Serum bile acid measurements in women of European and South Asian ethnicity with or without gestational diabetes mellitus: A cohort study.

OBJECTIVE: Investigation of serum bile acid profiles in pregnancies complicated by gestational diabetes mellitus (GDM) in a multi-ethnic cohort of women who are lean or obese. DESIGN: Prospective cohort study. SETTING: UK multicentre study. POPULATION: Fasting serum from participants of European or South Asian self-reported ethnicity from the PRiDE study, between 23 and 31 weeks of gestation. METHODS: Bile acids were measured using ultra-performance liquid chromatography-tandem mass spectrometry. Log-transformed data were analysed using linear regression in STATA/IC 15.0. MAIN OUTCOME MEASURES: Total bile acids (TBAs), C4, fasting glucose and insulin. RESULTS: The TBAs were 1.327-fold (1.105-1.594) increased with GDM in European women (P = 0.003). Women with GDM had 1.162-fold (1.002-1.347) increased levels of the BA synthesis marker C4 (P = 0.047). In South Asian women, obesity (but not GDM) increased TBAs 1.522-fold (1.193-1.942, P = 0.001). Obesity was associated with 1.420-fold (1.185-1.702) increased primary/secondary BA ratio (P < 0.001) related to 1.355-fold (1.140-1.611) increased primary BA concentrations (P = 0.001). TBAs were positively correlated with fasting glucose (P = 0.039) in all women, and with insulin (P = 0.001) and the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (P = 0.001) in women with GDM. CONCLUSIONS: Serum BA homeostasis in late gestation depends on body mass index and GDM in ethnicity-specific ways. This suggests ethnicity-specific aetiologies may contribute to metabolic risk in European and South Asian women, with the relationship between BAs and insulin resistance of greater importance in European women. Further studies into ethnicity-specific precision medicine for GDM are required.

The most impactful endometriosis symptom: An international, cross-sectional, two-round survey study.

INTRODUCTION: There is considerable variation in the types of symptoms experienced by people living with endometriosis, and it is unclear which symptoms impact people the most. This study aimed to identify the specific symptoms that are "most impactful" to people living with the condition. MATERIAL AND METHODS: Two sequential online surveys were conducted. Women aged over 18 years with a diagnosis of endometriosis were eligible to participate. Participants first provided a free-text list of all the endometriosis symptoms they experienced (Survey 1, Australian only). Responses were condensed into a shorter list by grouping symptom types and selecting the top 20 most common and most impactful. Survey 2 (international) participants reviewed the list and selected all that they had experienced in the last 3 months, nominated one as their single "most impactful symptom", and rated its impact on one of five randomized scale types. RESULTS: Survey 1 and Survey 2 had 195 and 983 responses, respectively. The mean age of respondents was 30.8 ± 7.9 years. There were 275 separate symptom descriptions from Survey 1, which were condensed into 104 groups, of which 25 met criteria for inclusion in Survey 2. The most commonly experienced symptoms were abdominal pain (93% of respondents), bloating (92%), and fatigue (90%), and the symptoms nominated as causing the most impact were pelvic pain (20%), abdominal pain (15%), and cramps (7%). Nearly everyone (99.7%) in Survey 2 reported experiencing at least one pain symptom. The symptoms that generated the highest impact scores were infertility (99.8/100), irregular menstrual cycles (95.3/100), and constipation (92/100). The average impact score was 87.5/100. CONCLUSIONS: There was substantial variation in the symptom selected as causing the most impact, and the level of impact was high. A focus on measuring the "most impactful symptom" in future research may enable us to better capture and measure the true symptom experience.

The "most bothersome symptom" construct: A qualitative study of Australians living with endometriosis.

INTRODUCTION: "Improvement in the most bothersome symptom" was recently selected as a core outcome for endometriosis intervention trials. This study aimed to explore the applicability of the construct of "symptom bother" in representing the lived experiences of people with endometriosis. MATERIAL AND METHODS: Semi-structured interviews were conducted to understand the meaning of "symptom bother" and related constructs. Eighteen interviews were conducted: 14 among people with a surgical diagnosis of endometriosis who were recruited from the community, and four with people who were recruited from a private gynecology clinic who had either a confirmed diagnosis or a high suspicion of the disease. All interviews were audio recorded, transcribed verbatim, and analyzed thematically. RESULTS: Three primary themes were identified: (1) endometriosis symptoms and priorities vary with time and context, (2) endometriosis symptoms impair normal daily functioning, (3) endometriosis symptoms are more than just a "bother." The concept of "bother" to describe endometriosis symptoms did not resonate with most participants. Whilst "bother" was familiar language, it did not encompass the broader implications of living with endometriosis. Participants felt "bother" implied emotional distress, lacking a full understanding of the consequences of the disease. Instead, "symptom impact" was endorsed, allowing participants to quantify and objectively assess their symptoms, free from negative connotations. CONCLUSIONS: This was the first qualitative study to explore "symptom bother" among people living with endometriosis. Instead of "bother," "impact" was widely endorsed as a suitable construct. This term more appropriately captured the broad ways in which endometriosis symptoms impair daily functioning.

MRPS25 mutations impair mitochondrial translation and cause encephalomyopathy.

Mitochondrial disorders are clinically and genetically heterogeneous and are associated with a variety of disease mechanisms. Defects of mitochondrial protein synthesis account for the largest subgroup of disorders manifesting with impaired respiratory chain capacity; yet, only a few have been linked to dysfunction in the protein components of the mitochondrial ribosomes. Here, we report a subject presenting with dyskinetic cerebral palsy and partial agenesis of the corpus callosum, while histochemical and biochemical analyses of skeletal muscle revealed signs of mitochondrial myopathy. Using exome sequencing, we identified a homozygous variant c.215C>T in MRPS25, which encodes for a structural component of the 28S small subunit of the mitochondrial ribosome (mS25). The variant segregated with the disease and substitutes a highly conserved proline residue with leucine (p.P72L) that, based on the high-resolution structure of the 28S ribosome, is predicted to compromise inter-protein contacts and destabilize the small subunit. Concordant with the in silico analysis, patient's fibroblasts showed decreased levels of MRPS25 and other components of the 28S subunit. Moreover, assembled 28S subunits were scarce in the fibroblasts with mutant mS25 leading to impaired mitochondrial translation and decreased levels of multiple respiratory chain subunits. Crucially, these abnormalities were rescued by transgenic expression of wild-type MRPS25 in the mutant fibroblasts. Collectively, our data demonstrate the pathogenicity of the p.P72L variant and identify MRPS25 mutations as a new cause of mitochondrial translation defect.

Uniparental isodisomy of chromosome 2 causing MRPL44-related multisystem mitochondrial disease.

Mutations in nuclear-encoded protein subunits of the mitochondrial ribosome are an increasingly recognised cause of oxidative phosphorylation system (OXPHOS) disorders. Among them, mutations in the MRPL44 gene, encoding a structural protein of the large subunit of the mitochondrial ribosome, have been identified in four patients with OXPHOS defects and early-onset hypertrophic cardiomyopathy with or without additional clinical features. A 23-year-old individual with cardiac and skeletal myopathy, neurological involvement, and combined deficiency of OXPHOS complexes in skeletal muscle was clinically and genetically investigated. Analysis of whole-exome sequencing data revealed a homozygous mutation in MRPL44 (c.467 T > G), which was not present in the biological father, and a region of homozygosity involving most of chromosome 2, raising the possibility of uniparental disomy. Short-tandem repeat and genome-wide SNP microarray analyses of the family trio confirmed complete maternal uniparental isodisomy of chromosome 2. Mitochondrial ribosome assembly and mitochondrial translation were assessed in patient derived-fibroblasts. These studies confirmed that c.467 T > G affects the stability or assembly of the large subunit of the mitochondrial ribosome, leading to impaired mitochondrial protein synthesis and decreased levels of multiple OXPHOS components. This study provides evidence of complete maternal uniparental isodisomy of chromosome 2 in a patient with MRPL44-related disease, and confirms that MRLP44 mutations cause a mitochondrial translation defect that may present as a multisystem disorder with neurological involvement.

A community-based program to reduce acute rheumatic fever and rheumatic heart disease in northern Australia.

BACKGROUND: In Australia's north, Aboriginal peoples live with world-high rates of rheumatic heart disease (RHD) and its precursor, acute rheumatic fever (ARF); driven by social and environmental determinants of health. We undertook a program of work to strengthen RHD primordial and primary prevention using a model addressing six domains: housing and environmental support, community awareness and empowerment, health literacy, health and education service integration, health navigation and health provider education. Our aim is to determine how the model was experienced by study participants. METHODS: This is a two-year, outreach-to-household, pragmatic intervention implemented by Aboriginal Community Workers in three remote communities. The qualitative component was shaped by Participatory Action Research. Yarning sessions and semi-structured interviews were conducted with 14 individuals affected by, or working with, ARF/RHD. 31 project field reports were collated. We conducted a hybrid inductive-deductive thematic analysis guided by critical theory. RESULTS: Aboriginal Community Workers were best placed to support two of the six domains: housing and environmental health support and health navigation. This was due to trusting relationships between ACWs and families and the authority attributed to ACWs through the project. ACWs improved health literacy and supported awareness and empowerment; but this was limited by disease complexities. Consequently, ACWs requested more training to address knowledge gaps and improve knowledge transfer to families. ACWs did not have skills to provide health professionals with education or ensure health and education services participated in ARF/RHD. Where knowledge gain among participant family members was apparent, motivation or structural capability to implement behaviour change was lacking in some domains, even though the model was intended to support structural changes through care navigation and housing fixes. CONCLUSIONS: This is the first multi-site effort in northern Australia to strengthen primordial and primary prevention of RHD. Community-led programs are central to the overarching strategy to eliminate RHD. Future implementation should support culturally safe relationships which build the social capital required to address social determinants of health and enable holistic ways to support sustainable individual and community-level actions. Government and services must collaborate with communities to address systemic, structural issues limiting the capacity of Aboriginal peoples to eliminate RHD.

Health seeking behaviours and treatments received by Australian women with vulvodynia: A cross-sectional survey.

BACKGROUND: Vulvodynia is a condition characterised by pain in the vulva lasting more than three months and for which no obvious aetiology can be found. It affects around 8% of women and has significant negative impacts on quality of life. There is a paucity of research on healthcare management pathways and the use of evidence-based treatments in an Australian community setting. AIMS: To explore which healthcare professionals Australian women with vulvodynia seek treatment from, and which treatments are recommended, provided, or prescribed by these healthcare professionals. MATERIALS AND METHODS: A cross-sectional online survey was conducted from May 2019 to August 2019. Women were eligible to participate if they had been diagnosed with vulvodynia by a healthcare professional, were currently living in Australia, and were over 18 years old. RESULTS: Fifty respondents meet the inclusion criteria, with a mean age of 30.5 years. On average, respondents reported seeing four different types of healthcare professionals in the management of their vulvodynia, with general practitioners (GPs) (98%), medical specialists (96%), and physiotherapists (80%) being the three most commonly consulted. Most respondents reported seeing multiple GPs (>87%), multiple medical specialists (>77%), and multiple physiotherapists (50%). The most commonly prescribed interventions were pelvic floor down-training exercises (76%), topical (70%) and oral (70%) medication, and vulvodynia information (56%). CONCLUSIONS: Australian women with vulvodynia seek help from several professionals and receive a variety of treatments for their pain. Of concern is many treatments that are being offered clinically have very little peer-reviewed evidence of effectiveness in vulvodynia.

Enhanced Microbial Bile Acid Deconjugation and Impaired Ileal Uptake in Pregnancy Repress Intestinal Regulation of Bile Acid Synthesis.

Pregnancy is associated with progressive hypercholanemia, hypercholesterolemia, and hypertriglyceridemia, which can result in metabolic disease in susceptible women. Gut signals modify hepatic homeostatic pathways, linking intestinal content to metabolic activity. We sought to identify whether enteric endocrine signals contribute to raised serum bile acids observed in human and murine pregnancies, by measuring fibroblast growth factor (FGF) 19/15 protein and mRNA levels, and 7α-hydroxy-4-cholesten-3-one. Terminal ileal farnesoid X receptor (FXR)-mediated gene expression and apical sodium bile acid transporter (ASBT) protein concentration were measured by qPCR and western blotting. Shotgun whole-genome sequencing and ultra-performance liquid chromatography tandem mass spectrometry were used to determine the cecal microbiome and metabonome. Targeted and untargeted pathway analyses were performed to predict the systemic effects of the altered metagenome and metabolite profiles. Dietary CA supplementation was used to determine whether the observed alterations could be overcome by intestinal bile acids functioning as FXR agonists. Human and murine pregnancy were associated with reduced intestinal FXR signaling, with lower FGF19/15 and resultant increased hepatic bile acid synthesis. Terminal ileal ASBT protein was reduced in murine pregnancy. Cecal bile acid conjugation was reduced in pregnancy because of elevated bile salt hydrolase-producing Bacteroidetes. CA supplementation induced intestinal FXR signaling, which was not abrogated by pregnancy, with strikingly similar changes to the microbiota and metabonome as identified in pregnancy. Conclusion: The altered intestinal microbiota of pregnancy enhance bile acid deconjugation, reducing ileal bile acid uptake and lowering FXR induction in enterocytes. This exacerbates the effects mediated by reduced bile acid uptake transporters in pregnancy. Thus, in pregnant women and mice, there is reduced FGF19/15-mediated hepatic repression of hepatic bile acid synthesis, resulting in hypercholanemia.

Ending rheumatic heart disease in Australia: the evidence for a new approach.

■The RHD Endgame Strategy: the blueprint to eliminate rheumatic heart disease in Australia by 2031 (the Endgame Strategy) is the blueprint to eliminate rheumatic heart disease (RHD) in Australia by 2031. Aboriginal and Torres Strait Islander people live with one of the highest per capita burdens of RHD in the world. ■The Endgame Strategy synthesises information compiled across the 5-year lifespan of the End Rheumatic Heart Disease Centre of Research Excellence (END RHD CRE). Data and results from priority research projects across several disciplines of research complemented literature reviews, systematic reviews and narrative reviews. Further, the experiences of those working in acute rheumatic fever (ARF) and RHD control and those living with RHD to provide the technical evidence for eliminating RHD in Australia were included. ■The lived experience of RHD is a critical factor in health outcomes. All future strategies to address ARF and RHD must prioritise Aboriginal and Torres Strait Islander people's knowledge, perspectives and experiences and develop co-designed approaches to RHD elimination. The environmental, economic, social and political context of RHD in Australia is inexorably linked to ending the disease. ■Statistical modelling undertaken in 2019 looked at the economic and health impacts of implementing an indicative strategy to eliminate RHD by 2031. Beginning in 2019, the strategy would include: reducing household crowding, improving hygiene infrastructure, strengthening primary health care and improving secondary prophylaxis. It was estimated that the strategy would prevent 663 deaths and save the health care system $188 million. ■The Endgame Strategy provides the evidence for a new approach to RHD elimination. It proposes an implementation framework of five priority action areas. These focus on strategies to prevent new cases of ARF and RHD early in the causal pathway from Streptococcus pyogenes exposure to ARF, and strategies that address the critical systems and structural changes needed to support a comprehensive RHD elimination strategy.

Hyperendemic rheumatic heart disease in a remote Australian town identified by echocardiographic screening.

OBJECTIVES: Using echocardiographic screening, to estimate the prevalence of rheumatic heart disease (RHD) in a remote Northern Territory town. DESIGN: Prospective, cross-sectional echocardiographic screening study; results compared with data from the NT rheumatic heart disease register. SETTING, PARTICIPANTS: People aged 5-20 years living in Maningrida, West Arnhem Land (population, 2610, including 2366 Indigenous Australians), March 2018 and November 2018. INTERVENTION: Echocardiographic screening for RHD by an expert cardiologist or cardiac sonographer. MAIN OUTCOME MEASURES: Definite or borderline RHD, based on World Heart Federation criteria; history of acute rheumatic fever (ARF), based on Australian guidelines for diagnosing ARF. RESULTS: The screening participation rate was 72%. The median age of the 613 participants was 11 years (interquartile range, 8-14 years); 298 (49%) were girls or women, and 592 (97%) were Aboriginal Australians. Definite RHD was detected in 32 screened participants (5.2%), including 20 not previously diagnosed with RHD; in five new cases, RHD was classified as severe, and three of the participants involved required cardiac surgery. Borderline RHD was diagnosed in 17 participants (2.8%). According to NT RHD register data at the end of the study period, 88 of 849 people in Maningrida and the surrounding homelands aged 5-20 years (10%) were receiving secondary prophylaxis following diagnoses of definite RHD or definite or probable ARF. CONCLUSION: Passive case finding for ARF and RHD is inadequate in some remote Australian communities with a very high burden of RHD, placing children and young people with undetected RHD at great risk of poor health outcomes. Active case finding by regular echocardiographic screening is required in such areas.

Transcript availability dictates the balance between strand-asynchronous and strand-coupled mitochondrial DNA replication.

Mammalian mitochondria operate multiple mechanisms of DNA replication. In many cells and tissues a strand-asynchronous mechanism predominates over coupled leading and lagging-strand DNA synthesis. However, little is known of the factors that control or influence the different mechanisms of replication, and the idea that strand-asynchronous replication entails transient incorporation of transcripts (aka bootlaces) is controversial. A firm prediction of the bootlace model is that it depends on mitochondrial transcripts. Here, we show that elevated expression of Twinkle DNA helicase in human mitochondria induces bidirectional, coupled leading and lagging-strand DNA synthesis, at the expense of strand-asynchronous replication; and this switch is accompanied by decreases in the steady-state level of some mitochondrial transcripts. However, in the so-called minor arc of mitochondrial DNA where transcript levels remain high, the strand-asynchronous replication mechanism is instated. Hence, replication switches to a strand-coupled mechanism only where transcripts are scarce, thereby establishing a direct correlation between transcript availability and the mechanism of replication. Thus, these findings support a critical role of mitochondrial transcripts in the strand-asynchronous mechanism of mitochondrial DNA replication; and, as a corollary, mitochondrial RNA availability and RNA/DNA hybrid formation offer means of regulating the mechanisms of DNA replication in the organelle.

Clonidine for pain-related distress in Aboriginal children on a penicillin regimen to prevent recurrence of rheumatic fever.

CONTEXT: Indigenous children and adolescents in Australia and globally bear the burden of acute rheumatic fever (ARF). It has been virtually eliminated in well-resourced, developed settings. ARF is an autoimmune response to infection with group A Streptococcus. The mainstay of management is long-acting intramuscular penicillin injections to prevent recurrence of ARF and development of rheumatic heart disease (RHD), comprising valvular pathology and attendant complications. In Australia, penicillin injections are currently prescribed every 28 days for 5-10 years after diagnosis of ARF, depending on cardiac involvement. Adherence to this regimen reduces ARF recurrences and RHD progression. 'Days at risk' of ARF recurrence are calculated as the number of days after day 28 that an injection is not received. Adherence to the injection schedule has been reported as difficult in most global locations due to the painful nature of the injections, the long timeframes of the prescription, young age of patients, access problems and costs in some locations. The newly updated Australian guideline on the prevention, diagnosis and management of ARF and RHD has a chapter dedicated to secondary prophylaxis. This chapter takes into account cultural considerations and advises on ways to minimise pain and distress of injections in children such as pain gate strategies, distraction techniques and concurrent injection of local anaesthetic. ISSUES: Some children continue to find the injection regimen traumatising despite strategies to reduce pain and fear. Clinicians providing the injections to children also find the injecting episodes distressing if pain is not effectively minimised. An Aboriginal Community Controlled Health Service in a remote setting in northern Australia addressed the issue of severe trauma of injection episodes experienced by an Aboriginal boy aged 7 years. Usual strategies were not effective, so advice was sought from an expert anaesthetist at a tertiary hospital. As a result, oral clonidine 3 µg/kg was trialled 45 minutes prior to the penicillin injection. Procedural coaching and monitoring protocols specific to administration of clonidine in children under their care were created by the health service. The initial dose of clonidine was delivered with the child as an inpatient. LESSONS LEARNED: Clonidine was successful in reducing pain related distress and facilitating adherence to the penicillin regimen. Subsequent doses were delivered and monitored in a remote setting by nurses. After 18 months, the boy no longer required clonidine due to his increased coping capacity. A second child was recognised with similar trauma and has been taking clonidine for pre-procedural sedation for 6 months with good effect and no adverse effects. An additional child was similarly prescribed clonidine without success. Failure in that instance was attributed to lack of procedural coaching and receiving the initial dose of clonidine in an emergency department in hurried circumstances. Individualised child-focused and culturally appropriate care in remote settings is feasible: in this instance team planning for use of clonidine and procedural coaching when other measures have failed. However, for children with RHD, or other comorbidities, advice from the child's treating cardiologist is required prior to prescribing clonidine due to possible adverse consequences. These include hypotension and atrioventricular block, which could lead to haemodynamic compromise in the setting of moderate to severe RHD.

Bacterial infection systemically suppresses stomatal density.

Many plant pathogens gain entry to their host via stomata. On sensing attack, plants close these pores to restrict pathogen entry. Here, we show that plants exhibit a second longer term stomatal response to pathogens. Following infection, the subsequent development of leaves is altered via a systemic signal. This reduces the density of stomata formed, thus providing fewer entry points for pathogens on new leaves. Arabidopsis thaliana leaves produced after infection by a bacterial pathogen that infects through the stomata (Pseudomonas syringae) developed larger epidermal pavement cells and stomata and consequently had up to 20% reductions in stomatal density. The bacterial peptide flg22 or the phytohormone salicylic acid induced similar systemic reductions in stomatal density suggesting that they might mediate this effect. In addition, flagellin receptors, salicylic acid accumulation, and the lipid transfer protein AZI1 were all required for this developmental response. Furthermore, manipulation of stomatal density affected the level of bacterial colonization, and plants with reduced stomatal density showed slower disease progression. We propose that following infection, development of new leaves is altered by a signalling pathway with some commonalities to systemic acquired resistance. This acts to reduce the potential for future infection by providing fewer stomatal openings.

Reduced stomatal density in bread wheat leads to increased water-use efficiency.

Wheat is a staple crop, frequently cultivated in water-restricted environments. Improving crop water-use efficiency would be desirable if grain yield can be maintained. We investigated whether a decrease in wheat stomatal density via the manipulation of epidermal patterning factor (EPF) gene expression could improve water-use efficiency. Our results show that severe reductions in stomatal density in EPF-overexpressing wheat plants have a detrimental outcome on yields. However, wheat plants with a more moderate reduction in stomatal density (i.e. <50% reduction in stomatal density on leaves prior to tillering) had yields indistinguishable from controls, coupled with an increase in intrinsic water-use efficiency. Yields of these moderately reduced stomatal density plants were also comparable with those of control plants under conditions of drought and elevated CO2. Our data demonstrate that EPF-mediated control of wheat stomatal development follows that observed in other grasses, and we identify the potential of stomatal density as a tool for breeding wheat plants that are better able to withstand water-restricted environments without yield loss.

Redox regulation of pyruvate kinase M2 by cysteine oxidation and S-nitrosation.

We show here that the M2 isoform of human pyruvate kinase (M2PYK) is susceptible to nitrosation and oxidation, and that these modifications regulate enzyme activity by preventing the formation of the active tetrameric form. The biotin-switch assay carried out on M1 and M2 isoforms showed that M2PYK is sensitive to nitrosation and that Cys326 is highly susceptible to redox modification. Structural and enzymatic studies have been carried out on point mutants for three cysteine residues (Cys424, Cys358, and Cys326) to characterise their potential roles in redox regulation. Nine cysteines are conserved between M2PYK and M1PYK. Cys424 is the only cysteine unique to M2PYK. C424S, C424A, and C424L showed a moderate effect on enzyme activity with 80, 100, and 140% activity, respectively, compared with M2PYK. C358 had been previously identified from in vivo studies to be the favoured target for oxidation. Our characterised mutant showed that this mutation stabilises tetrameric M2PYK, suggesting that the in vivo resistance to oxidation for the Cys358Ser mutation is due to stabilisation of the tetrameric form of the enzyme. In contrast, the Cys326Ser mutant exists predominantly in monomeric form. A biotin-switch assay using this mutant also showed a significant reduction in biotinylation of M2PYK, confirming that this is a major target for nitrosation and probably oxidation. Our results show that the sensitivity of M2PYK to oxidation and nitrosation is regulated by its monomer-tetramer equilibrium. In the monomer state, residues (in particular C326) are exposed to oxidative modifications that prevent reformation of the active tetrameric form.

Cell density and airspace patterning in the leaf can be manipulated to increase leaf photosynthetic capacity.

The pattern of cell division, growth and separation during leaf development determines the pattern and volume of airspace in a leaf. The resulting balance of cellular material and airspace is expected to significantly influence the primary function of the leaf, photosynthesis, and yet the manner and degree to which cell division patterns affect airspace networks and photosynthesis remains largely unexplored. In this paper we investigate the relationship of cell size and patterning, airspace and photosynthesis by promoting and repressing the expression of cell cycle genes in the leaf mesophyll. Using microCT imaging to quantify leaf cellular architecture and fluorescence/gas exchange analysis to measure leaf function, we show that increased cell density in the mesophyll of Arabidopsis can be used to increase leaf photosynthetic capacity. Our analysis suggests that this occurs both by increasing tissue density (decreasing the relative volume of airspace) and by altering the pattern of airspace distribution within the leaf. Our results indicate that cell division patterns influence the photosynthetic performance of a leaf, and that it is possible to engineer improved photosynthesis via this approach.

Formation of the Stomatal Outer Cuticular Ledge Requires a Guard Cell Wall Proline-Rich Protein.

Stomata are formed by a pair of guard cells which have thickened, elastic cell walls to withstand the large increases in turgor pressure that have to be generated to open the pore that they surround. We have characterized FOCL1, a guard cell-expressed, secreted protein with homology to Hyp-rich cell wall proteins. FOCL1-GFP localizes to the guard cell outer cuticular ledge and plants lacking FOCL1 produce stomata without a cuticular ledge. Instead the majority of stomatal pores are entirely covered over by a continuous fusion of the cuticle, and consequently plants have decreased levels of transpiration and display drought tolerance. The focl1 guard cells are larger and less able to reduce the aperture of their stomatal pore in response to closure signals suggesting that the flexibility of guard cell walls is impaired. FOCL1 is also expressed in lateral root initials where it aids lateral root emergence. We propose that FOCL1 acts in these highly specialized cells of the stomata and root to impart cell wall strength at high turgor and/or to facilitate interactions between the cell wall and the cuticle.

ATAD3 gene cluster deletions cause cerebellar dysfunction associated with altered mitochondrial DNA and cholesterol metabolism.

Although mitochondrial disorders are clinically heterogeneous, they frequently involve the central nervous system and are among the most common neurogenetic disorders. Identifying the causal genes has benefited enormously from advances in high-throughput sequencing technologies; however, once the defect is known, researchers face the challenge of deciphering the underlying disease mechanism. Here we characterize large biallelic deletions in the region encoding the ATAD3C, ATAD3B and ATAD3A genes. Although high homology complicates genomic analysis of the ATAD3 defects, they can be identified by targeted analysis of standard single nucleotide polymorphism array and whole exome sequencing data. We report deletions that generate chimeric ATAD3B/ATAD3A fusion genes in individuals from four unrelated families with fatal congenital pontocerebellar hypoplasia, whereas a case with genomic rearrangements affecting the ATAD3C/ATAD3B genes on one allele and ATAD3B/ATAD3A genes on the other displays later-onset encephalopathy with cerebellar atrophy, ataxia and dystonia. Fibroblasts from affected individuals display mitochondrial DNA abnormalities, associated with multiple indicators of altered cholesterol metabolism. Moreover, drug-induced perturbations of cholesterol homeostasis cause mitochondrial DNA disorganization in control cells, while mitochondrial DNA aggregation in the genetic cholesterol trafficking disorder Niemann-Pick type C disease further corroborates the interdependence of mitochondrial DNA organization and cholesterol. These data demonstrate the integration of mitochondria in cellular cholesterol homeostasis, in which ATAD3 plays a critical role. The dual problem of perturbed cholesterol metabolism and mitochondrial dysfunction could be widespread in neurological and neurodegenerative diseases.

Transition to adult care for Aboriginal children with rheumatic fever: a review informed by a focussed ethnography in northern Australia.

Aboriginal children in northern Australia have high rates of rheumatic fever and rheumatic heart disease, which are chronic conditions because of the need for long-term treatment and monitoring. This article critically reviews the literature on transition to adult care for children with chronic conditions and considers applicability to the care of these children. The review was merged with findings from a focussed ethnography conducted in four remote Aboriginal communities with young people who have these conditions. Transition care aims to support adolescents on a healthcare trajectory to facilitate best long-term health and personal outcomes. Characteristics of the two medical conditions, the children and their local health services in northern Australia were generalised and merged with principles from the transition care literature, including policies governing transition clinics in urban locations. In this setting, the challenge is to transition Aboriginal children safely through to adulthood without rheumatic heart damage rather than to a separate health service on reaching adulthood. Recommended tailoring of transition care involves engaging and valuing local navigators who can address language and cultural barriers to provide a sustainable alternative to transition coordinators in mainstream programs. This has potential to improve care without further burdening overstretched clinical resources.