A Comparison of the Effectiveness of Silibinin and Resveratrol in Preventing Alpha-Amanitin-Induced Hepatotoxicity

At least one of the procyclic acidic repetitive protein (PARP or procyclin) loci of Trypanosoma brucei is a small (5- to 6-kilobase) polycistronic transcription unit which is transcribed in an alpha-amanitin-resistant manner. Its single promoter, as mapped by run-on transcription analysis and UV inactivation of transcription, is located immediately upstream of the first alpha-PARP gene. Transcription termination occurs in a region approximately 3 kilobases downstream of the beta-PARP gene. The location of the promoter was confirmed by its ability to direct transcription of the bacterial chloramphenicol acetyltransferase gene in insect-form (procyclic) T. brucei. The putative PARP promoter is located in the region between the 3' splice acceptor site (nucleotide position 0) and nucleotide position -196 upstream of the alpha-PARP genes. Regulatory regions influencing the levels of PARP expression may be located further upstream. We conclude that a single promoter, which is located very close to the 3' splice acceptor site of the alpha-PARP genes, directs the transcription of a small, polycistronic, and alpha-amanitin-resistant transcription unit.

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Expression of the HSP 70.1 gene, a landmark of early zygotic activity in the mouse embryo, is restricted to the first burst of transcription

Development ◽

10.1242/dev.121.1.113 ◽

1995 ◽

Vol 121 (1) ◽

pp. 113-122 ◽

Cited By ~ 4

Author(s):

E. Christians ◽

E. Campion ◽

E.M. Thompson ◽

J.P. Renard

Keyword(s):

Dna Replication ◽

Mouse Embryo ◽

Culture Conditions ◽

Hsp 70 ◽

Cell Stage ◽

Embryonic Genome ◽

Genome Activation ◽

Alpha Amanitin ◽

Zygotic Genome

Activation of the mouse embryonic genome at the 2-cell stage is characterized by the synthesis of several alpha-amanitin-sensitive polypeptides, some of which belong to the multigenic hsp 70 family. In the present work we show that a member of this family, the HSP 70.1 gene, is highly transcribed at the onset of zygotic genome activation. Transcription of this gene began as early as the 1-cell stage. Expression of the gene continued through the early 2-cell stage but was repressed before the completion of the second round of DNA replication. During this period we observed that the level of transcription was modulated by in vitro culture conditions. The coincidence of repression of HSP70.1 transcription with the second round of DNA replication was not found for other transcription-dependent polypeptides synthesized at the 2-cell stage.

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Unequal cleavage in leech embryos: zygotic transcription is required for correct spindle orientation in subset of early blastomeres

Development ◽

10.1242/dev.122.2.599 ◽

1996 ◽

Vol 122 (2) ◽

pp. 599-606

Author(s):

S.T. Bissen ◽

C.M. Smith

Keyword(s):

Cell Division ◽

Early Period ◽

Spindle Orientation ◽

Mitotic Spindles ◽

Maternal Control ◽

Transcription Analysis ◽

Cell Divisions ◽

Zygotic Transcription ◽

Different Types ◽

Alpha Amanitin

Leech embryos undergo invariant sequences of equal and unequal cell divisions to give rise to identifiable progeny cells. While many of the early cleavages are under maternal control, the divisions of a subset of early blastomeres (the large cells of the D' lineage) are perturbed after the inhibition of zygotic transcription. Analysis of the different types of cells produced in embryos injected with the transcriptional inhibitor, alpha-amanitin, revealed that the symmetry of cell division is perturbed in these large D'-derived cells during this early period of development. These cells, which would normally undergo a series of equal and unequal cleavages, always undergo equal cleavages after the inhibition of zygotic transcription. It appears that zygotically transcribed gene product(s) are required in the large cells of the D' lineage to orient the mitotic spindles properly for these unequal cell cleavages.

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