Multi-scale distribution and dynamics of bivalve larvae in a deep atoll lagoon (Ahe, French Polynesia).

Bivalve larvae and hydrographic parameters were sampled over a range of spatio-temporal scales in a deep atoll lagoon. Bivalve larvae abundances were very high throughout the year: 18,550 m(-3) in average. Larvae were (i) concentrated at mid-depth with nocturnal ascent and diurnal descent, (ii) heterogeneously dispersed at the lagoon scale, (iii) subject to day-to-day variation in abundance and (iv) transferred between different parts of the lagoon providing evidence of intra-lagoonal connectivity. The primacy of physical factors was seen on large spatial scale with the diluting effect of water renewal and transfers by hydrodynamics. On smaller spatial scale, the primacy of biological processes was recognised, with larval swimming activity leading to dial vertical migration correlated with food concentration. Variations in larval abundance were driven by bivalve reproductive activity correlated with meteorological conditions (i.e. windy periods). Finally, relationship between bivalve larvae patterns and pearl oyster (Pinctada margaritifera) settlement structuring is discussed.

Motility activation and metabolism characteristics of spermatozoa of the black-lip-pearl oyster Pinctada margaritifera var: cumingii (Jameson, 1901).

Motility of Pinctada margaritifera (Linnaeus, 1758); var: cumingii (Jameson, 1901) (P. margaritifera) spermatozoa collected from gonads are not immediately activated at spawning in seawater (SW) but motility occurs when spermatozoa are transferred into alkaline seawater (pH ranging from 9.0 to 11.4). This motility-activating effect of alkaline pH is reversed when pH is shifted back to more acidic values. In both cases, activity of sperm (% motile cells) increases gradually after alkaline pH activation then lasts for several minutes. The characteristics of these fully motile spermatozoa are described in details at the level of flagella: the wave amplitude and wave-length range 5 to 6 µm and 15 µm respectively, while the flagellar beat frequency is approximately 49 Hz. The velocity of sperm displacement is from 220 to 230 µm/sec. The general swimming pattern is almost circular: the head trajectories describe portions of circles intercalated with small linear segments. Spermatozoa saved in natural seawater at 4°C retain potent motility for several days and can be subsequently activated by alkaline seawater. Respiration and ATP concentration were measured in 3 conditions: regular seawater (pH 7.8), artificial diluent (pH 8.2), and alkaline Tris-buffered seawater (pH 10.5). Results show that sperm respiration rates are higher whereas ATP levels are lower in the latter two media.

Oyster vasa-like gene as a marker of the germline cell development in Crassostrea gigas.

The oyster vasa-like gene was previously demonstrated to be specifically expressed in germline cells of adult oysters Crassostrea gigas. In the present study, this gene was used as a molecular marker to establish the developmental pattern of germline cells during oyster ontogenesis, using whole-mount in situ hybridization and real-time PCR. The Oyvlg transcripts appeared to be localized to the vegetal pole of unfertilized oocytes and maternally transmitted to embryos. At early development, these maternal transcripts were observed to segregate into a single blastomere, from the CD macromere of 2-cell stage to the 4d mesentoblast of blastula. From late blastula stage, the mesentoblast divided into two cell clumps that migrated to both sides of the larvae body and that would correspond to primordial germ cells (PGCs). Based on these results, we postulate that the germline of C. gigas is specified at early development by maternal cytoplasmic determinants including Oyvlg mRNAs, in putative PGCs that would differentiate into germinal stem cells in juvenile oysters.

[Pleural trichomoniasis due to trichomonas tenax]. / Trichomonase pleurale à Trichomonas tenax.

Thoracic infections due to Trichomonas species often go unrecognised as they are seldom described in the literature. We describe a case that, to our knowledge, is the first reported case of empyema caused by this organism. A 59 year old man with metastatic adenocarcinoma of the lung developed a right pyopneumothorax following treatment with corticosteroids and radiotherapy. The pleural fluid was purulent and fetid, and contained large numbers of Trichomonas tenax amongst a mixed bacterial flora. Pleural drainage and antibiotic therapy with metronidazole, ciprofloxacin and gentalline were instituted immediately, but the patient died 4 days later. Trichomonas tenax is part of the normal oral floral and may on occasions colonize the airways. It can thus become involved during aspiration pneumonia or cause pleural infection following the rupture of a pulmonary abscess. Such infection tends to be associated with concurrent respiratory pathology or with immunodepression. The significance Trichomonas tenax when found in the airways is unclear and their pathogenic role is discussed.

Acinar primary cell culture from the digestive gland of Pecten maximus (L.): an original model for ecotoxicological purposes.

The purpose of this study was to establish an original primary acinar cell culture model for the mollusc bivalve Pecten maximus (L.), and to define its values and limits for subsequent ecotoxicological applications. To prevent microbial contaminations occurring frequently in invertebrate cell cultures, a perfusion of the stomach-digestive gland complex was performed in situ using a sterile salt solution containing broad-range antibiotics. Digestive acini were isolated using a pronase enzyme that was removed by several washings of the acinar suspension, after which their viability and functionality were determined by three different assays: fluorescein diacetate (FDA) de-esterification, 3-4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium (MTT) reduction and neutral red (NR) incorporation describing de-esterification, mitochondrial dehydrogenase and lysosome activity, respectively. The kinetic conditions for these assays were defined beforehand. The results showed that digestive acini could be maintained in vitro both cytologically and functionally for at least 96 h, which is sufficient for many ecotoxicological applications. Preliminary contamination assays, according to the function studied (cell esterases, mitochondrial respiration, lysosomal incorporation), indicated that polycyclic aromatic hydrocarbons had a negative effect on the survival of acini in vitro.

Evaluation of the toxicity of chemical compounds using digestive acini of the bivalve mollusc Pecten maximus L. maintained alive in vitro.

The digestive gland of bivalve molluscs is a model of choice for experiments in ecotoxicology because of its implication in detoxification processes moreover of its classical functions in digestive phenomena. All physiological deteriorations of this organ, related or not to pollution, can lead to animal death. The recent development of a method allowing digestive acini of Pecten maximus to be maintained alive in vitro for 96 h opens up new research prospects in ecotoxicology. The action of contaminants considered to be cytotoxic or genotoxic in the literature were tested on this model. The results show the high cytotoxicity of ethylmethane sulphonate 80 and 5 mM after 2 h of contact with acini. Other compounds such as 4-nitroquinoline-N-oxide 0.1 mM, cadmium chloride 10(-5) M and atrazine 10(-4) M, which were weakly toxic after 2 h, became highly toxic after 48 h of contact. Compounds such as 4-nitroquinoline-N-oxide 1 mM, which were not cytotoxic after 2 h, proved to be the most genotoxic of all those tested. Others, such as MMS 1 mM, cadmium chloride 10(-4) and 10(-5) M, and atrazine 10(-5) M, showed an unconfirmed tendency to be genotoxic. The results obtained with this 'acinus' model seem more readily transposable to the whole organism than those obtained with 'isolated cell' models, in that acini can be considered as digestive glands 'in miniature'.

Isolation of the pathogen Vibrio tapetis and defense parameters in brown ring diseased Manila clams Ruditapes philippinarum cultivated in England.

The Manila clam Ruditapes philippinarum was introduced for aquacultural purposes to Europe in the 1970s. In 1987, brown ring disease (BRD), caused by Vibrio tapetis, appeared in clams cultivated in Brouënou (Finistère, France) and later became increasingly widespread and was reported in cultivated and wild clams existing on the Atlantic coasts of France and Spain. The present study reports, for the first time, the presence of BRD in clams cultivated in England. The etiologic bacterium was isolated and identified using bacteriological and serological techniques. The defence response of affected clams was also studied and significant changes in the hematological and biochemical characteristics of hemolymph and extrapallial fluids were demonstrated. Significant mobilization of hemocytes toward the extrapallial fluids, in contact with the main site of infection (mantle-periostracal lamina area), was observed, suggesting a role for these pseudo-internal compartments in the preservation of clam health.

Reproductive characteristics and strategies of reducing-system bivalves.

The reproductive biology of Type 3 reducing-system bivalves (those whose pallial cavity is irrigated with water rich in reducing substances) is reviewed, with respect to size-at-maturity, sexuality, reproductive cycle, gamete size, symbiont transmission, and larval development/dispersal strategies. The pattern which emerges from the fragmentary data is that these organisms present reproductive particularities associated with their habitat, and with their degree of reliance on bacterial endosymbionts. A partial exception to this pattern is the genus Bathymodiolus, which also presents fewer trophic adaptations to the reducing environment, suggesting a bivalent adaptive strategy. A more complete understanding of the reproductive biology of Type 3 bivalves requires much more data, which may not be feasible for some aspects in the deep-sea species.

[PCR SSCP study of an echovirus 30 meningitis outbreak]. / Etude par PCR SSCP d'une épidémie de méningite à échovirus 30.

Between April and October 1997, 21 children of 4 days to 13 years old were admitted to the Pedatric Unit of Aulnay Sous Bois's Hospital for viral meningitidis. The number of white blood cells in the cerebrospinal fluid (CSF) was between 1 and 612 cells/mm3, with, on an average, 56% of segmented cells, 34% lymphocytes and 34% monocytes. Proteins and glucose of CSF were standard. One CSF was normal. Viral meningitidis was confirmed by viral culture of CSF onto MRC5. Enterovirus were identified by direct immunofluorescence (Monoclonal Mouse Anti-Enterovirus, Dako). Serotyping (Enterovirus antisera, Eurobio, Trousses 4) identified an echovirus 30 in all cases. A highly conserved 154 bp sequence at the 5'non-coding region was studied by reverse transcription-polymerase chain reaction (RT-PCR) followed by single-strand conformation polymorphism (SSCP) (GenPhor, Pharmacia) analysis. Two dominant SSCP patterns were observed: the first contained 4/21 strains and the other 10/21 strains. The SSCP patterns of the 7 other strains were different. These results show that 2 echovirus 30 dominant clones were responsible of viral meningitidis admitted to the Pediatric Unit of Aulnay Sous Bois's hospital, between april and october 1997. The PCR-SSCP of the 5'non-coding region of echovirus 30 is a convenient, simple, reproducible epidemiologic method and it's easily applicable in a general hospital.

Mycobacterium kansasii infection in a Paris suburb: comparison of disease presentation and outcome according to human immunodeficiency virus status. Groupe dEtude Des Mycobactéries de la Seine-Saint-Denis.

SETTING: Department of Seine-Saint-Denis, France. OBJECTIVE: To compare the presentation and outcome of Mycobacterium kansasii infections according to human immunodeficiency virus (HIV) status. DESIGN: Retrospective analysis of all the medical charts of adults meeting the diagnostic criteria of the American Thoracic Society for M. kansasii infection between 1991 and 1995. RESULTS: Between 1991 and 1995, 35 cases (23 HIV-[6%] and 12 HIV+ [34%]) were found, giving an annual incidence of 0.5/100000. The following particularities were common to both groups: 1) frequency and prominence of respiratory and general symptoms, 2) rarity of clinically apparent extra-thoracic involvement, 3) bacteriological confirmation mostly obtained with respiratory tract specimens, 4) favourable bacteriological outcome, and 5) low mortality attributable to the mycobacterial infection. The most striking differences concerned chest radiography: HIV- patients had apical cavitated and nodular lesions, while HIV+ patients exhibited a variety of other patterns, including alveolar infiltrates, miliary lesions and/or thoracic lymphadenopathy. CONCLUSION: Apart from pulmonary radiographic differences, presentation and short-term outcome of M. kansasii infections were similar in HIV+ and HIV-patients.

Molecular fingerprinting of Mycobacterium tuberculosis and risk factors for tuberculosis transmission in Paris, France, and surrounding area.

Forty-three percent of the tuberculosis cases reported in France are from the Ile de France region. The incidence of tuberculosis in this region is 33 cases per 100,000 inhabitants, twice the national average. A restriction fragment length polymorphism (RFLP) analysis was performed with clinical isolates of Mycobacterium tuberculosis isolated during 1995 in 10 hospitals in Paris and surrounding areas to detect tuberculosis transmission and define the factors associated with clustering in this population. The molecular markers used were the insertion sequence IS6110 and the direct repeat (DR) sequence. Social, demographic, and clinical data were collected from the patients' medical files. Ten patients with isolates with a single copy of IS6110 were excluded from further analysis. Twenty-four patients with false-positive cultures due to laboratory contamination (based on RFLP analysis with IS6110 and examination of patient data) were also excluded. The study was then conducted with 272 strains isolated from 272 patients. Further fingerprinting was performed by using the DR element with strains with patterns by RFLP analysis with IS6110 that differed by one band only and strains with identical patterns by RFLP analysis with IS6110 and with low numbers of copies of IS6110. The combined use of both markers identified unique patterns for 177 strains and clustered 95 (35.7%) strains in 26 groups, each containing isolates from 2 to 12 patients. The clustering was strongly associated with homelessness and the male sex. It was not associated with age, birth in a foreign country, human immunodeficiency virus positivity, or residence in hostels or prison. Isolates from homeless people were often included in large clusters, and homeless people could be the source of tuberculosis transmission for more than 50% of the clustered patients. These results suggest that homeless people play a key role in the spread of M. tuberculosis in the community and that poor socioeconomic conditions are the main risk factors associated with active tuberculosis transmission.

[Value of rectosigmoidoscopy with bacteriological culture of colonic biopsies in the diagnosis of post-antibiotic hemorrhagic colitis related to Klebsiella oxytoca]. / Intérêt de la rectosigmoïdoscopie avec culture bactériologique de biopsies coliques dans le diagnostic des colites hémorragiques post-antibiotiques associées à Klebsiella oxytoca.

UNLABELLED: We report 7 cases of antibiotic-associated and hemorrhagic colitis due to Klebsiella oxytoca. The diagnosis was performed by sigmoidoscopy with bacteriological biopsy culture. PATIENTS AND METHODS: Nine patients, aged 25-83 years, were hospitalized from February 1993 to October 1995 with hemorrhagic acute diarrhea following antibiotic treatment: amoxicillin (n = 3). amoxicillin-clavulanic acid (n = 4), cephalosporine (n = 2). All patients have had two stool samples cultures including Clostridium difficile toxin detection. Sigmoidoscopy with collection of biopsy specimens for bacteriological cultures was performed routinely. RESULTS: Endoscopic findings established the diagnosis of colitis in all cases: rectitis (n = 1), diffuse left colitis (n = 4), segmental left colitis (n = 4). The lesions were erythematous and purpuric (n = 5) or ulcerative (n = 4). Stool culture was normal in all cases but Klebsiella oxytoca was isolated in 7 cases (78%). CONCLUSIONS: Sigmoidoscopy and bioptic microbiology ensured the diagnosis of antibiotic-associated hemorrhagic colitis due to Klebsiella oxytoca.

[Value of proctosigmoidoscopy with bacteriological culture of colonic biopsies in the etiological diagnosis of post-antibiotic acute diarrhea in adults. Prospective study in 24 patients]. / Intérêt de la rectosigmoïdoscopie avec culture bactériologique de biopsies coliques dans le diagnostic étiologique de diarrhée aiguë post-antibiotique de l'adulte. Etude prospective sur 24 patients.

The aim of this study was to analyse the interest of proctosigmoidoscopy and biopsies microbiology in antibiotic-associated acute diarrhea in adults. Between February 1993 and October 1995, we have studied prospectively 24 patients with antibiotic-associated acute diarrhea. Ages ranged from 17 to 83 years. They had taken antibiotics: amoxicillin (n = 8) amoxicillin-clavulanic acid (n = 11), cephalosporinia (n = 3), cotrimoxazole (n = 1), macrolide (n = 1). For each patient, 2 stool cultures with Cytotoxin assay for Clostridium difficile and 3 fecal samples for parasitic enteropathogens were collected. Proctosigmoidoscopy with biopsies microbiology was carried out in all patients. Stool culture was always negative but colonic biopsies cultures were positive with Klebsiella oxytoca in 7 patients. Cytotoxin assay of C. difficile was positive in 11 patients. Proctosigmoidoscopy permitted also diagnosis of 2 pseudomembranous colitis without cytotoxin assay of C. difficile. Proctosigmoidoscopy permitted diagnosis of 83% of antibiotic-associated acute diarrhea. Complementary to Cytotoxin assay of C. difficile, it should be necessary in antibiotic-associated acute diarrhea in adults.

[Estimation of fertility and quality of oocytes emitted by the clam Ruditapes decussatus (Linnaeus 1758) during experimental inductions]. / Estimation de la fécondité et de la qualité des ovocytes émis par la palourde Ruditapes decussatus (Linné 1758) lors d'inductions expérimentales.

Experimental inductions were carried out on some genitors of clams Ruditapes decussatus to obtain sexual emissions and estimate the fecondity of this species. The genitors were collected from two sites of tunisian littoral. Higher percent of oocytes was found in summer with a maximum of 52 x 10(4) oocytes in Gargour (Golf of Gabès) against 45 x 10(4) in Menzel-Jemil (Lagoon of Bizerte). The observation under the electronic microscope of free oocytes allowed us to subdivised them in three groupes: immatures, matures and atretics. Only mature oocytes were susceptible to be feconded and underwent larval development with unknown proportion.