The presence of enhancers adjacent to the Ac promoter increases the abundance of transposase mRNA and alters the timing of Ds excision in Arabidopsis

1994 ◽  
Vol 24 (5) ◽  
pp. 789-798 ◽  
Author(s):  
Llu�s Balcells ◽  
George Coupland
Keyword(s):  
Ds Excision ◽  
Transposase Mrna

scholarly journals Excision Patterns of Activator (Ac) and Dissociation (Ds) Elements in Zea mays L.: Implications for the Regulation of Transposition

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1851-1869 ◽  
Author(s):  
Manfred Heinlein
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Waxy Gene ◽  
Transposition Frequency ◽  
Cis Acting ◽  
Dosage Effects ◽  
In Trans ◽  
Ds Excision ◽  
Maize Kernels ◽  
Strong Contrast

The pattern of aleurone variegation of maize kernels carrying Ac and bz-m2(DI) as reporter allele for Ac activity depends on the dosage of both Ac and Ds. Alterations of Ac dosage can abolish Ds excision at certain times and allow it to occur at other times. wx-m7 and wx-m9 are different Ac insertions in the Waxy gene which have different dosage effects on Ds excision. Kernels, heterozygous for the two Ac alleles and being either wx-m7/wx-m7/wx-m9 or wx-m9/wx-m9/wx-m7 exhibit characteristic patterns of predominantly late excisions; this is in strong contrast to the pattern of early excisions present on wx-m7/wx-m7/wx-m7 homozygotes. This observation supports the hypothesis that the Ac alleles express different amounts of transposase (TPase) during development and that above a certain level of TPase transposition is inhibited. Furthermore, experimental results suggest that the frequency of Ac-induced events is influenced by the dosage and composition of the transactivated Ds or Ac allele. Thus, transposition frequency seems not to be exclusively determined in trans by the amount of active TPase, but also by specific cis-acting properties of the TPase substrate.

scholarly journals Regulation of Activator/Dissociation Transposition by Replication and DNA Methylation

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1723-1733
Author(s):  
Francesca Ros ◽  
Reinhard Kunze
Keyword(s):  
Dna Methylation ◽  
Transposable Elements ◽  
Strong Evidence ◽  
Complementary Strand ◽  
Regulatory Effect ◽  
Ds Excision ◽  
Dna Strand ◽  
Petunia Protoplasts ◽  
Ac Transposase ◽  
High Binding Affinity

Abstract In maize the transposable elements Activator/Dissociation (Ac/Ds) transpose shortly after replication from one of the two resulting chromatids (“chromatid selectivity”). A model has been suggested that explains this phenomenon as a consequence of different affinity for Ac transposase binding to holo-, hemi-, and unmethylated transposon ends. Here we demonstrate that in petunia cells a holomethylated Ds is unable to excise from a nonreplicating vector and that replication restores excision. A Ds element hemi-methylated on one DNA strand transposes in the absence of replication, whereas hemi-methylation of the complementary strand causes a >6.3-fold inhibition of Ds excision. Consistently in the active hemi-methylated state, the Ds ends have a high binding affinity for the transposase, whereas binding to inactive ends is strongly reduced. These results provide strong evidence for the above-mentioned model. Moreover, in the absence of DNA methylation, replication enhances Ds transposition in petunia protoplasts >8-fold and promotes formation of a predominant excision footprint. Accordingly, replication also has a methylation-independent regulatory effect on transposition.

scholarly journals Characterization of the Putative Transposase mRNA of Tag1, Which Is Ubiquitously Expressed in Arabidopsis and Can Be Induced by Agrobacterium-Mediated Transformation With dTag1 DNA

Genetics ◽  
1998 ◽  
Vol 149 (2) ◽  
pp. 693-701 ◽  
Author(s):  
Dong Liu ◽  
Nigel M Crawford
Keyword(s):  
Arabidopsis Thaliana ◽  
Transposable Element ◽  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Transcript Levels ◽  
Agrobacterium Mediated Transformation ◽  
Transgenic Lines ◽  
Localization Signal ◽  
Transposase Mrna

Abstract Tag1 is an autonomous transposable element of Arabidopsis thaliana. Tag1 expression was examined in two ecotypes of Arabidopsis (Columbia and No-0) that were transformed with CaMV 35S-Tag1-GUS DNA. These ecotypes contain no endogenous Tag1 elements. A major 2.3-kb and several minor transcripts were detected in all major organs of the plants. The major transcript encoded a putative transposase of 84.2 kD with two nuclear localization signal sequences and a region conserved among transposases of the Ac or hAT family of elements. The abundance of Tag1 transcripts varied among transgenic lines and did not correlate with somatic excision frequency or germinal reversion rates, suggesting that factors other than transcript levels control Tag1 excision activity. In untransformed plants of the Landsberg ecotype, which contain two endogenous Tag1 elements, no Tag1 transcripts were detected. Agrobacterium-mediated transformation of these Landsberg plants with a defective 1.4-kb Tag1 element resulted in the appearance of full-length Tag1 transcripts from the endogenous elements. Transformation with control DNA containing no Tag1 sequences did not activate endogenous Tag1 expression. These results indicate that Agrobacterium-mediated transformation with dTag1 can activate the expression of Tag1.

Introduction of Foreign Genes into Silkworm Eggs by Electroporation and Its Application in Transgenic Vector Test

2004 ◽  
Vol 36 (5) ◽  
pp. 323-330 ◽  
Author(s):  
Xiu-Yang Guo ◽  
Liang Dong ◽  
Sheng-Peng Wang ◽  
Ting-Qing Guo ◽  
Jian-Yang Wang ◽  
...  
Keyword(s):  
Instar Larva ◽  
Foreign Gene ◽  
Positive Ratio ◽  
Significant Difference ◽  
Voltage Dependent ◽  
Localization Signal ◽  
Foreign Genes ◽  
The One ◽  
Transposase Mrna

Abstract Electroporation as a methodology to introduce foreign genes into silkworm eggs was systematically analyzed. The foreign gene in both the newly hatched and 3rd instar larva DNA can be detected by PCR. The amount of foreign gene in 3rd instar larva DNA was about 1/1000 of that in newly hatched larva DNA. The ratio of foreign gene entering into silkworm eggs was voltage dependent and showed significant difference between the tested silkworm strains. When the piggyBac transposon system was applied, the effect of nuclear localization signal (NLS) peptide and the in vitro transcribed transposase mRNA on the transposition rate has been measured. Results showed that the in vitro transcribed transposase mRNA facilitated transposition to take place earlier and NLS could result in higher transposition probability and earlier transposition as well. When linearized vectors containing varied length of flanking homologous sequences around a reporter gene were introduced into silkworm eggs by electroporation, the one with 2.6 kb total arm length gave higher G1 positive ratio than that with total arm length of 1.5 kb and 800 bp.

scholarly journals Elevated levels of Activator transposase mRNA are associated with high frequencies of Dissociation excision in Arabidopsis.

1992 ◽  
Vol 4 (5) ◽  
pp. 583-595 ◽  
Author(s):  
J Swinburne ◽  
L Balcells ◽  
S R Scofield ◽  
J D Jones ◽  
G Coupland
Keyword(s):  
High Frequencies ◽  
Transposase Mrna

scholarly journals The IS10 transposase mRNA is destabilized during antisense RNA control.

1990 ◽  
Vol 9 (4) ◽  
pp. 1259-1266 ◽  
Author(s):  
C.C. Case ◽  
E.L. Simons ◽  
R.W. Simons
Keyword(s):  
Antisense Rna ◽  
Transposase Mrna

Variations in the maize Ac transposase transcript level and the Ds excision frequency in transgenic wheat callus lines

Genome ◽  
1999 ◽  
Vol 42 (6) ◽  
pp. 1234-1241 ◽  
Author(s):  
Shigeo Takumi ◽  
Koji Murai ◽  
Naoki Mori ◽  
Chiharu Nakamura
Keyword(s):  
Microprojectile Bombardment ◽  
Transcript Level ◽  
Gus Gene ◽  
Large Variability ◽  
Transposase Gene ◽  
Ds Excision ◽  
Ac Transposase ◽  
Callus Lines ◽  
Transgenic Callus ◽  
Wheat Callus

To investigate the excision of a maize transposable element in wheat cells, plasmid DNAs containing a Dissociation (Ds) element located between a rice actin 1 gene promoter and a beta-glucuronidase (GUS) gene (gus) were introduced into wheat callus lines by microprojectile bombardment, and transient GUS expression was assayed. The gus-expressing cells after Ds excision were detected only when the Activator (Ac) transposase gene was co-transformed. To further examine a relationship between the amount of Ac mRNA and the Ds excision frequency, the Ds-containing plasmids were introduced into 15 independent transgenic callus lines transformed with the Ac transposase gene. Ten lines expressed the Ac transposase gene under the control of either the cauliflower mosaic virus 35S promoter or the Ac native promoter. The gus gene expression that indicated the Ds excision was observed only in the transgenic callus lines stably expressing the Ac transposase gene. The number of blue spots reflecting the frequency of Ds excision was variable among them. Northern-blot analysis also showed a large variability in the amount of Ac transposase transcripts among the lines. It was however noted that the excision frequency was decreased at a high level of the Ac transposase transcripts, supporting the hypothesis that Ds excision is inhibited above a certain level of the Ac transposase as observed in maize and transgenic tobacco.Key words: transposon, Ds excision, Ac transposase transcript level, transgenic callus, wheat.

scholarly journals Analysis of Extrachromosomal Ac/Ds Transposable Elements

Genetics ◽  
2000 ◽  
Vol 155 (1) ◽  
pp. 349-359 ◽  
Author(s):  
Vera Gorbunova ◽  
Avraham A Levy
Keyword(s):  
Random Sequence ◽  
Donor Site ◽  
Plasmid Rescue ◽  
Present Evidence ◽  
Extrachromosomal Elements ◽  
Linear Elements ◽  
Ds Excision ◽  
Hairpin Formation ◽  
Insight Into ◽  
Original Donor

Abstract The mechanism of transposition of the maize Ac/Ds elements is not well understood. The true transposition intermediates are not known and it has not been possible to distinguish between excision models involving 8-bp staggered cuts or 1-bp staggered cuts followed by hairpin formation. In this work, we have analyzed extrachromosomal excision products to gain insight into the excision mechanism. Plasmid rescue was used to demonstrate that Ds excision is associated with the formation of circular molecules. In addition, we present evidence for the formation of linear extrachromosomal species during Ds excision. Sequences found at the termini of circular and linear elements showed a broad range of nucleotide additions or deletions, suggesting that these species are not true intermediates. Additional nucleotides adjacent to the termini in extrachromosomal elements were compared to the sequence of the original donor site. This analysis showed that: (1) the first nucleotide adjacent to the transposon end was significantly more similar to the first nucleotide flanking the element in the donor site than to a random sequence and (2) the second and farther nucleotides did not resemble the donor site. The implications of these findings for excision models are discussed.

Elevated Levels of Activator Transposase mRNA Are Associated with High Frequencies of Dissociation Excision in Arabidopsis

1992 ◽  
Vol 4 (5) ◽  
pp. 583
Author(s):  
June Swinburne ◽  
Lluis Balcells ◽  
Steven R. Scofield ◽  
Jonathan D. G. Jones ◽  
George Coupland
Keyword(s):  
High Frequencies ◽  
Transposase Mrna
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