To provide a broad analysis of gene expression in developing Arabidopsis seeds, microarrays have been produced that display approximately 2,600 seed-expressed genes. DNA for genes spotted on the arrays were selected from Ͼ10,000 clones partially sequenced from a cDNA library of developing seeds. Based on a series of controls, sensitivity of the arrays was estimated at one to two copies of mRNA per cell and cross hybridization was estimated to occur if closely related genes have Ͼ70% to 80% sequence identity. These arrays have been hybridized in a series of experiments with probes derived from seeds, leaves, and roots of Arabidopsis. Analysis of expression ratios between the different tissues has allowed the tissue-specific expression patterns of many hundreds of genes to be described for the first time. Approximately 25% of the 2,600 genes were expressed at ratios Ն 2-fold higher in seeds than leaves or roots and 10% at ratios Ն 10. Included in this list are a large number of proteins of unknown function, and potential regulatory factors such as protein kinases, phosphatases, and transcription factors. The Arabidopsis arrays were also found to be useful for transcriptional profiling of mRNA isolated from developing oilseed rape (Brassica napus) seeds and expression patterns correlated well between the two species.

Large-scale single-pass sequencing of cDNAs from different plants has provided an extensive reservoir for the cloning of genes, the evaluation of tissue-specific gene expression, markers for map-based cloning, and the annotation of genomic sequences. Although as of January 2000 GenBank contained over 220,000 entries of expressed sequence tags (ESTs) from plants, most publicly available plant ESTs are derived from vegetative tissues and relatively few ESTs are specifically derived from developing seeds. However, important morphogenetic processes are exclusively associated with seed and embryo development and the metabolism of seeds is tailored toward the accumulation of economically valuable storage compounds such as oil. Here we describe a new set of ESTs from Arabidopsis, which has been derived from 5- to 13-d-old immature seeds. Close to 28,000 cDNAs have been screened by DNA/DNA hybridization and approximately 10,500 new Arabidopsis ESTs have been generated and analyzed using different bioinformatics tools. Approximately 40% of the ESTs currently have no match in dbEST, suggesting many represent mRNAs derived from genes that are specifically expressed in seeds. Although these data can be mined with many different biological questions in mind, this study emphasizes the import of photosynthate into developing embryos, its conversion into seed oil, and the regulation of this pathway.

I882.] Flowers of Sobacnv;um rostratzum casd Cassia clauwcecrista. 28I fidence that no representative of an exclusively exotic fauna figured in the pipe-sculptures of the mound-builders. If we accept the presence of the mammoth or mastodon amongst these carvings, the species which served as models, though now extinct, must be classed with our indigenous fauna. Their knowledge of such animals as the parroquet, the manatus, and possibly the seal and Rocky mountain sheep, does not necessarily indicate any particular migration on the part of that ancient people, but serves to show that their intercourse and commercial relations with other peoples were extensive. As has been previously remarked, however, the artists were apparently well acquainted with some of the birds, mammals and amphibia whose geographical limits were far removed from the upper portion of the Mississippi valley, but which, nevertheless, might have been met with by some of the people in their expeditions. On the other hand, many of the representations were evidently executed from descriptions or rude delineations furnished by those who had seen the originals. The mounds have produced galena from Missouri and the adjacent territory; mica from the spurs of the Allegh any or Rocky mountains; Catlinite from Minnesota; copper from the Lake Superior region; obsidian from Mexico and the Pacific slope of the United States, and marine shells from the Gulf of Mexico, the Atlantic ocean, and also the Dentaliumr of the Pacific coast.-Thus it will be seen that the trade relations of the mound-builders extended over a great extent of territory, in fact, covering the greater portion of the present United States and probably penetrating into British America and Mexico.

The soil fungi Mortierella pusilla, M. isabellina, and Trichoderma viride, and the aquatic fungus Saprolegnia parasitica were chosen as test organisms to study the fungitoxicity of the pesticides methoxychlor and fenitrothion and some of their known metabolites and derivatives. The inhibition of mycelial growth on agar plates was used as a criterion for toxicity and it was established that the inhibiting effect was fungistatic rather than fungicidal. The results, which indicate that some metabolites are more toxic than the parent pesticides, are reported in the form of dosage response relationships and a novel method of reporting such relationships is proposed.

No abstract