Explore the vast range of titles available.

Gene targeting in embryonic stem cells has become the principal technology for manipulation of the mouse genome, offering unrivalled accuracy in allele design and access to conditional mutagenesis. To bring these advantages to the wider research community, large-scale mouse knockout programmes are producing a permanent resource of targeted mutations in all protein-coding genes. Here we report the establishment of a high-throughput gene-targeting pipeline for the generation of reporter-tagged, conditional alleles. Computational allele design, 96-well modular vector construction and high-efficiency gene-targeting strategies have been combined to mutate genes on an unprecedented scale. So far, more than 12,000 vectors and 9,000 conditional targeted alleles have been produced in highly germline-competent C57BL/6N embryonic stem cells. High-throughput genome engineering highlighted by this study is broadly applicable to rat and human stem cells and provides a foundation for future genome-wide efforts aimed at deciphering the function of all genes encoded by the mammalian genome. Knockout mice with potential Knockout mice in which a specific gene is inactivated are central to the analysis of gene function. An important resource is reported here in the form of a high-throughput gene targeting pipeline that has already produced thousands of conditional mutations in the C57BL/6 embryonic stem-cell line, suitable for the creation of mutant mice for large-scale phenotyping programmes. The strategy is also applicable to rat and human stem cells and provides a foundation for deciphering the function of all genes encoded by the mammalian genome.

Chlamydia trachomatis remains a leading cause of bacterial sexually transmitted infections and preventable blindness worldwide. There are, however, limited in vitro models to study the role of host genetics in the response of macrophages to this obligate human pathogen. Here, we describe an approach using macrophages derived from human induced pluripotent stem cells (iPSdMs) to study macrophage– Chlamydia interactions in vitro . We show that iPSdMs support the full infectious life cycle of C. trachomatis in a manner that mimics the infection of human blood-derived macrophages. Transcriptomic and proteomic profiling of the macrophage response to chlamydial infection highlighted the role of the type I interferon and interleukin 10-mediated responses. Using CRISPR/Cas9 technology, we generated biallelic knockout mutations in host genes encoding IRF5 and IL-10RA in iPSCs, and confirmed their roles in limiting chlamydial infection in macrophages. This model can potentially be extended to other pathogens and tissue systems to advance our understanding of host-pathogen interactions and the role of human genetics in influencing the outcome of infections. In vitro models to study the role of host genetics in the response to chlamydial infection are limited. Here, Yeung et al . show that macrophages derived from human induced pluripotent stem cells (which can be genetically manipulated) support chlamydial infection and can be used for this purpose.

The clinical complications of malaria are caused by the parasite expansion in the blood. Invasion of erythrocytes is a complex process that depends on multiple receptor-ligand interactions. Identification of host receptors is paramount for fighting the disease as it could reveal new intervention targets, but the enucleated nature of erythrocytes makes genetic approaches impossible and many receptors remain unknown. Host-parasite interactions evolve rapidly and are therefore likely to be species-specific. As a results, understanding of invasion receptors outside the major human pathogen Plasmodium falciparum is very limited. Here we use mouse embryonic stem cells (mESCs) that can be genetically engineered and differentiated into erythrocytes to identify receptors for the rodent malaria parasite Plasmodium berghei. Two proteins previously implicated in human malaria infection: glycophorin C (GYPC) and Band-3 (Slc4a1) were deleted in mESCs to generate stable cell lines, which were differentiated towards erythropoiesis. In vitro infection assays revealed that while deletion of Band-3 has no effect, absence of GYPC results in a dramatic decrease in invasion, demonstrating the crucial role of this protein for P. berghei infection. This stem cell approach offers the possibility of targeting genes that may be essential and therefore difficult to disrupt in whole organisms and has the potential to be applied to a variety of parasites in diverse host cell types.

The International Mouse Phenotyping Consortium reports the generation of new mouse mutant strains for more than 5,000 genes, including 2,850 novel null, 2,987 novel conditional-ready and 4,433 novel reporter alleles.

Mutational signatures are imprints of pathophysiological processes arising through tumorigenesis. We generated isogenic CRISPR-Cas9 knockouts (Δ) of 43 genes in human induced pluripotent stem cells, cultured them in the absence of added DNA damage, and performed whole-genome sequencing of 173 subclones. Δ Δ Δ Δ Δ Δ Δ Δ and Δ produced marked mutational signatures indicative of being critical mitigators of endogenous DNA modifications. Detailed analyses revealed mutational mechanistic insights, including how 8-oxo-dG elimination is sequence-context-specific while uracil clearance is sequence-context-independent. Mismatch repair (MMR) deficiency signatures are engendered by oxidative damage (C>A transversions), differential misincorporation by replicative polymerases (T>C and C>T transitions), and we propose a 'reverse template slippage' model for T>A transversions. Δ Δ and Δ signatures were similar to each other but distinct from Δ . Finally, we developed a classifier, MMRDetect, where application to 7,695 WGS cancers showed enhanced detection of MMR-deficient tumors, with implications for responsiveness to immunotherapies.

In 2007, the International Knockout Mouse Consortium (IKMC) made the ambitious promise to generate mutations in virtually every protein-coding gene of the mouse genome in a concerted worldwide action. Now, 5 years later, the IKMC members have developed high-throughput gene trapping and, in particular, gene-targeting pipelines and generated more than 17,400 mutant murine embryonic stem (ES) cell clones and more than 1,700 mutant mouse strains, most of them conditional. A common IKMC web portal (www.knockoutmouse.org) has been established, allowing easy access to this unparalleled biological resource. The IKMC materials considerably enhance functional gene annotation of the mammalian genome and will have a major impact on future biomedical research.

Mutational signatures are imprints of pathophysiological processes arising through tumorigenesis. Here, we generate isogenic CRISPR-Cas9 knockouts (Δ) of 43 genes in human induced pluripotent stem cells, culture them in the absence of added DNA damage, and perform whole-genome sequencing of 173 daughter subclones. ΔOGG1, ΔUNG, ΔEXO1, ΔRNF168, ΔMLH1, ΔMSH2, ΔMSH6, ΔPMS1, and ΔPMS2 produce marked mutational signatures indicative of being critical mitigators of endogenous DNA changes. Detailed analyses reveal that 8-oxo-dG removal by different repair proteins is sequence-context-specific while uracil clearance is sequence-context-independent. Signatures of mismatch repair (MMR) deficiency show components of C>A transversions due to oxidative damage, T>C and C>T transitions due to differential misincorporation by replicative polymerases, and T>A transversions for which we propose a 'reverse template slippage' model. ΔMLH1, ΔMSH6, and ΔMSH2 signatures are similar to each other but distinct from ΔPMS2. We validate these gene-specificities in cells from patients with Constitutive Mismatch Repair Deficiency Syndrome. Based on these experimental insights, we develop a classifier, MMRDetect, for improved clinical detection of MMR-deficient tumors. Competing Interest Statement SNZ holds patents on clinical algorithms of mutational signatures and during the completion of this project, served advisory roles for Astra Zeneca, Artios Pharma Ltd and Scottish Genome Project.

The International Mouse Phenotyping Consortium reports the generation of new mouse mutant strains for over 5,000 genes from targeted embryonic stem cells on the C57BL/6N genetic background. This includes 2,850 null alleles for which no equivalent mutant mouse line exists, 2,987 novel conditional-ready alleles, and 4,433 novel reporter alleles. This nearly triples the number of genes with reporter alleles and almost doubles the number of conditional alleles available to the scientific community. When combined with more than 30 years of community effort, the total mutant allele mouse resource covers more than half of the genome. The extensively validated collection is archived and distributed through public repositories, facilitating availability to the worldwide biomedical research community, and expanding our understanding of gene function and human disease.

Effective grazing management in Australia’s semi-arid rangelands requires monitoring landscape conditions and identifying sustainable and productive practice through understanding the interactions of environmental factors and management of soil health. Challenges include extreme rainfall variability, intensifying drought, and inherently nutrient-poor soils. We investigated the impacts of grazing strategies on landscape function—specifically soil health—as the foundation for productive pastures, integrating the heterogenous nature of grass tussocks and the interspaces that naturally exist in between them. At Wambiana—a long-term research site in north-eastern Australia—we studied two soil types, two stocking rates (high, moderate), and resting land from grazing during wet seasons (rotational spelling). Rotational spelling had the highest biocrust (living soil cover), in interspaces and under grass tussocks. Biocrusts were dominated by cyanobacteria that binds soil particles, reduces erosion, sequesters carbon, fixes nitrogen, and improves soil fertility. Rotational spelling with a moderate stocking rate emerged as best practice at these sites, with adjustment of stocking rates in line with rainfall and soil type recommended. In drought-prone environments, monitoring the presence and integrity of biocrusts connects landscape function and soil health. Biocrusts that protect and enrich the soil will support long-term ecosystem integrity and economic profitability of cattle production in rangelands.

Abstract Background Understanding the attack rate of influenza infection and the proportion who become ill by risk group is key to implementing prevention measures. While population-based studies of antihemagglutinin antibody responses have been described previously, studies examining both antihemagglutinin and antineuraminidase antibodies are lacking. Methods In 2015, we conducted a seroepidemiologic cohort study of individuals randomly selected from a population in New Zealand. We tested paired sera for hemagglutination inhibition (HAI) or neuraminidase inhibition (NAI) titers for seroconversion. We followed participants weekly and performed influenza polymerase chain reaction (PCR) for those reporting influenza-like illness (ILI). Results Influenza infection (either HAI or NAI seroconversion) was found in 321 (35% [95% confidence interval, 32%–38%]) of 911 unvaccinated participants, of whom 100 (31%) seroconverted to NAI alone. Young children and Pacific peoples experienced the highest influenza infection attack rates, but overall only a quarter of all infected reported influenza PCR–confirmed ILI, and one-quarter of these sought medical attention. Seroconversion to NAI alone was higher among children aged <5 years vs those aged ≥5 years (14% vs 4%; P < .001) and among those with influenza B vs A(H3N2) virus infections (7% vs 0.3%; P < .001). Conclusions Measurement of antineuraminidase antibodies in addition to antihemagglutinin antibodies may be important in capturing the true influenza infection rates. New Zealand’s seroepidemiological cohort study found that neuraminidase inhibition assay identified more influenza virus infections than hemagglutination inhibition assay. This result highlights the importance to measure serologically defined infections against not just hemagglutinin but also neuraminidase antigens in future seroepidemiologic cohort studies.