Circadian genomics of the chick pineal gland in vitro

<p>Abstract</p> <p>Background</p> <p>Chick pinealocytes exhibit all the characteristics of a complete circadian system, comprising photoreceptive inputs, molecular clockworks and an easily measured rhythmic output, melatonin biosynthesis. These properties make the <it>in vitro </it>pineal a particularly useful model for exploring circadian control of gene transcription in a pacemaker tissue, as well as regulation of the transcriptome by primary inputs to the clock (both photic and noradrenergic).</p> <p>Results</p> <p>We used microarray analysis to investigate the expression of approximately 8000 genes within cultured pinealocytes subjected to both LD and DD. We report that a reduced subset of genes was rhythmically expressed <it>in vitro </it>compared to those previously published <it>in vivo</it>, and that gene expression rhythms were lower in amplitude, although the functional distribution of the rhythmic transcriptome was largely similar. We also investigated the effects of 6-hour pulses of light or of norepinephrine on gene expression in free-running cultures during both subjective day and night. As expected, both light and norepinephrine inhibited melatonin production; however, the two treatments differentially enhanced or suppressed specific sets of genes in a fashion that was dependent upon time of day.</p> <p>Conclusion</p> <p>Our combined approach of utilizing a temporal, photic and pharmacological microarray experiment allowed us to identify novel genes linking clock input to clock function within the pineal. We identified approximately 30 rhythmic, light-responsive, NE-insensitive genes with no previously known clock function, which may play a role in circadian regulation of the pineal. These are candidates for future functional genomics experiments to elucidate their potential role in circadian physiology. Further, we hypothesize that the pineal circadian transcriptome is reduced but functionally conserved <it>in vitro</it>, and supports an endogenous role for the pineal in regulating local rhythms in metabolism, immune function, and other conserved pathways.</p

Bioconversion of possible T-2 toxin precursors by a mutant strain of Fusarium sporotrichioides NRRL 3299.

Liquid cultures of a mutant strain of Fusarium sporotrichioides NRRL 3299 that accumulates trichodiene rather than T-2 toxin converted tricho-9-ene-2 alpha,3 alpha,11 alpha-triol, trichotriol (tricho-10-ene-2 alpha,3 alpha,9 alpha-triol), tricho-10-ene-2 alpha,3 alpha,9 beta-triol, 3 alpha-hydroxytrichothecene, and 3 alpha-acetoxytrichothecene to T-2 toxin. Other possible oxygenated precursors of T-2 toxin, including trichodiol (tricho-10-ene-2 alpha,9 alpha-diol), trichothecene, 4 alpha-hydroxytrichothecene, and 15-hydroxytrichothecene, were not metabolized. The results indicate that in the biosynthesis of T-2 toxin by F. sporotrichioides, (i) oxygenation at C-3 occurs prior to the second cyclization, (ii) this second cyclization involves two steps that may be nonenzymatic, and (iii) oxidation at C-3 precedes that at C-4 or C-15