Back-Projected Signal-Based Self-Interferometric Phase Analysis Technique for Sea Surface Observation Using a Single Scatterometer System.

This manuscript presents a self-interferometric phase analysis technique for sea surface observation using a single scatterometer system. The self-interferometric phase is proposed to complement the imprecise analysis results due to the very meager signal strength measured at a high incident angle of more than 30°, which is a vulnerability of the existing analysis method using the Doppler frequency based on the backscattered signal strength. Moreover, compared to conventional interferometry, it is characterized by the phase-based analysis using consecutive signals from a single scatterometer system without any auxiliary system or channel. To apply the interferometric signal process on the moving sea surface observation, it is necessary to secure a reference target; however, this is hard to solve in practice. Hence, we adopted the back-projection algorithm to project the radar signals onto a fixed reference position above the sea surface, where the theoretical model for extracting the self-interferometric phase was derived from the radar-received signal model applying the back-projection algorithm. The observation performance of the proposed method was verified using the raw data collected at the Ieodo Ocean Research Station in Republic of Korea. In the observation result for wind velocity at the high incident angles of 40° and 50°, the self-interferometric phase analysis technique shows a better performance of a correlation coefficient of more than about 0.779 and an RMSE (root-mean-square error) of about 1.69 m/s compared to the existing method of a correlation coefficient of less than 0.62 and RMSE of more than 2.46 m/s.

Multifunctional Scatterometer System for Measuring Physical Oceanographic Parameters Using Range-Doppler FMCW Radar.

A multifunctional scatterometer system and optimized radar signal processing for simultaneous observation of various physical oceanographic parameters are described in this paper. Existing observation methods with microwave remote sensing techniques generally use several separate systems such as scatterometer, altimeter, and Doppler radar for sea surface monitoring, which are inefficient in system operation and cross-analysis of each observation data. To improve this point, we integrated separate measurement functions into a single observation system by adding a measurement function of Doppler frequency to the existing system. So it enables to simultaneously measure the range and polarimetric responses of backscattering as well as movements of the sea surface. Here, the simultaneous measurement function of Doppler frequency was implemented by sampling an FMCW (frequency modulated continuous wave) radar signal as 2D raw data consisting of fast- and slow-time samples, i.e., the range and backscattering of radar target signals are analyzed from the fast-time samples while the Doppler frequency by the radar target's movement extracts from the slow-time samples. Through the Fourier transformed-based range-Doppler signal process, distance (R), backscattering (σ°), and Doppler frequency (fD) are sequentially extracted from the 2D raw data, and a correlation to the physical oceanographic parameters is analyzed. Operability of the proposed system was examed through total 3 times of field campaigns from June 2017 to August 2020 and the observation data retrieved by the radar measurement data (R, σ°, fD) was also cross-analyzed with in-situ data: e.g., tide, significant wave height, and wind speed and direction. Differences in the comparative results as an observational accuracy are as follows. Tidal level (Root Mean Square Error 0.169 m (R)), significant wave height (RMSE 0.127 m (R), 0.362 m (σ°)), wind speed (RMSE 1.880 m/s (fD), 2.094 m/s (σ°)) and direction (18.84° (fD)).

Sea Surface Imaging with a Shortened Delayed-Dechirp Process of Airborne FMCW SAR for Ocean Monitoring on Emergency.

A sea surface imaging technique for an emergency response using a ready-made frequency modulated continuous wave-synthetic aperture radar (FMCW SAR) system and its experimental results are described in this paper. The optimal range of radiowave incidence angle for sea surface imaging was analyzed by a theoretical scattering model and measurement data, and it was properly applied to the FMCW SAR system by readjusting the delayed-dechirp process. Raw data acquired through flight experiments were reconstructed to SAR image by the range-doppler algorithm. To verify the performance of the reconstructed sea surface image, dual-channel images collected by the configuration of the along-track interferometry were used, and then performance indicators such as signal attenuation, coherence, and phase difference were analyzed. Through this experimental study, it was confirmed that the ready-made FMCW SAR system without a function of the incident angle control can also conduct limited missions for maritime observation. It is possible to be an alternative resource for emergency response, in which the cases are requiring urgent maritime disaster detection and analysis.

JBIR-107, a new metabolite from the marine-sponge-derived actinomycete, Streptomyces tateyamensis NBRC 105047.

As part of our chemical screening program for new microbial secondary metabolites, we discovered a new compound, JBIR-107 (1), from the culture of Streptomyces tateyamensis NBRC 105047 isolated from a marine sponge sample. Extensive NMR and MS spectroscopic data enabled the structure of 1 to be determined as 5-acetamido-6-(4-(methyl(2-oxo-3-phenylpropyl)amino)phenyl)-4-oxohexanoic acid.

JBIR-129 and -139, cytotoxic 34-membered polyol macrolides of microbial origin.

New 34-membered polyol macrolides JBIR-129 (1) and JBIR-139 (2) were isolated from the culture of the terrestrial Streptomyces RK74. The planar structures of 1 and 2 were established on the basis of 1D and 2D NMR, ESI-TOF-MS, IR, and UV spectra. The relative configurations of the sugar units were determined by analyzing vicinal ¹H-¹H coupling constants and steric information. Both 1 and 2 showed cytotoxic activity against human ovarian adenocarcinoma SKOV-3 cells with IC50 values of 0.3 and 0.4 µM, respectively.

Tyrosyl-DNA phosphodiesterase 1 inhibitor from an anamorphic fungus.

Tyrosyl-DNA phosphodiesterase 1 (Tdp1) is an enzyme that catalyzes hydrolysis of 3'-phosphotyrosyl bonds and is involved in repair of irreversible topoisomerase I (Top1)-DNA covalent complexes. Tdp1 inhibitors are regarded as potential cancer therapeutics in combination with Top1 inhibitors, which are currently used to treat human cancers. While screening for Tdp1 inhibitors, we discovered a novel compound, JBIR-21 (1), from the culture of an anamorphic fungus, RF-13305. The structure of 1 was established by extensive NMR and MS analyses. Compound 1 showed inhibitory activity against Tdp1 (IC(50) value, 18 µM) and cytotoxic activity against cancer cell lines (IC(50) values, 3.5-13 µM). Compound 1 also exhibited antitumor activity in a mouse xenograft model without adverse effects.

Antiphased dust deposition and productivity in the Antarctic Zone over 1.5 million years.

The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report a high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our deep-ocean records cover the last 1.5 Ma, thus doubling that from Antarctic ice-cores. We find a 5 to 15-fold increase in dust deposition during glacials and a 2 to 5-fold increase in biogenic silica deposition, reflecting higher ocean productivity during interglacials. This antiphasing persisted throughout the last 25 glacial cycles. Dust deposition became more pronounced across the Mid-Pleistocene Transition (MPT) in the Southern Hemisphere, with an abrupt shift suggesting more severe glaciations since ~0.9 Ma. Productivity was intermediate pre-MPT, lowest during the MPT and highest since 0.4 Ma. Generally, glacials experienced extended sea-ice cover, reduced bottom-water export and Weddell Gyre dynamics, which helped lower atmospheric CO2 levels.

Ancient marine sediment DNA reveals diatom transition in Antarctica.

Antarctica is one of the most vulnerable regions to climate change on Earth and studying the past and present responses of this polar marine ecosystem to environmental change is a matter of urgency. Sedimentary ancient DNA (sedaDNA) analysis can provide such insights into past ecosystem-wide changes. Here we present authenticated (through extensive contamination control and sedaDNA damage analysis) metagenomic marine eukaryote sedaDNA from the Scotia Sea region acquired during IODP Expedition 382. We also provide a marine eukaryote sedaDNA record of ~1 Mio. years and diatom and chlorophyte sedaDNA dating back to ~540 ka (using taxonomic marker genes SSU, LSU, psbO). We find evidence of warm phases being associated with high relative diatom abundance, and a marked transition from diatoms comprising <10% of all eukaryotes prior to ~14.5 ka, to ~50% after this time, i.e., following Meltwater Pulse 1A, alongside a composition change from sea-ice to open-ocean species. Our study demonstrates that sedaDNA tools can be expanded to hundreds of thousands of years, opening the pathway to the study of ecosystem-wide marine shifts and paleo-productivity phases throughout multiple glacial-interglacial cycles.

Episodes of Early Pleistocene West Antarctic Ice Sheet Retreat Recorded by Iceberg Alley Sediments.

Ice loss in the Southern Hemisphere has been greatest over the past 30 years in West Antarctica. The high sensitivity of this region to climate change has motivated geologists to examine marine sedimentary records for evidence of past episodes of West Antarctic Ice Sheet (WAIS) instability. Sediments accumulating in the Scotia Sea are useful to examine for this purpose because they receive iceberg-rafted debris (IBRD) sourced from the Pacific- and Atlantic-facing sectors of West Antarctica. Here we report on the sedimentology and provenance of the oldest of three cm-scale coarse-grained layers recovered from this sea at International Ocean Discovery Program Site U1538. These layers are preserved in opal-rich sediments deposited ∼1.2 Ma during a relatively warm regional climate. Our microCT-based analysis of the layer's in-situ fabric confirms its ice-rafted origin. We further infer that it is the product of an intense but short-lived episode of IBRD deposition. Based on the petrography of its sand fraction and the Phanerozoic 40Ar/39Ar ages of hornblende and mica it contains, we conclude that the IBRD it contains was likely sourced from the Weddell Sea and/or Amundsen Sea embayment(s) of West Antarctica. We attribute the high concentrations of IBRD in these layers to "dirty" icebergs calved from the WAIS following its retreat inland from its modern grounding line. These layers also sit at the top of a ∼366-m thick Pliocene and early Pleistocene sequence that is much more dropstone-rich than its overlying sediments. We speculate this fact may reflect that WAIS mass-balance was highly dynamic during the ∼41-kyr (inter)glacial world.

Arctigenin blocks the unfolded protein response and shows therapeutic antitumor activity.

Cancer cells in poorly vascularized solid tumors are constantly or intermittently exposed to stressful microenvironments, including glucose deprivation, hypoxia, and other forms of nutrient starvation. These tumor-specific conditions, especially glucose deprivation, activate a signaling pathway called the unfolded protein response (UPR), which enhances cell survival by induction of the stress proteins. We have established a screening method to discover anticancer agents that could preferentially inhibit tumor cell viability under glucose-deprived conditions. Here we identify arctigenin (ARC-G) as an active compound that shows selective cytotoxicity and inhibits the UPR during glucose deprivation. Indeed, ARC-G blocked expression of UPR target genes such as phosphorylated-PERK, ATF4, CHOP, and GRP78, which was accompanied by enhanced phosphorylation of eIF2 alpha during glucose deprivation. The UPR inhibition led to apoptosis involving a mitochondrial pathway by activation of caspase-9 and -3. Furthermore, ARC-G suppressed tumor growth of colon cancer HT-29 xenografts. Our results demonstrate that ARC-G can be served as a novel type of antitumor agent targeting the UPR in glucose-deprived solid tumors.

JBIR-66, a new metabolite isolated from tunicate-derived Saccharopolyspora sp. SS081219JE-28.

In the course of our chemical screening program for new secondary metabolites, we isolated a new compound JBIR-66 (1) from the culture broth of the tunicate-derived actinomycete, Saccharopolyspora sp. SS081219JE-28. The structure of 1 was determined to be (3Z,6E,8E)-N-(4-acetamido-3-hydroxybutyl)-2-hydroxy-4,8-dimethylundeca-3,6,8-trienamide on the basis of extensive NMR and MS spectroscopic data.

Seasonal contrast of particulate organic carbon (POC) characteristics in the Geum and Seomjin estuary systems (South Korea) revealed by carbon isotope (δ13C and Δ14C) analyses.

In this study, we newly investigated surface water samples collected in two contrasting Korean estuary systems (i.e., closed Geum and open Seomjin estuaries) along a salinity gradient in winter (December) in 2016. The main objectives were to determine the source of particulate organic carbon (POC) in winter and to assess the environmental factors inducing seasonal differences in POC characteristics. Concentrations and dual carbon isotopes (δ13C and Δ14C) of POC were analyzed together with concentrations and stable carbon isotopes (δ13C) of dissolved inorganic carbon (DIC) and compared with those obtained in summer (August) in 2016. Our study provided a new insight that for both estuarine systems, the seasonal contrast in POC characteristics was associated with stronger wind-induced estuarine sediment resuspensions in winter than in summer providing a greater contribution of aged POC to the total POC pool in winter.

Etoposide-resistant HT-29 human colon carcinoma cells during glucose deprivation are sensitive to piericidin A, a GRP78 down-regulator.

Glucose deprivation, a pathophysiological cell condition, causes up-regulation of GRP78 and induction of etoposide resistance in human cancer cells. The induction of drug resistance can be partly explained by the fact that GRP78 can block activation of caspase-7 induced by treatment with etoposide. Therefore, downregulating GRP78 expression may be a novel strategy anticancer drug development. Based on that premise, we established a screening program for anticancer agents that exhibit preferential cytotoxic activity for etoposide-resistant cancer cells under glucose-deprived conditions. We recently isolated an active compound, AR-054, from the culture broth of Streptomyces sp., which prevents stress-induced etoposide resistance in vitro. AR-054 was identified as piericidin A, a prototypical compound, by ESI-MS analysis and various NMR spectroscopic methods. Here, we showed that piericidin A suppressed the accumulation of GRP78 protein and was also highly toxic to etoposide-resistant HT-29 cells, with IC50 values for colony formation of 6.4 and 7.7 nM under 2-deoxyglucose supplemented and glucose-deprived conditions, respectively. Interestingly, piericidin A had no effect under normal growth conditions. Therefore, we suggest that piericidin A prevents up-regulation of GRP78, and exhibits cytotoxicity in glucose-deprived HT-29 cells that are resistant to etoposide.

Glucose-deprived HT-29 human colon carcinoma cells are sensitive to verrucosidin as a GRP78 down-regulator.

Glucose deprivation, a feature of poorly vascularized solid tumors, activates the unfolded protein response (UPR) which is a stress-signaling pathway in tumor cells that is associated with the molecular chaperone GRP78 and induction of GRP78 has been shown to protect them against programmed cell death. Thus, targeting glucose-deprived conditions may be a novel strategy in anticancer drug development. Based on that, we established a novel screening program for chaperone modulators that preferentially cytotoxic activity in cancer cells under glucose-deprived conditions. During the course of our screening system, we recently isolated an active compound, 326-2, from Penicillium verrucosum var. cyclopium and identified it as a down-regulator of the grp78 gene. As expected, 326-2 inhibited the expression of the GRP78 promoter under glucose-deprived conditions in a dose-dependent manner with an IC(50) value of 50nM. Furthermore, 326-2 was identified as verrucosidin, a pyrone-type polyketide, by ESI-MS analyses and various NMR spectroscopic methods. We found that verrucosidin prevents UPR-induced expression of protein, such as GRP78, whose expression is induced by glucose-deprived or by 2-deoxyglucose; this effect is not seen under normal growth conditions. The GRP78-inhibitory action of verrucosidin was dependent on strict hypoglycemic conditions and resulted in selective cell death of glucose-deprived HT-29 human colon cancer cells.

Effect of methanolic extract from silkworm droppings on proliferation and caspase activity in HT-29 human colon cancer cells.

Colorectal cancer is the third most common cause of cancer-related deaths in the world. Surgical intervention followed by chemotherapy remains the primary approach to treatment since colon cancers remain refractory to most chemotherapeutic agents. Based on that, we established a program to screen natural products for cytotoxic activity, employing the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay system utilizing HT-29 human colon cancer cells. During the course of our screening, we found that the methanolic extract of silkworm droppings (SDME) has cytotoxic effects on HT-29 cells. In the present study, we investigated the possible mechanisms by which SDME exerts its antiproliferative activity in HT-29 cells. As expected, SDME inhibited growth of HT-29 cells in a dose-dependent manner as assessed by the MTT reduction assay, the lactate dehydrogenase release assay, and the colony formation assay. We also investigated whether the apoptotic effects induced by SDME involve the caspase pathway using the caspase colorimetric assay. Interestingly, caspase-9 and -3, but not caspase-8, were activated in response to SDME treatment. Taken together, these results clearly indicate that the induction of apoptosis by SDME involves a mitochondrial-mediated pathway and strongly suggest that SDME may potentially be a chemotherapeutic agent for human colon cancer.

Methanolic extracts of Plocamium telfairiae induce cytotoxicity and caspase-dependent apoptosis in HT-29 human colon carcinoma cells.

Natural marine products have recently become the focus of increased research interest, due to their potential pharmacological activities. Therefore, we have screened 50 varieties of marine seaweed and determined that the methanolic extracts from Plocamium telfairiae (PTE) exhibited a cytotoxic effect against HT-29 human colon carcinoma cells. In this study, we report on the cytotoxic activity and mechanism of PTE-induced apoptosis in HT-29 cells. The treatment of HT-29 cells with various PTE concentrations resulted in the inhibition of growth and the induction of apoptosis in a dose-dependent manner, as determined by the results of a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay, a lactate dehydrogenase release assay, a morphological assay, and a colony formation assay. Interestingly, we also detected apoptotic bodies on Hoechst staining and attempted to determine whether the PTE-induced apoptosis involved the caspase pathway, using a caspase colorimetric assay. The activation of caspases-8, -9, -3, and -7 and the specific proteolytic cleavage of poly(ADP-ribose) polymerase were detected over the course of apoptosis induction. Our results showed that PTE may function as a chemopreventive and/or chemotherapeutic agent in colon carcinoma cells via the reduction of cell viability and the induction of apoptosis.

Mithramycin inhibits etoposide resistance in glucose-deprived HT-29 human colon carcinoma cells.

Physiological cell conditions such as glucose deprivation and hypoxia play roles in the development of drug resistance in solid tumors. These tumor-specific conditions cause decreased expression of DNA topoisomerase IIalpha, rendering cells resistant to topo II target drugs such as etoposide. Thus, targeting tumor-specific conditions such as a low glucose environment may be a novel strategy in the development of anticancer drugs. On this basis, we established a novel screening program for anticancer agents with preferential cytotoxic activity in cancer cells under glucose-deprived conditions. We recently isolated an active compound, AA-98, from Streptomyces sp. AA030098 that can prevent stress-induced etoposide resistance in vitro. Furthermore, LC-MS and various NMR spectroscopic methods identified AA-98 as mithramycin, which belongs to the aureolic acid group of antitumor compounds. We found that mithramycin prevents the etoposide resistance that is induced by glucose deprivation. The etoposide-chemosensitive action of mithramycin was just dependent on strict low glucose conditions, and resulted in the selective cell death of etoposide-resistant HT-29 human colon cancer cells.

Advanced Interval Type-2 Fuzzy Sliding Mode Control for Robot Manipulator.

In this paper, advanced interval type-2 fuzzy sliding mode control (AIT2FSMC) for robot manipulator is proposed. The proposed AIT2FSMC is a combination of interval type-2 fuzzy system and sliding mode control. For resembling a feedback linearization (FL) control law, interval type-2 fuzzy system is designed. For compensating the approximation error between the FL control law and interval type-2 fuzzy system, sliding mode controller is designed, respectively. The tuning algorithms are derived in the sense of Lyapunov stability theorem. Two-link rigid robot manipulator with nonlinearity is used to test and the simulation results are presented to show the effectiveness of the proposed method that can control unknown system well.

Enhanced adjuvantic property of polymerized liposome as compared to a phospholipid liposome.

Liposome, although intensively researched as vaccine or drug delivery vehicle, has been of limited use due to the low and unpredictable long-term stability. In order to overcome such problems, polymerized liposome (PL) that could initiate polymerization under very mild reaction condition was examined and compared to a conventional liposome. The polymerizable lipid, 1,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphorylcholine (DLL), was synthesized according to the literature, and 1,2-distearoyl-sn-glycero-3-phosphorylcholine (DSPC) was used as the conventional lipid counterpart. Polymerization of liposome was as easy and convenient as just shaking in pH 7.4 buffer. The protein encapsulation efficiency of DLL was higher than that of DSPC, and its protein release rate was lower. Immunoglobulin G (IgG) activity examined after intraperitoneal injection of antigen encapsulated by either DLL or DSPC showed that ca. 2 times as much antibody was formed by DLL-encapsulated lysozyme compared with DSPC-encapsulated form. The reasons for the superior adjuvantic properties of DLL and its future application as a drug delivery system are briefly discussed.

Induction of tubulin polymerization and apoptosis in malignant mesothelioma cells by a new compound JBIR-23.

Malignant pleural mesothelioma (MPM) is a highly aggressive tumor with a poor prognosis. Thus, novel therapeutic agents need to be developed for treating it. We recently reported the isolation of the novel anti-MPM compound designated as JBIR-23 from Streptomyces sp. AK-AB27. In this study, JBIR-23 exerted its cytotoxic effect on MPM cells by promotion of tubulin polymerization and G2/M arrest, which was followed by apoptosis induction via the caspase pathway through phosphorylation of p38 mitogen-activated protein kinase and c-jun N-terminal kinase. Furthermore, in vivo analysis demonstrated that JBIR-23 prevented tumor growth in tumor-bearing nude mice without evident side effects.