Antibody responses to surface antigens of Plasmodium falciparum gametocyte-infected erythrocytes and their relation to gametocytaemia.

: An essential element for continuing transmission of Plasmodium falciparum is the availability of mature gametocytes in human peripheral circulation for uptake by mosquitoes. Natural immune responses to circulating gametocytes may play a role in reducing transmission from humans to mosquitoes. Here, antibody recognition of the surface of mature intra-erythrocytic gametocytes produced either by a laboratory-adapted parasite, 3D7, or by a recent clinical isolate of Kenyan origin (HL1204), was evaluated longitudinally in a cohort of Ghanaian school children by flow cytometry. This showed that a proportion of children exhibited antibody responses that recognized gametocyte surface antigens on one or both parasite lines. A subset of the children maintained detectable anti-gametocyte surface antigen (GSA) antibody levels during the 5 week study period. There was indicative evidence that children with anti-GSA antibodies present at enrolment were less likely to have patent gametocytaemia at subsequent visits (odds ratio = 0·29, 95% CI 0·06-1·05; P = 0·034). Our data support the existence of antigens on the surface of gametocyte-infected erythrocytes, but further studies are needed to confirm whether antibodies against them reduce gametocyte carriage. The identification of GSA would allow their evaluation as potential anti-gametocyte vaccine candidates and/or biomarkers for gametocyte carriage.<br/

Generating Negatively Supercoiled DNA Using Dual-Trap Optical Tweezers

Many genomic processes lead to the formation of underwound (negatively supercoiled) or overwound (positively supercoiled) DNA. These DNA topological changes regulate the interactions of DNA-binding proteins, including transcription factors, architectural proteins and topoisomerases. In order to advance our understanding of the structure and interactions of supercoiled DNA, we recently developed a single-molecule approach called Optical DNA Supercoiling (ODS). This method enables rapid generation of negatively supercoiled DNA (with between <5% and 70% lower helical twist than nonsupercoiled DNA) using a standard dual-trap optical tweezers instrument. ODS is advantageous as it allows for combined force spectroscopy, fluorescence imaging, and spatial control of the supercoiled substrate, which is difficult to achieve with most other approaches. Here, we describe how to generate negatively supercoiled DNA using dual-trap optical tweezers. To this end, we provide detailed instructions on the design and preparation of suitable DNA substrates, as well as a step-by-step guide for how to control and calibrate the supercoiling density produced

Constructing arrays of nucleosome positioning sequences using Gibson Assembly for single-molecule studies

As the basic building blocks of chromatin, nucleosomes play a key role in dictating the accessibility of the eukaryotic genome. Consequently, nucleosomes are involved in essential genomic transactions such as DNA transcription, replication and repair. In order to unravel the mechanisms by which nucleosomes can influence, or be altered by, DNA-binding proteins, single-molecule techniques are increasingly employed. To this end, DNA molecules containing a defined series of nucleosome positioning sequences are often used to reconstitute arrays of nucleosomes in vitro. Here, we describe a novel method to prepare DNA molecules containing defined arrays of the ‘601’ nucleosome positioning sequence by exploiting Gibson Assembly cloning. The approaches presented here provide a more accessible and efficient means to generate arrays of nucleosome positioning motifs, and facilitate a high degree of control over the linker sequences between these motifs. Nucleosomes reconstituted on such arrays are ideal for interrogation with single-molecule techniques. To demonstrate this, we use dual-trap optical tweezers, in combination with fluorescence microscopy, to monitor nucleosome unwrapping and histone localisation as a function of tension. We reveal that, although nucleosomes unwrap at ~20 pN, histones (at least histone H3) remain bound to the DNA, even at tensions beyond 60 pN

Unravelling the mechanisms of Type 1A topoisomerases using single-molecule approaches

Topoisomerases are essential enzymes that regulate DNA topology. Type 1A family topoisomerases are found in nearly all living organisms and are unique in that they require single-stranded (ss)DNA for activity. These enzymes are vital for maintaining supercoiling homeostasis and resolving DNA entanglements generated during DNA replication and repair. While the catalytic cycle of Type 1A topoisomerases has been long-known to involve an enzyme-bridged ssDNA gate that allows strand passage, a deeper mechanistic understanding of these enzymes has only recently begun to emerge. This knowledge has been greatly enhanced through the combination of biochemical studies and increasingly sophisticated single-molecule assays based on magnetic tweezers, optical tweezers, atomic force microscopy and Förster resonance energy transfer. In this review, we discuss how single-molecule assays have advanced our understanding of the gate opening dynamics and strand-passage mechanisms of Type 1A topoisomerases, as well as the interplay of Type 1A topoisomerases with partner proteins, such as RecQ-family helicases. We also highlight how these assays have shed new light on the likely functional roles of Type 1A topoisomerases in vivo and discuss recent developments in single-molecule technologies that could be applied to further enhance our understanding of these essential enzymes

Elucidating the Role of Topological Constraint on the Structure of Overstretched DNA Using Fluorescence Polarization Microscopy

The combination of DNA force spectroscopy and polarization microscopy of fluorescent DNA intercalator dyes can provide valuable insights into the structure of DNA under tension. These techniques have previously been used to characterize S-DNA—an elongated DNA conformation that forms when DNA overstretches at forces ≥ 65 pN. In this way, it was deduced that the base pairs of S-DNA are highly inclined, relative to those in relaxed (B-form) DNA. However, it is unclear whether and how topological constraints on the DNA may influence the base-pair inclinations under tension. Here, we apply polarization microscopy to investigate the impact of DNA pulling geometry, torsional constraint, and negative supercoiling on the orientations of intercalated dyes during overstretching. In contrast to earlier predictions, the pulling geometry (namely, whether the DNA molecule is stretched via opposite strands or the same strand) is found to have little influence. However, torsional constraint leads to a substantial reduction in intercalator tilting in overstretched DNA, particularly in AT-rich sequences. Surprisingly, the extent of intercalator tilting is similarly reduced when the DNA molecule is negatively supercoiled up to a critical supercoiling density (corresponding to ∼70% reduction in the linking number). We attribute these observations to the presence of P-DNA (an overwound DNA conformation). Our results suggest that intercalated DNA preferentially flanks regions of P-DNA rather than those of S-DNA and also substantiate previous suggestions that P-DNA forms predominantly in AT-rich sequences

Appetite, gut hormone and energy intake responses to low volume sprint interval and traditional endurance exercise.

Sprint interval exercise improves several health markers but the appetite and energy balance response is unknown. This study compared the effects of sprint interval and endurance exercise on appetite, energy intake and gut hormone responses. Twelve healthy males [mean (SD): age 23 (3) years, body mass index 24.2 (2.9) kg m(-2), maximum oxygen uptake 46.3 (10.2) mL kg(-1) min(-1)] completed three 8 h trials [control (CON), endurance exercise (END), sprint interval exercise (SIE)] separated by 1 week. Trials commenced upon completion of a standardised breakfast. Sixty minutes of cycling at 68.1 (4.3) % of maximum oxygen uptake was performed from 1.75-2.75 h in END. Six 30-s Wingate tests were performed from 2.25-2.75 h in SIE. Appetite ratings, acylated ghrelin and peptide YY (PYY) concentrations were measured throughout each trial. Food intake was monitored from buffet meals at 3.5 and 7 h and an overnight food bag. Appetite (P 0.05). Therefore, relative energy intake (energy intake minus the net energy expenditure of exercise) was lower in END than that in CON (15.7 %; P = 0.006) and SIE (11.5 %; P = 0.082). An acute bout of endurance exercise resulted in lower appetite perceptions in the hours after exercise than sprint interval exercise and induced a greater 24 h energy deficit due to higher energy expenditure during exercise

Pregnancy and helminth infections.

It has been proposed that helminth infection may be particularly detrimental during pregnancy, through adverse effects on maternal anaemia and on birth outcomes, and that anthelminthic treatment during pregnancy will therefore be particularly beneficial. However, the few treatment trials that have been conducted have given, but little support to this notion and further trials in settings of nutritional stress are needed. It has also been proposed that prenatal exposure to helminth infection has an important effect on the development of the foetal immune response. There is evidence that this may impact, long-term, upon responses to helminth and nonhelminth antigens, and to allergens. Exposure to helminths in utero may also have nonspecific effects that may modify the offspring's susceptibility to diseases mediated by inflammation, including metabolic disorders. The mechanisms of such effects are not known, but they deserve to be explored as current epidemiological findings suggest the possibility of primary prevention for inflammatory conditions such as allergy, through intervention during pregnancy

Family in the spotlight: a systematic review of family factors associated with participation of children with disabilities

QMU Research Centre: FireflyStella Arakelyan - orcid: 0000-0003-0326-707X https://orcid.org/0000-0003-0326-707XUpdate history: 2019-01-09 (Gold OA version deposited, article title updated, deposit exception, publication & AM embargo dates updated); 2018-12-12 (Corrected version of AM deposited)Donald Maciver - orcid: 0000-0002-6173-429X https://orcid.org/0000-0002-6173-429XAIM: The aim of this review was to synthesise empirical evidence of family factors associated with participation of children with disabilities aged 5-12 years to inform the development of family-centred participation-fostering interventions. METHOD: A systematic search was performed for articles published in English between 2001 and 2017 in MEDLINE, PsycINFO, CINAHL, Scopus and ASSIA following the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines (registration no: CRD42017078202). Quality of evidence was appraised using the Research Triangle Institute Item Bank. Family factors associated with participation were identified and assessed using a multistage “semi-quantitative” approach. RESULTS: Thirty studies were included in the review. Four non-modifiable “status” factors consistently associated with participation were parental ethnicity, parental education, family type and family socio-economic status. Six modifiable “process” factors with consistent associations with participation were parental mental and physical health functioning, parental self-efficacy beliefs, parental support, parental time, family preferences and activity orientation. INTERPRETATION: Rehabilitation professionals should direct their focus towards modifiable family factors as primary targets for family-centred interventions. Strategies that can improve families’ access to information, counselling, and community support services are likely to support children’s participation by empowering families and optimizing their health and well-being.Funding: This research was completed as part of a PhD funded by Lothian National Health Service and Queen Margaret University, Edinburgh, Scotland.https://onlinelibrary.wiley.com/journal/1469874961pubpub

Nitrogen forms affect root structure and water uptake in the hybrid poplar

The study analyses the effects of two different forms of nitrogen fertilisation (nitrate and ammonium) on root structure and water uptake of two hybrid poplar (Populus maximowiczii x P. balsamifera) clones in a field experiment. Water uptake was studied using sap flow gauges on individual proximal roots and coarse root structure was examined by excavating 18 whole-root systems. Finer roots were scanned and analyzed for architecture. Nitrogen forms did not affect coarse-root system development, but had a significant effect on fine-root development. Nitrate-treated trees presented higher fine:coarse root ratios and higher specific root lengths than control or ammonium treated trees. These allocation differences affected the water uptake capacity of the plants as reflected by the higher sapflow rate in the nitrate treatment. The diameter of proximal roots at the tree base predicted well the total root biomass and length. The diameter of smaller lateral roots also predicted the lateral root mass, length, surface area and the number of tips. The effect of nitrogen fertilisation on the fine root structure translated into an effect on the functioning of the fine roots forming a link between form (architecture) and function (water uptake)

Exercise-Induced Improvements in Insulin Sensitivity Are Not Attenuated by a Family History of Type 2 Diabetes

© Copyright © 2020 Amador, Meza, McAinch, King, Covington and Bajpeyi. Introduction: A family history of type 2 diabetes (FH+) is a major risk factor for the development of insulin resistance and type 2 diabetes. However, it remains unknown whether exercise-induced improvements in insulin sensitivity and metabolic flexibility are impacted by a FH+. Therefore, we investigated whether improvements in insulin sensitivity, metabolic flexibility, body composition, aerobic fitness and muscle strength are limited by a FH+ following eight weeks of combined exercise training compared to individuals without a family history of type 2 diabetes (FH–). Methods: Twenty (n = 10 FH–, n = 10 FH+) young, healthy, sedentary, normoglycemic, Mexican-American males (age: FH– 22.50 ± 0.81, FH+ 23.41 ± 0.86 years; BMI: FH– 27.91 ± 1.55, FH+ 26.64 ± 1.02 kg/m2) underwent eight weeks of combined aerobic and resistance exercise training three times/week (35 min aerobic followed by six full-body resistance exercises). Insulin sensitivity was assessed via hyperinsulinemic euglycemic clamps. Metabolic flexibility was assessed by the change in respiratory quotient from fasted to insulin-stimulated states. Body composition was determined using dual-energy x-ray absorptiometry. Aerobic fitness was determined by a graded exercise test, and upper- and lower-body strength were assessed via one-repetition maximum bench press and leg strength dynamometer, respectively. Results: Insulin sensitivity, metabolic flexibility, aerobic fitness and strength were not different between groups (p \u3e 0.05). Eight weeks of combined aerobic and resistance exercise training improved insulin sensitivity (FH– p = 0.02, FH+ p = 0.002), increased fat free mass (FH– p = 0.006, FH+ p = 0.001), aerobic fitness (FH– p = 0.03, FH+ p = 0.002), and upper- (FH– p = 0.0001, FH+ p = 0.0001) and lower-body strength (FH– p = 0.0009, FH+ p = 0.0003), but did not change metabolic flexibility (p \u3e 0.05) in both groups. Exercise-induced improvements in metabolic outcomes were similar between groups. Conclusions: Insulin sensitivity, metabolic flexibility, aerobic fitness and strength were not compromised by a FH+. Additionally, a FH+ is not a limiting factor for exercise-induced improvements in insulin sensitivity, aerobic fitness, body composition, and strength in normoglycemic young Mexican-American men