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1.
PM Visscher 《遗传、选种与进化》1995,27(4):335-345
2.
Jennifer J Beard David Evans Walter Peter G Allsopp 《Australian Journal of Entomology》2003,42(1):51-78
Abstract In many areas of the world, spider mites are significant pests of sugarcane. Australia is currently fortunate in lacking the most destructive species, and usually suffers only sporadic damage. Herein, we provide a key to the genera of spider mites associated with sugarcane, review the most significant genus, Oligonychus Berlese, and provide a key to the species of grass-feeding Oligonychus in the Australasian region. The species O. araneum Davis, O. digitatus Davis, O. grypus Baker and Pritchard, O. orthius Rimando, and O. oryzae (Hirst) are redescribed, while the Australian O. zanclopes sp. n. Beard and Walter from sugarcane and rice, O. turbelli sp. n. Beard and Walter, O. ephamnus sp. n. Beard and Walter and O. festucolus sp. n. Beard and Walter from other grasses, are newly described. Previous records of O. grypus in Australia appear to be misidentifications of what is described here as the new species O. zanclopes . 相似文献
3.
Characterization of the cell type-specific determinant in the genome of minute virus of mice. 总被引:19,自引:17,他引:2
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Two strains of minute virus of mice (MVM) show different host cell specificities. The prototype strain MVM(p) grows in fibroblasts, whereas the immunosuppressive variant MVM(i) grows in T lymphocytes. In this study, we have mapped on the viral genome a cell type-specific determinant: it is located between 69 and 85 map units in a region coding for the viral capsid proteins. The DNA of MVM(p) does not replicate in lymphocytes. MVM(i) cannot help MVM(p) grow in lymphocytes; thus the determinant acts in a cis fashion. We did not detect viral mRNA during a restrictive infection of lymphocytes with MVM(p). However, when the same cells were transfected with cloned DNA, both MVM(p) and MVM(i) DNAs were transcribed with the same efficiency from both promoters and the RNA was processed normally. Therefore, the specificity determinant is not a cell type-specific enhancer. 相似文献
4.
Demonstration of the ascorbate dependence of membrane-bound dopamine beta-monooxygenase in adrenal chromaffin granule ghosts 总被引:1,自引:0,他引:1
H H Herman K Wimalasena L C Fowler C A Beard S W May 《The Journal of biological chemistry》1988,263(2):666-672
Chromaffin granule ghosts from bovine adrenal medullae have been used to examine the ability of membrane-bound dopamine beta-monooxygenase to interact directly with intravesicular ascorbate and to investigate vectorial electron transfer from external ascorbate across the ghost membrane. Ghosts prepared by a modification of published procedures were shown to be fully active in both dopamine uptake and norepinephrine production. Dopamine uptake is dependent on the presence of a magnesium and ATP ionic complex, is abolished by reserpine, and reaches a steady-state level in the presence of dopamine beta-monooxygenase, ascorbate, catalase, and fumarate. Omission of ascorbate either inside or outside the ghosts greatly enhances dopamine accumulation, which reaches levels of approximately 30 nmol/mg under these conditions. Correspondingly, in the presence of all components, norepinephrine production reached approximately 100 nmol/mg in 30 min of incubation. Norepinephrine production was strictly magnesium-ATP-dependent, inhibited by either reserpine or dopamine beta-monooxygenase inactivation, and was markedly reduced when ascorbate was omitted from either inside or outside the ghosts. In the presence of limiting amounts of internal ascorbate, rapid norepinephrine production occurred which corresponded to the amount of initial ascorbate present, followed by a much slower endogenous norepinephrine production observable after complete depletion of internal ascorbate. The endogenous rate of norepinephrine production likely represents epinephrine-supported dopamine beta-monooxygenase turnover. Taken together, the data demonstrate that facile norepinephrine production by membrane-bound dopamine beta-monooxygenase occurs only when internal ascorbate is present, terminates upon depletion of internal ascorbate, and can only be sustained at a significant rate when reducing equivalents from external ascorbate are available. 相似文献
5.
Summary Five species of antarctic fishes can be arranged in order of increasing anaerobic capacity of the white muscles for burst swimming: Rhigophila dearborni (Zoarcidae), icefish (Channichthyidae), Dissostichus mawsoni, Trematomus centronotus, and Pagothenia borchgrevinki (Nototheniidae). This order reflects increasing dependence on anaerobic work done during short bursts of speed during prey capture or predator avoidance. Buffer capacity () for white muscle was lower than that of behaviourally equivalent fish from lower latitudes and is itself temperature-dependent. 相似文献
6.
7.
Oxidation of oxalate and polyamines by rat peroxisomes 总被引:1,自引:0,他引:1
M E Beard R Baker P Conomos D Pugatch E Holtzman 《The journal of histochemistry and cytochemistry》1985,33(5):460-464
During renal failure, polyamines and oxalate levels are elevated in the serum and the glomerular filtrate and are dumped by the kidney. Both of these compounds can be catabolized by oxidative reactions. We have, therefore, investigated the intracellular distribution of oxalate oxidase and of a polyamine oxidase in normal female rat kidney and liver. Polyamine oxidase was demonstrable, using spermidine as substrate in the cerous peroxyhydrate procedure of Briggs et al., in peroxisomes of kidney tubule cells and of hepatocytes. Oxalate oxidase could not be studied with this technique due to precipitation of cerium oxalate in the incubation medium. To demonstrate oxalate oxidase, and to confirm the polyamine oxidase localization, we incubated aldehyde-fixed tissue in a diaminobenzidine medium at pH 8, following the approach of Veenhuis et al., in which oxidases are demonstrated by virtue of their production of H2O2, which then serves as a substrate for endogenous catalase. Using oxalate or spermidine as substrate with this approach, we found reaction product in typical renal peroxisomes; we also found reaction product, with the polyamine substrate, in hepatocyte peroxisomes. To strengthen the conclusion that the oxidases themselves are present in peroxisomes, we used a light microscopic method, based on the tetrazolium procedures of Allen and Beard to demonstrate polyamine and oxalate oxidase activities in bodies with the distribution of renal peroxisomes. 相似文献
8.
Bleomycin degrades DNA under aerobic conditions when a ferrous salt is added. This reaction is enhanced by catalase and certain hydroxyl radical scavengers but inhibited by the addition of hydrogen peroxide. A ferricbleomycin complex is, however, stimulated by addition of hydrogen peroxide. These findings suggest that catalase removes hydrogen peroxide and in so doing prevents loss of ferrous ions and formation of hydroxyl radicals (OH.) by a Fenton-type reaction. It further suggests that OH. radicals, when formed, are more involved in the inactivation of bleomycin than in the release of thiobarbituric acid reactive material from DNA. 相似文献
9.
DISTRIBUTION OF PEROXISOMES (MICROBODIES) IN THE NEPHRON OF THE RAT : A Cytochemical Study 总被引:24,自引:9,他引:15
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The distribution of peroxisomes (microbodies) in the rat nephron was studied cytochemically, using glutaraldehyde- or formaldehyde-fixed tissue, by means of α-hydroxy acid oxidase activity in light microscopy or oxidation of 3,3'-diaminobenzidine (DAB) at pH 9 in both light and electron microscopy.The two cytochemical methods show peroxisomes to be nearly sperical particles found only in cells of the proximal convoluted tubule. Lysosomes were identified in the same or parallel sections, with β-glycerophosphate or 5'-cytidylic acid as substrate. They are found in all cells of the nephron. These cytochemical methods visualize the two organelles for light microscopy; they also permit unequivocal differentiation of all kidney peroxisomes from lysosomes in electron micrographs. Peroxisomes are larger and more reactive in the cells of the pars descendens (P3 segment) of the proximal convolution, located in the outer medulla and medullary rays, than in the cells of the pars convoluta (P1 and P2 segments), situated in the cortex. In contrast, lysosomes are much smaller in the P3 segment and larger and more reactive in the P1 and P2 segments. In all cells of the proximal convolution, peroxisomes tend to be concentrated nearer the base of the cells than do lysosomes. Mitochondria in P3 cells also show low levels of DAB oxidation at pH 6, in contrast to those in P1 and P2 cells. The possibility is discussed that P3 cells possess an extramitochondrial means of oxidation in which peroxisome oxidases play an important role. 相似文献
10.
Raimon L. Beard 《Entomologia Experimentalis et Applicata》1965,8(3):193-204
Suggested by immunological theory, this study was initiated to test an hypothesis on physiological induction of resistance to insecticides. The hypothesis was proved untenable in the test system, but from the experimentation emerged evidence for a chronically toxic action of DDT expressed in reduced fecundity in female house flies fed sub-lethal amounts of this insecticide. This action can be a strong selective force, promptly revealing tolerant genotypes in the population. The usual selection for resistance does not necessarily also select for ovarian tolerance; even DDT-resistant flies can show ovarian suppression when fed DDT-contaminated food.It is possible that the route of administration of the DDT is important as the means by which the physiologic events described can occur as a chronic intoxication without the usual acutely toxic effects.
Zusammenfassung Der vorliegenden Arbeit liegt die Frage zugrunde, ob Stubenfliegen, die bereits im Embryonalstadium DDT ausgesetzt werden, diesem gegenüber Resistenz erwerben können. Fütterung erwachsener Stubenfliegen mit C14-markiertem DDT führt zu dessen Inkorporation schon in den Eiern der Ovarien; die Inkorporation konnte in den schlüpfenden Larven weite verfolgt werden.In Versuchen, in denen je Versuchsglied stets nur die Nachkommenschaft eines Elternpaares (ein Eigelege) verwendet wurde, spalteten sich zwei gleichgrossen Populationen heraus: Während die eine die gleiche Anfälligkeit gegenüber DDT (0,12 g/Fliege) aufwies wie die Nachkommenschaft DDT-ungefütterter Eltern, war die andere Population dieser Dosis gegenüber tolerant.Die Ergebnisse von weiteren Versuchen belegen eindeutig, dass die durch DDT-Behandlung im Embryonalstadium hervorgerufene DDT-Toleranz primär nicht physiologisch bedingt ist, sondern primär auf genetischen Ursachen beruhen muss: Wurden DDT-gefütterte Weibchen mit DDT-anfälligen bzw. DDT-resistenten Männchen, denen kein DDT zum Futter gemischt worden war, gekreuzt, so war die gesamte Nachkommenschaft DDT-anfällig bzw. DDT-resistent.Es ergibt sich die Frage, welches Prinzip diese genotypisch verankerte Toleranz phänotypisch in Erscheinung treten lässt. Die in den Versuchen verwendeten DDT-Dosen waren ohne wesentlichen Einfluss auf den Eischlupf und die Mortalität von Larven und Fliegen. Dagegen senkte die Fütterung deutlich die Anzahl der zur Eiablage befähigten Weibchen und die Anzahl der von den anderen Weibchen gelegten Eier.相似文献