Investigation of immune complexes formed by mitochondrial antigens containing a new lipoylated site in sera of primary biliary cholangitis patients.

Primary biliary cholangitis (PBC) is characterized by the presence of serum anti-mitochondrial autoantibodies (AMAs). To date, four antigens among the 2-oxo-acid dehydrogenase complex family, which commonly have lipoyl domains as an epitope, have been identified as AMA-corresponding antigens (AMA-antigens). It has recently been reported that AMAs react more strongly with certain chemically modified mimics than with the native lipoyl domains in AMA-antigens. Moreover, high concentrations of circulating immune complexes (ICs) in PBC patients have been reported. However, the existence of ICs formed by AMAs and their antigens has not been reported to date. We hypothesized that AMAs and their antigens formed ICs in PBC sera, and analyzed sera of PBC and four autoimmune diseases (Sjögren's syndrome, systemic lupus erythematosus, systemic scleroderma, and rheumatoid arthritis) using immune complexome analysis, in which ICs are separated from serum and are identified by nano-liquid chromatography-tandem mass spectrometry. To correctly assign MS/MS spectra to peptide sequences, we used a protein-search algorithm that including lipoylation and certain xenobiotic modifications. We found three AMA-antigens, the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2), the E2 subunit of the 2-oxo-glutarate dehydrogenase complex (OGDC-E2) and dihydrolipoamide dehydrogenase binding protein (E3BP), by detecting peptides containing lipoylation and xenobiotic modifications from PBC sera. Although the lipoylated sites of these peptides were different from the well-known sites, abnormal lipoylation and xenobiotic modification may lead to production of AMAs and the formation ICs. Further investigation of the lipoylated sites, xenobiotic modifications, and IC formation will lead to deepen our understanding of PBC pathogenesis.

Immune complexome analysis reveals the presence of immune complexes and identifies disease-specific immune complex antigens in saliva samples from patients with Sjögren's syndrome.

Sjögren's syndrome (SS) is a chronic autoimmune disease that mainly damages the salivary and lacrimal glands. Immune complex (IC) formation triggers local inflammation through IC deposition and decreased antigen function. Some ICs can leak from the lesion and into the saliva, but no salivary ICs have been reported to date. We used immune complexome analysis to comprehensively identify antigens incorporated into IC (IC-antigens) in saliva samples from patients with SS (n = 9) or with xerostomia (n = 7). Neutrophil defensin 1 (67%), small proline-rich protein 2D (67%), myeloperoxidase (44%), neutrophil elastase (44%), cathepsin G (33%), nuclear mitotic apparatus 1 (33%) and phosphatidylinositol 4-phosphate 3-kinase C2 domain-containing subunit gamma (33%) were identified as new IC-antigens specifically and frequently detected in the saliva of SS patients. Of these, neutrophil defensin 1, myeloperoxidase, neutrophil elastase and cathepsin G are neutrophil intracellular proteins, which suggests that repeated destruction of neutrophils due to abnormal autoimmunity may be involved in the pathogenesis of SS. We also analyzed serum samples from three SS patients. There was little overlap of IC-antigens between two of the samples (fewer than 30% of the IC-antigens in the saliva samples), suggesting that many ICs are formed locally and independently of the circulation. In addition, we found that four SS-specific salivary antigens show sequence homology with several proteins of oral microbiomes but no antigen has homology with Epstein-Barr virus proteins. The homology between some IC-antigens and oral microbiome proteins may indicate the impact of oral infection on local autoimmunity through molecular mimicry theory.

Time-to-onset of diabetes with everolimus use: analysis of a spontaneous reporting system database.

The incidence of hyperglycemia and diabetes induced by everolimus has been shown in previous studies. Our study analyzed diabetes time-to-onset profiles after everolimus use in patients who underwent transplantation and patients with cancer. Using data from April 2007 to December 2018 in the Japanese Adverse Drug Event Report database, the reports with everolimus were classified according to its use as an immunosuppressant or anticancer drug. The median (25%-75%) days of diabetes time-to-onset in patients who underwent transplantation and patients with cancer were 172 (56-315) and 32 (18.5-57), respectively. There were no significant variations among patients with breast cancer, neuroendocrine tumor, and renal cell carcinoma. By conducting a Weibull shape parameter test, the lower limits of the 95% confidence intervals of the shape parameter ß values for the indications of the cancer types were >1, indicating the wear out failure type profile, whereas those for transplantation data indicated a random failure type profile. The diabetes time-to-onset profiles after everolimus use differed between usage as an anticancer drug and immunosuppressant and there were no significant variations among the type of cancer. It was suggested that the incidence of diabetes should be monitored for 1-2 months in patients with cancer, whereas continuous monitoring is needed in patients who undergo transplantation.

Psoriasis associated with ACE inhibitors: an analysis of the FAERS database.

Many case reports have been published concerning the development or exacerbation of psoriasis after administration of angiotensin-converting enzyme (ACE) inhibitors. The aim of the present study was to investigate the association between psoriasis and ACE inhibitors using the US Food and Drug Administration Adverse Event Reporting System (FAERS) data. After excluding patients with psoriasis-related primary diseases, the association of psoriasis with 14 ACE inhibitors was examined using disproportional analyses reporting odds ratio (ROR) and information component (IC). Signals were detected for all 14 ACE inhibitors combined (ROR: 1.25, 95% confidence interval [CI]: 1.14-1.37; IC: 0.31, 95% CI: 0.17-0.44) and individually for lisinopril (ROR: 1.20, 95% CI: 1.05-1.37; IC: 0.25, 95% CI: 0.06-0.45), perindopril (ROR: 1.86, 95% CI: 1.38-2.52; IC: 0.86, 95% CI: 0.43-1.30), and ramipril (ROR: 1.63, 95% CI: 1.36-1.96; IC: 0.69, 95% CI: 0.42-0.96). ACE inhibitors are widely used in patients with hypertension, heart failure, and diabetes mellitus, which are considered comorbidities of psoriasis. Our results suggest that the involvement of ACE inhibitors should be considered in patients on ACE inhibitor therapy who have developed (or show exacerbated) psoriasis.

Evaluation of syncope association with α1-adrenoceptor blockers in males using the FAERS database: impact of concomitant hypertension.

Previous studies have revealed an association between the administration of α1-adrenoceptor blockers (α1Bs) and episodes of syncope in patients with benign prostatic hyperplasia (BPH). The objective of the present study was to evaluate the association between α1Bs and syncope in BPH patients with hypertension using two different pharmacoepidemiological indices. Using the US Food and Drug Administration Adverse Event Reporting System, we analyzed the whole dataset and subsets for specific indications, including hypertension, diabetes, and dyslipidemia, for males older than 40 years. The drugs of interest were alfuzosin, doxazosin, and terazosin as non-selective α1Bs and silodosin and tamsulosin as selective α1Bs. The reporting odds ratio (ROR) and information component (IC) were used for signal detection. The association between the non-selective α1Bs and syncope was observed for all the items examined. The results obtained using the whole dataset, as well as the diabetes and dyslipidemia subsets, were same for the selective and non-selective α1Bs in terms of the association with syncope, while no association with syncope was observed for both silodosin [ROR: 1.09, 95% confidence interval (CI): 0.61-1.93; IC: 0.10, 95% CI: -0.72-0.92] and tamsulosin (ROR: 1.08, 95% CI: 0.90-1.30; IC: 0.10, 95% CI: -0.17-0.37) in patients with hypertension. The data suggested that α1Bs, even those with receptor subtype selectivity, were associated with syncope. Thus, careful attention should be paid when prescribing α1Bs, especially to patients who do not take medications for hypertension.

Proteomic profile of circulating immune complexes in chronic Chagas disease.

Immune complexes (ICs) are the direct and real-time products of humoral immune responses. The identification of constituent foreign or autoantigens within ICs might bring new insights into the pathology of infectious diseases. We applied immune complexome analysis of plasma to the study of Chagas disease caused by Trypanosoma cruzi. Twenty seropositive plasma samples including cardiac and/or megacolon determinate patients (n = 11) and indeterminate (n = 9) were analysed along with 10 seronegative individuals to characterize the antigens bound to circulating ICs. We identified 39 T. cruzi antigens and 114 human autoantigens specific to patients with Chagas. Among those antigens, two T. cruzi antigens (surface protease GP63, glucose-6-isomerase) and six human autoantigens (CD180 antigen, ceruloplasmin, fibrinogen beta chain, fibrinogen beta chain isoform 2 preprotein, isoform gamma-A of fibrinogen γ-chain, serum paraoxonase) were detected in more than 50% of the patients tested. Human isoform short of complement factor H-related protein 2 and trans-sialidase of T. cruzi were more frequently found in the indeterminate (5/9 for both) compared with in the determinate Chagas (0/11, P = 0·046 for human, 1/11, P = 0·0498 for T. cruzi). The immune complexome could illustrate the difference of immune status between clinical forms of chronic Chagas disease.

Saliva as a potential tool for diagnosis of dry mouth including Sjögren's syndrome.

OBJECTIVES: Recently, the use of saliva as a diagnostic tool has gained considerable attention because it is non-invasive and easy to perform repeatedly. In this study, we focused on soluble molecules in saliva to establish a new diagnostic method for xerostomia. MATERIALS AND METHODS: Saliva was obtained from 90 patients with Sjögren's syndrome (SS), 22 patients with xerostomia associated with neurogenic/neuropsychiatric disorders and drugs (XND), 30 patients with radiation-induced xerostomia (RX), and 36 healthy controls. Concentrations of helper T (Th) cytokines in saliva were measured by flow cytometric analysis. Concentrations of secretory IgA (SIgA) and chromogranin A (CgA) were measured by ELISA. RESULTS: Unstimulated and stimulated whole saliva from patients with SS, XND, and RX was significantly reduced compared with controls. Th1 and Th2 cytokines from SS patients were significantly higher than controls. Furthermore, Th2 cytokines were closely associated with strong lymphocytic accumulation in salivary glands from SS patients, while Th1 and Th17 cytokines were negatively associated. SIgA levels were not significantly different between all patient groups and controls. CgA levels from XND patients were significantly higher than controls. CONCLUSIONS: The measurement of cytokines, CgA, and SIgA in saliva is suggested to be useful for the diagnosis of xerostomia and also to reveal disease status.

Muscle atrophy in chronic inflammatory demyelinating polyneuropathy: a computed tomography assessment.

BACKGROUND AND PURPOSE: Muscle atrophy is generally mild in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) compared with the severity and duration of the muscle weakness. Muscle atrophy was evaluated using computed tomography (CT) in patients with CIDP. METHODS: Thirty-one patients with typical CIDP who satisfied the diagnostic criteria for the definite CIDP classification proposed by the European Federation of Neurological Societies and the Peripheral Nerve Society were assessed. The clinicopathological findings in patients with muscle atrophy were also compared with those in patients without atrophy. RESULTS: Computed tomography evidence was found of marked muscle atrophy with findings suggestive of fatty degeneration in 11 of the 31 patients with CIDP. CT-assessed muscle atrophy was in the lower extremities, particularly in the ankle plantarflexor muscles. Muscle weakness, which reflects the presence of muscle atrophy, tended to be more pronounced in the lower extremities than in the upper extremities in patients with muscle atrophy, whereas the upper and lower limbs tended to be equally affected in patients without muscle atrophy. Nerve conduction examinations revealed significantly greater reductions in compound muscle action potential amplitudes in the tibial nerves of patients with muscle atrophy. Sural nerve biopsy findings were similar in both groups. The functional prognoses after immunomodulatory therapies were significantly poorer amongst patients with muscle atrophy. CONCLUSIONS: Muscle atrophy was present in a subgroup of patients with CIDP, including patients with a typical form of the disease. These patients tended to demonstrate predominant motor impairments of the lower extremities and poorer functional prognoses.

Autoimmune sequence of streptococcal M protein shared with the intermediate filament protein, vimentin.

The crossreactivity of antibodies against a renal autoimmune epitope of Streptococcus pyogenes M protein with glomerular mesangial cells was investigated. The antibodies directed against the amino acid sequence Ile-Arg-Leu-Arg of the nephritogenic type 1 M protein reacted in a fibrillar pattern with mesangial cells cultured from isolated glomeruli. In Western blots of urea-extracted mesangial proteins, the antibodies reacted with a 56-kD protein. Monoclonal and polyclonal antibodies identified the 56-kD mesangial protein as vimentin. Two synthetic peptides of human vimentin containing the sequence Arg-Leu-Arg reacted with the autoimmune antibodies raised against a streptococcal M protein peptide. These results provide evidence that the intermediate filament protein vimentin shares autoimmune epitopes with streptococcal M protein.

A case of idiopathic hypereosinophilic syndrome with leptomeningeal dissemination and intraventricular mass lesion: an autopsy report.

A 43-year-old female presented with idiopathic hypereosinophilic syndrome (HES) manifesting as an intraventricular mass lesion and leptomeningeal and cerebral parenchymal infiltration by eosinophils, lymphocytes and macrophages. She had no history of either malignancy or allergic disorder. She complained of hearing disturbance caused by eosinophilic otitis media. Eosinophilia was detected in the peripheral blood. Hearing disturbance and eosinophilia improved with corticosteroid treatment. Six months later, she was admitted with disturbances of consciousness. Magnetic resonance imaging revealed a mass lesion in the right lateral ventricle and leptomeningeal involvement around the brain stem. Her symptoms deteriorated rapidly, and she died of brain stem malfunction. Autopsy demonstrated significant infiltration by eosinophils and lymphocytes into the mass lesion in the ventricle, subarachnoid space, perivascular space and parenchyma of the medulla oblongata. Histological examination of the bone marrow and other organs did not detect any evidence of parasites, malignancies, or systemic disorders in any organ. The final diagnosis was idiopathic HES. The present case shows that leptomeningeal dissemination and infiltration by eosinophils into the cerebral ventricles and brain stem should be considered in the course of idiopathic HES.

Insulin-like growth factor I regulates apoptosis in condylar cartilage.

Endogenous insulin-like growth factor-I (IGF-I) is known to affect the growth and development of condylar cartilage. However, the critical effect of IGF-I on cell survival is still unknown. We hypothesized that endogenous IGF-I could regulate the survival of cells of the mandibular condylar cartilage. Mandibular condyles dissected from 12-day-old rats were cultured for 1, 3, and 5 days in medium containing antisense oligodeoxynucleotide (AS-ODN) for IGF-I. Real-time RT-PCR analysis showed that the levels of IGF-I and IGF binding protein (IGFBP)3 mRNAs in the AS-ODN group were significantly decreased. After 3 days' culture, the number of necrotic cells was observed in the undifferentiated mesenchymal cell layer. These cells were TUNEL-positive and confirmed to be apoptotic by electron microscopic observation. Immunoblotting revealed that expression of cleaved caspase3 was increased with AS-ODN. These results may suggest that the cells in the undifferentiated mesenchymal cell layer of the mandibular condyle require IGF-I for survival.

Common regulation of growth arrest and differentiation of osteoblasts by helix-loop-helix factors.

Cellular differentiation entails the coordination of cell cycle arrest and tissue-specific gene expression. We investigated the involvement of basic helix-loop-helix (bHLH) factors in differentiation of osteoblasts using the human osteoblastic cell line MG63. Serum starvation induced growth arrest at G1 phase, accompanied by expression of cyclin-dependent kinase inhibitor p21(WAF1/Cip1). Reporter assays with the p21 gene promoter demonstrated that the combination of E2A (E12 or E47) and coactivator CBP was responsible for p21 induction independent of p53. Twist inhibited E2A-CBP-dependent activation of the exogenous and endogenous p21 promoters. Ids similarly inhibited the exogenously transfected p21 promoter; however less antagonistic effect on the endogenous p21 promoter was observed. Twist was predominantly present in nuclei in MG63 cells growing in complete medium, while it localized mainly in the cytoplasm after serum starvation. The fibroblast growth factor receptor 3 gene (FGFR3), which generates signals leading to differentiation of osteoblasts, was found to be controlled by the same transcriptional regulation as the p21 gene. E2A and Twist influenced alkaline phosphatase expression, a consensus marker of osteoblast differentiation. Expression of E2A and FGFR3 was seen at the location of osteoblast differentiation in the calvaria of mouse embryos, implicating bHLH molecules in physiological osteoblast differentiation. These results demonstrate that a common regulatory system is involved in at least two distinct steps in osteoblastic differentiation. Our results also provide the molecular basis of Saethre-Chotzen syndrome, caused by mutations of the TWIST and FGFR3 genes.

5-Methoxy-N,N-diisopropyltryptamine (Foxy), a selective and high affinity inhibitor of serotonin transporter.

5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) is a synthetic orally active hallucinogenic tryptamine derivative, known also as Foxy or Foxy methoxy. However, few studies have examined its effects in vitro. In the present study, we investigated the actions of 5-MeO-DIPT against monoamine neurotransmitter transporters, including the transporters for dopamine (DAT), norepinephrine (NET), and serotonin (SERT), using COS-7 cells heterologously expressing these transporters and rat brain synaptosomes. 5-MeO-DIPT specifically inhibited the uptake of [3H]serotonin (5-HT) by the SERT-expressing COS-7 cells and rat striatal synaptosomes in a high affinity manner at concentrations similar to those for cocaine. The effect was reversible and competitive. 5-MeO-DIPT failed to stimulate reverse transport of [3H]5-HT through SERT, while it prevented the releasing action of methamphetamine. 5-MeO-DIPT induced cell toxicity at high concentrations in COS-7 cells, and it was not influenced by the expression of SERT. These results demonstrated that 5-MeO-DIPT acts as a competitive SERT inhibitor and has an inability to cause reverse transport, underlying its serotonergic actions.

Secretion of bioactive interleukin-6 and tumor necrosis factor-alpha proteins from primary cultured human fetal membrane chorion cells infected with influenza virus.

Influenza virus infection during pregnancy is implicated in one of the causes of premature delivery, abortion and stillbirth. Pro-inflammatory cytokines, such as interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha produced by fetal membranes, are postulated to facilitate premature delivery. We investigated the secretion of IL-6 and TNF-alpha from primary cultured human fetal membrane chorion and amnion cells infected with influenza virus at protein and bioactivity levels in order to understand the pathology of premature delivery during influenza virus infection. Concentrations of IL-6 and TNF-alpha proteins were significantly increased in culture supernatants of chorion cells by influenza virus infection. Culture supernatants of the virus-infected chorion cells stimulated the proliferation of IL-6-sensitive 7-TD-1 cells and induced the cytolysis of TNF-alpha-sensitive L929 cells, both activities of which were inhibited by the addition of respective antibody, whereas no such phenomena were observed in amnion cells. The results demonstrated that only chorion cells secreted significant amounts of bioactive IL-6 and TNF-alpha proteins responding to influenza virus infection. The present study suggests a possibility that the secretion of bioactive IL-6 and TNF-alpha proteins from fetal membrane chorion cells is implicated in the pathogenesis of premature delivery during influenza virus infection.

Biosynthesis, glycosylation and intracellular processing of the neuroglandular antigen, a human melanoma-associated antigen.

Neuroglandular antigen (NGA) was identified as a human melanoma-associated antigen by a panel of murine monoclonal antibodies of both IgG2a (LS62, LS76, LS159) and IgG1 (LS113, LS140, LS152) subclasses, developed in this laboratory (L. Sikora, A. Pinto, D. Demetrick, W. Dixon, S. Urbanski, and L. M. Jerry, Int. J. Cancer, 39: 138-145, 1987). Monoclonal antibody LS62 was used to immunoprecipitate NGA from radiolabeled cultured melanoma cells, and it behaved as a heterogeneous glycoprotein "smear" on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis (Mr 29,000-70,000). Radioactive pulse-chase time course experiments using human melanoma cells cultured in the presence or absence of inhibitors of protein glycosylation showed that the antigen consisted of a core protein with a molecular weight of 22,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This molecule was modified by the addition of at least three N-linked oligosaccharide side chains (as revealed by limited N-glycanase digestion) to give a precursor form with a molecular weight of approximately 34,000. Subsequent processing steps yielded a heterogeneous family of glycoproteins with varying amounts of covalently attached carbohydrate. Much of this heterogeneity in both molecular weight and pI (as revealed by two-dimensional electrophoresis) could be removed by treatment of the antigen with neuraminidase, suggesting heavy sialylation of the glycoprotein. NGA could be detected on the surface of melanoma cells by fluorescence-activated cell sorter analysis, surface radioiodination, and, as previously shown, immunoperoxidase staining. However, there was a larger intracellular pool of the molecule and the antigen was rapidly released into the culture supernatant. The function of NGA remains unknown but its elevated expression in transformed melanocytes have prompted this characterization to understand its biochemical nature and relation to other melanoma-associated antigens.

Isolation and influenza virus receptor activity of glycophorins B, C and D from human erythrocyte membranes.

(1) Glycophorins (GPs) AM, AN, B, C and D were each isolated into a high state of purity from human erythrocyte membranes by a combination of lithium diiodosalicylate (LIS)-phenol extraction, gel-filtration with Bio-Gel A1.5m and HPLC with LiChrospher 1000 TMAE. (2) GPs-B, -C and -D reacted with influenza A and B viruses as well as GPs-AM and -AN and the order of reactivities against two viruses of the glycophorins was as follows: GP-B > GP-C > GP-AM = GP-AN >> GP-D for the former virus and GP-C > GP-B > GP-AM = GP-AN >> GP-D for the latter virus.

A factor from damaged rat kidney stimulates collagen biosynthesis by mesangial cells.

Rats were administered CCl4, a well-defined nephrotoxin, for 20 weeks to produce glomerular sclerosis. Tubular degeneration and necrosis with interstitial fibrosis was clearly evident by histological examination. Kidneys were homogenized in phosphate-buffered saline and a collagen synthesis-stimulating factor was isolated by Sephadex G-50 gel filtration. The 5 kDa component stimulated both type I and type IV procollagen synthesis by mesangial cells and type I procollagen synthesis by rat skin fibroblasts. In each cell type, 2-6-fold increases in procollagen protein production or cell proliferation was noted. The steady-state levels of mRNA encoding for procollagen alpha 1(I) and procollagen alpha 1(IV) chains in mesangial cells were determined by by hybridization to their corresponding cDNA clones. The type I procollagen mRNA was elevated 1.4-fold compared to a 1.6-fold increase in mRNA encoding for type IV procollagen. The similar properties and chemical characteristics of this fibrogenic factor with a factor from fibrotic liver suggests they are the same and that a common endogenous collagen synthesis stimulator may be present in fibrosing organs, thus providing a driving force for collagen over-production.

Neurotrophin-3 increases the DNA-binding activities of several transcription factors in a mouse osteoblastic cell line.

In the mouse osteoblastic cell line MC3T3-E1, the signaling responses of several DNA-binding proteins induced by the treatment of neurotrophin-3 were examined using electrophoretic mobility shift assay. Neurotrophin-3 increased binding activities in nuclear extracts of MC3T3-E1 cells to TPA-responsive element (TRE), cyclic AMP-responsive element (CRE) and serum-responsive element (SRE), but not binding activity in the nuclear extracts to c-Myc binding DNA element. Competition experiments revealed that the binding activity to TRE in the nuclear extracts of neurotrophin-3-treated MC3T3-E1 cells was entirely inhibited by the both unlabeled TRE and CRE probes. On the other hand, the binding activity to CRE was abolished by the unlabeled CRE probe but not by the same amount of unlabeled TRE probe. Moreover, immunodepletion/supershift assay using antibodies directed to Fos, Jun and CREB proteins, showed that the binding activities to TRE and CRE in the nuclear extracts were derived in part from these proteins.

Accumulation of nuclear-encoded tRNA(Thr) (AGU) in mitochondria of the liverwort Marchantia polymorpha.

The mitochondrial genome of the liverwort Marchantia polymorpha does not encode the full complement of tRNAs for the threonine and isoleucine codon boxes. To find the missing tRNA genes specifically for tRNA(Thr) in mitochondria, we have searched the genomic library and identified two clones (pTT1 and pTT2), encoding the identical tRNA(Thr) (AGU) gene copy with different 5'- and 3'-flanking sequences. By northern analysis, we demonstrate considerable accumulation of the nuclear encoded tRNA(Thr) and moderate expression of native tRNA(Thr) (GGU) in mitochondria. Nonetheless, the imported and native tRNA(Thr) species together are not sufficient to translate all four threonine codons used in liverwort mitochondria, implicating mitochondrial import of at least one additional threonine isoacceptor tRNA.

Structure and organization of Marchantia polymorpha chloroplast genome. III. Gene organization of the large single copy region from rbcL to trnI(CAU).

The nucleotide sequence (25,320 base-pairs) of a part of the large single-copy region of chloroplast DNA from the liverwort Marchantia polymorpha was determined. This region encodes putative genes for four tRNAs, isoleucine tRNA(CAU), arginine tRNA(CCG), proline tRNA(UGG) and tryptophan tRNA(CCA); eight photosynthetic polypeptides, the large subunit of ribulose bisphosphate carboxylase/oxygenase (rbcL), 51,000 Mr photosystem II chlorophyll alpha apoprotein (psbB), apocytochrome b-559 polypeptides (psbE and psbF), 10,000 Mr phosphoprotein (psbH), cytochrome f preprotein (petA), cytochrome b6 polypeptide (petB), and cytochrome b6/f complex subunit 4 polypeptide (petD); 13 ribosomal proteins (L2, L14, L16, L20, L22, L23, L33, S3, S8, S11, S12, S18 and S19); initiation factor 1 (infA); ribosome-associating polypeptide (secX); and alpha subunit of RNA polymerase (rpoA). Functionally related genes were located in several clusters in this region of the genome. There were two ribosomal protein gene clusters: rpl23-rpl2-rps19-rpl22-rps3-rpl16-+ ++rpl14-rps8-infA-secX-rps11-rpoA, with a gene arrangement similar to that of the Escherichia coli S10-spc-alpha operons, and the rps12'-rpl20-rps18-rpl33 cluster. There were gene clusters encoding photosynthesis components such as the psbB-psbH-petB-petD and the psbE-psbF clusters. Thirteen open reading frames, ranging in length from 31 to 434 amino acid residues, remain to be identified.