Increasing numbers of sense-antisense transcripts (SATs), which are transcribed from the same chromosomal location but in opposite directions, have been identified in various eukaryotic species, but the biological meanings of most SATs remain unclear. To improve understanding of natural sense-antisense transcription, we performed comparative expression profiling of SATs conserved among humans and mice. Using custom oligo-arrays loaded with probes that represented SATs with both protein-coding and non-protein-coding transcripts, we showed that 33% of the 291 conserved SATs displayed identical expression patterns in the two species. Among these SATs, expressional balance inversion of sense-antisense genes was mostly observed in testis at a tissue-specific manner. Northern analyses of the individual conserved SAT loci revealed that: (i) a smeary hybridization pattern was present in mice, but not in humans, and (2) small RNAs (about 60 to 80 nt) were detected from the exon-overlapping regions of SAT loci. In addition, further analyses showed marked alteration of sense-antisense expression balance throughout spermatogenesis in testis. These results suggest that conserved SAT loci are rich in potential regulatory roles that will help us understand this new class of transcripts underlying the mammalian genome.

SummaryAnthocyanin acyltransferases (AATs) catalyze a regiospeci®c acyl transfer from acyl-CoA to the glycosyl moiety of anthocyanins, thus playing an important role in¯ower coloration. The known AATs are subfamily members of an acyltransferase family, the BAHD family, which play important roles in secondary metabolism in plants. Here, we describe the puri®cation, characterization, and cDNA cloning of a novel anthocyanin malonyltransferase from scarlet sage (Salvia splendens)¯owers. The puri®ed enzyme (hereafter referred to as Ss5MaT2) is a monomeric 46-kDa protein that catalyzes the transfer of the malonyl group from malonyl-CoA to the 4 HHH -hydroxyl group of the 5-glucosyl moiety of anthocyanins. Thus, it is a malonylCoA:anthocyanin 5-glucoside 4HHH -O-malonyltransferase. On the basis of the partial amino acid sequences of the puri®ed enzyme, we isolated a cDNA that encodes an acyltransferase protein. The steady-state transcript level of the gene was the highest in recently opened, fully pigmented¯owers and was also correlated with the trend observed for an AAT gene responsible for the ®rst malonylation step during salvianin biosynthesis. Immunoprecipitation studies using antibodies against the recombinant acyltransferase protein corroborated the identity of this cDNA as that encoding Ss5MaT2. The deduced amino acid sequence of Ss5MaT2 showed a low similarity (22±24% identity) to those of AATs and lacked the AAT-speci®c signature sequence. A phylogenetic analysis suggested that Ss5MaT2 is more related to acetyl-CoA:benzylalcohol acetyltransferase (BEAT) rather than to AAT. This is another example in which enzymes with similar, although not identical, substrate evolved from different branches of the BAHD family.

The plastid genome of higher plants includes about 120 genes. We adopted genomic array technologies to the tobacco plastid genome. A microarray was constructed, consisting of 220 DNA fragments that cover the whole genome sequence. Each DNA fragment corresponds to a single known gene or an intergenic region. We evaluated reliability of this microarray by comparing the plastid RNA level in light- or dark-grown tobacco seedlings. The transcripts encoding photosynthetic subunits increased significantly in light-grown tissues as expected. Furthermore, we found unexpected signals in several intergenic regions, suggesting the existence of novel transcripts in tobacco plastids.

M: Bilirubin pigmentation of human teeth caused by hyperbilirubinemia. J Oral Pathol Med 1999; 28: 128-30. C Munksgaard, 1999.This study was conducted to identify bilirubin in deciduous teeth obtained from two patients with a history of severe liver dysfunction. Teeth were histologically

Background: Recent transcriptomic analyses in mammals have uncovered the widespread occurrence of endogenous antisense transcripts, termed natural antisense transcripts (NATs). NATs are transcribed from the opposite strand of the gene locus and are thought to control sense gene expression, but the mechanism of such regulation is as yet unknown. Although several thousand potential sense-antisense pairs have been identified in mammals, examples of functionally characterized NATs remain limited. To identify NAT candidates suitable for further functional analyses, we performed DNA microarray-based NAT screening using mouse adult normal tissues and mammary tumors to target not only the sense orientation but also the complementary strand of the annotated genes.