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Communications Biology Apr 2024
PubMed: 38637608
DOI: 10.1038/s42003-024-06157-x -
Scientific Reports Apr 2024Honey bees are social insects, and each colony member has unique morphological and physiological traits associated with their social tasks. Previously, we identified a...
Honey bees are social insects, and each colony member has unique morphological and physiological traits associated with their social tasks. Previously, we identified a long non-coding RNA from honey bees, termed Nb-1, whose expression in the brain decreases associated with the age-polyethism of workers and is detected in some neurosecretory cells and octopaminergic neurons, suggesting its role in the regulation of worker labor transition. Herein, we investigated its spatially and temporary-regulated/sex-specific expression. Nb-1 was expressed as an abundant maternal RNA during oogenesis and embryogenesis in both sexes. In addition, Nb-1 was expressed preferentially in the proliferating neuroblasts of the mushroom bodies (a higher-order center of the insect brain) in the pupal brains, suggesting its role in embryogenesis and mushroom body development. On the contrary, Nb-1 was expressed in a drone-specific manner in the pupal and adult retina, suggesting its role in the drone visual development and/or sense. Subcellular localization of Nb-1 in the brain during development differed depending on the cell type. Considering that Nb-1 is conserved only in Apidae, our findings suggest that Nb-1 potentially has pleiotropic functions in the expression of multiple developmental, behavioral, and physiological traits, which are closely associated with the honey bee lifecycle.
Topics: Female; Male; Bees; Animals; RNA, Long Noncoding; Niobium; Brain; Neurons; Head; Pupa
PubMed: 38622193
DOI: 10.1038/s41598-024-59494-6 -
BioRxiv : the Preprint Server For... Apr 2024Quantitative live imaging is a valuable tool that offers insights into cellular dynamics. However, many fundamental biological processes are incompatible with current...
Quantitative live imaging is a valuable tool that offers insights into cellular dynamics. However, many fundamental biological processes are incompatible with current live imaging modalities. oogenesis is a well-studied system that has provided molecular insights into a range of cellular and developmental processes. The length of the oogenesis coupled with the requirement for inputs from multiple tissues has made long-term culture challenging. Here, we have developed Bellymount-Pulsed Tracking (Bellymount-PT), which allows continuous, non-invasive live imaging of oogenesis inside the female abdomen for up to 16 hours. Bellymount-PT improves upon the existing Bellymount technique by adding pulsed anesthesia with periods of feeding that support the long-term survival of flies during imaging. Using Bellymount-PT we measure key events of oogenesis including egg chamber growth, yolk uptake, and transfer of specific proteins to the oocyte during nurse cell dumping with high spatiotemporal precision within the abdomen of a live female.
PubMed: 38617254
DOI: 10.1101/2024.03.31.587498 -
Science Advances Apr 2024During Drosophila oogenesis, the Oskar (OSK) RNA binding protein (RBP) determines the amount of germ plasm that assembles at the posterior pole of the oocyte. Here, we...
During Drosophila oogenesis, the Oskar (OSK) RNA binding protein (RBP) determines the amount of germ plasm that assembles at the posterior pole of the oocyte. Here, we identify mechanisms that subsequently regulate germ plasm assembly in the early embryo. We show that the Smaug (SMG) RBP is transported into the germ plasm of the early embryo where it accumulates in the germ granules. SMG binds to and represses translation of the messenger RNA (mRNA) as well as the () mRNA, which encodes an RBP that we show promotes germ plasm production. Loss of SMG or mutation of SMG's binding sites in the or mRNA results in excess translation of these transcripts in the germ plasm, accumulation of excess germ plasm, and budding of excess primordial germ cells (PGCs). Therefore, SMG triggers a posttranscriptional regulatory pathway that attenuates the amount of germ plasm in embryos to modulate the number of PGCs.
Topics: Animals; Drosophila; Cytoplasm; Germ Cells; Lizards; RNA, Messenger; Cell Count
PubMed: 38608012
DOI: 10.1126/sciadv.adg7894 -
Nucleus (Austin, Tex.) Dec 2024The nuclear lamina (NL) changes composition for regulation of nuclear events. We investigated changes that occur in Drosophila oogenesis, revealing switches in NL...
The nuclear lamina (NL) changes composition for regulation of nuclear events. We investigated changes that occur in Drosophila oogenesis, revealing switches in NL composition during germ cell differentiation. Germline stem cells (GSCs) express only LamB and predominantly emerin, whereas differentiating nurse cells predominantly express LamC and emerin2. A change in LamC-specific localization also occurs, wherein phosphorylated LamC redistributes to the nuclear interior only in the oocyte, prior to transcriptional reactivation of the meiotic genome. These changes support existing concepts that LamC promotes differentiation, a premise that was tested. Remarkably ectopic LamC production in GSCs did not promote premature differentiation. Increased LamC levels in differentiating germ cells altered internal nuclear structure, increased RNA production, and reduced female fertility due to defects in eggshell formation. These studies suggest differences between Drosophila lamins are regulatory, not functional, and reveal an unexpected robustness to level changes of a major scaffolding component of the NL.
Topics: Animals; Female; Nuclear Lamina; Drosophila melanogaster; Drosophila Proteins; Drosophila; Cell Differentiation; Germ Cells
PubMed: 38597409
DOI: 10.1080/19491034.2024.2339214 -
Scientific Reports Apr 2024Oocytes of both vertebrates and invertebrates often contain an intricate organelle assemblage, termed the Balbiani body (Bb). It has previously been suggested that this...
Oocytes of both vertebrates and invertebrates often contain an intricate organelle assemblage, termed the Balbiani body (Bb). It has previously been suggested that this assemblage is involved in the delivery of organelles and macromolecules to the germ plasm, formation of oocyte reserve materials, and transfer of mitochondria to the next generation. To gain further insight into the function of the Bb, we performed a series of analyses and experiments, including computer-aided 3-dimensional reconstructions, detection of DNA (mtDNA) synthesis as well as immunolocalization studies. We showed that in orthopteran Meconema meridionale, the Bb comprises a network of mitochondria and perinuclear nuage aggregations. As oogenesis progresses, the network expands filling almost entire ooplasm, then partitions into several smaller entities, termed micro-networks, and ultimately into individual mitochondria. As in somatic cells, this process involves microfilaments and elements of endoplasmic reticulum. We showed also that at least some of the individual mitochondria are surrounded by phagophores and eliminated via mitophagy. These findings support the idea that the Bb is implicated in the multiplication and selective elimination of (defective) mitochondria and therefore may participate in the transfer of undamaged (healthy) mitochondria to the next generation.
Topics: Animals; Oocytes; Oogenesis; Mitochondria; Insecta; Endoplasmic Reticulum; Orthoptera
PubMed: 38594333
DOI: 10.1038/s41598-024-58997-6 -
Nature Communications Apr 2024Actomyosin networks constrict cell area and junctions to alter cell and tissue shape. However, during cell expansion under mechanical stress, actomyosin networks are...
Actomyosin networks constrict cell area and junctions to alter cell and tissue shape. However, during cell expansion under mechanical stress, actomyosin networks are strengthened and polarized to relax stress. Thus, cells face a conflicting situation between the enhanced actomyosin contractile properties and the expansion behaviour of the cell or tissue. To address this paradoxical situation, we study late Drosophila oogenesis and reveal an unusual epithelial expansion wave behaviour. Mechanistically, Rac1 and Rho1 integrate basal pulsatile actomyosin networks with ruffles and focal adhesions to increase and then stabilize basal area of epithelial cells allowing their flattening and elongation. This epithelial expansion behaviour bridges cell changes to oocyte growth and extension, while oocyte growth in turn deforms the epithelium to drive cell spreading. Basal pulsatile actomyosin networks exhibit non-contractile mechanics, non-linear structures and F-actin/Myosin-II spatiotemporal signal separation, implicating unreported expanding properties. Biophysical modelling incorporating these expanding properties well simulates epithelial cell expansion waves. Our work thus highlights actomyosin expanding properties as a key mechanism driving tissue morphogenesis.
Topics: Animals; Actomyosin; Drosophila Proteins; Epithelial Cells; Actin Cytoskeleton; Drosophila; Epithelium; Morphogenesis
PubMed: 38589403
DOI: 10.1038/s41467-024-47236-1 -
BMC Genomics Apr 2024Mammalian follicle development is characterized by extensive changes in morphology, endocrine responsiveness, and function, providing the optimum environment for oocyte...
BACKGROUND
Mammalian follicle development is characterized by extensive changes in morphology, endocrine responsiveness, and function, providing the optimum environment for oocyte growth, development, and resumption of meiosis. In cattle, the first signs of transcription activation in the oocyte are observed in the secondary follicle, later than during mouse and human oogenesis. While many studies have generated extensive datasets characterizing gene expression in bovine oocytes, they are mostly limited to the analysis of fully grown and matured oocytes. The aim of the present study was to apply single-cell RNA sequencing to interrogate the transcriptome of the growing bovine oocyte from the secondary follicle stage through to the mid-antral follicle stage.
RESULTS
Single-cell RNA-seq libraries were generated from oocytes of known diameters (< 60 to > 120 μm), and datasets were binned into non-overlapping size groups for downstream analysis. Combining the results of weighted gene co-expression network and Trendy analyses, and differently expressed genes (DEGs) between size groups, we identified a decrease in oxidative phosphorylation and an increase in maternal -genes and transcription regulators across the bovine oocyte growth phase. In addition, around 5,000 genes did not change in expression, revealing a cohort of stable genes. An interesting switch in gene expression profile was noted in oocytes greater than 100 μm in diameter, when the expression of genes related to cytoplasmic activities was replaced by genes related to nuclear activities (e.g., chromosome segregation). The highest number of DEGs were detected in the comparison of oocytes 100-109 versus 110-119 μm in diameter, revealing a profound change in the molecular profile of oocytes at the end of their growth phase.
CONCLUSIONS
The current study provides a unique dataset of the key genes and pathways characteristic of each stage of oocyte development, contributing an important resource for a greater understanding of bovine oogenesis.
Topics: Female; Cattle; Animals; Humans; Mice; Transcriptome; Oogenesis; Oocytes; Ovarian Follicle; Cell Proliferation; Mammals
PubMed: 38580918
DOI: 10.1186/s12864-024-10234-0 -
Cellular and Molecular Life Sciences :... Apr 2024The DNA methylation is gradually acquired during oogenesis, a process sustained by successful follicle development. However, the functional roles of methyl-CpG-binding...
The DNA methylation is gradually acquired during oogenesis, a process sustained by successful follicle development. However, the functional roles of methyl-CpG-binding protein 2 (MeCP2), an epigenetic regulator displaying specifical binding with methylated DNA, remains unknown in oogenesis. In this study, we found MeCP2 protein was highly expressed in primordial and primary follicle, but was almost undetectable in secondary follicles. However, in aged ovary, MeCP2 protein is significantly increased in both oocyte and granulosa cells. Overexpression of MeCP2 in growing oocyte caused transcription dysregulation, DNA hypermethylation, and genome instability, ultimately leading to follicle growth arrest and apoptosis. MeCP2 is targeted by DCAF13, a substrate recognition adaptor of the Cullin 4-RING (CRL4) E3 ligase, and polyubiquitinated for degradation in both cells and oocytes. Dcaf13-null oocyte exhibited an accumulation of MeCP2 protein, and the partial rescue of follicle growth arrest induced by Dcaf13 deletion was observed following MeCP2 knockdown. The RNA-seq results revealed that large amounts of genes were regulated by the DCAF13-MeCP2 axis in growing oocytes. Our study demonstrated that CRL4 E3 ubiquitin ligase targets MeCP2 for degradation to ensure normal DNA methylome and transcription in growing oocytes. Moreover, in aged ovarian follicles, deceased DCAF13 and DDB1 protein were observed, indicating a potential novel mechanism that regulates ovary aging.
Topics: Female; Humans; Cullin Proteins; DNA; DNA Methylation; Methyl-CpG-Binding Protein 2; Oocytes; Ubiquitin-Protein Ligases
PubMed: 38578457
DOI: 10.1007/s00018-024-05185-4 -
Frontiers in Cell and Developmental... 2024The establishment of the embryonic dorsoventral axis in occurs when the radial symmetry around the egg's animal-vegetal axis is broken to give rise to the typical...
The establishment of the embryonic dorsoventral axis in occurs when the radial symmetry around the egg's animal-vegetal axis is broken to give rise to the typical symmetry of Bilaterians. We have previously shown that the Notch1 protein is ventrally enriched during early embryogenesis in and zebrafish and exerts ventralizing activity through β-Catenin destabilization and the positive regulation of ventral center genes in . These findings led us to further investigate when these asymmetries arise. In this work, we show that the asymmetrical distribution of Notch1 protein and mRNA precedes cortical rotation and even fertilization in Moreover, we found that in unfertilized eggs transcripts encoded by the ventralizing gene are also asymmetrically distributed in the animal hemisphere and transcripts accumulate consistently on the same side of the eccentric maturation point. Strikingly, a Notch1 asymmetry orthogonal to the animal-vegetal axis appears during oogenesis. Thus, we show for the first time a maternal bias in the distribution of molecules that are later involved in ventral patterning during embryonic axialization, strongly supporting the hypothesis of a dorsoventral prepattern or intrinsic bilaterality of eggs before fertilization.
PubMed: 38572484
DOI: 10.3389/fcell.2024.1365705