SummaryTo understand organ function, it is important to have an inventory of its cell types and of their corresponding marker genes. This is a particularly challenging task for human tissues like the pancreas, because reliable markers are limited. Hence, transcriptome-wide studies are typically done on pooled islets of Langerhans, obscuring contributions from rare cell types and of potential subpopulations. To overcome this challenge, we developed an automated platform that uses FACS, robotics, and the CEL-Seq2 protocol to obtain the transcriptomes of thousands of single pancreatic cells from deceased organ donors, allowing in silico purification of all main pancreatic cell types. We identify cell type-specific transcription factors and a subpopulation of REG3A-positive acinar cells. We also show that CD24 and TM4SF4 expression can be used to sort live alpha and beta cells with high purity. This resource will be useful for developing a deeper understanding of pancreatic biology and pathophysiology of diabetes mellitus.

SummaryAdult mitotic tissues like the intestine, skin, and blood undergo constant turnover throughout the life of an organism. Knowing the identity of the stem cell is crucial to understanding tissue homeostasis and its aberrations upon disease. Here we present a computational method for the derivation of a lineage tree from single-cell transcriptome data. By exploiting the tree topology and the transcriptome composition, we establish StemID, an algorithm for identifying stem cells among all detectable cell types within a population. We demonstrate that StemID recovers two known adult stem cell populations, Lgr5+ cells in the small intestine and hematopoietic stem cells in the bone marrow. We apply StemID to predict candidate multipotent cell populations in the human pancreas, a tissue with largely uncharacterized turnover dynamics. We hope that StemID will accelerate the search for novel stem cells by providing concrete markers for biological follow-up and validation.

No abstract

No abstract

In low-risk patients, there was no difference in cardiac outcome at one year between those who underwent on-pump bypass surgery and those who underwent off-pump surgery. Off-pump surgery was more cost effective.

for the Octopus Study Group C ORONARY ARTERY BYPASS graft (CABG) surgery effectively relieves angina but is associated with significant cerebral morbidity. 1 This has largely been attributed to the use of cardiopulmonary bypass. 1,2 Cardiopulmonary bypass requires cannulation and crossclamping of the ascending aorta, which may dislodge atheromatous macroemboli, leading to stroke. 3 Cardiopulmonary bypass also increases the permeability of the blood-brain barrier and generates microemboli, which may adversely affect cognitive function. 4,5 The incidence of cognitive decline in the first year after surgery ranges from less than 5% to more than 30%, depending both on patient characteristics and on the definition of decline that is used. 2,6 Stroke occurs in approximately 3% of patients undergoing CABG surgery. 1 The desire to avoid the perceived ill effects of cardiopulmonary bypass has led to a renewed interest in bypass surgery on the beating heart (off-pump CABG surgery). This has been stimulated by the development of cardiac stabilizers, which facilitate the construc-Author Affiliations: Departments of Anesthesiology (Drs van Dijk and Kalkman and Ms Spoor), Psychiatry (Dr Hijman), Cardiology (Drs Nathoe and Borst), and Cardiothoracic Surgery (Dr Jansen

The V-ATPase is the main regulator of intra-organellar acidification. Assembly of this complex has extensively been studied in yeast, while limited knowledge exists for man. We identified 11 male patients with hemizygous missense mutations in ATP6AP1, encoding accessory protein Ac45 of the V-ATPase. Homology detection at the level of sequence profiles indicated Ac45 as the long-sought human homologue of yeast V-ATPase assembly factor Voa1. Processed wild-type Ac45, but not its disease mutants, restored V-ATPase-dependent growth in Voa1 mutant yeast. Patients display an immunodeficiency phenotype associated with hypogammaglobulinemia, hepatopathy and a spectrum of neurocognitive abnormalities. Ac45 in human brain is present as the common, processed ∼40-kDa form, while liver shows a 62-kDa intact protein, and B-cells a 50-kDa isoform. Our work unmasks Ac45 as the functional ortholog of yeast V-ATPase assembly factor Voa1 and reveals a novel link of tissue-specific V-ATPase assembly with immunoglobulin production and cognitive function.

The human U1A protein‐U1A pre‐mRNA complex and the relationship between its structure and function in inhibition of polyadenylation in vitro were investigated. Two molecules of U1A protein were shown to bind to a conserved region in the 3′ untranslated region of U1A pre‐mRNA. The secondary structure of this region was determined by a combination of theoretical prediction, phylogenetic sequence alignment, enzymatic structure probing and molecular genetics. The U1A binding sites form (part of) a complex secondary structure which is significantly different from the binding site of U1A protein on U1 snRNA. Studies with mutant pre‐mRNAs showed that the integrity of much of this structure is required for both high affinity binding to U1A protein and specific inhibition of polyadenylation in vitro. In particular, binding of a single molecule of U1A protein to U1A pre‐mRNA is not sufficient to produce efficient inhibition of polyadenylation.