A highly divergent HIV-2-related isolate

It has been suggested that the human immunodeficiency virus type 2 (HIV-2) and the simian immunodeficiency virus from rhesus macaques (SIVmac) evolved from the sooty mangabey virus SIVsm (ref. 1). We now describe an HIV-2-related isolate, HIV-2-D205, from a healthy Ghanaian woman that is genetically equidistant to the prototypic HIV-2 strains and to SIVsm and SIVmac. Supported by the observation that HIV-2D205 differs in a step of envelope glycoprotein processing, our data indicate that it could represent an alternative HIV-2 subtype and that viruses of the HIV-2/SIVsm/SIVmac group could have already infected humans before HIV-2 and SIVsm/SIVmac diverged.     

Comportement nucléaire anormal dans la racine d'Ornithogalum umbellatum L.

Zusammenfassung BeiOrnithogalum umbellatum findet sich in einzelnen Wurzelspitzen eine allgemein auftretende anomale Zweiteilung des Ruhekerns. Sämtliche Zellen einer Zellenreihe vollziehen die Teilungen synchron. Die getrennten Kernhälften liegen beiderseits einer Ebene, welche die Zellreihe in ihrer Längsrichtung durchschneidet.     

Die Zucht vonLytta vesicatoria im Laboratorium und Nachweis der Cantharidinsynthese in Larven

Summary Adult males ofLytta vesicatoria (Coleopt., Meloidae) synthesize cantharidin, but females do not, although the substance is present in the females too. We developed a method for rearing larvae of this parasitic beetle in the laboratory. It is shown that there exist 7 larval stages and 4 hypermetamorphic forms (triungulinus, second larva,pseudochrysalis and fourth larva). Larvae from the second to the fifth stage (second larva) synthesize cantharidin. Therefore, we conclude that the substance present in the adult female is at least in part synthesized in the larval period. Nothing is known about the biological significance of this biochemical sexual dimorphism.

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Coleoptera, Meloidae.     

Noninvasively diagnosing coronary artery disease with 61-channel MCG data

Magnetocardiography(MCG) has been investigated as a tool for noninvasive detection of coronary artery disease(CAD). In this study, the area ratio of positive and negative magnetic induction extracted from an extrema circle in the magnetocardiogram was analyzed at specific time points in the cardiac cycle: P maximum, R peak, J point, T onset, T peak and T end. The area of the positive proportion of the magnetic field relative to the total area within a circle encompassing the field extrema was determined and proposed for fast-speed CAD diagnosis. MCG was performed with a 61-channel biomagnetometer in a shielded environment in 38 healthy subjects and 15 CAD patients. A notable difference in area ratio was found between healthy and CAD subjects at the peak time of T wave: 0.416 ± 0.090 versus0.465 ± 0.065(p = 0.013). Using a cutoff value of 0.4506resulted in a sensitivity and specificity of 86.7 % and 73.8 %,respectively. This approach may enable a fast-speed CAD diagnosis in a clinical setting.     

Genetic variation in Mon1a affects protein trafficking and modifies macrophage iron loading in mice

We undertook a quantitative trait locus (QTL) analysis in mice to identify modifier genes that might influence the severity of human iron disorders. We identified a strong QTL on mouse chromosome 9 that differentially affected macrophage iron burden in C57BL/10J and SWR/J mice. A C57BL/10J missense allele of an evolutionarily conserved gene, Mon1a, cosegregated with the QTL in congenic mouse lines. We present evidence that Mon1a is involved in trafficking of ferroportin, the major mammalian iron exporter, to the surface of iron-recycling macrophages. Differences in amounts of surface ferroportin correlate with differences in cellular iron content. Mon1a is also important for trafficking of cell-surface and secreted molecules unrelated to iron metabolism, suggesting that it has a fundamental role in the mammalian secretory apparatus.     

Phosphatidylinositol-3,5-bisphosphate lipid-binding-induced activation of the human two-pore channel 2

Mammalian two-pore channels (TPCs) are activated by the low-abundance membrane lipid phosphatidyl-(3,5)-bisphosphate (PI(3,5)P₂) present in the endo-lysosomal system. Malfunction of human TPC1 or TPC2 (hTPC) results in severe organellar storage diseases and membrane trafficking defects. Here, we compared the lipid-binding characteristics of hTPC2 and of the PI(3,5)P₂-insensitive TPC1 from the model plant Arabidopsis thaliana. Combination of simulations with functional analysis of channel mutants revealed the presence of an hTPC2-specific lipid-binding pocket mutually formed by two channel regions exposed to the cytosolic side of the membrane. We showed that PI(3,5)P₂ is simultaneously stabilized by positively charged amino acids (K203, K204, and K207) in the linker between transmembrane helices S4 and S5 and by S322 in the cytosolic extension of S6. We suggest that PI(3,5)P₂ cross links two parts of the channel, enabling their coordinated movement during channel gating.