Genome sequence of temperate bacteriophage Psymv2 from Antarctic Dry Valley soil isolate Psychrobacter sp. MV2

A temperate phage, Psymv2, was isolated from an Antarctic soil bacterium, Psychrobacter sp. MV2. The morphology of Psymv2 was typical of the Siphoviridae, with an isometric head and non-contractile tail. The Psymv2 genome was found to be 35,725?bp in length, had a G?+?C content of 44.5?%, with 49 protein-coding genes and one tRNA gene predicted. Integration of Psymv2 occurred at an ssrA gene, with the last 27 bases of this gene directly repeated at the prophage ends. The genome was organised in a modular fashion: integration, regulation, packaging, head assembly, tail assembly, host specificity and lysis. While the genome sequence had little similarity on a nucleotide level to previously reported phage sequences, the genome architecture resembled that of Siphoviridae of low G?+?C Gram-positive bacteria. The closest relatives to Psymv2 were uncharacterized putative prophages within the P. arcticus 273-4 and Acinetobacter baumannii 6013113 genomes. Global alignment of the Psymv2 genome and these prophages revealed significant conservation of the structural modules despite the large spatial divergence of their hosts. A number of unique ORFs were identified in the Psymv2 genome that may contribute to phage and lysogen fitness.     

Sterols of the Toxic Marine Dinoflagellate,Pyrodinium bahamense

Pyrodinium bahamense is a dinoflagellate of concern in subtropical and tropical coastal environments. To date, there is only a single published study on its fatty acids, but no published data on its sterol composition. Sterols, which are membrane‐reinforcing lipids in eukaryotes, display a great diversity of structures in dinoflagellates, with some serving as chemotaxonomic markers. We have examined the sterol compositions of two isolates of P. bahamense from Indian River Lagoon and Tampa Bay, Florida, and have found both to produce three sterols: cholesterol, dinosterol, and 4α‐methylgorgostanol. All three sterols are found in closely related, armored taxa.     

More long‐unburnt forest will benefit mammals in Australian sub‐alpine forests and woodlands

The composition of mammalian communities in Australia's Eucalyptus forests and woodlands is known to be affected by fire. However, there are few published studies that compare mammal assemblages in recently burnt and long‐unburnt forests because there are few areas with long‐term fire history data. Understanding the value of long‐unburnt forest is important because it is becoming rare in fire‐prone regions of the world, such as south‐eastern Australia, partly because of the widespread use of prescribed burning. We deployed wildlife cameras for 28 trap‐nights at each of 81 sites that ranged from 0.5 to at least 96 years since the last fire. We recorded a total of 15 native mammal species. At least one mammal species was recorded at 80 of the 81 sites. Significantly more species were detected at long‐unburnt sites (>96 years since fire) than sites 0.5–12 years since the last fire. Species composition varied significantly between sites 0.5–12 years and >96 years since the last fire but did not vary between sites 0.5–2 years and 6–12 years since the last fire. Although there was not one category of time since fire (i.e. 0.5–2 years, 6–12 years and >96 years) in which all 15 native mammal species were recorded, long‐unburnt sites were significantly more important for the occurrence of seven mammal species; intermediate and recently burnt sites were significantly more important for one species. Our results suggested that, while a diversity of fire ages is important for conserving mammalian diversity, long‐unburnt forests and woodlands (which comprised only 8% of our study area) are disproportionately important for mammal conservation. Our results add to a growing body of the literature from south‐eastern Australia, suggesting that remaining long‐unburnt forest should be afforded protection from fire and more forest should be transitioned to long unburnt.     

An environmental 1H NMR metabolomic study of the exposure of the marine mussel Mytilus edulis to atrazine, lindane, hypoxia and starvation

Marine mussels are useful, robust model organisms that have been widely used as biomonitors. In the natural environment they can be subjected simultaneously to a mixture of environmental stresses (hypoxia, starvation) and to pollutants. In this study Mytilus edulis was used to investigate the effects of two pesticides, atrazine and lindane, which have different modes of action but produce similar changes in behaviour (depression of ventilation and feeding) in the mussels, and can cause starvation and mild hypoxia. Acetonitrile/²H₂O (60/40% v/v) extracts of foot muscle from animals subjected to hypoxia, or starvation, or low or high doses of pesticide were analysed using ¹H NMR spectroscopy to produce metabolic fingerprints associated with these treatments. Discriminant analysis based on metabolites that showed significant differences between treated and control animals gave a clear separation between all treatment groups. The fingerprints of atrazine treated animals were clearly separated from those of animals that were starved or subjected to hypoxia. The high and low doses of atrazine were also well separated. Lindane treatment was separated from control animals in a dose dependent way, and was associated with an increase in the concentration of alanine, and a decrease in all of the other identified metabolites (including osmolytes). This is consistent with a general depression of activity. This limited study demonstrates the potential of the metabolomic approach to provide a separation of the effects of poisoning from those of environmental stress. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Neural Mechanisms Associated With Food Motivation in Obese and Healthy Weight Adults

One out of three adults in the United States is clinically obese. Excess food intake is associated with food motivation, which has been found to be higher in obese compared to healthy weight (HW) individuals. Little is known, however, regarding the neural mechanisms associated with food motivation in obese compared to HW adults. The current study used functional magnetic resonance imaging (fMRI) to examine changes in the hemodynamic response in obese and HW adults while they viewed food and nonfood images in premeal and postmeal states. During the premeal condition, obese participants showed increased activation, compared to HW participants, in anterior cingulate cortex (ACC) and medial prefrontal cortex (MPFC). Moreover, in the obese group, self‐report measures of disinhibition were negatively correlated with premeal ACC activations and self‐report measures of hunger were positively correlated with premeal MPFC activations. During the postmeal condition, obese participants also showed greater activation than HW participants in the MPFC. These results indicate that brain function associated with food motivation differs in obese and HW adults and may have implications for understanding brain mechanisms contributing to overeating and obesity, and variability in response to diet interventions.     

Quantitative modeling of viable cell density,cell size,intracellular conductivity,and membrane capacitance in batch and fed‐batch CHO processes using dielectric spectroscopy

Dielectric spectroscopy was used to analyze typical batch and fed‐batch CHO cell culture processes. Three methods of analysis (linear modeling, Cole–Cole modeling, and partial least squares regression), were used to correlate the spectroscopic data with routine biomass measurements [viable packed cell volume, viable cell concentration (VCC), cell size, and oxygen uptake rate (OUR)]. All three models predicted offline biomass measurements accurately during the growth phase of the cultures. However, during the stationary and decline phases of the cultures, the models decreased in accuracy to varying degrees. Offline cell radius measurements were unsuccessfully used to correct for the deviations from the linear model, indicating that physiological changes affecting permittivity were occurring. The β‐dispersion was analyzed using the Cole–Cole distribution parameters Δε (magnitude of the permittivity drop), f_c (critical frequency), and α (Cole–Cole parameter). Furthermore, the dielectric parameters static internal conductivity (σ_i) and membrane capacitance per area (C_m) were calculated for the cultures. Finally, the relationship between permittivity, OUR, and VCC was examined, demonstrating how the definition of viability is critical when analyzing biomass online. The results indicate that the common assumptions of constant size and dielectric properties used in dielectric analysis are not always valid during later phases of cell culture processes. The findings also demonstrate that dielectric spectroscopy, while not a substitute for VCC, is a complementary measurement of viable biomass, providing useful auxiliary information about the physiological state of a culture. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

Proteomic identification of desmoglein 2 and activated leukocyte cell adhesion molecule as substrates of ADAM17 and ADAM10 by difference gel electrophoresis

In contrast with the early view of metalloproteases as simple extracellular matrix-degrading entities, recent findings show that they are highly specific modulators of different signaling pathways involved, positively or negatively, in tumor development. Thus, before considering a given metalloprotease a therapeutic target, it seems advisable to characterize its function by identifying its repertoire of substrates. Here, we present a proteomic approach to identify ADAM17 substrates by difference gel electrophoresis. We found that the shedding of the extracellular domain of the transferrin receptor and those of two cell-cell adhesion molecules, activated leukocyte cell adhesion molecule (ALCAM) and desmoglein 2 (Dsg-2), is increased in cells overexpressing ADAM17. Genetic evidence shows that while ADAM17 is responsible for the shedding of ALCAM, both ADAM17 and ADAM10 can act on Dsg-2. Activation of the epidermal growth factor receptor leads to the upregulation of the shedding of Dsg-2 and to the concomitant upregulation of ADAM17, but not ADAM10, supporting the ability of overexpressed ADAM17 to shed Dsg-2. These results unveil a role of ADAM10 and ADAM17 in the shedding of cell-cell adhesion molecules. Since loss of cell adhesion is an early event in tumor development, these results suggest that ADAM17 is a useful target in anticancer therapy.     

Growth in length of Mytilus edulis L. fed on different algal diets

Mytilus edulis L. was fed on different algal diets and the increase in shell length was measured every 12–24 h. The mussels respond within 12 h to major changes in the diet. When pre-starved mussels were fed every 24 h with monocultures of Tetraselmis suecica (Kylin) Butch, there was a pronounced lag period followed by a linear increase in shell growth rate. When both pre-starved and pre-fed mussels were fed on equal rations of T. suecica with concentrations ranging from 2.5 to 10.0 × 10⁷ cells · 1^?1, the growth rate levelled off at about the same rate. Within the same range of concentrations there was a linear correlation between final growth rates and algal cell concentration. Feeding with monocultures of Isochrysis galbana (Parke) or Thalassiosira pseudonana Hasle et Heimdal (Hustedt) gave approximately the same shell growth as with Tetraselmis suecica alone, while combinations of these three algal species produced significant synergistic effects. When filtrate only from T. suecica cultures was supplied to the mussels there was a rapid initial stimulation of the shell growth. Centrifugated cells of T. suecica which were resuspended in filtered sea water, homogenized and sonicated to rupture the cells, gave 13% less growth than with untreated cells (P < 0.05). The use of the accurate laser diffraction method for length growth measurements may greatly reduce the time and effort involved in growth experiments.