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101.
Bonny Patrice Desdouits Marion Schaeffer Julien Garry Pascal Essia Ngang Jean Justin Le Guyader Françoise S. 《Food and environmental virology》2020,12(3):274-277
Food and Environmental Virology - Shellfish constitute an important protein source but may be contaminated by viruses from various origins. A study performed on clams collected in Cameroon showed a... 相似文献
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The composition of the herbaceous cover and the seed bank of old and recent hedge banks in Brittany were studied and compared. Concentration method was used for seed bank samples. Grimes plant strategies were used to explain observed patterns. The analysis of the seed bank of these hedge banks showed that the species richness and diversity differed in relation to the date of construction of the hedge banks. The seed banks of recent hedge banks were richer and more diversified than those of old hedge banks. Differences in the floristic composition of the established plant cover between the recent and old hedge banks were determined by multivariate analyses. The species exclusively found in the seed bank and in the herb cover of recent hedge banks were mainly grassland species, whereas the species that only occurred on old hedge banks tended to be woodland species. The floristic composition of the two compartments (established vegetation and seed bank) was very different. A multivariate analysis revealed that the difference between the composition of the seed banks of recent and old hedge banks was less than that between the composition of the established vegetation and seed bank of hedge banks of the same age. Both seed bank and vegetation of recent hedge banks were dominated by ruderal species, whereas old hedge vegetation was dominated by stress-tolerant woodland species, indicating that mechanically constructed hedge banks may impose limitations on colonization by late woodland species. 相似文献
104.
François Vialard Giuseppe Simoni Denise Molina Gomes Azzedine Abourra Simona De Toffol Fabrice Bru Maria Carmen Martinez Romero Lucio Nitsch Philippe Bouhanna Livia Marcato Thomas Popowski Beatrice Grimi Jose Antonio Martínez-Conejero B. Benzacken Rita Genesio Francesca R. Grati 《黑龙江环境通报》2012,32(4):329-335
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Maternal serum markers for trisomy 21 screening (MSS) can be assayed in women ≥35 years in an attempt to reduce the need for invasive procedures and thereby avoid their side effects. Our objective was to compare, in women ≥35, eight different software packages dedicated to second trimester MSS, thus providing reliable data for patient counselling. A simulation study was carried out on 189 sera from women with Down syndrome fetuses and 11 962 sera from mothers of unaffected babies. The first step was to estimate the joint distribution of alpha-fetoprotein (AFP) and free beta-human chorionic gonadotrophin (β-hCG). The second step was to calculate trisomy 21 detection and false-positive rates for each software according to maternal age (35–45 years), using the usual 1:250 risk threshold. Agreement between software packages was measured using 2×2 kappa coefficients. Detection rates and false-positive rates increased with maternal age. Depending on the software, 57–71% detection rates were achieved at 35 years with 12–18% false-positive rates. At 45 years, 61–100% detection rates were achieved with 66–95% false-positive rates. Up to 39 years, all softwares were concordant (kappa coefficients >0.75). In the range 35–45 years, false-positive and detection rates increased substantially with maternal age and differences between software packages are observed. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
109.
Jean-Pierre Lechaire Ghislaine Frébourg Françoise Gaill Olivier Gros 《Marine Biology》2008,154(4):693-700
In this study, Codakia orbicularis gill-tissues were cryo-fixed by using high-pressure freezing, a freeze substitution process and finally by cryo-embedding
in Lowicryl. Ultrathin sections were then used for an EFTEM microanalysis. Results show that intracellular bacterial symbionts
contain elemental sulphur in periplasmic vesicles as indicated by conventional TEM. When sulphur is temporarily depleted in
the environment, such structures may act as energy sources for bacterial metabolism. Moreover, sulphate was detected in the
cytoplasm of the bacterial symbionts, suggesting the oxidation of elemental sulphur, located in periplasmic granules, to sulphate
(the final step in sulphur oxidation) by these chemoautotrophic bacteria. To assess the effects of host starvation on the
bacterial sulphur content, adult individuals of C. orbicularis were maintained in starvation for 6 weeks in sterile artificial seawater depleted in sulphur. During starvation, both (1)
the number of bacteria inside the bacteriocytes and (2) the number of periplasmic granules per prokaryotic cell decreased.
The content of the remaining periplasmic granules had been modified to sulphate. This observation suggests that bacterial
gill-endosymbionts used the elemental sulphur in their periplasmic granules as stored substrate for oxidation in order to
produce energy in case of sulphur depletion. 相似文献
110.
The determination of reproductive status and the reconstruction of individual reproductive histories are central to many ecological
studies. In cetaceans, it has been assumed that ovarian scars accumulate with age and provide a lifetime record of female
reproductive history. If ovarian scars persist, the number of scars should increase with age after puberty. To test this,
we examined age, reproductive status and ovarian scars from 187 short-beaked common dolphins (Delphinus delphis) from the eastern North Atlantic. The number of Corpus Albicans (CA) present in ovaries did not increase with age after age
at sexual maturity (ASM), suggesting that ovarian scars are not persistent and that their number at any one time would be
a function of rates of ovulation and healing, the latter being defined here as the resorption or disintegration of CA tissue.
Since female mammals stop ovulating when pregnant, inferences about healing rates could be made by using pregnant females.
Pregnant females had ca. 40% fewer scars than non-pregnant females. This suggests that most CAs would heal quickly, with a
half-life of less than 1 year, although larger scars may persist longer. Therefore, counting CAs would have limited potential
for reconstructing individual reproductive lifetime histories in the common dolphin. A reassessment of the use of ovarian
scars to reconstruct individual life reproductive histories in cetaceans is suggested. 相似文献