Fixing numbers for matroids

Motivated by work in graph theory, we define the fixing number for a matroid. We give upper and lower bounds for fixing numbers for a general matroid in terms of the size and maximum orbit size (under the action of the matroid automorphism group). We prove the fixing numbers for the cycle matroid and bicircular matroid associated with 3-connected graphs are identical. Many of these results have interpretations through permutation groups, and we make this connection explicit.Comment: This is a major revision of a previous versio

Inter and intra-specific diversity of parasites that cause lymphatic filariasis

AbstractLymphatic filariasis is caused by three closely related nematode parasites: Wuchereria bancrofti, Brugia malayi and Brugia timori. These species have many ecological variants that differ in several aspects of their biology such as mosquito vector species, host range, periodicity, and morphology. Although the genome of B. malayi (the first genome sequenced from a parasitic nematode) has been available for more than five years, very little is known about genetic variability among the lymphatic dwelling filariae. The genetic diversity among these worms is not only interesting from a biological perspective, but it may have important practical implications for the Global Program to Eliminate Lymphatic Filariasis, as the parasites may respond differently to diagnostic tests and/or medical interventions. Therefore, better information on their genetic variability is urgently needed. With improved methods for nucleic acid extraction and recent advances in sequencing chemistry and instrumentation, this gap can be filled relatively inexpensively. Improved information on filarial genetic diversity may increase the chances of success for lymphatic filariasis elimination programs

Localization of Wolbachia-like gene transcripts and peptides in adult Onchocerca flexuosa worms indicates tissue specific expression

BACKGROUND: Most filarial species in the genus Onchocerca depend on Wolbachia endobacteria to successfully carry out their life cycle. O. flexuosa is a Wolbachia-free species, but its genome contains Wolbachia-like sequences presumably obtained from Wolbachia via horizontal gene transfer. Proteogenomic studies have shown that many of these Wolbachia-like sequences are expressed in adult worms. METHODS: Six Wolbachia-like sequences in O. flexuosa were chosen for further study based on their sequence conservation with Wolbachia genes, length of predicted open reading frames, and expression at the RNA and/or protein levels. In situ hybridization and immunohistochemical labeling were used to localize Wolbachia-like transcripts and peptides in adult worm tissues. RESULTS: RNA probes representing three of the six target sequences produced hybridization signals in worm tissues. These probes bound to transcripts in the intestine and lateral chords of both sexes, in the hypodermis, median chords and uteri in females, and in sperm precursor cells in males. Antibodies raised to three peptides corresponding to these transcripts bound to specific bands in a soluble extract of adult O. flexuosa by Western blot that were not labeled by control antibodies in pre-immune serum. Two of the three antibodies produced labeling patterns in adult worm sections that were similar to those of the RNA probes, while the third produced a different pattern. CONCLUSIONS: A subset of the Wolbachia-like sequences present in the genome of the Wolbachia-free filarial species O. flexuosa are transcribed in tissues where Wolbachia reside in infected filarial species. Some of the peptides and/or proteins derived from these transcripts appear to be concentrated in the same tissues while others may be exported to other regions of the worm. These results suggest that horizontally transferred Wolbachia genes and gene products may replicate important Wolbachia functions in uninfected filarial worms

Ariel - Volume 4 Number 5

Editors David A. Jacoby Eugenia Miller Tom Williams Associate Editors Paul Bialas Terry Burt Michael Leo Gail Tenikat Editor Emeritus and Business Manager Richard J. Bonnano Movie Editor Robert Breckenridge Staff Richard. Blutstein Mary F. Buechler Alice M. Johnson J.D. Kanofskv Rocky Webe

Systems biology studies of adult Paragonimus lung flukes facilitate the identification of immunodominant parasite antigens

Paragonimiasis is a food-borne trematode infection acquired by eating raw or undercooked crustaceans. It is a major public health problem in the far East, but it also occurs in South Asia, Africa, and in the Americas. Paragonimus worms cause chronic lung disease with cough, fever and hemoptysis that can be confused with tuberculosis or other non-parasitic diseases. Treatment is straightforward, but diagnosis is often delayed due to a lack of reliable parasitological or serodiagnostic tests. Hence, the purpose of this study was to use a systems biology approach to identify key parasite proteins that may be useful for development of improved diagnostic tests.The transcriptome of adult Paragonimus kellicotti was sequenced with Illumina technology. Raw reads were pre-processed and assembled into 78,674 unique transcripts derived from 54,622 genetic loci, and 77,123 unique protein translations were predicted. A total of 2,555 predicted proteins (from 1,863 genetic loci) were verified by mass spectrometric analysis of total worm homogenate, including 63 proteins lacking homology to previously characterized sequences. Parasite proteins encoded by 321 transcripts (227 genetic loci) were reactive with antibodies from infected patients, as demonstrated by immunoaffinity purification and high-resolution liquid chromatography-mass spectrometry. Serodiagnostic candidates were prioritized based on several criteria, especially low conservation with proteins in other trematodes. Cysteine proteases, MFP6 proteins and myoglobins were abundant among the immunoreactive proteins, and these warrant further study as diagnostic candidates.The transcriptome, proteome and immunolome of adult P. kellicotti represent a major advance in the study of Paragonimus species. These data provide a powerful foundation for translational research to develop improved diagnostic tests. Similar integrated approaches may be useful for identifying novel targets for drugs and vaccines in the future

Exploring co-production of accessible digital mental health tools in collaboration with young people from marginalised backgrounds:A Scoping Review

ContextDespite evidence that digital mental health supports can improve young people’s access to mental health care, guidance on the most appropriate co-production processes for engaging youth in designing and evaluating these technologies is lacking. User input is critical in digital mental health solutions, particularly for marginalised young people who are often excluded from co-production processes.AimsTo explore the extant literature on co-production processes with marginalised youth in digital mental health supports, ranging from mental health promotion to targeted interventions. A scoping review was chosen to map and summarise the evidence and identify knowledge gaps.MethodThe search spanned 12 databases, including studies from 2021 onwards, focused on co-production with young people aged 16-25 in different stages of designing and assessing digital mental health technologies, especially those who are marginalised.ResultsAfter the screening process, 20 studies were included in the review. Design (n=8) and overall evaluation of the co-design process (n=5) were the primary study foci, with qualitative (n=10) and mixed methods (n=7) dominating the study designs. Most studies utilised human support with a digital component (n=15), while a small number (n=5) used a digital only approach. Promotion/ primary prevention was the dominant study focus (n=16), while four studies addressed targeted interventions. Common study areas included mental wellbeing (n=8), coping/resilience and help-seeking (n=3), followed by interventions addressing stress (n=2), depression (n=2) and anxiety (n=2), but also substance abuse, trauma, and suicide. 8 studies recruited participants through social media, while 6 recruited through health care settings, schools/universities (n=5) or community partners (n=3). In terms of marginalised youth, studies mostly comprised LGBTQ+ (n=12) and ethnic minorities (n=10), and sample sizes averaged 745 in quantitative studies to 22 for qualitative studies.ConclusionThis review covers the co-production processes of design, implementation, evaluation and overall evaluation of co- producing digital mental health supports with marginalised youth. The review highlights youth involvement primarily in design and overall evaluations, with apps being the type of digital mental health support in 6 of those studies and surveys and workshops the most common approaches to involving youth. Overall evaluation studies predominantly focus on promotion/primary prevention and the LGBTQ+ community. There is a need for more consistent user input from marginalised youth such as those with disability, rurally isolated, unemployed/ out of education and immigrants in not only the design stage, but also during implementation, and assessment of digital mental health supports.ImplicationThe findings have clear implications for advancing the inclusion of marginalised youth in the co-production of digital mental health supports and ensuring more effective use of digital technologies in youth mental health services.<br/

Preliminary findings from a scoping review on co-producing accessible digital mental health tools in partnership with marginalized young people

Despite evidence that digital mental health supports can improve young people's access to mental health care, guidance on the most appropriate co-production processes for engaging youth in designing and evaluating these technologies is lacking. User input is critical in digital mental health solutions, particularly for marginalised young people who are often excluded from co-production processes.The aim was to explore the extant literature on co-production processes with marginalised youth in digital mental health supports, ranging from mental health promotion to targeted interventions to serve as the basis for our wider, youth-led project, including a qualitative exploration of digital mental health challenges facing young people across the island of Ireland; identifying, with young people, appropriate digital mental health apps and interventions; validating, in partnership with young people, what digital mental health interventions work; and using these findings to inform policy and practice recommendations for health providers across the island of Ireland and beyond.The scoping review was guided by Arksey and O’Malley’s framework and PRISMA-ScR. The search spanned 12 databases, including studies from 2021 onwards, focused on co-production with young people aged 16-25 in different stages of designing and assessing digital mental health technologies, especially those who are marginalised. Twenty-two studies were identified as meeting the inclusion criteria. Preliminary findings suggest that young people are mainly involved in the initial design phase (n=8) or overall evaluations (n=5) of digital mental health supports and that studies use primarily qualitative (e.g. focus groups and interviews; n=10) or mixed methods (=7) rather than participatory design for co- production.Implications of these findings will be discussed in light of feedback received from the wider project’s youth panel and service provider advisory board to showcase a) the multifaceted concept of co- production and b) how to best translate it into practice to achieve truly youth-led results

Preliminary findings from a scoping review on co-production of accessible digital mental health tools in collaboration with young people from marginalised backgrounds

Despite evidence that digital mental health supports can improve young people's access to mental health care, guidance on the most appropriate co-production processes for engaging youth in designing and evaluating these technologies is lacking. User input is critical in digital mental health solutions, particularly for marginalised young people who are often excluded from co-production processes. The aim was to explore the extant literature on co-production processes with marginalised youth in digital mental health supports, ranging from mental health promotion to targeted interventions.The search spanned 12 databases, including studies from 2021 onwards, focused on co-production with young people aged 16-25 in different stages of designing and assessing digital mental health technologies, especially those who are marginalised.22 studies identified with young people mainly involved in initial design (n=8) or overall evaluation (n=5). 16 studies focused on mental health promotion and apps (n=8) and web-based (n=4) were the most popular digital means.<br/

Landscape of Digital Mental Health Interventions for Youth Aged 12-25

Young people’s mental health is a growing global public concern. Digital mental health interventions offer a cost-effective and accessible solution to complement traditional care, reaching those facing difficulties accessing in-person support. These interventions show promise in enhancing mental health outcomes and can be a valuable component to a comprehensive strategy for young people's well-being.A scoping review was conducted to explore the range of digital solutions to support young people’s mental health. The review included studies that focus on mental wellbeing, mental health, and mental illness, including all types of digital interventions. All types of studies, published from 2017 onwards with a population of young people between ages of 12-25 and validated pre and post mental health or wellbeing primary outcome measure, were included. The search was conducted in 6 databases, initially returning 8,227 records. After screening, 146 studies were included in the final review.Half of the studies recruited participants from the general population who weren’t experiencing mental ill health (n=72, 49%), around a third recruited participants experiencing mental ill health symptoms (n=44, 30%), and 14% (n=21) studies included participants with a mental health diagnosis. Most studies utilised a digital only approach, where the entire intervention was delivered though a digital tool (n=80, 55%) while 45% used a blended approach, where participants used a digital intervention with some degree of human support. However, these figures differed depending on the study population (Figure 1). The most common type of digital tool used was websites (n=79, 54%), followed by apps (n=50, 34%), apps or websites with another tool such as wearables or telehealth (n=7, 5%), chatbots (n=6, 4%), virtual reality (n=2, 1%), text messaging (n=1, &lt;1%) and emails (n=1, &lt;1%). Studies predominately recruited females making up an overage of 70% population, while males accounted for 30% on average. Only 31 out of 146 studies included participants of other genders. Retention rates ranged from 2-100%, with an average of 66% of participants completing the studies. This review highlights the range of digital approaches used with young people, but also the lack of diversity in youth digital mental health study populations. Future work should seek to include more representative populations and overcome barriers to engagement with digital mental health supports. <br/

Comparing the mitochondrial genomes of Wolbachia-dependent and independent filarial nematode species

BACKGROUND: Many species of filarial nematodes depend on Wolbachia endobacteria to carry out their life cycle. Other species are naturally Wolbachia-free. The biological mechanisms underpinning Wolbachia-dependence and independence in filarial nematodes are not known. Previous studies have indicated that Wolbachia have an impact on mitochondrial gene expression, which may suggest a role in energy metabolism. If Wolbachia can supplement host energy metabolism, reduced mitochondrial function in infected filarial species may account for Wolbachia-dependence. Wolbachia also have a strong influence on mitochondrial evolution due to vertical co-transmission. This could drive alterations in mitochondrial genome sequence in infected species. Comparisons between the mitochondrial genome sequences of Wolbachia-dependent and independent filarial worms may reveal differences indicative of altered mitochondrial function. RESULTS: The mitochondrial genomes of 5 species of filarial nematodes, Acanthocheilonema viteae, Chandlerella quiscali, Loa loa, Onchocerca flexuosa, and Wuchereria bancrofti, were sequenced, annotated and compared with available mitochondrial genome sequences from Brugia malayi, Dirofilaria immitis, Onchocerca volvulus and Setaria digitata. B. malayi, D. immitis, O. volvulus and W. bancrofti are Wolbachia-dependent while A. viteae, C. quiscali, L. loa, O. flexuosa and S. digitata are Wolbachia-free. The 9 mitochondrial genomes were similar in size and AT content and encoded the same 12 protein-coding genes, 22 tRNAs and 2 rRNAs. Synteny was perfectly preserved in all species except C. quiscali, which had a different order for 5 tRNA genes. Protein-coding genes were expressed at the RNA level in all examined species. In phylogenetic trees based on mitochondrial protein-coding sequences, species did not cluster according to Wolbachia dependence. CONCLUSIONS: Thus far, no discernable differences were detected between the mitochondrial genome sequences of Wolbachia-dependent and independent species. Additional research will be needed to determine whether mitochondria from Wolbachia-dependent filarial species show reduced function in comparison to the mitochondria of Wolbachia-independent species despite their sequence-level similarities