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  1. Article ; Online: Planar cell polarity

    José Casal / Freya Storer / Peter A. Lawrence

    Open Biology, Vol 13, Iss

    intracellular asymmetry and supracellular gradients of Frizzled

    2023  Volume 6

    Abstract: Planar cell polarity (PCP), the coordinated orientation of structures such as cilia, mammalian hairs or insect bristles, depends on at least two molecular systems. We have argued that these two systems use similar mechanisms; each depending on a ... ...

    Abstract Planar cell polarity (PCP), the coordinated orientation of structures such as cilia, mammalian hairs or insect bristles, depends on at least two molecular systems. We have argued that these two systems use similar mechanisms; each depending on a supracellular gradient of concentration that spans a field of cells. In a linked paper, we studied the Dachsous/Fat system. We found a graded distribution of Dachsous in vivo in a segment of the pupal epidermis in the abdomen of Drosophila. Here we report a similar study of the key molecule for the Starry Night/Frizzled or ‘core’ system. We measure the distribution of the receptor Frizzled on the cell membranes of all cells of one segment in the living pupal abdomen of Drosophila. We find a supracellular gradient that falls about 17% in concentration from the front to the rear of the segment. We present some evidence that the gradient then resets in the most anterior cells of the next segment back. We find an intracellular asymmetry in all the cells, the posterior membrane of each cell carrying about 22% more Frizzled than the anterior membrane. These direct molecular measurements add to earlier evidence that the two systems of PCP act independently.
    Keywords Frizzled ; gradients ; planar cell polarity ; Biology (General) ; QH301-705.5
    Subject code 612
    Language English
    Publishing date 2023-06-01T00:00:00Z
    Publisher The Royal Society
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Planar cell polarity

    Adrià Chorro / Bhavna Verma / Maylin Homfeldt / Beatríz Ibáñez / Peter A. Lawrence / José Casal

    Open Biology, Vol 12, Iss

    intracellular asymmetry and supracellular gradients of Dachsous

    2022  Volume 10

    Abstract: The slope of a supracellular molecular gradient has long been thought to orient and coordinate planar cell polarity (PCP). Here we demonstrate and measure that gradient. Dachsous (Ds) is a conserved and elemental molecule of PCP; Ds forms intercellular ... ...

    Abstract The slope of a supracellular molecular gradient has long been thought to orient and coordinate planar cell polarity (PCP). Here we demonstrate and measure that gradient. Dachsous (Ds) is a conserved and elemental molecule of PCP; Ds forms intercellular bridges with another cadherin molecule, Fat (Ft), an interaction modulated by the Golgi protein Four-jointed (Fj). Using genetic mosaics and tagged Ds, we measure Ds in vivo in membranes of individual cells over a whole metamere of the Drosophila abdomen. We find as follows. (i) A supracellular gradient rises from head to tail in the anterior compartment (A) and then falls in the posterior compartment (P). (ii) There is more Ds in the front than the rear membranes of all cells in the A compartment, except that compartment's most anterior and most posterior cells. There is more Ds in the rear than in the front membranes of all cells of the P compartment. (iii) The loss of Fj removes intracellular asymmetry anteriorly in the segment and reduces it elsewhere. Additional experiments show that Fj makes PCP more robust. Using Dachs (D) as a molecular indicator of polarity, we confirm that opposing gradients of PCP meet slightly out of register with compartment boundaries.
    Keywords asymmetry ; planar cell polarity ; Dachs ; Four-jointed ; gradient ; Fat ; Biology (General) ; QH301-705.5
    Subject code 612
    Language English
    Publishing date 2022-10-01T00:00:00Z
    Publisher The Royal Society
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Planar cell polarity in the larval epidermis of Drosophila and the role of microtubules

    Stefano Pietra / KangBo Ng / Peter A. Lawrence / José Casal

    Open Biology, Vol 10, Iss

    2020  Volume 12

    Abstract: We investigate planar cell polarity (PCP) in the Drosophila larval epidermis. The intricate pattern of denticles depends on only one system of PCP, the Dachsous/Fat system. Dachsous molecules in one cell bind to Fat molecules in a neighbour cell to make ... ...

    Abstract We investigate planar cell polarity (PCP) in the Drosophila larval epidermis. The intricate pattern of denticles depends on only one system of PCP, the Dachsous/Fat system. Dachsous molecules in one cell bind to Fat molecules in a neighbour cell to make intercellular bridges. The disposition and orientation of these Dachsous–Fat bridges allows each cell to compare two neighbours and point its denticles towards the neighbour with the most Dachsous. Measurements of the amount of Dachsous reveal a peak at the back of the anterior compartment of each segment. Localization of Dachs and orientation of ectopic denticles help reveal the polarity of every cell. We discuss whether these findings support our gradient model of Dachsous activity. Several groups have proposed that Dachsous and Fat fix the direction of PCP via oriented microtubules that transport PCP proteins to one side of the cell. We test this proposition in the larval cells and find that most microtubules grow perpendicularly to the axis of PCP. We find no meaningful bias in the polarity of microtubules aligned close to that axis. We also reexamine published data from the pupal abdomen and find no evidence supporting the hypothesis that microtubular orientation draws the arrow of PCP.
    Keywords planar cell polarity ; microtubules ; dachsous ; fat ; ovo ; dachs ; Biology (General) ; QH301-705.5
    Subject code 612
    Language English
    Publishing date 2020-12-01T00:00:00Z
    Publisher The Royal Society
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: A refutation to ‘A new A-P compartment boundary and organizer in holometabolous insect wings’

    Peter A. Lawrence / José Casal / José F. de Celis / Ginés Morata

    Scientific Reports, Vol 9, Iss 1, Pp 1-

    2019  Volume 6

    Abstract: Abstract We respond to a recent report by Abbasi and Marcus who present two main findings: first they argue that there is an organiser and a compartment boundary within the posterior compartment of the butterfly wing. Second, they present evidence for a ... ...

    Abstract Abstract We respond to a recent report by Abbasi and Marcus who present two main findings: first they argue that there is an organiser and a compartment boundary within the posterior compartment of the butterfly wing. Second, they present evidence for a previously undiscovered lineage boundary near wing vein 5 in Drosophila, a boundary that delineates a “far posterior” compartment. Clones of cells were marked with the yellow mutation and they reported that these clones always fail to cross a line close to vein 5 on the Drosophila wing. In our hands yellow proved an unusable marker for clones in the wing blade and therefore we reexamined the matter. We marked clones of cells with multiple wing hairs or forked and found a substantial proportion of these clones cross the proposed lineage boundary near vein 5, in conflict with their findings and conclusion. As internal controls we showed that these same clones respect the other two well established compartment boundaries: the anteroposterior compartment boundary is always respected. The dorsoventral boundary is mostly respected, and is crossed only by clones that are induced early in development, consistent with many reports. We question the validity of Abbasi and Marcus’ conclusions regarding the butterfly wing but present no new data. Arising from: R. Abbasi and J. M. Marcus Sci. Rep. 7, 16337 (2017); https://doi.org/10.1038/s41598-017-16553-5.
    Keywords Medicine ; R ; Science ; Q
    Subject code 590
    Language English
    Publishing date 2019-05-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Real lives and white lies in the funding of scientific research

    Peter A Lawrence

    PLoS Biology, Vol 7, Iss 9, p e

    the granting system turns young scientists into bureaucrats and then betrays them.

    2009  Volume 1000197

    Keywords Biology (General) ; QH301-705.5
    Language English
    Publishing date 2009-09-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Men, women, and ghosts in science.

    Peter A Lawrence

    PLoS Biology, Vol 4, Iss 1, p e

    2006  Volume 19

    Keywords Biology (General) ; QH301-705.5
    Language English
    Publishing date 2006-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Regions within a single epidermal cell of Drosophila can be planar polarised independently

    Miguel Rovira / Pedro Saavedra / José Casal / Peter A Lawrence

    eLife, Vol

    2015  Volume 4

    Abstract: Planar cell polarity (PCP), the coordinated and consistent orientation of cells in the plane of epithelial sheets, is a fundamental and conserved property of animals and plants. Up to now, the smallest unit expressing PCP has been considered to be an ... ...

    Abstract Planar cell polarity (PCP), the coordinated and consistent orientation of cells in the plane of epithelial sheets, is a fundamental and conserved property of animals and plants. Up to now, the smallest unit expressing PCP has been considered to be an entire single cell. We report that, in the larval epidermis of Drosophila, different subdomains of one cell can have opposite polarities. In larvae, PCP is driven by the Dachsous/Fat system; we show that the polarity of a subdomain within one cell is its response to levels of Dachsous/Fat in the membranes of contacting cells. During larval development, cells rearrange (Saavedra et al., 2014) and when two subdomains of a single cell have different types of neighbouring cells, then these subdomains can become polarised in opposite directions. We conclude that polarisation depends on a local comparison of the amounts of Dachsous and Fat within opposing regions of a cell's membrane.
    Keywords morphogen ; planar cell polarity ; dachsous ; fat ; four-jointed ; gradients ; Medicine ; R ; Science ; Q ; Biology (General) ; QH301-705.5
    Subject code 612
    Language English
    Publishing date 2015-02-01T00:00:00Z
    Publisher eLife Sciences Publications Ltd
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Planar cell polarity

    Pedro Saavedra / Amy Brittle / Isabel M. Palacios / David Strutt / José Casal / Peter A. Lawrence

    Biology Open, Vol 5, Iss 4, Pp 397-

    the Dachsous/Fat system contributes differently to the embryonic and larval stages of Drosophila

    2016  Volume 408

    Abstract: The epidermal patterns of all three larval instars (L1–L3) of Drosophila are made by one unchanging set of cells. The seven rows of cuticular denticles of all larval stages are consistently planar polarised, some pointing forwards, others backwards. In ... ...

    Abstract The epidermal patterns of all three larval instars (L1–L3) of Drosophila are made by one unchanging set of cells. The seven rows of cuticular denticles of all larval stages are consistently planar polarised, some pointing forwards, others backwards. In L1 all the predenticles originate at the back of the cells but, in L2 and L3, they form at the front or the back of the cell depending on the polarity of the forthcoming denticles. We find that, to polarise all rows, the Dachsous/Fat system is differentially utilised; in L1 it is active in the placement of the actin-based predenticles but is not crucial for the final orientation of the cuticular denticles, in L2 and L3 it is needed for placement and polarity. We find Four-jointed to be strongly expressed in the tendon cells and show how this might explain the orientation of all seven rows. Unexpectedly, we find that L3 that lack Dachsous differ from larvae lacking Fat and we present evidence that this is due to differently mislocalised Dachs. We make some progress in understanding how Dachs contributes to phenotypes of wildtype and mutant larvae and adults.
    Keywords Dachs ; Dachsous ; Fat ; Epidermis ; Planar cell polarity ; Science ; Q ; Biology (General) ; QH301-705.5
    Language English
    Publishing date 2016-04-01T00:00:00Z
    Publisher The Company of Biologists
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Plasticity of both planar cell polarity and cell identity during the development of Drosophila

    Pedro Saavedra / Jean-Paul Vincent / Isabel M Palacios / Peter A Lawrence / José Casal

    eLife, Vol

    2014  Volume 3

    Abstract: Drosophila has helped us understand the genetic mechanisms of pattern formation. Particularly useful have been those organs in which different cell identities and polarities are displayed cell by cell in the cuticle and epidermis (Lawrence, 1992; ... ...

    Abstract Drosophila has helped us understand the genetic mechanisms of pattern formation. Particularly useful have been those organs in which different cell identities and polarities are displayed cell by cell in the cuticle and epidermis (Lawrence, 1992; Bejsovec and Wieschaus, 1993; Freeman, 1997). Here we use the pattern of larval denticles and muscle attachments and ask how this pattern is maintained and renewed over the larval moult cycles. During larval growth each epidermal cell increases manyfold in size but neither divides nor dies. We follow individuals from moult to moult, tracking marked cells and find that, as cells are repositioned and alter their neighbours, their identities change to compensate and the pattern is conserved. Single cells adopting a new fate may even acquire a new polarity: an identified cell that makes a forward-pointing denticle in the first larval stage may make a backward-pointing denticle in the second and third larval stages.
    Keywords planar cell polarity ; pattern ; denticle ; convergent extension ; Drosophila ; Medicine ; R ; Science ; Q ; Biology (General) ; QH301-705.5
    Subject code 612
    Language English
    Publishing date 2014-02-01T00:00:00Z
    Publisher eLife Sciences Publications Ltd
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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