Simultaneous Raman microspectroscopy and fluorescence imaging of bone mineralization in living zebrafish larvae

Confocal Raman microspectroscopy and fluorescence imaging are two well-established methods providing functional insight into the extracellular matrix and into living cells and tissues, respectively, down to single molecule detection. In living tissues, however, cells and extracellular matrix coexist and interact. To acquire information on this cell-matrix interaction, we developed a technique for colocalized, correlative multispectral tissue analysis by implementing high-sensitivity, wide-field fluorescence imaging on a confocal Raman microscope. As a proof of principle, we study early stages of bone formation in the zebrafish (Danio rerio) larvae because the zebrafish has emerged as a model organism to study vertebrate development. The newly formed bones were stained using a calcium fluorescent marker and the maturation process was imaged and chemically characterized in vivo. Results obtained from early stages of mineral deposition in the zebrafish fin bone unequivocally show the presence of hydrogen phosphate containing mineral phases in addition to the carbonated apatite mineral. The approach developed here opens significant opportunities in molecular imaging of metabolic activities, intracellular sensing, and trafficking as well as in vivo exploration of cell-tissue interfaces under (patho-)physiological conditions.

Prevalence and genetic variants of hepatitis GB-C/HG and TT viruses in Gabon, equatorial Africa

The distribution of Hepatitis GB-C/HG (GB-C/HG) and TT viruses (TTV) infections was investigated in selected populations from Gabon using Polymerase Chain Reaction (PCR) and Enzyme Linked Immunosorbent Assay (ELISA) for anti-Envelop 2 (anti-E2) GBV-C/HGV antibodies. Among pregnant women, 29 of 229 (12.6%) were Hepatitis GB virus-C and Hepatitis G virus (GBV-C/HGV) RNA positive (+) and 32 of 81 (39.5%) anti-E2 + versus 8 of 39 (20.5%) TTV DNA +. Among sickle cell anemia patients, 9.7% (3/31) were GBV-C/HGV RNA + versus 22.5% (7/31) TTV DNA +. For tuberculosis patients, the figures were 11.5% (4/35) and 0%. A study of hepatocellular carcinoma cases (n = 27) versus controls (n = 66) did not show significant differences for GBV-C/HGV RNA (10.7% versus 12.1%) and TTV DNA (44.4% versus 30.3%). According to phylogenetic analysis, the 15 GBV-C/HGV strains investigated clustered in group 1, the most common in sub-Saharan Africa whereas TTV sequences (n = 4) mostly clustered in genotypes G1 and one close to genotype G3. In the Gabonese populations investigated, GBV-C/HGV and TTV infections were highly endemic. These data are consistent with the low pathogenicity of these agents.

[The consumption of cassava is not responsible for the etiology of endemic goiter in rural areas in Senegal]

An epidemiological study of iodine deficiency disorders (IDD) was carried out in West Senegal and Casamance. Five hundred and eighty five households were selected in 3 areas with a high prevalence of goiter. We assessed the relative impact of iodine deficiency (estimated by mean iodine excretion in the urine of family members) and cassava consumption (mean frequency of consumption by the household). Cassava consumption, even if on a regular basis, neither caused nor increased goiter formation in this area of West Africa. This was probably due to the local method of cassava root preparation, which reduces the amount of cyanogenic compounds consumed. Iodine deficiency was principally responsible for goiter formation. Therefore, the commercial availability of iodine-supplemented salt should lead to the eradication of IDD from Senegal in the near future.

The synthesis of vitellogenins by the digestive gland of Helix aspersa: evidence from cell-free translation of mRNA

All the RNAs were extracted separately from the gonads and digestive glands of the garden snail Helix aspersa. After separation by oligo-dT-cellulose chromatography, the mRNA were evaluated using optical density measurements and agarose gel electrophoretic analysis and then used in a cell-free translation system: a rabbit reticulocyte lysate added with 35S methionine. The in vitro synthesized proteins were characterized by immunoprecipitation with polyclonal antibodies which were raised against mature oocyte proteins. The proteins were then evaluated quantitatively using liquid scintillation counting and qualitatively using SDS polyacrylamide gel electrophoresis and fluorography. The results demonstrated that the digestive gland of the garden snail is a vitellogenin synthesis site.