The International journal of developmental biology最新文献

Although the nonbilaterian Hydra has a simple body architecture, its signaling systems are as complex as those of Bilateria. We here add data to the fibroblast growth factor signaling system which has previously been identified in Hydra as essential for bud detachment. The localized expression patterns of its, now fifteen, FGFs indicate additional, yet unidentified, functions in sometimes very small subsets of cells at the body termini and/or during budding or in testes. Presence of a typical signal sequence (prediction >93%) in only 30% of the Hydra FGFs suggests mechanisms of action (and/or secretion) other than the canonical ones. A knockdown approach using siRNA revealed a potential role for Hv-FGF-c in tentacle morphogenesis. Our results document a high complexity of FGF signaling sites in Hydra and open the field for a detailed analysis of their functions.

Carnitine palmitoyltransferase 1 (CPT1) is a key regulatory enzyme in fatty acid metabolism, responsible for the translocation of long-chain fatty acids into the mitochondria for β-oxidation in diverse biological contexts. Recent studies implicated the critical role of cpt1 genes during zebrafish development and heart regeneration; however, a comprehensive characterization of their spatiotemporal expression dynamics remains lacking. Here, we systematically analyzed the expression profiles of four cpt1 paralogs (cpt1aa, cpt1ab, cpt1b, and cpt1a2b) during zebrafish embryogenesis and the expression of cpt1ab and cpt1b during zebrafish heart regeneration. Our results reveal that these paralogs exhibit distinct spatiotemporal expression patterns during zygotic development. While cpt1aa and cpt1ab share high sequence conservation (77%), their expression patterns diverge substantially. Conversely, cpt1ab and cpt1b display convergent cardiac and somitic expression despite lower sequence similarity (53%). Following ventricular ablation, cpt1b expression transiently ceased then recovered during regeneration, whereas cpt1ab remained unchanged. These findings shed light on the evolutionary conservation and functional divergence of cpt1 paralogs, which establish a critical foundation for elucidating paralog-specific roles in fatty acid metabolism during vertebrate development and regeneration.

The skull of amniotes is categorized into three conditions based on skeletal arrangement in the temporal region: anapsid, synapsid and diapsid. Mammals (class Mammalia), a descendent lineage of the clade Synapsida, possess the synapsid skull, which is characterized by a single lower temporal arch that ventrally borders the lower temporal fenestra. Although we previously suggested, based on the data from placental mammals, that the reduction in the expression domain of the upstream osteogenic genes Msx2 and Runx2 in the embryonic temporal mesenchyme might have played a role in the evolution of synapsid skulls, the molecular basis of synapsid skull evolution is still largely unknown. In this study, we investigated expression patterns of four osteogenic genes (two upstream genes Msx2 and Runx2 and two downstream genes Sp7 and Sparc) in the embryonic and neonatal temporal region of the gray short-tailed opossum Monodelphis domestica, the most commonly used experimental marsupial model, in order to more thoroughly understand the molecular basis of development of synapsid skulls unique to mammals. We found that M. domestica embryos and neonates display very restricted expressions of Msx2 and/or Runx2 in the dermal bone precursors in the temporal region, as two placental species do (the house mouse Mus musculus and the greater horseshoe bat Rhinolophus ferrumequinum). Spatially restricted expression of Msx2 and Runx2 in the embryonic temporal region may be a foundation for creating the "advanced" synapsid skull shared by all mammals where only three dermal bones configure the temporal region.

Following publication of this article, the authors identified typographical errors in the primer sequences listed in Table 1 in the Materials and Methods section. The corrected table is published.

Interactions between ephrins and their Eph receptors regulate a broad range of cellular processes, including attraction, repulsion, adhesion and migration, all of which play crucial roles in tissue remodeling and homeostasis. While several ephrin ligands and Eph receptors are known to be expressed in the developing kidney, their specific roles, particularly during nephrogenesis, remain poorly understood. The development of the Xenopus pronephros provides an accessible and relatively simple model for studying vertebrate nephrogenesis. Through a comprehensive gene expression analysis of all ephrin ligands and Eph receptors present in Xenopus genomes, we have identified members of the Eph-ephrin signaling pathway that may contribute to pronephric development. Among them, efna3, which encodes an ephrin ligand, is strongly expressed in the ventral region of the pronephric anlage and later in the intermediate and distal segments of the developing tubule. This expression pattern is strikingly complementary to that of epha4 and epha7, which are expressed in the region forming the proximal tubule. This suggests a potential role for efna3-epha4/epha7 signaling in establishing a boundary between these domains during pronephros development.

How the dorsal thalamus of amniotes (reptiles, birds, and mammals) is organized remains an important but incompletely answered question. Identification of meaningful subdivisions would greatly aid in its understanding. Because the dorsal thalamus is more simply organized during development, studies have examined this structure during embryogenesis. Most reports using this approach have examined the developing dorsal thalamus in mammals and birds. Only rarely has the development of the dorsal thalamus been investigated in reptiles. Regardless, any approach to identify subdivisions, the presumed building blocks of the dorsal thalamus, should include representatives of all three classes of vertebrates. To fill this gap in knowledge, the development of the dorsal thalamus was investigated in Alligator mississippiensis, a member of the reptilian group most closely related to birds. As the first detailed study of its kind, cytoarchitecture and calretinin expression were used to examine dorsal thalamus development. Three subdivisions, termed tiers, and the individual nuclei originating from each tier, were identified. These three tiers were similar to the subdivisions found in birds and, to a limited extent, in mammals. Taken together, these early subdivisions may represent the common building blocks of the dorsal thalamus and provide clues to understand how evolution has sculpted this structure in amniotes.

The development of cranial nerves, including the trigeminal nerve, and the formation of neuromuscular junctions (NMJs) are crucial processes for craniofacial motor function. Mllt11/Af1q/Tcf7c (hereafter Mllt11), a novel type of cytoskeletal-interacting protein, has been implicated in neuronal migration and neuritogenesis during central nervous system development. However, its role in peripheral nerve development and NMJ formation remains poorly understood. This study investigates the function of Mllt11 during trigeminal ganglion development and its impact on motor innervation of the masseter muscle. We report Mllt11 expression in the developing trigeminal ganglia, suggesting a potential role in cranial nerve development. Using a conditional knockout mouse model to delete Mllt11 in Wnt1-expressing neural crest cells, we assessed trigeminal ganglion development and innervation of the masseter muscle in the jaw. Surprisingly, we found that Mllt11 loss does not affect the initial formation of the trigeminal ganglion but disrupts its placodal vs. neural crest cellular composition. Furthermore, we showed that conditional inactivation of Mllt11 using Wnt1^Cre2 led to a reduction of neurofilament density and NMJs within the masseter muscle, along with a reduction of Phox2b⁺ branchiomotor neurons in rhombomere 2, indicating altered trigeminal motor innervation. This was due to the surprising finding that the Wnt1^Cre2/+ mouse driver promoted aberrant recombination and reporter gene expression within branchiomotor neuron pools in rhombomere 2, as well as targeting neural crest cell populations. Our findings show that Mllt11 regulates the cellular composition of the trigeminal ganglion and is essential for proper trigeminal motor innervation in the masseter muscle.

The transcription factor GATA4 is found in Sertoli and Leydig cells, whereas SOX9 is exclusive to Sertoli cells, being both factors essential for the normal development of murine and human fetal testis. In turn, the steroidogenic acute regulatory protein (STAR) is specifically expressed in Leydig cells. Nevertheless, the function of STAR, GATA4 and SOX9 in peripubertal, adolescent and adult testes in Klinefelter syndrome and azoospermic patients remains poorly understood. To characterize the developmental expression of STAR, GATA4 and SOX9 in human testicular somatic cells, we performed immunofluorescence using fetal, peripubertal, adolescent and adult testes. Our findings demonstrate that STAR is absent in early fetal stages, but present in Leydig cells from 12 weeks of gestation, as well as in peripubertal, adolescent and adult Klinefelter patients, in the adult testis with idiopathic azoospermia and in men showing normal spermatogenesis. GATA4 was expressed in both Sertoli and Leydig cells during all the studied developmental stages and in peripubertal, adolescent and adult patients with and without spermatogenesis. SOX9 was mainly expressed in Sertoli cells in fetal, peripubertal, adolescent and adult Sertoli cell patients. In patients with Klinefelter syndrome as well as in men with or without spermatogenesis SOX9 was also found in Leydig cells. Our findings support the premise that STAR is a key steroidogenic protein for androgen development in the fetal testis, that GATA4 regulates Sertoli and Leydig cells during testis development and that SOX9 regulates the development of Sertoli cells and is present in the Leydig cells of patients with azoospermia.

Based on observations of in vivo morphogenesis, differentiation is expected to be regulated by mechanical cues. However, the detail mechanisms remain largely unknown. A previous study using human pluripotent stem cells (hPSCs) demonstrated that neural plate border (NPB) specification was enhanced by mechanical force. However, it is unknown whether mechanical force is also involved in the specification of the preplacodal ectoderm (PPE), which is derived from the NPB. Here, we verified the validity of the PPE induction method in stretch chambers, and conducted the stretching stimuli experiments. When repetitive stretching stimuli were applied from Day 2 to 10 or Day 2 to 7, expression of the PPE marker SIX1 was increased. However, this increase was not observed when the stimuli were applied from Day 5 to 10, suggesting there is a critical period of sensitivity to mechanical forces. Immunofluorescent staining revealed lower active β-catenin signals in the cell sheet in the stretched samples compared to those in the controls, suggesting a negative correlation between stretching stimuli and Wnt signaling. Our finding suggests that mechanical force is important in PPE differentiation.

Toll-Like Receptor 7 (TLR7) is recognized for its role in immune responses, particularly in detecting viral RNA. However, emerging evidence suggests that TLR7 may also contribute to ocular development. In this study, we assessed the expression pattern of TLR7 in various CD-1 mouse eye compartments during critical developmental stages, from embryonic day 12 to 16, as well as in adult tissues such as the cornea, pigmented epithelium, neural retina and lens. Our findings reveal a region-specific and time-dependent expression of TLR7, suggesting that it may play a role in the morphogenetic processes that shape the eye during intrauterine development.