Pituitary duplication and nasopharyngeal teratoma in a newborn: CT, MRI, US and correlative histopathological findings

The computed tomography and MRI imaging findings in a case of pituitary duplication and epipharyngeal teratoma are described in a newborn baby girl with respiratory difficulties. Associated skull base and central nervous system malformations are presented. Teratoma diagnosis was confirmed by histology. The embryological pathogenesis is discusse

On the trail of the 'new head' in Les Treilles

The vertebrate brain develops in association with neighboring tissues: neural crest, placodes, mesoderm and endoderm. The molecular and evolutionary relationships between the forming nervous system and the other craniofacial structures were at the focus of a recent meeting at the Fondation des Treilles in France. Entitled 'Relationships between Craniofacial and Neural Development', the meeting brought together researchers working on diverse species, the findings of whom provide clues as to the origin and diversity of the brain and facial regions that are involved in forming the 'new head' of vertebrates

The emergence of <i>Pax7</i>-expressing muscle stem cells during vertebrate head muscle development

Pax7 expressing muscle stem cells accompany all skeletal muscles in the body and in healthy individuals, efficiently repair muscle after injury. Currently, the in vitro manipulation and culture of these cells is still in its infancy, yet muscle stem cells may be the most promising route towards the therapy of muscle diseases such as muscular dystrophies.It is often overlooked that muscular dystrophies affect head and body skeletal muscle differently. Moreover, these muscles develop differently. Specifically, head muscle and its stem cells develop from the non-somitic head mesoderm which also has cardiac competence. To which extent head muscle stem cells retain properties of the early head mesoderm and might even be able to switch between a skeletal muscle and cardiac fate is not known. This is due to the fact that the timing and mechanisms underlying head muscle stem cell development are still obscure. Consequently, it is not clear at which time point one should compare the properties of head mesodermal cells and head muscle stem cells.To shed light on this, we traced the emergence of head muscle stem cells in the key vertebrate models for myogenesis, chicken, mouse, frog and zebrafish, using Pax7 as key marker. Our study reveals a common theme of head muscle stem cell development that is quite different from the trunk. Unlike trunk muscle stem cells, head muscle stem cells do not have a previous history of Pax7 expression, instead Pax7 expression emerges de-novo. The cells develop late, and well after the head mesoderm has committed to myogenesis. We propose that this unique mechanism of muscle stem cell development is a legacy of the evolutionary history of the chordate head mesoderm

The Developmental Brain Gene NPAS3 Contains the Largest Number of Accelerated Regulatory Sequences in the Human Genome

To identify the evolutionary genetic novelties that contributed to shape human-specific traits such as the use of a complex language, long-term planning and exceptional learning abilities is one of the ultimate frontiers of modern biology. Evolutionary signatures of functional shifts could be detected by comparing noncoding regions that are highly conserved across mammals or primates and rapidly accumulated nucleotide substitutions only in the lineage leading to humans. As gene loci densely populated with human-accelerated elements (HAEs) are more likely to have contributed to human-specific novelties, we sought to identify the transcriptional units and genomic 1 Mb intervals of the entire human genome carrying the highest number of HAEs. To this end, we took advantage of four available data sets of human genomic accelerated regions obtained through different comparisons and algorithms and performed a meta-analysis of the combined data. We found that the brain developmental transcription factor neuronal PAS domain-containing protein 3 (NPAS3) contains the largest cluster of noncoding-accelerated regions in the human genome with up to 14 elements that are highly conserved in mammals, including primates, but carry human-specific nucleotide substitutions. We then tested the ability of the 14 HAEs identified at the NPAS3 locus to act as transcriptional regulatory sequences in a reporter expression assay performed in transgenic zebrafish. We found that 11 out of the 14 HAEs present in NPAS3 act as transcriptional enhancers during development, particularly within the nervous system. As NPAS3 is known to play a crucial role during mammalian brain development, our results indicate that the high density of HAEs present in the human NPAS3 locus could have modified the spatiotemporal expression pattern of NPAS3 in the developing human brain and, therefore, contributed to human brain evolution.Fil: Kamm, Gretel Betiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular; ArgentinaFil: Pisciottano, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular; ArgentinaFil: Kliger, Rafi. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones En Ingeniería Genética y Biología Molecular; ArgentinaFil: Franchini, Lucia Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular; Argentin

Genetic regulation of pituitary gland development in human and mouse

Normal hypothalamopituitary development is closely related to that of the forebrain and is dependent upon a complex genetic cascade of transcription factors and signaling molecules that may be either intrinsic or extrinsic to the developing Rathke’s pouch. These factors dictate organ commitment, cell differentiation, and cell proliferation within the anterior pituitary. Abnormalities in these processes are associated with congenital hypopituitarism, a spectrum of disorders that includes syndromic disorders such as septo-optic dysplasia, combined pituitary hormone deficiencies, and isolated hormone deficiencies, of which the commonest is GH deficiency. The highly variable clinical phenotypes can now in part be explained due to research performed over the last 20 yr, based mainly on naturally occurring and transgenic animal models. Mutations in genes encoding both signaling molecules and transcription factors have been implicated in the etiology of hypopituitarism, with or without other syndromic features, in mice and humans. To date, mutations in known genes account for a small proportion of cases of hypopituitarism in humans. However, these mutations have led to a greater understanding of the genetic interactions that lead to normal pituitary development. This review attempts to describe the complexity of pituitary development in the rodent, with particular emphasis on those factors that, when mutated, are associated with hypopituitarism in humans

Generic signal-specific responses: cytokinin and context-dependent cellular responses

The phytohormone cytokinin triggers numerous and diverse responses during the plant life cycle via a two-component phosphorelay signalling system. Each step of the signalling cascade is supported by a gene family comprising several members. While functional redundancy is observed among family members, additional gene-specific functions encoded by cis-regulatory and coding sequence of individual family members have been described and contribute to specificity in signalling output. In addition, the cellular context of the signal-receiving cell affects the response triggered. Recent studies in Arabidopsis have demonstrated how expression of cytokinin signalling components predefines a spatiotemporal map of signalling sensitivity, which causes local signal amplification and attenuation. In summary, the specific interpretation of cytokinin signalling is affected by an orchestrated interplay of signalling genes and cellular contex

Craniovertebral anomalies associated with pituitary gland duplication

Background: An extremely rare occurrence of the pituitary gland duplication inspired us to examine in detail the accompanying craniovertebral congenital anomalies in a patient involved. Materials and methods: T1-wighted magnetic resonance imaging (MRI) was performed, as well as the multislice computerised tomography (MSCT) and MSCT angiography in our patient, as well as in a control group of 10 healthy subjects. Results: In a 20-year-old male a double pituitary gland was identified, as well as hypothalamic enlargement, tuberomamillary fusion and hamartoma. In addition, the patient also showed a duplicated hypophyseal fossa and posterior clinoid processes, notch of the upper sphenoid, prominent inner relief of the skull, inverse shape of the foramen magnum, third occipital condyle, partial aplasia of the anterior and posterior arches of the atlas with a left arcuate foramen, duplication of the odontoid process and the C2 body, and fusion of the C2–C4 and T12–L1 vertebrae. The MSCT angiography presented a segmental dilatation of both vertebral arteries and the A2 segment of the anterior cerebral artery, as well as a duplication of the basilar artery. Conclusions: This patient is unique due to complex craniovertebral congenital anomalies associated with a duplication of the pituitary gland

Identification and expression of the lamprey Pax6 gene: evolutionary origin of the segmented brain of vertebrates

The Pax6 gene plays a developmental role in various metazoans as the master regulatory gene for eye patterning. Pax6 is also spatially regulated in particular regions of the neural tube. Because the amphioxus has no neuromeres, an understanding of Pax6 expression in the agnathans is crucial for an insight into the origin of neuromerism in the vertebrates. We have isolated a single cognate cDNA of the Pax6 gene, LjPax6, from a Lampetra japonica cDNA library and observed the pattern of its expression using in situ hybridization. Phylogenetic analysis revealed that LjPax6 occurs as an sister group of gnathostome Pax6. In lamprey embryos, LjPax6 is expressed in the eye, the nasohypophysial plate, the oral ectoderm and the brain. In the central nervous system, LjPax6 is expressed in clearly delineated domains in the hindbrain, midbrain and forebrain. We compared the pattern of LjPax6 expression with that of other brain-specific regulatory genes, including LjOtxA, LjPax2/5/8, LjDlx1/6, LjEmx and LjTTF1. Most of the gene expression domains showed conserved pattern, which reflects the situation in the gnathostomes, conforming partly to the neuromeric patterns proposed for the gnathostomes. We conclude that most of the segmented domains of the vertebrate brain were already established in the ancestor common to all vertebrates. Major evolutionary changes in the vertebrate brain may have involved local restriction of cell lineages, leading to the establishment of neuromeres.</p

Genetic analysis of the Arabidopsis TIR1/AFB auxin receptors reveals both overlapping and specialized functions

© 2020, Prigge et al. The TIR1/AFB auxin co-receptors mediate diverse responses to the plant hormone auxin. The Arabidopsis genome encodes six TIR1/AFB proteins representing three of the four clades that were established prior to angiosperm radiation. To determine the role of these proteins in plant development we performed an extensive genetic analysis involving the generation and characterization of all possible multiply-mutant lines. We find that loss of all six TIR1/AFB proteins results in early embryo defects and eventually seed abortion, and yet a single wild-type allele of TIR1 or AFB2 is sufficient to support growth throughout development. Our analysis reveals extensive functional overlap between even the most distantly related TIR1/AFB genes except for AFB1. Surprisingly, AFB1 has a specialized function in rapid auxin-dependent inhibition of root growth and early phase of root gravitropism. This activity may be related to a difference in subcellular localization compared to the other members of the family