scholarly journals Bidirectional radial Ca2+ activity regulates neurogenesis and migration during early cortical column formation

2016 ◽  
Vol 2 (2) ◽  
pp. e1501733 ◽  
Author(s):  
Brian G. Rash ◽  
James B. Ackman ◽  
Pasko Rakic
Keyword(s):  
Brain Disorders ◽  
Cortical Column ◽  
Long Distance ◽  
Feedback Information ◽  
Radial Glial Cells ◽  
Column Formation ◽  
Radial Glial ◽  
And Migration ◽  
Radial Axis ◽  
Migratory Pathway

Cortical columns are basic cellular and functional units of the cerebral cortex that are malformed in many brain disorders, but how they initially develop is not well understood. Using an optogenetic sensor in the mouse embryonic forebrain, we demonstrate that Ca2+ fluxes propagate bidirectionally within the elongated fibers of radial glial cells (RGCs), providing a novel communication mechanism linking the proliferative and postmitotic zones before the onset of synaptogenesis. Our results indicate that Ca2+ activity along RGC fibers provides feedback information along the radial migratory pathway, influencing neurogenesis and migration during early column development. Furthermore, we find that this columnar Ca2+ propagation is induced by Notch and fibroblast growth factor activities classically implicated in cortical expansion and patterning. Thus, cortical morphogens and growth factors may influence cortical column assembly in part by regulating long-distance Ca2+ communication along the radial axis of cortical development.

Systematics, Biogeography, and Morphological Character Evolution of the Hemiepiphytic Subfamily Monsteroideae (Araceae)

2019 ◽  
Vol 104 (1) ◽  
pp. 33-48 ◽  
Author(s):  
Alejandro Zuluaga ◽  
Martin Llano ◽  
Ken Cameron
Keyword(s):  
Dna Sequences ◽  
Pacific Islands ◽  
R Package ◽  
Morphological Characters ◽  
Ancestral State ◽  
Seed Shape ◽  
Long Distance ◽  
The Pacific ◽  
And Migration ◽  
The Tropics

The subfamily Monsteroideae (Araceae) is the third richest clade in the family, with ca. 369 described species and ca. 700 estimated. It comprises mostly hemiepiphytic or epiphytic plants restricted to the tropics, with three intercontinental disjunctions. Using a dataset representing all 12 genera in Monsteroideae (126 taxa), and five plastid and two nuclear markers, we studied the systematics and historical biogeography of the group. We found high support for the monophyly of the three major clades (Spathiphylleae sister to Heteropsis Kunth and Rhaphidophora Hassk. clades), and for six of the genera within Monsteroideae. However, we found low rates of variation in the DNA sequences used and a lack of molecular markers suitable for species-level phylogenies in the group. We also performed ancestral state reconstruction of some morphological characters traditionally used for genera delimitation. Only seed shape and size, number of seeds, number of locules, and presence of endosperm showed utility in the classification of genera in Monsteroideae. We estimated ancestral ranges using a dispersal-extinction-cladogenesis model as implemented in the R package BioGeoBEARS and found evidence for a Gondwanan origin of the clade. One tropical disjunction (Monstera Adans. sister to Amydrium Schott–Epipremnum Schott) was found to be the product of a previous Boreotropical distribution. Two other disjunctions are more recent and likely due to long-distance dispersal: Spathiphyllum Schott (with Holochlamys Engl. nested within) represents a dispersal from South America to the Pacific Islands in Southeast Asia, and Rhaphidophora represents a dispersal from Asia to Africa. Future studies based on stronger phylogenetic reconstructions and complete morphological datasets are needed to explore the details of speciation and migration within and among areas in Asia.

War Captives, Left-Behind Wives, and Buddhist Nuns: Female Migrants in Early Medieval China (4th–6th Century CE)

2021 ◽  
pp. 1-18
Author(s):  
Wen-Yi Huang
Keyword(s):  
Fourth Century ◽  
Early Medieval ◽  
Long Distance ◽  
Textual Representations ◽  
Medieval China ◽  
Gender And Migration ◽  
Early Medieval China ◽  
And Migration ◽  
Northern Wei ◽  
Distance Travel

Abstract Using received texts and excavated funerary epitaphs, this article examines the intricacies of gender and migration in early medieval China by exploring women's long-distance mobility from the fourth century to the sixth century, when what is now known as China was divided by the Northern Wei and a succession of four southern states—the Eastern Jin, Liu-Song, Southern Qi, and Liang. I focus on three types of migration in which women participated during this period: war-induced migration, family reunification, and religious journeys. Based on this analysis, I propose answers to two important questions: the connection between migration and the state, and textual representations of migrants. Though the texts under consideration are usually written in an anecdotal manner, the references to women, I argue, both reveals nuances in perceptions of womanhood at the time and elucidates the contexts within—and through—which long-distance travel became possible for women.

scholarly journals The dematerialization of telecommunication: communication centres and peripheries in Europe and the world, 1850–1920

2007 ◽  
Vol 2 (3) ◽  
pp. 345-372 ◽  
Author(s):  
Roland Wenzlhuemer
Keyword(s):  
Telecommunication Network ◽  
Local Development ◽  
Global Communication ◽  
Communication Structure ◽  
Long Distance ◽  
Interregional Trade ◽  
Distance Information ◽  
History Information ◽  
And Migration ◽  
Global Data

AbstractInterregional communication has been a key constituent of the process of globalization since its very origins. For most of its history, information has moved between world regions and along the routes according to the rationales established by interregional trade and migration. The dematerialization of telecommunication in the late eighteenth and nineteenth century eventually detached long-distance information transmission from transport and transformed the global communication structure. New communication centres (and new peripheries) emerged. Some regions moved closer to the global data stream than others. It is still unclear how such different degrees of global connectivity impacted on local development. This essay contributes to the identification and valuation of global communication centres and peripheries in order to provide suitable candidates for future case studies. To this end, statistical data on the development of domestic telegraph networks in selected countries has been analysed and interpreted. In a second step, Social Network Analysis methods have been employed to measure the centrality of almost three hundred cities and towns in the European telecommunication network of the early twentieth century.‘You cannot not communicate.’Paul Watzlawick

scholarly journals On the interrelations between migration and commuting

Stanovnistvo ◽  
2013 ◽  
Vol 51 (1) ◽  
pp. 69-90 ◽  
Author(s):  
Vesna Lukic
Keyword(s):  
Real Estate ◽  
Labour Market ◽  
Real Estate Market ◽  
Modern Trend ◽  
Population Mobility ◽  
Rural Settlements ◽  
Long Distance ◽  
And Migration ◽  
Vojvodina Province

In this paper, we emphasise the significance of studying the interrelations between commuting and migration. The aim of the paper is to point out the factors which affect these interrelations (demographic and socio-economic characteristics of migrants and commuters, labour market, real estate market, information, life style, etc.), with the special emphasis on the role of commuting distance onto the chosen mobility type. Besides theorethical frameworks and results of the selected foreign researches up to date, the overview of research of interrelations between migration and commuting in Serbia has also been presented. While earlier studies conducted by Gawryszenski (1978), Termote (1980) and Reitsma&Vergoossen (1987) pointed to the replacement of migration types between each other within country, in recent literature the interaction between migration and commuting has been studied in a trans-boundary context of the contemporary EU. Modern trend of long distance commuting instead of migration and the concept of substitution/replacement regarding migration and commuting have also been discussed. In Serbia, there is a positive correlation between commuting outflows and immigration in rural settlements of Vojvodina province. Namely, commuting and migration are complement, which is the characteristic of both processes sub-urbanisation and ex-urbanisation (Lukic, 2012). In addition to ownership of real estate and previous migration experience, marital status influenced the chosen mobility type in Serbia as well. Adjustment to changes of Serbian labour market is mostly conducted via migration (Miletic, Lukic, Miljanovic, 2011). Interrelations between migration and commuting are very significant due to the tendency of transformation of some commuters into migrants. This process has its consequences, both on demographic as well as the overall socio-economic development of the area of commuters? origin and destination. However, even though the surveys conducted in Serbia during the 1980s showed that around 30 per cent of commuters expressed desire to move to their place of work, the degree of realization of these intentions remained unknown. While in some countries traffic studies and data from the management of the enterprises are used as sources of data on commuting, the studies on the commuter population in Serbia are based solely onto two types of data sources. These are census and poll surveys. Although they have more potential than the official statistics for the analysis of the links between migration and commuting and other characteristics of commuters, poll surveys on this topic in Serbia are relatively rare due to financial and organizational obstacles. Indeed, the last major survey was conducted in the 1980s. Therefore, even though the interrelations between migration and commuting have been confirmed, there is still a lot of space for their research indicating the need for further methodology developments in researching these types of population mobility.

scholarly journals Crucial Roles of the Arp2/3 Complex during Mammalian Corticogenesis

2015 ◽  
Author(s):  
Pei-Shan Wang ◽  
Fu-Sheng Chou ◽  
Fengli Guo ◽  
Praveen Suraneni ◽  
Sheng Xia ◽  
...  
Keyword(s):  
Cell Fate ◽  
Membrane Trafficking ◽  
Neuronal Migration ◽  
Neuronal Cell ◽  
Leading Edge ◽  
Radial Glial Cells ◽  
A Cell ◽  
Radial Glial ◽  
Altered Cell ◽  
Actin Nucleator

The polarity and organization of radial glial cells (RGCs), which serve as both stem cells and scaffolds for neuronal migration, are crucial for cortical development. However, the cytoskeletal mechanisms that drive radial glial outgrowth and maintain RGC polarity remain poorly understood. Here, we show that the Arp2/3 complex, the unique actin nucleator that produces branched actin networks, plays essential roles in RGC polarity and morphogenesis. Disruption of the Arp2/3 complex in RGCs retards process outgrowth toward the basal surface and impairs apical polarity and adherens junctions. Whereas the former is correlated with abnormal actin-based leading edge, the latter is consistent with blockage in membrane trafficking. These defects result in altered cell fate, disrupted cortical lamination and abnormal angiogenesis. In addition, we present evidence that the Arp2/3 complex is a cell-autonomous regulator of neuronal migration. Our data suggest that Arp2/3-mediated actin assembly may be particularly important for neuronal cell motility in soft or poorly adhesive matrix environment.

North European Rock Art

2017 ◽  
Author(s):  
Joakim Goldhahn
Keyword(s):  
Bronze Age ◽  
Iron Age ◽  
Rock Art ◽  
Northern Europe ◽  
Long Distance ◽  
Migration Period ◽  
Farming Communities ◽  
And Migration ◽  
The Bronze Age

This chapter offers a long-term perspective on rock art in northern Europe. It first provides an overview of research on the rock art traditions of northern Europe before discussing the societies and cultures that created such traditions. It then considers examples of rock art made by hunter-gatherer societies in northern Europe, focusing on the first rock art boom related to Neolithization. It also examines the second rock art boom, which was associated with social and religious changes within farming communities that took place around 1600–1400 bc. The chapter concludes by analysing the breakdown of long-distance networks in the transition from the Bronze Age to the Iron Age and its consequences for the making of rock art within the southern traditions, as well as the use of rock art sites during the Pre-Roman Iron Age, Roman Iron Age, and Migration Period.

Topical Review: Neuronal Migration in Cortical Development

2004 ◽  
Vol 19 (3) ◽  
pp. 274-279
Author(s):  
Shigeaki Kanatani ◽  
Hidenori Tabata ◽  
Kazunori Nakajima
Keyword(s):  
Neuronal Migration ◽  
Radial Glia ◽  
Asymmetric Cell Division ◽  
Time Lapse ◽  
Radial Glial Cells ◽  
Daughter Cells ◽  
Radial Glial ◽  
Time Lapse Imaging ◽  
Mitotic Behavior

Cortical formation in the developing brain is a highly complicated process involving neuronal production (through symmetric or asymmetric cell division) interaction of radial glia with neuronal migration, and multiple modes of neuronal migration. It has been convincingly demonstrated by numerous studies that radial glial cells are neural stem cells. However, the processes by which neurons arise from radial glia and migrate to their final destinations in vivo are not yet fully understood. Recent studies using time-lapse imaging of neuronal migration are giving investigators an increasingly more detailed understanding of the mitotic behavior of radial glia and the migrating behavior of their daughter cells. In this review, we describe recent progress in elucidating neuronal migration in brain formation and how neuronal migration is disturbed by mutations in genes that control this process. ( J Child Neurol 2005;20:274—279).

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