Development Of Vertebral Column Research Articles

Embryonic Thyroid Hormone Insufficiency Causes Structural Anomalies in the Embryo of Domestic Chick, Gallus domesticus.

Thyroid hormone (TH) is essential for growth and development, yet its specific role during embryogenesis remains incompletely understood. This study investigates the impact of TH deficiency, induced by thiourea, a known inhibitor of thyroid peroxidase (TPO), on the development of domestic chicks. Thiourea was administered before thyroid gland formation, and its presence in treated embryos was confirmed through liquid chromatography-mass spectrometry. In silico docking revealed a strong interaction between thiourea and the CCP-like domain of TPO, which was corroborated by TPO activity assays showing reduced enzyme function. This reduction in enzyme activity led to lower embryonic TH levels and increased thyroid-stimulating hormone (TSH) secretion. Morphological analysis of newly hatched chicks revealed significant structural anomalies, particularly in lateral plate mesoderm-derived structures, including omphalocele, limb deformities, anophthalmia and craniofacial defects. Alcian blue and Alizarin red staining demonstrated reduced ossification in ribs and forelimbs, while histological analysis showed incomplete abdominal wall closure and abnormal vertebral column development. Haematological profiling of TH-deficient newly hatched chicks revealed significantly lower blood cell counts, highlighting TH's critical role in haematopoiesis. These findings emphasise the multifaceted role of TH in embryonic development, with potential implications for understanding congenital hypothyroidism and its developmental impacts, especially in regions with limited healthcare access.

Effect of temperature on the incubation, growth, survival, and presence of skeletal deformities in larvae of the clownfish Amphiprion ocellaris (Pomacentridae) under rearing conditions

The results of the effect of five different incubation temperatures on the development of clownfish (Amphiprion ocellaris) larvae are presented. This ornamental species is widely marketed worldwide and is reared in captivity at CIAD to meet the demand in the domestic market. The experimental work was carried out over 30 days post-hatching to observe the temperature's effect on the development of the larvae's vertebral column and caudal complex. The eggs were incubated at 26, 28, 30, 32, and 34°C. The percentage of hatching, survival, growth, and the presence of skeletal malformations were evaluated. Hatching and survival percentages did not show significant differences between treatments. Regarding growth, there were significant differences between treatments, with organisms showing slower growth at 26°C and larger sizes at 34°C. The highest percentage of malformations occurred in larvae cultured at 34°C, with lordosis being the most frequently observed deformity among the treatments. Therefore, it can be concluded that the optimal temperature range for cultivating and harvesting quality A. ocellaris organisms is between 28 and 30°C.

Ontogeny of vertebral column and fin development, and detection of deformations in hatchery-reared European Flounder (Platichthys flesus) during early life stage

Understanding the skeletal development and deformations for aquaculture candidate fish species is vital for successful aquaculture practices. Developmental abnormalities at early life stages may reduce fish viability, growth, and wellbeing. This study was carried out to investigate the skeletal ontogeny and skeletal deformities of the European flounder (Platichthys flesus) at early life stage. Artificially produced European flounder larvae (n = 270) were randomly selected at a regular interval (30 fish at each sampling) from hatching to 50 days post-hatch (dph) and their skeletal ontogeny and skeletal deformations were evaluated by using bone and cartilage staining techniques. The average length of fish was 2.71 ± 0.04 mm at 0 dph and reached 19.76 ± 1.7 mm at 50 dph. The notochord began to form at 10 dph and finished flexion at 30 dph. Hypural rays appeared between 10 and 15 dph, followed by appearance of tail fin rays. Urostyle developed at 30 dph and began to ossify at 40 dph. Meristic characters showed an interspecific variation. At least one type of deformation was observed on 23.3% of larvae, and a total of 13 different deformations were identified. The most common deformation was the deformed vertebra which was observed 13 times followed by deformed dorsal fin ray, deformed caudal fin ray, and deformed neural arch and/or spine. Skeletal development during the early life stage of European flounder under culture conditions could be useful for future culture attempts and for early detection of skeletal deformations.

Epichordal vertebral column formation in Xenopus laevis.

Although Xenopus Laevis is the most widely used model amphibian, skeletal development of its vertebral column has not been well illustrated so far. The mode of vertebral column development in anurans has been classified into two modes: perichordal and epichordal. Xenopus vertebral column formation is believed to follow the epichordal mode, but this aspect has been underemphasized, and illustrative examples are currently unavailable to the scientific community. This study documents the entire process of vertebral column formation in X. laevis, from the initial neural arch formation to the completion of metamorphosis. These images reveal that the neural arch arises from the dorsal lamina and lateral pedicle primordia, with no strict adherence to an anteroposterior sequence. Unlike other species, Xenopus centrum primordia exclusively form at the expanded ventral margins of neural arches, rather than from the cartilaginous layer surrounding the notochord. These paired centrum primordia then fuse at the ventral midline, dorsal to the notochord, and subsequently the notochord degenerates. This mode of centrum formation differs from the traditional epichordal mode, indicating that Xenopus might have lost the ability to form a cartilaginous layer around the notochord. Instead, the neural arch's ventral margin appears to have evolved to incorporate centrum precursor cells at its base, thereby forming a centrum-like structure compensating for the absence of a true centrum. It is widely accepted that postsacral vertebrae lack centra, only possessing neural arches, and eventually fuse with the hypochord to form the urostyle. However, we have shown that the paired ventral ends of the postsacral vertebrae also fuse at the midline to form a centrum-like structure. This process might extend to the trunk region during centrum formation. In addition to these findings, we offer evolutionary insights into the reasons why Xenopus retains centrum primordia at the base of neural arches.

Direct BMP signaling to chordoblasts is required for the initiation of segmented notochord sheath mineralization in zebrafish vertebral column development.

The vertebral column, with the centra as its iteratively arranged building blocks, represents the anatomical key feature of the vertebrate phylum. In contrast to amniotes, where vertebrae are formed from chondrocytes and osteoblasts deriving from the segmentally organized neural crest or paraxial sclerotome, teleost vertebral column development is initiated by chordoblasts of the primarily unsegmented axial notochord, while sclerotomal cells only contribute to later steps of vertebrae formation. Yet, for both mammalian and teleostean model systems, unrestricted signaling by Bone Morphogenetic Proteins (BMPs) or retinoic acid (RA) has been reported to cause fusions of vertebral elements, while the interplay of the two signaling processes and their exact cellular targets remain largely unknown. Here, we address this interplay in zebrafish, identifying BMPs as potent and indispensable factors that, as formerly shown for RA, directly signal to notochord epithelial cells/chordoblasts to promote entpd5a expression and thereby metameric notochord sheath mineralization. In contrast to RA, however, which promotes sheath mineralization at the expense of further collagen secretion and sheath formation, BMP defines an earlier transitory stage of chordoblasts, characterized by sustained matrix production/col2a1 expression and concomitant matrix mineralization/entpd5a expression. BMP-RA epistasis analyses further indicate that RA can only affect chordoblasts and their further progression to merely mineralizing cells after they have received BMP signals to enter the transitory col2a1/entpd5a double-positive stage. This way, both signals ensure consecutively for proper mineralization of the notochord sheath within segmented sections along its anteroposterior axis. Our work sheds further light onto the molecular mechanisms that orchestrate early steps of vertebral column segmentation in teleosts. Similarities and differences to BMP's working mechanisms during mammalian vertebral column formation and the pathomechanisms underlying human bone diseases such as Fibrodysplasia Ossificans Progressiva (FOP) caused by constitutively active BMP signaling are discussed.

Integrated Analysis of Transcriptome Expression Profiles Reveals miRNA-326-NKX3.2-Regulated Porcine Chondrocyte Differentiation.

The porcine body length trait is an essential factor affecting meat production and reproductive performance. It is evident that the development/lengthening of individual vertebrae is one of the main reasons for increases in body length; however, the underlying molecular mechanism remains unclear. In this study, RNA-seq analysis was used to profile the transcriptome (lncRNA, mRNA, and miRNA) of the thoracic intervertebral cartilage (TIC) at two time points (1 and 4 months) during vertebral column development in Yorkshire (Y) and Wuzhishan pigs (W). There were four groups: 1- (Y1) and 4-month-old (Y4) Yorkshire pigs and 1- (W1) and 4-month-old (W4) Wuzhishan pigs. In total, 161, 275, 86, and 126 differentially expressed (DE) lncRNAs, 1478, 2643, 404, and 750 DE genes (DEGs), and 74,51, 34, and 23 DE miRNAs (DE miRNAs) were identified in the Y4 vs. Y1, W4 vs. W1, Y4 vs. W4, and Y1 vs. W1 comparisons, respectively. Functional analysis of these DE transcripts (DETs) demonstrated that they had participated in various biological processes, such as cellular component organization or biogenesis, the developmental process, the metabolic process, bone development, and cartilage development. The crucial bone development-related candidate genes NK3 Homeobox 2 (NKX3.2), Wnt ligand secretion mediator (WLS), gremlin 1 (GREM1), fibroblast growth factor receptor 3 (FGFR3), hematopoietically expressed homeobox (HHEX), (collagen type XI alpha 1 chain (COL11A1), and Wnt Family Member 16 (WNT16)) were further identified by functional analysis. Moreover, lncRNA, miRNA, and gene interaction networks were constructed; a total of 55 lncRNAs, 6 miRNAs, and 7 genes formed lncRNA-gene, miRNA-gene, and lncRNA-miRNA-gene pairs, respectively. The aim was to demonstrate that coding and non-coding genes may co-regulate porcine spine development through interaction networks. NKX3.2 was identified as being specifically expressed in cartilage tissues, and it delayed chondrocyte differentiation. miRNA-326 regulated chondrocyte differentiation by targeting NKX3.2. The present study provides the first non-coding RNA and gene expression profiles in the porcine TIC, constructs the lncRNA-miRNA-gene interaction networks, and confirms the function of NKX3.2 in vertebral column development. These findings contribute to the understanding of the potential molecular mechanisms regulating pig vertebral column development. They expand our knowledge about the differences in body length between different pig species and provide a foundation for future studies.

Phylogenetic Diversity of Ossification Patterns in the Avian Vertebral Column: A Review and New Data from the Domestic Pigeon and Two Species of Grebes.

Simple SummaryThere are still many unknowns in the development of the skeleton in birds. Traditionally, the neck vertebrae were considered to be the first ossifying elements in the spine. Later studies have shown that this is not always the case. In some species, the thoracic vertebrae ossify even before them. Evolutionary analyses indicate that ancestrally the spine starts ossifying from two different sites, one located in the neck, the other in the thorax. However, the Neoaves, a group that includes all living birds except the palaeognaths, landfowl and waterfowl, are very poorly studied. In this article, we review the information about ossification patterns of the spine in birds. We also describe its development in three neoavians, the pigeon and two grebes. In the pigeon, the neck vertebrae were the first to ossify, but in the grebe, the thoracic vertebrae ossified earlier. Our analyses confirm the ancestral presence of two sites from which the ossification of the spine starts in birds.Despite many decades of studies, our knowledge of skeletal development in birds is limited in many aspects. One of them is the development of the vertebral column. For many years it was widely believed that the column ossifies anteroposteriorly. However, later studies indicated that such a pattern is not universal in birds and in many groups the ossification starts in the thoracic rather than cervical region. Recent analyses suggest that two loci, located in the cervical and thoracic vertebrae, were ancestrally present in birds. However, the data on skeletal development are very scarce in the Neoaves, a clade that includes approximately 95% of extant species. We review the available information about the vertebral column development in birds and describe the ossification pattern in three neoavians, the domestic pigeon (Columba livia domestica), the great crested grebe (Podiceps cristatus) and the red-necked grebe (Podiceps grisegena). In P. cristatus, the vertebral column starts ossifying in the thoracic region. The second locus is present in the cervical vertebrae. In the pigeon, the cervical vertebrae ossify before the thoracics, but both the thoracic and cervical loci are present. Our ancestral state reconstructions confirm that both these loci were ancestrally present in birds, but the thoracic locus was later lost in psittacopasserans and at least some galloanserans.

Ontogeny of morphological variations in the vertebral column: Prevalence and bony variability in young Spanish children

Pre- and postnatal development and variability in discrete vertebral traits have been poorly described in embryonic studies. Numerous authors have reported that these variations are observable only from adolescence; scientific publications on the vertebrae of fetuses and infants are scarce. Thus, the aims of this study were to (1) describe the ontogeny and variability of anatomical variations in the vertebral column of a Spanish infant population and (2) analyze the frequency and relationship between sex, age, and intertrait variables. A total of 4728 vertebrae from 197 skeletons were studied. The age at death ranged from 22 intrauterine weeks to 8 years. Twenty morphological traits related to vertebral column development were analyzed. A descriptive statistical analysis was performed, and the chi-square test was used to measure the relationship between sex, age, and intertrait variables. We observed that 88.32% of skeletons expressed discrete traits along the spine. In fetuses, the double transverse foramen and unclosed transverse process of the axis were the most prevalent traits. In infants older than one year, the appearance of the L5 cleft neural arch, unclosed transverse process of the atlas, and craniocaudal shifts were frequent. A significant result was found between sex and the unclosed transverse process in the axis. The intertrait relationship was significant for all traits that shared the same embryonic structure. Morphological variations became visible following the appearance of ossification centers during the pre- and postnatal periods, and their etiology was associated with embryonic development.

NFAT5/TonEBP controls early acquisition of notochord phenotypic markers, collagen composition, and sonic hedgehog signaling during mouse intervertebral disc embryogenesis

High osmolarity, bound water, and hydrostatic pressure contribute to notochord mechanics and its morphogenesis into the nucleus pulposus (NP) compartment of the intervertebral disc. Indeed, the osmoadaptive transcription factor, nuclear factor of activated T-cells 5 (NFAT5 aka TonEBP), is robustly expressed by resident cells of the notochord and NP. Nevertheless, the molecular mechanisms that drive notochord osmoregulation and the functions of NFAT5 in disc embryogenesis remain largely unexplored. In this study, we show that deletion of NFAT5 in mice results in delayed vertebral column development and a reduced NP aspect ratio in the caudal spine. This phenotype is associated with lower levels of the T-box transcription factor, Brachyury, delayed expression of notochord phenotypic markers, and decreased collagen II deposition in the perinotochordal sheath and condensing mesenchyme. In addition, NFAT5 mutants showed a stage-dependent dysregulation of sonic hedgehog (Shh) signaling with non-classical expression of Gli1. Generation of mice with notochord-specific deletion of IFT88 (ShhcreERT2;Ift88f/f) supported this mode of Gli1 regulation. Using isolated primary NP cells and bioinformatics approaches, we further show that Ptch1 and Smo expression is controlled by NFAT5 in a cell autonomous manner. Altogether, our results demonstrate that NFAT5 contributes to notochord and disc embryogenesis through its regulation of hallmark notochord phenotypic markers, extracellular matrix, and Shh signaling.

Expression profiles of RA synthases and catabolic enzymes in newly hatched and metamorphosing larvae of Japanese flounder, Paralichthys olivaceus

Retinoic acid (RA) plays various embryogenesis and post-embryogenesis roles in vertebrates. As exposure of metamorphosing flounder larvae to RA has teratogenic effects on skin color and vertebral column development, harmonized RA synthesis and catabolism are likely essential in metamorphic development. To approach understanding of the roles of RA in flounder metamorphic development, we here examined the tissue mRNA expression of RA synthases (aldh1a1, aldh1a2, aldh1a3) and catabolic enzymes (cyp26a1, cyp26b1, cyp26c1) in newly hatched and metamorphosing larvae, and three-month-old juveniles by in situ hybridization (ISH). No ISH signal was detected for any genes from the skin and vertebral column susceptible to the teratogenic effects by RA. Since the intestine expressed aldh1a2 at high level in larvae but not in juvenile, it is a possibility that the larval intestine serves as a source of RA, and RA catabolic enzymes function at the level below sensitivity of ISH at vertebral column and skin development. We found that aldh1a2 and aldh1a3 were expressed along the margin of the tectum and the neurohypophysis of pituitary, respectively, both in contact with the cerebrospinal fluid (CSF), and cyp26b1 at the posterior tectum and cerebellum. We hypothesize that RA is supplied from the tectum and pituitary via the CSF for brain growth and maintenance, and cyp26b1 locally regulates RA contents in the brain.

The Association between Ponticulus Posticus and Dental Agenesis: A Retrospective Study.

Objective:Neural tube defects may increase the risk of an abnormal development of skull, vertebral column and teeth formation, including dental agenesis in non syndromic patients. The association between the presence of a congenital Dental Agenesis (DA) and the Atlantooccipital Ligament (AOL) calcification, known as “Ponticulus Posticus” (PP), as possible links can be investigated.Design:After a systematic review of the scientific literature on this topic, two independent examiners assessed the AOL calcification in lateral cephalograms of 350 non syndromic patients(7-21 years old). The results were compared with a control group (non syndromic patients, without congenital missing teeth).Results:The 16.3% of the population studied by cephalometric analysis revealed a prevalence rate of PP (both complete and partial) with a slight male predominance is seen, not statistically significant (χ square test = 0.09; p= 0.76). In both sexes complete PP is more observed. In the patients affected by DA the frequency of PP is the 66.6% (both complete than partial). The χ square test with Yates correction showed a significative difference(χ= 66.20; p value= 0.00) between PP in patients with DA compared to not affected by DA.Conclusions:PP is not an uncommon anomaly. Since orofacial pain like migraine and other symptoms are often associated to PP, during routine radiographic examination, if detected, it should be documented in patients’ health record and with symptoms, further investigation should be sought for. These findings encourage to think there’s an association between DA in non syndromic patients and neuro-crestal cells defects.

The sp7 gene is required for maturation of osteoblast-lineage cells in medaka (Oryzias latipes) vertebral column development

Sp7 is a zinc finger transcription factor that is essential for osteoblast differentiation in mammals. To verify the characteristic features of osteoblast-lineage cells in teleosts, we established medaka sp7 mutants using a transcription activator-like effector nuclease (TALEN) genome editing system. These mutants showed severe defects in the formation of skeletal structures. In particular, the neural and the hemal arches were not formed, although the chordal centra were formed. Analysis of the transgenic medaka revealed that sp7 mutant had normal distribution of type X collagen a1 a (col10a1a)-positive osteoblast-like cells around the centrum and at the proximal region of the vertebral arch. The sp7 mutant phenotype could be rescued by exogenous sp7 expression in col10a1a-positive cells, as well as in sp7-positive osteoblast cells. Furthermore, runx2-positive osteoblast progenitors were observed on the vertebral arches, but not on the centrum, during vertebral column development. In addition, these osteoblast progenitors differentiated into the col10a1a-positive cells. In sp7 mutant, the runx2-positive cells were normally distributed at the region of unformed vertebral arch but failed to differentiate into col10a1a-positive cells. These results indicate that osteoblast-lineage cells undergo two distinct differentiation processes during development of the vertebral arch and the centrum. Nevertheless, our results verified that sp7 gene expression in osteoblast-lineage cells is required for differentiation into mature osteoblasts to form the vertebral column and other skeletal structures.

Embryonic development of the axial column in the little skate, Leucoraja erinacea.

The morphological patterns and molecular mechanisms of vertebral column development are well understood in bony fishes (osteichthyans). However, vertebral column morphology in elasmobranch chondrichthyans (e.g., sharks and skates) differs from that of osteichthyans, and its development has not been extensively studied. Here, we characterize vertebral development in an elasmobranch fish, the little skate, Leucoraja erinacea, using microCT, paraffin histology, and whole-mount skeletal preparations. Vertebral development begins with the condensation of mesenchyme, first around the notochord, and subsequently around the neural tube and caudal artery and vein. Mesenchyme surrounding the notochord differentiates into a continuous sheath of spindle-shaped cells, which forms the precursor to the mineralized areolar calcification of the centrum. Mesenchyme around the neural tube and caudal artery/vein becomes united by a population of mesenchymal cells that condenses lateral to the sheath of spindle-shaped cells, with this mesenchymal complex eventually differentiating into the hyaline cartilage of the future neural arches, hemal arches, and outer centrum. The initially continuous layers of areolar tissue and outer hyaline cartilage eventually subdivide into discrete centra and arches, with the notochord constricted in the center of each vertebra by a late-forming "inner layer" of hyaline cartilage, and by a ring of areolar calcification located medial to the outer vertebral cartilage. The vertebrae of elasmobranchs are distinct among vertebrates, both in terms of their composition (i.e., with centra consisting of up to three tissues layers-an inner cartilage layer, a calcified areolar ring, and an outer layer of hyaline cartilage), and their mode of development (i.e., the subdivision of arch and outer centrum cartilage from an initially continuous layer of hyaline cartilage). Given the evident variation in patterns of vertebral construction, broad taxon sampling, and comparative developmental analyses are required to understand the diversity of mechanisms at work in the developing axial skeleton of vertebrates. J. Morphol. 278:300-320, 2017. © 2017 Wiley Periodicals, Inc.

Loss of Lysyl Oxidase-like 3 Attenuates Embryonic Lung Development in Mice

Lysyl oxidase-like 3 (LOXL3), a human disease gene candidate, is a member of the lysyl oxidase (LOX) family and is indispensable for mouse palatogenesis and vertebral column development. Our previous study showed that the loss of LOXL3 resulted in a severe cleft palate and spinal deformity. In this study, we investigated a possible role for LOXL3 in mouse embryonic lung development. LOXL3-deficient mice displayed reduced lung volumes and weights, diminished saccular spaces, and deformed and smaller thoracic cavities. Excess elastic fibres were detected in LOXL3-deficient lungs, which might be related to the increased LOXL4 expression. Increased transforming growth factor β1 (TGFβ1) expression might be involved in the up-regulation of LOXL4 in LOXL3-deficient lungs. We concluded that the loss of LOXL3 attenuates mouse embryonic lung development.

Role of notochord cells and sclerotome-derived cells in vertebral column development in fugu, Takifugu rubripes: histological and gene expression analyses.

Despite the common structure of vertebrates, the development of the vertebral column differs widely between teleosts and tetrapods in several respects, including the ossification of the centrum and the function of the notochord. In contrast to tetrapods, vertebral development in teleosts is not fully understood, particularly for large fish with highly ossified bones. We therefore examined the histology and gene expression profile of vertebral development in fugu, Takifugu rubripes, a model organism for genomic research. Ossification of the fugu centrum is carried out by outer osteoblasts expressing col1a1, col2a1, and sparc, and the growing centra completely divide the notochord into double cone-shaped segments that function as intercentral joints. In this process, the notochord basal cells produce a thick notochord sheath exhibiting Alcian-blue-reactive cartilaginous properties and composing the intercentral ligament in cooperation with the external ligament connective tissue. Synthesis of the matrix by the basal cells was ascertained by an in vitro test. Expression of twist2 indicates that this connective tissue is descended from the embryonic sclerotome. Notochord basal cells express sox9, ihhb, shh, and col2a1a, suggesting that the signaling system involved in chondrocyte proliferation and matrix production also functions in notochord cells for notochord sheath formation. We further found that the notochord expression of both ntla and shh is maintained in the fugu vertebral column, whereas it is turned off after embryogenesis in zebrafish. Thus, our results demonstrate that, in contrast to zebrafish, a dynamic morphogenesis and molecular network continues to function in fugu until the establishment of the adult vertebral column.

Loss of lysyl oxidase-like 3 causes cleft palate and spinal deformity in mice.

In mammals, embryonic development are highly regulated morphogenetic processes that are tightly controlled by genetic elements. Failure of any one of these processes can result in embryonic malformation. The lysyl oxidase (LOX) family genes are closely related to human diseases. In this study, we investigated the essential role of lysyl oxidase-like 3 (LOXL3), a member of the LOX family, in embryonic development. Mice lacking LOXL3 exhibited perinatal lethality, and the deletion of the Loxl3 gene led to impaired development of the palate shelves, abnormalities in the cartilage primordia of the thoracic vertebrae and mild alveolar shrinkage. We found that the obvious decrease of collagen cross-links in palate and spine that was induced by the lack of LOXL3 resulted in cleft palate and spinal deformity. Thus, we provide critical in vivo evidence that LOXL3 is indispensable for mouse palatogenesis and vertebral column development. The Loxl3 gene may be a candidate disease gene resulting in cleft palate and spinal deformity.

Expression of growth differentiation factor 6 in the human developing fetal spine retreats from vertebral ossifying regions and is restricted to cartilaginous tissues.

During embryogenesis vertebral segmentation is initiated by sclerotomal cell migration and condensation around the notochord, forming anlagen of vertebral bodies and intervertebral discs. The factors that govern the segmentation are not clear. Previous research demonstrated that mutations in growth differentiation factor 6 resulted in congenital vertebral fusion, suggesting this factor plays a role in development of vertebral column. In this study, we detected expression and localization of growth differentiation factor 6 in human fetal spinal column, especially in the period of early ossification of vertebrae and the developing intervertebral discs. The extracellular matrix proteins were also examined. Results showed that high levels of growth differentiation factor 6 were expressed in the nucleus pulposus of intervertebral discs and the hypertrophic chondrocytes adjacent to the ossification centre in vertebral bodies, where strong expression of proteoglycan and collagens was also detected. As fetal age increased, the expression of growth differentiation factor 6 was decreased correspondingly with the progress of ossification in vertebral bodies and restricted to cartilaginous regions. This expression pattern and the genetic link to vertebral fusion suggest that growth differentiation factor 6 may play an important role in suppression of ossification to ensure proper vertebral segmentation during spinal development.

Sulphated glycosaminoglycans and proteoglycans in the developing vertebral column of juvenile Atlantic salmon (Salmo salar).

In the present study, the distribution of sulphated glycosaminoglycans (GAGs) in the developing vertebral column of Atlantic salmon (Salmo salar) at 700, 900, 1100 and 1400 d° was examined by light microscopy. The mineralization pattern was outlined by Alizarin red S and soft structures by Alcian blue. The temporal and spatial distribution patterns of different types of GAGs: chondroitin-4-sulphate/dermatan sulphate, chondroitin-6-sulphate, chondroitin-0-sulphate and keratan sulphate were addressed by immunohistochemistry using monoclonal antibodies against the different GAGs. The specific pattern obtained with the different antibodies suggests a unique role of the different GAG types in pattern formation and mineralization. In addition, the distribution of the different GAG types in normal and malformed vertebral columns from 15 g salmon was compared. A changed expression pattern of GAGs was found in the malformed vertebrae, indicating the involvement of these molecules during the pathogenesis. The molecular size of proteoglycans (PGs) in the vertebrae carrying GAGs was analysed with western blotting, and mRNA transcription of the PGs aggrecan, decorin, biglycan, fibromodulin and lumican by real-time qPCR. Our study reveals the importance of GAGs in development of vertebral column also in Atlantic salmon and indicates that a more comprehensive approach is necessary to completely understand the processes involved.

In vivo genome-wide analysis of multiple tissues identifies gene regulatory networks, novel functions and downstream regulatory genes for Bapx1 and its co-regulation with Sox9 in the mammalian vertebral column.

BackgroundVertebrate organogenesis is a highly complex process involving sequential cascades of transcription factor activation or repression. Interestingly a single developmental control gene can occasionally be essential for the morphogenesis and differentiation of tissues and organs arising from vastly disparate embryological lineages.ResultsHere we elucidated the role of the mammalian homeobox gene Bapx1 during the embryogenesis of five distinct organs at E12.5 - vertebral column, spleen, gut, forelimb and hindlimb - using expression profiling of sorted wildtype and mutant cells combined with genome wide binding site analysis. Furthermore we analyzed the development of the vertebral column at the molecular level by combining transcriptional profiling and genome wide binding data for Bapx1 with similarly generated data sets for Sox9 to assemble a detailed gene regulatory network revealing genes previously not reported to be controlled by either of these two transcription factors.ConclusionsThe gene regulatory network appears to control cell fate decisions and morphogenesis in the vertebral column along with the prevention of premature chondrocyte differentiation thus providing a detailed molecular view of vertebral column development.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-1072) contains supplementary material, which is available to authorized users.

Osteological ontogeny and malformations in larval and juvenile golden pompano Trachinotus ovatus (Linnaeus 1758)

The osteological ontogeny and the incidence of deformities occurred in vertebral column and caudal complex were studied from 1 day post hatch (DPH) to 31 DPH in Trachinotus ovatus. Results indicate that the development of both caudal complex and vertebral column initiated between 7 DPH and 9 DPH along with the calcification of haemal arches and neural arches, and occurrence of caudal elements. The last element of caudal complex, uroneural, appeared on 18 DPH. A high number of malformations in the vertebral column and caudal complex were detected in this study. More than 33% experimental fish exhibited at least one type of malformation. Results from this study provide the first reference on the osteological ontogeny and malformation of golden pompano. Such information can be applied to the quality control for fingerling production in golden pompano.