Parallelism and convergence in anuran fangs

The anuran lower jaw is composed of three pairs of bones: dentaries, angulosplenials and mentomeckelians. Although the lower jaw is toothless, except in Gastrotheca guentheri , enlarged fangs or odontoids have evolved at least four times independently in some myobatrachids, hylids, ranids and leptodactylids through both parallel and convergent evolutionary events. Fangs seem to represent the single best design solution to enable an anuran to inflict a bite-like wound, but the biological role of biting varies among species. Fangs are projections of the dentaries in ranids, but in the hylid frog Hemiphractus and in ceratophryine leptodactylids, they form a sinosteotic unit with the dentaries and mentomeckelians. Comparisons of morphology, behaviour and diet among frog taxa with enlarged fangs reveal that the fangs may be the result of either sexual or natural selection. Those fangs that evolved in response to sexual selection seem to be relatively larger than those that resulted of natural selection.     

MANOMETRIC MEASUREMENTS OF PHOTOSYNTHESIS IN THE MARINE ALGA GIGARTINA

A manometric method for measuring photosynthesis in marine algae is described. Photosynthesis in the red alga Gigartina harveyana is shown to be similar in all important respects to photosynthesis in Chlorella and other Chlorophyceae.     

Patient-reported benefits from the pre-sleep routine approach to treating insomnia: Findings from a treatment development trial

Sleep and Biological Rhythms - This uncontrolled trial evaluated the feasibility, acceptability, and initial changes in sleep associated with a novel cognitive-behavioral treatment for insomnia,...     

Pseudomonas aeruginosa Type III secretion system interacts with phagocytes to modulate systemic infection of zebrafish embryos

Pseudomonas aeruginosa is an opportunistic human pathogen that can cause serious infection in those with deficient or impaired phagocytes. We have developed the optically transparent and genetically tractable zebrafish embryo as a model for systemic P. aeruginosa infection. Despite lacking adaptive immunity at this developmental stage, zebrafish embryos were highly resistant to P. aeruginosa infection, but as in humans, phagocyte depletion dramatically increased their susceptibility. The virulence of an attenuated P. aeruginosa strain lacking a functional Type III secretion system was restored upon phagocyte depletion, suggesting that this system influences virulence through its effects on phagocytes. Intravital imaging revealed bacterial interactions with multiple blood cell types. Neutrophils and macrophages rapidly phagocytosed and killed P. aeruginosa , suggesting that both cell types play a role in protection against infection. Intravascular aggregation of erythrocytes and other blood cells with resultant circulatory blockage was observed immediately upon infection, which may be relevant to the pathogenesis of thrombotic complications of human P. aeruginosa infections. The real-time visualization capabilities and genetic tractability of the zebrafish infection model should enable elucidation of molecular and cellular details of P. aeruginosa pathogenesis in conditions associated with neutropenia or impaired phagocyte function.     

Metagenomic and lipid analyses reveal a diel cycle in a hypersaline microbial ecosystem

Marine microbial communities experience daily fluctuations in light and temperature that can have important ramifications for carbon and nutrient cycling. Elucidation of such short time scale community-wide dynamics is hindered by system complexity. Hypersaline aquatic environments have lower species richness than marine environments and can be well-defined spatially, hence they provide a model system for diel cycle analysis. We conducted a 3-day time series experiment in a well-defined pool in hypersaline Lake Tyrrell, Australia. Microbial communities were tracked by combining cultivation-independent lipidomic, metagenomic and microscopy methods. The ratio of total bacterial to archaeal core lipids in the planktonic community increased by up to 58% during daylight hours and decreased by up to 32% overnight. However, total organism abundances remained relatively consistent over 3 days. Metagenomic analysis of the planktonic community composition, resolved at the genome level, showed dominance by Haloquadratum species and six uncultured members of the Halobacteriaceae. The post 0.8 μm filtrate contained six different nanohaloarchaeal types, three of which have not been identified previously, and cryo-transmission electron microscopy imaging confirmed the presence of small cells. Notably, these nano-sized archaea showed a strong diel cycle, with a pronounced increase in relative abundance over the night periods. We detected no eukaryotic algae or other photosynthetic primary producers, suggesting that carbon resources may derive from patchily distributed microbial mats at the sediment-water interface or from surrounding land. Results show the operation of a strong community-level diel cycle, probably driven by interconnected temperature, light abundance, dissolved oxygen concentration and nutrient flux effects.