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Recent evidence indicates that saturated fatty acid-induced (SFA-induced) lipotoxicity contributes to the pathogenesis of cardiovascular and metabolic diseases; however, the molecular mechanisms that underlie SFA-induced lipotoxicity remain unclear. Here, we have shown that repression of stearoyl-CoA desaturase (SCD) enzymes, which regulate the intracellular balance of SFAs and unsaturated FAs, and the subsequent accumulation of SFAs in vascular smooth muscle cells (VSMCs), are characteristic events in the development of vascular calcification. We evaluated whether SMC-specific inhibition of SCD and the resulting SFA accumulation plays a causative role in the pathogenesis of vascular calcification and generated mice with SMC-specific deletion of both Scd1 and Scd2. Mice lacking both SCD1 and SCD2 in SMCs displayed severe vascular calcification with increased ER stress. Moreover, we employed shRNA library screening and radiolabeling approaches, as well as in vitro and in vivo lipidomic analysis, and determined that fully saturated phosphatidic acids such as 1,2- distearoyl-PA (18:0/18:0-PA) mediate SFA-induced lipotoxicity and vascular calcification. Together, these results identify a key lipogenic pathway in SMCs that mediates vascular calcification., Introduction Vascular calcification is a major complication in patients who are aging, have diabetes, or have chronic kidney disease (CKD) and is an active process that differentiates vascular smooth muscle [...]

A major factor often overlooked in the production of calcifying marine invertebrates in aquaculture is the effect of changes in the carbonate chemistry of culture water caused by organism metabolism and calcification. This study examined the effects of temperature, stocking density and seawater exchange rate on the survival and growth of the juvenile sea urchin, Tripneustes gratilla with particular reference to effects of these factors on the carbonate chemistry of culture water. Growth and survival of T. gratilla were highest at 26-28 °C. Growth rates, relative spine length, consumption rates and food conversion efficiency were reduced by up to 50 % by an increase in stocking density from 43 to 129 individuals m.sup.-2 and a reduction in seawater exchange rate from 3.0 to 0.3 exchanges h.sup.-1, but survival rates were unaffected. Analysis of the influence of seawater parameters indicated that total alkalinity (A.sub.T), calcite saturation state (ΩCa) and dissolved CO.sub.2 were the primary factors limiting growth at high densities and low seawater exchange rates. Uptake of bicarbonates for calcification and release of respiratory CO.sub.2 by T. gratilla appeared to be driving changes in carbonate chemistry. Our results show that reduced capacity of culture water to buffer acidification (low A.sub.T) can be a limiting factor in intensive production of calcifying marine invertebrates. This study demonstrates the importance of considering the influence of biogenic CO.sub.2 on seawater carbonate chemistry in aquaculture, particularly given the threat of reduced pH of source water due to ocean acidification, and also in experiments investigating the influence of anthropogenic CO.sub.2., Author(s): Benjamin Mos [sup.1] , Maria Byrne [sup.2] , Kenneth L. Cowden [sup.1] , Symon A. Dworjanyn [sup.1] Author Affiliations: (Aff1) grid.1031.3, 0000000121532610, National Marine Science Centre, Southern Cross University, [...]

A large percentage of CO.sub.2 emitted into the atmosphere is absorbed by the oceans, causing chemical changes in surface waters known as ocean acidification (OA). Despite the high interest and increased pace of OA research to understand the effects of OA on marine organisms, many ecologically important organisms remain unstudied. Calcidiscus is a heavily calcified coccolithophore genus that is widespread and genetically and morphologically diverse. It contributes substantially to global calcium carbonate production, organic carbon production, oceanic carbon burial, and ocean-atmosphere CO.sub.2 exchange. Despite the importance of this genus, relatively little work has examined its responses to OA. We examined changes in growth, morphology, and carbon allocation in multiple strains of Calcidiscus leptoporus in response to ocean acidification. We also, for the first time, examined the OA response of Calcidiscusquadriperforatus, a larger and more heavily calcified Calcidiscus congener. All Calcidiscus coccolithophores responded negatively to OA with impaired coccolith morphology and a decreased ratio of particulate inorganic to organic carbon (PIC:POC). However, strains responded variably; C. quadriperforatus showed the most sensitivity, while the most lightly calcified strain of C. leptoporus showed little response to OA. Our findings suggest that calcium carbonate production relative to organic carbon production by Calcidiscus coccolithophores may decrease in future oceans and that Calcidiscus distributions may shift if more resilient strains and species become dominant in assemblages. This study demonstrates that variable responses to OA may be strain or species specific in a way that is closely linked to physiological traits, such as cellular calcite quota. Electronic supplementary material The online version of this article (doi:10.1007/s00227-015-2669-x) contains supplementary material, which is available to authorized users., Author(s): Rachel E. Diner[sup.1] , Ina Benner[sup.1] , Uta Passow[sup.2] , Tomoko Komada[sup.1] , Edward J. Carpenter[sup.1] , Jonathon H. Stillman[sup.1] [sup.3] [sup.4] Author Affiliations: (1) Romberg Tiburon Center, San [...]

Calciphylaxis [calcific uraemic arteriolopathy (CUA)] is a rare disease at the interface of nephrology, dermatology and cardiology. CUA most often occurs in adult dialysis patients. It is only rarely seen in patients without relevant chronic kidney disease, and only anecdotal reports about childhood calciphylaxis have been published. Clinically, CUA is characterized by a typical cascade, starting with severe pain in initially often inconspicuous skin areas, followed by progressive cutaneous lesions that may develop into deep tissue ulcerations. The typical picture is a mixture of large retiform ulceration with thick eschar surrounded by violaceous, indurated, tender plaques. The histopathological picture reveals arteriolar, often circumferential, calcification and extensive matrix remodelling of the subcutis. These findings explain the macroscopic correlation between skin induration and ulceration. The prognosis in CUA patients is limited due to underlying comorbidities such as uraemic cardiovascular disease and infectious complications. The etiology of CUA is multifactorial, and imbalances between pro- and anti-calcification factors, especially in the setting of end-stage renal disease play an outstanding role. Oral anticoagulant treatment with vitamin K antagonists is a predominant CUA trigger factor. It is speculative as to why children and adolescents only develop calciphylaxis in exceptional cases, although a seldom usage of vitamin K antagonists and the preserved mineral buffering capacity of the growing skeleton may be protective. Keywords Calciphylaxis * Calcific uraemic arteriolopathy * Chronic kidney disease * Calcification * Vascular disease, Introduction Calciphylaxis, or calcific uraemic arteriolopathy (CUA), is a rare disease. The estimated yearly incidence is The clinical importance of CUA Although rare, several issues predispose CUA as a focus [...]

The impact of elevated C[O.sub.2] and temperature on photosynthesis and calcification in the symbiont-bearing benthic foraminifer Marginopora vertebralis was studied. Individual specimens of M. vertebralis were collected from Heron Island on the southern Great Barrier Reef (Australia). They were maintained for 5 weeks at different temperatures (28, 32°C) and pC[O.sub.2] (400, 1,000 µatm) levels spanning a range of current and future climate-change scenarios. The photosynthetic capacity of M. vertebralis was measured with [O.sub.2] microsensors and a pulse-amplitudemodulated chlorophyll (Chl) fluorometer, in combination with estimates of Chl a and Chl [c.sub.2] concentrations and calcification rates. After 5 weeks, control specimens remained unaltered for all parameters. Chlorophyll a concentrations significantly decreased in the specimens at 1,000 µatm C[O.sub.2] for both temperatures, while no change in Chl [c.sub.2] concentration was observed. Photoinhibition was observed under elevated C[O.sub.2] and temperature, with a 70-80 % decrease in the maximum quantum yield of PSII. There was no net [O.sub.2] production at elevated temperatures in both C[O.sub.2] treatments as compared to the control temperature, supporting that temperature has more impact on photosynthesis and [O.sub.2] flux than changes in ambient C[O.sub.2]. Photosynthetic pigment loss and a decrease in photochemical efficiency are thus likely to occur with increased temperature. The elevated C[O.sub.2] and high temperature treatment also lead to a reduction in calcification rate (from +0.1 to >-0.1 % [day.sup.-1]). Thus, both calcification and photosynthesis of the major sediment-producing foraminifer M. vertebralis appears highly vulnerable to elevated temperature and ocean acidification scenarios predicted in climate-change models., Introduction Climate change is expected to have significant impacts on near-shore marine ecosystems and their resident organisms (Johnson and Marshall 2007). Human activities, such as burning of fossil fuels, industrialization, [...]

Bryozoans are colonial benthic marine invertebrate calcifiers, important and especially abundant and diverse in southern hemisphere shelf environments. Large heavily calcified colonies can be up to 50 years old, but most longer-lived bryozoans are limited to 10-20 y. Many smaller species are annual. Radial extension in flat encrusting bryozoans is generally on the order of 1-5 mm/y. Erect calcified species generally grow vertically 2-15 mm/y, though articulated species such as Cenaria may reach rates of 40 mm/y. Corresponding calcification rates are generally [10.sup.1]-[10.sup.2] mg/y, but there can be an order of magnitude variation in rate among years in high-latitude bryozoans. Multi-branched bryozoans produce up to 24 g of CaC[O.sub.3]/y. The carbonate produced by bryozoans varies from calcite to aragonite and mixtures of both. Skeletal carbonate mineralogy of bryozoans is complex and appears to be strongly genetically controlled. Global climate change, leading to increasing water temperatures, will generally increase marine bryozoan metabolic rates, and may increase Mg in calcite. On the other hand, decreasing pH (ocean acidification) causes corrosion, changes in mineralogy, and decreased survival. This review of bryozoan growth and calcification allows a general perspective, but also reveals gaps in our knowledge which need to be addressed., Introduction Bryozoans have been described as a minor phylum, and it is true that the combination of being inedible, small, difficult to identify, and currently found mainly in cryptic habitats [...]

Ocean acidification caused by rising atmospheric C[O.sub.2] is predicted to negatively impact growth and calcification rates of coralline algae. Decreases in coralline abundance may have cascading effects on marine ecosystems and on carbon sequestration worldwide. In this study, we measured growth and calcification rates of three common species of articulated coralline algae (Bossiella plu-mosa. Calliarthron tuberculosum, and Corallina vancouv-eriensis) at an intertidal field site in British Columbia. Linear growth rates measured in the field were slow, al-though Bossiella grew significantly faster (0.22 cm [mon.sup.-1]) than Calliarthron and Corallina (0.17 and 0.15 cm [mon.sup.-1], respectively). Growth rates in the field were generally slower than growth rates in the laboratory. Suggesting that data generated in the laboratory may not be representative of natural field conditions. Growth rates did not decrease as fronds approached their maximum observed size, suggest-ing that maximum frond size might be determined not by intrinsic factors but by external factors such as wave-induced drag forces. Using growth data, we estimate that the largest observed Bossiella frond (20 cm2) and Calliarthron frond (40 [cm.sup.2]) were about 4 and 11 years old, respectively, and had deposited approximately 1 and 6 g CaCO3 in that time. Given the great abundance of coralline algae along the coast of British Columbia, deposition rates of Ca[CO.sub.3] are expected to play a significant but poorly characterized role in carbon sequestration., Introduction Coralline algae (Corallinales and Sporolithales, Rhodo-phyta) are important components of marine communities worldwide, cementing coral reefs (Steneck and Adey, 1976) and quickly colonizing bare rock to provide habitat for [...]