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1.
JOSEPH DONNELLY 《The Annals of applied biology》1958,46(2):243-253
1. A simple method of radioactive labelling of L. sericata larvae is described.
2. More uniform count levels are obtained in individuals which have fed entirely on radioactive foods than in those which first feed on non-active food.
3. The radioactive count rates of the larvae are correlated with larval live weight and the counting rates of resulting imagines correlated both with corresponding larval counting rates and with imaginal live weight.
4. The loss of32 P in the larvae due to causes other than decay of the isotope is traced from the prepupal stage to 3 weeks after emergence. The first and major loss occurs at emergence, when about 10% of the original 31 P is shed as empty puparium and meconium. Adults lose about 1.5% per day.
5. The distribution of32 P in the adult body of L. sericata labelled in the larval stage has been determined. The abdominal tissues have a lower activity than the rest of the body. 相似文献
2. More uniform count levels are obtained in individuals which have fed entirely on radioactive foods than in those which first feed on non-active food.
3. The radioactive count rates of the larvae are correlated with larval live weight and the counting rates of resulting imagines correlated both with corresponding larval counting rates and with imaginal live weight.
4. The loss of
5. The distribution of
2.
Colonization of Vibrio pelagius and Aeromonas caviae in early developing turbot (Scophthalmus maximus L.) larvae 总被引:2,自引:1,他引:1
Polyclonal antisera made in rabbits against whole washed cells of Vibrio pelagius and Aeromonas caviae were used for detection of these bacterial species in the rearing water and gastrointestinal tract of healthy turbot ( Scophthalmus maximus ) larvae exposed to V. pelagius and/or Aer. caviae . The results demonstrated that this method is suitable for detection of V. pelagius and Aer. caviae in water samples and larvae at population levels higher than 103 ml−1 and 103 larva−1 . Populations of aerobic heterotrophic bacteria present in the gastrointestinal tract of turbot larvae, estimated using the dilution plate technique, increased from approximately 4 × 102 bacteria larva−1 on day 3 post-hatching to approximately 105 bacteria fish−1 16 days post-hatching. Sixteen days after hatching, Vibrio spp. accounted for approximately 3 × 104 cfu larva−1 exposed to V. pelagius on days 2, 5 and 8 post-hatching. However, only 103 of the Vibrio spp. belonged to V. pelagius . When larvae were exposed to Aer. caviae on day 2 post-hatching, the gut microbiota of 5-day old larvae was mainly colonized by Aeromonas spp. (104 larva−1 ), of which 9 × 103 belonged to Aer. caviae . Later in the experiment, at the time when high mortality occurred, 9 × 105 Aer. caviae were detected. Introduction of V. pelagius to the rearing water seemed to improve larval survival compared with fish exposed to Aer. caviae and with the control group. It was therefore concluded that it is beneficial with regard to larval survival to introduce bacteria ( V. pelagius ) to the rearing water. 相似文献
3.
In the sugar beet plant ( Beta vulgaris L. ssp. altissima ) the vascular bundles of old leaves lead to the center and those of young leaves to the periphery of the storage root. Whether the flux of assimilates follows these anatomical routes was tested by applying 14 CO2 for 4 h to either an old (10th) or a young (20th) leaf in intact sugar beet plants. Four-month-old plants, which had about 30 leaves, were used in the experiment. The 14 C distribution in the storage root was measured by autoradiography and counting in about 20 cross and longitudinal sections per root.
About 37% of assimilated14 C from an old leaf and 23% from a young leaf were exported within 24 h. Although some 14 C moved into younger leaves, most was exported into the storage root. During its rapid movement towards the root tip, which took place perferentially in the orthostichon belonging to the [14 C]-treated leaf, the label spread laterally.
The autoradiograms indicate that the distribution of assimilates within the storage root is roughly determined by the course of the vascular bundles extending from the source leaf. The fine distribution, however, seems to be controlled by sucrose gradients between storage cells. 相似文献
About 37% of assimilated
The autoradiograms indicate that the distribution of assimilates within the storage root is roughly determined by the course of the vascular bundles extending from the source leaf. The fine distribution, however, seems to be controlled by sucrose gradients between storage cells. 相似文献
4.
Christian Chabert Catherine Cavegn Alain Bernard Ann Mills 《Journal of neurochemistry》1994,63(1):62-65
Abstract: The human D4 dopamine receptor has been expressed in Sf9 insect cells where it appears to couple to endogenous G proteins. Increased guanine nucleotide exchange to G proteins is a reflection of receptor activation and can be followed using a [35 S]GTPγS binding assay. By measuring D4 receptor stimulation of [35 S]-GTPγS binding we have been able to characterize several dopaminergic compounds for their functional activity at this receptor. In Sf9 cells expressing the D4 receptor, dopamine, quinpirole, and dp -2-aminodihydroxy-1,2,3,4-tetrahydronaphthalene were all full agonists, whereas (−)-apomorphine appeared to be a partial agonist. No increase in [35 S]GTPγS binding was observed for noninfected cells or cells infected with an unrelated sequence. The quinpirole-stimulated [35 S]GTPγS binding could be inhibited by the antagonists clozapine, eticlopride, and haloperidol, and a Schild analysis of these data showed that all three compounds were acting as competitive antagonists of D4 receptors. The rank order of affinities derived from the Schild analysis correlated with that obtained from [3 H]spiperone competition binding assays. In conclusion, we have shown that, using this assay system, it is possible to investigate functionally the pharmacology of a recombinant G protein-coupled receptor in the absence of any information regarding the eventual second messenger pathways involved. 相似文献
5.
Abstract: The susceptibility of various developmental stages of Tetranychus evansi Baker & Pritchard (eggs, larvae, protonymphs, deutonymphs and adults) to the entomopathogenic fungi Metarhizium anisopliae (Metschnikoff) Sorokin and Beauveria bassiana (Balsamo) Vuillemin was evaluated under laboratory conditions. Three concentrations (3.0 × 106 , 1.0 × 107 and 1.0 × 108 conidia/ml) of both fungi were used for each stage. The effect of fungal infection on fecundity and egg fertility was also investigated using both fungal species. Deutonymphs that survived the infection and developed into adult females were allowed to oviposit. Adults and deutonymphs were more susceptible to fungal infection than larval and protonymphal stages at all the concentrations. Nevertheless, the concentration level influenced the mortality of the different mite stages. Eggs were also susceptible to fungal infection and mortality was dose-dependent. Fungus-treated female mites laid fewer eggs than the controls but there was no significant difference in egg hatchability between the treatments. 相似文献
6.
Abstract: The activities mediated by the N -methyl-D-aspartate (NMDA) receptor were studied in cultured rat cerebellar granule cells. Micromolar concentrations of the metal binding compounds, EDTA, cysteine, and histidine, as well as serum albumin strongly potentiated receptor activity in the presence of millimolar concentrations of Ca2+ and Mg2+ . The findings indicated that these agents remove an endogenous metal, probably Zn2+ , which attenuates NMDA receptor-mediated 45 Ca uptake and toxicity. Several added metal ions were therefore tested at low micromolar concentrations. Zn2+ was found to be the most potent inhibitor of NMDA-induced 45 Ca uptake, followed by Cu2+ and Fe2+ . Co2+ , Cd2+ , Fe3+ , and AI3+ had no significant effect, whereas Ni2+ potentiated the 45 Ca uptake but inhibited at much higher concentrations. The potentiating agents that remove the endogenous metal had a particularly dramatic effect in the presence of Mg2+ , the voltage-dependent suppressor of the NMDA receptor. Mg2+ also played an important role in the inhibitory effect of added Zn2+ . Much lower concentrations of Zn2+ were needed to achieve inhibition of NMDA-induced 45 Ca uptake in the presence of Mg2+ . Under a variety of conditions, a very good correlation was found between NMDA receptor-mediated 45 Ca uptake and the magnitude of acute neurotoxicity. 相似文献
7.
ABSTRACT. Various doses of a microsporan parasite, Nosema sp., were fed to third and fourth instar larvae of Lesioderma sericorne that infested different types of stored grains. A spore dose of 3 × 103 spores/individual resulted in a 39% infection rate, reduction in larval and adult weights, and mean spore concentrations of 1.28 ± 0.2 × 108 spores/larva and 1.1 ± 0.2 × 108 spores/adult. At the above dose, mortality was not well marked (about 35% in larvae and 25% in adults). At 3 × 104 spores/individual, the rate of mortality increases to 80% in larvae and 60% in adults. However, more of the pest population (88% of larvae and 73% of adults) died at a dose of 3 × 105 spores/individual. This dose produced mean spore concentrations of 3.91 ± 0.2 × 108 spores/larva and 2.89 ± 0.2 × 108 spores/adult. Insect death was caused by heavy damage to gut epithelia and fat bodies. 相似文献
8.
Effects of nitrate, chloride and chlorate ions upon nitrate and chlorate uptake by roots of maize ( Zea mays L., cv. B73) seedlings were examined. Net nitrate uptake, 36 ClO3 − influx and 36 Cl− influx (the latter two in a background of 0.5 m M KNO3 ) displayed similar pH profiles with optima at pH 5.5 and below. External, non-labeled chloride had little effect on the accumulation of 36 ClO3 − (both in 5 h and 20 min uptake assays), while nitrate and chlorate had almost identical, marked inhibitory effects. Nitrate pretreatment caused an apparent induction of both 36 ClO3 − and 15 NO3 − uptake activities. After 5 h of treatment in nitrate, the uptake activities of chloride- and chlorate-pretreated plants increased to that of nitrate-pretreated plants. During 6 h exposure to chlorate, 36 ClO3 − uptake activity of nitrate-pretreated plants decreased to that of chlorate- and chloride-pretreated plants. The results support the existence of a shared nitrate/chlorate transport system in maize roots which is not inhibited by external chloride, and which is induced by nitrate, but not by chlorate or chloride. The suggestion is made that selection of chlorate-resistant mutants of maize can identify nitrate uptake as well as nitrate reductase mutants. 相似文献
9.
Laura J. Sim Qixu Liu Steven R. Childers Dana E. Selley 《Journal of neurochemistry》1998,70(4):1567-1576
Abstract: Endomorphin-1 is a peptide whose binding selectivity suggests a role as an endogenous ligand at μ-opioid receptors. In the present study, the effect of endomorphin-1 on μ receptor-coupled G proteins was compared with that of the μ agonist DAMGO by using agonist-stimulated [35 S]GTPγS binding in rat brain. [35 S]GTPγS autoradiography revealed a similar localization of endomorphin-1 and DAMGO-stimulated [35 S]GTPγS binding in areas including thalamus, caudate-putamen, amygdala, periaqueductal gray, parabrachial nucleus, and nucleus tractus solitarius. Naloxone blocked endomorphin-1-stimulated labeling in all regions examined. Although the distribution of endomorphin-1-stimulated [35 S]GTPγS binding resembled that of DAMGO, the magnitude of endomorphin-1-stimulated binding was significantly lower than that produced by DAMGO. Concentration-effect curves of endomorphin-1 and DAMGO in thalamic membranes confirmed that endomorphin-1 produced only 70% of DAMGO-stimulated [35 S]GTPγS binding. Differences in maximal stimulation of [35 S]GTPγS binding between DAMGO and endomorphin-1 were magnified by increasing GDP concentrations, and saturation analysis of net endomorphin-1-stimulated [35 S]GTPγS binding revealed a lower apparent B max value than that obtained with DAMGO. Endomorphin-1 also partially antagonized DAMGO stimulation of [35 S]GTPγS binding. These results demonstrate that endomorphin-1 is a partial agonist for G protein activation at the μ-opioid receptor in brain. 相似文献
10.
David A. Morris 《Physiologia plantarum》1981,52(2):251-256
When N 6 [8–14 C] furfuryladenine was applied to the intact root system of Pisum sativum L. cv. Meteor seedlings it was almost completely metabolised to other compounds within 24 h. Of the total activity recovered from the plants 94.5% was retained in the root system itself. 14 C was recovered in a number of ethanol-soluble compounds and in ribonucleic acid, deoxyribonucleic acid and protein fractions of roots, stems, leaves and axillary buds. In rapidly growing axillary buds released from apical dominance by removal of the shoot apex the combined nucleic acid fractions accounted for 63.3% of the total 14 C recovered from these organs. Xylem exudate collected from decapitated plants 0 to 12 h after supplying N 5 [8–14 C]furfuryladenine to the roots consistently contained a single major 14 C-labelled compound which, in three different solvent systems, had the same Rf values as a major endogenous cytokinin isolated from the xylem of unlabelled plants. The content of N 6 [8–14 C] furfuryladenine itself in the xylem exudate was always low and in some experiments it could not be detected.
It is suggested that part of the label from N6 [8- 14 CJfurfuryladenine taken up by the intact root system may have become incorporated in an endogenous cylokinin before export to the shoot. 相似文献
It is suggested that part of the label from N
11.
We report a novel use of the 15 N dilution technique to detail the translocation of amino compounds in the legume Sesbania rostrata . The conventional 15 N dilution technique follows the dilution of 15 N within a labelled plant, as 14 N2 is fixed by symbiotic bacteria. In our experiments, stem-nodulated Sesbania rostrata were enriched by feeding with 15 N ammonium nitrate for 2 weeks, followed by a 1 week period where the only N available to the plants was via nitrogen fixation of atmospheric N2 . We measured the composition, concentration and 15 N enrichment of amino compounds in various plant tissues, both above and below the stem nodules, using GC-MS and isotopic abundance mass spectrometry techniques. Approximately 28% of the total N in the stem nodules was derived from internal plant sources. The ureides allantoic acid and allantoin were not abundant in xylem, leaf or nodule tissues. The amides asparagine and glutamine were the major export products from stem nodules although a wide range of other amino compounds are also synthesized. Amino acids within the nodules had a low level of enrichment, demonstrating that a small fraction (≈ 11%) was derived from outside the nodules, and significant cycling of N (28% of xylem N) through the root system was revealed by measurements of 15 N distribution and amino acid concentrations. 相似文献
12.
Carbon dioxide fixation in orchid aerial roots 总被引:1,自引:0,他引:1
Acidity fluctuation, CO2 gas exchange, δ13 C value, PEP carboxylase and RuBP carboxylase activities in aerial roots of selected thick-leaved orchid hybrids ( Arachnis and Aranthera ) were studied. Both aerial roots and leaves showed acidity fluctuation over a 24 h period. Dark acidification in aerial roots was enhanced at low temperature (15°C). Aerial roots had δ13 C values close to those of leaves which have been previously demonstrated to possess crassulacean acid metabolism. Variation in δ13 C values along the length of the roots was observed; the root tip having a less negative δ13 C value (—13.34%‰) than the older portions of the roots (—14.55%‰). There was no net CO2 fixation by aerial root, although 1432 CO2 fixation was observed in light and in darkness. The pattern of fluctuation in activities of PEP carboxylase and RuBP carboxylase in aerial roots was similar to that obtained for the leaves. In both aerial roots and leaves, PEP carboxylase activity was several times higher than that of RuBP carboxylase. 相似文献
13.
Anadromous whitefish [ Coregonus lavaretus (L.)] yolk-sac larvae were marked with a radioactive strontium isotope, 85 Sr. Before marking the method was tested in accumulation-elimination tests using various strontium concentrations. The first-phase effective half-life of 85 Sr in yolk-sac larvae was 4 days. The mean 85 Sr radioactivity was 81 Bq per larva at the day of release and the half-life of the slow component was 51 days, so the strontium label was easily detected up to 60 days after marking. The larvae were released into the River Simojoki about 12 km upstream from the river mouth and recaptured from early May to the end of July. Marked larvae were found at the river mouth 12–13 days after release, while the last marked fish in the river were found at 16 days. It is likely that all leave the river within 2 to 3 weeks post-hatching. Two months after marking some larvae had attained a distance of 10 km from the river mouth. 相似文献
14.
Methane-derived carbon flows through methane-oxidizing bacteria to higher trophic levels in aquatic systems 总被引:1,自引:0,他引:1
Recent investigations have shown that biogenic methane can be a carbon source for macro invertebrates in freshwater food webs. Stable carbon isotopic signatures, used to infer an organism's food source, indicated that methane can play a major role in the nutrition of chironomid larvae. However, the pathway of methane-derived carbon into invertebrate biomass is still not confirmed. It has been proposed that chironomid larvae ingest methane-oxidizing bacteria (MOB), but this has not been experimentally demonstrated to date. Using 13 C-labelled methane we could show for the first time that chironomid larvae assimilate methane-derived carbon through MOB. Chironomid larval biomass was significantly 13 C-enriched after dwelling for 10 days in lake sediment enriched with labelled methane. Moreover, phospholipid fatty acids diagnostic for MOB were detected in larval tissue and were significantly 13 C-enriched, which encompasses the 13 C-uptake predicted for a methane-based nutrition. Additionally, chironomid larvae fed on sediment and water-column derived MOB biomass. 相似文献
15.
16.
GABA UPTAKE IN RAT CENTRAL NERVOUS SYSTEM: COMPARISON OF UPTAKE IN SLICES AND HOMOGENATES AND THE EFFECTS OF SOME INHIBITORS 总被引:26,自引:16,他引:10
Abstract— Fifty-two substances were tested as inhibitors of the uptake of [3 H]GABA in slices of rat cerebral cortex. Among GABA analogues tested, only the 2-fluoro, 3-hydroxy and 2-amino compounds had affinities for the uptake mechanism comparable to that of GABA. [3 H]GABA uptake was also potently inhibited by p -chloromercuriphenylsulphonate, N -ethylmaleimide, chlorpromazine and haloperidol. No inhibitors were found to act in a competitive manner with respect to GABA. [3 H]GABA uptake was also examined in homogenates of cerebral cortex and other regions of CNS. There was a rapid uptake of [3 H]GABA into particles when homogenate samples were incubated with the labelled amino acid; this uptake had similar kinetic properties and inhibitor sensitivity to that observed in slices of intact tissue. Density gradient centrifugation experiments indicated that the particles responsible for the uptake of [3 H]GABA in homogenates were probably synaptosomes. Uptake of [3 H]GABA also occurred in slices and homogenates of rat spinal cord, and evidence was obtained by the simultaneous labelling of homogenates with [14 C]glycine and [3 H]GABA that these two amino acids were taken up by different nerve terminals in this region. 相似文献
17.
Abstract— By using a combination of subcutaneous and intraventricular injections of [14 C]uridine and [3 H]methyl- l -methionine we have obtained maximum incorporation in about 40 min of both radioactive precursors into nuclear RNA from rat brain. In this nuclear fraction we found at least two different types of RNA that were rapidly labelled. One of them incorporated both [14 C]uridine and [3 H]methyl groups and seemed to correspond to species of rRNA and their precursors. The other RNA fraction was less methylated or non-methylated and exhibited sedimentation coefficients distributed along a continuous 8–30 % sucrose density gradient. At least part of the latter type of RNA very probably was mRNA, but much of it must conespond to a different RNA similar to that recently described in HeLa cells by P enman , V esco and P enman (1968).
We also found that labelled 185 and 285 rRNA components began leaving the nucleus for the cytoplasm within 24 to 33 min after the radioactive precursors had been injected, and, in the cytoplasmic fraction, the patterns of incorporation for [14 C]uridine and [3 H]-methyl groups were similar for the 18S and 28S rRNA components. We estimate that in this fraction of rat brain the 18S rRNA component was 1·4 times more methylated than the 28S component. We also detected a lower sedimentation coefficient for the non- or slightly methylated, species of soluble RNA found in the cytoplasmic fraction. 相似文献
We also found that labelled 185 and 285 rRNA components began leaving the nucleus for the cytoplasm within 24 to 33 min after the radioactive precursors had been injected, and, in the cytoplasmic fraction, the patterns of incorporation for [
18.
Abstract The distribution of heterotrophic bacteria in polluted coastal and unpolluted pelagic seawaters was studied using a 14 C-MPN method with either five of seven kinds of 14 C-organic compounds as substrates. The total number of heterotrophic bacteria in pelagic waters ranged from 9.2 × 103 to 5.4. ¢ 104 cell/ml and more than 85% of the heterotrophic bacteria were represented by obligate oligotrophs. In coastal waters, the number of heterotrophs was one order of magnitude higher (av. 3.5 ¢ 105 cells/ml), and eutrophic and facultatively oligotrophic bacteria were predominant. Oligotrophs in pelagic waters had a high specificity for the utilization of amino acids, especially glycine, and acetate-utilizing bacteria were scarce. The in situ maximum uptake rates of glutamate and glycine were much higher than those of glycolate and acetate. Acetate uptake rates were extremely low or not detectable in pelagic waters. The specificity of uptake kinetics is assumed to depend on the existence of obligate oligotrophs as dominant bacteria in pelagic seawater. 相似文献
19.
QIANGWANG JIA-ANCHENG ZHONG-MINLIU SHENG-GANWU XUE-PINGZHAO CHANG-XINGWU 《Insect Science》2005,12(2):109-119
Synergistic actions for mixtures of abamectin with other insecticides in some insect pests were evaluated, and the possible synergistic mechanism was studied by the comparison in toxicity and cuticular penetration of abamectin between with and without other insecticides or synergists in Helicoverpa armigera larvae. The results of bioassay showed that horticultural mineral oil (HMO), hexaflumuron, chlorpyrifos, and some other insecticides were synergistic to abamectin with 152.0-420.0 of co-toxicity coefficient(CTC) in some agricultural insect pests. In topical application tests, HMO or piperonyl butoxide (PBO) increased the toxicity of abamectin in larvae of H. armigera, but the mortality was not affected by s,s,s-tributylphorotrithioate (DEF) and triphenylphosphate (TPP). The synergistic action of HMO was obviously higher than PBO, and when treated simultaneously with abamectin, HMO gave a more significant synergism than if treated 2 hours ahead. The highest synergistic effect (SE) was found in the mixture of ‘abamectin HMO (1:206)‘. The mortality did not increase or the toxicity drop, when a synergist or HMO was added into the mixture of ‘abamectin HMO‘ or ‘abamectin synergist‘, respectively. Results from the isotope tracing experiments showed that HMO significantly enhanced the penetration of ^3H-abamectin through the cuticle of H.armigera larvae, which resulted in the synergism of the mixture. The cuticular penetration of ^3H-abamectin was not accumulatively affected by chlorpyrifos, nor by hexaflumuron,though there was an inhibition within 30 seconds or 1 hour after treated by these two chemicals respectively. Results suggested that the synergism of abamectin mixed with hexaflumuron or chlorpyrifos might be related to inhibition of metabolic enzymes or target sites in the larvae. 相似文献
20.
Abstract: [3 H]Diazepam and [3 H]flunitrazepam ([3 H]FNP) binding to washed and frozen synaptosomal membranes from rat cerebral cortex were compared. In Tris-citrate buffer, γ -aminobutyric acid (GABA) and NaCl both increased [3 H]diazepam binding more than [3 H]FNP binding. GABA and pentobarbital both enhanced this effect of NaCl. Because of the extremely rapid dissociation of [3 H]diazepam in the absence of NaCl and GABA, the Bmax (maximal binding capacity) was smaller by the filtration assay than by the centrifugation assay. [3 H]FNP, which dissociates more slowly, had the same Bmax in both assays. [3 H]Diazepam association had two components, and was faster than [3 H]FNP association. [3 H]Diazepam dissociation, which also had two components, was faster than that of [3 H]FNP, and also had a greater fraction of rapidly dissociating species. [3 H]FNP dissociation was similar when initiated by diazepam, flunitrazepam, clonazepam, or Ro15-1788, which is a benzodiazepine antagonist. [3 H]Diazepam dissociation with Ro15-1788, flunitrazepam, or clonazepam was slower than with diazepam. GABA and NaCl, but not pentobarbital, increased the percentage of slowly dissociating species. This effect of NaCl was potentiated by GABA and pentobarbital. The results support the cyclic model of benzodiazepine receptors existing in two interconvertible conformations, and suggest that, distinct from their binding affinity, some ligands (like flunitrazepam) are better than others (like diazepam) in inducing the conversion of the receptor to the higher-affinity state. 相似文献