Drosophila polymers

Enzymatically active PARP molecules have also been found involved in transcription in undamaged cells. Recent research on Drosophila has demonstrated that active puff loci are rich in PARPl and ADPR polymers, this being the necessary condition to induce chromatin decondensation and gene expression [159]. Mechanism of PARPl-mediated puffing and chromatin remodeling reinforces the idea previously suggested by Althaus to explain the role played by PARPl in DNA repair [160]. 

The polymer must have a high molar mass. PEG at a range of 6-20 kDa is commonly used (Ersson et al., 1998). Precipitation with PEG was used, for instance, by Demi et al. (1999) as one of the purification steps for the isolation of hepatitis B virus surface antigen (HBsAg) from the insect cell culture supernatant of genetically modified DS-2 Drosophila melanoga-ster Schneider-2) cells. 

In reproductive biology, sialic acid polymers are receiving more and more attention. Polysialic acid with a(2-8)-linkages was found to be expressed on mouse embryos before and after implantation and the neuronal cell adhesion molecule (NCAM), which bears a polysialic acid chain, seems to be involved in cellular interactions in the early mammalian embryo [101,1076]. A similar function is attributed to polysialic acid observed during a short period of the larval stage of Drosophila melanogaster [1077]. It has to be noted that this is the first report on the occurrence of sialic acid in insects. 

Styrene tested positive in an EPA mutagenicity study. It tested positive in a histidine reversion-Ames test, Saccharomyces cerevisiae gene conversion, in vitro human lymphocyte micronuclens, and Drosophila melanogaster sex-linked lethal tests (NIOSH 1986). Carcinogenicity of styrene in humans is not known. There is limited evidence of carcinogenicity in animals for both the monomer and the polymer. 

V. Cell-Free Disassembly of Drosophila Lamin Aggregates (Polymers)... 

Stage 14 Drosophila egg chambers (hereafter referred to as oocytes) are arrested in first meiotic metaphase. A cell-free extract of these oocytes catalyzes apparent disassembly of purified Drosophila nuclei (purified from either embryos or tissue culture cells) as well as of nuclear lamin polymers formed in vitro from isolated interphase lamins (Maus et al., 1995). Biochemically, the oocyte extract catalyzes lamin solubilization and phosphorylation as well as characteristic changes in one- and two-dimensional gel mobility. Cell-free nuclear lamina disassembly is ATP dependent and addition of calcium to extracts blocks disassembly as judged both morphologically and biochemically. 

The most interesting discovery that suggests the existence of Z-DNA in nature was made by Rich and co-workers (Lafer et al., 1981 Noidheim et al, 1981). These authors have successfully produced antibodies that are specific to the Z-DNA conformation, as proved by their binding in vitro to three different DNA polymers capable of forming Z-DNA. These antibodies are found to bind in vivo to the interband regions of polytene chromosomes of Drosophila as visualized by fluorescent staining, thus indi-... 

---