ORCID Profile
0000-0003-3558-8222
Current Organisations
University of Queensland
,
Aalto University
,
University of South Australia
,
University of Melbourne
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Zoology | Curriculum and Pedagogy Theory and Development | Education Systems | Animal Neurobiology | Other Education | Social Change | Higher Education | Urban and Regional Studies (excl. Planning) | Secondary Education | Curriculum Studies Not Elsewhere Classified | Professional Development Of Teachers Not Elsewhere Classified | Evolution of Developmental Systems | Animal Cell and Molecular Biology | Animal Developmental and Reproductive Biology | Curriculum and Pedagogy | Specialist Studies in Education | Policy and Administration | Neurosciences | Teacher Education and Professional Development of Educators | Central Nervous System | Gene and Molecular Therapy | Educational Policy, Administration And Management | Education Systems not elsewhere classified
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Biological Sciences | Secondary education | Education and training not elsewhere classified | Teaching and Instruction not elsewhere classified | Equity and Access to Education | Nervous System and Disorders | Law, Politics and Community Services not elsewhere classified | Professions and Professionalisation | Syllabus and Curriculum Development | Education and Training Systems Policies and Development | School/Institution Policies and Development |
Related Links
Publications
The evolution, formation and connectivity of the anterior commissure
Publisher: Elsevier BV
Date: 10-2021
DOI: 10.1016/J.SEMCDB.2021.04.009
Abstract: The anterior commissure is the most ancient of the forebrain interhemispheric connections among all vertebrates. Indeed, it is the predominant pallial commissure in all non-eutherian vertebrates, universally subserving basic functions related to olfaction and survival. A key feature of the anterior commissure is its ability to convey connections from erse brain areas, such as most of the neocortex in non-eutherian mammals, thereby mediating the bilateral integration of erse functions. Shared developmental mechanisms between the anterior commissure and more evolutionarily recent commissures, such as the corpus callosum in eutherians, have led to the hypothesis that the former may have been a precursor for additional expansion of commissural circuits. However, differences between the formation of the anterior commissure and other telencephalic commissures suggest that independent developmental mechanisms underlie the emergence of these connections in extant species. Here, we review the developmental mechanisms and connectivity of the anterior commissure across evolutionarily distant species, and highlight its potential functional importance in humans, both in the course of normal neurodevelopment, and as a site of plastic axonal rerouting in the absence or damage of other connections.
DCC regulates astroglial development essential for telencephalic morphogenesis and corpus callosum formation
Publisher: eLife Sciences Publications, Ltd
Date: 06-04-2018
DOI: 10.7554/ELIFE.61769
Abstract: The forebrain hemispheres are predominantly separated during embryogenesis by the interhemispheric fissure (IHF). Radial astroglia remodel the IHF to form a continuous substrate between the hemispheres for midline crossing of the corpus callosum (CC) and hippoc al commissure (HC). DCC and NTN1 are molecules that have an evolutionarily conserved function in commissural axon guidance. The CC and HC are absent in Dcc and Ntn1 knockout mice, while other commissures are only partially affected, suggesting an additional aetiology in forebrain commissure formation. Here, we find that these molecules play a critical role in regulating astroglial development and IHF remodelling during CC and HC formation. Human subjects with DCC mutations display disrupted IHF remodelling associated with CC and HC malformations. Thus, axon guidance molecules such as DCC and NTN1 first regulate the formation of a midline substrate for dorsal commissures prior to their role in regulating axonal growth and guidance across it.
Negotiating university equity from Indigenous standpoints: A shaky bridge
Publisher: Informa UK Limited
Date: 22-11-2012
Non-uniform temporal scaling of developmental processes in the mammalian cortex
Publisher: Springer Science and Business Media LLC
Date: 23-09-2023
The anatomy, organisation and development of contralateral callosal projections of the mouse somatosensory cortex
Publisher: SAGE Publications
Date: 2017
Abstract: Alterations in the development of neuronal connectivity can result in dramatic outcomes for brain function. In the cerebral cortex, most sensorimotor and higher-order functions require coordination between precise regions of both hemispheres through the axons that form the corpus callosum. However, little is known about how callosal axons locate and innervate their contralateral targets. Here, we use a combination of in utero electroporation, retrograde tracing, sensory deprivation and high-resolution axonal quantification to investigate the development, organisation and activity dependence of callosal axons arising from the primary somatosensory cortex of mice. We show that distinct contralateral projections arise from different neuronal populations and form homotopic and heterotopic circuits. Callosal axons innervate the contralateral hemisphere following a dorsomedial to ventrolateral and region-specific order. Furthermore, we identify two periods of region- and layer-specific developmental exuberance that correspond to initial callosal axon innervation and subsequent arborisation. Early sensory deprivation affects only the latter of these events. Taken together, these results reveal the main developmental events of contralateral callosal targeting and may aid future understanding of the formation and pathologies of brain connectivity.
Molecular Switches in the Development and Fate Specification of Vomeronasal Neurons: Figure 1.
Publisher: Society for Neuroscience
Date: 07-12-2011
The contemporary challenge of activism as curriculum work
Publisher: Informa UK Limited
Date: 28-02-2022
Evolution of Developmental Timing as a Driving Force of Brain Diversity
Publisher: S. Karger AG
Date: 2022
DOI: 10.1159/000524334
Teachers and students as researchers: rebuilding curriculum inquiry for the future
Publisher: Springer Science and Business Media LLC
Date: 04-2022
Undergraduate teaching of evolution in chile: more than natural selection
Publisher: SciELO Agencia Nacional de Investigacion y Desarrollo (ANID)
Date: 03-2005
Shared and differential traits in the accessory olfactory bulb of caviomorph rodents with particular reference to the semiaquatic capybara
Publisher: Wiley
Date: 25-02-2011
Astroglial-mediated remodeling of the interhemispheric midline during telencephalic development is exclusive to eutherian mammals
Publisher: Springer Science and Business Media LLC
Date: 30-05-2017
Bilateral visual projections exist in non-teleost bony fish and predate the emergence of tetrapods
Publisher: American Association for the Advancement of Science (AAAS)
Date: 09-04-2021
Abstract: In primates, visual connections are bilateral: Each eye sends neural connections to both sides of the brain. Vigouroux et al. looked at the evolutionary underpinnings of the bilateral visual system. A close look at the connections between the retina and the brain in a variety of fish species representing a span of evolutionary ergence revealed that contralateral connections seem to be universal. The ipsilateral connections, which add to the contralateral connections to form a bilateral visual system, arrived later in evolution but before the transition to land-dwelling animals. Science , this issue p. 150
The contemporary challenge of activism as curriculum work
Publisher: Routledge
Date: 08-09-2023
The Connection between the Radio Jet and the γ-ray Emission in the Radio Galaxy 3C 120 and the Blazar CTA 102
Publisher: MDPI AG
Date: 27-09-2016
A pan-mammalian map of interhemispheric brain connections predates the evolution of the corpus callosum
Publisher: Proceedings of the National Academy of Sciences
Date: 04-09-2018
Abstract: The neocortex is a hallmark of mammalian evolution, and connections between both hemispheres integrate bilateral functions. In eutherians (e.g., rodents and humans), interhemispheric circuits course via the corpus callosum and share a similar connectome throughout species. Noneutherian mammals (i.e., monotremes and marsupials), however, did not evolve a corpus callosum therefore, whether the eutherian connectome arose as consequence of callosal evolution or instead reflects ancient connectivity principles remains unknown. We studied monotreme and marsupial interhemispheric neocortical connectomes and compared these with eutherian datasets. This revealed interhemispheric connectivity features shared across mammals, with or without a corpus callosum, suggesting that an ancient connectome originated at least 80 million years before callosal evolution.
In search of common developmental and evolutionary origin of the claustrum and subplate
Publisher: Wiley
Date: 06-05-2020
DOI: 10.1002/CNE.24922
Development of body, head and brain features in the Australian fat-tailed dunnart (Sminthopsis crassicaudata; Marsupialia: Dasyuridae); A postnatal model of forebrain formation
Publisher: Public Library of Science (PLoS)
Date: 07-09-2017
An ethical re-framing of curriculum for sustainability education
Publisher: Springer Science and Business Media LLC
Date: 04-2020
Conditions for broad-based curriculum scholarship: reflections on Victorian infrastructure for supporting curriculum workers in the 1970s and 1980s
Publisher: Springer Science and Business Media LLC
Date: 28-03-2018
Part-Time Schooling
Publisher: SAGE Publications Ltd
Date: 2009
DRAXIN regulates interhemispheric fissure remodelling to influence the extent of corpus callosum formation
Publisher: eLife Sciences Publications, Ltd
Date: 04-05-2021
DOI: 10.7554/ELIFE.61618
Abstract: Corpus callosum dysgenesis (CCD) is a congenital disorder that incorporates either partial or complete absence of the largest cerebral commissure. Remodelling of the interhemispheric fissure (IHF) provides a substrate for callosal axons to cross between hemispheres, and its failure is the main cause of complete CCD. However, it is unclear whether defects in this process could give rise to the heterogeneity of expressivity and phenotypes seen in human cases of CCD. We identify incomplete IHF remodelling as the key structural correlate for the range of callosal abnormalities in inbred and outcrossed BTBR mouse strains, as well as in humans with partial CCD. We identify an eight base-pair deletion in Draxin and misregulated astroglial and leptomeningeal proliferation as genetic and cellular factors for variable IHF remodelling and CCD in BTBR strains. These findings support a model where genetic events determine corpus callosum structure by influencing leptomeningeal-astroglial interactions at the IHF.
Detection statistics of the RadioAstron AGN survey
Publisher: Elsevier BV
Date: 2020
Cortical activity emerges in region-specific patterns during early brain development
Publisher: Cold Spring Harbor Laboratory
Date: 19-02-2023
DOI: 10.1101/2023.02.18.529078
Abstract: The development of precise neural circuits in the brain requires spontaneous patterns of neural activity prior to functional maturation. In the rodent cerebral cortex patchwork and wave patterns of activity develop in somatosensory and visual regions, respectively, and are present at birth. However, whether such activity patterns occur in non-eutherian mammals, as well as when and how they arise during development remain open questions relevant to understand brain formation in health and disease. Since the onset of patterned cortical activity is challenging to study prenatally in eutherians, here we offer a new approach in a minimally invasive manner using marsupial dunnarts, whose cortex forms postnatally. We discovered similar patchwork and travelling waves in the dunnart somatosensory and visual cortices at stage 27 (equivalent to newborn mice), and examined progressively earlier stages of development to determine their onset and how they first emerge. We observed that these patterns of activity emerge in a region-specific and sequential manner, becoming evident as early as stage 24 in somatosensory and stage 25 in visual cortices (equivalent to embryonic day 16 and 17, respectively, in mice), as cortical layers establish and thalamic axons innervate the cortex. In addition to sculpting synaptic connections of existing circuits, evolutionarily conserved patterns of neural activity could therefore help regulate early events in cortical development. Region-specific patterns of neural activity are present at birth in rodents and are thought to refine synaptic connections during critical periods of cerebral cortex development. Marsupials are born much more immature than rodents, allowing the investigation of how these patterns arise in vivo. We discovered that cortical activity patterns are remarkably similar in marsupial dunnarts and rodents, and that they emerge very early, before cortical neurogenesis is complete. Moreover, they arise from the outset in different patterns specific to somatosensory and visual areas (i.e., patchworks and waves) indicating they may also play evolutionarily conserved roles in cortical regionalization during development.
Clade-specific forebrain cytoarchitectures of the extinct Tasmanian tiger
Publisher: Proceedings of the National Academy of Sciences
Date: 31-07-2023
Abstract: The thylacine, or Tasmanian tiger, is the largest of modern-day carnivorous marsupials and was hunted to extinction by European settlers in Australia. Its physical resemblance to eutherian wolves is a striking ex le of evolutionary convergence to similar ecological niches. However, whether the neuroanatomical organization of the thylacine brain resembles that of canids and how it compares with other mammals remain unknown due to the scarcity of available s les. Here, we gained access to a century-old hematoxylin-stained histological series of a thylacine brain, digitalized it at high resolution, and compared its forebrain cellular architecture with 34 extant species of monotremes, marsupials, and eutherians. Phylogenetically informed comparisons of cortical folding, regional volumes, and cell sizes and densities across cortical areas and layers provide evidence against brain convergences with canids, instead demonstrating features typical of marsupials, and more specifically Dasyuridae, along with traits that scale similarly with brain size across mammals. Enlarged olfactory, limbic, and neocortical areas suggest a small-prey predator and/or scavenging lifestyle, similar to extant quolls and Tasmanian devils. These findings are consistent with a nonuniformity of trait convergences, with brain traits clustering more with phylogeny and head/body traits with lifestyle. By making this resource publicly available as rapid web-accessible, hierarchically organized, multiresolution images for perpetuity, we anticipate that additional comparative insights might arise from detailed studies of the thylacine brain and encourage researchers and curators to share, annotate, and preserve understudied material of outstanding biological relevance.
Synthesis and Characterization of Plasmonic Resonant Guided Wave Networks
Publisher: American Chemical Society (ACS)
Date: 27-05-2014
DOI: 10.1021/NL500694C
Abstract: Composed of optical waveguides and power-splitting waveguide junctions in a network layout, resonant guided wave networks (RGWNs) split an incident wave into partial waves that resonantly interact within the network. Resonant guided wave networks have been proposed as nanoscale distributed optical networks (Feigenbaum and Atwater, Phys. Rev. Lett. 2010, 104, 147402) that can function as resonators and color routers (Feigenbaum et al. Opt. Express 2010, 18, 25584-25595). Here we experimentally characterize a plasmonic resonant guided wave network by demonstrating that a 90° waveguide junction of two v-groove channel plasmon polariton (CPP) waveguides operates as a compact power-splitting element. Combining these plasmonic power splitters with CPP waveguides in a network layout, we characterize a prototype plasmonic nanocircuit composed of four v-groove waveguides in an evenly spaced 2 × 2 configuration, which functions as a simple, compact optical logic device at telecommunication wavelengths, routing different wavelengths to separate transmission ports due to the resulting network resonances. The resonant guided wave network exhibits the full permutation of Boolean on/off values at two output ports and can be extended to an eight-port configuration, unlike other photonic crystal and plasmonic add/drop filters, in which only two on/off states are accessible.
Students at risk and NAPLAN: The collateral damage
Publisher: Routledge
Date: 06-11-2016
Introduction - knowledge-and-ethics: strong curriculum values both, together
Publisher: Springer Science and Business Media LLC
Date: 04-2020
Deterioration of the Gαo Vomeronasal Pathway in Sexually Dimorphic Mammals
Publisher: Public Library of Science (PLoS)
Date: 19-10-2011
Divergent evolution of developmental timing in the neocortex revealed by marsupial and eutherian transcriptomes.
Publisher: The Company of Biologists
Date: 02-2022
DOI: 10.1242/DEV.200212
Abstract: Only mammals evolved a neocortex, which integrates sensory-motor and cognitive functions. Significant ersifications in the cellular composition and connectivity of the neocortex occurred between the two main therian groups: marsupials and eutherians. However, the developmental mechanisms underlying these ersifications are largely unknown. Here, we compared the neocortical transcriptomes of Sminthopsis crassicaudata, a mouse-sized marsupial, with those of eutherian mice at two developmentally equivalent time points corresponding to deeper and upper layer neuron generation. Enrichment analyses revealed more mature gene networks in marsupials at the early stage, which reverted at the later stage, suggesting a more precocious but protracted neuronal maturation program relative to birth timing of cortical layers. We ranked genes expressed in different species and identified important differences in gene expression rankings between species. For ex le, genes known to be enriched in upper-layer cortical projection neuron subtypes, such as Cux1, Lhx2 and Satb2, likely relate to corpus callosum emergence in eutherians. These results show molecular heterochronies of neocortical development in Theria, and highlight changes in gene expression and cell type composition that may underlie neocortical evolution and ersification. This article has an associated 'The people behind the papers' interview.
Transcriptional control of long-range cortical projections
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.CONB.2018.05.005
Abstract: Long-range projection neurons of the neocortex form the major tracts of the mammalian brain and are crucial for sensory-motor, associative and executive functions. Development of such circuits involves neuronal proliferation, specification and migration, as well as axonal elongation, navigation and targeting, where growing axons encounter multiple guidance cues and integrate these signals to execute guidance decisions. The complexity of axon guidance mechanisms in the formation of long-range neuronal projections has suggested that they might be under control of transcription factors, which are DNA-binding proteins that regulate the expression of downstream genes. Here we discuss recent advances in our understanding of the control of axon guidance by transcriptional regulation, as well as future directions for the elucidation of the mechanisms and pathological relevance of this process.
Transposition and Intermingling of Gαi2 and Gαo Afferences into Single Vomeronasal Glomeruli in the Madagascan Lesser Tenrec Echinops telfairi
Publisher: Public Library of Science (PLoS)
Date: 24-11-2009
Aggravating Students’ Structural Vulnerabilities: Cruel Miseries of Selection for ‘Success’ in Schools with Power-Marginalised Intake
Publisher: Springer Science and Business Media LLC
Date: 09-2021
MOJAVE. XIX. Brightness Temperatures and Intrinsic Properties of Blazar Jets
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We present multiepoch, parsec-scale core brightness temperature observations of 447 active galactic nucleus (AGN) jets from the MOJAVE and 2 cm Survey programs at 15 GHz from 1994 to 2019. The brightness temperature of each jet over time is characterized by its median value and variability. We find that the range of median brightness temperatures for AGN jets in our s le is much larger than the variations within in idual jets, consistent with Doppler boosting being the primary difference between the brightness temperatures of jets in their median state. We combine the observed median brightness temperatures with apparent jet speed measurements to find the typical intrinsic Gaussian brightness temperature of 4.1( ± 0.6) × 10 10 K, suggesting that jet cores are at or below equipartition between particle and magnetic field energy in their median state. We use this value to derive estimates for the Doppler factor for every source in our s le. For the 309 jets with both apparent speed and brightness temperature data, we estimate their Lorentz factors and viewing angles to the line of sight. Within the BL Lac optical class, we find that high-synchrotron-peaked BL Lacs have smaller Doppler factors, lower Lorentz factors, and larger angles to the line of sight than intermediate and low-synchrotron-peaked BL Lacs. We confirm that AGN jets with larger Doppler factors measured in their parsec-scale radio cores are more likely to be detected in γ rays, and we find a strong correlation between γ -ray luminosity and Doppler factor for the detected sources.
Evolution and development of interhemispheric connections in the vertebrate forebrain
Publisher: Frontiers Media SA
Date: 14-07-2014
Evolution of Telencephalic Commissures: Conservation and Change of Developmental Systems in the Origin of Brain Wiring Novelties
Publisher: Elsevier
Date: 2017
Researching for social justice: contextual, conceptual and methodological challenges
Publisher: Informa UK Limited
Date: 09-2009
Cognitive Ecology in Hummingbirds: The Role of Sexual Dimorphism and Its Anatomical Correlates on Memory
Publisher: Public Library of Science (PLoS)
Date: 05-03-2014
Author response: DRAXIN regulates interhemispheric fissure remodelling to influence the extent of corpus callosum formation
Publisher: eLife Sciences Publications, Ltd
Date: 12-03-2021
Re‐imagining doctoral education: Professional Doctorates and beyond
Publisher: Informa UK Limited
Date: 06-2009
Opening school walls to funds of knowledge
Publisher: Routledge
Date: 10-05-2023
Erratum: “Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. XVIII. Kinematics and Inner Jet Evolution of Bright Radio-loud Active Galaxies” (2021, ApJ, 923, 30)
Publisher: American Astronomical Society
Date: 05-2023
Educating for Futures in Marginalized Regions: A sociological framework for rethinking and researching aspirations
Publisher: Informa UK Limited
Date: 08-10-2013
Heterogeneities of size and sexual dimorphism between the subdomains of the lateral-innervated accessory olfactory bulb (AOB) of Octodon degus (Rodentia: Hystricognathi)
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.BBR.2008.11.009
Abstract: The vomeronasal system (VNS) of rodents participates in the regulation of a variety of social and sexual behaviours related to semiochemical communication. All rodents studied so far possess two parallel pathways from the vomeronasal organ (VNO) to the accessory olfactory bulb (AOB). These segregated afferences express either Gi2 or Go protein alpha-subunits and innervate the rostral or caudal half of the AOB, respectively. In muroid rodents, such as rats and mice, both sub isions of the AOB are of similar proportions as there is no anatomical feature indicative of the segregation, histochemical detection has been required to portray its boundary. We studied the AOB of Octodon degus, a diurnal caviomorph rodent endemic to central Chile, and found several distinctive traits not reported in a rodent before: (i) the vomeronasal nerve innervates the AOB from its lateral aspect, in opposition to the medial innervation described in rabbits and muroids, (ii) an indentation that spans all layers delimits the boundary between the rostral and caudal AOB sub isions (rAOB and cAOB, respectively), (iii) the rAOB is twice the size of the cAOB and features more and larger glomeruli, and (iv) the rAOB, but not the cAOB, shows male-biased sexual dimorphisms in size and number of glomeruli, while the cAOB, but not the rAOB, shows a male-biased dimorphism in mitral cell density. The heterogeneities we describe here within AOB subdomains suggest that these segregated regions may engage in distinct operationalities. We discuss our results in relation to conspecific semiochemical communication in O. degus, and present it as a new animal model for the study of VNS neurobiology and evolution.
Community-oriented pre-service teachers
Publisher: Routledge
Date: 07-02-2020
Cortical activity emerges in region-specific patterns during early brain development
Publisher: Proceedings of the National Academy of Sciences
Date: 22-05-2023
Abstract: The development of precise neural circuits in the brain requires spontaneous patterns of neural activity prior to functional maturation. In the rodent cerebral cortex, patchwork and wave patterns of activity develop in somatosensory and visual regions, respectively, and are present at birth. However, whether such activity patterns occur in noneutherian mammals, as well as when and how they arise during development, remain open questions relevant for understanding brain formation in health and disease. Since the onset of patterned cortical activity is challenging to study prenatally in eutherians, here we offer an approach in a minimally invasive manner using marsupial dunnarts, whose cortex forms postnatally. We discovered similar patchwork and travelling waves in the dunnart somatosensory and visual cortices at stage 27 (equivalent to newborn mice) and examined earlier stages of development to determine the onset of these patterns and how they first emerge. We observed that these patterns of activity emerge in a region-specific and sequential manner, becoming evident as early as stage 24 in somatosensory and stage 25 in visual cortices (equivalent to embryonic day 16 and 17, respectively, in mice), as cortical layers establish and thalamic axons innervate the cortex. In addition to sculpting synaptic connections of existing circuits, evolutionarily conserved patterns of neural activity could therefore help regulate other early events in cortical development.
Young people pursuing futures: making identity labors curricular
Publisher: Informa UK Limited
Date: 24-08-2021
Thalamic Afferents and Neocortical Arealization: An Ongoing Journey
Publisher: Society for Neuroscience
Date: 28-08-2013
Women teachers in Hong Kong: stories of changing gendered identities
Publisher: Informa UK Limited
Date: 06-2010
Author response: DCC regulates astroglial development essential for telencephalic morphogenesis and corpus callosum formation
Publisher: eLife Sciences Publications, Ltd
Date: 02-04-2021
MOJAVE. XVII. Jet Kinematics and Parent Population Properties of Relativistically Beamed Radio-loud Blazars
Publisher: American Astronomical Society
Date: 21-03-2019
Changing Teaching and Teacher Education in the ‘Anthropocene’
Publisher: On Education. Journal for Research and Debate
Date: 04-2019
Mutual influences between the main olfactory and vomeronasal systems in development and evolution
Publisher: Frontiers Media SA
Date: 2012
Transnational Curriculum Inquiry in a Changing World
Publisher: Springer International Publishing
Date: 2021
Differential timing of a conserved transcriptional network underlies divergent cortical projection routes across mammalian brain evolution
Publisher: Proceedings of the National Academy of Sciences
Date: 20-04-2020
Abstract: The corpus callosum connects left and right cerebral cortices, integrating sensory-motor and associative functions, and is the largest connection in the human brain. While all mammals have a cerebral cortex, only eutherians evolved a corpus callosum. However, how this occurred remains largely unknown. We compared transcription factors that control subcerebral versus callosal neuron projection fates in eutherians and marsupials and found remarkably high similarity of their gene sequences and functions. However, expression of the callosal gene SATB2 was delayed in mice relative to dunnarts, and premature overexpression was sufficient for reversion to an ancestral-like brain phenotype. Our results suggest that transcriptional heterochrony might have influenced callosal evolution, and that complex traits can originate by differential deployment of existing regulatory genes.
Multiple events of gene manipulation via in pouch electroporation in a marsupial model of mammalian forebrain development
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.JNEUMETH.2017.09.004
Abstract: The technique of in utero electroporation has been widely used in eutherians, such as mice and rats, to investigate brain development by selectively manipulating gene expression in specific neuronal populations. A major challenge, however, is that surgery is required to access the embryos, affecting animal survival and limiting the number of times it can be performed within the same litter. Marsupials are born at an early stage of brain development as compared to eutherians. Forebrain neurogenesis occurs mostly postnatally, allowing electroporation to be performed while joeys develop attached to the teat. Here we describe the method of in pouch electroporation using the Australian marsupial fat-tailed dunnart (Sminthopsis crassicaudata, Dasyuridae). In pouch electroporation is minimally invasive, quick, successful and anatomically precise. Moreover, as no surgery is required, it can be performed several times in the same in idual, and littermates can undergo independent treatments. As compared to in utero electroporation in rodents, in pouch electroporation in marsupials offers unprecedented opportunities to study brain development in a minimally invasive manner. Continuous access to developing joeys during a protracted period of cortical development allows multiple and independent genetic manipulations to study the interaction of different systems during brain development. In pouch electroporation in marsupials offers an excellent in vivo assay to study forebrain development and evolution. By combining developmental, functional and comparative approaches, this system offers new avenues to investigate questions of biological and medical relevance, such as the precise mechanisms of brain wiring and the organismic and environmental influences on neural circuit formation.
Monitoring Of Jets in Active Galactic Nuclei with VLBA Experiments. XVIII. Kinematics and Inner Jet Evolution of Bright Radio-loud Active Galaxies
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We have analyzed the parsec-scale jet kinematics of 447 bright radio-loud active active galactic nuclei (AGN), based on 15 GHz Very Long Baseline Array (VLBA) data obtained between 1994 August 31 and 2019 August 4. We present new total intensity and linear polarization maps obtained between 2017 January 1 and 2019 August 4 for 143 of these AGN. We tracked 1923 bright features for five or more epochs in 419 jets. The majority (60%) of the well-s led jet features show either accelerated or nonradial motion. In 47 jets there is at least one nonaccelerating feature with an unusually slow apparent speed. Most of the jets show variations of 10°–50° in their inner jet position angle (PA) over time, although the overall distribution has a continuous tail out to 200°. AGN with spectral energy distributions peaked at lower frequencies tend to have more variable PAs, with BL Lac objects being less variable than quasars. The Fermi Large Area Telescope (LAT) gamma-ray-associated AGN also tend to have more variable PAs than the non-LAT AGN in our s le. We attribute these trends to smaller viewing angles for the lower spectral peaked and LAT-associated jets. We identified 13 AGN where multiple features emerge over decade-long periods at systematically increasing or decreasing PAs. Since the ejected features do not fill the entire jet cross section, this behavior is indicative of a precessing flow instability near the jet base. Although some jets show indications of oscillatory PA evolution, we claim no bona fide cases of periodicity since the fitted periods are comparable to the total VLBA time coverage.
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