Publications by authors named "Ahmed Z Balboula"

15 Publications

  • Page 1 of 1

Loop-mediated isothermal amplification (LAMP) and machine learning application for early pregnancy detection using bovine vaginal mucosal membrane.

Biochem Biophys Res Commun 2021 Sep 10;569:179-186. Epub 2021 Jul 10.

Graduate School of Global Food Resources/Global Center for Food, Land and Water Resources, Hokkaido University, Sapporo, Hokkaido, 060-8589, Japan. Electronic address:

An early and accurate pregnancy diagnosis method is required to improve the reproductive performance of cows. Here we developed an easy pregnancy detection method using vaginal mucosal membrane (VMM) with application of Reverse Transcription-Loop-mediated Isothermal Amplification (RT-LAMP) and machine learning. Cows underwent artificial insemination (AI) on day 0, followed by VMM-collection on day 17-18, and pregnancy diagnosis by ultrasonography on day 30. By RNA sequencing of VMM samples, three candidate genes for pregnancy markers (ISG15 and IFIT1: up-regulated, MUC16: down-regulated) were selected. Using these genes, we performed RT-LAMP and calculated the rise-up time (RUT), the first-time absorbance exceeded 0.05 in the reaction. We next determined the cutoff value and calculated accuracy, sensitivity, specificity, positive prediction value (PPV), and negative prediction value (NPV) for each marker evaluation. The IFIT1 scored the best performance at 92.5% sensitivity, but specificity was 77.5%, suggesting that it is difficult to eliminate false positives. We then developed a machine learning model trained with RUT of each marker combination to predict pregnancy. The model created with the RUT of IFIT1 and MUC16 combination showed high specificity (86.7%) and sensitivity (93.3%), which were higher compared to IFIT1 alone. In conclusion, using VMM with RT-LAMP and machine learning algorithm can be used for early pregnancy detection before the return of first estrus.
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http://dx.doi.org/10.1016/j.bbrc.2021.07.015DOI Listing
September 2021

Capture and metabolomic analysis of the human endometrial epithelial organoid secretome.

Proc Natl Acad Sci U S A 2021 Apr;118(15)

Division of Animal Sciences, University of Missouri, Columbia, MO 65211;

Suboptimal uterine fluid (UF) composition can lead to pregnancy loss and likely contributes to offspring susceptibility to chronic adult-onset disorders. However, our understanding of the biochemical composition and mechanisms underpinning UF formation and regulation remain elusive, particularly in humans. To address this challenge, we developed a high-throughput method for intraorganoid fluid (IOF) isolation from human endometrial epithelial organoids. The IOF is biochemically distinct to the extraorganoid fluid (EOF) and cell culture medium as evidenced by the exclusive presence of 17 metabolites in IOF. Similarly, 69 metabolites were unique to EOF, showing asymmetrical apical and basolateral secretion by the in vitro endometrial epithelium, in a manner resembling that observed in vivo. Contrasting the quantitative metabolomic profiles of IOF and EOF revealed donor-specific biochemical signatures of organoids. Subsequent RNA sequencing of these organoids from which IOF and EOF were derived established the capacity to readily perform organoid multiomics in tandem, and suggests that transcriptomic regulation underpins the observed secretory asymmetry. In summary, these data provided by modeling uterine luminal and basolateral fluid formation in vitro offer scope to better understand UF composition and regulation with potential impacts on female fertility and offspring well-being.
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http://dx.doi.org/10.1073/pnas.2026804118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8053979PMC
April 2021

Yes-associated protein 1 translocation through actin cytoskeleton organization in trophectoderm cells.

Dev Biol 2020 12 15;468(1-2):14-25. Epub 2020 Sep 15.

Laboratory of Animal Breeding and Reproduction, Research Faculty of Agriculture, Hokkaido University, Kita-ku Kita 9 Nishi 9, Sapporo, 060-8589, Japan. Electronic address:

A mammalian embryo experiences the first cell segregation at the blastocyst stage, in which cells giving form to the embryo are sorted into two lineages; trophectoderm (TE) and inner cell mass (ICM). This first cell segregation process is governed by cell position-dependent Hippo signaling, which is a phosphorylation cascade determining whether Yes-associated protein 1 (YAP1), one of the key components of the Hippo signaling pathway, localizes within the nucleus or cytoplasm. YAP1 localization determines the transcriptional on/off switch of a key gene, Cdx2, required for TE differentiation. However, the control mechanisms involved in YAP1 nucleocytoplasmic shuttling post blastocyst formation remain unknown. This study focused on the mechanisms involved in YAP1 release from TE nuclei after blastocoel contraction in bovine blastocysts. The blastocysts contracted by blastocoel fluid aspiration showed that the YAP1 translocation from nucleus to cytoplasm in the TE cells was concomitant with the protruded actin cytoskeleton. This YAP1 release from TE nuclei in the contracted blastocysts was prevented by actin disruption and stabilization. In contrast, Y27632, which is a potent inhibitor of Rho-associated coiled-coil containing protein kinase 1/2 (ROCK) activity, was found to promote YAP1 nuclear localization in the TE cells of contracted blastocysts. Meanwhile, lambda protein phosphatase (LPP) treatment inducing protein dephosphorylation could not prevent YAP1 release from TE nuclei in the contracted blastocysts, indicating that YAP1 release from TE nuclei does not depend on the Hippo signaling pathway. These results suggested that blastocyst contraction causes YAP1 release from TE nuclei through actin cytoskeleton remodeling in a Hippo signaling-independent manner. Thus, the present study raised the possibility that YAP1 subcellular localization is controlled by actin cytoskeletal organization after the blastocyst formation. Our results demonstrate diverse regulatory mechanisms for YAP1 nucleocytoplasmic shuttling in TE cells.
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http://dx.doi.org/10.1016/j.ydbio.2020.09.004DOI Listing
December 2020

Vitrification-induced activation of lysosomal cathepsin B perturbs spindle assembly checkpoint function in mouse oocytes.

Mol Hum Reprod 2020 09;26(9):689-701

Research Faculty of Agriculture, Hokkaido University, Hokkaido 060-8589, Japan.

As the age of child-bearing increases and correlates with infertility, cryopreservation of female gametes is becoming common-place in ART. However, the developmental competence of vitrified oocytes has remained low. The underlying mechanisms responsible for reduced oocyte quality post-vitrification are largely unknown. Mouse cumulus-oocyte complexes were vitrified using a cryoloop technique and a mixture of dimethylsulphoxide, ethylene glycol and trehalose as cryoprotectants. Fresh and vitrified/thawed oocytes were compared for chromosome alignment, spindle morphology, kinetochore-microtubule attachments, spindle assembly checkpoint (SAC) and aneuploidy. Although the majority of vitrified oocytes extruded the first polar body (PB), they had a significant increase of chromosome misalignment, abnormal spindle formation and aneuploidy at metaphase II. In contrast to controls, vitrified oocytes extruded the first PB in the presence of nocodazole and etoposide, which should induce metaphase I arrest in a SAC-dependent manner. The fluorescence intensity of mitotic arrest deficient 2 (MAD2), an essential SAC protein, at kinetochores was reduced in vitrified oocytes, indicating that the SAC is weakened after vitrification/thawing. Furthermore, we found that vitrification-associated stress disrupted lysosomal function and stimulated cathepsin B activity, with a subsequent activation of caspase 3. MAD2 localization and SAC function in vitrified oocytes were restored upon treatment with a cathepsin B or a caspase 3 inhibitor. This study was conducted using mouse oocytes, therefore confirming these results in human oocytes is a prerequisite before applying these findings in IVF clinics. Here, we uncovered underlying molecular pathways that contribute to an understanding of how vitrification compromises oocyte quality. Regulating these pathways will be a step toward improving oocyte quality post vitrification and potentially increasing the efficiency of the vitrification program.
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http://dx.doi.org/10.1093/molehr/gaaa051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7828578PMC
September 2020

Inverse relationship between autophagy and CTSK is related to bovine embryo quality.

Reproduction 2020 06;159(6):757-766

Research Faculty of Agriculture, Hokkaido University, Hokkaido, Japan.

Improving the quality and the developmental competence of in vitro produced (IVP) embryos is an indispensable goal for assisted reproductive technology. Autophagy is a major protective mechanism for intracellular degradation of unnecessary cytoplasmic components. Autophagy ends by the fusion between autophagic vacuoles and lysosomes, allowing the degradation of the cargo by lysosomal enzymes, especially the cathepsins (CTSs). However, it is still unclear how autophagy and cathepsin K (CTSK) relate to embryo development. This study evaluated (1.) the activities of autophagy and CTSK in relation to bovine embryo quality and (2.) the effect of autophagy induction and/or CTSK inhibition on preimplantation embryo development and quality. We show here that good-quality embryos exhibited a greater autophagic activity and less CTSK activity compared to poor-quality embryos. Blastomeres of an individual embryo may vary in their quality. Good quality blastomeres showed an increased autophagic activity and decreased CTSK activity compared to poor-quality blastomeres within the same embryo at different developmental stages. Importantly, induction of autophagy and/or inhibition of CTSK improved the developmental rate (increased blastocyst and hatching rates) and the quality (increased total cell number and decreased the percentage of apoptotic cells) of IVP bovine embryos. These results demonstrate a promising approach to selectively isolate good-quality embryos and improve the efficiency of IVEP of cattle embryos.
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http://dx.doi.org/10.1530/REP-20-0036DOI Listing
June 2020

Hot topic: Pregnancy-induced expression of interferon-stimulated genes in the cervical and vaginal mucosal membranes.

J Dairy Sci 2018 Sep 21;101(9):8396-8400. Epub 2018 Jun 21.

Laboratory of Animal Breeding and Reproduction, Department of Animal Science, Research Faculty of Agriculture, Hokkaido University, Hokkaido 060-8589, Japan. Electronic address:

In ruminants, IFN-tau (IFNT) is a pregnancy recognition signal secreted by the embryonic trophectoderm before implantation, and it induces the expression of IFN-stimulated genes (ISG) in the uterine endometrium and blood leukocytes. The expression of ISG in blood leukocytes could indicate the presence of a viable conceptus before return of the next estrus; however, expression levels have high variation for confirming pregnancy. We hypothesized that the secreted IFNT in the uterus would affect ISG expression in cervical and vaginal tissues because they are directly adjacent to the uterus. To prove the hypothesis, we investigated the expression of 3 ISG (ISG15, MX1, and MX2) in cervical and vaginal mucosal membranes collected from pregnant (n = 12) and nonpregnant (n = 11) lactating Holstein cows at 17 to 18 d after artificial insemination. Mucosal membrane samples of the cervical canal near the external os (cervix) and deep vaginal wall surrounding the external os (vagina) were collected separately by simply scraping with a curette on d 17 or 18 of pregnancy (d 1 = ovulation), at which time IFNT secretion into the maternal uterus is maximal. After pregnancy diagnosis on d 30 and 60, separately collected samples confirmed as pregnant and nonpregnant were used for evaluation of the expression of IFN-stimulated protein 15 kDa (ISG15) and myxovirus-resistance protein 1 and 2 (MX1, MX2) with quantitative real-time PCR. The collected mucosal membrane samples from cervix contained mostly cell clots showing membrane structure and a low content of blood cells. The expression levels of all 3 genes were significantly increased in pregnant cows compared with nonpregnant cows in both cervical and vaginal samples. These results suggest that increased expression of ISG in the cervix and vagina is a pregnancy-associated phenomenon and is highly affected by IFNT secreted from the conceptus through the uterus.
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http://dx.doi.org/10.3168/jds.2017-14251DOI Listing
September 2018

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

Estrous cycle stage-dependent manner of type I interferon-stimulated genes induction in the bovine endometrium.

J Reprod Dev 2017 Jun 26;63(3):211-220. Epub 2017 Feb 26.

Laboratory of Animal Genetics and Reproduction, Department of Animal Science, Research Faculty of Agriculture, Hokkaido University, Hokkaido 060-8589, Japan.

Interferon tau (IFN-τ) is a ruminant-specific type I IFN secreted by a conceptus before its attachment to the uterus. IFN-τ induces the expression of IFN-stimulated genes (ISGs) via the type I IFN receptor (IFNAR), which is composed of IFNAR1 and IFNAR2 subunits in the endometrium. However, expression patterns of IFNARs during the estrous cycle have not been reported. We hypothesized that the response to a type I IFN changes along with IFNARs and the IFN-regulatory factors (IRFs) driving transcription of IFN signal-related genes and modulating a type I IFN signal during the estrous cycle. We investigated the estrous cycle stage-dependent type I IFN induction of ISGs and expression patterns of IFN signal-related genes in bovine endometrial tissues. Endometrial tissue pieces collected from bovine uteri at each estrous stage (early, mid, and late) were cultured with or without recombinant bovine IFN-α or concentrated pregnant uterine flushing (PUF) on day 18 after confirming the presence of a conceptus. IFN-α and PUF each significantly increased the expression of ISGs in endometrial tissues. The induction levels of the typical ISGs (MX1-a and ISG15) were significantly higher at the mid stage and correlated with high expression of IRFs at the mid stage. The immunostaining of IFNARs showed strong fluorescence intensities in luminal and glandular epithelia at the early and mid stages. Collectively, these results suggest that the endometrium exhibits estrous cycle stage-dependent responsiveness to type I IFN that may be associated with the expression of IFNARs and IRFs for pregnancy recognition.
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http://dx.doi.org/10.1262/jrd.2016-176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5481623PMC
June 2017

Haspin kinase regulates microtubule-organizing center clustering and stability through Aurora kinase C in mouse oocytes.

J Cell Sci 2016 10 25;129(19):3648-3660. Epub 2016 Aug 25.

Department of Genetics, 145 Bevier Road, Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8082, USA

Meiotic oocytes lack classic centrosomes and, therefore, bipolar spindle assembly depends on clustering of acentriolar microtubule-organizing centers (MTOCs) into two poles. However, the molecular mechanism regulating MTOC assembly into two poles is not fully understood. The kinase haspin (also known as GSG2) is required to regulate Aurora kinase C (AURKC) localization at chromosomes during meiosis I. Here, we show that inhibition of haspin perturbed MTOC clustering into two poles and the stability of the clustered MTOCs. Furthermore, we show that AURKC localizes to MTOCs in mouse oocytes. Inhibition of haspin perturbed the localization of AURKC at MTOCs, and overexpression of AURKC rescued the MTOC-clustering defects in haspin-inhibited oocytes. Taken together, our data uncover a role for haspin as a regulator of bipolar spindle assembly by regulating AURKC function at acentriolar MTOCs in oocytes.
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http://dx.doi.org/10.1242/jcs.189340DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5087654PMC
October 2016

RBBP4 regulates histone deacetylation and bipolar spindle assembly during oocyte maturation in the mouse.

Biol Reprod 2015 Apr 18;92(4):105. Epub 2015 Mar 18.

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

During meiosis I (MI) in oocytes, the maturation-associated decrease of histone acetylation is critical for normal meiotic progression and accurate chromosome segregation. RBBP4 is a component of several different histone deacetylase containing chromatin-remodeling complexes, but RBBP4's role in regulating MI is not known. Depleting RBBP4 in mouse oocytes resulted in multipolar spindles at metaphase (Met) I with subsequent perturbed meiotic progression and increased incidence of abnormal spindles, chromosome misalignment, and aneuploidy at Met II. We attribute these defects to improper deacetylation of histones because histones H3K4, H4K8, H4K12, and H4K16 were hyperacetylated in RBBP4-depleted oocytes. Importantly, we show that RBBP4-mediated histone deacetylation is essential for regulating bipolar spindle assembly, at least partially, through promoting Aurora kinase (AURK) C function. To our knowledge, these results are the first to identify RBBP4 as a regulator of histone deacetylation during oocyte maturation, and they provide evidence that deacetylation is required for bipolar spindle assembly through AURKC.
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http://dx.doi.org/10.1095/biolreprod.115.128298DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4643954PMC
April 2015

Heat stress during in vitro fertilization decreases fertilization success by disrupting anti-polyspermy systems of the oocytes.

Mol Reprod Dev 2015 Jan 2;82(1):36-47. Epub 2014 Dec 2.

Livestock and Grassland Research Division, Kyushu Okinawa Agricultural Research Center, NARO, Kumamoto, Japan.

Low pregnancy rates during the summer are due, in part, to reduced fertilization. Given that elevated temperature is associated with this season, we investigated the effect of heat stress during fertilization using an in vitro model. Three experiments were performed to determine the mechanism by which exposure to elevated temperature disrupts fertilization. Oocytes were fertilized for 6 hr at 38.5°C or 41.0°C or 40.0°C with non-pre-incubated sperm, or for 6 hr at 38.5°C with sperm that had been pre-incubated at 38.5°C or 41.0°C for 4 hr. In each experiment, zygotes were cultured at 38.5°C in 5% CO(2) and 5% O(2). Rates of cleavage and blasocyst formation were reduced when fertilization occurs at elevated temperatures. The percent of sperm classified as alive, using fluorescein diacetate labeling, was decreased by pre-incubation and fertilization at 40.0°C. Although no difference was observed in sperm penetration rate, polyspermy tended to be increased by heat stress during fertilization. The zona pellucidae of zygotes formed following fertilization at 40.0°C for 6 hr were more sensitive to digestion with pronase. Furthermore, these zygotes exhibited higher hydrogen peroxide levels, measured by 2,7-dihydrodichlorofluorescein diacetate staining, and showed increased transcript abundance for HSPA1A, a gene involved in the heat-shock response, but decreased transcript abundance for UCHL1, a gene involved in preventing polyspermy. Results indicate that heat stress during fertilization is lethal to sperm, and causes oxidative stress, altered transcript abundance, and a defective block to polyspermy in the zygote. Thus, an increase in polyspermy is likely one cause of the reduced competency of zygotes fertilized under elevated temperatures to develop to the blastocyst stage.
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http://dx.doi.org/10.1002/mrd.22441DOI Listing
January 2015

Phosphorylation of threonine 3 on histone H3 by haspin kinase is required for meiosis I in mouse oocytes.

J Cell Sci 2014 Dec 14;127(Pt 23):5066-78. Epub 2014 Oct 14.

Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA

Meiosis I (MI), the division that generates haploids, is prone to errors that lead to aneuploidy in females. Haspin is a kinase that phosphorylates histone H3 on threonine 3, thereby recruiting Aurora kinase B (AURKB) and the chromosomal passenger complex (CPC) to kinetochores to regulate mitosis. Haspin and AURKC, an AURKB homolog, are enriched in germ cells, yet their significance in regulating MI is not fully understood. Using inhibitors and overexpression approaches, we show a role for haspin during MI in mouse oocytes. Haspin-perturbed oocytes display abnormalities in chromosome morphology and alignment, improper kinetochore-microtubule attachments at metaphase I and aneuploidy at metaphase II. Unlike in mitosis, kinetochore localization remained intact, whereas the distribution of the CPC along chromosomes was absent. The meiotic defects following haspin inhibition were similar to those observed in oocytes where AURKC was inhibited, suggesting that the correction of microtubule attachments during MI requires AURKC along chromosome arms rather than at kinetochores. Our data implicate haspin as a regulator of the CPC and chromosome segregation during MI, while highlighting important differences in how chromosome segregation is regulated between MI and mitosis.
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http://dx.doi.org/10.1242/jcs.158840DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4248095PMC
December 2014

Selective disruption of aurora C kinase reveals distinct functions from aurora B kinase during meiosis in mouse oocytes.

PLoS Genet 2014 Feb 27;10(2):e1004194. Epub 2014 Feb 27.

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

Aurora B kinase (AURKB) is the catalytic subunit of the chromosomal passenger complex (CPC), an essential regulator of chromosome segregation. In mitosis, the CPC is required to regulate kinetochore microtubule (K-MT) attachments, the spindle assembly checkpoint, and cytokinesis. Germ cells express an AURKB homolog, AURKC, which can also function in the CPC. Separation of AURKB and AURKC function during meiosis in oocytes by conventional approaches has not been successful. Therefore, the meiotic function of AURKC is still not fully understood. Here, we describe an ATP-binding-pocket-AURKC mutant, that when expressed in mouse oocytes specifically perturbs AURKC-CPC and not AURKB-CPC function. Using this mutant we show for the first time that AURKC has functions that do not overlap with AURKB. These functions include regulating localized CPC activity and regulating chromosome alignment and K-MT attachments at metaphase of meiosis I (Met I). We find that AURKC-CPC is not the sole CPC complex that regulates the spindle assembly checkpoint in meiosis, and as a result most AURKC-perturbed oocytes arrest at Met I. A small subset of oocytes do proceed through cytokinesis normally, suggesting that AURKC-CPC is not the sole CPC complex during telophase I. But, the resulting eggs are aneuploid, indicating that AURKC is a critical regulator of meiotic chromosome segregation in female gametes. Taken together, these data suggest that mammalian oocytes contain AURKC to efficiently execute meiosis I and ensure high-quality eggs necessary for sexual reproduction.
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http://dx.doi.org/10.1371/journal.pgen.1004194DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3937256PMC
February 2014

Knockdown of RBBP7 unveils a requirement of histone deacetylation for CPC function in mouse oocytes.

Cell Cycle 2014 6;13(4):600-11. Epub 2013 Dec 6.

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

During mouse oocyte maturation histones are deacetylated, and inhibiting this deacetylation leads to abnormal chromosome segregation and aneuploidy. RBBP7 is a component of several different complexes that contain histone deacetylases, and therefore could be implicated in histone deacetylation. We find that Rbbp7 is a dormant maternal mRNA that is recruited for translation during oocyte maturation to regulate the histone deacetylation. Importantly, we show that the maturation-associated decrease of histone acetylation is required for localization and function of the chromosomal passenger complex (CPC) during oocyte meiotic maturation. This finding can explain the phenotypes of oocytes where Rbbp7 is depleted by an siRNA/morpholino cocktail including severe chromosome misalignment, improper kinetochore-microtubule attachments, impaired SAC function, cytokinesis defects, and increased incidence of aneuploidy at metaphase II (Met II). These results implicate RBBP7 as a novel regulator of histone deacetylation during oocyte maturation and provide evidence that such deacetylation is required for proper chromosome segregation by regulating localized CPC function.
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http://dx.doi.org/10.4161/cc.27410DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5896761PMC
April 2015

Effect of summer heat environment on body temperature, estrous cycles and blood antioxidant levels in Japanese Black cow.

Anim Sci J 2012 May 8;83(5):394-402. Epub 2011 Dec 8.

Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, Koshi, Kumamoto, Japan.

This study investigated the effect of summer heat environment on estrous cycles and blood antioxidant levels in Japanese Black cows. A total of 13 non-lactating Japanese Black cows (summer: 9, winter: 4) were examined. Body temperature was measured rectally and intravaginally using a thermometer and data logger, respectively. Estrous behavior was monitored using a radiotelemetric pedometer that recorded walking activity. Rectal temperatures were higher during summer than winter (P<0.001). There was an acute increase in vaginal temperature at the onset of estrus during winter but such an increase was not observed during summer. Walking activity during estrus decreased dramatically in the summer compared to the winter. Duration of estrous cycle was longer in summer (23.4 days, P<0.05) than winter (21.5 days), and the subsequent rise in progesterone concentrations following estrus tended to be delayed in summer. The level of thiobarbituric acid reactive substances (TBARS) in peripheral blood cells was higher during summer (P<0.05), while the levels of superoixde dismutase (SOD), glutathione peroxidase (GPx) and glutathione were lower (P<0.05). These results indicate that high ambient temperature during summer increases both body temperature and oxidative stress, and also reduces signs of estrus in Japanese Black cows.
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http://dx.doi.org/10.1111/j.1740-0929.2011.00967.xDOI Listing
May 2012
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