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61.
Differential Postnatal Development of Monoamine Oxidases A and B in the Blood-Brain Barrier of the Rat 总被引:2,自引:2,他引:0
Abstract: We studied the monoamine metabolizing mitochondrial enzyme, monoamine oxidase (MAO), in cerebral microvessels obtained from postnatally developing rats by measuring the specific binding of [3 H]pargyline, an irreversible inhibitor of MAO, and the rate of oxidation of three known MAO substrates: benzylamine, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, and tryptamine. MAO activity increased postnatally, with the greatest increase occurring in the second week and reaching a peak at 3 weeks of age. A concomitant increase in MAO of the cerebral cortex also occurred, but was several-fold less than that of cerebral microvessels. Using clorgyline and deprenyl, relatively specific inhibitors of MAO-A and MAO-B, we showed that cerebral microvessels contain both forms of MAO at all ages, but there was a major preponderance in the postnatal development of MAO-B. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses of rat microvessels after [3 H]pargyline binding also showed two distinct bands of radioactivity at all ages. These two bands corresponded to molecular weights of ∼6.5,000 for MAO-A and -60,000 for MAO-B. SDS-PAGE resuits of brain microvessels obtained from 1-, 14-, and 42-day-old rats confirm the differential postnatal development of MAO-B in rat brain microvessels. 相似文献
62.
Regional environments, life-history patterns, and habitat use of spirostreptid millipedes in arid regions 总被引:1,自引:0,他引:1
C. S. CRAWFORD K. BERCOVITZ M. R. WARBURG 《Zoological Journal of the Linnean Society》1987,89(1):63-88
Among diplopods with desert populations, only three species of Spirostreptida have been studied in an ecological context. The present review compares regional environments, life-history patterns, and uses of habitat by Orlhoporus ornatus (Girard) from southwestern North America, Archispirostreptus tumuliporus judaicus (Attems) from the eastern Mediterranean seaboard, and Harpagophora nigra (Attems) from southwestern Africa. Published and unpublished studies are used to explore evidence for convergence among these species, as opposed to traits adapting them to physical aspects of given regions or habitats. Unlike A. t. judaicus, O. ornatus and H. nigra are relatively restricted to arid habitats, although populations of all three species experience a variety of rainfall regimes and regional topographies. Where studied, O. ornatus and H. nigra hibernate during the long, often cool or cold dry season; they forage following warm-season rains. A. t. judaicus , in contrast, forages during its long, warm dry season and hibernates in the cool, wet winter. Populations from the Judaean and Negev deserts differ from those inhabiting a mesic habitat (Megiddo) closer to the coast in regard to rates of development, seasonal activity and seasonal water balance. Convergence in the form of well-developed desiccation resistance characterizes the two strictly desert species. All three species, together with other subtropical millipedes exposed to long dry seasons, are convergent with respect to patterns of diel surface activity and use of shelter. However species- and habitat-specific life-history features such as the seasonal timing of dormancy and emergence tend to mask convergence at the habitat level. Hence, the independent evolution of the three species with desert populations has resulted in life histories and habitat use that combine a moderate amount of convergence with considerable opportunistic adaptation to regional and local conditions. 相似文献
63.
Baulcombe DC Huttly AK Martienssen RA Barker RF Jarvis MG 《Molecular & general genetics : MGG》1987,209(1):33-40
Summary A genomic clone of a wheat -amylase gene (Amy3/33) was identified, on the basis of hybridisation properties, as different from -Amy1 and -Amy2 genes which had been characterised previously. The nucleotide sequence revealed that this gene has the normal sequence motifs of an active gene and an open reading frame interrupted by two introns. The protein sequence encoded by this open reading frame is recognisably similar to that of -amylase from the -Amy1 and -Amy2 genes and there is high sequence homology in all three proteins at the putative active sites and Ca++ binding region. In addition, the introns are at positions equivalent to the position of introns in the -Amy1 and -Amy2 genes. However, the sequence was less similar to -Amy1 and -Amy2 than these are to each other. Southern blot analysis showed that the Amy3/33 DNA is one of a small multigene family carried on a different chromosome (group 5) from either the -Amy1 or -Amy2 genes. A further difference from the -Amy1 and -Amy2 genes was the pattern of expression. Amy3/33 was expressed only in immature grains and, unlike the -Amy1 and -Amy2 genes, not at all in germinating aleurones. These data suggested therefore that this gene represents a third type of -amylase gene, not described before, which shares a common evolutionary ancestor with the -Amy1 and -Amy2 genes. 相似文献
64.
Indole-3-acetic acid (IAA) and indole-3-ethanol (IEt) were identified in immature seeds of Pinus sylvestris L. by combined gas chromatography-mass spectrometry. Indole-3-methanol was tentatively identified using multiple ion monitoring. Anatomical investigations of seeds, as well as measurements of free and alkali-hydrolysable IAA and IEt, were made during seed development and germination. Levels of free IAA and IEt decreased during seed development. In the later stages of seed maturation most IAA and IEt were present in alkali-hydrolysable forms. Bound IAA and bound IEt rapidly decreased during germination, while levels of free IAA and IEt increased dramatically for a short period. 相似文献
65.
Indole-3-ethanol (IEt) was extracted from Phycomyces blakesleeanus Bgff. and purified by TLC and HPLC. Identification was performed by mass spectrum. The HPLC-purified compound showed an UV-spectrum typical for indoles, with absorption maxima at 220 and 281 nm. The IEt content varied between 1.5 nmol (g fresh weight)−1 and 5.6 nmol (g fresh weight)−1 . The observed variations were strongly correlated with certain developmental stages of the fungus. Furthermore, the decrease of IEt between 60 and 84 h of fungal development coincides with a high IEt oxidase activity. The product of the enzyme reaction was indole-3-acetaldehyde, which was identified by co-chromatography with an authentic standard in several TLC and HPLC systems and by chemical conversion to indole-3-acetaldoxime. 相似文献
66.
67.
Summary During imbibition of whole tea seeds (6 days) two purine alkaloids, caffeine and theobromine, did not decrease in the seed
coats and there was no increase in the seeds. In parallel with and after the breaking of seed coats there was a gradual release
of caffeine from coats of germinating seeds. By contrast, when the seed was freed from the outer seed coat and soaked, imbibition
of the seed required only 2 days and simultaneously caffeine was released from the inner seed coat. In such seeds, but not
in whole seeds, growth of embryonic tissues (roots and shoots) was inhibited after the breaking of the inner seed coats. Nevertheless,
caffeine increased more in such roots of the seedlings of decoated seeds than in roots of normal seedlings. 相似文献
68.
Elizabeth A. Bray Satoshi Naito Nai-Sui Pan Edwin Anderson Philip Dubé Roger N. Beachy 《Planta》1987,172(3):364-370
Soybean (Glycine max (L.) Merr.) seeds contain the storage protein -conglycinin, encoded by a multigene family. -Conglycinin consists of three subunits; , , and . A genomic clone for a -subunit of -conglycinin has been characterized by restriction-enzyme mapping and hybrid selected in-vitro translation followed by immunoprecipitation. In order to determine the developmental regulation of this -subunit gene, its expression was studied in seeds of transgenic petunia (Petunia hybrida) and tobacco (Nicotiana tabacum L.) plants. The -subunit expressed in seeds of petunia and tobacco was recognized by anti--conglycinin serum at a relative molecular mass of 53 000, equivalent to that of the native protein. Separation of the petunia-seed proteins by isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis showed that multiple isoelectric forms of the -subunit were produced. There was approximately a twofold variation in the accumulation of the -subunit protein in the mature seeds of transgenic petunia plants, each containing a single -subunit gene. However, the level of protein accumulation in mature seeds and the amount of -subunit mRNA in developing seeds was not correlated. Accumulation of the -subunit protein in transgenic seeds was less than the -subunit protein that accumulated in transgenic petunia seeds containing a single -subunit gene and less than the amount of the -subunit in mature soybean seeds which contain 8–13 -subunit genes. In transgenic tobacco plants, the accumulation of the -subunit protein in seeds was generally well correlated with the number of genes that were incorporated in the different transformants.Abbreviations kb
kilobase
- kDa
kilodalton
- Mr
relative molecular mass
- SDS-PAGE
sodium dodecyl sulfate polyacrylamide gel electrophoresis 相似文献
69.
The analysis of planktonic rotifer populations: A plea for long-term investigations 总被引:20,自引:10,他引:10
Alois Herzig 《Hydrobiologia》1987,147(1):163-180
Short-term species succession, and long-term community development, of planktonic rotifer populations of the temperate zone and factors influencing species' abundance (ie., physical and chemical limitations, food and exploitative competition, mechanical interference competition, predation, parasitism) are described and discussed. The long-term development of plankton communities in three European lakes is described and the major events are discussed in relation to ecological interactions. Frequently, the shortcomings of our knowledge about population ecology and ecophysiology of rotifers prevent explanations of short-term and, especially, of long-term developments of these plankton organisms. The need for qualitative and quantitative observations in the field and in the laboratory over long periods becomes obvious. 相似文献
70.
Norbert Rieder 《Hydrobiologia》1987,145(1):175-181
A group of nine sensory setae is found on the tip of the antennula ofDaphnia magna in both sexes. Inside a seta four dendrites are situated, each with one receptor cilium. The receptor cilia extend through
a liquor space into the exterior part of the seta.
The exterior part of the liquor space is divided from the interior part by a knob-like thickening of the innermost layer of
the epicuticle, the basal bead. The basal bead narrows the liquor space and the receptor cilia. The interior part of the liquor
space is surrounded by five sheath cells, the exterior part by a thin cuticle. In the exterior part the receptor cilia branch
partly and reach a terminal pellet on the tip of the seta. The terminal pellet is a thickened part of the epicuticle. It is
permeable to several dissolved substances.
It is the exterior part of the receptor that projects over the tip of the antennula and seems to be the entire seta. During
the premoult the fifth sheath cell builds up the articulation of the seta, the fourth the basal bead, and the third the shaft
of the seta. The first sheath cell forms the cuticular sheath.
The organ seems to be a chemoreceptor, but the adequate stimulus is as yet unknown. 相似文献