scholarly journals Novel developmental bases for the evolution of hypobranchial muscles in vertebrates

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Rie Kusakabe ◽  
Shinnosuke Higuchi ◽  
Masako Tanaka ◽  
Mitsutaka Kadota ◽  
Osamu Nishimura ◽  
...  
Keyword(s):  
Body Wall ◽  
Hypoglossal Nerve ◽  
Expression Patterns ◽  
Complex Form ◽  
Rectus Muscle ◽  
Precursor Cells ◽  
Somatic Muscle ◽  
Developmental Mechanisms ◽  
Abdominal Rectus Muscle ◽  
Body Wall Muscles

Abstract Background Vertebrates are characterized by possession of hypobranchial muscles (HBMs). Cyclostomes, or modern jawless vertebrates, possess a rudimentary and superficial HBM lateral to the pharynx, whereas the HBM in jawed vertebrates is internalized and anteroposteriorly specified. Precursor cells of the HBM, marked by expression of Lbx1, originate from somites and undergo extensive migration before becoming innervated by the hypoglossal nerve. How the complex form of HBM arose in evolution is relevant to the establishment of the vertebrate body plan, but despite having long been assumed to be similar to that of limb muscles, modification of developmental mechanisms of HBM remains enigmatic. Results Here we characterize the expression of Lbx genes in lamprey and hagfish (cyclostomes) and catshark (gnathostome; jawed vertebrates). We show that the expression patterns of the single cyclostome Lbx homologue, Lbx-A, do not resemble the somitic expression of mammalian Lbx1. Disruption of Lbx-A revealed that LjLbx-A is required for the formation of both HBM and body wall muscles, likely due to the insufficient extension of precursor cells rather than to hindered muscle differentiation. Both homologues of Lbx in the catshark were expressed in the somitic muscle primordia, unlike in amniotes. During catshark embryogenesis, Lbx2 is expressed in the caudal HBM as well as in the abdominal rectus muscle, similar to lamprey Lbx-A, whereas Lbx1 marks the rostral HBM and pectoral fin muscle. Conclusions We conclude that the vertebrate HBM primarily emerged as a specialized somatic muscle to cover the pharynx, and the anterior internalized HBM of the gnathostomes is likely a novelty added rostral to the cyclostome-like HBM, for which duplication and functionalization of Lbx genes would have been a prerequisite.

scholarly journals ATRT-13. DIFFERENT CELLS OF ORIGIN PAVE THE WAY FOR MOLECULAR HETEROGENEITY IN RHABDOID TUMORS

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii278-iii278
Author(s):  
Monika Graf ◽  
Marta Interlandi ◽  
Natalia Moreno ◽  
Dörthe Holdhof ◽  
Viktoria Melcher ◽  
...  
Keyword(s):  
Single Cell ◽  
Expression Patterns ◽  
Time Frame ◽  
Precursor Cells ◽  
Genetically Engineered ◽  
Molecular Heterogeneity ◽  
Loss Of Function ◽  
Cellular Origin ◽  
Cells Of Origin ◽  
Rhabdoid Tumors

Abstract Rhabdoid tumors (RT) are rare but highly aggressive pediatric neoplasms. These tumors carry homozygous loss-of-function alterations of SMARCB1 in almost all cases with an otherwise low mutational load. RT arise at different intracranial (ATRT) as well as extracranial (MRT) anatomical sites. Three main molecular subgroups (ATRT-SHH, ATRT-TYR, ATRT-MYC) have been characterized for ATRT which are epigenetically and clinically diverse, while MRT show remarkable similarities with ATRT-MYC distinct from ATRT-SHH and ATRT-TYR. Even though there are hypotheses about various cells of origin among RT subgroups, precursor cells of RT have not yet been identified. Previous studies on the temporal control of SMARCB1 knockout in genetically engineered mouse models have unveiled a tight vulnerable time frame during embryogenesis with regard to the susceptibility of precursor cells to result in RT. In this study, we employed single-cell RNA sequencing to describe the intra- and intertumoral heterogeneity of murine ATRT-SHH and -MYC as well as extracranial MYC tumor cells. We defined subgroup-specific tumor markers for all RT classes but also observed a notable overlap of gene expression patterns in all MYC subgroups. By comparing these single-cell transcriptomes with available single-cell maps of early embryogenesis, we gained first insights into the cellular origin of RT. Finally, unsupervised clustering of published human RT methylation data and healthy control tissues confirmed the existence of different cells of origin for intracranial SHH tumors and MYC tumors independent of their anatomical localizations.

MyoD and Myf-5 define the specification of musculature of distinct embryonic origin

1998 ◽  
Vol 76 (6) ◽  
pp. 1079-1091 ◽  
Author(s):  
Boris Kablar ◽  
Atsushi Asakura ◽  
Kirsten Krastel ◽  
Chuyan Ying ◽  
Linda L May ◽  
...  
Keyword(s):  
Abdominal Wall ◽  
Expression Pattern ◽  
Branchial Arch ◽  
Precursor Cells ◽  
Mouse Development ◽  
Unique Role ◽  
Branchial Arches ◽  
Embryonic Origin ◽  
Body Wall Muscles ◽  
Myogenic Precursor

Mounting evidence supports the notion that Myf-5 and MyoD play unique roles in the development of epaxial (originating in the dorso-medial half of the somite, e.g. back muscles) and hypaxial (originating in the ventro-lateral half of the somite, e.g. limb and body wall muscles) musculature. To further understand how Myf-5 and MyoD genes co-operate during skeletal muscle specification, we examined and compared the expression pattern of MyoD-lacZ (258/-2.5lacZ and MD6.0-lacZ) transgenes in wild-type, Myf-5, and MyoD mutant embryos. We found that the delayed onset of muscle differentiation in the branchial arches, tongue, limbs, and diaphragm of MyoD-/- embryos was a consequence of a reduced ability of myogenic precursor cells to progress through their normal developmental program and not because of a defect in migration of muscle progenitor cells into these regions. We also found that myogenic precursor cells for back, intercostal, and abdominal wall musculature in Myf-5-/-embryos failed to undergo normal translocation or differentiation. By contrast, the myogenic precursors of intercostal and abdominal wall musculature in MyoD-/- embryos underwent normal translocation but failed to undergo timely differentiation. In conclusion, these observations strongly support the hypothesis that Myf-5 plays a unique role in the development of muscles arising after translocation of epithelial dermamyotome cells along the medial edge of the somite to the subjacent myotome (e.g., back or epaxial muscle) and that MyoD plays a unique role in the development of muscles arising from migratory precursor cells (e.g., limb and branchial arch muscles, tongue, and diaphragm). In addition, the expression pattern of MyoD-lacZ transgenes in the intercostal and abdominal wall muscles of Myf-5-/- and MyoD-/- embryos suggests that appropriate development of these muscles is dependent on both genes and, therefore, these muscles have a dual embryonic origin (epaxial and hypaxial).Key words: epaxial and hypaxial muscle, Myf-5, MyoD, mouse development, somite.

The Ligamentary System and the Segmental Musculature of Nephtys

1960 ◽  
Vol s3-101 (54) ◽  
pp. 149-176
Author(s):  
R. B. CLARK ◽  
M. E. CLARK
Keyword(s):  
Body Wall ◽  
The Body ◽  
Power Stroke ◽  
Coelomic Fluid ◽  
Unusual Structure ◽  
Shock Absorbers ◽  
Proximal Half ◽  
Unique System ◽  
Body Wall Muscles ◽  
The Impact

Nephtys lacks circular body-wall muscles. The chief antagonists of the longitudinal muscles are the dorso-ventral muscles of the intersegmental body-wall. The worm is restrained from widening when either set of muscles contracts by the combined influence of the ligaments, some of the extrinsic parapodial muscles, and possibly, to a limited extent, by the septal muscles. Although the septa are incomplete, they can and do form a barrier to the transmission of coelomic fluid from one segment to the next under certain conditions, particularly during eversion of the proboscis. Swimming is by undulatory movements of the body but the distal part of the parapodia execute a power-stroke produced chiefly by the contraction of the acicular muscles. It is suspected that the extrinsic parapodial muscles, all of which are inserted in the proximal half of the parapodium, serve to anchor the parapodial wall at the insertion of the acicular muscles and help to provide a rigid point of insertion for them. Burrowing is a cyclical process involving the violent eversion of the proboscis which makes a cavity in the sand. The worm is prevented from slipping backwards by the grip the widest segments have on the sides of the burrow. The proboscis is retracted and the worm crawls forward into the cavity it has made. The cycle is then repeated. Nephtys possesses a unique system of elastic ligaments of unusual structure. The anatomy of the system is described. The function of the ligaments appears to be to restrain the body-wall and parapodia from unnecessary and disadvantageous dilatations during changes of body-shape, and to serve as shock-absorbers against the high, transient, fluid pressures in the coelom, which are thought to accompany the impact of the proboscis against the sand when the worm is burrowing. From what is known of its habits, Nephtys is likely to undertake more burrowing than most other polychaetes.

scholarly journals Segmental differences in firing properties and potassium currents in Drosophila larval motoneurons

2012 ◽  
Vol 107 (5) ◽  
pp. 1356-1365 ◽  
Author(s):  
Subhashini Srinivasan ◽  
Kimberley Lance ◽  
Richard B. Levine
Keyword(s):  
Patch Clamp ◽  
Abdominal Segment ◽  
Body Wall ◽  
Potassium Currents ◽  
Whole Cell Patch Clamp ◽  
Voltage Dependent ◽  
Body Wall Muscles ◽  
Motoneuron Activity ◽  
Firing Properties ◽  
Thoracic And Abdominal

Potassium currents play key roles in regulating motoneuron activity, including functional specializations that are important for locomotion. The thoracic and abdominal segments in the Drosophila larval ganglion have repeated arrays of motoneurons that innervate body-wall muscles used for peristaltic movements during crawling. Although abdominal motoneurons and their muscle targets have been studied in detail, owing, in part, to their involvement in locomotion, little is known about the cellular properties of motoneurons in thoracic segments. The goal of this study was to compare firing properties among thoracic motoneurons and the potassium currents that influence them. Whole-cell, patch-clamp recordings performed from motoneurons in two thoracic and one abdominal segment revealed both transient and sustained voltage-activated K+ currents, each with Ca++-sensitive and Ca++-insensitive [A-type, voltage-dependent transient K+ current (IAv)] components. Segmental differences in the expression of voltage-activated K+ currents were observed. In addition, we demonstrate that Shal contributes to IAv currents in the motoneurons of the first thoracic segment.

Electrophysiology of Acanthocephalan Body Wall Muscles

1979 ◽  
Vol 82 (1) ◽  
pp. 273-280
Author(s):  
B. S. WONG ◽  
DONALD M. MILLER ◽  
T. T. DUNAGAN
Keyword(s):  
Light Microscopy ◽  
Intracellular Recording ◽  
Body Wall ◽  
Membrane Potentials ◽  
The Body ◽  
Spontaneous Potential ◽  
Body Wall Muscles ◽  
Macracanthorhynchus Hirudinaceus ◽  
Anterior Posterior

Body wall muscles of an acanthocephalan Macracanthorhynchus hirudinaceus were studied by means of scanning and light microscopy and intracellular recording of potentials. Three types of spontaneous potential changes were found: larger (L) potentials which usually exhibited overshoot and were as large as 65 mV; smaller symmetric (A) potentials approximately 15 mV in amplitude; and even smaller asymmetric (S) potentials which sometimes reached 10 mV. The potentials recorded depended upon the position of the electrode in the anterior-posterior, as well as the medialateral, axis. Tetrodotoxin eliminated L but not S potentials. Ouabain lengthened the time for depolarization of L potentials and depolarized the membrane potentials. It is suggested that the rete system activates the body wall muscles in Acanthocephala.

The spatial organization of epidermal structures: hairy establishes the geometrical pattern of Drosophila leg bristles by delimiting the domains of achaete expression

Development ◽  
1993 ◽  
Vol 118 (1) ◽  
pp. 9-20 ◽  
Author(s):  
T.V. Orenic ◽  
L.I. Held ◽  
S.W. Paddock ◽  
S.B. Carroll
Keyword(s):  
Drosophila Melanogaster ◽  
Spatial Organization ◽  
Expression Patterns ◽  
Cell Types ◽  
Precursor Cells ◽  
Geometrical Pattern ◽  
Leg Development ◽  
Puparium Formation ◽  
Late Expression ◽  
Bristle Pattern

The spatial organization of Drosophila melanogaster epidermal structures in embryos and adults constitutes a classic model system for understanding how the two dimensional arrangement of particular cell types is generated. For example, the legs of the Drosophila melanogaster adult are covered with bristles, which in most segments are arranged in longitudinal rows. Here we elucidate the key roles of two regulatory genes, hairy and achaete, in setting up this periodic bristle pattern. We show that achaete is expressed during pupal leg development in a dynamic pattern which changes, by approximately 6 hours after puparium formation, into narrow longitudinal stripes of 3–4 cells in width, each of which represents a field of cells (proneural field) from which bristle precursor cells are selected. This pattern of gene expression foreshadows the adult bristle pattern and is established in part through the function of the hairy gene, which also functions in patterning other adult sense organs. In pupal legs, hairy is expressed in four longitudinal stripes, located between every other pair of achaete stripes. We show that in the absence of hairy function achaete expression expands into the interstripe regions that normally express hairy, fusing the two achaete stripes and resulting in extra-wide stripes of achaete expression. This misexpression of achaete, in turn, alters the fields of potential bristle precursor cells which leads to the misalignment of bristle rows in the adult. This function of hairy in patterning achaete expression is distinct from that in the wing in which hairy suppresses late expression of achaete but has no effect on the initial patterning of achaete expression. Thus, the leg bristle pattern is apparently regulated at two levels: a global regulation of the hairy and achaete expression patterns which partitions the leg epidermis into striped zones (this study) and a local regulation (inferred from other studies on the selection of neural precursor cells) that involves refinement steps which may control the alignment and spacing of bristle cells within these zones.

The gene tinman is required for specification of the heart and visceral muscles in Drosophila

Development ◽  
1993 ◽  
Vol 118 (3) ◽  
pp. 719-729 ◽  
Author(s):  
R. Bodmer
Keyword(s):  
Heart Development ◽  
Body Wall ◽  
Heart Cells ◽  
Visceral Muscle ◽  
Visceral Mesoderm ◽  
Body Wall Muscles ◽  
Visceral Muscles

The homeobox-containing gene tinman (msh-2, Bodmer et al., 1990 Development 110, 661–669) is expressed in the mesoderm primordium, and this expression requires the function of the mesoderm determinant twist. Later in development, as the first mesodermal subdivisions are occurring, expression becomes limited to the visceral mesoderm and the heart. Here, I show that the function of tinman is required for visceral muscle and heart development. Embryos that are mutant for the tinman gene lack the appearance of visceral mesoderm and of heart primordia, and the fusion of the anterior and posterior endoderm is impaired. Even though tinman mutant embryos do not have a heart or visceral muscles, many of the somatic body wall muscles appear to develop although abnormally. When the tinman cDNA is ubiquitously expressed in tinman mutant embryos, via a heatshock promoter, formation of heart cells and visceral mesoderm is partially restored, tinman seems to be one of the earliest genes required for heart development and the first gene reported for which a crucial function in the early mesodermal subdivisions has been implicated.

Positioning and maintenance of embryonic body wall muscle attachments in C. elegans requires the mup-1 gene

Development ◽  
1991 ◽  
Vol 111 (3) ◽  
pp. 667-681 ◽  
Author(s):  
P.Y. Goh ◽  
T. Bogaert
Keyword(s):  
Extracellular Matrix ◽  
Body Wall ◽  
Early Stage ◽  
Muscle Growth ◽  
The Body ◽  
Body Wall Muscle ◽  
C Elegans ◽  
Extracellular Matrix Molecule ◽  
Extracellular Matrix Components ◽  
Body Wall Muscles

As part of a general study of genes specifying a pattern of muscle attachments, we identified and genetically characterised mutants in the mup-1 gene. The body wall muscles of early stage mup-1 embryos have a wild-type myofilament pattern but may extend ectopic processes. Later in embryogenesis, some body wall muscles detach from the hypodermis. Genetic analysis suggests that mup-1 has both a maternal and a zygotic component and is not required for postembryonic muscle growth and attachment. mup-1 mutants are suppressed by mutations in several genes that encode extracellular matrix components. We propose that mup-1 may encode a cell surface/extracellular matrix molecule required both for the positioning of body wall muscle attachments in early embryogenesis and the subsequent maintenance of these attachments to the hypodermis until after cuticle synthesis.

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