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1.
2.
D-amino acid oxidase is a widely distributed peroxisomal enzyme whose principal natural substrates are still unknown. Thiazolidine carboxylates, their derivatives and relatives, and the intermediates in their metabolism are among the more plausible substrate candidates. Using a cytochemical procedure, we have explored the distribution of peroxide-generating enzymatic activity against two thiazolidine carboxylates. We find that these compounds are effective substrates for peroxisomal oxidation in a variety of tissues that contain peroxisomal D-amino acid oxidase. Reaction was seen in the "classical" peroxisomes of rat liver and kidney, the peroxisomes of the fat body of firefly and of Drosophila and the peroxisomes of frog retina. Interestingly, both with the thiazolidine compounds and with more traditional D-amino acid oxidase substrates, the fireflies' photocyte granules, which are peroxisomes, lack activity. 相似文献
3.
Genes of theHoxDcomplex related to theDrosophila Abd-Bgene are involved in the morphogenesis of vertebrate paired appendages.Hoxd-11,for instance, is necessary in combination with otherHoxgenes for the proper development of different parts of the tetrapod limbs. Sequence comparisons between the mouse, chicken, and zebrafishHoxd-11loci have revealed the conservation of several blocks of DNA sequence which may be of importance for the regulation ofHoxd-11expression. We have used transgenic mice to show that one of these conserved elements specifically drives expression in a proximal-posterior part of developing forelimbs. Production of mice transgenic for a full fishHoxd-11construct as well as for mouse–fishHoxd-11chimeric constructs shows that the fish counterpart of this sequence is able to elicit expression in mouse forelimbs as well, though in a slightly different domain. However, this fish element requires the presence of the mouse promoter and does not work in its own context. These results are discussed in light of both the control ofHoxdgene expression during limb development and the use of a comparative interspecies approach to understand the regulation of genes involved in vertebrate development. 相似文献
4.
Start-up of a thermophilic upflow anaerobic sludge bed (UASB) reactor with mesophilic granular sludge 总被引:1,自引:0,他引:1
Jules B. van Lier Katja C. F. Grolle Alfons J. M. Stams Everly Conway de Macario Gatze Lettinga 《Applied microbiology and biotechnology》1992,37(1):130-135
Summary Fast start-up of thermophilic upflow anaerobic sludge bed (UASB) reactors was achieved at process temperatures of 46, 55 and 64° C, using mesophilic granular sludge as inoculum and fatty acid mixtures as feed. The start-up was brought about by increasing the temperature of mesophilic UASB reactors in a single step, which initially led to a sharp drop in the methane production rate. Thereafter, stable thermophilic methanogenesis was achieved within a period of 1 or 2 weeks depending on the temperature of operation. Mesophilic granules functioned initially as effective carrier material for thermophilic organisms. However, long-term operation led to disintegration of the granules, resulting in wash-out of thermophilic biomass. The temperature optima for acetotrophic methanogenic activity of the sludges cultivated at 46, 55 and 64° C, were similar, but differed significantly from the temperature optimum of the mesophilic inoculum. All the sludges examined were dominated by Methanothrix-like rods. These could be distinguished by antigenic fingerprinting into two subpopulations, one predominant at 36° C and the other predominant at 46° C and above.
Offprint requests to: J. B. van Lier 相似文献
5.
Kenning M. Anderson Thomas M. Seed Diana E. Wilson Jules E. Harris 《In vitro cellular & developmental biology. Animal》1992,28(6):410-414
Summary Culturing human prostate PC-3 cells for 4, 24, or 72 h in the presence of 5,8,11,14-eicosatetraynoic acid (ETYA), an inhibitor
of arachidonic acid metabolism and cholesterol biosynthesis, markedly altered the morphology and reduced the number of mitochondria
in the treated cells. Using quantitative electron microscopic morphometry, we documented changes in the number, form, area,
matrix density, and integrity of the cristae and limiting membranes of mitochondria in cells cultured with ETYA. The inhibition
of cholesterol synthesis or the substitution of ETYA for polyunsaturated fatty acids in the inner membrane may participate
in the disruption of the mitochondria, which resembles the morphologic sequelae of oxidative stress. If sufficiently extensive,
these changes could contribute to the inhibition of cellular proliferation by ETYA. 相似文献
6.
Helga Ginalski-Winkelmann Thomas V. Waehneldt Steven R. Cohen Jean-Marie Matthieu 《Neurochemistry international》1982,4(1):67-71
Total particulate material from control and myelin deficient (mld) brains was subjected to density centrifugation on a continuous sucrose gradient. Particles from control brains distributed in a bell-shaped mode with a peak density near 0.64 M-sucrose. In mld material only a slight elevation of optical density was observed near 0.8 M-sucrose. The highest specific activities of 2′,3′-cyclic nucleotide 3′-phosphodiesterase were observed at densities of 0.63 and 0.71 M-sucrose for mld and control brains, respectively. The peak of myelin basic protein in control fractions was near 0.60 M-sucrose. In mld fractions no peak was observed. Proteolipid and Wolfgram proteins had a maximum near 0.65 and 0.73 M-sucrose in control and mld fractions, respectively. The absence of myelin basic proteins in all the fractions makes it unlikely that, in mld mice, myelin basic proteins are synthesized but not incorporated into myelin. 相似文献
7.
Elvira Costantino-Ceccarini Thomas V. Waehneldt Helga Ginalski Philippe Burgisser Jacqueline Reigner Jean-Marie Matthieu 《Neurochemical research》1982,7(1):1-12
The distribution of UDP-galactose: ceramide galactosyltransferase (CGalT) was studied in subcellular fractions of rat forebrain during development using zonal centrifugation on linear gradients. Specialized subfractions: SN 1, a microsomal fraction, SN 4, a myelin-related fraction, and purified myelin were also used for this study. For comparison, two microsomal lipid synthesizing enzymes, a myelin-specific enzyme, 2,3-cyclic nucleotide 3-phosphodiesterase and myelin proteins were measured in the same subfractions. UDP-glucose: ceramide glucosyltransferase and cerebroside sulfotransferase were confined to microsomes. CGalT was ferase and cerebroside sulfotransferase were confined to microsomes. CGalT was localized in microsomes, but also in myelin and myelin-related fractions. The developmental change in distribution of CGalT in adult animals toward myelin containing fractions could indicate that the replacement of galactosylceramide in compact myelin could be carried out in close proximity to compact myelin (mesaxon, paranodal loops) rather than in the distant oligodendrocyte perikaryon. 相似文献
8.
Infection of cat flea, Ctenocephalides felis, larvae by the entomophilic nematode Neoaplectana carpocapsae was accomplished in the laboratory. The Breton strain of N. carpocapsae provided higher larval mortality at lower dosages than did the DD-136 strain. Adult nematodes were evident in the insect hemocoel after 48 h; however, no infective third-stage larvae were produced. Larval flea infection increased with an increase in the moisture content of sand from 2% to 7% and of sandy clay from 7% to 12%. Larval flea infection was also obtained on turf containing dauer larvae. Nematode penetration of cocoons with invasion of prepupal and pupal fleas was apparent. 相似文献
9.
Summary Two stable epithelial-like cell lines, the pig kidney strain (LLC-PK1) and a Wilms' tumor line (TuWi), previously established in other laboratories, were found to exhibit a number of properties
characteristic of kidney proximal tubular epithelium. Electron micrographs of LLC-PK1 monolayers revealed cells forming rosettes reminiscent of tubules. Numerous elongated microvilli and an amorphous basal laminar
material surrounded the cell membranes. Cell junctions were located between cell membranes at regions adjacent to the patent
lumens. Wilms' cells in culture were similar in appearance to the pig kidney cells; they exhibited numerous microvilli, a
thin basal laminar coating on the membrane, and desmonsomes between cells. No rosette formation was evident. Neither cell
line was found to produce extracellular reticulin fibers when grown in the presence ofl-ascorbic acid for 1 week. Absence of stainable reticulin in cell monolayer culture after ascorbicacid treatment has been
noted only in cell lines of apparent epithelial origin. Histochemically, both lines reacted positively for activities of a
number of enzymes found in high amounts in normal kidney tubular epithelium. Pig kidney cells were highly positive for γ-glutamyl
transpeptidase activity and moderately active for acid phosphatase and leucine aminopeptidase activities. Wilms' tumor cells
were markedly active for γ-glutamyl transpeptidase, 5′-nucleotidase, ATPase, glucose-6-phosphatase, and acid phosphatase activities.
These findings in conjunction with the ultrastructural observations indicate that these two lines in culture maintain many
of the properties typical of proximal kidney tubular epithelium. 相似文献
10.
Céline Arzel Johan Elmberg Matthieu Guillemain Michel Lepley Fabrice Bosca Pierre Legagneux Jean-Baptiste Nogues 《Journal of Ornithology》2009,150(1):61-73
Two frequent assumptions about the evolution of long-distance migration in birds are that they travel long distances annually
to reach food-rich areas for breeding, and that they time their migratory journey to be at staging sites when the latter provide
the best feeding conditions. These assumptions have rarely been properly tested, and there is no study in which a species’
major food types have been measured by standardized methods throughout a flyway and over a large part of the year. We here
present such data for Eurasian teal (Anas crecca), converted to a common energetic currency, and collected at wintering, spring staging and breeding sites. Teal did not time
migration to maximize local food abundance; most birds left wintering and spring staging sites before a sharp increase in
invertebrate food abundance occurred. On the other hand, hatching of ducklings coincided with a peak in invertebrate food
abundance on boreal breeding lakes. Mean overall food abundance (invertebrates and seeds combined) did not differ between
wintering sites in southern France and breeding sites in northern Sweden at the time of breeding. Our results are inconsistent
with the hypothesis that long-distance migration in dabbling ducks has evolved because adult birds gain an immediate pay-off
in increased food abundance by flying north in spring. However, our data confirm a selective advantage for breeding at higher
latitudes, because hatching of ducklings may coincide with a peak in invertebrate emergence and because longer days may increase
the duration of efficient foraging. 相似文献