Arabidopsis and rice are the only two model plants whose finished phase genome sequence has been completed. Here we report the construction of an oligomer microarray based on the presently known and predicted gene models in the rice genome. This microarray was used to analyze the transcriptional activity of the gene models in representative rice organ types. Expression of 86% of the 41,754 known and predicted gene models was detected. A significant fraction of these expressed gene models are organized into chromosomal regions, about 100 kb in length, that exhibit a coexpression pattern. Compared with similar genome-wide surveys of the Arabidopsis transcriptome, our results indicate that similar proportions of the two genomes are expressed in their corresponding organ types. A large percentage of the rice gene models that lack significant Arabidopsis homologs are expressed. Furthermore, the expression patterns of rice and Arabidopsis best-matched homologous genes in distinct functional groups indicate dramatic differences in their degree of conservation between the two species. Thus, this initial comparative analysis reveals some basic similarities and differences between the Arabidopsis and rice transcriptomes.

We have mapped the autosomal sex reversal locus, SRA1, associated with campomelic dysplasia (CMPD1) to 17q24.3-q25.1 by three independent apparently balanced de novo reciprocal translocations. Chromosome painting indicates that the translocated segment of 17q involves about 15% of chromosome 17 in all three translocations, corresponding to a breakpoint at the interphase between 17q24-q25. All three 17q breakpoints were localized distal to the growth hormone locus (GH), and proximal to thymidine kinase (TK1). Due to the distal location of the breakpoints, previously mentioned candidate genes, HOX2 and COL1A1, can be excluded as being involved in CMPD1/SRA1. The mouse mutant tail-short (Ts) which maps to the homologous syntenic region on mouse chromosome 11, displays some of the features of CMPD1.

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Zinc salt-based fixation (ZBF) has proved advantageous in histochemical analyses conducted on intact tissues but has not been exploited in flow cytometry procedures that focus on quantitative analysis of individual cells. Here, we show that ZBF performs equally well to paraformaldehyde in the preservation of surface epitope labeling and forward and side scatter parameters as measured by flow cytometry. ZBF-fixed mouse epithelial keratinocytes exhibit a staining pattern for the surface markers Sca-1, CD34 and a6 integrin that is highly analogous to live cells. Furthermore, ZBF also preserves DNA allowing subsequent quantitative PCR analysis or labeling for incorporation of the thymidine analog EdU following surface and intracellular epitope staining. Finally, ZBF treatment allows for long-term storage of labeled cells with little change in these parameters. Thus, we present a protocol for zinc salt fixation of cells that allows for the simultaneous analysis of DNA and intracellular and cell surface proteins by flow cytometry. ' 2010 International Society for Advancement of Cytometry Key terms stem cell markers; EdU; DNA quantification; long-term storage THE main purpose of chemical fixation is to preserve tissue and subcellular architecture thereby facilitating immunohistochemical detection of epitopes and histochemical detection of chemical substances within cells. Formaldehyde-based fixatives fulfill this requirement to a large extent and have been the preferred compounds for decades in standard pathology procedures. However, a growing demand has emerged for enhanced preservation of proteins and other cellular molecules such as DNA and RNA. In particular, formaldehyde fixation can fragment genomic DNA and hinder quantitative analysis of nucleic acids and generally prohibits PCR amplification of DNA fragments longer than a few hundred base pairs (1). Besides the deleterious effects on DNA, formaldehyde cross-linking alters the tertiary and quaternary structure of proteins and may also mask the secondary structure of globular proteins. Consequently, this can diminish the availability of cellular epitopes to the detriment of immunological-based assays (2). Finally, most formaldehyde fixatives are hazardous and suspected carcinogens, which makes their use dependent on working under a fume hood.As an alternative to formaldehyde-based fixation, zinc salt-based fixation (ZBF), which does not contain any cross-linking agents, is also effective in histopathology procedures (3-6). In fact, studies have shown that RNA, DNA, and proteins are preserved better in ZBF than in neutral buffered formalin (5,6). Furthermore, it was shown that the morphological preservation was comparable to aldehyde-based fixation. Recently, it has been shown that enzymes retain their activity in ZBF-fixed tissue enabling analysis of enzymatic activity in tissue sections (7). However, the use of ZBF has not received a

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