Successful application of ancient DNA extraction and library construction protocols to museum wet collection specimens

Millions of scientific specimens are housed in museum collections, a large part of which are fluid preserved. The use of formaldehyde as fixative and subsequent storage in ethanol is especially common in ichthyology and herpetology. This type of preservation damages DNA and reduces the chance of successful retrieval of genetic data. We applied ancient DNA extraction and single stranded library construction protocols to a variety of vertebrate samples obtained from wet collections and of different ages. Our results show that almost all samples tested yielded endogenous DNA. Archival DNA extraction was successful across different tissue types as well as using small amounts of tissue. Conversion of archival DNA fragments into single-stranded libraries resulted in usable data even for samples with initially undetectable DNA amounts. Subsequent target capture approaches for mitochondrial DNA using homemade baits on a subset of 30 samples resulted in almost complete mitochondrial genome sequences in several instances. Thus, application of ancient DNA methodology makes wet collection specimens, including type material as well as rare, old or extinct species, accessible for genetic and genomic analyses. Our results, accompanied by detailed step-by-step protocols, are a large step forward to open the DNA archive of museum wet collections for scientific studies

Interdisciplinary care of children with diffuse midline glioma

Diffuse Midline Glioma (DMG) which includes Diffuse Intrinsic Pontine Glioma (DIPG) is an infiltrative tumor of the midline structures of the central nervous system that demonstrates an aggressive pattern of growth and has no known curative treatment. As these tumors progress, children experience ongoing neurological decline including inability to ambulate, swallow and communicate effectively. We propose that optimal care for patients with DMG should involve a specialized team experienced in caring for the multifaceted needs of these patients and their families. Herein we review the roles and evidence to support early involvement of a specialized interdisciplinary team and outline our views on best practices for these challenging tumors

Structural and mechanistic insight into the Listeria monocytogenes two-enzyme lipoteichoic acid synthesis system

Lipoteichoic acid (LTA) is an important cell wall component required for proper cell growth in many Gram-positive bacteria. In Listeria monocytogenes, two enzymes are required for the synthesis of this polyglycerolphosphate polymer. The LTA primase LtaPLm initiates LTA synthesis by transferring the first glycerolphosphate (GroP) subunit onto the glycolipid anchor and the LTA synthase LtaSLm extends the polymer by the repeated addition of GroP subunits to the tip of the growing chain. Here, we present the crystal structures of the enzymatic domains of LtaPLm and LtaSLm. Although the enzymes share the same fold, substantial differences in the cavity of the catalytic site and surface charge distribution contribute to enzyme specialization. The eLtaSLm structure was also determined in complex with GroP revealing a second GroP binding site. Mutational analysis confirmed an essential function for this binding site and allowed us to propose a model for the binding of the growing chain