Recurrent congenital toxoplasmosis in a woman with lupus erythematosus

We describe the case of a patient with systemic lupus erythematosus, treated by corticosteroids, who presented during two successive pregnancies with serological reactivation of toxoplasmosis associated with fetal lesions. The first infected fetus died in utero with signs of hydrops. The second fetus was treated in utero with a combination of sulfadoxine and pyrimethamine, administered to the mother, and is now well. The increasing number of immunocompromised pregnant patients with immunity to Toxoplasma gondii may lead to a higher risk of reactivation of maternal toxoplasmosis and congenital infection.     

50 Jahre Elektroneninterferenzen

On the occasion of the anniversary a recollection is given of the history of the discovery of electron diffraction.

     

Phylogeographic study of the dwarf oyster, Ostreola stentina, from Morocco, Portugal and Tunisia: evidence of a geographic disjunction with the closely related taxa, Ostrea aupouria and Ostreola equestris

Despite the economic importance of oysters due to the high aquaculture production of several species, the current knowledge of oyster phylogeny and systematics is still fragmentary. In Europe, Ostrea edulis, the European flat oyster, and Ostreola stentina, the Provence oyster or dwarf oyster, are both present along the European and African, Atlantic and Mediterranean, coasts. In order to document the relationship not only between O. stentina and O. edulis, but also with the other Ostrea and Ostreola species, we performed a sequence analysis of the 16S mitochondrial fragment (16S rDNA: the large subunit rRNA-coding gene) and the COI fragment (COI: cytochrome oxidase subunit I). Oysters were sampled from populations in Portugal (two populations), Tunisia (two populations) and Morocco (one population), identified as O. stentina on the basis of shell morphological characters. Our data supported a high degree of differentiation between O. stentina and O. edulis and a close relationship between O. stentina and both Ostrea aupouria (from New Zealand) and Ostreola equestris (from Mexico Gulf/Atlantic). The status of this geographic disjunction between these closely related species is discussed. Furthermore, although identified in a separate genus Ostreola by Harry (Veliger 28:121–158, 1985), our molecular data on O. stentina, together with those available for the other two putative congeneric species, O. equestris and Ostreola conchaphila, would favour incorporation of Ostreola in Ostrea. Finally, a PCR-RFLP approach allowed the rapid identification of O. edulis and O. stentina.     

Activity patterns in the terebellid polychaete <Emphasis Type="Italic">Eupolymnia nebulosa</Emphasis> assessed using a new image analysis system

The activity and surface sediment displacement by the terebellid polychaete Eupolymnia nebulosa were monitored, using new image acquisition and image analysis procedures. We used a video sensor mounted on a motorized table, to acquire adjacent images of the whole studied aquarium within about 2 s. These images were then grouped within a composite image acquired every 15 s. Consecutive composite images were compared to infer activity and surface sediment displacement. This procedure proved efficient for E. nebulosa as indicated by (1) the continuity of the tentacles within composite images, and (2) the direct comparison of images and detected activities. There were important temporal changes in the relative importance of the three main types of activity: feeding, tube-building and (both partial and total) emergence from the tube, accounting, respectively, for 75, 15 and 10% of the entire experiment duration. Activity intensity (cm² min^-1) was assessed through the surface of pixels with grey levels differing by more than 20 (on a 0–255 scale) between two consecutive images. Feeding was associated with low activity intensity, whereas tube-building and emergence from the tubes were associated with high activity intensities. Surface sediment displacement mostly resulted from tentacle activity both during feeding and tube-building and was almost zero when worms emerged from their tube. We used our experimental set up to assess spatial changes in activity intensity and particle displacements along the tentacles. Most of the activity occurred within the first 4–6 cm from the tube aperture. Particle loss during their transfer along the tentacles preferentially affected larger particles as postulated by the model of particle selection and transport in tentaculate deposit-feeders. Moreover, the speed of the particles along the tentacles correlated negatively with their size. This contributed to increase in the residence time of larger particles on the tentacles and thus, to further enhance their probability of being lost. The size distributions of particles during feeding and tube-building did not differ significantly although visual observations confirmed the preferential use of larger particles for tube-building. This suggests the existence of a sorting step occurring elsewhere than on the tentacles as already demonstrated for spionid polychaetes.     

Ingestion of pico- and nanoplankton by the Mediterranean red coral Corallium rubrum

This study investigates the feeding behaviour of the precious red coral Corallium rubrum on bacterioplankton. The effects of flow rate, prey concentration, and seawater temperature were tested. The results obtained show that C. rubrum was able to prey on both pico- and nanoplankton cells. Flagellates constituted the major bacterioplankton food source in terms of carbon and nitrogen, representing from 43 to 70% of the C and N ingested. Flow speed (2, 6, and 11 cm s⁻¹) had no effect on grazing rates, maybe due to the small size of the ingested particles. Conversely, feeding rates increased with prey concentration and seawater temperature. There was a doubling of the picoplankton ingestion rate for a sixfold increase in its concentration. The ingestion of autotrophic flagellates, however, increased at the same time as their concentration, indicating a preference for this type of food. Considering the range of concentrations typically found in the Ligurian Sea, the ingestion of pico- and nanoplankton brings 148 ng C polyp⁻¹ day⁻¹ and 28 ng N polyp⁻¹ day⁻¹. This type of food represents only ca. 4.5% of the total carbon gained by C. rubrum from the different sources, but might be the most important in terms of nitrogen, phosphorus, and other essential elements.     

Toxic dinoflagellates (Alexandrium fundyense and A. catenella) have minimal apparent effects on oyster hemocytes

The possible effect of Alexandrium spp. containing paralytic shellfish poisoning (PSP) toxins on the hemocytes of oysters was tested experimentally. In one trial, eastern oysters, Crassostrea virginica Gmelin, were exposed to bloom concentrations of the sympatric dinoflagellate, Alexandrium fundyense Balech, alone and in a mixture with a non-toxic diatom, Thalassiosira weissflogii (Grun) Fryxell et Hasle. Subsequently, another experiment exposed Pacific oysters, Crassostrea gigas Thunberg, to a mixed suspension of the sympatric, toxic species Alexandrium catenella (Whedon et Kofoid) Balech, with T. weissflogii. Measurements of numbers of oyster hemocytes, percentages of different cell types, and functions (phagocytosis, reactive oxygen species (ROS) production, and mortality) were made using flow-cytometry. During and after exposure, almost no significant effects of Alexandrium spp. upon hemocyte numbers, morphology, or functions were detected, despite observations of adductor-muscle paralysis in C. virginica and measured toxin accumulation in C. gigas. The only significant correlation found was between toxin accumulation at one temperature and higher numbers of circulating live and dead hemocytes in C. gigas. The PSP toxins are known to interfere specifically with sodium-channel function; therefore, the finding that the toxins had no effect on measured hemocyte functions suggests that sodium-channel physiology is not important in these hemocyte functions. Finally, because oysters were exposed to the living algae, not purified toxins, there was no evidence of bioactive compounds other than PSP toxins affecting hemocytes in the two species of Alexandrium studied.     

Comparaison biochimique de quatre espèces de copépodes planctoniques de Méditerranée nord-occidentale à partir des enzymogrammes des estérases,de la leucine aminopeptidase,de la phosphatase alcaline,de la malate déshydrogénase et de l'enzyme malique

Four copepod species (Acartia clausi, Centropages typicus, Temora stylifera, Calanus helgolandicus) from the northwest Mediterranean were subjected to electrophoresis on polyacrylamide gel in an attempt to distinguish specific biochemical characteristics for each species. Enzymograms of 5 enzymes were studied: esterases, leucine aminopeptidase, alkaline phosphatase, malate dehydrogenase and the malic enzyme. Marked interspecific differences were revealed, enabling specific biochemical identities to be established which can be useful as taxonomic criteria in the same way as morphological characteristics. The study was performed during different seasons in 1980.     

Fécondité de Nephrops norvegicus dans le golfe de Gascogne

Females of the Norway lobster Nephrops norvegicus (L.) incubate their eggs under the abdomen for a period of several months. We estimated the individual fecundity of N. norvegicus (1) before spawning, and (2) at the end of the incubation period. From these two relationships, we then calculated the average egg loss. Egg loss seems to be relatively higher for small females than for large ones. The mean egg loss estimated for the Bay of Biscay (45%) differs from the only other existing value (75%) calculated by other authors for Portuguese waters. Egg loss may regulate stock-density, and may be a mechanism intervening in stock-recruitment. In order to estimate the fecundity per recruit, fecundity at the end of the incubation period must be used: this takes into account the rate of egg loss as a function of female length.

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Contribution No. 721, du Centre Océanologique de Bretagne     

A simple voltammetric procedure for speciation and evaluation of As removal from water

Here, we show a fast and sensitive method for the determination of inorganic arsenic in natural waters using differential pulse cathodic stripping voltammetry. All the arsenite determinations were done in 2.0 mol L⁻¹ HCl + 3.15 × 10⁻⁴ mol L⁻¹ Cu(II) supporting electrolyte. 1 × 10⁻³ mol L⁻¹ sodium thiosulphate was used as As(V) reducing agent. The detection limit was 0.5 μg L⁻¹ for both species. The method has been applied to water samples collected in an arsenic-contaminated region of Brazil, in particular, to verify the efficiency of the solar oxidation and removal of arsenic process applied to these waters.