Evidence for a functional role of the cytoskeleton in determination of the dorsoventral axis in Xenopus laevis eggs

Development ◽  
1983 ◽  
Vol 77 (1) ◽  
pp. 15-37
Author(s):  
Geertje A. Ubbels ◽  
K. Hara ◽  
C. H. Koster ◽  
M. W. Kirschner
Keyword(s):  
Functional Role ◽  
Normal Development ◽  
Cytological Study ◽  
Time Lapse ◽  
Microtubule Assembly ◽  
Dorsoventral Axis ◽  
Normal Table ◽  
Fertilized Egg

A normal table of events of the first cleavage period in the fertilized egg (cf. Gerhart, 1980) has been completed (cf. Table I) by studying external and internal features. Through a cytological study of eggs fixed after video time-lapse observation such featurescan directly be correlated and it has been shown that the first postfertilization wave (PFW) reflects spermaster growth, which causes rearrangements of animal yolk material. Thismay, in conjunction with the interaction of the spermaster rays with the cortex, define, in time as well as in space, the asymmetric cortical contraction which we suppose to evoke asymmetry in the animal hemisphere by formation of the vitelline wall (Pasteels, 1964) and in the vegetal hemisphere by formation of the Vegetal Dorsalising Centre (Kirschneret al. 1981). Neither prick-activated eggs nor fertilized eggs incubated in vinblastine develop a spermaster. Under these conditions abnormal cytoplasmic segregation may be directed by gravity alone. For normal development the activated egg must in some way, for instance through the sperm centriole, organize microtubule assembly into a monaster. The centriole actsas a microtubule-organizing centre in structuring the egg's cytoskeleton, and through this directs localization of the various yolk components, in time as well as in space. In egg rotation experiments performed under appropriate conditions, the cytoskeleton is disturbed and yolk rearranges under gravity till a new equilibrium is established which determines a new dorsoventral polarity. Such experiments also show that neither the dorsal cytoplasm nor the grey crescent cortex act as the ultimate dorsal determinants, since their localization is unaltered upon rotation, whereas the overall yolk distribution is significantly changed.

P–222 Can we optimise the time that we perform the fertilisation check in the lab? Lessons learnt from time-lapse incubation

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
A Barrie ◽  
R Smith ◽  
L Best ◽  
N Davis ◽  
S Duffy ◽  
...  
Keyword(s):  
Study Design ◽  
Fetal Heart ◽  
Time Lapse ◽  
Trial Registration ◽  
Optimum Time ◽  
Use Of Time ◽  
Lessons Learnt ◽  
Registration Number

Abstract Study question Can time-lapse data be used to identify the optimum time to perform the fertilisation check for oocytes cultured in standard incubation? Summary answer The optimum time to perform fertilisation checks for oocytes cultured in standard incubation is 16.5hpi+/–0.5h. What is known already Time-lapse incubation allows the embryologist to retrospectively review collated images of oocytes and embryos to capture important embryological observations that may have otherwise been missed. This is a luxury not available to embryologists when oocytes or embryos are cultured in standard incubation. Traditionally, the optimum time to perform the fertilisation check is 17 hours post insemination (hpi) +/- 1 hour. It was hypothesised that this could be fine-tuned ensuring the maximum number of fertilised oocytes were observed, thereby increasing the number of usable embryos for the patient. Study design, size, duration This was a retrospective, multicentre analysis including data from 27,022 ICSI derived embryos cultured in time-lapse incubation between January 2011 to November 2019. Participants/materials, setting, methods The time of pronuclei appearance and disappearance was recorded using the time-lapse incubation software. The number of oocytes exhibiting normal fertilisation (defined as the presence of two pronuclei) during 30 minute intervals from 15hpi to 20hpi was determined. Main results and the role of chance Between 15–17.5hpi the average number of oocytes exhibiting normal fertilisation was 98.19% with most oocytes having visible pronuclei at 16–16.5hpi (98.32%). At 18–18.5hpi the number of visible pronuclei falls to 95.53% and continues to fall to 87.02% at 19.5–20hpi meaning that over 3000 (11%) normally fertilised oocytes, within this cohort, would not be identified. Limitations, reasons for caution The conclusions of this investigation cannot be effectively extrapolated to IVF embryos as only ICSI embryos were used for the determination of the results. Wider implications of the findings: The optimum time to perform fertilisation checks for oocytes cultured in standard incubation is 16.5hpi+/–0.5h. However, without the use of time-lapse incubation, the fertilisation of at least 2% of embryos that create a fetal heart will be missed, even if the fertilisation check is performed in the optimum window (16.5hpi+/–0.5h). Trial registration number Not applicable

scholarly journals Deletion of inositol-requiring enzyme-1α in podocytes disrupts glomerular capillary integrity and autophagy

2017 ◽  
Vol 28 (12) ◽  
pp. 1636-1651 ◽  
Author(s):  
Daniel Robert Kaufman ◽  
Joan Papillon ◽  
Louise Larose ◽  
Takao Iwawaki ◽  
Andrey V. Cybulsky
Keyword(s):  
Functional Role ◽  
Plasma Membranes ◽  
Normal Development ◽  
Dominant Negative ◽  
Male Mice ◽  
Glomerular Injury ◽  
Cross Sectional ◽  
Foot Process ◽  
Essential Function

Inositol-requiring enzyme-1α (IRE1α) is an endoplasmic reticulum (ER)–transmembrane endoribonuclease kinase that plays an essential function in extraembryonic tissues during normal development and is activated during ER stress. To address the functional role of IRE1α in glomerular podocytes, we produced podocyte-specific IRE1α-deletion mice. In male mice, deletion of IRE1α in podocytes resulted in albuminuria beginning at 5 mo of age and worsening with time. Electron microscopy revealed focal podocyte foot-process effacement in 9-mo-old male IRE1α-deletion mice, as well as microvillous transformation of podocyte plasma membranes. Compared with control, glomerular cross-sectional and capillary lumenal areas were greater in deletion mice, and there was relative podocyte depletion. Levels of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II expression and c-Jun N-terminal kinase-1 phosphorylation were decreased in IRE1α-deletion glomeruli, in keeping with reduced autophagy. Deletion of IRE1α exacerbated glomerular injury in anti–glomerular basement membrane nephritis. In cell culture, IRE1α dominant-negative mutants reduced the physiological (basal) accumulation of LC3B-II and the size of autophagic vacuoles but did not affect ER-associated degradation. Thus IRE1α is essential for maintaining podocyte and glomerular integrity as mice age and in glomerulonephritis. The mechanism is related, at least in part, to the maintenance of autophagy in podocytes.

scholarly journals N6-Methyladenosine Role in Cancer: Learning from AML

2018 ◽  
Author(s):  
Zaira Ianniello ◽  
Alessandro Fatica
Keyword(s):  
Functional Role ◽  
Cellular Differentiation ◽  
Normal Development ◽  
Cancer Development ◽  
Rna Modifications ◽  
Deep Impact ◽  
Rna Molecules ◽  
The World ◽  
Post Transcriptional Regulation

We are currently assisting at the explosion of the epitranscriptomics, which studies the functional role of chemical modifications into RNA molecules. Among more than 100 RNA modifications, the N6-methyladenosine (m6A), in particular, has attracted the interest of researchers all around the world. m6A is the most abundant internal chemical modification in mRNA and it can control any aspect of mRNA post-transcriptional regulation. m6A is installed by “writers”, removed by “erasers”, and recognized by “readers”, thus, it can be compared to the reversible and dynamic epigenetic modifications in histones and DNA. Given its fundamental role in determining the way mRNAs are expressed, it comes as no surprise that alterations to m6A modifications have a deep impact in cell differentiation, normal development and human diseases. Here, we review the proteins involved in m6A modification in mammals, m6A role in gene expression and its contribution to cancer development. In particular, we will focus on AML that, among first, has indicated how alteration in m6A modification can disrupt normal cellular differentiation and lead to cancer.

scholarly journals Functional role of increased acetylated tubulin in porcine oocyte microtubule structure, meiotic maturation and embryogenesis

2019 ◽  
Author(s):  
Junming Sun ◽  
Kuiqing Cui ◽  
Zhipeng Li ◽  
Bangjun Gao ◽  
Jianrong Jiang ◽  
...  
Keyword(s):  
Functional Role ◽  
Microtubule Assembly ◽  
Meiotic Maturation ◽  
Preimplantation Embryo Development ◽  
Acetylated Tubulin ◽  
Tubulin Acetylation ◽  
Abnormal Rate ◽  
Porcine Oocyte ◽  
Microtubule Structure

Abstract Acetylated microtubule improves porcine oocyte microtubule structure, meiotic maturation and subsequent embryonic development. HDAC6 can specifically deacetylate α-tubulin in assembled microtubules, increased acetylated microtubule treatment with tubacin, a HDAC6-selective inhibitor, is beneficial for porcine oocytes maturation and early embryogenesis. Here it is shown that α-tubulin acetylation gradually decreased from MI to IVF pronuclear stage. The increased acetylation of α-tubulin significantly reduced the abnormal rate of microtubules, furthermore, the proportion of mitochondria in the vicinity of IVF nucleus was significantly enhanced in MI and MII stages. The expression levels of microtubule assembly genes ( TUBA1A , α TAT1 and MAP2 ) significantly up-regulated in MI and MII stages. In addition, the oocytes with high acetylation level of α-tubulin significantly improved maturation, syngamy and IVF blastocyst formation compared with the control oocytes. In present study, these indicate functional role of increased acetylated α-tubulin advances normal spindle formation and mitochondrial concentration, moreover, improves porcine maturation, syngamy and preimplantation embryo development.

Role of Pax3/7 in the tectum regionalization

Development ◽  
2001 ◽  
Vol 128 (20) ◽  
pp. 4069-4077
Author(s):  
Eiji Matsunaga ◽  
Isato Araki ◽  
Harukazu Nakamura
Keyword(s):  
Optic Tectum ◽  
Normal Development ◽  
Marker Gene ◽  
Torus Semicircularis ◽  
Ventral Mesencephalon ◽  
Expression Domain ◽  
Dorsoventral Axis ◽  
Normal Expression ◽  
Sequential Induction

Pax3/7 is expressed in the alar plate of the mesencephalon. The optic tectum differentiates from the alar plate of the mesencephalon, and expression of Pax3/7 is well correlated to the tectum development. To explore the function of Pax3 and Pax7 in the tectum development, we misexpressed Pax3 and Pax7 in the diencephalon and ventral mesencephalon. Morphological and molecular marker gene analysis indicated that Pax3 and Pax7 misexpression caused fate change of the alar plate of the presumptive diencephalon to that of the mesencephalon, that is, a tectum and a torus semicircularis were formed ectopically. Ectopic tectum in the diencephalon appeared to be generated through sequential induction of Fgf8, En2 and Pax3/7. In ventral mesencephalon, which expresses En but does not differentiate to the tectum in normal development, Pax3 and Pax7 misexpression induced ectopic tectum. In normal development, Pax3 and Pax7 expression in the mesencephalon commences after Otx2, En and Pax2/5 expression. In addition, expression domain of Pax3 and Pax7 is well consistent with presumptive tectum region in a dorsoventral axis. Taken together with normal expression pattern of Pax3 and Pax7, results of misexpression experiments suggest that Pax3 and Pax7 define the tectum region subsequent to the function of Otx2 and En.

Localization of Intracisternal a Particle Antigens in Neoplastic Cells and Preimplantation Mouse Embryos

1980 ◽  
Vol 38 ◽  
pp. 696-697
Author(s):  
Thomas T.F. Huang ◽  
Patricia G. Calarco
Keyword(s):  
Endoplasmic Reticulum ◽  
Normal Development ◽  
Mouse Embryos ◽  
Neoplastic Cells ◽  
Large Numbers ◽  
Preimplantation Mouse Embryos ◽  
Preimplantation Mouse ◽  
Intracisternal A Particle ◽  
Normal Feature

The stage specific appearance of a retravirus, termed the Intracisternal A particle (IAP) is a normal feature of early preimplantation development. To date, all feral and laboratory strains of Mus musculus and even Asian species such as Mus cervicolor and Mus pahari express the particles during the 2-8 cell stages. IAP form by budding into the endoplasmic reticulum and appear singly or as groups of donut-shaped particles within the cisternae (fig. 1). IAP are also produced in large numbers in several neoplastic cells such as certain plasmacytomas and rhabdomyosarcomas. The role of IAP, either in normal development or in neoplastic behavior, is unknown.

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