Detection of transcriptome-wide microRNA-target interactions in single cells with agoTRIBE.

MicroRNAs (miRNAs) exert their gene regulatory effects on numerous biological processes based on their selection of target transcripts. Current experimental methods available to identify miRNA targets are laborious and require millions of cells. Here we have overcome these limitations by fusing the miRNA effector protein Argonaute2 to the RNA editing domain of ADAR2, allowing the detection of miRNA targets transcriptome-wide in single cells. miRNAs guide the fusion protein to their natural target transcripts, causing them to undergo A>I editing, which can be detected by sensitive single-cell RNA sequencing. We show that agoTRIBE identifies functional miRNA targets, which are supported by evolutionary sequence conservation. In one application of the method we study microRNA interactions in single cells and identify substantial differential targeting across the cell cycle. AgoTRIBE also provides transcriptome-wide measurements of RNA abundance and allows the deconvolution of miRNA targeting in complex tissues at the single-cell level.

Historical RNA expression profiles from the extinct Tasmanian tiger.

Paleogenomics continues to yield valuable insights into the evolution, population dynamics, and ecology of our ancestors and other extinct species. However, DNA sequencing cannot reveal tissue-specific gene expression, cellular identity, or gene regulation, which are only attainable at the transcriptional level. Pioneering studies have shown that useful RNA can be extracted from ancient specimens preserved in permafrost and historical skins from extant canids, but no attempts have been made so far on extinct species. We extract, sequence, and analyze historical RNA from muscle and skin tissue of a ∼130-year-old Tasmanian tiger (Thylacinus cynocephalus) preserved in desiccation at room temperature in a museum collection. The transcriptional profiles closely resemble those of extant species, revealing specific anatomical features such as slow muscle fibers or blood infiltration. Metatranscriptomic analysis, RNA damage, tissue-specific RNA profiles, and expression hotspots genome-wide further confirm the thylacine origin of the sequences. RNA sequences are used to improve protein-coding and noncoding annotations, evidencing missing exonic loci and the location of ribosomal RNA genes while increasing the number of annotated thylacine microRNAs from 62 to 325. We discover a thylacine-specific microRNA isoform that could not have been confirmed without RNA evidence. Finally, we detect traces of RNA viruses, suggesting the possibility of profiling viral evolution. Our results represent the first successful attempt to obtain transcriptional profiles from an extinct animal species, providing thought-to-be-lost information on gene expression dynamics. These findings hold promising implications for the study of RNA molecules across the vast collections of natural history museums and from well-preserved permafrost remains.

The Artery of Adamkiewicz: Anatomy and Considerations in Spine Surgery - A Review of the Literature.

The artery of Adamkiewicz (AKA) provides blood supply to the thoracolumbar spinal cord. Any disruption of the AKA can lead to the anterior spinal artery (ASA) syndrome, with devastating systematic and neurologic complications for the patient. This is a narrative review of the anatomy of AKA, the characteristics of ASA syndrome and the role of radiologic techniques in diagnosis and treatment. A detailed search of the PubMed database was conducted from January 2000 until April 2020, to locate articles relevant to our study. The references of the included studies were also retrieved in order not to miss any information. The ASA syndrome can present as a possible post-operative complication after minimally invasive or open surgeries of multiple specialties that involve the field of spine. Risk factors associated with ASA syndrome include; kyphosis of the patient, corresponding spinal surgical approach, intraoperative hypotension, multiple ligations of the AKA, a left side approach and a 360-combined or revision surgery. The incidence varies among different operations. Many different imaging modalities have been used in preoperative plan, including but not limited to computed tomography angiography, magnetic resonance angiography, and subtraction angiography. The use of computed tomography angiography or magnetic resonance angiography preoperatively can play a major role in the prevention of the ASA syndrome. However, more research needs to be done before making any final assumptions.

Morel-lavallée lesion: report of a case of unknown mechanism.

Morel-Lavallée lesions are cystic lesions occurring between the subcutaneous tissue and the underlying layer of a fascia. The most frequent mechanism of occurrence is posttraumatic, usually after degloving injuries. The chain of events leading to the occurrence of this lesion is the formation of a potential space between the subcutaneous tissue and the firmly attached deep fascia, which in turn fills with blood and/or lymph and/or necrotic fat, secondary to disruption of the capillaries. We present a case of a 74-year-old male patient with a cystic lesion of the lateral surface of his left thigh increasing in size over a period of six months. Despite the meticulous history acquisition, we were unable to reveal any alleged mechanism of injury of the area. The patient underwent an MRI which revealed an ovoid cyst. The patient underwent surgical excision of the cyst. The pathology examination revealed a simple cyst, lined by a fibrous capsule and filled with serosanguineous fluid, thus confirming the diagnosis. The patient made a full recovery and since has been asymptomatic.