First chromosome scale genomes of ithomiine butterflies (Nymphalidae: Ithomiini): Comparative models for mimicry genetic studies

The ithomiine butterflies (Nymphalidae: Danainae) represent the largest known radiation of Müllerian mimetic butterflies. They dominate by number the mimetic butterfly communities, which include species such as the iconic neotropical Heliconius genus. Recent studies on the ecology and genetics of speciation in Ithomiini have suggested that sexual pheromones, colour pattern and perhaps hostplant could drive reproductive isolation. However, no reference genome was available for Ithomiini, which has hindered further exploration on the genetic architecture of these candidate traits, and more generally on the genomic patterns of divergence. Here, we generated high-quality, chromosome-scale genome assemblies for two Melinaea species, M. marsaeus and M. menophilus, and a draft genome of the species Ithomia salapia. We obtained genomes with a size ranging from 396 to 503 Mb across the three species and scaffold N50 of 40.5 and 23.2 Mb for the two chromosome-scale assemblies. Using collinearity analyses we identified massive rearrangements between the two closely related Melinaea species. An annotation of transposable elements and gene content was performed, as well as a specialist annotation to target chemosensory genes, which is crucial for host plant detection and mate recognition in mimetic species. A comparative genomic approach revealed independent gene expansions in ithomiines and particularly in gustatory receptor genes. These first three genomes of ithomiine mimetic butterflies constitute a valuable addition and a welcome comparison to existing biological models such as Heliconius, and will enable further understanding of the mechanisms of adaptation in butterflies.     

EPR and multi-field magnetisation of reduced forms of the binuclear iron centre in ribonucleotide reductase from mouse

Mouse ribonucleotide reductase is composed of a 1?:?1 complex of two homodimeric subunits and catalyses the first unique step on the biochemical pathway to DNA synthesis. The small subunit, protein R2, contains dinuclear iron-oxygen clusters and a tyrosyl free radical required for catalytic activity. We have studied the mixed valent and fully reduced forms of the diiron oxygen cluster from mouse R2 protein by low-temperature EPR. EPR signals of the mixed-valent states of proteins R2 reconstituted with ferrous iron and oxygen in normal and deuterated water, using the same buffers, show apparent g values of 1.92, 1.73, and 1.60 for the mixed-valent state in H₂O and 1.93, 1.73, and 1.62 in D₂O. These g values are typical for diiron-oxygen proteins, while the effect of D₂O is unprecedented for this class of proteins. We estimate the coupling constant J for the Heisenberg exchange (H?=?2J*S₁*S₂) to be J?=?–7.5±1?cm^–1 for the mixed-valent form. The diferrous R2 protein shows an integer spin EPR signal in the presence of azide or 20% glycerol. Variable temperature variable field saturation magnetisation measurements show that only in the azide-complexed R2 protein does a weak ferromagnetic coupling occur (J?=?0.26±0.05?cm^–1), while R2 protein in the absence or presence of 20% glycerol contains non-coupled mononuclear ferrous iron (S?=?2) sites.     

Photosynthetic performance of a helical tubular photobioreactor incorporating the cyanobacterium spirulina platensis

The photosynthetic performance of a helical tubular photobioreactor ("Biocoil"), incorporating the filamentous cyanobacterium Spirulina platensis, was investigated. The photobioreactor was constructed in a cylindrical shape (0.9 m high) with a 0.25-m(2)basal area and a photostage comprising 60 m of transparent PVC tubing of 1.6-cm inner diameter (volume = 12.1 L). The inner surface of the cylinder (area = 1.32 m(2)) was illuminated with cool white fluorescent lamps; the energy input of photosynthetically active radiation(PAR, 400 to 700 nm) into the photobioreactor was 2920 kJ per day. An air-lift system ncorporating 4%CO(2) was used to circulate the growth medium in the tubing. The maximum productivity achieved in batch culture was 7.18 g dry biomass per day [0.51 g . d biomass/L . day, or 5.44 g . d biomass/m(2)(inner surface of cylindrical shape)/day] which corresponded to a photosynthetic (PAR) efficiency of 5.45%. The CO(2) was efficiently removed from the gaseous stream; monitoring the CO(2) the outlet and inlet gas streams showed a 70% removal of CO(2) from the inlet gas over an 8-h period with almost maximum growth rate. (c) 1995 John Wiley & Sons, Inc.     

Oestradiol, a new hapten for detecting nucleic acid sequences by FISH

 Oestradiol has been conjugated to allylamine-dUTP with an 11-atom spacer to allow enzymatic incorporation of the label into DNA sequences. In a comparative DNA and mRNA FISH study we have used DNA probes that were either labelled with digoxigenin, biotin or oestradiol. Results show that oestradiol-labelled probes can detect DNA and RNA sequences in FISH equally well as digoxigenin- and biotin-labelled probes. Further, no crossreactivity between the various hapten-specific antibodies and the three haptens were observed. Binding of the rabbit anti-oestradiol antibody to endogenous oestrogen in various tissues was not observed under the conditions tested. In view of the increasing demands for multi-colour DNA and mRNA FISH applications, oestradiol is a welcome addition to the collection of haptens employed in FISH. Accepted 20 June 1997     

Candidose et tumeur obstructive intestinales chez un Babouin captif, ‘Papio Papio’ (Desm.)

Résumé Une candidose intestinale associée à une tumeur épithéliale, à métaplasie glandulaire, à pouvoir invasif marqué, provoquant une gêne du transit, a été découverte chez un Babouin de Guinée,Papio papio (Desm.) de la collection du Parc zoologique de Paris. A cette occasion nous avons rapporté les résultats concernant deux autres affections du tube digestid de nos Babouins captifs.

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Report of a case of candidiasis of the digestive tract associated to an obstructive epithelial tumor, with great invasive ability, in a captive Baboon,Papio papio (Desm.). Included is a discussion of the incidence of some intestinal disturbances involving candidiasis of subhuman Primates.

     

Growth of Streptomyces bambergiensis and glucose isomerase biosynthesis

Summary Growth and glucose isomerase biosynthesis in Streptomyces bambergiensis ATCC 13879 have been studied under different conditions. Some data concerning correlation between cultivation conditions and elemental analysis of the cells are also presented.