Regulation of Genomic Output and (Pluri)potency in Regeneration.

Regeneration is a remarkable phenomenon that has been the subject of awe and bafflement for hundreds of years. Although regeneration competence is found in highly divergent organisms throughout the animal kingdom, recent advances in tools used for molecular and genomic characterization have uncovered common genes, molecular mechanisms, and genomic features in regenerating animals. In this review we focus on what is known about how genome regulation modulates cellular potency during regeneration. We discuss this regulation in the context of complex tissue regeneration in animals, from Hydra to humans, with reference to ex vivo-cultured cell models of pluripotency when appropriate. We emphasize the importance of a detailed molecular understanding of both the mechanisms that regulate genomic output and the functional assays that assess the biological relevance of such molecular characterizations.

Planarians recruit piRNAs for mRNA turnover in adult stem cells.

PIWI proteins utilize small RNAs called piRNAs to silence transposable elements, thereby protecting germline integrity. In planarian flatworms, PIWI proteins are essential for regeneration, which requires adult stem cells termed neoblasts. Here, we characterize planarian piRNAs and examine the roles of PIWI proteins in neoblast biology. We find that the planarian PIWI proteins SMEDWI-2 and SMEDWI-3 cooperate to degrade active transposons via the ping-pong cycle. Unexpectedly, we discover that SMEDWI-3 plays an additional role in planarian mRNA surveillance. While SMEDWI-3 degrades numerous neoblast mRNAs in a homotypic ping-pong cycle, it is also guided to another subset of neoblast mRNAs by antisense piRNAs and binds these without degrading them. Mechanistically, the distinct activities of SMEDWI-3 are primarily dictated by the degree of complementarity between target mRNAs and antisense piRNAs. Thus, PIWI proteins enable planarians to repurpose piRNAs for potentially critical roles in neoblast mRNA turnover.

Eos Promotes TH2 Differentiation by Interacting with and Propagating the Activity of STAT5.

The Ikaros zinc-finger transcription factor Eos has largely been associated with sustaining the immunosuppressive functions of regulatory T cells. Paradoxically, Eos has more recently been implicated in promoting proinflammatory responses in the dysregulated setting of autoimmunity. However, the precise role of Eos in regulating the differentiation and function of effector CD4+ T cell subsets remains unclear. In this study, we find that Eos is a positive regulator of the differentiation of murine CD4+ TH2 cells, an effector population that has been implicated in both immunity against helminthic parasites and the induction of allergic asthma. Using murine in vitro TH2 polarization and an in vivo house dust mite asthma model, we find that EosKO T cells exhibit reduced expression of key TH2 transcription factors, effector cytokines, and cytokine receptors. Mechanistically, we find that the IL-2/STAT5 axis and its downstream TH2 gene targets are one of the most significantly downregulated pathways in Eos-deficient cells. Consistent with these observations, we find that Eos forms, to our knowledge, a novel complex with and supports the tyrosine phosphorylation of STAT5. Collectively, these data define a regulatory mechanism whereby Eos propagates STAT5 activity to facilitate TH2 cell differentiation.

DNA methylation machinery is involved in development and reproduction in the viviparous pea aphid (Acyrthosiphon pisum).

Epigenetic mechanisms, such as DNA methylation, have been proposed to mediate plastic responses in insects. The pea aphid (Acyrthosiphon pisum), like the majority of extant aphids, displays cyclical parthenogenesis - the ability of mothers to switch the reproductive mode of their offspring from reproducing parthenogenetically to sexually in response to environmental cues. The pea aphid genome encodes two paralogs of the de novo DNA methyltransferase gene, dnmt3a and dnmt3x. Here we show, using phylogenetic analysis, that this gene duplication event occurred at least 150 million years ago, likely after the divergence of the lineage leading to the Aphidomorpha (phylloxerans, adelgids and true aphids) from that leading to the scale insects (Coccomorpha) and that the two paralogs are maintained in the genomes of all aphids examined. We also show that the mRNA of both dnmt3 paralogs is maternally expressed in the viviparous aphid ovary. During development both paralogs are expressed in the germ cells of embryos beginning at stage 5 and persisting throughout development. Treatment with 5-azactyidine, a chemical that generally inhibits the DNA methylation machinery, leads to defects of oocytes and early-stage embryos and causes a proportion of later stage embryos to be born dead or die soon after birth. These phenotypes suggest a role for DNA methyltransferases in reproduction, consistent with that seen in other insects. Taking the vast evolutionary history of the dnmt3 paralogs, and the localisation of their mRNAs in the ovary, we suggest there is a role for dnmt3a and/or dnmt3x in early development, and a role for DNA methylation machinery in reproduction and development of the viviparous pea aphid.

Molecular characterization of a flatworm Girardia isolate from Guanajuato, Mexico.

Planarian flatworms are best known for their impressive regenerative capacity, yet this trait varies across species. In addition, planarians have other features that share morphology and function with the tissues of many other animals, including an outer mucociliary epithelium that drives planarian locomotion and is very similar to the epithelial linings of the human lung and oviduct. Planarians occupy a broad range of ecological habitats and are known to be sensitive to changes in their environment. Yet, despite their potential to provide valuable insight to many different fields, very few planarian species have been developed as laboratory models for mechanism-based research. Here we describe a previously undocumented planarian isolate, Girardia sp. (Guanajuato). After collecting this isolate from a freshwater habitat in central Mexico, we characterized it at the morphological, cellular, and molecular level. We show that Girardia sp. (Guanajuato) not only shares features with animals in the Girardia genus but also possesses traits that appear unique to this isolate. By thoroughly characterizing this new planarian isolate, our work facilitates future comparisons to other flatworms and further molecular dissection of the unique and physiologically-relevant traits observed in this Girardia sp. (Guanajuato) isolate.

Genomic Signatures of Recent Adaptation in a Wild Bumblebee.

Environmental changes threaten insect pollinators, creating risks for agriculture and ecosystem stability. Despite their importance, we know little about how wild insects respond to environmental pressures. To understand the genomic bases of adaptation in an ecologically important pollinator, we analyzed genomes of Bombus terrestris bumblebees collected across Great Britain. We reveal extensive genetic diversity within this population, and strong signatures of recent adaptation throughout the genome affecting key processes including neurobiology and wing development. We also discover unusual features of the genome, including a region containing 53 genes that lacks genetic diversity in many bee species, and a horizontal gene transfer from a Wolbachia bacteria. Overall, the genetic diversity we observe and how it is distributed throughout the genome and the population should support the resilience of this important pollinator species to ongoing and future selective pressures. Applying our approach to more species should help understand how they can differ in their adaptive potential, and to develop conservation strategies for those most at risk.

One genome, multiple phenotypes: decoding the evolution and mechanisms of environmentally induced developmental plasticity in insects.

Plasticity in developmental processes gives rise to remarkable environmentally induced phenotypes. Some of the most striking and well-studied examples of developmental plasticity are seen in insects. For example, beetle horn size responds to nutritional state, butterfly eyespots are enlarged in response to temperature and humidity, and environmental cues also give rise to the queen and worker castes of eusocial insects. These phenotypes arise from essentially identical genomes in response to an environmental cue during development. Developmental plasticity is taxonomically widespread, affects individual fitness, and may act as a rapid-response mechanism allowing individuals to adapt to changing environments. Despite the importance and prevalence of developmental plasticity, there remains scant mechanistic understanding of how it works or evolves. In this review, we use key examples to discuss what is known about developmental plasticity in insects and identify fundamental gaps in the current knowledge. We highlight the importance of working towards a fully integrated understanding of developmental plasticity in a diverse range of species. Furthermore, we advocate for the use of comparative studies in an evo-devo framework to address how developmental plasticity works and how it evolves.

Long-term safety of brazikumab in the open-label period of a randomized phase 2a study of patients with Crohn's disease.

BACKGROUND: Short-term efficacy and safety of brazikumab (MEDI2070), a human monoclonal antibody and anti-p19 subunit inhibitor of interleukin-23, was demonstrated in a phase 2a trial in patients with moderate-to-severe active Crohn's disease (CD). We report brazikumab long-term safety and tolerability from the open-label period of this phase 2a study. METHODS: Patients who completed the 12-week, double-blind induction period were eligible for inclusion in an open-label period where all patients received subcutaneous brazikumab (210 mg) every 4 weeks for 100 weeks. Patients had moderate-to-severe active CD and had failed or were intolerant to ≥ 1 anti-tumour necrosis factor alpha (TNFα) agent. Safety assessments included treatment-emergent adverse events (TEAEs); further assessments were pharmacokinetics and immunogenicity. RESULTS: Of the 104 patients who entered the open-label period, 57 (54.8%) continued to the end of the open-label period and 47 (45.2%) discontinued brazikumab. The most common reasons for discontinuation were lack of response (14.4%), patient decision (12.5%), and TEAEs (11.5%). In total, 44 (84.6%) in the group switching from placebo to brazikumab (placebo/brazikumab) and 43 (82.7%) in the group continuing brazikumab (brazikumab/brazikumab) experienced 1 or more TEAEs. Most TEAEs were mild-to-moderate in severity. Common TEAEs included nasopharyngitis and headache. Numbers of treatment-emergent serious adverse events (TESAEs) were similar between groups. Infections occurred in 40.4% of patients in the placebo/brazikumab group and 50% in the brazikumab/brazikumab group. There were 5 TESAEs of infection, none of which were opportunistic. No major adverse cardiac events, malignancies, or deaths were reported. CONCLUSIONS: Brazikumab was well tolerated with an acceptable safety profile over a 100-week period in patients with moderate-to-severe active CD who failed or were intolerant to 1 or more anti-TNFα agents. TRIAL REGISTRATION: NCT01714726; registered October 26, 2012.

Cathepsin L proteolytically processes histone H3 during mouse embryonic stem cell differentiation.

Chromatin undergoes developmentally-regulated structural and chemical changes as cells differentiate, which subsequently lead to differences in cellular function by altering patterns of gene expression. To gain insight into chromatin alterations that occur during mammalian differentiation, we turned to a mouse embryonic stem cell (ESC) model. Here we show that histone H3 is proteolytically cleaved at its N-terminus during ESC differentiation. We map the sites of H3 cleavage and identify Cathepsin L as a protease responsible for proteolytically processing the N-terminal H3 tail. In addition, our data suggest that H3 cleavage may be regulated by covalent modifications present on the histone tail itself. Our studies underscore the intriguing possibility that histone proteolysis, brought about by Cathepsin L and potentially other family members, plays a role in development and differentiation that was not previously recognized.

Development of a multiplex microsatellite marker set for the study of the solitary red mason bee, Osmia bicornis (Megachilidae).

BACKGROUND: Solitary bees, such as the red mason bee (Osmia bicornis), provide important ecosystem services including pollination. In the face of global declines of pollinator abundance, such haplodiploid Hymenopterans have a compounded extinction risk due to the potential for limited genetic diversity. In order to assess the genetic diversity of Osmia bicornis populations, we developed microsatellite markers and characterised them in two populations. METHODS AND RESULTS: Microsatellite sequences were mined from the recently published Osmia bicornis genome, which was assembled from DNA extracted from a single male bee originating from the United Kingdom. Sequences were identified that contained dinucleotide, trinucleotide, and tetranucleotide repeat regions. Seventeen polymorphic microsatellite markers were designed and tested, sixteen of which were developed into four multiplex PCR sets to facilitate cheap, fast and efficient genotyping and were characterised in unrelated females from Germany (n = 19) and England (n = 14). CONCLUSIONS: The microsatellite markers are highly informative, with a combined exclusion probability of 0.997 (first parent), which will enable studies of genetic structure and diversity to inform conservation efforts in this bee.

Network analysis reveals aggregation behaviour for an endangered predator at an offshore island.

Site fidelity and aggregation behaviour were assessed for giant sea bass Stereolepis gigas (GSB) at Santa Barbara Island, California, USA, from 2018 to 2020. Results indicate seasonal variation in GSB presence, and network analyses revealed a preferred location in a spatially constrained pattern, indicative of aggregation behaviour. Results show GSB aggregated annually during spawning months in the same location, confirming the first known aggregation of GSB at Santa Barbara Island. Identifying and monitoring aggregation sites is vital to ensuring proper protection and ultimate recovery for this protected species in a changing climate.

Genome Architecture Facilitates Phenotypic Plasticity in the Honeybee (Apis mellifera).

Phenotypic plasticity, the ability of an organism to alter its phenotype in response to an environmental cue, facilitates rapid adaptation to changing environments. Plastic changes in morphology and behavior are underpinned by widespread gene expression changes. However, it is unknown if, or how, genomes are structured to ensure these robust responses. Here, we use repression of honeybee worker ovaries as a model of plasticity. We show that the honeybee genome is structured with respect to plasticity; genes that respond to an environmental trigger are colocated in the honeybee genome in a series of gene clusters, many of which have been assembled in the last 80 My during the evolution of the Apidae. These clusters are marked by histone modifications that prefigure the gene expression changes that occur as the ovary activates, suggesting that these genomic regions are poised to respond plastically. That the linear sequence of the honeybee genome is organized to coordinate widespread gene expression changes in response to environmental influences and that the chromatin organization in these regions is prefigured to respond to these influences is perhaps unexpected and has implications for other examples of plasticity in physiology, evolution, and human disease.

Extending the post-thaw viability of cryoprecipitate.

BACKGROUND: Cryoprecipitate has a short post-thaw expiry time of 6 h. The aim of this study was to assess the stability and function of cryoprecipitate components (FVIII, fibrinogen, vWF, and FXIII) and cryoprecipitate sterility up to 120 h post-thawing when stored at two temperatures (2-6°C and room temperature [20-24°C]). METHODS AND MATERIALS: Twenty batches (110 individual units) of time-expired, thawed cryoprecipitate were collected. Units were sampled at the 6-h expiration mark and then stored at 2-6°C or room temperature (RT). They were resampled every 24 h for 120 h. One unit from each batch was sent for sterility testing at 120 h. Samples had FVIII (one stage and chromogenic), fibrinogen, FXIII, vWFag, and vWF:RCo assays performed in batches. Rotational thromboelastometry (ROTEM) was also performed. RESULTS: FVIII levels declined significantly at 120 h post-thawing at both RT and 2-6°C, but still met international standards for FVIII content. Fibrinogen, vWF antigen, and FXIII levels reduced minimally over 120 h and always met international standard requirements when stored at either temperature. ROTEM analysis demonstrated that fibrinogen function was not compromised at 120 h post-thawing under both storage conditions. vWF:RCo levels declined significantly over 120 h at both storage temperatures. No bacterial contamination was detected in 20 units of cryoprecipitate following storage for 120 h post-thawing. CONCLUSION: These results demonstrate that extension of the storage time of thawed cryoprecipitate to 120 h, stored at either 2-6°C or RT, is feasible while still maintaining required FVIII, fibrinogen, and vWFag levels. Storage at 2-6°C has the advantage of reduced risk of potential bacterial contamination.

Social competition stimulates cognitive performance in a sex-specific manner.

Social interactions are thought to be a critical driver in the evolution of cognitive ability. Cooperative interactions, such as pair bonding, rather than competitive interactions have been largely implicated in the evolution of increased cognition. This is despite competition traditionally being a very strong driver of trait evolution. Males of many species track changes in their social environment and alter their reproductive strategies in response to anticipated levels of competition. We predict this to be cognitively challenging. Using a Drosophila melanogaster model, we are able to distinguish between the effects of a competitive environment versus generic social contact by exposing flies to same-sex same-species competition versus different species partners, shown to present non-competitive contacts. Males increase olfactory learning/memory and visual memory after exposure to conspecific males only, a pattern echoed by increased expression of synaptic genes and an increased need for sleep. For females, largely not affected by mating competition, the opposite pattern was seen. The results indicate that specific social contacts dependent on sex, not simply generic social stimulation, may be an important evolutionary driver for cognitive ability in fruit flies.

The diversity and distribution of D1 proteins in cyanobacteria.

The psbA gene family in cyanobacteria encodes different forms of the D1 protein that is part of the Photosystem II reaction centre. We have identified a phylogenetically distinct D1 group that is intermediate between previously identified G3-D1 and G4-D1 proteins (Cardona et al. Mol Biol Evol 32:1310-1328, 2015). This new group contained two subgroups: D1INT, which was frequently in the genomes of heterocystous cyanobacteria and D1FR that was part of the far-red light photoacclimation gene cluster of cyanobacteria. In addition, we have identified subgroups within G3, the micro-aerobically expressed D1 protein. There are amino acid changes associated with each of the subgroups that might affect the function of Photosystem II. We show a phylogenetically broad range of cyanobacteria have these D1 types, as well as the genes encoding the G2 protein and chlorophyll f synthase. We suggest identification of additional D1 isoforms and the presence of multiple D1 isoforms in phylogenetically diverse cyanobacteria supports the role of these proteins in conferring a selective advantage under specific conditions.

An open label study of the safety and efficacy of a single dose of weekly chloroquine and azithromycin administered for malaria prophylaxis in healthy adults challenged with 7G8 chloroquine-resistant Plasmodium falciparum in a controlled human malaria infection model.

BACKGROUND: Malaria remains the top infectious disease threat facing the U.S. military in many forward operating environments. Compliance with malaria chemoprophylaxis remains a critical component in preventing malaria in the deployed Service Member. Studies of previous military operations show that compliance is consistently higher with weekly versus daily dosing regimens. Current FDA approved weekly chemoprophylaxis options have contraindications that can limit prescribing. The combination of chloroquine (CQ) with azithromycin (AZ) has previously been shown to be an efficacious treatment option for malaria, has pharmacokinetics compatible with weekly dosing, and has shown synergy when combined in vitro. METHODS: In this open label study, 18 healthy volunteers, aged 18-50 years (inclusive), were randomly assigned to receive either 300 mg CQ or 300 mg CQ and 2 gm azithromycin (CQAZ) of directly observed therapy, weekly for 3 weeks prior to undergoing mosquito bite challenge with chloroquine-resistant Plasmodium falciparum. Volunteers that remained asymptomatic and had no evidence of parasitaemia continued to receive weekly post-exposure chemoprophylaxis for 3 weeks following malaria challenge. The primary endpoint was the number of volunteers that remained asymptomatic and had no evidence of parasitaemia 28 days after the malaria challenge. RESULTS: All 6 (100%) volunteers randomized to the CQ control group became symptomatic with parasitaemia during the 28-day post-challenge period. Only 1/12 (8.3%) of volunteers in the CQAZ group developed symptoms and parasitaemia during the 28-day post-challenge period. However, after chemoprophylaxis was discontinued an additional 6 volunteers developed parasitaemia between days 28-41 after challenge, with 4 of 6 experiencing symptoms. 80% of subjects in the CQAZ group experienced treatment related gastrointestinal adverse events (including 13% that experienced severe nausea) compared to 38% in the CQ group. A comparison of the pharmacokinetics in the CQAZ group demonstrated higher azithromycin Cmax (p = 0.03) and AUC (p = 0.044) levels in those volunteers who never became parasitaemic compared to those who did. CONCLUSION: Given the high rate of side effects and poor efficacy when administered for 3 weeks before and after challenge, the combination of weekly chloroquine and azithromycin is a suboptimal regimen combination for weekly malaria chemoprophylaxis. Trial registration ClinicalTrials.gov NCT03278808.

Including health impacts in environmental impact assessments for three Australian coal-mining projects: a documentary analysis.

Notwithstanding the historical benefits of coal in aiding human and economic development, the negative health and environmental impacts of coal extraction and processing are of increasing concern. Environmental impact assessments (EIAs) are a regulated policy mechanism that can be used to predict and consider the health impacts of mining projects to determine if consent is given. The ways in which health is considered within EIA is unclear. This research investigated 'How and to what extent are health, well-being and equity issues considered in Environmental Impact Assessments (EIAs) of major coal mining projects in New South Wales, Australia'. To this end we developed and applied a comprehensive coding framework designed to interrogate the publicly available environmental impact statements (EISs) of three mines in New South Wales (NSW), Australia, for their inclusion of health, well-being and equity issues. Analysis of the three EISs demonstrates that: the possible impacts of each mine on health and well-being were narrowly and inadequately considered; when health and well-being were considered there was a failure to assess the possible impacts specific to the particular mine and the communities potentially affected; the cumulative impacts on human health of multiple mines in the same geographical area were almost completely ignored; the discussions of intragenerational and intergenerational equity did not demonstrate a sound understanding of equity and, it is essential that governments' requirements for the EIA include detailed analysis of the health, well-being, equity and cumulative impacts specific to the proposed mine and relevant communities.

Correlation Between Malaria-Specific Antibody Profiles and Responses to Artemisinin Combination Therapy for Treatment of Uncomplicated Malaria in Western Kenya.

BACKGROUND: The impact of preexisting immunity on the efficacy of artemisinin combination therapy must be examined to monitor resistance, and for implementation of new treatment strategies. METHODS: Serum samples obtained from a clinical trial in Western Kenya randomized to receive artemether-lumefantrine (AL) or artesunate-mefloquine (ASMQ) were screened for total immunoglobulin G against preerythrocytic and erythrocytic antigens. The association and correlation between different variables, and impact of preexisting immunity on parasite slope half-life (t½) was determined. RESULTS: There was no significant difference in t½, but the number of individuals with lag phase was significantly higher in the AL than in the ASMQ arm (29 vs 13, respectively; P < .01). Circumsporozoite protein-specific antibodies correlate positively with t½ (AL, P = .03; ASMQ, P = .09), but negatively with clearance rate in both study arms (AL, P = .16; ASMQ, P = .02). The t½ correlated negatively with age in ASMQ group. When stratified based on t½, the antibody titers against circumsporozoite protein and merozoite surface protein 1 were significantly higher in participants who cleared parasites rapidly in the AL group (P = .01 and P = .02, respectively). CONCLUSION: Data presented here define immunoprofiles associated with distinct responses to 2 different antimalarial drugs, revealing impact of preexisting immunity on the efficacy of artemisinin combination therapy regimens in a malaria-holoendemic area. CLINICAL TRIALS REGISTRATION: NCT01976780.

Correction to: From genes to environment in shaping of an embryo: understanding embryonic-extraembryonic interactions at the BSDB autumn meeting in Oxford.

The authors of the article Ajduk & Duncan 2019 sincerely apologize for specifying the incorrect institutional affiliation for Professor Ali Brivanlou and also the incorrect spelling of Professor Brivanlou's surname in the text of the article.

From genes to environment in shaping of an embryo: understanding embryonic-extraembryonic interactions at the BSDB autumn meeting in Oxford.

The British Society for Developmental Biology Autumn Meeting, held in Oxford in September 2018, was the third in a series of international workshops which have been focussed on development at the extraembryonic-embryonic interface. This workshop, entitled "Embryonic-Extraembryonic Interactions: from Genetics to Environment" built on the two previous workshops held in 2011 (Leuven, Belgium) and 2015 (Göttingen, Germany). This workshop brought together researchers utilising a diverse range of organisms (including both vertebrate and invertebrate species) and a range of experimental approaches to answer core questions in developmental biology. This meeting report highlights some of the major themes emerging from the workshop including an evolutionary perspective as well as recent advances that have been made through the adoption of emerging techniques and technologies.