Mastermind Mutations Generate a Unique Constellation of Midline Cells within the Drosophila CNS

Background: The Notch pathway functions repeatedly during the development of the central nervous system in metazoan organisms to control cell fate and regulate cell proliferation and asymmetric cell divisions. Within the Drosophila midline cell lineage, which bisects the two symmetrical halves of the central nervous system, Notch is required for initial cell specification and subsequent differentiation of many midline lineages. Methodology/Principal Findings: Here, we provide the first description of the role of the Notch co-factor, mastermind, in the central nervous system midline of Drosophila. Overall, zygotic mastermind mutations cause an increase in midline cell number and decrease in midline cell diversity. Compared to mutations in other components of the Notch signaling pathway, such as Notch itself and Delta, zygotic mutations in mastermind cause the production of a unique constellation of midline cell types. The major difference is that midline glia form normally in zygotic mastermind mutants, but not in Notch and Delta mutants. Moreover, during late embryogenesis, extra anterior midline glia survive in zygotic mastermind mutants compared to wild type embryos. Conclusions/Significance: This is an example of a mutation in a signaling pathway cofactor producing a distinct centra

Optical Density Changes Of Gafchromic MD-55 Film Resulting From Laser Light Exposure At Wavelengths Of 671 Nm And 633 Nm

Laser-based scanners provide a sensitive means for measuring optical density (OD) of Gafchromic films. Such instruments were reviewed in a recent AAPM report (task group 55) which provided recommendations and information on OD measurements (effect of wavelength, temperature, etc.). The present article reports that variable rate scanners and spot densitometers using laser diodes (671 nm) and HeNe lasers (633 nm) can cause polymerization of Gafchromic film. The light induced polymerization depends on light power, wavelength, beam spot size, dwell time, and prior radiation dose of the film. Measurements were made with a custom built scanner that provided accurate control of light power, light polarization, dwell time, and film position in relation to the beam focus. The results demonstrate that lasers operating with powers of 0.1, 0.5, 1.0, and 1.5 mW produce a nonlinear increase in OD of Gafchromic film. The measured change in OD after 1 min of exposure ranges from 0.150 to 0.244 for a laser diode operating at 0.5 and 1.5 mW, respectively. Tables are included that tabulate the increase in OD for laser power, dwell time, and prior dose. Laser light induced polymerization can have a significant impact on dosimetry measurements acquired using these laser-based systems. (C) 2000 American Association of Physicists in Medicine. [S0094-2405(00)03301-0]

[ 18 F]-Labeled PARP-1 PET imaging of PSMA targeted alpha particle radiotherapy response

The growing interest and clinical translation of alpha particle (α) therapies brings with it new challenges to assess target cell engagement and to monitor therapeutic effect. Noninvasive imaging has great potential to guide α-treatment and to harness the potential of these agents in the complex environment of disseminated disease. Poly(ADP) ribose polymerase 1 (PARP-1) is among the most abundantly expressed DNA repair enzymes with key roles in multiple repair pathways-such as those induced by irradiation. Here, we used a third-generation PARP1-specific radiotracer,

Combined HIV-1 sequence and integration site analysis informs viral dynamics and allows reconstruction of replicating viral ancestors

Understanding HIV-1 persistence despite antiretroviral therapy (ART) is of paramount importance. Both single-genome sequencing (SGS) and integration site analysis (ISA) provide useful information regarding the structure of persistent HIV DNA populations; however, until recently, there was no way to link integration sites to their cognate proviral sequences. Here, we used multiple-displacement amplification (MDA) of cellular DNA diluted to a proviral endpoint to obtain full-length proviral sequences and their corresponding sites of integration. We applied this method to lymph node and peripheral blood mononuclear cells from 5 ART-treated donors to determine whether groups of identical subgenomic sequences in the 2 compartments are the result of clonal expansion of infected cells or a viral genetic bottleneck. We found that identical proviral sequences can result from both cellular expansion and viral genetic bottlenecks occurring prior to ART initiation and following ART failure. We identified an expanded T cell clone carrying an intact provirus that matched a variant previously detected by viral outgrowth assays and expanded clones with wild-type and drug-resistant defective proviruses. We also found 2 clones from 1 donor that carried identical proviruses except for nonoverlapping deletions, from which we could infer the sequence of the intact parental virus. Thus, MDA-SGS can be used for "viral reconstruction" to better understand intrapatient HIV-1 evolution and to determine the clonality and structure of proviruses within expanded clones, including those with drug-resistant mutations. Importantly, we demonstrate that identical sequences observed by standard SGS are not always sufficient to establish proviral clonality