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The single-copy gene for the large subunit of ATP citrate lyase (ACL) from the alga Cyanophora paradoxa was characterized at the cDNA and genome levels. The gene product showed high sequence similarity to its mammalian counterparts, but is smaller in size, as is also found for the fungal subunit Acl1 and, most probably, for the corresponding subunit from Arabidopsis thaliana. The C. paradoxa gene is interrupted by at least 12 introns of 53-65 bp with conserved border and branchpoint sequences, and the product lacks a stroma-targeting peptide. Enzyme activity was found in the cytosol of C. paradoxa but not in the plastid (cyanelle) fraction. This is in contrast to the subcellular distribution of ATP citrate lyases in higher plants, where both chloroplast and cytosolic enzymes have been reported.

Immunoscreening of a C. paradoxa expression library against water soluble muroplast (“cyanelle”) proteins resulted in isolation of a clone encoding the nucleus-encoded muroplast class-II fructose-1,6-bisphosphate aldolase (class-II FBA§). Its nucleotide sequence was determined. The 1432 bp insert, derived from a single-copy gene transcript, bears a reading frame of 1206 bp in length, representing 402 amino acids with 346 amino acids of mature protein. The leading amino acids match structural features necessary for precursor import across chloroplast envelope membranes. In phylogenetic tree topology, the investigated mature FBA clusters within type B FBAs with Synechocystis sp. as nearest neighbor. This is the first report of a Type B class-II FBA sequence of plastids.

Anterior myocardial infarction (MI) was produced in conscious dogs to evaluate the relationships among: a) cardiac technetium-99m stannous pyrophosphate (TcPPi) accretion, b) creatine phosphokinase (CPK) depletion, and c) postmortem MI weight, infarct structure, and histology. In vitro, there was a close relationship between measured MI weight and MI weight calculated by the TcPPi accretion (r = 0.96) or CPK depletion (r = 0.93) in representative "cross-sectional" MI samples. Cardiac TcPPi accretion and CPK depletion showed a curvilinear relationship over the spectrum of tissue samples. Adjacent to infarcts, there was marked TcPPi uptake and modest CPK depletion where histology suggested ischemia without infarction. Within infarcts, microscopically visible calcium was rare in this series, suggesting little intracellular calcium accumulation, insensitivity of the von Kossa staining technique, and/or other cellular mechanisms to account for Tc-PPi uptake in this conscious dog model without reperfusion.

The ferredoxin: NADP+ oxidoreductase of the protist Cyanophora paradoxa, as a descendant of a former symbiotic consortium, an important model organism in view of the Endosymbiosis Theory, is the first enzyme purified from a formerly original endocytobiont (cyanelle) that is found to be encoded in the nucleus of the host. This cyanoplast enzyme was isolated by FPLC (19% yield) and characterized with respect to the uvvis spectrum, pH optimum (pH 9), molecular mass of 34 kDa, and an N-terminal amino acid sequence (24 residues). The enzyme shows, as known from other organisms, molecular heterogeneity. The N-terminus of a further ferredoxin: NADP+ oxidoreductase polypeptide represents a shorter sequence missing the first four amino acids of the mature enzyme.

Single-chain urokinase-type plasminogen activator (scu-PA) can be cleaved by thrombin into a virtually inactive form called thrombin-cleaved two-chain urokinase-type plasminogen activator (tcu-PA/T), a process accelerated by thrombomodulin, which contains six epidermal growth factor (EGF)-like domains. In this study, we identified the EGF-like domains of thrombomodulin required for the acceleration of the inactivation of scu-PA by thrombin using various forms of thrombomodulin (TM). scu-PA was treated with thrombin in the absence and presence of full-length rabbit TM (containing EGF1-6), recombinant TM comprising all of the extracellular domains including EGF1-6 (TMLEO) and recombinant TM comprising EGF4-6 plus the interconnecting region between EGF3 and EGF4 (TMEi4-6), and the tcu-PA/T generated was quantitated in each case. Rabbit TM accelerated the inactivation of scu-PA approximately 35-fold, while both recombinant forms accelerated it only threefold due to the absence of a critical chondroitin sulfate moiety. Subsequently, TME5-6 was prepared by cyanogen bromide digestion of TMEi4-6. TME5-6 bound to thrombin but did not accelerate the activation of protein C. In contrast, the inactivation of scu-PA by thrombin was accelerated to the same extent as that induced by TMLEO and TMEi4-6. This study demonstrates that, in addition to the chondroitin sulfate moiety, only EGF-like domains 5 and 6 are essential for the acceleration of the inactivation of scu-PA by thrombin. This differs from the domains that are critical for activation of protein C (EGF-like domains i4-6) and thrombin activatable fibrinolysis inhibitor (EGF-like domains 3-6).

Cyanophora paradoxa is an important model organism for the study of the transition from endocytobiontic cyanobacteria to factual eukaryotic cell organelles. The cyanelles of these organisms possess cyanobacterial, as well as plastidic, characteristics. Although the transfer of cyanellar proteins from cytosolic into cyanellar space has been shown, the process of translocation of a known protein across the peptidoglycan layer and the envelope membranes has not been characterized. In this study we demonstrate that a specific and obligate cyanelle protein —Ferredoxin-NADP+-oxidoreductase (FNR) — is coded on the nuclear genome, synthesized on 80S ribosomes and transported from the eukaryotic cell compartment into the cyanelles of Cyanophora paradoxa, an original intracellular host-guest relation. These results indicate a gene transfer from guest to host genome and support the view that, in spite of their cyanobacterial origin, cyanelles have been evolved to cell organelles comparable to plastids.

Cyanophora paradoxa, a protist and descendant of a cyanome, harbors photosynthetic active murein-enveloped cyanoplasts. Under normal culture conditions it preferentially uses cyanoplast located accessory phycobiliproteins for storage of assimilated carbon, instead of a starch pool located in its cytosol. However, during incipient nitrogen starvation, the direction of carbon flux in the cell changes: the assimilated photosynthetic carbon now becomes increasingly incorporated into the cytosolic starch, whereas phycobiliproteins are degraded. Sulfur deficiency shows a similar influence on carbon flux and biodegradation of phycobiliprot1eins. A model calculation prompts the assumption that assimilated nitrogen goes through an intracellular pool of metabolites with regulating properties (probably amino acids) before it is stored in the phycobiliproteins

A partial characterization of the observed isoenzymes of the glucose-6-phosphate dehydrogenase (G6PDH) in Cyanophora paradoxa is given. The enzyme activities of G6PDH and 6-phosphogluconate-dehydrogenase detected in both cytosolic and cyanoplast cell compartments in comparison with biochemical properties of the isoenzymes of the G6PDH and nutritional characteristics of the flagellate allow speculation about the role of the cytosolic pentose phosphate cycle in C. paradoxa.

Using a novel cyanelle isolation procedure we showed that pre-ferredoxin-NADP+-oxidoreductase (pre-FNR) from C. paradoxa is translocated in vitro across the peptidoglycancontaining cyanelle envelope. Efficient import was also observed in a heterologous system with pea chloroplasts as the recipient organelles. These results support the conclusion derived from comparative analysis of plastid genome organization, that all plastids originate from a common semi-autonomous endosymbiotic ancestor.

Contraction band necrosis (CBN) may represent infarct extension from free radical generation during reperfusion. We sought to limit CBN with the free radical scavenger N-2-mercaptopropionyl glycine (MPG, 20 mg/kg). Sixteen chronically instrumented Beagles (8 control, and 8 MPG treated) underwent 90-min left anterior descending coronary artery (LAD) occlusion followed by 6-h reperfusion. Coronary blood flow (CBF) was measured by the radioactive microsphere technique. The dogs were killed, and the hearts were perfused with red and blue dyes to determine area at risk (AAR), stained with nitroblue tetrazolium for infarct localization, and sectioned for histologic analysis and BF measurements. In controls and MPG-treated animals, infarct/risk ratios were 40 +/- 5 and 38 +/- 6%, and epicardial collateral BFs were 0.21 +/- 0.037 and 0.15 +/- 0.034 ml/g/min, respectively (p = NS). Hemodynamic measurements did not differ between the two groups. However, CBN as a percentage of total infarct was reduced in controls (22 +/- 3%) as compared with MPG-treated animals (35 +/- 2%, p = 0.002). Thus, MPG altered the histologic composition of infarcts in this model, surprisingly increasing the amount of CBN without altering overall infarct size (IS). These results raise questions about the role of free radical scavengers in generation of CBN and suggest that a population of cells exists in which treatment with MPG may alter the mechanism of cell death.

Previous investigations of the petH gene of the biflagellated autotrophic protist Cyanophora paradoxa (Cp; Glaucocystophyta), descendant of an original endocyanome (symbiotic consortium of a eukaryote with an endocytobiotic cyanobacterium), established that: (i) the gene coding for a cyanoplast protein (FNR) is located on the nuclear genome; (ii) the sequence of the mature protein shows a high degree of amino-acid conservation to cyanobacterial homologs; (iii) the sequence of the transit peptide of the pre-protein displays poor, if any, homology to counterparts in higher plants. Here, we show that the G+C content and codon usage of this gene are most similar to a genuine nuclear gene. By contrast, the G+C content and codon usage display substantial differences to a collection of 30 cyanoplast encoded genes mainly attributable to alterations in the third codon position. Correspondence analysis on codon preference parameters corroborates the claim of codon usage adaptation of the translocated gene to the nuclear pattern. As a consequence, codon usage distances of genes of Cp encoded either by the nucleus or the cyanoplasts vs. homologous genes of the cyanobacterium, Anabaena, are notably different; this result has important phylogenetic implications.

Two aldolases from the alga Cyanophora paradoxa (Glaucocystophyta) can be separated by chromatography on diethylaminoethyl-Fractogel. The two aldolases are inhibited by 1 mM ethylene-diaminetetraacetate (EDTA) and, therefore, are class II aldolases. When cells of C. paradoxa were fractionated, one aldolase was associated with the cytosol fraction and the other was associated with the cyanoplast fraction. The Km(fructose-1,6-bisphosphate) was 600 [mu]M for the cytosolic aldolase and 340 [mu]M for the cyanoplast aldolase. The activity of the cytosolic aldolase was increased up to 4-fold by 100 mM K+ and slightly inhibited by Li+ and Cs+, whereas the cyanoplast aldolase was not affected by these ions. Inactivation by 1 mM EDTA could be partly restored by the addition of Co2+ or Mn2+ and to a lesser extent by Zn2+ or Mg2+. The molecular masses of the native cytosolic and cyanoplast aldolases are about 90 and 85 kD, respectively, as estimated by velocity centrifugation in sucrose gradients. Implications for the evolution of class I and II aldolases in chloroplasts of higher plants and algae will be discussed.

A cDNA clone for pre-ferredoxin-NADP+ reductase (FNR) was obtained by screening a Cyanophora paradoxa expression library with antibodies specific for cyanelle FNR. The 1.4 kb transcript was derived from a single-copy gene. The precursor (41 kDa) and mature forms (34 kDa) of FNR were identified by western blotting of in vitro translation products and cyanelle extracts, respectively. The derived amino acid sequence of the mature form was corroborated by data from N-terminal protein sequencing and yielded identity scores from 58% to 62% upon comparison with cyanobacterial FNRs. Sequence conservation seemed to be even more pronounced in comparison with enzymes from higher plants, but using the neighbor joining method the C. paradoxa sequence was clearly positioned between the prokaryotic and eukaryotic sequences. The transit peptide of 65 or 66 amino acids appeared to be totally unrelated to those from spinach, pea and ice plant but showed overall characteristics of stroma-targeting peptides.

The nucleus encoded cyanoplast (“cyanellar”) ferredoxin-NADP+ -oxidoreductase (FNR ) of Cyanophora paradoxa, characterized by an N-terminal amino acid sequence, is compared with homologous sequences of other photoautotrophic organisms. The high degree of similarity to the cyanobacterial sequences indicates a cyanobacterial origin. This could be a first direct demonstration of an intertaxonic combination: a gene transfer from an original endocytobiont (cyanobacterium) to the nucleus of its host, one of the most important demands of the Endosymbiosis Theory, an evolutionary mechanism leading to the origin of a new species.

Cyanophora paradoxa ferredoxin is encoded by (cyano-)plastidic DNA, in contrast to those of all other photosynthetic eukaryotes investigated so far. In the present study we report (i) the rapid purification of a chloroplast-type [2Fe-2S] ferredoxin in a two-step procedure by DEAE-Sephadex and Mono Q ion-exchange chromatography; (ii) the biochemical characterization of the purified ferredoxin by electrophoretic separation methods on a microscale; and (iii) a qualitative and quantitative ferredoxin detection method in the femtomole range that allows densitometry, semidry immunoblotting, identification of ferredoxin in soluble cell protein preparations, and analysis of protein biosynthesis from cyanoplast poly(A)− RNA in vivo and in vitro. These fast micromethods should be useful for screening phototrophic species containing ferredoxins encoded by nonnuclear DNA.

The petFI gene encoding ferredoxin I was localized in the large single copy region of cyanelle DNA by heterologous hybridization. Sequence analysis revealed an ORF of 99 amino acids (including the N-tenninal processed methionine) at a position 477 bp from the 3' end of tufA but on the opposite strand. The 25 ammo-terminal residues well corresponded to partial sequences obtained with purified cyanelle ferredoxin. The assignment of yet another gene that is not found on the genomes of chlorophyll β-type plastids to cyanelle DNA again corroborates the special position of cyanelles serving as a model for plastid evolution from endocytobiotic cyanobacteria.

The phycobiliproteids of cyanobacteria have two functions. They are accessoric pigments for the light-dependent photosynthetic electron transport, and, secondly, they are storage proteins. Cyanocyta korschikoffiana, the endocyanelle of Cyanophora paradoxa, a hardly adapted endocytobiotic cyanobacterium, is responsible for the photoautotrophy of the host flagellate. The biosynthesis of the phycobiliproteids takes place in the endocyanelles and is reversible. Under nitrogen starvation the phycobiliproteids were disintegrated again, in contrast to the carotenoids (and in a lower degree to chlorophyll), whose contents rem ain more constant in the cells, as shown by in vivo measurements. Therefore, it is concluded that sim ilar to the function in free living cyanobacteria the phycobiliproteids of C. paradoxa also serve as storage substances (“stress proteins”). This opinion is supported by experiments with chloramphenicol

Thioacylureas and thioacylam ides were found to inhibit photosynthetic O2-evolution (Hill-reactions) of “broken chloroplasts”, some derivatives approaching an I50 of 10-5м. The inhibition site is near photosystem II. The inhibitory effects of the tested derivatives vary in their pH-dependency between pH 5 and 8.

Die Geschwindigkeit der photosynthetischen Sauerstoffentwicklung des sich recht langsam vermehrenden Cyanoms Cyanophora paradoxa ist nur geringfugig niedriger als diejenige anderer Algen (in bezug auf die Chlorophyllkonzentration). Merkwurdigerweise stellt man eine starke Abhangigkeit photosynthetischer Reaktionen (O2-Entwicklung, CO2 Fixierung und Hill-Reaktion mit 2,6-Dichlorphenolindophenol) von der im Medium vorgegebenen Konzentration eines Osmotikums fest. Unter bestimmten Voraussetzungen konnen steigende Saccharosekonzentrationen (bis ca. 0,1 M) die assimilatorische Sauerstoffproduktion zunachst beschleunigen, hohere Saccharose-Konzentrationen (uber 0,1 M) hemmen dagegen. Der Hemmeffekt ist unspezifisch und kann auch in Abhangigkeit von Sorbit und Natriumchlorid beobachtet werden. Die bisherigen Versuche sprechen dafur, das der Hemmeffekt bis zu einer Konzentration von ca. 0,1 M Saccharose wahrend kurzer Einwirkungszeit reversibel ist, bei hoheren Konzentrationen jedoch schon irreversible Zellschadigungen anzeigt.

The disc-gel electrophoretograms of aqueous crude extracts of organisms containing phycochromoproteins (Cyanobacteria, Rhodo- and Cryptophyta) give colored ‘fingerprints’, which are species specific and in many cases strain specific also (infraspecific variability). It was found that in a slightly acidic system (pH 4,3) the electrophoretograms in one single gel concentration (16% PAA) or the Hedrick-Smith plots for the phycochromoprotein bands represent a chemotaxonomic key for identification of Cyanobacteria species. The results summarized here in a list of chemotaxonomical and numerical data for 23 strains, allow one to distinguish between the size and charge isomers of the investigated biliproteids.

The morphologic description and measurements of endarterectomy specimens are usually believed to be accurate and are used as the gold standard against which the findings of diagnostic procedures are judged. Pathology data on 289 endarterectomy specimens from five participating centers and the corresponding angiography and B-mode ultrasonography data provided a basis for scrutinizing the validity of using the morphologic measurements as a standard. Discrepancies of greater than 1 mm between pathology and angiography measurements of minimum residual lumen occurred in 35% of the cases and between pathology and B-mode ultrasonography measurements in 64% of the cases. Discrepancies of greater than 1 mm between pathology- and angiography-measured lesion width occurred in 81% of the cases and between pathology and B-mode ultrasonography measurements in 64% of the cases. The cases representing mismatches of greater than 1 mm at one participating center were subjected to a rigorous review, with remeasurement of all morphologic features, in an attempt to explain the discrepancies. Various types of artifactual distortion of the specimens, the presence of slit-like and occluded lumens that were likely related to loss of perfusion pressure, and an inability to match planes of interrogation used in angiography and B-mode ultrasonography with pathology planes contributed significantly to the existence of mismatches. On the other hand, fixation and decalcification produced minimal and insignificant distortional changes. We conclude that the acquisition of quantitative data from endarterectomy specimens and the acceptance of morphologic data as a standard are limited by a number of problems that can be defined but have been difficult to resolve.

The inhibition effects of CHI and CA on the biosynthesis of the tetrapyrrolpigments were measured with two methods (in vivo VIS-spectroscopy, for chlorophyll (Chi) and the phycochromoproteids, 14C incorporation only for Chi). In the case of the Chl-biosynthesis both methods show the same results: a) In vivo VIS-spectroscopy demonstrates that the inhibition effect of CA manifests faster than that of CHI, b) during the 14C incorporation into Chi chloramphenicol (CA) inhibits more than cyclohexim ide (CHI) in contrary to the behaviour of chloroplasts. It seems that the CHI caused decrease of 14C incorporation into Chi can be ascribed to the decreased photosynthesis. The influence o f the antibiotics of the phycochrom oproteids is similar to that observed for chlorophyll. It is remarkable that under the influence of CHI the phycochromoproteid biosynthesis is significantly better than under CA influence, although CHI damages the consortium more than CA. That can be interpreted, as for chlorophyll, with a more endocytobiont coded phycochrom oproteid synthesis

To prove the extent to which the endocyanelle of C. paradoxa is autonomous with respect to the biosynthesis of its photosynthetic pigments, the degree, to which the translation inhibitors cycloheximide (CHI) and chloramphenicol (CA) influence the biosynthesis of carotenoids, was investigated by two methods (in vivo VIS-spectroscopy and photosynthetic l4C-incorporation into the pigments). During the first 6 h (in vivo VIS-spectra) the probes treated with the inhibitors show a similar increase of the total carotenoid content as the control, thereafter the inhibition by CHI is increased significantly at approx. 50% (18 h), by CA somewhat lower. The [14C]carbon- dioxide incorporation into β-carotene do not show any notable differences between the control culture and the cultures treated with inhibitors. Quite different to this observation is the behaviour of zeaxanthin. CHI shows an inhibition of 60% after 8 h, whereas CA accelerates the biosynthesis of zeaxanthin at +60% (to the control). Zeaxanthin has the same absolute concen­tration, but it was marked only ten times lower than β-carotene. The greater effect of CHI (in vivo VIS-spectra) should not be taken as a higher participation of the eukaryotic genome. In contrast that is only to ascribe to the inhibition of the photosynthetic activity, which is in the same order of magnitude. Additionally the behaviour of zeaxanthin seems to be more a sign for higher participation of the prokaryotic genome

Computer-based image processing methods have been applied to describe blood flow marker distribution in ischemic and nonischemic hearts. The processing begins with digitization of flow marker images derived from a heart slice containing the marker. Then, amplitude bands corresponding to intensity ranges of the indicator are created by Fourier-based filtration and amplitude mapping which together remove noise and demonstrate marker distribution topographically. Next, Cartesian plots of flow marker values averaged across transmural lines and lines normal to them are made to show marker distribution along selected radial and circumferential directions in heart walls. Finally, histograms of marker intensity are obtained to describe distnrbution of marker within regions bounded by arbitrarily shaped contours drawn on images. Flow marker distributions derived from photographs of Thioflavin S fluorescence and autoradiographs produced by 85Sr-labeled microspheres show both heterogeneity and distinct gradients in normal hearts, at infarct margins, and within ischemic zones. The local distribution of flow implied by Thioflavin S appeared more inhomogeneous than that indicated by the 85Sr-microspheres, probably as a consequence of the Thioflavin S fluorescence being a surface phenomenon. The available results indicate that this computer-based processing may provide a means of topographically relating flow marker and structural changes and also provide a high-resolution quantitative description of flow marker distribution in a flexible and efficient way for handling large amounts of data.

Methods to portray myocardial blood flow in a two-dimensional continuum are advantageous in that they allow blood flow history to be overlaid on histological or histochemical descriptions of the consequences of ischemia. We describe here autoradiographic methods that allow such portrayals at three separate times during the evolution of ischemic injury. A computer-based image-analysis system was used to derive such flow maps by taking advantage of the physical characteristics of radioactive isotopes.

Energy-dispersive x-ray spectroscopy and inductively coupled plasma emission spectrometry were evaluated as methods for routine multielement analysis of biological material. Standard samples included Standard Reference Materials (National Bureau of Standards), compounded mixtures, and supplements that provided a wide range of elemental concentrations for analysis. Elements included in this study were Zn, Pb, Ni, Mn, Fe, Mg, Cu, Ca, As, Se, Br, Rb, and Sr. Standards were analyzed as unknowns by participating laboratories. The two methods were evaluated for sensitivity, precision, and accuracy, and the results compared to those obtained for atomic absorption spectrometric analysis of identical standard unknowns. Both methods compared favorably and both were determined to be highly reliable for such an application. Advantages and disadvantages of each method are compared and discussed.

It is not clear whether an endocytobiont is able to develop during a long evolution tim e only to an organelle like cell structure (defect mutant) with a high degree of m etabolic dependency or also to a perfect cell organelle with genetical dependency to the host nucleus (intercom partm ental translocation of proteins and/or gene transfer) in the sense of the Serial Endocytobiosis Hypothesis (SEH). Cyanocyta korschokoffiana, the endocyanelle of C. paradoxa, seems to be a very suitable object to answer this question. Therefore we have studied the influence of the translation inhibitors cycloheximide (CHI) and chloramphenicol (CA) on the biosynthetic behaviour of this cyanobacterial endocytobiont regarding the photosynthetic oxygen during 20 h developing and incubation time. After dilution with fresh culture medium the oxygen evolution of the control culture remains nearly constant, if it is related to the phycocyanin content, whereas it increases slowly to a constant level relating to the chlorophyll content (nearly 140-150% of the starting activity). CHI and CA show a rapid effect on the oxygen evolution. At the first 8 - 10 h the oxygen evolution of cultures treated with CA are hardly dim inished and remain more or less constant with regard to the starting activity, but that of cultures treated with CHI decreases strongly. After 24 h the CHI treated flagellate is photosynthetically inactive and far-reaching destroyed (microscopic observations), indicating that CHI has beside the inhibition effects on protein synthesis also secondary effects on the stability of membranes of C. paradoxa

1. Die Schmerzschwellen am sensiblen Nerven wurden mit frequenten Kondensatorentladungen nachgepruft. Es ergibt sich dabei wieder ein Minimum fur eine bestimmte Frequenz, die nur erheblich hoher liegt, wie bei Reizung mit rechtwinkligen Stromstosen. 2. Es wird die Schwellenreizzahl fur die benutzten Frequenzen untersucht und die „Summationszeit“ berechnet. 3. Die Schmerzschwellen werden im leichten hypoglykamischen Zustand und leichtesten Alkoholrausch untersucht. Es ergibt sich, das diese beiden am Zentralnervensystem angreifenden Veranderungen die Schmerzschwellen im entgegengesetzten Sinne verschieben. Aus den Versuchen kann geschlossen werden, das die untersuchten Schmerzschwellen zentrale Schwellen sind.

Malate dehydrogenase isoenzymes from eight cyanophycean species were investigated with polyacrylamide disc gel electrophoresis. Using 7% acrylamide the pherograms from each species showed 5–8 zones with malate dehydrogenase activity. It was demonstrated that in Anabaena flos-aquae there are 8 isoenzyme bands which include 3 forms of equal molecular weight, two of which consist of several isomers differing in their net charge. The MDH zymograms of the blue-green algae investigated can be used as “fingerprints”. The isoenzyme pattern of the MDHs of Anacystis nidulans makes its position in the order Chroococcales uncertain.

The ferredoxin present in the chloroplasts of higher plants and algae is encoded by the nuclear genome. We found that this is not the case for the cyanellar ferredoxin of Cyanophora paradoxa. The coding and synthesizing site of this polypeptide was determined by selective inhibition of transcription and translation in the host and the cyanellar compartment, respectively. Water-soluble cyanellar proteins were isolated, extracted from in vivo 14C-labelled cells, separated by NEPHGE and analyzed by autoradiography. The results clearly showed that the ferredoxin must be encoded on the cyanellar genome. This finding is discussed in the context of the evolutionary position of C. paradoxa cyanelles as a model system with which to study intermediate stages between cyanobacteria and plastids.

Four cases of Barrett's esophagus are presented. Three cases presented with significant esophageal bleeding and one case presented with high esophageal stricture. Gastrointestinal panendoscopy was done in each case and multiple biopsies were taken. The biopsies were utilized for histomorphology, pepsinogen agar gel electrophoresis, and tissue gastrin assays. Tissue gastrin levels in esophageal mucosa were elevated in 2 cases when compared to controls with and without hiatus hernia. Pepsin and acid secretory studies were done by isolating the esophagus. Barrett's esophagus was shown to produce pepsin by both chemical studies (2 cases) and agar gel electrophoresis at pH 5.7 (3 cases), and was also shown to produce acid. The mucosa contained either cathepsin or cathepsin and pepsinogens in all cases. Nissen's fundoplication was performed in all of the patients. Of 3 patients who were bleeding, 2 who consented for this operation stopped bleeding after the operation. It is to be noted that the usual clinical treatment of antacids, bedrest, and raising the head end of the bed failed in all of the patients. The follow-up of 9 months to 3 years postoperatively has shown persistence of Barrett's mucosa with no evidence for any reversion to normal esophageal type.