A benign approach to the preparation of freshwater bryozoan statoblasts for scanning electron microscopy (SEM) imaging

Abstract

Several different species of freshwater Bryozoa, belonging to the genera Plumatella, Rumarcanella and Fredericella, were detected within the Northern Mallee Pipeline (NMP) system in Victoria, Australia, that required definitive identification. These organisms produce asexual buds called statoblasts, with valves composed of sclerotised chitin that bear minute micro-ornamentations of considerable taxonomical significance. Imaging and analysis of these distinctive micro-ornamentations using scanning electron microscopy (SEM) is often employed for species identification. Meticulous preparation of statoblast samples is therefore required that necessitates the removal of adhering debris, dehydration and drying—whilst mitigating specimen damage and distortion. This technical note describes an approach whereby each of these three steps have been individually designed to be as benign as possible, using mild detergent/sonication to remove debris, a gradual and gentle dehydration procedure using ethanol, and critical point drying. For the overall process, these methods are chosen to optimise control and to minimise the use of harsh and hazardous chemicals.     

The use of adjunctive GPIIb/IIIa inhibitors in patients with unstable angina/non-Q-wave MI undergoing percutaneous coronary intervention

Glycoprotein IIb/IIIa receptor inhibitors represent a relatively new therapeutic approach in the field of antiplatelet therapy. Following the development of abciximab a number of small molecule GPIIb/IIIa inhibitors have been introduced such as tirofiban and eptifibatide. In this fast-moving field the interventional cardiologist needs a framework to guide decision-making for the individual patient. This review covers the efficacy and safety data from the clinical trials of GPIIb/IIIa inhibitors in the context of patients undergoing percutaneous coronary intervention for unstable angina/non-Q-wave myocardial infarction. There is an increasing body of evidence to support the efficacy of GPIIb/IIIa inhibitors in reducing the risk of adverse ischemic events in high and low risk patients undergoing percutaneous coronary intervention. A number of unresolved efficacy and safety issues remain, including the duration of treatment before and after intervention; whether a reduction in the heparin dose would further decrease the risk of hemorrhage without affecting the periprocedural thrombotic rate in patients undergoing PTCA with adjunctive GPIIb/IIIa inhibitors; and the cost-effectiveness of this therapy. When a thorough analysis of cost-effectiveness has been made, it will be easier to advocate the widespread use of these agents in all patients undergoing coronary intervention.     

The fermentation of sugarcane molasses by Dekkera bruxellensis and the mobilization of reserve carbohydrates

The yeast Dekkera bruxellensis is considered to be very well adapted to industrial environments, in Brazil, USA, Canada and European Countries, when different substrates are used in alcoholic fermentations. Our previous study described its fermentative profile with a sugarcane juice substrate. In this study, we have extended its physiological evaluation to fermentation situations by using sugarcane molasses as a substrate to replicate industrial working conditions. The results have confirmed the previous reports of the low capacity of D. bruxellensis cells to assimilate sucrose, which seems to be the main factor that can cause a bottleneck in its use as fermentative yeast. Furthermore, the cells of D. bruxellensis showed a tendency to deviate most of sugar available for biomass and organic acids (lactic and acetic) compared with Saccharomyces cerevisiae, when calculated on the basis of their respective yields. As well as this, the acetate production from molasses medium by both yeasts was in marked contrast with the previous data on sugarcane juice. Glycerol and ethanol production by D. bruxellensis cells achieved levels of 33 and 53 % of the S. cerevisiae, respectively. However, the ethanol yield was similar for both yeasts. It is worth noting that this yeast did not accumulate trehalose when the intracellular glycogen content was 30 % lower than in S. cerevisiae. The lack of trehalose did not affect yeast viability under fermentation conditions. Thus, the adaptive success of D. bruxellensis under industrial fermentation conditions seems to be unrelated to the production of these reserve carbohydrates.     

A high-throughput cloning system for reverse genetics in <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis>

Background  

The three trypanosomatids pathogenic to men, Trypanosoma cruzi, Trypanosoma brucei and Leishmania major, are etiological agents of Chagas disease, African sleeping sickness and cutaneous leishmaniasis, respectively. The complete sequencing of these trypanosomatid genomes represented a breakthrough in the understanding of these organisms. Genome sequencing is a step towards solving the parasite biology puzzle, as there are a high percentage of genes encoding proteins without functional annotation. Also, technical limitations in protein expression in heterologous systems reinforce the evident need for the development of a high-throughput reverse genetics platform. Ideally, such platform would lead to efficient cloning and compatibility with various approaches. Thus, we aimed to construct a highly efficient cloning platform compatible with plasmid vectors that are suitable for various approaches.     

Resistance of tomato genotypes to the greenhouse whitefly Trialeurodes vaporariorum (West.) (Hemiptera: Aleyrodidae)

The greenhouse whitefly, Trialeurodes vaporariorum Westwood, is the most common and abundant whitefly in Argentine horticultural greenhouse crops, especially in tomato (Solanum lycopersicum). Resistance in some wild tomato relatives, such as S. peruvianum, S. habrochaites and S. pennellii to the greenhouse whitefly has been described. The Mi gene confers effective resistance against several species of insects, among them the sweet potato whitefly, Bemisia tabaci Gennadius. Resistance to T. vaporariorum was found in the prebreeding line FCN 93-6-2, derived from a cross between S. lycopersicum cultivar Uco Plata INTA (MiMi) and the wild line FCN 3-5 S. habrochaites. The purpose of this study was to evaluate resistance to T. vaporariorum in tomato genotypes and to study the relationship between this resistance and the presence of the REX-1 marker, which is linked to the Mi gene. In a free-choice assay, the average number of adults per leaf and the number of immatures on the middle and basal plant parts were analyzed. In a no-choice assay, the oviposition rate and adult survival rate were calculated. For all variables analyzed, FCN 3-5 was the most resistant strain. Variations were found in the F2 progeny between the prebreeding line FCN 13-1-6-1 and cv. Uco Plata INTA. Results from the F2 progeny indicate that resistance to T. vaporariorum may be polygenic with transgressive segregation. Whitefly resistance was found to be independent of the REX-1 marker.     

Immunoprophylaxis of respiratory syncytial virus: global experience

In sarcoidosis, host genetic factors are discussed as contributing to disease susceptibility and course. Since tumor necrosis factor (TNF)-α is a central mediator of granuloma formation and since elevated TNF-α levels are found during active phases of sarcoidosis, genetic polymorphisms correlating with influences on TNF-α levels are of special interest. The complete sequencing of the MHC region and the increase in the number of identified gene polymorphisms in this locus associated with TNF-α production offer the opportunity of detecting new genes associated with sarcoidosis and perhaps of defining disease-associated haplotypes that bear the potential of serving as predictive markers for this disease.     

Flexibility in crosstalk between H2B ubiquitination and H3 methylation in vivo

Histone H2B ubiquitination is a dynamic modification that promotes methylation of histone H3K79 and H3K4. This crosstalk is important for the DNA damage response and has been implicated in cancer. Here, we show that in engineered yeast strains, ubiquitins tethered to every nucleosome promote H3K79 and H3K4 methylation from a proximal as well as a more distal site, but only if in a correct orientation. This plasticity indicates that the exact location of the attachment site, the native ubiquitin-lysine linkage and ubiquitination cycles are not critical for trans-histone crosstalk in vivo. The flexibility in crosstalk also indicates that other ubiquitination events may promote H3 methylation.