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91.
Osmoregulation in Escherichia coli by accumulation of organic osmolytes: betaines,glutamic acid,and trehalose 总被引:42,自引:0,他引:42
Like other cyanobacteria, Chlorogloeopsis fritschii contained as major lipid classes monogalactosyldiacyl-glycerols, digalactosyldiacylglycerols, sulfoquinovosyldiacylglycerols and diacylglycerophosphoglycerols. In addition to these lipid classes this cyanobacterium also contained small amounts of diacylglycerophosphocholines and sterols, predominantly lanosterol, thus showing similarity to photosynthetic eukaryotes. Dark incubated cells contained larger proportions of the latter two lipid classes than light grown cells. Like other prokaryotes, C. fritschii lacked linolenic acid (18:3) in its lipids. Lipids from the thylakoids were richer in palmitoleic acid (16:1) than those of whole cells. There was no effect of light on the patterns of constituent fatty acids of lipids from C. fritschii, in contrast to photosynthetic eukaryotes.Abbreviations MGDG
Monogalactosyldiacylglycerols
- PA
Phosphatidic acids
- PE
Diacylglycerophosphoethanolamines
- PG
Diacylglycerophosphoethanolamines
- DGDG
Digalactosyldiacylglycerols
- SQDG
Sulfoquinovosyldiacylglycerols
- PC
Diacylglycerophosphocholines 相似文献
92.
Marina Ripamonti Silvana Canevari Sylvie Ménard Delia Mezzanzanica Silvia Miotti Rosaria Orlandi Franco Rilke Elda Tagliabue Maria Ines Colnaghi 《Cancer immunology, immunotherapy : CII》1987,24(1):13-18
Summary In order to investigate in vivo clinical applications of murine monoclonal antibodies directed against human ovarian carcinoma a preclinical in vivo model was developed using BALB/c athymic mice. Three human carcinoma cell lines (MCF7, HT29, and SW626) were injected into the peritoneal cavity of pristane-primed animals and the biological and antigenic characteristics of the i.p. grown tumors were studied. The animals were killed when moribund or 6–8 weeks after tumor injection. At autopsy tumor take was observed in 85% of the injected animals, whereas palpable nodules were evident in only 83%. Examination of the peritoneal cavity revealed intraabdominal carcinomatosis with tumor masses varying in size between 0.2 and 0.5 cm in diameter and tumor sheets. The most frequently affected organs were the diaphragm, the liver, and the reproductive system. Ascitic fluid formation was rare and no animal developed tumors outside the peritoneal cavity. To determine whether the in vivo tumors retained the same antigenic characteristics as the in vitro cell lines, four monoclonal antibodies (MBrl, MOv2, MOv8, and MOv15) directed against ovarian carcinoma-associated antigens and two different experimental approaches (immunofluorescence and immunoblotting) were used. Variations at either a quantitative or a qualitative level were observed for some antigens, whereas no evident changes were apparent for others. In particular, the antigens detected by MBr1 and MOv15 on the MCF7 line both maintained high levels of expression and immunoblotting staining pattern, whereas the antigens detected by MOv2 on the HT29 and SW626 lines, although present at a high level, clearly changed their staining pattern. As regards the antigens recognized by MOv8 and MOv15 on the HT29 and SW626 lines, we observed a drastic decrease in the level of their expression and in many cases a drop below the threshold of detectability of the test. The intraabdominal carcinomatosis described partially mimics the growth characteristics of human ovarian cancer and maintains the expression of some antigenic markers associated with epithelial tumors of the ovary and may therefore be useful in devising immunodiagnostic and/or immunotherapeutic strategies for ovarian carcinoma. 相似文献
93.
Cell-free extracts ofAnacystis nidulans were fractionated by discontinuous sucrose density gradient centrifugation resulting in the separation of two distinct types of membranes, the heavier one containing the chlorophyll and the lighter one devoid of chlorophyll. Identity of the latter with plasma membrane was confirmed by labeling of intact cells with impermeant marker,35S-diazobenzenesulfonate, prior to cell disruption. Both membrane fractions were purified individually by repeated recentrifugation on identical gradients. Purified membranes were subjected to dissociating polyacrylamide gel electrophoresis, either type of membranes yielding a distinct polypeptide pattern. After transfer of the polypeptides to nitrocellulose by Western blotting, two of the proteins, with molecular weights of approximately 55,000 and 32,000, respectively, gave strong and specifically complementary cross-reactions with antibodies raised against subunits I and II of the aa3-type cytochrome oxidase fromParacoccus denitrificans. The findings will be discussed in terms of the presence of aa3-type cytochrome oxidase in both plasma and thylakoid membranes ofAnacystis nidulans. 相似文献
94.
Matilde Jose Isabelle Tratner Maryse Poiret Jean-Louis Nahon Jean-Louis Danan Jose Maria Sala-Trepat 《Molecular & general genetics : MGG》1989,215(2):225-230
Summary The distribution of middle repetitive sequences in the genic and extragenic regions of the rat albumin and -fetoprotein genes was analyzed. Their presence was determined by probing Southern blots of restriction fragments of albumin and -fetoprotein genomic subclones with 32P-labeled total rat DNA. Repetitive sequences were detected in both genes. They were classified as weak, moderate and intense hybridizing elements according to the intensity of hybridization. Weak repetitive sequences were characterized as dG·dT repeats by using 32P-labeled poly-(dG·dT)(dC·dA) oligomer probe. They occurred in 5 and 3 extragenic regions of the two genes and in introns 4 and 5 of the albumin gene. The moderate repetitive sequence present in intron 6 of the albumin gene was identified as the rat SINES element, 4D12. The intense repetitive sequence, localized in the 3 non-coding region of the albumin gene, corresponded to the terminal segment of a rat high repeat long interspersed DNA family, L1Rn. 4D12 and L1Rn sequences were also scattered throughout the -fetoprotein locus as moderate and intense repetitive elements, respectively, but their distribution was different from that of the albumin genomic region. These results indicate that repetitive sequences invaded the two loci in a non-conservative manner. 相似文献
95.
De novo root formation in thin cell layers of tobacco: changes in free and bound polyamines 总被引:4,自引:0,他引:4
Patrizia Torrigiani Maria Maddalena Altamura Francesca Capitani Donatella Serafini-Fracassini Nello Bagni 《Physiologia plantarum》1989,77(3):294-301
Thin cell layers excised from tobacco ( Nicotiana tabacum L. cv. Samsun) stem internodes, with an appropriate exogenous hormonal balance, were able to form a greater number of roots, and in a larger percentage of the explants (93%) than when they were excised from pedicels (40%). The developmental sequence of root formation and explant growth were followed by histological analysis. Free and bound [trichloroacetic acid (TCA)-soluble and -insoluble] putrescine and spermidine increased in the explants, particularly when root meristemoids appeared. These meristemoids originated in the superficial (day 6 in culture) or deep (days 10–11) layers and inside the newly formed callus (day 25). At those times, TCA-soluble and, to a lesser extent, TCA-insoluble bound putrescine predominated over the other polyamines. Spermine was always present in trace amounts. Polyamines decreased again when root and callus formation was completed (day 30). The involvement of these three classes of polyamines (free, TCA-soluble and -insoluble) in morphogenic processes is discussed. 相似文献
96.
Biosynthesis of the Cyanogenic Glucoside Dhurrin in Seedlings of Sorghum bicolor (L.) Moench and Partial Purification of the Enzyme System Involved 总被引:3,自引:1,他引:2 下载免费PDF全文
The cyanogenic glucoside dhurrin is rapidly synthesized in etiolated seedlings of Sorghum bicolor (L.) Moench. The dhurrin content of the seedlings increases sigmoidally with the germination time. Shoots of 10 centimeters height contain 850 nanomoles of dhurrin per shoot corresponding to 6% of the dry weight. The biosynthetic activity sharply rises upon germination and reaches a maximum level of 10 nanomoles dhurrin/(hour × shoot) after 48 hours when the shoots are 3 centimeters high. This maximum level is followed by a sharp decline in activity when germination time exceeds 65 hours. Dhurrin and the dhurrin-synthesizing enzyme system are primarily located in the upper part of the etiolated shoot where both are evenly distributed between the coleoptile, the primary leaves and the upper 0.5 centimeter of the first internode including the shoot apex. Dhurrin constitutes 30% of the dry weight of the upper 1.2 centimeter of 10 centimeter high shoots. The seed and root contain neither dhurrin nor the dhurrin-synthesizing enzyme system. The codistribution of dhurrin and the enzyme system throughout the seedling indicates that production and storage sites are located within the same cell. Purification of the dhurrin-synthesizing enzyme by gel filtration or by sucrose gradient centrifugations results in a tenfold increase in specific activity. Further purification is accompained by a decline in specific activity due to loss of essential components as demonstrated by reconstitution experiments. 相似文献
97.
98.
Maria C. Nieto Elizabeth S. Song Denise McKinney Minnie McMillan Robert S. Goodenow 《Immunogenetics》1989,30(5):361-369
We have analyzed changes in the antigenicity of major histocompatibility complex class I molecules resulting from the association
of human beta-2 micro-globulin (B2m) with the mouse class I heavy chain. In particular, the H-2Ld molecule exhibited enhanced crossreactivity for the 34-1-2 monoclonal antibody. In order to assess the nature of this structural
alteration induced by human B2m, we utilized H-2 class I hybrid molecules in the mapping of the 34-1-2 determinant to the
helical region of the alpha-1 domain. H-2Ld class I hybrid molecules were then used to establish the importance of the alpha-2 and- 3 domains in the observed increase
of 34-1-2 cross-reactivity following exchange with human B2m. The H-2Ld hybrids suggest that alterations in interdomain contact are responsible for enhanced 34-1-2 cross-reactivity on the H-2Ld molecule. It is likely that this alteration arises through changes in class I conformation at regions of the molecule distant
from points of contact between B2m and the class I molecule. This suggests that perturbations induced by association of human
B2m with H-2Ld can affect the conformation of the alpha-1 and- 2 superdomain. That class I antigenic determinants are altered by the association
of human B2m with mouse class I further suggests that the class I molecule is structurally flexible and may reflect the ability
of the class I molecule to bind and present a vast array of disparate peptides to the T-cell receptor. 相似文献
99.
Cathepsin S from bovine spleen. Purification, distribution, intracellular localization and action on proteins. 总被引:8,自引:2,他引:6 下载免费PDF全文
Cathepsin S was detected in bovine kidney, spleen, lymph nodes and lung by immunochemical methods. The immunostaining of cathepsin S in kidney was concentrated to the cells of the proximal tubule, where the enzyme was present in cytoplasmic granules. The purification method for cathepsin S from bovine spleen involved (NH4)2SO4 fractionation, chromatography on CM-Sephadex C-50, gel filtration on Sephacryl S-200 and chromatofocusing (pH 8.0-6.0). The enzyme was partially destroyed by autolysis of the homogenate at pH 4.2. The isoelectric point of cathepsin S was 7.0. Cathepsin S was found to hydrolyse proteins at a similar rate to cathepsin L below pH 7.0. At pH values of 7.0-7.5 cathepsin S retained most of its activity, whereas cathepsin L was completely inactive. 相似文献
100.
Hydrolysis of sunflower oil by means of hydrophobic membrane with lipolytic activity 总被引:3,自引:0,他引:3
Magdalena Rucka Bozena Turkiewicz Maria Tomaszewska Nikodem Chlubek 《Biotechnology letters》1989,11(3):167-172
Polytetrafluoroethylene (PTFE) membranes of different porosity were used for lipase from Rhizopus immobilization. The immobilized enzyme applied to sunflower oil hydrolysis achieved the activity of 1228 U/m2 of the membrane area and the half-life time was calculated to be 7 days. 相似文献