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71.
72.
Gynodioecy, the coexistence of hermaphrodites and male steriles, is frequent in populations of Plantago lanceolata L. A condition for the maintenance of gynodioecy in an obligatory outbreeding species like this is an increase in female fitness in male steriles compared with hermaphrodites. One of the possible underlying mechanisms, a lower cyanide-resistant respiration in male steriles, which could lead to a higher metabolic efficiency, was investigated. For the experiments adult plants were used, because the effects which compensate for male sterility have been found in characters like seed production and longevity. No general correlation between sex phenotype and cyanide-resistant respiration capacity, or with any other respiration component, was found. Only in a single cross a strong correlation between cyanide-resistant respiration activity and sex phenotype was established, male steriles possessing the higher activity. The conclusion from these experiments is that there is no pleiotropic relationship between respiration levels and sex phenotype. The strongly significant correlation mentioned is ascribed to chromosomal linkage. 相似文献
73.
Comparative biochemical and immunological studies of the glycine betaine synthesis pathway in diverse families of dicotyledons 总被引:10,自引:0,他引:10
Elizabeth A. Weretilnyk Sebastian Bednarek Kent F. McCue David Rhodes Andrew D. Hanson 《Planta》1989,178(3):342-352
Members of the Chenopodiaceae can accumulate high levels (>100 mol·(g DW)-1) of glycine betaine (betaine) in leaves when salinized. Chenopodiaceae synthesize betaine by a two-step oxidation of choline (cholinebetaine aldehyde betaine), with the second step catalyzed by betaine aldehyde dehydrogenase (BADH, EC 1.2.1.8). High betaine levels have also been reported in leaves of species from several distantly-related families of dicotyledons, raising the question of whether the same betaine-synthesis pathway is used in all cases.Fast atom bombardment mass spectrometry showed that betaine levels of >100 mol·(g DW)-1 are present in Lycium ferocissimum Miers (Solanaceae), Helianthus annuus L. (Asteraceae), Convolvulus arvensis L. (Convolvulaceae), and Amaranthus caudatus L. (Amaranthaceae), that salinization promotes betaine accumulation in these plants, and that they can convert supplied choline to betaine aldehyde and betaine. Nicotiana tabacum L. and Lycopersicon lycopersicum (L.) Karst. ex Farw. (Solanaceae), Lactuca sativa L. (Asteraceae) and Ipomoea purpurea L. (Convolvulaceae) also contained betaine, but at a low level (0.1–0.5 mol·(g DW)-1. Betaine aldehyde dehydrogenase activity assays, immunotitration and immunoblotting demonstrated that the betaine-accumulating species have a BADH enzyme recognized by antibodies raised against BADH from Spinacia oleracea L. (Chenopodiaceae), and that the Mr of the BADH monomer is in all cases close to 63 000. These data indicate that the cholinebetaine aldehydebetaine pathway may have evolved by vertical descent from an early angiosperm ancestor, and might be widespread (albeit not always strongly expressed) among flowering plants. Consistent with these suggestions, Magnolia x soulangiana was found to have a low level of betaine, and to express a protein of Mr 63 000 which cross-reacted with antibodies to BADH from Spinacia oleracea.Abbreviations BADH
Betaine aldehyde dehydrogenase
- DCIMS
desorption chemical ionization mass spectrometry
- FABMS
fast atom bombardment mass spectrometry
- Mr
relative molecular mass
- PAGE
polyacrylamide gel electrophoresis
- SDS
sodium dodecyl sulfate
- TLC
thin-layer chromatography 相似文献
74.
Rate of trypanosome killing by lectins in midguts of different species and strains of Glossina 总被引:4,自引:0,他引:4
The activity of lectins in different species of tsetse was compared in vivo by the time taken to remove all trypanosomes from the midgut following an infective feed and in vitro by agglutination tests. Teneral male Glossina pallidipes Austen, G. austeni Newstead and G. p. palpalis R-D. removed 50% of all Trypanosoma brucei rhodesiense Stephens & Fantham infections within 60 h. A 'refractory' line of G. m. morsitans Westwood took 170 h to kill 50% infections while a 'susceptible' line of the same species failed to kill 50%. Agglutination tests with midgut homogenates showed differences between fly stocks which accorded with differences in rate of trypanosome killing in vivo. Flies fed before an infective feed were able to remove trypanosomes from their midguts more quickly than flies infected as tenerals. Increasing the period of starvation before infection increased the susceptibility to trypanosome infection of non-teneral flies. Teneral flies showed little agglutinating activity in vitro, suggesting that lectin is produced in response to the bloodmeal. Feeding flies before infection also abolished the differences in rate of trypanosome killing found between teneral 'susceptible' and 'refractory' G. m. morsitans, suggesting that maternally inherited susceptibility to trypanosome infection is a phenomenon limited to teneral flies. Electron micrographs of midguts of G. m. morsitans suggest that procyclic trypanosomes are killed by cell lysis, presumably the result of membrane damage caused by lectin action. 相似文献
75.
Archaeoglobus fulgidus is an extremely thermophilic archaebacterium that can grow at the expense of lactate oxidation with sulfate to CO2 and H2S. The organism contains coenzyme F420, tetrahydromethanopterin, and methanofuran which are coenzymes previously thought to be unique for methanogenic bacteria. We report here that the bacterium contains methylenetetrahydromethanopterin: F420 oxidoreductase (20 U/mg), methenyltetrahydromethanopterin cyclohydrolase (0.9 U/mg), formyltetrahydromethanopterin: methanofuran formyltransferase (4.4 U/mg), and formylmethanofuran: benzyl viologen oxidoreductase (35 mU/mg). Besides these enzymes carbon monoxide: methyl viologen oxidoreductase (5 U/mg), pyruvate: methyl viologen oxidoreductase (0.7 U/mg), and membranebound lactate: dimethylnaphthoquinone oxidoreductase (0.1 U/mg) were found. 2-Oxoglutarate dehydrogenase, which is a key enzyme of the citric acid cycle, was not detectable. From the enzyme outfit it is concluded that in A. fulgidus lactate is oxidized to CO2 via a modified acetyl-CoA/carbon monoxide dehydrogenase pathway involving C1-intermediates otherwise only used by methanogenic bacteria.Non-standard abbreviations APS
adenosine 5-phosphosulfate
- BV
benzyl viologen
- DCPIP
2,6-dichlorophenolindophenol
- DMN
2,3-dimethyl-1,4-naphthoquinone
- DTT
DL-1,4-dithiothreitol
- H4F
tetrahydrofolate
- H4MPT
tetrahydromethanopterin
- CH2
H4MPT, methylene-H4MPT
- CH
H4MPT, methenyl-H4MPT
- Mes
morpholinoethane sulfonic acid
- MFR
methanofuran
- Mops
morpholinopropane sulfonic acid
- MV
methyl viologen
- Tricine
N-tris(hydroxymethyl)-methylglycine
- U
mol product formed per min 相似文献
76.
James M. Chen Grace Lee Paul W. Brandt-Rauf Randall B. Murphy Shalom Rackovsky Matthew R. Pincus 《Journal of Protein Chemistry》1990,9(5):543-547
The predicted conformation and position of the central transforming region (residues 55–67) of the p21 protein are compared with the conformation and position of this segment in a recently determined X-ray crystal structure of residues 1–166 of this protein in the activated state bound to a nonhydrolyzable GTP derivative. We previously predicted that this segment of the protein would adopt a roughly extended conformation from Ile 55-Thr 58, a reverse turn at Ala 59-Gln 61, followed by an -helix from Glu 62-Met 67. We further predicted that this region of the activated protein occupies a position that is virtually identical to corresponding regions in the homologous purine nucleotide-binding proteins, bacterial elongation factor (EF-tu), and adenylate kinase (ADK). We find that there is a close correspondence between the conformation and position of our predicted structure and those found in the X-ray crystal structure. A mechanism for activation of the protein is proposed and is corroborated by X-ray crystallographic data. 相似文献
77.
Ludwig M. G. Heilmeyer Jr. Jeung-Whan Han Rolf Thieleczek Magdolna Varsanyi Georg W. Mayr 《Molecular and cellular biochemistry》1990,99(2):111-116
Skeletal muscle triads are possessing the whole set of enzymes of the phosphatidylinositol (PI)-linked signal generating pathway, PI-kinase, PI(4)P-kinase, and PI(4,5)P2-phospholipase C (PLC). The activities of these enzymes are comparable to those found in other cell types for which a functional role of the PI-pathway in intracellular signal transduction has been established. For skeletal muscle an unequivocal function and an initiating signal for Ins(1,4,5)P3-liberation is still unknown. However, the observed Ca-dependency of PLC activity suggests that here Ins(1,4,5)P3 production is a consequence rather than a cause of increasing cytosolic Ca2+. Recently, the glycolytic enzyme aldolase, whose activity can be modulated by inositol polyphosphates, has been localized in the triadic structure. The enzyme which has a high affinity to Ins(1,4)P2, Ins(1,4,5)P3 and Ins(1,3,4,5)P4, seems to be compartmentalized to the junctional foot structure from which it is released upon binding of these molecules. This phenomenon could reflect a capability for regulation of the glycolytic flux even for aldolase, especially if a non steady-state situation in the junctional gap is considered. Meanwhile we have accumulated evidence for the operation of a partial glycolytic sequence in the junctional region established by the enzymes aldolase, glyceraldehyde-3-P (GAP) dehydrogenase and phosphoglycerate kinase. This system is able to produce ATP upon oxidation of GAP and could be, because of the inositol polyphosphate-sensing abilities of aldolase, a target for the membrane associated PI-pathway. The ATP production is however transient which indicates the coupling to an ATP hydrolyzing reaction. Thus, it appears that the ATP produced by the membrane associated system is effectively utilized by an ATP consuming membrane localized system like PI-metabolism or protein kinases. There are indications that exogeneously added ATP does not equilibrate with the ATP synthesized in the junctional region which suggests an effective structural or kinetical compartmentalization of this system. Therefore it is hypothesized that the ATP synthesized by the membrane associated glycolytic sequence is utilized in membrane localized reactions. 相似文献
78.
Frans P. Houwen Jeannette Plokker Alfons J. M. Stams Alexander J. B. Zehnder 《Archives of microbiology》1990,155(1):52-55
Enzyme measurements were carried out with crude cell-free extracts of the propionate oxidizing coculture of Syntrophobacter wolinii and Desulfovibrio G11. Using cell-free extracts of a pure culture of Desulfovibrio G11 as a blank, most of the enzymes involved in the methylmalonyl-CoA pathway for propionate oxidation, including a propionyl-CoA: oxaloacetate transcarboxylase, were demonstrated in S. wolinii. 相似文献
79.
Growth of Propionibacterium freudenreichii was studied with glycerol, lactate, and propionate as energy sources and a three-electrode poised-potential amperometric electrode system with hexacyanoferrate (III) as mediator. In batch culture experiments with glycerol and lactate as substrates, hexacyanoferrate (III) was completely reduced. Growth yields increased and the fermentation patterns were shifted towards higher acetate formation with increasing hexacyanoferrate (III) concentrations (0.25–8.0 mM). In experiments with regulated electrodes, glycerol, lactate, and propionate were oxidized to acetate and CO2, and the electrons were quantitatively transferred to the working electrode. Growth yields of 29.0, 13.4 and 14.2 g cell material per mol were calculated, respectively. The high cell yield obtained during propionate oxidation cannot be explained solely by substrate level phosphorylation indicating that additional energy was conserved via electron transport phosphorylation. Furthermore, this result indicated complete reversibility of the methyl-malonyl-CoA pathway in propionic acid bacteria. 相似文献
80.
Wolfgang Ludwig Michael Weizenegger Silvia Dorm Jan Andreesen Karl Heinz Schleifer 《FEMS microbiology letters》1990,71(1-2):139-143
A 1330 base-pair fragment of a 16S rRNA gene has been amplified, cloned and sequenced. Comparison to other 16S rRNA sequences of eubacteria showed that P. niger represents a deep branch within the subdivision "Gram-positive with Gram-negative cell walls". It is not related to peptostreptococci, representatives of this genus studied so far are more closely related to clostridia. 相似文献