Recent geochemical data from Oman, Newfoundland, and the western United States suggest that long-term oxidation of Ediacaran oceans resulted in progressive depletion of a large dissolved organic carbon (DOC) reservoir and potentially triggered the radiation of acanthomorphic acritarchs, algae, macroscopic Ediacara organisms, and, subsequently, motile bilaterian animals. However, the hypothesized coupling between ocean oxidation and evolution is contingent on the reliability of continuous geochemical and paleontological data in individual sections and of intercontinental correlations. Here we report high-resolution geochemical data from the fossil- acritarchs ͉ isotopes ͉ redox ͉ Neoproterozoic ͉ early animals T he Ediacaran (635-542 Ma) Earth witnessed profound changes in the aftermath of widespread and potentially global ice ages, including the evolution and radiation of complex megascopic life and major perturbations of the global carbon cycle that accompanied oxygenation of the deep ocean (1-9). These biological and environmental events have been speculatively linked, yet their temporal relationships have not been accurately documented in relatively continuous and fossil-rich sections that span a range of well-documented depositional settings. For example, geochemical data from siliciclasticdominated Ediacaran successions in Newfoundland (5) and the western United States (7) are incomplete, and those from the early Ediacaran interval in Oman (4) are of low stratigraphic resolution. Furthermore, paleontological data from these successions are limited to macroscopic Ediacara fossils and the biomineralizing animal Cloudina (10).To further test the proposed linkages between redox changes and biological evolution (4, 5), we carried out a high-resolution chemostratigraphic and biostratigraphic investigation of the fossiliferous Doushantuo Formation in the Yangtze Gorges area, South China. Our data reveal pulsed oxidation events that coincide with the origination and diversification of acanthomorphic acritarchs and other multicellular life forms in the basin. In combination with available data from other Ediacaran successions, our results indicate that oxidation of terminal Proterozoic oceans may have been episodic (4), with the final and permanent oxidation occurring Ϸ551 Ma. Sedimentological, Paleontological, and Geochemical DataThe Doushantuo Formation in the Yangtze Gorges area, constrained between 635.2 Ϯ 0.6 and 551.1 Ϯ 0.7 Ma (11), is divided into four lithostratigraphic members (Fig. 1). At the Jiulongwan section [supporting information (SI) Fig. 3], member I represents an Ϸ5-m-thick cap dolostone overlying the Nantuo glacial diamictite and contains a suite of enigmatic sedimentary structures and textures (12, 13). Member II is characterized by Ϸ70 m of alternating organic-rich shale and dolostone beds with abundant pea-sized chert nodules. Member III is Ϸ70 m thick and is composed of dolostone and bedded chert in the lower part that passes up-section into alternating limestone-dolostone ''ribbon rocks.'' Me...

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The predicted type-II band alignment and the interfacial polarized field in g-C3N4/MoS2 nanocomposite are responsible for its enhanced photocatalysis.

Apoptotic cell suicide initiated by ligation of CD95 (Fas/APO-1) occurs through recruitment, oligomerization and autocataly-

Although protein degradation is enhanced in muscle-wasting conditions and limits the rate of muscle growth in domestic animals, the proteolytic system responsible for degrading myofibrillar proteins in skeletal muscle is not well defined. The goals of this study were to evaluate the roles of the calpains (calcium-activated cysteine proteases) in mediating muscle protein degradation and the extent to which these proteases participate in protein turnover in muscle. Two strategies to regulate intracellular calpain activities were developed: overexpression of dominant-negative m-calpain and overexpression of calpastatin inhibitory domain. To express these constructs, L8 myoblast cell lines were transfected with LacSwitch plasmids, which allowed for isopropyl ␤-Dthiogalactoside-dependent expression of the gene of interest. Inhibition of calpain stabilized fodrin, a well characterized calpain substrate. Under conditions of accelerated degradation (serum withdrawal), inhibition of m-calpain reduced protein degradation by 30%, whereas calpastatin inhibitory domain expression reduced degradation by 63%. Inhibition of calpain also stabilized nebulin. These observations indicate that calpains play key roles in the disassembly of sarcomeric proteins. Inhibition of calpain activity may have therapeutic value in treatment of muscle-wasting conditions and may enhance muscle growth in domestic animals.

Mutations in the human CRALBP gene cause retinal pathology and delayed dark adaptation. Biochemical studies have not identified the primary physiological function of CRALBP. To resolve this, we generated and characterized mice with a non-functional CRALBP gene (Rlbp1(-/-) mice). The photosensitivity of Rlbp1(-/-) mice is normal but rhodopsin regeneration, 11-cis-retinal production, and dark adaptation after illumination are delayed by >10-fold. All-trans-retinyl esters accumulate during the delay indicating that isomerization of all-trans- to 11-cis-retinol is impaired. No evidence of photoreceptor degeneration was observed in animals raised in cyclic light/dark conditions for up to 1 year. Albino Rlbp(-/-) mice are protected from light damage relative to the wild type. These findings support a role for CRALBP as an acceptor of 11-cis-retinol in the isomerization reaction of the visual cycle.

The reduction of all-trans-retinal in photoreceptor outer segments is the first step in the regeneration of bleached visual pigments. We report here the cloning of a dehydrogenase, retSDR1, that belongs to the shortchain dehydrogenase/reductase superfamily and localizes predominantly in cone photoreceptors. retSDR1 expressed in insect cells displayed substrate specificities of the photoreceptor all-trans-retinol dehydrogenase. Homology modeling of retSDR1 using the carbonyl reductase structure as a scaffold predicted a classical Rossmann fold for the nucleotide binding, and an Nterminal extension that could facilitate binding of the enzyme to the cell membranes. The presence of retSDR1 in a subset of inner retinal neurons and in other tissues suggests that the enzyme may also be involved in retinol metabolism outside of photoreceptors.

We report a large and nonvolatile bipolar-electric-field-controlled magnetization at room temperature in a Co(40)Fe(40)B(20)/Pb(Mg(1/3)Nb(2/3))(0.7)Ti(0.3)O(3) structure, which exhibits an electric-field-controlled looplike magnetization. Investigations on the ferroelectric domains and crystal structures with in situ electric fields reveal that the effect is related to the combined action of 109° ferroelastic domain switching and the absence of magnetocrystalline anisotropy in Co(40)Fe(40)B(20). This work provides a route to realize large and nonvolatile magnetoelectric coupling at room temperature and is significant for applications.