Deformation properties of single red blood cell in a stenosed microchannel

Red Blood Cells (RBCs) exhibit different types of motions and different deformed shapes, when they move through capillaries. RBCs can travel through capillaries having smaller diameters than RBCs’ diameter, due to the capacity of high deformability of the viscoelastic RBC membrane. The motion and the steady state shape of the RBCs depend on many factors, such as the geometrical parameters of the microvessel through which blood flows, the RBC membrane bending stiffness and the flow velocity. In this study, the effect of the RBC’s membrane stiffness on the deformation of a single RBC in a stenosed capillary is comprehensively examined. Smoothed Particle Hydrodynamics (SPH) in combination with the two-dimensional spring network membrane model is used to investigate the motion and the deformation property of the RBC. The simulation results demonstrate that the membrane bending stiffness of the RBC has a significant impact on the RBCs’ deformability.

Carrot red leaf and carrot mottle viruses : observations on the composition of the particles in single and mixed infections

Particles of carrot red leaf virus (CRLV; luteovirus group) purified from chervil (Anthriscus cerefolium) contain a single ssRNA species of mol. wt. about 1.8 x 106 and a major protein of mol. wt. about 25000. CRLV acts as a helper for aphid transmission of carrot mottle virus (CMotV; ungrouped) from mixedly infected plants. Virus preparations purified from such plants possess the infectivity of both viruses but contain particles indistinguishable from those of CRLV; some of the particles are therefore thought to consist of CMotV RNA packaged in CRLV coat protein. When RNA from such preparations was electrophoresed in agarose/polyacrylamide gels, CMotV infectivity was associated with an RNA band that migrated ahead of the CRLV RNA band and had an estimated mol. wt. of about 1.5 x 106, similar to that previously found for the infective ssRNA extracted directly from Nicotiana clevelandii leaves infected with CMotV alone. Preparations of dsRNA from CMotV-infected N. clevelandii leaves contained two species: one of mol. wt. about 3.2 x 106, presumably the replicative form of the infective ssRNA, and the other, mol. wt. about 0.9 x 106, of unknown origin and function. The infective agent in buffer extracts of CMotV-infected N. clevelandii was resistant to RNase (although the enzyme acted as a reversible inhibitor of infection at high concentrations) and is therefore not unprotected RNA. It may be protected within the approximately 52 nm enveloped structures previously reported.

Purification of particles of subterranean clover red leaf virus using an industrial-grade cellulase

Particles of two isolates of subterranean clover red leaf virus were purified by a method in which infected plant tissue was digested with an industrial-grade cellulase, Celluclast® 2.0 L type X. The yields of virus particles using this enzyme were comparable with those obtained using either of two laboratory-grade cellulases, Cellulase type 1 (Sigma) and Driselase®. However, the specific infectivity or aphid transmissibility of the particles purified using Celluclast® was 10-100 times greater than those of preparations obtained using laboratory-grade cellulases or no enzyme. The main advantage of using Celluclast® is that at present in Australia its cost is only ca. 1% of laboratory-grade cellulases.

Neutrophil oxidative burst is primed by supernatant from stored red cells : implications for Transfusion-Related Acute Lung Injury (TRALI)

Aim/Background: Transfusion-related acute lung injury (TRALI) is a potentially fatal adverse transfusion reaction. It is hypothesised to occur via a two-insult mechanism: the recipient’s underlying co-morbidity in addition to the transfusion of blood products activate neutrophils in the lung resulting in damaged endothelium and capillary leakage. Neutrophil activation may occur by antibody or non-antibody related mechanisms, with the length of storage of cellular blood products implicated in the latter. This study investigated non-antibody mediated priming and/or activation of neutrophil oxidative burst. Methods: A cytochrome C reduction assay was used to assess priming and activation of neutrophil oxidative burst by pooled supernatant (SN) from day 1 (D1; n=75) and day 42 (D42; n=113) packed red blood cells (PRBC). Pooled PRBC-SN were assessed in parallel with PAF (priming), fMLP (activating), PAF + fMLP (priming + activating) and buffer only (negative) controls. Cytochrome C reduction was measured over 30min at 37oC (inclusive of 10min priming). Neutrophil activation by PRBC-SN was assessed cf. buffer only and neutrophil priming by PRBC-SN was assessed by co-incubation with fMLP cf. fMLP alone. One-way ANOVA; Newman-Keuls post-test; p<0.05; n=10 independent assays. Results: Neither D1- nor D42- PRBC-SN alone activated neutrophil oxidative burst. In addition, D1-PRBC-SN did not prime fMLP-activated neutrophil oxidative burst. D42-PRBC-SN did, however, prime neutrophils for subsequent activation of oxidative burst by fMLP, the magnitude of response being similar to PAF (a known neutrophil priming agonist). Conclusion: These findings are consistent with the two-insult mechanism of TRALI. Factors released into the SN during PRBC storage contributed to neutrophil priming synergistically with other neutrophil stimulating agonists. This implicates PRBC storage duration as a key factor contributing to non-immune neutrophil activation in the development of TRALI in patients with pre-disposing inflammatory conditions.

I still dream of my grandfather's red roses

"I still dream of my grandfather's red roses" is an online audio documentary. Asking people from her community to make a statement beginning with the words "I dream of", Australian documentarist Phoebe Hart curates these fragments and creatively envisages the literal and figurative world of dreams, arresting our collective hopes, desires and fears.

Beef production and the environment : is it really 'hard to be green when you are in the red'?

The statement. 'it is hard to be green when you are in the red' is commonly used by primary producers to explain the necessity of placing a greater emphasis on financial survival rather than longer term environmental sustainability. The subject of environmental sustainability on pastoral properties was explored during face-to:face interviews with cattle grazers in the Fitzroy Basin area of Central Queensland. Findings from the study suggest that while economic factors are important, they are not the only determinant in whether a landholder priorities environmental sustainability, Rather. social factors such as knowledge claims. beliefs, attitudes. values, peer pressure and social sanctioning, constructed and enacted within the productivist paradigm of primary production. play a crucial role in how landholders manage their natural assets. This suggests that the edict that 'It is hard to be green when you are in the red' is inaccurate and does not explain why conservation-focused pastoral management is not yet occurring on a large scale.

Characterization of ENU-induced mutations in red blood cell structural proteins

Murine models with modified gene function as a result of N-ethyl-N-nitrosourea (ENU) mutagenesis have been used to study phenotypes resulting from genetic change. This study investigated genetic factors associated with red blood cell (RBC) physiology and structural integrity that may impact on blood component storage and transfusion outcome. Forward and reverse genetic approaches were employed with pedigrees of ENU-treated mice using a homozygous recessive breeding strategy. In a “forward genetic” approach, pedigree selection was based upon identification of an altered phenotype followed by exome sequencing to identify a causative mutation. In a second strategy, a “reverse genetic” approach based on selection of pedigrees with mutations in genes of interest was utilised and, following breeding to homozygosity, phenotype assessed. Thirty-three pedigrees were screened by the forward genetic approach. One pedigree demonstrated reticulocytosis, microcytic anaemia and thrombocytosis. Exome sequencing revealed a novel single nucleotide variation (SNV) in Ank1 encoding the RBC structural protein ankyrin-1 and the pedigree was designated Ank1EX34. The reticulocytosis and microcytic anaemia observed in the Ank1EX34 pedigree were similar to clinical features of hereditary spherocytosis in humans. For the reverse genetic approach three pedigrees with different point mutations in Spnb1 encoding RBC protein spectrin-1β, and one pedigree with a mutation in Epb4.1, encoding band 4.1 were selected for study. When bred to homozygosity two of the spectrin-1β pedigrees (a, b) demonstrated increased RBC count, haemoglobin (Hb) and haematocrit (HCT). The third Spnb1 mutation (spectrin-1β c) and mutation in Epb4.1 (band 4.1) did not significantly affect the haematological phenotype, despite these two mutations having a PolyPhen score predicting the mutation may be damaging. Exome sequencing allows rapid identification of causative mutations and development of databases of mutations predicted to be disruptive. These tools require further refinement but provide new approaches to the study of genetically defined changes that may impact on blood component storage and transfusion outcome.

An R2R3 MYB transcription factor determines red petal colour in an Actinidia (kiwifruit) hybrid population

Background Red colour in kiwifruit results from the presence of anthocyanin pigments. Their expression, however, is complex, and varies among genotypes, species, tissues and environments. An understanding of the biosynthesis, physiology and genetics of the anthocyanins involved, and the control of their expression in different tissues, is required. A complex, the MBW complex, consisting of R2R3-MYB and bHLH transcription factors together with a WD-repeat protein, activates anthocyanin 3-O-galactosyltransferase (F3GT1) to produce anthocyanins. We examined the expression and genetic control of anthocyanins in flowers of Actinidia hybrid families segregating for red and white petal colour. Results Four inter-related backcross families between Actinidia chinensis Planch. var. chinensis and Actinidia eriantha Benth. were identified that segregated 1:1 for red or white petal colour. Flower pigments consisted of five known anthocyanins (two delphinidin-based and three cyanidin-based) and three unknowns. Intensity and hue differed in red petals from pale pink to deep magenta, and while intensity of colour increased with total concentration of anthocyanin, no association was found between any particular anthocyanin data and hue. Real time qPCR demonstrated that an R2R3 MYB, MYB110a, was expressed at significant levels in red-petalled progeny, but not in individuals with white petals. A microsatellite marker was developed that identified alleles that segregated with red petal colour, but not with ovary, stamen filament, or fruit flesh colour in these families. The marker mapped to chromosome 10 in Actinidia. The white petal phenotype was complemented by syringing Agrobacterium tumefaciens carrying Actinidia 35S::MYB110a into the petal tissue. Red pigments developed in white petals both with, and without, co-transformation with Actinidia bHLH partners. MYB110a was shown to directly activate Actinidia F3GT1 in transient assays. Conclusions The transcription factor, MYB110a, regulates anthocyanin production in petals in this hybrid population, but not in other flower tissues or mature fruit. The identification of delphinidin-based anthocyanins in these flowers provides candidates for colour enhancement in novel fruits.

Analysis of genetically modified red-fleshed apples reveals effects on growth and consumer attributes

Consumers of whole foods, such as fruits, demand consistent high quality and seek varieties with enhanced health properties, convenience or novel taste. We have raised the polyphenolic content of apple by genetic engineering of the anthocyanin pathway using the apple transcription factor MYB10. These apples have very high concentrations of foliar, flower and fruit anthocyanins, especially in the fruit peel. Independent lines were examined for impacts on tree growth, photosynthesis and fruit characteristics. Fruit were analysed for changes in metabolite and transcript levels. Fruit were also used in taste trials to study the consumer perception of such a novel apple. No negative taste attributes were associated with the elevated anthocyanins. Modification with this one gene provides near isogenic material and allows us to examine the effects on an established cultivar, with a view to enhancing consumer appeal independently of other fruit qualities. © 2012 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

An ancient duplication of apple MYB transcription factors is responsible for novel red fruit-flesh phenotyp

Anthocyanin accumulation is coordinated in plants by a number of conserved transcription factors. In apple (Malus × domestica), an R2R3 MYB transcription factor has been shown to control fruit flesh and foliage anthocyanin pigmentation (MYB10) and fruit skin color (MYB1). However, the pattern of expression and allelic variation at these loci does not explain all anthocyanin-related apple phenotypes. One such example is an open-pollinated seedling of cv Sangrado that has green foliage and develops red flesh in the fruit cortex late in maturity. We used methods that combine plant breeding, molecular biology, and genomics to identify duplicated MYB transcription factors that could control this phenotype. We then demonstrated that the red-flesh cortex phenotype is associated with enhanced expression of MYB110a, a paralog of MYB10. Functional characterization of MYB110a showed that it was able to up-regulate anthocyanin biosynthesis in tobacco (Nicotiana tabacum). The chromosomal location of MYB110a is consistent with a whole-genome duplication event that occurred during the evolution of apple within the Maloideae family. Both MYB10 and MYB110a have conserved function in some cultivars, but they differ in their expression pattern and response to fruit maturity.

Mapping a candidate gene (MdMYB10) for red flesh and foliage colour in apple

BACKGROUND Integrating plant genomics and classical breeding is a challenge for both plant breeders and molecular biologists. Marker-assisted selection (MAS) is a tool that can be used to accelerate the development of novel apple varieties such as cultivars that have fruit with anthocyanin through to the core. In addition, determining the inheritance of novel alleles, such as the one responsible for red flesh, adds to our understanding of allelic variation. Our goal was to map candidate anthocyanin biosynthetic and regulatory genes in a population segregating for the red flesh phenotypes. RESULTS We have identified the Rni locus, a major genetic determinant of the red foliage and red colour in the core of apple fruit. In a population segregating for the red flesh and foliage phenotype we have determined the inheritance of the Rni locus and DNA polymorphisms of candidate anthocyanin biosynthetic and regulatory genes. Simple Sequence Repeats (SSRs) and Single Nucleotide Polymorphisms (SNPs) in the candidate genes were also located on an apple genetic map. We have shown that the MdMYB10 gene co-segregates with the Rni locus and is on Linkage Group (LG) 09 of the apple genome. CONCLUSION We have performed candidate gene mapping in a fruit tree crop and have provided genetic evidence that red colouration in the fruit core as well as red foliage are both controlled by a single locus named Rni. We have shown that the transcription factor MdMYB10 may be the gene underlying Rni as there were no recombinants between the marker for this gene and the red phenotype in a population of 516 individuals. Associating markers derived from candidate genes with a desirable phenotypic trait has demonstrated the application of genomic tools in a breeding programme of a horticultural crop species.

Effect of strong acids on red mud structural and fluoride adsorption properties

The removal of fluoride using red mud has been improved by acidifying red mud with hydrochloric, nitric and sulphuric acid. This investigation shows that the removal of fluoride using red mud is significantly improved if red mud is initially acidified. The acidification of red mud causes sodalite and cancrinite phases to dissociate, confirmed by the release of sodium and aluminium into solution as well as the disappearance of sodalite bands and peaks in infrared and X-ray diffraction data. The dissolution of these mineral phases increases the amount of available iron and aluminium oxide/hydroxide sites that are accessible for the adsorption of fluoride. The removal of fluoride is dependent on the charge of iron and aluminium oxide/hydroxides on the surface of red mud. Acidifying red mud with hydrochloric, nitric and sulphuric acid resulted in surface sites of the form ≡ SOH2+ and ≡ SOH. Optimum removal is obtained when the majority of surface sites are in the form ≡ SOH2+ as the substitution of a fluoride ion doesn’t cause a significant increase in pH. This investigation shows the importance of having a low and consistent pH for the removal of fluoride from aqueous solutions using red mud.

Identification and characterisation of F3GT1 and F3GGT1, two glycosyltransferases responsible for anthocyanin biosynthesis in red-fleshed kiwifruit (Actinidia chinensis)

Much of the diversity of anthocyanins is due to the action of glycosyltransferases, which add sugar moieties to anthocyanidins. We identified two glycosyltransferases, F3GT1 and F3GGT1, from red-fleshed kiwifruit (Actinidia chinensis) that perform sequential glycosylation steps. Red-fleshed genotypes of kiwifruit accumulate anthocyanins mainly in the form of cyanidin 3-O-xylo-galactoside. Genes in the anthocyanin and flavonoid biosynthetic pathway were identified and shown to be expressed in fruit tissue. However, only the expression of the glycosyltransferase F3GT1 was correlated with anthocyanin accumulation in red tissues. Recombinant enzyme assays in vitro and in vivo RNA interference (RNAi) demonstrated the role of F3GT1 in the production of cyanidin 3-O-galactoside. F3GGT1 was shown to further glycosylate the sugar moiety of the anthocyanins. This second glycosylation can affect the solubility and stability of the pigments and modify their colour. We show that recombinant F3GGT1 can catalyse the addition of UDP-xylose to cyanidin 3-galactoside. While F3GGT1 is responsible for the end-product of the pathway, F3GT1 is likely to be the key enzyme regulating the accumulation of anthocyanin in red-fleshed kiwifruit varieties.