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1.
Hum Cell ; 37(2): 491-501, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38184488

ABSTRACT

Neoadjuvant chemotherapy (NAC) followed by surgery is a standard approach for management of locally advanced esophageal squamous cell carcinoma (ESCC). Patients who do not respond well to NAC have a poor prognosis. Despite extensive research, the mechanisms of chemoresistance in ESCC remain largely unknown. Here, we established paired tumor organoids-designated as PreNAC-O and PostNAC-O-from one ESCC patient before and after NAC, respectively. Although the two organoids did not exhibit significant differences in proliferation, morphology or drug sensitivity in vitro, the tumorigenicity of PostNAC-O in vivo was significantly higher than that of PreNAC-O. Xenografts from PreNAC-O tended to exhibit keratinization, while those from PostNAC-O displayed conspicuous necrotic areas. The tumorigenicity of PostNAC-O xenografts during the chemotherapy was comparable to that of PreNAC-O without treatment. Furthermore, the gene expression profiles of the xenografts suggested that expression of genes involved in the EMT and/or hypoxia response might be related to the tumorigenicity of PostNAC-O. Our data suggested that the tumorigenicity of residual cancer had been enhanced, outweighing the effects of chemotherapy, rather than being attributable to intrinsic chemoresistance. Further studies are required to clarify the extent to which residual cancers share a common mechanism similar to that revealed here.


Subject(s)
Esophageal Neoplasms , Esophageal Squamous Cell Carcinoma , Humans , Esophageal Squamous Cell Carcinoma/drug therapy , Esophageal Squamous Cell Carcinoma/genetics , Esophageal Squamous Cell Carcinoma/pathology , Esophageal Neoplasms/drug therapy , Esophageal Neoplasms/genetics , Esophageal Neoplasms/metabolism , Neoplasm, Residual , Neoadjuvant Therapy , Organoids/pathology
2.
Pathobiology ; 91(2): 121-131, 2024.
Article in English | MEDLINE | ID: mdl-37797604

ABSTRACT

INTRODUCTION: We have previously reported that overexpression of visinin-like protein 1 (VSNL1) is frequently observed in advanced colorectal adenocarcinomas and correlates with poorer prognosis. In this study, we determined the levels of VSNL1 expression in the earlier stages of colorectal tumors including adenomas and adenocarcinomas, and attempted to clarify the functional significance of VSNL1 overexpression in colorectal carcinogenesis. METHODS: Levels of VSNL expression in colorectal tumor tissues were analyzed using immunohistochemistry. The effects of VSNL1 downregulation and overexpression on cell proliferation, resistance to apoptosis, and invasiveness were determined using two VSNL1-overexpressing colorectal cancer cell lines, CW-2 and HCT-116 and VSNL1 inducibly expressing SNU-C5, respectively. Gene expression signatures in VSNL1-downregulated CW-2 and HCT-116 were identified using transcriptome and gene set enrichment analyses. RESULTS: VSNL1 expression was restricted to only a few crypt cells in the non-tumorous epithelium, whereas it became enhanced in adenomas and adenocarcinomas with the progression of tumorigenesis. Downregulation of VSNL1 in CW-2 and HCT-116 cells suppressed their proliferation through induction of apoptosis. Conversely, overexpression of VSNL1 in SNU-C5 cells enhanced resistance to anoikis. Transcriptome and gene set enrichment analyses revealed that downregulation of VSNL1 altered the expression level of the apoptosis-related gene set in CW-2 and HCT-116 cells. CONCLUSION: VSNL1 plays a role in both the development and progression of colorectal tumors by enhancing cell viability.


Subject(s)
Adenocarcinoma , Adenoma , Colorectal Neoplasms , Humans , Carcinogenesis/genetics , Apoptosis/genetics , Cell Proliferation , HCT116 Cells , Colorectal Neoplasms/genetics , Colorectal Neoplasms/pathology , Adenocarcinoma/genetics , Adenoma/genetics , Gene Expression Regulation, Neoplastic , Neurocalcin/genetics , Neurocalcin/metabolism
3.
Cancers (Basel) ; 15(16)2023 Aug 15.
Article in English | MEDLINE | ID: mdl-37627132

ABSTRACT

Prediction of therapeutic outcomes is important for cancer patients in order to reduce side effects and improve the efficacy of anti-cancer drugs. Currently, the most widely accepted method for predicting the efficacy of anti-cancer drugs is gene panel testing based on next-generation sequencing. However, gene panel testing has several limitations. For example, only 10% of cancer patients are estimated to have druggable mutations, even if whole-exome sequencing is applied. Additionally, even if optimal drugs are selected, a significant proportion of patients derive no benefit from the indicated drug treatment. Furthermore, most of the anti-cancer drugs selected by gene panel testing are molecularly targeted drugs, and the efficacies of cytotoxic drugs remain difficult to predict. Apart from gene panel testing, attempts to predict chemotherapeutic efficacy using ex vivo cultures from cancer patients have been increasing. Several groups have retrospectively demonstrated correlations between ex vivo drug sensitivity and clinical outcome. For ex vivo culture, surgically resected tumor tissue is the most abundant source. However, patients with recurrent or metastatic tumors do not usually undergo surgery, and chemotherapy may be the only option for those with inoperable tumors. Therefore, predictive methods using small amounts of cancer tissue from diagnostic materials such as endoscopic, fine-needle aspirates, needle cores and liquid biopsies are needed. To achieve this, various types of ex vivo culture and endpoint assays using effective surrogate biomarkers of drug sensitivity have recently been developed. Here, we review the variety of ex vivo cultures and endpoint assays currently available.

4.
Chem Pharm Bull (Tokyo) ; 71(2): 175-182, 2023.
Article in English | MEDLINE | ID: mdl-36724980

ABSTRACT

Palladium-catalyzed, hydroxy-group-directed C-H arylation of [1,1'-biphenyl]-2-ols with chloroarenes was performed. The reaction showed a broad substrate scope and was successfully applied to pharmaceuticals containing a chloro group. Using 2-heteroarylphenols instead of [1,1'-biphenyl]-2-ols also yielded the desired products. The arylated product was further transformed into a triphenylene derivative.


Subject(s)
Biphenyl Compounds , Palladium , Molecular Structure , Catalysis
5.
Lab Invest ; 103(6): 100105, 2023 06.
Article in English | MEDLINE | ID: mdl-36842278

ABSTRACT

Patient-derived tumor organoids have considerable potential as an in vitro diagnostic tool for drug susceptibility testing. In the present study, we investigated whether bile collected for diagnostic purposes could be a potential source for the establishment of biliary cancer organoids. Among 68 cases of biliary cancer, we successfully generated 60 bile-derived organoids (BDOs) from individual patients. Consistent with previous reports that described biliary cancer organoids from surgical tissues, the BDOs showed diverse morphologies such as simple cysts, multiloculated cysts, thick capsulated cysts, and solid masses. They also harbored mutations in KRAS and TP53 at frequencies of 15% and 55%, respectively. To enrich the cancer organoids by removing contaminated noncancerous components of BDOs, we attempted to verify the effectiveness of 3 different procedures, including repeat passage, xenografting, and selection with an MDM2 inhibitor for TP53 mutation-harboring BDOs. By monitoring the sequence and expression of mutated TP53, we found that all these procedures successfully enriched the cancer organoids. Our data suggest that BDOs can be established with minimal invasiveness from almost all patients with biliary cancers, including inoperable cases. Thus, despite some limitations with respect to the characterization of BDOs and methods for the enrichment of cancer cell-derived organoids, our data suggest that BDOs could have potential applications in personalized medicine.


Subject(s)
Cysts , Mycobacterium tuberculosis , Humans , Bile/metabolism , Microbial Sensitivity Tests , Organoids/pathology , Cysts/metabolism , Cysts/pathology
6.
Cancer Sci ; 114(5): 2189-2202, 2023 May.
Article in English | MEDLINE | ID: mdl-36694355

ABSTRACT

Constitutive activation of the mitogen-activated protein kinase (MAPK) signaling pathway is essential for tumorigenesis of pancreatic ductal adenocarcinoma (PDAC). To date, however, almost all clinical trials of inhibitor targeting this pathway have failed to improve the outcome of patients with PDAC. We found that implanted MIA Paca2, a human PDAC cell line sensitive to a MAPK inhibitor, PD0325901, became refractory within a week after treatment. By comparing the expression profiles of MIA Paca2 before and after acquisition of the refractoriness to PD0325901, we identified clusterin (CLU) as a candidate gene involved. CLU was shown to be induced immediately after treatment with PD0325901 or expressed primarily in more than half of PDAC cell lines, enhancing cell viability by escaping from apoptosis. A combination of PD0325901 and CLU downregulation was found to synergistically or additively reduce the proliferation of PDAC cells. In surgically resected PDAC tissues, overexpression of CLU in cancer cells was observed immunohistochemically in approximately half of the cases studied. Collectively, our findings highlight the mechanisms responsible for the rapid refractory response to MEK inhibitor in PDAC cells, suggesting a novel therapeutic strategy that could be applicable to patients with PDAC using inhibitor targeting the MAPK signaling pathway and CLU.


Subject(s)
Carcinoma, Pancreatic Ductal , Pancreatic Neoplasms , Humans , Clusterin/genetics , Clusterin/metabolism , Clusterin/therapeutic use , Pancreatic Neoplasms/drug therapy , Pancreatic Neoplasms/genetics , Pancreatic Neoplasms/metabolism , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic use , Carcinoma, Pancreatic Ductal/drug therapy , Carcinoma, Pancreatic Ductal/genetics , Carcinoma, Pancreatic Ductal/metabolism , Mitogen-Activated Protein Kinases , Mitogen-Activated Protein Kinase Kinases , Cell Line, Tumor , Cell Proliferation , Pancreatic Neoplasms
7.
DEN Open ; 3(1): e203, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36568965

ABSTRACT

A 74-year-old man was diagnosed with unresectable pancreatic cancer with obstructive jaundice. Chemotherapy with gemcitabine and nab-paclitaxel was initiated after placement of a duckbill-shaped anti-reflux metal stent (D-ARMS). A period of 1 month after D-ARMS placement, the patient developed hematemesis and entered severe shock following emergency admission for further evaluation. Contrast-enhanced computed tomography revealed a pseudoaneurysm in the gastroduodenal artery, coincident with the site of D-ARMS placement, and bleeding from the same site was diagnosed. Angiography was performed, and the pseudoaneurysm was successfully treated by transcatheter arterial embolization using coils. The patient was subsequently discharged from hospital and experienced no further bleeding until his death due to an aggravation of the pancreatic cancer after 2 months. We report a case of pancreatic cancer with pseudoaneurysm after D-ARMS placement.

8.
J Imaging ; 8(11)2022 Nov 02.
Article in English | MEDLINE | ID: mdl-36354872

ABSTRACT

Parkinson's disease is characterized by motor dysfunction caused by functional deterioration of the substantia nigra. Lower putamen volume (i.e., putamen atrophy) may be an important clinical indicator of motor dysfunction and neurological symptoms, such as autonomic dysfunction, in patients with Parkinson's disease. We proposed and applied a new evaluation method for putamen volume measurement on 31 high-resolution T2-weighted magnetic resonance images from 16 patients with Parkinson's disease (age, 80.3 ± 7.30 years; seven men, nine women) and 30 such images from 19 control participants (age, 75.1 ± 7.85 years; eleven men, eight women). Putamen atrophy was expressed using a ratio based on the thalamus. The obtained values were used to assess differences between the groups using the Wilcoxon rank-sum test. The intraclass correlation coefficient showed sufficient intra-rater reliability and validity of this method. The Parkinson's disease group had a significantly lower mean change ratio in the putamen (0.633) than the control group (0.719), suggesting that putamen atrophy may be identified using two-dimensional images. The evaluation method presented in this study may indicate the appearance of motor dysfunction and cognitive decline and could serve as a clinical evaluation index for Parkinson's disease.

9.
BMC Gastroenterol ; 22(1): 490, 2022 Nov 28.
Article in English | MEDLINE | ID: mdl-36437464

ABSTRACT

BACKGROUND: Although eradication therapy for chronic Helicobacter pylori (H. pylori) reduces the risk of gastric cancer (GC), its effectiveness is not complete. Therefore, it is also critically important to identifying those patients who remain at high risk after H. pylori eradication therapy. Accumulation of protein methylation is strongly implicated in cancer, and recent study showed that dimethylation of eEF1A lysine 55 (eEF1AK55me2) promotes carcinogenesis in vivo. We aimed to investigate the relationship between eEF1A dimethylation and H. pylori status, efficacy of eradication therapy, and GC risk in H. pylori-eradicated mucosa, and to reveal the potential downstream molecules of eEF1A dimethylation. METHODS: Records of 115 patients (11 H. pylori-negative, 29 H. pylori-positive, 75 post-eradication patients) who underwent upper gastrointestinal endoscopy were retrospectively reviewed. The eEF1A dimethyl level was evaluated in each functional cell type of gastric mucosa by immunofluorescent staining. We also investigated the relationship between eEF1AK55me2 downregulation by CRISPR/Cas9 mediated deletion of Mettl13, which is known as a dimethyltransferase of eEF1AK55me2. RESULTS: The level of eEF1A dimethylation significantly increased in the surface and basal areas of H. pylori-positive mucosa compared with the negative mucosa (surface, p = 0.0031; basal, p = 0.0036, respectively). The eEF1A dimethyl-levels in the surface area were significantly reduced by eradication therapy (p = 0.005), but those in the basal area were maintained even after eradication therapy. Multivariate analysis revealed that high dimethylation of eEF1A in the basal area of the mucosa was the independent factor related to GC incidence (odds ratio = 3.6611, 95% confidence interval = 1.0350-12.949, p = 0.0441). We also showed the relationship between eEF1A dimethylation and expressions of reprogramming factors, Oct4 and Nanog, by immunohistochemistry and in vitro genome editing experiments. CONCLUSIONS: The results indicated that H. pylori infection induced eEF1A dimethylation in gastric mucosa. The accumulation of dimethyl-eEF1A in the basal area of the mucosa might contribute to GC risk via regulation of reprograming factors in H. pylori eradicated-gastric mucosa.


Subject(s)
Helicobacter pylori , Stomach Neoplasms , Humans , Stomach Neoplasms/genetics , Stomach Neoplasms/metabolism , Lysine/metabolism , Retrospective Studies , Gastric Mucosa/metabolism
10.
Lab Invest ; 102(12): 1355-1366, 2022 12.
Article in English | MEDLINE | ID: mdl-35922477

ABSTRACT

Despite recent advances in sequencing technology and large-scale drug screenings employing hundreds of cell lines, the predictive accuracy of mutation-based biomarkers is still insufficient as a guide for cancer therapy. Therefore, novel types of diagnostic methods using alternative biomarkers would be highly desirable. We have hypothesized that sensitivity-specific changes in the phosphorylation of signaling molecules could be useful in this respect. Here, with the aim of developing a method for predicting the response of cancers to cisplatin using a combination of specific biomarker(s) and patient-derived tumor organoids (PDOs), we found that cisplatin-sensitive cell lines or PDOs showed enhanced phosphorylation of c-Jun (p-c-Jun) within 24 h after cisplatin treatment. We also compared the responses of 6 PDOs to cisplatin with the therapeutic effect of neoadjuvant chemotherapy (docetaxel/cisplatin/5-fluorouracil) in 6 matched patients. Mechanistically, the c-Jun induction was partly related to TNF signaling induced by cisplatin. Our data suggest that enhanced phosphorylation of c-Jun in response to cisplatin treatment could be a predictive biomarker for the efficacy of cisplatin in selected cancer patients.


Subject(s)
Antineoplastic Agents , Neoplasms , Humans , Cisplatin/pharmacology , Cisplatin/therapeutic use , Organoids/pathology , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Phosphorylation , Docetaxel/pharmacology , Neoplasms/pathology , Biomarkers
11.
Nihon Hoshasen Gijutsu Gakkai Zasshi ; 78(6): 569-581, 2022 Jun 20.
Article in Japanese | MEDLINE | ID: mdl-35474038

ABSTRACT

PURPOSE: In synthetic q-space learning (synQSL), which uses deep learning to infer the diffusional kurtosis (K), a bias that depends on the noise level added to the synthetic training data occurs. The purpose of this study was to evaluate K inference using synQSL and bias correction. METHODS: Using the synthetic test data and the real image data, K was inferred by synQSL, and bias correction was performed. Then, those results were compared with K inferred by fitting by the least-squares fitting (LSF) method. At this time, the noise level of the training data was set to 3 types, the noise level of the synthesis test data was set to 5 types, and the number of excitation (NEX) of the real image data was set to 4 types. Robustness of inference was evaluated by the outlier rate, which is the ratio of K outliers to the whole brain. We also evaluated the root mean square error (RMSE) of the inferred K. RESULTS: The outlier rate inferred by synQSL without correction was significantly lower in the test data of each noise level than that by the LSF method and was further reduced by correction. In addition, the RMSE of NEX 1 with NEX 4 as the correct answer based on the real image data had the smallest correction result of K by synQSL. CONCLUSION: Inferring K using synQSL and bias correction is a robust and small error method compared to that using the LSF method.


Subject(s)
Brain , Diffusion Magnetic Resonance Imaging , Diffusion Magnetic Resonance Imaging/methods
12.
Clin J Gastroenterol ; 14(4): 1115-1120, 2021 Aug.
Article in English | MEDLINE | ID: mdl-33768451

ABSTRACT

Patients with dengue fever usually present with fever and rash, but non-specific symptoms such as headache, myalgia, arthralgia, and digestive symptoms are sometimes seen. We report a case of dengue fever with digestive symptoms in a patient who traveled to Indonesia. A 35-year-old man presented with fever, diarrhea, headache, and arthralgia. He later developed generalized rash. Dengue fever was clinically suspected from the travel history and confirmed by laboratory tests. He tested positive for anti-dengue virus antibodies, so dengue fever was diagnosed. Dengue fever should be included in the differential diagnosis of patients with digestive symptoms after returning to Japan.


Subject(s)
Communicable Diseases, Imported , Dengue , Adult , Dengue/complications , Dengue/diagnosis , Fever/etiology , Humans , Japan , Male , Travel
13.
Clin J Gastroenterol ; 14(3): 791-795, 2021 Jun.
Article in English | MEDLINE | ID: mdl-33389695

ABSTRACT

There is no established treatment for rectal varices. Although endoscopic cyanoacrylate (N-butyl 2-cyanoacrylate) injection therapy is the standard treatment for gastric varices, there are few reports of its use for rectal varices. We present a case of rectal varix that was successfully treated with endoscopic cyanoacrylate injection therapy. An 80-year-old man with cirrhosis was treated for rectal varices with interventional radiology 2 years earlier. At his current presentation, he underwent colonoscopy for hematochezia and anemia, which showed recurrence of rectal varix. We performed endoscopic cyanoacrylate injection therapy for the lesion. However, since we observed bleeding from the treated varix the next day, additional cyanoacrylate was injected. Thereafter, there was no re-bleeding and no recurrence was observed at the 3-year follow-up. According to the previous reports, interventional radiology (IVR), endoscopic sclerotherapy (EIS), and endoscopic variceal ligation (EVL) have been mainly used to treat rectal varices; however, there are few reports of endoscopic cyanoacrylate injection therapy. Our case suggests that endoscopic cyanoacrylate injection therapy might be a useful and safe treatment option for rectal varices.


Subject(s)
Esophageal and Gastric Varices , Varicose Veins , Aged, 80 and over , Cyanoacrylates , Esophageal and Gastric Varices/therapy , Gastrointestinal Hemorrhage/etiology , Gastrointestinal Hemorrhage/therapy , Humans , Male , Recurrence , Sclerotherapy , Varicose Veins/diagnostic imaging , Varicose Veins/therapy
14.
Neurospine ; 18(4): 903-913, 2021 Dec.
Article in English | MEDLINE | ID: mdl-35000348

ABSTRACT

The retro-odontoid pseudotumor is often concurrent with atlantoaxial subluxation (AAS). Therefore, the pseudotumor is relatively common in rheumatoid arthritis (RA) but rare in primary osteoarthritis (OA). This is a case report of an elderly male patient suffering from neck pain and compression myelopathy caused by the craniocervical pseudotumor with OA but without atlantoaxial instability. He had long-lasting peripheral and spinal pain treated by nonsteroidal anti-inflammatory drugs. Imaging found upper cervical spondylosis without AAS or dynamic instability but with periodontoid calcifications and ossifications, suggesting calcium pyrophosphate dihydrate (CPPD) crystal deposition. Based on a comprehensive literature search and review, CPPD disease around the atlantodental joint is a possible contributor to secondary OA development and retro-odontoid pannus formation through chronic inflammation, which can be enough severe to induce compression myelopathy in non-RA patients without AAS. The global increase in the aged population advises caution regarding more prevalent upper cervical spine disorders associated with OA and CPPD.

15.
Nihon Shokakibyo Gakkai Zasshi ; 117(5): 402-412, 2020.
Article in Japanese | MEDLINE | ID: mdl-32389912

ABSTRACT

A 68-year-old woman was referred to our hospital due to widespread purpura on her legs. A diagnosis of IgA vasculitis was made based on the findings of a skin biopsy. However, after being admitted to our hospital, abdominal pain and lower gastrointestinal hemorrhaging developed. The purpura disappeared gradually, whereas the abdominal pain migrated and persisted. Treatment with prednisolone was initiated, and the clinical course improved temporarily. However, her severe abdominal symptoms recurred while, in addition, the intestinal tract lesions migrated after the prednisolone dosage was tapered. Therefore, intravenous high-dose methylprednisolone was administered followed by oral steroids. The dose was thereafter carefully tapered, and the steroid dose reduction was successful with this treatment. We herein report the clinical course of the case along with a review of the relevant literature.


Subject(s)
IgA Vasculitis , Immunoglobulin A/metabolism , Vasculitis , Abdomen , Abdominal Pain , Adult , Aged , Female , Humans
16.
Clin J Gastroenterol ; 13(4): 564-567, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32125663

ABSTRACT

Gastrointestinal Dieulafoy's ulcer is a rare disease of unknown etiology. Dieulafoy's ulcer often presents in the stomach and is thought to cause about 5% of all gastrointestinal bleeds in adults, but can be found in any part of the gastrointestinal tract. Dieulafoy's ulcer corresponds to an arterial malformation in the submucosal space and can cause life-threatening hemorrhage. We report a case of the lower gastrointestinal bleeding from a cecal Dieulafoy's ulcer that was successfully treated with endoscopic clips. An 82-year-old woman had been diagnosed with hypertension and cerebral infarction. She had been using aspirin to prevent recurrent infarction. She was admitted to our hospital with hematochezia. Urgent colonoscopy revealed a small, reddish vascular malformation in the cecum. The lesion was suggestive of Dieulafoy's ulcer and was treated with endoscopic clips. The patient has since been discharged from our hospital without experiencing any further bleeding. Endoscopy is a useful method for diagnosing and treating Dieulafoy's ulcer.


Subject(s)
Gastrointestinal Diseases , Ulcer , Adult , Aged, 80 and over , Cecum , Female , Gastrointestinal Hemorrhage/etiology , Humans , Stomach
17.
Angew Chem Int Ed Engl ; 56(18): 5087-5090, 2017 04 24.
Article in English | MEDLINE | ID: mdl-28370999

ABSTRACT

The increasing attention devoted to triangulenes and their heteroatom derivatives inspired us to explore a divergent synthesis of heteroatom-centered 4,8,12-triazatriangulenes, which involved the preparation of a nitrogen-containing macrocyclic precursor and subsequent central heteroatom introduction by electrophilic C-Li and C-H substitution. The boron-centered triangulene has a planar structure unlike the bowl-shaped phosphorus- and silicon-centered triangulenes. The described synthetic procedure can be used to fabricate a broad range of attractive functional materials, for example, for organic light-emitting diodes, based on heteroatom-centered triangulenes.

18.
Adv Mater ; 28(14): 2777-81, 2016 Apr 13.
Article in English | MEDLINE | ID: mdl-26865384

ABSTRACT

Ultrapure blue-fluorescent molecules based on thermally activated delayed fluorescence are developed. Organic light-emitting diode (OLED) devices employing the new emitters exhibit a deep blue emission at 467 nm with a full-width at half-maximum of 28 nm, CIE coordinates of (0.12, 0.13), and an internal quantum efficiency of ≈100%, which represent record-setting performance for blue OLED devices.

19.
PLoS One ; 10(8): e0135408, 2015.
Article in English | MEDLINE | ID: mdl-26270815

ABSTRACT

Accurate regulation of chlorophyll synthesis is crucial for chloroplast formation during the greening process in angiosperms. In this study, we examined the role of phytochrome B (phyB) in the regulation of chlorophyll synthesis in rice seedlings (Oryza sativa L.) through the characterization of a pale-green phenotype observed in the phyB mutant grown under continuous red light (Rc) irradiation. Our results show that the Rc-induced chlorophyll accumulation can be divided into two components--a phyB-dependent and a phyB-independent component, and that the pale-green phenotype is caused by the absence of the phyB-dependent component. To elucidate the role of the missing component we established an Rc-induced greening experiment, the results of which revealed that several genes encoding proteins on the chlorophyll branch were repressed in the phyB mutant. Notable among them were ChlH and GUN4 genes, which encode subunit H and an activating factor of magnesium chelatase (Mg-chelatase), respectively, that were largely repressed in the mutant. Moreover, the kinetic profiles of chlorophyll precursors suggested that Mg-chelatase activity simultaneously decreased with the reduction in the transcript levels of ChlH and GUN4. These results suggest that phyB mediates the regulation of chlorophyll synthesis through transcriptional regulation of these two genes, whose products exert their action at the branching point of the chlorophyll biosynthesis pathway. Reduction of 5-aminolevulinic acid (5-ALA) synthesis could be detected in the mutant, but the kinetic profiles of chlorophyll precursors indicated that it was an event posterior to the reduction of the Mg-chelatase activity. It means that the repression of 5-ALA synthesis should not be a triggering event for the appearance of the pale-green phenotype. Instead, the repression of 5-ALA synthesis might be important for the subsequent stabilization of the pale-green phenotype for preventing excessive accumulation of hazardous chlorophyll precursors, which is an inevitable consequence of the reduction of Mg-chelatase activity.


Subject(s)
Chlorophyll/biosynthesis , Ferrochelatase/biosynthesis , Oryza/metabolism , Phytochrome B/metabolism , Seedlings/metabolism , Transcription, Genetic/physiology , Chlorophyll/genetics , Ferrochelatase/genetics , Gene Expression Regulation, Plant/physiology , Mutation , Oryza/genetics , Phytochrome B/genetics , Seedlings/genetics
20.
J Acoust Soc Am ; 133(5): EL339-45, 2013 May.
Article in English | MEDLINE | ID: mdl-23656091

ABSTRACT

This paper introduces an approach for online speech source clustering and separation, which is based on the utilization of the multichannel location information in a recursive expectation maximization (EM) algorithm. Specifically, the normalized multichannel speech-recording vector is employed as a feature vector and is modeled using Watson mixture model. The model parameters are determined by maximizing the data likelihood at every time-frequency slot in an online processing manner. Consequently, the proposed approach can continuously adjust the speech clusters. Promising results showing the advantage of the proposed approach over the batch EM algorithm in the case of two speakers with speaker movement are obtained.


Subject(s)
Acoustics/instrumentation , Online Systems , Signal Processing, Computer-Assisted , Speech Acoustics , Algorithms , Humans , Models, Theoretical , Motion , Pattern Recognition, Automated , Sound , Sound Spectrography , Time Factors
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