Influence of <Emphasis Type="Italic">Daphnia</Emphasis> infochemicals on functional traits of <Emphasis Type="Italic">Microcystis</Emphasis> strains (Cyanobacteria)

We conducted a laboratory experiment to investigate the influence of Daphnia infochemicals on growth rate, microcystin production, colony formation and cell size of eight Microcystis strains isolated from two lakes. The strains were characterized genetically by their 16S-23S rDNA ITS sequence. The experiment was composed of four treatments: (1) a control using filtered WC medium, (2) addition of Scenedesmus obliquus culture medium filtrate, (3) addition of Daphnia magna culture medium filtrate and (4) addition of sodium octyl sulphate, a commercially available Daphnia infochemical. Our results showed that sympatric strains differed strongly for the measured functional traits, while no correlations between traits were found. Between-strain differences in growth rate, microcystin production, colony formation and cell size were generally larger than the differences in phenotypes observed between treatments. Despite this, several strains reacted to the infochemicals by changing functional trait values. Daphnia culture medium filtrate and, to a lesser extent, sodium octyl sulphate had a negative influence on the growth rate of half of the strains and stimulated microcystin production in one strain, but the latter effect was not Daphnia-specific as Scenedesmus culture medium filtrate had the same effect. Daphnia culture medium filtrate also induced colony formation in one strain. Our data suggest that Daphnia infochemicals generally have a weak influence on growth rate, microcystin production and colony formation of Microcystis strains as compared to the inter-strain variability, while existing inducible effects are highly strain-specific.     

Effects of ice cover on the behavioural patterns of aquatic-mating male bearded seals

We used vocalizations to examine the behaviour of male bearded seals, Erignathus barbatus, in relation to ice cover over 2 consecutive years. Site fidelity varied between males. Territorial males returned to the same display locations in successive years, whereas roaming males returned to the study area but not to specific display locations. Males did not vocalize under the land-fast-ice edge and were therefore limited by access to areas of drift ice and open water for the purpose of displaying. Between-year fluctuations in ice cover restricted the number of displaying males during the early part of the mating season in April. Decreased ice cover during May resulted in more males displaying, but the number of males declined in June irrespective of the continued decline in ice cover. Roaming males were not heard when the ice cover was more than 60%, whereas territorial males were present during all ice conditions. Yearly fluctuations in ice cover may alter the long-term mating success of individuals and predictably available display areas may be preferred to areas that are more likely to be enclosed by fast-ice in some years.     

Small G proteins in peroxisome biogenesis: the potential involvement of ADP-ribosylation factor 6

Background  

Peroxisomes execute diverse and vital functions in virtually every eukaryote. New peroxisomes form by budding from pre-existing organelles or de novo by vesiculation of the ER. It has been suggested that ADP-ribosylation factors and COPI coatomer complexes are involved in these processes.     

From the Waters of the Empire to the Tanks of Paris: The Creation and Early Years of the Aquarium Tropical,Palais de la Porte Dorée

From May to November 1931, the Exposition coloniale internationale was held in Paris. Publicized as a trip around the world in a single day, it was designed to stimulate investments and general enthusiasm for the colonies. Along with exotic temporary pavilions representing the various colonies, model villages inhabited by colonial natives, and pavilions representing commercial product brands and other colonial powers, the exposition included a zoo and an aquarium featuring animals from the colonies. Installing a large aquarium had been a costly and difficult process, and construction was plagued by many delays and problems. But when the aquarium finally opened a few months into the exposition, it quickly became a favorite of the public. With the double mission to provide a living synthesis of the products of the warm waters of the French empire and give visitors a sense of the diversity, beauty, and economic resources of their colonial possessions, the aquarium functioned as a panorama that presented a striking visual metaphor for the empire. This article follows the aquarium during the exposition and in the years that followed. We explore its place in the history of aquaria in general and pay particular attention to its role in the exposition and within the French colonial context of the 1930s and onward. Here, both the scientists in charge of the site and the aquatic animals living in its tanks and terrariums provide a window into the relationship of marine biology, public education, consumerism, and colonialism at mid-twentieth century.     

Sleep deprivation sensitizes human craniofacial muscles

It is unknown whether and how sleep deprivation influences craniofacial muscle sensitivity in healthy humans. We investigated whether total sleep deprivation (TSD) and one night of recovery sleep (RS) can alter mechanical pain sensitivity in temporal and masseter muscles. Fifteen healthy volunteers participated in three consecutive sessions. Pressure pain thresholds were measured on the temporal and masseter muscles. Both temporal and masseter muscles became sensitized after 24?h of TSD. RS reversed the muscle sensitization.