BackgroundGiant viruses in the genus Chlorovirus (family Phycodnaviridae) infect eukaryotic green microalgae. The prototype member of the genus, Paramecium bursaria chlorella virus 1, was sequenced more than 15 years ago, and to date there are only 6 fully sequenced chloroviruses in public databases. Presented here are the draft genome sequences of 35 additional chloroviruses (287 – 348 Kb/319 – 381 predicted protein encoding genes) collected across the globe; they infect one of three different green algal species. These new data allowed us to analyze the genomic landscape of 41 chloroviruses, which revealed some remarkable features about these viruses.ResultsGenome colinearity, nucleotide conservation and phylogenetic affinity were limited to chloroviruses infecting the same host, confirming the validity of the three previously known subgenera. Clues for the existence of a fourth new subgenus indicate that the boundaries of chlorovirus diversity are not completely determined. Comparison of the chlorovirus phylogeny with that of the algal hosts indicates that chloroviruses have changed hosts in their evolutionary history. Reconstruction of the ancestral genome suggests that the last common chlorovirus ancestor had a slightly more diverse protein repertoire than modern chloroviruses. However, more than half of the defined chlorovirus gene families have a potential recent origin (after Chlorovirus divergence), among which a portion shows compositional evidence for horizontal gene transfer. Only a few of the putative acquired proteins had close homologs in databases raising the question of the true donor organism(s). Phylogenomic analysis identified only seven proteins whose genes were potentially exchanged between the algal host and the chloroviruses.ConclusionThe present evaluation of the genomic evolution pattern suggests that chloroviruses differ from that described in the related Poxviridae and Mimiviridae. Our study shows that the fixation of algal host genes has been anecdotal in the evolutionary history of chloroviruses. We finally discuss the incongruence between compositional evidence of horizontal gene transfer and lack of close relative sequences in the databases, which suggests that the recently acquired genes originate from a still largely un-sequenced reservoir of genomes, possibly other unknown viruses that infect the same hosts.

The 331-kbp chlorovirusParamecium bursariachlorella virus 1 (PBCV-1) genome was resequenced and annotated to correct errors in the original 15-year-old sequence; 40 codons was considered the minimum protein size of an open reading frame. PBCV-1 has 416 predicted protein-encoding sequences and 11 tRNAs. A proteome analysis was also conducted on highly purified PBCV-1 virions using two mass spectrometry-based protocols. The mass spectrometry-derived data were compared to PBCV-1 and its hostChlorella variabilisNC64A predicted proteomes. Combined, these analyses revealed 148 unique virus-encoded proteins associated with the virion (about 35% of the coding capacity of the virus) and 1 host protein. Some of these proteins appear to be structural/architectural, whereas others have enzymatic, chromatin modification, and signal transduction functions. Most (106) of the proteins have no known function or homologs in the existing gene databases except as orthologs with proteins of other chloroviruses, phycodnaviruses, and nuclear-cytoplasmic large DNA viruses. The genes encoding these proteins are dispersed throughout the virus genome, and most are transcribed late or early-late in the infection cycle, which is consistent with virion morphogenesis.

Section 6 of the "Repository policy for OpenAIR @ RGU" (available from http://www.rgu.ac.uk/staff-and-currentstudents/library/library-policies/repository-policies) provides guidance on the criteria under which RGU will consider withdrawing material from OpenAIR. If you believe that this item is subject to any of these criteria, or for any other reason should not be held on OpenAIR, then please contact openair-help@rgu.ac.uk with the details of the item and the nature of your complaint. saw@ecs.soton.ac.uk ABSTRACTAcademics expend a large amount of time and effort to sustain and enhance the motivation of undergraduate students. Typically based on a desire to ensure that all students achieve their full potential, approaches are based on an understanding that students who are highly motivated will learn more. Furthermore, institutional rewards accrue from effective use of academics' time, along with financial benefits associated with high levels of retention and progression. This working group report, based on practice in Europe, Australasia and North America, builds on previous work. It provides an updated and revised literature review, analyses a larger collection of survey data and has sought to triangulate earlier findings with qualitative data from practitioner interviews. The report covers established approaches in teaching, support and extra-curricular activities. It tracks emerging practice such as streamed and differentiated teaching, and research based and authentic learning. It also considers contemporary innovations in student activities. Finally it reports on a repository of tips and techniques which has been established to support faculty wishing to change or review current methods. Categories and Subject Descriptors

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Purpose -The development of a K-12 computer science curriculum based on constructivist principles needs to be informed by knowledge of content and process concepts that are central to the discipline of computer science. The paper aims to discuss this issue. Design/methodology/approach -Taking a cross-cultural approach and using an experimental design (a SPF-2•15×16 split-plot design), this study compares the combinations of content and process concepts identified as important in Germany with those considered relevant in the US context. Findings -First, the combinations of content and process concepts identified in the German context can be generalized to the US context. Second, it is possible to identify combinations of content and process concepts in the US context that are also important in the German context. Third, content and process concepts identified in the two contexts can be integrated to generate a broader perspective that is valid for both contexts. Practical implications -The results can be used for consolidating available curricular drafts for computer science as a teaching subject at school of the type available in many. The present findings are of great relevance for research-based approaches to the pre-and in-service education of computer science teachers. The methodological approach taken is important in efforts to consolidate curricular models of computer science education, as have been initiated by the Bologna process in Europe and by the organizations Association for Computing Machinery, Association for Information Systems, and Institute of Electrical and Electronic Engineers-Computer Society in the USA. Originality/value -Results show that competence areas of central concepts identified in the two contexts can be integrated to generate a broader perspective that is valid for both contexts.