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41.
42.
1. Coproporphyrinogenase has been prepared from rat-liver mitochondria and its properties have been studied. The isoelectric point was found to be around pH5.0 and the molecular weight to be 80000+/-8000. The pH optimum of the enzymic reaction was 7.4 and the apparent K(m) was of the order 0.03mm. The enzyme was destroyed by boiling and irreversible inactivation occurred below pH3.5. It could be stored at -10 degrees without loss of activity. The enzyme acts specifically on coproporphyrinogen III and does not form protoporphyrinogen from trans-2,4-diacrylicdeuteroporphyrin or its porphyrinogen. It was unaffected by prolonged dialysis and no cofactor requirement could be demonstrated. 2. Column chromatography of a partially purified enzyme preparation on Sephadex G-200 was found to be an improved method of purification, which gave a coproporphyrinogenase 58-fold purified. The purified enzyme was studied electrophoretically but no evidence was obtained to suggest that more than one enzyme was involved in the reaction. 3. The action was studied of various compounds added to the system. The presence of monothiol groups in the enzyme system was indicated, whereas vicinal dithiol groups were not involved in the reaction. Metal-chelating agents did not inhibit the reaction and no requirement for the presence of any essential metal has been found. All attempts to demonstrate the presence of a prosthetic group, in particular flavines, failed. Neither pyridoxal phosphate nor ATP was involved in the reaction, nor was a mitochondrial electron-transport chain required for the activity of the enzyme. Some circumstantial evidence was obtained to suggest that cis-2,4-diacrylicdeuteroporphyrin is an intermediate in the reaction. 相似文献
43.
Intra- and interspecific competition between laboratory populations of four green leafhoppers, Nephotettix spp. was studied in the laboratory under three different temperature regimes of 24°C, 27°C and 30°C. For the single-species population of the three tropical species, the equilibrium density increased as the temperature increased. On the other hand, for the temperature species N. cincticeps, the highest equilibrium density was at the intermediate temperature and the lowest at high temperature. Interspecific interactions between two tropical (N. virescens vs. N. nigropictus), a tropical and a temperature (N. virescens vs. N. cincticeps) and a rice-feeding and a grass-inhabiting (N. virescens vs. N. malayanus) Nephotettix species were also studied in the laboratory at the three temperature regimes. Temperature differentially affected the outcome of competition between two Nephotettix species. Between N. virescens and N. nigropictus, the latter was more successful over the former at low and intermediate temperatures, while the former was more successful at high temperature. Between N. virescens and N. cincticeps, the temperate species inhibited the growth of the tropical species at low temperature while the tropical species inhibited the growth of the temperate species at high temperature. At intermediate temperature, the population of N. virescens persisted at a slightly higher density over the population of N. cincticeps. Between the rice-feeding N. virescens and the grass-inhabiting N. malayanus, regardless of temperature the population density of the latter was greatly reduced and later became extinct while the population of the former continued its growth. These consequences of competition between two Nephotettix species conformed fairly well to those predicted by theLotka-Volterra model using demographic parameters specified for each species. 相似文献
44.
M Morales J del Castillo D S Smith 《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1989,94(2):547-554
1. The changes in the consistence of the spine-test articular capsule, or ligament, of the primary spines of Eucidaris tribuloides induced by acetylcholine (ACh) have been studied. Two complementary techniques were used: (a) "forced-vibration", which detects variations in the stiffness of the ligament along a single diametral plane; and (b) "forced-rotation" which records the spatial distribution of those changes. 2. ACh (1 microM to 1 mM) caused a rapid increase in the resistive force opposed by the ligament to passive stretching. Similar effects were elicited by several monoquaternary, N-substituted derivatives of trimethylammonium. 3. The opposite effect, i.e. softening, was induced by decamethonium, dimethylphenylpiperazine, and 2-ketoamyltrimethylammonium. 4. The involvement in these effects of ACh-binding groups with pharmacological properties similar to those of the "anionic sites" of nicotinic ACh receptors is suggested. 相似文献
45.
Prof. Dr. Renate Koenig Maria Rüdel Dr. D.-E. Lesemann 《Journal of Phytopathology》1989,127(2):169-172
A number of virus isolates were obtained from ditches and drainage canals in the Palatinate grapevine-growing area (‘Rheinpfalz’) in West Germany. By means of the immunoelectron microscopical decoration and the agar gel double diffusion tests these isolates were identified as petunia asteroid mosaic virus, carnation ringspot virus and tobacco necrosis virus strain D, respectively. 相似文献
46.
47.
J. L. Molina-Cano L. F. García del Moral J. M. Ramos M. B. García del Moral P. Jiménez-Tejada I. Romagosa F. Roca de Togores 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,80(6):762-768
Summary Three mutants induced in the two-rowed barley variety Beka and their three binary recombinants have been used in an attempt to define an ideotype suitable for Mediterranean agroclimatic conditions. Physiological methods (classical plant growth analysis) together with the study of genotype x environment interaction for grain yield were used to characterize the genotypes. That characterization brought out the huge phenotypical variation produced by only three mutant genes, suggesting that single Mendelian genes may alone explain the quantitative variation, including grain yield, without the necessity of using the polygenic concept. The genotype best adapted to the environments studied is later in heading and has shorter straw and denser spikes than Beka; it also has higher inverse of leaf area rate and grain: leaf area ratio, a lower rate of leaf senescence, and a shorter grain filling period than the original variety. 相似文献
48.
N. del Hoyo J. A. Pulido M. T. Carretero M. A. Pérez-Albarsanz 《Bioscience reports》1990,10(1):105-112
Rat ventral prostate incorporated (1-14C)acetate, (1-14C)palmitate and (1-14C)linoleate into different phospholipids in a time-dependent process. The rate of incorporation into total phospholipids was higher with linoleate (10.0 nmol/g) than with either palmitate (5.8 nmol/g) or acetate (4.7 nmol/g). Predominant labelling with all the radioactive substrates assayed was found in choline glycerophospholipids (PC). The radioactive profiles for linoleate in the other ventral prostate phospholipids differed from those obtained with palmitate and acetate. Specifically linoleate was incorporated into inositol glycerophospholipids plus lysoethanolamine glycerophospholipids (PI+LPE) and not into sphingomyelin (SM), while palmitate and acetate incorporated into SM but not into PI+LPE. Acetate showed the highest oxidation to CO2 whereas no differences were observed in the radioactivity incorporated into CO2 from a saturated (palmitate) or an essential unsaturated fatty acid (linoleate). These studies also show zinc-dependence by the acetate to CO2 oxidation.Abbreviations PL
total phospholipids
- PC
choline glycerophospholipids
- PE
ethanolamine glycerophospholipids
- PI+LPE
inositol glycerophospholipids plus lysoethanolamine glycerophospholipids
- PS
serine glycerophospholipids
- SM
sphingomyelin 相似文献
49.
J A Vega C Rodríguez M Medina M E del Valle 《Cellular and molecular biology, including cyto-enzymology》1990,36(5):537-546
The presence of neuron-specific enolase (NSF) and neurofilament proteins (NFP) immunoreactivities (IR) was investigated in dorsal root ganglia (DRG) of adult rats at cervical, thoracic, lumbar and sacral levels. All neurons display NSE-like IR with a variable intensity of immunostain which is not related to the neuronal size. Conversely, the antibody against all three proteic subunits of NFP no labelled the primary sensory neurons, whereas the intraganglionic axons and dorsal root of spinal nerves result positives. In the sciatic nerve the immunoreactivity was similar for NSE- and NFP-like IR. No regional differences were found among the different levels of DRG for NSE-like IR. The present results demonstrate heterogeneity in the neurons of the rat. DRG for NSE-like IR, and differences between sensory neurons and fibers in the distribution of NFP-like IR. 相似文献
50.
Sandra Afione Luciano Debeljuk Adriana Seilicovich Daniel Pisera Mercedes Lasaga María del Carmen Díaz Beatriz Duvilanski 《Peptides》1990,11(6):1065-1068
In the present work we examined the effect of the neutralization of endogenous substance P by the administration of an anti-substance P serum (ASPS) on GABA concentration in the anterior pituitary in hyperprolactinemic conditions induced by 5-hydroxytryptophan or by grafting anterior pituitaries. ASPS reduced the increase in the anterior pituitary GABA concentration induced by hyperprolactinemia. In vitro experiments showed that substance P inhibited K+-evoked GABA efflux from hypothalamic fragments and decreased GABA concentration in the anterior pituitary but ASPS increased it. Our results demonstrate that substance P modifies hypothalamic GABA release and anterior pituitary GABA concentration and suggest that an interaction exists between substance P and GABA. 相似文献