Stable suppression of nitrite oxidizing bacteria (NOB) is one of the major bottlenecks for achieving mainstream nitrite shunt or partial nitritation/anammox (PN/A). It is increasingly experienced that NOB could develop resistance to suppressions over an extended time, leading to failure of nitrite shunt or PN/A. This study reports and demonstrates the first effective strategy to overcome NOB adaptation through alternating sludge treatment with free nitrous acid (FNA) and free ammonia (FA). During over 650 days reactor operation, NOB adaptation to both FNA and FA was observed but the adaptation was successfully overcome by deploying the alternate treatment strategy. Microbial community analysis showed Nitrospira and Nitrobacter, the key NOB populations in the reactor, have the ability to adapt to FNA and FA, respectively, but do not adapt to the alternation. Stable nitrite shunt with nitrite accumulation ratio over 95% and excellent nitrogen removal was maintained for the last 8 months with only one alternation applied. N2O emission increased initially as the attainment of nitrite shunt but exhibited a declining trend during the study. By using onsite-produced nitrite and ammonium, the proposed strategy is feasible and sustainable. This study brings the mainstream nitrite shunt and PN/A one step closer to wide applications.

Stem cell factor (SCF) is a powerful chemokine that binds to the c-Kit receptor CD117 and has shown promise as a homing agent capable of progenitor cell recruitment. In the present study we have documented high levels of both SCF and its receptor c-Kit in differentiating dental pulp (DP) cells and in the sub-odontoblastic layer of Höhl. In vitro studies using human DP progenitors revealed a significant increase in cell proliferation after100nM SCF application, explained by a 2-fold upregulation in cyclin D3 and FGF2 cell cycle regulators, and a 7-fold increase in CDK4 expression. DP cell migration in the presence of SCF was up-regulated 2.7-fold after a 24 hour culture period, and this effect was accompanied by cytoskeletal rearrangement, a 1.5-fold increase in polymeric F-actin over G-actin, and a 1.8-fold increase in RhoA expression. Explaining the signaling effect of SCF on DP migration, PI3K/Akt and MEK/ERK pathway inhibitors were demonstrated to significantly reduce DP cell migration, while SCF alone doubled the number of migrated cells. ERK and AKT phosphorylation were dramatically upregulated already 3-5 minutes after SCF addition to the culture medium and declined thereafter, classifying SCF as a fast acting chemokine. When applied as an agent to promote tissue regeneration in subcutaneously implanted collagen sponges, SCF resulted in a 7-fold increase in the cell number in the implanted tissue construct, a more than 9-fold increase in capillaries, as well as collagen sponge remodeling and collagen fiber neogenesis. Together, these studies demonstrate the suitability of SCF as a potent aid in the regeneration of dental pulp and other mesenchymal tissues, capable of inducing cell homing, angiogenesis, and tissue remodeling.

4.4 The FNA-based applications are feasible and economically viable in wastewater treatment systems .

Enamel-related gene products (ERPs) are detected in non-enamel tissues such as bone. We hypothesized that, if functional, ERP expression corresponds with distinct events during osteoblast differentiation and affects bone development and mineralization. In mouse calvariae and MC3T3 cells, expression profiles of enamel-related gene products (ERPs) correlated with key events in post-natal calvarial development and MC3T3 cell mineralization. Developing skulls from both Amel-and Ambndeficient animals were approximately 15% shorter when compared with those of wild-type controls, and their sutures remained patent for a longer period of time. Analysis of Amel-and Ambn-deficient calvariae and calvarial osteoblast cultures revealed a dramatic reduction in mineralized nodules, a significant reduction in Runx2, Sp7, Ibsp, and Msx2 expression, and a reduction in Alx4 in Amel-deficient calvariae vs. an increase in Alx4 in Ambn-deficient calvariae. Analysis of these data indicates that ERP expression follows defined developmental profiles and affects osteoblast differentiation, mineralization, and calvarial bone development. We propose that, in parallel to their role in the developing enamel matrix, ERPs have retained an evolutionary conserved function related to the biomineralization of bones.KEY WORDS: amelogenin, ameloblastin, osteoblast, calvaria, evolution, suture. A supplemental appendix to this article is published electronically only at http://jdr.sagepub.com/supplemental.

Inflammatory conditions as they occur during periodontal disease often result in decreased alveolar bone levels and a loss of connective tissue homeostasis. Here we have focused on the effect of microRNA-138 (miR-138) as a potential regulator of periodontal stem cells as they affect homeostasis during inflammatory conditions. Our data indicate that miR-138 was significantly upregulated in our periodontal disease animal model. Interaction of miR-138 with a predicted targeting site on the osteocalcin (OC) promoter resulted in a 3.7-fold reduction of luciferase activity in promoter assays compared with controls; and miR-138 overexpression in periodontal progenitors significantly inhibited OC (3.4-fold), Runx2 (2.8-fold), and collagen I (2.6-fold). Moreover, treatment with inflammatory modulators such as interleukin (IL)-6 and lipopolysaccharide (LPS) resulted in a significant 2.2-fold (IL-6) or 1.9-fold (LPS) increase in miR-138 expression, while OC and Runx2 expression was significantly decreased as a result of treatment with each inflammatory mediator. Further defining the role of miR-138 in the OC-mediated control of mineralization, we demonstrated that the LPS-induced downregulation of OC expression was partially reversed after miR-138 knockdown. LPS, miR-138 mimic, and OC small interfering RNA inhibited osteoblast differentiation marker alkaline phosphatase activity, while miR-138 inhibitor and OC protein addition enhanced alkaline phosphatase activity. Supporting the role of OC as an essential modulator of osteoblast differentiation, knockdown of miR-138 or addition of OC protein partially rescued alkaline phosphatase activity in periodontal ligament (PDL) cells subjected to LPS treatment. Our data establish miR-138 inhibitor as a potential therapeutic agent for the prevention of the bone loss associated with advanced periodontal disease.

We report U isotope data for marine black shales of the early Mesoproterozoic Velkerri Formation (Roper Group) and late Paleoproterozoic Wollogorang Formation (Tawallah Group) from the McArthur Basin, Northern Australia. An average authigenic δ 238 U of 0.13 ± 0.04‰ (1SD; relative to standard CRM145) was obtained for six U-and Mo-rich shales from a ~ 1 m interval that was deposited at 1361 ± 21 Ma (based on previous Re-Os geochronology). After correcting for a local U isotope fractionation of ~0.60-0.85‰ associated with U removal to anoxic sediments, we infer that global seawater at 1.36 Ga had a δ 238 U of ~ -0.47‰ to -0.72‰, which is ~0.1-0.3‰ lighter than modern seawater (-0.39 ± 0.01‰). Uranium isotope mass-balance modelling suggests that <25% of the seafloor was anoxic at 1.36 Ga. This interpretation is consistent with high U and Mo enrichments in these samples compared with other Velkerri Formation and mid-Proterozoic black shales, which suggests a sizable dissolved oceanic Mo and U inventory developed in response to an episode of increased ocean oxygenation. Hence, a significant expanse of O 2 -bearing deep ocean waters may have existed at 1.36 Ga. The O 2 concentrations of those waters were not necessarily high given that a large expanse of weakly oxygenated deep waters is also consistent with the mass-balance model. A lower average authigenic δ 238 U of -0.08 ± 0.18‰ (1SD) was obtained for less U-and Mo-rich black shales from a ~1 m interval in the lower Velkerri Formation, deposited at 1417 ± 29 Ma. In contrast to the upper Velkerri interval, the mass-balance model permits widespread ocean anoxia during deposition of the lower Velkerri interval. Black shales of the ca. 1.73 Ga Paleoproterozoic Wollogorang Formation previously yielded an erroneously young Re-Os date of 1359 ± 150 Ma, likely due to post-depositional hydrothermal alteration at ca. 1640 Ma. Higher δ 238 U is observed in samples closer to the base of the black shale unit where the greatest extent of open-system Re-Os behavior was observed. Hence, post-depositional hydrothermal fluid flow may overprint the depositional δ 238 U of black shales and cause erroneous estimates of ancient global ocean anoxia.

Sidestream sludge treatment approaches have been developed in recent years to achieve mainstream nitrite shunt or partial nitritation, where NOB are selectively inactivated by biocidal factors such as free nitrous acid (FNA) or free ammonium (FA) in a sidestream reactor.The existence of NOB in raw wastewater has been increasingly realized and could pose critical challenge to stable NOB suppressions in those systems. This study, for the first time, evaluated 2 the impact of influent NOB on the NOB suppressions in a mainstream nitrite shunt system achieved through sidestream sludge treatment. An over 500-day sequential batch reactor operation with six experimental phases rigorously demonstrated the negative effects of influent NOB on mainstream NOB control. Continuously seeding of NOB contained in influent stimulated NOB community shifts, leading to different extents of ineffective NOB suppression.The role of primary wastewater treatment in NOB removal from raw wastewater was also investigated. Results suggest primary settling and High Rate Activated Sludge system could remove a large part of NOB contained in raw wastewater. Primary treatment for raw wastewater is necessary for ensuring stable mainstream NOB suppressions.

Molecular evolution studies suggest that amelogenins (AMEL), the principal components of the mammalian enamel matrix, emerged considerably later than ameloblastin (AMBN), and enamelin. Here we have created a transgenic mouse model to ask the question how a conceivable basal enamel lacking AMEL and enriched in the more basal AMBN might compare to recent mouse enamel. To address this question we have overexpressed AMBN using a K14 promoter and removed AMEL from the genetic background by crossbreeding with AMEL−/− mice. Enamel coverings of AMEL−/− mice and of the squamate Iguana iguana were used for comparison. Scanning electron microscopic analysis documented that AMBN TG × amel−/− mouse molars were covered by a 5μm thin “enameloid” layer resembling the thin enamel of the Iguana squamate. Transmission electron microscopy revealed that the enamel of developing AMBN TG × amel−/−mouse molars contained approximately 70nm short and randomly oriented crystals, while WT controls, AMBN overexpressors, and AMEL−/− mice all featured elongated and parallel oriented crystals measuring between 300nm and 600nm in average length. Together, these studies illustrate that AMBN promotes the growth of a crystalline enamel layer with short and randomly oriented crystals, but lacks the ability to facilitate the formation of long and parallel oriented apatite crystals.