Calcein staining of calcified structures in pearl oyster Pinctada margaritifera and the effect of food resource level on shell growth

International audienceMarine mollusc shell growth has been widely measured using fluorochrome marking. In order to test the efficiency and reliability of calcein staining on Pinctada margaritifera shells and pearls, the present study examined two administration methods, different concentrations and several immersion times. Immersion in a 150 mg L-1 calcein solution for 12 h to 24 h appeared to be the best method for marking P. margaritifera shells. For pearl marking, injection of a 200 mg L-1 calcein solution into the pearl pouch was the optimal method. Calcein marking was then used to measure the influence of food resource levels on the shell growth. Groups of 23-month-old P. margaritifera were fed at three trophic levels for two months. The two highest food levels tested (6000 cell mL(-1) and 15000 cell mL(-1)) induced uniform growth between the dorsal and ventral sides of shell, whereas the lowest food level (800 cell mL(-1)) induced greater growth on the dorsal side. Shell deposits from the ventral side were observed using a scanning electron microscope, revealing that the difference of the trophic level over two months had modified the thickness of the aragonite tablets formed. These results showed that the trophic level is a major factor conditioning P. margaritifera development. (C) 2011 Elsevier B.V. All rights reserved

The Effects of Increased pCO\u3csub\u3e2\u3c/sub\u3e and Temperature on the North Atlantic Spring Bloom: I. The Phytoplankton Community and Biogeochemical Response

ABSTRACT: The North Atlantic spring bloom is one of the largest annual biological events in the ocean, and is characterized by dominance transitions from siliceous (diatoms) to calcareous (coccolithophores) algal groups. To study the effects of future global change on these phytoplankton and the biogeochemical cycles they mediate, a shipboard continuous culture experiment (Ecostat) was conducted in June 2005 during this transition period. Four treatments were examined: (1) 12°C and 390 ppm CO2 (ambient control), (2) 12°C and 690 ppm CO2 (high pCO2), (3) 16°C and 390 ppm CO2 (high temperature), and (4) 16°C and 690 ppm CO2 (‘greenhouse’). Nutrient availability in all treatments was designed to reproduce the low silicate conditions typical of this late stage of the bloom. Both elevated pCO2 and temperature resulted in changes in phytoplankton community structure. Increased temperature promoted whole community photosynthesis and particulate organic carbon (POC) production rates per unit chlorophyll a. Despite much higher coccolithophore abundance in the greenhouse treatment, particulate inorganic carbon production (calcification) was significantly decreased by the combination of increased pCO2 and temperature. Our experiments suggest that future trends during the bloom could include greatly reduced export of calcium carbonate relative to POC, thus providing a potential negative feedback to atmospheric CO2 concentration. Other trends with potential climate feedback effects include decreased community biogenic silica to POC ratios at higher temperature. These shipboard experiments suggest the need to examine whether future pCO2 and temperature increases on longer decadal timescales will similarly alter the biological and biogeochemical dynamics of the North Atlantic spring bloom

Influence of LRP5 polymorphisms on normal variation in BMD

Genetic studies based on cohorts with rare and extreme bone phenotypes have shown that the LRP5 gene is an important genetic modulator of BMD. Using family-based and case-control approaches, this study examines the role of the LRP5 gene in determining normal population variation of BMD and describes significant association and suggestive linkage between LRP5 gene polymorphisms and BMD in >900 individuals with a broad range of BMD

Infections and multiple sclerosis: Recommendations from the French Multiple Sclerosis Society

International audienceIntroduction: Viral, bacterial, or fungal infections are suspected of triggering multiple sclerosis (MS) and promoting relapses of the disease and are likely to be promoted by immune-active treatments. This raises questions about the infectious workup and preventive treatment of these infections prior to their initiation.Objectives: To establish recommendations on infections and MS. Provide information to patients and healthcare professionals on the minimal infectious workup to be performed in an MS patient at diagnosis and prior to initiation of immuno-active therapy in MS.Methods: The recommendation attempts to answer four main questions about infections and MS. The French Group for Recommendations in Multiple Sclerosis (France4MS) did a systematic review of articles from PubMed and universities databases (from January 1975 to June 2020), using the RAND/UCLA formalized consensus method. The RAND/UCLA method has been developed to synthesize the scientific literature and expert opinions on health care topics and was used for reaching a formal agreement. Twenty-three experts contributed to the detailed review and a group of 63 multidisciplinary health professionals validated the final version of 36 recommendations.Results: It is recommended that MS patients undergo a minimal infectious workup, check their vaccination status at diagnosis, and repeat it during follow-up and before starting immunotherapy. Screening and preventive treatment of viral (group Herpes virus, HPV, JCV, HCV, HBV), bacterial (mycobacteria) and fungal (Cryptococcus) infections is recommended prior to the initiation of certain immuno-active MS therapies.Discussion and conclusions: At diagnosis of MS and prior to the choice of therapeutic strategy, it is recommended to update the vaccination schedule of MS patients in reference to the HCSP vaccination schedule and the SFSEP recommendations. Before starting immunosuppressive treatment, it is recommended to inform patients of the risks of infections and to look for a constitutive or acquired immune deficiency. Health professionals and patients should be informed of the updated recommendations on infections and MS