The regulation of mTORC2 kinase activity and complex integrity

Growth factor signaling promotes anabolic processes via activation of the PI3K-Akt kinase cascade. Deregulation of the growth factor-dependent PI3K-Akt pathway was implicated in tumorigenesis. Akt is an essential serine/threonine protein kinase that controls multiple physiological functions such as cell growth, proliferation, and survival to maintain cellular homeostasis. Recently, the mammalian Target of Rapamycin Complex 2 (mTORC2) was identified as the main Akt Ser-473 kinase, and Ser-473 phosphorylation is required for Akt hyperactivation. However, the detailed mechanism of mTORC2 regulation in response to growth factor stimulation or cellular stresses is not well understood. In the first project, we studied the regulation of the mTORC2-Akt signaling under ER stress. We identified the inactivation of mTORC2 by glycogen synthase kinase-3β (GSK-3β). Under ER stress, the essential mTORC2 component, rictor, is phosphorylated by GSK-3β at Ser-1235. This phosphorylation event results in the inhibition of mTORC2 kinase activity by interrupting Akt binding to mTORC2. Blocking rictor Ser-1235 phosphorylation can attenuate the negative impacts of GSK-3β on mTORC2/Akt signaling and tumor growth. Thus, our work demonstrated that GSK-3β-mediated rictor Ser-1235 phosphorylation in response to ER stress interferes with Akt signaling by inhibiting mTORC2 kinase activity. In the second project, I investigated the regulation of the mTORC2 integrity. We found that basal mTOR kinase activity depends on ATP level, which is tightly regulated by cell metabolism. The ATP-sensitive mTOR kinase is required for SIN1 protein phosphorylation and stabilization. SIN1 is an indispensable subunit of mTORC2 and is required for the complex assembly and mTORC2 kinase activity. Our findings reveal that mTOR-mediated phosphorylation of SIN1 is critical for maintaining complex integrity by preventing SIN1 from lysosomal degradation. In sum, our findings verify two distinct mTORC2 regulatory mechanisms via its components rictor and SIN1. First, GSK-3β-mediated rictor Ser-1235 phosphorylation results in mTORC2 inactivation by interfering its substrate binding ability. Second, mTOR-mediated Ser-260 phosphorylation of SIN1 preserves its complex integrity. Thus, these two projects provide novel insights into the regulation of mTORC2.

Assessing Treatment Integrity: A Case Example

This paper presents an example of assessing treatment integrity as part of an experimental study of home-based, intensive family preservation services (IFPS). Participants were 103 IFPS workers and 24 state public child welfare agency workers (FC). The structured, self-report questionnaire included questions about specific components of the services, as well as the characteristics of the family and the workers themselves. Findings suggest that IFPS workers delivered services according to the treatment model guidelines. The procedure yielded a good estimate of whether the structural components of treatment were delivered according to the model as delineated in the treatment manual. The paper discusses the advantages and disadvantages of this approach to assessing treatment integrity.

The impact of ocean acidification and warming on the skeletal mechanical properties of the sea urchin Paracentrotus lividus from laboratory and field observations

Increased atmospheric CO2 concentration is leading to changes in the carbonate chemistry and the temperature of the ocean. The impact of these processes on marine organisms will depend on their ability to cope with those changes, particularly the maintenance of calcium carbonate structures. Both a laboratory experiment (long-term exposure to decreased pH and increased temperature) and collections of individuals from natural environments characterized by low pH levels (individuals from intertidal pools and around a CO2 seep) were here coupled to comprehensively study the impact of near-future conditions of pH and temperature on the mechanical properties of the skeleton of the euechinoid sea urchin Paracentrotus lividus. To assess skeletal mechanical properties, we characterized the fracture force, Young's modulus, second moment of area, material nanohardness, and specific Young's modulus of sea urchin test plates. None of these parameters were significantly affected by low pH and/or increased temperature in the laboratory experiment and by low pH only in the individuals chronically exposed to lowered pH from the CO2 seeps. In tidal pools, the fracture force was higher and the Young's modulus lower in ambital plates of individuals from the rock pool characterized by the largest pH variations but also a dominance of calcifying algae, which might explain some of the variation. Thus, decreases of pH to levels expected for 2100 did not directly alter the mechanical properties of the test of P. lividus. Since the maintenance of test integrity is a question of survival for sea urchins and since weakened tests would increase the sea urchins' risk of predation, our findings indicate that the decreasing seawater pH and increasing seawater temperature expected for the end of the century should not represent an immediate threat to sea urchins vulnerability

Constraints on the magnitude and patterns of ocean cooling at the Last Glacial Maximum - Supplementary material

Observation-based reconstructions of sea surface temperature from relatively stable periods in the past, such as the Last Glacial Maximum, represent an important means of constraining climate sensitivity and evaluating model simulations. The first quantitative global reconstruction of sea surface temperatures during the Last Glacial Maximum was developed by the Climate Long-Range Investigation, Mapping and Prediction (CLIMAP) project in the 1970s and 1980s. Since that time, several shortcomings of that earlier effort have become apparent. Here we present an updated synthesis of sea surface temperatures during the Last Glacial Maximum, rigorously defined as the period between 23 and 19 thousand years before present, from the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface (MARGO) project. We integrate microfossil and geochemical reconstructions of surface temperatures and include assessments of the reliability of individual records. Our reconstruction reveals the presence of large longitudinal gradients in sea surface temperature in all of the ocean basins, in contrast to the simulations of the Last Glacial Maximum climate available at present.

Lake Baikal amphipods under climate change: Thermal constraints and ecological consequences, links to supplementary material

Lake Baikal, the world's most voluminous freshwater lake, has experienced unprecedented warming during the last decades. A uniquely diverse amphipod fauna inhabits the littoral zone and can serve as a model system to identify the role of thermal tolerance under climate change. This study aimed to identify sublethal thermal constraints in two of the most abundant endemic Baikal amphipods, Eulimnogammarus verrucosus and Eulimnogammarus cyaneus, and Gammarus lacustris, a ubiquitous gammarid of the Holarctic. As the latter is only found in some shallow isolated bays of the lake, we further addressed the question whether rising temperatures could promote the widespread invasion of this non-endemic species into the littoral zone. Animals were exposed to gradual temperature increases (4 week, 0.8 °C/d; 24 h, 1 °C/h) starting from the reported annual mean temperature of the Baikal littoral (6 °C). Within the framework of oxygen- and capacity-limited thermal tolerance (OCLTT), we used a nonlinear regression approach to determine the points at which the changing temperature-dependence of relevant physiological processes indicates the onset of limitation. Limitations in ventilation representing the first limits of thermal tolerance (pejus (= "getting worse") temperatures (Tp)) were recorded at 10.6 (95% confidence interval; 9.5, 11.7), 19.1 (17.9, 20.2), and 21.1 (19.8, 22.4) °C in E. verrucosus, E. cyaneus, and G. lacustris, respectively. Field observations revealed that E. verrucosus retreated from the upper littoral to deeper and cooler waters once its Tp was surpassed, identifying Tp as the ecological thermal boundary. Constraints in oxygen consumption at higher than critical temperatures (Tc) led to an exponential increase in mortality in all species. Exposure to short-term warming resulted in higher threshold values, consistent with a time dependence of thermal tolerance. In conclusion, species-specific limits to oxygen supply capacity are likely key in the onset of constraining (beyond pejus) and then life-threatening (beyond critical) conditions. Ecological consequences of these limits are mediated through behavioral plasticity in E. verrucosus. However, similar upper thermal limits in E. cyaneus (endemic, Baikal) and G. lacustris (ubiquitous, Holarctic) indicate that the potential invader G. lacustris would not necessarily benefit from rising temperatures. Secondary effects of increasing temperatures remain to be investigated.

Beryllium ages, sedimentology and weathering characteristics of Reedy Glacier deposits

Deposits corresponding to multiple periods of glaciation are preserved in ice-free areas adjacent to Reedy Glacier, southern Transantarctic Mountains. Glacial geologic mapping, supported by 10Be surface-exposure dating, shows that Reedy Glacier was significantly thicker than today multiple times during the mid-to-late Cenozoic. Longitudinal-surface profiles reconstructed from the upper limits of deposits indicate greater thickening at the glacier mouth than at the head during these episodes, indicating that Reedy Glacier responded primarily to changes in the thickness of the West Antarctic Ice Sheet. Surface-exposure ages suggest this relationship has been in place since at least 5 Ma. The last period of thickening of Reedy Glacier occurred during Marine Isotope Stage 2, at which time the glacier surface near its confluence with the West Antarctic Ice Sheet was at least 500 m higher than today.

(Table 4) Concentrations of radionuclides in waters of the Barents and Kara Seas in August 2003

A methodology of experimental simulation of state of spent nuclear fuel that occurs on the sea floor due to some catastrophes or dumping is developed. Data on long-term (more than 2000 days) experiments on estimation of 85Kr and 137Cs release rate from spent nuclear fuel (fragments of irradiated UO2 pellets) were firstly obtained; these estimates prove correctness of a hypothesis offered by us in early 1990s concerning to earlier 85Kr release (by one order of magnitude higher than that of 137Cs) as compared to other fission fragments in case of loss of integrity of fuel containment as a result of corrosion on the sea floor. A method and technique of onboard 85Kr and 137Cs sampling and extraction (as well as sampling of tritium, product of triple 235U fission) and their radiometric analysis at coastal laboratories are developed. Priority data on 85Kr background in bottom layers of the Barents and Kara Seas and 137Cs and 3H in these seas (state of 2003) are presented. Models necessary for estimation of dilution of fission products of spent nuclear fuel and their transport on the floor in accident and dumping regions are developed. An experimental method for examination of state of spent nuclear fuel on the sea floor (one expedition each 2-3 years) by 85Kr release into environment (a leak tracer) is proposed; this release is an indicator of destruction of fuel containment and release of products of spent nuclear fuel in case of 235UO2 corrosion in sea water.

Seawater carbonate chemistry and biological processes of Mytilus edulis during experiments, 2011

Progressive ocean acidification due to anthropogenic CO2 emissions will alter marine ecosytem processes. Calcifying organisms might be particularly vulnerable to these alterations in the speciation of the marine carbonate system. While previous research efforts have mainly focused on external dissolution of shells in seawater under saturated with respect to calcium carbonate, the internal shell interface might be more vulnerable to acidification. In the case of the blue mussel Mytilus edulis, high body fluid pCO2 causes low pH and low carbonate concentrations in the extrapallial fluid, which is in direct contact with the inner shell surface. In order to test whether elevated seawater pCO2 impacts calcification and inner shell surface integrity we exposed Baltic M. edulis to four different seawater pCO2 (39, 142, 240, 405 Pa) and two food algae (310-350 cells mL-1 vs. 1600-2000 cells mL-1) concentrations for a period of seven weeks during winter (5°C). We found that low food algae concentrations and high pCO2 values each significantly decreased shell length growth. Internal shell surface corrosion of nacreous ( = aragonite) layers was documented via stereomicroscopy and SEM at the two highest pCO2 treatments in the high food group, while it was found in all treatments in the low food group. Both factors, food and pCO2, significantly influenced the magnitude of inner shell surface dissolution. Our findings illustrate for the first time that integrity of inner shell surfaces is tightly coupled to the animals' energy budget under conditions of CO2 stress. It is likely that under food limited conditions, energy is allocated to more vital processes (e.g. somatic mass maintenance) instead of shell conservation. It is evident from our results that mussels exert significant biological control over the structural integrity of their inner shell surfaces.

Grazing under experimental hypercapnia and elevated temperature does not affect the radula of a chiton (Mollusca, Polyplacophora, Lepidopleurida)

Chitons (class Polyplacophora) are benthic grazing molluscs with an eight-part aragonitic shell armature. The radula, a serial tooth ribbon that extends internally more than half the length of the body, is mineralised on the active feeding teeth with iron magnetite apparently as an adaptation to constant grazing on rocky substrates. As the anterior feeding teeth are eroded they are shed and replaced with a new row. The efficient mineralisation and function of the radula could hypothetically be affected by changing oceans in two ways: changes in seawater chemistry (pH and pCO2) may impact the biomineralisation pathway, potentially leading to a weaker or altered density of the feeding teeth; rising temperatures could increase activity levels in these ectothermic animals, and higher feeding rates could increase wear on the feeding teeth beyond the animals' ability to synthesise, mineralise, and replace radular rows. We therefore examined the effects of pH and temperature on growth and integrity in the radula of the chiton Leptochiton asellus. Our experiment implemented three temperature (10, 15, 20 °C) and two pCO2 treatments (400 µatm, pH 8.0; 2000 µatm, pH 7.5) for six treatment groups. Animals (n = 50) were acclimated to the treatment conditions for a period of 4 weeks. This is sufficient time for growth of ca. 7-9 new tooth rows or 20% turnover of the mineralised portion. There was no significant difference in the number of new (non-mineralised) teeth or total tooth row count in any treatment. Examination of the radulae via SEM revealed no differences in microwear or breakage on the feeding cusps correlating to treatment groups. The shell valves also showed no signs of dissolution. As a lineage, chitons have survived repeated shifts in Earth's climate through geological time, and at least their radulae may be robust to future perturbations.

Effects of light and elevated pCO2 on the growth and photochemical efficiency of Acropora cervicornis

The effects of light and elevated pCO2 on the growth and photochemical efficiency of the critically endangered staghorn coral, Acropora cervicornis, were examined experimentally. Corals were subjected to high and low treatments of CO2 and light in a fully crossed design and monitored using 3D scanning and buoyant weight methodologies. Calcification rates, linear extension, as well as colony surface area and volume of A. cervicornis were highly dependent on light intensity. At pCO2 levels projected to occur by the end of the century from ocean acidification (OA), A. cervicornis exhibited depressed calcification, but no change in linear extension. Photochemical efficiency (F v /F m ) was higher at low light, but unaffected by CO2. Amelioration of OA-depressed calcification under high-light treatments was not observed, and we suggest that the high-light intensity necessary to reach saturation of photosynthesis and calcification in A. cervicornis may limit the effectiveness of this potentially protective mechanism in this species. High CO2 causes depressed skeletal density, but not linear extension, illustrating that the measurement of extension by itself is inadequate to detect CO2 impacts. The skeletal integrity of A. cervicornis will be impaired by OA, which may further reduce the resilience of the already diminished populations of this endangered species.

Sedimentological investigations and age constraints of sediment cores from the outer Abbot trough, Amundsen Sea shelf

Knowing the extent of the West Antarctic Ice Sheet (WAIS) at the Last Glacial Maximum (LGM) is crucial for initiating and calibrating numerical ice sheet models that can predict future ice-sheet change and contributions to sea level. However, empirical data are lacking for key areas of outer continental shelves, where the LGM-WAIS must have terminated. We present detailed marine geophysical and geological data documenting an up to ~12 m-thick sequence of glaciomarine sediments within a relict glacial trough in the outer parts of the Amundsen Sea Embayment. Continuous deposition must have persisted here since at least >40 ka BP, pre-dating the established LGM by >13,000 years. Observations constrain the LGM grounding line to a distinct grounding-zone wedge ~100 km inland from the continental shelf edge. Thus, a substantial shelf area (~6000 km**2) remained ice free through the last glacial cycle.

Unravelling the moisture sources of the Alpine Glaciers using tunnel valleys as constraints

A lack of archives has impeded reconstructions of moisture pathways for past glaciations in the European Alps. Here, we focus on the confluence area of two palaeoglaciers in the Swiss Plateau that were sourced on the northern (Aare glacier) and southern sides (Valais glacier) of the European Alps. We mapped tunnel valleys in the region using a drilling database, based on which we inferred the relative extent of each glacier c. 270 ka ago when the valleys were formed. We then compared this situation with that of the LGM. We found that, while the Valais glacier expanded farther into the foreland than the Aare glacier during the LGM, the opposite was the case c. 270 ka ago. We also found that LGM glaciers were non-erosive in the distal foreland. These contrasts in extents and erosional efficiencies imply differences in moisture pathways between the LGM and the time when the tunnel valleys were formed.