ring, several clinical findings may be associated with ring chromosomes. Ring chromosome 13 is one of such disorders in which the genotype-phenotype correlation is stronger by virtue of the accumulating literature. It can be associated with multiple congenital abnormalities and severe mental retardation. We report a case with mosaic ring chromosome 13 whose prenatal ultrasound revealed bilateral ventriculomegaly. Anal atresia, unidentifiable external genitalia, and an absent thumb were observed in the postmortem examination.

  12. Lateral facial cleft associated with accessory mandible having teeth, absent parotid gland and peripheral facial weakness.

    PubMed

    Ozçelik, D; Toplu, G; Türkseven, A; Senses, D A; Yiğit, B

    2014-07-01

    Transverse facial cleft is a very rare malformation. The Tessier no. 7 cleft is a lateral facial cleft which emanates from oral cavity and extends towards the tragus, involving both soft tissue and skeletal components. Here, we present a case having transverse facial cleft, accessory mandible having teeth, absent parotid gland and ipsilateral peripheral facial nerve weakness. After surgical repair of the cleft in 2-month of age, improvement of the facial nerve function was detected in 3-year of age. Resection of the accessory mandible was planned in 5-6 years of age.

  13. Profuse congenital familial milia with absent dermatoglyphics (Basan's Syndrome): description of a new family.

    PubMed

    Luna, Paula Carolina; Larralde, Margarita

    2012-01-01

    Milia are common, small, keratin-containing cysts frequently seen in all age groups. They may arise spontaneously or develop after a variety of stimuli. They can be found alone or as part of syndromes. We present a female neonate born not only with profuse facial milia, but also with acral bullae and absent dermatoglyphics. Similar features were seen in several members of her family. These findings correspond to the syndrome known as Basan's syndrome, a rare autosomal-dominant inherited dermatosis characterized by profuse congenital milia, transient neonatal acral bullae, and absence of dermatoglyphics.

  14. [Tetralogy of Fallot with absent pulmonary valve in a newborn and infant. Complete surgical correction].

    PubMed

    Cabrera Duro, A; Rodrigo Carbonero, D; Martínez Corrales, P; Aramendi Gallardo, J; Alcíbar Villa, J; López de Heredia Goya, J; Romero Ibarra, C

    2004-02-01

    We report two patients, a newborn and a 7-month old infant, with tetralogy of Fallot and absent pulmonary valve syndrome. Both had severe obstruction at the level of the ring with aneurysmal pulmonary artery branches, which compressed and displaced the trachea and main bronchial tubes. The neonate required mechanical ventilation from birth. Treatment was aggressive in both patients with interventricular septum defect closure, arterioplasty of the branches and homograft in the infant, and resection of the truncus and pulmonary branches with posterior face suture of both branches associated with a valved conduit in orthotopic position in the neonate. We believe that early treatment avoids airway degeneration and right ventricle volume overload.

  15. Global arms proliferation

    SciTech Connect

    Christiansen, D.

    1991-09-01

    This paper reports that the United States delivered some US $11 billion of military hardware to Iran between 1969 and 1979, in the hopes of helping stabilize a volatile situation in the Middle East. That did not work. When Iran used the weapons against Iraq, the USSR, France, and a number of developing countries helped arm Iraq. It was this vast arsenal that Iraq deployed in its Kuwait-Persian Gulf War venture. Granted, those weapons were augmented by some U.S.-made equipment like TOW antitank missiles and Hawk antiaircraft missiles that were captured in the Iraqi attack on Kuwait. A report issued by the U.S. Office of Technology Assessment (OTA) in June cited that chain of events to demonstrate that the U.S. and other major exporters are gradually losing control of the weapons transferred (to other countries) as well as the technology and industry necessary to produce and support them.

  16. Robotic Arm Biobarrier Cable

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This image, taken by the Surface Stereo Imager on NASA's Phoenix Mars Lander on the 14th Martian day of the mission (June 7, 2008), shows the cable that held the Robotic Arm's biobarrier in place during flight has snapped. The cable's springs retracted to release the biobarrier right after landing.

    To the lower right of the image a spring is visible. Extending from that spring is a length of cable that snapped during the biobarrier's release. A second spring separated from the cable when it snapped and has been photographed on the ground under the lander near one of the legs.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  17. The Neanderthal lower arm.

    PubMed

    De Groote, Isabelle

    2011-10-01

    Neanderthal forearms have been described as being very powerful. Different individual features in the lower arm bones have been described to distinguish Neanderthals from modern humans. In this study, the overall morphology of the radius and ulna is considered, and morphological differences among Neanderthals, Upper Paleolithic Homo sapiens and recent H. sapiens are described. Comparisons among populations were made using a combination of 3D geometric morphometrics and standard multivariate methods. Comparative material included all available complete radii and ulnae from Neanderthals, early H. sapiens and archaeological and recent human populations, representing a wide geographical and lifestyle range. There are few differences among the populations when features are considered individually. Neanderthals and early H. sapiens fell within the range of modern human variation. When the suite of measurements and shapes were analyzed, differences and similarities became apparent. The Neanderthal radius is more laterally curved, has a more medially placed radial tuberosity, a longer radial neck, a more antero-posteriorly ovoid head and a well-developed proximal interosseous crest. The Neanderthal ulna has a more anterior facing trochlear notch, a lower M. brachialis insertion, larger relative mid-shaft size and a more medio-lateral and antero-posterior sinusoidal shaft. The Neanderthal lower arm morphology reflects a strong cold-adapted short forearm. The forearms of H. sapiens are less powerful in pronation and supination. Many differences between Neanderthals and H. sapiens can be explained as a secondary consequence of the hyper-polar body proportions of the Neanderthals, but also as retentions of the primitive condition of other hominoids.

  18. How do octopuses use their arms?

    PubMed

    Mather, J A

    1998-09-01

    A taxonomy of the movement patterns of the 8 flexible arms of octopuses is constructed. Components consist of movements of the arm itself, the ventral suckers and their stalks, as well as the relative position of arms and the skin web between them. Within 1 arm, combinations of components result in a variety of behaviors. At the level of all arms, 1 group of behaviors is described as postures, on the basis of the spread of all arms and the web to make a 2-dimensional surface whose position differs in the 3rd dimension. Another group of arm behaviors is actions, more or less coordinated and involving several to all arms. Arm control appears to be based on radial symmetry, relative equipotentiality of all arms, relative independence of each arm, and separability of components within the arm. The types and coordination of arm behaviors are discussed with relationship to biomechanical limits, muscle structures, and neuronal programming.

  19. Layers of Experience Using "Arms"

    ERIC Educational Resources Information Center

    Brown, Laurinda; Coles, Alf; Ball, Derek; Morton, Pat; Coles, Matt; Ordman, Louise; Orr, Barry; Lam, Tung Ken

    2008-01-01

    This article presents the authors' personal accounts and their experiences in working on mathematics using "arms." "Arms" is an idea that first appeared as a program written by John Warwick and David Wooldridge in an ATM publication "Some Lessons in Mathematics with a Microcomputer," 1983. The introduction to…

  20. Arms control and the MX

    SciTech Connect

    Kroll, J.M.

    1985-01-01

    By 1969, Soviet ballistic missile deployments led the United States to project the vulnerability of Minuteman Intercontinental Ballistic Missile (ICBM) silos along with an imbalance in ICBM capabilities. The Nixon Administration planned two simultaneous responses: strategic arms negotiations, to limit the threat through mutually agreed restraints; and the Safeguard Anti-Ballistic Missile defense program, to defend, as necessary, the threatened ICBM force. The US succeeded in neither. The planned defense did not materialize, even though SALT failed to limit the growth of the Soviet threat. In the years after SALT I, the US planned, but again did not carry through, ICBM programs to enhance ICBM survivability and at the same time to approach essential equivalence with Soviet capabilities. This dissertation examines the relationship of the two US responses and how arms control affected the MX ICBM system. First, the effects of US arms control objectives and optimism on the MX are analyzed from the first MX systems study in 1974, supporting the new Strategic Arms Limitation Talks, to the deployment of MX in current Minuteman silos, supporting the Strategic Arms Reduction Talks. Here US arms control contributed to MX delays and highlighted ICBM capability over ICBM survivability. Second, the effect of specific arms control provisions are addressed topically for each strategic arms agreement. The framework they establish allowed ICBM capabilities to increase, but constrained ICBM survivability.

  1. Beyond Arms-Control Monitoring

    SciTech Connect

    Jeanloz, Raymond; Fung, Inez; Bowyer, Ted W.; Wofsy, Steven

    2013-02-15

    Expanded monitoring of the environment, everywhere and at all times, can advance arms control around the world, enhancing transparency among nations. In particular, improved characterization of the atmosphere now offers powerful opportunities for global monitoring, with multiple societal benefits. It may be useful to think of environmental monitoring as a long-term objective of arms-control verification.

  2. LISA Long-Arm Interferometry

    NASA Technical Reports Server (NTRS)

    Thorpe, James I.

    2009-01-01

    An overview of LISA Long-Arm Interferometry is presented. The contents include: 1) LISA Interferometry; 2) Constellation Design; 3) Telescope Design; 4) Constellation Acquisition; 5) Mechanisms; 6) Optical Bench Design; 7) Phase Measurement Subsystem; 8) Phasemeter Demonstration; 9) Time Delay Interferometry; 10) TDI Limitations; 11) Active Frequency Stabilization; 12) Spacecraft Level Stabilization; 13) Arm-Locking; and 14) Embarassment of Riches.

  3. Group velocity mismatch-absent nonlinear frequency conversions for mid-infrared femtosecond pulses generation

    PubMed Central

    Zhong, Haizhe; Zhang, Lifu; Li, Ying; Fan, Dianyuan

    2015-01-01

    A novel group velocity mismatch (GVM) absent scheme for nonlinear optical parametric procedure in mid-infrared was developed with type-I quasi phase matching by use of an off-digital nonlinear optical coefficient d31. This was achieved by matching of the group velocities of the pump and the signal waves, while the phase velocities were quasi phase matched. The system employs MgO-doped periodically poled LiNbO3 as the nonlinear medium. Desired group-velocity dispersion would be obtained via appropriately temperature regulation. To demonstrate its potential applications in ultrafast mid-infrared pulses generation, aiming at a typical mid-infrared wavelength of ~3.2 μm, design examples of two basic nonlinear frequency conversion procedures are studied for both the narrow-band seeding mid-IR optical parametric amplification (OPA) and the synchronously pumped femtosecond optical parametric oscillation (SPOPO). Compared with the conventional scheme of type-0 QPM, the quantum-efficiency can be more than doubled with nearly unlimited bandwidth. The proposed GVM- absent phase matching design may provide a promising route to efficient and broadband sub-100 fs mid-infrared ultrafast pulses generation without group-velocity walk-off. PMID:26099837

  4. Distractor Dwelling, Skipping, and Revisiting Determine Target Absent Performance in Difficult Visual Search

    PubMed Central

    Horstmann, Gernot; Herwig, Arvid; Becker, Stefanie I.

    2016-01-01

    Some targets in visual search are more difficult to find than others. In particular, a target that is similar to the distractors is more difficult to find than a target that is dissimilar to the distractors. Efficiency differences between easy and difficult searches are manifest not only in target-present trials but also in target-absent trials. In fact, even physically identical displays are searched through with different efficiency depending on the searched-for target. Here, we monitored eye movements in search for a target similar to the distractors (difficult search) versus a target dissimilar to the distractors (easy search). We aimed to examine three hypotheses concerning the causes of differential search efficiencies in target-absent trials: (a) distractor dwelling (b) distractor skipping, and (c) distractor revisiting. Reaction times increased with target similarity which is consistent with existing theories and replicates earlier results. Eye movement data indicated guidance in target trials, even though search was very slow. Dwelling, skipping, and revisiting contributed to low search efficiency in difficult search, with dwelling being the strongest factor. It is argued that differences in dwell time account for a large amount of total search time differences. PMID:27574510

  5. Distractor Dwelling, Skipping, and Revisiting Determine Target Absent Performance in Difficult Visual Search.

    PubMed

    Horstmann, Gernot; Herwig, Arvid; Becker, Stefanie I

    2016-01-01

    Some targets in visual search are more difficult to find than others. In particular, a target that is similar to the distractors is more difficult to find than a target that is dissimilar to the distractors. Efficiency differences between easy and difficult searches are manifest not only in target-present trials but also in target-absent trials. In fact, even physically identical displays are searched through with different efficiency depending on the searched-for target. Here, we monitored eye movements in search for a target similar to the distractors (difficult search) versus a target dissimilar to the distractors (easy search). We aimed to examine three hypotheses concerning the causes of differential search efficiencies in target-absent trials: (a) distractor dwelling (b) distractor skipping, and (c) distractor revisiting. Reaction times increased with target similarity which is consistent with existing theories and replicates earlier results. Eye movement data indicated guidance in target trials, even though search was very slow. Dwelling, skipping, and revisiting contributed to low search efficiency in difficult search, with dwelling being the strongest factor. It is argued that differences in dwell time account for a large amount of total search time differences.

  6. Unrepaired Tetralogy of Fallot with Absent Pulmonary Valve in a Mildly Symptomatic 16-Year-Old Boy

    PubMed Central

    Drogalis-Kim, Diana E.; Reemtsen, Brian L.

    2016-01-01

    Absent pulmonary valve is a rare and severe variant seen in only 3% to 6% of patients with tetralogy of Fallot. Fetuses with this combined condition who survive through birth typically need intervention in infancy or early childhood because of respiratory distress, heart failure, or failure to thrive. We describe the unusual case of a mildly symptomatic 16-year-old boy with these conditions who underwent successful primary repair. Our search of the medical literature yielded fewer than 5 cases of tetralogy of Fallot with absent pulmonary valve (or variants with an absent left pulmonary artery) and survival without repair into later adolescence or adulthood. PMID:28100972

  7. Axonemal dynein intermediate-chain gene (DNAI1) mutations result in situs inversus and primary ciliary dyskinesia (Kartagener syndrome).

    PubMed

    Guichard, C; Harricane, M C; Lafitte, J J; Godard, P; Zaegel, M; Tack, V; Lalau, G; Bouvagnet, P

    2001-04-01

    Kartagener syndrome (KS) is a trilogy of symptoms (nasal polyps, bronchiectasis, and situs inversus totalis) that is associated with ultrastructural anomalies of cilia of epithelial cells covering the upper and lower respiratory tracts and spermatozoa flagellae. The axonemal dynein intermediate-chain gene 1 (DNAI1), which has been demonstrated to be responsible for a case of primary ciliary dyskinesia (PCD) without situs inversus, was screened for mutation in a series of 34 patients with KS. We identified compound heterozygous DNAI1 gene defects in three independent patients and in two of their siblings who presented with PCD and situs solitus (i.e., normal position of inner organs). Strikingly, these five patients share one mutant allele (splice defect), which is identical to one of the mutant DNAI1 alleles found in the patient with PCD, reported elsewhere. Finally, this study demonstrates a link between ciliary function and situs determination, since compound mutation heterozygosity in DNAI1 results in PCD with situs solitus or situs inversus (KS).

  8. Computerized axial tomography of the chest for visualization of ''absent'' pulmonary arteries

    SciTech Connect

    Sondheimer, H.M.; Oliphant, M.; Schneider, B.; Kavey, R.E.W.; Blackman, M.S.; Parker, F.B. Jr.

    1982-05-01

    To expand the search for central pulmonary arteries in six patients with absence of cardiac-pulmonary continuity, computerized axial tomography (CAT) of the chest was performed. The CAT scans were compared with previous arteriograms and pulmonary vein wedge angiograms. Three patients with type IV truncus arteriosus were studied, and none had a central, right or left pulmonary artery on CAT scan. However, two patients with tetralogy of Fallot with pulmonary atresia and a patent ductus arteriosus to the right lung demonstrated the presence of a left pulmonary artery. In addition, one child with truncus arteriosus with ''absent'' left pulmonary artery demonstrated a left pulmonary artery on the CAT scan. The CAT scan may therefore enhance our ability to search for disconnected pulmonary arteries in children with complex cyanotic congenital heart disease.

  9. Absent or reversed end diastolic flow velocity in the umbilical artery and necrotising enterocolitis.

    PubMed Central

    Malcolm, G; Ellwood, D; Devonald, K; Beilby, R; Henderson-Smart, D

    1991-01-01

    Absent or reversed end diastolic flow (AREDF) velocities in the umbilical artery were identified in 25 high risk pregnancies. In six pregnancies the fetus was abnormal and all but one of these ended in perinatal death. Of the 19 morphologically normal fetuses, three died in utero and there were four neonatal or infant deaths. The mortality rate was 48% for all pregnancies and 37% for those with morphologically normal fetuses. There was a highly significant increased risk for the development of necrotising enterocolitis in these morphologically normal fetuses with AREDF (53%) compared with controls (6%) who did have umbilical artery end diastolic flow velocities in fetal life. There were no significant differences between the matched pairs for parameters of neonatal outcome chosen to reflect neonatal morbidity. These findings demonstrate the close association between AREDF and necrotising enterocolitis that appears to be independent of other variables such as degree of growth retardation, prematurity, and perinatal asphyxia. PMID:1863128

  10. Ejaculatory ducts opening into accessory urethral channel with hypospadias and absent verumontanum: a rare association.

    PubMed

    Ravi Kumar, Valkodai Ramanthan; Duraisami, Vijayagiri

    2013-12-01

    Ejaculatory ducts draining into accessory urethral channel opening into perineum is rare. This is a case report of a 27-year-old male who had hypospadias surgery at 3 years of age, presenting with discharge of semen through the perineal opening from adolescence. Cystoscopy and dye study showed that it was a short channel communicating with both ejaculatory ducts. Cystoscopy of the native urethra revealed that the vermontanum had not developed. The mucous lined accessory urethra was anastomosed to the bulbar urethra. Urethrogram done after one year showed that the accessory urethra was draining well into the bulbar urethra. Such type of accessory urethral channel communicating with ejaculatory ducts and associated with hypospadias and absent vermontanum has not been reported so far.

  11. Delayed emergence from anesthesia associated with absent brainstem reflexes following suboccipital craniotomy.

    PubMed

    Munis, James R; Marcukaitis, Anthony W; Sprung, Juraj

    2006-01-01

    One of the most feared complications after intracranial surgery is development of acute intracranial pathology, which may result in hypoperfusion and brain injury. Thus, early neurological assessment, performed in the operating room immediately after emergence from anesthesia, is a practice that may contribute to timely diagnosis of neurosurgical complications. Failure to awake after general anesthesia precludes conductance of neurological assessment. We report a patient who failed to emerge from anesthesia after suboccipital craniotomy and had absent brain-stem reflexes with fixed and dilated pupils consistent with severe brain injury. Approximately 60 minutes after termination of surgery, the patient suddenly woke up. After the fact, we discovered that the neurosurgeon performed a generous field block with bupivacaine along the neck incision line. We presume that our patient's failure to awaken was caused by paralysis of brain-stem caused by migration of bupivacaine from the site of the injection.

  12. ARM Lead Mentor Selection Process

    SciTech Connect

    Sisterson, DL

    2013-03-13

    The ARM Climate Research Facility currently operates more than 300 instrument systems that provide ground-based observations of the atmospheric column. To keep ARM at the forefront of climate observations, the ARM infrastructure depends heavily on instrument scientists and engineers, also known as Instrument Mentors. Instrument Mentors must have an excellent understanding of in situ and remote-sensing instrumentation theory and operation and have comprehensive knowledge of critical scale-dependent atmospheric processes. They also possess the technical and analytical skills to develop new data retrievals that provide innovative approaches for creating research-quality data sets.

  13. Absent movement-related cortical potentials in children with primary motor stereotypies.

    PubMed

    Houdayer, Elise; Walthall, Jessica; Belluscio, Beth A; Vorbach, Sherry; Singer, Harvey S; Hallett, Mark

    2014-08-01

    The underlying pathophysiologic mechanism for complex motor stereotypies in children is unknown, with hypotheses ranging from an arousal to a motor control disorder. Movement-related cortical potentials (MRCPs), representing the activation of cerebral areas involved in the generation of movements, precede and accompany self-initiated voluntary movements. The goal of this study was to compare cerebral activity associated with stereotypies to that seen with voluntary movements in children with primary complex motor stereotypies. Electroencephalographic (EEG) activity synchronized with video recording was recorded in 10 children diagnosed with primary motor stereotypies and 7 controls. EEG activity related to stereotypies and self-paced arm movements were analyzed for presence or absence of early or late MRCP, a steep negativity beginning about 1 second before the onset of a voluntary movement. Early MRCPs preceded self-paced arm movements in 8 of 10 children with motor stereotypies and in 6 of 7 controls. Observed MRCPs did not differ between groups. No MRCP was identified before the appearance of a complex motor stereotypy. Unlike voluntary movements, stereotypies are not preceded by MRCPs. This indicates that premotor areas are likely not involved in the preparation of these complex movements and suggests that stereotypies are initiated by mechanisms different from voluntary movements. Further studies are required to determine the site of the motor control abnormality within cortico-striatal-thalamo-cortical pathways and to identify whether similar findings would be found in children with secondary stereotypies.

  14. Absent movement-related cortical potentials in children with primary motor stereotypies

    PubMed Central

    Houdayer, Elise; Walthall, Jessica; Belluscio, Beth A.; Vorbach, Sherry; Singer, Harvey S.; Hallett, Mark

    2013-01-01

    Background The underlying pathophysiologic mechanism for complex motor stereotypies in children is unknown with hypotheses ranging from an arousal to a motor control disorder. Movement-related cortical potentials (MRCPs), representing the activation of cerebral areas involved in the generation of movements, precede and accompany self-initiated voluntary movements. The goal of this study was to compare cerebral activity associated with stereotypies to that seen with voluntary movements in children with primary complex motor stereotypies. Methods Electroencephalographic (EEG) activity synchronized with video recording was recorded in 10 children diagnosed with primary motor stereotypies and 7 controls. EEG activity related to stereotypies and self-paced arm movements were analyzed for presence or absence of early or late MRCP, a steep negativity beginning about one second before the onset of a voluntary movement. Results Early MRCPs preceded self-paced arm movements in 8 out of 10 children with motor stereotypies and in 6 out of 7 controls. Observed MRCPs did not differ between groups. No MRCP was identified before the appearance of a complex motor stereotypy. Conclusions Unlike voluntary movements, stereotypies are not preceded by MRCPs. This indicates that premotor areas are likely not involved in the preparation of these complex movements and suggests that stereotypies are initiated by mechanisms different from voluntary movements. Further studies are required to determine the site of the motor control abnormality within cortico-striatal-thalamo-cortical pathways and to identify whether similar findings would be found in children with secondary stereotypies. PMID:24259275

  15. Exoskeletal technology. [teleoperator arm system

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C.

    1974-01-01

    Possible applications are considered of a master-sleeve teleoperator arm system, developed in exoskeletal space suit technology, as therapeutic aid, orthotic device, or for therapy on patients with neurological disorders.

  16. Arm transplantation: prospects and visions.

    PubMed

    Jones, N F; Schneeberger, S

    2009-03-01

    Based on the results of above-elbow replantation, it is possible that above-elbow arm transplantation will be successful and result in a superior functional outcome as defined by the Chen criteria. Above-elbow arm transplantation is probably technically simpler than distal forearm or wrist transplantation, especially since the macroanastomoses do not require microsurgical expertise. However, hand function depends on reinnervation of forearm muscles and the distance for nerves to regenerate for reinnervation of intrinsic muscles of the hand is significant. The vascularized bone marrow transplanted with the arm holds potential to induce chimerism and promote tolerance but could also make the recipient more susceptible to graft-versus-host disease. Prospective trials comparing the functional results after above-elbow arm transplantation with the functional results achieved by the best neuronal-controlled above-elbow prosthesis are warranted and will determine the gold standard of upper-extremity reconstruction.

  17. ARM Standards Policy Committee Report

    SciTech Connect

    Cialella, A; Jensen, M; Koontz, A; McFarlane, S; McCoy, R; Monroe, J; Palanisamy, G; Perez, R; Sivaraman, C

    2012-09-19

    Data and metadata standards promote the consistent recording of information and are necessary to ensure the stability and high quality of Atmospheric Radiation Measurement (ARM) Climate Research Facility data products for scientific users. Standards also enable automated routines to be developed to examine data, which leads to more efficient operations and assessment of data quality. Although ARM Infrastructure agrees on the utility of data and metadata standards, there is significant confusion over the existing standards and the process for allowing the release of new data products with exceptions to the standards. The ARM Standards Policy Committee was initiated in March 2012 to develop a set of policies and best practices for ARM data and metadata standards.

  18. Unequal-Arms Michelson Interferometers

    NASA Technical Reports Server (NTRS)

    Tinto, Massimo; Armstrong, J. W.

    2000-01-01

    Michelson interferometers allow phase measurements many orders of magnitude below the phase stability of the laser light injected into their two almost equal-length arms. If, however, the two arms are unequal, the laser fluctuations can not be removed by simply recombining the two beams. This is because the laser jitters experience different time delays in the two arms, and therefore can not cancel at the photo detector. We present here a method for achieving exact laser noise cancellation, even in an unequal-arm interferometer. The method presented in this paper requires a separate readout of the relative phase in each arm, made by interfering the returning beam in each arm with a fraction of the outgoing beam. By linearly combining the two data sets with themselves, after they have been properly time shifted, we show that it is possible to construct a new data set that is free of laser fluctuations. An application of this technique to future planned space-based laser interferometer detector3 of gravitational radiation is discussed.

  19. Unequal-Arms Michelson Interferometers

    NASA Technical Reports Server (NTRS)

    Tinto, Massimo; Armstrong, J. W.

    1999-01-01

    Michelson interferometers allow phase measurements many orders of magnitude below the phase stability of the laser light injected into their two almost equal-length arms. If, however, the two arms are unequal, the laser fluctuations can not be removed by simply recombining the two beams. This is because the laser jitters experience different time delays in the two arms, and therefore can not cancel at the photo detector. We present here a method for achieving exact laser noise cancellation, even in an unequal-arm interferometer. The method presented in this paper requires a separate readout of the relative phase in each arm, made by interfering the returning beam in each arm with a fraction of the outgoing beam. By linearly combining the two data sets with themselves, after they have been properly time-shifted, we show that it is possible to construct a new data set that is free of laser fluctuations. An application of this technique to future planned space-based laser interferometer detectors of gravitational radiation is discussed.

  20. Naval arms control: The opposition

    SciTech Connect

    Blaker, J.R.

    1990-02-01

    The author observes that hope that naval arms control agreements might bolster Soviet mellowing and inhibit a return to confrontation must be balanced against the likelihood that whether or not the United States negotiates on naval arms control has little real effect on what happens in the Soviet Union and against the undesirability of being pinned down to a less advantageous military position if things go sour. The hope that U.S. willingness to formally limit and reduce American naval capabilities and options would compel the Soviets to reduce even further their potent land-based power on the Eurasian continent or their strategic nuclear power has to be balanced against the possibility that Soviet willingness to make such reductions is driven by factors that have very little to do with the naval relationship between the two nations. Ultimately, then, we are driven back to the dilemma faced by the professional military regarding naval arms control. Without compelling evidence that naval arms control proposals are beneficial in themselves, the author notes we need a clear exposition of how they fit with other negotiations to improve national security and a much better understanding of the role naval arms control negotiations should play in a comprehensive national arms control strategy.

  1. Silent dropouts in health surveys: are nonrespondent absent teenagers different from those who participate in school-based health surveys?

    PubMed

    Michaud, P A; Delbos-Piot, I; Narring, F

    1998-04-01

    3324 in-school students aged 15-20 years randomly selected from high schools and professional centers in francophone Switzerland answered a self-administered questionnaire about their health problems, needs, and behavior. Their responses were compared with those of 96 absent students sampled via telephone on a shorter, but similar questionnaire. Relative to the absent students, a significantly higher percentage of in-school students reported skin problems, weight concerns, sleep problems, headaches, stomach aches, and vision or dental problems. The percentages of students reporting a need for help were also higher among present students than among those who were absent: nutrition, 21.8 vs. 9.4; stress, 44.2 vs. 31.3; depression, 28.4 vs. 18.9; sleep problems, 21.3 vs. 12.1; sports, 9.2 vs. 4.2; and love life, 31.5 vs. 14.5. The rates of hospitalization and injuries were lower among absent students, 28.2 vs. 40.1. A higher proportion of absent students were sexually active and they also had a tendency to use tobacco, alcohol, and cannabis more often than did present students. Absent students also more frequently partook of leisure and group activities. Study findings suggest that within the Swiss context, school absenteeism is probably related less to physical or chronic health problems than to hedonistic lifestyles which predispose some students skip part of the school hours.

  2. 49 CFR 234.223 - Gate arm.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Gate arm. 234.223 Section 234.223 Transportation... Maintenance Standards § 234.223 Gate arm. Each gate arm, when in the downward position, shall extend across... clearly viewed by approaching highway users. Each gate arm shall start its downward motion not less...

  3. 49 CFR 234.223 - Gate arm.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Gate arm. 234.223 Section 234.223 Transportation... SYSTEMS Maintenance, Inspection, and Testing Maintenance Standards § 234.223 Gate arm. Each gate arm, when... maintained in a condition sufficient to be clearly viewed by approaching highway users. Each gate arm...

  4. 49 CFR 234.223 - Gate arm.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Gate arm. 234.223 Section 234.223 Transportation... SYSTEMS Maintenance, Inspection, and Testing Maintenance Standards § 234.223 Gate arm. Each gate arm, when... maintained in a condition sufficient to be clearly viewed by approaching highway users. Each gate arm...

  5. 49 CFR 234.223 - Gate arm.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Gate arm. 234.223 Section 234.223 Transportation... Maintenance Standards § 234.223 Gate arm. Each gate arm, when in the downward position, shall extend across... clearly viewed by approaching highway users. Each gate arm shall start its downward motion not less...

  6. 49 CFR 234.223 - Gate arm.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Gate arm. 234.223 Section 234.223 Transportation... SYSTEMS Maintenance, Inspection, and Testing Maintenance Standards § 234.223 Gate arm. Each gate arm, when... maintained in a condition sufficient to be clearly viewed by approaching highway users. Each gate arm...

  7. Algorithms for Unequal-Arm Michelson Interferometers

    NASA Technical Reports Server (NTRS)

    Giampieri, Giacomo; Hellings, Ronald W.; Tinto, Massimo; Bender, Peter L.; Faller, James E.

    1994-01-01

    A method of data acquisition and data analysis is described in which the performance of Michelson-type interferometers with unequal arms can be made nearly the same as interferometers with equal arms. The method requires a separate readout of the relative phase in each arm, made by interfering the returning beam in each arm with a fraction of the outgoing beam.

  8. 22 CFR 130.3 - Armed forces.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Armed forces. 130.3 Section 130.3 Foreign Relations DEPARTMENT OF STATE INTERNATIONAL TRAFFIC IN ARMS REGULATIONS POLITICAL CONTRIBUTIONS, FEES AND COMMISSIONS § 130.3 Armed forces. Armed forces means the army, navy, marine, air force, or coast guard,...

  9. 22 CFR 130.3 - Armed forces.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Armed forces. 130.3 Section 130.3 Foreign Relations DEPARTMENT OF STATE INTERNATIONAL TRAFFIC IN ARMS REGULATIONS POLITICAL CONTRIBUTIONS, FEES AND COMMISSIONS § 130.3 Armed forces. Armed forces means the army, navy, marine, air force, or coast guard,...

  10. 22 CFR 130.3 - Armed forces.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Armed forces. 130.3 Section 130.3 Foreign Relations DEPARTMENT OF STATE INTERNATIONAL TRAFFIC IN ARMS REGULATIONS POLITICAL CONTRIBUTIONS, FEES AND COMMISSIONS § 130.3 Armed forces. Armed forces means the army, navy, marine, air force, or coast guard,...

  11. 22 CFR 130.3 - Armed forces.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Armed forces. 130.3 Section 130.3 Foreign Relations DEPARTMENT OF STATE INTERNATIONAL TRAFFIC IN ARMS REGULATIONS POLITICAL CONTRIBUTIONS, FEES AND COMMISSIONS § 130.3 Armed forces. Armed forces means the army, navy, marine, air force, or coast guard,...

  12. 22 CFR 130.3 - Armed forces.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Armed forces. 130.3 Section 130.3 Foreign Relations DEPARTMENT OF STATE INTERNATIONAL TRAFFIC IN ARMS REGULATIONS POLITICAL CONTRIBUTIONS, FEES AND COMMISSIONS § 130.3 Armed forces. Armed forces means the army, navy, marine, air force, or coast guard,...

  13. Atmospheric Radiation Measurement (ARM) Data from the ARM Aerial Facility

    DOE Data Explorer

    The Atmospheric Radiation Measurement (ARM) Program is the largest global change research program supported by the U.S. Department of Energy. The primary goal of the ARM Program is to improve the treatment of cloud and radiation physics in global climate models in order to improve the climate simulation capabilities of these models. ARM data is collected both through permanent monitoring stations and field campaigns around the world. Airborne measurements required to answer science questions from researchers or to validate ground data are also collected. To find data from all categories of aerial operations, follow the links from the AAF information page at http://www.arm.gov/sites/aaf. Tables of information will provide start dates, duration, lead scientist, and the research site for each of the named campaigns. The title of a campaign leads, in turn, to a project description, contact information, and links to the data. Users will be requested to create a password, but the data files are free for viewing and downloading. The ARM Archive physically resides at the Oak Ridge National Laboratory.

  14. LC8 dynein light chain (DYNLL1) binds to the C-terminal domain of ATM-interacting protein (ATMIN/ASCIZ) and regulates its subcellular localization

    SciTech Connect

    Rapali, Peter; Garcia-Mayoral, Maria Flor; Martinez-Moreno, Monica; Tarnok, Krisztian; Schlett, Katalin; Albar, Juan Pablo; Bruix, Marta; Nyitray, Laszlo; Rodriguez-Crespo, Ignacio

    2011-10-28

    Highlights: Black-Right-Pointing-Pointer We have screened a human library with dynein light chain DYNLL1 (DLC8) as bait. Black-Right-Pointing-Pointer Dynein light chain DYNLL1 binds to ATM-kinase interacting protein (ATMIN). Black-Right-Pointing-Pointer ATMIN has 17 SQ/TQ motifs, a motif frequently found in DYNLL1-binding partners. Black-Right-Pointing-Pointer The two proteins interact in vitro, with ATMIN displaying at least five binding sites. Black-Right-Pointing-Pointer The interaction of ATMIN and DYNNL1 in transfected cells can also be observed. -- Abstract: LC8 dynein light chain (now termed DYNLL1 and DYNLL2 in mammals), a dimeric 89 amino acid protein, is a component of the dynein multi-protein complex. However a substantial amount of DYNLL1 is not associated to microtubules and it can thus interact with dozens of cellular and viral proteins that display well-defined, short linear motifs. Using DYNLL1 as bait in a yeast two-hybrid screen of a human heart library we identified ATMIN, an ATM kinase-interacting protein, as a DYNLL1-binding partner. Interestingly, ATMIN displays at least 18 SQ/TQ motifs in its sequence and DYNLL1 is known to bind to proteins with KXTQT motifs. Using pepscan and yeast two-hybrid techniques we show that DYNLL1 binds to multiple SQ/TQ motifs present in the carboxy-terminal domain of ATMIN. Recombinant expression and purification of the DYNLL1-binding region of ATMIN allowed us to obtain a polypeptide with an apparent molecular mass in gel filtration close to 400 kDa that could bind to DYNLL1 in vitro. The NMR data-driven modelled complexes of DYNLL1 with two selected ATMIN peptides revealed a similar mode of binding to that observed between DYNLL1 and other peptide targets. Remarkably, co-expression of mCherry-DYNLL1 and GFP-ATMIN mutually affected intracellular protein localization. In GFP-ATMIN expressing-cells DNA damage induced efficiently nuclear foci formation, which was partly impeded by the presence of mCherry-DYNLL1

  15. Molecular genetic analysis of Drosophila eyes absent mutants reveals an eye enhancer element.

    PubMed Central

    Zimmerman, J E; Bui, Q T; Liu, H; Bonini, N M

    2000-01-01

    The eyes absent (eya) gene is critical for normal eye development in Drosophila and is highly conserved to vertebrates. To define regions of the gene critical for eye function, we have defined the mutations in the four viable eya alleles. Two of these mutations are eye specific and undergo transvection with other mutations in the gene. These were found to be deletion mutations that remove regulatory sequence critical for eye cell expression of the gene. Two other viable alleles cause a reduced eye phenotype and affect the function of the gene in additional tissues, such as the ocelli. These mutations were found to be insertion mutations of different transposable elements within the 5' UTR of the transcript. Detailed analysis of one of these revealed that the transposable element has become subject to regulation by eye enhancer sequences of the eya gene, disrupting normal expression of EYA in the eye. More extended analysis of the deletion region in the eye-specific alleles indicated that the deleted region defines an enhancer that activates gene expression in eye progenitor cells. This enhancer is responsive to ectopic expression of the eyeless gene. This analysis has defined a critical regulatory region required for proper eye expression of the eya gene. PMID:10628984

  16. Molecular analysis of Drosophila eyes absent mutants reveals features of the conserved Eya domain.

    PubMed Central

    Bui, Q T; Zimmerman, J E; Liu, H; Bonini, N M

    2000-01-01

    The eyes absent (eya) gene is critical to eye formation in Drosophila; upon loss of eya function, eye progenitor cells die by programmed cell death. Moreover, ectopic eya expression directs eye formation, and eya functionally synergizes in vivo and physically interacts in vitro with two other genes of eye development, sine oculis and dachshund. The Eya protein sequence, while highly conserved to vertebrates, is novel. To define amino acids critical to the function of the Eya protein, we have sequenced eya alleles. These mutations have revealed that loss of the entire Eya Domain is null for eya activity, but that alleles with truncations within the Eya Domain display partial function. We then extended the molecular genetic analysis to interactions within the Eya Domain. This analysis has revealed regions of special importance to interaction with Sine Oculis or Dachshund. Select eya missense mutations within the Eya Domain diminished the interactions with Sine Oculis or Dachshund. Taken together, these data suggest that the conserved Eya Domain is critical for eya activity and may have functional subregions within it. PMID:10835393

  17. Identification of Transcriptional Targets of the Dual Function Transcription Factor/Phosphatase Eyes Absent

    PubMed Central

    Jemc, Jennifer; Rebay, Ilaria

    2007-01-01

    Drosophila eye specification and development relies on a collection of transcription factors termed the retinal determination gene network (RDGN). Two members of this network, Eyes absent (EYA) and Sine oculis (SO), form a transcriptional complex in which EYA provides the transactivation function while SO provides the DNA binding activity. EYA also functions as a protein tyrosine phosphatase, raising the question of whether transcriptional output is dependent or independent of phosphatase activity. To explore this, we used microarrays together with binding site analysis, quantitative real-time PCR, chromatin immunoprecipitation, genetics and in vivo expression analysis to identify new EYA-SO targets. In parallel, we examined the expression profiles of tissue expressing phosphatase mutant eya and found that reducing phosphatase activity did not globally impair transcriptional output. Among the targets identified by our analysis was the cell cycle regulatory gene, string (stg), suggesting that EYA and SO may influence cell proliferation through transcriptional regulation of stg. Future investigation into the regulation of stg and other EYA-SO targets identified in this study will help elucidate the transcriptional circuitries whereby output from the RDGN integrates with other signaling inputs to coordinate retinal development. PMID:17714699

  18. Terminal hemimelia of the lower extremity: absent lateral ray and a normal fibula

    PubMed Central

    Kim, Jae Kwang; Chung, Moon Sang; Lee, Sang Ki

    2007-01-01

    Congenital lateral ray deficiency is considered to be a manifestation of fibular hemimelia. However, we have noted patients with absent lateral ray but stable knee and ankle joints, and named this condition terminal hemimelia of the lower extremity. This study was undertaken to further define this group of patients and to compare these patients with fibular hemimelia patients. Four boys and one girl of mean age six years two months were in the terminal hemimelic group and four boys and three girls of mean age eight years seven months in the fibular hemimelic group at the final evaluation. Clinical features commonly observed in the fibular hemimelia such as knee valgus, knee instability, tibial bowing, ball and socket ankle, ankle instability, tarsal coalition, leg length inequality were compared between both groups. Terminal hemimelia of the lower extremity was the same as fibular hemimelia in clinical features below the ankle joint. However, terminal hemimela was found to be milder than fibular hemimelia in terms of limb shortening. The clinical features above the ankle joint were different between both groups. Knees and ankles were stable, and gait disturbance were rarely noticed in patients with terminal hemimelia of the lower extremity. PMID:17558505

  19. Effect of absent end diastolic flow velocity in the fetal umbilical artery on subsequent outcome

    PubMed Central

    Adiotomre, P.; Johnstone, F.; Laing, I.

    1997-01-01

    Sixty babies, delivered over a six and a half year period, who had absent end diastolic frequency (AEDF) in the umbilical artery, were studied. Individually matched control pregnancies for gestational age, birthweight, maternal clinical condition and date of delivery, in whom umbilical artery recordings showed end diastolic frequency, were also studied.
  Matching was achieved in 36 cases. Neonates from case pregnancies showed no increase in necrotising enterocolitis, intraventricular haemorrhage, pneumo-thorax, neonatal death or bronchopulmonary dysplasia. However, they were significantly less likely to require ventilation for respiratory distress syndrome (P=0.02).
  Although AEDF indicates a fetus under vascular stress, this finding alone will include a spectrum of response in the baby, from the well compensated to the irreversibly damaged. Delivery at different points in the deteriorating fetal environment may explain discrepant study results. This intrauterine stress, by increasing fetal corticosteroid and thyroid hormones, may account for enhanced lung maturity. Predictions of neonatal course need to be based on more comprehensive awareness of fetal status.

 Keywords: high risk pregnancies; end diastolic flow velocity; ventilation; respiratory distress syndrome. PMID:9059184

  20. Axillary Meristem Formation in Rice Requires the WUSCHEL Ortholog TILLERS ABSENT1[OPEN

    PubMed Central

    Tanaka, Wakana; Ohmori, Yoshihiro; Ushijima, Tomokazu; Matsusaka, Hiroaki; Matsushita, Tomonao; Kumamaru, Toshihiro; Kawano, Shigeyuki; Hirano, Hiro-Yuki

    2015-01-01

    Axillary shoot formation is a key determinant of plant architecture. Formation of the axillary shoot is regulated by initiation of the axillary meristem or outgrowth of the axillary bud. Here, we show that rice (Oryza sativa) TILLERS ABSENT1 (TAB1; also known as Os WUS), an ortholog of Arabidopsis thaliana WUS, is required to initiate axillary meristem development. We found that formation of the axillary meristem in rice proceeds via a transient state, which we term the premeristem, characterized by the expression of OSH1, a marker of indeterminate cells in the shoot apical meristem. In the tab1-1 (wus-1) mutant, however, formation of the axillary meristem is arrested at various stages of the premeristem zone, and OSH1 expression is highly reduced. TAB1/WUS is expressed in the premeristem zone, where it shows a partially overlapping pattern with OSH1. It is likely, therefore, that TAB1 plays an important role in maintaining the premeristem zone and in promoting the formation of the axillary meristem by promoting OSH1 expression. Temporal expression patterns of WUSCHEL-RELATED HOMEOBOX4 (WOX4) indicate that WOX4 is likely to regulate meristem maintenance instead of TAB1 after establishment of the axillary meristem. Lastly, we show that the prophyll, the first leaf in the secondary axis, is formed from the premeristem zone and not from the axillary meristem. PMID:25841039

  1. Structure of a Yeast Dyn2-Nup159 Complex and Molecular Basis for Dynein Light Chain-Nuclear Pore Interaction*

    PubMed Central

    Romes, Erin M.; Tripathy, Ashutosh; Slep, Kevin C.

    2012-01-01

    The nuclear pore complex gates nucleocytoplasmic transport through a massive, eight-fold symmetric channel capped by a nucleoplasmic basket and structurally unique, cytoplasmic fibrils whose tentacles bind and regulate asymmetric traffic. The conserved Nup82 complex, composed of Nsp1, Nup82, and Nup159, forms the unique cytoplasmic fibrils that regulate mRNA nuclear export. Although the nuclear pore complex plays a fundamental, conserved role in nuclear trafficking, structural information about the cytoplasmic fibrils is limited. Here, we investigate the structural and biochemical interactions between Saccharomyces cerevisiae Nup159 and the nucleoporin, Dyn2. We find that Dyn2 is predominantly a homodimer and binds arrayed sites on Nup159, promoting the Nup159 parallel homodimerization. We present the first structure of Dyn2, determined at 1.85 Å resolution, complexed with a Nup159 target peptide. Dyn2 resembles homologous metazoan dynein light chains, forming homodimeric composite substrate binding sites that engage two independent 10-residue target motifs, imparting a β-strand structure to each peptide via antiparallel extension of the Dyn2 core β-sandwich. Dyn2 recognizes a highly conserved QT motif while allowing sequence plasticity in the flanking residues of the peptide. Isothermal titration calorimetric analysis of the comparative binding of Dyn2 to two Nup159 target sites shows similar affinities (18 and 13 μm), but divergent thermal binding modes. Dyn2 homodimers are arrayed in the crystal lattice, likely mimicking the arrayed architecture of Dyn2 on the Nup159 multivalent binding sites. Crystallographic interdimer interactions potentially reflect a cooperative basis for Dyn2-Nup159 complex formation. Our data highlight the determinants that mediate oligomerization of the Nup82 complex and promote a directed, elongated cytoplasmic fibril architecture. PMID:22411995

  2. Structure of a yeast Dyn2-Nup159 complex and molecular basis for dynein light chain-nuclear pore interaction.

    PubMed

    Romes, Erin M; Tripathy, Ashutosh; Slep, Kevin C

    2012-05-04

    The nuclear pore complex gates nucleocytoplasmic transport through a massive, eight-fold symmetric channel capped by a nucleoplasmic basket and structurally unique, cytoplasmic fibrils whose tentacles bind and regulate asymmetric traffic. The conserved Nup82 complex, composed of Nsp1, Nup82, and Nup159, forms the unique cytoplasmic fibrils that regulate mRNA nuclear export. Although the nuclear pore complex plays a fundamental, conserved role in nuclear trafficking, structural information about the cytoplasmic fibrils is limited. Here, we investigate the structural and biochemical interactions between Saccharomyces cerevisiae Nup159 and the nucleoporin, Dyn2. We find that Dyn2 is predominantly a homodimer and binds arrayed sites on Nup159, promoting the Nup159 parallel homodimerization. We present the first structure of Dyn2, determined at 1.85 Å resolution, complexed with a Nup159 target peptide. Dyn2 resembles homologous metazoan dynein light chains, forming homodimeric composite substrate binding sites that engage two independent 10-residue target motifs, imparting a β-strand structure to each peptide via antiparallel extension of the Dyn2 core β-sandwich. Dyn2 recognizes a highly conserved QT motif while allowing sequence plasticity in the flanking residues of the peptide. Isothermal titration calorimetric analysis of the comparative binding of Dyn2 to two Nup159 target sites shows similar affinities (18 and 13 μM), but divergent thermal binding modes. Dyn2 homodimers are arrayed in the crystal lattice, likely mimicking the arrayed architecture of Dyn2 on the Nup159 multivalent binding sites. Crystallographic interdimer interactions potentially reflect a cooperative basis for Dyn2-Nup159 complex formation. Our data highlight the determinants that mediate oligomerization of the Nup82 complex and promote a directed, elongated cytoplasmic fibril architecture.

  3. Computing Relative Joint Positions of Robot Arms

    NASA Technical Reports Server (NTRS)

    Barker, L. K.

    1986-01-01

    Vector-algebra method developed for extracting Denavit-Hartenberg parameters for any assembled robot arm. Method for extracting relative joint geometry of robot arms useful to researchers who need data for existing robot arms for either validation of mathematical models or for studies involving actual control of these devices. Method, does not require robot arm to be disassembled, also useful in recalibration of misalined or bent robot arm and becomes useful industrial procedure. Merit of method is errors not propagated.

  4. Proprioceptive Interaction between the Two Arms in a Single-Arm Pointing Task.

    PubMed

    Kigawa, Kazuyoshi; Izumizaki, Masahiko; Tsukada, Setsuro; Hakuta, Naoyuki

    2015-01-01

    Proprioceptive signals coming from both arms are used to determine the perceived position of one arm in a two-arm matching task. Here, we examined whether the perceived position of one arm is affected by proprioceptive signals from the other arm in a one-arm pointing task in which participants specified the perceived position of an unseen reference arm with an indicator paddle. Both arms were hidden from the participant's view throughout the study. In Experiment 1, with both arms placed in front of the body, the participants received 70-80 Hz vibration to the elbow flexors of the reference arm (= right arm) to induce the illusion of elbow extension. This extension illusion was compared with that when the left arm elbow flexors were vibrated or not. The degree of the vibration-induced extension illusion of the right arm was reduced in the presence of left arm vibration. In Experiment 2, we found that this kinesthetic interaction between the two arms did not occur when the left arm was vibrated in an abducted position. In Experiment 3, the vibration-induced extension illusion of one arm was fully developed when this arm was placed at an abducted position, indicating that the brain receives increased proprioceptive input from a vibrated arm even if the arm was abducted. Our results suggest that proprioceptive interaction between the two arms occurs in a one-arm pointing task when the two arms are aligned with one another. The position sense of one arm measured using a pointer appears to include the influences of incoming information from the other arm when both arms were placed in front of the body and parallel to one another.

  5. The Asteroid Redirect Mission (ARM)

    NASA Technical Reports Server (NTRS)

    Abell, Paul

    2015-01-01

    The National Aeronautics and Space Administration (NASA) is developing a robotic mission to visit a large near-Earth asteroid (NEA), collect a multi-ton boulder from its surface, and redirect it into a stable orbit around the Moon. Once returned to cislunar space in the mid-2020s, astronauts will explore the boulder and return to Earth with samples. This Asteroid Redirect Mission (ARM) is part of NASA's plan to advance the technologies, capabilities, and spaceflight experience needed for a human mission to the Martian system in the 2030s. Subsequent human and robotic missions to the asteroidal material would also be facilitated by its return to cislunar space. Although ARM is primarily a capability demonstration mission (i.e., technologies and associated operations), there exist significant opportunities to advance our knowledge of small bodies in the synergistic areas of science, planetary defense, asteroidal resources and in-situ resource utilization (ISRU), and capability and technology demonstrations. In order to maximize the knowledge return from the mission, NASA is organizing an ARM Investigation Team, which is being preceded by the Formulation Assessment and Support Team. These teams will be comprised of scientists, technologists, and other qualified and interested individuals to help plan the implementation and execution of ARM. An overview of robotic and crewed segments of ARM, including the mission requirements, NEA targets, and mission operations, will be provided along with a discussion of the potential opportunities associated with the mission.

  6. NASA's Asteroid Redirect Mission (ARM)

    NASA Astrophysics Data System (ADS)

    Abell, Paul; Mazanek, Dan; Reeves, David; Naasz, Bo; Cichy, Benjamin

    2015-11-01

    The National Aeronautics and Space Administration (NASA) is developing a robotic mission to visit a large near-Earth asteroid (NEA), collect a multi-ton boulder from its surface, and redirect it into a stable orbit around the Moon. Once returned to cislunar space in the mid-2020s, astronauts will explore the boulder and return to Earth with samples. This Asteroid Redirect Mission (ARM) is part of NASA’s plan to advance the technologies, capabilities, and spaceflight experience needed for a human mission to the Martian system in the 2030s. Subsequent human and robotic missions to the asteroidal material would also be facilitated by its return to cislunar space. Although ARM is primarily a capability demonstration mission (i.e., technologies and associated operations), there exist significant opportunities to advance our knowledge of small bodies in the synergistic areas of science, planetary defense, asteroidal resources and in-situ resource utilization (ISRU), and capability and technology demonstrations. In order to maximize the knowledge return from the mission, NASA is organizing an ARM Investigation Team, which is being preceded by the Formulation Assessment and Support Team. These teams will be comprised of scientists, technologists, and other qualified and interested individuals to help plan the implementation and execution of ARM. An overview of robotic and crewed segments of ARM, including the mission requirements, NEA targets, and mission operations, will be provided along with a discussion of the potential opportunities associated with the mission.

  7. Late outcomes for the surgical management of absent pulmonary valve syndrome in infants

    PubMed Central

    Hu, Renjie; Zhang, Haibo; Xu, Zhiwei; Liu, Jinfen; Su, Zhaokang; Ding, Wenxiang

    2013-01-01

    OBJECTIVES Absent pulmonary valve syndrome (APVS) is a rare cardiac malformation that is usually associated with aneurysmal dilatation of pulmonary arteries and respiratory distress. The surgical mortality of neonates and infants with APVS has decreased tremendously, from 60% in 1980s to 10–20% recently. This study retrospectively reviews surgical outcomes of our 10-year experience in patients with APVS. METHODS From 2002 to 2012, 42 patients with APVS underwent surgical correction. Thirty-seven patients had APVS as a variant of tetralogy of Fallot, 4 with double outlet right ventricle and 1 with ventricular septal defect. Respiratory distress was present in 12 infants. Four patients needed continuous positive airway pressure and 5 required intubation with mechanical ventilation before surgery. RESULTS There was no hospital death and 3 late deaths. The mean follow-up time was 62.71 ± 34.31 months. Significant differences were found in the duration of postoperative ventilation between patients with or without respiratory distress (P = 0.009) and patients with left or right aortic arch (P = 0.012). The Kaplan–Meier curve indicated that overall survival at 5 and 10 years was 92.4%. The survival rates between patients with or without respiratory distress were 72.7 and 100%, respectively (P = 0.003). Overall mortality was associated with longer cardiopulmonary bypass time (P = 0.004) and lower weight at operation (P = 0.042). There were no significant differences in survival and postoperative data such as the duration of ventilation or intensive care unit stay and New York Heart Association class among the three methods of right ventricular outflow tract (RVOT) reconstruction. CONCLUSIONS Surgical treatment of APVS has got favourable outcomes in terms of mortality and reoperation rate. Different methods of RVOT reconstruction do not affect the surgical outcome. Patients required long-term follow-up for postoperative respiratory complications secondary to persistent

  8. Is CFTR-delF508 Really Absent from the Apical Membrane of the Airway Epithelium?

    PubMed Central

    Borthwick, Lee A.; Botha, Phil; Verdon, Bernard; Brodlie, Malcolm J.; Gardner, Aaron; Bourn, David; Johnson, Gail E.

    2011-01-01

    Background Understanding where mutant CFTR is localised in airway epithelia is essential in guiding the best therapeutic approach to correct the dysfunction of the CFTR protein. The widely held paradigm is that CF patients harbouring the commonest mutation, CFTR-delF508, trap CFTR within the endoplasmic reticulum and target it for degradation. However there are conflicting reports concerning expression and localisation of CFTR-delF508 in lung tissue. To attempt to resolve this fundamental issue we developed a novel approach to measure CFTR-delF508 in the lower airways of patients who have undergone lung transplantation for advanced CF. By sampling CF and non-CF epithelium simultaneously from the same individual, confounding factors of different airway microenvironments which may have influenced previous observations can be overcome. Methods Epithelia sampled by bronchial brushing above (CF) and below (non-CF) the bronchial anastomosis were stained for CFTR and the localisation and level of expression assessed (n = 12). Results There was no significant difference in the proportion of tall columnar cells showing CFTR immunostaining as a discrete band at the apical membrane in cells harbouring the CFTR-delF508 mutation compared to non-CF cells (p = 0.21, n = 12). However, the amount of CFTR expressed at the apical surface was reduced by ∼50% in CF cells compared to non-CF cells (p = 0.04, n = 5). Conclusions Our novel observation challenges the prevailing paradigm that CFTR is essentially absent from the apical membrane of respiratory cells harbouring the CFTR-delF508 mutation. Moreover, it raises the possibility that the new generation of CFTR potentiators may offer a realistic therapeutic option for CF patients. PMID:21826241

  9. Duck TRIM27-L enhances MAVS signaling and is absent in chickens and turkeys.

    PubMed

    Blaine, Alysson H; Miranzo-Navarro, Domingo; Campbell, Lee K; Aldridge, Jerry R; Webster, Robert G; Magor, Katharine E

    2015-10-01

    Wild waterfowl, including mallard ducks, are the natural reservoir of avian influenza A virus and they are resistant to strains that would cause fatal infection in chickens. Here we investigate potential involvement of TRIM proteins in the differential response of ducks and chickens to influenza. We examine a cluster of TRIM genes located on a single scaffold in the duck genome, which is a conserved synteny group with a TRIM cluster located in the extended MHC region in chickens and turkeys. We note a TRIM27-like gene is present in ducks, and absent in chickens and turkeys. Orthologous genes are predicted in many birds and reptiles, suggesting the gene has been lost in chickens and turkeys. Using quantitative real-time PCR (qPCR) we show that TRIM27-L, and the related TRIM27.1, are upregulated 5- and 9-fold at 1 day post-infection with highly pathogenic A/Vietnam/1203/2004. To assess whether TRIM27.1 or TRIM27-L are involved in modulation of antiviral gene expression, we overexpressed them in DF1 chicken cells, and neither show any direct effect on innate immune gene expression. However, when co-transfected with duck RIG-I-N (d2CARD) to constitutively activate the MAVS pathway, TRIM27.1 weakly decreases, while TRIM27-L strongly activates innate immune signaling leading to increased transcription of antiviral genes MX1 and IFN-β. Furthermore, when both are co-expressed, the activation of the MAVS signaling pathway by TRIM27-L over-rides the inhibition by TRIM27.1. Thus, ducks have an activating TRIM27-L to augment MAVS signaling following RIG-I detection, while chickens lack both TRIM27-L and RIG-I itself.

  10. Arms Control past and future

    SciTech Connect

    Fox, T.R.

    1991-12-01

    I am going to talk today about Arms Control. First, I want to go over the recent history of the process. Five years ago, the pace of arms control changed dramatically. From an outsider it probably didn't appear that way -- but those working it, the shift from the historic glacial speed normally associated with this process to one of pressures -- political and economic -- national and global -- to actually conclude meaningful, verifiable agreements was a major change. Then, I want to spend a few minutes covering the future of arms control new that we have lost our enemy, and it is no longer a bipolar world. I also want to leave time for easy questions.

  11. Arms Control past and future

    SciTech Connect

    Fox, T.R.

    1991-12-01

    I am going to talk today about Arms Control. First, I want to go over the recent history of the process. Five years ago, the pace of arms control changed dramatically. From an outsider it probably didn`t appear that way -- but those working it, the shift from the historic glacial speed normally associated with this process to one of pressures -- political and economic -- national and global -- to actually conclude meaningful, verifiable agreements was a major change. Then, I want to spend a few minutes covering the future of arms control new that we have lost our enemy, and it is no longer a bipolar world. I also want to leave time for easy questions.

  12. Scanning ARM Cloud Radar Handbook

    SciTech Connect

    Widener, K; Bharadwaj, N; Johnson, K

    2012-06-18

    The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.

  13. Ergonomically neutral arm support system

    DOEpatents

    Siminovitch, Michael J; Chung, Jeffrey Y; Dellinges, Steven; Lafever, Robin E

    2005-08-02

    An ergonomic arm support system maintains a neutral position for the forearm. A mechanical support structure attached to a chair or other mounting structure supports the arms of a sitting or standing person. The system includes moving elements and tensioning elements to provide a dynamic balancing force against the forearms. The support structure is not fixed or locked in a rigid position, but is an active dynamic system that is maintained in equipoise by the continuous operation of the opposing forces. The support structure includes an armrest connected to a flexible linkage or articulated or pivoting assembly, which includes a tensioning element such as a spring. The pivoting assembly moves up and down, with the tensioning element providing the upward force that balances the downward force of the arm.

  14. Welcome to the U. S. arms superstore

    SciTech Connect

    Hartung, W.D. )

    1993-09-01

    After the 1991 Gulf War, the [open quotes]Big Five[close quotes]--the United States, France, Britain, the Soviet Union, and China--initiated talks on limiting the flow of arms to the Middle East and the United Nations established an arms register as a way to promote a more open international dialogue concerning the problem of conventional arms proliferation. Two and a half years later, the promises about arms controls have been forgotten in favor of a policy to sell arms to any nation possessing sufficient cash to purchase them. The promises to curb the weapons trade may have been forgotten because of the new dynamics that are driving the arms trade in the post-Cold War era. This article seeks to define these dynamics and to suggest means of getting the arms control process back on track. The rationale behind the commercialization of arms and means of combatting the arms exportation problem are emphasized. 18 refs.

  15. Assembly of an Intact Golgi Complex Requires Phospholipase A2 (PLA2) Activity, Membrane Tubules, and Dynein-Mediated Microtubule Transport

    PubMed Central

    Judson, Bret L.; Brown, William J.

    2009-01-01

    Previous studies have shown that treatment of mammalian cells with phospholipase A2 (PLA2) antagonists cause the normally interconnected Golgi ribbon to break up into large fragments of stacked Golgi cisternae (“mini-stacks”) that remain located in the juxtanuclear region. Using the reversible PLA2 antagonist, ONO-RS-082 (ONO) and live-cell, time-lapse microscopy to image the Golgi reassembly process, we found that Golgi mini-stacks underwent a burst of membrane tubule formation following washout of ONO: before washout only 4.3 ± 3.8 tubules/cell/10 min were formed, whereas after washout 29.9 ± 11.9 tubules/cell/10 min formed. These membranes tubules formed bridges between physically separate mini-stacks, thus mediating their coalescence into intact Golgi ribbons. Formation of inter-stack tubules and an intact Golgi ribbon was also facilitated by microtubules because treatment with nocodazole significantly inhibited both processes. This microtubule-dependent process was also dependent on dynein because the dynein inhibitor nordihydroguaiaretic acid (NDGA) inhibited reassembly. These studies show that a late stage of Golgi assembly occurs via membrane tubules, whose formation is dependent on PLA2 activity and microtubules. Considering these results together, we concluded that the maintenance and assembly of normal Golgi architecture is dependent on the PLA2-mediated, dynamic formation of inter-Golgi membrane tubules. PMID:19747452

  16. Femoral hypoplasia-unusual facies syndrome with bifid hallux, absent tibia, and macrophallus: a report of a Bedouin baby.

    PubMed Central

    Sabry, M A; Obenbergerova, D; Al-Sawan, R; Saleh, Q A; Farah, S; Al-Awadi, S A; Farag, T I

    1996-01-01

    A male Bedouin baby with the clinical profile of femoral hypoplasia-unusual facies syndrome is described. The phenotype includes bilateral asymmetrical lower limb hypoplasia/aplasia with short remnants of both femora, absent right tibia, bifid right big toe, dysmorphic facies, thoracic/pelvic abnormalities, macrophallus, and bilateral cryptorchidism. This report re-emphasises the previously described rare association of femoral hypoplasia-unusual facies syndrome with preaxial polydactyly and suggests that the clinical spectrum of the syndrome could be stretched further to accommodate other unusual traits, for example, macrophallus and absent tibia. Images PMID:8929957

  17. Amine templating effect absent in uranyl sulfates synthesized with 1,4-n-butyldiamine

    SciTech Connect

    Jouffret, Laurent J.; Wylie, Ernest M.; Burns, Peter C.

    2013-01-15

    Two new uranyl sulfates, (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2}){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS2) and (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2})(SO{sub 4}){sub 2}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS3), were synthesized and their crystal structures determined. NDUS2 was obtained in highly acidic media heat-treated at 373 K and subsequently maintained at 278 K until crystals formed after two months. NDUS3 results from the degradation of NDUS2 over the course of a few days. NDUS2 and NDUS3 crystallize in the monoclinic space group P2{sub 1}/n, a=10.9075(4) A, b=10.4513(4) A, c=17.7881(7) A, {beta}=97.908(2) Degree-Sign , V=2008.52(13) A{sup 3}, Z=4, at 140 K and a=8.8570(4) A, b=7.3299(3) A, c=20.4260(9) A, {beta}=95.140(2) Degree-Sign , V=1320.74(10) A{sup 3}, Z=4, at 140 K, respectively. The compounds contain interlayer 1,4-n-butyldiammonium cations that charge-balance the anionic structural units. - Graphical abstract: Amine templating effect absent in uranyl sulfates synthesized with 1,4-diaminobutane, as shown by the synthesis of two new uranyl sulfates, (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2}){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS2) and (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2})(SO{sub 4}){sub 2}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS3). Highlights: Black-Right-Pointing-Pointer Two layered uranyl sulfates were synthesized. Black-Right-Pointing-Pointer Amine molecules are located in the interlayers of the compounds. Black-Right-Pointing-Pointer No templating effect of the amine was observed. Black-Right-Pointing-Pointer Amine molecules are only charge balancing cations in the structures.

  18. 1H–NMR Metabolomic Biomarkers of Poor Outcome after Hemorrhagic Shock are Absent in Hibernators

    PubMed Central

    Bogren, Lori K.; Murphy, Carl J.; Johnston, Erin L.; Sinha, Neeraj; Serkova, Natalie J.; Drew, Kelly L.

    2014-01-01

    rats. These same biomarkers are absent in AGS after HS with warm I/R. PMID:25211248

  19. The 14-kDa Dynein Light Chain-Family Protein Dlc1 Is Required for Regular Oscillatory Nuclear Movement and Efficient Recombination during Meiotic Prophase in Fission Yeast

    PubMed Central

    Miki, Futaba; Okazaki, Koei; Shimanuki, Mizuki; Yamamoto, Ayumu; Hiraoka, Yasushi; Niwa, Osami

    2002-01-01

    A Schizosaccharomyces pombe spindle pole body (SPB) protein interacts in a two-hybrid system with Dlc1, which belongs to the 14-kDa Tctex-1 dynein light chain family. Green fluorescent protein-tagged Dlc1 accumulated at the SPB throughout the life cycle. During meiotic prophase, Dlc1 was present along astral microtubules and microtubule-anchoring sites on the cell cortex, reminiscent of the cytoplasmic dynein heavy chain Dhc1. In a dlc1-null mutant, Dhc1-dependent nuclear movement in meiotic prophase became irregular in its duration and direction. Dhc1 protein was displaced from the cortex anchors and the formation of microtubule bundle(s) that guide nuclear movement was impaired in the mutant. Meiotic recombination in the dlc1 mutant was reduced to levels similar to that in the dhc1 mutant. Dlc1 and Dhc1 also have roles in karyogamy and rDNA relocation during the sexual phase. Strains mutated in both the dlc1 and dhc1 loci displayed more severe defects in recombination, karyogamy, and sporulation than in either single mutant alone, suggesting that Dlc1 is involved in nuclear events that are independent of Dhc1. S. pombe contains a homolog of the 8-kDa dynein light chain, Dlc2. This class of dynein light chain, however, is not essential in either the vegetative or sexual phases. PMID:11907273

  20. Hand/Wrist/Arm Problems

    MedlinePlus

    ... your doctor right away.Start OverDiagnosisYou may have TENDINITIS, inflammation of a tendon.Self CareUse an over- ... OverDiagnosisYour may have TENNIS ELBOW, a type of TENDINITIS.Self CareRest the arm, apply ice packs to ...

  1. Minorities in the Armed Forces

    ERIC Educational Resources Information Center

    Griggs, Anthony

    1973-01-01

    Summarizes the findings of the Congressional Black Caucus and the specially formed task force; reports that high ranking officers have pledged to attack racial discrimination; and describes an association of minority officers whose purpose is to enhance the image of the armed forces within the minority community. (Author/JM)

  2. Deficits of Semantic Control Produce Absent or Reverse Frequency Effects in Comprehension: Evidence from Neuropsychology and Dual Task Methodology

    ERIC Educational Resources Information Center

    Almaghyuli, Azizah; Thompson, Hannah; Lambon Ralph, Matthew A.; Jefferies, Elizabeth

    2012-01-01

    Patients with multimodal semantic impairment following stroke (referred to here as "semantic aphasia" or SA) fail to show the standard effects of frequency in comprehension tasks. Instead, they show absent or even "reverse" frequency effects: i.e., better understanding of less common words. In addition, SA is associated with poor regulatory…

  3. The Concept of the Absent Curriculum: The Case of the Muslim Contribution and the English National Curriculum for History

    ERIC Educational Resources Information Center

    Wilkinson, Matthew L. N.

    2014-01-01

    This paper introduces the concept of the "absent curriculum" on the premise that the study of curriculum has been prone to privileging curricular presence to the exclusion of curricular absence. In order to address this imbalance and to articulate a theory of absence in the curriculum, the paper applies ideas derived from the philosophy…

  4. New technologies and the arms race

    SciTech Connect

    Schaerf, C.; Reid, B.H.; Carlton, D.

    1989-01-01

    This volume contains the proceedings of the International Conference on Technology, the Arms Race and Arms Control. Topics covered include: Cosmic space and the role of Europe and Non-military justification for investments in military technologies.

  5. Does Octopus vulgaris have preferred arms?

    PubMed

    Byrne, Ruth A; Kuba, Michael J; Meisel, Daniela V; Griebel, Ulrike; Mather, Jennifer A

    2006-08-01

    Previous behavioral studies in Octopus vulgaris revealed lateralization of eye use. In this study, the authors expanded the scope to investigate arm preferences. The octopus's generalist hunting lifestyle and the structure of their arms suggest that these animals have no need to designate specific arms for specific tasks. However, octopuses also show behaviors, like exploration, in which only single or small groups of arms are involved. Here the authors show that octopuses had a strong preference for anterior arm use to reach for and explore objects, which points toward a task division between anterior and posterior arms. Four out of 8 subjects also showed a lateral bias. In addition, octopuses had a preference for a specific arm to reach into a T maze to retrieve a food reward. These findings give evidence for limb-specialization in an animal whose 8 arms were believed to be equipotential.

  6. Low-cost robotic arm control

    NASA Astrophysics Data System (ADS)

    Rogers, John R.

    2008-04-01

    A low-cost robotic arm and controller system is presented. The controller is a desktop model of the robotic arm with the same degrees of freedom whose joints are equipped with sensors. Manipulating the controller by hand causes the robotic arm to mimic the movement in maser-slave fashion. The system takes advantage of the low cost and wide availability of hobby radio control components and uses a low-cost, easy-to-program microprocessor. The system is implemented with a video camera on the robotic arm, and the arm is mounted on an unmanned omnidirectional vehicle inspection robot. With a camera on the end of a robot arm, the vehicle inspection system can reach difficult to-access regions of the vehicle underbody. Learning to manipulate the robot arm with this controller is faster than learning with a traditional joystick. Limitations of the microcontroller are discussed, and suggestions for further development of the robot arm and control are made.

  7. Overcoming Robot-Arm Joint Singularities

    NASA Technical Reports Server (NTRS)

    Barker, L. K.; Houck, J. A.

    1986-01-01

    Kinematic equations allow arm to pass smoothly through singular region. Report discusses mathematical singularities in equations of robotarm control. Operator commands robot arm to move in direction relative to its own axis system by specifying velocity in that direction. Velocity command then resolved into individual-joint rotational velocities in robot arm to effect motion. However, usual resolved-rate equations become singular when robot arm is straightened.

  8. 32 CFR 935.134 - Arm signals.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Arm signals. 935.134 Section 935.134 National... WAKE ISLAND CODE Motor Vehicle Code § 935.134 Arm signals. (a) Any person operating a motor vehicle and... signal for a turn or stop is made by fully extending the left arm as follows: (1) Left turn—extend...

  9. 33 CFR 154.510 - Loading arms.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Loading arms. 154.510 Section 154... FACILITIES TRANSFERRING OIL OR HAZARDOUS MATERIAL IN BULK Equipment Requirements § 154.510 Loading arms. (a) Each mechanical loading arm used for transferring oil or hazardous material and placed into...

  10. 32 CFR 935.134 - Arm signals.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Arm signals. 935.134 Section 935.134 National... WAKE ISLAND CODE Motor Vehicle Code § 935.134 Arm signals. (a) Any person operating a motor vehicle and... signal for a turn or stop is made by fully extending the left arm as follows: (1) Left turn—extend...

  11. 32 CFR 935.134 - Arm signals.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Arm signals. 935.134 Section 935.134 National... WAKE ISLAND CODE Motor Vehicle Code § 935.134 Arm signals. (a) Any person operating a motor vehicle and... signal for a turn or stop is made by fully extending the left arm as follows: (1) Left turn—extend...

  12. 32 CFR 935.134 - Arm signals.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Arm signals. 935.134 Section 935.134 National... WAKE ISLAND CODE Motor Vehicle Code § 935.134 Arm signals. (a) Any person operating a motor vehicle and... signal for a turn or stop is made by fully extending the left arm as follows: (1) Left turn—extend...

  13. 33 CFR 154.510 - Loading arms.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Loading arms. 154.510 Section 154... FACILITIES TRANSFERRING OIL OR HAZARDOUS MATERIAL IN BULK Equipment Requirements § 154.510 Loading arms. (a) Each mechanical loading arm used for transferring oil or hazardous material and placed into...

  14. 32 CFR 935.134 - Arm signals.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Arm signals. 935.134 Section 935.134 National... WAKE ISLAND CODE Motor Vehicle Code § 935.134 Arm signals. (a) Any person operating a motor vehicle and... signal for a turn or stop is made by fully extending the left arm as follows: (1) Left turn—extend...

  15. 33 CFR 154.510 - Loading arms.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Loading arms. 154.510 Section 154... FACILITIES TRANSFERRING OIL OR HAZARDOUS MATERIAL IN BULK Equipment Requirements § 154.510 Loading arms. (a) Each mechanical loading arm used for transferring oil or hazardous material and placed into...

  16. 33 CFR 154.510 - Loading arms.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Loading arms. 154.510 Section 154... FACILITIES TRANSFERRING OIL OR HAZARDOUS MATERIAL IN BULK Equipment Requirements § 154.510 Loading arms. (a) Each mechanical loading arm used for transferring oil or hazardous material and placed into...

  17. 33 CFR 154.510 - Loading arms.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Loading arms. 154.510 Section 154... FACILITIES TRANSFERRING OIL OR HAZARDOUS MATERIAL IN BULK Equipment Requirements § 154.510 Loading arms. (a) Each mechanical loading arm used for transferring oil or hazardous material and placed into...

  18. 77 FR 30875 - Armed Forces Day, 2012

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-23

    ... Documents#0;#0; ] Proclamation 8823 of May 18, 2012 Armed Forces Day, 2012 By the President of the United... circumstances. On Armed Forces Day, we pay tribute to the unparalleled service of our Armed Forces and recall... Day. I direct the Secretary of Defense on behalf of the Army, Navy, Air Force, and Marine Corps,...

  19. Arm Tremor, Tardive Dyskinesia, and Mental Retardation.

    ERIC Educational Resources Information Center

    van Emmerik, R. E. A.; And Others

    1993-01-01

    The arm tremor of adults (n=32) diagnosed as having mental retardation and/or tardive dyskinesia was examined through an analysis of the acceleration properties of several arm postures. The degree of arm acceleration was increased in all subjects compared to a control group without mental retardation. Effects of neuroleptic medication were noted.…

  20. Spirality: Spiral arm pitch angle measurement

    NASA Astrophysics Data System (ADS)

    Shields, Douglas W.; Boe, Benjamin; Pfountz, Casey; Davis, Benjamin L.; Hartley, Matthew; Pour Imani, Hamed; Slade, Zac; Kennefick, Daniel; Kennefick, Julia

    2015-12-01

    Spirality measures spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Written in MATLAB, the code package also includes GenSpiral, which produces FITS images of synthetic spirals, and SpiralArmCount, which uses a one-dimensional Fast Fourier Transform to count the spiral arms of a galaxy after its pitch is determined.

  1. Regenerator cross arm seal assembly

    DOEpatents

    Jackman, Anthony V.

    1988-01-01

    A seal assembly for disposition between a cross arm on a gas turbine engine block and a regenerator disc, the seal assembly including a platform coextensive with the cross arm, a seal and wear layer sealingly and slidingly engaging the regenerator disc, a porous and compliant support layer between the platform and the seal and wear layer porous enough to permit flow of cooling air therethrough and compliant to accommodate relative thermal growth and distortion, a dike between the seal and wear layer and the platform for preventing cross flow through the support layer between engine exhaust and pressurized air passages, and air diversion passages for directing unregenerated pressurized air through the support layer to cool the seal and wear layer and then back into the flow of regenerated pressurized air.

  2. Cold warriors target arms control

    SciTech Connect

    Isaacs, J.

    1995-09-01

    While disagreements over the conflict in Bosnia have strained US relations with Western Europe and Russia, these divisions will pale in comparison to the tensions that will arise if recent congressional arms control decisions become law. If the Republicans who dominate Congress are successful, a series of arms control agreements painstakingly negotiated by Republican and Democratic presidents could be consigned to the ash heap. This list includes the Start I and Start II nuclear reduction agreements, the 1972 Anti-Ballistic Missile (ABM) Treaty and the ongoing negotiations to achieve a comprehensive test ban (CTB) by 1996. US leadership in the post-Cold War era will undermined as the international community, already skeptical about this country`s direction, will question the ability of the executive branch to surmount isolantionist impulses.

  3. Dual arm master controller development

    NASA Technical Reports Server (NTRS)

    Kuban, D. P.; Perkins, G. S.

    1985-01-01

    The advanced servomanipulator (ASM) slave was designed with an anthropomorphic stance gear/torque tube power drives, and modular construction. These features resulted in increased inertia, friction, and backlash relative to tape driven manipulators. Studies were performed which addressed to human factor design and performance tradeoffs associated with the corresponding master controller best suited for the ASM. The results of these studies, as well as the conceptual design of the dual arm master controller, are presented.

  4. The DOE ARM Aerial Facility

    SciTech Connect

    Schmid, Beat; Tomlinson, Jason M.; Hubbe, John M.; Comstock, Jennifer M.; Mei, Fan; Chand, Duli; Pekour, Mikhail S.; Kluzek, Celine D.; Andrews, Elisabeth; Biraud, S.; McFarquhar, Greg

    2014-05-01

    The Department of Energy Atmospheric Radiation Measurement (ARM) Program is a climate research user facility operating stationary ground sites that provide long-term measurements of climate relevant properties, mobile ground- and ship-based facilities to conduct shorter field campaigns (6-12 months), and the ARM Aerial Facility (AAF). The airborne observations acquired by the AAF enhance the surface-based ARM measurements by providing high-resolution in-situ measurements for process understanding, retrieval-algorithm development, and model evaluation that are not possible using ground- or satellite-based techniques. Several ARM aerial efforts were consolidated into the AAF in 2006. With the exception of a small aircraft used for routine measurements of aerosols and carbon cycle gases, AAF at the time had no dedicated aircraft and only a small number of instruments at its disposal. In this "virtual hangar" mode, AAF successfully carried out several missions contracting with organizations and investigators who provided their research aircraft and instrumentation. In 2009, AAF started managing operations of the Battelle-owned Gulfstream I (G-1) large twin-turboprop research aircraft. Furthermore, the American Recovery and Reinvestment Act of 2009 provided funding for the procurement of over twenty new instruments to be used aboard the G-1 and other AAF virtual-hangar aircraft. AAF now executes missions in the virtual- and real-hangar mode producing freely available datasets for studying aerosol, cloud, and radiative processes in the atmosphere. AAF is also engaged in the maturation and testing of newly developed airborne sensors to help foster the next generation of airborne instruments.

  5. Hand-arm vibration syndrome

    PubMed Central

    Shen, Shixin (Cindy); House, Ronald A.

    2017-01-01

    Abstract Objective To provide family physicians with an understanding of the epidemiology, pathogenesis, symptoms, diagnosis, and management of hand-arm vibration syndrome (HAVS), an important and common occupational disease in Canada. Sources of information A MEDLINE search was conducted for research and review articles on HAVS. A Google search was conducted to obtain gray literature relevant to the Canadian context. Additional references were obtained from the articles identified. Main message Hand-arm vibration syndrome is a prevalent occupational disease affecting workers in multiple industries in which vibrating tools are used. However, it is underdiagnosed in Canada. It has 3 components—vascular, in the form of secondary Raynaud phenomenon; sensorineural; and musculoskeletal. Hand-arm vibration syndrome in its more advanced stages contributes to substantial disability and poor quality of life. Its diagnosis requires careful history taking, in particular occupational history, physical examination, laboratory tests to rule out alternative diagnoses, and referral to an occupational medicine specialist for additional investigations. Management involves reduction of vibration exposure, avoidance of cold conditions, smoking cessation, and medication. Conclusion To ensure timely diagnosis of HAVS and improve prognosis and quality of life, family physicians should be aware of this common occupational disease and be able to elicit the relevant occupational history, refer patients to occupational medicine clinics, and appropriately initiate compensation claims. PMID:28292796

  6. High precision detector robot arm system

    DOEpatents

    Shu, Deming; Chu, Yong

    2017-01-31

    A method and high precision robot arm system are provided, for example, for X-ray nanodiffraction with an X-ray nanoprobe. The robot arm system includes duo-vertical-stages and a kinematic linkage system. A two-dimensional (2D) vertical plane ultra-precision robot arm supporting an X-ray detector provides positioning and manipulating of the X-ray detector. A vertical support for the 2D vertical plane robot arm includes spaced apart rails respectively engaging a first bearing structure and a second bearing structure carried by the 2D vertical plane robot arm.

  7. Fetal MRI correlates with postnatal CT angiogram assessment of pulmonary anatomy in tetralogy of Fallot with absent pulmonary valve.

    PubMed

    Sun, Heather Y; Boe, Justin; Rubesova, Erika; Barth, Richard A; Tacy, Theresa A

    2014-01-01

    In tetralogy of Fallot with absent pulmonary valve, pulmonary stenosis and regurgitation results in significant pulmonary artery dilatation. Branch pulmonary artery dilatation often compresses the tracheobronchial tree, causing fluid trapping in fetal life and air trapping and/or atelectasis after birth. Prenatal diagnosis predicts poor prognosis, which depends on the degree of respiratory insufficiency from airway compromise and lung parenchymal disease after birth. Fetal magnetic resonance imaging (MRI) has been useful in evaluating the effects of congenital lung lesions on lung development and indicating severity of pulmonary hypoplasia. This report is the first demonstrating the utility of fetal MRI in tetralogy of Fallot/absent pulmonary valve patients, which predicted postnatal pulmonary artery size and visualized airway compression and lung parenchymal lesions. The distribution of lobar fluid trapping on fetal MRI correlated with air trapping on postnatal computed tomography angiogram.

  8. Echinorhynchus salmonis Müller, 1784 absent in Britain and Ireland: re-identification of museum specimens.

    PubMed

    Chubb, James C

    2004-03-01

    Collections of 'Echinorhynchus salmonis' from Britain and Ireland deposited in The Natural History Museum, London (1921.7.19.3-12 and 1952.10.30.122-127) were re-identified as Acanthocephalus clavula and Acanthocephalus lucii respectively. The amphipod, Pontoporeia affinis, European intermediate host of E. salmonis, does not occur in the British Isles, so it is concluded that E. salmonis is absent from British and Irish freshwater fishes.

  9. Left-right symmetry breaking in mice by left-right dynein may occur via a biased chromatid segregation mechanism, without directly involving the Nodal gene.

    PubMed

    Sauer, Stephan; Klar, Amar J S

    2012-01-01

    Ever since cloning the classic iv (inversedviscerum) mutation identified the "left-right dynein" (lrd) gene in mice, most research on body laterality determination has focused on its function in motile cilia at the node embryonic organizer. This model is attractive, as it links chirality of cilia architecture to asymmetry development. However, lrd is also expressed in blastocysts and embryonic stem cells, where it was shown to bias the segregation of recombined sister chromatids away from each other in mitosis. These data suggested that lrd is part of a cellular mechanism that recognizes and selectively segregates sister chromatids based on their replication history: old "Watson" versus old "Crick" strands. We previously proposed that the mouse left-right axis is established via an asymmetric cell division prior to/or during gastrulation. In this model, left-right dynein selectively segregates epigenetically differentiated sister chromatids harboring a hypothetical "left-right axis development 1" ("lra1") gene during the left-right axis establishing cell division. Here, asymmetry development would be ultimately governed by the chirality of the cytoskeleton and the DNA molecule. Our model predicts that randomization of chromatid segregation in lrd mutants should produce embryos with 25% situs solitus, 25% situs inversus, and 50% embryonic death due to heterotaxia and isomerism. Here we confirmed this prediction by using two distinct lrd mutant alleles. Other than lrd, thus far Nodal gene is the most upstream function implicated in visceral organs laterality determination. We next tested whether the Nodal gene constitutes the lra1 gene hypothesized in the model by testing mutant's effect on 50% embryonic lethality observed in lrd mutants. Since Nodal mutation did not suppress lethality, we conclude that Nodal is not equivalent to the lra1 gene. In summary, we describe the origin of 50% lethality in lrd mutant mice not yet explained by any other laterality

  10. Sertoli cell processes have axoplasmic features: an ordered microtubule distribution and an abundant high molecular weight microtubule- associated protein (cytoplasmic dynein)

    PubMed Central

    1988-01-01

    Microtubules in the cytoplasm of rat Sertoli cell stage VI-VIII testicular seminiferous epithelium were studied morphometrically by electron microscopy. The Sertoli cell microtubules demonstrated axonal features, being largely parallel in orientation and predominantly spaced one to two microtubule diameters apart, suggesting the presence of microtubule-bound spacer molecules. Testis microtubule-associated proteins (MAPs) were isolated by a taxol, salt elution procedure. Testis MAPs promoted microtubule assembly, but to a lesser degree than brain MAPs. High molecular weight MAPs, similar in electrophoretic mobilities to brain MAP-1 and MAP-2, were prominent components of total testis MAPs, though no shared immunoreactivity was detected between testis and brain high molecular weight MAPs using both polyclonal and monoclonal antibodies. Unlike brain high molecular weight MAPs, testis high molecular weight MAPs were not heat stable. Testis MAP composition, studied on postnatal days 5, 10, 15, and 24 and in the adult, changed dramatically during ontogeny. However, the expression of the major testis high molecular weight MAP, called HMW-2, was constitutive and independent of the development of mature germ cells. The Sertoli cell origin of HMW-2 was confirmed by identifying this protein as the major MAP found in an enriched Sertoli cell preparation and in two rat models of testicular injury characterized by germ cell depletion. HMW-2 was selectively released from testis microtubules by ATP and co-purified by sucrose density gradient centrifugation with MAP- 1C, a neuronal cytoplasmic dynein. The inhibition of the microtubule- activated ATPase activity of HMW-2 by vanadate and erythro-(2-hydroxy-3- nonyl)adenine and its proteolytic breakdown by vanadate-dependent UV photocleavage confirmed the dynein-like nature of HMW-2. As demonstrated by this study, the neuronal and Sertoli cell cytoskeletons share morphological, structural and functional properties. PMID:2972729

  11. The Asteroid Redirect Mission (ARM)

    NASA Astrophysics Data System (ADS)

    Abell, Paul; Gates, Michele; Johnson, Lindley; Chodas, Paul; Mazanek, Dan; Reeves, David; Ticker, Ronald

    2016-07-01

    To achieve its long-term goal of sending humans to Mars, the National Aeronautics and Space Administration (NASA) plans to proceed in a series of incrementally more complex human spaceflight missions. Today, human flight experience extends only to Low-Earth Orbit (LEO), and should problems arise during a mission, the crew can return to Earth in a matter of minutes to hours. The next logical step for human spaceflight is to gain flight experience in the vicinity of the Moon. These cis-lunar missions provide a "proving ground" for the testing of systems and operations while still accommodating an emergency return path to the Earth that would last only several days. Cis-lunar mission experience will be essential for more ambitious human missions beyond the Earth-Moon system, which will require weeks, months, or even years of transit time. In addition, NASA has been given a Grand Challenge to find all asteroid threats to human populations and know what to do about them. Obtaining knowledge of asteroid physical properties combined with performing technology demonstrations for planetary defense provide much needed information to address the issue of future asteroid impacts on Earth. Hence the combined objectives of human exploration and planetary defense give a rationale for the Asteroid Re-direct Mission (ARM). Mission Description: NASA's ARM consists of two mission segments: 1) the Asteroid Redirect Robotic Mission (ARRM), the first robotic mission to visit a large (greater than ~100 m diameter) near-Earth asteroid (NEA), collect a multi-ton boulder from its surface along with regolith samples, demonstrate a planetary defense technique, and return the asteroidal material to a stable orbit around the Moon; and 2) the Asteroid Redirect Crewed Mission (ARCM), in which astronauts will take the Orion capsule to rendezvous and dock with the robotic vehicle, conduct multiple extravehicular activities to explore the boulder, and return to Earth with samples. NASA's proposed

  12. ASSEMBLY AND CHARACTERIZATION OF 8-ARM AND 12-ARM DNA BRANCHED JUNCTIONS

    PubMed Central

    Wang, Xing

    2012-01-01

    Branched DNA molecules can be assembled into objects and networks directed by sticky-ended cohesion. The connectivity of these species is limited by the number of arms flanking the branch point. To date, the only branched junctions constructed contain six or fewer arms. We report the construction of DNA branched junctions that contain either 8 or 12 double helical arms surrounding a branch point. The design of the 8-arm junction expoits the limits of a previous approach to thwart branch migration, but the design of the 12-arm junction uses a new to principle achieve this end. The 8-arm junction is stable with 16 nucleotide pairs per arm, but the 12-arm junction has been stabilized by 24 nucleotide pairs per arm. Ferguson analysis of these junctions in combination with three, four, five, and six-arm junctions indicates a linear increase in friction constant as the number of arms increases; the four-arm junction migrates anomalously at 4°C., suggesting stacking of its domains. All strands in both the 8-arm and 12-arm junctions show similar responses to hydroxyl radical autofootprinting analysis, indicating that they lack any dominant stacking structures. The stability of the 12-arm junction demonstrates that the number of arms in a junction is not limited to the case of having adjacent identical base pairs flanking the junction. The ability to construct eight-arm and twelve-arm junctions increases the number of objects, graphs and networks that can be built from branched DNA components. In principle, the stick structure corresponding to cubic close packing is now a possible target for assembly by DNA nanotechnology. PMID:17564446

  13. Arms Control: a Selected Bibliography

    DTIC Science & Technology

    1990-01-01

    THE REAGAN YEARS. Lexington, MA: Lexington Books, 1987. (JX1974.7 R33 1987) Seaborg , Glenn T. STEMMING THE TIDE: ARMS CONTROL IN THE JOHNSON YEARS...William, and Seaborg , Glenn T. "Non-Nuclear States Move to End Testing." BULLETIN OF THE ATOMIC SCIENTISTS, Vol. 45, June 1989, pp. 36-37. "European...STRATEGIC OFFENSIVE FORCE REDUCTION PORTION OF THE NUCLEAR AND SPACE TALKS IN GENEVA, by Edward L. Warner, III, Glenn A. Kent, and Randall J. DeValk. Note N

  14. NASA's Asteroid Redirect Mission (ARM)

    NASA Technical Reports Server (NTRS)

    Abell, P. A.; Mazanek, D. D.; Reeves, D. M.; Chodas, P. W.; Gates, M. M.; Johnson, L. N.; Ticker, R. L.

    2017-01-01

    Mission Description and Objectives: NASA's Asteroid Redirect Mission (ARM) consists of two mission segments: 1) the Asteroid Redirect Robotic Mission (ARRM), a robotic mission to visit a large (greater than approximately 100 meters diameter) near-Earth asteroid (NEA), collect a multi-ton boulder from its surface along with regolith samples, and return the asteroidal material to a stable orbit around the Moon; and 2) the Asteroid Redirect Crewed Mission (ARCM), in which astronauts will explore and investigate the boulder and return to Earth with samples. The ARRM is currently planned to launch at the end of 2021 and the ARCM is scheduled for late 2026.

  15. Python-ARM Radar Toolkit

    SciTech Connect

    Jonathan Helmus, Scott Collis

    2013-03-17

    The Python-ARM Radar Toolkit (Py-ART) is a collection of radar quality control and retrieval codes which all work on two unifying Python objects: the PyRadar and PyGrid objects. By building ingests to several popular radar formats and then abstracting the interface Py-ART greatly simplifies data processing over several other available utilities. In addition Py-ART makes use of Numpy arrays as its primary storage mechanism enabling use of existing and extensive community software tools.

  16. Navy autonomy thwarts arms control

    SciTech Connect

    Arkin, W.M.

    1987-09-01

    During the past three decades the two superpowers have steadily modernized their naval forces, sent large numbers of nuclear weapons to sea, and engaged in provocative and potentially destabilizing operations. Currently the US is deploying new aircraft carriers, a new generation of fighter aircraft, and new surface ships with greater offensive and defensive power. The Soviet Union has deployed a new generation of attack submarines and is completing its first large aircraft carrier. And the Soviets are preparing to follow the US lead in deploying long-range, highly accurate sea-launched cruise missiles. These developments, accompanied by naval operations that increase the potential for superpower conflict at sea, should make naval arms control a high priority. But it has not been a focus of US-Soviet negotiations and only recently has garnered more interest from multilateral disarmament bodies. An examination of the record shows that bilateral efforts in this area have been minimal and impeded by strong opposition, particularly from the US Navy. The multilateral approach may be more promising because of five agreements affecting the seas that could offer precedents, but this will require improved coordination between the arms control and law of the sea processes. 10 references.

  17. Arms races between and within species.

    PubMed

    Dawkins, R; Krebs, J R

    1979-09-21

    An adaptation in one lineage (e.g. predators) may change the selection pressure on another lineage (e.g. prey), giving rise to a counter-adaptation. If this occurs reciprocally, an unstable runaway escalation or 'arms race' may result. We discuss various factors which might give one side an advantage in an arms race. For example, a lineage under strong selection may out-evolve a weakly selected one (' the life-dinner principle'). We then classify arms races in two independent ways. They may be symmetric or asymmetric, and they may be interspecific or intraspecific. Our example of an asymmetric interspecific arms race is that between brood parasites and their hosts. The arms race concept may help to reduce the mystery of why cuckoo hosts are so good at detecting cuckoo eggs, but so bad at detecting cuckoo nestlings. The evolutionary contest between queen and worker ants over relative parental investment is a good example of an intraspecific asymmetric arms race. Such cases raise special problems because the participants share the same gene pool. Interspecific symmetric arms races are unlikely to be important, because competitors tend to diverge rather than escalate competitive adaptations. Intraspecific symmetric arms races, exemplified by adaptations for male-male competition, may underlie Cope's Rule and even the extinction of lineages. Finally we consider ways in which arms races can end. One lineage may drive the other to extinction; one may reach an optimum, thereby preventing the other from doing so; a particularly interesting possibility, exemplified by flower-bee coevolution, is that both sides may reach a mutual local optimum; lastly, arms races may have no stable and but may cycle continuously. We do not wish necessarily to suggest that all, or even most, evolutionary change results from arms races, but we do suggest that the arms race concept may help to resolve three long-standing questions in evolutionary theory.

  18. Lever arm dysfunction in cerebral palsy gait.

    PubMed

    Theologis, Tim

    2013-11-01

    Skeletal structures act as lever arms during walking. Muscle activity and the ground reaction against gravity exert forces on the skeleton, which generate torque (moments) around joints. These lead to the sequence of movements which form normal human gait. Skeletal deformities in cerebral palsy (CP) affect the function of bones as lever arms and compromise gait. Lever arm dysfunction should be carefully considered when contemplating treatment to improve gait in children with CP.

  19. Dynamic analysis for robot arm control

    NASA Technical Reports Server (NTRS)

    Bejczy, A. K.

    1983-01-01

    Explicit state equations provide detailed analytic insight into the dynamic behavior of a robot arm and facilitate the understanding of the control problem. The analytic strength of explicit state equations is exemplified for a given robot arm. In fact, for the quoted example, the explicit and exact state equations involve considerably less computation than the use of the known most efficient general-purpose computational algorithm for robot arm dynamics.

  20. Simplified robot arm dynamics for control

    NASA Technical Reports Server (NTRS)

    Bejczy, A. K.; Paul, R. P.

    1981-01-01

    A brief summary and evaluation is presented on the use of symbolic state equation techniques in order to represent robot arm dynamics with sufficient accuracy for controlling arm motion. The use of homogeneous transformations and the Lagrangian formulation of mechanics offers a convenient frame for the derivation, analysis and simplification of complex robot dynamics equations. It is pointed out that simplified state equations can represent robot arm dynamics with good accuracy.

  1. Introduction to Reading and Visualizing ARM Data

    SciTech Connect

    Mather, James

    2014-02-18

    Atmospheric Radiation Measurement (ARM) Program standard data format is NetCDF 3 (Network Common Data Form). The object of this tutorial is to provide a basic introduction to NetCDF with an emphasis on aspects of the ARM application of NetCDF. The goal is to provide basic instructions for reading and visualizing ARM NetCDF data with the expectation that these examples can then be applied to more complex applications.

  2. Letter report: Ari Patrinos -- ARM summary

    SciTech Connect

    MacDonald, G.J.; Ruderman, M.A.; Treiman, S.B.

    1995-07-27

    This letter report provides a summary of the authors` views on ARM. ARM is a highly focused program designed to improve understanding of the transport of infrared and solar radiation through the atmosphere. The program pays particular attention to the interaction of radiation with the three phases of water. The goals of ARM are usually articulated in terms of improvements in climate models. The authors agree that ARM can indeed make significant contributions to the understanding of climate change. In addition they believe that the results of the program will have wide applicability to a broad range of problems, including more accurate short-term and seasonal weather forecasting.

  3. Arms Transfers to the Irish Republican Army.

    DTIC Science & Technology

    1987-06-01

    and Policy Sciences 3 • " . %" "i - .% *’ -.. " - ’ .’’" -W%" . ’% G " %,’’ .- "S.*" *’I % ’ %- ABSTRACT 1, - This -ia, describes the arms transfer...from the policy of divestiture added insult to injury. There were sharp increases in the late 󈨀s in both arms manufacturing and in the volume of...through arms transfers to the Irish rebels coincided in time with several relevant changes; (1) the coordination of Eastern bloc arms 45 transfer policies

  4. Changing patterns of US arms transfers

    SciTech Connect

    Salomone, M.D.

    1985-01-01

    The thesis has three purposes. First is to explore the changing patterns of US arms transfers from Fiscal Year 1950 (FY 1950) through Fiscal Year 1980 (FY 1980). Second, is to describe and assess the decision-making process for arms transfers within the US Government. Third is to examine and critique the conventional wisdom concerning US arms transfers, to support that wisdom, or to offer an alternate empirically supported view. The conventional wisdom about US arms transfer is that they have been rising at an alarming rate, and that this is the result of an arms transfer decision-making process which is out of control. This belief is founded on an empirically based proposition that arms transfers have been rising at an alarming rate. However, this proposition has never been empirically validated. To explore this conventional wisdom, the author establishes the historical, political and defense policy contexts for US arms transfers over the period FY 1950 through FY 1980. The author critiques the conventional wisdom about US arms transfers, analyzes the many ways that arms transfers have been measured, and explores the impediments to accurate measurement and assessment of the phenomenon.

  5. Low friction high speed rocker arm

    SciTech Connect

    Simko, A.O.

    1987-07-28

    A valve train is described for an internal combustion engine comprising, a camshaft mounted close above the cylinder head face of the engine, a one-piece essentially U-shaped rocker arm mounted above the camshaft for an arcuate movement and defined by a bottom wall integral with a pair of laterally spaced upstanding side walls. The bottom wall has a cylindrical fulcrum surface projecting upwardly. A lash adjuster fixedly supports above the rocker arm against lateral movement and has a lower surface engaging the cylindrical fulcrum surface with a contact establishing a pure rolling motion without friction of the rocker arm upon the lash adjuster lower surface. A reciprocatingly mounted valve stem engages one end of the rocker arm for reciprocation of the valve. The other end of the rocker arm rotatably supports a dual function roller engagable with a cam lobe on the camshaft for arcuate pivoting of the rocker arm about its fulcrum upon rotation of the camshaft. Support means supports the roller for both an arcuate movement of its axis of rotation along a predetermined path providing a pure rolling motion of the rocker arm about its fulcrum upon the lash adjuster surface. This confines the roller and arm in a manner preventing a longitudinal sliding movement of the rocker arm fulcrum surface relative to the lash adjuster surface.

  6. Disk's Spiral Arms Point to Possible Planets

    NASA Video Gallery

    Simulations of young stellar systems suggest that planets embedded in a circumstellar disk can produce many distinctive structures, including rings, gaps and spiral arms. This video compares comput...

  7. Comparison of Smoking, Drinking, and Marijuana Use between Students Present or Absent on the Day of a School-Based Survey

    ERIC Educational Resources Information Center

    Bovet, Pascal; Viswanathan, Bharathi; Faeh, David; Warren, Wick

    2006-01-01

    The aim of this population-based survey was to compare the prevalence of selected risk behaviors between students present or absent on the day of a school-based survey. The study population was a representative sample of all students of secondary schools in the Seychelles (Indian Ocean). Students absent on the day of the survey were traced and…

  8. Here! But What about Those Who Are Not? Reinforcement among Chronically Absent Elementary Students, Its Effectiveness, and the Why behind the Absences

    ERIC Educational Resources Information Center

    Bickelhaupt, Delane L.

    2011-01-01

    This paper is a description of an action research (AR) study done with chronically absent elementary school students. The AR sought to answer these questions: 1) do reinforcement and daily check-ins increase attendance and 2) why are some students absent? Related literature regarding attendance and the methods used for the study are described and…

  9. Cortical Spiking Network Interfaced with Virtual Musculoskeletal Arm and Robotic Arm

    PubMed Central

    Dura-Bernal, Salvador; Zhou, Xianlian; Neymotin, Samuel A.; Przekwas, Andrzej; Francis, Joseph T.; Lytton, William W.

    2015-01-01

    Embedding computational models in the physical world is a critical step towards constraining their behavior and building practical applications. Here we aim to drive a realistic musculoskeletal arm model using a biomimetic cortical spiking model, and make a robot arm reproduce the same trajectories in real time. Our cortical model consisted of a 3-layered cortex, composed of several hundred spiking model-neurons, which display physiologically realistic dynamics. We interconnected the cortical model to a two-joint musculoskeletal model of a human arm, with realistic anatomical and biomechanical properties. The virtual arm received muscle excitations from the neuronal model, and fed back proprioceptive information, forming a closed-loop system. The cortical model was trained using spike timing-dependent reinforcement learning to drive the virtual arm in a 2D reaching task. Limb position was used to simultaneously control a robot arm using an improved network interface. Virtual arm muscle activations responded to motoneuron firing rates, with virtual arm muscles lengths encoded via population coding in the proprioceptive population. After training, the virtual arm performed reaching movements which were smoother and more realistic than those obtained using a simplistic arm model. This system provided access to both spiking network properties and to arm biophysical properties, including muscle forces. The use of a musculoskeletal virtual arm and the improved control system allowed the robot arm to perform movements which were smoother than those reported in our previous paper using a simplistic arm. This work provides a novel approach consisting of bidirectionally connecting a cortical model to a realistic virtual arm, and using the system output to drive a robotic arm in real time. Our techniques are applicable to the future development of brain neuroprosthetic control systems, and may enable enhanced brain-machine interfaces with the possibility for finer control of

  10. Cortical Spiking Network Interfaced with Virtual Musculoskeletal Arm and Robotic Arm.

    PubMed

    Dura-Bernal, Salvador; Zhou, Xianlian; Neymotin, Samuel A; Przekwas, Andrzej; Francis, Joseph T; Lytton, William W

    2015-01-01

    Embedding computational models in the physical world is a critical step towards constraining their behavior and building practical applications. Here we aim to drive a realistic musculoskeletal arm model using a biomimetic cortical spiking model, and make a robot arm reproduce the same trajectories in real time. Our cortical model consisted of a 3-layered cortex, composed of several hundred spiking model-neurons, which display physiologically realistic dynamics. We interconnected the cortical model to a two-joint musculoskeletal model of a human arm, with realistic anatomical and biomechanical properties. The virtual arm received muscle excitations from the neuronal model, and fed back proprioceptive information, forming a closed-loop system. The cortical model was trained using spike timing-dependent reinforcement learning to drive the virtual arm in a 2D reaching task. Limb position was used to simultaneously control a robot arm using an improved network interface. Virtual arm muscle activations responded to motoneuron firing rates, with virtual arm muscles lengths encoded via population coding in the proprioceptive population. After training, the virtual arm performed reaching movements which were smoother and more realistic than those obtained using a simplistic arm model. This system provided access to both spiking network properties and to arm biophysical properties, including muscle forces. The use of a musculoskeletal virtual arm and the improved control system allowed the robot arm to perform movements which were smoother than those reported in our previous paper using a simplistic arm. This work provides a novel approach consisting of bidirectionally connecting a cortical model to a realistic virtual arm, and using the system output to drive a robotic arm in real time. Our techniques are applicable to the future development of brain neuroprosthetic control systems, and may enable enhanced brain-machine interfaces with the possibility for finer control of

  11. Proprioceptive illusions created by vibration of one arm are altered by vibrating the other arm.

    PubMed

    Hakuta, Naoyuki; Izumizaki, Masahiko; Kigawa, Kazuyoshi; Murai, Norimitsu; Atsumi, Takashi; Homma, Ikuo

    2014-07-01

    There is some evidence that signals coming from both arms are used to determine the perceived position and movement of one arm. We examined whether the sense of position and movement of one (reference) arm is altered by increases in muscle spindle signals in the other (indicator) arm in blindfolded participants (n = 26). To increase muscle spindle discharge, we applied 70-80 Hz muscle vibration to the elbow flexors of the indicator arm. In a first experiment, proprioceptive illusions in the vibrated reference arm in a forearm position-matching task were compared between conditions in which the indicator arm elbow flexors were vibrated or not vibrated. We found that the vibration illusion of arm extension induced by vibration of reference arm elbow flexors was reduced in the presence of vibration of the indicator elbow flexors. In a second experiment, participants were asked to describe their perception of the illusion of forearm extension movements of the reference arm evoked by vibration of reference arm elbow flexors in response to on/off and off/on transitions of vibration of non-reference arm elbow flexors. When vibration of non-reference arm elbow flexors was turned on, they reported a sensation of slowing down of the illusion of the reference arm. When it was turned off, they reported a sensation of speeding up. To conclude, the present study shows that both the sense of limb position and the sense of limb movement of one arm are dependent to some extent on spindle signals coming from the other arm.

  12. Arm sway holds sway: locomotor-like modulation of leg reflexes when arms swing in alternation.

    PubMed

    Massaad, F; Levin, O; Meyns, P; Drijkoningen, D; Swinnen, S P; Duysens, J

    2014-01-31

    It has been argued that arm movements are important during human gait because they affect leg activity due to neural coupling between arms and legs. Consequently, one would expect that locomotor-like alternating arm swing is more effective than in-phase swing in affecting the legs' motor output. Other alternating movements such as trunk rotation associated to arm swing could also affect leg reflexes. Here, we assessed how locomotor-like movement patterns would affect soleus H-reflexes in 13 subjects performing arm swing in the sagittal plane (ipsilateral, contralateral and bilateral in-phase versus locomotor-like anti-phase arm movements) and trunk rotation with the legs stationary, and leg stepping with the arms stationary. Findings revealed that soleus H-reflexes were suppressed for all arm, trunk or leg movements. However, a marked reflex modulation occurred during locomotor-like anti-phase arm swing, as was also the case during leg stepping, and this modulation flattened out during in-phase arm swing. This modulation had a peculiar bell shape and showed maximum suppression at a moment where the heel-strike would occur during a normal walking cycle. Furthermore, this modulation was independent from electromyographic activity, suggesting a spinal processing at premotoneuronal level. Therefore, trunk movement can affect legs' output, and a special neural coupling occurs between arms and legs when arms move in alternation. This may have implications for gait rehabilitation.

  13. Films on the arms race

    SciTech Connect

    Dowling, J.

    1983-01-01

    Films convey the historical perspectives, the biographical stories, the insights of the participants, and the horror of nuclear war - far better than can any physicist. While films are not very efficient for covering details, derivation, or numbers, they can not be beaten in showing what really happens in a nuclear explosion, in getting across general concepts, in illustrating the parameters of a problem, and the problem itself. Most importantly, films and TV can reach the people who must be informed about these issues if we are to resolve the problems. The author points out how films can contribute to an understanding of the issues of the arms race and nuclear war, with references to specific films. An annotated bibliography of 37 films is then presented.

  14. Bare lymphocyte syndrome. Consequences of absent class II major histocompatibility antigen expression for B lymphocyte differentiation and function.

    PubMed Central

    Clement, L T; Plaeger-Marshall, S; Haas, A; Saxon, A; Martin, A M

    1988-01-01

    The bare lymphocyte syndrome is a rare combined immunodeficiency disorder associated with the absence of class I and/or class II major histocompatibility (MHC) antigens. Although it has been inferred that the immune deficiency is a consequence of disordered MHC-restricted interactions among otherwise normal cells, the biological capabilities and differentiation of B lymphocytes deficient in class II MHC antigens have not been rigorously analyzed. We have examined the phenotypic and functional attributes of B cells with absent class II MHC antigens. Our data demonstrate that these B cells are intrinsically defective in their responses to membrane-mediated activation stimuli. In addition, virtually all the B cells had phenotypic evidence of arrested differentiation at an immature stage. Finally, these B cells also failed to express the C3d-EBV receptor normally present on all B lymphocytes. These data indicate that class II MHC molecules are vital participants in early events of the B cell activation cascade, and that other non-MHC membrane molecules may also be absent as a consequence of either arrested differentiation or as a result of the basic defect affecting the expression of MHC membrane antigens. PMID:3257764

  15. Absent or compressed basal cisterns on first CT scan: ominous predictors of outcome in severe head injury.

    PubMed

    Toutant, S M; Klauber, M R; Marshall, L F; Toole, B M; Bowers, S A; Seelig, J M; Varnell, J B

    1984-10-01

    The relationship of outcome to the appearance of the basal cisterns as seen on initial computerized tomography (CT) scanning was assessed in 218 consecutive severely head-injured patients entered into the second phase of the National Pilot Traumatic Coma Data Bank. Outcome could be directly related to the status of the basal cisterns on the initial CT scan. The mortality rates were 77%, 39%, and 22% among those with absent, compressed, and normal basal cisterns, respectively. This association between cisterns and outcome was shown to be strong after adjusting for Glasgow Coma Scale (GCS) score (p less than 0.001). The state of the cisterns was more important for those with higher GCS scores (scores 6 to 8) than for those with lower scores (scores 3 to 5). Patients with GCS scores of 6 to 8, with cisterns absent or not visualized, suffered nearly a fourfold additional risk of poor outcome, compared to those with normal cisterns. This indicates that the status of the cisterns can be used as an early noninvasive method of identifying patients at high risk of death or severe disability, in whom the initial neurological examination would potentially suggest otherwise.

  16. Sensory-Feedback Exoskeletal Arm Controller

    NASA Technical Reports Server (NTRS)

    An, Bin; Massie, Thomas H.; Vayner, Vladimir

    2004-01-01

    An electromechanical exoskeletal arm apparatus has been designed for use in controlling a remote robotic manipulator arm. The apparatus, called a force-feedback exoskeleton arm master (F-EAM) is comfortable to wear and easy to don and doff. It provides control signals from the wearer s arm to a robot arm or a computer simulator (e.g., a virtual-reality system); it also provides force and torque feedback from sensors on the robot arm or from the computer simulator to the wearer s arm. The F-EAM enables the wearer to make the robot arm gently touch objects and finely manipulate them without exerting excessive forces. The F-EAM features a lightweight design in which the motors and gear heads that generate force and torque feedback are made smaller than they ordinarily would be: this is achieved by driving the motors to power levels greater than would ordinarily be used in order to obtain higher torques, and by providing active liquid cooling of the motors to prevent overheating at the high drive levels. The F-EAM (see figure) includes an assembly that resembles a backpack and is worn like a backpack, plus an exoskeletal arm mechanism. The FEAM has five degrees of freedom (DOFs) that correspond to those of the human arm: 1. The first DOF is that of the side-to-side rotation of the upper arm about the shoulder (rotation about axis 1). The reflected torque for this DOF is provided by motor 1 via drum 1 and a planar four-bar linkage. 2. The second DOF is that of the up-and-down rotation of the arm about the shoulder. The reflected torque for this DOF is provided by motor 2 via drum 2. 3. The third DOF is that of twisting of the upper arm about its longitudinal axis. This DOF is implemented in a cable remote-center mechanism (CRCM). The reflected torque for this DOF is provided by motor 3, which drives the upper-arm cuff and the mechanism below it. A bladder inflatable by gas or liquid is placed between the cuff and the wearer s upper arm to compensate for misalignment

  17. 31 CFR 543.301 - Arms or any related materiel.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Arms or any related materiel. 543.301... Definitions § 543.301 Arms or any related materiel. The term arms or any related materiel means arms or... of arms and related materiel and technical training and assistance intended solely for support of...

  18. 31 CFR 543.301 - Arms or any related materiel.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Arms or any related materiel. 543.301... Definitions § 543.301 Arms or any related materiel. The term arms or any related materiel means arms or... of arms and related materiel and technical training and assistance intended solely for support of...

  19. 31 CFR 543.301 - Arms or any related materiel.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Arms or any related materiel. 543.301... Definitions § 543.301 Arms or any related materiel. The term arms or any related materiel means arms or... of arms and related materiel and technical training and assistance intended solely for support of...

  20. 31 CFR 543.301 - Arms or any related materiel.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Arms or any related materiel. 543.301... Definitions § 543.301 Arms or any related materiel. The term arms or any related materiel means arms or... of arms and related materiel and technical training and assistance intended solely for support of...

  1. Effort, success, and nonuse determine arm choice.

    PubMed

    Schweighofer, Nicolas; Xiao, Yupeng; Kim, Sujin; Yoshioka, Toshinori; Gordon, James; Osu, Rieko

    2015-07-01

    How do humans choose one arm or the other to reach single targets in front of the body? Current theories of reward-driven decisionmaking predict that choice results from a comparison of "action values," which are the expected rewards for possible actions in a given state. In addition, current theories of motor control predict that in planning arm movements, humans minimize an expected motor cost that balances motor effort and endpoint accuracy. Here, we test the hypotheses that arm choice is determined by comparison of action values comprising expected effort and expected task success for each arm, as well as a handedness bias. Right-handed subjects, in either a large or small target condition, were first instructed to use each hand in turn to shoot through an array of targets and then to choose either hand to shoot through the same targets. Effort was estimated via inverse kinematics and dynamics. A mixed-effects logistic-regression analysis showed that, as predicted, both expected effort and expected success predicted choice, as did arm use in the preceding trial. Finally, individual parameter estimation showed that the handedness bias correlated with mean difference between right- and left-arm success, leading to overall lower use of the left arm. We discuss our results in light of arm nonuse in individuals' poststroke.

  2. Dual-arm manipulators with adaptive control

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun (Inventor)

    1991-01-01

    The described and improved multi-arm invention of this application presents three strategies for adaptive control of cooperative multi-arm robots which coordinate control over a common load. In the position-position control strategy, the adaptive controllers ensure that the end-effector positions of both arms track desired trajectories in Cartesian space despite unknown time-varying interaction forces exerted through a load. In the position-hybrid control strategy, the adaptive controller of one arm controls end-effector motions in the free directions and applied forces in the constraint directions; while the adaptive controller of the other arm ensures that the end-effector tracks desired position trajectories. In the hybrid-hybrid control strategy, the adaptive controllers ensure that both end-effectors track reference position trajectories while simultaneously applying desired forces on the load. In all three control strategies, the cross-coupling effects between the arms are treated as disturbances which are compensated for by the adaptive controllers while following desired commands in a common frame of reference. The adaptive controllers do not require the complex mathematical model of the arm dynamics or any knowledge of the arm dynamic parameters or the load parameters such as mass and stiffness. Circuits in the adaptive feedback and feedforward controllers are varied by novel adaptation laws.

  3. 78 FR 30731 - Armed Forces Day, 2013

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-22

    ... Documents#0;#0; ] Proclamation 8984 of May 17, 2013 Armed Forces Day, 2013 By the President of the United States of America A Proclamation Since the earliest days of our Union, America has been blessed with an..., liberty, and the pursuit of happiness. And on Armed Forces Day, we honor those who serve bravely...

  4. 75 FR 28185 - Armed Forces Day, 2010

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-20

    ...#0;#0; ] Proclamation 8522 of May 14, 2010 Armed Forces Day, 2010 By the President of the United... Armed Forces Day, we pay tribute to these patriots who risk their lives, sometimes giving their last... days of independence. Today, we have the greatest military force in the history of the world because...

  5. Why we cannot grow a human arm.

    PubMed

    Ricci, John L

    2013-11-01

    There are several significant issues that prevent us from growing a human arm now, or within the next 10-20 years. From a tissue engineering perspective, while we can grow many of the components necessary for construction of a human arm, we can only grow them in relatively small volumes, and when scaled up to large volumes we lack the ability to develop adequate blood/nerve supply. From a genetic engineering perspective, we will probably never be able to turn on the specific genes necessary to "grow an arm" unless it is attached to a fetus and this presents enormous ethical issues related to farming of human organs and structures. Perhaps the most daunting problem facing the transplantation of a tissue engineered or transplanted arm is that of re-innervation of the structure. Since the sensory and motor nerve cells of the arm are located outside of the structure, re-innervation requires those nerves to regenerate over relatively large distances to repopulate the nervous system of the arm. This is something with which we have had little success. We can grow repair parts, but "growing an arm" presents too many insurmountable problems. The best we could possibly do with tissue engineering or genetic engineering would be the equivalent of a fetal arm and the technical problems, costs, and ethical hurdles are enormous. A more likely solution is a functional, permanent, neuroelectronically-controlled prosthesis. These are nearly a reality today.

  6. 21 CFR 890.3640 - Arm sling.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Arm sling. 890.3640 Section 890.3640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3640 Arm sling. (a) Identification....

  7. 21 CFR 890.3640 - Arm sling.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Arm sling. 890.3640 Section 890.3640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3640 Arm sling. (a) Identification....

  8. 21 CFR 890.3640 - Arm sling.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Arm sling. 890.3640 Section 890.3640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3640 Arm sling. (a) Identification....

  9. Design of a biomimetic robotic octopus arm.

    PubMed

    Laschi, C; Mazzolai, B; Mattoli, V; Cianchetti, M; Dario, P

    2009-03-01

    This paper reports the rationale and design of a robotic arm, as inspired by an octopus arm. The octopus arm shows peculiar features, such as the ability to bend in all directions, to produce fast elongations, and to vary its stiffness. The octopus achieves these unique motor skills, thanks to its peculiar muscular structure, named muscular hydrostat. Different muscles arranged on orthogonal planes generate an antagonistic action on each other in the muscular hydrostat, which does not change its volume during muscle contractions, and allow bending and elongation of the arm and stiffness variation. By drawing inspiration from natural skills of octopus, and by analysing the geometry and mechanics of the muscular structure of its arm, we propose the design of a robot arm consisting of an artificial muscular hydrostat structure, which is completely soft and compliant, but also able to stiffen. In this paper, we discuss the design criteria of the robotic arm and how this design and the special arrangement of its muscular structure may bring the building of a robotic arm into being, by showing the results obtained by mathematical models and prototypical mock-ups.

  10. 21 CFR 890.3640 - Arm sling.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Arm sling. 890.3640 Section 890.3640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3640 Arm sling. (a) Identification....

  11. 21 CFR 890.3640 - Arm sling.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Arm sling. 890.3640 Section 890.3640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3640 Arm sling. (a) Identification....

  12. Teaching Undergraduates about Nuclear Arms and Strategy.

    ERIC Educational Resources Information Center

    Harrison, Michael J.

    1985-01-01

    Nuclear arms education is being addressed in many academic disciplines and can be approached from many viewpoints. Rationale, ethical issues, instructional strategies, European views, and course materials are considered. A syllabus and references are also included for a course titled "Physics of Nuclear Arms and Nuclear War." (DH)

  13. Research in lightweight elastic robotic arms

    NASA Astrophysics Data System (ADS)

    Nartker, T. A.

    1993-06-01

    The program involved a series of individual projects coordinated to develop controls for a flexible light weight robot arm. A hydraulically actuated 3-link robot arm was installed on a PRAB hydraulic base, and was designed of tubular steel. A PERT program chart was prepared (appendix B) on which various interrelated project milestones were projected.

  14. Whither the Third World Arms Producers?

    DTIC Science & Technology

    1987-01-01

    for 17 percent of the world arms market and 20 percent of the Third World market. The share of Third World arms exporters in 1984 reached almost 15...percent of the world market and about 18 percent of the Third World market. The present article examines these trends and some of their implications in greater detail.

  15. Small Arms Marksmanship Manual, NAVPERS 93863.

    ERIC Educational Resources Information Center

    Bureau of Naval Personnel, Washington, DC.

    The Navy's small arms marksmanship training program is designed to achieve proficiency for Navy personnel in handling the rifle, pistol andshotgun. The minimum objective of this program is to qualify Navy personnel as "Marksman," and ensure that personnel who are issued small arms for security, recreation, or competitions are fully qualified in…

  16. Kinematic analysis of 7 DOF anthropomorphic arms

    NASA Technical Reports Server (NTRS)

    Kreutz-Delgado, K.; Long, M.; Seraji, H.

    1990-01-01

    A kinematic analysis of anthropomorphic seven-degree-of-freedom serial link spatial manipulators with revolute joints is presented. To uniquely determine joint angles for a given end-effector position and orientation, the redundancy is parameterized by a scalar variable which corresponds to the angle between the arm plane and a reference plane. The forward kinematic mappings from joint-space to end-effector coordinates and arm angle and the augmented Jacobian matrix which gives end-effector and arm angle rates as functions of joint rates are given. Conditions under which the augmented Jacobian becomes singular are given and are shown to correspond to the arm being either at a kinematically singular configuration or at a nonsingular configuration for which the arm angle ceases to parameterize the redundancy.

  17. Anthropomorphic dual-arm space telemanipulation system

    NASA Technical Reports Server (NTRS)

    Jau, Bruno M.

    1990-01-01

    Dexterous dual-arm manipulations are feasible with the system described and illustrated in the paper. The structure is based on an extensible host arm that carries the dual-arm robot which comprises two 7-DOF arms each of which includes a hand with a thumb and three fingers with 4 DOF each. Joint compliance can be stiffened to any level, and the operator uses arm harnesses and gloves to utilize the robotics in an anthropomorphic fashion. The configuration eliminates coordinate-transformation computations, and the system is found to achieve a control-frequency rate of 1000 Hz for its direct man/machine interfaces based on fiber-optic cables. The electronics control for the system utilizes a sensory system consisting of force, position, and compliance sensors. The robotics system is expected to be a user-friendly device that permits assembly, repair, tethering, and other complex mechanical operations.

  18. Absent pulmonary valve

    MedlinePlus

    ... Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics . 20th ed. Philadelphia, PA: Elsevier; 2016:chap 428. ... Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics . 20th ed. Philadelphia, PA: Elsevier; 2016:chap 430. ...

  19. Leg automaticity is stronger than arm automaticity during simultaneous arm and leg cycling.

    PubMed

    Sakamoto, Masanori; Tazoe, Toshiki; Nakajima, Tsuyoshi; Endoh, Takashi; Komiyama, Tomoyoshi

    2014-04-03

    Recent studies indicate that human locomotion is quadrupedal in nature. An automatic rhythm-generating system is thought to play a crucial role in controlling arm and leg movements. In the present study, we attempted to elucidate differences between intrinsic arm and leg automaticity by investigating cadence variability during simultaneous arm and leg (AL) cycling. Participants performed AL cycling with visual feedback of arm or leg cadence. Participants were asked to focus their attention to match the predetermined cadence; this affects the automaticity of the rhythm-generating system. Leg cadence variability was only mildly affected when the participants intended to precisely adjust either their arm or leg cycling cadence to a predetermined value. In contrast, arm cadence variability significantly increased when the participants adjusted their leg cycling cadence to a predetermined value. These findings suggest that different neural mechanisms underlie the automaticities of arm and leg cycling and that the latter is stronger than the former during AL cycling.

  20. Rapid adaptation to Coriolis force perturbations of arm trajectory

    NASA Technical Reports Server (NTRS)

    Lackner, J. R.; Dizio, P.

    1994-01-01

    1. Forward reaching movements made during body rotation generate tangential Coriolis forces that are proportional to the cross product of the angular velocity of rotation and the linear velocity of the arm. Coriolis forces are inertial forces that do not involve mechanical contact. Virtually no constant centrifugal forces will be present in the background when motion of the arm generates transient Coriolis forces if the radius of body rotation is small. 2. We measured the trajectories of arm movements made in darkness to a visual target that was extinguished as movement began. The reaching movements were made prerotation, during rotation at 10 rpm in a fully enclosed rotating room, and postrotation. During testing the subject was seated at the center of the room and pointed radially. Neither visual nor tactile feedback about movement accuracy was present. 3. In experiment 1, subjects reached at a fast or slow rate and their hands made contact with a horizontal surface at the end of the reach. Their initial perrotary movements were highly significantly deviated relative to prerotation in both trajectories and end-points in the direction of the transient Coriolis forces that had been generated during the reaches. Despite the absence of visual and tactile feedback about reaching accuracy, all subjects rapidly regained straight movement trajectories and accurate endpoints. Postrotation, transient errors of opposite sign were present for both trajectories and endpoints. 4. In a second experiment the conditions were identical except that subjects pointed just above the location of the extinguished target so that no surface contact was involved. All subjects showed significant initial perrotation deviations of trajectories and endpoints in the direction of the transient Coriolis forces. With repeated reaches the trajectories, as viewed from above, again became straight, but there was only partial restoration of endpoint accuracy, so that subjects reached in a straight

  1. Rapid adaptation to Coriolis force perturbations of arm trajectory.

    PubMed

    Lackner, J R; Dizio, P

    1994-07-01

    1. Forward reaching movements made during body rotation generate tangential Coriolis forces that are proportional to the cross product of the angular velocity of rotation and the linear velocity of the arm. Coriolis forces are inertial forces that do not involve mechanical contact. Virtually no constant centrifugal forces will be present in the background when motion of the arm generates transient Coriolis forces if the radius of body rotation is small. 2. We measured the trajectories of arm movements made in darkness to a visual target that was extinguished as movement began. The reaching movements were made prerotation, during rotation at 10 rpm in a fully enclosed rotating room, and postrotation. During testing the subject was seated at the center of the room and pointed radially. Neither visual nor tactile feedback about movement accuracy was present. 3. In experiment 1, subjects reached at a fast or slow rate and their hands made contact with a horizontal surface at the end of the reach. Their initial perrotary movements were highly significantly deviated relative to prerotation in both trajectories and end-points in the direction of the transient Coriolis forces that had been generated during the reaches. Despite the absence of visual and tactile feedback about reaching accuracy, all subjects rapidly regained straight movement trajectories and accurate endpoints. Postrotation, transient errors of opposite sign were present for both trajectories and endpoints. 4. In a second experiment the conditions were identical except that subjects pointed just above the location of the extinguished target so that no surface contact was involved. All subjects showed significant initial perrotation deviations of trajectories and endpoints in the direction of the transient Coriolis forces. With repeated reaches the trajectories, as viewed from above, again became straight, but there was only partial restoration of endpoint accuracy, so that subjects reached in a straight

  2. Robotic Arm Comprising Two Bending Segments

    NASA Technical Reports Server (NTRS)

    Mehling, Joshua S.; Difler, Myron A.; Ambrose, Robert O.; Chu, Mars W.; Valvo, Michael C.

    2010-01-01

    The figure shows several aspects of an experimental robotic manipulator that includes a housing from which protrudes a tendril- or tentacle-like arm 1 cm thick and 1 m long. The arm consists of two collinear segments, each of which can be bent independently of the other, and the two segments can be bent simultaneously in different planes. The arm can be retracted to a minimum length or extended by any desired amount up to its full length. The arm can also be made to rotate about its own longitudinal axis. Some prior experimental robotic manipulators include single-segment bendable arms. Those arms are thicker and shorter than the present one. The present robotic manipulator serves as a prototype of future manipulators that, by virtue of the slenderness and multiple- bending capability of their arms, are expected to have sufficient dexterity for operation within spaces that would otherwise be inaccessible. Such manipulators could be especially well suited as means of minimally invasive inspection during construction and maintenance activities. Each of the two collinear bending arm segments is further subdivided into a series of collinear extension- and compression-type helical springs joined by threaded links. The extension springs occupy the majority of the length of the arm and engage passively in bending. The compression springs are used for actively controlled bending. Bending is effected by means of pairs of antagonistic tendons in the form of spectra gel spun polymer lines that are attached at specific threaded links and run the entire length of the arm inside the spring helix from the attachment links to motor-driven pulleys inside the housing. Two pairs of tendons, mounted in orthogonal planes that intersect along the longitudinal axis, are used to effect bending of each segment. The tendons for actuating the distal bending segment are in planes offset by an angle of 45 from those of the proximal bending segment: This configuration makes it possible to

  3. Anti-satellite weapons, countermeasures, and arms control

    NASA Astrophysics Data System (ADS)

    1985-09-01

    Anti-satellite weapons, countermeasures, and arms control; MILSATs, ASATs, and national security; ASAT capabilities and countermeasures; ASAT arms control: history; ASAT arms control: options; and a comparative evaluation of ASAT policy options are discussed.

  4. Characterization of the first intragenic SATB2 duplication in a girl with intellectual disability, nearly absent speech and suspected hypodontia.

    PubMed

    Kaiser, Ann-Sophie; Maas, Bianca; Wolff, Anna; Sutter, Christian; Janssen, Johannes W G; Hinderhofer, Katrin; Moog, Ute

    2015-05-01

    SATB2, a gene encoding a highly conserved DNA-binding protein, is known to have an important role in craniofacial and neuronal development. Only a few patients with SATB2 variants have been described so far. Recently, Döcker et al provided a summary of these patients and delineated the SAS (SATB2-associated syndrome). We here report on a girl with intellectual disability, nearly absent speech and suspected hypodontia who was shown to carry an intragenic SATB2 tandem duplication hypothesized to lead to haploinsufficiency of SATB2. Preliminary information on this patient had already been included in the article by Döcker et al. We want to give a detailed description of the patient's phenotype and genotype, providing further insight into the spectrum of the molecular mechanisms leading to SAS.

  5. Vestibular responses to linear acceleration are absent in otoconia-deficient C57BL/6JEi-het mice

    NASA Technical Reports Server (NTRS)

    Jones, S. M.; Erway, L. C.; Bergstrom, R. A.; Schimenti, J. C.; Jones, T. A.

    1999-01-01

    Vestibular evoked potentials (VsEPs) were measured in normal mice and in mice homozygous for the head tilt mutation (het/het, abbr. het). The het mice lack otoconia, the inertial mass critical for natural stimulation of inner ear gravity receptors. Our findings demonstrate that vestibular neural responses to pulsed linear acceleration are absent in het mice. The results: (1) confirm that adequate sensory stimuli fail to activate gravity receptors in the het model; and (2) serve as definitive evidence that far-field vestibular responses to pulsed linear acceleration depend critically on otolith end organs. The C57BL/6JEi-het mouse may be an excellent model of gravity receptor sensory deprivation.

  6. Rare Site of Parasitic Dermoid Cyst at Uterovesical Fold of Peritoneum with Absent One-Sided Adnexa

    PubMed Central

    Sehgal, Alka; Ballega, Puneeti; Punia, RPS

    2016-01-01

    Teratomas are the most common type of germ cell tumour. It can be congenital or acquired and are usually found in gonads (testes and ovaries). Parasitic dermoid cysts are rare and their actual incidence is unknown. We are reporting a case of 25-year-old gravida two, para one and one living child, who underwent emergency cesarean section in view of symptomatic placenta previa. A parasitic dermoid cyst was found incidently in front of uterus which was attached to uterovasical fold of bladder. This cyst did not show any connection to uterus or adnexa. Uterus, uterine cavity, right side tube and ovary were normal. Her left sided fallopian tube and ovary was completely absent. She did not have any symptoms related to the dermoid cyst. Histopathology confirmed parasitic mature dermoid cyst. PMID:28208952

  7. Rare Site of Parasitic Dermoid Cyst at Uterovesical Fold of Peritoneum with Absent One-Sided Adnexa.

    PubMed

    Dubey, Sunita; Sehgal, Alka; Ballega, Puneeti; Punia, Rps

    2016-12-01

    Teratomas are the most common type of germ cell tumour. It can be congenital or acquired and are usually found in gonads (testes and ovaries). Parasitic dermoid cysts are rare and their actual incidence is unknown. We are reporting a case of 25-year-old gravida two, para one and one living child, who underwent emergency cesarean section in view of symptomatic placenta previa. A parasitic dermoid cyst was found incidently in front of uterus which was attached to uterovasical fold of bladder. This cyst did not show any connection to uterus or adnexa. Uterus, uterine cavity, right side tube and ovary were normal. Her left sided fallopian tube and ovary was completely absent. She did not have any symptoms related to the dermoid cyst. Histopathology confirmed parasitic mature dermoid cyst.

  8. The evolution of neuroArm.

    PubMed

    Sutherland, Garnette R; Wolfsberger, Stefan; Lama, Sanju; Zarei-nia, Kourosh

    2013-01-01

    Intraoperative imaging disrupts the rhythm of surgery despite providing an excellent opportunity for surgical monitoring and assessment. To allow surgery within real-time images, neuroArm, a teleoperated surgical robotic system, was conceptualized. The objective was to design and manufacture a magnetic resonance-compatible robot with a human-machine interface that could reproduce some of the sight, sound, and touch of surgery at a remote workstation. University of Calgary researchers worked with MacDonald, Dettwiler and Associates engineers to produce a requirements document, preliminary design review, and critical design review, followed by the manufacture, preclinical testing, and clinical integration of neuroArm. During the preliminary design review, the scope of the neuroArm project changed to performing microsurgery outside the magnet and stereotaxy inside the bore. neuroArm was successfully manufactured and installed in an intraoperative magnetic resonance imaging operating room. neuroArm was clinically integrated into 35 cases in a graded fashion. As a result of this experience, neuroArm II is in development, and advances in technology will allow microsurgery within the bore of the magnet. neuroArm represents a successful interdisciplinary collaboration. It has positive implications for the future of robotic technology in neurosurgery in that the precision and accuracy of robots will continue to augment human capability.

  9. Collecting Survey Data during Armed Conflict

    PubMed Central

    Axinn, William G.; Ghimire, Dirgha; Williams, Nathalie E.

    2012-01-01

    Surveys provide crucial information about the social consequences of armed conflict, but armed conflict can shape surveys in ways that limit their value. We use longitudinal survey data from throughout the recent armed conflict in Nepal to investigate the relationship between armed conflict events and survey response. The Chitwan Valley Family Study (CVFS) provides a rare window into survey data collection through intense armed conflict. The CVFS data reveal that with operational strategies tailored to the specific conflict, duration of the panel study is the main determinant of attrition from the study, just as in most longitudinal studies outside of conflict settings. Though minor relative to duration, different dimensions of armed conflict can affect survey response in opposing directions, with bombings in the local area reducing response rates but nationwide political events increasing response rates. This important finding demonstrates that survey data quality may be affected differently by various dimensions of armed conflict. Overall, CVFS response rates remained exceptionally high throughout the conflict. We use the CVFS experience to identify principles likely to produce higher quality surveys during periods of generalized violence and instability. PMID:23420645

  10. Is Negotiated Arms Control Possible?

    NASA Astrophysics Data System (ADS)

    Panofsky, W. K. H.

    2014-11-01

    I had a very difficult time deciding on the topic of this talk, since Viki's interests cover such a broad range of activities with which I am also concerned. You can hear next week about the recent exciting work with the SLAC storage rings, a description of the design principles of such rings, and their future promise for new physics through Professor Richter's Loeb Lectures at Harvard. Talking about inelastic lepton scattering during an M.I.T. conference would be bringing coals to Newcastle, since the local M.I.T. physicists are primary agents in these experiments. Broad problems in high energy physics policy, for instance such questions as the relation between University users and the large laboratories, are matters of current concern to Viki and his friends in high energy physics, but I doubt whether many would sit still for a one-hour talk on that subject. I would therefore like to use the opportunity to express some personal views on certain current issues in arms control, since I know that there exists a wide spectrum of involvement and also opinion on this subject in the local community...

  11. The arms race between fishers

    NASA Astrophysics Data System (ADS)

    Rijnsdorp, Adriaan D.; Poos, Jan Jaap; Quirijns, Floor J.; HilleRisLambers, Reinier; De Wilde, Jan W.; Den Heijer, Willem M.

    An analysis of the changes in the Dutch demersal fishing fleet since the 1950s revealed that competitive interactions among vessels and gear types within the constraints imposed by biological, economic and fisheries management factors are the dominant processes governing the dynamics of fishing fleets. Double beam trawling, introduced in the early 1960s, proved a successful fishing method to catch deep burying flatfish, in particular sole. In less than 10 years, the otter trawl fleet was replaced by a highly specialised beam trawling fleet, despite an initial doubling of the loss rate of vessels due to stability problems. Engine power, size of the beam trawl, number of tickler chains and fishing speed rapidly increased and fishing activities expanded into previously lightly fished grounds and seasons. Following the ban on flatfish trawling within the 12 nautical mile zone for vessels of more than 300 hp in 1975 and with the restriction of engine power to 2000 hp in 1987, the beam trawl fleet bifurcated. Changes in the fleet capacity were related to the economic results and showed a cyclic pattern with a period of 6-7 years. The arms race between fishers was fuelled by competitive interactions among fishers: while the catchability of the fleet more than doubled in the ten years following the introduction of the beam trawl, a decline in catchability was observed in reference beam trawlers that remained the same. Vessel performance was not only affected by the technological characteristics but also by the number and characteristics of competing vessels.

  12. Kinesin-2 motors transport IFT-particles, dyneins and tubulin subunits to the tips of Caenorhabditis elegans sensory cilia: relevance to vision research?

    PubMed

    Scholey, Jonathan M

    2012-12-15

    The sensory outer segments (OS) of vertebrate retinal photoreceptors, which detect photons of light, resemble the distal segments of Caenorhabditis elegans sensory cilia, which detect chemical ligands that influence the chemotactic movements of the animal. Based on fluorescence microscopy assays performed in sensory cilia of living, transgenic "wild type" and mutant C. elegans, combined with in vitro motility assays using purified motors, we have proposed that two types of kinesin-2 motor, heterotrimeric kinesin-II and homodimeric OSM-3, cooperate to build amphid and phasmid sensory cilia on chemosensory neurons. Specifically, we propose that these motors function together in a redundant manner to build the axoneme core (aka middle segments (MS)), whereas OSM-3 alone serves to build the distal segments (DS). Furthermore, our data suggest that these motors accomplish this by driving two sequential steps of anterograde transport of cargoes consisting of IFT-particles, retrograde dynein motors, and ciliary tubulin subunits, from the transition zone to the tips of the axonemal microtubules (MTs). Homologs of kinesin-II (KIF3) and OSM-3 (KIF17) are also proposed to contribute to the assembly of vertebrate photoreceptors, although how they do so is currently unclear. Here I review our work on kinesin-2 motors, intraflagellar transport (IFT) and cilium biogenesis in C. elegans sensory cilia, and comment on its possible relevance to current research on vertebrate photoreceptor cilia assembly and function.

  13. Cyclin B3 and dynein heavy chain cooperate to increase fitness in the absence of mdf-1/MAD1 in Caenorhabditis elegans.

    PubMed

    Tarailo-Graovac, Maja; Wong, Tammy; Qin, Zhaozhao; Flibotte, Stephane; Taylor, Jon; Moerman, Donald G; Rose, Ann M; Chen, Nansheng

    2014-01-01

    Spindle assembly checkpoint (SAC) ensures genome stability by delaying anaphase onset until all the chromosomes have achieved proper spindle attachment. Once correct attachment has been achieved, SAC must be silenced. In the absence of mdf-1/MAD1, an essential SAC component, Caenorhabditis elegans cannot propagate beyond 3 generations. Previously, in a dog-1(gk10)/FANCJ mutator background, we isolated a suppressor of mdf-1(gk2) sterility (such-4) which allowed indefinite propagation in the absence of MDF-1. We showed that such-4 is a Cyclin B3 (cyb-3) duplication. Here we analyze mdf-1 such-4; dog-1, which we propagated for 470 generations, with freezing of samples for long time storage at F170 and F270. Phenotypic analysis of this strain revealed additional suppression of sterility in the absence of MDF-1, beyond the effects of such-4. We applied oligonucleotide array Comparative Genomic Hybridization (oaCGH) and whole genome sequencing (WGS) and identified a further amplification of cyb-3 (triplication) and a new missense mutation in dynein heavy chain (dhc-1). We show that dhc-1(dot168) suppresses the mdf-1(gk2), and is the second cloned suppressor, next to cyb-3 duplication, that does not cause a delay in anaphase onset. We also show that amplification of cyb-3 and dhc-1(dot168) cooperate to increase fitness in the absence of MDF-1.

  14. Rab5 and its effector FHF contribute to neuronal polarity through dynein-dependent retrieval of somatodendritic proteins from the axon

    PubMed Central

    Guo, Xiaoli; Farías, Ginny G.; Mattera, Rafael; Bonifacino, Juan S.

    2016-01-01

    An open question in cell biology is how the general intracellular transport machinery is adapted to perform specialized functions in polarized cells such as neurons. Here we illustrate this adaptation by elucidating a role for the ubiquitous small GTPase Ras-related protein in brain 5 (Rab5) in neuronal polarity. We show that inactivation or depletion of Rab5 in rat hippocampal neurons abrogates the somatodendritic polarity of the transferrin receptor and several glutamate receptor types, resulting in their appearance in the axon. This loss of polarity is not caused primarily by increased transport from the soma to the axon but rather by decreased retrieval from the axon to the soma. Retrieval is also dependent on the Rab5 effector Fused Toes (FTS)–Hook–FTS and Hook-interacting protein (FHIP) (FHF) complex, which interacts with the minus-end–directed microtubule motor dynein and its activator dynactin to drive a population of axonal retrograde carriers containing somatodendritic proteins toward the soma. These findings emphasize the importance of both biosynthetic sorting and axonal retrieval for the polarized distribution of somatodendritic receptors at steady state. PMID:27559088

  15. Method of making a rocker arm

    SciTech Connect

    Taniguchi, M.; Kawamura, M.; Ishida, N.; Ito, M.

    1989-06-27

    A method of producing a rocker arm is described, comprising: forming a rocker arm having a valve contacting portion, a cam contacting portion and a pivot portion for contact with a pivot of a lash adjuster and entirely made of ceramics; processing the rocker arm by barrel finishing; and; grinding the pivot portion by using the valve contacting portion and the cam contacting portion as datum surfaces and thereby locating the pivot portion in position relative to the valve contacting portion and the cam contacting portion.

  16. Multiple caliper arms capable of independent movement

    SciTech Connect

    Deaton, J.G.

    1992-02-11

    This patent describes a multiple arm caliper tool system for use in a well borehole. It comprises: an elongate tool body that adapted to be lowered and retrieved along a well borehole; at least a pari of caliper arms, each of the arms being a piston isolating the chamber; and means for compressing the hydraulic fluid within the chamber so that hydraulic fluid in the chamber is brought to a specified pressure wherein the hydraulic fluid acts on all of the push rods extending into the chamber.

  17. ARM Climate Research Facility Annual Report 2005

    SciTech Connect

    J. Voyles

    2005-12-31

    Through the ARM Program, the DOE funded the development of several highly instrumented ground stations for studying cloud formation processes and their influence on radiative transfer, and for measuring other parameters that determine the radiative properties of the atmosphere. This scientific infrastructure, and resultant data archive, is a valuable national and international asset for advancing scientific knowledge of Earth systems. In fiscal year (FY) 2003, the DOE designated ARM sites as a national scientific user facility: the ARM Climate Research (ACRF). The ACRF has enormous potential to contribute to a wide range interdisciplinary science in areas such as meteorology, atmospheric aerosols, hydrology, biogeochemical cycling, and satellite validation, to name only a few.

  18. Robot arm dynamic model reduction for control

    NASA Technical Reports Server (NTRS)

    Bejczy, A. K.; Lee, S.

    1983-01-01

    General methods are described by which the mathematical complexities of explicit and exact state equations of robot arms can be reduced to a simplified and compact state equation representation without introducing significant errors into the robot arm dynamic model. The model reduction methods are based on homogeneous coordinates and on the Langrangian algorithm for robot arm dynamics, and utilize matrix, vector and numeric analysis techniques. The derivation of differential vector representation of centripetal and Coriolis forces which has not yet been established in the literature is presented.

  19. Bullying and the UK Armed Forces.

    PubMed

    Coetzee, R H; Atkins, S; Gould, M

    2012-06-01

    There are certain characteristics of the culture and environment in the Armed Forces that may be conducive to bullying. In this article we examine the cultural and environmental factors that may encourage such behaviour and those that act as deterrents for victims to come forward. We will look at the scope of this problem within the UK Armed Forces specifically, before more generally considering the psychological impact of bullying. There appears to be an overall downward trend in bullying within the UK Armed Forces and a positive increase in complaints as more victims step forward. We conclude by highlighting some areas for further development.

  20. [Acute ischemia of an arm as an unusual manifestation of ergotism].

    PubMed

    Heinz, M; Theiss, W; Golder, W; Schömig, A

    1994-11-04

    A 27-year-old woman developed acute pain, pallor and feeling of cold in her left arm. She had been a smoker of 15-20 cigarettes daily since the age of 15 years, but had not previously had any serious illness. In addition to contraceptives she had had been taking one to several suppositories containing caffeine and ergotamine tartrate (2 mg) daily against migraine. Angiological examination 5 days after onset of symptoms discovered a weak brachial pulse low in the left upper arm, while ulnar and radial pulses were absent. All other pulses were normally palpable. Colour duplex sonography demonstrated occlusion of the brachial artery which angiographically was due to a 5 cm severe narrowing without thrombus, blood flowing distally via collaterals. No improvement was achieved by local injection of 100,000 IU urokinase, 0.5 mg nitroglycerin, 20 mg tolazoline and a 3-hour infusion of alprostadil. On infusion of 560 ml hydroxyethylstarch over 8 hours, 400 mg naftidrofuryl, therapeutic doses of heparin and abstinence from ergotamine (since admission) the vessel diameter increased by 50% within 23 hours and after a further 24 hours to almost 100% of the comparable arterial segment of the right arm while merely on heparin infusion.