Abnormal haemoglobins in Cape Town

No Abstract

Genome sequence of an alkaliphilus species isolated from historically contaminated sediments of the gulf of Naples (Mediterranean Sea)

Here, we report the draft genome sequence of a metagenome-assembled genome (MAG) of a new Alkaliphilus bacterium, NP8, of the Clostridiaceae family. This bacterium was isolated from polluted sediment collected from an abandoned industrial site located in the Gulf of Naples (Mediterranean Sea) as part of a microbial consortium

Hosts, seasonal occurrence and life cycle of Rhipicentor nuttalli (Acari: Ixodidae)

There are only two species worldwide within the genus Rhipicentor, namely Rhipicentor bicornis and Rhipicentor nuttalli, and both occur only in Africa. Rhipicentor nuttalli has a widespread distribution in South Africa and the present investigation was initiated to elucidate its host preference, seasonality and life cycle. Rock elephant shrews, Elephantulus myurus, were examined for ticks at four localities in the Free State Province, one in Gauteng Province and two in Limpopo Province, South Africa. Cape elephant shrews, Elephantulus edwardii, were examined at two places in the Western Cape Province, and a single specimen of the bushveld elephant shrew, Elephantulus intufi, was examined in central Namibia. Small mammals of other species were also examined at two of these localities. The majority of E. myurus at two sites in the Free State, at the locality in Gauteng and both sites in Limpopo Province were infested with larvae and/or nymphs of R. nuttalli, while the single E. edwardii examined at one site in the Western Cape Province and the single E. intufi examined in Namibia were infested with nymphs of this tick. Not one of the other small animals was infested. Although larvae and nymphs of R. nuttalli were present on E. myurus throughout the year, the former were generally most numerous during the period March to September, and the latter during May to October. The preferred hosts of the adults are domestic dogs, leopards, Panthera pardus and South African hedgehogs, Atelerix frontalis. Adult females engorged on Atelerix frontalis in 16-32 days and, after a preoviposition period of 2-4 days, produced approximately 17 000 eggs during the following 60-70 days. The average incubation period of the eggs was 59 days. Larvae engorged on E. myurus in 4-10 days and moulted to nymphs 12-20 days later. Nymphs required 11-15 days to engorge on E. myurus and moulted to adults 32-47 days later. Allowing 14 days for the exoskeletons and mouthparts of each of the three parasitic stages to harden before they can attach to a host, the life cycle took approximately 214 days to complete in the laboratory. The length of this period, considered in conjunction with the times of maximum seasonal occurrence of the immature stages, indicates that the life cycle probably takes a year to complete in the field.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.University of the Free State. Foundation for Research Development (now National Research Foundation).mn201

Mitocondrial COI and 16S rDNA sequences support morphological identification and biogeography of deep-sea red crabs of the genus Chaceon (Crustacea, Decapoda, Geryonidae) in the Eastern Central and South Atlantic Ocean

The geographical spreading of new fishing activities and the increasingly deeper locations of these activities have shown the worldwide distribution of gerionid crabs and new descriptions of Chaceon taxa. However, incomplete penetrance, variable expressivity, and phenotypic overlap make the morphometric identification of these species difficult. In this study, partial sequences of the cytochrome c oxidase subunit 1 (COI) and 16S mitochondrial ribosomal RNA (16S rRNA) genes have been analyzed in Chaceon species from the Eastern Central and South Atlantic and compared with sequences of species from Western Atlantic. Our results corroborate the proposed morphological species and highlight the significant separation of the Eastern Atlantic species and those from Atlantic coasts of South America for both markers (97% Bayesian posterior probability, BPP / 83% Bootstrap replicates, BT). Interestingly, Chaceon sanctaehelenae shows a closer relationship with the species of the American coast than with those from the Eastern Atlantic. On the other hand, while COI marker clearly separates Chaceon atopus and Chaceon erytheiae species (99 BPP / 91% BT), these species share haplotypes for the 16S rRNA marker, pointing to a recent speciation process. Moreover, a close relationship was observed between Chaceon maritae and Chaceon affinis (94% BPP / 77% BT). The topologies of the trees obtained indicate that the ancestor of this genus was closer related to those species from South America than to those from the Eastern Atlantic.Versión del edito

Biorefining of wood: Combined production of ethanol and xylanase from waste fiber sludge

The possibility to utilize fiber sludge, waste fibers from pulp mills and lignocellulose-based biorefineries, for combined production of liquid biofuel and biocatalysts was investigated. Without pretreatment, fiber sludge was hydrolyzed enzymatically to monosaccharides, mainly glucose and xylose. In the first of two sequential fermentation steps, the fiber sludge hydrolysate was fermented to cellulosic ethanol with the yeast Saccharomyces cerevisiae. Although the final ethanol yields were similar, the ethanol productivity after 9.5 h was 3.3 g/l/h for the fiber sludge hydrolysate compared with only 2.2 g/l/h for a reference fermentation with similar sugar content. In the second fermentation step, the spent fiber sludge hydrolysate (the stillage obtained after distillation) was used as growth medium for recombinant Aspergillus niger expressing the xylanase-encoding Trichoderma reesei (Hypocrea jecorina) xyn2 gene. The xylanase activity obtained with the spent fiber sludge hydrolysate (8,500 nkat/ml) was higher than that obtained in a standard medium with similar monosaccharide content (1,400 nkat/ml). Analyses based on deglycosylation with N-glycosidase F suggest that the main part of the recombinant xylanase was unglycosylated and had molecular mass of 20.7 kDa, while a minor part had N-linked glycosylation and molecular mass of 23.6 kDa. Chemical analyses of the growth medium showed that important carbon sources in the spent fiber sludge hydrolysate included xylose, small aliphatic acids, and oligosaccharides. The results show the potential of converting waste fiber sludge to liquid biofuel and enzymes as coproducts in lignocellulose-based biorefineries. © 2010 Society for Industrial Microbiology.Articl

Molecular analysis of a Saccharomyces cerevisiae mutant with improved ability to utilize xylose shows enhanced expression of proteins involved in transport, initial xylose metabolism, and the pentose phosphate pathway

Differences between the recombinant xylose-utilizing Saccharomyces cerevisiae strain TMB 3399 and the mutant strain TMB 3400, derived from TMB 3399 and displaying improved ability to utilize xylose, were investigated by using genome-wide expression analysis, physiological characterization, and biochemical assays. Samples for analysis were withdrawn from chemostat cultures. The characteristics of S. cerevisiae TMB 3399 and TMB 3400 grown on glucose and on a mixture of glucose and xylose, as well as of S. cerevisiae TMB 3400 grown on only xylose, were investigated. The strains were cultivated under chemostat conditions at a dilution rate of 0.1 h-1, with feeds consisting of a defined mineral medium supplemented with 10 g of glucose liter-1, 10 g of glucose plus 10 g of xylose liter-1 or, for S. cerevisiae TMB 3400, 20 g of xylose liter-1. S. cerevisiae TMB 3400 consumed 31% more xylose of a feed containing both glucose and xylose than S. cerevisiae TMB 3399. The biomass yields for S. cerevisiae TMB 3400 were 0.46 g of biomass g of consumed carbohydrate-1 on glucose and 0.43 g of biomass g of consumed carbohydrate-1 on xylose. A Ks value of 33 mM for xylose was obtained for S. cerevisiae TMB 3400. In general, the percentage error was <20% between duplicate microarray experiments originating from independent fermentation experiments. Microarray analysis showed higher expression in S. cerevisiae TMB 3400 than in S. cerevisiae TMB 3399 for (i) HXT5, encoding a hexose transporter; (ii) XKS1, encoding xylulokinase, an enzyme involved in one of the initial steps of xylose utilization; and (iii) SOL3, GND1, TAL1, and TKL1, encoding enzymes in the pentose phosphate pathway. In addition, the transcriptional regulators encoded by YCR020C, YBR083W, and YPR199C were expressed differently in the two strains. Xylose utilization was, however, not affected in strains in which YCR020C was overexpressed or deleted. The higher expression of XKS1 in S. cerevisiae TMB 3400 than in TMB 3399 correlated with higher specific xylulokinase activity in the cell extracts. The specific activity of xylose reductase and xylitol dehydrogenase was also higher for S. cerevisiae TMB 3400 than for TMB 3399, both on glucose and on the mixture of glucose and xylose.Articl

Generation of the improved recombinant xylose-utilizing Saccharomyces cerevisiae TMB 3400 by random mutagenesis and physiological comparison with Pichia stipitis CBS 6054

The recombinant xylose-utilizing Saccharomyces cerevisiae TMB 3399 was constructed by chromosomal integration of the genes encoding D-xylose reductase (XR), xylitol dehydrogenase (XDH), and xylulokinase (XK). S. cerevisiae TMB 3399 was subjected to chemical mutagenesis with ethyl methanesulfonate and, after enrichment, 33 mutants were selected for improved growth on D-xylose and carbon dioxide formation in Durham tubes. The best-performing mutant was called S. cerevisiae TMB 3400. The novel, recombinant S. cerevisiae strains were compared with Pichia stipitis CBS 6054 through cultivation under aerobic, oxygen-limited, and anaerobic conditions in a defined mineral medium using only D-xylose as carbon and energy source. The mutation led to a more than five-fold increase in maximum specific growth rate, from 0.0255 h-1 for S. cerevisiae TMB 3399 to 0.14 h-1 for S. cerevisiae TMB 3400, whereas P. stipitis grew at a maximum specific growth rate of 0.44 h-1. All yeast strains formed ethanol only under oxygen-limited and anaerobic conditions. The ethanol yields and maximum specific ethanol productivities during oxygen limitation were 0.21, 0.25, and 0.30 g ethanol g xylose-1 and 0.001, 0.10, and 0.16 g ethanol g biomass-1 h-1 for S. cerevisiae TMB 3399, TMB 3400, and P. stipitis CBS 6054, respectively. The xylitol yield under oxygen-limited and anaerobic conditions was two-fold higher for S. cerevisiae TMB 3399 than for TMB 3400, but the glycerol yield was higher for TMB 3400. The specific activity, in U mg protein-1, was higher for XDH than for XR in both S. cerevisiae TMB 3399 and TMB 3400, while P. stipitis CBS 6054 showed the opposite relation. S. cerevisiae TMB 3400 displayed higher specific XR, XDH and XK activities than TMB 3399. Hence, we have demonstrated that a combination of metabolic engineering and random mutagenesis was successful to generate a superior, xylose-utilizing S. cerevisiae, and uncovered distinctive physiological properties of the mutant. © 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.Articl

Damring formation during rotary kiln chromite pre-reduction: Effects of pulverized carbonaceous fuel selection and partial pellet melting

Electricity consumption is the largest cost contributing factor in the production of ferrochrome. Currently the pelletized chromite pre-reduction process (solid-state reduction of chromite) is the process option with the lowest specific electricity consumption (MWh/ton). In this process, pelletized chromite is fed into a rotary kiln at 1573 K (1300 °C), where partial pre-reduction takes place. Damring formation (material build-up) in the rotary kiln causes routine shutdowns, resulting in loss of revenue. The damring formation is possibly caused by melting of the ash of the pulverized coal used to fire the kiln and/or the partial melting of the chromite pellets. Ash fusion temperatures of twenty different samples were evaluated to assess the temperature at which the pulverized coal ash will start to contribute to damring formation. Sessile drop tests were used to assess the softening behavior of different ore types (e.g., UG2, MG, and LG metgrade), as well as softening of composite chromite pellets made from these ores. Actual damrings were also analyzed using scanning electron microscopy with energy dispersive X-ray spectroscopy. Results indicate that it is mainly the pulverized coal ash that will contribute to damring formation, and not ore or pellet softening. Multiple-linear regression was used to derive equations to predict the ash fusion temperatures of the pulverized coal ash, which can be used by ferrochrome producers to optimize pulverized coal selection

A note on the estimator of the alpha coefficient for standardized variables under normality

standard deviation, reliability, Cronbach’s alpha, internal consistency,

Exact distributions of intraclass correlation and Cronbach's alpha with Gaussian data and general covariance

interrater reliability, confidence interval, compound symmetry, quadratic forms,