A segment of rye chromosome 1 enhances growth and embryogenesis of calli derived from immature embryos of wheat

Summary The influence of the short arm of rye chromosome 1 (1RS) from Secale cereale var. Imperial on the growth and differentiation of callus cultures from wheat Triticum aestivum var. Chinese Spring immature embryos was analysed. This chromosome arm was found to stimulate both embryogenesis and the rate of growth of calli. Recombinant lines carrying segments of 1RS were used to delineate the regions of 1RS responsible for the tissue culture effects. The enhancement of embryogenesis and the stimulation of growth were shown to be associated with two distinct genetic regions of the chromosome arm; the former is located between the centromere and the Sec 1 locus, while the latter is situated in the immediate vicinity of the Sec 1 locus.     

The clinical significance of HAMA in patients treated with mouse monoclonal antibodies

Twenty-four patients were analyzed for the development of HAMA (human antimouse antibodies) after being treated with repeated doses (200–500 mg) of the mouse monoclonal antibody (MAb) 17-1A. All patients developed anti-17-1A IgG antibodies, and most of them also developed IgM antibodies. In only two patients could immune complexes be demonstrated. Allergic reactions were rare (1.9%). In an extended study, a further 19 patient were analyzed for an idiotypic response. Forty-one out of 43 patients developed antiidiotypic antibodies (ab₂), and 20 of these also antianti-idiotypic antibodies (ab₃). Ab₃ ⁺ patients responded significantly better (p=0.01) and survived longer (p<0.001) compared to ab₃ ⁻ patients. In this study, we showed that MAb 17-1A could be repeatedly given on a safe basis. The development of high titers of HAMA did not cause significant clinical problems when further repeated infusions of MAb 17-1A were given. The development of an idiotypic response also indicate that the induction of HAMA might be beneficial and not harmful to the patient.     

Biosurfactant yields and nutrient consumption of Pseudomonas fluorescens 378 studied in a microcomputer controlled multifermentation system

Production of biosurfactant AP-6 and consumption of carbon (succinic acid) and nitrogen (ammonium ions) by Pseudomonas fluorescens 378 were studied under different growth conditions. The study was performed in a microcomputer controlled multibatch fermentation system which enabled simultaneous running of 10 fermentors. The fermentors were mantled glass vessels, temperature controlled by circulated water, and mixing was arranged by magnetic stirrers. They were connected to the computer system (pH measurement and control) via signal conditioning cards. The microcomputer had a 128 kbytes RAM, two 800-kbyte floppy disc drives, a graphic terminal, and expansion cards. Biosurfactant production was independent of the carbon-to-nitrogen ratio and the phosphorus content in the medium. Omitting the Fe(III) supplement to the medium increased the product yield by 120%. Changes in oxygen transfer rate and pH in the iron deficient cultures did not have any effect on the product yield. Iron deficiency increased the cell consumption of carbon source. Consumption of carbon source in relation to nitrogen uptake (carbon/nitrogen quotient) increased with increasing quotient in the growth medium. The uptake of carbon and nitrogen changed in the intervals of 1.2-1.5 g/g biomass and 0.09-0.16 g/g biomass, respectively. The consumption of carbon increased from 1.5 g/g biomass to 2.0 g/g biomass when the medium concentration of phosphorus was decreased from 0.18 to 0.027 g/L.     

Stimulation of the anaerobic growth ofSalmonella typhimurium by reduction ofl-carnitine,carnitine derivatives and structure-related trimethylammonium compounds

In view of the development of al-carnitine deficiency, the metabolism ofl-carnitine and structure-related trimethylammonium compounds was studied inSalmonella typhimurium LT₂ by means of thin-layer chromatography (TLC).l-Carnitine, crotonobetaine and acetyl-l-carnitine stimulated the anaerobic growth in a complex medium significantly. The stimulation depended on the formation of -butyrobetaine. The reduction ofl-carnitine proceeded in two steps: (1) Dehydration of thel-carnitine to crotonobetaine, (2) hydrogenation of crotonobetaine to -butyrobetaine. The reduction of crotonobetaine was responsible for the growth stimulation. Terminal electron acceptors of the anaerobic respiration such as nitrate and trimethylamine N-oxide, but not fumarate, suppressed the catabolism ofl-carnitine completely. Glucose fermentation, too, inhibited the reduction ofl-carnitine but optimal growth with a high carnitine catabolism was achieved byd-ribose. The esters of carnitine with medium- and long-chain fatty acids inhibited the growth considerably because of their detergent properties.Abbreviations TLC thin-layer chromatography     

Biosynthetic pathways of Vibrio succinogenes growing with fumarate as terminal electron acceptor and sole carbon source

1. With fumarate as the terminal electron acceptor and either H₂ or formate as donor, Vibrio succinogenes could grow anaerobically in a mineral medium using fumarate as the sole carbon source. Both the growth rate and the cell yield were increased when glutamate was also present in the medium.
2. Glutamate was incorporated only into the amino acids of the glutamate family (glutamate, glutamine, proline and arginine) of the protein. The residual cell constituents were synthesized from fumarate.
3. Pyruvate and phosphoenolpyruvate, as the central intermediates of most of the cell constituents, were formed through the action of malic enzyme and phosphoenolpyruvate synthetase. Fructose-1,6-bisphosphate aldolase was present in the bacterium suggesting that this enzyme is involved in carbohydrate synthesis.
4. In the absence of added glutamate the amino acids of the glutamate family were synthesized from fumarate via citrate. The enzymes involved in glutamate synthesis were present.
5. During growth in the presence of glutamate, net reducing equivalents were needed for cell synthesis. Glutamate and not H₂ or formate was used as the source of these reducing equivalents. For this purpose part of the glutamate was oxidized to yield succinate and CO₂.
6. The α-ketoglutarate dehydrogenase involved in this reaction was found to use ferredoxin as the electron acceptor. The ferredoxin of the bacterium was reoxidized by means of a NADP-ferredoxin oxidoreductase. Enzymes catalyzing the reduction of NAD, NADP or ferredoxin by H₂ or formate were not detected in the bacterium.

     

Response analysis of vertebrate retina

In a recent work (Ouztöreli, 1980) a mathematical model for studying the neural activities in a vertebrate retina has been investigated, where the basic network contains five interconnected neurons: a receptor cell, a bipolar cell, a horizontal cell, an amacrine cell, and a retinal ganglion cell. More recently, in (Ouztöreli and O'Mara, 1980) the basic network has been extended to a larger network containing twelve neurons. In both of these works, the performances of the basic and extended models were discussed under different structural and processing conditions with constant inputs by using the results of one of our earlier work (Ouztöreli, 1979). In the present paper we investigate by simulations the responses of the basic retinal network to piecewise constant and periodic inputs. The step and frequency responses of the extended retinal network will be discussed in a forthcoming paper.This work was partially supported by the Natural Sciences and Engineering Research Council of Canada under Grant A-4345 through the University of alberta     

Pyruvate kinase “Göttingen1,2”: Congenital hemolytic anemia,evidence of double heterozygosity,and lack of enzyme cooperativity

Summary Double heterozygosity of pyruvate kinase (PK) deficiency associated with hereditary hemolytic anemia is emphasized by studies of a kindred harboring two distinct mutant forms of this enzyme. The hematologically unaffected parents exhibit slightly reduced PK activity, a normal Hill coefficient, and a normal thermodynamic dissociation constant for the overall reaction. The paternal enzyme is characterized by normal substrate affinities and decreased activities with the substrate analogues CDP and GDP, whereas the maternal enzyme shows normal affinity for PEP, but an increased affinity for ADP and low thermostability. It is assumed that the erythrocytes of the parents contain a mixture of normal PK and a functionally abnormal isoenzyme, the latter differing between the parents. The two children suffer from hereditary hemolytic anemia. Their PK must be a combination of the mutant paternal and maternal isoenzymes, and their activities are reduced to about 30%. These enzymes are characterized by an increased affinity for PEP and a decreased affinity for ADP, a Hill coefficient of about 1 (indicating lack of cooperativity due to a loss of its allosteric properties), a decreased overall catalytic activity, and a higher resistance to heat denaturation. Further differences are observed in the SDS-gel electrophoresis between the two patients' enzymes. From the enzymological point of view it is impossible to characterize true PK variants in such double heterozygous cases which contain a combination of two different isoenzymes. The cause of chronic hemolysis appears to depend mainly on the loss of the allosteric properties, i.e., the lack of enzyme cooperativity.     

Quantitative Bestimmung von Sulfhydrylgruppen mit Mercurochrom

Zusammenfassung Native Ehrlich-Ascites Tumorzellen (EATZ) werden in einer 1×10^–3 M Lösung von Dibrommercurifluoreszein (DBMF) in Sörensen-Phosphatpuffer pH 6.7+0,9% NaCl 30 min inkubiert und sodann viermal mit dem gleichen Puffer, der 0,01 M in bezug auf NaCN ist, bis zur Farblosigkeit des Überstandes gewaschen. Die Zellen zeigen nun ein Absorptionsmaximum zwischen 520 und 525 nm, das mit dem von Komplexen reiner Korpuskularproteine mit DBMF identisch ist. Die Zellen werden im Scanning bei 520 nm photometriert und daraus ihre Gesamtextinktionen ermittelt. Unter Zugrundelegung des in früheren Arbeiten bei den Protein-DBMF-Komplexen bestimmten Extinktions-koeffizienten =33 000 ergibt sich ein Gehalt von rund 1,1×10^–14 Molen Proteinthiolen (Prot-SH) pro Zelle. Dieser Wert entspricht sowohl dem von Nöhammer 1982 mit Dihydroxydinaphthyldisulfid gefundenen Gehalt an reaktiven, d.h. schnell reagierenden Prot-SH, als auch dem von Rindler et al. 1970 bestimmten SH-Gehalt der primär löslichen Zellproteine. Da aus nativ mit DBMF behandelten Zellen jedoch keine im Homogenat-Puffer löslichen Proteine gefunden wurden, ist es wahrscheinlich, daß DBMF mit den schnellen SH-Gruppen der Cytosol-Proteine reagiert, die dabei strukturelle Veränderungen erfahren, die zum Löslichkeitsverlust führen. DBMF erfaßt jedoch die gesamten Prot-SH, reaktive und maskierte, wenn es auf vorher fixierte Zellen einwirkt (Nöhammer et al. 1981). Ist der zum Waschen verwendete Puffer Cyanid-frei, so wird die identische Absorptionsbande gemessen; die für E _tot,520 ermittelten Werte sind jedoch um 60% höher. Die Differenz wird nicht-kovalent, reversibel an die Zellen gebundenem DBMF zugeschrieben.

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Quantitative determination of sulfhydryl groups with MercurochromeII. Detection of fast reacting protein thiols in native cells

Summary Native Ehrlich ascites tumor cells (EATC) are incubated during 30 min in a 1×10^–3 M solution of dibrommercurifluoresceine (DBMF) in Sörensen phosphate buffer pH 6.7+0.9% NaCl. Subsequently the cells are washed four times in the same buffer containing additionally 0.01 M NaCN until the supernate appears to be colourless. They show an absorption maximum between 520 and 525 nm which is identical with that of complexes between pure corpuscular proteins and DBMF, investigated previously. Scanning at 520 nm yields the total extinction of the stained cells E _tot which is calculated into moles of protein bound thiol groups (prot-SH), with an extinction coefficient =33,000 previously determined with the protein-DBMF-complexes. A mean protein-SH content of 1.1×10^–14 moles per single cell is found which corresponds with both the content of fast reacting prot-SH previously determined by Nöhammer with dihydroxydinaphthyldisulfide, and the SH-content of the soluble cellular proteins determined by Rindler et al. with DTNB. As no soluble proteins could be obtained from DBMF-treated cells, it can be assumed that in native cells DBMF reacts preferentially with the fast reacting SH-groups of the soluble proteins which, in the course of structural changes, became insoluble. According to Nöhammer et al. (1981), however, DBMF also reacts with the total of protein-SH content of 1.1×10^–14 moles per single cell is found which fixed with ethanol/ether. When the buffer used for washing is free from CN^–, the identical absorption band is measured; however, the values determined for E _tot,520 are approximately 60% higher. The extinction difference is ascribed to DBMF, noncovalently and reversibly bound to the cells.