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Kenji Sugioka, Lars-Eric Fielmich, Kota Mizumoto, Bruce Bowerman, Sander van den Heuvel, Akatsuki Kimura, Hitoshi Sawa
The adenomatous polyposis coli (APC) tumor suppressor has dual functions in Wnt/β-catenin signaling and accurate chromosome segregation and is frequently mutated in colorectal cancers. Although APC contributes to proper cell division, the underlying mechanisms remain poorly understood. Here we show that Caenorhabditis elegans APR-1/APC is an attenuator of the pulling forces acting on the mitotic spindle. During asymmetric cell division of the C. elegans zygote, a LIN-5/NuMA protein complex localizes dynein to the cell cortex to generate pulling forces on astral microtubules that position the mitotic spindle...
January 18, 2018: Proceedings of the National Academy of Sciences of the United States of America
Yi Xie, J Todd Blankenship
Despite extensive work on the mechanisms that generate plasma membrane furrows, understanding how cells are able to dynamically regulate furrow dimensions is an unresolved question. Here, we present an in-depth characterization of furrow behaviors and their regulation in vivo during early Drosophila morphogenesis. We show that the deepening in furrow dimensions with successive nuclear cycles is largely due to the introduction of a new, rapid ingression phase (Ingression II). Blocking the midblastula transition (MBT) by suppressing zygotic transcription through pharmacological or genetic means causes the absence of Ingression II, and consequently reduces furrow dimensions...
January 16, 2018: PLoS Genetics
Yi-Liang Miao, Andrés Gambini, Yingpei Zhang, Elizabeth Padilla-Banks, Wendy N Jefferson, Miranda L Bernhardt, Weichun Huang, Leping Li, Carmen J Williams
Understanding factors that regulate zygotic genome activation (ZGA) is critical for determining how cells are reprogrammed to become totipotent or pluripotent. There is limited information regarding how this process occurs physiologically in early mammalian embryos. Here we identify a mediator complex subunit, MED13, as translated during mouse oocyte maturation and transcribed early from the zygotic genome. Knockdown and conditional knockout approaches demonstrate that MED13 is essential for ZGA in the mouse, in part by regulating expression of the embryo-specific chromatin remodeling complex, esBAF...
January 9, 2018: Biology of Reproduction
Marie Teixeira, Bénédicte F Py, Christophe Bosc, Daphné Laubreton, Marie-Jo Moutin, Jacqueline Marvel, Frédéric Flamant, Suzy Markossian
In this report, we present an improved protocol for CRISPR/Cas9 genome editing in mice. The procedure consists in the electroporation of intact mouse zygotes with ribonucleoprotein complexes prepared in vitro from recombinant Cas9 nuclease and synthetic dual guide RNA. This simple cloning-free method proves to be extremely efficient for the generation of indels and small deletions by non-homologous end joining, and for the generation of specific point mutations by homology-directed repair. The procedure, which avoids DNA construction, in vitro transcription and oocyte microinjection, greatly simplifies genome editing in mice...
January 11, 2018: Scientific Reports
Jack da Silva
The disruptive selection theory of the evolution of anisogamy posits that the evolution of a larger body or greater organismal complexity selects for a larger zygote, which in turn selects for larger gametes. This may provide the opportunity for one mating type to produce more numerous, small gametes, forcing the other mating type to produce fewer, large gametes. Predictions common to this and related theories have been partially upheld. Here, a prediction specific to the disruptive selection theory is derived from a previously published game-theoretic model that represents the most complete description of the theory...
January 2018: Ecology and Evolution
Douglas W Houston
This protocol details the oocyte host-transfer method in Xenopus, using transplantation by intraperitoneal injection. This approach is suitable for the overexpression of mRNAs and for the use of antisense oligonucleotides to deplete maternal mRNAs, which are not replaced until zygotic genome activation in the mid-blastula transition. Xenopus oocyte host-transfer can also be used for highly efficient mutagenesis in the F0 generation by prefertilization injection of genome editing reagents.
January 10, 2018: Cold Spring Harbor Protocols
Romain Gibeaux, Rachael Acker, Maiko Kitaoka, Georgios Georgiou, Ila van Kruijsbergen, Breanna Ford, Edward M Marcotte, Daniel K Nomura, Taejoon Kwon, Gert Jan C Veenstra, Rebecca Heald
Hybridization of eggs and sperm from closely related species can give rise to genetic diversity, or can lead to embryo inviability owing to incompatibility. Although central to evolution, the cellular and molecular mechanisms underlying post-zygotic barriers that drive reproductive isolation and speciation remain largely unknown. Species of the African clawed frog Xenopus provide an ideal system to study hybridization and genome evolution. Xenopus laevis is an allotetraploid with 36 chromosomes that arose through interspecific hybridization of diploid progenitors, whereas Xenopus tropicalis is a diploid with 20 chromosomes that diverged from a common ancestor approximately 48 million years ago...
January 10, 2018: Nature
Evi Goulielmaki, Sofia Kaforou, Kannan Venugopal, Thanasis G Loukeris, Inga Siden-Kiamos, Konstantinos Koussis
In an effort to eradicate malaria, new interventions are proposed to include compound/vaccine development against pre-erythrocytic, erythrocytic and mosquito stages of Plasmodium. Drug repurposing might be an alternative approach to new antimalarials reducing the cost and the time required for drug development. Previous in vitro studies have examined the effects of protease inhibitors on different stages of the Plasmodium parasite, although the clinical relevance of this remains unclear. In this study we tested the putative effect of three HIV protease inhibitors, two general aspartyl protease inhibitors and three AAA-p97 ATPase inhibitors on the zygote to ookinete transition of the Plasmodium parasite...
January 3, 2018: Molecular and Biochemical Parasitology
Javier García-Ferreyra, Roly Hilario, Julio Dueñas
OBJECTIVE: Advanced paternal age is related to poor sperm quality; however, little is known on its effect on aneuploidy embryo rates and, more importantly, on chromosomal abnormalities like trisomy 21, 18 and 13. The objective of this study was to evaluate the effect of advanced paternal age on the trisomy rates of the chromosomes 21, 18 or 13 in embryos obtained from donated oocytes. METHODS: A total of 378 embryos, obtained from 52 IVF/ICSI cycles with donated oocytes in conjunction with PGD, were allocated according to paternal age in three groups: Group A: ≤39 years (n=115 embryos), Group B: 40-49 years (n=157 embryos) and Group C: ≥50 year (n=106 embryos)...
January 5, 2018: JBRA Assisted Reproduction
Yanzhen Bi, Zaidong Hua, Hongyan Ren, Liping Zhang, Hongwei Xiao, Ximei Liu, Wenjun Hua, Shuqi Mei, Adrian Molenaar, Götz Laible, Xinmin Zheng
Programmable nucleases have allowed the rapid development of gene editing and transgenics, but the technology still suffers from the lack of predefined genetic loci for reliable transgene expression and maintenance. To address this issue, we used ФC31 integrase to navigate the porcine genome and identify the pseudo attP sites suitable as safe harbors for sustained transgene expression. The combined ФC31 integrase mRNA and an enhanced green fluorescence protein (EGFP) reporter donor were microinjected into one-cell zygotes for transgene integration...
January 4, 2018: International Journal of Molecular Sciences
Alexei N Korablev, Irina A Serova, Oleg L Serov
BACKGROUND: Copy Number Variation (CNV) of the human CNTN6 gene (encoding the contactin-6 protein), caused by deletions or duplications, is responsible for severe neurodevelopmental impairments, often in combination with facial dysmorphias. Conversely, deleterious point mutations of this gene do not show any clinical phenotypes. The aim of this study is to generate mice carrying large deletions, duplications and inversions involving the Cntn6 gene as a new experimental model to study CNV of the human CNTN6 locus...
December 28, 2017: BMC Genetics
Richard Behringer, Marina Gertsenstein, Kristina Vintersten Nagy, Andras Nagy
For experiments that require large numbers of preimplantation mouse embryos, such as microinjection of zygotes, gonadotropins are administered to females before mating to increase the number of oocytes that are ovulated (i.e., to induce superovulation). Pregnant mare serum gonadotropin (PMSG) is used to mimic the oocyte maturation effect of the endogenous follicle-stimulating hormone (FSH), and human chorionic gonadotropin (hCG) is used to mimic the ovulation induction effect of luteinizing hormone (LH).
January 2, 2018: Cold Spring Harbor Protocols
Stephanie Eckerle, Mario Ringler, Virginie Lecaudey, Roland Nitschke, Wolfgang Driever
Control of microtubule dynamics is crucial for cell migration. We analyzed regulation of microtubule network dynamics in the zebrafish yolk cell during epiboly, the earliest coordinated gastrulation movement. We labeled microtubules with EMTB-3GFP and EB3-mCherry to visualize and measure microtubule dynamics by TIRF microscopy live imaging. Yolk cell microtubules dynamics is temporally modulated during epiboly progression. We used maternal zygotic Pou5f3 mutant (MZspg) embryos, which develop strong distortions of microtubule network organization and epiboly retardation, to investigate genetic control of microtubule dynamics...
December 26, 2017: Developmental Biology
Carlos Patino Descovich, Daniel B Cortes, Sean Ryan, Jazmine Nash, Li Zhang, Paul S Maddox, Francois Nedelec, Amy Shaub Maddox
Cell shape changes such as cytokinesis are driven by the actomyosin contractile cytoskeleton. The molecular rearrangements that bring about contractility in nonmuscle cells are currently debated. Specifically, both filament sliding by myosin motors, as well as cytoskeletal crosslinking by myosins and nonmotor crosslinkers, are thought to promote contractility. Here, we examined how the abundance of motor and nonmotor crosslinkers affects the speed of cytokinetic furrowing. We built a minimal model to simulate contractile dynamics in the C...
December 27, 2017: Molecular Biology of the Cell
Yawei Gao, Xiaoyu Liu, Bin Tang, Chong Li, Zhaohui Kou, Lin Li, Wenqiang Liu, You Wu, Xiaochen Kou, Jingyi Li, Yanhong Zhao, Jiqing Yin, Hong Wang, She Chen, Lujian Liao, Shaorong Gao
Pre-implantation embryo development is an intricate and precisely regulated process orchestrated by maternally inherited proteins and newly synthesized proteins following zygotic genome activation. Although genomic and transcriptomic studies have enriched our understanding of the genetic programs underlying this process, the protein expression landscape remains unexplored. Using quantitative mass spectrometry, we identified nearly 5,000 proteins from 8,000 mouse embryos of each stage (zygote, 2-cell, 4-cell, 8-cell, morula, and blastocyst)...
December 26, 2017: Cell Reports
Hai-Bo Xu, Yong-Xin Li, Yan Li, Newton O Otecko, Ya-Ping Zhang, Bingyu Mao, Dong-Dong Wu
New genes are drivers of evolutionary innovation and phenotypic evolution. Expression of new genes in early development raises the possibility that new genes could originate and be recruited for functions in embryonic development, but this remains undocumented. Here, based on temporal gene expression at different developmental stages in Xenopus tropicalis, we found that young protein-coding genes were significantly enriched for expression in developmental stages occurring after the midblastula transition (MBT), and displayed a decreasing trend in abundance in the subsequent stages after MBT...
December 21, 2017: Journal of Molecular Cell Biology
Morgane Roth, Ana M Florez-Rueda, Stephan Griesser, Margot Paris, Thomas Städler
Background and Aims: Defective hybrid seed development in angiosperms might mediate the rapid establishment of intrinsic post-zygotic isolation between closely related species. Extensive crosses within and among three lineages of wild tomatoes (Solanum section Lycopersicon) were performed to address the incidence, developmental timing and histological manifestations of hybrid seed failure. These lineages encompass different, yet fairly recent, divergence times and both allopatric and partially sympatric pairs...
December 21, 2017: Annals of Botany
David Blom-Dahl, Natalia Azpiazu
The eyegone (eyg) gene encodes Eyg, a transcription factor of the Pax family with multiple roles during Drosophila development. Eyg has been shown to be nuclear in the cells where it functions. In this report we describe a new functional cytoplasmic distribution of Eyg during egg chamber development in the female ovarioles. The protein is present from the germarium until stage 10 of cyst development. The majority of egg chambers that develop in the absence of Eyg arrest their development before stage 10, show augmented levels of the telomeric retro-transposon TART-A and low levels of heterochromatin marks in the oocyte nucleus...
December 23, 2017: Developmental Biology
Bingjie Han, Katianna R Antkowiak, Xintao Fan, Mallory Rutigliano, Sean P Ryder, Erik E Griffin
Intracellular protein gradients underlie essential cellular and developmental processes, but the mechanisms by which they are established are incompletely understood. During the asymmetric division of the C. elegans zygote, the RNA-binding protein MEX-5 forms an anterior-rich cytoplasmic gradient that causes the RNA-binding protein POS-1 to form an opposing, posterior-rich gradient. We demonstrate that the polo-like kinase PLK-1 mediates the repulsive coupling between MEX-5 and POS-1 by increasing the mobility of POS-1 in the anterior...
December 19, 2017: Current Biology: CB
Danielle C Hamm, Elizabeth D Larson, Markus Nevil, Kelsey E Marshall, Eliana R Bondra, Melissa M Harrison
In nearly all metazoans, the earliest stages of development are controlled by maternally deposited mRNAs and proteins. The zygotic genome becomes transcriptionally active hours after fertilization. Transcriptional activation during this maternal-to-zygotic transition (MZT) is tightly coordinated with the degradation of maternally provided mRNAs. In Drosophila melanogaster, the transcription factor Zelda plays an essential role in widespread activation of the zygotic genome. While Zelda expression is required both maternally and zygotically, the mechanisms by which it functions to remodel the embryonic genome and prepare the embryo for development remain unclear...
December 19, 2017: PLoS Genetics
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