Left‐right asymmetry in gut development: what happens next?

Burn, Sally F.; Hill, Robert E.

doi:10.1002/bies.200900056

Cited by 23 publications

(27 citation statements)

References 98 publications

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“…The many problems associated with intestinal malrotation in humans, which has been estimated to occur in as many as 1/500 births, support this reasoning (Burn and Hill, 2009;Stewart et al, 1976;Sutherland and Ware, 2009). …”

Section: Box 1 Phylogenetic Tree Of the Major Animal Cladesmentioning

confidence: 97%

The evolution and conservation of left-right patterning mechanisms

et al. 2014

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Morphological asymmetry is a common feature of animal body plans, from shell coiling in snails to organ placement in humans. The signaling protein Nodal is key for determining this laterality. Many vertebrates, including humans, use cilia for breaking symmetry during embryonic development: rotating cilia produce a leftward flow of extracellular fluids that induces the asymmetric expression of Nodal. By contrast, Nodal asymmetry can be induced flow-independently in invertebrates. Here, we ask when and why flow evolved. We propose that flow was present at the base of the deuterostomes and that it is required to maintain organ asymmetry in otherwise perfectly bilaterally symmetrical vertebrates.

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Section: Box 1 Phylogenetic Tree Of the Major Animal Cladesmentioning

confidence: 97%

The evolution and conservation of left-right patterning mechanisms

et al. 2014

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“…The vertebrate body plan is internally asymmetric [1], [2], [3], and although complete situs inversus is benign in humans, partial disruption of this asymmetric organization (for example in heterotaxy) can be lethal [4], [5], [6]. Although separated by 450 M year of divergent evolution, many insect body plans show similar internal asymmetry; for example, the alimentary canal of the classical developmental model Drosophila starts development symmetrically, but is then thrown into highly stereotyped folds within the body cavity.…”

Section: Introductionmentioning

confidence: 99%

Functional Correlates of Positional and Gender-Specific Renal Asymmetry in Drosophila

et al. 2012

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BackgroundIn humans and other animals, the internal organs are positioned asymmetrically in the body cavity, and disruption of this body plan can be fatal in humans. The mechanisms by which internal asymmetry are established are presently the subject of intense study; however, the functional significance of internal asymmetry (outside the brain) is largely unexplored. Is internal asymmetry functionally significant, or merely an expedient way of packing organs into a cavity?Methodology/Principal FindingsLike humans, Drosophila shows internal asymmetry, with the gut thrown into stereotyped folds. There is also renal asymmetry, with the rightmost pair of renal (Malpighian) tubules always ramifying anteriorly, and the leftmost pair always sitting posteriorly in the body cavity. Accordingly, transcriptomes of anterior-directed (right-side) and posterior-directed (left-side) Malpighian (renal) tubules were compared in both adult male and female Drosophila. Although genes encoding the basic functions of the tubules (transport, signalling) were uniformly expressed, some functions (like innate immunity) showed positional or gender differences in emphasis; others, like calcium handling or the generation of potentially toxic ammonia, were reserved for just the right-side or left-side tubules, respectively. These findings correlated with the distinct locations of each tubule pair within the body cavity. Well known developmental genes (like dorsocross, dachshund and doublesex) showed continuing, patterned expression in adult tubules, implying that somatic tissues maintain both left-right and gender identities throughout life. Gender asymmetry was also noted, both in defence and in male-specific expression of receptors for neuropeptide F and sex-peptide: NPF elevated calcium only in male tubules.Conclusions/SignificanceAccordingly, the physical asymmetry of the tubules in the body cavity is directly adaptive. Now that the detailed machinery underlying internal asymmetry is starting to be delineated, our work invites the investigation, not just of tissues in isolation, but in the context of their unique physical locations and milieux.

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“…It has been convincingly argued that the need for asymmetries within the gastrointestinal system drove the evolutionary adoption of handed asymmetry in internal organs [19, 20]. Though gut asymmetries have long fascinated embryologists, only recently have great strides been made in our understanding of the cellular, molecular, and mechanical basis of gut L-R patterning.…”

Section: Asymmetric Morphogenesis Of the Organsmentioning

confidence: 99%

“…This depends on the Nodal-Pitx2 cascade and, in particular, the downstream asymmetrically expressed Nkx3-2 / Bapx1 transcription factor-encoding gene. One model suggests that Nkx3-2 induces Fgf10 which signals to the dorsal pancreatic bud initiating its migration towards the FGF signal on the left side where the SMP outgrowth has arisen [20]. …”

Section: Asymmetric Morphogenesis Of the Organsmentioning

confidence: 99%

Left–Right Patterning: Breaking Symmetry to Asymmetric Morphogenesis

2017

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Vertebrates exhibit striking left-right (L-R) asymmetries in the structure and position of the internal organs. Symmetry is broken by motile cilia-generated asymmetric fluid flow, resulting in a signaling cascade — the Nodal-Pitx2 pathway — being robustly established within mesodermal tissue on the left side only. This pathway impinges upon various organ primordia to instruct their side-specific development. Recently, progress has been made in understanding both the breaking of embryonic L-R symmetry and how the Nodal-Pitx2 pathway controls lateralized cell differentiation, migration, and other aspects of cell behavior, as well as tissue-level mechanisms, that drive asymmetries in organ formation. Proper execution of asymmetric organogenesis is critical to health, making furthering our understanding of L-R development an important concern.

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Left‐right asymmetry in gut development: what happens next?

Cited by 23 publications

References 98 publications

The evolution and conservation of left-right patterning mechanisms

The evolution and conservation of left-right patterning mechanisms

Functional Correlates of Positional and Gender-Specific Renal Asymmetry in Drosophila

Left–Right Patterning: Breaking Symmetry to Asymmetric Morphogenesis

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