The ability and safety of community-based health workers to safely initiate lifesaving therapies for pre-eclampsia in Ogun State, Nigeria: An analysis of 260 community treatments with MgSO4 and/or methyldopa.

OBJECTIVES: To evaluate community-based health workers' ability to identify cases of hypertension in pregnancy, safely deliver methyldopa and magnesium sulphate and make referrals when appropriate. STUDY DESIGN: This was part of Nigeria Community-Level Interventions for Pre-eclampsia (CLIP) cluster randomized controlled trial (NCT01911494). Community-based Health Workers (CHW) recruited pregnant women from five Local Government Areas (clusters) and used mobile health aid for clinical assessment of pre-eclampsia. MAIN OUTCOME MEASURES: The primary outcome was the number of adverse events that occurred after the administration of magnesium sulphate and/or methyldopa to pregnant women by CHWs. FINDINGS: Of 8790 women receiving mobile health-guided care, community-based health workers in Nigeria provided 309 women with hypertension (4.2% of delivered women), and safely administered 142 doses of intramuscular magnesium sulphate. Community Heath Extension Workers (CHEWs) and nurses gave fifty-two and sixty-seven doses of intramuscular magnesium sulphate respectively, twenty-three doses were given by other health care workers (midwives, community health officers, health assistants). The high rate of administration by nurses can be explained by turf protection as well as their seniority within the health system. Also, CHEWs and nurses gave 124 doses of oral methyldopa and 126 urgent referrals were completed. There were no complications related to administration of treatment or referral. INTERPRETATION: These findings demonstrate the ability of community-based health workers to safely administer methyldopa and intramuscular magnesium sulphate. The use of task-sharing, therefore, could drastically reduce the three delays (triage, transport and treatment) associated with high maternal mortality and morbidity in rural communities in low- and middle-income countries.

Community-level interventions for pre-eclampsia (CLIP) in Pakistan: A cluster randomised controlled trial.

OBJECTIVES: To reduce all-cause maternal and perinatal mortality and major morbidity through Lady Health Worker (LHW)-facilitated community engagement and early diagnosis, stabilization and referral of women with preeclampsia, an important contributor to adverse maternal and perinatal outcomes given delays in early detection and initial management. STUDY DESIGN: In the Pakistan Community-Level Interventions for Pre-eclampsia (CLIP) cluster randomized controlled trial (NCT01911494), LHWs engaged the community, recruited pregnant women from 20 union councils (clusters), undertook mobile health-guided clinical assessment for preeclampsia, and referral to facilities after stabilization. MAIN OUTCOME MEASURES: The primary outcome was a composite of maternal, fetal and newborn mortality and major morbidity. FINDINGS: We recruited 39,446 women in intervention (N = 20,264) and control clusters (N = 19,182) with minimal loss to follow-up (3∙7% vs. 4∙5%, respectively). The primary outcome did not differ between intervention (26·6%) and control (21·9%) clusters (adjusted odds ratio, aOR, 1∙20 [95% confidence interval 0∙84-1∙72]; p = 0∙31). There was reduction in stillbirths (0·89 [0·81-0·99]; p = 0·03), but no impact on maternal death (1·08 [0·69, 1·71]; p = 0·74) or morbidity (1·12 [0·57, 2·16]; p = 0·77); early (0·95 [0·82-1·09]; p = 0·46) or late neonatal deaths (1·23 [0·97-1·55]; p = 0·09); or neonatal morbidity (1·22 [0·77, 1·96]; p = 0·40). Improvements in outcome rates were observed with 4-7 (p = 0·015) and ≥8 (p < 0·001) (vs. 0) CLIP contacts. INTERPRETATION: The CLIP intervention was well accepted by the community and implemented by LHWs. Lack of effects on adverse outcomes could relate to quality care for mothers with pre-eclampsia in health facilities. Future strategies for community outreach must also be accompanied by health facility strengthening. FUNDING: The University of British Columbia (PRE-EMPT), a grantee of the Bill & Melinda Gates Foundation (OPP1017337).

Community level interventions for pre-eclampsia (CLIP) in India: A cluster randomised controlled trial.

OBJECTIVES: Pregnancy hypertension is associated with 7.1% of maternal deaths in India. The objective of this trial was to assess whether task-sharing care might reduce adverse pregnancy outcomes related to delays in triage, transport, and treatment. STUDY DESIGN: The Indian Community-Level Interventions for Pre-eclampsia (CLIP) open-label cluster randomised controlled trial (NCT01911494) recruited pregnant women in 12 clusters (initial four-cluster internal pilot) in Belagavi and Bagalkote, Karnataka. The CLIP intervention (6 clusters) consisted of community engagement, community health workers (CHW) provided mobile health (mHeath)-guided clinical assessment, initial treatment, and referral to facility either urgently (<4 h) or non-urgently (<24 h), dependent on algorithm-defined risk. Treatment effect was estimated by multi-level logistic regression modelling, adjusted for prognostically-significant baseline variables. Predefined secondary analyses included safety and evaluation of the intensity of mHealth-guided CHW-provided contacts. MAIN OUTCOME MEASURES: 20% reduction in composite of maternal, fetal, and newborn mortality and major morbidity. RESULTS: All 14,783 recruited pregnancies (7839 intervention, 6944 control) were followed-up. The primary outcome did not differ between intervention and control arms (adjusted odds ratio (aOR) 0.92 [95% confidence interval 0.74, 1.15]; p = 0.47; intraclass correlation coefficient 0.013). There were no intervention-related safety concerns following administration of either methyldopa or MgSO4, and 401 facility referrals. Compared with intervention arm women without CLIP contacts, those with ≥8 contacts suffered fewer stillbirths (aOR 0.19 [0.10, 0.35]; p < 0.001), at the probable expense of survivable neonatal morbidity (aOR 1.39 [0.97, 1.99]; p = 0.072). CONCLUSIONS: As implemented, solely community-level interventions focussed on pre-eclampsia did not improve outcomes in northwest Karnataka.

Community-level interventions for pre-eclampsia (CLIP) in Mozambique: A cluster randomised controlled trial.

OBJECTIVES: Pregnancy hypertension is the third leading cause of maternal mortality in Mozambique and contributes significantly to fetal and neonatal mortality. The objective of this trial was to assess whether task-sharing care might reduce adverse pregnancy outcomes related to delays in triage, transport, and treatment. STUDY DESIGN: The Mozambique Community-Level Interventions for Pre-eclampsia (CLIP) cluster randomised controlled trial (NCT01911494) recruited pregnant women in 12 administrative posts (clusters) in Maputo and Gaza Provinces. The CLIP intervention (6 clusters) consisted of community engagement, community health worker-provided mobile health-guided clinical assessment, initial treatment, and referral to facility either urgently (<4hrs) or non-urgently (<24hrs), dependent on algorithm-defined risk. Treatment effect was estimated by multi-level logistic regression modelling, adjusted for prognostically-significant baseline variables. Predefined secondary analyses included safety and evaluation of the intensity of CLIP contacts. MAIN OUTCOME MEASURES: 20% reduction in composite of maternal, fetal, and newborn mortality and major morbidity. RESULTS: 15,013 women (15,123 pregnancies) were recruited in intervention (N = 7930; 2·0% loss to follow-up (LTFU)) and control (N = 7190; 2·8% LTFU) clusters. The primary outcome did not differ between intervention and control clusters (adjusted odds ratio (aOR) 1·31, 95% confidence interval (CI) [0·70, 2·48]; p = 0·40). Compared with intervention arm women without CLIP contacts, those with ≥8 contacts experienced fewer primary outcomes (aOR 0·79 (95% CI 0·63, 0·99); p = 0·041), primarily due to improved maternal outcomes (aOR 0·72 (95% CI 0·53, 0·97); p = 0·033). INTERPRETATION: As generally implemented, the CLIP intervention did not improve pregnancy outcomes; community implementation of the WHO eight contact model may be beneficial. FUNDING: The University of British Columbia (PRE-EMPT), a grantee of the Bill & Melinda Gates Foundation (OPP1017337).

The PRECISE (PREgnancy Care Integrating translational Science, Everywhere) database: open-access data collection in maternal and newborn health.

In less-resourced settings, adverse pregnancy outcome rates are unacceptably high. To effect improvement, we need accurate epidemiological data about rates of death and morbidity, as well as social determinants of health and processes of care, and from each country (or region) to contextualise strategies. The PRECISE database is a unique core infrastructure of a generic, unified data collection platform. It is built on previous work in data harmonisation, outcome and data field standardisation, open-access software (District Health Information System 2 and the Baobab Laboratory Information Management System), and clinical research networks. The database contains globally-recommended indicators included in Health Management Information System recording and reporting forms. It comprises key outcomes (maternal and perinatal death), life-saving interventions (Human Immunodeficiency Virus testing, blood pressure measurement, iron therapy, uterotonic use after delivery, postpartum maternal assessment within 48 h of birth, and newborn resuscitation, immediate skin-to-skin contact, and immediate drying), and an additional 17 core administrative variables for the mother and babies. In addition, the database has a suite of additional modules for 'deep phenotyping' based on established tools. These include social determinants of health (including socioeconomic status, nutrition and the environment), maternal co-morbidities, mental health, violence against women and health systems. The database has the potential to enable future high-quality epidemiological research integrated with clinical care and discovery bioscience.

The feasibility of task-sharing the identification, emergency treatment, and referral for women with pre-eclampsia by community health workers in India.

BACKGROUND: Hypertensive disorders are the second highest direct obstetric cause of maternal death after haemorrhage, accounting for 14% of maternal deaths globally. Pregnancy hypertension contributes to maternal deaths, particularly in low- and middle-income countries, due to a scarcity of doctors providing evidence-based emergency obstetric care. Task-sharing some obstetric responsibilities may help to reduce the mortality rates. This study was conducted to assess acceptability by the community and other healthcare providers, for task-sharing by community health workers (CHW) in the identification and initial care in hypertensive disorders in pregnancy. METHODS: This study was conducted in two districts of Karnataka state in south India. A total of 14 focus group discussions were convened with various community representatives: women of reproductive age (N = 6), male decision-makers (N = 2), female decision-makers (N = 3), and community leaders (N = 3). One-to-one interviews were held with medical officers (N = 2), private healthcare OBGYN specialists (N = 2), senior health administrators (N = 2), Taluka (county) health officers (N = 2), and obstetricians (N = 4). All data collection was facilitated by local researchers familiar with the setting and language. Data were subsequently transcribed, translated and analysed thematically using NVivo 10 software. RESULTS: There was strong community support for home visits by CHW to measure the blood pressure of pregnant women; however, respondents were concerned about their knowledge, training and effectiveness. The treatment with oral antihypertensive agents and magnesium sulphate in emergencies was accepted by community representatives but medical practitioners and health administrators had reservations, and insisted on emergency transport to a higher facility. The most important barriers for task-sharing were concerns regarding insufficient training, limited availability of medications, the questionable validity of blood pressure devices, and the ability of CHW to correctly diagnose and intervene in cases of hypertensive disorders of pregnancy. CONCLUSION: Task-sharing to community-based health workers has potential to facilitate early diagnosis of the hypertensive disorders of pregnancy and assist in the provision of emergency care. We identified some facilitators and barriers for successful task-sharing of emergency obstetric care aimed at reducing mortality and morbidity due to hypertensive disorders of pregnancy.

Magnesium sulphate for the management of preeclampsia and eclampsia in low and middle income countries: a systematic review of tested dosing regimens.

OBJECTIVE: To review systematically the magnesium sulphate (MgSO4) dosing regimens tested in low and middle income countries (LMICs) for women with preeclampsia (prevention) and/or eclampsia (treatment). DATA SOURCES: We searched Medline, EMBASE, IPA, CINAHL, CDSR, and CENTRAL databases for relevant English language publications. STUDY SELECTION: Our search yielded 753 publications, of which 26 (10 randomized controlled trials and 16 observational studies) evaluated MgSO4 for preeclampsia and/or eclampsia in World Bank-classified LMICs. DATA EXTRACTION: Independent, by two authors. DATA SYNTHESIS: Twenty-five studies were conducted in hospital settings and one in the community. Rates of eclampsia were usually < 5% (median 3.0%, range 0.0% to 26.5%) even when MgSO4 was administered for eclampsia. When dosage varied from the standard Pritchard or Zuspan regimens, almost all (n = 22) reduced the dose or duration of treatment, most commonly because of concerns about maternal safety, cost, or resource availability. Four trials of a loading dose only (4 g IV + 10 g IM) versus loading plus maintenance dosing of 5 g/4 hr IM found no difference in eclampsia recurrence (RR 1.64; 95% CI 0.48 to 5.65, n = 396). One study documented less eclampsia recurrence associated with community administration of a MgSO4 loading dose before referral to a care facility versus treatment in a care facility (RR 0.23; 95% CI 0.11 to 0.49, n = 265). CONCLUSION: Use of MgSO4 for eclampsia treatment and prevention has been well-studied in LMICs, but concern remains about potential toxicity. Further studies are needed to identify the minimum effective dosage of MgSO4 for management of preeclampsia and eclampsia and whether MgSO4 loading can be safely administered in the community.

Objectif : Procéder à une analyse systématique des schémas posologiques de sulfate de magnésium (MgSO4) mis à l'essai dans des pays à revenu faible ou intermédiaire (PRFI) chez des femmes présentant une prééclampsie (prévention) et/ou une éclampsie (traitement). Sources de données : Nous avons mené des recherches dans les bases de données Medline, EMBASE, IPA, CINAHL, CDSR et CENTRAL afin d'en tirer les publications anglophones pertinentes. Sélection des études : Notre recherche nous a menés à 753 publications, dont 26 (10 essais comparatifs randomisés et 16 études observationnelles) ont évalué l'utilisation de MgSO4 dans des cas de prééclampsie et/ou d'éclampsie au sein de PRFI identifiés par la Banque mondiale. Extraction de données : Indépendante, menée par deux auteurs. Synthèse des données : Vingt-cinq études ont été menées en milieu hospitalier et une étude l'a été en milieu communautaire. Les taux d'éclampsie étaient habituellement inférieurs à 5 % (médiane : 3,0 %, plage : 0,0 % - 26,5 %) même lorsque du MgSO4 était administré pour contrer l'éclampsie. Lorsque les posologies utilisées s'éloignaient des posologies standard Pritchard ou Zuspan, pratiquement chacune d'entre elles (n = 22) réduisait la dose de MgSO4 ou la durée du traitement, la raison la plus couramment citée étant la présence de préoccupations au sujet de la sûreté maternelle, des coûts ou de la disponibilité des ressources. Quatre essais ayant comparé le seul recours à une dose de mise en charge (4 g IV + 10 g IM) au recours à une dose de mise en charge et à une dose d'entretien de 5 g/4 h IM n'ont constaté aucune différence en matière de récurrence de l'éclampsie (RR, 1,64; IC à 95 %, 0,48 - 5,65, n = 396). Une étude a constaté une récurrence moindre de l'éclampsie associée à l'administration d'une dose de mise en charge de MgSO4 en milieu communautaire avant l'orientation vers un établissement de soins, par comparaison avec l'administration d'un tel traitement au sein d'un établissement de soins (RR, 0,23; IC à 95 %, 0,11 - 0,49, n = 265). Conclusion : Bien que l'utilisation de MgSO4 aux fins de la prévention et de la prise en charge de l'éclampsie ait bien été étudiée au sein des PRFI, des préoccupations subsistent quant à sa toxicité potentielle. La tenue d'autres études s'avère requise pour identifier la posologie minimale efficace de MgSO4 pour la prise en charge de la prééclampsie et de l'éclampsie, ainsi que pour déterminer si une dose de mise en charge de MgSO4 peut être administrée en toute sûreté en milieu communautaire.

Identification of 526 conserved metazoan genetic innovations exposes a new role for cofactor E-like in neuronal microtubule homeostasis.

The evolution of metazoans from their choanoflagellate-like unicellular ancestor coincided with the acquisition of novel biological functions to support a multicellular lifestyle, and eventually, the unique cellular and physiological demands of differentiated cell types such as those forming the nervous, muscle and immune systems. In an effort to understand the molecular underpinnings of such metazoan innovations, we carried out a comparative genomics analysis for genes found exclusively in, and widely conserved across, metazoans. Using this approach, we identified a set of 526 core metazoan-specific genes (the 'metazoanome'), approximately 10% of which are largely uncharacterized, 16% of which are associated with known human disease, and 66% of which are conserved in Trichoplax adhaerens, a basal metazoan lacking neurons and other specialized cell types. Global analyses of previously-characterized core metazoan genes suggest a prevalent property, namely that they act as partially redundant modifiers of ancient eukaryotic pathways. Our data also highlights the importance of exaptation of pre-existing genetic tools during metazoan evolution. Expression studies in C. elegans revealed that many metazoan-specific genes, including tubulin folding cofactor E-like (TBCEL/coel-1), are expressed in neurons. We used C. elegans COEL-1 as a representative to experimentally validate the metazoan-specific character of our dataset. We show that coel-1 disruption results in developmental hypersensitivity to the microtubule drug paclitaxel/taxol, and that overexpression of coel-1 has broad effects during embryonic development and perturbs specialized microtubules in the touch receptor neurons (TRNs). In addition, coel-1 influences the migration, neurite outgrowth and mechanosensory function of the TRNs, and functionally interacts with components of the tubulin acetylation/deacetylation pathway. Together, our findings unveil a conserved molecular toolbox fundamental to metazoan biology that contains a number of neuronally expressed and disease-related genes, and reveal a key role for TBCEL/coel-1 in regulating microtubule function during metazoan development and neuronal differentiation.

Allelic ratios and the mutational landscape reveal biologically significant heterozygous SNVs.

The issue of heterozygosity continues to be a challenge in the analysis of genome sequences. In this article, we describe the use of allele ratios to distinguish biologically significant single-nucleotide variants from background noise. An application of this approach is the identification of lethal mutations in Caenorhabditis elegans essential genes, which must be maintained by the presence of a wild-type allele on a balancer. The h448 allele of let-504 is rescued by the duplication balancer sDp2. We readily identified the extent of the duplication when the percentage of read support for the lesion was between 70 and 80%. Examination of the EMS-induced changes throughout the genome revealed that these mutations exist in contiguous blocks. During early embryonic division in self-fertilizing C. elegans, alkylated guanines pair with thymines. As a result, EMS-induced changes become fixed as either G→A or C→T changes along the length of the chromosome. Thus, examination of the distribution of EMS-induced changes revealed the mutational and recombinational history of the chromosome, even generations later. We identified the mutational change responsible for the h448 mutation and sequenced PCR products for an additional four alleles, correlating let-504 with the DNA-coding region for an ortholog of a NFκB-activating protein, NKAP. Our results confirm that whole-genome sequencing is an efficient and inexpensive way of identifying nucleotide alterations responsible for lethal phenotypes and can be applied on a large scale to identify the molecular basis of essential genes.

Fine tuning of RFX/DAF-19-regulated target gene expression through binding to multiple sites in Caenorhabditis elegans.

In humans, mutations of a growing list of regulatory factor X (RFX) target genes have been associated with devastating genetics disease conditions including ciliopathies. However, mechanisms underlying RFX transcription factors (TFs)-mediated gene expression regulation, especially differential gene expression regulation, are largely unknown. In this study, we explore the functional significance of the co-existence of multiple X-box motifs in regulating differential gene expression in Caenorhabditis elegans. We hypothesize that the effect of multiple X-box motifs is not a simple summation of binding effect to individual X-box motifs located within a same gene. To test this hypothesis, we identified eight C. elegans genes that contain two or more X-box motifs using comparative genomics. We examined one of these genes, F25B4.2, which contains two 15-bp X-box motifs. F25B4.2 expression in ciliated neurons is driven by the proximal motif and its expression is repressed by the distal motif. Our data suggest that two X-box motifs cooperate together to regulate the expression of F25B4.2 in location and intensity. We propose that multiple X-box motifs might be required to tune specific expression level. Our identification of genes with multiple X-box motifs will also improve our understanding of RFX/DAF-19-mediated regulation in C. elegans and in other organisms including humans.

The two actin-interacting protein 1 genes have overlapping and essential function for embryonic development in Caenorhabditis elegans.

Disassembly of actin filaments by actin-depolymerizing factor (ADF)/cofilin and actin-interacting protein 1 (AIP1) is a conserved mechanism to promote reorganization of the actin cytoskeleton. We previously reported that unc-78, an AIP1 gene in the nematode Caenorhabditis elegans, is required for organized assembly of sarcomeric actin filaments in the body wall muscle. unc-78 functions in larval and adult muscle, and an unc-78-null mutant is homozygous viable and shows only weak phenotypes in embryos. Here we report that a second AIP1 gene, aipl-1 (AIP1-like gene-1), has overlapping function with unc-78, and that depletion of the two AIP1 isoforms causes embryonic lethality. A single aipl-1-null mutation did not cause a detectable phenotype. However, depletion of both unc-78 and aipl-1 arrested development at late embryonic stages due to severe disorganization of sarcomeric actin filaments in body wall muscle. In vitro, both AIPL-1 and UNC-78 preferentially cooperated with UNC-60B, a muscle-specific ADF/cofilin isoform, in actin filament disassembly but not with UNC-60A, a nonmuscle ADF/cofilin. AIPL-1 is expressed in embryonic muscle, and forced expression of AIPL-1 in adult muscle compensated for the function of UNC-78. Thus our results suggest that enhancement of actin filament disassembly by ADF/cofilin and AIP1 proteins is critical for embryogenesis.

Duplication of cyb-3 (cyclin B3) suppresses sterility in the absence of mdf-1/MAD1 spindle assembly checkpoint component in Caenorhabditis elegans.

mdf-1/MAD1 is a conserved spindle assembly checkpoint component that is essential for the survival of Caenorhabditis elegans. Previously, using a dog-1(gk10)/FANCJ mutator strain, we have isolated a suppressor of mdf-1(gk2) sterility. This suppressor, named such-4, was demonstrated to be a tandem duplication that contained 62 putative protein coding genes. We apply here the recently developed Mos1-mediated single-copy insertion (MosSCI) method to study this copy number variation (CNV) in C. elegans and show that such-4 is caused by the duplication of a single gene cyb-3, illustrating the power of MosSCI-mediated single-gene duplications for uncovering gene dosage genetic interactions. Importantly, we show here, for the first time, that doubling the CYB-3 (Cyclin B3) dosage suppresses sterility in the absence of the essential spindle assembly checkpoint component MDF-1 without causing a delay in the onset of anaphase.

Spindle assembly checkpoint genes reveal distinct as well as overlapping expression that implicates MDF-2/Mad2 in postembryonic seam cell proliferation in Caenorhabditis elegans.

BACKGROUND: The spindle assembly checkpoint (SAC) delays anaphase onset by inhibiting the activity of the anaphase promoting complex/cyclosome (APC/C) until all of the kinetochores have properly attached to the spindle. The importance of SAC genes for genome stability is well established; however, the roles these genes play, during postembryonic development of a multicellular organism, remain largely unexplored. RESULTS: We have used GFP fusions of 5' upstream intergenic regulatory sequences to assay spatiotemporal expression patterns of eight conserved genes implicated in the spindle assembly checkpoint function in Caenorhabditis elegans. We have shown that regulatory sequences for all of the SAC genes drive ubiquitous GFP expression during early embryonic development. However, postembryonic spatial analysis revealed distinct, tissue-specific expression of SAC genes with striking co-expression in seam cells, as well as in the gut. Additionally, we show that the absence of MDF-2/Mad2 (one of the checkpoint genes) leads to aberrant number and alignment of seam cell nuclei, defects mainly attributed to abnormal postembryonic cell proliferation. Furthermore, we show that these defects are completely rescued by fzy-1(h1983)/CDC20, suggesting that regulation of the APC/CCDC20 by the SAC component MDF-2 is important for proper postembryonic cell proliferation. CONCLUSION: Our results indicate that SAC genes display different tissue-specific expression patterns during postembryonic development in C. elegans with significant co-expression in hypodermal seam cells and gut cells, suggesting that these genes have distinct as well as overlapping roles in postembryonic development that may or may not be related to their established roles in mitosis. Furthermore, we provide evidence, by monitoring seam cell lineage, that one of the checkpoint genes is required for proper postembryonic cell proliferation. Importantly, our research provides the first evidence that postembryonic cell division is more sensitive to SAC loss, in particular MDF-2 loss, than embryonic cell division.

An antibiotic selection marker for nematode transgenesis.

We have developed a nematode transformation vector carrying the bacterial neomycin resistance gene (NeoR) and shown that it could confer resistance to G-418 on both wild-type Caenorhabditis elegans and C. briggsae. This selection system allows hands-off maintenance and enrichment of transgenic worms carrying non-integrated transgenes on selective plates. We also show that this marker can be used for Mos1-mediated single-copy insertion in wild-type genetic backgrounds (MosSCI-biotic).

Characterization of the octamer, a cis-regulatory element that modulates excretory cell gene-expression in Caenorhabditis elegans.

BACKGROUND: We have previously demonstrated that the POU transcription factor CEH-6 is required for driving aqp-8 expression in the C. elegans excretory (canal) cell, an osmotic regulatory organ that is functionally analogous to the kidney. This transcriptional regulation occurs through a CEH-6 binding to a cis-regulatory element called the octamer (ATTTGCAT), which is located in the aqp-8 promoter. RESULTS: Here, we further characterize octamer driven transcription in C. elegans. First, we analyzed the positional requirements of the octamer. To do so, we assayed the effects on excretory cell expression by placing the octamer within the well-characterized promoter of vit-2. Second, using phylogenetic footprinting between three Caenorhabditis species, we identified a set of 165 genes that contain conserved upstream octamers in their promoters. Third, we used promoter::GFP fusions to examine the expression patterns of 107 of the 165 genes. This analysis demonstrated that conservation of octamers in promoters increases the likelihood that the gene is expressed in the excretory cell. Furthermore, we found that the sequences flanking the octamers may have functional importance. Finally, we altered the octamer using site-directed mutagenesis. Thus, we demonstrated that some nucleotide substitutions within the octamer do not affect the expression pattern of nearby genes, but change their overall expression was changed. Therefore, we have expanded the core octamer to include flanking regions and variants of the motif. CONCLUSIONS: Taken together, we have demonstrated that octamer-containing regions are associated with excretory cell expression of several genes that have putative roles in osmoregulation. Moreover, our analysis of the octamer sequence and its sequence variants could aid in the identification of additional genes that are expressed in the excretory cell and that may also be regulated by CEH-6.

High-throughput in vivo analysis of gene expression in Caenorhabditis elegans.

Using DNA sequences 5' to open reading frames, we have constructed green fluorescent protein (GFP) fusions and generated spatial and temporal tissue expression profiles for 1,886 specific genes in the nematode Caenorhabditis elegans. This effort encompasses about 10% of all genes identified in this organism. GFP-expressing wild-type animals were analyzed at each stage of development from embryo to adult. We have identified 5' DNA regions regulating expression at all developmental stages and in 38 different cell and tissue types in this organism. Among the regulatory regions identified are sequences that regulate expression in all cells, in specific tissues, in combinations of tissues, and in single cells. Most of the genes we have examined in C. elegans have human orthologs. All the images and expression pattern data generated by this project are available at WormAtlas (http://gfpweb.aecom.yu.edu/index) and through WormBase (http://www.wormbase.org).

Transcriptional regulation of AQP-8, a Caenorhabditis elegans aquaporin exclusively expressed in the excretory system, by the POU homeobox transcription factor CEH-6.

Due to the ever changing environmental conditions in soil, regulation of osmotic homeostasis in the soil-dwelling nematode Caenorhabditis elegans is critical. AQP-8 is a C. elegans aquaporin that is expressed in the excretory cell, a renal equivalent tissue, where the protein participates in maintaining water balance. To better understand the regulation of AQP-8, we undertook a promoter analysis to identify the aqp-8 cis-regulatory elements. Using progressive 5' deletions of upstream sequence, we have mapped an essential regulatory region to roughly 300 bp upstream of the translational start site of aqp-8. Analysis of this region revealed a sequence corresponding to a known DNA functional element (octamer motif), which interacts with POU homeobox transcription factors. Phylogenetic footprinting showed that this site is perfectly conserved in four nematode species. The octamer site's function was further confirmed by deletion analyses, mutagenesis, functional studies, and electrophoretic mobility shift assays. Of the three POU homeobox proteins encoded in the C. elegans genome, CEH-6 is the only member that is expressed in the excretory cell. We show that expression of AQP-8 is regulated by CEH-6 by performing RNA interference experiments. CEH-6's mammalian ortholog, Brn1, is expressed both in the kidney and the central nervous system and binds to the same octamer consensus binding site to drive gene expression. These parallels in transcriptional control between Brn1 and CEH-6 suggest that C. elegans may well be an appropriate model for determining gene-regulatory networks in the developing vertebrate kidney.

Genome-scale analysis of in vivo spatiotemporal promoter activity in Caenorhabditis elegans.

Differential regulation of gene expression is essential for cell fate specification in metazoans. Characterizing the transcriptional activity of gene promoters, in time and in space, is therefore a critical step toward understanding complex biological systems. Here we present an in vivo spatiotemporal analysis for approximately 900 predicted C. elegans promoters (approximately 5% of the predicted protein-coding genes), each driving the expression of green fluorescent protein (GFP). Using a flow-cytometer adapted for nematode profiling, we generated 'chronograms', two-dimensional representations of fluorescence intensity along the body axis and throughout development from early larvae to adults. Automated comparison and clustering of the obtained in vivo expression patterns show that genes coexpressed in space and time tend to belong to common functional categories. Moreover, integration of this data set with C. elegans protein-protein interactome data sets enables prediction of anatomical and temporal interaction territories between protein partners.