The rotifer fauna and population dynamics of Lake Studer 2 (Kerguelen Archipelago) with description ofFilinia terminalis kergueleniensis n. ssp. and a new record ofKeratella sancta Russel 1944

Two species of Anabas Cuvier, 1816 (Osteichthyes: Anabantidae): A. testudineus (Bloch, 1795) and A. oligolepis Bleeker, 1855 are widely distributed in India. Since both species are represented in one habitat — Lake Kolleru, and are very closely related, they were compared using starch gel electrophoresis. Electrophoretic separation of proteins of eye lens, skeletal muscle and heart muscle revealed differences such as i) absence of one protein fraction in one of them, ii) mobility and iii) staining intensity of some of the bands. The esterase (non-specific) patterns of serum, liver, kidney, skeletal muscle, heart muscle and eggs also showed differences. The LDH fraction of eye lens showed a difference in mobility.     

Effect of vertebrate predation on the spatio-temporal distribution of cladocerans in a temperature eutrophic lake

We analysed the spatio-temporal distribution of zooplankton along a profile of 10 stations from the shore to the pelagic zone from April to September 1988, the period when the larvae and juveniles Rutilus rutilus, the most abundant species in the Lake, are in the littoral zone. The digestive tracts of the young roach were analysed. They fed essentially on rotifers and on cladocerans. For comparison, zooplankton was also analysed at one littoral area without fish fry. There was an increase of cladoceran density from the vegetated nearshore zone to the offshore zone. Considering the density of Bosmina longirostris, Daphnia longispina, Chydorus sphaericus and Ceriodaphnia quadrangula, we observed a different distribution pattern in the course of the year. In the nearshore zone, the relative abundance of small species, Bosmina and Chydorus, was much higher than that of the larger Daphnia. From April to September, predation pressure mainly affected the smallest species: in contrast to the inshore station without fish fry, the density of Bosmina decreased in May in the littoral with fish. Chydorus was concentrated in the littoral between February and April, then grew into the pelagic zone, where predation pressure obviously was low during the warm season. The number of Daphnia, which was eaten by the fish fry at any time, remained low in the nearshore zone, which suggests that the presence of fish may cause Daphnia to avoid this zone. Ceriodaphnia which was not affected by this predation, was scarce in the nearshore zone during mid-summer. The low density of the cladocerans in the nearshore zone is likely associated with vertebrate predation by roach fry and juveniles, the result of such a process being either a depletion in density of the prey, or an avoidance behaviour.     

Evolutionary Divergence of the Genetic Architecture Underlying Photoperiodism in the Pitcher-Plant Mosquito, Wyeomyia Smithii

We determine the contribution of composite additive, dominance, and epistatic effects to the genetic divergence of photoperiodic response along latitudinal, altitudinal, and longitudinal gradients in the pitcher-plant mosquito, Wyeomyia smithii. Joint scaling tests of crosses between populations showed wide-spread epistasis as well as additive and dominance differences among populations. There were differences due to epistasis between an alpine population in North Carolina and populations in Florida, lowland North Carolina, and Maine. Longitudinal displacement resulted in differences due to epistasis between Florida and Alabama populations separated by 300 km but not between Maine and Wisconsin populations separated by 2000 km. Genetic differences between New Jersey and Ontario did not involve either dominance or epistasis and we estimated the minimum number of effective factors contributing to a difference in mean critical photoperiod of 5 SD between them as n(E) = 5. We propose that the genetic similarity of populations within a broad northern region is due to their more recent origin since recession of the Laurentide Ice Sheet and that the unique genetic architecture of each population is the result of both mutation and repeated migration-founder-flush episodes during the dispersal of W. smithii in North America. Our results suggest that differences in composite additive and dominance effects arise early in the genetic divergence of populations while differences due to epistasis accumulate after more prolonged isolation.     

Effects of invertebrate predation on the seasonal succession of a zooplankton community: a two year study in Lake Aydat,France

Saline playa lakes represent major geomorphic and hydrologic components of internal drainage basins in the arid to semiarid interior of Australia. These lakes mark the outcrop areas of regional shallow groundwater; thus, they are effective hydro-chemical sinks for elemental concentration and authigenic formation of carbonate, evaporite, and silica/silicate minerals.Field observations and petrochemical characterization of playa sediments from drainage basins in Western and Central Australia indicate that localized discharge of groundwater, from shallow aquifers in calcrete deposits, plays a fundamental role in geochemical evolution of playa-lake marginal facies. The available data indicates also that although evaporative concentration and salt recycling are major controls on geochemistry of the playas, yet a simple evaporative concentration model does not provide a complete explanation for brine evolution and particularly the geochemical process-product relationships observed in the individual playa lakes. The distribution of the chemical facies in the playas, in relation to geomorphic setting of the internal drainage basins, reflects a significant impact of variation in groundwater discharge pattern on the geochemical evolution of the playa lakes. Accordingly, the development of chemical facies in individual playas have progressed through repeated episodes of evaporative concentration, groundwater-level fluctuations and ion-exchange processes.     

The rotifer fauna of the River Loire (France), at the level of the nuclear power plants

In the heated affluents of nuclear power plants of the river Loire, rotifers are abundant. Cosmopolitan species are numerically dominant, but a tropical fauna is also present, among which the genus Brachionus, representing 20% of the total species, is best represented. From a comparison between water upstream and downstream of the power plants, it further appears that in downstream warmed-up waters, some species show an important development, but not in colder upstream waters.     

Block Copolymer/DNA Vaccination Induces a Strong Allergen-Specific Local Response in a Mouse Model of House Dust Mite Asthma

Background

Allergic asthma is caused by abnormal immunoreactivity against allergens such as house dust mites among which Dermatophagoides farinae (Der f) is a common species. Currently, immunotherapy is based on allergen administration, which has variable effect from patient to patient and may cause serious side effects, principally the sustained risk of anaphylaxis. DNA vaccination is a promising approach by triggering a specific immune response with reduced allergenicity.

Objective

The aim of the study is to evaluate the effects of DNA immunization with Der f1 allergen specific DNA on allergic sensitization, inflammation and respiratory function in mice.

Methods

Mice were vaccinated 28 and 7 days before allergen exposure with a Der f1-encoding plasmid formulated with a block copolymer. Asthma was induced by skin sensitization followed by intra-nasal challenges with Der f extract. Total lung, broncho-alveolar lavage (BAL) and spleen cells were analyzed by flow cytometry for their surface antigen and cytokine expression. Splenocytes and lung cell IFN-γ production by CD8+ cells in response to Der f CMH1-restricted peptides was assessed by ELISPOT. IgE, IgG1 and IgG2a were measured in serum by ELISA. Specific bronchial hyperresponsiveness was assessed by direct resistance measurements.

Results

Compared to animals vaccinated with an irrelevant plasmid, pVAX-Der f1 vaccination induced an increase of B cells in BAL, and an elevation of IL-10 and IFN-γ but also of IL-4, IL-13 and IL-17 producing CD4+ lymphocytes in lungs and of IL-4 and IL-5 in spleen. In response to CD8-restricted peptides an increase of IFN-γ was observed among lung cells. IgG2a levels non-specifically increased following block copolymer/DNA vaccination although IgE, IgG1 levels and airways resistances were not impacted.

Conclusions & Clinical Relevance

DNA vaccination using a plasmid coding for Der f1 formulated with the block copolymer 704 induces a specific immune response in the model of asthma used herein.     

Daytime grazing and assimilation rates of planktonic copepods Acanthodiaptomus denticornis and Cyclops vicinus vicinus. Comparison of spatial and resource utilisation by rotifers and cladoceran communities in a eutrophic lake

The clearance rates of ¹⁴ carbon-labelled Chlamydomonas sp. by the copepodite and adult stages of the 2 dominant species of Copepoda were studied in eutrophic Lake Aydat. They varied from 30 to 3,007 µl ind^–1 h^–1 for Acanthodiaptomus denticornis (mean = 600 µl ind^–1 h^–1) and from 20 to 1,133 µl ind^–1 h^–1 for Cyclops vicinus (mean = 340 µl ind^–1 h^–1). Their maximum assimilation efficiencies were 58% and 50%, respectively. These populations collectively could consume the available food in 4 days during September (maximum daily grazing rate = 24%). Mean individual clearance rates could be ranked Acanthodiaptomus denticornis > Ceriodaphnia quadrangula > Chydorus sphaericus > Daphnia longispina > Cyclops vicinus vicinus > Bosmina longirostris > K. cochlearis > K. quadrata and Kellicottia longispina. Like cladocerans and rotifers, the copepods living in this eutrophic lake can feed at low oxygen concentrations.     

Acanthodiaptomus denticornis another omnivorous calanoid copepod: description of its mouth appendages and feeding experiments on animal prey

The mouthpart morphology of the freshwater calanoid copepod Acanthodiaptomus denticornis was examined with optical microscopy. The mouthparts have sharp teeth and stout appendages with clawlike setae, typical of omnivorous calanoid mouthpart morphology. Observation of the buccal aperture with Scanning Electron Microscopy shows a large opening permitting feeding on prey as large as Keratella cochlearis. These observations agree with our feeding experiments which show that A. denticornis feed on K. cochlearis.