Chlorine Inactivation of Bacterial Bioterrorism Agents

Seven species of bacterial select agents were tested for susceptibility to free available chlorine (FAC). Under test conditions, the FAC routinely maintained in potable water would be sufficient to reduce six species by 2 orders of magnitude within 10 min. Water contaminated with spores of Bacillus anthracis spores would require further treatment.     

PaleoView: a tool for generating continuous climate projections spanning the last 21 000 years at regional and global scales

It has been difficult to access projections of global‐scale climate change with high temporal resolution spaning the late Pleistocene and Holocene. This has limited our ability to discern how climate fluctuations have affected species’ range dynamics and extinction processes, turn‐over in ecological communities and changes in genetic diversity. PaleoView is a new freeware tool, which provides a comprehensive but easy‐to‐use way to generate and view paleoclimate data at temporal and spatial resolutions suitable for detecting biotic responses to major climate shifts since the last glacial maximum. Regional to global scale simulations of temperature, precipitation, humidity and mean sea level pressure can be generated from PaleoView as gridded or time series data at time intervals as short as a decade for any period during the last 21 000 yr. They can be viewed using a built‐in geographical user interface or saved as data files. Modelled climate reconstructions are based on daily simulation output from the Community Climate System Model ver. 3 (CCSM3). This global coupled atmosphere–ocean–sea ice–land general circulation model accurately reproduces major climatic features associated with the most recent deglaciation event, and predicts present‐day patterns of climate conditions with verified hindcast skill. By providing a portal for readily accessing climate reconstructions at high temporal resolutions, PaleoView can help to better establish the consequences of past climate fluctuations on macro‐ecological patterns of biological and genetic diversity.     

Do riparian forest strips in modified forest landscapes aid in conserving bat diversity?

Agricultural practices lead to losses of natural resources and biodiversity. Maintaining forests alongside streams (riparian forest strips) has been used as a mechanism to minimize the impact of clearing for agriculture on biodiversity. To test the contribution of riparian forest strips to conserve biodiversity in production landscapes, we selected bats as a biodiversity model system and examined two dimensions of diversity: taxonomic and functional. We compared bat diversity and composition in forest, with and without stream habitat, and in narrow forest riparian strips surrounded by areas cleared for agriculture. We tested the hypothesis that riparian forest strips provide potential conservation value by providing habitat and serving as movement corridors for forest bat species. Riparian forest strips maintained 75% of the bat species registered in forested habitats. We found assemblage in sites with riparian forest strips were dominated by a few species with high abundance and included several species with low abundance. Bat species assemblage was more similar between sites with streams than between those sites to forests without stream habitat. These results highlight the importance of stream habitat in predicting presence of bat species. We registered similar number of guilds between forest sites and riparian forest strips sites. Relative to matrix habitats, stream and edge habitats in riparian forest strips sites were functionally more diverse, supporting our hypothesis about the potential conservation value of riparian forest strips. Results from this study suggest that maintaining riparian forest strips within cleared areas for agricultural areas helps conserve the taxonomic and functional diversity of bats. Also, it provides basic data to evaluate the efficacy of maintaining these landscape features for mitigating impacts of agricultural development on biodiversity. However, we caution that riparian forest strips alone are not sufficient for biodiversity maintenance; their value depends on maintenance of larger forest areas in their vicinity.     

Asexual reproduction and genetic determination of growth form in the coral Pavona cactus: biochemical genetic and immunogenic evidence

Summary Tissue grafting and electrophoresis were used to study the genotypic structure of a population of the scleractinian coral, Pavona cactus. Three growth forms were distinguished within one continuous population of this morphologically variable species. Both techniques provided evidence of localized asexual reproduction within each growth form, a result consistent with numerous field observations of naturally occurring fragments. A perfect association between clonal genotype and growth form was found in an electrophoretic survey of 80 colonies. 23 multi-locus genotypes were detected in the 80 colonies tested. All genotypically similar colonies had the same growth form, even where colonies were separated by 50 m. Although environmental gradients undoubtedly modify colony morphology, the high correlation between genotype and growth form suggests that major differences in colony morphology are genetically determined.Tissue grafting tests did not reliably identify all clones. Fusions developed between all electrophoretically indistinguishable colonies, consistent with the initial assumption that fusion between paired colonies would indicate selfrecognition. However, there was also one fusion in 20 pairings of electrophoretically different colonies. Although there was general agreement between the two techniques, the one inconsistent fusion suggests that caution should be exercised in the application of histocompatibility tests as bioassays for clonal population structure, and that electrophoresis is the more appropriate technique for this species.The ability of genotypes to dominate in intraspecific competitive interactions and to survive fragmentation was assessed. An intraspecific dominance hierarchy was identified among the 6 clones tested. Competition was highly asymmetrical between dominant and subordinate-ranking clones. Genotypes that were most successful in producing widespread clones were found to dominate intraspecific competitive interactions and had high rates of fragment survival. Offprint requests to: D.J. Ayre Contribution No 252 from the Australian Institute of Marine Science     

Influence of O(3)/O(2)-pneumoperitoneum as an oxidative stressor on duration of anaesthesia, loss of different reflexes and cytokine mRNA expression

We analysed the effect of intraperitoneal insufflated ozonized oxygen on the anaesthetic strength generated by tribromoethanol, ketamine/xylazine, chloral hydrate, pentobarbital, and urethane in male Wistar rats. High dosages of anaesthetic drugs normally used for deep surgical anaesthesia were injected. The ozonized oxygen gas mixture was given five times daily on five consecutive days at 0.8 mg ozone/kg body weight before anaesthesia. The reflexes were measured 15, 30, 60, 90, 120, 180, and 240 min after injection of the anaesthetic drug. The sleeping time and the loss and regain of six different reflexes on noxious and non-aversive stimuli were recorded during the 4 h of observation. O(3)/O(2)-pneumoperitoneum (O(3)/O(2)-PP) reduced the sleeping time induced by tribromoethanol and ketamine/xylazine and increased it for chloral hydrate and pentobarbital. In accordance to the changes in the duration of anaesthesia, the O(3)/O(2)-PP induced significant changes in the loss of different reflexes. Additionally, the modulatory effect of the anaesthetic drugs on splenic cytokine mRNA expression was further influenced by O(3)/O(2)-PP. Thus, the influence of an oxidative stressor on anaesthetic potency and on the resting immune system has to be taken into account for experimental designs in which surgical anaesthesia is necessary for small laboratory animals.     

Multicellular computer simulation of morphogenesis: blastocoel roof thinning and matrix assembly in Xenopus laevis

In the blastocoel roof (BCR) of the Xenopus laevis embryo, epibolic movements are driven by the radial intercalation of deep cell layers and the coordinate spreading of the overlying superficial cell layer. Thinning of the lateral margins of the BCR by radial intercalation requires fibronectin (FN), which is produced and assembled into fibrils by the inner deep cell layer of the BCR. A cellular automata (CA) computer model was developed to analyze the spatial and temporal movements of BCR cells during epiboly. Simulation parameters were defined based on published data and independent results detailing initial tissue geometry, cell numbers, cell intercalation rates, and migration rates. Hypotheses regarding differential cell adhesion and FN assembly were also considered in setting system parameters. A 2-dimensional model simulation was developed that predicts BCR thinning time of 4.8 h, which closely approximates the time required for the completion of gastrulation in vivo. Additionally, the model predicts a temporal increase in FN matrix assembly that parallels fibrillogenesis in the embryo. The model is capable of independent predictions of cell rearrangements during epiboly, and here was used to predict successfully the lateral dispersion of a patch of cells implanted in the BCR, and increased assembly of FN matrix following inhibition of radial intercalation by N-cadherin over-expression.     

Estimating time since infection in early homogeneous HIV-1 samples using a poisson model

Background  

The occurrence of a genetic bottleneck in HIV sexual or mother-to-infant transmission has been well documented. This results in a majority of new infections being homogeneous, i.e., initiated by a single genetic strain. Early after infection, prior to the onset of the host immune response, the viral population grows exponentially. In this simple setting, an approach for estimating evolutionary and demographic parameters based on comparison of diversity measures is a feasible alternative to the existing Bayesian methods (e.g., BEAST), which are instead based on the simulation of genealogies.