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Search indexed bioRxiv preprints in genomics, neuroscience, cell biology and bioinformatics. Read source abstracts and check manuscript versions; preprints are not peer reviewed.

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bioRxiv2018

The RhoGAP SPV-1 regulates calcium signaling to control the contractility of the C. elegans spermatheca during embryo transits.

Contractility of the non-muscle and smooth muscle cells that comprise biological tubing is regulated by the Rho-ROCK and calcium signaling pathways. Although many molecular details about these signaling pathways are known, less is known about how they are coordinated spatiotemporally in biological tubes. The spermatheca of the C. elegans reproductive system enables study of the signaling pathways regulating actomyosin contractility in live adult animals. The RhoGAP SPV-1 was previously identified as a negative regulator of RHO-1/Rho and spermathecal contractility. Here, we uncover a role for SPV-1 as a key regulator of calcium signaling. spv-1 mutants expressing the calcium indicator GCaMP in the spermatheca exhibit premature calcium release, elevated calcium levels, and disrupted spatial regulation of calcium signaling during spermathecal contraction. Although RHO-1 is required for spermathecal contractility, RHO-1 does not play a significant role in regulating calcium. In contrast, activation of CDC-42 recapitulates many aspects of spv-1 mutant calcium signaling. Depletion of cdc-42 by RNAi does not suppress the premature or elevated calcium signal seen in spv-1 mutants, suggesting other targets remain to be identified. Our results suggest SPV-1 works through both the Rho-ROCK and calcium signaling pathways to coordinate cellular contractility.\n\nHighlight SummaryThrough in vivo imaging of the calcium sensor GCaMP, we show that the RhoGAP SPV-1 is a key regulator of calcium signaling in the C. elegans spermatheca. Our data suggests SPV-1 acts at least partially through the small GTPase CDC-42 to modulate calcium signaling, while also acting on RHO-1 to modulate Rho-ROCK signaling. This places SPV-1 as a central regulator of cellular contractility.

cell biology↗

bioRxiv2018

Unraveling Tumor-Immune Heterogeneity in Advanced Ovarian Cancer Uncovers Immunogenic Effect of Chemotherapy

In metastatic cancer, the role of heterogeneity at the tumor-immune microenvironment, its molecular underpinnings and clinical relevance remain largely unexplored. To understand tumor-immune dynamics at baseline and upon chemotherapy treatment, we performed unbiased pathway and cell type-specific immunogenomics analysis of treatment-naive (38 samples from 8 patients) and paired chemotherapy treated (80 paired samples from 40 patients) high-grade serous ovarian cancer (HGSOC) samples. Whole transcriptome analysis and image-based quantification of T cells from treatment-naive tumors revealed ubiquitous variability in immune signaling and distinct immune microenvironments co-existing within the same individuals and within tumor deposits at diagnosis. To systematically explore cell type composition of the tumor microenvironment using bulk mRNA, we derived consensus immune and stromal cell gene signatures by intersecting state-of-the-art deconvolution methods, providing improved accuracy and sensitivity when compared to HGSOC immunostaining and leukocyte methylation data sets. Cell-type deconvolution and pathway analyses revealed that Myc and Wnt signaling associate with immune cell exclusion in untreated HGSOC. To evaluate the effect of chemotherapy on the intrinsic tumor-immune heterogeneity, we compared site-matched and site-unmatched tumors before and after neoadjuvant chemotherapy. Transcriptomic and T-cell receptor sequencing analyses showed that site-matched samples had increased cytotoxic immune activation and oligoclonal expansion of T cells after chemotherapy, which was not seen in site-unmatched samples where heterogeneity could not be accounted for. These results demonstrate that the tumor-immune interface in advanced HGSOC is intrinsically heterogeneous, and thus requires site-specific analysis to reliably unmask the impact of therapy on the tumor-immune microenvironment.

cancer biology↗

bioRxiv2018

Antigen receptor locus dynamics is orchestrated near the sol-gel phase transition to enforce stepwise VDJ gene rearrangement

Diverse antibody repertoires are generated through remote genomic interactions involving immunoglobulin variable (VH), diversity (DH) and joining (JH) gene segments. How such interactions are orchestrated remains unknown. We developed a novel strategy to track VH-DHJH motion and interactions in live B-lymphocytes. We found that VH and DHJH segments were trapped in configurations that only allowed constrained local motion, such that spatially proximal VH and DHJH segments remained in proximity, whereas spatially remote segments explored their immediate neighborhood while remaining remote. Comparison of experimental and simulated data revealed that such a highly constrained motion was imposed by a network of cross-linked chromatin chains characteristic of a gel phase, yet it was poised near the sol phase, a solution of independent chromatin chains. We propose that epigenetically induced gel droplets and the proximity to the sol-gel phase transition constitute the mechanism that orchestrates ordered VDJ rearrangement.

immunology↗

bioRxiv2018

Dissociation rate compensation mechanism for budding yeast pioneer transcription factors

Nucleosomes restrict the occupancy of most transcription factors (TF) by reducing binding and accelerating dissociation, while a small group of TFs have high affinities to nucleosome-embedded sites and facilitate nucleosome displacement. To mechanistically understand this process, we investigated two S. cerevisiae TFs, Reb1 and Cbf1. We show these factors bind their sites within nucleosomes with similar affinities to naked DNA, trapping a partially unwrapped nucleosome without histone eviction. Both the binding and dissociation rates of Reb1 and Cbf1 are significantly slower at the nucleosomal sites relative to DNA, demonstrating that the high affinities are achieved by increasing the dwell time on nucleosomes to compensate for reduced binding. Reb1 also shows slow migration rate in the yeast nuclei. These properties are similar to human pioneer factors (PFs), suggesting the mechanism of nucleosome targeting is conserved from yeast to human.

molecular biology↗

bioRxiv2018

The ion channel ppk301 controls freshwater egg-laying in the mosquito Aedes aegypti

Aedes aegypti mosquitoes are deadly vectors of arboviral pathogens including Zika, dengue, and yellow fever, and breed in containers of freshwater associated with human habitation1,2. Female Ae. aegypti lay eggs near freshwater because larval and pupal stages are aquatic3. They use volatile cues to locate water at a distance4, while at close-range they contact water to evaluate its suitability for egg-laying4-7. High salinity is lethal to mosquito offspring and therefore correctly laying eggs in freshwater is a crucial parenting decision made by female mosquitoes. Here we show that the DEG/ENaC channel8-10 ppk301 is required for mosquitoes to exploit freshwater egg-laying substrates. When ppk301 mutant females contact water, they do not lay eggs as readily as wild-type animals and are more likely to make aberrant decisions between freshwater and saltwater at concentrations that impair offspring survival. We used a CRISPR-Cas9-based genetic knock-in strategy combined with the Q-binary transactivator system11 to build genetic tools for labelling and imaging neurons in the mosquito. We found that ppk301 is expressed in sensory neurons in legs and proboscis, appendages that directly contact water, and that ppk301-expressing neurons project to central taste centres. Using in vivo calcium imaging with the genetically-encoded calcium sensor GCaMP6s12, we found that ppk301-expressing cells respond to water but, unexpectedly, also to salt. This suggests that ppk301 is instructive for egg-laying at low salt concentrations but that a ppk301-independent pathway is responsible for inhibiting egg-laying at high salt concentrations. Water is a key resource for insect survival and understanding how mosquitoes interact with water to control different behaviours is an opportunity to study the evolution of chemosensory systems. The new genetic tools described here will enable direct study of not only egg-laying, but also other behaviours in mosquitoes that influence disease transmission and enable comparative studies of insect biology more broadly.

neuroscience↗

bioRxiv2018

QuBiT: A quantitative tool for epithelial tubes reveals cell dynamics and unexpected patterns of organization during Drosophila tracheal morphogenesis

Biological tubes are essential for animal survival, and their functions are critically dependent on tube shape. Analyzing the contributions of cell shape and organization to the morphogenesis of small tubes has been hampered by the limitations of existing programs in quantifying cell geometry on highly curved tubular surfaces and calculating tube-specific parameters. We therefore developed QuBiT (Quantitative Tool for Biological Tubes) and used it to analyze morphogenesis during embryonic Drosophila tracheal (airway) development. We find that there are previously unknown anterior-to-posterior (A-P) gradients of cell orientation and aspect ratio, and that there is periodicity in the organization of cells in the main tube. Furthermore, cell intercalation during development dampens an A-P gradient of the number of the number of cells per cross-section of the tube, but these intercalation events do not change the patterns of cell connectivity. These unexpected findings demonstrate the importance of a computational tool for analyzing the morphogenesis of small diameter biological tubes.

cell biology↗

bioRxiv2018

Galectin-1 promotes the invasion of bladder cancer urothelia through their matrix milieu

The progression of carcinoma of the urinary bladder involves migration of cancer epithelia through their surrounding tissue matrix microenvironment. This was experimentally confirmed when a gender- and grade-diverse set of bladder cancer cell lines were cultured in pathomimetic three-dimensional laminin-rich environments. The high-grade cells, particularly female, formed multicellular invasive morphologies in 3D. In comparison, low- and intermediate-grade counterparts showed growth-restricted phenotypes. A proteomic approach combining mass spectrometry and bioinformatics analysis identified the estrogen-driven lactose-binding lectin Galectin-1 (GAL-1) as a putative candidate that could drive this invasion. Expression of LGALS1, the gene encoding GAL-1 showed an association with tumor grade progression in bladder cell lines. Immunohisto- and cyto-chemical experiments suggested greater extracellular levels of GAL-1 in 3D cultures of high-grade bladder cells and cancer tissues. High levels of GAL-1 associated with increased proliferation- and adhesion- of bladder cancer cells when grown on laminin-rich matrices. Pharmacological inhibition and Gal-1 knockdown in high-grade female cells decreased their adhesion to, and viability on, laminin-rich substrata. Higher GAL-1 also correlated with reduced E-cadherin and increased N-cadherin levels in consonance with a mesenchymal-like phenotype that we observed in 3D culture. The inhibition of GAL-1 reversed the stellate invasive phenotype to a more growth-restricted one in high-grade cells embedded within both basement-membrane-like and stromal collagenous matrix scaffolds. Finally, inhibition of GAL-1 specifically altered cell surface sialic acids, suggesting the mechanism by which the levels of GAL-1 may underlie the aggression and poor prognosis of invasive bladder cancer, especially in women.

cancer biology↗

bioRxiv2018

In vivo assembly and trafficking of olfactory Ionotropic Receptors

lonotropic Receptors (IRs) are a large, divergent subfamily of ionotropic glutamate receptors(iGluRs), with roles in chemosensation, thermosensation and hygrosensation. Analogous to the synaptic targeting mechanisms of their iGluR ancestors, IRs are thought to form complexes of broadly-expressed co-receptors and selectively-expressed tuning receptors to localise to sensory cilia. While tuning receptors extracellular ligand-binding domain (LBD) defines sensory specificity, the role of this domain in co-receptors is unclear. We identify a coreceptor-specific sequence in the LBD, which contains a single N-glycosylation site. Combining molecular genetic and cell biological analyses, we show that this site is dispensable for assembly of IR complexes in olfactory sensory neurons, but essential for endoplasmic reticulum exit of some,but not all, IR complexes. Our data reveal an important role for the IR co-receptor LBD in control of intracellular transport, provide novel insights into the stoichiometry and assembly of IR complexes, and uncover an unexpected heterogeneity in the trafficking regulation of this sensory receptor family.

neuroscience↗

bioRxiv2018

Dynamic enhancer partitioning instructs activation of a growth regulator during exit from naïve pluripotency

During early mammalian development, the genome undergoes profound transitions in chromatin states, topological organization and recruitment of cis regulatory factors involved in transcriptional control. How these three layers of gene regulation interact is the matter of intense research. The Zdbf2 gene--which is involved in growth control--provides a valuable model to study this question: upon exit from naive pluripotency and prior to tissue differentiation, it undergoes a switch in usage from a distal to a proximal promoter, along with a switch in chromatin states, from polycomb to DNA methylation occupancy. Using an embryonic stem cell (ESC) culture system to mimic this period, we show here that four enhancers contribute to the Zdbf2 promoter switch, concomitantly with dynamic changes in chromosome architecture. Indeed, CTCF plays a key role in partitioning the locus in ESCs, to facilitate enhancer contact with the distal Zdbf2 promoter only. Partition relieving enhances proximal Zdbf2 promoter activity, as observed during differentiation or with mutants that lack local CTCF-based partition. Importantly, we show that CTCF-based regulation occurs independently of the polycomb and DNA methylation pathways. Our study reveals the importance of multi-layered regulatory frameworks to ensure proper spatio-temporal activation of developmentally important genes.

molecular biology↗

bioRxiv2018

Lmx1b influences correct post-mitotic coding of mesodiencephalic dopaminergic neurons

The Lim Homeobox transcription factor 1 beta (LMX1b) has been identified as one of the transcription factors important for the development of mesodiencephalic dopaminergic (mdDA) neurons. During early development, Lmx1b is essential for induction and maintenance of the Isthmic Organizer (IsO), and genetic ablation results in the disruption of inductive activity from the IsO and loss of properly differentiated mdDA neurons.\n\nTo study the downstream targets of Lmx1b without affecting the IsO, we generated a conditional model in which Lmx1b was selectively deleted in Pitx3 expressing cells from embryonic day (E)13 onward. Supporting previous data, no significant changes could be observed in general dopamine (DA) marks, like Th, Pitx3 and Vmat2 at E14.5. However, in depth analysis by means of RNA-sequencing revealed that Lmx1b is important for the expression level of survival factors En1 and En2 and for the repression of mdDA subset mark Ahd2 during (late) development. Interestingly, the regulation of Ahd2 by Lmx1b was found to be Pitx3 independent, since Pitx3 levels were not altered in Lmx1b conditional knock-outs (cKO) and Ahd2 expression was also up-regulated in Lmx1b/Pitx3 double mutants compared to Pitx3 mutants. Further analysis of Lmx1b cKOs showed that post-mitotic deletion of Lmx1b additional leads to a loss of TH+ cells at 3 months age both in the VTA and SNc. Remarkably, different cell types were affected in the SNc and the VTA. While TH+AHD2+ cells were lost the SNc, TH+AHD2- neurons were affected in the VTA, reflected by a loss of Cck expression, indicating that Lmx1b is important for the survival of a sub-group of mdDA neurons.

developmental biology↗

bioRxiv2018

The ULK1-FBXW5-SEC23B nexus controls autophagy

In response to nutrient deprivation, the cell needs to mobilize an extensive amount of membrane to form and grow the autophagosome, allowing the progression of autophagy. By providing membranes and a source for LC3 lipidation, COPII (Coat Protein Complex II) localizes to the endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC) and promotes autophagosome biogenesis. However, the molecular mechanisms that, in response to starvation, divert COPII from the secretory pathway to the autophagic pathway are largely unknown. Here, we show that the F-box protein FBXW5 targets SEC23B, a component of COPII, for proteasomal degradation and that this event limits the autophagic flux in the presence of nutrients. In response to starvation, ULK1 phosphorylates SEC23B on Serine 186, preventing the interaction of SEC23B with FBXW5 and, therefore, inhibiting its degradation. Phosphorylated and stabilized SEC23B associates with SEC24A and SEC24B, but not SEC24C and SEC24D, and they re-localize to the ERGIC, promoting autophagic flux. Induction of autophagy and localization of both SEC23B and SEC24B to the ERGIC in response to nutrient deprivation are significantly reduced in SEC23B(S186A) knock-in cells. We propose that, in the presence of nutrients, FBXW5 limits COPII-mediated autophagosome biogenesis. Inhibition of this event by ULK1 ensures efficient execution of the autophagic cascade in response to nutrient starvation.

cell biology↗

bioRxiv2018

Dynamic regulation of the Trypanosoma brucei transferrin receptor in response to iron starvation is mediated via the 3UTR

The bloodstream form of the parasite Trypanosoma brucei obtains iron from its mammalian host by receptor-mediated endocytosis of host transferrin through its own unique transferrin receptor (TbTfR). Expression of TbTfR rapidly increases upon iron starvation by post-transcriptional regulation through a currently undefined mechanism that is distinct from the mammalian iron response system. We have created reporter cell lines by fusing the TbTfR 3'UTR or a control Aldolase 3UTR to reporter genes encoding GFP or firefly Luciferase, and inserted the fusions into a bloodstream form cell line at a tagged ribosomal RNA locus. Fusion of the TbTfR 3UTR is sufficient to significantly repress the expression of the reporter proteins under normal growth conditions. Under iron starvation conditions we observed upregulation of the TbTfR 3UTR fusions only, with a magnitude and timing consistent with that reported for upregulation of the TbTfR. We conclude that the dynamic regulation of the T. brucei transferrin receptor in response to iron starvation is mediated via its 3UTR, and that the effect is independent of genomic location.

cell biology↗

bioRxiv2018

Strengthening Bolivian Pharmacovigilance system: new therapeutic strategies to improve health of Chagas Disease and Tuberculosis patients

IntroductionChagas disease (CD) and Tuberculosis (TB) are important health problems in Bolivia. Current treatments for both infections require a long period of time, and unwanted drug-related adverse events (ADRs) are frequent.\n\nPurposeThis study aims to strengthen the Bolivian Pharmacovigilance system, focusing on CD and TB.\n\nMethodsA situational diagnosis of Pharmacovigilance in the Department of Cochabamba was performed. The use of a new Local Case Report Form (CRF) was implemented, together with the CRF established by the Unidad de Medicamentos y Tecnologia en Salud (UNIMED), in several health care centers. Training and follow-up on drug safety monitoring and ADR reporting was provided to all health professionals involved in CD and TB treatment. A comparative analysis of the reported ADRs using the CRF provided by UNIMED, the new CRF proposal, and medical records, was performed.\n\nResultsOut of the total patients starting treatment for CD, 35,35% suffered ADR according to the information collected in the medical records, and 25% of them were classified as moderate/severe (MS) types. Only 51,43% of MS ADRs were reported to UNIMED. Regarding TB treatment, 9,89% of the total patients suffered ADR, 44% of them were classified as MS, and 75% of MS ADRs were reported to UNIMED.\n\nConclusionsThe reinforcement of the Bolivian Pharmacovigilance system is an ambitious project that should take a long-term perspective and the engagement of national health workers and other stake holders at all levels. Continuity and perseverance are essential to achieve a solid ADR reporting system, improving patient safety, drug efficacy and adherence to treatment.

pharmacology and toxicology↗

bioRxiv2018

Insights into the genetic diversity of Mycobacterium tuberculosis in Tanzania

BackgroundHuman tuberculosis (TB) is caused by seven phylogenetic lineages of the Mycobacterium tuberculosis complex (MTBC), Lineage 1-7. Recent advances in rapid genotyping of MTBC based on single nucleotide polymorphisms (SNP), allow for rapid and phylogenetically robust strain classification, paving the way for defining genotype-phenotype relationships in clinical settings. Such studies have revealed that, in addition to host and environmental factors, different strains of the MTBC influence the outcome of TB infection and disease. In Tanzania, such molecular epidemiological studies of TB however are scarce in spite of a high TB burden.\n\nMethods and FindingsHere we used a SNP-typing method to genotype a nationwide collection of 2,039 MTBC clinical isolates obtained from new and retreatment TB cases diagnosed in 2012 and 2013. Four lineages, namely Lineage 1-4 were identified. The distribution and frequency of these lineages varied across the regions but overall, Lineage 4 was the most frequent (n=866, 42.5%), followed by Lineage 3 (n=681, 33.4%) and 1 (n=336, 16.5%), with Lineage 2 being the least frequent (n=92, 4.5%). A total of 64 (3.1%) isolates could not be assigned to any lineage. We found Lineage 2 to be associated with female sex (adjusted odds ratio [aOR] 2.25; 95% confidence interval [95% CI] 1.38 - 3.70, p<0.001) and retreatment (aOR 1.78; 95% CI 1.00 - 3.02, p=0.040). We found no associations between MTBC lineage and patient age or HIV status. Our sublineage typing based on spacer oligotyping revealed the presence of mainly EAI, CAS and LAM families. Finally, we detected low levels of multidrug resistant isolates among a subset of retreatment cases\n\nConclusionsThis study provides novel insights into the influence of pathogen-related factors on the TB epidemic in Tanzania.

epidemiology↗

bioRxiv2018

TREATMENT OUTCOME OF DIABETIC KETOACIDOSIS AMONG PATIENTS ATENDING GENERAL HOSPITAL IN NORTH-WEST ETHIOPIA: HOSPITAL BASED STUDY

BackgroundDiabetic ketoacidosis is an acute life-threatening complication of diabetes mellitus. There was limited data on level of in-hospital mortality, hospital stay and factors associated with length of hospital stay among diabetic patients admitted to diabetic ketoacidosis at Debretabor General Hospital.\n\nObjectiveThe aim of the study was to determine the length of hospital stay and in-hospital mortality of diabetic ketoacidosis patients and to assess determinants of long hospital stay among diabetic patients admitted with Diabetic ketoacidosis at Debretabor General Hospital.\n\nMethodA retrospective study was conducted at Debretabor General Hospital from June 1to 30, 2018. Participants included in the study were all diabetic patients with diabetic ketoacidosis admitted to the hospital from August 2010 to May 31, 2018 whose medical records contained complete pertinent data. The primary outcome was to determine the length of hospital stay and in-hospital mortality of diabetic ketoacidosis patients. All the statistical data was carried out using Statistical Package for Social Sciences (SPSS). Descriptive statistics was presented using means with standard deviation and percentages.\n\nResultA total of 387 patients medical records contained pertinent complete information included in this study. Mean age of the patients was 33.30{+/-} 14.96 years. The majority of patients were females 244 (63.0%). The mean length of hospital stay was 4.64({+/-}2.802) days. About twenty percent 79(20.41%) patients had long hospital stay (>7days). The majority 370 (95.60%) of patients improved and discharged and 17 (4.40%) patients died in the hospital. patients who had mild DKA; AOR: 0.16 [0.03-0.78] and patients between the age of 35-44years, AOR: 0.125[0.017-0.92] had reduced length of hospital stay. further, patients with DKA precipitated by infection were 4.59 times more likely to have long hospital stay than patients with DKA precipitated by unknown causes; AOR 4.59[1.08-19.42].\n\nConclusionsIn the current study, the mean length of hospital stay was around five days. About twenty percent patients had long hospital stay. Nearly ninety five percent of patientsimproved and discharged. The presence of infection, frequent rebound hyperglycemia and severity of DKA were the major determinants of long hospital stay.

epidemiology↗

bioRxiv2018

The mRNA export adaptor Yra1 contributes to DNA double-strand break repair through its C-box domain

Yra1 is an mRNA export adaptor involved in mRNA biogenesis and export in S. cerevisiae. Yra1 overexpression was recently shown to promote accumulation of DNA:RNA hybrids favoring DNA double strand breaks (DSB), cell senescence and telomere shortening, via an unknown mechanism. Yra1 was also identified at an HO-induced DSB and Yra1 depletion causes defects in DSB repair. Previous work from our laboratory showed that Yra1 ubiquitination by Tom1 is important for mRNA export. Interestingly, we found that Yra1 is also ubiquitinated by the SUMO-targeted ubiquitin ligases Slx5-Slx8 implicated in the interaction of irreparable DSB with nuclear pores. Here we show that Yra1 binds an HO-induced irreparable DSB. Importantly, a Yra1 mutant lacking the evolutionarily conserved C-box is not recruited to an HO-induced irreparable DSB and becomes lethal under DSB induction in a HO-cut reparable system. Together, the data provide evidence that Yra1 plays a crucial role in DSB repair via homologous recombination. Unexpectedly, while the Yra1 C-box is essential, Yra1 sumoylation and/or ubiquitination are dispensable in this process.

molecular biology↗

bioRxiv2018

Haematological parameters and plasma levels of 8-iso-prostaglandin F2α in malaria-sickle cell co-morbidity: A cross sectional study

IntroductionMalaria and sickle cell disease (SCD) co-morbidity have previously been reported in Ghana. However, there is paucity of data on haematological profiles and oxidative stress in comorbidity states. This study identified novel inflammatory biomarkers associated with malaria in SCD and analyzed the levels of 8-iso-prostaglandin F2 oxidative stress biomarker in malaria-SCD co-morbidity in Ghanaian patients.\n\nMethodsBlood (5ml) was collected from malaria patients into K3-EDTA tube. Malaria parasites speciation and quantification were then done according WHO guidelines. All eligible samples were assayed for haematological profile, sickle cell phenotyping, infectious markers (hepatitis B, hepatitis C, syphilis and HIV 1&2) and plasma levels of 8-epi-prostaglandin F2..\n\nResultsPrevalence of malaria in SCD (malaria-SCD) was 13.4% (45/335). Male: female ratio was 0.8:1 (X2=1.43, p=0.231). Mean ages for malaria in normal haemoglobin type (malaria-HbAA) and malaria-SCD were 12.79{+/-}4.91 and 11.56{+/-}3.65 years respectively (p=0.048). Geometric mean of parasite density was higher in malaria-HbAA (20394 parasites/l vs. 9990 parasites/l, p=0.001) whilst mean body temperature was higher in malaria-SCD (39.0{+/-}0.87{degrees}C vs. 37.9{+/-}1.15{degrees}C, p=0.001). Mean leukocytes, lymphocytes, eosinophils, monocytes, platelets and platelet indices values were significantly elevated in malaria-SCD. Significant reduction in RBC and RBC indices in malaria-SCD were also observed. Eosinophils-to-basophils ratio (EBR) and monocytes-to-basophils ratio (MBR) were novel cellular inflammatory biomarkers which could predict malaria in SCD. The sensitivities of cut-off values of EBR>14, MBR>22 and combined use of EBR>14 and MBR>22 were 79.55%, 84.09% and 91.11% respectively. Mean 8-iso-prostaglandin F2 was 338.1pg/ml in malaria-HbAA and 643.8pg/ml in malaria-SCD (p=0.001). 8-iso-prostaglandin F2 correlated with parasite density (r=0.787, p=0.001), temperature (r=0.566, p=0.001) and leucocytes (r=0.573, p=0.001) and negatively correlated with RBC (r=-0.476, p=0.003), haemoglobin (r=-0.851, p=0.001) and haematocrit (r=-0.735, p=0.001).\n\nConclusionPlasmodium falciparum parasitaemia increases oxidative damage and causes derangement haematological parameters. Cut of values of EBR>14 and MBR>22 could predict malaria in SCD.

immunology↗

bioRxiv2018

The influence of truncating the carboxy-terminal amino acid residues of Streptococcal enolase on its ability to interact with canine plasminogen.

The native octameric structure of streptococcal enolase from Streptococcus pyogenes increasingly dissociates as amino acid residues are removed one by one from the carboxy-terminus. These truncations gradually convert native octameric enolase into monomers and oligomers. In this work, we investigated how these truncations influence the interaction between Streptococcal enolase and canine plasminogen. We used dual polarization interferometry (DPI), localized surface plasmon resonance (LSPR), and sedimentation velocity analytical ultracentrifugation (AUC) to study the interaction. The DPI was our first technique, was performed on all the truncations and used one exclusive kind of chip. The LSRP was used to show that the DPI results were not dependent on the type of chip used. The AUC was required to show that our surface results were not the result of selecting a minority population in any given sample; the majority of the protein was responsible for the binding phenomenon we observed. By comparing results from these techniques we identified one detail that is essential for streptococcal enolase to bind plasminogen: In our hands the individual monomers bind plasminogen; dimers, trimers, tetramers may or may not bind, the fully intact, native, octamer does not bind plasminogen. We also evaluated the contribution to the equilibrium constant made by surface binding as well as in solution. On a surface, the association coefficient is about twice that in solution. The difference is probably not significant. Finally, the fully octameric form of the protein that does not contain a hexahis N-terminal peptide does not bind to a silicon oxynitride surface, does not bind to a Au-nanoparticle surface, does not bind to a surface coated with Ni-NTA nor does it bind to a surface coated with DPgn. The likelihood is great that the enolase species on the surface of Streptococcus pyogenes is an x-mer of the native octamer.

biophysics↗