Cervical cancer isolate PT3, super-permissive for adeno-associated virus replication, over-expresses DNA polymerase δ, PCNA, RFC and RPA

<p>Abstract</p> <p>Background</p> <p>Adeno-associated virus (AAV) type 2 is an important virus due to its use as a safe and effective human gene therapy vector and its negative association with certain malignancies. AAV, a dependo-parvovirus, autonomously replicates in stratified squamous epithelium. Such tissue occurs in the nasopharynx and anogenitals, from which AAV has been clinically isolated. Related autonomous parvoviruses also demonstrate cell tropism and preferentially replicate in oncogenically transformed cells. Combining these two attributes of parvovirus tropism, squamous and malignant, we assayed if AAV might replicate in squamous cervical carcinoma cell isolates.</p> <p>Results</p> <p>Three primary isolates (PT1-3) and two established cervical cancer cell lines were compared to normal keratinocytes (NK) for their ability to replicate AAV. One isolate, PT3, allowed for high levels of AAV DNA replication and virion production compared to others. In research by others, four cellular components are known required for <it>in vitro </it>AAV DNA replication: replication protein A (RPA), replication factor C (RFC), proliferating cell nuclear antigen (PCNA), and DNA polymerase delta (POLD1). Thus, we examined PT3 cells for expression of these components by DNA microarray and real-time quantitative PCR. All four components were over-expressed in PT3 over two representative low-permissive cell isolates (NK and PT1). However, this super-permissiveness did not result in PT3 cell death by AAV infection.</p> <p>Conclusion</p> <p>These data, for the first time, provide evidence that these four cellular components are likely important for AAV <it>in vivo </it>DNA replication as well as <it>in vitro</it>. These data also suggest that PT3 will be a useful reagent for investigating the AAV-permissive transcriptome and AAV anti-cancer effect.</p

Mus81-mediated DNA cleavage resolves replication forks stalled by topoisomerase I–DNA complexes

Replication forks stalled by excess DNA supercoiling can be resolved by DNA cleavage by the Mus81 endonuclease

Iterative Image Based Video Summarization by Node Segmentation

In this paper, we propose a simple video summarization system based on removal of similar frames and the maintenance of unique frames. It tries to capture the temporal content of the frame and to output the video with a length specified by the user. It aims at eliminating similar frames by a process of clustering where similar frames are clustered into one group. Similar frames have less degree of variation in visual frames, color distribution and visual attributes. When clusters are formed, a fraction of the frames from each of the group is retrieved to form a sequence of frames resulting in the desired output