scholarly journals Centrin Is Necessary for the Formation of the Motile Apparatus in Spermatids of Marsilea

2001 ◽  
Vol 12 (3) ◽  
pp. 761-776 ◽  
Author(s):  
Vincent P. Klink ◽  
Stephen M. Wolniak
Keyword(s):  
Essential Role ◽  
Normal Development ◽  
De Novo ◽  
Basal Bodies ◽  
Double Stranded Rna ◽  
Rna Probes ◽  
Marsilea Vestita ◽  
Stored Mrna ◽  
Novel Method ◽  
Β Tubulin

During spermiogenesis in the water fern, Marsilea vestita, basal bodies are synthesized de novo in cells that lack preexisting centrioles, in a particle known as a blepharoplast. We have focused on basal body assembly in this organism, asking what components are required for blepharoplast formation. Spermiogenesis is a rapid process that is activated by placing dry microspores into water. Dry microspores contain large quantities of stored protein and stored mRNA, and inhibitors reveal that certain proteins are translated from stored transcripts at specific times during development. Centrin translation accompanies blepharoplast appearance, while β-tubulin translation occurs later, during axonemal formation. In asking whether centrin is an essential component of the blepharoplast, we used antisense, sense, and double-stranded RNA probes made from theMarsilea centrin cDNA, MvCen1, to block centrin translation. We employed a novel method to introduce these RNAs directly into the cells. Antisense and sense both arrest spermiogenesis when blepharoplasts should appear, and dsRNA made from the same cDNA is an effective inhibitor at concentrations at least 10 times lower than either of the single-stranded RNA used in these experiments. Blepharoplasts are undetectable and basal bodies fail to form. Antisense, sense, and dsRNA probes made from Marsileaβ-tubulin permitted normal development until axonemes form. In controls, antisense, sense, and dsRNA, made from a segment of HIV, had no effect on spermiogenesis. Immunoblots suggest that translational blocks induced by centrin-based RNA are gene specific and concentration dependent, since neither β-tubulin- nor HIV-derived RNAs affects centrin translation. The disruption of centrin translation affects microtubule distributions in spermatids, since centrin appears to control formation of the cytoskeleton and motile apparatus. These results show that centrin plays an essential role in the formation of a motile apparatus during spermiogenesis of M. vestita.

Molecular cloning of a centrin homolog from Marsilea vestita and evidence for its translational control during spermiogenesis

1999 ◽  
Vol 77 (2) ◽  
pp. 101-108 ◽  
Author(s):  
Peter E Hart ◽  
Stephen M Wolniak
Keyword(s):  
Translational Control ◽  
De Novo ◽  
Basal Bodies ◽  
Motile Cells ◽  
Marsilea Vestita ◽  
Stored Mrna ◽  
Eukaryotic Organisms ◽  
Alpha Amanitin ◽  
Made In

Spermiogenesis in the water fern Marsilea vestita is a process that reaches completion 11 h after dry microspores are immersed in an aqueous medium at 20°C. Each microspore produces 32 spermatozoids and each spermatozoid has a coiled cell body and approximately 140 cilia. The spermatids make basal bodies de novo, from a structure known as a blepharoplast. From the onset of development, the spores contain a large quantity of protein and stored mRNA. We have found previously that centrin, a protein involved in the function of microtubule organizing centers and present in association with basal bodies in motile cells, is made in large quantity approximately 4 h after the microspores are placed into liquid medium. In this paper, we show that a centrin cDNA (MvCen1) we isolated from M. vestita closely resembles centrin cDNAs from other eukaryotic organisms. MvCen1, synthesized in Escherichia coli as a GST-fusion protein, reacted with anti-centrin monoclonal antibodies on immunoblots. Northern blot analysis demonstrates that centrin mRNA is present in the dry microspore at the time of imbibition, at levels that remain constant over 10 h of development and are unaffected by treatment of spores with alpha-amanitin. The centrin transcripts, stored in dry microspores, cannot be translated in vitro for at least 30 min after imbibition.Key words: Marsilea vestita, spermatozoid, spermiogenesis, centrin, MTOC.

Cell cycle arrest allows centrin translation but not basal body formation during spermiogenesis inMarsilea

2001 ◽  
Vol 114 (23) ◽  
pp. 4265-4272 ◽  
Author(s):  
Chiawei W. Tsai ◽  
Stephen M. Wolniak
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
De Novo ◽  
Cyclin B ◽  
Basal Bodies ◽  
Cycle Arrest ◽  
Essentially Normal ◽  
Marsilea Vestita ◽  
Stored Mrna ◽  
Cytoplasmic Particle

Spermiogenesis in the water fern Marsilea vestita is a rapid process that requires the de novo formation of basal bodies in a cytoplasmic particle known as a blepharoplast. Spermiogenesis is activated by placing dry spores into water and is dependent upon the translation of new proteins from stored mRNAs with little, if any, new transcription. We looked at the necessity of cell division cycles in the gametophyte as a prerequisite for the activation of centrin translation and for the consequent formation of blepharoplasts. Cell cycle arrest was induced by treatments of gametophytes with hydroxyurea, with olomoucine, or after RNAi, employing dsRNA derived from Marsilea cyclin A or cyclin B. In all cases, centrin is translated from stored mRNA at the normal time, approximately 4 hours after imbibition, and it accumulates to maximal levels ∼6 hours after imbibition. In spite of the fact that centrin is translated at essentially normal times and accumulates to nearly normal levels, no blepharoplasts form in the gametophytes where division cycles have been disrupted. These results provide a clear demonstration that the new translation of centrin, by itself, is insufficient for blepharoplast formation, the de novo formation of basal bodies, and the assembly of a motile apparatus.

scholarly journals Induction of Promoter DNA Methylation Upon High-Pressure Spraying of Double-Stranded RNA in Plants

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 789
Author(s):  
Athanasios Dalakouras ◽  
Ioannis Ganopoulos
Keyword(s):  
High Pressure ◽  
De Novo ◽  
Epigenetic Changes ◽  
Double Stranded Rna ◽  
Rna Molecules ◽  
Promoter Sequences ◽  
Promoter Dna Methylation ◽  
Promoter Dna ◽  
First Time ◽  
De Novo Methylation

Exogenous application of RNA molecules is a potent method to trigger RNA interference (RNAi) in plants in a transgene-free manner. So far, all exogenous RNAi (exo-RNAi) applications have aimed to trigger mRNA degradation of a given target. However, the issue of concomitant epigenetic changes was never addressed. Here, we report for the first time that high-pressure spraying of dsRNAs can trigger de novo methylation of promoter sequences in plants.

A new case of de novo 11q duplication in a patient with normal development and intelligence and review of the literature

2007 ◽  
Vol 143A (3) ◽  
pp. 265-270 ◽  
Author(s):  
Yuri A. Zarate ◽  
Jillene M. Kogan ◽  
Elizabeth K. Schorry ◽  
Teresa A. Smolarek ◽  
Robert J. Hopkin
Keyword(s):  
Normal Development ◽  
De Novo ◽  
Review Of The Literature

scholarly journals Protein synthesis persists during necrotic cell death

2005 ◽  
Vol 168 (4) ◽  
pp. 545-551 ◽  
Author(s):  
Xavier Saelens ◽  
Nele Festjens ◽  
Eef Parthoens ◽  
Isabel Vanoverberghe ◽  
Michael Kalai ◽  
...  
Keyword(s):  
Cell Death ◽  
Protein Synthesis ◽  
De Novo ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Necrotic Cell Death ◽  
Necrotic Cell ◽  
Proteolytic Activation ◽  
Double Stranded Rna ◽  
Molecular Events

Cell death is an intrinsic part of metazoan development and mammalian immune regulation. Whereas the molecular events orchestrating apoptosis have been characterized extensively, little is known about the biochemistry of necrotic cell death. Here, we show that, in contrast to apoptosis, the induction of necrosis does not lead to the shut down of protein synthesis. The rapid drop in protein synthesis observed in apoptosis correlates with caspase-dependent breakdown of eukaryotic translation initiation factor (eIF) 4G, activation of the double-stranded RNA-activated protein kinase PKR, and phosphorylation of its substrate eIF2-α. In necrosis induced by tumor necrosis factor, double-stranded RNA, or viral infection, de novo protein synthesis persists and 28S ribosomal RNA fragmentation, eIF2-α phosphorylation, and proteolytic activation of PKR are absent. Collectively, these results show that, in contrast to apoptotic cells, necrotic dying cells retain the opportunity to synthesize proteins.

Mechanical Neural Growth Models

2005 ◽  
Author(s):  
Kathleen B. Allen ◽  
Bradley E. Layton
Keyword(s):  
De Novo ◽  
Mechanical Load ◽  
Growth Models ◽  
Growth Patterns ◽  
Polar Structure ◽  
Structural Support ◽  
Inner Surface ◽  
Neural Growth ◽  
Free Environment ◽  
Β Tubulin

Critical to being able to control the growth patterns of cell-based sensors is being able to understand how the cytoskeleton of the cell maintains its structure and integrity both under mechanical load and in a load-free environment. Our approach to a better understanding of cell growth is to use a computer simulation that incorporates the primary structures, microtubules, necessary for growth along with their observed behaviors and experimentally determined mechanical properties. Microtubules are the main compressive structural support elements for the axon of a neuron and are created via polymerization of α-β tubulin dimers. Our de novo simulation explores the mechanics of the forces between microtubules and the membrane. We hypothesize that axonal growth is most influenced by the location and direction of the force exerted by the microtubule on the membrane, and furthermore that the interplay of forces between microtubules and the inner surface of the cell membrane dictates the polar structure of axons. The simulation will be used to understand cytoskeletal mechanics for the purpose of engineering cells to be used as sensors.

scholarly journals Dup(13)(q14.2-q14.3): Yet Another New Differential Diagnostic Aspect for Short Stature–like Phenotype

2005 ◽  
Vol 53 (3) ◽  
pp. 365-366 ◽  
Author(s):  
Isolde Schreyer ◽  
Annett Neumann ◽  
Volkmar Beensen ◽  
Karl-Heinz Eichhorn ◽  
Anita Heller ◽  
...  
Keyword(s):  
Pregnant Woman ◽  
Short Stature ◽  
Growth Retardation ◽  
Normal Development ◽  
De Novo ◽  
Female Child ◽  
Maternal Origin ◽  
Healthy Female ◽  
Diagnostic Aspect ◽  
Fetal Karyotype

We report on the case of a pregnant woman with hyposomia who was previously suspected of having Turner syndrome. Prenatal cytogenetic diagnostics showed a fetal karyotype of 46,XX,dup(13)(q14.2q21.1) ish.13q14(RB1 × 3). Parental and grandparental chromosome analyses were performed and the dup(13) was found to be of maternal origin (de novo). The pregnancy was continued and a healthy female child was born with normal development apart from growth retardation. The reported chromosomal aberration is, together with two other cases reported in the literature, the first hint of a short stature–like phenotype due to dup(13)(q14.2q14.3).

scholarly journals THE DEVELOPMENT OF BASAL BODIES AND FLAGELLA IN ALLOMYCES ARBUSCULUS

1964 ◽  
Vol 23 (2) ◽  
pp. 339-354 ◽  
Author(s):  
Fernando L. Renaud ◽  
Hewson Swift
Keyword(s):  
Electron Microscope ◽  
Basal Body ◽  
De Novo ◽  
The Other ◽  
Basal Bodies ◽  
Distilled Water ◽  
Vegetative Hypha ◽  
Original Length ◽  
Large Primary ◽  
Hyphal Tip

The development of basal bodies and flagella in the water mold Allomyces arbusculus has been studied with the electron microscope. A small pre-existing centriole, about 160 mµ in length, was found in an inpocketing of the nuclear membrane in the vegetative hypha. Thus, formation of a basal body does not occur de novo. When the hyphal tip started to differentiate into gametangia, the centrioles were found to exist in pairs. One of the members of the pair then grew distally to more than three times its original length, whereas the other remained the same size. The larger centriole would correspond to the basal body of a future gamete. Gametogenesis was usually induced by transferring a "ripe" culture to distilled water. Shortly after this was done, a few vesicles were pinched off from the cell membrane of the gametangium and came in contact with the basal body. Apparently, they fused and formed a large primary vesicle. The flagellum then started to grow by invaginating into it. Flagellar fibers were evident from the very beginning. As the flagellum grew so did the vesicle by fusion with secondary vesicles, thus coming to form the flagellar sheath. The different stages of flagellar morphogenesis are described and the possible interrelationships with other processes are discussed.

Viroid-induced DNA methylation in plants

2013 ◽  
Vol 4 (6) ◽  
pp. 557-565 ◽  
Author(s):  
Athanasios Dalakouras ◽  
Elena Dadami ◽  
Michael Wassenegger
Keyword(s):  
Dna Methylation ◽  
Small Rnas ◽  
Rna Silencing ◽  
De Novo ◽  
Rna Degradation ◽  
Double Stranded Rna ◽  
Methyl Group ◽  
Rna Molecules ◽  
Cumulative Data

AbstractIn eukaryotes, DNA methylation refers to the addition of a methyl group to the fifth atom in the six-atom ring of cytosine residues. At least in plants, DNA regions that become de novo methylated can be defined by homologous RNA molecules in a process termed RNA-directed DNA methylation (RdDM). RdDM was first discovered in viroid-infected plants. Viroids are pathogenic circular, non-coding, single-stranded RNA molecules. Members of the Pospiviroidae family replicate in the nucleus through double-stranded RNA intermediates, attracting the host RNA silencing machinery. The recruitment of this machinery results in the production of viroid-derived small RNAs (vd-sRNAs) that mediate RNA degradation and DNA methylation of cognate sequences. Here, we provide an overview of the cumulative data on the field of viroid-induced RdDM and discuss three possible scenarios concerning the mechanistic details of its establishment.

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