A centromere-derived retroelement RNA localizes in cis and is a core element of the transcriptional landscape of Drosophila centromeres

Centromeres are essential chromosomal landmarks that dictate the point of attachment between chromosomes and spindle microtubules during cell division. The stable transmission of the centromere site through generations is ensured by a unique chromatin containing the histone H3 variant CENP-A. Previous studies have highlighted the impact of transcription on promoting CENP-A deposition. However, the specific sequences undergoing this transcription and their contribution to centromere function in metazoan systems remain elusive. In this study, we unveil the centromeric transcriptional landscape and explore its correlation with CENP-A in D. melanogaster, currently the only in vivo model with assembled centromeres. We find that the centromere-enriched retroelement G2/Jockey-3 (hereafter referred to as Jockey-3) is a major driver of centromere transcription, producing RNAs that localize to all mitotic centromeres, with the Y centromere showing the most transcription. Taking advantage of the polymorphism of Jockey-3, we show that these RNAs remain associated with their cognate DNA sequences in cis. Using a LacI/lacO system to generate de novo centromeres, we find that Jockey-3 transcripts do not localize to ectopic sites, suggesting they are unlikely to function as non-coding RNAs with a structural role at centromeres. At de novo centromeres on the lacO array, the presence of CENP-A augments the detection of exogenous lacO-derived transcripts specifically in metaphase. We propose that Jockey-3 contributes to the epigenetic maintenance of the centromere by promoting chromatin transcription, while inserting in a region that permits its continuous transmission. Given the conservation of retroelements as centromere components across taxa, our findings have broad implications in understanding this widespread association.

Zenker’s diverticulitis: a bitter pill to swallow

Acute oesophageal obstruction from food bolus impaction is often triggered by underlying oesophageal pathology, both benign and malignant. These can be readily detected with standard investigations such as oesophagoscopy or computed tomography. Zenker’s diverticulum (ZD) is a benign condition frequently presenting with chronic dysphagia or may be asymptomatic. We report the case of an 81-year-old man with a previously undiagnosed 1-cm ZD causing complete oesophageal obstruction secondary to localized oedema from an impacted ibuprofen tablet. Although initial clinical, endoscopic and radiological findings were equivocal and suspicious for upper oesophageal malignancy, symptoms rapidly settled in response to systemic corticosteroids. The diagnosis was later confirmed on barium swallow with no other clinical, radiological or histopathological abnormalities identified. In conclusion, ZD is an uncommon cause of acute oesophageal obstruction which may occur in diverticula of all sizes. Surgery should be performed in patients with recurrent symptoms or large diverticula.

Continuous Glucose Monitoring in the Management of Neonatal Hypoglycaemia

A quality improvement project was carried out in a Level 3 Neonatal Intensive Care Unit (NICU) which aimed to successfully implement the use of continuous glucose monitoring systems (CGMS) in hypoglycaemic infants. Piloting of the device revealed several potential practical barriers to its reliably successful implementation. Five Plan-Do-Study-Act (PDSA) cycles followed, tackling these problems and other issues inductively identified throughout the project. Parents and multi-professional stakeholders were involved and consulted throughout. Change was measured on a runchart using qualitative and quantitative feedback. Problem rate per patient was reduced to zero by the end of a one-month study period. This study used basic quality improvement methodologies to implement a change intervention in a structured manner and elucidated aspects of its use that need to be adapted for its successful incorporation into real-life clinical practice.