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Hopwood N. Species Choice and Model Use: Reviving Research on Human Development. JOURNAL OF THE HISTORY OF BIOLOGY 2024; 57:231-279. [PMID: 39075321 PMCID: PMC11341657 DOI: 10.1007/s10739-024-09775-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/13/2024] [Indexed: 07/31/2024]
Abstract
While model organisms have had many historians, this article places studies of humans, and particularly our development, in the politics of species choice. Human embryos, investigated directly rather than via animal surrogates, have gone through cycles of attention and neglect. In the past 60 years they moved from the sidelines to center stage. Research was resuscitated in anatomy, launched in reproductive biomedicine, molecular genetics, and stem-cell science, and made attractive in developmental biology. I explain this surge of interest in terms of rivalry with models and reliance on them. The greater involvement of medicine in human reproduction, especially through in vitro fertilization, gave access to fresh sources of material that fed critiques of extrapolation from mice and met demands for clinical relevance or "translation." Yet much of the revival depended on models. Supply infrastructures and digital standards, including biobanks and virtual atlases, emulated community resources for model organisms. Novel culture, imaging, molecular, and postgenomic methods were perfected on less precious samples. Toing and froing from the mouse affirmed the necessity of the exemplary mammal and its insufficiency justified inquiries into humans. Another kind of model-organoids and embryo-like structures derived from stem cells-enabled experiments that encouraged the organization of a new field, human developmental biology. Research on humans has competed with and counted on models.
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Affiliation(s)
- Nick Hopwood
- Department of History and Philosophy of Science, University of Cambridge, Free School Lane, Cambridge, CB2 3RH, UK.
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Männer J. When Does the Human Embryonic Heart Start Beating? A Review of Contemporary and Historical Sources of Knowledge about the Onset of Blood Circulation in Man. J Cardiovasc Dev Dis 2022; 9:187. [PMID: 35735816 PMCID: PMC9225347 DOI: 10.3390/jcdd9060187] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 05/31/2022] [Accepted: 06/07/2022] [Indexed: 11/17/2022] Open
Abstract
The onset of embryonic heart beating may be regarded as the defining feature for the beginning of personal human life. Clarifying the timing of the first human heartbeat, therefore, has religious, philosophical, ethical, and medicolegal implications. This article reviews the historical and contemporary sources of knowledge on the beginning of human heart activity. Special attention is given to the problem of the determination of the true age of human embryos and to the problem of visualization of the human embryonic heart activity. It is shown that historical and current textbook statements about the onset of blood circulation in man do not derive from observations on living human embryos but derive from the extrapolation of observations on animal embryos to the human species. This fact does not preclude the existence of documented observations on human embryonic heart activity: Modern diagnostic (ultrasound) and therapeutic (IVF) procedures facilitate the visualization of early embryonic heart activity in precisely dated pregnancies. Such studies showed that the human heart started its pumping action during the fourth post-fertilization week. A small number of direct observations on the heart activity of aborted human embryos were reported since the 19th century, but did not receive much recognition by embryologists.
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Affiliation(s)
- Jörg Männer
- Group Cardio-Embryology, Institute of Anatomy and Embryology UMG, Georg-August-University Goettingen, D-37075 Goettingen, Germany
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Cantagrel V, Lossi AM, Lisgo S, Missirian C, Borges A, Philip N, Fernandez C, Cardoso C, Figarella-Branger D, Moncla A, Lindsay S, Dobyns WB, Villard L. Truncation of NHEJ1 in a patient with polymicrogyria. Hum Mutat 2007; 28:356-64. [PMID: 17191205 DOI: 10.1002/humu.20450] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Polymicrogyria (PMG) is a common malformation of the human cerebral cortex for which both acquired and genetic causes are known. Although genetic heterogeneity is documented, only one gene is currently known to cause isolated PMG. To clone new genes involved in this type of cerebral malformation, we studied a fetus presenting a defect of cortical organization consisting of a polymicrogyric cortex and neuronal heterotopia within the white matter. Karyotype analysis revealed that the fetus was carrier of a balanced, de novo, chromosomal translocation t(2;7)(q35;p22). Cloning and sequencing of the two translocation breakpoints reveals that the chromosomal rearrangement disrupts the coding region of a single gene, called NHEJ1, Cernunnos, or XLF, in 2q35. The NHEJ1 gene was recently identified as being responsible for autosomal recessive immunodeficiency with microcephaly. Using quantitative PCR experiments, we show that a truncated transcript is expressed in the polymicrogyric patient cells, suggesting a potential dominant negative effect possibly leading to a different phenotype. We performed in situ hybridization on human embryos and showed that the NHEJ1 transcript is preferentially expressed in the telencephalic ventricular and subventricular zones, consistent with the phenotype of the affected individual. In the human adult central nervous system (CNS), NHEJ1 is mainly expressed in the cerebral cortex and in the cerebellum. The association of PMG with the disruption of its transcript suggests that, in addition to its recently uncovered function in the immune system, the NHEJ1 protein may also play a role during development of the human cerebral cortex.
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Abstract
Human development in the first 8 weeks is potentially one of the most exciting areas of biologic research. Beyond historic staging of fixed human embryos, it is also one of the least understood. In contrast, detailed information exists for the embryonic period of several other species, from which human development information is extrapolated. This period is also the most sensitive to system abnormalities generated by teratogens. This review combines the human embryo Carnegie stages, available online at UNSW Embryology (http://embryology.med.unsw.edu.au), with teratogen-sensitive information. Integrating this data with current molecular, imaging, and online tools will provide insights to this period.
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Affiliation(s)
- Mark Anthony Hill
- School of Medical Sciences, The University of New South Wales, Sydney, Australia.
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Abstract
Studies of human embryos and fetuses have highlighted developmental differences between humans and model organisms. In addition to describing the normal biology of our own species, a justification in itself, studies of early human development have aided identification of candidate disease genes mapped by positional cloning strategies, understanding pathophysiology, where human disorders are not faithfully reproduced by models in other species, and, more recently, potential therapies based on human embryonic stem and embryonic germ cells. In this article, we review these applications. We also discuss when and how to study human embryo and early fetuses and some of the regulations of this research.
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Affiliation(s)
- H Ostrer
- Human Genetics Program, Department of Pediatrics, New York University School of Medicine, New York, NY 10016, USA.
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Lindsay S, Sarma S, Martínez-de-la-Torre M, Kerwin J, Scott M, Luis Ferran J, Baldock R, Puelles L. Anatomical and gene expression mapping of the ventral pallium in a three-dimensional model of developing human brain. Neuroscience 2006; 136:625-32. [PMID: 16344140 DOI: 10.1016/j.neuroscience.2005.06.093] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Revised: 06/16/2005] [Accepted: 06/27/2005] [Indexed: 11/19/2022]
Abstract
Combining gene expression data with morphological information has revolutionized developmental neuroanatomy in the last decade. Visualization and interpretation of complex images have been crucial to these advances in our understanding of mechanisms underlying early brain development, as most developmental processes are spatially oriented, in topologically invariant patterns that become overtly distorted during brain morphogenesis. It has also become clear that more powerful methodologies are needed to accommodate the increasing volume of data available and the increasingly sophisticated analyses that are required, for example analyzing anatomy and multiple gene expression patterns at individual developmental stages, or identifying and analyzing homologous structures through time and/or between species. Three-dimensional models have long been recognized as a valuable way of providing a visual interpretation and overview of complex morphological data. We have used a recently developed method, optical projection tomography, to generate digital three-dimensional models of early human brain development. These models can be used both as frameworks, onto which normal or experimental gene expression data can be mapped, and as objects, within which topological morphological relationships can be investigated in silico. Gene expression patterns and selected morphological structures or boundaries can then be visualized individually or in different combinations in order to study their respective morphogenetic significance. Here, we review briefly the optical projection tomography method, placing it in the context of other methods used to generate developmental three dimensional models, and show the definition of some CNS anatomical domains within a Carnegie stage 19 human model. We also map the telencephalic EMX1 and PAX6 gene expression patterns to this model, corroborating for the first time the existence of a ventral pallium primordium in the telencephalon of human embryos, a distinct claustroamygdaloid histogenetic area comparable to the recently defined mouse primordium given that name [Puelles L, Kuwana E, Puelles E, Bulfone A, Shimamura K, Keleher J, Smiga S, Rubenstein JLR (2000) Pallial and subpallial derivatives in the embryonic chick and mouse telencephalon, traced by the expression of the genes Dlx-2, Emx-1, Nkx-2.1, Pax-6, and Tbr-1. J Comp Neurol 424:409-438; Puelles L, Martínez S, Martínez-de-la-Torre M, Rubenstein JLR (2004) Gene maps and related histogenetic domains in the forebrain and midbrain. In: The rat nervous system, 3rd ed (Paxinos G, ed), pp 3-25. San Diego: Academic Press].
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Affiliation(s)
- S Lindsay
- Institute of Human Genetics, University of Newcastle upon Tyne, International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
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Kerwin J, Scott M, Sharpe J, Puelles L, Robson SC, Martínez-de-la-Torre M, Ferran JL, Feng G, Baldock R, Strachan T, Davidson D, Lindsay S. 3 dimensional modelling of early human brain development using optical projection tomography. BMC Neurosci 2004; 5:27. [PMID: 15298700 PMCID: PMC514604 DOI: 10.1186/1471-2202-5-27] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Accepted: 08/06/2004] [Indexed: 11/28/2022] Open
Abstract
Background As development proceeds the human embryo attains an ever more complex three dimensional (3D) structure. Analyzing the gene expression patterns that underlie these changes and interpreting their significance depends on identifying the anatomical structures to which they map and following these patterns in developing 3D structures over time. The difficulty of this task greatly increases as more gene expression patterns are added, particularly in organs with complex 3D structures such as the brain. Optical Projection Tomography (OPT) is a new technology which has been developed for rapidly generating digital 3D models of intact specimens. We have assessed the resolution of unstained neuronal structures within a Carnegie Stage (CS)17 OPT model and tested its use as a framework onto which anatomical structures can be defined and gene expression data mapped. Results Resolution of the OPT models was assessed by comparison of digital sections with physical sections stained, either with haematoxylin and eosin (H&E) or by immunocytochemistry for GAP43 or PAX6, to identify specific anatomical features. Despite the 3D models being of unstained tissue, peripheral nervous system structures from the trigeminal ganglion (~300 μm by ~150 μm) to the rootlets of cranial nerve XII (~20 μm in diameter) were clearly identifiable, as were structures in the developing neural tube such as the zona limitans intrathalamica (core is ~30 μm thick). Fourteen anatomical domains have been identified and visualised within the CS17 model. Two 3D gene expression domains, known to be defined by Pax6 expression in the mouse, were clearly visible when PAX6 data from 2D sections were mapped to the CS17 model. The feasibility of applying the OPT technology to all stages from CS12 to CS23, which encompasses the major period of organogenesis for the human developing central nervous system, was successfully demonstrated. Conclusion In the CS17 model considerable detail is visible within the developing nervous system at a minimum resolution of ~20 μm and 3D anatomical and gene expression domains can be defined and visualised successfully. The OPT models and accompanying technologies for manipulating them provide a powerful approach to visualising and analysing gene expression and morphology during early human brain development.
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Affiliation(s)
- Janet Kerwin
- Institute of Human Genetics, University of Newcastle upon Tyne, International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Mark Scott
- Institute of Human Genetics, University of Newcastle upon Tyne, International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - James Sharpe
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, University of Murcia, Spain
| | - Stephen C Robson
- School of Surgical & Reproductive Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 4LP, UK
| | | | - Jose Luis Ferran
- Department of Human Anatomy and Psychobiology, University of Murcia, Spain
| | - Guangjie Feng
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Richard Baldock
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Tom Strachan
- Institute of Human Genetics, University of Newcastle upon Tyne, International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Duncan Davidson
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Susan Lindsay
- Institute of Human Genetics, University of Newcastle upon Tyne, International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
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Tonkin ET, Smith M, Eichhorn P, Jones S, Imamwerdi B, Lindsay S, Jackson M, Wang TJ, Ireland M, Burn J, Krantz ID, Carr P, Strachan T. A giant novel gene undergoing extensive alternative splicing is severed by a Cornelia de Lange-associated translocation breakpoint at 3q26.3. Hum Genet 2004; 115:139-48. [PMID: 15168106 PMCID: PMC4894837 DOI: 10.1007/s00439-004-1134-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Accepted: 04/19/2004] [Indexed: 10/26/2022]
Abstract
Cornelia de Lange syndrome (CdLS) is a rare developmental malformation syndrome characterised by mental handicap, growth retardation, distinctive facial features and limb reduction defects. The vast majority of CdLS cases are sporadic. We carried out a high density bacterial artificial chromosome (BAC) microarray comparative genome hybridisation screen but no evidence was found for a consistent pattern of microdeletion/microduplication. As an alternative, we focused on identifying chromosomal regions spanning associated translocation breakpoints. We prioritised the distal 3q region because of the occurrence, in a classical CdLS patient, of a de novo balanced translocation with a breakpoint at 3q26.3 and of reports of phenotypic overlap between cases of mild CdLS and individuals trisomic for the 3q26-q27 region. We show that the 3q26.3 breakpoint severs a previously uncharacterised giant gene, NAALADL2, containing at least 32 exons spanning 1.37 Mb. Northern blot analysis identified up to six different transcripts in the 1-10 kb range with strongest expression in kidney and placenta; embryonic expression was largely confined to duodenal and stomach endoderm, mesonephros, metanephros and pancreas. Transcript analysis identified extensive alternative splicing leading to multiple 5' and 3' untranslated regions and variable coding sequences. Multiple protein isoforms were defined by different N-terminal regions (with at least four alternative initiating methionine codons), and by differential protein truncation/use of alternative C-terminal sequences attributable to alternative splicing/polyadenylation. Outside the N-terminal regions, the predicted proteins showed significant homology to N-acetylated alpha-linked acidic dipeptidase and transferrin receptors. Mutation screening of NAALADL2 in a panel of CdLS patient DNA samples failed to identify patient-specific mutations. We discuss the possibility that the 3q26.3 translocation could nevertheless contribute to pathogenesis.
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Affiliation(s)
- Emma T. Tonkin
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Melanie Smith
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Piet Eichhorn
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Sandie Jones
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Burhan Imamwerdi
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Susan Lindsay
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Mike Jackson
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Tzu-Jou Wang
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Maggie Ireland
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - John Burn
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Ian D. Krantz
- Division of Human Genetics and Molecular Biology, The Children’s Hospital of Philadelphia and the University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Philippa Carr
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, CB10 1SA, UK
| | - Tom Strachan
- Institute of Human Genetics, International Centre for Life, University of Newcastle, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK, Tel.: +44-191-2418616 Fax: +44-191-2418666
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Hagan DM, Ross AJ, Strachan T, Lynch SA, Ruiz-Perez V, Wang YM, Scambler P, Custard E, Reardon W, Hassan S, Nixon P, Papapetrou C, Winter RM, Edwards Y, Morrison K, Barrow M, Cordier-Alex MP, Correia P, Galvin-Parton PA, Gaskill S, Gaskin KJ, Garcia-Minaur S, Gereige R, Hayward R, Homfray T. Mutation analysis and embryonic expression of the HLXB9 Currarino syndrome gene. Am J Hum Genet 2000; 66:1504-15. [PMID: 10749657 PMCID: PMC1378009 DOI: 10.1086/302899] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/1999] [Accepted: 02/21/2000] [Indexed: 11/03/2022] Open
Abstract
The HLXB9 homeobox gene was recently identified as a locus for autosomal dominant Currarino syndrome, also known as hereditary sacral agenesis (HSA). This gene specifies a 403-amino acid protein containing a homeodomain preceded by a very highly conserved 82-amino acid domain of unknown function; the remainder of the protein is not well conserved. Here we report an extensive mutation survey that has identified mutations in the HLXB9 gene in 20 of 21 patients tested with familial Currarino syndrome. Mutations were also detected in two of seven sporadic Currarino syndrome patients; the remainder could be explained by undetected mosaicism for an HLXB9 mutation or by genetic heterogeneity in the sporadic patients. Of the mutations identified in the 22 index patients, 19 were intragenic and included 11 mutations that could lead to the introduction of a premature termination codon. The other eight mutations were missense mutations that were significantly clustered in the homeodomain, resulting, in each patient, in nonconservative substitution of a highly conserved amino acid. All of the intragenic mutations were associated with comparable phenotypes. The only genotype-phenotype correlation appeared to be the occurrence of developmental delay in the case of three patients with microdeletions. HLXB9 expression was analyzed during early human development in a period spanning Carnegie stages 12-21. Signal was detected in the basal plate of the spinal cord and hindbrain and in the pharynx, esophagus, stomach, and pancreas. Significant spatial and temporal expression differences were evident when compared with expression of the mouse Hlxb9 gene, which may partly explain the significant human-mouse differences in mutant phenotype.
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Affiliation(s)
- D M Hagan
- Human Genetics Unit, School of Biochemistry and Genetics, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, United Kingdom
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Women's Health LiteratureWatch. J Womens Health (Larchmt) 1999; 8:129-38. [PMID: 10094091 DOI: 10.1089/jwh.1999.8.129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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