Jordan, an active Volvox transposable element similar to higher plant transposons.

Miller, Stephen M.; Schmitt, Rüdiger; Kirk, David L.

doi:10.1105/tpc.5.9.1125

Cited by 58 publications

(47 citation statements)

References 53 publications

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“…Eukaryotic transposons that transpose without an RNA intermediate create short target site duplications upon insertion at a new genomic site; they possess short terminal inverted repeats (TIRs), and they are also frequently characterized by subterminal repeats which serve as transposase binding sites (38,42,44). Because the RE described here has all these structural properties, we propose that it is a transposon and have named it restless.…”

Section: Resultsmentioning

confidence: 99%

restless, an Active Ac-like Transposon from the Fungus Tolypocladium inflatum: Structure, Expression, and Alternative RNA Splicing

Kempken

Kück

1996

Molecular and Cellular Biology

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Elements of the hAT transposon family, such as the maize activator (Ac), have been discovered in a large number of eukaryotic species. This type of class II transposon, present in both plants and animals, has not been previously detected in any fungal organism. However, using a differential screening method to detect repetitive DNA, we have identified a hAT transposon in the hyphomycete Tolypocladium inflatum. The transposon, which we named restless, is 4,097 bp long, carries 20-bp inverted repeats and an 8-bp target site duplication, and encodes a long open reading frame which is interrupted by a single intronic sequence. The derived mRNA exhibits alternative splicing, resulting in the formation of two transcripts that may be translated into polypeptides of 157 or 803 amino acids. The predicted amino acid sequence of the larger polypeptide demonstrates significant homology with transposases from the hAT transposon family. A chromosomal analysis using pulsed-field gel electrophoresis showed that all seven chromosomal bands carry copies of the 4.1-kb transposon. This was confirmed in hybridization experiments with rare-cutting restriction endonucleases which indicate that about 15 copies are present in T. inflatum. The genomic distribution of restless and its transcriptional expression, alternative mRNA splicing, and genomic mobility all imply a potential role for this element in developing a transposon tagging system for use in filamentous fungi.Eukaryotic transposons can be divided into two major groups (18, 42). Class I transposable elements are able to transpose via an RNA intermediate, a process which employs a reverse transcriptase. Well-known members of this type include retrotransposons such as the copia element from Drosophila melanogaster (17) and the Ty elements from Saccharomyces cerevisiae (61).Class II elements, which transpose via DNA intermediates, demonstrate direct excision prior to their integration into target sequences. The best-known examples are the Ac-Ds elements of maize, discovered about half a century ago by Barbara McClintock (40,41).Both classes of transposons have previously been identified in filamentous fungi. In a few cases, such as the Neurospora crassa Tad element (37) and the Fusarium oxysporum Fot1 and impala elements (10, 39), this was achieved by the use of a transposon trap. Others were discovered by characterizing repeated DNA sequences, leading to the isolation of the MGR (24) and grasshopper (13) elements from Magnaporthe grisea, the Foret element from F. oxysporum (31), and the CfT-1 element from Cladosporium fulvum (43). The majority of these fungal transposons are class I transposable elements, while only a few belong to class II (Fot1 and impala). Those elements, whose prototypes were found in Caenorhabditis elegans or in D. melanogaster (7,28,46), were characterized as Tc1-mariner-like transposons (9).Here, we describe the isolation and characterization of a class II transposon from Tolypocladium inflatum ATCC 34921 (synonym Beauveria nivea [20,60]). This filamentou...

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Section: Resultsmentioning

confidence: 99%

restless, an Active Ac-like Transposon from the Fungus Tolypocladium inflatum: Structure, Expression, and Alternative RNA Splicing

Kempken

Kück

1996

Molecular and Cellular Biology

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“…On the other hand, in the related colonial alga V. carteri, where methylcytosine frequency is slightly higher than in C. reinhardtii (1.1% versus approximately 0.75%), nuclear methylation did appear to be associated with gene silencing (Babinger et al, 2001(Babinger et al, , 2007. Interestingly, V. carteri also has a more repeat-rich genome than C. reinhardtii with many active transposons (Miller et al, 1993;Ueki and Nishii, 2008;Prochnik et al, 2010) and may have retained or evolved higher levels of nuclear methylation activity than C. reinhardtii to suppress transposon activity.…”

Section: Dna Methylation Changes During the Life Cyclementioning

confidence: 98%

Dynamic changes in the transcriptome and methylome of Chlamydomonas reinhardtii throughout its life cycle

et al. 2015

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; 0000-0001-9355-9564 (M.P.).The green alga Chlamydomonas reinhardtii undergoes gametogenesis and mating upon nitrogen starvation. While the steps involved in its sexual reproductive cycle have been extensively characterized, the genome-wide transcriptional and epigenetic changes underlying different life cycle stages have yet to be fully described. Here, we performed transcriptome and methylome sequencing to quantify expression and DNA methylation from vegetative and gametic cells of each mating type and from zygotes. We identified 361 gametic genes with mating type-specific expression patterns and 627 genes that are specifically induced in zygotes; furthermore, these sex-related gene sets were enriched for secretory pathway and alga-specific genes. We also examined the C. reinhardtii nuclear methylation map with base-level resolution at different life cycle stages. Despite having low global levels of nuclear methylation, we detected 23 hypermethylated loci in gene-poor, repeat-rich regions. We observed mating type-specific differences in chloroplast DNA methylation levels in plus versus minus mating type gametes followed by chloroplast DNA hypermethylation in zygotes. Lastly, we examined the expression of candidate DNA methyltransferases and found three, DMT1a, DMT1b, and DMT4, that are differentially expressed during the life cycle and are candidate DNA methylases. The expression and methylation data we present provide insight into cell type-specific transcriptional and epigenetic programs during key stages of the C. reinhardtii life cycle.Chlamydomonas reinhardtii is a unicellular, biflagellate species of green alga found primarily in fresh water and soil (Harris et al., 2009). C. reinhardtii is an important reference organism for diverse eukaryotic cellular and metabolic processes, including photosynthetic biology (Rochaix, 2001), flagellar function and biogenesis (Silflow and Lefebvre, 2001), nutrient homeostasis (Grossman, 2000;Merchant et al., 2006;Glaesener et al., 2013), and sexual cycles (Goodenough et al., 2007). The nuclear and chloroplast genomes of C. reinhardtii have been fully sequenced, enabling genomic and epigenomic analyses (Maul et al., 2002;Merchant et al., 2007). The approximately 112-Mb haploid C. reinhardtii nuclear genome comprises 17 chromosomes. The circular chloroplast DNA (cpDNA) genome is 203 kb and present in 80 to 100 copies per cell that are organized into eight to 10 nucleoprotein complexes called nucleoids, which are distributed through the stroma.Like many unicellular eukaryotes, C. reinhardtii has a biphasic life cycle where haploid cells can reproduce vegetatively by mitotic division or, alternatively, undergo a sexual cycle. Vegetative cells can propagate indefinitely when provided with nutrients and light. Upon nitrogen starvation, however, cells stop dividing and differentiate into gametes whose mating type (plus or minus) is determined genetically by an approximately 300-kb mating type locus on chromosome 6, with two haplotypes, MT+ and MT2 (Umen, 2011; De Hoff et al.,...

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“…However, the morphologically wild-type strain that was used as the progenitor of the InvB mutants in this investigation was CRH22, which was derived from EVE by mutagenesis (Miller et al, 1993). CRH22 and all of its progeny carry a partial deletion of nitA, the nitrate reductase-encoding locus, which makes them suitable for cotransformation studies, using the nitA gene as the selectable marker.…”

Section: Volvox Carteri Strains Cultivation Conditions and Isolatiomentioning

confidence: 99%

“…However, all efforts to analyze the primary defects in such mutants were unsuccessful for many years, until a gene-tagging system based on an endogenous transposon called Jordan was developed (Miller et al, 1993), making tagging, recovery, and sequencing of such genes possible. Jordan was used to tag, recover, and characterize an inversionless gene called invA, which encodes a kinesin that provides the motile force to turn the cell sheet inside-out during inversion (Nishii et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Controlled Enlargement of the Glycoprotein Vesicle Surrounding aVolvoxEmbryo Requires the InvB Nucleotide-Sugar Transporter and Is Required for Normal Morphogenesis

Ueki

Nishii

2009

The Plant Cell

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Here, we report our analysis of a mutant of Volvox carteri, InvB, whose embryos fail to execute inversion, the process in which each Volvox embryo normally turns itself inside-out at the end of embryogenesis, thereby achieving the adult configuration. The invB gene encodes a nucleotide-sugar transporter that exhibits GDP-mannose transport activity when expressed in yeast. In wild-type embryos, the invB transcript is maximally abundant before and during inversion. A mannoside probe (fluorescent concanavalin A) stains the glycoprotein-rich gonidial vesicle (GV) surrounding wild-type embryos much more strongly than it stains the GV surrounding InvB embryos. Direct measurements revealed that throughout embryogenesis the GV surrounding a wild-type embryo increases in size much more than the GV surrounding an InvB embryo does, and the fully cleaved InvB embryo is much more tightly packed within its GV than a wild-type embryo is. To test the hypothesis that the restraint imposed by a smaller than normal GV directly causes the inversion defect in the mutant, we released InvB embryos from their GVs microsurgically. The resulting embryos inverted normally, demonstrating that controlled enlargement of the GV, by a process in which requires the InvB nucleotide-sugar transporter, is essential to provide the embryo sufficient space to complete inversion.

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Jordan, an active Volvox transposable element similar to higher plant transposons.

Cited by 58 publications

References 53 publications

restless, an Active Ac-like Transposon from the Fungus Tolypocladium inflatum: Structure, Expression, and Alternative RNA Splicing

restless, an Active Ac-like Transposon from the Fungus Tolypocladium inflatum: Structure, Expression, and Alternative RNA Splicing

Dynamic changes in the transcriptome and methylome of Chlamydomonas reinhardtii throughout its life cycle

Controlled Enlargement of the Glycoprotein Vesicle Surrounding aVolvoxEmbryo Requires the InvB Nucleotide-Sugar Transporter and Is Required for Normal Morphogenesis

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