Carotenoid Distribution in Living Cells of Haematococcus pluvialis (Chlorophyceae)

Haematococcus pluvialis is a freshwater unicellular green microalga belonging to the class Chlorophyceae and is of commercial interest for its ability to accumulate massive amounts of the red ketocarotenoid astaxanthin (3,3′-dihydroxy-β,β-carotene-4,4′-dione). Using confocal Raman microscopy and multivariate analysis, we demonstrate the ability to spectrally resolve resonance–enhanced Raman signatures associated with astaxanthin and β-carotene along with chlorophyll fluorescence. By mathematically isolating these spectral signatures, in turn, it is possible to locate these species independent of each other in living cells of H. pluvialis in various stages of the life cycle. Chlorophyll emission was found only in the chloroplast whereas astaxanthin was identified within globular and punctate regions of the cytoplasmic space. Moreover, we found evidence for β-carotene to be co-located with both the chloroplast and astaxanthin in the cytosol. These observations imply that β-carotene is a precursor for astaxanthin and the synthesis of astaxanthin occurs outside the chloroplast. Our work demonstrates the broad utility of confocal Raman microscopy to resolve spectral signatures of highly similar chromophores in living cells

‘There is a Time to be Born and a Time to Die’ (Ecclesiastes 3:2a): Jewish Perspectives on Euthanasia

Reviewing the publications of prominent American rabbis who have (extensively) published on Jewish biomedical ethics, this article highlights Orthodox, Conservative and Reform opinions on a most pressing contemporary bioethical issue: euthanasia. Reviewing their opinions against the background of the halachic character of Jewish (biomedical) ethics, this article shows how from one traditional Jewish textual source diverse, even contradictory, opinions emerge through different interpretations. In this way, in the Jewish debate on euthanasia the specific methodology of Jewish (bio)ethical reasoning comes forward as well as a diversity of opinion within Judaism and its branches

Spongiform encephalopathy in transgenic mice expressing a point mutation in the β2-α2 loop of the prion protein

Transmissible spongiform encephalopathies are fatal neurodegenerative diseases attributed to misfolding of the cellular prion protein, PrP(C), into a β-sheet-rich, aggregated isoform, PrP(Sc). We previously found that expression of mouse PrP with the two amino acid substitutions S170N and N174T, which result in high structural order of the β2-α2 loop in the NMR structure at pH 4.5 and 20°C, caused transmissible de novo prion disease in transgenic mice. Here we report that expression of mouse PrP with the single-residue substitution D167S, which also results in a structurally well ordered β2-α2 loop at 20°C, elicits spontaneous PrP aggregation in vivo. Transgenic mice expressing PrP(D167S) developed a progressive encephalopathy characterized by abundant PrP plaque formation, spongiform change, and gliosis. These results add to the evidence that the β2-α2 loop has an important role in intermolecular interactions, including that it may be a key determinant of prion protein aggregation

Effect of Glucose on Carbon Dioxide Assimilation and Substrate Oxidation by <i>Ferrobacillus ferrooxidans</i>

Ferrobacillus ferrooxidans , grown on either elemental sulfur or ferrous sulfate, was able to use either substrate as an energy source for the assimilation of CO 2 . In both cases, 0.01 μmole of carbon was incorporated per μmole of oxygen utilized. Glucose inhibited substrate oxidation and CO 2 fixation. Sulfur and iron oxidation were inhibited 5 to 15% and 40 to 50%, respectively, in the presence of 10% glucose. Under the same conditions, CO 2 assimilation was inhibited 50% with elemental sulfur as the energy source, and was almost totally inhibited when ferrous iron was used. </jats:p

Acquisitions thérapeutiques 1995 : Complications des maladies hépatiques

Ce texte résume les nouvelles acquisitions thérapeutiques de l'année 1995 concernant les complications des maladies hépatiques. L'année 1995 a été caractérisée par un regain d'intérêt pour le traitement médicamenteux dans l'hémorragie digestive aiguë sur rupture des varices oesophagiennes et dans la prévention de la récidive. L'efficacité de l'administration précoce de terlipressine ou d'octréotide améliore la survie des patients. L'association d'octréotide avec la sclérothérapie est supérieure à la sclérothérapie seule. D'autres publications viennent confirmer ou nuancer des thérapies déjà connues