Extreme tolerance to environmental stress of sexual and parthenogenetic resting eggs of Eucypris virens (Crustacea,Ostracoda)

1. The freshwater ostracod (Ostracoda), Eucypris virens, is commonly found in European temporary pools, where its long‐term persistence completely relies on the build‐up of resting egg banks. Extreme tolerance of dormant eggs and seeds is widely assumed, but freshwater ostracod eggs are relatively poorly studied. The study of ostracod resting eggs is of particular relevance as it may yield the key to understanding the distribution of the sexes in many species capable of both sexual and asexual reproduction. 2. We assessed the tolerance of dried resting eggs produced by females originating from three populations with males and three all‐female E. virens populations. Hatching time and success was compared between control eggs and eggs exposed to one of seven ecologically relevant stressors: digestive enzymes, high salinity, deep freezing, hydration, UV‐B radiation, hypoxia and insecticide treatment. 3. None of the stressors reduced significantly the viability of either sexual or asexual eggs. When compared with the reproductive mode–specific controls, exposure to UV‐B radiation had a mild impact on the survival of sexual and asexual eggs (?16.8 and ?22.4%, respectively), but this was only significant for asexual eggs. These results point to an extreme tolerance of E. virens resting eggs and have important implications for the ecology and evolution of the species. 4. The timing of hatching was not affected by the stress treatment, except for UV‐B radiation. A marginally significant delay in hatching response was observed for UV‐B‐radiated eggs when compared to the overall mean, but this treatment effect was absent when compared with the reproductive mode–specific controls. 5. The populations with males produced eggs that hatched on average earlier (?1.5 days at 17 °C) and were more successful (+26%) than asexual eggs. Due to the limited number of populations and the population‐specific origin and age of the eggs, the possibility due to the differences in age and origin of the resting eggs, or to variations in local conditions, cannot be ruled out.     

Relative roles of dispersal dynamics and competition in determining the isotopic niche breadth of a wetland fish

1. The niche variation hypothesis predicts that among‐individual variation in niche use will increase in the presence of intraspecific competition and decrease in the presence of interspecific competition. We sought to determine whether the local isotopic niche breadth of fish inhabiting a wetland was best explained by competition for resources and the niche variation hypothesis, by dispersal of individuals from locations with different prey resources or by a combination of the two. We analysed stable isotopes of carbon and nitrogen as indices of feeding niche and compared metrics of within‐site spread to characterise site‐level isotopic niche breadth. We then evaluated the explanatory power of competing models of the direct and indirect effects of several environmental variables spanning gradients of disturbance, competition strength and food availability on among‐individual variation of the eastern mosquitofish (Gambusia holbrooki). 2. The Dispersal model posits that only the direct effect of disturbance (i.e. changes in water level known to induce fish movement) influences among‐individual variation in isotopic niche. The Partitioning model allows for only direct effects of local food availability on among‐individual variation. The Combined model allows for both hypotheses by including the direct effects of disturbance and food availability. 3. A linear regression of the Combined model described more variance than models limited to the variables of either the Dispersal or Partitioning models. Of the independent variables considered, the food availability variable (per cent edible periphyton) explained the most variation in isotopic niche breadth, followed closely by the disturbance variable (days since last drying event). 4. Structural equation modelling provided further evidence that the Combined model was best supported by the data, with the Partitioning and the Dispersal models only modestly less informative. Again, the per cent edible periphyton was the variable with the largest direct effect on niche variability, with other food availability variables and the disturbance variable only slightly less important. Indirect effects of heterospecific and conspecific competitor densities were also important, through their effects on prey density. 5. Our results support the Combined hypotheses, although partitioning mechanisms appear to explain the most diet variation among individuals in the eastern mosquitofish. The results also support some predictions of the niche variation hypothesis, although both conspecific and interspecific competition appeared to increase isotopic niche breadth in contrast to predictions that interspecific competition would decrease it. We think this resulted from high diet overlap of co‐occurring species, most of which consume similar macroinvertebrates.     

Sequence polymorphisms in Pvs48/45 and Pvs47 gametocyte and gamete surface proteins in Plasmodium vivax isolated in Korea

Nucleotide sequence analyses of the Pvs48/45 and Pvs47 genes were conducted in 46 malaria patients from the Republic of Korea (ROK) (n = 40) and returning travellers from India (n = 3) and Indonesia (n = 3). The domain structures, which were based on cysteine residue position and secondary protein structure, were similar between Plasmodium vivax (Pvs48/45 and Pvs47) and Plasmodium falciparum (Pfs48/45 and Pfs47). In comparison to the Sal-1 reference strain (Pvs48/45, PVX_083235 and Pvs47, PVX_083240), Korean isolates revealed seven polymorphisms (E35K, H211N, K250N, D335Y, A376T, I380T and K418R) in Pvs48/45. These isolates could be divided into five haplotypes with the two major types having frequencies of 47.5% and 20%, respectivelfy. In Pvs47, 10 polymorphisms (F22L, F24L, K27E, D31N, V230I, M233I, E240D, I262T, I273M and A373V) were found and they could be divided into four haplotypes with one major type having a frequency of 75%. The Pvs48/45 isolates from India showed a unique amino acid substitution site (K26R). Compared to the Sal-1 and ROK isolates, the Pvs47 isolates from travellers returning from India and Indonesia had amino acid substitutions (S57T and I262K). The current data may contribute to the development of the malaria transmission-blocking vaccine in future clinical trials.     

French marine policy in the 1970s and 1980s

Abstract

France, hitherto more “continental”; than “maritime,”; increasingly developed its ocean activities in the 1970s and 1980s. This article describes the different sectors of its marine activities and evolvement of a different outlook concerning the sea. Important events such as the 1976 Proclamation and subsequent implementation of the French 200‐nautical mile Exclusive Economic Zone, and 1981 formation of a new Socialist government in France after 23 years of uninterrupted “Gaullist”; rule, offered a unique opportunity to restructure marine policy. The new Ministry of the Sea was intended to integrate marine policy and cater to a developing ocean “constituency.”; It was eventually downgraded to a “Secrétariat d'Etat,”; but its impact was undeniably important.     

Modelling a Wolbachia Invasion Using a Slow–Fast Dispersal Reaction–Diffusion Approach

This paper uses a reaction–diffusion approach to examine the dynamics in the spread of a Wolbachia infection within a population of mosquitoes in a homogeneous environment. The formulated model builds upon an earlier model by Skalski and Gilliam (Am. Nat. 161(3):441–458, 2003), which incorporates a slow and fast dispersal mode. This generates a faster wavespeed than previous reaction–diffusion approaches, which have been found to produce wavespeeds that are unrealistically slow when compared with direct observations. In addition, the model incorporates cytoplasmic incompatibility between male and female mosquitoes, which creates a strong Allee effect in the dynamics. In previous studies, linearised wavespeeds have been found to be inaccurate when a strong Allee effect is underpinning the dynamics. We provide a means to approximate the wavespeed generated by the model and show that it is in close agreement with numerical simulations. Wavespeeds are approximated for both Aedes aegypti and Drosophila simulans mosquitoes at different temperatures. These wavespeeds indicate that as the temperature decreases within the optimal temperature range for mosquito survival, the speed of a Wolbachia invasion increases for Aedes aegypti populations and decreases for Drosophila simulans populations.     

Engineered Escherichia coli with Periplasmic Carbonic Anhydrase as a Biocatalyst for CO2 Sequestration

Carbonic anhydrase is an enzyme that reversibly catalyzes the hydration of carbon dioxide (CO₂). It has been suggested recently that this remarkably fast enzyme can be used for sequestration of CO₂, a major greenhouse gas, making this a promising alternative for chemical CO₂ mitigation. To promote the economical use of enzymes, we engineered the carbonic anhydrase from Neisseria gonorrhoeae (ngCA) in the periplasm of Escherichia coli, thereby creating a bacterial whole-cell catalyst. We then investigated the application of this system to CO₂ sequestration by mineral carbonation, a process with the potential to store large quantities of CO₂. ngCA was highly expressed in the periplasm of E. coli in a soluble form, and the recombinant bacterial cell displayed the distinct ability to hydrate CO₂ compared with its cytoplasmic ngCA counterpart and previously reported whole-cell CA systems. The expression of ngCA in the periplasm of E. coli greatly accelerated the rate of calcium carbonate (CaCO₃) formation and exerted a striking impact on the maximal amount of CaCO₃ produced under conditions of relatively low pH. It was also shown that the thermal stability of the periplasmic enzyme was significantly improved. These results demonstrate that the engineered bacterial cell with periplasmic ngCA can successfully serve as an efficient biocatalyst for CO₂ sequestration.     

Yellow‐chevroned Parakeet (Brotogeris chiriri) abundance and canopy foraging at a dry forest in western Brazil

I studied Brotogeris chiriri abundance and foraging activity at a dry forest of the Urucum mountains in western Mato Grosso do Sul, Brazil, to evaluate their relationships with food resource production. Brotogeris chiriri abundance sharply increased during the early wet season (mainly October 2001) when it mostly foraged for fleshy fruits. At that time Protium heptaphyllum, one of the most common tree species, bore a large crop of fruits, the arils of which were extensively consumed by B. chiriri. Conversely, only a few parakeets were recorded foraging from the late wet to the late dry season, when dry fruit production predominated. The monthly pattern of parakeet abundance paralleled both its monthly pattern of foraging activity and fleshy fruit availability. Moreover, the variations in foraging activity were highly correlated to fleshy fruit production. Thus, data presented here evidenced the effect of both fruiting pulses and a common tree species that produced a large and ephemeral fruit crop, on the dynamic of a small and mobile canopy forager at a primary dry forest.