A new micronucleus test using peripheral blood erythrocytes of the newt Pleurodeles waltl to detect mutagens in fresh-water pollution

A model micronucleus test system using peripheral blood erythrocytes from larvae of Pleurodeles waltl is described. The most suitable larval stage for testing chemical treatments was determined. Larvae were reared in water containing one of the 4 compounds: benzo[a]pyrene (BaP), ethyl methanesulphonate (EMS), diethyl sulphate (DES) and N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). Response curves as a function of treatment duration over a period of 16 days were plotted for 3 different concentrations of the 4 compounds in order to optimize conditions for a low dose micronucleus test. This model can be used as a monitoring system for the detection of fresh water pollution and can also be employed for clastogen screening of chemical compounds. The test is sensitive, reliable and easy to use.     

Spatiotemporal Evolution of Ebola Virus Disease at Sub-National Level during the 2014 West Africa Epidemic: Model Scrutiny and Data Meagreness

Background

The Ebola outbreak in West Africa has infected at least 27,443 individuals and killed 11,207, based on data until 24 June, 2015, released by the World Health Organization (WHO). This outbreak has been characterised by extensive geographic spread across the affected countries Guinea, Liberia and Sierra Leone, and by localized hotspots within these countries. The rapid recognition and quantitative assessment of localised areas of higher transmission can inform the optimal deployment of public health resources.

Methods

A variety of mathematical models have been used to estimate the evolution of this epidemic, and some have pointed out the importance of the spatial heterogeneity apparent from incidence maps. However, little is known about the district-level transmission. Given that many response decisions are taken at sub-national level, the current study aimed to investigate the spatial heterogeneity by using a different modelling framework, built on publicly available data at district level. Furthermore, we assessed whether this model could quantify the effect of intervention measures and provide predictions at a local level to guide public health action. We used a two-stage modelling approach: a) a flexible spatiotemporal growth model across all affected districts and b) a deterministic SEIR compartmental model per district whenever deemed appropriate.

Findings

Our estimates show substantial differences in the evolution of the outbreak in the various regions of Guinea, Liberia and Sierra Leone, illustrating the importance of monitoring the outbreak at district level. We also provide an estimate of the time-dependent district-specific effective reproduction number, as a quantitative measure to compare transmission between different districts and give input for informed decisions on control measures and resource allocation. Prediction and assessing the impact of control measures proved to be difficult without more accurate data. In conclusion, this study provides us a useful tool at district level for public health, and illustrates the importance of collecting and sharing data.     

Neutrophil extracellular trap cell death requires both autophagy and superoxide generation

Neutrophil extracellular traps (NETs) are extracellular chromatin structures that can trap and degrade microbes. They arise from neutrophils that have activated a cell death program called NET cell death, or NETosis. Activation of NETosis has been shown to involve NADPH oxidase activity, disintegration of the nuclear envelope and most granule membranes, decondensation of nuclear chromatin and formation of NETs. We report that in phorbol myristate acetate (PMA)-stimulated neutrophils, intracellular chromatin decondensation and NET formation follow autophagy and superoxide production, both of which are required to mediate PMA-induced NETosis and occur independently of each other. Neutrophils from patients with chronic granulomatous disease, which lack NADPH oxidase activity, still exhibit PMA-induced autophagy. Conversely, PMA-induced NADPH oxidase activity is not affected by pharmacological inhibition of autophagy. Interestingly, inhibition of either autophagy or NADPH oxidase prevents intracellular chromatin decondensation, which is essential for NETosis and NET formation, and results in cell death characterized by hallmarks of apoptosis. These results indicate that apoptosis might function as a backup program for NETosis when autophagy or NADPH oxidase activity is prevented.     

Globin gene expression in erythroid cell lines during larval development of Pleurodeles waltlii

We have attempted to determine whether in Pleurodeles ontogenesis there exists a close relationship between the two following characteristics: change from primitive to definitive erythroid cell populations, which parallels the change of major erythropoietic site; change in the type of synthesized hemoglobin, larval or adult. The origin of red blood cells was investigated by embryonic grafts of hemopoietic anlage from 2n to 4n embryos. The larval or adult hemoglobin type was characterized by immunofluorescence by using specific antibodies. Our results show that in Pleurodeles, blood island-originating red blood cells and spleen-originating red blood cells are both able to synthesize either Hb L or Hb A at a given time, but in separate cells.     

Use of flow cytometry to monitor infection and recombinant human alpha-1,3/4 fucosyltransferase production in baculovirus infected Sf9 cell cultures

This paper describes the setup and the use of a flow cytometric method for monitoring Sf9 insect cell infection by a recombinant baculovirus expressing the human alpha1,3/4 fucosyltransferase Fuc-TIII. Using side scattered light coupled to green fluorescence detection after immunolabeling of the recombinant protein, this method made it possible to monitor baculovirus infection of Sf9 cells grown in batch cultures and infected at different cell densities and multiplicities of infection. The method was able to precisely assess the extent of infection of the insect cells from 60 h postinfection. In asynchronously infected Sf9 cell cultures, the two-step infection process (primary and secondary infection) was well-characterized using this technique. Finally, a reduced sensitivity to baculovirus infection was observed for cells infected at the end of the growth phase compared to the cells infected during exponential growth phase.     

Dictyota cyanoloma (Dictyotales,Phaeophyceae), a Newly Introduced Brown Algal Species in California

Here, we report for the first time the presence of Dictyota cyanoloma in southern California. Dictyota cyanoloma is conspicuous in harbors and bays by its distinctive bright blue‐iridescent margins. This species was originally described from Europe, but subsequent studies have revealed that it represented an introduction from Australia. The current distribution of D. cyanoloma comprises southern Australia and the North East Atlantic, including the Mediterranean Sea and the Macaronesian islands. The presence of D. cyanoloma in southern California is supported by molecular cox1 and psbA gene sequences. A reconstruction of the invasive history based on nine polymorphic microsatellite markers reveals a close affinity of the Californian specimens with European populations. Dictyota cyanoloma in the United States appears to be (so far) restricted to the Californian coast from San Diego Bay in the south to Santa Catalina Island and Long Beach Harbor in the north. A correlative species distribution model suggests gradually declining habitat suitability north of the Southern Californian Bight and high suitability in Baja California, including the Gulf of California. Finally, its widespread abundance in bays and harbors suggests shipping is a likely transport mechanism.     

A statistical learning approach to the modeling of chromatographic retention of oligonucleotides incorporating sequence and secondary structure data

We propose a new model for predicting the retention time of oligonucleotides. The model is based on ν support vector regression using features derived from base sequence and predicted secondary structure of oligonucleotides. Because of the secondary structure information, the model is applicable even at relatively low temperatures where the secondary structure is not suppressed by thermal denaturing. This makes the prediction of oligonucleotide retention time for arbitrary temperatures possible, provided that the target temperature lies within the temperature range of the training data.

We describe different possibilities of feature calculation from base sequence and secondary structure, present the results and compare our model to existing models.

     

The effect of index selection on allele frequencies and future genetic gains when traits are correlated

The application of the selection index in the case of an additive two-trait model in which the genetic effect on each trait is determined by a finite number of loci is examined. Simulation results indicate that the direction of change in the frequency of favourable alleles is not necessarily in the positive direction at all loci when index selection is used as the basis for truncation selection. When the genetic correlation was positive (or favourable with respect to the economic weights), there was little difference (<5%) in genetic gain over 20 generations and no difference in the direction of change in allele frequencies or genetic correlation whether or not updated values for the genetic (co)variances were used in constructing the selection index. However, when the genetic correlation was negative or unfavourable, the effect of using genetic parameters which were not updated had unexpected effects on the allele frequencies and genetic correlation and reduced the genetic gain by a greater amount (< 12%).