Cdc48 targets INQ-localized Mrc1 to facilitate recovery from replication stress

DNA replication stress is a source of genome instability and a replication checkpoint has evolved to enable fork stabilisation and completion of replication during stress. Mediator of the replication checkpoint 1 (Mrc1) is the primary mediator of this response in Saccharomyces cerevisiae. Mrc1 is partially sequestered in the intranuclear quality control compartment (INQ) upon methyl methanesulfonate (MMS)-induced replication stress. Here we show that Mrc1 re-localizes from the replication fork to INQ during replication stress. Sequestration of Mrc1 in INQ is facilitated by the Btn2 chaperone and the Cdc48 segregase is required to release Mrc1 from INQ during recovery from replication stress. Consistently, we show that Cdc48 colocalizes with Mrc1 in INQ and we find that Mrc1 is recognized by the Cdc48 cofactors Ufd1 and Otu1, which contribute to clearance of Mrc1 from INQ. Our findings suggest that INQ localization of Mrc1 and Cdc48 function to facilitate replication stress recovery by transiently sequestering the replication checkpoint mediator Mrc1 and explains our observation that Btn2 and Cdc48 are required for efficient replication restart following MMS-induced replication stress.

Can Green Plants Mitigate Ammonia Concentration in Piglet Barns?

For animal welfare and for farmers’ health, the concentration of ammonia (NH3) in animal houses should be as low as possible. Plants can remove various atmospheric contaminants through the leaf stomata. This study examined the effect of ornamental plants installed inside a piglet barn on the NH3 concentration in the air. Gas measurements of the air in the ‘greened’ compartment (P) and a control compartment (CTR) took place over two measuring periods (summer–autumn and winter). Differences between the NH3 emissions were calculated based on the ventilation rates according to the CO2 balance. Fairly low mean NH3 concentrations between 2 and 4 ppm were measured. The NH3 emissions were about 20% lower (p < 0.01) in P than in CTR, in summer–autumn and in winter period.

The Gas-Dynamic Efficiency Increase of the K-300 Series Steam Turbine Control Compartment

The paper proposes ways to increase the efficiency of nozzle control for steam power turbines of the K-300 series, that, along with the K-200 series turbines, form the basis of thermal energy in Ukraine. The object of study is considered to be the control compartment (CC) of the high-pressure cylinder (HPC) of the K-325-23.5 steam turbine. In the paper, the calculation and design of the control compartment of the steam turbine was performed using the complex methodology developed in IPMach NAS of Ukraine, that includes methods of different levels of complexity, from one-dimensional to models for calculation of spatial viscous flows, as well as analytical methods for spatial geometries of flow parts description based on limited number of parameterized values. The complex design methodology is implemented in the IPMFlow software package, which is a development of the FlowER and FlowER–U software packages. A model of a viscous turbulent flow is based on the numerical integration of an averaged system of Navier-Stokes equations, for the closure of which the two-term Tamman equation of state is used. Turbulent phenomena were taken into account using a SST Menter two-parameter differential turbulence model. The research was conducted for six operation modes in the calculation area, which consisted of more than 3 million cells (elementary volumes), taking into account the interdiscand diaphragm leakage. According to the results of numerical studies of the original control compartment of the K-325-23.5 steam turbine, it is shown that the efficiency in the flow part is quite low in all operation modes, including the nominal one (100% power mode), due to large losses of kinetic energy in the equalization chamber, as well as inflated load on the first stage. On the basis of the performed analysis of gas-dynamic processes, the directions of a control compartment flow part modernization are formed and themodernization itself is executed. In the new flow part, compared to the original one, there is a favorable picture of the flow in all operation modes, which ensures its high gas-dynamic efficiency. Depending on the mode, the efficiency of the control compartment increased by 4.9–7.3%, and the capacity increased by 1–2 MW. In the nominal mode (100% mode) the efficiency of the new control compartment, taking into account the interdisc and overbandage leakage, is 91%.

Continual near-infrared spectroscopy monitoring in the injured lower limb and acute compartment syndrome

Aims The aim of this study was to evaluate near-infrared spectroscopy (NIRS) as a continuous, non-invasive monitor for acute compartment syndrome (ACS). Patients and Methods NIRS sensors were placed on 86 patients with, and 23 without (controls), severe leg injury. NIRS values were recorded for up to 48 hours. Longitudinal data were analyzed using summary and graphical methods, bivariate comparisons, and multivariable multilevel modelling. Results Mean NIRS values in the anterior, lateral, superficial posterior, and deep posterior compartments were between 72% and 78% in injured legs, between 69% and 72% in uninjured legs, and between 71% and 73% in bilaterally uninjured legs. In patients without ACS, the values were typically > 3% higher in injured compartments. All seven limbs with ACS had at least one compartment where NIRS values were 3% or more below a reference uninjured control compartment. Missing data were encountered in many instances. Conclusion NIRS oximetry might be used to aid the assessment and management of patients with ACS. Sustained hyperaemia is consistent with the absence of ACS in injured legs. Loss of the hyperaemic differential warrants heightened surveillance. NIRS values in at least one injured compartment(s) were > 3% below the uninjured contralateral compartment(s) in all seven patients with ACS. Additional interventional studies are required to validate the use of NIRS for ACS monitoring. Cite this article: Bone Joint J 2018;100-B:787–97.

IMiQ: a novel protein quality control compartment protecting mitochondrial functional integrity

Aggregated polypeptides accumulating inside mitochondria are sequestered in a single cellular quality compartment, called IMiQ. Its formation retains proteotoxic aggregates in a distinct cellular localization, increasing mitochondrial fitness by relieving the protein quality control system of misfolded polypeptides.

IMiQC: a novel protein quality control compartment protecting mitochondrial functional integrity

Aggregation processes can cause severe perturbations of cellular homeostasis and are frequently associated with diseases. We performed a comprehensive analysis of mitochondrial quality and function in presence of misfolded, aggregation-prone polypeptides. Although we observed significant aggregate formation inside mitochondria, we observed only a minor impairment of mitochondrial function. We could show that detoxification of misfolded reporter polypeptides as well as endogenous proteins inside mitochondria takes place via their sequestration into the specific organellar deposit site Intra-Mitochondrial Protein Quality Control Compartment (IMiQC). Only minor amounts of co-aggregated proteins were associated with IMiQC and neither resolubilization nor degradation by the mitochondrial PQC system were observed. The single IMiQC aggregate deposit was not transferred to daughter cells during cell division. Detoxification of misfolded polypeptides via IMiQC formation was highly dependent on a functional mitochondrial fission machinery. We conclude that the formation of the aggregate deposit is an important mechanism to maintain full functionality of mitochondria under proteotoxic stress conditions.

Mammalian ER mannosidase I resides in quality control vesicles, where it encounters its glycoprotein substrates

Endoplasmic reticulum α1,2 mannosidase I (ERManI), a central component of ER quality control and ER-associated degradation (ERAD), acts as a timer enzyme, modifying N-linked sugar chains of glycoproteins with time. This process halts glycoprotein folding attempts when necessary and targets terminally misfolded glycoproteins to ERAD. Despite the importance of ERManI in maintenance of glycoprotein quality control, fundamental questions regarding this enzyme remain controversial. One such question is the subcellular localization of ERManI, which has been suggested to localize to the ER membrane, the ER-derived quality control compartment (ERQC), and, surprisingly, recently to the Golgi apparatus. To try to clarify this controversy, we applied a series of approaches that indicate that ERManI is located, at the steady state, in quality control vesicles (QCVs) to which ERAD substrates are transported and in which they interact with the enzyme. Both endogenous and exogenously expressed ERManI migrate at an ER-like density on iodixanol gradients, suggesting that the QCVs are derived from the ER. The QCVs are highly mobile, displaying dynamics that are dependent on microtubules and COP-II but not on COP-I vesicle machinery. Under ER stress conditions, the QCVs converge in a juxtanuclear region, at the ERQC, as previously reported. Our results also suggest that ERManI is turned over by an active autophagic process. Of importance, we found that membrane disturbance, as is common in immunofluorescence methods, leads to an artificial appearance of ERManI in a Golgi pattern.