ARP2/3-independent WAVE/SCAR pathway and class XI myosin control sperm nuclear migration in flowering plants

After eukaryotic fertilization, gamete nuclei migrate to fuse parental genomes in order to initiate development of the next generation. In most animals, microtubules control female and male pronuclear migration in the zygote. Flowering plants, on the other hand, have evolved actin filament (F-actin)-based sperm nuclear migration systems for karyogamy. Flowering plants have also evolved a unique double-fertilization process: two female gametophytic cells, the egg and central cells, are each fertilized by a sperm cell. The molecular and cellular mechanisms of how flowering plants utilize and control F-actin for double-fertilization events are largely unknown. Using confocal microscopy live-cell imaging with a combination of pharmacological and genetic approaches, we identified factors involved in F-actin dynamics and sperm nuclear migration inArabidopsis thaliana(Arabidopsis) andNicotiana tabacum(tobacco). We demonstrate that the F-actin regulator, SCAR2, but not the ARP2/3 protein complex, controls the coordinated active F-actin movement. These results imply that an ARP2/3-independent WAVE/SCAR-signaling pathway regulates F-actin dynamics in female gametophytic cells for fertilization. We also identify that the class XI myosin XI-G controls active F-actin movement in theArabidopsiscentral cell. XI-G is not a simple transporter, moving cargos along F-actin, but can generate forces that control the dynamic movement of F-actin for fertilization. Our results provide insights into the mechanisms that control gamete nuclear migration and reveal regulatory pathways for dynamic F-actin movement in flowering plants.

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The bryophytes Physcomitrium patens and Marchantia polymorpha as model systems for studying evolutionary cell and developmental biology in plants

The Plant Cell ◽

10.1093/plcell/koab218 ◽

2021 ◽

Author(s):

Satoshi Naramoto ◽

Yuki Hata ◽

Tomomichi Fujita ◽

Junko Kyozuka

Keyword(s):

Developmental Biology ◽

Cell Division ◽

Current Knowledge ◽

Flowering Plants ◽

Model Systems ◽

Marchantia Polymorpha ◽

Special Focus ◽

Cellular Mechanisms ◽

Regulatory Pathways ◽

Biological Studies

Abstract Bryophytes are non-vascular spore-forming plants. Unlike in flowering plants, the gametophyte (haploid) generation of bryophytes dominates the sporophyte (diploid) generation. A comparison of bryophytes with flowering plants allows us to answer some fundamental questions raised in evolutionary cell and developmental biology. The moss Physcomitrium patens was the first bryophyte with a sequenced genome. Many cell and developmental studies have been conducted in this species using gene targeting by homologous recombination. The liverwort Marchantia polymorpha has recently emerged as an excellent model system with low genomic redundancy in most of its regulatory pathways. With the development of molecular genetic tools such as efficient genome editing, both P. patens and M. polymorpha have provided many valuable insights. Here, we review these advances, with a special focus on polarity formation at the cell and tissue levels. We examine current knowledge regarding the cellular mechanisms of polarized cell elongation and cell division, including symmetric and asymmetric cell division. We also examine the role of polar auxin transport in mosses and liverworts. Finally, we discuss the future of evolutionary cell and developmental biological studies in plants.

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Individuality, self and sociality of vascular plants

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0760 ◽

2021 ◽

Vol 376 (1821) ◽

pp. 20190760 ◽

Cited By ~ 2

Author(s):

František Baluška ◽

Stefano Mancuso

Keyword(s):

Action Potentials ◽

Vascular Plants ◽

Kin Recognition ◽

Flowering Plants ◽

Theme Issue ◽

Long Distance ◽

Self Recognition ◽

Seed Dispersers ◽

And Control

Vascular plants are integrated into coherent bodies via plant-specific synaptic adhesion domains, action potentials (APs) and other means of long-distance signalling running throughout the plant bodies. Plant-specific synapses and APs are proposed to allow plants to generate their self identities having unique ways of sensing and acting as agents with their own goals guiding their future activities. Plants move their organs with a purpose and with obvious awareness of their surroundings and require APs to perform and control these movements. Self-identities allow vascular plants to act as individuals enjoying sociality via their self/non-self-recognition and kin recognition. Flowering plants emerge as cognitive and intelligent organisms when the major strategy is to attract and control their animal pollinators as well as seed dispersers by providing them with food enriched with nutritive and manipulative/addictive compounds. Their goal in interactions with animals is manipulation for reproduction, dispersal and defence. This article is part of the theme issue ‘Basal cognition: multicellularity, neurons and the cognitive lens’.

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Cephalopod Retinal Development Shows Vertebrate-like Mechanisms of Neurogenesis

10.1101/2021.10.28.466353 ◽

2021 ◽

Author(s):

Francesca Napoli ◽

Christina M Daly ◽

Stephanie Neal ◽

Kyle J McCulloch ◽

Alexandra Zaloga ◽

...

Keyword(s):

Cell Cycle ◽

Nervous System ◽

Progenitor Cells ◽

Cellular Proliferation ◽

Imaging Techniques ◽

Nuclear Migration ◽

Live Imaging ◽

Cellular Mechanisms ◽

High Resolution Data ◽

Interkinetic Nuclear Migration

Neurogenesis, the regulation of cellular proliferation and differentiation in the developing nervous system, is the process that underlies the diversity of size and cell type found in animal nervous systems. Our understanding of how this process has evolved is limited because of the lack of high resolution data and live-imaging methods across species. The retina is a classic model for the study of neurogenesis in vertebrates and live-imaging of the retina has shown that during development, progenitor cells are organized in a pseudostratified neuroepithelium and nuclei migrate in coordination with the cell cycle along the apicobasal axis of the cell, a process called interkinetic nuclear migration. Eventually cells delaminate and differentiate within the boundaries of the epithelium. This process has been considered unique to vertebrates and thought to be important in maintaining organization during the development of a complex nervous system. Coleoid cephalopods, including squid, cuttlefish and octopus, have the largest nervous system of any invertebrate and convergently-evolved camera-type eyes, making them a compelling comparative system to vertebrates. Here we have pioneered live-imaging techniques to show that the squid, Doryteuthis pealeii, displays cellular mechanisms during cephalopod retinal neurogenesis that are hallmarks of vertebrate processes. We find that retinal progenitor cells in the squid undergo interkinetic nuclear migration until they exit the cell cycle, we identify retinal organization corresponding to progenitor, post-mitotic and differentiated cells, and we find that Notch signaling regulates this process. With cephalopods and vertebrates having diverged 550 million years ago, these results suggest that mechanisms thought to be unique to vertebrates may be common to highly proliferative neurogenic primordia contributing to a large nervous system.

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Compliance or negotiation? Diyanet’s female preachers and the diffusion of a ‘true’ religion in Turkey

Social Compass ◽

10.1177/0037768617727487 ◽

2017 ◽

Vol 64 (4) ◽

pp. 530-545 ◽

Cited By ~ 4

Author(s):

Chiara Maritato

Keyword(s):

Religious Authority ◽

Religious Activities ◽

Control Female ◽

Religious Engagement ◽

State Monopoly ◽

Turkish State ◽

And Control ◽

Religion In Turkey

This article addresses the religious activities of the female preachers ( vaizeler) employed by the Turkish Presidency of Religious Affairs (Diyanet). It investigates the extent to which, and how, the activities carried out by the Diyanet’s vaizeler are in compliance with a state attempt to standardise and control female religious engagement. As religious officers, the vaizeler both spread and embody an organised religion. However, far from any dichotomous perspective, to assert their religious authority the Diyanet’s preachers navigate daily between compliance with the institution’s dogmas and negotiation with a plurality of interpretations labelled as unofficial, popular and traditional. To fully assess this issue, this article refers to ethnographic observations of everyday vaizeler’s preaching activities in Istanbul’s mosques. Conducted between 2013 and 2014, these observations are crucial for contextualising the evolution of the Turkish state monopoly over religious affairs, particularly in the aftermath of the July 2016 attempted coup.

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