The position of the nucleus in a cell can instruct morphogenesis in some cases, conveying spatial and temporal information and abnormal nuclear positioning can lead to disease. In oocytes from worm, sea urchin, frog and some fish, nucleus position regulates embryo development, it marks the animal pole and in Drosophila it defines the future dorso-ventral axis of the embryo and of the adult body plan. However, in mammals, the oocyte nucleus is centrally located and does not instruct any future embryo axis. Yet an off-center nucleus correlates with poor outcome for mouse and human oocyte development. This is surprising since oocytes further undergo two extremely asymmetric divisions in terms of the size of the daughter cells (enabling polar body extrusion), requiring an off-centering of their chromosomes. In this review we address not only the bio-physical mechanism controlling nucleus positioning via an actin-mediated pressure gradient, but we also speculate on potential biological relevance of nuclear positioning in mammalian oocytes and early embryos.
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http://dx.doi.org/10.1016/j.semcdb.2017.08.010 | DOI Listing |
Unlabelled: Layer 6 corticothalamic (L6CT) neurons project to both cortex and thalamus, inducing multiple effects including the modulation of cortical and thalamic firing, and the emergence of high gamma oscillations in the cortical local field potential (LFP). We hypothesize that the high gamma oscillations driven by L6CT neuron activation are shaped by the dynamic engagement of intracortical and cortico-thalamo-cortical circuits. To test this, we optogenetically activated L6CT neurons in NTSR1-cre mice expressing channelrhodopsin-2 in L6CT neurons.
View Article and Find Full Text PDFUnlabelled: Melanin pigments block genotoxic agents by positioning on the sun-exposed side of human skin keratinocytes' nucleus. How this position is regulated and its role in genome photoprotection remains unknown. By developing a model of human keratinocytes internalizing extracellular melanin into pigment organelles, we show that keratin 5/14 intermediate filaments mechanically control the 3D perinuclear position of pigments, shielding DNA from photodamage.
View Article and Find Full Text PDFFront Biosci (Landmark Ed)
January 2025
The Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, Hunan Normal University Health Science Center, 410013 Changsha, Hunan, China.
Background: α thalassemia/mental retardation syndrome X-linked (ATRX) serves as a part of the sucrose nonfermenting 2 (SNF2) chromatin-remodeling complex. In interphase, ATRX localizes to pericentromeric heterochromatin, contributing to DNA double-strand break repair, DNA replication, and telomere maintenance. During mitosis, most ATRX proteins are removed from chromosomal arms, leaving a pool near the centromere region in mammalian cells, which is critical for accurate chromosome congression and sister chromatid cohesion protection.
View Article and Find Full Text PDFViruses
January 2025
School of Life Sciences, Jiangsu University, Zhenjiang 212013, China.
Bombyx mori bidensovirus (BmBDV), a significant pathogen in the sericulture industry, holds a unique taxonomic position due to its distinct segmented single-stranded DNA (ssDNA) genome and the presence of a self-encoding DNA polymerase. However, the functions of viral non-structural proteins, such as NS2, remain unknown. This protein is hypothesized to play a role in viral replication and pathogenesis.
View Article and Find Full Text PDFPlants (Basel)
January 2025
State Key Laboratory of Vegetable Biobreeding, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
The trichomes of mustard leaves have significance due to their ability to combat unfavorable external conditions and enhance disease resistance. It was demonstrated that the MYB-bHLH-WD40 (MBW) ternary complex consists of MYB, basic Helix-Loop-Helix (bHLH), and WD40-repeat (WD40) family proteins and plays a key role in regulating trichome formation and density. The bHLH gene family, particularly the Myelocytomatosis (MYC) proteins that possess the structural bHLH domain (termed bHLH-MYC), are crucial to the formation and development of leaf trichomes in plants.
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