Phosphorites of the late Neoproterozoic (570 Ϯ 20 Myr BP) Doushantuo Formation, southern China, preserve an exceptional record of multicellular life from just before the Ediacaran radiation of macroscopic animals. Abundant thalli with cellular structures preserved in three-dimensional detail show that latest-Proterozoic algae already possessed many of the anatomical and reproductive features seen in the modern marine flora. Embryos preserved in early cleavage stages indicate that the divergence of lineages leading to bilaterians may have occurred well before their macroscopic traces or body fossils appear in the geological record. Discovery of these fossils shows that the early evolution of multicellular organisms is amenable to direct palaeontological inquiry.Most of the fossils that document the first 85% of evolutionary history are microscopic. Not until the Phanerozoic eon (Ͻ544 Myr BP) do the remains of large animals, algae and, later, plants become conspicuous constituents of the sedimentary record. The most important biological event that connects these palaeobiologically distinct eras is the evolution of complex multicellularity in eukaryotes. Multicellular organisms arose at least six times: in animals, fungi and several groups of algae 1 . Macroscopic remains of uncertain systematic affinities occur in rocks as old as 1,800-2,100 Myr BP 2 and cellularly preserved microfossils of red, green and stramenopile (brown and related) algae indicate that multicellularity was achieved in these groups by about 1,000 Myr 3 . Multicellularity may have evolved comparably early in minute ancestral animals, but until now any pre-Ediacaran animal history has been contentious and thought by many to be unrecognized and perhaps unrecognizable by palaeontologists.Phosphorites of the Doushantuo Formation in southern China contain three-dimensionally preserved fossils that record in exquisite Figure 1 Location and generalized stratigraphy of the fossiliferous Weng'an section in Guizhou Province, South China. The arrow indicates the principal stratigraphic horizon containing phosphatized algae and embryos. Fm, Formation.Figure 2 Algal thalli from the Doushantuo phosphorite and the modern bangiophyte red alga, Prophyra suborbiculata. a-c, Thalli from Doushantuo phosphorite. a, b, Scanning electron micrographs of a thallus composed of cuboidal cell packets similar to those of modern chlorosarcinacean green algae; b, the upper left quadrant of a at higher magnification. c, Photomicrograph of cruciate cell tetrads embedded in a foliose thallus; d, Carposporangia within the thallus of living Porphyra. Scale bar (in d): 200 m for a; 50 m for b; and 100 m for c and d.

Permineralized fossils of the terminal Proterozoic (600–550 Ma) Doushantuo Formation, China, provide an unusually clear window on biological diversity just before the Ediacaran radiation. In the eastern Yangtze Gorges region, cherts in lower and upper Doushantuo carbonates preserve prokaryotes and protists from subtidal marine environments below and above fair weather wave base, respectively. Phosphorites in the Weng'an district to the south contain diverse acanthomorphic acritarchs as well as cellularly preserved thalloid algae. Twelve taxa of probable cyanobacteria are recognized. None is endemic to the Doushantuo Formation, and most have long stratigraphic ranges. The apparent restriction of two species to late Neoproterozoic and Cambrian rocks may reflect secular variation in taphonomic circumstance rather than evolution. Thirty-one species of spheromorphic and acanthomorphic acritarchs are recognized, about half of which occur elsewhere in rocks of the same approximate age. At least some of the eight formally described species of multicellular algae can be assigned with confidence to the Rhodophyta; these fossils provide a glimpse of structural and reproductive diversity in Neoproterozoic algae that is, to date, unique. Several reports of Doushantuo animal fossils have been published; most compelling are triact spicules identified in chert nodules. Along with more than two dozen taxa of compressed macrofossils preserved in carbonaceous shales from the top of the formation, Doushantuo permineralizations indicate that large animals radiated into a world rich in prokaryotic, protistan, and, even, multicellular diversity.

The extent of gene regulation in cell differentiation is poorly understood. We previously used saturation mutagenesis to identify 18 genes that are needed for the development and function of a single type of sensory neuron--the touch receptor neuron for gentle touch in Caenorhabditis elegans. One of these genes, mec-3, encodes a transcription factor that controls touch receptor differentiation. By culturing and isolating wild-type and mec-3 mutant cells from embryos and applying their amplified RNA to DNA microarrays, here we have identified genes that are known to be expressed in touch receptors, a previously uncloned gene (mec-17) that is needed for maintaining touch receptor differentiation, and more than 50 previously unknown mec-3-dependent genes. These genes are randomly distributed in the genome and under-represented both for genes that are co-expressed in operons and for multiple members of gene families. Using regions 5' of the start codon of the first 20 genes, we have also identified an over-represented heptanucleotide, AATGCAT, that is needed for the expression of touch receptor genes.

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a b s t r a c tThis paper describes an immunomagnetic separation of target bacterial cells from others by using magnetic bead. The surface of bead was coated with antibodies which can capture specific organism. The binding efficiency of immunomagnetic bead (IMB) capturing target bacterial cells was higher than 98% when the concentrations of target and interferent bacterial cells were at the same level. The concentration of bacteria was determined indirectly by detecting adenosine 5 -triphosphate (ATP) employing bioluminescence (BL) reaction of firefly luciferin-ATP. Benzalkonium chloride (BAC) was used as an ATP extractant from living bacterial cells. We found that BAC could enhance the light emission when the concentration of BAC was less than 5.3 × 10 −2 % (w/v) and the BL intensity reached its maximum at the concentration of BAC was 2.7 × 10 −2 %, which was 10-fold stronger than that without BAC. Based on the principle of the IMB, a microfluidic chip combined with immunofluorescence assay for separating and detecting bacteria simultaneously was also developed. The IMBs were magnetically fixed in the beadbeds of chip channels with a 3-mm diameter of NdFeB permanent magnet. The target bacterial cells can be captured magnetically and observed by a fluorescent microscope.