Sebastian Pfaff

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We have constructed a Xenopus laevis oocyte expression vector, pOEV, which allows cloned DNA to be transcribed and translated directly in the oocyte. Since proteins translated in oocytes are post-translationally modified according to conserved eukaryotic signals, these cells offer a convenient system for performing structural and functional analyses of(More)
Expression of the Xenopus laevis transcription factor IIIA (TFIIIA) gene is developmentally regulated. In this study we have used defined nucleotide mutations to map cis-elements involved in transcriptional regulation of the promoter for oocyte-TFIIIA (O-TFIIIA) in stage II-IV oocytes, stage VI oocytes, and tail bud embryos. During oogenesis O-TFIIIA mRNA(More)
TFIIIA mRNA expression is developmentally regulated during Xenopus oogenesis. We have identified a positive-acting cis-element in the TFIIIA gene located between -671 and -629 with respect to the mRNA initiation site, termed element 3. Element 3 contributes to the efficient transcription of the TFIIIA gene in stage III oocytes, but is inactive in the normal(More)
The Xenopus TFIIIA gene is transcribed very efficiently in oocytes. In addition to a TATA element at -30, we show that from -425 to +7 the TFIIIA gene contains only two positive cis elements centered at -267 (element 1) and -230 (element 2). This arrangement of the cis elements in the TFIIIA gene is striking because these two elements are positioned very(More)
We consider optimal control problems governed by nonlinear hyperbolic conservation laws at junctions and analyze in particular the Fréchet-differentiability of the reduced objective functional. This is done by showing that the control-to-state mapping of the considered problems satisfies a generalized notion of differentiability. We consider both, the case(More)
The oncogenic avian retrovirus OK10 has the genetic structure gag-delta pol-myc-delta-env. The myc sequence is transduced from a cellular gene, proto-myc, while gag, pol, and env are essential retrovirus genes. By analogy with other directly oncogenic retroviruses, the specific myc sequence of OK10 is thought to be essential for transforming function.(More)
The transforming (onc) genes of retroviruses contain specific sequences, derived from as yet poorly defined, normal cellular genes, termed proto-onc genes. Proto-onc genes must be defined to explain their docility compared to the oncogenicity of the viral derivatives. Here we set out to determine the borders of the chicken proto-fps gene from which the onc(More)
This paper focuses on the differentiability properties of the control-to-state mapping for entropy solutions to a scalar hyperbolic conservation law on R with respect to the switching times of an on/off control. As an example we consider the traffic density on a unidirectional road described by the LWR-model that is controlled by a traffic light switching(More)
We consider the optimal control of initial-boundary value problems for entropy solutions of scalar hyperbolic conservation laws. In particular, we consider initial-boundary value problems where the initial and boundary data switch between different C 1-functions at certain switching points and both, the functions and the switching points, are controlled. We(More)
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