Interactions between U and V sex chromosomes during the life cycle of Ectocarpus.

In many animals and flowering plants, sex determination occurs in the diploid phase of the life cycle with XX/XY or ZW/ZZ sex chromosomes. However, in early diverging plants and most macroalgae, sex is determined by female (U) or male (V) sex chromosomes in a haploid phase called the gametophyte. Once the U and V chromosomes unite at fertilization to produce a diploid sporophyte, sex determination no longer occurs, raising key questions about the fate of the U and V sex chromosomes in the sporophyte phase. Here, we investigate genetic and molecular interactions of the UV sex chromosomes in both the haploid and diploid phases of the brown alga Ectocarpus. We reveal extensive developmental regulation of sex chromosome genes across its life cycle and implicate the TALE-HD transcription factor OUROBOROS in suppressing sex determination in the diploid phase. Small RNAs may also play a role in the repression of a female sex-linked gene, and transition to the diploid sporophyte coincides with major reconfiguration of histone H3K79me2, suggesting a more intricate role for this histone mark in Ectocarpus development than previously appreciated.

Perceptions of organizational culture among infection preventionists in Israel, the United States, and Thailand: Results from national infection prevention surveys.

In national surveys of infection preventionists in Israel (n = 15), the United States (n = 415), and Thailand (n = 100), we found that views of organizational culture track well with these countries' cultural dimension scores of power distance and individualism. Our findings highlight the importance of considering cultural dimensions when implementing infection prevention efforts.

Preventing healthcare-associated MRSA bacteremia: getting to the root of the problem.

Introduction: Bloodstream infections caused by methicillin-resistant Staphylococcus aureus (MRSA) remain a major challenge in most countries worldwide. Setting: We describe a quasi-experimental sequential intervention at Mater Dei Hospital, Malta, to reduce hyper-prevalence of healthcare-associated MRSA bacteremia (HA-MRSA-B). Interventions: The hospital initiated a hand hygiene (HH) campaign in 2008 to improve alcohol hand rub (AHR) use. In 2011, this was followed by root cause analysis (RCA) of all HA-MRSA-B cases and finally universal MRSA admission screening in 2014. Change-point analysis was used to evaluate the impact of the interventions. Results: The effect of the HH campaign became evident when AHR consumption reached 40 L/1000 occupied bed days (BD). RCAs identified intravascular devices as the likely risk factor in 83% of all HA-MRSA-B; specifically non-tunneled double-lumen hemodialysis catheters (36%), peripheral venous cannulas (25%), and central venous catheters (22%). Interventions to improve their management resulted in the greatest reduction of HA-MRSA-B rates. They were informed by the RCA findings and targeted behavior change through education, motivation, and system change. Universal MRSA admission screening provided the final decline in incidence. Each intervention affected HA-MRSA-B rates after a lag period of approximately 18-24 months. Overall, HA-MRSA-B incidence decreased from 1.72 cases/10000BD in 2008 to 0.18/10000BD in 2019; a reduction of almost 90%. Intravenous device interventions were also associated with a reduction of methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia rates. Conclusions: Significant improvement in HA-MRSA-B is possible, even in highly endemic regions. It requires well-planned behavior change interventions which are compatible with local context and culture.

Cell cycle status of male and female gametes during Arabidopsis reproduction.

Fertilization in Arabidopsis (Arabidopsis thaliana) is a highly coordinated process that begins with a pollen tube delivering the 2 sperm cells into the embryo sac. Each sperm cell can then fertilize either the egg or the central cell to initiate embryo or endosperm development, respectively. The success of this double fertilization process requires a tight cell cycle synchrony between the male and female gametes to allow karyogamy (nuclei fusion). However, the cell cycle status of the male and female gametes during fertilization remains elusive as DNA quantification and DNA replication assays have given conflicting results. Here, to reconcile these results, we quantified the DNA replication state by DNA sequencing and performed microscopic analyses of fluorescent markers covering all phases of the cell cycle. We show that male and female Arabidopsis gametes are both arrested prior to DNA replication at maturity and initiate their DNA replication only during fertilization.

Revisiting the personal protective equipment components of transmission-based precautions for the prevention of COVID-19 and other respiratory virus infections in healthcare.

The COVID-19 pandemic highlighted some potential limitations of transmission-based precautions. The distinction between transmission through large droplets vs aerosols, which have been fundamental concepts guiding infection control measures, has been questioned, leading to considerable variation in expert recommendations on transmission-based precautions for COVID-19. Furthermore, the application of elements of contact precautions, such as the use of gloves and gowns, is based on low-quality and inconclusive evidence and may have unintended consequences, such as increased incidence of healthcare-associated infections and spread of multidrug-resistant organisms. These observations indicate a need for high-quality studies to address the knowledge gaps and a need to revisit the theoretical background regarding various modes of transmission and the definitions of terms related to transmission. Further, we should examine the implications these definitions have on the following components of transmission-based precautions: (i) respiratory protection, (ii) use of gloves and gowns for the prevention of respiratory virus infections, (iii) aerosol-generating procedures and (iv) universal masking in healthcare settings as a control measure especially during seasonal epidemics. Such a review would ensure that transmission-based precautions are consistent and rationally based on available evidence, which would facilitate decision-making, guidance development and training, as well as their application in practice.

Red macroalgae in the genomic era.

Rhodophyta (or red algae) are a diverse and species-rich group that forms one of three major lineages in the Archaeplastida, a eukaryotic supergroup whose plastids arose from a single primary endosymbiosis. Red algae are united by several features, such as relatively small intron-poor genomes and a lack of cytoskeletal structures associated with motility like flagella and centrioles, as well as a highly efficient photosynthetic capacity. Multicellular red algae (or macroalgae) are one of the earliest diverging eukaryotic lineages to have evolved complex multicellularity, yet despite their ecological, evolutionary, and commercial importance, they have remained a largely understudied group of organisms. Considering the increasing availability of red algal genome sequences, we present a broad overview of fundamental aspects of red macroalgal biology and posit on how this is expected to accelerate research in many domains of red algal biology in the coming years.

Genetic control of generative cell shape by DUO1 in Arabidopsis.

KEY MESSAGE: The main features of generative cell morphogenesis, formation of a cytoplasmic projection and elongation of the GC body, operate through independent genetic pathways. Male gametogenesis in developing angiosperm pollen involves distinctive changes in cell morphogenesis. Re-shaping and elongation of the generative cell (GC) are linked to the formation of a GC cytoplasmic projection connected to the vegetative cell nucleus. Although genetic control of GC morphogenesis is unknown, we suspected the involvement of the germline-specific MYB transcription factor DUO POLLEN1 (DUO1). We used light and fluorescence microscopy to examine male germline development in pollen of wild-type Arabidopsis and in four allelic duo1 mutants expressing introduced cell markers. Our analysis shows that the undivided GC in duo1 pollen forms a cytoplasmic projection, but the cell body fails to elongate. In contrast GCs of cyclin-dependent kinase function mutants, which fail to divide like duo1 mutants, achieve normal morphogenesis. We conclude that DUO1 has an essential role in the elongation of the GC, but DUO1-independent pathways control the development of the GC cytoplasmic projection. The two main features of GC morphogenesis therefore operate through independently regulated genetic pathways.

A Trendline and Predictive Analysis of the First-Wave COVID-19 Infections in Malta.

Following the first COVID-19 infected cases, Malta rapidly imposed strict lockdown measures, including restrictions on international travel, together with national social distancing measures, such as prohibition of public gatherings and closure of workplaces. The study aimed to elucidate the effect of the intervention and relaxation of the social distancing measures upon the infection rate by means of a trendline analysis of the daily case data. In addition, the study derived a predictive model by fitting historical data of the SARS-CoV-2 positive cases within a two-parameter Weibull distribution, whilst incorporating swab-testing rates, to forecast the infection rate at minute computational expense. The trendline analysis portrayed the wave of infection to fit within a tri-phasic pattern, where the primary phase was imposed with social measure interventions. Following the relaxation of public measures, the two latter phases transpired, where the two peaks resolved without further escalation of national measures. The derived forecasting model attained accurate predictions of the daily infected cases, attaining a high goodness-of-fit, utilising uncensored government-official infection-rate and swabbing-rate data within the first COVID-19 wave in Malta.

General Practitioners', Pharmacists' and Parents' Views on Antibiotic Use and Resistance in Malta: An Exploratory Qualitative Study.

BACKGROUND: Antibiotic resistance (ABR) remains a global health threat that requires urgent action. Antibiotic use is a key driver of ABR and is particularly problematic in the outpatient setting. General practitioners (GPs), the public, and pharmacists therefore play an important role in safeguarding antibiotics. In this study, we aimed to gain a better understanding of the antibiotic prescribing-use-dispensation dynamic in Malta from the perspective of GPs, pharmacists, and parents; Methods: we conducted 8 focus groups with 8 GPs, 24 pharmacists, and 18 parents between 2014 and 2016. Data were analysed using inductive and deductive content analysis; Results: Awareness on antibiotic overuse and ABR was generally high among interviewees although antibiotic use was thought to be improving. Despite this, some believed that antibiotic demand, non-compliance, and over-the-counter dispensing are still a problem. Nevertheless, interviewees believed that the public is more accepting of alternative strategies, such as delayed antibiotic prescription. Both GPs and pharmacists were enthusiastic about their roles as patient educators in raising knowledge and awareness in this context; Conclusions: While antibiotic use and misuse, and knowledge and awareness, were perceived to have improved in Malta, our study suggests that even though stakeholders indicated willingness to drive change, there is still much room for improvement.

Chromatin landscape associated with sexual differentiation in a UV sex determination system.

In many eukaryotes, such as dioicous mosses and many algae, sex is determined by UV sex chromosomes and is expressed during the haploid phase of the life cycle. In these species, the male and female developmental programs are initiated by the presence of the U- or V-specific regions of the sex chromosomes but, as in XY and ZW systems, sexual differentiation is largely driven by autosomal sex-biased gene expression. The mechanisms underlying the regulation of sex-biased expression of genes during sexual differentiation remain elusive. Here, we investigated the extent and nature of epigenomic changes associated with UV sexual differentiation in the brown alga Ectocarpus, a model UV system. Six histone modifications were quantified in near-isogenic lines, leading to the identification of 16 chromatin signatures across the genome. Chromatin signatures correlated with levels of gene expression and histone PTMs changes in males versus females occurred preferentially at genes involved in sex-specific pathways. Despite the absence of chromosome scale dosage compensation and the fact that UV sex chromosomes recombine across most of their length, the chromatin landscape of these chromosomes was remarkably different to that of autosomes. Hotspots of evolutionary young genes in the pseudoautosomal regions appear to drive the exceptional chromatin features of UV sex chromosomes.

MRSA surveillance programmes worldwide: moving towards a harmonised international approach.

Multinational surveillance programmes for methicillin-resistant Staphylococcus aureus (MRSA) are dependent on national structures for data collection. This study aimed to capture the diversity of national MRSA surveillance programmes and to propose a framework for harmonisation of MRSA surveillance. The International Society of Antimicrobial Chemotherapy (ISAC) MRSA Working Group conducted a structured survey on MRSA surveillance programmes and organised a webinar to discuss the programmes' strengths and challenges as well as guidelines for harmonisation. Completed surveys represented 24 MRSA surveillance programmes in 16 countries. Several countries reported separate epidemiological and microbiological surveillance. Informing clinicians and national policy-makers were the most common purposes of surveillance. Surveillance of bloodstream infections (BSIs) was present in all programmes. Other invasive infections were often included. Three countries reported active surveillance of MRSA carriage. Methodology and reporting of antimicrobial susceptibility, virulence factors, molecular genotyping and epidemiological metadata varied greatly. Current MRSA surveillance programmes rely upon heterogeneous data collection systems, which hampers international epidemiological monitoring and research. To harmonise MRSA surveillance, we suggest improving the integration of microbiological and epidemiological data, implementation of central biobanks for MRSA isolate collection, and inclusion of a representative sample of skin and soft-tissue infection cases in addition to all BSI cases.

Comparative transcriptomic analysis reveals conserved programmes underpinning organogenesis and reproduction in land plants.

The appearance of plant organs mediated the explosive radiation of land plants, which shaped the biosphere and allowed the establishment of terrestrial animal life. The evolution of organs and immobile gametes required the coordinated acquisition of novel gene functions, the co-option of existing genes and the development of novel regulatory programmes. However, no large-scale analyses of genomic and transcriptomic data have been performed for land plants. To remedy this, we generated gene expression atlases for various organs and gametes of ten plant species comprising bryophytes, vascular plants, gymnosperms and flowering plants. A comparative analysis of the atlases identified hundreds of organ- and gamete-specific orthogroups and revealed that most of the specific transcriptomes are significantly conserved. Interestingly, our results suggest that co-option of existing genes is the main mechanism for evolving new organs. In contrast to female gametes, male gametes showed a high number and conservation of specific genes, which indicates that male reproduction is highly specialized. The expression atlas capturing pollen development revealed numerous transcription factors and kinases essential for pollen biogenesis and function.

The epigenetic origin of life history transitions in plants and algae.

Plants and algae have a complex life history that transitions between distinct life forms called the sporophyte and the gametophyte. This phenomenon-called the alternation of generations-has fascinated botanists and phycologists for over 170 years. Despite the mesmerizing array of life histories described in plants and algae, we are only now beginning to learn about the molecular mechanisms controlling them and how they evolved. Epigenetic silencing plays an essential role in regulating gene expression during multicellular development in eukaryotes, raising questions about its impact on the life history strategy of plants and algae. Here, we trace the origin and function of epigenetic mechanisms across the plant kingdom, from unicellular green algae through to angiosperms, and attempt to reconstruct the evolutionary steps that influenced life history transitions during plant evolution. Central to this evolutionary scenario is the adaption of epigenetic silencing from a mechanism of genome defense to the repression and control of alternating generations. We extend our discussion beyond the green lineage and highlight the peculiar case of the brown algae. Unlike their unicellular diatom relatives, brown algae lack epigenetic silencing pathways common to animals and plants yet display complex life histories, hinting at the emergence of novel life history controls during stramenopile evolution.

Adverse reactions to Pfizer-BioNTech vaccination of healthcare workers at Malta's state hospital.

BACKGROUND: The long-term control of COVID-19 depends on an effective global vaccination strategy. Protecting healthcare workers (HCWs) from serious infection is critical. Malta, a European country, initiated the vaccination roll-out using Pfizer-BioNTech COVID-19 vaccine targeting HCWs. This study determined vaccination adverse effects (AEs) in this cohort. METHOD: An online survey was disseminated to all HCWs via work email (29/3/21 to 9/4/21) to gather AEs regarding pain, redness and swelling at injection site, fever, chills, fatigue, muscle/joint pains, headache, vomiting and diarrhoea severity following each dose (Likert scale). Descriptive, comparative and multiple binary regression analyses were performed. RESULTS: A response of 30.30% (n = 1480) was achieved with the commonest AEs being pain at injection site (88.92% CI 95%: 87.21-90.42), mostly mild (51%) and moderate (43%). Fatigue was reported by 72.97% (CI 95%: 70.65-75.17), 42% were mild and 41% were moderate. Females reported significantly (P ≤ .05, respectively) more pain (OR: 1.90), redness (OR: 2.49), swelling at injection site (OR: 1.33), fever (OR: 1.74), chills (OR: 2.32), fatigue (OR: 2.43), muscle (OR: 1.54) and joint pains (OR: 2.01), headache (OR: 2.07) and vomiting (OR: 3.43) when adjusted for age and HCW role. Localised AEs were reported following both vaccine doses unlike systemic AEs that were mostly reported after second doses. CONCLUSION: Vaccination benefits outweigh the minor AEs experienced, with females exhibiting a higher susceptibility. The general low vaccination AEs observed within the HCW cohort is encouraging and should help in allaying vaccine hesitancy among the population.

Impact of a Social Marketing Intervention on General Practitioners' Antibiotic Prescribing Practices for Acute Respiratory Tract Complaints in Malta.

Introduction: Antibiotics are commonly prescribed in primary care for acute respiratory tract complaints (aRTCs), often inappropriately. Social marketing interventions could improve prescribing in such settings. We evaluate the impact of a social marketing intervention on general practitioners' (GPs') antibiotic prescribing for aRTCs in Malta. Methods: Changes in GPs' antibiotic prescribing were monitored over two surveillance periods between 2015 and 2018. Primary outcome: change in antibiotic prescription for aRTCs. Secondary outcomes: change in antibiotic prescription: (i) for immediate use, (ii) for delayed antibiotic prescription, (iii) by diagnosis, and (iv) by antibiotic class. Data were analysed using clustered analysis and interrupted time series analysis (ITSA). Results: Of 33 participating GPs, 18 successfully completed the study. Although clustered analyses showed a significant 3% decrease in overall antibiotic prescription (p = 0.024), ITSA showed no significant change overall (p = 0.264). Antibiotic prescription decreased significantly for the common cold (p < 0.001), otitis media (p = 0.044), and sinusitis (p = 0.004), but increased for pharyngitis (p = 0.015). Conclusions: The intervention resulted in modest improvements in GPs' antibiotic prescribing. A more top-down approach will likely be required for future initiatives to be successful in this setting, focusing on diagnostic and prescribing support like rapid diagnostic testing, prescribing guidelines, and standardised delayed antibiotic prescriptions.

Barriers and facilitators to prudent antibiotic prescribing for acute respiratory tract infections: A qualitative study with general practitioners in Malta.

BACKGROUND: Antibiotic resistance is a leading global public health concern and antibiotic use is a key driver. Effective interventions are needed to target key stakeholders, including general practitioners (GPs). In Malta, little is known about factors that influence GPs' antibiotic prescribing, making it challenging to implement targeted interventions. We therefore aimed to explore GPs' understanding of antibiotic use and resistance, and describe their perceived barriers and facilitators to prudent antibiotic prescribing for acute respiratory tract infections in Malta. METHODS: Face-to-face individual semi-structured interviews were held with a quota sample of 20 GPs in 2014. Interviews were audio recorded and transcribed verbatim, and later analysed iteratively using manifest and latent content analysis. Findings were collated in a socioecological model to depict how GPs as individuals are embedded within larger social systems and contexts, and how each component within this system impacts their prescribing behaviour. FINDINGS: We found that GPs' antibiotic prescribing decisions are complex and impacted by numerous barriers and facilitators at the individual, interpersonal, organisational, community, and public policy level. Predominant factors found to impact GPs' antibiotic prescribing included not only intrinsic GP factors such as knowledge, awareness, experience, and misconceptions, but also several external factors. At the interpersonal level, GPs' perceived patient demand and behaviour to be a persistent issue that impacts their prescribing decisions. Similarly, some GPs found pressure from drug reps to be concerning despite being considered an important source of information. Organisational and public policy-level issues such as lack of access to relevant antibiotic prescribing guidelines and current antibiotic resistance data from the community, were also considered major barriers to appropriate antibiotic prescribing. Utilisation of diagnostic testing was found to be low and GPs' perceptions on the introduction of rapid point-of-care tests to support antibiotic prescription decisions, were mixed. CONCLUSION: This study revealed the complexity of the antibiotic prescribing decision and the numerous barriers and facilitators that impact it, visualised through a socioecological model. Addressing GPs' antibiotic prescribing practices will require targeted and coordinated implementation activities at all levels to change behaviour and address misconceptions, whilst also improving the physical and social environment. TRIAL REGISTRATION NUMBER: NCT03218930; https://clinicaltrials.gov/ct2/show/NCT03218930.

Histone variants take center stage in shaping the epigenome.

The dynamic properties of the nucleosome are central to genomic activity. Variants of the core histones that form the nucleosome play a pivotal role in modulating nucleosome structure and function. Despite often small differences in sequence, histone variants display remarkable diversity in genomic deposition and post-translational modification. Here, we summarize the roles played by histone variants in the establishment, maintenance and reprogramming of plant chromatin landscapes, with a focus on histone H3 variants. Deposition of replicative H3.1 during DNA replication controls epigenetic inheritance, while local replacement of H3.1 with H3.3 marks cells undergoing terminal differentiation. Deposition of specialized H3 variants in specific cell types is emerging as a novel mechanism of selective epigenetic reprogramming during the plant life cycle.

Epigenetic reprogramming rewires transcription during the alternation of generations in Arabidopsis.

Alternation between morphologically distinct haploid and diploid life forms is a defining feature of most plant and algal life cycles, yet the underlying molecular mechanisms that govern these transitions remain unclear. Here, we explore the dynamic relationship between chromatin accessibility and epigenetic modifications during life form transitions in Arabidopsis. The diploid-to-haploid life form transition is governed by the loss of H3K9me2 and DNA demethylation of transposon-associated cis-regulatory elements. This event is associated with dramatic changes in chromatin accessibility and transcriptional reprogramming. In contrast, the global loss of H3K27me3 in the haploid form shapes a chromatin accessibility landscape that is poised to re-initiate the transition back to diploid life after fertilisation. Hence, distinct epigenetic reprogramming events rewire transcription through major reorganisation of the regulatory epigenome to guide the alternation of generations in flowering plants.

Each pollen grain from a flowering plant houses sperm, which contain half of the genes needed to make a new plant, and a companion or vegetative cell (VC) that serves to deliver sperm to the egg. The genes in the vegetative cell and those in the sperm are identical to the genes of the plant they come from, so how can this set of identical genetic information produce such different cells? Both DNA and histones, the proteins that pack and order DNA, can be chemically modified locally through a process called methylation. The location of these modifications can affect how genetic information in the DNA is read to make different types of cells. The use of processes like methylation to regulate whether genes are switched on or off is called epigenetics. So what role does epigenetics play in plant pollen? To answer this question, Borg et al. examined the epigenetics of pollen in Arabidopsis thaliana, a widely studied plant and common weed. In vegetative cells, DNA methylation is lost together with a different methylation mark (H3K9me2), which unlocks several genes needed for pollen to transport sperm. By contrast, sperm loses an entirely different methylation mark, called H3K27me3, which unlocks a different set of genes that help to prepare development of a new plant once sperm fertilizes the egg. Through these different set of epigenetic changes, activity increases at different groups of genes that are important for shaping the function of each pollen cell type. These results reveal how the loss of DNA and histone methylation are important for plants to reproduce sexually via pollen. This offers insights into the evolution of plants and other related life forms. Learning about plant reproduction may also help to increase food production by improving crop yields.

A Synthetic Approach to Reconstruct the Evolutionary and Functional Innovations of the Plant Histone Variant H2A.W.

Diversification of histone variants is marked by the acquisition of distinct motifs and functional properties through convergent evolution.1-4 H2A variants are distinguished by specific C-terminal motifs and tend to be segregated within defined domains of the genome.5,6 Whether evolution of these motifs pre-dated the evolution of segregation mechanisms or vice versa has remained unclear. A suitable model to address this question is the variant H2A.W, which evolved in plants through acquisition of a KSPK motif7 and is tightly associated with heterochromatin.4 We used fission yeast, where chromatin is naturally devoid of H2A.W, to study the impact of engineered chimeras combining yeast H2A with the KSPK motif. Biochemical assays showed that the KSPK motif conferred nucleosomes with specific properties. Despite uniform incorporation of the engineered H2A chimeras in the yeast genome, the KSPK motif specifically affected heterochromatin composition and function. We conclude that the KSPK motif promotes chromatin properties in yeast that are comparable to the properties and function of H2A.W in plant heterochromatin. We propose that the selection of functional motifs confer histone variants with properties that impact primarily a specific chromatin state. The association between a new histone variant and a preferred chromatin state can thus provide a setting for the evolution of mechanisms that segregate the new variant to this state, thereby enhancing the impact of the selected properties of the variant on genome activity.