Limbless: A new genetic mutant in the chick

Prahlad, K. V.; Skala, Gerald; Jones, D. G.; Briles, W. E.

doi:10.1002/jez.1402090308

Cited by 51 publications

(27 citation statements)

References 6 publications

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“…7A), owing to the failure of apical ectodermal ridge (AER) formation (Fallon et al, 1983). Limb-bud development is, however, initiated and parts of the pectoral and pelvic girdles form (Prahlad et al, 1979), as do a few muscles of the Development 132 (3) Research article proximal hindlimb (data not shown). However, we found that all cloacal muscles were completely absent (Fig.…”

Section: Proximal Leg Development Is Required For Cloacal Musclesmentioning

confidence: 98%

“…On HH34, the embryos were processed for MyoD whole-mount in situ hybridisation. Spontaneously amelic chicken embryos limbless were kindly provided by Professor John Fallon (University of Wisconsin, USA) (Prahlad et al, 1979;Fallon et al, 1983). …”

Section: Chick Legless Modelsmentioning

confidence: 99%

“…First, we examined chicken limbless autosomal recessive mutants (Prahlad et al, 1979). These mutants form no visible limbs (Fig.…”

Section: Proximal Leg Development Is Required For Cloacal Musclesmentioning

confidence: 99%

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A dual fate of the hindlimb muscle mass: cloacal/perineal musculature develops from leg muscle cells

et al. 2005

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The cloaca serves as a common opening to the urinary and digestive systems. In most mammals, the cloaca is present only during embryogenesis, after which it undergoes a series of septation events leading to the formation of the anal canal and parts of the urogenital tract. During embryogenesis it is surrounded by skeletal muscle. The origin and the mechanisms regulating the development of these muscles have never been determined. Here, we show that the cloacal muscles of the chick originate from somites 30-34, which overlap the domain that gives rise to leg muscles (somites 26-33). Using molecular and cell labelling protocols, we have determined the aetiology of cloacal muscles. Surprisingly, we found that chick cloacal myoblasts first migrate into the developing leg bud and then extend out of the ventral muscle mass towards the cloacal tubercle. The development of homologous cloacal/perineal muscles was also examined in the mouse. Concordant with the results in birds, we found that perineal muscles in mammals also develop from the ventral muscle mass of the hindlimb. We provide genetic evidence that the perineal muscles are migratory, like limb muscles, by showing that they are absent in metd/d mutants. Using experimental embryological procedures (in chick) and genetic models (in chick and mouse), we show that the development of the cloacal musculature is dependent on proximal leg field formation. Thus, we have discovered a novel developmental mechanism in vertebrates whereby muscle cells first migrate from axially located somites to the pelvic limb, then extend towards the midline and only then differentiate into the single cloacal/perineal muscles.

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Section: Proximal Leg Development Is Required For Cloacal Musclesmentioning

confidence: 98%

Section: Chick Legless Modelsmentioning

confidence: 99%

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A dual fate of the hindlimb muscle mass: cloacal/perineal musculature develops from leg muscle cells

et al. 2005

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“…Prahlad et al, 1979;Ros et al, 1996), and there is only rudimentary knowledge of the genes that act upstream of blade and head development (Huang et al, 2006). By contrast, much information has been gathered on genes that finely pattern these structures.…”

Section: Introductionmentioning

confidence: 99%

Scapula development is governed by genetic interactions ofPbx1with its family members and withEmx2via their cooperative control ofAlx1

et al. 2010

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SUMMARYThe genetic pathways underlying shoulder blade development are largely unknown, as gene networks controlling limb morphogenesis have limited influence on scapula formation. Analysis of mouse mutants for Pbx and Emx2 genes has suggested their potential roles in girdle development. In this study, by generating compound mutant mice, we examined the genetic control of scapula development by Pbx genes and their functional relationship with Emx2. Analyses of Pbx and Pbx1;Emx2 compound mutants revealed that Pbx genes share overlapping functions in shoulder development and that Pbx1 genetically interacts with Emx2 in this process. Here, we provide a biochemical basis for Pbx1;Emx2 genetic interaction by showing that Pbx1 and Emx2 can bind specific DNA sequences as heterodimers. Moreover, the expression of genes crucial for scapula development is altered in these mutants, indicating that Pbx genes act upstream of essential pathways for scapula formation. In particular, expression of Alx1, an effector of scapula blade patterning, is absent in all compound mutants. We demonstrate that Pbx1 and Emx2 bind in vivo to a conserved sequence upstream of Alx1 and cooperatively activate its transcription via this potential regulatory element. Our results establish an essential role for Pbx1 in genetic interactions with its family members and with Emx2 and delineate novel regulatory networks in shoulder girdle development.

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“…The limbless mutation results in the failure of limb development at all 4 sites Prahlad et al, 1979). The phenotypic expression of the limbless gene appears to be mediated through an effect on the ectodermal cell layer.…”

mentioning

confidence: 99%

Survival of motoneurons in the brachial lateral motor column of limbless mutant chick embryos depends on the periphery

Jl¹,

Fallon²

1986

J. Neurosci.

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Motoneuron survival in the embryonic spinal cord is influenced by the presence or absence of the developing limb bud. We have recently begun a reexamination of the relationship between limb absence and motoneuron survival in a nonsurgical limb deletion model, the limbless mutant chick embryo. As in surgically limbdeleted normal embryos, only 10% of the motoneurons that are intially produced in the limbless mutant lateral motor column (LMC) survive the embryonic period (Lanser and Fallon, 1984). We now report' that, when supplied with a normal periphery (i.e., a normal limb bud), more than 40% of the motoneurons initially produced in the limbless LMC survive the embryonic period. Motoneuron cell counts in one-winged limbless embryos reveal that over 3.5 times as many motoneurons survive the cell death period in the LMC on the side with the limb than on the opposite, limbless side. This demonstrates the dependence of embryonic LMC motoneurons on the developing limb for survival and indicates that the limbless mutant is an appropriate model for studying the death and survival of LMC motoneurons during development. Using the limbless mutant to study LMC motoneuron survival eliminates the complication of possible direct surgical effects on motoneuron death. In addition, we found that a substantial effect of the wing on rescuing LMC motoneurons was exerted prior to the 6th day of embryonic development. Normally, little cell loss occurs in the brachial LMC during this time. Accordingly, motoneuron death in the limb-deprived brachial LMC, whether in surgically limb-deleted normal embryos or in genetically limbless embryos, is accelerated with respect to cell death in the normal brachial LMC.Since cell death was first established as an integral part of the development of specific nerve centers (Hamburger and LeviMontalcini, 1949), the phenomenon of naturally occurring neuronal death has been widely documented but incompletely understood (for a historical review, see Oppenheim, 198 1). One neuronal population where cell death has been extensively studied is the lateral motor column (LMC) of the spinal cord (see Lamb, 1984, for review). The LMC contains the motoneurons that innervate the muscles of the vertebrate limb. It has been

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Limbless: A new genetic mutant in the chick

Cited by 51 publications

References 6 publications

A dual fate of the hindlimb muscle mass: cloacal/perineal musculature develops from leg muscle cells

A dual fate of the hindlimb muscle mass: cloacal/perineal musculature develops from leg muscle cells

Scapula development is governed by genetic interactions ofPbx1with its family members and withEmx2via their cooperative control ofAlx1

Survival of motoneurons in the brachial lateral motor column of limbless mutant chick embryos depends on the periphery

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