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61.
ABSTRACT. Thirty four taxa of heterotrophic protists (amoebae, flagellates and heliozoa) were encountered in cultures established from marine samples from Belize (Central America) and Tenerife (Canary Islands). Most species are flagellates drawn from the choanoflagellates, the cryptophyceans, the euglenids, the kinetoplastids, the bicosoecids, the chromulinids, the pedinellids and a variety of laxa of uncertain affinities (Protista incertae sedis). the identity of the thecate choanoflagellates Salpingoeca ringens Kent, 1880, and S. tuba Kent, 1880, is discussed, and four new species of heterotrophic protists are described: one new species of the amoeba genus Paulinella (Paulinella intermedia n. sp.) and three new species of the incertae sedis genus Luffisphaera Belcher & Swale, 1975 ( Luffisphaera bulbochaete n. sp.; L. longihastis n. sp.; L. turriformis n. sp.).  相似文献   
62.
Evolution and phylogenetic utility of the period gene in Lepidoptera   总被引:6,自引:0,他引:6  
Evolution and phylogenetic utility of the period gene are explored through sequence analysis of a relatively conserved 909-bp fragment in 26 lepidopteran species. Taxa range from tribes to superfamilies, primarily within the putative clade Macrolepidotera plus near outgroups, and include both strongly established and problematic groupings. Their divergence dates probably range from the late Cretaceous through much of the Tertiary. Comparisons within the same set of closely related species show that amino acid substitutions in period occur 4.9 and 44 times as frequently as they do in two other nuclear genes--dopa decarboxylase and elongation factor-1 alpha, respectively. In contrast, rates of observed synonymous substitution are within 60% of each other for these three genes. Synonymous changes in period approach saturation by the family level, whereas nonsynonymous and amino acid divergences across the Macrolepidoptera are less than half the maximal values reported for this gene. Phylogenetic analyses of period strongly supported groupings at the family level and below. In contrast to previous analyses at this level with other nuclear genes, much of the information lies in nonsynonymous change. Relationships up to the superfamily level were recovered with decreasing effectiveness, and little, if any, signal was apparent regarding relationships among superfamilies. This could reflect rapid radiation of the superfamilies, however, rather than saturation in the period locus; thus, period, in combination with other genes, remains a plausible candidate for approaching the difficult problems of lepidopteran family and superfamily relationships.   相似文献   
63.
64.
Disposition of (-)-norepinephrine and (-)-epinephrine in jejunum of WLH chicken was studied using oil-immersion technique. The relative rate of different routes of disposition of catecholamines was in the following order: for (-)-NE COMT greater than or equal to MAO greater than or equal to U2 greater than U1, for (-)-Epi U2 greater than or equal to COMT greater than MAO greater than U1. The role of enzymatic degradation is almost equal to that of uptake processes for (-)-Epi, but it was greater for (-)-NE.  相似文献   
65.
Zygotes of the brown alga Fucus distichus L. Powell accumulate a sulfated polysaccharide (fucoidin) in the cell wall at the site of rhizoid formation. Previous work indicated that zygotes grown in seawater minus sulfate do not sulfate the preformed fucan (an unsulfated fucoidin) but form rhizoids. Under these conditions, we determined whether sulfation of the fucan is required for its localization in the rhizoid wall. This was accomplished by developing a specific stain for both the fucan and fucoidin. Using a precipitin assay, we demonstrated in vitro that the lectin ricin (RCA(I)) specifically complexes with both the sulfated and desulfated polysaccharide. No precipitate is observed when either is incubated in 0.1 M D-galactose or when RCA(I) is mixed with laminarin or alginic acid, the other major polysaccharides in Fucus. RCA(I) conjugated with fluorescein isothiocyanate (FITC) is also shown to bind specifically to fucoidin using a filter paper (DE81) assay. When added to zygotes, RCA(I)-FITC binds only to the site of fucoidin localization, i.e., the rhizoid cell wall. However, RCA(I)-FITC is not observed in the rhizoid wall of zygotes grown in the absence of sulfate. This observation is not due to inability of RCA(I)-FITC to bind to the fucan in vivo. Chemically desulfated cell walls that contained fucoidin in the rhizoid wall bind RCA(I)-FITC only in the rhizoid region. Also, the concentration of fucose-containing polymers and polysaccharides that form precipitates with RCA(I) is the same in embryos grown in the presence or absence of sulfate. If sulfate is added back to cultures of zygotes grown without sulfate, fucoidin is detected at the rhizoid tip by RCA(I)-FITC several hours later. These results support the conclusion that the enzymatic sulfation of the fucan is a modification of the polysaccharide required for its localization and/or assembly into a specific region of the cell wall.  相似文献   
66.
Thiouracil and a few related drugs are known to be melanoma-seeking agents owing to specific incorporation into nascent melanin. The melanin-affinic properties are apparently due to binding to intermediates, preferably dopaquinone, produced in the melanin synthetic pathway by tyrosinase-catalysed oxidation of tyrosine. In the present paper, in vitro screening methods have been used for the identification of possible melanoma seekers according to the above principle. The binding of test substance to dopaquinone suppresses dopachrome formation by the withdrawal of dopaquinone from the reaction mixture, and the decrease in dopachrome concentration was monitored spectrophotometrically at 475 nm. In order to eliminate false results caused by tyrosinase inhibition, which also will decrease the dopachrome concentration, the oxygen consumption was followed potentiometrically. To avoid the effect of tyrosinase inhibition on dopachrome formation, additional experiments with autoxidation of L-dopa in the presence of test substance were performed. Of the 22 substances (mainly thioureylenes and thioamides) studied, 4,5,6-triamino-2(H)-pyrimidinehtionsulfate, trithiocyanuric acid, 2-thiouracil, 6-methyl-2-thiouracil, and 4-amino-2-mercaptopyrimidine most effectively decreased the dopachrome formation with no or little inhibition of tyrosinase activity. They should therefore be regarded as potential melanoma seekers. In a complementary autoradiographic study on the uptake of the potent tyrosinase inhibitor mercaptobenzothiazole (MBT) in B 16 melanoma, transplanted to mice, it was found that strong tyrosinase inhibition seems to decrease incorporation into melanin in vivo. MBT was partly accumulated in restricted areas of the tumor, which may be explained by the small molar dose injected.  相似文献   
67.
The botryoid odontogenic cyst (BOC) is a rare, locally more aggressive variant of the usually indolent lateral periodontal cyst (LPC) and gingival cyst (GC). A recent case of BOC provided an opportunity for an exploratory study on the causes of its more aggressive behavior. The limited objective was to see if the BOC was sufficiently different from the other cysts to warrant an investment in a large study. Sections of neutral buffered formalin fixed, paraffin-embedded tissues from the BOC and archival specimens of four GCs, four LPCs and three odontogenic keratocysts (OKCs) were stained using immunohistochemistry for Ki-67, a marker of proliferating cells, caspase-3, a marker of cells undergoing apoptosis, tumor suppressor p53, and the apoptosis inhibitor BCL2. The mean labeling index (LI) of immunoreactive cyst epithelial cells was computed for each antibody and type of cyst. Compared to the LPCs and GCs, the BOC exhibited a moderately larger Ki-67/caspase-3 LI difference, which indicates that the BOC had a net higher rate of growth. We found a much higher level of LI, therefore likely dysregulation of p53. We also found a much higher LI of BCL2. The LIs of p53 and BCL2 in the BOC were similar to and more than twice that of the OKCs, respectively. Although meaningful statistical analysis was precluded by our use of only one case of BOC and a small number of the other cysts, the high p53 and very high BCL2 labeling indices of the BOC offer a potential explanation for its reportedly more aggressive behavior that clearly is worthy of further investigation.  相似文献   
68.
U Handa  A Palta  H Mohan  R P Punia 《Acta cytologica》2001,45(6):1073-1076
BACKGROUND: Glomus tumor is a relatively uncommon soft tissue tumor that can occur at any age and anatomic site, with a predilection for the subungual region. CASE: A 24-year-old female presented with a gradually enlarging, painful swelling in the subungual region of the right index finger. Fine needle aspiration was performed under a ring block and yielded hemorrhagic material. The smears revealed clusters of uniform, round to oval cells admixed with wisps of magenta intercellular myxoid material and a few spindle-shaped cells crossing clusters of tumor cells. A diagnosis of benign vascular tumor consistent with glomus tumor was given. Subsequent histopathologic examination confirmed the diagnosis and showed alpha-SMA positivity on immunohistochemistry. CONCLUSION: This case report is the second on the cytologic features of glomus tumor in the English-language literature. Although the cytomorphologic features of glomus tumor are quite distinctive, an appropriate clinical history and immunohistochemical stains (e.g., alpha-SMA and vimentin positivity) can further help to ascertain the diagnosis.  相似文献   
69.
Arsenic (As) and Fluoride (F) are present in many soils, affecting crops and posing risks in the food chain. We performed pot experiments on spiked soils enriched in these elements either individually or simultaneously, over a wide range of concentrations. Soybean biomass production, grain yield, As and F accumulation and distribution within the plant, and the antioxidant response to these stresses were analyzed. Arsenic was more toxic than F. At As levels >35 mg/kg and F levels >375 mg/kg, yield loss reached 60% and 30%, respectively. At the highest dose of As plants died within 2 weeks, whereas F showed no lethality. When they were applied simultaneously, detrimental effects were more important. As and F in plants increased in all soybean organs although grains presented the lowest concentrations. Antioxidant enzymes were enhanced in plants but this increase was not high enough to cope with the oxidative damage.  相似文献   
70.
Taxol from fungal endophytes and the issue of biodiversity   总被引:7,自引:0,他引:7  
Fungi represent one of the most understudied and diverse group of organisms. Commonly, these organisms make associations with higher life forms and may proceed to biochemically mimic the host organism. An excellent example of this is the anticancer drug, taxol, which had been previously supposed to occur only in the plant genusTaxus (yew). However, taxol has been reported in a novel endophytic fungus—Taxomyces andreanae, but also has been demonstrated to occur in a number of unrelated fungal endophytes includingPestalotia, Pestalotiopsis, Fusarium, Alternaria, Pithomyces, Monochaetia and others. Thus, this report presents information on the presence of taxol among disparate fungal genera, and uses these observations as an additional argument to support efforts to study fungal endophytes and preserve their associated host plants.  相似文献   
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