Fermentation of potato mash,potato mash/maltrin mixtures,maltrin and wheat starch usingZymomonas mobilis

Summary Potato mash, potato mash/maltrin mixtures, maltrin and wheat starch have been fermented with 95 to 98% conversion efficiencies. Highest ethanol yields obtained were 13.5% (v/v) in 24 h. The addition of 20% backset (= thin stillage) or change of pre-culture conditions did not affect the process.

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Fermentation de purée de pommes de terre seule et en mélange avec la maltrine, de maltrine seule et d'amidon de froment par Zymomonas mobilis

Résumé On fermente la purée de pommes de terre seule et en mélange avec la maltrine ainsi que l'amidon de froment jusqu'à 95 à 98% d'efficacité de conversion. Les rendements les plus élevés en éthanol sont de 13.5% (v/v) en 24 h. Le recyclage de 20% de résidu fluide de fermentation ou le changement des conditions de préculture n'affectent pas le processus.

     

Catabolic Regulation of the Expression of the Major Myelin Glycoprotein by Schwann Cells in Culture

Previous studies have suggested that neonatal Schwann cell cultures deprived of axonal contact do not express components of the myelin membrane, including the major myelin glycoprotein, P0. In contrast, Schwann cells from permanently transected, adult nerve exhibit continued biosynthesis of P0 after culture, suggesting that the ability to express the myelin glycoprotein may depend on the degree of cellular differentiation. To examine further the ability of Schwann cell cultures to express P0 as a function of age, we have performed precursor incorporation studies on endoneurial explants from 4- to 12-day-old rat sciatic nerves after 5 days in culture. The data reveal that explants from 12-day-old animals synthesize detectable levels of this integral myelin protein when assayed by [3H]mannose incorporation, even though there is no apparent myelin assembly in the cultures. Pulse-chase analysis of cultures from 12-day-old rats demonstrates that [3H]mannose-labeled P0 is substantially degraded within 3 h. This catabolism largely can be prevented by the addition of swainsonine, ammonium chloride, or L-methionine methyl ester to the pulse-chase media. The former agent alters oligosaccharide processing whereas the latter two compounds inhibit lysosomal function. The P0 synthesized by the 12-day explant cultures following the addition of swainsonine is readily fucosylated, implying that the protein has progressed at least as far as the medial Golgi before its exit and subsequent catabolism. If cultures from 4-, 6-, and 8-day-old animals are analyzed for P0 biosynthesis by [3H]mannose incorporation in the presence of swainsonine, detectable levels of the glycoprotein are seen.(ABSTRACT TRUNCATED AT 250 WORDS)     

Identification of a widely distributed 90-kDa glycoprotein that is homologous to the Hermes-1 human lymphocyte homing receptor

Homing of recirculating lymphocytes from the blood into the lymphoid tissues is mediated by 90-kDa homing receptors on the lymphocyte cell surface, allowing selective binding to specialized endothelium lining high endothelial venules. This study describes two novel mAb, NKI-P1 and NKI-P2, directed against functional epitopes of a human lymphocyte homing receptor, gp90. Biochemical studies demonstrated that these antibodies recognize a 90-kDa glycoprotein which is similar to the Ag recognized by the mAb Hermes-1. This notion was confirmed by immunohistochemical studies showing identical reaction patterns. Furthermore, it was observed that NKI-P1 and NKI-P2 blocked adhesion of lymphocytes to high endothelial venules. Immunohistochemical, immunofluorescence, and immunoprecipitation studies revealed that gp90 is widely expressed on hemopoietic cells including lymphocytes, macrophages/dendritic cells, myeloid cells, and erythrocytes. The gp90 is also expressed on a number of nonhemopoietic cells such as endothelial cells, certain epithelial cells, and fibroblasts. In addition to its expression on normal cells, gp90 is present on a spectrum of tumor cell lines of lymphoid, monocytic, epithelial, glial, and melanocytic origin. In addition to the 90-kDa product, the antibodies immunoprecipitate several polypeptides in the range of 120 to 200 kDa. Interestingly, it was observed that certain mamma tumor cell-line cells lack the 90-kDa polypeptide indicating the heterogeneous expression of the molecules recognized by the antibodies. These results indicate that the 90-kDa glycoprotein homologues of the Hermes-1 human lymphocyte homing receptor are expressed on hemopoietic tissues as well as on a number of nonhemopoietic tissues and tumor cell lines. Although the function of these molecules in nonlymphoid cells is presently unknown, they might play a role in cell-cell or cell-matrix adhesion.     

Electron spin resonance evidence for the formation of free radicals in plants exposed to ozone

Electron spin resonance (ESR) spectroscopy was used to demonstrate that free radicals are formed in O₃-fumigated plant leaves prior to the formation of visible leaf injury. ESR signals with a g-value of 2.0037 to 2.0043, were observed in pea ( Pisum sativum L. cv. Feltham first) and bean ( Phaseolus vulgaris L. cv. Pinto) plants that had been fumigated for 4 h with 70–300 nl l⁻¹ of ozone after they had been treated with the spin-trap N- t -butyl-α-phenylnitrone (PBN). The size of the ESR signals increased with the concentration of ozone used but the nature of the trapped radicals could not be identified. However, further experiments using an inhibitor of ethylene biosynthesis, arninoethoxyvinyl glycine (AVG), showed that the reaction between ozone and ethylene is the cause for ozone toxicity.     

Mechanical impedance increases aluminium tolerance of soybean (Glycine max) roots

The effect of aluminium (Al) on root elongation was studied in solution culture and sand culture. Compared to solution culture, in sand culture a ten times higher Al supply was necessary to inhibit root elongation to a comparable degree. This was due to a much lower Al uptake into the 5 mm root tips in sand culture. Fe concentrations in root tips were also lower in sand culture. Ca concentrations were higher and less depressed by Al, whereas Mg and K concentrations were not affected by the culture substrate. Regressions of Al concentrations in root tips versus inhibition of root elongation by Al revealed root damage at lower Al concentrations in sand culture. The effect of culture substrate on Al tolerance was independent of N source and could also be shown in flowing solution culture with and without sand. The results indicate that mechanical impedance in sand culture decreased Al uptake. This may be due to enhanced exudation of organic complexors thus reducing activites of monomeric Al species.     

Seasonal nitrogen and carbon concentrations in white,brown and woody fine roots of sugar maple (Acer saccharum Marsh)

Small diameter (<1.0-mm) Acer saccharum Marsh roots were separated into white, brown and woody development state classes and analyzed for total N and C concentrations in April, July and October of 1988. White roots had greater concentrations of N and C than either brown or woody roots at each sampling date, and the N concentration of brown roots was consistently greater than that of woody roots. There were no temporal changes in N concentrations in any of the roots. C was slightly elevated in mid-summer in all three classes of roots. The data suggest the possible existence of an N translocation mechanism in ageing and developing fine roots. More research should be undertaken to establish the mechanisms of N loss in developing fine roots.     

Isolation of a crustaceann-acetyl-d-glucosamine-1-phosphate transferase and its activation by phospholipids

Summary Then-acetyl-d-glucosamine-1-phosphate: dolichol phosphate transferase fromArtemia has been partially purified and characterized. The enzyme is solubilized from crude microsomes using Triton X-100, and after detergent removal appears to be associated with phospholipids. Using dolichol phosphate and UDP-n-acetyl-d-glucosamine as substrates, the enzyme catalyzes the formation of dolichol-pyrophosphate-n-acetyl-d-glucosamine. the product identity has been verified by TLC and paper chromatography following mild acid hydrolysis. Under the incubation conditions used only one product is made, i.e., Dol-p-p-GlcNAc. The formation of product is linear with increasing amounts of added protein and with time of incubation. The enzyme requires magnesium ions for activity. Activity of the enzyme is stimulated 6-fold by exogenous dolichol phosphate and is also stimulated by added phospholipids, with optimal activity being obtained in the presence of mixtures of phosphatidylcholine and phosphatidylglycerol. Enzymatic activity is not increased upon addition of GDP-mannose or dolichol phosphate mannose. The enzyme is rapidly inactivated by exposure to several detergents, including Triton X-100 and deoxycholate. The activity is inhibited by tunicamycin and by the purified B₂ homologue of this antibiotic. Other antibiotic inhibitors such as diumycin and polyoxin D have little effect on the enzyme. Both the microsomal and solubilized enzyme preparations are inactivated by 70% upon treatment with phospholipase A₂; activity may be restored by addition of phospholipids. Following hydrophobic interaction chromatography on Phenyl Sepharose, gel filtration chromatography on Sepharose CL-4B indicated that the enzyme, purified 81-fold, contained phophatidylcholine and phosphatidyl-ethanolamine.Abbreviations SDS sodium dodecyl sulfate - PMSF phenyl methanesulfonylfluoride - HEPES 4-(2-hydroxyethyl)-1-piperazineethane sulfonic acid - GlcNAc N-acetyl-d-glucosamine - Dol-PP-GlcNAc dolichol pyrophosphate N-acetyl-d-glucosamine - Dol-P-man dolichol-phosphate-mannose - Dol-PP- (GlcNAc)₂ dolichol-pyrophosphate-di-N- acetylchitobiose - DMSO dimethylsulfoxide - C:M (2:1) chloroform:methanol (2:1) - C:M:W (10:10:3) chloroform:methanol:water (10:10:3) - GlcNAc-1-P N-acetyl-d-glucosamine-1-phosphate - Dol-P dolichol phosphate - EGTA ethylene glycol bis (b-aminoethyl ether)-NNNN tetraacetic acid     

Applications of minirhizotrons to understand root function in forests and other natural ecosystems

Minirhizotrons have proved useful to understand the dynamics and function of fine roots. However, they have been used comparatively infrequently in forests and other natural plant communities. Several factors have contributed to this situation, including anomalous root distributions along the minirhizotron surface and the difficulty of extracting data from minirhizotron images. Technical and methodological advances have ameliorated some of these difficulties, and minirhizotrons have considerable potential to address some questions of long standing interest. These questions include more fully understanding the role of roots in carbon and nutrient cycling, rates of root decomposition, responses to resource availability and the functional significance of interactions between plant roots and soil organisms. Maximizing the potential for minirhizotrons to help us better understand the functional importance of fine roots in natural plant communities depends upon using them to answer only those questions appropriate to both their inherent strengths and limitations.