Publications by authors named "Cecilia S Blengini"

8 Publications

  • Page 1 of 1

Aurora kinase A is essential for meiosis in mouse oocytes.

PLoS Genet 2021 Apr 26;17(4):e1009327. Epub 2021 Apr 26.

Department of Genetics; Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America.

The Aurora protein kinases are well-established regulators of spindle building and chromosome segregation in mitotic and meiotic cells. In mouse oocytes, there is significant Aurora kinase A (AURKA) compensatory abilities when the other Aurora kinase homologs are deleted. Whether the other homologs, AURKB or AURKC can compensate for loss of AURKA is not known. Using a conditional mouse oocyte knockout model, we demonstrate that this compensation is not reciprocal because female oocyte-specific knockout mice are sterile, and their oocytes fail to complete meiosis I. In determining AURKA-specific functions, we demonstrate that its first meiotic requirement is to activate Polo-like kinase 1 at acentriolar microtubule organizing centers (aMTOCs; meiotic spindle poles). This activation induces fragmentation of the aMTOCs, a step essential for building a bipolar spindle. We also show that AURKA is required for regulating localization of TACC3, another protein required for spindle building. We conclude that AURKA has multiple functions essential to completing MI that are distinct from AURKB and AURKC.
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http://dx.doi.org/10.1371/journal.pgen.1009327DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8102010PMC
April 2021

Unscrambling the oocyte and the egg: clarifying terminology of the female gamete in mammals.

Mol Hum Reprod 2020 11;26(11):797-800

Reproductive Medicine Group, National Institute of Environmental Health Sciences, Durham, NC, USA.

Most reproductive biologists who study female gametes will agree with the 16th century anatomist William Harvey's doctrine: 'Ex Ovo Omnia'. This phrase, which literally translates to 'everything from the egg', recognizes the centrality of the egg in animal development. Eggs are most impressive cells, capable of supporting development of an entirely new organism following fertilization or parthenogenetic activation. Not so uniformly embraced in the field of reproductive biology is the nomenclature used to refer to the female germ cell. What is an oocyte? What is an egg? Are these terms the same, different, interchangeable? Here we provide functional definitions of the oocyte and egg, and how they can be used in the context of mammalian gamete biology and beyond.
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http://dx.doi.org/10.1093/molehr/gaaa066DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7648930PMC
November 2020

SIRT7 promotes chromosome synapsis during prophase I of female meiosis.

Chromosoma 2019 09 29;128(3):369-383. Epub 2019 Jun 29.

Department of Genetics, Rutgers University, 145 Bevier Rd., Piscataway, NJ, 08854, USA.

Sirtuins are NAD-dependent protein deacylases and ADP-ribosyltransferases that are involved in a wide range of cellular processes including genome homeostasis and metabolism. Sirtuins are expressed in human and mouse oocytes yet their role during female gamete development are not fully understood. Here, we investigated the role of a mammalian sirtuin member, SIRT7, in oocytes using a mouse knockout (KO) model. Sirt7 KO females have compromised fecundity characterized by a rapid fertility decline with age, suggesting the existence of a diminished oocyte pool. Accordingly, Sirt7 KO females produced fewer oocytes and ovulated fewer eggs. Because of the documented role of SIRT7 in DNA repair, we investigated whether SIRT7 regulates prophase I when meiotic recombination occurs. Sirt7 KO pachynema-like staged oocytes had approximately twofold increased γH2AX signals associated with regions with unsynapsed chromosomes. Consistent with the presence of asynaptic chromosome regions, Sirt7 KO oocytes had fewer MLH1 foci (~one less), a mark of crossover-mediated repair, than WT oocytes. Moreover, this reduced level of crossing over is consistent with an observed twofold increased incidence of aneuploidy in Metaphase II eggs. In addition, we found that acetylated lysine 18 of histone H3 (H3K18ac), an established SIRT7 substrate, was increased at asynaptic chromosome regions suggesting a functional relationship between this epigenetic mark and chromosome synapsis. Taken together, our findings demonstrate a pivotal role for SIRT7 in oocyte meiosis by promoting chromosome synapsis and have unveiled the importance of SIRT7 as novel regulator of the reproductive lifespan.
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http://dx.doi.org/10.1007/s00412-019-00713-9DOI Listing
September 2019

Immunofluorescence Technique to Detect Subcellular Structures Critical to Oocyte Maturation.

Methods Mol Biol 2018 ;1818:67-76

Department of Genetics, Rutgers University, Piscataway, NJ, USA.

Immunofluorescence is a useful technique for analysis of protein expression and localization, thereby providing information regarding protein function, regulation, and protein-protein interactions. It is a standard approach to determine the temporal and spatial location of gene products that function in oocyte meiotic maturation. Fixation is one of the critical steps in the immunofluorescence protocol. Here, we describe the use of antibodies that are widely utilized in oocytes studies: anti-centromeric antigen (ACA), anti-Aurora kinase A (AURKA) and anti-alpha and gamma-tubulin antibodies that require different technical approaches for successful visualization, and we provide protocols for these conditions that are amenable to mouse oocyte studies. Detection of these proteins provides phenotypic information about spindle morphology, chromosome alignment, and microtubule attachments to kinetochores critical to assessing oocyte quality.
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http://dx.doi.org/10.1007/978-1-4939-8603-3_8DOI Listing
March 2019

Maternal RNA regulates Aurora C kinase during mouse oocyte maturation in a translation-independent fashion.

Biol Reprod 2017 Jun;96(6):1197-1209

Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA.

During oocyte meiotic maturation, Aurora kinase C (AURKC) is required to accomplish many critical functions including destabilizing erroneous kinetochore-microtubule (K-MT)attachments and regulating bipolar spindle assembly. How localized activity of AURKC is regulated in mammalian oocytes, however, is not fully understood. Female gametes from many species, including mouse, contain stores of maternal transcripts that are required for downstream developmental events. We show here that depletion of maternal RNA in mouse oocytes resulted in impaired meiotic progression, increased incidence of chromosome misalignment and abnormal spindle formation at metaphase I (Met I), and cytokinesis defects. Importantly, depletion of maternal RNA perturbed the localization and activity of AURKC within the chromosomal passenger complex (CPC). These perturbations were not observed when translation was inhibited by cycloheximide (CHX) treatment. These results demonstrate a translation-independent function of maternal RNA to regulate AURKC-CPC function in mouse oocytes.
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http://dx.doi.org/10.1093/biolre/iox047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6279119PMC
June 2017

Pre- and Postcopulatory Traits of Salvator Male Lizards in Allopatry and Sympatry.

Scientifica (Cairo) 2016 24;2016:8176267. Epub 2016 Mar 24.

Instituto de Diversidad y Ecología Animal (IDEA), CONICET and Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Vélez Sársfield 299, X5000JJC Córdoba, Argentina.

The reproductive traits of males are under influence of sexual pressures before and after copulation. The strength of sexual selection varies across populations because they undergo varying competition for mating opportunities. Besides intraspecific pressures, individuals seem to be subjected to pressures driven by interspecific interactions in sympatry. Lizards may vary their reproductive strategies through varying sexual characters, body size, gonadal investment, and sperm traits. We evaluated the reproductive traits, involved in pre- and postcopulatory competition, in allopatric and sympatric populations of Salvator lizards. We observed a spatial gradient of male competition among populations, with the following order: allopatric zone of S. rufescens; sympatric zone; and allopatric zone of S. merianae. Accordingly, variation in secondary sexual character, the relative testis mass, and the length of sperm component was observed between allopatry and sympatry in each species, suggesting differences in the investment of reproductive traits. However, we found that these two Salvator species did not differ in secondary sexual characters in sympatry. Interestingly, the trade-off between testes and muscle varied differently from allopatry to sympatry between these Salvator species, suggesting that the influence of social context on reproductive traits investment would affect lizard species differently.
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http://dx.doi.org/10.1155/2016/8176267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4823511PMC
April 2016

Variability in sperm form and function in the context of sperm competition risk in two Tupinambis lizards.

Ecol Evol 2014 Nov 7;4(21):4080-92. Epub 2014 Oct 7.

Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Instituto de Diversidad y Ecología Animal (IDEA) CONICET, Universidad Nacional de Córdoba Av. Vélez Sársfield 299, X5000JJC, Córdoba, Argentina.

In polyandrous species, sperm morphometry and sperm velocity are under strong sexual selection. Although several hypotheses have been proposed to explain the role of sperm competition in sperm trait variation, this aspect is still poorly understood. It has been suggested that an increase in sperm competition pressure could reduce sperm size variation or produce a diversity of sperm to maximize male fertilization success. We aim at elucidating the variability of sperm morphometric traits and velocity in two Tupinambis lizards in the context of sperm competition risk. Sperm traits showed substantial variation at all levels examined: between species, among males within species, and within the ejaculate of individual males. Sperm velocity was found to be positively correlated with flagellum: midpiece ratio, with relatively longer flagella associated with faster sperm. Our results document high variability in sperm form and function in lizards.
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http://dx.doi.org/10.1002/ece3.1262DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4242561PMC
November 2014

Female mediation of competitive fertilization success in Drosophila melanogaster.

Proc Natl Acad Sci U S A 2013 Jun 11;110(26):10693-8. Epub 2013 Jun 11.

Department of Biology, Syracuse University, Syracuse, NY 13244, USA.

How females store and use sperm after remating can generate postcopulatory sexual selection on male ejaculate traits. Variation in ejaculate performance traits generally is thought to be intrinsic to males but is likely to interact with the environment in which sperm compete (e.g., the female reproductive tract). Our understanding of female contributions to competitive fertilization success is limited, however, in part because of the challenges involved in observing events within the reproductive tract of internally fertilizing species while discriminating among sperm from competing males. Here, we used females from crosses among isogenic lines of Drosophila melanogaster, each mated to two genetically standardized males (the first with green- and the second with red-tagged sperm heads) to demonstrate heritable variation in female remating interval, progeny production rate, sperm-storage organ morphology, and a number of sperm performance, storage, and handling traits. We then used multivariate analyses to examine relationships between this female-mediated variation and competitive paternity. In particular, the timing of female ejection of excess second-male and displaced first-male sperm was genetically variable and, by terminating the process of sperm displacement, significantly influenced the relative numbers of sperm from each male competing for fertilization, and consequently biased paternity. Our results demonstrate that females do not simply provide a static arena for sperm competition but rather play an active and pivotal role in postcopulatory processes. Resolving the adaptive significance of genetic variation in female-mediated mechanisms of sperm handling is critical for understanding sexual selection, sexual conflict, and the coevolution of male and female reproductive traits.
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http://dx.doi.org/10.1073/pnas.1300954110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3696778PMC
June 2013