Whole cell reconstructions of Leishmania mexicana through the cell cycle

The unicellular parasite Leishmania has a precisely defined cell architecture that is inherited by each subsequent generation, requiring a highly coordinated pattern of duplication and segregation of organelles and cytoskeletal structures. A framework of nuclear division and morphological changes is known from light microscopy, yet this has limited resolution and the intrinsic organisation of organelles within the cell body and their manner of duplication and inheritance is unknown. Using volume electron microscopy approaches, we have produced three-dimensional reconstructions of different promastigote cell cycle stages to give a spatial and quantitative overview of organelle positioning, division and inheritance. The first morphological indications seen in our dataset that a new cell cycle had begun were the assembly of a new flagellum, the duplication of the contractile vacuole and the increase in volume of the nucleus and kinetoplast. We showed that the progression of the cytokinesis furrow created a specific pattern of membrane indentations, while our analysis of sub-pellicular microtubule organisation indicated that there is likely a preferred site of new microtubule insertion. The daughter cells retained these indentations in their cell body for a period post-abscission. By comparing cultured and sand fly derived promastigotes, we found an increase in the number and overall volume of lipid droplets in the promastigotes from the sand fly, reflecting a change in their metabolism to ensure transmissibility to the mammalian host. Our insights into the cell cycle mechanics of Leishmania will support future molecular cell biology analyses of these parasites.

Discrimination, gender dysphoria, drinking to cope, and alcohol harms in the UK trans and non-binary community

Transgender (trans) and non-binary people may be at increased risk of alcohol harms, but little is known about motives for drinking in this community. This study explored the relationship between risk of alcohol dependence, experience of alcohol harms, drinking motives, dysphoria, and discrimination within a United Kingdom sample of trans and non-binary people with a lifetime history of alcohol use. A cross-sectional survey was co-produced with community stakeholders and administered to a purposive sample of trans and non-binary people from 1 February until 31 March 2022. A total of 462 respondents were included-159 identified as non-binary and/or genderqueer (identities outside the man/woman binary), 135 solely as women, 63 solely as men, 15 as another gender identity, 90 selected multiple identities. Higher levels of reported discrimination were associated with higher risk of dependence and more reported harms from drinking. Coping motives, enhancement motives, and drinking to manage dysphoria were associated with higher Alcohol Use Disorders Identification Test scores. Social, coping, and enhancement motives alongside discrimination and drinking to have sex were associated with harms. The relationship between discrimination and risk of dependence was mediated by coping motives and drinking to manage dysphoria. Further to these associations, we suggest that reducing discrimination against trans and non-binary communities might reduce alcohol harms in this population. Interventions should target enhancement motives, coping motives and gender dysphoria. Social and enhancement functions of alcohol could be replaced by alcohol free supportive social spaces.

Parental sleep-related practices and sleep in children aged 1-3 years: a systematic review

The current systematic review sought to identify the relationship between the range of different parental sleep-related practices that had been explored in relations to child sleep outcomes in children aged 1-3 years. A systematic literature review was carried out in CINAHL, The Cochrane Library, PsycArticles, PsycInfo, PubMed and Web of Science, as well as relevant grey literature in August 2022 using the terms; population (children, aged 1-3 years), exposure (parental sleep-related practice) and outcome (child sleep). Any quantitative study published between 2010 and 2022 that explored the relationship between parental sleep-related practices and the sleep of children aged 1-3 years were included. The Mixed Methods Appraisal Tool was employed to quality appraise included studies and results were narratively synthesised. In all, 16 longitudinal and cross-sectional quantitative studies met inclusion criteria. Parental presence or physical involvement, as well as broader parental practices including using screens or devices at bedtime and night-time breastfeeding were all related to poorer child sleep outcomes. Consistent and relaxing routines, sleeping in a cot, and spending all night in their own sleep location were associated with better child sleep outcomes. Acknowledging the plethora of diverse parental sleep-related practices, which may have varying relationships with child sleep outcomes, could be usefully considered in theoretical models and to inform clinical practice. Issues of definitional and measurement ambiguity are highlighted and discussed.

Infectious disease in the Pleistocene: Old friends or old foes?

The impact of endemic and epidemic disease on humans has traditionally been seen as a comparatively recent historical phenomenon associated with the Neolithisation of human groups, an increase in population size led by sedentarism, and increasing contact with domesticated animals as well as species occupying opportunistic symbiotic and ectosymbiotic relationships with humans. The orthodox approach is that Neolithisation created the conditions for increasing population size able to support a reservoir of infectious disease sufficient to act as selective pressure. This orthodoxy is the result of an overly simplistic reliance on skeletal data assuming that no skeletal lesions equated to a healthy individual, underpinned by the assumption that hunter-gatherer groups were inherently healthy while agricultural groups acted as infectious disease reservoirs. The work of van Blerkom, Am. J. Phys. Anthropol., vol. suppl 37 (2003), Wolfe et al., Nature, vol. 447 (2007) and Houldcroft and Underdown, Am. J. Phys. Anthropol., vol. 160, (2016) has changed this landscape by arguing that humans and pathogens have long been fellow travelers. The package of infectious diseases experienced by our ancient ancestors may not be as dissimilar to modern infectious diseases as was once believed. The importance of DNA, from ancient and modern sources, to the study of the antiquity of infectious disease, and its role as a selective pressure cannot be overstated. Here we consider evidence of ancient epidemic and endemic infectious diseases with inferences from modern and ancient human and hominin DNA, and from circulating and extinct pathogen genomes. We argue that the pandemics of the past are a vital tool to unlock the weapons needed to fight pandemics of the future.

In Depth Topological Analysis of Arabidopsis Mid-SUN Proteins and Their Interaction with the Membrane-Bound Transcription Factor MaMYB

Mid-SUN proteins are a neglected family of conserved type III membrane proteins of ancient origin with representatives in plants, animals, and fungi. Previous higher plant studies have associated them with functions at the nuclear envelope and the endoplasmic reticulum (ER). In this study, high-resolution confocal light microscopy is used to explore the localisation of SUN3 and SUN4 in the perinuclear region, to explore topology, and to study the role of mid-SUNs on endoplasmic reticulum morphology. The role of SUN3 in the ER is reinforced by the identification of a protein interaction between SUN3 and the ER membrane-bound transcription factor maMYB. The results highlight the importance of mid-SUNs as functional components of the ER and outer nuclear membrane.

A Functional Interaction Between Y674-R685 Region of the SARS-CoV-2 Spike Protein and the Human α7 Nicotinic Receptor

The α7 nicotinic acetylcholine receptor (nAChR) is present in neuronal and non-neuronal cells and has anti-inflammatory actions. Molecular dynamics simulations suggested that α7 nAChR interacts with a region of the SARS-CoV-2 spike protein (S), and a potential contribution of nAChRs to COVID-19 pathophysiology has been proposed. We applied whole-cell and single-channel recordings to determine whether a peptide corresponding to the Y674-R685 region of the S protein can directly affect α7 nAChR function. The S fragment exerts a dual effect on α7. It activates α7 nAChRs in the presence of positive allosteric modulators, in line with our previous molecular dynamics simulations showing favourable binding of this accessible region of the S protein to the nAChR agonist binding site. The S fragment also exerts a negative modulation of α7, which is evidenced by a profound concentration-dependent decrease in the durations of openings and activation episodes of potentiated channels and in the amplitude of macroscopic responses elicited by ACh. Our study identifies a potential functional interaction between α7 nAChR and a region of the S protein, thus providing molecular foundations for further exploring the involvement of nAChRs in COVID-19 pathophysiology.

A rare missense variant in the ATP2C2 gene is associated with language impairment and related measures

At least 5% of children present unexpected difficulties in expressing and understanding spoken language. This condition is highly heritable and often co-occurs with other neurodevelopmental disorders such as dyslexia and ADHD. Through an exome sequencing analysis, we identified a rare missense variant (chr16:84405221, GRCh38.p12) in the ATP2C2 gene. ATP2C2 was implicated in language disorders by linkage and association studies, and exactly the same variant was reported previously in a different exome sequencing study for language impairment (LI). We followed up this finding by genotyping the mutation in cohorts selected for LI and comorbid disorders. We found that the variant had a higher frequency in LI cases (1.8%, N = 360) compared with cohorts selected for dyslexia (0.8%, N = 520) and ADHD (0.7%, N = 150), which presented frequencies comparable to reference databases (0.9%, N = 24 046 gnomAD controls). Additionally, we observed that carriers of the rare variant identified from a general population cohort (N = 42, ALSPAC cohort) presented, as a group, lower scores on a range of reading and language-related measures compared to controls (N = 1825; minimum P = 0.002 for non-word reading). ATP2C2 encodes for an ATPase (SPCA2) that transports calcium and manganese ions into the Golgi lumen. Our functional characterization suggested that the rare variant influences the ATPase activity of SPCA2. Thus, our results further support the role of ATP2C2 locus in language-related phenotypes and pinpoint the possible effects of a specific rare variant at molecular level.

ACME dissociation: a versatile cell fixation-dissociation method for single-cell transcriptomics

Single-cell sequencing technologies are revolutionizing biology, but they are limited by the need to dissociate live samples. Here, we present ACME (ACetic-MEthanol), a dissociation approach for single-cell transcriptomics that simultaneously fixes cells. ACME-dissociated cells have high RNA integrity, can be cryopreserved multiple times, and are sortable and permeable. As a proof of principle, we provide single-cell transcriptomic data of different species, using both droplet-based and combinatorial barcoding single-cell methods. ACME uses affordable reagents, can be done in most laboratories and even in the field, and thus will accelerate our knowledge of cell types across the tree of life.

Go your own way: membrane-targeting sequences

Membrane-targeting sequences, connected targeting mechanisms, and co-factors orchestrate primary targeting of proteins to membranes.

The experiences and needs of couples affected by prostate cancer aged 65 and under: a qualitative study

PURPOSE

Prostate Cancer (PCa) is often considered to be an illness affecting older men, however the prevalence in younger men (<=65 years) is rising. Diagnosis and treatment for PCa can have a significant impact on the lives of both the man with PCa and his partner. This study explored the experiences and needs of younger men and their partners affected by PCa. The findings will be used to inform service provision and develop interventions appropriate to need.

METHODS

Participants were recruited from respondents to a national PROMS study (Life After Prostate Cancer Diagnosis (LAPCD), who indicated on completed questionnaires their willingness to be interviewed. Semi-structured telephone interviews were conducted with twenty-eight couples, separately (56 participants). Data were analysed using the Framework Method.

RESULTS

Following the diagnosis of PCa, couples' experienced changes in their intimate relationships, parental/familial roles, work and finances, and social connections and activities. Couples adopted a range of strategies and behaviours to help their adjustment to PCa, such as communicating with each other, distancing, distraction, and adopting a positive mindset towards PCa. This, in turn, influenced how their identity as a couple evolved.

CONCLUSIONS

Following a diagnosis of PCa, the identity of couples are continually evolving. It is important that these couples are provided with the appropriate information, support and resources to help them transition along the cancer pathway.

IMPLICATIONS FOR CANCER SURVIVORS

Key areas of support identified for younger couples include: 1) couple focused support programme to foster relationship strategies/behaviours that facilitate couple adjustment; 2) age-specific support, e.g. 'buddying systems' connecting younger couples affected by PCa and providing them with tailored information (written/online/app).

Control of assembly of extra-axonemal structures: the paraflagellar rod of trypanosomes

Eukaryotic flagella are complex microtubule-based organelles that, in many organisms, contain extra-axonemal structures, such as the outer dense fibres of mammalian sperm and the paraflagellar rod (PFR) of trypanosomes. Flagellum assembly is a complex process occurring across three main compartments, the cytoplasm, the transition zone and the flagellum itself. The process begins with the translation of protein components followed by their sorting and trafficking into the flagellum, transport to the assembly site and incorporation. Flagella are formed from over 500 proteins and the principles governing assembly of the axonemal components are relatively clear. However, the coordination and location of assembly of extra-axonemal structures are less clear. We have discovered two cytoplasmic proteins in Trypanosoma brucei that are required for PFR formation, PFR assembly factors 1 and 2 (PFR-AF1 and PFR-AF2, respectively). Deletion of either PFR-AF1 or PFR-AF2 dramatically disrupted PFR formation and caused a reduction in the amount of major PFR proteins. The existence of cytoplasmic factors required for PFR formation aligns with the concept that processes facilitating axoneme assembly occur across multiple compartments, and this is likely a common theme for extra-axonemal structure assembly.

Arboreal route navigation in a Neotropical mammal: energetic implications associated with tree monitoring and landscape attributes

BACKGROUND

Although navigating along a network of routes might constrain animal movement flexibility, it may be an energetically efficient strategy. Routinely using the same route allows for visually monitoring of food resources, which might reduce the cognitive load and as such facilitate the process of movement decision-making. Similarly, locating routes in areas that avoid costly landscape attributes will enhance their overall energy balance. In this study we determined the benefits of route navigation in an energy minimiser arboreal primate, the black howler monkey (Alouatta pigra).

METHODS

We monitored five neighbouring groups of black howler monkeys at Palenque National Park, Mexico from September 2016 through August 2017. We recorded the location of the focal group every 20 m and mapped all travel paths to establish a route network (N = 1528 travel bouts). We constructed linear mixed models to assess the influence of food resource distribution (N = 931 trees) and landscape attributes (slope, elevation and presence of canopy gaps) on the location of routes within a route network.

RESULTS

The number of food trees that fell within the visual detection distance from the route network was higher (mean: 156.1 ± SD 44.9) than randomly simulated locations (mean: 121.9 ± SD 46.4). Similarly, the number of food trees found within the monkey's visual range per meter travelled increased, on overage, 0.35 ± SE 0.04 trees/m with increasing use of the route. In addition, route segments used at least twice were more likely to occur with increasing density of food resources and decreasing presence of canopy gaps. Route segments used at least four times were more likely to occur in elevated areas within the home ranges but only under conditions of reduced visual access to food resources.

CONCLUSIONS

Route navigation emerged as an efficient movement strategy in a group-living arboreal primate. Highly used route segments potentially increased visual access to food resources while avoiding energetically costly landscape features securing foraging success in a tropical rainforest.

Using the TIDieR checklist to describe health visitor support for mothers with mental health problems: Analysis of a cross-sectional survey

At least half of the 20% of mothers who experience mental health problems (MHPs) during pregnancy or after birth are not receiving the help they need that will lead to recovery. In order to identify where improvements need to be made, it is necessary to describe exactly what is being done and the barriers and facilitators that compromise or enhance optimal care. The majority of mothers experience mild to moderate anxiety or depression. The expectation is that primary care professionals, such as health visitors (HVs), can provide the support they need that will lead to recovery. The aim of this study was to explore the views of HVs regarding the content and purpose of an intervention to support mothers with MHPs, described as 'listening visits' (LVs). A link to an online survey was offered to the members and champions of the Institute of Health Visiting (n = 9,474) March-May 2016. The survey was completed by 1,599 (17%) of the target population, of whom 85% were offering LVs. The Template for Intervention Description and Replication (TIDieR) checklist was used to provide a framework to describe commonalities and variations in practice. There appeared to be a shared understanding of the rationale for LVs but a lack of agreement about what the intervention should be called, the techniques that should be used and the duration, frequency and expected outcomes of the intervention. Contextual factors such as staff shortages; conflicting priorities; the needs and circumstances of mothers; the capability and motivation of HVs; inadequate training and supervision; and the absence of clear guidance contributed to variations in perceptions and practice. There are many ways in which the HV contribution to the assessment and management of mothers with MHPs could be improved. The intervention delivered by HVs needs to be more clearly articulated. The contextual factors influencing competent and consistent practice also need to be addressed.