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151.
Endogeneous levels of zinc and copper were found to be 1.2±0.1×10−2 and 0.3±0.1×10−2 μg/A260 unit, respectively, in polysomal fractions from control animals; cadmium, however, was undetectable. In experimental
animals (injected with cadmium) zinc, copper, and cadmium were found in polysomal fractions isolated by two different methods.
One hour after a cadmium injection there was a rise in both the zinc and copper content of the polysomal fractions, which
then declined steadily to below control levels by 16 h. Neither zinc nor cadmium were dialyzable from these fractions by a
TRIS buffer; however, addition of 0.01M EDTA to the buffer resulted in removal of 75% of the zinc and all of the detectable cadmium.
The addition of cadmium (CdCl2) to control supernatants (adjusted to the cadmium concentration present in supernatants 6 h after in vivo exposure) resulted
in metal binding to polysomal fractions in levels comparable to those observed after in vivo exposures to the metal. When
cadmium was added in the form of cadmium thionein, a smaller fraction of the metal was isolated with the polysomal fraction.
Cadmium bound to polysomal fractions in vivo (24 h after exposure) was sensitive to release by protease digestion, but insensitive
to release by ribonuclease digestion. 相似文献
152.
Summary The ultrastructure of neurons in spinal ganglia of the domestic fowl poisoned with tri-ortho-cresyl-phosphate (TOCP) shows characteristic changes. The light neurons react to TOCP by a marked increase in the number of neurofilaments. These neurons also contain mitochondria in various degenerative stages. Several of the altered mitochondria show an increasing osmiophilia. Some of the darker neurons display a hypertrophy of the endoplasmic reticulum or a relative increase of neurofilaments. The mitochondria in some of these cells show early stages of degeneration. These changes appear 13 days after TOCP ingestion. 相似文献
153.
Daphnia magna as a test animal in acute and chronic toxicity tests 总被引:18,自引:2,他引:16
D. M. M. Adema 《Hydrobiologia》1978,59(2):125-134
Daphnia magna is a commonly used test animal in aquatic toxicology.Test procedures for acute and chronic test are described, together with the influence of several variables on their results.The practicability of the methods was checked with four model compounds, viz. 1,1,2-trichloroethane, dieldrin, pentachlorophenol and 3,4-dichloroaniline. Toxicity data of these compounds for Daphnia magna are given. 相似文献
154.
The red marine algae Microcladia borealis, M. californica and M. coulteri produce several unusual halogenated monoterpenes including violacene, plocamene-B, plocamene-C, and plocamane-D. The isolation of these terpenes along with a study of their variation in each Microcladia at different locations are described. 相似文献
155.
Richard p. Sheridan 《Journal of phycology》1978,14(3):279-281
Inhabition of photosynthesis in Chloroccoum sp by bisulfileion was the reciprocal of the light intensity curve. Respiration was least affected of the bisulfite after endogenous substrate was reduced by incubation in darkness. Maximum areduction in growth occurred with bisulfile treatment at or above optimal growth temperatures. Maximum phytotoxicity correlated with conditions resulting in maximum metabolic activity. The order of toxicity was –H2SO3HSO3?SO3. 相似文献
156.
BACKGROUNDS: Recently, potential liver toxicity was discussed with the intake of kava extract preparations (Piper methysticum) as anxiolytic drugs. The aim of this study was to test chronic toxicity in rats by oral application of an ethanolic kava full extract. METHODS: Wistar rats of both sexes were fed 7.3 or 73 mg/kg body weight of ethanolic kava extract for 3 and 6 months. The animals were examined for changes in body weight, hematological and liver parameters, and macroscopical and microscopical histological changes in the major organs. RESULTS: No signs of toxicity could be found. CONCLUSIONS: The results are in accordance with the medical experience regarding the use of kava preparations and the long tradition of kava drinking in the South Pacific island states. Specifically, the results do not back the suspicion of potential liver toxicity. 相似文献
157.
The antibacterial activities of isoflavonoid (kievitone and phaseollin), flavonoid (hydroxyflavans), furanoacetylenic (wyerone), and sesquiterpenoid (capsidiol and rishitin), phytoalexins against eight Gram-negative and six Gram-positive bacteria were examined using the paper-disc antibiotic assay method. With the exception of capsidiol, which was inactive at the highest concentration tested (200,μg/disc) all of the phytoalexins were selectively toxic towards Gram-positive species. Wyerone and kievitone were generally more toxic than other phytoalexins; rishitin was the least active inhibitor. 相似文献
158.
Thio-dimethylarsinic acid (thio-DMAV) is a human urinary metabolite of the class 1 human carcinogen inorganic arsenic as well as of arsenosugars. Thio-DMAV exerts strong cellular toxicity, whereas its toxic modes of action are not fully understood. For the first time, this study characterises the impact of a long-term (21 days) in vitro incubation of thio-DMAV on the expression of selected genes related to cell death, stress response, epigenetics and DNA repair. The observed upregulation of DNMT1 might be a cellular compensation to counterregulate the in a very recent study observed massive global DNA hypomethylation after chronic thio-DMAV incubation. Moreover, our data suggest that chronic exposure towards subcytotoxic, pico- to nanomolar concentrations of thio-DMAV causes a stress response in human urothelial cells. The upregulation of genes encoding for proteins of DNA repair (Apex1, Lig1, XRCC1, DDB2, XPG, ATR) as well as damage response (GADD45A, GADD45G, Trp53) indicate a potential genotoxic risk emanating from thio-DMAV after long-term incubation. 相似文献
159.
Sandor Doma 《Hydrobiologia》1979,67(2):183-188
A new rearing technique ideally suitable for promoting either the parthenogenetic or the gametogenetic (ephippia) type of reproduction ofDaphnia magna in the laboratory is described. Airdrying and rehydration induces rapid hatching. Using this technique it is possible to measure the toxicity of chemicals to ephippia in an 8 day test procedure. 相似文献
160.
Anna-Maj Balsberg-Påhlsson 《Plant and Soil》1995,175(1):125-132
Deschampsia flexuosa (L.) Trin. is an abundant grass species in the ground flora of acidic beech forests in southern Sweden. Generally, the species
is restricted to a limited soil pH range (pH 4–5). The main objective was to study the influence of different soil acidities
on germination, initial root development and on the growth of the species. The experiments were carried out under controlled
conditions and designed to simulate the physico-chemical conditions present in the field. By using forest soils within the
pH range 4.0 to 8.3 and artificial variation in pH (3.2 to 7.6) of soil-water extracts, it was possible to evaluate the influence
of soil reaction and the H+ per se. In all experiments seeds have been used. Germination was significantly delayed in the very acid soil (pH 4.0) in
comparison to the germination in soils within the pH range (4.4 to 6.4). Soil substances, other than the H+, might be responsible for this delay in germination, whereas development of the radicle was markedly affected by increasing
H+ concentrations. Especially the development of root hairs was sensitive to H+ and was significantly reduced at a pH<-3.8. By increasing soil acidity the injury symptoms, including curling and discolouring,
became more intense and at the highest acidity (pH 3.2) the radicles appeared brown, stunted and the root hairs were lacking.
Most favourable growth was obtained at pH 4.4 and 5.0. Soil pH levels above and below this range limited both shoot and root
growth. The results showed very good correspondence with observations made in Beech forest soils in southern Sweden, where
the species was growing in soils within the pH range 3.9 to 5.1 with a peak growth at pH 4.3. This study shows that in soils
at pH≤3.8, the poor development of the radicle may be crucial in the establishment ofDeschampsia flexuosa. Root hair development was more sensitive to soil acidity than radicle elongation. Germination was delayed in very acid Beech
forest soils but other factors than the H-ion per se may be responsible for this delay. 相似文献