In macronuclear DNA of the ciliated protozoan Paramecium caudatum, we identified a gene homologous to aubergine/piwi in Drosophila and ZWILLE in Arabidopsis, which have recently been shown to regulate the maintenance of stem cell in animals and plants. The DNA sequence was considered to be actually transcribed because it was also obtained from cDNA of vegetative phase cells by RACE-PCR. The gene named pap (Paramecium aubergine/piwi homologue) encodes 781 amino acids and contains three short introns (21bp, 22bp and 23bp) in the ORF. Forty four UAA colons and 8 UAG colons which code for glutamine in Paramecium were found in the ORF. This is the first finding of piwi/ZWILLE homologue in a protozoan. The gene was transcribed actively immediately after induction of conjugation, while the transcription was restricted amount during vegetative phase. The result suggests that the gene is integrated in the developmental process of conjugation.
Sialic acid-conjugated cholesterols (SC) with different spacer lengths were synthesized as ganglioside analogs. The interaction of SC (12mol%)-containing liposomes with rat lymphocyte cells was investigated by monitoring increases in the intracellular calcium signal under a confocal fluorescence microscopy. Cells were stimulated strongly in the presence of SC-containing liposomes, while free SC not reconstituted to liposomes did not significantly stimulate the cells. The reconstitution of sialolipids to liposomes play a crucial role in the stimulation of cells. The efficiency of SC-containing liposomes was comparable to that of the naturally occurring gangliosides, GT1b-containing liposomes.
Capsaicin receptor (vanilloid receptor 1, VR1), a cation channel, has been recently cloned and shown to be expressed in a subset of sensory neurons (Caterina et al., 1997, Nature 389, 816-824). To examine the distribution of VR1 on the protein level in the whole body, we produced an antiserum against bacterially expressed VR1. Immunoblot analysis revealed that VR1 was expressed in not only nervous tissues including brain but tongue, esophagus, diaphragm, and leg muscle. In these tissues, VRl mRNA was also expressed (confirmed by RT-PCR). The significance of the expression in these muscles was discussed.
GC-MS analysis of the preputial gland extracts of lesser bandicoot rat revealed that nine major components are present in both male and female. The antibiotic compound, erythromycin derivative, was also identified as a major fraction irrespective of male and female. The presence of erythromycin derivative suggests that the antibiotic may be secreted from a symbiant bacterium and served as a naturally occurring medicine which protect the rats against the pathogens.