scholarly journals Regulation of Temporal Identity Transitions in Drosophila Neuroblasts

2005 ◽  
Vol 8 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Ruth Grosskortenhaus ◽  
Bret J. Pearson ◽  
Amanda Marusich ◽  
Chris Q. Doe
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pierre Mattar ◽  
Christine Jolicoeur ◽  
Thanh Dang ◽  
Sujay Shah ◽  
Brian S. Clark ◽  
...  

AbstractNeural progenitor cells undergo identity transitions during development to ensure the generation different types of neurons and glia in the correct sequence and proportions. A number of temporal identity factors that control these transitions in progenitor competence have been identified, but the molecular mechanisms underlying their function remain unclear. Here, we asked how Casz1, the mammalian orthologue of Drosophila castor, regulates competence during retinal development. We show that Casz1 is required to control the transition between neurogenesis and gliogenesis. Using BioID proteomics, we reveal that Casz1 interacts with the nucleosome remodeling and deacetylase (NuRD) complex in retinal cells. Finally, we show that both the NuRD and the polycomb repressor complexes are required for Casz1 to promote the rod fate and suppress gliogenesis. As additional temporal identity factors have been found to interact with the NuRD complex in other contexts, we propose that these factors might act through this common biochemical process to regulate neurogenesis.


This chapter reviews the book Stepmother Russia, Foster Mother America: Identity Transitions in the New Odessa Jewish Commune, Odessa, Oregon, New York, 1881–1891 (2014), by Theodore H. Friedgut, together with Israel Mandelkern, Recollections of a Communist (edited and annotated by Theodore H. Friedgut). Stepmother Russia, Foster Mother America is a two-in-one volume that explores an obscure episode in the history of the Jews in the late nineteenth century while at the same time connecting much of its content to the author’s own life experience as a son of western Canada’s Jewish farming colonies and, later, as an ideologically driven halutz on an Israeli kibbutz. Stepmother Russia, Foster Mother America retells one branch of the mostly forgotten history of the Am Olam agricultural movement and brings a new layer into the discussion of global Jewish agrarianism, while Recollections of a Communist offers an edited and annotated version of a memoir written by Mandelkern.


2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Austin Seroka ◽  
Rita M. Yazejian ◽  
Sen-Lin Lai ◽  
Chris Q. Doe

2016 ◽  
Vol 8 (2) ◽  
pp. 98-116 ◽  
Author(s):  
Kate V. Lewis ◽  
Marcus Ho ◽  
Candice Harris ◽  
Rachel Morrison

Purpose This paper aims to report an empirically grounded theoretical framework within which to understand the role of entrepreneurial identity development in the discovery, development and exploitation of opportunity, and to elaborate on how these identity transitions both mobilise and constrain female entrepreneurs. Design/methodology/approach A qualitative case study-based research design was used in this study. Primary and secondary data were collected from eight female participants (all of whom can be categorised as “mumpreneurs”) and analysed to inform the theoretical framework that is the foundation of the paper. Findings The authors describe how identity conflict, role congruence and reciprocal identity creation play a critical role in venture creation as a form of entrepreneurship. Drawing on the constructs of identification, self-verification and identity enactment, the authors build a theoretical framework for understanding entrepreneurial identity transitions in relation to opportunity-seeking behaviours. Research limitations/implications The work is theoretical in character and based on a sample that, whilst rich in the provision of theoretical insight, is small in scope. Additionally, the sample is located in one geographical context (New Zealand) which likely has implications for the way in which the key constructs are perceived and enacted. Originality/value This paper is an attempt to integrate conceptualisations of entrepreneurial identity development with opportunity-related processes in the context of venture creation. A holistic focus on identity transitions and their relevance to perception and action in relation to opportunity (the root of entrepreneurial behaviour) is novel; at this point, it is exploratory in intention and tentative in reach.


2019 ◽  
Author(s):  
Austin Q. Seroka ◽  
Chris Q. Doe

AbstractThe generation of neuronal diversity is essential for circuit formation and behavior. Morphological differences in sequentially born neurons could be due to intrinsic molecular identity specified by temporal transcription factors (henceforth called intrinsic temporal identity) or due to changing extrinsic cues. Here we use the Drosophila NB7-1 lineage to address this question. NB7-1 sequentially generates the U1-U5 motor neurons; each has a distinct intrinsic temporal identity due to inheritance of a different temporal transcription factor at time of birth. Here we show that the U1-U5 neurons project axons sequentially, followed by sequential dendrite extension. We misexpress the earliest temporal transcription factor, Hunchback, to create “ectopic” U1 neurons with an early intrinsic temporal identity but later birth-order. These ectopic U1 neurons have axon muscle targeting and dendrite neuropil targeting consistent with U1 intrinsic temporal identity, rather than their time of birth or differentiation. We conclude that intrinsic temporal identity plays a major role in establishing both motor axon muscle targeting and dendritic arbor targeting, which are required for proper motor circuit development.


2021 ◽  
Author(s):  
Camille Boudreau-Pinsonneault ◽  
Awais Javed ◽  
Michel Fries ◽  
Pierre Mattar ◽  
Michel Cayouette

Temporal identity factors are sufficient to reprogram developmental competence of neural progenitors, but whether they could also reprogram the identity of fully differentiated cells is unknown. To address this question, we designed a conditional gene expression system combined with genetic lineage tracing that allows rapid screening of potential reprogramming factors in the mouse retina. Using this assay, we report that co-expression of the early temporal identity transcription factor Ikzf1, together with Ikzf4, another Ikaros family member, is sufficient to directly convert adult Muller glial cells into neuron-like cells in vivo, without inducing a proliferative progenitor state. scRNA-seq analysis shows that the reprogrammed cells share some transcriptional signatures with both cone photoreceptors and bipolar cells. Furthermore, we show that co-expression of Ikzf1 and Ikzf4 can reprogram mouse embryonic fibroblasts to induced neurons by remodeling chromatin and promoting a neuronal gene expression program. This work uncovers general neuronal reprogramming properties for temporal identity factors in differentiated cells, opening new opportunities for cell therapy development.


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