Setting up for gastrulation: D. melanogaster

Stathopoulos, Angelike; Newcomb, Susan

doi:10.1016/bs.ctdb.2019.11.004

Cited by 17 publications

(20 citation statements)

References 165 publications

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“…At this point, widespread zygotic gene expression is initiated. It is at this early stage of the developmental process of the Drosophila embryo that patterning along the AP and DV body axes is established (reviewed by Stathopoulos and Newcomb, 2020). Two maternally deposited morphogens, Bcd and Dl, are key factors that orchestrate this patterning process.…”

Section: Introductionmentioning

confidence: 99%

Dynamic patterning by morphogens illuminated by cis-regulatory studies

Irizarry

Stathopoulos

2021

Development

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Morphogen concentration changes in space as well as over time during development. However, how these dynamics are interpreted by cells to specify fate is not well understood. Here, we focus on two morphogens: the maternal transcription factors Bicoid and Dorsal, which directly regulate target genes to pattern Drosophila embryos. The actions of these factors at enhancers has been thoroughly dissected and provides a rich platform for understanding direct input by morphogens and their changing roles over time. Importantly, Bicoid and Dorsal do not work alone; we also discuss additional inputs that work with morphogens to control spatiotemporal gene expression in embryos.

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Section: Introductionmentioning

confidence: 99%

Dynamic patterning by morphogens illuminated by cis-regulatory studies

Irizarry

Stathopoulos

2021

Development

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“…To determine the extent of MBT in our cell cycle-arrested embryos, we examined postcellularization development. Precisely orchestrated zygotic transcriptional networks subdivide the body plan into segments and guide gastrulation [15,31,45]. As part of this program, many transcriptional inputs guide engrailed gene expression in segmentally repeated stripes [46,47].…”

Section: Gastrulation and Embryonic Patterning In Cell Cycle-arrestedmentioning

confidence: 99%

“…The occurrence of post-MBT developmental events implied the activation of zygotic gene expression, but these studies did not indicate the extent of this activation. To gain a full picture of the dynamics of the transcriptome after cessation of the rapid early cycles, we manually collected embryos that were arrested in cycle 12 (C12) with triple cyclin RNAi for different amounts of time (15,30,50, and 70 minutes after completion of mitosis 11), as well as control embryos at different cell cycles, and carried out single-embryo RNA-seq analyses (Fig 3A and S1 Table). We calculated the Log 2 -transformed count per million (Log 2 CPM+1) for each gene (S2 Table) to allow comparison of their expression levels among different embryos.…”

Section: Transcriptome Dynamics Of the Embryos Arrested In Cycle 12mentioning

confidence: 99%

“…Zygotic gene expression is precisely and dynamically controlled both in time and space during early embryonic development [15,39,45]. To gain an insight into the patterning of zygotic transcription in cell cycle-arrested embryos, we first used in situ hybridization to detect mature transcripts from a "N/C-dependent" gene odd.…”

Section: Zygotic Transcription Is Patterned In Cell Cycle-arrested Emmentioning

confidence: 99%

“…When the nuclei achieve the capacity to take command, the biology of the early embryo is transformed at the mid-blastula transition (MBT). At this stage, the cell cycle slows, the maternal posttranscriptional program is shut down, zygotic transcription is up-regulated, cells start to take on distinct fates, and morphogenesis begins [4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Interphase-arrested Drosophila embryos activate zygotic gene expression and initiate mid-blastula transition events at a low nuclear-cytoplasmic ratio

et al. 2020

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Externally deposited eggs begin development with an immense cytoplasm and a single overwhelmed nucleus. Rapid mitotic cycles restore normality as the ratio of nuclei to cytoplasm (N/C) increases. A threshold N/C has been widely proposed to activate zygotic genome transcription and onset of morphogenesis at the mid-blastula transition (MBT). To test whether a threshold N/C is required for these events, we blocked N/C increase by down-regulating cyclin/Cdk1 to arrest early cell cycles in Drosophila. Embryos that were arrested two cell cycles prior to the normal MBT activated widespread transcription of the zygotic genome including genes previously described as N/C dependent. Zygotic transcription of these genes largely retained features of their regulation in space and time. Furthermore, zygotically regulated post-MBT events such as cellularization and gastrulation movements occurred in these cell cycle-arrested embryos. These results are not compatible with models suggesting that these MBT events are directly coupled to N/C. Cyclin/Cdk1 activity normally declines in tight association with increasing N/C and is regulated by N/C. By experimentally promoting the decrease in cyclin/Cdk1, we uncoupled MBT from N/C increase, arguing that N/C-guided down-regulation of cyclin/Cdk1 is sufficient for genome activation and MBT.

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From Egg to Adult: A Developmental Table of the Ant Monomorium pharaonis

Rajakumar,

Pontieri,

et al. 2024

J Exp Zool Pt B

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Ants are one of the most ecologically and evolutionarily successful groups of animals and exhibit a remarkable degree of phenotypic diversity. This success is largely attributed to the fact that all ants are eusocial and live in colonies with a reproductive division of labor between morphologically distinct queen and worker castes. Yet, despite over a century of studies on caste determination and evolution in ants, we lack a complete ontogenetic series from egg to adult for any ant species. We, therefore, present a developmental table for the Pharaoh ant Monomorium pharaonis, a species whose colonies simultaneously produce reproductive queens and completely sterile workers. In total, M. pharaonis embryonic, larval, and pupal development lasts 45 days. During embryogenesis, the majority of developmental events are conserved between M. pharaonis and the fruit fly Drosophila melanogaster. We discovered, however, two types of same‐stage embryos before gastrulation: (1) embryos with internalized germ cells; and (2) embryos with germ cells outside of the blastoderm at the posterior pole. Moreover, we also found two‐types of embryos following germ band extension: (1) embryos with primordial germ cells that will develop into reproductive queens; and (2) embryos with no germ cells that will develop into completely sterile workers. Together, these data show that queen and worker castes are already determined and differentiated by early embryogenesis. During larval development, we confirmed that reproductive and worker larvae proceed through three larval instars. Using anatomical and developmental markers, we can further discern the development of gyne (unmated queen) larvae, male larvae, and worker larvae as early as the 1st instar. Overall, we hope that the ontogenetic series we present here will serve as a blueprint for the generation of future ant developmental tables.

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Setting up for gastrulation: D. melanogaster

Cited by 17 publications

References 165 publications

Dynamic patterning by morphogens illuminated by cis-regulatory studies

Dynamic patterning by morphogens illuminated by cis-regulatory studies

Interphase-arrested Drosophila embryos activate zygotic gene expression and initiate mid-blastula transition events at a low nuclear-cytoplasmic ratio

From Egg to Adult: A Developmental Table of the Ant Monomorium pharaonis

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