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Background To adapt the periodic fluctuation of environmental factors, plants are subtle to monitor the natural variation for the growth and development. The daily activities and physiological functions in coordination with the natural variation are regulated by circadian clock genes. The circadian emission of floral scents is one of the rhythmic physiological activities controlled by circadian clock genes. Here, we study the molecular mechanism of circadian emission pattern of ocimene and linalool compounds in Oncidium Sharry Baby (Onc. SB) orchid. Results GC-Mass analysis revealed that Onc. SB periodically emitted ocimene and linalool during 6 to 14 o’clock daily. Terpene synthase, one of the key gene in the terpenoid biosynthetic pathway is expressed in coordination with scent emission. The promoter structure of terpene synthase revealed a circadian binding sequence (CBS), 5’-AGATTTTT-3’ for CIRCADIAN CLOCK ASSOCIATED1 (CCA1) transcription factor. EMSA data confirms the binding affinity of CCA1. Transactivation assay further verified that TPS expression is regulated by CCA1. It suggests that the emission of floral scents is controlled by CCA1. Conclusions The work validates that the mechanism of circadian emission of floral scents in Onc. Sharry Baby is controlled by the oscillator gene, CCA1(CIRCADIAN CLOCK ASSOCIATED 1) under light condition. CCA1 transcription factor up-regulates terpene synthase (TPS) by binding on CBS motif, 5’-AGATTTTT-3’ of promoter region to affect the circadian emission of floral scents in Onc. SB.

Cytokine splice variants generated from alternative splicing of pre-mRNA have been broadly described and are implicated to influence cytokine signaling. Nonetheless, their importance in regulating the immune response remains unclear. The ENU-mutagenized pedigree 191 (P191) generated by the Mouse Mutagenesis Program Core Facility funded by the National Science Council was characterized by its depressed expression of CD44 on CD8 T cells. The mutant gene was linked to chromosome 8 and was mapped to IL-15 mRNA. Infection of P191 mutant mice with HSV-1 via flank skin revealed insufficient control of zosteriform as results of severe and delayed pathological manifestations, increased viral yields and lacking of Gr1+ cell recruitment to the lesional site. Whereas antigen specific CD8 T cells were generated in P191 mutant mice after HSV-1 infection detected with MHC class I tetramer in complex with HSV-1 gB498-505 epitope by flow cytometric analysis, the number was declined later time as opposed to be accumulated as generated in the wild type mice. These results have suggested that expression of IL-15 alternative splice variant could not only have effect ongenerating effective innate immune response in skin but also affect the function and maintenance of CD8 memory cells against HSV-1 infection. However, how the IL-15 splice variant modulates these immune mechanism remains to be clarified.

Background: To adapt the periodic fluctuation of environmental factors, plants are subtle to monitor the natural variation for the growth and development. It is well known that the daily activities and physiological functions in coordination with the natural variation are regulated by circadian clock genes. The circadian emission of floral scents is one of the rhythmic physiological activity controlled by circadian clock genes. Here, we study the circadian emission pattern and molecular mechanism of floral terpenoids compounds (ocimene/linalool) in Oncidium Sharry Baby (Onc. SB) orchid, which were diurnally emitted under light condition. Results: GC-Mass analysis revealed that Onc. SB periodically emitted ocimene and linalool during 6:00AM to 2:00PM daily. Terpene synthase, one of the key gene in the terpenoid biosynthetic pathway is expressed in coordination with scent emission. Investigation on the promoter structure of terpene synthase revealed a circadian binding site (CBS), 5’-AGATTTTT-3’ for the binding motif of CIRCADIAN CLOCK ASSOCIATED1 (CCA1) transcription factor. EMSA data performed confirms the binding affinity between CCA1 protein and CBS of cis-acting DNA element. It suggests that the diurnal circadian emission of floral scent is controlled by CCA1.Conclusions: The work validates that the mechanism of circadian emission of floral scents in Onc. SB is controlled by the oscillator gene, CCA1(CIRCADIAN CLOCK ASSOCIATED 1) under light condition. CCA1 transcription factor regulates terpene synthase (TPS) by direct binding on CBS motif, 5’-AGATTTTT-3’ of promoter region. The circadian expression of TPS is the key gene to affect the biosynthesis and emission of floral scent in Onc. Sharry Baby.

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