A circadian egg timer gates ovulation.
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ABSTRACT:
SUBMITTER: Sellix MT
PROVIDER: S-EPMC2888283 | biostudies-literature | 2010 Mar
REPOSITORIES: biostudies-literature
Publications
A circadian egg timer gates ovulation.
Sellix Michael T MT Yoshikawa Tomoko T Menaker Michael M
Current biology : CB 20100301 6
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Project description:The present study aimed at studying the rainbow trout egg transcriptome using 9152-cDNA microarrays after natural or controlled ovulation. The analysis of egg transcriptome after natural or controlled ovulation led to the identification of 26 genes. We observed that both hormonal induction and photoperiod control of ovulation induced significant changes in the egg mRNA abundance of specific genes. We demonstrate that hormonal induction of ovulation has an impact on the egg mRNA abundance of specific genes even though the resulting effects on the developmental potential of the egg is so far unknown. In addition, we also identified 1 gene exhibiting a differential mRNA abundance in eggs of varying developmental potential. Keywords: Egg quality-dependent
2006-10-03 | GSE5928 | GEO
Project description:The present study aimed at studying the rainbow trout egg transcriptome using 9152-cDNA microarrays after natural or controlled ovulation. The analysis of egg transcriptome after natural or controlled ovulation led to the identification of 26 genes. We observed that both hormonal induction and photoperiod control of ovulation induced significant changes in the egg mRNA abundance of specific genes. We demonstrate that hormonal induction of ovulation has an impact on the egg mRNA abundance of specific genes even though the resulting effects on the developmental potential of the egg is so far unknown. In addition, we also identified 1 gene exhibiting a differential mRNA abundance in eggs of varying developmental potential. Analysis of egg transcriptome after natural ovulation (4 samples), photoperiod-controlled ovulation (14 samples), and hormonally-induced ovulation (11 samples).
2010-07-01 | E-GEOD-5928 | biostudies-arrayexpress
Project description:BackgroundThe preservation of fish egg quality after ovulation-control protocols is a major issue for the development of specific biotechnological processes (e.g. nuclear transfer). Depending on the species, it is often necessary to control the timing of ovulation or induce the ovulatory process. The hormonal or photoperiodic control of ovulation can induce specific egg quality defects that have been thoroughly studied. In contrast, the impact on the egg transcriptome as a result of these manipulations has received far less attention. Furthermore, the relationship between the mRNA abundance of maternally-inherited mRNAs and the developmental potential of the egg has never benefited from genome-wide studies. Thus, the present study aimed at studying the rainbow trout (Oncorhynchus mykiss) egg transcriptome after natural or controlled ovulation using 9152-cDNA microarrays.ResultsThe analysis of egg transcriptome after natural or controlled ovulation led to the identification of 26 genes. The expression patterns of 17 of those genes were monitored by real-time PCR. We observed that the control of ovulation by both hormonal induction and photoperiod manipulation induced significant changes in the egg mRNA abundance of specific genes. A dramatic increase of Apolipoprotein C1 (APOC1) and tyrosine protein kinase HCK was observed in the eggs when a hormonal induction of ovulation was performed. In addition, both microarray and real-time PCR analyses showed that prohibitin 2 (PHB2) egg mRNA abundance was negatively correlated with developmental success.ConclusionFirst, we showed, for the first time in fish, that the control of ovulation using either a hormonal induction or a manipulated photoperiod can induce differences in the egg mRNA abundance of specific genes. While the impact of these modifications on subsequent embryonic development is unknown, our observations clearly show that the egg transcriptome is affected by an artificial induction of ovulation.Second, we showed that the egg mRNA abundance of prohibitin 2 was reflective of the developmental potential of the egg.Finally, the identity and ontology of identified genes provided significant hints that could result in a better understanding of the mechanisms associated with each type of ovulation control (i.e. hormonal, photoperiodic), and in the identification of conserved mechanisms triggering the loss of egg developmental potential.
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Project description:Inactivation is an intrinsic property of several voltage-dependent ion channels, closing the conduction pathway during membrane depolarization and dynamically regulating neuronal activity. BK K(+) channels undergo N-type inactivation via their β2 subunit, but the physiological significance is not clear. Here, we report that inactivating BK currents predominate during the day in the suprachiasmatic nucleus, the brain's intrinsic clock circuit, reducing steady-state current levels. At night inactivation is diminished, resulting in larger BK currents. Loss of β2 eliminates inactivation, abolishing the diurnal variation in both BK current magnitude and SCN firing, and disrupting behavioural rhythmicity. Selective restoration of inactivation via the β2 N-terminal 'ball-and-chain' domain rescues BK current levels and firing rate, unexpectedly contributing to the subthreshold membrane properties that shift SCN neurons into the daytime 'upstate'. Our study reveals the clock employs inactivation gating as a biophysical switch to set the diurnal variation in suprachiasmatic nucleus excitability that underlies circadian rhythm.
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Project description:The circadian clocks within the hypothalamic-pituitary-gonadal axis control estrous cycles in female rodents. The suprachiasmatic nucleus (SCN), where the central clock is located, generates daily signals to trigger surge release of luteinizing hormone (LH), which in turn induces ovulation. It has been observed in aged rodents that output from the SCN such as neuronal firing activity is declined, and estrous cycles become irregular and finally stop. Circadian clock mutants display accelerated reproductive aging, suggesting the complicated interplay between the circadian system and the endocrine system. To investigate such circadian regulation of estrous cycles, we construct a mathematical model that describes dynamics of key hormones such as LH and of circadian clocks in the SCN and in the ovary, and simulate estrous cycles for various parameter values. Our simulation results demonstrate that reduction of the amplitude of the SCN signal, which is a symptom of aging, makes estrous cycles irregular. We also show that variation in the phase of the SCN signal and changes in the period of ovarian circadian clocks exacerbates the aging effect on estrous cyclicity. Our study suggests that misalignment between the SCN and ovarian circadian oscillations is one of the primary causes of the irregular estrous cycles.
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Project description:The daily rhythm of adult emergence of holometabolous insects is one of the first circadian rhythms to be studied. In these insects, the circadian clock imposes a daily pattern of emergence by allowing or stimulating eclosion during certain windows of time and inhibiting emergence during others, a process that has been described as "gating." Although the circadian rhythm of insect emergence provided many of the key concepts of chronobiology, little progress has been made in understanding the bases of the gating process itself, although the term "gating" suggests that it is separate from the developmental process of metamorphosis. Here, we follow the progression through the final stages of Drosophila adult development with single-animal resolution and show that the circadian clock imposes a daily rhythmicity to the pattern of emergence by controlling when the insect initiates the final steps of metamorphosis itself. Circadian rhythmicity of emergence depends on the coupling between the central clock located in the brain and a peripheral clock located in the prothoracic gland (PG), an endocrine gland whose only known function is the production of the molting hormone, ecdysone. Here, we show that the clock exerts its action by regulating not the levels of ecdysone but that of its actions mediated by the ecdysone receptor. Our findings may also provide insights for understanding the mechanisms by which the daily rhythms of glucocorticoids are produced in mammals, which result from the coupling between the central clock in the suprachiasmatic nucleus and a peripheral clock located in the suprarenal gland.
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Project description:Multiple mechanisms likely contribute to the increase in chromosome missegregation that leads to production of aneuploid eggs and fetuses at advanced maternal age. It is therefore considered unlikely that a single approach could prevent age-related egg aneuploidy. Here we show using three independent approaches that ovulation reduction is sufficient to prevent egg aneuploidy in aged mammals. To gain insights into the mechanism underlying the rescue in egg aneuploidy, we show that ovulation suppression correlates with retention of chromosomal Rec8-cohesin, implying that ovulations are linked to cohesin deterioration. Moreover, we discovered that ageing alters 3D chromatin organization by single-nucleus Hi-C (snHi-C). Extruded loops increase in size with age and this is retarded by ovulation reduction. We conclude that reducing ovulations leads to retention of chromosomal Rec8, which maintains interphase chromatin structure and promotes chromosome segregation and production of euploid eggs. Importantly, our data suggest that ovulation itself contributes to the maternal age effect. This work provides the first experimental evidence that progesterone treatment reduces egg aneuploidy and suggests that hormonal contraception can reduce the risk of trisomic pregnancies like Down’s syndrome at advanced maternal age.
2021-04-01 | GSE130585 | GEO
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