Reflective multi-immersion microscope objectives inspired by the Schmidt telescope

Imaging large, cleared samples requires microscope objectives that combine a large field of view (FOV) with a long working distance (WD) and a high numerical aperture (NA). Ideally, such objectives should be compatible with a wide range of immersion media, which is challenging to achieve with conventional lens-based objective designs. Here we introduce the multi-immersion 'Schmidt objective' consisting of a spherical mirror and an aspherical correction plate as a solution to this problem. We demonstrate that a multi-photon variant of the Schmidt objective is compatible with all homogeneous immersion media and achieves an NA of 1.08 at a refractive index of 1.56, 1.1-mm FOV and 11-mm WD. We highlight its versatility by imaging cleared samples in various media ranging from air and water to benzyl alcohol/benzyl benzoate, dibenzyl ether and ethyl cinnamate and by imaging of neuronal activity in larval zebrafish in vivo. In principle, the concept can be extended to any imaging modality, including wide-field, confocal and light-sheet microscopy.

Artificial intelligence takes center stage: exploring the capabilities and implications of ChatGPT and other AI-assisted technologies in scientific research and education

The emergence of large language models (LLMs) and assisted artificial intelligence (AI) technologies have revolutionized the way in which we interact with technology. A recent symposium at the Walter and Eliza Hall Institute explored the current practical applications of LLMs in medical research and canvassed the emerging ethical, legal and social implications for the use of AI-assisted technologies in the sciences. This paper provides an overview of the symposium's key themes and discussions delivered by diverse speakers, including early career researchers, group leaders, educators and policy-makers highlighting the opportunities and challenges that lie ahead for scientific researchers and educators as we continue to explore the potential of this cutting-edge and emerging technology.

SARS-CoV-2 mouse adaptation selects virulence mutations that cause TNF-driven age-dependent severe disease with human correlates

The diversity of COVID-19 disease in otherwise healthy people, from seemingly asymptomatic infection to severe life-threatening disease, is not clearly understood. We passaged a naturally occurring near-ancestral SARS-CoV-2 variant, capable of infecting wild-type mice, and identified viral genomic mutations coinciding with the acquisition of severe disease in young adult mice and lethality in aged animals. Transcriptomic analysis of lung tissues from mice with severe disease elucidated a host antiviral response dominated mainly by interferon and IL-6 pathway activation in young mice, while in aged animals, a fatal outcome was dominated by TNF and TGF-β signaling. Congruent with our pathway analysis, we showed that young TNF-deficient mice had mild disease compared to controls and aged TNF-deficient animals were more likely to survive infection. Emerging clinical correlates of disease are consistent with our preclinical studies, and our model may provide value in defining aberrant host responses that are causative of severe COVID-19.

ahctf1 and kras mutations combine to amplify oncogenic stress and restrict liver overgrowth in a zebrafish model of hepatocellular carcinoma

The nucleoporin (NUP) ELYS, encoded by AHCTF1, is a large multifunctional protein with essential roles in nuclear pore assembly and mitosis. Using both larval and adult zebrafish models of hepatocellular carcinoma (HCC), in which the expression of an inducible mutant kras transgene (kras^G12V) drives hepatocyte-specific hyperplasia and liver enlargement, we show that reducing ahctf1 gene dosage by 50% markedly decreases liver volume, while non-hyperplastic tissues are unaffected. We demonstrate that in the context of cancer, ahctf1 heterozygosity impairs nuclear pore formation, mitotic spindle assembly, and chromosome segregation, leading to DNA damage and activation of a Tp53-dependent transcriptional programme that induces cell death and cell cycle arrest. Heterozygous expression of both ahctf1 and ranbp2 (encoding a second nucleoporin), or treatment of heterozygous ahctf1 larvae with the nucleocytoplasmic transport inhibitor, Selinexor, completely blocks kras^G12V-driven hepatocyte hyperplasia. Gene expression analysis of patient samples in the liver hepatocellular carcinoma (LIHC) dataset in The Cancer Genome Atlas shows that high expression of one or more of the transcripts encoding the 10 components of the NUP107-160 subcomplex, which includes AHCTF1, is positively correlated with worse overall survival. These results provide a strong and feasible rationale for the development of novel cancer therapeutics that target ELYS function and suggest potential avenues for effective combinatorial treatments.

Epigenetic modulators of B cell fate identified through coupled phenotype-transcriptome analysis

High-throughput methodologies are the cornerstone of screening approaches to identify novel compounds that regulate immune cell function. To identify novel targeted therapeutics to treat immune disorders and haematological malignancies, there is a need to integrate functional cellular information with the molecular mechanisms that regulate changes in immune cell phenotype. We facilitate this goal by combining quantitative methods for dissecting complex simultaneous cell phenotypic effects with genomic analysis. This combination strategy we term Multiplexed Analysis of Cells sequencing (MAC-seq), a modified version of Digital RNA with perturbation of Genes (DRUGseq). We applied MAC-seq to screen compounds that target the epigenetic machinery of B cells and assess altered humoral immunity by measuring changes in proliferation, survival, differentiation and transcription. This approach revealed that polycomb repressive complex 2 (PRC2) inhibitors promote antibody secreting cell (ASC) differentiation in both murine and human B cells in vitro. This is further validated using T cell-dependent immunization in mice. Functional dissection of downstream effectors of PRC2 using arrayed CRISPR screening uncovered novel regulators of B cell differentiation, including Mybl1, Myof, Gas7 and Atoh8. Together, our findings demonstrate that integrated phenotype-transcriptome analyses can be effectively combined with drug screening approaches to uncover the molecular circuitry that drives lymphocyte fate decisions.

Therapeutic inhibition of the SRC-kinase HCK facilitates T cell tumor infiltration and improves response to immunotherapy

Although immunotherapy has revolutionized cancer treatment, many immunogenic tumors remain refractory to treatment. This can be largely attributed to an immunologically "cold" tumor microenvironment characterized by an accumulation of immunosuppressive myeloid cells and exclusion of activated T cells. Here, we demonstrate that genetic ablation or therapeutic inhibition of the myeloid-specific hematopoietic cell kinase (HCK) enables activity of antagonistic anti-programmed cell death protein 1 (anti-PD1), anti-CTLA4, or agonistic anti-CD40 immunotherapies in otherwise refractory tumors and augments response in treatment-susceptible tumors. Mechanistically, HCK ablation reprograms tumor-associated macrophages and dendritic cells toward an inflammatory endotype and enhances CD8⁺ T cell recruitment and activation when combined with immunotherapy in mice. Meanwhile, therapeutic inhibition of HCK in humanized mice engrafted with patient-derived xenografts counteracts tumor immunosuppression, improves T cell recruitment, and impairs tumor growth. Collectively, our results suggest that therapeutic targeting of HCK activity enhances response to immunotherapy by simultaneously stimulating immune cell activation and inhibiting the immunosuppressive tumor microenvironment.

Langerhans cells are an essential cellular intermediary in chronic dermatitis

SHARPIN regulates signaling from the tumor necrosis factor (TNF) superfamily and pattern-recognition receptors. An inactivating Sharpin mutation in mice causes TNF-mediated dermatitis. Blocking cell death prevents the phenotype, implicating TNFR1-induced cell death in causing the skin disease. However, the source of TNF that drives dermatitis is unknown. Immune cells are a potent source of TNF in vivo and feature prominently in the skin pathology; however, T cells, B cells, and eosinophils are dispensable for the skin phenotype. We use targeted in vivo cell ablation, immune profiling, and extensive imaging to identify immune populations driving dermatitis. We find that systemic depletion of Langerin⁺ cells significantly reduces disease severity. This is enhanced in mice that lack Langerhans cells (LCs) from soon after birth. Reconstitution of LC-depleted Sharpin mutant mice with TNF-deficient LCs prevents dermatitis, implicating LCs as a potential cellular source of pathogenic TNF and highlighting a T cell-independent role in driving skin inflammation.

Analyzing Vessel Regression and Endothelial Apoptosis as a Component of Angiogenic Vessel Remodeling

Angiogenic vessel remodeling is a critical step in establishing a hierarchical vessel network. Vessel networks rapidly expand through angiogenesis in response to pro-angiogenic factors. This leads to an initially dense vessel network that requires selective regression of vessel branches to establish a hierarchical conduit for blood flow, a process known as pruning. This involves migration of endothelial cells from low-flow vessels to adjacent high-flow vessels and generally occurs independently of cell death. Vessels may also regress in response to other stimuli, including reduced metabolic demand, redundancy, and pathological stimuli. In these contexts, widespread vessel regression typically occurs and involves loss of endothelial cells by apoptotic cell death. Thus, vessel remodeling occurs via both apoptosis independent and dependent vessel regression. In this chapter, we outline a semi-automated method for quantifying vessel regression using the neonatal model of angiogenesis. We further provide instruction on analyzing endothelial apoptosis in this model.

The histone acetyltransferase HBO1 promotes efficient tip cell sprouting during angiogenesis

Blood vessel growth and remodelling are essential during embryonic development and disease pathogenesis. The diversity of endothelial cells (ECs) is transcriptionally evident and ECs undergo dynamic changes in gene expression during vessel growth and remodelling. Here, we investigated the role of the histone acetyltransferase HBO1 (KAT7), which is important for activating genes during development and for histone H3 lysine 14 acetylation (H3K14ac). Loss of HBO1 and H3K14ac impaired developmental sprouting angiogenesis and reduced pathological EC overgrowth in the retinal endothelium. Single-cell RNA sequencing of retinal ECs revealed an increased abundance of tip cells in Hbo1-deficient retinas, which led to EC overcrowding in the retinal sprouting front and prevented efficient tip cell migration. We found that H3K14ac was highly abundant in the endothelial genome in both intra- and intergenic regions, suggesting that HBO1 acts as a genome organiser that promotes efficient tip cell behaviour necessary for sprouting angiogenesis. This article has an associated 'The people behind the papers' interview.

Real-time multi-angle projection imaging of biological dynamics

We introduce a cost-effective and easily implementable scan unit that converts any camera-based microscope with optical sectioning capability into a multi-angle projection imaging system. Projection imaging reduces data overhead and accelerates imaging by a factor of >100, while also allowing users to readily view biological phenomena of interest from multiple perspectives on the fly. By rapidly interrogating the sample from just two perspectives, our method also enables real-time stereoscopic imaging and three-dimensional particle localization. We demonstrate projection imaging with spinning disk confocal, lattice light-sheet, multidirectional illumination light-sheet and oblique plane microscopes on specimens that range from organelles in single cells to the vasculature of a zebrafish embryo. Furthermore, we leverage our projection method to rapidly image cancer cell morphodynamics and calcium signaling in cultured neurons at rates up to 119 Hz as well as to simultaneously image orthogonal views of a beating embryonic zebrafish heart.

Blocking endothelial apoptosis revascularizes the retina in a model of ischemic retinopathy

Aberrant, neovascular retinal blood vessel growth is a vision-threatening complication in ischemic retinal diseases. It is driven by retinal hypoxia frequently caused by capillary nonperfusion and endothelial cell (EC) loss. We investigated the role of EC apoptosis in this process using a mouse model of ischemic retinopathy, in which vessel closure and EC apoptosis cause capillary regression and retinal ischemia followed by neovascularization. Protecting ECs from apoptosis in this model did not prevent capillary closure or retinal ischemia. Nonetheless, it prevented the clearance of ECs from closed capillaries, delaying vessel regression and allowing ECs to persist in clusters throughout the ischemic zone. In response to hypoxia, these preserved ECs underwent a vessel sprouting response and rapidly reassembled into a functional vascular network. This alleviated retinal hypoxia, preventing subsequent pathogenic neovascularization. Vessel reassembly was not limited by VEGFA neutralization, suggesting it was not dependent on the excess VEGFA produced by the ischemic retina. Neutralization of ANG2 did not prevent vessel reassembly, but did impair subsequent angiogenic expansion of the reassembled vessels. Blockade of EC apoptosis may promote ischemic tissue revascularization by preserving ECs within ischemic tissue that retain the capacity to reassemble a functional network and rapidly restore blood supply.

BCL-XL exerts a protective role against anemia caused by radiation-induced kidney damage

Studies of gene-targeted mice identified the roles of the different pro-survival BCL-2 proteins during embryogenesis. However, little is known about the role(s) of these proteins in adults in response to cytotoxic stresses, such as treatment with anti-cancer agents. We investigated the role of BCL-XL in adult mice using a strategy where prior bone marrow transplantation allowed for loss of BCL-XL exclusively in non-hematopoietic tissues to prevent anemia caused by BCL-XL deficiency in erythroid cells. Unexpectedly, the combination of total body γ-irradiation (TBI) and genetic loss of Bcl-x caused secondary anemia resulting from chronic renal failure due to apoptosis of renal tubular epithelium with secondary obstructive nephropathy. These findings identify a critical protective role of BCL-XL in the adult kidney and inform on the use of BCL-XL inhibitors in combination with DNA damage-inducing drugs for cancer therapy. Encouragingly, the combination of DNA damage-inducing anti-cancer therapy plus a BCL-XL inhibitor could be tolerated in mice, at least when applied sequentially.

Downregulation of the GHRH/GH/IGF1 axis in a mouse model of Börjeson-Forssman-Lehman syndrome

Börjeson-Forssman-Lehmann syndrome (BFLS) is an intellectual disability and endocrine disorder caused by plant homeodomain finger 6 (PHF6) mutations. Individuals with BFLS present with short stature. We report a mouse model of BFLS, in which deletion of Phf6 causes a proportional reduction in body size compared with control mice. Growth hormone (GH) levels were reduced in the absence of PHF6. Phf6 ^{- /Y} animals displayed a reduction in the expression of the genes encoding GH-releasing hormone (GHRH) in the brain, GH in the pituitary gland and insulin-like growth factor 1 (IGF1) in the liver. Phf6 deletion specifically in the nervous system caused a proportional growth defect, indicating a neuroendocrine contribution to the phenotype. Loss of suppressor of cytokine signaling 2 (SOCS2), a negative regulator of growth hormone signaling partially rescued body size, supporting a reversible deficiency in GH signaling. These results demonstrate that PHF6 regulates the GHRH/GH/IGF1 axis.

Consequences of Zmat3 loss in c-MYC- and mutant KRAS-driven tumorigenesis

TP53 is a critical tumor suppressor that is mutated in approximately 50% of human cancers. Unveiling the downstream target genes of TP53 that fulfill its tumor suppressor function is an area of intense investigation. Zmat3 (also known as Wig-1 or PAG608) is one such downstream target of p53, whose loss in hemopoietic stem cells lacking the apoptosis and cell cycle regulators, Puma and p21, respectively, promotes the development of leukemia. The function of Zmat3 in tumorigenesis however remains unclear. Here, to investigate which oncogenic drivers co-operate with Zmat3 loss to promote neoplastic transformation, we utilized Zmat3 knockout mice in models of c-MYC-driven lymphomagenesis and Kras^G12D-driven lung adenocarcinoma development. Interestingly, unlike loss of p53, Zmat3 germline loss had little impact on the rate of tumor development or severity of malignant disease upon either the c-MYC or Kras^G12D oncogenic activation. Furthermore, loss of Zmat3 failed to rescue Kras^G12D primary lung tumor cells from oncogene-induced senescence. Taken together, we conclude that in the context of c-MYC-driven lymphomagenesis or mutant Kras^G12D-driven lung adenocarcinoma development, additional co-occurring mutations are required to resolve Zmat3 tumor suppressive activity.

Author Correction: The neuropeptide VIP confers anticipatory mucosal immunity by regulating ILC3 activity

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Inhibition of the SRC Kinase HCK Impairs STAT3-Dependent Gastric Tumor Growth in Mice

Persistent activation of the latent transcription factor STAT3 is observed in gastric tumor epithelial and immune cells and is associated with a poor patient prognosis. Although targeting STAT3-activating upstream kinases offers therapeutically viable targets with limited specificity, direct inhibition of STAT3 remains challenging. Here we provide functional evidence that myeloid-specific hematopoietic cell kinase (HCK) activity can drive STAT3-dependent epithelial tumor growth in mice and is associated with alternative macrophage activation alongside matrix remodeling and tumor cell invasion. Accordingly, genetic reduction of HCK expression in bone marrow-derived cells or systemic pharmacologic inhibition of HCK activity suppresses alternative macrophage polarization and epithelial STAT3 activation, and impairs tumor growth. These data validate HCK as a molecular target for the treatment of human solid tumors harboring excessive STAT3 activity.

Subtle Changes in the Levels of BCL-2 Proteins Cause Severe Craniofacial Abnormalities

Apoptotic cell death removes unwanted cells and is regulated by interactions between pro-survival and pro-apoptotic members of the BCL-2 protein family. The regulation of apoptosis is thought to be crucial for normal embryonic development. Accordingly, complete loss of pro-survival MCL-1 or BCL-XL (BCL2L1) causes embryonic lethality. However, it is not known whether minor reductions in pro-survival proteins could cause developmental abnormalities. We explored the rate-limiting roles of MCL-1 and BCL-XL in development and show that combined loss of single alleles of Mcl-1 and Bcl-x causes neonatal lethality. Mcl-1^+/-;Bcl-x^+/- mice display craniofacial anomalies, but additional loss of a single allele of pro-apoptotic Bim (Bcl2l11) restores normal development. These findings demonstrate that the control of cell survival during embryogenesis is finely balanced and suggest that some human craniofacial defects, for which causes are currently unknown, may be due to subtle imbalances between pro-survival and pro-apoptotic BCL-2 family members.

Characterisation of mice lacking the inflammatory caspases-1/11/12 reveals no contribution of caspase-12 to cell death and sepsis

Caspases exert critical functions in diverse cell death pathways, including apoptosis and pyroptosis, but some caspases also have roles in the processing of cytokines into their functional forms during inflammation. The roles of many caspases have been unravelled by the generation of knockout mice, but still very little is known about the overlapping functions of caspases as only a few studies report on double or triple caspase knockout mice. For example, the functions of caspase-12 in cell death and inflammation, on its own or overlapping with the functions of caspase-1 and caspase-11, are only poorly understood. Therefore, we generated a novel mutant mouse strain lacking all three inflammatory caspases, caspases-1, -11 and -12. Analysis under steady state conditions showed no obvious differences between caspase-1/11/12-/- and wildtype (WT) mice. Since caspases-1 and -11 are involved in endotoxic shock, we analysed the response of caspase-1/11/12-/- mice to high-dose LPS injection. Interestingly, we could not detect any differences in responses between caspase-1/11/12-/- mice vs. caspase-1/11 double knockout mice. Furthermore, cell lines generated from caspase-1/11/12-/- mice showed no differences in their apoptotic or necroptotic responses to a diverse set of cytotoxic drugs in vitro when compared to WT cells. Importantly, these drugs also included ER stress-inducing agents, such as thapsigargin and tunicamycin, a form of cell death for which a critical pro-apoptotic function of caspase-12 has previously been reported. Additionally, we found no differences between caspase-1/11/12-/- and WT mice in their in vivo responses to the ER stress-inducing agent, tunicamycin. Collectively, these findings reveal that caspase-12 does not have readily recognisable overlapping roles with caspases-1 and -11 in the inflammatory response induced by LPS and in necroptosis and apoptosis induced by diverse cytotoxic agents, including the ones that elicit ER stress.

Intraclonal Plasticity in Mammary Tumors Revealed through Large-Scale Single-Cell Resolution 3D Imaging

Breast tumors are inherently heterogeneous, but the evolving cellular organization through neoplastic progression is poorly understood. Here we report a rapid, large-scale single-cell resolution 3D imaging protocol based on a one-step clearing agent that allows visualization of normal tissue architecture and entire tumors at cellular resolution. Imaging of multicolor lineage-tracing models of breast cancer targeted to either basal or luminal progenitor cells revealed profound clonal restriction during progression. Expression profiling of clones arising in Pten/Trp53-deficient tumors identified distinct molecular signatures. Strikingly, most clones harbored cells that had undergone an epithelial-to-mesenchymal transition, indicating widespread, inherent plasticity. Hence, an integrative pipeline that combines lineage tracing, 3D imaging, and clonal RNA sequencing technologies offers a comprehensive path for studying mechanisms underlying heterogeneity in whole tumors.

Traditional methods for managing illness in newborns and infants in an Arab society

AIM

This study explored self-management practices in relation to traditional methods for managing illness in newborns and infants and the implications of these practices on infant health.

BACKGROUND

Self-medication with folk remedies is believed to have short- and long-term impacts on well-being. Little is known about how mothers in Arab societies used their traditional beliefs and practices in self-managing their newborns' and infants' health.

METHODS

Data were collected from five focus groups using open-ended questions with 37 mothers. Participants were selected using snowball sampling and were recruited from four different cities in Jordan between June 2016 and August 2016.

ETHICAL APPROVAL

All identifying information regarding the study participants has been omitted, and this study was approved by the Academic Research Committee at the University of Jordan.

FINDINGS

Mothers were more willing to try herbal remedies, traditional massage and certain foods to self-manage their infants' health. Folk remedies were not restricted to traditions handed down through generations, but included a representation of newly emerged trends towards 'safety' or 'nature'.

CONCLUSIONS

While the use of folk remedies have been handed down generations as customs, today, virtual support groups and social media provide modern resources for folk remedies' promotion in care and self-management.

IMPLICATIONS FOR NURSING AND HEALTH POLICY

Nursing and health policymakers can use our findings for planning and developing strategies and health policies that increase public awareness about adverse health effects associated with herbal remedies. Such strategies are likely to be facilitated through partnerships between nursing and midwifery education institutions, antenatal clinics and social media in the region.

Embryogenesis and Adult Life in the Absence of Intrinsic Apoptosis Effectors BAX, BAK, and BOK

Intrinsic apoptosis, reliant on BAX and BAK, has been postulated to be fundamental for morphogenesis, but its precise contribution to this process has not been fully explored in mammals. Our structural analysis of BOK suggests close resemblance to BAX and BAK structures. Notably, Bok^-/-Bax^-/-Bak^-/- animals exhibited more severe defects and died earlier than Bax^-/-Bak^-/- mice, implying that BOK has overlapping roles with BAX and BAK during developmental cell death. By analyzing Bok^-/-Bax^-/-Bak^-/- triple-knockout mice whose cells are incapable of undergoing intrinsic apoptosis, we identified tissues that formed well without this process. We provide evidence that necroptosis, pyroptosis, or autophagy does not substantially substitute for the loss of apoptosis. Albeit very rare, unexpected attainment of adult Bok^-/-Bax^-/-Bak^-/- mice suggests that morphogenesis can proceed entirely without apoptosis mediated by these proteins and possibly without cell death in general.

Constitutive overexpression of TNF in BPSM1 mice causes iBALT and bone marrow nodular lymphocytic hyperplasia

BPSM1 (Bone phenotype spontaneous mutant 1) mice develop severe polyarthritis and heart valve disease as a result of a spontaneous mutation in the Tnf gene. In these mice, the insertion of a retrotransposon in the 3' untranslated region of Tnf causes a large increase in the expression of the cytokine. We have found that these mice also develop inducible bronchus-associated lymphoid tissue (iBALT), as well as nodular lymphoid hyperplasia (NLH) in the bone marrow. Loss of TNFR1 prevents the development of both types of follicles, but deficiency of TNFR1 in the hematopoietic compartment only prevents the iBALT and not the NLH phenotype. We show that the development of arthritis and heart valve disease does not depend on the presence of the tertiary lymphoid tissues. Interestingly, while loss of IL-17 or IL-23 limits iBALT and NLH development to some extent, it has no effect on polyarthritis or heart valve disease in BPSM1 mice.

Mutant TRP53 exerts a target gene-selective dominant-negative effect to drive tumor development

Here, Aubrey et al. researched how mutant TRP53 drives tumor development. Their findings demonstrate a strong functional synergy between deregulated expression of c-MYC and the hot spot mutant TRP53 proteins that distinguishes them from the less frequently occurring TRP53 mutants and that mutant TRP53 drives tumorigenesis primarily through dominant-negative effects.

Mutations in Trp53, prevalent in human cancer, are reported to drive tumorigenesis through dominant-negative effects (DNEs) over wild-type TRP53 function as well as neomorphic gain-of-function (GOF) activity. We show that five TRP53 mutants do not accelerate lymphomagenesis on a TRP53-deficient background but strongly synergize with c-MYC overexpression in a manner that distinguishes the hot spot Trp53 mutations. RNA sequencing revealed that the mutant TRP53 DNE does not globally repress wild-type TRP53 function but disproportionately impacts a subset of wild-type TRP53 target genes. Accordingly, TRP53 mutant proteins impair pathways for DNA repair, proliferation, and metabolism in premalignant cells. This reveals that, in our studies of lymphomagenesis, mutant TRP53 drives tumorigenesis primarily through the DNE, which modulates wild-type TRP53 function in a manner advantageous for neoplastic transformation.

Converse Smith-Martin cell cycle kinetics by transformed B lymphocytes

Recent studies using direct live cell imaging have reported that individual B lymphocytes have correlated transit times between their G1 and S/G2/M phases. This finding is in contradiction with the influential model of Smith and Martin that assumed the bulk of the total cell cycle time variation arises in the G1 phase of the cell cycle with little contributed by the S/G2/M phase. Here we extend these studies to examine the relation between cell cycle phase lengths in two B lymphoma cell lines. We report that transformed B lymphoma cells undergo a short G1 period that displays little correlation with the time taken for the subsequent S/G2/M phase. Consequently, the bulk of the variation noted for total division times within a population is found in the S/G2/M phases and not the G1 phase. Models that reverse the expected source of variation and assume a single deterministic time in G1 followed by a lag + exponential distribution for S/G2/M fit the data well. These models can be improved further by adopting two sequential distributions or by using the stretched lognormal model developed for primary lymphocytes. We propose that shortening of G1 transit times and uncoupling from other cell cycle phases may be a hallmark of lymphocyte transformation that could serve as an observable phenotypic marker of cancer evolution.

Quantification of Extracellular Double-stranded RNA Uptake and Subcellular Localization Using Flow Cytometry and Confocal Microscopy

Double-stranded RNA is a potent pathogen-associated molecular pattern (PAMP) produced as a by-product of viral replication and a well-known hallmark of viral infection. Viral dsRNAs can be released from infected cells into the extracellular space and internalized by neighboring cells via endocytosis. Mammals possess multiple pattern recognition receptors (PRRs) capable of detecting viral dsRNAs such as endosomal toll-like receptor 3 (TLR3) and cytosolic RIG-I-like receptors (RLRs) which lead to the production of type I interferons (IFNs). Thus, intracellular localization of viral dsRNA can provide insight into the downstream signaling pathways leading to innate immune activation. Here, we describe a quantitative method for measuring extracellular dsRNA uptake and visualizing subcellular localization of internalized dsRNA via flow cytometry and confocal microscopy respectively.

MACROD2 Haploinsufficiency Impairs Catalytic Activity of PARP1 and Promotes Chromosome Instability and Growth of Intestinal Tumors

ADP-ribosylation is an important posttranslational protein modification that regulates diverse biological processes, controlled by dedicated transferases and hydrolases. Here, we show that frequent deletions (∼30%) of the MACROD2 mono-ADP-ribosylhydrolase locus in human colorectal cancer cause impaired PARP1 transferase activity in a gene dosage-dependent manner. MACROD2 haploinsufficiency alters DNA repair and sensitivity to DNA damage and results in chromosome instability. Heterozygous and homozygous depletion of Macrod2 enhances intestinal tumorigenesis in Apc^Min/+ mice and the growth of human colorectal cancer xenografts. MACROD2 deletion in sporadic colorectal cancer is associated with the extent of chromosome instability, independent of clinical parameters and other known genetic drivers. We conclude that MACROD2 acts as a haploinsufficient tumor suppressor, with loss of function promoting chromosome instability, thereby driving cancer evolution.Significance: Chromosome instability (CIN) is a hallmark of cancer. We identify MACROD2 deletion as a cause of CIN in human colorectal cancer. MACROD2 loss causes repression of PARP1 activity, impairing DNA repair. MACROD2 haploinsufficiency promotes CIN and intestinal tumor growth. Our results reveal MACROD2 as a major caretaker tumor suppressor gene. Cancer Discov; 8(8); 988-1005. ©2018 AACR.See related commentary by Jin and Burkard, p. 921This article is highlighted in the In This Issue feature, p. 899.

SIDT2 Transports Extracellular dsRNA into the Cytoplasm for Innate Immune Recognition

Double-stranded RNA (dsRNA) is a common by-product of viral infections and acts as a potent trigger of antiviral immunity. In the nematode C. elegans, sid-1 encodes a dsRNA transporter that is highly conserved throughout animal evolution, but the physiological role of SID-1 and its orthologs remains unclear. Here, we show that the mammalian SID-1 ortholog, SIDT2, is required to transport internalized extracellular dsRNA from endocytic compartments into the cytoplasm for immune activation. Sidt2-deficient mice exposed to extracellular dsRNA, encephalomyocarditis virus (EMCV), and herpes simplex virus 1 (HSV-1) show impaired production of antiviral cytokines and-in the case of EMCV and HSV-1-reduced survival. Thus, SIDT2 has retained the dsRNA transport activity of its C. elegans ortholog, and this transport is important for antiviral immunity.

Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

The Daya Bay experiment has observed correlations between reactor core fuel evolution and changes in the reactor antineutrino flux and energy spectrum. Four antineutrino detectors in two experimental halls were used to identify 2.2 million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles for each of six 2.9 GW_{th} reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective ^{239}Pu fission fractions F_{239} from 0.25 to 0.35, Daya Bay measures an average IBD yield σ[over ¯]_{f} of (5.90±0.13)×10^{-43}  cm^{2}/fission and a fuel-dependent variation in the IBD yield, dσ_{f}/dF_{239}, of (-1.86±0.18)×10^{-43}  cm^{2}/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the ^{239}Pu fission fraction at 10 standard deviations. The variation in IBD yield is found to be energy dependent, rejecting the hypothesis of a constant antineutrino energy spectrum at 5.1 standard deviations. While measurements of the evolution in the IBD spectrum show general agreement with predictions from recent reactor models, the measured evolution in total IBD yield disagrees with recent predictions at 3.1σ. This discrepancy indicates that an overall deficit in the measured flux with respect to predictions does not result from equal fractional deficits from the primary fission isotopes ^{235}U, ^{239}Pu, ^{238}U, and ^{241}Pu. Based on measured IBD yield variations, yields of (6.17±0.17) and (4.27±0.26)×10^{-43}  cm^{2}/fission have been determined for the two dominant fission parent isotopes ^{235}U and ^{239}Pu. A 7.8% discrepancy between the observed and predicted ^{235}U yields suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.

Inhibition of Hematopoietic Cell Kinase Activity Suppresses Myeloid Cell-Mediated Colon Cancer Progression

Aberrant activation of the SRC family kinase hematopoietic cell kinase (HCK) triggers hematological malignancies as a tumor cell-intrinsic oncogene. Here we find that high HCK levels correlate with reduced survival of colorectal cancer patients. Likewise, increased Hck activity in mice promotes the growth of endogenous colonic malignancies and of human colorectal cancer cell xenografts. Furthermore, tumor-associated macrophages of the corresponding tumors show a pronounced alternatively activated endotype, which occurs independently of mature lymphocytes or of Stat6-dependent Th2 cytokine signaling. Accordingly, pharmacological inhibition or genetic reduction of Hck activity suppresses alternative activation of tumor-associated macrophages and the growth of colon cancer xenografts. Thus, Hck may serve as a promising therapeutic target for solid malignancies.

Plasmodium falciparum ligand binding to erythrocytes induce alterations in deformability essential for invasion

The most lethal form of malaria in humans is caused by Plasmodium falciparum. These parasites invade erythrocytes, a complex process involving multiple ligand-receptor interactions. The parasite makes initial contact with the erythrocyte followed by dramatic deformations linked to the function of the Erythrocyte binding antigen family and P. falciparum reticulocyte binding-like families. We show EBA-175 mediates substantial changes in the deformability of erythrocytes by binding to glycophorin A and activating a phosphorylation cascade that includes erythrocyte cytoskeletal proteins resulting in changes in the viscoelastic properties of the host cell. TRPM7 kinase inhibitors FTY720 and waixenicin A block the changes in the deformability of erythrocytes and inhibit merozoite invasion by directly inhibiting the phosphorylation cascade. Therefore, binding of P. falciparum parasites to the erythrocyte directly activate a signaling pathway through a phosphorylation cascade and this alters the viscoelastic properties of the host membrane conditioning it for successful invasion.

Abstract S2-04: RANK ligand as a target for breast cancer prevention in BRCA1 mutation carriers

Background: BRCA1 mutation carriers commonly undergo prophylactic mastectomy to reduce their risk of breast cancer. The precise role of chemoprevention with tamoxifen, which reduces the incidence of ER-positive breast cancer in the general population, is uncertain for BRCA1 mutation carriers, where uptake has been modest. The identification of an effective and acceptable prevention therapy therefore remains a 'holy grail' for the field. Precancerous BRCA1mut/+ tissue harbors an aberrant population of luminal progenitor cells and deregulated progesterone signaling has been implicated in BRCA1-associated oncogenesis. Since Receptor Activator of Nuclear Factor-kappa B ligand (RANKL) is a key paracrine effector of progesterone signaling, and RANKL and its receptor RANK contribute to mammary tumorigenesis, we investigated a role for this pathway in the preneoplastic phase of BRCA1 mutation carriers.

Methods: We explored a role for the RANK/RANKL pathway during the preneoplastic phase in freshly isolated (histologically normal) patient specimens from BRCA1 mutation carriers using several approaches. RANK and RANKL expression in breast cancer was evaluated in formalin fixed paraffin embedded (FFPE) archival sections by IHC from the kConFab and the Amgen Tissue Banks. All samples were obtained with patient consent and relevant IRB approval. A role for RANKL inhibition in attenuating tumor onset was studied using the MMTV-cre/Brca1fl/fl/p53+/– mouse model that recapitulates human basal-like breast cancer.

Results: We identified two subsets of luminal progenitors (RANK+ and RANK–) in histologically normal tissue of BRCA1 mutation carriers and found that RANK+ cells are highly proliferative, exhibit grossly aberrant DNA repair and bear a molecular signature similar to that of basal-like breast cancer. Moreover, high levels of RANK expression prevailed in established BRCA1-associated tumors. These data suggest that RANK+ and not RANK– progenitors are a key target population in these women. Notably, inhibition of RANKL signaling by denosumab in 3D breast organoids derived from pre-neoplastic BRCA1mut/+ tissue attenuated progesterone-induced proliferation. Furthermore, inhibition of RANKL with either the RANKL inhibitor OPG-Fc or a RANKL monoclonal antibody in a Brca1-deficient mouse model significantly curtailed mammary tumorigenesis, when compared to controls (p<0.001).

Conclusions: Together these findings identify a targetable pathway in a putative cell of origin population in BRCA1 mutation carriers and implicate RANKL blockade as a promising breast cancer prevention strategy.

Citation Format: Lindeman GJ, Nolan E, Vaillant F, Branstetter D, Pal B, Giner G, Whitehead L, Lok SW, Mann GB, kConFab Consortium, Rohrbach K, Huang L-Y, Soriano R, Smyth GK, Dougall WC, Visvader JE. RANK ligand as a target for breast cancer prevention in BRCA1 mutation carriers [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S2-04.

Analysis of Ca2+ mediated signaling regulating Toxoplasma infectivity reveals complex relationships between key molecules

Host cell invasion, exit and parasite dissemination is critical to the pathogenesis of apicomplexan parasites such as Toxoplasma gondii and Plasmodium spp. These processes are regulated by intracellular Ca²⁺ signaling although the temporal dynamics of Ca²⁺ fluxes and down-stream second messenger pathways are poorly understood. Here, we use a genetically encoded biosensor, GFP-Calmodulin-M13-6 (GCaMP6), to capture Ca²⁺ flux in live Toxoplasma and investigate the role of Ca²⁺ signaling in egress and motility. Our analysis determines how environmental cues and signal activation influence intracellular Ca²⁺ flux, allowing placement of effector molecules within this pathway. Importantly, we have identified key interrelationships between cGMP and Ca²⁺ signaling that are required for activation of egress and motility. Furthermore, we extend this analysis to show that the Ca²⁺ Dependent Protein Kinases-TgCDPK1 and TgCDPK3-play a role in signal quenching before egress. This work highlights the interrelationships of second messenger pathways of Toxoplasma in space and time, which is likely required for pathogenesis of all apicomplexan species.

Limits on Active to Sterile Neutrino Oscillations from Disappearance Searches in the MINOS, Daya Bay, and Bugey-3 Experiments

Searches for a light sterile neutrino have been performed independently by the MINOS and the Daya Bay experiments using the muon (anti)neutrino and electron antineutrino disappearance channels, respectively. In this Letter, results from both experiments are combined with those from the Bugey-3 reactor neutrino experiment to constrain oscillations into light sterile neutrinos. The three experiments are sensitive to complementary regions of parameter space, enabling the combined analysis to probe regions allowed by the Liquid Scintillator Neutrino Detector (LSND) and MiniBooNE experiments in a minimally extended four-neutrino flavor framework. Stringent limits on sin^{2}2θ_{μe} are set over 6 orders of magnitude in the sterile mass-squared splitting Δm_{41}^{2}. The sterile-neutrino mixing phase space allowed by the LSND and MiniBooNE experiments is excluded for Δm_{41}^{2}<0.8  eV^{2} at 95%  CL_{s}.

Improved Search for a Light Sterile Neutrino with the Full Configuration of the Daya Bay Experiment

This Letter reports an improved search for light sterile neutrino mixing in the electron antineutrino disappearance channel with the full configuration of the Daya Bay Reactor Neutrino Experiment. With an additional 404 days of data collected in eight antineutrino detectors, this search benefits from 3.6 times the statistics available to the previous publication, as well as from improvements in energy calibration and background reduction. A relative comparison of the rate and energy spectrum of reactor antineutrinos in the three experimental halls yields no evidence of sterile neutrino mixing in the 2×10^{-4}≲|Δm_{41}^{2}|≲0.3  eV^{2} mass range. The resulting limits on sin^{2}2θ_{14} are improved by approx imately a factor of 2 over previous results and constitute the most stringent constraints to date in the |Δm_{41}^{2}|≲0.2  eV^{2} region.

Search for Sterile Neutrinos Mixing with Muon Neutrinos in MINOS

We report results of a search for oscillations involving a light sterile neutrino over distances of 1.04 and 735 km in a ν_{μ}-dominated beam with a peak energy of 3 GeV. The data, from an exposure of 10.56×10^{20} protons on target, are analyzed using a phenomenological model with one sterile neutrino. We constrain the mixing parameters θ_{24} and Δm_{41}^{2} and set limits on parameters of the four-dimensional Pontecorvo-Maki-Nakagawa-Sakata matrix, |U_{μ4}|^{2} and |U_{τ4}|^{2}, under the assumption that mixing between ν_{e} and ν_{s} is negligible (|U_{e4}|^{2}=0). No evidence for ν_{μ}→ν_{s} transitions is found and we set a world-leading limit on θ_{24} for values of Δm_{41}^{2}≲1  eV^{2}.

Establishing routines to cope with the loneliness associated with widowhood: a narrative analysis

WHAT IS KNOWN ON THE SUBJECT?: Loneliness in older adults has been identified as an important public health issue in many countries. Widowhood is a time when many older people experience loneliness. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: Little is known about strategies that are effective in mitigating experiences of loneliness and this paper explores this with older people who have been through the process. The narratives of the older people in this study described a trajectory in which loneliness was experienced as both a loss of spouse and a loss of routines that enabled them to maintain connections with others. This trajectory moved onto the establishment of new routines that enabled connections to be developed. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: Loneliness is strongly associated with depression and anxiety in the elderly and mental health nurses should be encouraged to screen for loneliness when undertaking assessments. Interventions that facilitate the development of meaningful routines could be integrated into mental health nursing care of older people.

ABSTRACT

Background Loneliness in older people is a public health concern in many Western countries. While not necessarily a symptom of mental disorder, it is often associated with depression and anxiety. Widowhood is a transition period during which many older people experience acute loneliness but over time develops strategies to manage it. Little is known about effective strategies that older people have used to manage the experience. The strategies older people used to manage this was the focus of this paper. Aim The aim was to examine older widows' experiences of loneliness. Design The design of this study was a qualitative narrative analysis with thematic analysis and the participants were 40 older widow/widowers aged between 70 and 97 years. Findings The study found that the participants negotiated the experience of loneliness following widowhood from an acute phase of experiencing an absence and the associated loss of routine connection to the establishment of new routines that provided new connections and a new sense of identity as an individual rather than a couple. Conclusions It is important for mental health nurses to screen for loneliness and be able to facilitate interventions that may alleviate the experience of loneliness.

Apoptosis regulates endothelial cell number and capillary vessel diameter but not vessel regression during retinal angiogenesis

The growth of hierarchical blood vessel networks occurs by angiogenesis. During this process, new vessel growth is accompanied by the removal of redundant vessel segments by selective vessel regression ('pruning') and a reduction in endothelial cell (EC) density in order to establish an efficient, hierarchical network. EC apoptosis has long been recognised for its association with angiogenesis, but its contribution to this process has remained unclear. We generated mice in which EC apoptosis was blocked by tissue-specific deletion of the apoptosis effector proteins BAK and BAX. Using the retina as a model, we found that apoptosis made a minor contribution to the efficiency of capillary regression around arteries where apoptosis was most concentrated, but was otherwise dispensable for vessel pruning. Instead, apoptosis was necessary for the removal of non-perfused vessel segments and the reduction in EC density that occurs during vessel maturation. In the absence of apoptosis, increased EC density resulted in an increase in the diameter of capillaries, but not arteries or veins. Our findings show that apoptosis does not influence the number of vessels generated during angiogenesis. Rather it removes non-perfused vessel segments and regulates EC number during vessel maturation, which has vessel-specific consequences for vessel diameter.

RANK ligand as a potential target for breast cancer prevention in BRCA1-mutation carriers

Individuals who have mutations in the breast-cancer-susceptibility gene BRCA1 (hereafter referred to as BRCA1-mutation carriers) frequently undergo prophylactic mastectomy to minimize their risk of breast cancer. The identification of an effective prevention therapy therefore remains a 'holy grail' for the field. Precancerous BRCA1(mut/+) tissue harbors an aberrant population of luminal progenitor cells, and deregulated progesterone signaling has been implicated in BRCA1-associated oncogenesis. Coupled with the findings that tumor necrosis factor superfamily member 11 (TNFSF11; also known as RANKL) is a key paracrine effector of progesterone signaling and that RANKL and its receptor TNFRSF11A (also known as RANK) contribute to mammary tumorigenesis, we investigated a role for this pathway in the pre-neoplastic phase of BRCA1-mutation carriers. We identified two subsets of luminal progenitors (RANK(+) and RANK(-)) in histologically normal tissue of BRCA1-mutation carriers and showed that RANK(+) cells are highly proliferative, have grossly aberrant DNA repair and bear a molecular signature similar to that of basal-like breast cancer. These data suggest that RANK(+) and not RANK(-) progenitors are a key target population in these women. Inhibition of RANKL signaling by treatment with denosumab in three-dimensional breast organoids derived from pre-neoplastic BRCA1(mut/+) tissue attenuated progesterone-induced proliferation. Notably, proliferation was markedly reduced in breast biopsies from BRCA1-mutation carriers who were treated with denosumab. Furthermore, inhibition of RANKL in a Brca1-deficient mouse model substantially curtailed mammary tumorigenesis. Taken together, these findings identify a targetable pathway in a putative cell-of-origin population in BRCA1-mutation carriers and implicate RANKL blockade as a promising strategy in the prevention of breast cancer.

Essential role for a novel population of binucleated mammary epithelial cells in lactation

The mammary gland represents a unique tissue to study organogenesis as it predominantly develops in the post-natal animal and undergoes dramatic morphogenetic changes during puberty and the reproductive cycle. The physiological function of the mammary gland is to produce milk to sustain the newborn. Here we view the lactating gland through three-dimensional confocal imaging of intact tissue. We observed that the majority of secretory alveolar cells are binucleated. These cells first arise in very late pregnancy due to failure of cytokinesis and are larger than mononucleated cells. Augmented expression of Aurora kinase-A and Polo-like kinase-1 at the lactogenic switch likely mediates the formation of binucleated cells. Our findings demonstrate an important physiological role for polyploid mammary epithelial cells in lactation, and based on their presence in five different species, suggest that binucleated cells evolved to maximize milk production and promote the survival of offspring across all mammalian species.

Endothelial cell survival during angiogenesis requires the pro-survival protein MCL1

Angiogenesis is essential to match the size of blood vessel networks to the metabolic demands of growing tissues. While many genes and pathways necessary for regulating angiogenesis have been identified, those responsible for endothelial cell (EC) survival during angiogenesis remain largely unknown. We have investigated the in vivo role of myeloid cell leukemia 1 (MCL1), a pro-survival member of the BCL2 family, in EC survival during angiogenesis. EC-specific deletion of Mcl1 resulted in a dose-dependent increase in EC apoptosis in the angiogenic vasculature and a corresponding decline in vessel density. Our results suggest this apoptosis was independent of the BH3-only protein BIM. Despite the known link between apoptosis and blood vessel regression, this was not the cause of reduced vessel density observed in the absence of endothelial MCL1. Rather, the reduction in vessel density was linked to ectopic apoptosis in regions of the angiogenic vasculature where EC proliferation and new vessel growth occurs. We have therefore identified MCL1 as an essential survival factor for ECs that is required for blood vessel production during angiogenesis.

Abstract P3-11-05: RANK ligand is a target for breast cancer prevention in BRCA1 mutation carriers

Background: BRCA1 mutation carriers often undergo prophylactic mastectomy to minimize their risk of breast cancer. The value of targeting ovarian hormones to prevent breast tumorigenesis remains contentious and the identification of an effective and acceptable chemoprevention strategy remains a 'holy grail' for the field. Recently, luminal progenitor cells have been identified as the likely cell-of-origin for BRCA1-associated breast tumors1. In addition, deregulated progesterone signaling has been implicated as a potential mechanism underlying tumor development in Brca1-deficient mammary glands2, although its role in luminal progenitor activation in BRCA1 mutation carriers is unknown. RANKL (Receptor Activator of Nuclear Factor-kappa B Ligand) has been identified as a key paracrine effector of progesterone-induced mammary epithelial proliferation in both mouse and human tissue3-5. Notably, RANKL and its receptor RANK play a critical role in the development of breast cancer, with inhibition of RANKL resulting in attenuation of tumorigenesis in mouse models of hormone-driven mammary carcinogenesis6,7.

Methods: We explored a role for the RANK/RANKL pathway during the preneoplastic phase in freshly isolated, histologically normal specimens from BRCA1 mutation carriers using a combination of strategies. RANK and RANKL expression in breast cancer was also evaluated in formalin fixed paraffin embedded (FFPE) archival sections by IHC. All samples were obtained with relevant IRB approval. A role for RANKL inhibition in attenuating tumor onset was studied using models that recapitulate human basal-like cancer.

Results: A RANK+ subset of luminal progenitor cells was identified in histologically normal breast tissue from BRCA1-mutation carriers. The RANK+ luminal progenitors exhibited higher proliferative activity compared to RANK- progenitors. RNA profiling revealed a distinctive molecular signature, consistent with the RANK+ subset being a possible target for neoplastic transformation. In established BRCA1-associated breast tumors, a four-fold higher incidence of RANK expression was observed, compared to tumors from non-carriers. In ongoing work, histologically normal pre-neoplastic BRCA1mut/+ tissue is being studied using ex vivo breast organoid assays to determine whether RANKL inhibition can attenuate breast epithelial proliferation.

Conclusions: Our data raise the possibility that RANK signaling is implicated in the initiation of tumorigenesis in BRCA1 mutation carriers (and possibly other high risk women) and that RANKL is a promising chemoprevention target. The findings are of sufficient interest to have led to a clinical trial, BRCA-D (Registered as ACTRN12614000694617). A finalized abstract will be submitted in early September, during the Late-Breaking Abstract submission period.

References:

1. Lim et al Nature Med 2009: 15, 907-13.

2. Poole et al Science 2006: 314, 1467-70.

3. Asselin-Labat et al Nature 2010: 465, 798-802.

4. Joshi et al Nature 2010: 465, 803-7.

5. Tanos et al Sci Transl Med 2013: 5, 182ra55.

6. Schramek et al Nature 2010: 468, 98-102.

7. Gonzales-Suarez et al Nature 2010: 468, 103-7.

Citation Format: Lindeman GJ, Nolan E, Pal B, Vaillant F, Giner G, Whitehead L, Mann GB, Lok SW, Shackleton K, Kathleen Cuningham Foundation Consortium (kConFab), Smyth GK, Visvader JE. RANK ligand is a target for breast cancer prevention in BRCA1 mutation carriers. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-11-05.

Measurement of the Reactor Antineutrino Flux and Spectrum at Daya Bay

This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9 GWth nuclear reactors with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296 721 and 41 589 inverse β decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55±0.04) ×10(-18)  cm(2) GW(-1) day(-1) or (5.92±0.14) ×10(-43)  cm(2) fission(-1). This flux measurement is consistent with previous short-baseline reactor antineutrino experiments and is 0.946±0.022 (0.991±0.023) relative to the flux predicted with the Huber-Mueller (ILL-Vogel) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2σ over the full energy range with a local significance of up to ∼4σ between 4-6 MeV. A reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.

Localisation-based imaging of malarial antigens during erythrocyte entry reaffirms a role for AMA1 but not MTRAP in invasion

Microscopy-based localisation of proteins during malaria parasite (Plasmodium) invasion of the erythrocyte is widely used for tentative assignment of protein function. To date, however, imaging has been limited by the rarity of invasion events and the poor resolution available, given the micron size of the parasite, which leads to a lack of quantitative measures for definitive localisation. Here, using computational image analysis we have attempted to assign relative protein localisation during invasion using wide-field deconvolution microscopy. By incorporating three-dimensional information we present a detailed assessment of known parasite effectors predicted to function during entry but as yet untested or for which data are equivocal. Our method, termed longitudinal intensity profiling, resolves confusion surrounding the localisation of apical membrane antigen 1 (AMA1) at the merozoite–erythrocyte junction and predicts that the merozoite thrombospondin-related anonymous protein (MTRAP) is unlikely to play a direct role in the mechanics of entry, an observation supported with additional biochemical evidence. This approach sets a benchmark for imaging of complex micron-scale events and cautions against simplistic interpretations of small numbers of representative images for the assignment of protein function or prioritisation of candidates as therapeutic targets.

Highlighted Article: Here we develop a high-definition imaging approach to dissect and assign function to proteins involved in the rapid process of malaria parasite invasion of the human erythrocyte.