Suboxic DOM is bioavailable to surface prokaryotes in a simulated overturn of an oxygen minimum zone, Devil’s Hole, Bermuda

Oxygen minimum zones (OMZs) are expanding due to increased sea surface temperatures, subsequent increased oxygen demand through respiration, reduced oxygen solubility, and thermal stratification driven in part by anthropogenic climate change. Devil’s Hole, Bermuda is a model ecosystem to study OMZ microbial biogeochemistry because the formation and subsequent overturn of the suboxic zone occur annually. During thermally driven stratification, suboxic conditions develop, with organic matter and nutrients accumulating at depth. In this study, the bioavailability of the accumulated dissolved organic carbon (DOC) and the microbial community response to reoxygenation of suboxic waters was assessed using a simulated overturn experiment. The surface inoculated prokaryotic community responded to the deep (formerly suboxic) 0.2 μm filtrate with cell densities increasing 2.5-fold over 6 days while removing 5 μmol L−1 of DOC. After 12 days, the surface community began to shift, and DOC quality became less diagenetically altered along with an increase in SAR202, a Chloroflexi that can degrade recalcitrant dissolved organic matter (DOM). Labile DOC production after 12 days coincided with an increase of Nitrosopumilales, a chemoautotrophic ammonia oxidizing archaea (AOA) that converts ammonia to nitrite based on the ammonia monooxygenase (amoA) gene copy number and nutrient data. In comparison, the inoculation of the deep anaerobic prokaryotic community into surface 0.2 μm filtrate demonstrated a die-off of 25.5% of the initial inoculum community followed by a 1.5-fold increase in cell densities over 6 days. Within 2 days, the prokaryotic community shifted from a Chlorobiales dominated assemblage to a surface-like heterotrophic community devoid of Chlorobiales. The DOM quality changed to less diagenetically altered material and coincided with an increase in the ribulose-1,5-bisphosphate carboxylase/oxygenase form I (cbbL) gene number followed by an influx of labile DOM. Upon reoxygenation, the deep DOM that accumulated under suboxic conditions is bioavailable to surface prokaryotes that utilize the accumulated DOC initially before switching to a community that can both produce labile DOM via chemoautotrophy and degrade the more recalcitrant DOM

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Correction: Temporal and spatially controlled APP transgene expression using Cre-dependent alleles

Although a large number of mouse models have been made to study Alzheimer's disease, only a handful allow experimental control over the location or timing of the protein being used to drive pathology. Other fields have used the Cre and the tamoxifen-inducible CreER driver lines to achieve precise spatial and temporal control over gene deletion and transgene expression, yet these tools have not been widely used in studies of neurodegeneration. Here, we describe two strategies for harnessing the wide range of Cre and CreER driver lines to control expression of disease-associated amyloid precursor protein (APP) in modeling Alzheimer's amyloid pathology. We show that CreER-based spatial and temporal control over APP expression can be achieved with existing lines by combining a Cre driver with a tetracycline-transactivator (tTA)-dependent APP responder using a Cre-to-tTA converter line. We then describe a new mouse line that places APP expression under direct control of Cre recombinase using an intervening lox-stop-lox cassette. Mating this allele with a CreER driver allows both spatial and temporal control over APP expression, and with it, amyloid onset. This article has an associated First Person interview with the first author of the paper

Development of Astatine-211 ( 211 At)-Based Anti-CD123 Radioimmunotherapy for Acute Leukemias and Other CD123+ Hematologic Malignancies

Abstract Background: Radioimmunotherapy (RIT) has long been pursued to improve outcomes in acute leukemia. Of current interest are alpha-particle emitting radionuclides as they deliver a very large amount of radiation over just a few cell diameters, enabling efficient and selective target cell kill. So far, alpha-emitters including astatine-211 (211At) have been primarily explored with monoclonal antibodies (mAbs) targeting CD45 or CD33 but their broad display on non-malignant target-expressing cells can lead to marked "on-target, off tumor cell" toxicities. To overcome this limitation, we developed a novel form of 211At-based RIT targeting CD123. CD123 is displayed widely on acute leukemia cells, including underlying leukemic stem cells, but is expressed only on a discrete subset of normal hematopoietic cells and is virtually absent on non-blood cells. Methods: We immunized BALB/c mice with peptides consisting of the extracellular domain of human CD123 to generate anti-CD123 mAbs. Flow cytometry-based assays with human acute leukemia cell lines were used to characterize binding of hybridoma supernatants and mAbs to CD123. mAbs were conjugated with isothiocyantophenethyl-ureido-closo-decaborate(2-) (B10), a boron cage molecule for subsequent astatination, and were then labeled with 211At. In vivo leukemia cell targeting ("biodistribution") and efficacy studies were conducted in immunodeficient NOD-Rag1 null IL2rɣ null/J (NRG) mice xenografted with MOLM-13 cells, a CD123+ human acute myeloid leukemia cell line. Results: Based on initial hybridoma screening studies, we selected 4 mAbs (10C4, 5G4, 11F11, and 1H8) for further characterization. Phenotyping studies with CD123+ and CD123- human acute leukemia cell lines (including CD123+ cell lines in which CD123 was deleted via CRISPR/Cas9) confirmed specific binding of all mAbs to human CD123 (binding intensity: 10C4&gt;5G4=11F11=1H8), with 10C4 yielding a higher median fluorescence intensity than the widely used commercial anti-CD123 mAb clones, 7G3 and 6H6 (Figure 1). In vitro internalization with a panel of human acute leukemia cell lines studies demonstrated uptake of all mAbs by CD123+ target cells with a kinetic slower than that for anti-CD33 antibodies (typically, 30-50% of the anti-CD123 mAb internalized over 2-4 hours). All 4 anti-CD123 mAbs could be conjugated to B10 and subsequently labeled with 211At. Unlike a non-binding 211At-labeled control mAb, 211At-labeled anti-CD123 mAbs showed uptake at MOLM-13 flank tumors in NRG mice carrying MOLM-13 xenografts. After additional leukemia cell targeting studies to optimize the dosing of 10C4, we conducted proof-of-concept efficacy studies in NRG mice injected intravenously with luciferase-transduced MOLM-13 cells (disseminated leukemia model). Animals were either untreated or treated with 10 µCi, 20 µCi, or 40 µCi of 211At-labeled 10C4-B10 mAb (9-11 animals/group). This was followed by the infusion of bone marrow cells from donor mice as stem cell support 3 days later. As shown in Figure 2 and Figure 3, 211At-10C4-B10 led to a dose dependent decrease in tumor burden. Further, the treatment significantly prolonged survival compared to untreated animals (median survival: 49 days [40 µCi of 211At] vs. 31 days [10 µCi of 211At] vs. 21 days [Ctrl]; P&lt;0.0001 for Ctrl vs. 10 µCi, P&lt;0.004 for 10 µCi vs. 40 µCi), demonstrating potent in vivo anti-leukemia efficacy of a single dose of 211At-CD123 RIT. Conclusion: Our data support the further development of 211At-CD123 RIT for the treatment of patients with acute leukemia and other CD123+ hematologic malignancies. Figure 1 Figure 1. Disclosures Green: Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Cellectar Biosciences: Research Funding; GSK: Membership on an entity's Board of Directors or advisory committees; JANSSEN Biotech: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Therapeutics: Patents & Royalties, Research Funding; Legend Biotech: Consultancy; Neoleukin Therapeutics: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; SpringWorks Therapeutics: Research Funding. Walter: Kite: Consultancy; Janssen: Consultancy; Genentech: Consultancy; BMS: Consultancy; Astellas: Consultancy; Agios: Consultancy; Amphivena: Consultancy, Other: ownership interests; Selvita: Research Funding; Pfizer: Consultancy, Research Funding; Jazz: Research Funding; Macrogenics: Consultancy, Research Funding; Immunogen: Research Funding; Celgene: Consultancy, Research Funding; Aptevo: Consultancy, Research Funding; Amgen: Research Funding. </jats:sec

The Alpha Emitter Astatine-211 Targeted to CD38 Can Eradicate Multiple Myeloma in Minimal Residual Disease Models

Abstract Introduction Multiple myeloma (MM) is considered incurable but patients achieving minimal-residual disease (MRD) negative status following treatment have significantly better overall and progression-free survival. MM is highly heterogeneous both between and within patients, limiting the curative potential of novel agents targeting specific pathways. However all MM is highly sensitive to radiation. The α-emitter astatine-211 (211At) deposits a very large amount of energy (~100 keV/μm) within a few cell diameters (50-90 μm) resulting in irreparable double strand DNA breaks, making 211At, targeted to MM cells, particularly suited to eliminating MRD. CD38 is expressed on malignant plasma cells regardless of mutational status, and CD38 monoclonal antibodies (mAbs) constitute a proven targeted therapy for MM but do not alone eradicate disease. We proposed that 211At conjugated to an anti-CD38 mAb could effectively eliminate MM MRD, and tested this hypothesis in cellular and murine models. Methods We conjugated the anti-CD38 mAb OKT10 and an isotype matched control mAb, BHV1, to the amine-reactive labeling agent B10-NCS and labeled the final constructs with 211At. To assess in vitro cell binding we incubated each labeled construct with CD38+ cell lines, washed, and then measured cell pellet radioactivity in a gamma counter. To assess cytotoxicity we incubated CD38+ and CD38- cell lines with unlabeled or 211At-labeled OKT10-B10 for 60 hrs, then assayed viability. NOD.Cg-Rag1tm1Mom Il2rgtm1Wjl/SzJ (NRG) mice bearing H929luc or OPM-2luc MM xenografts were generated by subcutaneous (SQ) flank injection of 107 cells 7 days prior to treatment. MRD was modeled by intravenous (IV) injection of 2.5 - 5 x 105 cells 5 days prior to treatment. Radioimmunotherapy (RIT) was administered by IV injection of 7.5 - 45 µCi of 211At-OKT10-B10 or 211At-BHV1-B10. For biodistribution studies (n = 5/group) mouse tissues were harvested 24 hrs post RIT and measured in a gamma counter. For therapy studies (n = 8-10/group), all mice received syngeneic bone marrow transplant 3 days post RIT. Disease progression was assessed by tumor dimensions, luminescence imaging and survival. Results 211At-CD38 mAb selectively bound and killed CD38+ but not CD38- MM cells in vitro. In vivo, biodistribution experiments demonstrated that 211At-CD38 RIT delivered 2.4 times more radiation to MM xenografts than did control 211At-BHV1 RIT (p = 0.007), and delivered significantly higher dose to tumor than to healthy tissues including lung (p = 0.04) and kidney (p = 0.015). In murine therapy studies, 211At-CD38 RIT at 15 - 45 µCi at least doubled median survival relative to untreated controls in each of two MM SQ xenograft models (p 15 µCi 211At-CD38-RIT [p = 0.016] and all other groups [p Conclusions The efficacy of CD38 targeted 211At appears to be a function of disease distribution and malignant plasma cell access, as compellingly demonstrated by our models. Bulky tumor geometry reduces mAb penetration. In contrast, the isolated cells and small tumor clusters that define MRD are readily accessible to mAbs, creating optimal conditions for α-emitter cell kill. In an era of highly potent MM therapy, preventing relapse remains frustratingly rare. Our approach is both agnostic to high-risk cytogenetic features and offers the potential to eliminate all residual MM cell clones. These encouraging findings will be explored in a clinical trial of 211At-CD38 RIT. Download : Download high-res image (203KB) Download : Download full-size image Disclosures Orozco: Actinium Pharmaceuticals: Research Funding. Jones: Juno Therapeutics, a Celgene Company: Employment, Equity Ownership. Till: Mustang Bio: Patents & Royalties, Research Funding. Gopal: Teva: Research Funding; Spectrum: Research Funding; Janssen: Consultancy, Research Funding; BMS: Research Funding; Incyte: Consultancy; Gilead: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Brim: Consultancy; Pfizer: Research Funding; Aptevo: Consultancy; Takeda: Research Funding; Merck: Research Funding; Asana: Consultancy. Green: Juno Therapeutics: Patents & Royalties, Research Funding

The α-emitter astatine-211 targeted to CD38 can eradicate multiple myeloma in a disseminated disease model

Minimal residual disease (MRD) has become an increasingly prevalent and important entity in multiple myeloma (MM). Despite deepening responses to frontline therapy, roughly 75% of MM patients never become MRD-negative to ≤10-5, which is concerning because MRD-negative status predicts significantly longer survival. MM is highly heterogeneous, and MRD persistence may reflect survival of isolated single cells and small clusters of treatment-resistant subclones. Virtually all MM clones are exquisitely sensitive to radiation, and the α-emitter astatine-211 (211At) deposits prodigious energy within 3 cell diameters, which is ideal for eliminating MRD if effectively targeted. CD38 is a proven MM target, and we conjugated 211At to an anti-CD38 monoclonal antibody to create an 211At-CD38 therapy. When examined in a bulky xenograft model of MM, single-dose 211At-CD38 at 15 to 45 µCi at least doubled median survival of mice relative to untreated controls (P 150 days) for 50% to 80% of mice, where all untreated mice died in 20 to 55 days (P < .0001). Treatment toxicities were transient and minimal. These data suggest that 211At-CD38 offers the potential to eliminate residual MM cell clones in low-disease-burden settings, including MRD. We are optimistic that, in a planned clinical trial, addition of 211At-CD38 to an autologous stem cell transplant (ASCT) conditioning regimen may improve ASCT outcomes for MM patients

Hybrid breeding in wheat: technologies to improve hybrid wheat seed production

Global food security demands the development and delivery of new technologies to increase and secure cereal production on finite arable land without increasing water and fertilizer use. There are several options for boosting wheat yields, but most offer only small yield increases. Wheat is an inbred plant, and hybrids hold the potential to deliver a major lift in yield and will open a wide range of new breeding opportunities. A series of technological advances are needed as a base for hybrid wheat programmes. These start with major changes in floral development and architecture to separate the sexes and force outcrossing. Male sterility provides the best method to block self-fertilization, and modifying the flower structure will enhance pollen access. The recent explosion in genomic resources and technologies provides new opportunities to overcome these limitations. This review outlines the problems with existing hybrid wheat breeding systems and explores molecular-based technologies that could improve the hybrid production system to reduce hybrid seed production costs, a prerequisite for a commercial hybrid wheat system.Ryan Whitford, Delphine Fleury, Jochen C. Reif, Melissa Garcia, Takashi Okada, Viktor Korzun and Peter Langridg