Publications by authors named "Catherine A Wilson"

19 Publications

  • Page 1 of 1

Leaky barriers: leaky enough for fish to pass?

R Soc Open Sci 2021 Mar 3;8(3):201843. Epub 2021 Mar 3.

School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK.

Perceived as environmental-friendly hydraulic structures, leaky barriers used for natural flood management are introduced into rivers, potentially creating migration barriers for fish. Using sustainable, local materials to construct wooden barriers across river channels in upper catchments, these barriers aim to slow down the flow, reduce flood peaks and attenuate the flow reaching downstream communities. Yet little is known about their impact on hydrodynamics and fish passage. Here, we examined two model barrier designs under 100% and 80% bankfull flow conditions in an open channel flume. These barriers included a porous and a non-porous design, with the latter emulating the natural accumulation of brush, sediment and leaf material between logs over time. Flow visualization and velocity measurements recorded with acoustic Doppler velocimetry characterized the flow field upstream and downstream of the barriers. Our fish behavioural studies revealed that juvenile salmon () movement between downstream and upstream sections of the flume was inhibited by barrier design rather than discharge, influencing upstream fish passage and their spatial preference, indicating the importance of barrier design criteria to facilitate fish movement.
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http://dx.doi.org/10.1098/rsos.201843DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8074940PMC
March 2021

RADSex: A computational workflow to study sex determination using restriction site-associated DNA sequencing data.

Mol Ecol Resour 2021 Jul 9;21(5):1715-1731. Epub 2021 Mar 9.

Physiological Chemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany.

The study of sex determination and sex chromosome organization in nonmodel species has long been technically challenging, but new sequencing methodologies now enable precise and high-throughput identification of sex-specific genomic sequences. In particular, restriction site-associated DNA sequencing (RAD-Seq) is being extensively applied to explore sex determination systems in many plant and animal species. However, software specifically designed to search for and visualize sex-biased markers using RAD-Seq data is lacking. Here, we present RADSex, a computational analysis workflow designed to study the genetic basis of sex determination using RAD-Seq data. RADSex is simple to use, requires few computational resources, makes no prior assumptions about the type of sex-determination system or structure of the sex locus, and offers convenient visualization through a dedicated R package. To demonstrate the functionality of RADSex, we re-analysed a published data set of Japanese medaka, Oryzias latipes, where we uncovered a previously unknown Y chromosome polymorphism. We then used RADSex to analyse new RAD-Seq data sets from 15 fish species spanning multiple taxonomic orders. We identified the sex determination system and sex-specific markers in six of these species, five of which had no known sex-markers prior to this study. We show that RADSex greatly facilitates the study of sex determination systems in nonmodel species thanks to its speed of analyses, low resource usage, ease of application and visualization options. Furthermore, our analysis of new data sets from 15 species provides new insights on sex determination in fish.
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http://dx.doi.org/10.1111/1755-0998.13360DOI Listing
July 2021

A Search for Sex-Linked Loci in the Agamid Lizard, Calotes versicolor.

Sex Dev 2019 28;13(3):143-150. Epub 2019 Jun 28.

The Indian garden lizard, Calotes versicolor, lacks cytologically recognizable sex chromosomes, and its mechanism of sex determination is unclear. We evaluated genotype-to-sex-phenotype association using RAD-seq in wild-caught males and females, 30 of each sex. Of 210,736 unique, 96-nt long RAD-tags, 48% contained polymorphisms, 23% of which were present in at least 40 of 60 individuals. Twenty one RAD-tags neared, but none achieved, the inclusion criteria for sex enrichment, as expected if C. versicolor lacks highly differentiated sex chromosomes. Three RAD-tags with alleles most strongly associated with sex tended to be heterozygous in females and to lack male-specific alleles, suggesting a ZW female/ZZ male system. Putative female alleles, however, were present in some males and lacking from some females, suggesting either recombination between these markers and the sex locus or sex reversal due to environmental or genetic factors. Paired-end, 250-nt reads from 1 male provided a fragmented draft genome assembly. Four sex-associated RAD-tags were identical to portions of 4 unique C. versicolor genomic contigs rather than linked to a single putative sex-linked region. The lack of strongly sex-linked loci coupled with weak evidence for temperature-associated sex determination intensifies the need for further investigation of the puzzling sex determination mechanism in C. versicolor.
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http://dx.doi.org/10.1159/000500465DOI Listing
April 2020

Antarctic blackfin icefish genome reveals adaptations to extreme environments.

Nat Ecol Evol 2019 03 25;3(3):469-478. Epub 2019 Feb 25.

Unit of Polar Genomics, Korea Polar Research Institute, Incheon, Korea.

Icefishes (suborder Notothenioidei; family Channichthyidae) are the only vertebrates that lack functional haemoglobin genes and red blood cells. Here, we report a high-quality genome assembly and linkage map for the Antarctic blackfin icefish Chaenocephalus aceratus, highlighting evolved genomic features for its unique physiology. Phylogenomic analysis revealed that Antarctic fish of the teleost suborder Notothenioidei, including icefishes, diverged from the stickleback lineage about 77 million years ago and subsequently evolved cold-adapted phenotypes as the Southern Ocean cooled to sub-zero temperatures. Our results show that genes involved in protection from ice damage, including genes encoding antifreeze glycoprotein and zona pellucida proteins, are highly expanded in the icefish genome. Furthermore, genes that encode enzymes that help to control cellular redox state, including members of the sod3 and nqo1 gene families, are expanded, probably as evolutionary adaptations to the relatively high concentration of oxygen dissolved in cold Antarctic waters. In contrast, some crucial regulators of circadian homeostasis (cry and per genes) are absent from the icefish genome, suggesting compromised control of biological rhythms in the polar light environment. The availability of the icefish genome sequence will accelerate our understanding of adaptation to extreme Antarctic environments.
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http://dx.doi.org/10.1038/s41559-019-0812-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7307600PMC
March 2019

Cold Fusion: Massive Karyotype Evolution in the Antarctic Bullhead Notothen .

G3 (Bethesda) 2017 07 5;7(7):2195-2207. Epub 2017 Jul 5.

Institute of Neuroscience, University of Oregon, Eugene, Oregon 97403

Half of all vertebrate species share a series of chromosome fusions that preceded the teleost genome duplication (TGD), but we do not understand the causative evolutionary mechanisms. The "Robertsonian-translocation hypothesis" suggests a regular fusion of each ancestral acro- or telocentric chromosome to just one other by centromere fusions, thus halving the karyotype. An alternative "genome-stirring hypothesis" posits haphazard and repeated fusions, inversions, and reciprocal and nonreciprocal translocations. To study large-scale karyotype reduction, we investigated the decrease of chromosome numbers in Antarctic notothenioid fish. Most notothenioids have 24 haploid chromosomes, but bullhead notothen () has 11. To understand mechanisms, we made a RAD-tag meiotic map with ∼10,000 polymorphic markers. Comparative genomics aligned about a thousand orthologs of platyfish and stickleback genes along bullhead chromosomes. Results revealed that 9 of 11 bullhead chromosomes arose by fusion of just two ancestral chromosomes and two others by fusion of three ancestral chromosomes. All markers from each ancestral chromosome remained contiguous, implying no inversions across fusion borders. Karyotype comparisons support a history of: (1) Robertsonian fusions of 22 ancestral chromosomes in pairs to yield 11 fused plus two small unfused chromosomes, like ; (2) fusion of one of the remaining two ancestral chromosomes to a preexisting fused pair, giving 12 chromosomes like ; and (3) fusion of the remaining ancestral chromosome to another fused pair, giving 11 chromosomes in These results raise the question of what selective forces promoted the systematic fusion of chromosomes in pairs and the suppression of pericentric inversions in this lineage, and provide a model for chromosome fusions in stem teleosts.
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http://dx.doi.org/10.1534/g3.117.040063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5498148PMC
July 2017

Variations on a theme: Genomics of sex determination in the cichlid fish Astatotilapia burtoni.

BMC Genomics 2016 11 7;17(1):883. Epub 2016 Nov 7.

Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland.

Background: Sex chromosomes change more frequently in fish than in mammals or birds. However, certain chromosomes or genes are repeatedly used as sex determinants in different members of the teleostean lineage. East African cichlids are an enigmatic model system in evolutionary biology representing some of the most diverse extant vertebrate adaptive radiations. How sex is determined and if different sex-determining mechanisms contribute to speciation is unknown for almost all of the over 1,500 cichlid species of the Great Lakes. Here, we investigated the genetic basis of sex determination in a cichlid from Lake Tanganyika, Astatotilapia burtoni, a member of the most species-rich cichlid lineage, the haplochromines.

Results: We used RAD-sequencing of crosses for two populations of A. burtoni, a lab strain and fish caught at the south of Lake Tanganyika. Using association mapping and comparative genomics, we confirmed male heterogamety in A. burtoni and identified different sex chromosomes (LG5 and LG18) in the two populations of the same species. LG5, the sex chromosome of the lab strain, is a fusion chromosome in A. burtoni. Wnt4 is located on this chromosome, representing the best candidate identified so far for the master sex-determining gene in our lab strain of A. burtoni.

Conclusions: Cichlids exemplify the high turnover rate of sex chromosomes in fish with two different chromosomes, LG5 and LG18, containing major sex-determining loci in the two populations of A. burtoni examined here. However, they also illustrate that particular chromosomes are more likely to be used as sex chromosomes. Chromosome 5 is such a chromosome, which has evolved several times as a sex chromosome, both in haplochromine cichlids from all Great Lakes and also in other teleost fishes.
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http://dx.doi.org/10.1186/s12864-016-3178-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5100337PMC
November 2016

A Genetic Map for the Only Self-Fertilizing Vertebrate.

G3 (Bethesda) 2016 04 7;6(4):1095-106. Epub 2016 Apr 7.

Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, 852-8521, Japan

The mangrove killifish Kryptolebias marmoratus, and its close relative Kryptolebias hermaphroditus, are the only vertebrate species known to reproduce by self-fertilization due to functional ovotestis development. To improve our understanding of their genomes, we constructed a genetic map. First, a single F1 fish was made by artificial fertilization between K. marmoratus and K. hermaphroditus strains. F2 progeny were then obtained by self-fertilization of the F1 fish. We used RAD-seq to query genomic DNAs from the two parental strains, the F1 individual and 49 F2 progeny. Results identified 9904 polymorphic RAD-tags (DNA markers) that mapped to 24 linkage groups, corresponding to the haploid chromosome number of these species. The total length of the map was 1248 cM, indicating that about one recombination occurred for each of the 24 homologous chromosome pairs in each meiosis. Markers were not evenly distributed along the chromosomes: in all chromosomes, many markers (> 8% of the total markers for each chromosome) mapped to chromosome tips. Centromeres suppress recombination, and this uneven distribution is probably due to the species' acrocentric chromosomes. Mapped marker sequences were compared to genomic sequences of medaka and platyfish, the next most closely related species with sequenced genomes that are anchored to genetic maps. Results showed that each mangrove killifish chromosome corresponds to a single chromosome of both platyfish and medaka, suggesting strong conservation of chromosomes over 100 million years of evolution. Our genetic map provides a framework for the K. marmoratus/K. hermaphroditus genome sequence and an important resource for understanding the biology of hermaphroditism.
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http://dx.doi.org/10.1534/g3.115.022699DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4825644PMC
April 2016

BRG1 Governs Nanog Transcription in Early Mouse Embryos and Embryonic Stem Cells via Antagonism of Histone H3 Lysine 9/14 Acetylation.

Mol Cell Biol 2015 Dec 28;35(24):4158-69. Epub 2015 Sep 28.

Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University, East Lansing, Michigan, USA Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA

During mouse preimplantation development, the generation of the inner cell mass (ICM) and trophoblast lineages comprises upregulation of Nanog expression in the ICM and its silencing in the trophoblast. However, the underlying epigenetic mechanisms that differentially regulate Nanog in the first cell lineages are poorly understood. Here, we report that BRG1 (Brahma-related gene 1) cooperates with histone deacetylase 1 (HDAC1) to regulate Nanog expression. BRG1 depletion in preimplantation embryos and Cdx2-inducible embryonic stem cells (ESCs) revealed that BRG1 is necessary for Nanog silencing in the trophoblast lineage. Conversely, in undifferentiated ESCs, loss of BRG1 augmented Nanog expression. Analysis of histone H3 within the Nanog proximal enhancer revealed that H3 lysine 9/14 (H3K9/14) acetylation increased in BRG1-depleted embryos and ESCs. Biochemical studies demonstrated that HDAC1 was present in BRG1-BAF155 complexes and BRG1-HDAC1 interactions were enriched in the trophoblast lineage. HDAC1 inhibition triggered an increase in H3K9/14 acetylation and a corresponding rise in Nanog mRNA and protein, phenocopying BRG1 knockdown embryos and ESCs. Lastly, nucleosome-mapping experiments revealed that BRG1 is indispensable for nucleosome remodeling at the Nanog enhancer during trophoblast development. In summary, our data suggest that BRG1 governs Nanog expression via a dual mechanism involving histone deacetylation and nucleosome remodeling.
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http://dx.doi.org/10.1128/MCB.00546-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4648823PMC
December 2015

The Evolutionarily Conserved C-terminal Domains in the Mammalian Retinoblastoma Tumor Suppressor Family Serve as Dual Regulators of Protein Stability and Transcriptional Potency.

J Biol Chem 2015 Jun 22;290(23):14462-75. Epub 2015 Apr 22.

From the Department of Biochemistry and Molecular Biology,

The retinoblastoma (RB) tumor suppressor and related family of proteins play critical roles in development through their regulation of genes involved in cell fate. Multiple regulatory pathways impact RB function, including the ubiquitin-proteasome system with deregulated RB destruction frequently associated with pathogenesis. With the current study we explored the mechanisms connecting proteasome-mediated turnover of the RB family to the regulation of repressor activity. We find that steady state levels of all RB family members, RB, p107, and p130, were diminished during embryonic stem cell differentiation concomitant with their target gene acquisition. Proteasome-dependent turnover of the RB family is mediated by distinct and autonomously acting instability elements (IE) located in their C-terminal regulatory domains in a process that is sensitive to cyclin-dependent kinase (CDK4) perturbation. The IE regions include motifs that contribute to E2F-DP transcription factor interaction, and consistently, p107 and p130 repressor potency was reduced by IE deletion. The juxtaposition of degron sequences and E2F interaction motifs appears to be a conserved feature across the RB family, suggesting the potential for repressor ubiquitination and specific target gene regulation. These findings establish a mechanistic link between regulation of RB family repressor potency and the ubiquitin-proteasome system.
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http://dx.doi.org/10.1074/jbc.M114.599993DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4505513PMC
June 2015

Transcription factor AP-2γ induces early Cdx2 expression and represses HIPPO signaling to specify the trophectoderm lineage.

Development 2015 May 9;142(9):1606-15. Epub 2015 Apr 9.

Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA

Cell fate decisions are fundamental to the development of multicellular organisms. In mammals the first cell fate decision involves segregation of the pluripotent inner cell mass and the trophectoderm, a process regulated by cell polarity proteins, HIPPO signaling and lineage-specific transcription factors such as CDX2. However, the regulatory mechanisms that operate upstream to specify the trophectoderm lineage have not been established. Here we report that transcription factor AP-2γ (TFAP2C) functions as a novel upstream regulator of Cdx2 expression and position-dependent HIPPO signaling in mice. Loss- and gain-of-function studies and promoter analysis revealed that TFAP2C binding to an intronic enhancer is required for activation of Cdx2 expression during early development. During the 8-cell to morula transition TFAP2C potentiates cell polarity to suppress HIPPO signaling in the outside blastomeres. TFAP2C depletion triggered downregulation of PARD6B, loss of apical cell polarity, disorganization of F-actin, and activation of HIPPO signaling in the outside blastomeres. Rescue experiments using Pard6b mRNA restored cell polarity but only partially corrected position-dependent HIPPO signaling, suggesting that TFAP2C negatively regulates HIPPO signaling via multiple pathways. Several genes involved in regulation of the actin cytoskeleton (including Rock1, Rock2) were downregulated in TFAP2C-depleted embryos. Inhibition of ROCK1 and ROCK2 activity during the 8-cell to morula transition phenocopied TFAP2C knockdown, triggering a loss of position-dependent HIPPO signaling and decrease in Cdx2 expression. Altogether, these results demonstrate that TFAP2C facilitates trophectoderm lineage specification by functioning as a key regulator of Cdx2 transcription, cell polarity and position-dependent HIPPO signaling.
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http://dx.doi.org/10.1242/dev.120238DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419278PMC
May 2015

Wild sex in zebrafish: loss of the natural sex determinant in domesticated strains.

Genetics 2014 Nov 18;198(3):1291-308. Epub 2014 Sep 18.

Institute of Neuroscience, University of Oregon, Eugene Oregon 97403

Sex determination can be robustly genetic, strongly environmental, or genetic subject to environmental perturbation. The genetic basis of sex determination is unknown for zebrafish (Danio rerio), a model for development and human health. We used RAD-tag population genomics to identify sex-linked polymorphisms. After verifying this "RAD-sex" method on medaka (Oryzias latipes), we studied two domesticated zebrafish strains (AB and TU), two natural laboratory strains (WIK and EKW), and two recent isolates from nature (NA and CB). All four natural strains had a single sex-linked region at the right tip of chromosome 4, enabling sex genotyping by PCR. Genotypes for the single nucleotide polymorphism (SNP) with the strongest statistical association to sex suggested that wild zebrafish have WZ/ZZ sex chromosomes. In natural strains, "male genotypes" became males and some "female genotypes" also became males, suggesting that the environment or genetic background can cause female-to-male sex reversal. Surprisingly, TU and AB lacked detectable sex-linked loci. Phylogenomics rooted on D. nigrofasciatus verified that all strains are monophyletic. Because AB and TU branched as a monophyletic clade, we could not rule out shared loss of the wild sex locus in a common ancestor despite their independent domestication. Mitochondrial DNA sequences showed that investigated strains represent only one of the three identified zebrafish haplogroups. Results suggest that zebrafish in nature possess a WZ/ZZ sex-determination mechanism with a major determinant lying near the right telomere of chromosome 4 that was modified during domestication. Strains providing the zebrafish reference genome lack key components of the natural sex-determination system but may have evolved variant sex-determining mechanisms during two decades in laboratory culture.
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http://dx.doi.org/10.1534/genetics.114.169284DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4224167PMC
November 2014

Transcriptional reprogramming and chromatin remodeling accompanies Oct4 and Nanog silencing in mouse trophoblast lineage.

Stem Cells Dev 2014 Feb 7;23(3):219-29. Epub 2013 Nov 7.

1 Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University , East Lansing, Michigan.

In mouse blastocysts, CDX2 plays a key role in silencing Oct4 and Nanog expression in the trophectoderm (TE) lineage. However, the underlying transcriptional and chromatin-based changes that are associated with CDX2-mediated repression are poorly understood. To address this, a Cdx2-inducible mouse embryonic stem (ES) cell line was utilized as a model system. Induction of Cdx2 expression resulted in a decrease in Oct4/Nanog expression, an increase in TE markers, and differentiation into trophoblast-like stem (TS-like) cells within 48 to 120 h. Consistent with the down-regulation of Oct4 and Nanog transcripts, a time-dependent increase in CDX2 binding and a decrease in RNA polymerase II (RNAPII) and OCT4 binding was observed within 48 h (P<0.05). To test whether transcriptionally active epigenetic marks were erased during differentiation, histone H3K9/14 acetylation and two of its epigenetic modifiers were evaluated. Accordingly, a significant decrease in histone H3K9/14 acetylation and loss of p300 and HDAC1 binding at the Oct4 and Nanog regulatory elements was observed by 48 h. Accompanying these changes, there was a significant increase in total histone H3 and a loss of chromatin accessibility at both the Oct4 and Nanog regulatory elements (P<0.05), indicative of chromatin remodeling. Lastly, DNA methylation analysis revealed that methylation did not occur at Oct4 and Nanog until 96 to 120 h after induction of CDX2. In conclusion, our results show that silencing of Oct4 and Nanog is facilitated by sequential changes in transcription factor binding, histone acetylation, chromatin remodeling, and DNA methylation at core regulatory elements.
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http://dx.doi.org/10.1089/scd.2013.0328DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3904517PMC
February 2014

Evidence that transcription factor AP-2γ is not required for Oct4 repression in mouse blastocysts.

PLoS One 2013 31;8(5):e65771. Epub 2013 May 31.

Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University, East Lansing, Michigan, United States of America.

In mouse blastocysts segregation of the inner cell mass (ICM) and the trophectoderm (TE) is regulated by the mutually antagonistic effects of the transcription factors Oct4 and Cdx2 expressed in the ICM and TE, respectively. In contrast, in other species such as bovine and human, Oct4 is not restricted to the ICM and continues to be expressed in the Cdx2-positive TE. A recent comparative study of the bovine and mouse Oct4 promoters revealed that additional mechanisms might act in conjunction with Cdx2 to downregulate Oct4 expression in the mouse TE lineage. For instance, the mouse Oct4 distal enhancer contains an AP-2γ (Tcfap2c) binding motif that is absent in the bovine and human Oct4 distal enhancer. Nonetheless, the functional relevance of Tcfap2c in Oct4 repression during mouse preimplantation development was not tested. To elucidate the role of Tcfap2c in Oct4 expression an RNA interference approach was utilized. Depletion of Tcfap2c triggered a decrease in Oct4 expression at the 8-cell and morula stage. Remarkably, at the blastocyst stage depletion of Tcfap2c and/or its family member Tcfap2a had no effect on Oct4 repression. To test whether Tcfap2c interacts with Oct4 to positively regulate Oct4 expression, chromatin immunoprecipitation and in situ co-immunoprecipitation analyses were performed. These experiments revealed Tcfap2c and Oct4 binding were enriched at the Oct4 distal enhancer in embryonic stem (ES) cells, but were rapidly lost during differentiation into trophoblast-like cells when Oct4 became repressed. Moreover, Tcfap2c and Oct4 interactions were detected at the morula stage, but were lost during blastocyst formation. In summary, these data demonstrate that Tcfap2c is not required for Oct4 silencing in mouse blastocysts, but may be necessary for the maintenance of Oct4 expression during the 8 cell-to-morula transition. These findings support the notion Cdx2 is the predominant negative regulator of Oct4 expression during blastocyst formation in mice.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0065771PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3669238PMC
January 2014

Transcription factor AP-2γ is a core regulator of tight junction biogenesis and cavity formation during mouse early embryogenesis.

Development 2012 Dec;139(24):4623-32

Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University, East Lansing, MI, USA.

The trophectoderm epithelium is the first differentiated cell layer to arise during mammalian development. Blastocyst formation requires the proper expression and localization of tight junction, polarity, ion gradient and H2O channel proteins in the outer cell membranes. However, the underlying transcriptional mechanisms that control their expression are largely unknown. Here, we report that transcription factor AP-2γ (Tcfap2c) is a core regulator of blastocyst formation in mice. Bioinformatics, chromatin immunoprecipitation and transcriptional analysis revealed that Tcfap2c binds and regulates a diverse group of genes expressed during blastocyst formation. RNA interference experiments demonstrated that Tcfap2c regulates genes important for tight junctions, cell polarity and fluid accumulation. Functional and ultrastructural studies revealed that Tcfap2c is necessary for tight junction assembly and paracellular sealing in trophectoderm epithelium. Aggregation of control eight-cell embryos with Tcfap2c knockdown embryos rescued blastocyst formation via direct contribution to the trophectoderm epithelium. Finally, we found that Tcfap2c promotes cellular proliferation via direct repression of p21 transcription during the morula-to-blastocyst transition. We propose a model in which Tcfap2c acts in a hierarchy to facilitate blastocyst formation through transcriptional regulation of core genes involved in tight junction assembly, fluid accumulation and cellular proliferation.
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http://dx.doi.org/10.1242/dev.086645DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3518458PMC
December 2012

Brg1 is required for Cdx2-mediated repression of Oct4 expression in mouse blastocysts.

PLoS One 2010 May 12;5(5):e10622. Epub 2010 May 12.

Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University, East Lansing, Michigan, United States of America.

During blastocyst formation the segregation of the inner cell mass (ICM) and trophectoderm is governed by the mutually antagonistic effects of the transcription factors Oct4 and Cdx2. Evidence indicates that suppression of Oct4 expression in the trophectoderm is mediated by Cdx2. Nonetheless, the underlying epigenetic modifiers required for Cdx2-dependent repression of Oct4 are largely unknown. Here we show that the chromatin remodeling protein Brg1 is required for Cdx2-mediated repression of Oct4 expression in mouse blastocysts. By employing a combination of RNA interference (RNAi) and gene expression analysis we found that both Brg1 Knockdown (KD) and Cdx2 KD blastocysts exhibit widespread expression of Oct4 in the trophectoderm. Interestingly, in Brg1 KD blastocysts and Cdx2 KD blastocysts, the expression of Cdx2 and Brg1 is unchanged, respectively. To address whether Brg1 cooperates with Cdx2 to repress Oct4 transcription in the developing trophectoderm, we utilized preimplantation embryos, trophoblast stem (TS) cells and Cdx2-inducible embryonic stem (ES) cells as model systems. We found that: (1) combined knockdown (KD) of Brg1 and Cdx2 levels in blastocysts resulted in increased levels of Oct4 transcripts compared to KD of Brg1 or Cdx2 alone, (2) endogenous Brg1 co-immunoprecipitated with Cdx2 in TS cell extracts, (3) in blastocysts Brg1 and Cdx2 co-localize in trophectoderm nuclei and (4) in Cdx2-induced ES cells Brg1 and Cdx2 are recruited to the Oct4 promoter. Lastly, to determine how Brg1 may induce epigenetic silencing of the Oct4 gene, we evaluated CpG methylation at the Oct4 promoter in the trophectoderm of Brg1 KD blastocysts. This analysis revealed that Brg1-dependent repression of Oct4 expression is independent of DNA methylation at the blastocyst stage. In toto, these results demonstrate that Brg1 cooperates with Cdx2 to repress Oct4 expression in the developing trophectoderm to ensure normal development.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0010622PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2868905PMC
May 2010

Ghrelin and peptide YY (PYY) profiles in gastrointestinal tissues and the circulation of the rat during pregnancy and lactation.

Peptides 2009 Dec 22;30(12):2213-20. Epub 2009 Sep 22.

Department of Metabolic Medicine, Faculty of Medicine, Imperial College London, Hammersmith Hospital, 6th Floor, Commonwealth Building, Du Cane Road, London W12 0NN, UK.

Plasma and tissue profiles of gastrointestinal hormones ghrelin and peptide YY (PYY) were investigated in different female rat reproductive states. Neither plasma nor tissue ghrelin concentrations were suppressed during pregnancy despite elevated leptin. The highest concentrations of stomach ghrelin were measured in late pregnancy. PYY concentrations in plasma, descending colon and rectum tissues were increased (P<0.001) throughout pregnancy and lactation. PYY peaked at day 5 of lactation in plasma, as well as descending colon and rectum tissues (proestrus vs day 5 of lactation: 25+/-3.0 pmol/l vs 55+/-8.0 pmol/l; 85+/-4.5 pmol/g wwt vs 418+/-45.0 pmol/g wwt; 23+/-3.0 pmol/g wwt vs 78+/-9.1 pmol/g wwt). This PYY peak was temporally associated with the luteinizing hormone peak on day 1 of lactation. Following weaning, dam adiposity and plasma leptin increased whereas ghrelin stomach peptide decreased. Relative PYY concentrations in the tissues of the gut varied in the different states suggesting regional alterations taking place in the colon. The ascending colon produced the highest concentrations in non-pregnant rats, the descending colon the highest concentrations during lactation with the pregnant rats and the dams postweaning in a transition state between. It is unclear what role the increased PYY in various tissues observed has during pregnancy and lactation as it would be expected to be reduced in these states of greatly increased appetite. PYY may have an influence on maternal dietary adaptation, intestinal hypertrophy and weight gain during pregnancy and lactation although it is still unclear precisely how it acts.
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http://dx.doi.org/10.1016/j.peptides.2009.09.022DOI Listing
December 2009

The 5HT(7) receptor subtype is involved in the regulation of female sexual behaviour in the rat.

Pharmacol Biochem Behav 2007 Aug-Sep;87(3):386-92. Epub 2007 May 24.

Department of Biological and Biomedical Sciences, Aga Khan University, Karachi 74800, Pakistan.

5-Hydroxytryptamine (5-HT) regulates sexual behaviour in the female rat via a number of its receptors. The role of the 5HT(7) receptor was investigated in ovariectomised rats primed with 10 mug oestradiol benzoate (OB) followed at 48 h by 0.5 mg progesterone, which induced receptivity in approximately half of the animals. These animals were treated with three agonists all effective at 5HT(1A) and 5HT(7) receptors; 5-hydroxytryptophan, 8-hydroxy-2-(di-n-propylamino)tetralin 1-Br (8-OH DPAT) and 5-carboxy-aminotryptamine (5-CT) in the presence or absence of selective 5HT(1A) and 5HT(7) antagonists: WAY 100135 and SB 269970-A. The three agonists inhibited lordosis in the receptive group, and this was prevented by both the selective 5HT(1A) and 5HT(7) antagonists. When given alone, both WAY 100135 and SB 269970-A increased the lordosis in the non-receptive rats indicating that endogenous 5-HT acting on 5HT(1A) and 5HT(7) receptors may have a tonic inhibitory effect on receptivity. A comparison of OB priming doses on the effect of serotoninergic agents showed that the higher OB doses attenuated the inhibitory effect of 8-OH DPAT and enhanced the stimulatory effect of WAY 100135, but did not affect the actions of 5-CT or SB 269970-A. The interaction between oestradiol and 5-HT activity on sexual behaviour may therefore be selective to the 5HT(1A) pathway.
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http://dx.doi.org/10.1016/j.pbb.2007.05.012DOI Listing
October 2007

Estrogen and progesterone regulate alpha, beta, and gammaENaC subunit mRNA levels in female rat kidney.

Kidney Int 2004 May;65(5):1774-81

Development, Growth and Function Division, Rowett Institute, Aberdeen, Scotland, United Kingdom.

Background: Estrogen and progesterone regulate alpha, beta, and gamma amiloride-sensitive epithelial sodium channel (ENaC) subunit mRNA levels in female rat kidney. Renal Na(+) handling differs between males and females. Further, within females Na(+) metabolism changes during the menstrual cycle and pregnancy. Electrolyte homeostasis and extracellular fluid volume are maintained primarily by regulated transport of Na(+) via the amiloride-sensitive Na(+) channel. This study examines the role of the female gender steroids in the regulation of expression of ENaC.

Methods: We measured ENaC subunit mRNA levels in rat kidney using Northern blotting. Kidneys were taken from male and females at different ages and from adult ovariectomized rats treated with 17-beta-estradiol benzoate (estrogen) and/or progesterone for 8 or 24 hours.

Results: The abundance of alpha, beta, and gammaENaC mRNA was significantly higher in female compared to male rat kidneys from 10 weeks of age (P= 0.001, P= 0.004, and P= 0.02, N= 10, respectively). These differences were abolished in ovariectomized rats. Treatment of ovariectomized rats with estrogen increased alphaENaC mRNA abundance in the kidney at both 8 and 24 hours (P < 0.05, N= 6; and P < 0.05, N= 7, respectively). Progesterone inhibited the effect of estrogen on alphaENaC mRNA at 8 hours but when given alone increased gammaENaC mRNA (P < 0.05, N= 3). Neither hormone, alone or in combination, had any significant effect on betaENaC mRNA levels at 8 or 24 hours.

Conclusion: Female gonadal steroids differentially modulate expression of ENaC subunit mRNA in the rat kidney.
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http://dx.doi.org/10.1111/j.1523-1755.2004.00593.xDOI Listing
May 2004

Effects of perinatal octylphenol on ultrasound vocalization, behavior and reproductive physiology in rats.

Physiol Behav 2002 Aug;76(4-5):645-53

Endocrinology and Reproduction Research Group, School of Biomedical Sciences, Guy's Campus, King's College, London SE1 1U, UK.

A rodent diet containing paraffin wax was designed to administer the environmental estrogen octylphenol (OP) to nonpregnant, pregnant and lactating rats. The estrogenic activity of OP via this diet was first confirmed in ovariectomized adult animals: 20 mg OP/kg/day increased the mitoses in the vaginal epithelium, and 60 mg OP/kg/day stimulated mitoses in the uterine luminal epithelium. The effects on a variety of reproductive and nonreproductive parameters were then investigated in the offspring of dams fed OP (100-250 mg/kg/day during gestation and lactation). A number of modest reproductive and morphological effects observed in the offspring including decreased body weights in adults of both sexes, disrupted vaginal cyclicity and decreases in seminiferous tubule diameter and testis, kidney, spleen and ovary weights. Behavioral effects included increased sexual arousal in males, increased sexual motivation in females towards a female teaser and increased motor activity by females. Ultrasonic vocalizations by pups at Postnatal Day (PND) 7 were reduced in number and duration in both sexes. There were no effects of perinatal OP on ano-genital distance, prepuce separation, aggressive behavior or adult ultrasound vocalization. These observations confirm that the dietary intake of estrogenic amounts of OP during pregnancy and lactation can have a wide variety of effects in the offspring.
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http://dx.doi.org/10.1016/s0031-9384(02)00788-6DOI Listing
August 2002