Maternal Transcripts of Hox Genes Are Found in Oocytes of Platynereis dumerilii (Annelida, Nereididae)

Hox genes are some of the best studied developmental control genes. In the overwhelming majority of bilateral animals, these genes are sequentially activated along the main body axis during the establishment of the ground plane, i.e., at the moment of gastrulation. Their activation is necessary for the correct differentiation of cell lines, but at the same time it reduces the level of stemness. That is why the chromatin of Hox loci in the pre-gastrulating embryo is in a bivalent state. It carries both repressive and permissive epigenetic markers at H3 histone residues, leading to transcriptional repression. There is a paradox that maternal RNAs, and in some cases the proteins of the Hox genes, are present in oocytes and preimplantation embryos in mammals. Their functions should be different from the zygotic ones and have not been studied to date. Our object is the errant annelid Platynereis dumerilii. This model is convenient for studying new functions and mechanisms of regulation of Hox genes, because it is incomparably simpler than laboratory vertebrates. Using a standard RT-PCR on cDNA template which was obtained by reverse transcription using random primers, we found that maternal transcripts of almost all Hox genes are present in unfertilized oocytes of worm. We assessed the localization of these transcripts using WMISH.

Mass spectral studies of lanthanide chelates. I. Samarium, europium, gadolinium and terbium chelates of thenoyltrifluoroacetone

The mass spectra of the lanthanide chelates of thenoyltrifluoroacetone, viz. Met{CF3COCH=C(O-)-C4H3S}3 (Met = Sm, Eu, Gd, Tb), have been obtained. All four spectra display similar fragmentation patterns. Fluorine migration to the metal with the concomitant loss of :CF2 occurs with all four lanthanide chelates. Peaks were observed for the ions [MetF2]+ (Met = Sm, Gd, Tb) and [MetF]+ (Met = Sm, Eu). The occurrence of [MetF]+ in the spectra of the samarium and europium chelates is in keeping with the tendency of these two lanthanides to be reduced to the bivalent state. On the other hand, oxidation of terbium(III) to terbium(IV) was not observed in the mass spectra.

Thio derivatives of β-Diketones and their metal chelates. XV. Mass spectra of cobalt(III) and rhodium(III) chelates of some fluorinated Monothio-β-diketones

The mass spectra of the cobalt(111) and rhodium(111) chelates of the fluorinated monothio-β-diketones RC(SH)=CHCOCF3 (R = Ph, p-MeC6H4, p-BrC6H4, p-FC6H4, and 2-thienyl) and of the cobalt(111) chelate of CH3C(SH)=CHCOCF3 have been obtained. The cobalt chelates do not give a peak for the molecular ion because of thermal degradation to the cobalt(11) complex CO(RCS=CHCOCF3)2, which then undergoes reactions in the mass spectrometer. Fluorine migration occurs with cobalt but not with rhodium. The cobalt complexes give rise to more metal-containing fragments than their rhodium analogues. Mechanisms are proposed for the reactions involving the metal-containing fragments. Cobalt undergoes valency changes to give cobalt(11) and cobalt(1) complex ions, whereas rhodium undergoes a valency change to the bivalent state only.