Transcription of a centromere-enriched retroelement and local retention of its RNA are significant features of the CENP-A chromatin landscape.

Centromeres depend on chromatin containing the conserved histone H3 variant CENP-A for function and inheritance, while the role of centromeric DNA repeats remains unclear. Retroelements are prevalent at centromeres across taxa and represent a potential mechanism for promoting transcription to aid in CENP-A incorporation or for generating RNA transcripts to maintain centromere integrity. Here, we probe into the transcription and RNA localization of the centromere-enriched retroelement G2/Jockey-3 (hereafter referred to as Jockey-3 ) in Drosophila melanogaster , currently the only in vivo model with assembled centromeres. We find that Jockey-3 is a major component of the centromeric transcriptome and produces RNAs that localize to centromeres in metaphase. Leveraging the polymorphism of Jockey-3 and a de novo centromere system, we show that these RNAs remain associated with their cognate DNA sequences in cis , suggesting they are unlikely to perform a sequence-specific function at all centromeres. We show that Jockey-3 transcription is positively correlated with the presence of CENP-A, and that recent Jockey-3 transposition events have occurred preferentially at CENP-A-containing chromatin. We propose that Jockey-3 contributes to the epigenetic maintenance of centromeres by promoting chromatin transcription, while inserting preferentially within these regions, selfishly ensuring its continued expression and transmission. Given the conservation of retroelements as centromere components through evolution, our findings have broad implications in understanding this association in other species.

The Oxfordshire Community Stroke Project classification in the early hours of ischemic stroke and relation to infarct site and size on cranial computed tomography.

BACKGROUND AND PURPOSE: The Oxfordshire Community Stroke Project (OCSP) classification clinically subdivides cerebral infarction into total anterior circulation (TACS), partial anterior circulation (PACS), posterior circulation (POCS) and lacunar (LACS) syndromes. We compared the OCSP classification in patients presenting within 12 hours of onset of stroke with infarct site and size on computed tomography (CT) brain scan at 5 to 7 days. METHODS: OCSP classification was prospectively assigned by 1 of 3 observers in 43 patients presenting within 12 hours of stroke. CT brain scan was performed on admission to exclude primary intracerebral hemorrhage. Repeat CT brain scan at 5 to 7 days was used to classify recent visible infarction as total anterior circulation infarction (TACI), partial anterior circulation infarction (PACI), lacunar circulation infarction (LACI), or posterior circulation infarction (POCI). For each OCSP subtype, sensitivity and specificity were calculated by using CT classification as a standard. RESULTS: Median (range) interval from onset of stroke symptoms to OCSP classification was 5.0 (1.5, 11.75) hours. Thirty-seven patients had ischemic stroke, with recent visible infarction in 34 (92%). Sensitivity and specificity of each OCSP subtype was TACS (0.80, 0.82), PACS (0.56, 0.79), LACS (0.33, 0.88), and POCS (1.00, 0.97). Overall, 65% of OCSP subtypes assigned were correct when compared to CT classification. CONCLUSIONS: In this small study, we have shown that the OCSP classification within 12 hours of ischemic stroke onset compares with CT classification at 5 to 7 days. Larger studies are required to evaluate the validity of the OCSP classification in the early hours of ischemic stroke in guiding appropriate patient selection for acute stroke therapy and interventions.

Changes in the HMO marketplace and the new role of consumers.

The HMO marketplace is becoming increasingly dominated by two organizational structures: the network or mixed model and the IPA model. Combined, these two HMO structures represent over 80% of all plans. Both of these plan types tend to be decentralized and diverse, causing separation of ownership and control. This article uses agency theory to examine various control mechanisms including the involvement of the consumer.