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Myeloid differentiation in blasts is distinguished by the presence of one or more needle-shaped crystalline structures called Auer rods. Auer rods manifest either alone or as faggot cells (containing bundles of Auer rods) in various types of acute myeloid leukemia (AML), myelodysplastic syndromes (MDS) and myelodysplastic/myeloproliferative neoplasms (MDS/MPN). Their presence largely portends a better prognosis in AML (as markers of maturation/differentiation) and upstages cases of MDS and MDS/MPN. Observation of these rods in residual blasts in treated cases of AML indicates an absence of remission. This article traces their historical discovery and examines their pathogenetic intricacies, as well as our current understanding of their relevance in myeloid neoplasms. Studies evaluating their prognostic impact in AML and MDS are catalogued. We also discuss a variety of other hematological and non-hematological neoplasms where structures potentially mistakable for Auer rods have been described. Even as the diagnostic approach to hematological malignancies has evolved from a morphology + cytochemistry + immunophenotyping-dependent one in the last century to a predominantly molecular genetics-based classification currently, and even as high-throughput sequencing and structural variation detection techniques surpass morphology in detecting clinically-relevant sub-categories of similar-appearing tumours, we review these curious microscopic structures that have withstood the test of time with respect to their diagnostic relevance.

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Nearly twenty years ago a mutation in the VAPB gene, resulting in a proline to serine substitution (p.P56S), was identified as the cause of a rare, slowly progressing, familial form of the motor neuron degenerative disease Amyotrophic Lateral Sclerosis (ALS). Since then, progress in unravelling the mechanistic basis of this mutation has proceeded in parallel with research on the VAP proteins and on their role in establishing membrane contact sites between the ER and other organelles. Analysis of the literature on cellular and animal models reviewed here supports the conclusion that P56S-VAPB, which is aggregation-prone, non-functional and unstable, is expressed at levels that are insufficient to support toxic gain-of-function or dominant negative effects within motor neurons. Instead, insufficient levels of the product of the single wild-type allele appear to be required for pathological effects, and may be the main driver of the disease. In light of the multiple interactions of the VAP proteins, we address the consequences of specific VAPB depletion and highlight various affected processes that could contribute to motor neuron degeneration. In the future, distinction of specific roles of each of the two VAP paralogues should help to further elucidate the basis of p.P56S familial ALS, as well as of other more common forms of the disease.

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Magnetotactic bacteria (MTB) are microorganisms thriving mostly at oxic-anoxic boundaries of aquatic habitats. MTB are efficient in biomineralising or sequestering diverse elements intracellularly, which makes them potentially important actors in biogeochemical cycles. Lake Pavin is a unique aqueous system populated by a wide diversity of MTB with two communities harbouring the capability to sequester not only iron under the form of magnetosomes but also phosphorus and magnesium under the form of polyphosphates, or calcium carbonates, respectively. MTB thrive in the water column of Lake Pavin over a few metres along strong redox and chemical gradients representing a series of different microenvironments. In this study, we investigate the relative abundance and the vertical stratification of the diverse populations of MTB in relation to environmental parameters, by using a new method coupling a precise sampling for geochemical analyses, MTB morphotype description, and in situ measurement of the physicochemical parameters. We assess the ultrastructure of MTB as a function of depth using light and electron microscopy. We evidence the biogeochemical niche of magnetotactic cocci, capable of sequestering large PolyP inclusions below the oxic-anoxic transition zone. Our results suggest a tight link between the S and P metabolisms of these bacteria and pave the way to better understand the implication of MTB for the P cycle in stratified environmental conditions.

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Bacteria are the simplest model of living organisms and thus are a convenient object for magnetobiological research. This paper describes some effects of combined magnetic fields (CMFs) on the bacterium Rhodospirillum rubrum strain VKM B-1621, which is not a pathogen but was selected due to its wide spectrum of growth abilities. The authors chose magnetic field-resonant phosphorus and iron (Fe3+ ) because P-containing biochemical compounds (standard abbreviations PP1 , AMP, ADP, ATP) provide energy flows in bacteria while iron could take part in formation of magnetosensitive intracellular inclusions. CMFs were produced by interaction of a geomagnetic field (ВDС ) and an alternating electromagnetic field (ВАС ), which were similar in their intensities. Their magnetic characteristics were as follows: (CMF-1) ВDC = 46.80 µÐ¢, ВАС = 86.11 µT, f = 807.0 Hz; (CMF-2) ВDC = 46.80 µÐ¢, ВАС = 86.11 µT, f = 38.3 Hz; that is, the frequencies of applied alternating electromagnetic fields coincided with cyclotron frequencies of phosphorus or ferric ions, respectively. The blank variants were exposed to the geomagnetic field. The CMFs increased bacterial consumption of dissolved iron as measured by residual concentrations of iron in the medium (P > 99%). An increase of bacterial nitrate reduction in the CMFs was statistically insignificant (P > 90%) when measured by residual concentrations of nitrate. Application of CMFs can influence bacterial activity and metabolism. Bioelectromagnetics. 2018;39:485-490, 2018. © 2018 Wiley Periodicals, Inc.

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