Cytochrome c oxidase subunit I gene in Thalassiosira nordenskioeldii strains inhabiting in cold and warm sea waters.

From the biota beneath the sea ice in Lake Saroma, which is adjacent to Sea of Okhotsk, a diatom culture of Saroma 16 was isolated. Strutted processes and a labiate process in Saroma 16 were characteristic of those in Thalassiosira nordenskioeldii. Similarity search analysis showed that the 826-bp rbcL-3P region sequence of this strain was 100% identical to multiple sequences registered as T. nordenskioeldii in a public database. The 4305-bp PCR-amplified mitochondrial cytochrome c oxidase subunit I (COI) gene (COI)-5P region of Saroma 16 included a 1060-bp open reading frame (ORF), which was interrupted by 934-bp and 2311-bp introns that included frame-shifted ORFs encoding reverse-transcriptase (RTase)-like proteins. Previous reports showed that a strain of the same species, CNS00052, originating from the East China Sea included no introns in the COI, whereas North Atlantic Ocean strains of the same species, such as CCMP992, CCMP993, and CCMP997, included a 2.3-kb intron in the same position as Saroma 16.

Salt tolerance in relation to elemental concentrations in leaf cell vacuoles and chloroplasts of a C4 monocotyledonous halophyte.

Halophytes accumulate and sequester high concentrations of salt in vacuoles while maintaining lower levels of salt in the cytoplasm. The current data on cellular and subcellular partitioning of salt in halophytes are, however, limited to only a few dicotyledonous C3 species. Using cryo-scanning electron microscopy X-ray microanalysis, we assessed the concentrations of Na, Cl, K, Ca, Mg, P and S in various cell types within the leaf-blades of a monocotyledonous C4 halophyte, Rhodes grass (Chloris gayana). We also linked, for the first time, elemental concentrations in chloroplasts of mesophyll and bundle sheath cells to their ultrastructure and photosynthetic performance of plants grown in nonsaline and saline (200 mM NaCl) conditions. Na and Cl accumulated to the highest levels in xylem parenchyma and epidermal cells, but were maintained at lower concentrations in photosynthetically active mesophyll and bundle sheath cells. Concentrations of Na and Cl in chloroplasts of mesophyll and bundle sheath cells were lower than in their respective vacuoles. No ultrastructural changes were observed in either mesophyll or bundle sheath chloroplasts, and photosynthetic activity was maintained in saline conditions. Salinity tolerance in Rhodes grass is related to specific cellular Na and Cl distributions in leaf tissues, and the ability to regulate Na and Cl concentrations in chloroplasts.

3-D reconstruction of rice leaf tissue for proper estimation of surface area of mesophyll cells and chloroplasts facing intercellular airspaces from 2-D section images.

BACKGROUND AND AIMS: The surface area of mesophyll cells (Smes) and chloroplasts (Sc) facing the intercellular airspace (IAS) are important parameters for estimating photosynthetic activity from leaf anatomy. Although Smes and Sc are estimated based on the shape assumption of mesophyll cells (MCs), it is questionable if the assumption is correct for rice MCs with concave-convex surfaces. Therefore, in this study, we establish a reconstruction method for the 3-D representation of the IAS in rice leaf tissue to calculate the actual Smes and Sc with 3-D images and to determine the correct shape assumption for the estimation of Smes and Sc based on 2-D section images. METHODS: We used serial section light microscopy to reconstruct 3-D representations of the IAS, MCs and chloroplasts in rice leaf tissue. Actual Smes and Sc values obtained from the 3-D representation were compared with those estimated from the 2-D images to find the correct shape-specific assumption (oblate or prolate spheroid) in different orientations (longitudinal and transverse sections) using the same leaf sample. KEY RESULTS: The 3-D representation method revealed that volumes of the IAS and MCs accounted for 30 and 70 % of rice leaf tissue excluding epidermis, respectively, and the volume of chloroplasts accounted for 44 % of MCs. The shape-specific assumption on the sectioning orientation affected the estimation of Smes and Sc using 2-D section images with discrepancies of 10-38 %. CONCLUSIONS: The 3-D representation of rice leaf tissue was successfully reconstructed using serial section light microscopy and suggested that estimation of Smes and Sc of the rice leaf is more accurate using longitudinal sections with MCs assumed as oblate spheroids than using transverse sections with MCs as prolate spheroids.

Three-dimensional ultrastructural change of chloroplasts in rice mesophyll cells responding to salt stress.

BACKGROUND AND AIMS: Excess salinity inhibits the metabolism of various systems and induces structural changes, especially in chloroplasts. Although the chloroplast body seems to swell under salinity stress as observed by conventional transmission electron microscopy, previous studies are limited to 2-D data and lack quantitative comparisons because specimens need to be sliced into ultrathin sections. This study shows three-dimensionally the structural changes in a whole mesophyll cell responding to salinity stress by serial sectioning with a focused ion beam scanning electron microscope (FIB-SEM) and compares the differences in chloroplast structures based on reconstructed models possessing accurate numerical voxel values. METHODS: Leaf blades of rice plants treated with 100 mm NaCl or without (control) for 4 d were fixed chemically and embedded in resin. The specimen blocks were sectioned and observed using the FIB-SEM, and then the sliced image stacks were reconstructed into 3-D models by image processing software. KEY RESULTS: On the transverse sections of rice mesophyll cells, the chloroplasts in the control leaves appeared to be elongated meniscus lens shaped, while those in the salt-treated leaves appear to be expanded oval shaped. The 3-D models based on serial sectioning images showed that the chloroplasts in the control cells spread like sheets fitted to the shape of the cell wall and in close contact with the adjacent chloroplasts. In contrast, those in the salt-stressed cells curled up into a ball and fitted to cell protuberances without being in close contact with adjacent chloroplasts. Although the shapes of chloroplasts were clearly different between the two treatments, their volumes did not differ. CONCLUSIONS: The 3-D reconstructed models of whole rice mesophyll cells indicated that chloroplasts under salt stress conditions were not swollen but became spherical without increasing their volume. This is in contrast to findings of previous studies based on 2-D images.

Interactions of C4 Subtype Metabolic Activities and Transport in Maize Are Revealed through the Characterization of DCT2 Mutants.

C4 photosynthesis in grasses requires the coordinated movement of metabolites through two specialized leaf cell types, mesophyll (M) and bundle sheath (BS), to concentrate CO2 around Rubisco. Despite the importance of transporters in this process, few have been identified or rigorously characterized. In maize (Zea mays), DCT2 has been proposed to function as a plastid-localized malate transporter and is preferentially expressed in BS cells. Here, we characterized the role of DCT2 in maize leaves using Activator-tagged mutant alleles. Our results indicate that DCT2 enables the transport of malate into the BS chloroplast. Isotopic labeling experiments show that the loss of DCT2 results in markedly different metabolic network operation and dramatically reduced biomass production. In the absence of a functioning malate shuttle, dct2 lines survive through the enhanced use of the phosphoenolpyruvate carboxykinase carbon shuttle pathway that in wild-type maize accounts for ∼ 25% of the photosynthetic activity. The results emphasize the importance of malate transport during C4 photosynthesis, define the role of a primary malate transporter in BS cells, and support a model for carbon exchange between BS and M cells in maize.

Three-dimensional ultrastructure of chloroplast pockets formed under salinity stress.

We investigated the invagination structure of a chloroplast that surrounds organelles such as mitochondria and peroxisomes within a thin layer of chloroplast stroma, which is called a chloroplast pocket. In this study, chloroplast pockets were observed in rice plants subjected to salinity stress but not under moderate growth condition. They included cytosol, transparent structure, lipid bodies, mitochondria, and peroxisomes. We constructed the three-dimensional architecture of chloroplast pockets by using serial images obtained by transmission electron microscopy and focused ion beam-scanning electron microscopy. Three types of chloroplast pockets were observed by transmission electron microscopy: Organelles were completely enclosed in a chloroplast pocket (enclosed type), a chloroplast pocket with a small gap in the middle part (gap type), and a chloroplast pocket with one side open (open type). Of the 70 pockets observed by serial imaging, 35 were enclosed type, and 21 and 14 were gap and open types, respectively. Mitochondria and peroxisomes were often in contact with the chloroplast pockets. Focused ion beam-scanning electron microscopy revealed chloroplasts with a sheet structure partially surrounding peroxisomes. This fact suggests that chloroplasts might construct large sheet structures that would be related to the formation of chloroplast pockets.

Rate of augmentation and risk factors with long-term follow-up in Japanese patients with restless legs syndrome.

OBJECTIVES: Preventing augmentation is the critical clinical issue for RLS treatment. As for augmentation in Asian RLS patients, there have been only four studies and the follow-up durations of these studies were not long. We investigated Japanese RLS patients with longer duration of treatment in a clinical setting. METHODS: This study is a retrospective assessment of 42 RLS patients with follow-up durations of longer than 18 months (78.4 ± 29.2, range 19-139) at two urban sleep centers in Osaka, Japan from May 2004 to April 2014. RESULTS: The mean age of first visit was 63.5 ± 14.1 years old and the estimated age of RLS onset was 47.9 ± 16.5 years old. Twenty-eight out of 42 patients were female. At initial evaluation, the mean International Restless Legs Scale score (IRLS score) was 22.0 ± 5.9. Thirty-one of 42 had already visited other clinics before coming to our sleep centers, and the number of clinics visited was 1.3 ± 0.6. Augmentation developed in two patients (4.8%), and the dosage of dopamine equivalent in patients with and without augmentation was 12.5 and 18.8 mg vs. 15.8 ± 17.7 mg. In the two RLS patients with augmentation, ferritin was 113.1 and 114.1 ng/mL, respectively, and the number of clinics before coming to our sleep centers was both three. CONCLUSIONS: The augmentation rate of Japanese RLS patients from our study is low compared with previous Western and Asian studies. It might be attributable to racial difference, lower dosage of dopaminergic treatment, and the level of ferritin.

Three-dimensional intracellular structure of a whole rice mesophyll cell observed with FIB-SEM.

Background and Aims: Ultrathin sections of rice leaf blades observed two-dimensionally using a transmission electron microscope (TEM) show that the chlorenchyma is composed of lobed mesophyll cells, with intricate cell boundaries, and lined with chloroplasts. The lobed cell shape and chloroplast positioning are believed to enhance the area available for the gas exchange surface for photosynthesis in rice leaves. However, a cell image revealing the three-dimensional (3-D) ultrastructure of rice mesophyll cells has not been visualized. In this study, a whole rice mesophyll cell was observed using a focused ion beam scanning electron microscope (FIB-SEM), which provides many serial sections automatically, rapidly and correctly, thereby enabling 3-D cell structure reconstruction. Methods: Rice leaf blades were fixed chemically using the method for conventional TEM observation, embedded in resin and subsequently set in the FIB-SEM chamber. Specimen blocks were sectioned transversely using the FIB, and block-face images were captured using the SEM. The sectioning and imaging were repeated overnight for 200-500 slices (each 50 nm thick). The resultant large-volume image stacks ( x = 25 µm, y = 25 µm, z = 10-25 µm) contained one or two whole mesophyll cells. The 3-D models of whole mesophyll cells were reconstructed using image processing software. Key Results: The reconstructed cell models were discoid shaped with several lobes around the cell periphery. The cell shape increased the surface area, and the ratio of surface area to volume was twice that of a cylinder having the same volume. The chloroplasts occupied half the cell volume and spread as sheets along the cell lobes, covering most of the inner cell surface, with adjacent chloroplasts in close contact with each other. Conclusions: Cellular and sub-cellular ultrastructures of a whole mesophyll cell in a rice leaf blade are demonstrated three-dimensionally using a FIB-SEM. The 3-D models and numerical information support the hypothesis that rice mesophyll cells enhance their CO 2 absorption with increased cell surface and sheet-shaped chloroplasts.

Salinity induces membrane structure and lipid changes in maize mesophyll and bundle sheath chloroplasts.

The membranes of Zea mays (maize) mesophyll cell (MC) chloroplasts are more vulnerable to salinity stress than are those of bundle sheath cell (BSC) chloroplasts. To clarify the mechanism underlying this difference in salt sensitivity, we monitored changes in the glycerolipid and fatty acid compositions of both types of chloroplast upon exposure to salinity stress. The monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) contents were higher in MC chloroplasts than in BSC chloroplasts, in both the presence and absence of salt treatment. Under salt conditions, the MGDG level in MC chloroplasts was significantly lower than under normal conditions, while it was unchanged in BSC chloroplasts. In both types of chloroplast, the contents of DGDG, phosphatidylglycerol and phosphatidylinositol remained at the same levels in control and salt-treated plants, whereas sulfoquinovosyldiacylglycerol and phosphatidylcholine were significantly lower and higher, respectively, upon salt treatment. In addition, the fatty acid composition and double bond index of individual lipid classes were changed by salt treatment in both BSC and MC chloroplasts, although these factors had no effect on glycerolipid content. These findings suggest that the difference in salt sensitivity of MC and BSC chloroplast membranes is related to differences in MGDG responses to salinity. Thus, we propose that the low MGDG content and the low sensitivity of MGDG to salinity in BSC chloroplasts render them more tolerant than MC chloroplasts to salinity stress.

Subjective oropharyngeal symptoms for abnormal swallowing in Japanese patients with obstructive sleep apnea syndrome: a descriptive questionnaire study.

OBJECTIVES: This study aimed to investigate the prevalence of clinical symptoms related to abnormal swallowing in a large sample of obstructive sleep apnea syndrome (OSAS) patients. METHODS: Oropharyngeal symptoms for abnormal swallowing were assessed by a self-administered questionnaire in 507 consecutive patients (females: 65, males: 442; mean age: 49.6 ± 12.6 years old) with clinical symptoms of OSAS, enrolled for cardiorespiratory evaluation. RESULTS: Overall, 16.2% of patients (82/507) had at least one symptom for abnormal swallowing and 6.3% (32/507) had two or more symptoms. The most frequent symptom was difficulty with coughing up phlegm during or after a meal (8.3%). Demographic, sleep, and clinical variables did not differ between the patients with and without abnormal symptoms. CONCLUSIONS: The results of the current study showed that 16% of middle-aged OSAS patients reported pharyngeal symptoms related to abnormal swallowing, regardless of the severity of OSAS.

The soybean mycorrhiza-inducible phosphate transporter gene, GmPT7, also shows localized expression at the tips of vein endings of senescent leaves.

GmPT7 was originally identified as an arbuscular mycorrhiza-inducible gene of soybean that encodes a member of subfamily I in the PHOSPHATE TRANSPORTER 1 family. In the present study, we established conditions under which a number of dwarf soybean plants complete their life cycles in a growth chamber. Using this system, we grew transgenic soybean with a GmPT7 promoter-ß-glucuronidase fusion gene and evaluated GmPT7 expression in detail. GmPT7 was highly expressed in mature, but not in collapsed, arbuscule-containing cortical cells, suggesting its importance in the absorption of fungus-derived phosphate and/or arbuscule development. GmPT7 was also expressed in the columella cells of root caps and in the lateral root primordia of non-mycorrhizal roots. The expression of GmPT7 occurred only in the late stage of phosphorus translocation from leaves to seeds, after water evaporation from the leaves ceased, and later than the expression of GmUPS1-2, GmNRT1.7a and GmNRT1.7b, which are possibly involved in nitrogen export. GmPT7 expression was localized in a pair of tracheid elements at the tips of vein endings of senescent leaves. Transmission electron microscopy revealed that the tip tracheid elements in yellow leaves were still viable and had intact plasma membranes. Thus, we think that GmPT7 on the plasma membranes transports phosphate from the apoplast into the tip elements. GmPT7 knockdown resulted in no significant effects, the function of GmPT7 remaining to be clarified. We propose a working model in which phosphate incorporated in vein endings moves to seeds via xylem to phloem transfer.

Structural changes of mesophyll cells in the rice leaf tissue in response to salinity stress based on the three-dimensional analysis.

Rice leaf blades have intricate-shaped mesophyll cells (MCs) with a large volume of chloroplasts enhancing gas exchange between stroma and intercellular airspace (IAS). Since the rice MCs do not form palisade or spongy tissue cells and are considered monotypic cells, the structural analysis of MCs in the middle part of the leaf tissue has been done, neglecting the various shapes of MCs can be observed on the cross-section of rice leaves. Moreover, the middle MC layer is sandwiched between the upper and lower layers and is more restricted in its demand for light and CO2 entering from the outside. Therefore, the different layers of MCs may differ in their sensitivity to salt stress that causes structural changes in cells. This study aims to elucidate the intra- and extra-cellular structures of MC in different layers of leaf tissue and determine how salinity affects the MC structure in each layer. The mesophyll tissue was divided into adaxial, middle and abaxial layers, and eight MCs and chloroplast regions were selected from each layer and reconstructed into three-dimensional (3D) representations. The whole leaf anatomical and physiological parameters were measured to find the effects of salinity stress on the MC structures. As a result, the 3D analysis of rice leaf tissue revealed the different structures of MCs with greater diversity in the adaxial and abaxial layers than in the middle layer. Salinity stress reduced the size and height of the MCs and coverage of the chloroplast on the cytoplasm periphery of the adaxial and abaxial layers, as well as the chloroplast size of adaxial MCs. Overall, these results reveal the variation of rice MC in leaf tissue and suggest the higher sensitivity to salt stress in the adaxial mesophyll among the layers, which may partly account for the decrease in photosynthetic capacity.

Daridorexant in Japanese patients with insomnia disorder: A phase 3, randomized, double-blind, placebo-controlled study.

OBJECTIVE: This Phase 3 double-blind, placebo-controlled study evaluated the efficacy and safety of daridorexant in Japanese patients with insomnia disorder. PATIENTS/METHODS: 490 patients with insomnia disorder from 95 sites in Japan were randomized to daridorexant 50 mg (n = 163), 25 mg (n = 163) or placebo (n = 164) for 4 weeks, followed by a 7-day placebo run-out and a 30-day safety follow-up. The primary efficacy endpoints, in hierarchical order, were change from baseline at Week 4 in subjective total sleep time (sTST) and subjective latency to sleep onset (sLSO), for daridorexant 50 mg vs placebo. sTST and sLSO were also evaluated (secondary endpoints) for daridorexant 25 mg vs placebo. Safety endpoints included adverse events and next-morning sleepiness (Visual Analog Scale, VAS). RESULTS: Daridorexant 50 mg significantly increased sTST and decreased sLSO versus placebo at Week 4 (least-squares mean difference [LSMD]: sTST 20.3 min [95 % CI 11.4, 29.2] p < 0.001; sLSO -10.7 min [-15.8, -5.5] p < 0.001). Daridorexant 25 mg also significantly improved both endpoints versus placebo (LSMD: sTST 9.2 min [0.3, 18.1] p = 0.042; sLSO -7.2 min [-12.3, -2.0] p = 0.006). Overall incidence of adverse events was similar across groups (50 mg: 22 %; 25 mg: 18 %; placebo 23 %); somnolence, the most common event, increased with increasing dose (50 mg: 6.8 %; 25 mg: 3.7 %; placebo 1.8 %). However, daridorexant did not increase VAS next-morning sleepiness. No rebound or withdrawal-related symptoms were observed after treatment discontinuation. CONCLUSIONS: In Japanese patients with insomnia disorder, daridorexant (25 and 50 mg) was well tolerated and significantly improved subjective sleep outcomes, with no evidence of residual effects.

Long-term safety and efficacy of daridorexant in Japanese patients with insomnia disorder.

OBJECTIVE/BACKGROUND: The short-term efficacy and safety of daridorexant, a dual orexin receptor antagonist, has been demonstrated in Japanese patients with insomnia disorder. The objective of this study was to evaluate, in a non-overlapping patient population to the short-term study, the long-term safety and efficacy of daridorexant in Japanese patients with insomnia disorder. PATIENTS/METHODS: In this Phase 3 open-label study conducted in Japan, 154 patients with insomnia disorder were randomized to daridorexant 50 mg (n = 102) or 25 mg (n = 52) for 52 weeks. The primary objective was to assess the safety and tolerability of daridorexant for up to 1 year. Secondary exploratory objectives were to evaluate the long-term efficacy of daridorexant on subjective sleep parameters (total sleep time, latency to sleep onset and wake after sleep onset) and daytime functioning (Insomnia Daytime Symptoms and Impacts Questionnaire). RESULTS: The incidence of treatment-emergent adverse events (TEAEs) was 74 % and 58 % in the 50 mg and 25 mg groups respectively. No serious drug-related TEAEs were reported. Both doses improved next-morning sleepiness (Visual Analog Scale) throughout the study. Five adjudicated adverse events of special interest were reported; excessive daytime sleepiness (n = 1, 25 mg; n = 2, 50 mg), sleep paralysis (n = 1, 50 mg) and nightmare (n = 1, 25 mg). Improvements in sleep and daytime functioning were maintained from Week 2 (first assessment) through to Week 52 in both dose groups. CONCLUSIONS: Up to 52-weeks, daridorexant was well tolerated with sustained improvement in sleep onset, sleep maintenance and daytime functioning, supporting its long-term use in Japanese patients with insomnia disorder.

Localization of reactive oxygen species and change of antioxidant capacities in mesophyll and bundle sheath chloroplasts of maize under salinity.

In maize, the structure of bundle sheath cell (BSC) chloroplasts is less subject to salinity stress than that of mesophyll cell (MC) chloroplasts. To elucidate the difference in sensitivity to salinity, antioxidant capacities and localization of reactive oxygen species were investigated in both chloroplasts. Transmission electron microscopic observation showed that O2 (-) localization was found in both chloroplasts under salinity, but the accumulation was much greater in MC chloroplasts. H2 O2 localization was observed only in MC chloroplasts of salt-treated plants. In isolated chloroplasts, the activities of superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11) and dehydroascorbate reductase (DHAR, EC 1.8.5.1) were increased by salinity. While the enhancement of SOD activity was similar in both chloroplasts, the increase of APX and DHAR activities were more pronounced in BSC chloroplasts than in MC chloroplasts. Monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) and glutathione reductase (GR, EC 1.6.4.2) were undetectable in BSC chloroplasts, while they increased in MC chloroplasts under salinity. Although ascorbate content increased by salinity only in BSC chloroplasts, glutathione content increased significantly in both chloroplasts, and was higher in MC chloroplasts than in BSC chloroplasts. The content of thiobarbituric acid-reactive substances, which is an indicator of lipid peroxidation, was significantly increased by salinity in both chloroplasts. These results suggested O2 (-) -scavenging capacity was comparable between both chloroplasts, whereas H2 O2 -scavenging capacity was lower in MC chloroplasts than in BSC chloroplasts. Moreover, the increased lipid peroxidation under salinity was associated with the structural alteration in MC chloroplasts, while it had less impact on the structure of BSC chloroplasts.

Negative association between self-reported jaw symptoms and apnea-hypopnea index in patients with symptoms of obstructive sleep apnea syndrome: a pilot study.

OBJECTIVES: Prior to oral appliance therapy for snoring and obstructive sleep apnea syndrome (OSAS), patients are screened for jaw symptoms (e.g., pain). However, the presence of jaw symptoms in a large spectrum of OSAS patients remains unknown. This study aimed to assess the distribution of subjective jaw symptoms in patients with symptoms of OSAS. METHODS: Five hundred and eleven consecutive patients (66 female, 445 male; mean age 49.6 ± 12.6 years) with clinical symptoms of OSAS were enrolled for cardiorespiratory evaluation. Self-administered questionnaires were used to assess jaw symptoms, tooth grinding and clenching during sleep, morning oral dryness, morning heartburn sensation, and pain in the neck and back. RESULTS: The mean apnea-hypopnea (AHI) index was 32.5 ± 30.6 per hour of sleep. Nineteen percent of patients (n = 96) reported at least one jaw symptom. The presence of jaw symptoms was more frequently reported by patients with AHI less than 15 (25 %) than those with AHI of 15 and more (15 %, p = 0.012). In the crude analyses, jaw symptoms were associated with tooth grinding, tooth clenching, morning oral dryness, morning heartburn sensation, and neck/back pain. Multiple logistic regression analysis confirmed that jaw symptoms were associated with AHI less than 15 (odds ratio (OR) 1.99, p = 0.009), tooth clenching (OR 1.79, p = 0.006), morning oral dryness (OR 2.17, p = 0.02), and neck/back pain (OR 1.99, p = 0.005). CONCLUSIONS: Jaw symptoms can be found in 19 % of patients with symptoms of OSAS and are more frequently reported in patients with lower AHI, a patient population for whom oral appliances are often prescribed.

Relationships between respiratory and oromotor events differ between motor phenotypes in patients with obstructive sleep apnea.

Purpose: The present study investigated the relationship between sleep bruxism (SB) and obstructive sleep apnea (OSA) in relation to the sleep architecture. Methods: We conducted a cross-sectional study. Polysomnographic recordings were performed on 36 patients. Sleep, respiratory, and oromotor variables, such as rhythmic masticatory muscle activity (RMMA) and non-specific masticatory muscle activity (NSMA), were compared between OSA patients with or without SB. A correlation analysis of the frequency of respiratory and oromotor events in NREM and REM sleep was performed. The frequency of oromotor events following respiratory events was also assessed. Results: The proportion of REM sleep was higher in OSA patients with SB than in those without SB (p = 0.02). The apnea-hypopnea index (AHI) did not significantly differ between the two groups; however, AHI was approximately 8-fold lower during REM sleep in OSA patients with SB (p = 0.01) and the arousal threshold was also lower (p = 0.04). Although the RMMA index was higher in OSA patients with than in those without SB (p < 0.01), the NSMA index did not significantly differ. The percentage of RMMA following respiratory events was significantly higher in OSA patients with than in those without SB, whereas that of NSMA did not significantly differ. The frequency of oromotor events throughout the whole night positively correlated with AHI. However, regardless of the sleep state, AHI did not correlate with the RMMA index, but positively correlated with the NSMA index. Conclusion: In consideration of the limitations of the present study, the results obtained indicate that OSA patients with SB have a unique phenotype of OSA and also emphasize the distinct relationship of respiratory events with RMMA and NSMA.

The chloroplastic 2-oxoglutarate/malate transporter has dual function as the malate valve and in carbon/nitrogen metabolism.

Transport of dicarboxylates across the chloroplast envelope plays an important role in transferring carbon skeletons to the nitrogen assimilation pathway and exporting reducing equivalent to the cytosol to prevent photo-inhibition (the malate valve). It was previously shown that the Arabidopsis plastidic 2-oxoglutarate/malate transporter (AtpOMT1) and the general dicarboxylate transporter (AtpDCT1) play crucial roles at the interface between carbon and nitrogen metabolism. However, based on the in vitro transport properties of the recombinant transporters, it was hypothesized that AtpOMT1 might play a dual role, also functioning as an oxaloacetate/malate transporter, which is a crucial but currently unidentified component of the chloroplast malate valve. Here, we test this hypothesis using Arabidopsis T-DNA insertional mutants of AtpOMT1. Transport studies revealed a dramatically reduced rate of oxaloacetate uptake into chloroplasts isolated from the knockout plant. CO(2) -dependent O(2) evolution assays showed that cytosolic oxaloacetate is efficiently transported into chloroplasts mainly by AtpOMT1, and supported the absence of additional oxaloacetate transporters. These findings strongly indicate that the high-affinity oxaloacetate transporter in Arabidopsis chloroplasts is AtpOMT1. Further, the knockout plants showed enhanced photo-inhibition under high light due to greater accumulation of reducing equivalents in the stroma, indicating malfunction of the malate valve in the knockout plants. The knockout mutant showed a phenotype consistent with reductions in 2-oxoglutarate transport, glutamine synthetase/glutamate synthase activity, subsequent amino acid biosynthesis and photorespiration. Our results demonstrate that AtpOMT1 acts bi-functionally as an oxaloacetate/malate transporter in the malate valve and as a 2-oxoglutarate/malate transporter mediating carbon/nitrogen metabolism.

Salt-induced chloroplast protrusion is the process of exclusion of ribulose-1,5-bisphosphate carboxylase/oxygenase from chloroplasts into cytoplasm in leaves of rice.

Chloroplast protrusions (CPs) are often observed under environmental stresses, but their role has not been elucidated. The formation of CPs was observed in the leaf of rice plants treated with 75 mm NaCl for 14 d. Some CPs were almost separated from the main chloroplast body. In some CPs, inner membrane structures and crystalline inclusions were included. Similar structures surrounded by double membranes were observed in the cytoplasm and vacuole. Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) was detected in CPs and the similar structures in the cytoplasm and vacuole. These results suggest that CP is one of the pathways of Rubisco exclusion from chloroplasts into the cytoplasm under salinity, and the exclusions could be transported to vacuole for their degradation.

Evaluation of the validity of large-scale serial sectioning TEM for three-dimensional reconstruction of rice mesophyll cells and chloroplasts.

Serial sectioning transmission electron microscopy (ssTEM) is a classical method of 3D reconstruction using serial sections obtained with an ultramicrotome. However, producing a long ribbon with homogeneity is difficult. Here, ultramicrotome movement was suspended after producing a ribbon of 15-30 serial sections (cutting intervals, 100 nm), and then, the ribbon was mounted on an individual one-slot grid. However, as this ssTEM method may include influencing factors such as incorrect intervals of section thickness and distortion of sections, which is produced by cutting sections using a diamond knife and beam interaction under TEM observation, qualitative and quantitative data on rice mesophyll cells and chloroplasts were compared with those obtained from a focused ion beam scanning electron microscopy (FIB-SEM) (cutting intervals, 50 nm). No structural distortion in 3D models was observed. In addition, no significant differences in the volume and surface area were observed between the two methods. The surface to volume ratio was significantly affected by the increase in section thickness, but not the difference of methodologies. Our method was useful for observing large volumes of plant cells and organelles, leading to the identification of various sizes and types of chloroplasts. The formation of a chloroplast pocket, which is a structure surrounding other intracellular compartments, was confirmed in rice leaves grown under moderate growth conditions using the ssTEM method. As only four out of 90 chloroplasts formed pocket structures, the formation was considered to be rare under the applied moderate growth conditions.