The small-subunit ribosomal RNA gene sequences from the hypotrichous ciliates Oxytricha nova and Stylonychia pustulata

We have determined the complete nucleotide sequence of the small- subunit ribosomal RNA genes for the ciliate protozoans Stylonychia pustulata and Oxytricha nova. The sequences are homologous and sufficiently similar that these organisms must be closely related. In a phylogeny inferred from comparisons of several eukaryotic small-subunit ribosomal RNAs, the divergence of the ciliates from the eukaryotic line of descent is seen to coincide with the radiation of the plants, the animals, and the fungi. This radiation is preceded by the divergence of the slime mold, Dictyostelium discoideum.      

Extracellular vesicle RNAs reflect placenta dysfunction and are a biomarker source for preterm labour

Preterm birth (PTB) can lead to lifelong complications and challenges. Identifying and monitoring molecular signals in easily accessible biological samples that can diagnose or predict the risk of preterm labour (PTL) in pregnant women will reduce or prevent PTBs. A number of studies identified putative biomarkers for PTL including protein, miRNA and hormones from various body fluids. However, biomarkers identified from these studies usually lack consistency and reproducibility. Extracellular vesicles (EVs) in circulation have gained significant interest in recent years as these vesicles may be involved in cell‐cell communication. We have used an improved small RNA library construction protocol and a newly developed size exclusion chromatography (SEC)‐based EV purification method to gain a comprehensive view of circulating RNA in plasma and its distribution by analysing RNAs in whole plasma and EV‐associated and EV‐depleted plasma. We identified a number of miRNAs in EVs that can be used as biomarkers for PTL, and these miRNAs may reflect the pathological changes of the placenta during the development of PTL. To our knowledge, this is the first study to report a comprehensive picture of circulating RNA, including RNA in whole plasma, EV and EV‐depleted plasma, in PTL and reveal the usefulness of EV‐associated RNAs in disease diagnosis.     

Floral Sonication is an Innate Behaviour in Bumblebees that can be Fine-Tuned with Experience in Manipulating Flowers

Bumblebees demonstrate an extensive capacity for learning complex motor skills to maximise exploitation of floral rewards. This ability is well studied in nectar collection but its role in pollen foraging is less well understood. Floral sonication is used by bees to extract pollen from some plant species with anthers which must be vibrated (buzzed) to release pollen. Pollen removal is determined by sonication characteristics including frequency and amplitude, and thus the ability to optimise sonication should allow bees to maximise the pollen collection. We investigated the ability of the buff-tailed bumblebee (Bombus terrestris) to modify the frequency and amplitude of their buzzes with increasing experience manipulating flowers of the buzz-pollinated plant Solanum rostratum. We analysed flight and feeding vibrations generated by naïve workers across feeding bouts. Feeding buzzes were of a higher frequency and a lower amplitude than flight buzzes. Both flight and feeding buzzes had reduced amplitudes with increasing number of foraging trips. However, the frequency of their feeding buzzes was reduced significantly more than their flight buzzes as bumblebee workers gained experience manipulating flowers. These results suggest that bumblebees are able to modify the characteristics of their buzzes with experience manipulating buzz-pollinated flowers. We discuss our findings in the context of bumblebee learning, and the current understanding of the optimal sonication characteristics for releasing pollen in buzz-pollinated species. Our results present a tantalising insight into the potential role of learning in floral sonication, paving the way for future research in this area.     

Identifying Adult Dengue Patients at Low Risk for Clinically Significant Bleeding

Background

Clinically significant bleeding is important for subsequent optimal case management in dengue patients, but most studies have focused on dengue severity as an outcome. Our study objective was to identify differences in admission parameters between patients who developed clinically significant bleeding and those that did not. We sought to develop a model for discriminating between these patients.

Methods

We conducted a retrospective study of 4,383 adults aged >18 years who were hospitalized with dengue infection at Tan Tock Seng Hospital, Singapore from 2005 to 2008. Patients were divided into those with clinically significant bleeding (n = 188), and those without (n = 4,195). Demographic, clinical, and laboratory variables on admission were compared between groups to determine factors associated with clinically significant bleeding during hospitalization.

Results

On admission, female gender (p<0.001); temperature >38°C (p<0.001); nausea/vomiting (p = 0.009) and abdominal pain/tenderness (p = 0.005); lower systolic blood pressure (p<0.001); higher pulse rate (p<0.001); increased absolute neutrophil count (ANC; p<0.001); reduced absolute lymphocyte count (ALC; p<0.001), haematocrit percentage (p<0.001) and platelet count (p = 0.04), and increased prothrombin time (p = 0.003) were significantly associated with clinically significant bleeding on univariate analysis. Multivariate analysis showed that independent variables in the final model were female gender (aOR 2.85; 95% CI: 1.9–4.33); temperature >38°C (aOR 1.81; 95% CI: 1.27–2.61), nausea/vomiting (aOR 1.39; 95% CI: 0.94–2.12), ANC (aOR 1.3; 95% CI: 1.15–1.46), ALC (aOR 0.4; 95% CI: 0.25–0.64), hematocrit percentage (aOR 0.96; 95% CI: 0.92–1.002) and platelet count (aOR 0.993; 95% CI: 0.988–0.998). At the cutoff of -3.919, the model achieved an AUC of 0.758 (sensitivity:0.87, specificity: 0.38, PPV: 0.06, NPV: 0.98).

Conclusion

Clinical risk factors associated with clinically significant bleeding were identified. This model may be useful to complement clinical judgement in triaging adult dengue patients given the dynamic nature of acute dengue, particularly in pre-identifying those less likely to develop clinically significant bleeding.     

Patterns of urine flow and electrolyte excretion in healthy elderly people.

Twenty four young (mean age 29.2 years, range 25-35) and 21 elderly (mean age 66.5, range 60-80) healthy subjects collected their urine in timed aliquots over 24 hours. The elderly subjects had been selected for their fitness by clinical and laboratory examinations and all lived independently at home. Sodium and potassium excretions were reduced in the elderly subjects compared with the young subjects, potassium excretion considerably so. This was despite similar 24 hour urine volumes and total solute excretion by both groups. The ratios of rates of excretion of water, electrolytes, and solutes during the night to the rates of excretion during the day were found to be higher in the elderly than the young subjects. Reduced day to night ratios of urinary excretion may be partly responsible for complaints of nocturia and sleep disturbance in elderly people.     

Studies in African Cyperaceae 28. New taxa and combinations in Abildgaardia Vahl IV

Eight new species of Abildgaardia subgen. Bulbostylis are described from tropical Africa, viz. Abildgaardia squarrosa, A. densiflora, A. acutespicata, A. angustespicata, A. lacunosa, A. microcephala, A. microrotundata and A. pluricephala .     

Comparison of leucine enkephalin and adrenocorticotrophin effects on adrenal function in fetal and adult sheep

At Day 120-125 of gestation equimolar amounts of ACTH and leu-enkephalin injected in vivo provoked similar rises in plasma cortisol concentrations in chronically catheterized fetuses. There was no concomitant change in plasma DHEA concentrations, or in maternal cortisol concentrations. At term (Days 135-140) 2 out of 5 animals responded similarly to both leu-enkephalin and ACTH injections with a rise in plasma cortisol concentrations, but the other 3 animals, in which basal cortisol concentrations had already risen, showed no response to either agonist. In adult sheep, ACTH provoked a significant increase in the plasma cortisol concentrations, but equimolar amounts of leu-enkephalin were without effect. There was a significant output of cortisol in response to ACTH administration by collagenase-dispersed adrenal cells from term sheep fetuses in vitro. Leu-enkephalin had no effect on cortisol output from dispersed adrenal cells when added by itself, or with ACTH. We conclude that leu-enkephalin is able to function as a stimulator of pituitary-adrenal function during fetal life. The lack of effect of leu-enkephalin on adrenal cells implies that its action is exerted not directly at the adrenal gland, but indirectly at the level of the hypothalamus or pituitary through stimulation of the release of other corticotrophic substances.     

The bioreduction of a β-tetralone to its corresponding alcohol by the yeast Trichosporon capitatum MY1890 and bacterium Rhodococcus erythropolis MA7213 in a range of ionic liquids

The stereospecific reduction of 6-Br-β-tetralone to its corresponding alcohol (S)-6-Br-β-tetralol was carried out by the yeast Trichosporon capitatum MY1890 and by the bacterium Rhodococcus erythropolis MA7213, using a range of ionic liquids chosen for the diversity of their composition. The decrease in cell viability of both types of cell upon exposure to ionic liquids was found to be between that determined for cells residing purely in fermentation media, and cells residing in a two-phase mixture of media and organic solvent (toluene). For T. capitatum MY1890 bioconversions, the water miscible hydrophilic ionic liquid [Emim][TOS] gave a reaction profile comparable to that observed in the previously studied water-ethanol (10% v/v) system, in terms of overall rate of reaction (0.2 g (prod) L^-1 h^-1) and conversion (100%). Of the hydrophobic ionic liquids evaluated, [Oc₃MeN][BTA] gave the best conversion of 60%, but at a much reduced rate, suggesting solute mass transfer from the ionic liquid phase was rate limiting. For bioconversions carried out with R. erythropolis MA7213 employing 20% v/v [Emim][TOS] as a co-solvent, the conversion yield doubled, and a four-fold increase in initial rate was found compared to the standard ethanol co-solvent. This was attributed to improved cell viability and reduced aggregation of the R. erythropolis MA7213 compared to T. capitatum MY1890. Overall, this study demonstrates the feasibility of using ionic liquids for whole cell biocatalysis, however, no obvious link is apparent between the physico-chemical properties of ionic liquids, their influence on cell viability, and their efficacy as media for bioconversions.     

Mechanical Coupling between Endoderm Invagination and Axis Extension in Drosophila

How genetic programs generate cell-intrinsic forces to shape embryos is actively studied, but less so how tissue-scale physical forces impact morphogenesis. Here we address the role of the latter during axis extension, using Drosophila germband extension (GBE) as a model. We found previously that cells elongate in the anteroposterior (AP) axis in the extending germband, suggesting that an extrinsic tensile force contributed to body axis extension. Here we further characterized the AP cell elongation patterns during GBE, by tracking cells and quantifying their apical cell deformation over time. AP cell elongation forms a gradient culminating at the posterior of the embryo, consistent with an AP-oriented tensile force propagating from there. To identify the morphogenetic movements that could be the source of this extrinsic force, we mapped gastrulation movements temporally using light sheet microscopy to image whole Drosophila embryos. We found that both mesoderm and endoderm invaginations are synchronous with the onset of GBE. The AP cell elongation gradient remains when mesoderm invagination is blocked but is abolished in the absence of endoderm invagination. This suggested that endoderm invagination is the source of the tensile force. We next looked for evidence of this force in a simplified system without polarized cell intercalation, in acellular embryos. Using Particle Image Velocimetry, we identify posteriorwards Myosin II flows towards the presumptive posterior endoderm, which still undergoes apical constriction in acellular embryos as in wildtype. We probed this posterior region using laser ablation and showed that tension is increased in the AP orientation, compared to dorsoventral orientation or to either orientations more anteriorly in the embryo. We propose that apical constriction leading to endoderm invagination is the source of the extrinsic force contributing to germband extension. This highlights the importance of physical interactions between tissues during morphogenesis.