Predicting algal growth inhibition toxicity: three-step strategy using structural and physicochemical properties

We propose a three-step strategy that uses structural and physicochemical properties of chemicals to predict their 72 h algal growth inhibition toxicities against Pseudokirchneriella subcapitata. In Step 1, using a log D-based criterion and structural alerts, we produced an interspecies QSAR between algal and acute daphnid toxicities for initial screening of chemicals. In Step 2, we categorized chemicals according to the Verhaar scheme for aquatic toxicity, and we developed QSARs for toxicities of Class 1 (non-polar narcotic) and Class 2 (polar narcotic) chemicals by means of simple regression with a hydrophobicity descriptor and multiple regression with a hydrophobicity descriptor and a quantum chemical descriptor. Using the algal toxicities of the Class 1 chemicals, we proposed a baseline QSAR for calculating their excess toxicities. In Step 3, we used structural profiles to predict toxicity either quantitatively or qualitatively and to assign chemicals to the following categories: Pesticide, Reactive, Toxic, Toxic low and Uncategorized. Although this three-step strategy cannot be used to estimate the algal toxicities of all chemicals, it is useful for chemicals within its domain. The strategy is also applicable as a component of Integrated Approaches to Testing and Assessment.

Interspecies quantitative structure-activity relationships (QSARs) for eco-toxicity screening of chemicals: the role of physicochemical properties

In addition to molecular structure profiles, descriptors based on physicochemical properties are useful for explaining the eco-toxicities of chemicals. In a previous study we reported that a criterion based on the difference between the partition coefficient (log POW) and distribution coefficient (log D) values of chemicals enabled us to identify aromatic amines and phenols for which interspecies relationships with strong correlations could be developed for fish-daphnid and algal-daphnid toxicities. The chemicals that met the log D-based criterion were expected to have similar toxicity mechanisms (related to membrane penetration). Here, we investigated the applicability of log D-based criteria to the eco-toxicity of other kinds of chemicals, including aliphatic compounds. At pH 10, use of a log POW - log D > 0 criterion and omission of outliers resulted in the selection of more than 100 chemicals whose acute fish toxicities or algal growth inhibition toxicities were almost equal to their acute daphnid toxicities. The advantage of log D-based criteria is that they allow for simple, rapid screening and prioritizing of chemicals. However, inorganic molecules and chemicals containing certain structural elements cannot be evaluated, because calculated log D values are unavailable.

Interspecies quantitative structure-activity-activity relationships (QSAARs) for prediction of acute aquatic toxicity of aromatic amines and phenols

We propose interspecies quantitative structure-activity-activity relationships (QSAARs), that is, QSARs with descriptors, to estimate species-specific acute aquatic toxicity. Using training datasets consisting of more than 100 aromatic amines and phenols, we found that the descriptors that predicted acute toxicities to fish (Oryzias latipes) and algae were daphnia toxicity, molecular weight (an indicator of molecular size and uptake) and selected indicator variables that discriminated between the absence or presence of various substructures. Molecular weight and the selected indicator variables improved the goodness-of-fit of the fish and algae toxicity prediction models. External validations of the QSAARs proved that algae toxicity could be predicted within 1.0 log unit and revealed structural profiles of outlier chemicals with respect to fish toxicity. In addition, applicability domains based on leverage values provided structural alerts for the predicted fish toxicity of chemicals with more than one hydroxyl or amino group attached to an aromatic ring, but not for fluoroanilines, which were not included in the training dataset. Although these simple QSAARs have limitations, their applicability is defined so clearly that they may be practical for screening chemicals with molecular weights of ≤364.9.

Cross-talk between the cellular redox state and the circadian system in Neurospora

The circadian system is composed of a number of feedback loops, and multiple feedback loops in the form of oscillators help to maintain stable rhythms. The filamentous fungus Neurospora crassa exhibits a circadian rhythm during asexual spore formation (conidiation banding) and has a major feedback loop that includes the FREQUENCY (FRQ)/WHITE COLLAR (WC) -1 and -2 oscillator (FWO). A mutation in superoxide dismutase (sod)-1, an antioxidant gene, causes a robust and stable circadian rhythm compared with that of wild-type (Wt). However, the mechanisms underlying the functions of reactive oxygen species (ROS) remain unknown. Here, we show that cellular ROS concentrations change in a circadian manner (ROS oscillation), and the amplitudes of ROS oscillation increase with each cycle and then become steady (ROS homeostasis). The ROS oscillation and homeostasis are produced by the ROS-destroying catalases (CATs) and ROS-generating NADPH oxidase (NOX). cat-1 is also induced by illumination, and it reduces ROS levels. Although ROS oscillation persists in the absence of frq, wc-1 or wc-2, its homeostasis is altered. Furthermore, genetic and biochemical evidence reveals that ROS concentration regulates the transcriptional function of WCC and a higher ROS concentration enhances conidiation banding. These findings suggest that the circadian system engages in cross-talk with the cellular redox state via ROS-regulatory factors.

Application of chemical reaction mechanistic domains to an ecotoxicity QSAR model, the KAshinhou Tool for Ecotoxicity (KATE)

The validity of chemical reaction mechanistic domains defined by skin sensitisation in the Quantitative Structure-Activity Relationship (QSAR) ecotoxicity system, KAshinhou Tools for Ecotoxicity (KATE), March 2009 version, has been assessed and an external validation of the current KATE system carried out. In the case of the fish end-point, the group of chemicals with substructures reactive to skin sensitisation always exhibited higher root mean square errors (RMSEs) than chemicals without reactive substructures under identical C- or log P-judgements in KATE. However, in the case of the Daphnia end-point this was not so, and the group of chemicals with reactive substructures did not always have higher RMSEs: the Schiff base mechanism did not function as a high error detector. In addition to the RMSE findings, the presence of outliers suggested that the KATE classification rules needs to be reconsidered, particularly for the amine group. Examination of the dependency of the organism on the toxic action of chemicals in fish and Daphnia revealed that some of the reactive substructures could be applied to the improvement of the KATE system. It was concluded that the reaction mechanistic domains of toxic action for skin sensitisation could provide useful complementary information in predicting acute aquatic ecotoxicity, especially at the fish end-point.

Global warming, plant paraquat resistance, and light signal transduction through nucleoside diphosphate kinase as a paradigm for increasing food supply

Light signal transduction was studied in extracts of mycelia of the fungus Neurospora crassa, and the third internodes of dark-grown Pisum sativum cv Alaska. Both processes increased the phosphorylation of nucleoside diphosphate kinase (NDPK). NDPK may function as a carrier of reduction equivalents, as it binds NADH, thereby providing electrons to transform singlet oxygen to superoxide by catalases (CAT). As the C-termini of NDPK interact with CAT which receive singlet oxygen, emitted from photoreceptors post light perception (which is transmitted to ambient triplet oxygen), we hypothesize that this may increase phospho-NDPK. Singlet oxygen, emitted from the photoreceptor, also reacts with unsaturated fatty acids in membranes thereby forming malonedialdehyde, which in turn could release ions from, e.g., the thylacoid membrane thereby reducing the rate of photosynthesis. A mutant of Alaska pea, which exhibited two mutations in chloroplast NDPK-2 and one mutation in mitochondrial localized NDPK-3, was resistant to reactive oxygen species including singlet oxygen and showed an increase in the production of carotenoids, anthocyanine, and thereby could reduce the concentration of singlet oxygen. The reduction of the concentration of singlet oxygen is predicted to increase the yield of crop plants, such as Alaska pea, soybean, rice, wheat, barley, and sugarcane. This approach to increase the yield of crop plants may contribute not only to enhance food supply, but also to reduce the concentration of CO(2) in the atmosphere.

ROS resistance in Pisum sativum cv. Alaska: the involvement of nucleoside diphosphate kinase in oxidative stress responses via the regulation of antioxidants

This study investigated the reactive oxygen species (ROS) tolerance mechanism of a paraquat-resistant Pisum sativum line (R3-1) compared with the wild type (WT). Physiological and biochemical analyses showed significant differences in the phenotypes, such as delayed leaf and floral development, superior branching, and greater biomass and yields in the R3-1 line, as well as an increased level of antioxidant pigments and a lower rate of cellular lipid peroxidation in the resistant R3-1. Additionally, the phosphorylation of crude proteins showed distinguishable differences in band mobility and intensity between the R3-1 and WT plants. cDNA cloning and sequence analysis of NDPKs, which were candidate phosphorylated proteins, revealed that two of the deduced amino acids in NDPK2 (IL12L and Glu205Lys) and one in NDPK3 (P45S) were mutated in R3-1. Using glutathione S-transferase-NDPK fusion constructs, we found that the precursor recombinant R3-1 NDPK2 showed an increased level of activity and autophosphorylation in R3-1 plants compared to WT plants. Native PAGE analysis of the crude proteins revealed that NDPK and catalase (CAT) activity co-existed in the same area of the gel. In a yeast two-hybrid assay, the N-terminal region of NDPK2 showed an interaction with the full-length CAT1 protein. Furthermore, we found that WT showed a decreased level of CAT activity compared with R3-1 under illumination and/or on media containing ROS-releasing reagents. Taken together, these results suggest that there is a strong interaction between NDPK2 and CAT1 in R3-1 plants, which possibly plays a vital role in the antioxidant defense against ROS.

Catalase-1 (CAT-1) and nucleoside diphosphate kinase-1 (NDK-1) play an important role in protecting conidial viability under light stress in Neurospora crassa

Recently we reported that Catalase-1 (CAT-1) played an important role in protecting conidial viability in Neurospora crassa, and interacted with a light signal transducer, nucleoside diphosphate kinase-1 (NDK-1). To disclose the functional interaction between CAT-1 and NDK-1 at the genetic level, we created CAT-1 and NDK-1 double mutants, cat-1;ndk-1-1 and cat-1;ndk-1-2, by crossing single mutants of cat-1 ( RIP ) and ndk-1 ( P72H ) previously isolated in our laboratory. The double mutant strains grew normally, but showed increased CAT-2 activity. In cat-1 ( RIP ), NDK activity was increased when dCDP was used as a substrate. ndk-1 ( P72H ), cat-1;ndk-1-1, and cat-1;ndk-1-2 were more sensitive to riboflavin than the wild type and cat-1 ( RIP ) under strong light (100 microE m(-2) s(-1)). The pull-down experiment suggests that His-tagged NDK-1 is bound to [(32)P]NADH. However, his-tagged NDK-1(P72H) was not bound to [(32)P]NADH. The double mutants showed much lower conidial viability and lost all conidial germination ability much more rapidly than cat-1 ( RIP ), when they were cultured under continuous light for more than 2 weeks. These results indicate that the interaction of CAT-1 with NDK-1 plays an important role in supporting the survival of conidia under oxidative and light-induced stress including singlet oxygen, and confirm our former conclusion that reactive oxygen species play an important role in light signal transduction via NDK-1 at the genetic level.

Loss of Catalase-1 (Cat-1) results in decreased conidial viability enhanced by exposure to light in Neurospora crassa

Light is one of the most important factors inducing morphogenesis in Neurospora crassa. The reception of light triggers the generation of reactive oxygen species (ROS) including hydrogen peroxide (H(2)O(2)). Catalase-1 (Cat-1) is one of three catalases known to detoxify H(2)O(2) into water and oxygen. We reported that the photomorphogenetic characteristics of mutants in nucleoside diphosphate kinase-1 (NDK-1), a light signal transducer, are severely affected, and NDK-1 interacted with Cat-1 in a yeast two-hybrid assay. To disclose the function of Cat-1, we created a Cat-1 loss-of-function mutant (cat-1 ( RIP )) by the repeat induced point-mutation (RIPing) method. No Cat-1 activity was detected in the mutant strain. Forty guanines were replaced with adenines in the cat-1 gene of cat-1 ( RIP ), which caused 30 amino acid substitutions. The mutant strain grew normally, but its conidia and mycelia were more sensitive to H(2)O(2) than those of the wild type. The lack of Cat-1 activity also caused a significant reduction in the conidial germination rate. Furthermore, light enhanced this reduction in cat-1 ( RIP ) more than that in the wild type. Introduction of cat-1 into the mutant reversed all of these defective phenotypes. These results indicate that Cat-1 plays an important role in supporting the survival of conidia under oxidative and light-induced stress.

Light-dependent subcellular localization of nucleoside diphosphate kinase-1 inNeurospora crassa

Nucleoside diphosphate kinase (NDK) is a housekeeping enzyme localized in cellular organelles and distributed in various organs in prokaryotes and eukaryotes. In Neurospora crassa, NDK-1 is suggested to control catalases in response to heat, oxidative stress and light. In this study, we identified the presence of NDK-1 during most developmental stages in submerged mycelia, aerial hyphae, asexual conidia and perithecia, and the localization of it in soluble, mitochondrial, nuclear and membrane fractions in the mycelial cell. A light-dependent localization of NDK-1 was shown by Western blotting and immunohistochemical analysis using anti-NDK-1 antibody. In the mycelia, NDK-1 was compartmentalized on the plasma membrane in darkness, while it was relocated in the cytoplasm under light. These results suggest that NDK-1 protein was translocated from the plasma membrane to cytoplasm in response to light, and may interact with catalase.

Interaction of nucleoside diphosphate kinase and catalases for stress and light responses in Neurospora crassa

Nucleoside diphosphate kinase (NDK) is an ubiquitous enzyme with the function of a signal transducer. In Neurospora crassa, an ndk-1(P72H) mutant carrying the point mutation Pro72His was isolated. We found that ndk-1(P72H) showed hypersensitivity to oxidative and heat stress and a decrease in the levels of catalase (Cat)-1 and -3 induced by oxidative, heat stress and illumination compared with wild type (Wt). We found, by conducting a yeast two-hybrid assay, that Cat-1 interacted with NDK-1. NDK-1 was suggested to control Cat-1 and Cat-3 at the post-transcriptional level in response to heat, oxidative stress and light.

Photomorphogenetic characteristics are severely affected in nucleoside diphosphate kinase-1 (ndk-1)-disrupted mutants in Neurospora crassa

We previously demonstrated that the NDK-1 (Nucleoside Diphosphate Kinase-1) point mutant, ndk-1(P72H), displays a defective phenotype in light-induced perithecial polarity in Neurospora crassa. To investigate the biological function of NDK-1 in detail, we isolated two ndk-1 mutants, ndk-1(RIP-1) and ndk-1(RIP-2), using the RIPing (repeat induced point mutation) method. Notably, we detected no accumulation of ndk-1(RIP-1) mRNA and truncated NDK-1(RIP-2) protein. The ndk-1(RIP) mutants exhibited altered morphogenesis; (1) aerial hypha was not formed with no conidium formation, (2) the mutants exhibited colonial, and very slow mycelial growth on a solid medium and by shaking culture in a liquid medium, (3) light-induced carotenoid accumulation in mutant mycelia is reduced to less than half that by wild type, (4) the mutants exhibited spiral growth of mycelia, and (5) female sterility with defective protoperithecium formation. The morphogenetic processes of 1, 3, and 5 are light induced in the wild type. Moreover, despite only 10-20% of total nucleoside diphosphate kinase activity, the accumulation of relevant transcripts in the ndk-1(RIP) mutants, such as al-1 and al-2, was similar to that of wild type.

Oxygen and hydrogen peroxide enhance light-induced carotenoid synthesis in Neurospora crassa

Previously, we found that intracellular reactive oxygen species (ROS) affect photomorphogenesis in Neurospora crassa. In this study, we investigated the physiological roles of ROS in the response to light and found that the exposure of mycelia to air was important for the light-induced carotenogenesis. Mycelia treated with a high concentration of O(2) gas and H(2)O(2) to release ROS showed an enhancement of light-induced carotenoid accumulation and the expression of gene related to light-inducible carotenogenesis. These results suggested that stimuli caused by the exposure of the mycelia to air containing O(2) gas triggered the light-induced carotenoid synthesis.

Molecular cloning and characterization of nucleoside diphosphate (NDP) kinases from Chinese cabbage (Brassica campestris)

Nucleoside diphosphate kinases (NDPKs) are key metabolic enzymes that catalyze the synthesis of non-adenosine nucleoside triphosphates (NTP) by transfer of the terminal phosphate between NDP and NTP. Recently we isolated three NDPK cDNAs from Chinese cabbage cDNA library. BcNDK1 has 636 bp and encodes a putative 17.4 kDa protein, BcNDK2 has 854 bp and encodes a putative 25.5 kDa protein, and BcNDK3 is 986 bp long and encodes a putative 25.7 kDa protein. The precursor proteins of BcNDK2 and BcNDK3 have long N-terminal extensions containing putative chloroplast or mitochondrial targeting sequences. A phylogenic tree showed that the 3 BcNDKs are highly homologous to other plant NDPK genes, especially those of Arabidopsis. Expression of the BcNDK genes depended on the developmental stage and the conditions of seed germination. Most notably, expression of BcNDK2 increased dramatically in seedlings transferred to the light after germinating in the dark. In addition, BcNDK3 differed from BcNDK1 in being highly expressed in the hooks and cotyledons of seedlings. Although all BcNDKs were highly expressed in petals, BcNDK1 was also expressed in pistils. Expression of each of the BcNDKs increased as the flower bud matured. These results indicate that NDPKs are involved in physiological pathways activated by a variety of environmental conditions and at different developmental stages.

Reactive oxygen species affect photomorphogenesis in Neurospora crassa

In Neurospora crassa, several biological phenomena such as the synthesis of carotenoids in the mycelia and polarity of perithecia are regulated by light. We found that a sod-1 mutant, with a defective Cu,Zn-type superoxide dismutase (SOD), showed accelerated light-dependent induction of carotenoid accumulation in the mycelia compared with the wild type. The initial rate of light-induced carotenoid accumulation in the sod-1 mutant was faster than that in the vvd mutant known to accumulate high concentrations. This acceleration was suppressed by treatment with antioxidant reagents. Light-induced transcription of genes involved in carotenoid synthesis, al-1, -2, and -3, was sustained in the sod-1 mutant, whereas it was transient in the wild type. Moreover sod-1 was defective in terms of light-induced polarity of perithecia. By genetic analysis, the enhancement in light-inducible carotenoid synthesis in sod-1 was dependent on the wild type alleles of wc-1 and wc-2. However, the sod-1;vvd double mutant showed additive effects on the carotenoid accumulation in the mycelia. These results suggested that intracellular reactive oxygen species regulated by SOD-1 could affect the light-signal transduction pathway via WC proteins.

Arabidopsis NDK1 is a Component of ROS Signaling by Interacting with Three Catalases

Plants sense various environmental stimuli and have specific signaling pathways to respond to these cues. We focused on light responsive components and found that NDKs were phosphorylated specifically after red light irradiation in Pisum sativum [Tanaka et al. (1998) J. Photochem. Photobiol. B 45: 113] and after blue light irradiation in Neurospora crassa [Oda and Hasunuma (1997) Mol. Gen. Genet. 256: 593, Ogura et al. (2001) J. Biol. Chem. 276: 21228]. We performed yeast two-hybrid screening using AtNDK1, the counterpart of NDK-P1 (Pisum sativum NDK1) in Arabidopsis, as bait, and isolated catalase3 (AtCat3). Interactions between AtNDK1-AtCAT1 and AtNDK1-AtCAT2 were also detected with the two-hybrid system. Non-denaturing two-dimensional gel electrophoresis of crude extracts from plants revealed that catalase and NDK activities co-migrated in the same area of the gel. Transgenic plants expressing AtNDK1 under control of the CaMV 35S promoter exhibited tolerance to paraquat and high ability to eliminate exogenous H2O2. These results indicate that AtNDK1 has a role in ROS response.

Putative functions of nucleoside diphosphate kinase in plants and fungi

The putative functions of NDP (nucleoside diaphosphate) kinases from various organisms focusing to fungi and plants are described. The biochemical reactions catalyzed by NDP kinase are as follows. (i) Phosphotransferring activity from mainly ATP to cognate NDPs generating nucleoside triphosphates (NTPs). (ii) Autophosphorylation activity from ATP and GTP. (iii) Protein kinase (phosphotransferring) activity phosphorylating such as myelin basic protein. NDP kinase could function to provide NTPs as a housekeeping enzyme. However, recent works proved possible functions of the NDP kinases in the processes of signal transduction in various organisms, as described below. 1) By use of the extracts of the mycelia of a filamentous fungus Neurospora crassa blue-light irradiation could increase the phosphorylation of a 15-kDa protein, which was purified and identified to be NDP kinase (NDK-1). By use of the etiolated seedlings of Pisum sativum cv Alaska and Oryza sativa red-light irradiation of intact plants increased the phosphorylation of NDP kinase. However, successive irradiation by red-far-red reversed the reaction, indicating that phytochrome-mediated light signals are transduced to the phosphorylation of NDP kinase. 2) NDP kinase localizing in mitochondria is encoded by nuclear genome and different from those localized in cytoplasm. NDP kinase in mitochondria formed a complex with succinyl CoA synthetase. 3) In Spinicia oleraceae two different NDP kinases were detected in the chloroplast, and in Pisum sativum two forms of NDP kinase originated from single species of mRNA could be detected in the choloroplast. However, the function of NDP kinases in the choloroplast is not yet known. 4) In Neurospora crassa a Pro72His mutation in NDP kinase (ndk-1Pro72His) deficient in the autophosphorylation and protein kinase activity resulted in lacking the light-induced polarity of perithecia. In wild-type directional light irradiation parallel to the solid medium resulted in the formation of the perithecial beak at the top of perithecia, which was designated as "light-induced polarity of perithecia." In wild-type in darkness the beak was formed at random places on perithecia, and in ndkPro72His mutant the perithecial beak was formed at random places even under directional light illumination. The introduction of genomic DNA and cDNA for ndk-1 demonstrated that the wild-type DNAs suppressed the mutant phenotype. With all these results except for the demonstration in Neurospora, most of the phenomena are elusive and should be solved in the molecular levels concerning with NDP kinases.

[A case of chondrosarcoma originating from the rib and presenting as a posterior mediastinal tumor-like shadow]

A 66-year-old man was admitted to our hospital because of induction therapy of interferon for chronic hepatitis due to hepatitis C virus. On routine investigation, a mass-like lesion was detected at the level of the hilum of the left lung on the chest plain radiograph. On the thoracic CT, the heterogeneous tumor, including calcification, was 6 cm in diameter in the posterior mediastinal area, and the rib and vertebra had been damaged by it. The tumor extended to the descending aorta and the left main bronchus. A small nodule in the left S1 + 2 was noted on another slice section of this thoracic CT. The possible diagnoses, based on these radiological findings, for this tumor were primary lung cancer, posterior mediastinal tumor and malignant tumor originating from the chest wall. The diagnosis of chondrosarcoma was made based on the histological findings of the specimen obtained from the tumor. This tumor could not be resected in this case, because it had extensively damaged the rib and vertebra, and the nodular lesion in the left S1 + 2 was regarded as a metastasis from it. Although reports of chondrosarcoma originating from a rib and presenting as a posterior mediastinal tumor-like shadow are rare, chondrosarcoma should be considered as a possible diagnosis for such tumors-posterior mediastinal masses with characteristic findings such as a large tumor in contact with the chest wall, and containing calcification, with destruction of bone and dissection of the rib as shown in our CT findings.

A point mutation in nucleoside diphosphate kinase results in a deficient light response for perithecial polarity in Neurospora crassa

In Neurospora crassa, the phosphorylation of nucleoside diphosphate kinase (NDK)-1 is rapidly enhanced after blue light irradiation. We have investigated the function of NDK-1 in the blue light signal transduction pathway. A mutant called psp (phosphorylation of small protein) shows undetectable phosphorylation of NDK-1 and is defective in light-responsive regulation of perithecial polarity. Sequencing analysis of ndk-1 cDNA by reverse transcription-polymerase chain reaction revealed that proline 72 of ndk-1 was replaced with histidine in psp. The mutation ndk-1(P72H) resulted in accumulation of normal levels of mRNA and of about 25% of NDK-1(P72H) protein compared with that of wild type as determined by Western blot analysis. The ectopic expression of cDNA and introduction of genomic DNA of wild type ndk-1 in psp (ndk-1(P72H)) suppressed the reduction in accumulation and phosphorylation of NDK-1 and the light-insensitive phenotype. These findings demonstrated that the phenotype of psp was caused by the ndk-1(P72H) mutation. Biochemical analysis using recombinant NDK-1 and NDK-1(P72H) indicated that the P72H substitution in NDK-1 was responsible for the decrease in phosphotransfer activities, 5% of autophosphorylation activity, and 2% of V(max) for protein kinase activity phosphorylating myelin basic protein, compared with those of wild type NDK-1, respectively.

DFL1, an auxin-responsive GH3 gene homologue, negatively regulates shoot cell elongation and lateral root formation, and positively regulates the light response of hypocotyl length

A novel dominant mutant designated 'dwarf in light 1' (dfl1-D) was isolated from screening around 1200 Arabidopsis activation-tagged lines. dfl1-D has a shorter hypocotyl under blue, red and far-red light, but not in darkness. Inhibition of cell elongation in shoots caused an exaggerated dwarf phenotype in the adult plant. The lateral root growth of dfl1-D was inhibited without any reduction of primary root length. The genomic DNA adjacent to the right border of T-DNA was cloned by plasmid rescue. The rescued genomic DNA contained a gene encoding a GH3 homologue. The transcript was highly accumulated in the dfl1-D. The dfl1-D phenotype was confirmed by over-expression of the gene in the wild-type plant. The dfl1-D showed resistance to exogenous auxin treatment. Moreover, over-expression of antisense DFL1 resulted in larger shoots and an increase in the number of lateral roots. These results indicate that the gene product of DFL1 is involved in auxin signal transduction, and inhibits shoot and hypocotyl cell elongation and lateral root cell differentiation in light.

DFL1, an auxin-responsive GH3 gene homologue, negatively regulates shoot cell elongation and lateral root formation, and positively regulates the light response of hypocotyl length

A novel dominant mutant designated 'dwarf in light 1' (dfl1-D) was isolated from screening around 1200 Arabidopsis activation-tagged lines. dfl1-D has a shorter hypocotyl under blue, red and far-red light, but not in darkness. Inhibition of cell elongation in shoots caused an exaggerated dwarf phenotype in the adult plant. The lateral root growth of dfl1-D was inhibited without any reduction of primary root length. The genomic DNA adjacent to the right border of T-DNA was cloned by plasmid rescue. The rescued genomic DNA contained a gene encoding a GH3 homologue. The transcript was highly accumulated in the dfl1-D. The dfl1-D phenotype was confirmed by over-expression of the gene in the wild-type plant. The dfl1-D showed resistance to exogenous auxin treatment. Moreover, over-expression of antisense DFL1 resulted in larger shoots and an increase in the number of lateral roots. These results indicate that the gene product of DFL1 is involved in auxin signal transduction, and inhibits shoot and hypocotyl cell elongation and lateral root cell differentiation in light.

[Idiopathic plasmacytic lymphadenopathy with polyclonal hyperimmunoglobulinemia and pleural effusion]

A 56-year-old man was admitted for further evaluation of mediastinal lymphadenopathy and left pleural effusion. A blood test revealed polyclonal hypergammaglobulinemia with an elevated erythrocyte sedimentation rate and level of C-reactive protein. Chest computed tomography disclosed bilateral hilar and multiple mediastinal lymph-node swelling and bilateral pleural thickening accompanied by a moderate amount of left pleural effusion. Biopsy specimens from mediastinal lymph nodes and the right pleura were obtained under video-assisted thoracoscopy. Histology on microscopic examination demonstrated mature plasma cells and lymphocyte infiltration in the conserved lymph-node structure and the pleura, suggesting a diagnosis of idiopathic plasmacytic lymphadenopathy (IPL) with polyclonal hyperimmunoglobulinemia. Interestingly, IL-6 was elevated in the pleural effusion but normal in serum. This was a rare and instructive case of IPL accompanied by pleural effusion that was considered to be an important determinant of the clinical spectrum of the disease.

[Nontuberculous mycobacterial infection followed for 12 years]

A 67-year-old woman presented in September 1985 with productive cough, bloody sputum, and dyspnea on exertion. Productive cough and bloody sputum had developed when the patient was 55 years old. Sputum culture and radiologic findings yielded a diagnosis of nontuberculous mycobacteriosis (NTM). Antituberculous therapy with INH, RFP, and EB was initiated in November 1987 because of the development of a cavity in the right upper lobe, and led to resolution of the lesion and clinical symptoms. Despite progression of bronchiectatic changes in both lungs and a relapse of her clinical symptoms during the following 10 years, the patient retained enough pulmonary function to be able to maintain an active daily life until she died of advanced gastric cancer at the age of 79. Autopsy revealed cystic bronchiectasis accompanied by bronchial wall thickening in both lungs, with some granuloma and acid-fast-bacteria observed in lung tissue. In this report, we concluded that patients with NTM usually experience a gradual progression of symptoms and radiographic changes during their clinical course, and that their pulmonary function may be conserved well enough to maintain an active daily life.

Isolation and characterization of Neurospora crassa nucleoside diphosphate kinase NDK-1

We have previously reported that phosphorylation of a 15-kDa protein increased after blue-light irradiation in Neurospora crassa. In this study, the 15-kDa protein was purified using four columns; DEAE-cellulose, Blue-Sepharose, SP-Sepharose and Mono Q. The 15-kDa protein was shown to be homologous with nucleoside diphosphate kinase by amino acid sequencing and was also shown to possess nucleoside diphosphate kinase activity. A gene encoding N. crassa nucleoside diphosphate kinase, ndk-1, was isolated from the mycelial cDNA and genomic libraries. The deduced amino acid sequence of NDK-1 was identical to that of the 15-kDa protein. Northern blot analysis suggested that WC-1 and WC-2, the key factors of blue-light signal transduction in N. crassa, did not regulate NDK-1 at the transcriptional level. NDK-1 also showed rapid autophosphorylation activity and protein kinase activity against myelin basic protein with a Km value of 0.36 mM. These results suggest that NDK-1 acts as a signal transducer by phosphorylating proteins.

[Intralobar pulmonary sequestration presenting increased serum CEA, CA 19-9, and CA 125, and associated with asymptomatic pulmonary aspergillosis]

A 44-year-old woman was admitted to our hospital for further evaluation of a consolidated shadow in the left lower lobe and the evaluation of serum tumor markers (CEA 46.3 ng/ml, CA 19-9 1911 U/ml, and CA 125 103 U/ml). Chest computed tomography revealed an irregular shaped, low density mass shadow in the left S10 region, suggesting the diagnosis of pulmonary sequestration or bronchial atresia. However digital subtraction angiography failed to demonstrate an anomalous feeding artery. We could not rule out the possibility that a malignant lesion was included in the consolidated shadow. A left thoracotomy revealed an intralobar pulmonary sequestration of the left lower lobe. Hyphae of aspergillus were found in the lumen of the cystic bronchus of the resected lung. Immunohistochemical studies showed strong expression of CEA, CA 19-9, and CA 125 by bronchial epithelia in the pulmonary sequenstration. The serum values of tumor markers returned to their normal ranges after surgery.

Phosphorylation of proteins in the stem section of etiolated rice seedling irradiated with red light

The molecular mechanism of light signal perception was analyzed using stem sections of etiolated rice (Oryza sativa L.) seedlings irradiated with red light from a fluorescent lamp. The membrane and cytosol fractions were labeled by 40 nM [gamma-32P]ATP for 10 s at 0 degrees C and proteins were separated by two-dimensional polyacrylamide gel electrophoresis. Phosphorylation of three proteins with molecular weights of 16, 17 and 18 kDa in the rice increased with the intensity of red light irradiation (50 micromol/m2/s) for 16 min. Most of the phosphorylation activity was present in the cytosol fraction. The three proteins cross-reacted with the anti-nucleoside diphosphate (NDP) kinase antibody. Phosphorylation of these proteins was correlated with changes in the activity of NDP kinase. These proteins phosphorylated histone III-S, a substrate for measuring the protein kinase activity. By phospho-amino acid analysis, phosphoserine was found present in the phosphorylated proteins. These rapidly phosphorylated proteins would thus appear to have the features of NDP kinase.

[Summer-type hypersensitivity pneumonitis with remarkable obstructive impairment of pulmonary function]

A 57-year-old-man was admitted because of persistent cough and progressive dyspnea over a period of 2 months. Examination revealed wheezing in both lungs, severe hypoxemia, and marked obstructive impairment of pulmonary function. A chest CT scan showed diffuse small nodular lesions with patchy air space opacifications. The patient was initially given a diagnosis of bronchiolitis of unknown cause. He showed marked improvement after treatment with oral prednisolone, but developed fever and dyspnea after returning home. This episode indicated hypersensitivity pneumonitis, a diagnosis supported by findings of increased CD 8 positive T-lymphocytes in bronchoalveolar lavage fluid, and a high titer of serum anti-Trichosporon antibody. Lung biopsy samples obtained under video-assisted thoracoscopy disclosed noncaseating granulomas in terminal and respiratory bronchioles, which resulted in marked narrowing of the lumen. The pathologic changes seemed to be consistent with obstructive impairment of pulmonary function in this patient.

Phytochrome-mediated light signals are transduced to nucleoside diphosphate kinase in Pisum sativum L. cv. Alaska

To clarify the molecular mechanism for the transduction of light signals in plants, we have established an in vitro system that uses crude membrane and soluble fractions of stem sections of etiolated Pisum sativum L. cv. Alaska after irradiation by red light, or sequential application of red and far-red light to the stem section. In a previous report (T. Hamada et al., J. Photochem. Photobiol. B: Biol. 33 (1996) 143-151) the labelling of proteins in membrane fraction by [gamma-32P] ATP at 0 degree C for 15 s and subsequent separation of proteins by two-dimensional electrophoresis allowed unambiguous identification of a heavily phosphorylated protein spot at 18 kDa (p18). In the present study we have confirmed the former results in the membrane fraction, and obtained the result that an increase in the phosphorylation of p18 by red-light irradiation is observed in the soluble fraction. Further, we have provided evidence that the p18 in the soluble fraction is purified and identified as nucleoside diphosphate (NDP) kinase by Western blotting, immuno-precipitation, amino acid sequencing and cDNA analysis. Purified p18 shows autophosphorylation activity and strong phosphorylating activity against myelin basic protein (MBP), a substrate of MAP (mitogen activated protein) kinase. The results show that phytochrome-mediated light signals are transduced to NDP kinase, which may elicit signals by providing high concentrations of, for example, GTP from GDT and ATP, by the autophosphorylation and by the protein kinase activity similar to MAP kinase.

Genetic analysis of signal transduction through light-induced protein phosphorylation in Neurospora crassa perithecia

We have previously demonstrated that blue light induces the phosphorylation of a 15-kDa protein in crude membrane fractions of Neurospora crassa mycelia. Here we report the isolation and characterization of a mutant (psp; phosphorylation of small proteins that is completely defective for phosphorylation of that protein, as assayed in both crude membrane and soluble fractions. This mutation defines a unique locus that maps to linkage group VR between al-3 and his-6. To elucidate the photobiological significance of the phosphorylation of the protein, we analyzed known photobiological phenomena and discovered that the positioning of beaks on the perithecia, defined as perithecial polarity, was light-dependent in the wild type. In the psp mutant, beaks were phototropic as in the wild type, but their position was random. In a wc-l mutant, however, beaks were positioned at random and were not phototropic. Thus light-induced perithecial polarity and phototropism of perithecial beaks are controlled differently. A psp; wc-l double mutant showed the same phenotype as that of wc-l with respect to these two photomorphogenetic characters. These results indicate that the wc-l gene is epistatic to psp in the light-signal transduction pathway that controls both phototropism and perithecial polarity.

[Pulmonary eosinophilic granuloma with relatively rapid progression and remission]

A 53-year-old woman with a smoking history of 20 pack-years was admitted to the hospital because of dry coughing and exertional dyspnea that had progressed over the previous 3 months. A chest X-ray film taken one month before the onset of symptoms was almost normal. Diffuse small nodular shadows with infiltration were evident one month after the onset of symptoms, and increased rapidly until admission to the hospital. Eosinophilic granuloma was diagnosed histologically after thoracoscopy. The symptoms, chest X-ray findings and pulmonary-function data improved spontaneously after admission to the hospital and the nodular shadows had a almost completely disappeared by 5 months later; the patient continued to smoke. The present case is unique and valuable because it shows the natural course of eosinophilic granuloma from the onset of symptoms to remission.

Altered vasoreactivity in lungs isolated from rats exposed to nitric oxide gas

A rebound phenomenon (severe arterial desaturation and pulmonary vasoconstriction) has been observed in some patients with pulmonary hypertension after sudden discontinuation of nitric oxide (NO) inhalation therapy. The mechanism responsible for this phenomenon is unknown. It has recently been reported that NO synthase (NOS) can be inhibited by NO as a negative feedback mechanism. We therefore hypothesized that this rebound phenomenon might be attributable to reduced endogenous NO production due to inhibition of pulmonary endothelial NOS (eNOS) activity by inhaled NO. To test this hypothesis, vasoreactivities were compared in isolated perfused lungs from rats exposed to 40 ppm NO gas and room air for 2 days. The pressor responses to angiotensin II and hypoxia of lungs from rats exposed to NO were markedly potentiated and their depressor response to bradykinin was considerably impaired, whereas that to sodium nitroprusside was preserved, compared with the responses of those exposed to room air. This altered pulmonary vasoreactivity was also induced by lower concentrations of inhaled NO (as low as 1 ppm) and was completely reversed by discontinuation of NO inhalation for several (< 8) hours. The expression of eNOS mRNA by lungs isolated from rats exposed to 40 ppm NO and room air for 2 days did not differ. These results suggest that pulmonary endogenous NO production is reversibly reduced after relatively short-term NO inhalation, which probably inhibits eNOS activity directly. We speculate that reduced production of pulmonary endogenous NO by exogenous (inhaled) NO could be the mechanism responsible for this rebound phenomenon.

Blue light induced ADP ribosylation of 38 and 56 kDa proteins in the soluble fraction of mycelia of Neurospora crassa

Soluble fractions prepared from the mycelia of wild type (74-OR23-1A) and band (bd) exhibited an increase in the rate of the ADP ribosylation of a 38 kDa protein from nicotinamide adenine [32P]dinucleotide ([32P]NAD) in the presence of 10(-7) M riboflavin caused by blue light irradiation in vitro. The soluble fraction was mixed with a reaction mixture containing 5 microCi [32P]NAD at 0 degree C for 20 s and then it was irradiated with blue light (420 nm, 42 mumol m-2 s-1) for 12.5, 25, 50, 100, 200 or 400 s at 0 degree C or for 100 s with photon irradiance of 0.42, 4.2, 6.4 or 42 mumol m-2 s-1. Immediately after irradiation, the reaction was stopped and analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. An increase in the ADP ribosylation of the 38 kDa protein could be detected within 100 s of irradiation, and the enhancement in the rate of ADP ribosylation of the 38 kDa protein was proportional to the increase in the photon irradiance. By the irradiation with blue light for 200 or 400 s, the ADP ribosylation of a 56 kDa protein could also be detected. Analysis by two-dimensional gel electrophoresis of proteins after ADP ribosylation of them revealed that the 38 kDa proteins displayed at least four radioactive protein spots and the 56 kDa protein a single radioactive protein spot. Soluble fractions of mycelia prepared from blind mutants wc-1, wc-2, delta ps15-1, lis-1, lis-2 and lis-3 exhibited also the enhancement of the ADP ribosylation of the 38 kDa protein by blue light irradiation, and at least wc-1, delta ps15-1, lis-1 and lis-2 displayed a similar blue light response in the 56 kDa protein.

Phytochrome regulates phosphorylation of a protein with characteristics of a nucleoside diphosphate kinase in the crude membrane fraction from stem sections of etiolated pea seedlings

The molecular mechanism of light signal perception via phytochrome was analysed using the third internodes of etiolated pea seedlings irradiated with red or red followed by far-red light. A crude membrane fraction prepared from the tissue was labelled by [gamma-32P]ATP at 4 x 10(-8) M for 15 s at 0 degree C, and the proteins were separated by two-dimensional gel electrophoresis. The phosphorylation of a protein with a molecular mass of about 15 kDa in the crude membrane fraction increased with an increase in the intensity of red light irradiation (10, 50 and 100 mumol m-2 s-1) for 20 s. Successive irradiation with red light (100 mumol m-2 s-1 for 20 s) and subsequent irradiation with far-red light reduced the phosphorylation of the protein, depending on the intensity of the far-red light (from 0.1 to 8 mumol m-2 s-1 for 180 s). A plasma membrane purified from the crude membrane fraction from red light irradiated tissue showed a rapid phosphorylation of the 15 kDa protein by 4 x 10(-8) M [gamma-32P]ATP at 0 degree C for 7 s, and subsequent addition of ATP, GTP, ADP or GDP at 10(-5) or 10(-6) M efficiently removed the phosphoryl group of the 15 kDa protein. The 15 kDa protein was autophosphorylated in the gel following separation by sodium dodecylsulphate (SDS) polyacrylamide gel electrophoresis. The partially purified 15 kDa protein included nucleoside diphosphate kinase (NDP kinase) activity, as well as cross-reactivity with an antibody specific to rat NDP kinase as assayed by immunostaining and crossreactivity with an antibody specific to ricet NDP kinase as assayed by immunoprecipitation.

[Angiotensin II receptors in a rat model of hypobaric hypoxic pulmonary hypertension]

Hypoxic pulmonary hypertension is characterized by profound remodeling of the walls of small pulmonary arteries: endothelial swelling and proliferation of media and adventitia to a degree that may narrow the lumen. The molecular mechanism responsible for these changes is unknown. Recent studies have demonstrated the existence of a vascular and cardiac renin-angiotensin system. This system can induce hypertrophy and proliferation of aortic smooth muscle cells and cardiac muscle cells in animal models of systemic hypertension. In the present experiments, Northern blot analysis and a receptor binding assay specific to angiotensin II (Ang II) receptors was used to study the pulmonary renin angiotensin system in a rat model of hypobaric hypoxic pulmonary hypertension. mRNA transcripts for the Ang II receptor AT(1A) were constitutively expressed, and specific binding of Ang II to the receptors occurred in lung tissue of control rats that breathed ambient air. After 3 days of hypobaric hypoxia (380 Torr), the AT(1A) mRNA level and the index of Ang II receptors had increased, but right ventricular hypertrophy was not still evident. Ang II receptors were significantly increased after 14 days of hypoxia, when histological evidence of pulmonary hypertension was observed. In addition, the Ang II level in pulmonary tissue was higher after 14 days of hypoxia than in normal controls. These findings suggest that the renin-angiotensin system in pulmonary tissue was activated in these rats, and that it contributes to the morphological changes observed in hypoxic pulmonary hypertension.

Effects of separate and combined ETA and ETB blockade on ET-1-induced constriction in perfused rat lungs

To evaluate the role of endothelin (ET) receptors in ET-1-induced pulmonary vasoreactivity, we studied the effects of ET-receptor agonists and antagonists in isolated perfused rat lungs. ET-1 (1-10 nM) caused concentration-dependent pulmonary vasoconstriction and gross pulmonary edema at a concentration of 10 nM. The combination of the selective ETA antagonist BQ-123 and the selective ETB antagonist BQ-788 inhibited ET-1-induced pulmonary vasoconstriction more effectively than BQ-123 alone, whereas BQ-788 alone enhanced the constriction. ET-1-induced hydrostatic pulmonary edema was prevented by the combination of BQ-123 and BQ-788 but not by either BQ-123 or BQ-788 alone. After the addition of 125 ng of exogenous ET-1, the perfusate levels of ET-1 were significantly higher in BQ-788-treated lungs than in either the vehicle control or BQ-123-treated lungs. The selective ETB agonist IRL-1620 also caused pulmonary vasoconstriction and edema, both of which were completely inhibited by BQ-788. ET-1-induced transient vasodilation was abolished by BQ-788 but was unaffected by BQ-123. These results suggest that in the isolated perfused rat lung, ET-1-induced vasoconstriction is mediated by both ETA and ETB receptors, whereas ET-1-induced transient vasodilation is mediated exclusively by the ETB receptor. Blockade of ETB receptors may result in enhanced ET-1 activity (via the ETA receptor) through inhibition of the ETB-mediated clearance of ET-1. Thus combined ETA and ETB blockade is required for the complete inhibition of ET-1-induced vasoconstriction in the rat pulmonary circulation.

Light signals are transduced to the phosphorylation of 15 kDa proteins in Neurospora crassa

A microsomal fraction prepared from the mycelia of the band (bd) strain of Neurospora crassa showed enhanced phosphorylation of two small proteins with molecular masses of around 15 kDa (ps15) by the irradiation of the reaction mixture containing [gamma-32P]ATP at 0 degrees C for 1 s with blue light (450 nm, 6 mumol/m2/s or 420 nm, 80 mumol/m2/s). The reaction was stopped at 5 s of incubation at 0 degrees C after blue light irradiation. The light effect could not be detected in ps15, when a microsomal fraction from a blind mutant, wc-1 or wc-2 was used. The mixing followed by homogenization of the microsomal fractions from wc-1 and wc-2 restored the activity to simulate the phosphorylation of ps15 by blue light. The phosphorylated amino acid residue of ps15 was unstable when the proteins on a nylon membrane were exposed to an acid or alkaline solution, suggesting that the phosphorylated residue was aspartic acid. The other phosphorylated protein with a molecular mass of 70 kDa (p70) showed no light effect in the phosphorylation and the phosphorylated residue was estimated to be histidine, since it was stable in alkaline solution.

BQ123, an ETA-receptor antagonist, attenuates hypoxic pulmonary hypertension in rats

To investigate the role of endothelin-1 (ET-1) in the pathogenesis of hypoxic pulmonary hypertension, we studied the effects of a recently described endothelin-receptor antagonist (ETA), BQ123, on the development of this process. Intraperitoneal osmotic pumps were placed into 8-wk-old Sprague-Dawley rats that received either saline or BQ123 (0.15 mg/h). The rats were maintained in room air normoxia or placed in a hypobaric chamber (380 Torr) for 2 wk to induce hypoxic pulmonary hypertension. There were no hemodynamic differences between normoxic rats treated with either saline or BQ123. However, treatment with BQ123 attenuated the hypoxia-induced increase in pulmonary arterial mean pressure and total pulmonary resistance index by 60 and 87% respectively. There was also a reduction in hypoxia-induced right ventricular hypertrophy in the BQ123 group. Histological studies performed using a barium-gelatin fixation technique in hypoxic BQ123-treated animals demonstrated a decrease in medial wall thickness in arteries corresponding to the respiratory and terminal bronchioles, respectively. Similarly, there was a significant reduction in the degree of muscularization of more distal vessels at the level of alveolar ducts in BQ123-treated hypoxic rats. We conclude that the ETA-receptor antagonist BQ123 attenuates the development of hypoxic pulmonary hypertension in rats in vivo, thereby suggesting a possible contributing role for ET-1 and the ETA receptor in the pathogenesis of this process.

EDRF suppresses an unidentified vasoconstrictor mechanism in hypertensive rat lungs

To test whether endothelium-derived relaxing factor (EDRF) plays a role in regulating the hypertensive pulmonary vascular bed, we compared effects of the inhibitor of EDRF production, N omega-nitro-L-arginine (L-NNA), on resting vascular tone in lungs and conduit pulmonary arteries isolated from control and chronically hypoxic rats. In contrast to no effect on normoxic vascular tone in salt solution-perfused normotensive lungs, 100 microM L-NNA caused a marked, L-arginine-sensitive, precapillary vasoconstriction in unstimulated hypertensive lungs. Bioassay of hypertensive lung perfusate did not detect a circulating vasoconstrictor, and L-NNA vasoconstriction was not inhibited by blockers of cyclooxygenase, 5-lipoxygenase, platelet-activating factor receptors, alpha-adrenoceptors, and serotonin 5-HT2 receptors or by scavengers of superoxide anion and H2O2. Inhibitors of endothelin-1 (ET-1) production and vasoconstriction tended to blunt the response, but accumulation of perfusate ET-1 was not increased in hypertensive lungs. L-NNA vasoconstriction was blocked by Ca(2+)-free plus ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid perfusion but not by nifedipine. Quiescent, endothelium-intact hypertensive but not normotensive conduit pulmonary artery rings were markedly constricted by 200 microM L-NNA. The onset but not the peak of the response was blunted by meclofenamate. The response was reduced slightly by the ETA receptor antagonist, BQ 123. L-NNA had little effect on denuded hypertensive arteries, and treatment with dilators showed they had constricted spontaneously. Both the L-NNA and the spontaneous constrictions were readily inhibited by nifedipine. These results indicate that in rat hypertensive pulmonary arteries, the basal release of EDRF suppresses vasoconstrictor mechanisms which are not expressed in normotensive arteries.