We studied a novel function of the presenilins (PS1 and PS2) in governing capacitative calcium entry (CCE), a refilling mechanism for depleted intracellular calcium stores. Abrogation of functional PS1, by either knocking out PS1 or expressing inactive PS1, markedly potentiated CCE, suggesting a role for PS1 in the modulation of CCE. In contrast, familial Alzheimer's disease (FAD)-linked mutant PS1 or PS2 significantly attenuated CCE and store depletion-activated currents. While inhibition of CCE selectively increased the amyloidogenic amyloid beta peptide (Abeta42), increased accumulation of the peptide had no effect on CCE. Thus, reduced CCE is most likely an early cellular event leading to increased Abeta42 generation associated with FAD mutant presenilins. Our data indicate that the CCE pathway is a novel therapeutic target for Alzheimer's disease.

Ocean acidification in nitrogen-enriched estuaries has raised global concerns. For decades, biotic and abiotic denitrification in estuarine sediments has been regarded as the major ways to remove reactive nitrogen, but they occur at the expense of releasing greenhouse gas nitrous oxide (N 2 O). However, how these pathways respond to acidification remains poorly understood. Here we performed a N 2 O isotopocules analysis coupled with respiration inhibition and molecular approaches to investigate the impacts of acidification on bacterial, fungal, and chemo-denitrification, as well as N 2 O emission, in estuarine sediments through a series of anoxic incubations.Results showed that acidification stimulated N 2 O release from sediments, which was mainly mediated by the activity of bacterial denitrifiers, whereas in neutral environments, N 2 O production was dominated by fungi. We also found that the contribution of chemo-denitrification to N 2 O production cannot be ignored, but was not significantly affected by acidification. The mechanistic investigation further demonstrated that acidification changed the keystone taxa of sedimentary denitrifiers from N 2 Oreducing to N 2 O-producing ones and reduced microbial electron-transfer efficiency during denitrification. These findings provide novel insights into how acidification stimulates N 2 O emission and modulates its pathways in estuarine sediments, and how it may contribute to the acceleration of global climate change in the Anthropocene.

Phenolic acids and tanshinones are two major bioactive components in Salvia miltiorrhiza Bunge. A novel endogenous R2R3-MYB transcription factor, SmMYB36, was identified in this research. This transcript factor can simultaneously influence the content of two types of components in SmMYB36 overexpression hairy roots. SmMYB36 was mainly localized in the nucleus of onion epidermis and it has transactivation activity. The overexpression of SmMYB36 promoted tanshinone accumulation but inhibited phenolic acid and flavonoid biosynthesis in Salvia miltiorrhiza hairy roots. The altered metabolite content was due to changed metabolic flow which was regulated by transcript expression of metabolic pathway genes. The gene transcription levels of the phenylpropanoid general pathway, tyrosine derived pathway, methylerythritol phosphate pathway and downstream tanshinone biosynthetic pathway changed significantly due to the overexpression of SmMYB36. The wide distribution of MYB binding elements (MBS, MRE, MBSI and MBSII) and electrophoretic mobility shift assay results indicated that SmMYB36 may be an effective tool to regulate metabolic flux shifts.

Jasmonates (JAs) are important plant hormones that regulate a variety of plant development and defense processes, including biosynthesis of secondary metabolites. The JASMONATE ZIM DOMAIN (JAZ) proteins act as negative regulators in the JA signaling pathways of plants. We first verified that methyl jasmonate (MeJA) enhanced the accumulation of both salvianolic acids and tanshinones in Salvia miltiorrhiza (Danshen) hairy roots by inducing the expression of their biosynthetic pathway genes. Nine JAZ genes were cloned from Danshen and their expression levels in hairy roots were all increased by treatment with MeJA. When analyzed in detail, however, SmJAZ8 showed the strongest expression in the induced hairy roots. Overexpression or RNAi of SmJAZ8 deregulated or up-regulated the yields of salvianolic acids and tanshinones in the MeJA-induced transgenic hairy roots, respectively, and transcription factors and biosynthetic pathway genes showed an expression pattern that mirrored the production of the compounds. Genetic transformation of SmJAZ8 altered the expression of other SmJAZ genes, suggesting evidence of crosstalk occurring in JAZ-regulated secondary metabolism. Furthermore, the transcriptome analysis revealed a primary-secondary metabolism balance regulated by SmJAZ8. Altogether, we propose a novel role for SmJAZ8 as a negative feedback loop controller in the JA-induced biosynthesis of salvianolic acids and tanshinones.

A subset of early-onset familial Alzheimer's disease (FAD) 1 is inherited as an autosomal dominant trait, and presenilin (PS) 1 and 2 genes in addition to ß-amyloid precursor protein (APP) gene were identified as the causative genes. PS1 is mapped to chromosome 14 (1,2), while PS2 is mapped to chromosome 1 (3-5). These PS1 and PS2 genes encode multispanned transmembrane proteins showing high degrees of homology (4,5).Both proteins are located predominantly in the endoplasmic reticulum (ER), and partly in the Golgi apparatus and other compartments (6-8), but their physiological functions remain unclear. More than 50 different mutations have thus far been identified in PS1 (9), while only two mutations have been found in PS2 (10). The residue at position 141 (Asn) in PS2, which is conserved in human and mouse PS1 and PS2, is substituted by Ile (N141I) in the Volga German kindred. Another missense mutation (M239V) in PS2 has been found in Italian FAD families (5).Although the pathogenetic mechanism how Alzheimer's disease (AD) is developed by PS mutations remains unknown, mutations of PS1 and PS2 are known to have similar effects on the production of amyloid ß-protein (Aß) 42, the initially deposited Aß species in senile plaques (11)(12)(13)(14): While Aß42 is normally secreted in much lower quantities than Aß40, these aforementioned mutations induce elevation of the Aß42 levels in cultured cells and transgenic mice (15)(16)(17)(18)(19)(20). It has also been reported that in primary neuronal cultures derived from PS1-knockout mouse embryos, Aß secretion was remarkably decreased, concomitant with the accumulation of the C-terminal fragment of APP (21). The mutation in the two particular Asp residues in the PS1-transmembrane domains induced a profound decrease in the Aß production and an increase in the levels of the C-terminal fragment of APP (22). These observations indicate that PS1 may have a direct or indirect role in the γ -cleavage of APP.We previously reported that the mutant PS2 transgenic mice showed increases in the Aß42 levels in the Tris-saline (TS)-soluble fractions in an age-dependent manner during 2 to 8 months of age (20). On the other hand, a series of Aß quantitation studies of autopsied human tissues has clearly shown that Aß42 already accumulates to a significant extent in the TS- In the present study, we sought to obtain further insight into the effects of mutant PS2on the Aß levels in the TS-insoluble, guanidine hydrochloride-solubilized fraction of the mouse brain, and to characterize the intracellular compartmentalization of insoluble Aß. EXPERIMENTAL PROCEDURESTransgenic mice -The heterozygous PS2 transgenic mice used in this study were from the previously established lines W2 (wild-type PS2 transgenic mice), and M1 and M2(N141I mutant PS2 transgenic mice) (20). Each line of transgenic mice was backcrossed to the C57BL/6J strain, and those mice carrying the PS2 transgene were selected using a transgene-specific PCR assay (20). Littermates without PS2 transgenes were used as the nontransge...

Inorganic phosphate solubilizing bacteria (iPSB) are essential to facilitate phosphorus (P) mobilization in alkaline soil, however, the phylogenetic structure of iPSB communities remains poorly characterized. Thus, we use a reference iPSB database to analyze the distribution of iPSB communities based on 16S rRNA gene illumina sequencing. Additionally, a noval pqqC primer was developed to quantify iPSB abundance. In our study, an alkaline soil with 27-year fertilization treatment was selected. The percentage of iPSB was 1.10~2.87% per sample, and the dominant iPSB genera were closely related to Arthrobacter, Bacillus, Brevibacterium and Streptomyces. Long-term P fertilization had no significant effect on the abundance of iPSB communities. Rather than P and potassium (K) additions, long-term nitrogen (N) fertilization decreased the iPSB abundance, which was validated by reduced relative abundance of pqqC gene (pqqC/16S). The decreased iPSB abundance was strongly related to pH decline and total N increase, revealing that the long-term N additions may cause pH decline and subsequent P releases relatively decreasing the demands of the iPSB community. The methodology and understanding obtained here provides insights into the ecology of inorganic P solubilizers and how to manipulate for better P use efficiency.

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