Alu elements are primate-specific short interspersed elements (SINEs), over 1 million copies of which are present in the human genome; thus, Alu elements are useful targets for detecting human cells. However, previous Alu-based techniques for detecting human genomic DNA do not reach the theoretical limits of sensitivity and specificity. In this study, we developed a highly sensitive and specific Alu-based real-time PCR method for discriminating human cells from rodent cells, using a primer and probe set carefully designed to avoid possible cross-reactions with rodent genomes. From 100 ng of mixed human and rodent genomes, 1 fg of human genome, equivalent to 1 human cell in 100 million rodent cells, was detectable. Furthermore, in vivo mouse subrenal capsule xenotransplantation assays revealed that 10 human cells per mouse organ were detectable. In addition, after intravenous injection of human mesenchymal stem cells into NOD/SCID mice via tail vein, the biodistribution of human cells was trackable in the mouse lungs and kidneys for at least 1 week. Our findings indicate that our primer and probe set is applicable for the quantitative detection of tiny amounts of human cells, such as xenotransplanted human cancer or stem cells, in rodents.

The New York Consortium on Membrane Protein Structure (NYCOMPS) was formed to accelerate the acquisition of structural information on membrane proteins by applying a structural genomics approach. NY-COMPS comprises a bioinformatics group, a centralized facility operating a high-throughput cloning and screening pipeline, a set of associated wet labs that perform high-level protein production and structure determination by x-ray crystallography and NMR, and a set of investigators focused on methods development. In the first three years of operation, the NYCOMPS pipeline has so far produced and screened 7,250 expression constructs for 8,045 target proteins. Approximately 600 of these verified targets were scaled up to levels required for structural studies, so far yielding 24 membrane protein crystals. Here we describe the overall structure of NYCOMPS and provide details on the high-throughput pipeline.

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The raffinose family oligosaccharides (RFOs), such as raffinose and stachyose, are synthesized by a set of distinct galactosyltransferases, which sequentially add galactose units to sucrose. The accumulation of RFOs in plant cells are closely associated with the responses to environmental factors, such as cold, heat and drought stresses. Systematic analysis of genes involved in the raffinose metabolism has not been reported to date. Searching the recently available working draft of the maize genome, six kinds of enzyme genes were speculated, which should encode all the enzymes involved in the raffinose metabolism in maize. Expression patterns of some related putative genes were analyzed. The conserved domains and phylogenetic relationships among the deduced maize proteins and their homologs isolated from other plant species were revealed. It was discovered that some of the key enzymes, such as galactinol synthase (ZmGolS5, ZmGolS45 and ZmGolS37), raffinose synthase (ZmRS1, ZmRS2, ZmRS3 and ZmRS10), stachyose synthase (ZmRS8) and β-fructofuranosidase, are encoded by multiple gene members with different expression patterns. These results reveal the complexity of the raffinose metabolism and the existence of metabolic channels for diverse RFOs in maize and provide useful information for improving maize stress tolerance through genetic engineering.