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Schiffer PH, Kroiher M, Kraus C, Koutsovoulos GD, Kumar S, R Camps JI, Nsah NA, Stappert D, Morris K, Heger P, Altmüller J, Frommolt P, Nürnberg P, Thomas WK, Blaxter ML, Schierenberg E. The genome of Romanomermis culicivorax: revealing fundamental changes in the core developmental genetic toolkit in Nematoda. BMC Genomics 2013; 14:923. [PMID: 24373391 PMCID: PMC3890508 DOI: 10.1186/1471-2164-14-923] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 12/17/2013] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The genetics of development in the nematode Caenorhabditis elegans has been described in exquisite detail. The phylum Nematoda has two classes: Chromadorea (which includes C. elegans) and the Enoplea. While the development of many chromadorean species resembles closely that of C. elegans, enoplean nematodes show markedly different patterns of early cell division and cell fate assignment. Embryogenesis of the enoplean Romanomermis culicivorax has been studied in detail, but the genetic circuitry underpinning development in this species has not been explored. RESULTS We generated a draft genome for R. culicivorax and compared its gene content with that of C. elegans, a second enoplean, the vertebrate parasite Trichinella spiralis, and a representative arthropod, Tribolium castaneum. This comparison revealed that R. culicivorax has retained components of the conserved ecdysozoan developmental gene toolkit lost in C. elegans. T. spiralis has independently lost even more of this toolkit than has C. elegans. However, the C. elegans toolkit is not simply depauperate, as many novel genes essential for embryogenesis in C. elegans are not found in, or have only extremely divergent homologues in R. culicivorax and T. spiralis. Our data imply fundamental differences in the genetic programmes not only for early cell specification but also others such as vulva formation and sex determination. CONCLUSIONS Despite the apparent morphological conservatism, major differences in the molecular logic of development have evolved within the phylum Nematoda. R. culicivorax serves as a tractable system to contrast C. elegans and understand how divergent genomic and thus regulatory backgrounds nevertheless generate a conserved phenotype. The R. culicivorax draft genome will promote use of this species as a research model.
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Affiliation(s)
| | - Michael Kroiher
- Zoologisches Institut, Universität zu Köln, Cologne, NRW, Germany
| | | | - Georgios D Koutsovoulos
- Institute of Evolutionary Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, Scotland, UK
| | - Sujai Kumar
- Institute of Evolutionary Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, Scotland, UK
| | - Julia I R Camps
- Zoologisches Institut, Universität zu Köln, Cologne, NRW, Germany
| | - Ndifon A Nsah
- Zoologisches Institut, Universität zu Köln, Cologne, NRW, Germany
| | - Dominik Stappert
- Institute für Entwicklungsbiologie, Universität zu Köln, Cologne, NRW, Germany
| | - Krystalynne Morris
- Hubbard Center for Genome Studies, University of New Hampshire, Durham, NH, USA
| | - Peter Heger
- Zoologisches Institut, Universität zu Köln, Cologne, NRW, Germany
| | - Janine Altmüller
- Cologne Center for Genomics, Universität zu Köln, Cologne, NRW, Germany
| | - Peter Frommolt
- Cologne Center for Genomics, Universität zu Köln, Cologne, NRW, Germany
| | - Peter Nürnberg
- Cologne Center for Genomics, Universität zu Köln, Cologne, NRW, Germany
| | - W Kelley Thomas
- Hubbard Center for Genome Studies, University of New Hampshire, Durham, NH, USA
| | - Mark L Blaxter
- Institute of Evolutionary Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, Scotland, UK
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Effects of In Vitro Maturation on Histone Acetylation in Metaphase II Oocytes and Early Cleavage Embryos. Obstet Gynecol Int 2010; 2010:989278. [PMID: 20613962 PMCID: PMC2896857 DOI: 10.1155/2010/989278] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 04/03/2010] [Accepted: 05/03/2010] [Indexed: 11/17/2022] Open
Abstract
In vitro maturation (IVM) of oocyte is an effective procedure for avoiding ovarian hyperstimulation syndrome in patients with polycystic ovaries (PCOS) during in vitro fertilization (IVF). To investigate the influences of IVM on epigenetic reprogramming and to search for the possible reasons for the lower rates of fertilization and cleavage in IVM oocytes, we examined the expression of two enzymes controlling histone acetylation, histone acetyltransferase GCN5 (GCN5) and histone deacetylase 1 (HDAC1), as well as their common target, acetyl-histone H3 (Ac-H3), in mouse metaphase II (MII) oocytes and preimplantation embryos. Results showed that IVM downregulated the protein expression of GCN5 in MII oocytes and two-cell embryos and changed the distribution of GCN5 in two-cell embryos. Expression of HDAC1 mRNA in MII oocytes and two-cell embryos decreased in the IVM group. However, none of these changes persisted after two-cell embryos. Levels of Ac-H3 in both oocytes and embryos remained unchanged after IVM. Our studies indicated that IVM could affect the protein and gene expression related to histone acetylation in oocytes and early cleavage embryos. By function of selection, parts of the changes could be recovered in late embryo development.
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Page BD, Diede SJ, Tenlen JR, Ferguson EL. EEL-1, a Hect E3 ubiquitin ligase, controls asymmetry and persistence of the SKN-1 transcription factor in the early C. elegans embryo. Development 2007; 134:2303-14. [PMID: 17537795 DOI: 10.1242/dev.02855] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During early divisions of the C. elegans embryo, many maternally supplied determinants accumulate asymmetrically, and this asymmetry is crucial for proper cell fate specification. SKN-1, a transcription factor whose message is maternally supplied to the embryo, specifies the mesendodermal cell fate. In the 2-cell embryo, SKN-1 is expressed at a higher level in the posterior cell. This asymmetry becomes more pronounced at the 4-cell stage, when SKN-1 is high in the posterior cell's daughters and low in the daughters of the anterior blastomere. To date, the direct mechanisms that control SKN-1 distribution remain unknown. In this report, we identify eel-1, which encodes a putative Hect E3 ubiquitin ligase that shares several domains of similarity to the mammalian E3 ligase Mule. EEL-1 binds SKN-1 and appears to target SKN-1 for degradation. EEL-1 has two functions in regulating SKN-1 during early embryogenesis. First, eel-1 promotes the spatial asymmetry of SKN-1 accumulation at the 2- and 4-cell stages. Second, eel-1 acts in all cells to downregulate SKN-1 from the 12- to the 28-cell stage. Although loss of eel-1 alone causes a reduction in SKN-1 asymmetry at the 2-cell stage, the function of eel-1 in both the spatial and temporal regulation of SKN-1 is redundant with the activities of other genes. These data strongly suggest that multiple, functionally redundant pathways cooperate to ensure precise control of SKN-1 asymmetry and persistence in the early embryo.
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Affiliation(s)
- Barbara D Page
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
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Nikolaou S, Gasser RB. Extending from PARs in Caenorhabditis elegans to homologues in Haemonchus contortus and other parasitic nematodes. Parasitology 2006; 134:461-82. [PMID: 17107637 DOI: 10.1017/s0031182006001727] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 08/23/2006] [Accepted: 10/02/2006] [Indexed: 11/05/2022]
Abstract
Signal transduction molecules play key roles in the regulation of developmental processes, such as morphogenesis, organogenesis and cell differentiation in all organisms. They are organized into 'pathways' that represent a coordinated network of cell-surface receptors and intracellular molecules, being involved in sensing environmental stimuli and transducing signals to regulate or modulate cellular processes, such as gene expression and cytoskeletal dynamics. A particularly important group of molecules implicated in the regulation of the cytoskeleton for the establishment and maintenance of cell polarity is the PAR proteins (derived from partition defective in asymmetric cell division). The present article reviews salient aspects of PAR proteins involved in the early embryonic development and morphogenesis of the free-living nematode Caenorhabditis elegans and some other organisms, with an emphasis on the molecule PAR-1. Recent advances in the knowledge and understanding of PAR-1 homologues from the economically important parasitic nematode, Haemonchus contortus, of small ruminants is summarized and discussed in the context of exploring avenues for future research in this area for parasitic nematodes.
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Affiliation(s)
- S Nikolaou
- Department of Veterinary Science, The University of Melbourne, 250 Princes Highway, Werribee, Victoria 3030, Australia
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Tenlen JR, Schisa JA, Diede SJ, Page BD. Reduced dosage of pos-1 suppresses Mex mutants and reveals complex interactions among CCCH zinc-finger proteins during Caenorhabditis elegans embryogenesis. Genetics 2006; 174:1933-45. [PMID: 17028349 PMCID: PMC1698638 DOI: 10.1534/genetics.105.052621] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cell fate specification in the early C. elegans embryo requires the activity of a family of proteins with CCCH zinc-finger motifs. Two members of the family, MEX-5 and MEX-6, are enriched in the anterior of the early embryo where they inhibit the accumulation of posterior proteins. Embryos from mex-5 single-mutant mothers are inviable due to the misexpression of SKN-1, a transcription factor that can specify mesoderm and endoderm. The aberrant expression of SKN-1 causes a loss of hypodermal and neuronal tissue and an excess of pharyngeal muscle, a Mex phenotype (muscle excess). POS-1, a third protein with CCCH motifs, is concentrated in the posterior of the embryo where it restricts the expression of at least one protein to the anterior. We discovered that reducing the dosage of pos-1(+) can suppress the Mex phenotype of mex-5(-) embryos and that POS-1 binds the 3'-UTR of mex-6. We propose that the suppression of the Mex phenotype by reducing pos-1(+) is due to decreased repression of mex-6 translation. Our detailed analyses of these protein functions reveal complex interactions among the CCCH finger proteins and suggest that their complementary expression patterns might be refined by antagonistic interactions among them.
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Affiliation(s)
- Jennifer R Tenlen
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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Tarazona AM, Rodríguez JI, Restrepo LF, Olivera-Angel M. Mitochondrial activity, distribution and segregation in bovine oocytes and in embryos produced in vitro. Reprod Domest Anim 2006; 41:5-11. [PMID: 16420320 DOI: 10.1111/j.1439-0531.2006.00615.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Contents Bovine oocytes and embryos produced in vitro were studied to determine the mitochondrial pattern of distribution, segregation and activity using DIOC 6 and Jc-1 fluorescence. The highest fluorescence level observed in mature oocytes was taken as 100% activity and six activity levels were estimated as follows: (1) 0%, (2) 1-15%, (3) 16-30%, (4) 31-50%, (5) 51-75% and (6) 76-100%. Three patterns of mitochondrial distribution were found: (1) diffused throughout the cytoplasm in oocytes and embryos, (2) pericytoplasmic in oocytes and embryos, and (3) perinuclear only in embryos. The segregation of mitochondria in blastomeres showed two distinct patterns: (1) symmetrical with an even mitochondrial population, and (2) asymmetrical with different numbers of mitochondria in each blastomere. In immature oocytes, mitochondrial activity was very low and the distribution was diffuse or negligible, while in mature oocytes the activity was high and the distribution was diffuse or pericytoplasmic. Competent embryos up to the 16-cell stage showed intermediate levels of activity (16-50%) but activity decreased thereafter up to the blastocyst stage. Non-competent embryos showed low levels of activity (1-15%) at all stages. These results suggest that mitochondria might play an important role during early development and that a minimum threshold of activity regulates the potential competence for reaching the blastocyst stage.
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Affiliation(s)
- A M Tarazona
- Reproduction-Physiology and Biotechnology, Group of Reproduction-Biogenesis, University of Antioquia, Medellin, Colombia
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Platzer U, Meinzer HP. Genetic Networks in the Early Development of Caenorhabditis elegans. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 234:47-100. [PMID: 15066373 DOI: 10.1016/s0074-7696(04)34002-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
One of the best-studied model organisms in biology is Caenorhabditis elegans. Because of its simple architecture and other biological advantages, considerable data have been collected about the regulation of its development. In this review, currently available data concerning the early phase of embryonic development are presented in the form of genetic networks. We performed computer simulations of regulatory mechanisms in embryonic development, and the results are described and compared with experimental observations.
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Affiliation(s)
- Ute Platzer
- Division Medical and Biological Informatics, Deutsches Krebsforschungszentrum D-69120 Heidelberg, Germany
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Lin R. A gain-of-function mutation in oma-1, a C. elegans gene required for oocyte maturation, results in delayed degradation of maternal proteins and embryonic lethality. Dev Biol 2003; 258:226-39. [PMID: 12781695 DOI: 10.1016/s0012-1606(03)00119-2] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In vertebrates, oocytes undergo maturation, arrest in metaphase II, and can then be fertilized by sperm. Fertilization initiates molecular events that lead to the activation of early embryonic development. In Caenorhabditis elegans, where no delay between oocyte maturation and fertilization is apparent, oocyte maturation and fertilization must be tightly coordinated. It is not clear what coordinates the transition from an oocyte to an embryo in C. elegans, but regulated turnover of oocyte-specific proteins contributes to the process. We describe here a gain-of-function mutation (zu405) in a gene that is essential for oocyte maturation, oma-1. In wild type animals, OMA-1 protein is expressed at a high level exclusively in oocytes and newly fertilized embryos and is degraded rapidly after the first mitotic division. The zu405 mutation results in improper degradation of the OMA-1 protein in embryos. In oma-1(zu405) embryos, the C blastomere is transformed to the EMS blastomere fate, resulting in embryonic lethality. We show that degradation of several maternally supplied cell fate determinants, including SKN-1, PIE-1, MEX-3, and MEX-5, is delayed in oma-1(zu405) mutant embryos. In wild type embryos, SKN-1 functions in EMS for EMS blastomere fate specification. A decreased level of maternal SKN-1 protein in the C blastomere relative to EMS is believed to be responsible for this cell expressing the C, instead of the EMS, fate. Delayed degradation of maternal SKN-1 protein in oma-1(zu405) embryos and resultant elevated levels in C blastomere is likely responsible for the observed C-to-EMS blastomere fate transformation. These observations suggest that oma-1, in addition to its role in oocyte maturation, contributes to early embryonic development by regulating the temporal degradation of maternal proteins in early C. elegans embryos.
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Affiliation(s)
- Rueyling Lin
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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Nikolaou S, Hartman D, Presidente PJA, Newton SE, Gasser RB. HcSTK, a Caenorhabditis elegans PAR-1 homologue from the parasitic nematode, Haemonchus contortus. Int J Parasitol 2002; 32:749-58. [PMID: 12062493 DOI: 10.1016/s0020-7519(02)00008-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A putative serine/threonine protein kinase (HcSTK) from the parasitic nematode Haemonchus contortus was characterised at the mRNA and amino acid levels. HcSTK displays a high level of identity (85-93% in the catalytic domain) with proteins of the PAR-1/MARK serine/threonine protein kinase (STK) subfamily, which represent signal transduction molecules involved in establishing and maintaining polarity in proliferating and differentiating cells. The transcript of hcstk is expressed in different developmental stages (second-, third-, fourth-stage larvae and adults) and various organs (muscle, intestine and reproductive) of H. contortus. In addition, there are several isoforms which appear to relate to a single gene. The expression profile of hcstk is similar to that of Caenorhabditis elegans PAR-1, and the level of sequence identity among members of the PAR-1/MARK STK subfamily, representing a range of species of vertebrates (e.g. humans and rodents), invertebrates (e.g. insects and C. elegans) and yeast, suggests that HcSTK may be involved in a conserved signal transduction pathway.
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Affiliation(s)
- Sia Nikolaou
- Victorian Institute of Animal Science, Agriculture Victoria, 475 Mickleham Road, Attwood, Victoria 3049, Australia
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Abstract
The nematode Caenorhabditis elegans was chosen as a model genetic organism because its attributes, chiefly its hermaphroditic lifestyle and rapid generation time, make it suitable for the isolation and characterization of genetic mutants. The most important challenge for the geneticist is to design a genetic screen that will identify mutations that specifically disrupt the biological process of interest. Since 1974, when Sydney Brenner published his pioneering genetic screen, researchers have developed increasingly powerful methods for identifying genes and genetic pathways in C. elegans.
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Affiliation(s)
- Erik M Jorgensen
- Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.
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Abstract
Both Drosophila neuroblasts and Caenorhabditis elegans zygotes use a conserved protein complex to establish cell polarity and regulate spindle orientation. Mammalian epithelia also use this complex to regulate apical/basal polarity. Recent results have allowed us to compare the mechanisms regulating asymmetric cell division in Drosophila neuroblasts and the C. elegans zygote.
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Affiliation(s)
- C Q Doe
- Institute of Molecular Biology, Institute of Neuroscience, Howard Hughes Medical Institute, 1254 University of Oregon, Eugene, Oregon 97403, USA
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