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BMC Biology Nov 2021The phylum Euglenozoa is a group of flagellated protists comprising the diplonemids, euglenids, symbiontids, and kinetoplastids. The diplonemids are highly abundant and...
BACKGROUND
The phylum Euglenozoa is a group of flagellated protists comprising the diplonemids, euglenids, symbiontids, and kinetoplastids. The diplonemids are highly abundant and speciose, and recent tools have rendered the best studied representative, Diplonema papillatum, genetically tractable. However, despite the high diversity of diplonemids, their lifestyles, ecological functions, and even primary energy source are mostly unknown.
RESULTS
We designed a metabolic map of D. papillatum cellular bioenergetic pathways based on the alterations of transcriptomic, proteomic, and metabolomic profiles obtained from cells grown under different conditions. Comparative analysis in the nutrient-rich and nutrient-poor media, as well as the absence and presence of oxygen, revealed its capacity for extensive metabolic reprogramming that occurs predominantly on the proteomic rather than the transcriptomic level. D. papillatum is equipped with fundamental metabolic routes such as glycolysis, gluconeogenesis, TCA cycle, pentose phosphate pathway, respiratory complexes, β-oxidation, and synthesis of fatty acids. Gluconeogenesis is uniquely dominant over glycolysis under all surveyed conditions, while the TCA cycle represents an eclectic combination of standard and unusual enzymes.
CONCLUSIONS
The identification of conventional anaerobic enzymes reflects the ability of this protist to survive in low-oxygen environments. Furthermore, its metabolism quickly reacts to restricted carbon availability, suggesting a high metabolic flexibility of diplonemids, which is further reflected in cell morphology and motility, correlating well with their extreme ecological valence.
Topics: Euglenozoa; Eukaryota; Meiotic Prophase I; Oxygen; Phylogeny; Proteomics
PubMed: 34819072
DOI: 10.1186/s12915-021-01186-y -
Nature Communications Apr 2024Meiotic prophase progression is differently regulated in males and females. In males, pachytene transition during meiotic prophase is accompanied by robust alteration in...
Meiotic prophase progression is differently regulated in males and females. In males, pachytene transition during meiotic prophase is accompanied by robust alteration in gene expression. However, how gene expression is regulated differently to ensure meiotic prophase completion in males remains elusive. Herein, we identify HSF5 as a male germ cell-specific heat shock transcription factor (HSF) for meiotic prophase progression. Genetic analyzes and single-cell RNA-sequencing demonstrate that HSF5 is essential for progression beyond the pachytene stage under non-stress conditions rather than heat stress. Chromatin binding analysis in vivo and DNA-binding assays in vitro suggest that HSF5 binds to promoters in a subset of genes associated with chromatin organization. HSF5 recognizes a DNA motif different from typical heat shock elements recognized by other canonical HSFs. This study suggests that HSF5 is an atypical HSF that is required for the gene expression program for pachytene transition during meiotic prophase in males.
Topics: Mice; Male; Heat Shock Transcription Factors; Meiotic Prophase I; Mice, Knockout; Mice, Inbred C57BL; Spermatogenesis; Testis; Heat-Shock Response; Female
PubMed: 38684656
DOI: 10.1038/s41467-024-47601-0 -
Cells Jan 2020The role of hydrogen sulfide (HS) is addressed in oocytes. Three enzymes involved in HS metabolism, cystathionine β-synthase, cystathionine γ-lyase, and...
The role of hydrogen sulfide (HS) is addressed in oocytes. Three enzymes involved in HS metabolism, cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase, were detected in prophase I and metaphase II-arrested oocytes and drove an acceleration of oocyte meiosis resumption when inhibited. Moreover, meiosis resumption is associated with a significant decrease in endogenous HS. On another hand, a dose-dependent inhibition was obtained using the HS donor, NaHS (1 and 5 mM). NaHS impaired translation. NaHS did not induce the dissociation of the components of the M-phase promoting factor (MPF), cyclin B and Cdk1, nor directly impacted the MPF activity. However, the M-phase entry induced by microinjection of metaphase II MPF-containing cytoplasm was diminished, suggesting upstream components of the MPF auto-amplification loop were sensitive to HS. Superoxide dismutase and catalase hindered the effects of NaHS, and this sensitivity was partially dependent on the production of reactive oxygen species (ROS). In contrast to other species, no apoptosis was promoted. These results suggest a contribution of HS signaling in the timing of amphibian oocytes meiosis resumption.
Topics: Animals; Apoptosis; Catalase; Cell Cycle Proteins; Cell Survival; Cyclin B; Cystathionine beta-Synthase; Cystathionine gamma-Lyase; Cytoplasm; Female; Hydrogen Sulfide; Maturation-Promoting Factor; Meiosis; Meiotic Prophase I; Metaphase; Oocytes; Protein Kinases; Reactive Oxygen Species; Signal Transduction; Sulfides; Sulfurtransferases; Superoxide Dismutase; Xenopus Proteins; Xenopus laevis; cdc25 Phosphatases
PubMed: 31963573
DOI: 10.3390/cells9010237 -
Cell Reports Jan 2024Dynamic chromosome remodeling and nuclear compartmentalization take place during mammalian meiotic prophase I. We report here that the crucial roles of male...
Dynamic chromosome remodeling and nuclear compartmentalization take place during mammalian meiotic prophase I. We report here that the crucial roles of male pachynema-specific protein (MAPS) in pachynema progression might be mediated by its liquid-liquid phase separation in vitro and in cellulo. MAPS forms distinguishable liquid phases, and deletion or mutations of its N-terminal amino acids (aa) 2-9 disrupt its secondary structure and charge properties, impeding phase separation. Maps pachytene spermatocytes exhibit defects in nucleus compartmentalization, including defects in forming sex bodies, altered nucleosome composition, and disordered chromatin accessibility. Maps male mice expressing MAPS protein lacking aa 2-9 phenocopy Maps mice. Moreover, a frameshift mutation in C3orf62, the human counterpart of Maps, is correlated with nonobstructive azoospermia in a patient exhibiting pachynema arrest in spermatocyte development. Hence, the phase separation property of MAPS seems essential for pachynema progression in mouse and human spermatocytes.
Topics: Humans; Male; Mice; Animals; Chromatin; Meiosis; Pachytene Stage; Phase Separation; Meiotic Prophase I; Spermatocytes; Mammals
PubMed: 38175751
DOI: 10.1016/j.celrep.2023.113651 -
Cell Reports Jan 2022The meiosis-specific telomere-binding protein TERB1 anchors telomeres to the nuclear envelope and drives chromosome movements for the pairing of homologous chromosomes....
The meiosis-specific telomere-binding protein TERB1 anchors telomeres to the nuclear envelope and drives chromosome movements for the pairing of homologous chromosomes. TERB1 has an MYB-like DNA-binding (MYB) domain, which is a hallmark of telomeric DNA-binding proteins. Here, we demonstrate that the TERB1 MYB domain has lost its canonical DNA-binding activity. The analysis of Terb1 point mutant mice expressing TERB1 lacking its MYB domain showed that the MYB domain is dispensable for telomere localization of TERB1 and the downstream TERB2-MAJIN complex, the promotion of homologous pairing, and even fertility. Instead, the TERB1 MYB domain regulates the enrichment of cohesin and promotes the remodeling of axial elements in the early-to-late pachytene transition, which suppresses telomere erosion. Considering its conservation across metazoan phyla, the TERB1 MYB domain is likely to be important for the maintenance of telomeric DNA and thus for genomic integrity by suppressing meiotic telomere erosion over long evolutionary timescales.
Topics: Animals; Female; Humans; Male; Meiotic Prophase I; Mice; Mice, Inbred C57BL; Protein Domains; Telomere; Telomere-Binding Proteins
PubMed: 35081355
DOI: 10.1016/j.celrep.2021.110289 -
Frontiers in Cell and Developmental... 2022During meiotic prophase I, tightly regulated processes take place, from pairing and synapsis of homologous chromosomes to recombination, which are essential for the...
During meiotic prophase I, tightly regulated processes take place, from pairing and synapsis of homologous chromosomes to recombination, which are essential for the generation of genetically variable haploid gametes. These processes have canonical meiotic features conserved across different phylogenetic groups. However, the dynamics of meiotic prophase I in non-mammalian vertebrates are poorly known. Here, we compare four species from Sauropsida to understand the regulation of meiotic prophase I in reptiles: the Australian central bearded dragon (), two geckos ( and ) and the painted turtle (). We first performed a histological characterization of the spermatogenesis process in both the bearded dragon and the painted turtle. We then analyzed prophase I dynamics, including chromosome pairing, synapsis and the formation of double strand breaks (DSBs). We show that meiosis progression is highly conserved in reptiles with telomeres clustering forming the , which we propose promotes homologous pairing and synapsis, along with facilitating the early pairing of micro-chromosomes during prophase I (i.e., early zygotene). Moreover, we detected low levels of meiotic DSB formation in all taxa. Our results provide new insights into reptile meiosis.
PubMed: 36313577
DOI: 10.3389/fcell.2022.1009776 -
MBio Mar 2018Diplonemids represent a hyperdiverse and abundant yet poorly studied group of marine protists. Here we describe two new members of the genus (Diplonemea, Euglenozoa),...
Diplonemids represent a hyperdiverse and abundant yet poorly studied group of marine protists. Here we describe two new members of the genus (Diplonemea, Euglenozoa), sp. nov. and sp. nov., based on life cycle, morphology, and 18S rRNA gene sequences. Along with euglenozoan apomorphies, they contain several unique features. Their life cycle is complex, consisting of a trophic stage that is, following the depletion of nutrients, transformed into a sessile stage and subsequently into a swimming stage. The latter two stages are characterized by the presence of tubular extrusomes and the emergence of a paraflagellar rod, the supportive structure of the flagellum, which is prominently lacking in the trophic stage. These two stages also differ dramatically in motility and flagellar size. Both diplonemid species host endosymbiotic bacteria that are closely related to each other and constitute a novel branch within , for which a new genus, " Cytomitobacter" gen. nov., has been established. Remarkably, the number of endosymbionts in the cytoplasm varies significantly, as does their localization within the cell, where they seem to penetrate the mitochondrion, a rare occurrence. We describe the morphology, behavior, and life cycle of two new species that established a relationship with two -like bacteria in the first report of an endosymbiosis in diplonemids. Both endosymbionts reside in the cytoplasm and the mitochondrion, which establishes an extremely rare case. Within their life cycle, the diplonemids undergo transformation from a trophic to a sessile and eventually a highly motile swimming stage. These stages differ in several features, such as the presence or absence of tubular extrusomes and a paraflagellar rod, along with the length of the flagella. These morphological and behavioral interstage differences possibly reflect distinct functions in dispersion and invasion of the host and/or prey and may provide novel insight into the virtually unknown function of diplonemids in the oceanic ecosystem.
Topics: Bacteria; Life Cycle Stages; Meiotic Prophase I; Phylogeny; RNA, Ribosomal, 18S; Symbiosis
PubMed: 29511084
DOI: 10.1128/mBio.02447-17 -
European Journal of Cell Biology Apr 2022In mammalian females, oocytes are stored in the ovary and meiosis is arrested at the diplotene stage of prophase I. When females reach puberty oocytes are selectively...
In mammalian females, oocytes are stored in the ovary and meiosis is arrested at the diplotene stage of prophase I. When females reach puberty oocytes are selectively recruited in cycles to grow, overcome the meiotic arrest, complete the first meiotic division and become mature (ready for fertilization). At a molecular level, the master regulator of prophase I arrest and meiotic resumption is the maturation-promoting factor (MPF) complex, formed by the active form of cyclin dependent kinase 1 (CDK1) and Cyclin B1. However, we still do not have complete information regarding the factors implicated in MPF activation. In this study we document that out of three mammalian serum-glucocorticoid kinase proteins (SGK1, SGK2, SGK3), mouse oocytes express only SGK1 with a phosphorylated (active) form dominantly localized in the nucleoplasm. Further, suppression of SGK1 activity in oocytes results in decreased CDK1 activation via the phosphatase cell division cycle 25B (CDC25B), consequently delaying or inhibiting nuclear envelope breakdown. Expression of exogenous constitutively active CDK1 can rescue the phenotype induced by SGK1 inhibition. These findings bring new insights into the molecular pathways acting upstream of MPF and a better understanding of meiotic resumption control by presenting a new key player SGK1 in mammalian oocytes.
Topics: Animals; Cell Cycle Checkpoints; Female; Immediate-Early Proteins; Mammals; Maturation-Promoting Factor; Meiosis; Meiotic Prophase I; Mice; Oocytes; Protein Serine-Threonine Kinases
PubMed: 35240557
DOI: 10.1016/j.ejcb.2022.151210 -
Nature Jun 2020In most species, homologous chromosomes must recombine in order to segregate accurately during meiosis. Because small chromosomes would be at risk of missegregation if...
In most species, homologous chromosomes must recombine in order to segregate accurately during meiosis. Because small chromosomes would be at risk of missegregation if recombination were randomly distributed, the double-strand breaks (DSBs) that initiate recombination are not located arbitrarily. How the nonrandomness of DSB distributions is controlled is not understood, although several pathways are known to regulate the timing, location and number of DSBs. Meiotic DSBs are generated by Spo11 and accessory DSB proteins, including Rec114 and Mer2, which assemble on chromosomes and are nearly universal in eukaryotes. Here we demonstrate how Saccharomyces cerevisiae integrates multiple temporally distinct pathways to regulate the binding of Rec114 and Mer2 to chromosomes, thereby controlling the duration of a DSB-competent state. The engagement of homologous chromosomes with each other regulates the dissociation of Rec114 and Mer2 later in prophase I, whereas the timing of replication and the proximity to centromeres or telomeres influence the accumulation of Rec114 and Mer2 early in prophase I. Another early mechanism enhances the binding of Rec114 and Mer2 specifically on the shortest chromosomes, and is subject to selection pressure to maintain the hyperrecombinogenic properties of these chromosomes. Thus, the karyotype of an organism and its risk of meiotic missegregation influence the shape and evolution of its recombination landscape. Our results provide a cohesive view of a multifaceted and evolutionarily constrained system that allocates DSBs to all pairs of homologous chromosomes.
Topics: Centromere; Chromosome Segregation; Chromosomes, Fungal; DNA Breaks, Double-Stranded; DNA Replication Timing; Homologous Recombination; Meiosis; Meiotic Prophase I; Recombinases; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Telomere; Time Factors
PubMed: 32494071
DOI: 10.1038/s41586-020-2248-2 -
International Journal of Molecular... Sep 2022The development of germ cells and other physiological events in the differentiated ovary of humans are highly conserved with several mammalian species, except for the... (Review)
Review
The development of germ cells and other physiological events in the differentiated ovary of humans are highly conserved with several mammalian species, except for the differences in timing. However, comparative knowledge on this topic is very scarce with respect to humans and lower vertebrates, such as chickens. In chickens, female germ cells enter into meiosis around embryonic day (E) 15.5 and are arrested in meiotic prophase I as primary oocytes. The oocytes arrested in meiosis I are accumulated in germ-cell cysts; shortly after hatching, they are enclosed by flattened granulosa cells in order to form primordial follicles. In humans, the process of meiotic recombination in female germ cells begins in the 10-11th week of gestation, and primordial follicles are formed at around week 20. In this review, we comprehensively elucidate both the conservation and the species-specific differences between chickens and humans with respect to germ cell, oocyte, and follicle development. Importantly, we provide functional insights into a set of chicken oocyte enriched genes (from E16 to 1 week post-hatch) that show convergent and divergent expression patterns with respect to the human oocyte (from week 11 to 26).
Topics: Animals; Chickens; Female; Germ Cells; Humans; Mammals; Meiosis; Oocytes; Ovarian Follicle
PubMed: 36232712
DOI: 10.3390/ijms231911412