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1.
A low-pressure microwave-induced helium plasma serves as an excitation source for metal chlorides, nitrates, and sulfates vaporized from a filament, resulting in fractional vaporization and differential sensitivities of detection of the elements depending on the vapor pressures of their salts. The shapes of the single emission peaks, which are simple in the presence of potassium chloride, become complex and may double in number. 相似文献
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In temperate waters of southern Japan, mouthbrooding males of the cardinal fish Apogon doederleini sometimes ate their entire brood within a day of spawning. In spite of annual variation in age structure and length of the breeding season, however, the annual cannibalism rate (broods cannibalized to total broods spawned) was nearly constant, 12–16%. Fish 1 year old frequently cannibalized early broods of the season, especially the first brood, whereas the cannibalism rate by 2 year-old fish did not vary within the season. In contrast, the cannibalism by older males increased late in the season. This tendency was attributed to their different allocation patterns to growth and reproduction. For 1 year-old fish, which can enhance future reproductive success by growth and cannibalizing on early broods instead of mouthbrooding (at relatively low temperatures), this may be a tactic for investing energy in growth. For fish 3 years, which have more breeding cycles and grow little, cannibalizing late broods may be energetic compensation for their poor somatic condition. No seasonal variation of cannibalism by 2 year-old fish can be explained by their intermediate nature of growth and reproduction. Multiple mate availability is one factor facilitating the cannibalism by 2 and 3 + year-old fish whose operational sex ratio is female-biased. 相似文献
5.
In order to estimate the exposure levels of mutagenic and carcinogenic heterocyclic amines in humans, we developed a high-performance liquid chromatography method to detect 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) in dialysis fluid of patients with uremia. Using this methods, dialysis fluid of 12 patients who had received hemodialysis treatment or continuous ambulatory peritoneal dialysis was examined. Trp-P-1 was detected in dialysate of all uremic patients (727 +/- 282 pmoles, n = 12). In patients who had been treated with continuous ambulatory peritoneal dialysis, the average amount of Trp-P-1 found in whole dialysate (6 l) per day was 710 +/- 203 pmoles (mean +/- S.D., n = 8). Moreover, Trp-P-2 could be detected in 5 out of 12 patients (206 +/- 85 pmoles, n = 5). These results indicate that patients with uremia are actually exposed to carcinogenic tryptophan pyrolysis products. The average exposure level of Trp-P-1 in uremic patients apparently exceeded 710 pmoles (150 ng) per day. 相似文献
6.
C J Mirell M Yanagisawa R Lau A E Pekary W W Chin J M Hershman 《Molecular endocrinology (Baltimore, Md.)》1987,1(6):408-412
Thyroidectomized rats were used to study the effects of a single injection of T3 on pituitary mRNA synthesis and hormone secretion. T3 was injected ip at doses of 0, 0.2, 1, or 5 micrograms/100 g body weight, and and animals were killed 24 h later. T3 caused a significant decrease in serum TSH, but caused no significant change in either serum GH or PRL. Pituitary mRNA was quantified by slot blot hybridization with cDNA probes specific for alpha-TSH, beta-TSH, PRL, and GH. We found that both the alpha and beta mRNA subunits decreased, that PRL mRNA remained relatively unchanged, and that GH mRNA increased with increasing T3 dose. The data show that a single dose of T3 can profoundly influence mRNA levels in the anterior pituitary; the lowest dose of T3 caused maximum inhibition of alpha-TSH mRNA while beta-TSH mRNA declined further in a dose-dependent manner. 相似文献
7.
Purification and properties of GM2 synthase, UDP-N-acetylgalactosamine: GM3 beta-N-acetylgalactosaminyltransferase from rat liver 总被引:2,自引:0,他引:2
A UDP-N-acetylgalactosamine:ganglioside GM3 beta-N-acetylgalactosaminyltransferase which catalyzes the conversion of ganglioside GM3 to GM2 has been purified over 6300-fold from a Triton X-100 extract of rat liver particulate fractions by hydrophobic chromatography and affinity chromatography on GM3-acid-Sepharose. The purified enzyme has two identical subunits of 64,000 daltons. The enzyme has a pH optimum of pH 6.7-6.9 and requires divalent cations such as Mn2+ and Ni2+. In studies on substrate specificity GM3 containing N-acetylneuraminic acid (GM3(NeuAc] and GM3 containing N-glycolylneuraminic acid were both good acceptors for the purified enzyme. The plots of the activity of transferase as a function of GM3(NeuAc) showed sigmoidal relationships. The oligosaccharide of GM3, sialyllactose, was also a good acceptor, which indicates that the preferred acceptor substrate has the possible structure NeuAc alpha 2- or NeuGc alpha 2-3 Gal beta 1-4Glc-OR. 相似文献
8.
Identification of the cell surface molecule involved in sexual cell fusion of Dictyostelium discoideum 总被引:6,自引:0,他引:6
Kazuyoshi Suzuki Kaichiro Yanagisawa 《Differentiation; research in biological diversity》1989,40(3):159-165
Dictyostelium discoideum was used as a model system for elucidating the molecular mechanism of sexual cell fusion. In heterothallic strains NC4 and HM1 of D. discoideum, complements in mating type, amoeboid cells acquire fusion competence only under certain environmental conditions, such as the presence of excess water and a certain period of darkness, to fuse sexually. The surface of cells which acquired fusion competence was found to possess specific antigens. Monovalent antibodies prepared from rabbit antiserum against fusion-competent NC4 cells inhibit the sexual cell fusion of these cells completely. Two specific antigenic proteins, 39 and 138 k Da in relative molecular mass and specific for fusion-competent cells, were detected. Only one, the 138-k Da protein, was capable of neutralizing the fusion-inhibitory activity of the monovalent antibody. These results show that the 139-k Da protein is the one involved in the sexual cell fusion of NC4 and HM1 strains in D. discoideum. 相似文献
9.
Endothelin-3 is a novel neuropeptide: isolation and sequence determination of endothelin-1 and endothelin-3 in porcine brain 总被引:4,自引:0,他引:4
O Shinmi S Kimura T Sawamura Y Sugita T Yoshizawa Y Uchiyama M Yanagisawa K Goto T Masaki I Kanazawa 《Biochemical and biophysical research communications》1989,164(1):587-593
The molecular forms of endothelin (ET) related peptides were investigated in porcine brain by using high performance liquid chromatography coupled with three specific radioimmunoassays. ET-1 and its oxidized form were isolated and sequenced as in the case of porcine spinal cord. A very small amount of big ET-1 (1-39) and its C-terminal fragment (big ET-1 (22-39] were also detected. Furthermore, immunoreactive (ir)-ET-3 was isolated and sequenced; its partial primary structure was identical to that of human (rat) ET-3. The concentrations of ir-ET-1 and ir-ET-3 in porcine brain were 140 fmol/g tissue and 5 fmol/g tissue, respectively. These results indicate that besides ET-1, ET-3 is a novel neuropeptide in the central nervous system. 相似文献
10.
Presence of endothelin-1 in porcine spinal cord: isolation and sequence determination 总被引:2,自引:0,他引:2
O Shinmi S Kimura T Yoshizawa T Sawamura Y Uchiyama Y Sugita I Kanazawa M Yanagisawa K Goto T Masaki 《Biochemical and biophysical research communications》1989,162(1):340-346
We investigated the molecular forms of endothelin (ET) related peptides in porcine spinal cord by high performance liquid chromatography coupled with radioimmunoassays using three antisera raised against ET-1 and C-terminal fragments of ET-1 and big ET-1. ET-1 and its oxidized form were isolated as major immunoreactive peptides and sequenced. Furthermore, immunoreactivities like ET-3 and big ET-1(22-39) (contents: less than 8% and less than 1% of ET-1, respectively) were detected based on their chromatographic retention times and characteristics of immunoreactivity to the antisera. Big ET-1 was only scarcely detected. Immunohistochemical study showed the presence of ET-1-like immunoreactivity in motoneurons, dorsal horn neurons and dot- and fiber-like structures in the dorsal horn of lumbar spinal cord. These results indicate that ET-1 is present not only in endothelial cells but also in spinal cord, and that big ET-1 is converted into ET-1 in spinal cord by specific processing between Trp21-Val22. The data also indicate that ET-1 may act as a neuropeptide in the central nervous system. 相似文献