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Frontiers in Cell and Developmental... 2024Vertebrate body axis formation initiates during gastrulation and continues within the tail bud at the posterior end of the embryo. Major structures in the trunk are...
Vertebrate body axis formation initiates during gastrulation and continues within the tail bud at the posterior end of the embryo. Major structures in the trunk are paired somites, which generate the musculoskeletal system, the spinal cord-forming part of the central nervous system, and the notochord, with important patterning functions. The specification of these different cell lineages by key signalling pathways and transcription factors is essential, however, a global map of cell types and expressed genes in the avian trunk is missing. Here we use high-throughput sequencing approaches to generate a molecular map of the emerging trunk and tailbud in the chick embryo. Single cell RNA-sequencing (scRNA-seq) identifies discrete cell lineages including somites, neural tube, neural crest, lateral plate mesoderm, ectoderm, endothelial and blood progenitors. In addition, RNA-seq of sequential tissue sections (RNA-tomography) provides a spatially resolved, genome-wide expression dataset for the avian tailbud and emerging body, comparable to other model systems. Combining the single cell and RNA-tomography datasets, we identify spatially restricted genes, focusing on somites and early myoblasts. Thus, this high-resolution transcriptome map incorporating cell types in the embryonic trunk can expose molecular pathways involved in body axis development.
PubMed: 38863942
DOI: 10.3389/fcell.2024.1382960 -
Acta Medica Philippina 2024Klippel-Feil Syndrome (KFS) continues to pose significant challenges for anesthesiologists. Beyond the expected complexities of managing difficult airways in these...
Klippel-Feil Syndrome (KFS) continues to pose significant challenges for anesthesiologists. Beyond the expected complexities of managing difficult airways in these patients, they often present with systemic anomalies that can elevate the risk of morbidity during surgeries conducted under anesthesia. Furthermore, laparoscopic procedures bring about additional physiologic changes that must be taken into consideration when planning the anesthetic care for these individuals. This report details the anesthetic management of a 29-year-old female diagnosed with Klippel-Feil Syndrome (KFS) and concomitant Müllerian duct aplasia-Renal agenesis-Cervicothoracic Somite dysplasia (MURCS) as well as Chiari Type 1 Malformation, who underwent a successful pelvic laparoscopic surgery. The airway was secured through awake fiberoptic-guided intubation while general anesthesia was maintained with a combination of sevoflurane inhalation and remifentanil infusion. Intraoperatively, the team prioritized neuroprotection, lung-protective ventilation strategies, and renal preservation measures. The anesthetic management of patients with KFS necessitates a comprehensive assessment of their anomalies. Incorporating these considerations into the anesthetic management will help mitigate the procedure's adverse effects and lead to favorable patient outcomes.
PubMed: 38836075
DOI: 10.47895/amp.v58i9.8680 -
Nature Communications May 2024The emergence of new structures can often be linked to the evolution of novel cell types that follows the rewiring of developmental gene regulatory subnetworks....
The emergence of new structures can often be linked to the evolution of novel cell types that follows the rewiring of developmental gene regulatory subnetworks. Vertebrates are characterized by a complex body plan compared to the other chordate clades and the question remains of whether and how the emergence of vertebrate morphological innovations can be related to the appearance of new embryonic cell populations. We previously proposed, by studying mesoderm development in the cephalochordate amphioxus, a scenario for the evolution of the vertebrate head mesoderm. To further test this scenario at the cell population level, we used scRNA-seq to construct a cell atlas of the amphioxus neurula, stage at which the main mesodermal compartments are specified. Our data allowed us to validate the presence of a prechordal-plate like territory in amphioxus. Additionally, the transcriptomic profile of somite cell populations supports the homology between specific territories of amphioxus somites and vertebrate cranial/pharyngeal and lateral plate mesoderm. Finally, our work provides evidence that the appearance of the specific mesodermal structures of the vertebrate head was associated to both segregation of pre-existing cell populations, and co-option of new genes for the control of myogenesis.
Topics: Animals; Mesoderm; Lancelets; Head; Gene Expression Regulation, Developmental; Vertebrates; Somites; Biological Evolution; Transcriptome
PubMed: 38811547
DOI: 10.1038/s41467-024-48774-4 -
Frontiers in Physiology 2024Initially, the two members of class 18 myosins, Myo18A and Myo18B, appeared to exhibit highly divergent functions, complicating the assignment of class-specific... (Review)
Review
Initially, the two members of class 18 myosins, Myo18A and Myo18B, appeared to exhibit highly divergent functions, complicating the assignment of class-specific functions. However, the identification of a striated muscle-specific isoform of Myo18A, Myo18Aγ, suggests that class 18 myosins may have evolved to complement the functions of conventional class 2 myosins in sarcomeres. Indeed, both genes, and , are predominantly expressed in the heart and somites, precursors of skeletal muscle, of developing mouse embryos. Genetic deletion of either gene in mice is embryonic lethal and is associated with the disorganization of cardiac sarcomeres. Moreover, Myo18Aγ and Myo18B localize to sarcomeric A-bands, albeit the motor (head) domains of these unconventional myosins have been both deduced and biochemically demonstrated to exhibit negligible ATPase activity, a hallmark of motor proteins. Instead, Myo18Aγ and Myo18B presumably coassemble with thick filaments and provide structural integrity and/or internal resistance through interactions with F-actin and/or other proteins. In addition, Myo18Aγ and Myo18B may play distinct roles in the assembly of myofibrils, which may arise from actin stress fibers containing the α-isoform of Myo18A, Myo18Aα. The β-isoform of Myo18A, Myo18Aβ, is similar to Myo18Aα, except that it lacks the N-terminal extension, and may serve as a negative regulator through heterodimerization with either Myo18Aα or Myo18Aγ. In this review, we contend that Myo18Aγ and Myo18B are essential for myofibril structure and function in striated muscle cells, while α- and β-isoforms of Myo18A play diverse roles in nonmuscle cells.
PubMed: 38784114
DOI: 10.3389/fphys.2024.1401717 -
Development (Cambridge, England) May 2024During mouse development, presomitic mesoderm cells synchronize Wnt and Notch oscillations, creating sequential phase waves that pattern somites. Traditional...
During mouse development, presomitic mesoderm cells synchronize Wnt and Notch oscillations, creating sequential phase waves that pattern somites. Traditional somitogenesis models attribute phase waves to a global modulation of the oscillation frequency. However, increasing evidence suggests that they could arise in a self-organizing manner. Here, we introduce the Sevilletor, a novel reaction-diffusion system that serves as a framework to compare different somitogenesis patterning hypotheses. Using this framework, we propose the Clock and Wavefront Self-Organizing model that considers an excitable self-organizing region where phase waves form independent of global frequency gradients. The model recapitulates the change in relative phase of Wnt and Notch observed during mouse somitogenesis and provides a theoretical basis for understanding the excitability of mouse presomitic mesoderm cells in vitro.
Topics: Animals; Mice; Somites; Receptors, Notch; Mesoderm; Models, Biological; Body Patterning; Wnt Proteins; Embryonic Development; Biological Clocks
PubMed: 38742434
DOI: 10.1242/dev.202606 -
International Journal of Molecular... Apr 2024is a critical transcription factor that plays a pivotal role in embryogenesis and muscle development. It has been established as a marker gene for growth-specific...
is a critical transcription factor that plays a pivotal role in embryogenesis and muscle development. It has been established as a marker gene for growth-specific muscle stem cells in zebrafish. In this study, we identified the gene in a large teleost fish, . Through in situ hybridization and histological analysis, we discovered that can be employed as a specific marker of growth-specific muscle stem cells, which originate from the somite stage and are primarily situated in the external cell layer (ECL) and myosepta, with a minor population distributed among muscle fibers. The knockdown of resulted in a significant increase in expression, subsequently promoting cell cycle progression and potentially accelerating the depletion of the stem cell pool, which ultimately led to significant growth retardation. These findings suggest that arrests the cell cycle of growth-specific muscle stem cells in the G2 phase by suppressing expression, which is essential for maintaining the stability of the growth-specific muscle stem cell pool. Our study provides significant insights into the molecular mechanisms underlying the indeterminate growth of large teleosts.
Topics: Animals; Cell Cycle; Cyclin B1; Fish Proteins; Gene Expression Regulation, Developmental; Homeodomain Proteins; Muscle Development; Stem Cells; Transcription Factors; Fishes
PubMed: 38732090
DOI: 10.3390/ijms25094871 -
International Journal of Molecular... Apr 2024During embryogenesis, basic fibroblast growth factor (bFGF) is released from neural tube and myotome to promote myogenic fate in the somite, and is routinely used for...
During embryogenesis, basic fibroblast growth factor (bFGF) is released from neural tube and myotome to promote myogenic fate in the somite, and is routinely used for the culture of adult skeletal muscle (SKM) stem cells (MuSC, called satellite cells). However, the mechanism employed by bFGF to promote SKM lineage and MuSC proliferation has not been analyzed in detail. Furthermore, the question of if the post-translational modification (PTM) of bFGF is important to its stemness-promoting effect has not been answered. In this study, GST-bFGF was expressed and purified from , which lacks the PTM system in eukaryotes. We found that both GST-bFGF and commercially available bFGF activated the Akt-Erk pathway and had strong cell proliferation effect on C2C12 myoblasts and MuSC. GST-bFGF reversibly compromised the myogenesis of C2C12 myoblasts and MuSC, and it increased the expression of , , and but strongly repressed that of , suggesting the maintenance of myogenic stemness amid repressed expression. The proliferation effect of GST-bFGF was conserved in C2C12 over-expressed with (C2C12-tTA-MyoD), implying its independence of the down-regulation of . In addition, the repressive effect of GST-bFGF on myogenic differentiation was almost totally rescued by the over-expression of . Together, these evidences suggest that (1) GST-bFGF and bFGF have similar effects on myogenic cell proliferation and differentiation, and (2) GST-bFGF can promote MuSC stemness and proliferation by differentially regulating and Pax3/7, (3) MyoD repression by GST-bFGF is reversible and independent of the proliferation effect, and (4) GST-bFGF can be a good substitute for bFGF in sustaining MuSC stemness and proliferation.
Topics: Muscle Development; Animals; Mice; MyoD Protein; Cell Proliferation; Fibroblast Growth Factor 2; Myoblasts; Cell Line; PAX7 Transcription Factor; PAX3 Transcription Factor; Myogenic Regulatory Factor 5; Cyclin D1; Satellite Cells, Skeletal Muscle; Cell Differentiation; Proto-Oncogene Proteins c-akt; Muscle, Skeletal
PubMed: 38673893
DOI: 10.3390/ijms25084308 -
PloS One 2024During vertebrate embryo development, the body is progressively segmented along the anterior-posterior (A-P) axis early in development. The rate of somite formation is...
During vertebrate embryo development, the body is progressively segmented along the anterior-posterior (A-P) axis early in development. The rate of somite formation is controlled by the somitogenesis embryo clock (EC), which was first described as gene expression oscillations of hairy1 (hes4) in the presomitic mesoderm of chick embryos with 15-20 somites. Here, the EC displays the same periodicity as somite formation, 90 min, whereas the posterior-most somites (44-52) only arise every 150 minutes, matched by a corresponding slower pace of the EC. Evidence suggests that the rostral-most somites are formed faster, however, their periodicity and the EC expression dynamics in these early stages are unknown. In this study, we used time-lapse imaging of chicken embryos from primitive streak to somitogenesis stages with high temporal resolution (3-minute intervals). We measured the length between the anterior-most and the last formed somitic clefts in each captured frame and developed a simple algorithm to automatically infer both the length and time of formation of each somite. We found that the occipital somites (up to somite 5) form at an average rate of 75 minutes, while somites 6 onwards are formed approximately every 90 minutes. We also assessed the expression dynamics of hairy1 using half-embryo explants cultured for different periods of time. This showed that EC hairy1 expression is highly dynamic prior to somitogenesis and assumes a clear oscillatory behaviour as the first somites are formed. Importantly, using ex ovo culture and live-imaging techniques, we showed that the hairy1 expression pattern recapitulates with the formation of each new pair of somites, indicating that somite segmentation is coupled with EC oscillations since the onset of somitogenesis.
Topics: Animals; Chick Embryo; Somites; Chickens; Basic Helix-Loop-Helix Transcription Factors; Avian Proteins; Mesoderm
PubMed: 38635504
DOI: 10.1371/journal.pone.0297853 -
Developmental Cell Apr 2024Embryogenesis requires substantial coordination to translate genetic programs to the collective behavior of differentiating cells, but understanding how cellular...
Embryogenesis requires substantial coordination to translate genetic programs to the collective behavior of differentiating cells, but understanding how cellular decisions control tissue morphology remains conceptually and technically challenging. Here, we combine continuous Cas9-based molecular recording with a mouse embryonic stem cell-based model of the embryonic trunk to build single-cell phylogenies that describe the behavior of transient, multipotent neuro-mesodermal progenitors (NMPs) as they commit into neural and somitic cell types. We find that NMPs show subtle transcriptional signatures related to their recent differentiation and contribute to downstream lineages through a surprisingly broad distribution of individual fate outcomes. Although decision-making can be heavily influenced by environmental cues to induce morphological phenotypes, axial progenitors intrinsically mature over developmental time to favor the neural lineage. Using these data, we present an experimental and analytical framework for exploring the non-homeostatic dynamics of transient progenitor populations as they shape complex tissues during critical developmental windows.
PubMed: 38579718
DOI: 10.1016/j.devcel.2024.03.024 -
Acta Parasitologica Mar 2024The present paper describes two new genera and species of the parasitic copepod family Chondracanthidae Milne Edwards, 1840 based on specimens collected from two species...
PURPOSE
The present paper describes two new genera and species of the parasitic copepod family Chondracanthidae Milne Edwards, 1840 based on specimens collected from two species of deep-sea fishes at a depth of 212 m off Suruga Bay, Japan. Avatar nishidai gen. et sp. nov. is described from the host fish Chaunax abei Le Danois, 1978 (Chaunacidae). Kokeshioides surugaensis gen. et sp. nov. is described from the host fish Setarches longimanus (Alcock, 1894) (Setarchidae).
METHODS
Fresh specimens of chondracanthids were collected from the buccal cavity of two species of deep-sea fishes (fish hosts were frozen), Chaunax abei Le Danois, 1978 (Lophiiformes: Chaunacidae) and Setarches longimanus (Alcock, 1894) (Perciformes: Setarchidae), caught at a depth of 212 m in Suruga Bay, Japan (34° 37'48.87″ N, 138° 43'2.958″ E). Both the species are described and illustrated based on ovigerous females.
RESULTS
The genus Avatar gen. nov. can readily be distinguished from all other chondracanthid genera by the following combination of features: cephalothorax slightly wider than long with anterior pair of large and posterior pair of small lateral lobes, and two pairs of ventro-lateral processes; the very posteriormost part of the first pedigerous somite contributes to the neck; cylindrical trunk with two pairs of blunt proximal fusiform processes; antennule with small knob terminally; antenna bearing distal endopodal segment; labrum protruding ventrally; two pairs of biramous legs each with 2-segmented rami. Kokeshioides gen. nov. has the following combinations of features that distinguish it from other chondracanthid genera: body flattened, without lateral processes; cephalothorax much wider than long, with paired anterolateral and posterolateral lobes, folded ventrally; the very posteriormost part of the first pedigerous somite contributes to the neck; mandible elongate; legs unique, heavily sclerotized, represented by two pairs of acutely pointed processes.
CONCLUSION
With the addition of two new genera presently reported, the family Chondracanthidae currently includes 52 valid genera. Among the described genera Avatar gen. nov. seems to be very primitive, while Kokeshioides gen. nov. is highly advanced. The deduced evolutionary history of chondracanthid genera is also discussed.
Topics: Animals; Copepoda; Japan; Fish Diseases; Female; Bays; Male; Fishes; Ectoparasitic Infestations; Perciformes
PubMed: 38468018
DOI: 10.1007/s11686-024-00820-3