Flowering in protea : a molecular and physiological study.

Includes bibliographical references.Proteas have been extensively cultivated and are grown as floricultural crop plants in many parts of the world, including South Africa. However, the factors that influence the initiation of flowering in Protea have not been identified. From data gathered by the Protea Atlas Project it is evident that Protea spp. have greatly varying flowering times. Furthermore, flowering times between Protea spp. and their hybrid cultivars are also very different. Towards a better understanding of the factors involved in floral initiation in this cultivated crop, three aspects of flowering were investigated in this study. The carbon input into Protea inflorescence development was determined by measuring respiration rates and weights of developing structures. By manipulating source-sink ratios in plants, the carbon assimilatory capacities to support inflorescences were investigated in three cultivars and one wild-grown species of Protea which develop different sized flowers. As some Proteas flower in response to seasonal change, an orthologue of the floral inducer FLOWERING LOCUS T (FT), ProteaFT (ProFT), was isolated from ‘Carnival’ (P. compacta x P. neriifolia) and its expression pattern followed diurnally and seasonally. Finally, the functions of paralogous genes of Protea LEAFY (ProLFY) from ‘Carnival’ displaying sequence similarity to the meristem identity gene LEAFY from Arabidopsis thaliana, were investigated through heterologous expression studies in A. thaliana

Editorial for Special Issue “Water within Minerals Processing”

The products of mining are key to the technology development of the future [...

Characterisation of three novel α-L-arabinofuranosidases from a compost metagenome

Background: The importance of the accessory enzymes such as α-L-arabinofuranosidases (AFases) in synergistic interactions within cellulolytic mixtures has introduced a paradigm shift in the search for hydrolytic enzymes. The aim of this study was to characterize novel AFase genes encoding enzymes with differing temperature optima and thermostabilities for use in hydrolytic cocktails. Results Three fosmids, pFos-H4, E3 and D3 were selected from the cloned metagenome of high temperature compost, expressed in Escherichia coli and subsequently purified to homogeneity from cell lysate. All the AFases were clustered within the GH51 AFase family and shared a homo-hexameric structure. Both AFase-E3 and H4 showed optimal activity at 60 °C while AFase-D3 had unique properties as it showed optimal activity at 25 °C as well as the ability to maintain substantial activity at temperatures as high as 90 °C. However, AFase-E3 was the most thermostable amongst the three AFases showing full activity even at 70 °C. The maximum activity was observed at a pH profile between pH 4.0–6.0 for all three AFases with optimal activity for AFase H4, D3 and E3 at pH 5.0, 4.5 and 4.0, respectively. All the AFases showed KM range between 0.31 mM and 0.43 mM, Kcat range between 131 s− 1 and 219 s− 1 and the specific activity for AFase-H4, AFases-E3 and was 143, 228 and 175 U/mg, respectively. AFases-E3 and D3 displayed activities against pNP-β-L-arabinopyranoside and pNP-β-L-mannopyranoside respectively, and both hydrolysed pNP-β-D-glucopyranoside. Conclusion All three AFases displayed different biochemical characteristics despite all showing conserved overall structural similarity with typical domains of AFases belonging to GH51 family. The hydrolysis of cellobiose by a GH51 family AFase is demonstrated for the first time in this study

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Case Reports1. A Late Presentation of Loeys-Dietz Syndrome: Beware of TGFβ Receptor Mutations in Benign Joint Hypermobility

Background: Thoracic aortic aneurysms (TAA) and dissections are not uncommon causes of sudden death in young adults. Loeys-Dietz syndrome (LDS) is a rare, recently described, autosomal dominant, connective tissue disease characterized by aggressive arterial aneurysms, resulting from mutations in the transforming growth factor beta (TGFβ) receptor genes TGFBR1 and TGFBR2. Mean age at death is 26.1 years, most often due to aortic dissection. We report an unusually late presentation of LDS, diagnosed following elective surgery in a female with a long history of joint hypermobility. Methods: A 51-year-old Caucasian lady complained of chest pain and headache following a dural leak from spinal anaesthesia for an elective ankle arthroscopy. CT scan and echocardiography demonstrated a dilated aortic root and significant aortic regurgitation. MRA demonstrated aortic tortuosity, an infrarenal aortic aneurysm and aneurysms in the left renal and right internal mammary arteries. She underwent aortic root repair and aortic valve replacement. She had a background of long-standing joint pains secondary to hypermobility, easy bruising, unusual fracture susceptibility and mild bronchiectasis. She had one healthy child age 32, after which she suffered a uterine prolapse. Examination revealed mild Marfanoid features. Uvula, skin and ophthalmological examination was normal. Results: Fibrillin-1 testing for Marfan syndrome (MFS) was negative. Detection of a c.1270G > C (p.Gly424Arg) TGFBR2 mutation confirmed the diagnosis of LDS. Losartan was started for vascular protection. Conclusions: LDS is a severe inherited vasculopathy that usually presents in childhood. It is characterized by aortic root dilatation and ascending aneurysms. There is a higher risk of aortic dissection compared with MFS. Clinical features overlap with MFS and Ehlers Danlos syndrome Type IV, but differentiating dysmorphogenic features include ocular hypertelorism, bifid uvula and cleft palate. Echocardiography and MRA or CT scanning from head to pelvis is recommended to establish the extent of vascular involvement. Management involves early surgical intervention, including early valve-sparing aortic root replacement, genetic counselling and close monitoring in pregnancy. Despite being caused by loss of function mutations in either TGFβ receptor, paradoxical activation of TGFβ signalling is seen, suggesting that TGFβ antagonism may confer disease modifying effects similar to those observed in MFS. TGFβ antagonism can be achieved with angiotensin antagonists, such as Losartan, which is able to delay aortic aneurysm development in preclinical models and in patients with MFS. Our case emphasizes the importance of timely recognition of vasculopathy syndromes in patients with hypermobility and the need for early surgical intervention. It also highlights their heterogeneity and the potential for late presentation. Disclosures: The authors have declared no conflicts of interes

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Physiology of floral induction in Protea spp

Thesis (MSc)--University of Stellenbosch, 2005.ENGLISH ABSTRACT: The aim of this study was to elucidate the control of flowering in Protea spp. The main factor that makes studying flowering in this diverse genus so challenging is the fact that most Protea spp. and their commercial hybrids have very dissimilar flowering times. The carbon input into floral organ formation and support is expensive as flowers from Protea spp are arranged in a very large ‘flowerhead’ (50 mm by 130 mm for ‘Carnival’) that can take up to two months to develop fully. Therefore the carbon needed for structural formation, metabolic respiration and the sugar-rich nectar production make these structures extremely expensive to form and maintain. Protea is a sclerophyllous, woody perennial shrub with a seasonal flush growth habit. The leathery leaves (source tissue) produce most of the carbon needed for support and growth of the new leaves, roots and flowers (sink tissue). In the case of expensive structures, such as the inflorescences, remobilization from stored reserves, probably from underground storage systems, can be observed for structural development and maintenance. At all times the flush subtending the apical meristem or florally developing bud provides the largest proportion of carbon for support of the heterotrophic structures. Protea apical meristems stay dormant during the winter months, but BA (benzyl adenine, 6-benzylaminopurine) application to the apical meristem of the Protea hybrid ‘Carnival’ has shown to be effective in the release of dormancy and subsequently shift flowering two months earlier than the natural harvesting time. BA is thought to shift source/sink relationships by stimulating the remobilization of carbon to the resting meristem. Although no direct evidence was found for this in our assay, possible reasons for a weak assay are discussed. This study combined physiological research with the use of molecular tools. An homologue of the Arabidopsis thaliana meristem identity gene, LEAFY, was identified in Proteaceae. PROFL (PROTEA FLORICAULA LEAFY) is expressed in both vegetative and reproductive meristems as well as leaves. PROFL expression in leaves may have an inhibitory effect on vegetative growth, as the expression was high at the same time as the expression in the apical meristem increased marking the transition to reproductive growth. In perennial species such as Protea, the availability of carbon is thought to be the main factor controlling floral development. Possible mechanisms of control may be through the direct control of meristem identity genes such as PROFL through sugar signaling. BA did not have a direct effect on PROFL expression although the expression pattern was one month in advance when compared to the natural system. PROFL expression seems to be consistent with that found for other woody perennial species and would therefore be a convenient marker for floral transition.AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die inisiëring van blomvorming in Protea spp. te ondersoek. Die verskil in blomtyd tussen Protea spp. en hul kommersieel ontwikkelde hibriede maak die studie van hierdie genus ‘n groot uitdaging. Die groot hoeveelheid koolstof wat benodig word vir blomvorming in Protea is hoofsaaklik as gevolg van die grootte (50 mm by 130 mm vir ‘Carnival’) van die blomkop waarin individuele blomme geranskik is. Hierdie blomkoppe kan tot 2 maande neem om volwassenheid te bereik. Die koolstof benodig vir strukturele ontwikkeling, metaboliese respirasie en produksie van suiker-ryke nektar maak die vorming van hierdie structure ongelooflik duur. Protea is ‘n bladhoudende, houtagtige bos met ‘n seisoenale groeipatroon. Die leeragtige blare voorsien die grootste hoeveelheid koolstof vir die ontwikkelende blare, wortels en blomme. Koolstof vir die ontwikkeling en ondersteuning van die groot stukture soos die blomkoppe word gedeeltelik deur die huidige fotosinfaat voorsien en bewyse vir die remobilisasie van gestoorde koolstof, heel waarskynlik vanaf ondergrondse stukture, is gevind. Die blare van die stemsegment wat die apikale meristeem of ontwikkelende blom dra, voorsien altyd die grootse hoeveelheid koolhidrate aan die ontwikkelende struktuur. Die apikale meristeme van Protea bly dormant gedurende die winter maande, maar applikasie van BA (bensieladenien, 6-bensielaminopurien) aan die apikale meristeme van die Protea hibried ‘Carnival’ verbreek dormansie en die blomtyd van hierdie gemanipuleerde plante is daarom twee maande vroeër as die natuurlike oestyd. Daar word gespekuleer dat BA applikasie aan die apikale meristeem die hoeveelheid koolstof wat na die dormante meristeem gestuur word verhoog wat dan die dormansie verbreek. Hierdie studie beproef ongelukkig hierdie hipotese swak en redes hiervoor word bespreek. In hierdie studie word fisiologiese analises met molekulêre studies gekombineer. ‘n Meristeem identiteits gene wat homologie wys met LEAFY (LFY) in Arabidopsis thaliana (Arabidopsis), PROFL (PROTEA FLORICAULA LEAFY), is in Proteaceae geïdentifiseer. PROFL word uitgedruk in reproduktiewe meristeme so wel as die vegetatiewe meristeme en blare. PROFL uitdrukking in blare mag dalk ‘n inhiberende effek hê op die vorming van nuwe blare, omdat die uitdrukking hoog was op die selfde tyd as wat blominisiëring plaasgevind het in die apikale meristeem. Die transisie tot reproduktiewe groei word gekenmerk deur ‘n verhoging in PROFL uitdrukking in die apikale meristeem. In meerjarige plante soos Protea spp word daar verwag dat die teenwoordigheid van voldoende koolstof die oorskakeling na reproduktiewe groei inisieer. Dit mag wees deur die direkte aksie van suikers met gene soos PROFL wat die finale skakel na reproduktiewe groei beheer. Alhoewel BA applikasie geen direkte effek gehad het op PROFL uitdrukking nie, was die blomtyd met twee maande vervroeg. PROFL uitdrukking was vergelykbaar met die uitdrukking van LFY homoloë in ander houtagtige, meerjarige plante en kan gebruik word as ‘n merker vir blominisiëring in Protea spp

A small-scale RNA isolation protocol useful for high-throughput extractions from recalcitrant plants

Many plants indigenous to South Africa are rich in secondary and oxidizing compounds such as pigments, complex polysaccharides and polyphenols. This makes isolation of high quality RNA for analysis of gene expression difficult. Here we describe a cost-effective isolation protocol suitable for RNA extraction from recalcitrant plant species. This method uses small amounts of tissue, so is useful when material is limited, and is easy to process large numbers of samples at once. We have used the method successfully with mature leaves of Protea hybrid ‘Sylvia’, and species P. repens, Leucospermum hybrid ‘Succession’, resurrection plants Xerophyta humilis and Craterostigma pumilum, and mature needles of Pine (Pinus radiata). RNA was analyzed spectrophotometrically and was found to be of high purity with low levels of contaminating compounds. Electrophoretic analyses on denaturing formaldehyde agarose gels and an Agilent 2100 Bioanalyzer confirmed the presence of RNA of high integrity. This is the first description of plant RNA integrity number (RIN) values for these plants using the algorithm designed for analyses of plant RNA containing multiple ribosomal bands. The RNA could successfully be used for reverse transcription and gene amplification

Investigating the Electrochemical Interaction of a Thiol Collector with Chalcopyrite and Galena in the Presence of a Mixed Microbial Community

| openaire: EC/H2020/730480/EU//ITERAMSHigh microbial cell counts have been recorded in sewage waters employed as process water in mineral beneficiation plants across the world. The presence of these microbes can negatively impact flotation performance through mineral passivation, although some microbes improve flotation performance as investigated in various bio-flotation studies. The current study aims to understand the electrochemical behaviour of minerals in the presence of a sodium ethyl xanthate (SEX) collector and microbes originating from a sulphide ore processing plant in South Africa. The electrochemical response was correlated to observe flotation performance. Mixed potential measurements were conducted in parallel to microflotation tests, to assess the hydrophilicity or hydrophobicity induced on sulphide minerals adapted to microbe-laden synthetic plant water. Sulphide minerals' mixed potentials and interactions of SEX with sulphide minerals were dramatically reduced in the presence of the mixed microbial community (MMC). The observations were correlated with poor flotation efficacy noted in microflotation tests. These fundamental results shed light on how the adsorption of thiol collectors on sulphide minerals is adversely affected by microbes, prompting a discussion on flotation process monitoring when mineral beneficiation is conducted using microbe-laden water.Peer reviewe