Caenorhabditis elegans germ granules are present in distinct configurations and assemble in a hierarchical manner.

RNA silencing pathways are complex, highly conserved, and perform crucial regulatory roles. In Caenorhabditis elegans germlines, RNA surveillance occurs through a series of perinuclear germ granule compartments - P granules, Z granules, SIMR foci, and Mutator foci - multiple of which form via phase separation. Although the functions of individual germ granule proteins have been extensively studied, the relationships between germ granule compartments (collectively, 'nuage') are less understood. We find that key germ granule proteins assemble into separate but adjacent condensates, and that boundaries between germ granule compartments re-establish after perturbation. We discover a toroidal P granule morphology, which encircles the other germ granule compartments in a consistent exterior-to-interior spatial organization, providing broad implications for the trajectory of an RNA as it exits the nucleus. Moreover, we quantify the stoichiometric relationships between germ granule compartments and RNA to reveal discrete populations of nuage that assemble in a hierarchical manner and differentially associate with RNAi-targeted transcripts, possibly suggesting functional differences between nuage configurations. Our work creates a more accurate model of C. elegans nuage and informs the conceptualization of RNA silencing through the germ granule compartments.

Cytoskeletal forces span the nuclear envelope to coordinate meiotic chromosome pairing and synapsis.

During meiosis, each chromosome must pair with its unique homologous partner, a process that usually culminates with the formation of the synaptonemal complex (SC). In the nematode Caenorhabditis elegans, special regions on each chromosome known as pairing centers are essential for both homologous pairing and synapsis. We report that during early meiosis, pairing centers establish transient connections to the cytoplasmic microtubule network. These connections through the intact nuclear envelope require the SUN/KASH domain protein pair SUN-1 and ZYG-12. Disruption of microtubules inhibits chromosome pairing, indicating that these connections promote interhomolog interactions. Dynein activity is essential to license formation of the SC once pairing has been accomplished, most likely by overcoming a barrier imposed by the chromosome-nuclear envelope connection. Our findings thus provide insight into how homolog pairing is accomplished in meiosis and into the mechanisms regulating synapsis so that it occurs selectively between homologs. For a video summary of this article, see the PaperFlick file with the Supplemental Data available online.

Spatiotemporal regulation of liquid-like condensates in epigenetic inheritance.

Non-membrane-bound organelles such as nucleoli, processing bodies, Cajal bodies and germ granules form by the spontaneous self-assembly of specific proteins and RNAs. How these biomolecular condensates form and interact is poorly understood. Here we identify two proteins, ZNFX-1 and WAGO-4, that localize to Caenorhabditis elegans germ granules (P granules) in early germline blastomeres. Later in germline development, ZNFX-1 and WAGO-4 separate from P granules to define an independent liquid-like condensate that we term the Z granule. In adult germ cells, Z granules assemble into ordered tri-condensate assemblages with P granules and Mutator foci, which we term PZM granules. Finally, we show that one biological function of ZNFX-1 and WAGO-4 is to interact with silencing RNAs in the C. elegans germline to direct transgenerational epigenetic inheritance. We speculate that the temporal and spatial ordering of liquid droplet organelles may help cells to organize and coordinate the complex RNA processing pathways that underlie gene-regulatory systems, such as RNA-directed transgenerational epigenetic inheritance.

Moving beyond the constraints of chemistry via crystal structure discovery with isotropic multiwell pair potentials.

The rigid constraints of chemistry-dictated by quantum mechanics and the discrete nature of the atom-limit the set of observable atomic crystal structures. What structures are possible in the absence of these constraints? Here, we systematically crystallize one-component systems of particles interacting with isotropic multiwell pair potentials. We investigate two tunable families of pairwise interaction potentials. Our simulations self-assemble a multitude of crystal structures ranging from basic lattices to complex networks. Sixteen of the structures have natural analogs spanning all coordination numbers found in inorganic chemistry. Fifteen more are hitherto unknown and occupy the space between covalent and metallic coordination environments. The discovered crystal structures constitute targets for self-assembly and expand our understanding of what a crystal structure can look like.

RNAi pathways repress reprogramming of C. elegans germ cells during heat stress.

Repression of cellular reprogramming in germ cells is critical to maintaining cell fate and fertility. When germ cells mis-express somatic genes they can be directly converted into other cell types, resulting in loss of totipotency and reproductive potential. Identifying the molecular mechanisms that coordinate these cell fate decisions is an active area of investigation. Here we show that RNAi pathways play a key role in maintaining germline gene expression and totipotency after heat stress. By examining transcriptional changes that occur in mut-16 mutants, lacking a key protein in the RNAi pathway, at elevated temperature we found that genes normally expressed in the soma are mis-expressed in germ cells. Furthermore, these genes displayed increased chromatin accessibility in the germlines of mut-16 mutants at elevated temperature. These findings indicate that the RNAi pathway plays a key role in preventing aberrant expression of somatic genes in the germline during heat stress. This regulation occurs in part through the maintenance of germline chromatin, likely acting through the nuclear RNAi pathway. Identification of new pathways governing germ cell reprogramming is critical to understanding how cells maintain proper gene expression and may provide key insights into how cell identity is lost in some germ cell tumors.

Infant Outcomes Following Maternal Infection With Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): First Report From the Pregnancy Coronavirus Outcomes Registry (PRIORITY) Study.

Infant outcomes after maternal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are not well described. In a prospective US registry of 263 infants, maternal SARS-CoV-2 status was not associated with birth weight, difficulty breathing, apnea, or upper or lower respiratory infection through 8 weeks of age.

Health care utilization by women sexual assault survivors after emergency care: Results of a multisite prospective study.

BACKGROUND: Approximately, 100,000 US women receive emergency care after sexual assault each year, but no large-scale study has examined the incidence of posttraumatic sequelae, receipt of health care, and frequency of assault disclosure to providers. The current study evaluated health outcomes and service utilization among women in the 6 weeks after sexual assault. METHODS: Women ≥18 years of age presenting for emergency care after sexual assault to twelve sites were approached. Among those willing to be contacted for the study (n = 1080), 706 were enrolled. Health outcomes, health care utilization, and assault disclosure were assessed via 6 week survey. RESULTS: Three quarters (76%) of women had posttraumatic stress, depression, or anxiety, and 65% had pain. Less than two in five reported seeing health care provider; receipt of care was not related to substantive differences in symptoms and was less likely among Hispanic women and women with a high school education or less. Nearly one in four who saw a primary care provider did not disclose their assault, often due to shame, embarrassment, or fear of being judged. CONCLUSION: Most women receiving emergency care after sexual assault experience substantial posttraumatic sequelae, but health care in the 6 weeks after assault is uncommon, unrelated to substantive differences in need, and limited in socially disadvantaged groups. Lack of disclosure to primary care providers was common among women who did receive care.

Lessons learned from the delivery of virtual integrative oncology interventions in clinical practice and research during the COVID-19 pandemic.

The outbreak of the coronavirus disease 2019 (COVID-19) and subsequent need for disease transmission mitigation efforts have significantly altered the delivery of cancer care (e.g., rise of telemedicine), including within the field of integrative oncology. However, little has been described about how National Cancer Institute-Designated Cancer Centers have transformed integrative oncology care delivery in response to the COVID-19 pandemic. The purpose of this commentary is to describe the delivery of integrative oncology clinical services and conduct of research at The Leonard P. Zakim Center for Integrative Therapies and Healthy Living at Dana-Farber Cancer Institute during the COVID-19 pandemic. Clinical services transitioned from an array of in-person appointment-based services, such as acupuncture and massage, and group programs, such as yoga and nutrition seminars to a combination of live-streamed and on-demand virtual group programs and one-on-one virtual appointments for services such as acupressure and self-care massage. Group program volume grew from 2189 in-person program patient visits in the 6 months prior to onset of the COVID pandemic to 16,366 virtual (e.g., live-streamed or on-demand) patient visits in the first 6 months of the pandemic. From a research perspective, two integrative oncology studies, focused on yoga and music therapy, respectively, were transitioned from in-person delivery to a virtual format. Participant accrual to these studies increased after the transition to virtual consent and intervention delivery. Overall, our clinical and research observations at Dana-Farber Cancer Institute suggest that the delivery of virtual integrative oncology treatments is feasible and appealing to patients. Trial Registration: NCT03824860 (Yoga); NCT03709225 (Music Therapy).

Distinct regions of the intrinsically disordered protein MUT-16 mediate assembly of a small RNA amplification complex and promote phase separation of Mutator foci.

In C. elegans, efficient RNA silencing requires small RNA amplification mediated by RNA-dependent RNA polymerases (RdRPs). RRF-1, an RdRP, and other Mutator complex proteins localize to Mutator foci, which are perinuclear germline foci that associate with nuclear pores and P granules to facilitate small RNA amplification. The Mutator complex protein MUT-16 is critical for Mutator foci assembly. By analyzing small deletions of MUT-16, we identify specific regions of the protein that recruit other Mutator complex components and demonstrate that it acts as a scaffolding protein. We further determine that the C-terminal region of MUT-16, a portion of which contains predicted intrinsic disorder, is necessary and sufficient to promote Mutator foci formation. Finally, we establish that MUT-16 foci have many properties consistent with a phase-separated condensate and propose that Mutator foci form through liquid-liquid phase separation of MUT-16. P granules, which contain additional RNA silencing proteins, have previously been shown to have liquid-like properties. Thus, RNA silencing in C. elegans germ cells may rely on multiple phase-separated compartments through which sorting, processing, and silencing of mRNAs occurs.

Perceived Care Quality Among Women Receiving Sexual Assault Nurse Examiner Care: Results From a 1-Week Postexamination Survey in a Large Multisite Prospective Study.

INTRODUCTION: This study examined the perspectives of female patients who had been sexually assaulted regarding the quality of care provided by sexual assault nurse examiners, including whether the patients' perspectives varied by their demographic characteristics and health status before the assault. METHODS: A total of 695 female patients who received care from sexual assault nurse examiners at 13 United States emergency care centers and community-based programs completed standardized surveys 1 week after receiving sexual assault nurse examiners' care for sexual assault. RESULTS: Most patients strongly agreed that the sexual assault nurse examiners provided high-quality care, including taking patients' needs/concerns seriously, not acting as though the assault was the patient's fault, showing care/compassion, explaining the sexual assault examination, and providing follow-up information. The perceptions did not vary by the patients' demographic characteristics or preassault health status. DISCUSSION: Female patients who had been sexually assaulted and who were evaluated at 13 widely geographically distributed sexual assault nurse examiners' programs consistently reported that the sexual assault nurse examiners provided high-quality, compassionate care.

MUT-16 promotes formation of perinuclear mutator foci required for RNA silencing in the C. elegans germline.

RNA silencing can be initiated by endogenous or exogenously delivered siRNAs. In Caenorhabditis elegans, RNA silencing guided by primary siRNAs is inefficient and therefore requires an siRNA amplification step involving RNA-dependent RNA polymerases (RdRPs). Many factors involved in RNA silencing localize to protein- and RNA-rich nuclear pore-associated P granules in the germline, where they are thought to surveil mRNAs as they exit the nucleus. Mutator class genes are required for siRNA-mediated RNA silencing in both germline and somatic cells, but their specific roles and relationship to other siRNA factors are unclear. Here we show that each of the six mutator proteins localizes to punctate foci at the periphery of germline nuclei. The Mutator foci are adjacent to P granules but are not dependent on core P-granule components or other RNAi pathway factors for their formation or stability. The glutamine/asparagine (Q/N)-rich protein MUT-16 is specifically required for the formation of a protein complex containing the mutator proteins, and in its absence, Mutator foci fail to form at the nuclear periphery. The RdRP RRF-1 colocalizes with MUT-16 at Mutator foci, suggesting a role for Mutator foci in siRNA amplification. Furthermore, we demonstrate that genes that yield high levels of siRNAs, indicative of multiple rounds of siRNA amplification, are disproportionally affected in mut-16 mutants compared with genes that yield low levels of siRNAs. We propose that the mutator proteins and RRF-1 constitute an RNA processing compartment required for siRNA amplification and RNA silencing.

Todos Santos small RNA symposium.

Worm biologists from the United States, Canada, and the United Kingdom gathered at the Colorado State University Todos Santos Center in Baja California Sur, Mexico, April 3-5, 2019 for the Todos Santos Small RNA Symposium. Meeting participants, many of whom were still recovering from the bomb cyclone that struck a large swath of North America just days earlier, were greeted by the warmth and sunshine that is nearly ubiquitous in the sleepy seaside town of Todos Santos. With only 24 speakers, the meeting had the sort of laid-back vibe you might expect amongst the palm trees and ocean breeze of the Pacific coast of Mexico. The meeting started with tracing the laboratory lineages of participants. Not surprisingly, the most common parental lineages represented at the meeting were Dr. Craig Mello, Dr. Gary Ruvkun, and Dr. Victor Ambros, whom, together with Dr. Andy Fire and Dr. David Baulcombe, pioneered the small RNA field. In sad irony, on the closing day of the meeting, participants were met with the news of Dr. Sydney Brenner's passing. By establishing the worm, Caenorhabditis elegans, as a model system Dr. Brenner paved the way for much of the research discussed here.

Systematic Review: Expressive arts interventions to address psychosocial stress in healthcare workers.

AIMS: To synthesize evidence about the effectiveness of expressive arts interventions used to reduce psychosocial stress among healthcare workers. DESIGN: Quantitative systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. DATA SOURCES: SocINDEX, PsycINFO, Pubmed, CINAHL. REVIEW METHODS: Databases were searched from 1997-2017. Fourteen studies met the criteria for final selection. RESULTS: Most studies occurred in the US (N = 11). Of the 897 participants, 59% were nurses. Two studies were randomized controlled trials and the others were a variation of a 1-group or 2-group pre- or quasi-experimental study. The intervention characteristics included 50% art-based, 29% music-based, and 21% used storytelling or narrative. The length of intervention varied from 1 hr to 13 weeks; 5 lasted 6 weeks. Improved outcomes were found in 13 of 14 studies reviewed and the greatest improvements were seen in burnout, stress, and emotional outcomes. Overall, music and art-based interventions had greater impact on well-being than storytelling or narrative. CONCLUSIONS: This systematic review provides preliminary evidence for the effectiveness of expressive arts interventions. IMPACT: Care for others is a preeminent value in health care; however, this can come at the expense of caring for oneself. Psychosocial stress poses a significant threat to the well-being of the healthcare workforce. Expressive arts interventions provide a creative means for reducing caregiver stress to remain well and able to provide high quality care to patients. The use of arts for healing has global application because expressive arts intervention can be culturally tailored and relevant.

Mentoring up: A grounded theory of nurse-to-nurse mentoring.

AIMS AND OBJECTIVES: To generate a theoretical explanation of nurse-to-nurse mentoring in the clinical setting. BACKGROUND: Despite an abundance of mentoring literature, the processes involved between nurses in mentoring relationships have yet to be studied. Nursing literature has focused on mentor attributes and relationship outcomes rather than focusing on theoretical discovery. DESIGN: Classical grounded theory (CGT). METHODS: CGT procedures (constant comparative method, coding and memoing) were used to analyse interview data exploring fifteen nurse protégés' experiences of mentoring. RESULTS: Confidencing, the protégés' need to become confident in the professional role, emerged as the main concern of study participants. Three dimensions are threaded throughout nurse-to-nurse mentoring: earnest intentions, filial bond and trust-worthiness. Earnest intentions are the sincere attitude that protégés and mentors demonstrate regarding their mentoring relationship. An exclusive, familial-type connection, filial bond, attends to the affective needs of protégés and mentors. Trust-worthiness, the explicit feeling of trust between protégés and mentors, strengthens as each demonstrates being worthy of the other's trust. Mentoring Up theory explains five phases of mentoring: seeding, opening, laddering, equalising and reframing. The initial phases are periods of relationship discovery (seeding) and testing (opening). Laddering is an intense period of reciprocal interactions between mentors and protégés. Equalising begins as protégés perceive themselves to be equal to their mentors in terms of their professional capability. Protégés reflect on the meaning of the relationship in the reframing phase. CONCLUSIONS: Mentoring Up is a dense theory that reveals insights, explanations and predictions for initiating, developing and engaging in mentoring relationships. Mentoring Up fills a gap in the existing literature and provides a framework for future mentoring research. RELEVANCE TO CLINICAL PRACTICE: The theory has implications for healthcare organisations, nursing education and individual nurses. Mentoring Up expounds on the interpersonal connections and reciprocal interactions vital for successful nurse-to-nurse mentoring.

Computational self-assembly of a one-component icosahedral quasicrystal.

Icosahedral quasicrystals (IQCs) are a form of matter that is ordered but not periodic in any direction. All reported IQCs are intermetallic compounds and either of face-centred-icosahedral or primitive-icosahedral type, and the positions of their atoms have been resolved from diffraction data. However, unlike axially symmetric quasicrystals, IQCs have not been observed in non-atomic (that is, micellar or nanoparticle) systems, where real-space information would be directly available. Here, we show that an IQC can be assembled by means of molecular dynamics simulations from a one-component system of particles interacting via a tunable, isotropic pair potential extending only to the third-neighbour shell. The IQC is body-centred, self-assembles from a fluid phase, and in parameter space neighbours clathrates and other tetrahedrally bonded crystals. Our findings elucidate the structure and dynamics of the IQC, and suggest routes to search for it and design it in soft matter and nanoscale systems.

Nonlinear machine learning and design of reconfigurable digital colloids.

Digital colloids, a cluster of freely rotating "halo" particles tethered to the surface of a central particle, were recently proposed as ultra-high density memory elements for information storage. Rational design of these digital colloids for memory storage applications requires a quantitative understanding of the thermodynamic and kinetic stability of the configurational states within which information is stored. We apply nonlinear machine learning to Brownian dynamics simulations of these digital colloids to extract the low-dimensional intrinsic manifold governing digital colloid morphology, thermodynamics, and kinetics. By modulating the relative size ratio between halo particles and central particles, we investigate the size-dependent configurational stability and transition kinetics for the 2-state tetrahedral (N = 4) and 30-state octahedral (N = 6) digital colloids. We demonstrate the use of this framework to guide the rational design of a memory storage element to hold a block of text that trades off the competing design criteria of memory addressability and volatility.

PIWI associated siRNAs and piRNAs specifically require the Caenorhabditis elegans HEN1 ortholog henn-1.

Small RNAs--including piRNAs, miRNAs, and endogenous siRNAs--bind Argonaute proteins to form RNA silencing complexes that target coding genes, transposons, and aberrant RNAs. To assess the requirements for endogenous siRNA formation and activity in Caenorhabditis elegans, we developed a GFP-based sensor for the endogenous siRNA 22G siR-1, one of a set of abundant siRNAs processed from a precursor RNA mapping to the X chromosome, the X-cluster. Silencing of the sensor is also dependent on the partially complementary, unlinked 26G siR-O7 siRNA. We show that 26G siR-O7 acts in trans to initiate 22G siRNA formation from the X-cluster. The presence of several mispairs between 26G siR-O7 and the X-cluster mRNA, as well as mutagenesis of the siRNA sensor, indicates that siRNA target recognition is permissive to a degree of mispairing. From a candidate reverse genetic screen, we identified several factors required for 22G siR-1 activity, including the chromatin factors mes-4 and gfl-1, the Argonaute ergo-1, and the 3' methyltransferase henn-1. Quantitative RT-PCR of small RNAs in a henn-1 mutant and deep sequencing of methylated small RNAs indicate that siRNAs and piRNAs that associate with PIWI clade Argonautes are methylated by HENN-1, while siRNAs and miRNAs that associate with non-PIWI clade Argonautes are not. Thus, PIWI-class Argonaute proteins are specifically adapted to associate with methylated small RNAs in C. elegans.

Phase behavior and complex crystal structures of self-assembled tethered nanoparticle telechelics.

Motivated by growing interest in the self-assembly of nanoparticles for applications such as photonics, organic photovoltaics, and DNA-assisted designer crystals, we explore the phase behavior of tethered spherical nanoparticles. Here, a polymer tether is used to geometrically constrain a pair of nanoparticles creating a tethered nanoparticle "telechelic". Using simulation, we examine how varying architectural features, such as the size ratio of the two end-group nanospheres and the length of the flexible tether, affects the self-assembled morphologies. We demonstrate not only that this hybrid building block maintains the same phase diversity as linear triblock copolymers, allowing for a variety of nanoparticle materials to replace polymer blocks, but also that new structures not previously reported are accessible. Our findings imply a robust underlying ordering mechanism is common among these systems, thus allowing flexibility in synthesis approaches to achieve a target morphology.

Digital colloids: reconfigurable clusters as high information density elements.

Through the design and manipulation of discrete, nanoscale systems capable of encoding massive amounts of information, the basic components of computation are open to reinvention. These components will enable tagging, memory storage, and sensing in unusual environments - elementary functions crucial for soft robotics and "wet computing". Here we show how reconfigurable clusters made of N colloidal particles bound flexibly to a central colloidal sphere have the capacity to store an amount of information that increases as O(N ln(N)). Using Brownian dynamics simulations, we predict dynamical regimes that allow for information to be written, saved, and erased. We experimentally assemble an N = 4 reconfigurable cluster from chemically synthesized colloidal building blocks, and monitor its equilibrium dynamics. We observe state switching in agreement with simulations. This cluster can store one bit of information, and represents the simplest digital colloid.

mut-16 and other mutator class genes modulate 22G and 26G siRNA pathways in Caenorhabditis elegans.

Argonaute-associated siRNAs and Piwi-associated piRNAs have overlapping roles in silencing mobile genetic elements in animals. In Caenorhabditis elegans, mutator (mut) class genes mediate siRNA-guided repression of transposons as well as exogenous RNAi, but their roles in endogenous RNA silencing pathways are not well-understood. To characterize the endogenous small RNAs dependent on mut class genes, small RNA populations from a null allele of mut-16 as well as a regulatory mut-16(mg461) allele that disables only somatic RNAi were subjected to deep sequencing. Additionally, each of the mut class genes was tested for a requirement in 26G siRNA pathways. The results indicate that mut-16 is an essential factor in multiple endogenous germline and somatic siRNA pathways involving several distinct Argonautes and RNA-dependent RNA polymerases. The results also reveal essential roles for mut-2 and mut-7 in the ERGO-1 class 26G siRNA pathway and less critical roles for mut-8, mut-14, and mut-15. We show that transposons are hypersusceptible to mut-16-dependent silencing and identify a requirement for the siRNA machinery in piRNA biogenesis from Tc1 transposons. We also show that the soma-specific mut-16(mg461) mutant allele is present in multiple C. elegans laboratory strains.