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1.
Magnesium-induced inner membrane aggregation in heart mitochondria: prevention and reversal by carboxyatractyloside and bongkrekic acid 下载免费PDF全文
Mg(2+) at an optimal concentration of 2mM (ph 6.5) induces large increases (up to 30 percent) in the optical density of bovine heart mitochondria incubated under conditions of low ionic strength (< approx. 0.01). The increases are associated with aggregation (sticking together) of the inner membranes and are little affected by changes in the energy status of the mitochondria. Virtually all of a number of other polyvalent cations tested and Ag(+) induce increases in mitochondrial optical density similar to those induced by Mg(2+), their approximate order of concentration effectiveness in respect to Mg(2+) being: La(3+) > Pb(2+) = Cu(2+) > Cd(2+) > Zn(2+) > Ag(+) > Mn(2+) > Ca(2+) > Mg(2+). With the exception of Mg(2+), all of these cations appear to induce swelling of the mitochondria concomitant with inner membrane aggregation. The inhibitors of the adenine nucleotide transport reaction carboxyatratyloside and bongkrekic acid are capable of preventing and reversing Mg(2+)-induced aggregation at the same low concentration required for complete inhibition of phosphorylating respiration, suggesting that they inhibit the aggregation by binding to the adenine nucleotide carrier. The findings are interpreted to indicate (a) that the inner mitochondrial membrane is normally prevented from aggregating by virtue of its net negative outer surface change, (b) that the cations induce the membrane to aggregate by binding at its outer surface, decreasing the net negative charge, and (c) that carboxyatractyloside and bongkrekic acid inhibit the aggregation by binding to the outer surface of the membrane, increasing the net negative charge. 相似文献
2.
PJ?MumbyEmail author JD?Hedley JRM?Chisholm CD?Clark H?Ripley J?Jaubert 《Coral reefs (Online)》2004,23(2):171-183
Trends in coral cover are widely used to indicate the health of coral reefs but are costly to obtain from field survey over large areas. In situ studies of reflected spectra at the coral surface show that living and recently dead colonies can be distinguished. Here, we investigate whether such spectral differences can be detected using an airborne remote sensing instrument. The Compact Airborne Spectrographic Imager (Itres Research Ltd, Canada) was flown in two configurations: 10 spectral bands with 1-m2 pixels and 6 spectral bands with 0.25-m2 pixels. First, we show that an instrument with 10 spectral bands possesses adequate spectral resolution to distinguish living Porites, living Pocillopora spp., partially dead Porites, recently dead
Porites (total colony mortality within 6 months), old dead (>6 months) Porites,
Halimeda spp., and coralline red algae when there is no water column to confuse spectra. All substrata were distinguished using fourth-order spectral derivatives around 538 nm and 562 nm. Then, at a shallow site (Tivaru) at Rangiroa Atoll, Tuamotu Archipelago (French Polynesia), we show that live and dead coral can be distinguished from the air to a depth of at least 4 m using first- and fourth-order spectral derivatives between 562–580 nm. However, partially dead and recently dead Porites
colonies could not be distinguished from an airborne platform. Spectral differences among substrata are then exploited to predict the cover of reef substrata in ten 25-m2 plots at nearby Motu Nuhi (max depth 8 m). The actual cover in these plots was determined in situ using quadrats with a 0.01-m2 grid. Considerable disparity occurred between field and image-based measures of substrate cover within individual 25-m2 quadrats. At this small scale, disparity, measured as the absolute difference in cover between field and remote-sensing methods, reached 25% in some substrata but was always less than 10% for living coral (99% of which consisted of
Porites spp.). At the scale of the reef (all ten 25-m2 quadrats), however, disparities in percent cover between imagery and field data were less than 10% for all substrata and extremely low for some classes (e.g. <3% for living
Porites, recently dead Porites
and Halimeda). The least accurately estimated substrata were sand and coralline red algae, which were overestimated by absolute values 7.9% and 6.6%, respectively. The precision of sampling was similar for field and remote-sensing methods: field methods required 19 plots to detect a 10% difference in coral cover among three reefs with a statistical power of 95%. Remote-sensing methods required 21 plots. However, it took 1 h to acquire imagery over 92,500 m2 of reef, which represents 3,700 plots of 25 m2 each, compared with 3 days to survey 10 such plots underwater. There were no significant differences in accuracy between 1-m2 and 0.25-m2 image resolutions, suggesting that the advantage of using smaller pixels is offset by reduced spectral information and an increase in noise (noise was observed to be 1.6–1.8 times greater in 0.25-m2 pixels). We show that airborne remote sensing can be used to monitor coral and algal cover over large areas, providing that water is shallow and clear, and that brown fleshy macroalgae are scarce, that depth is known independently (e.g. from sonar survey). 相似文献
3.
The response of trout and zebrafish embryos to low and high boron concentrations is U-shaped 总被引:2,自引:0,他引:2
Fish in the embryo-larval stage of development have been shown to be sensitive to boron (B) at both ends of the dose-response
curve (1,2). The present study evaluated the health effects of low and high B concentrations on rainbow trout (Oncorhynchus mykiss), a cold water species, and zebrafish (Danio rerio), a warm water species. Rainbow trout embryos were incubated from day 1 until 2 wk posthatch in Type 1 ASTM ultrapure-grade
water (12.5°C) supplemented with only B (0-500 μM) as boric acid, or together with CaCO3 (0–2 mM) to increase water hardness. Embryonic growth was stimulated by B in a dose-dependent manner at all Ca concentrations
(p < 0.001). Chronic exposures below 9 μmol B/L impaired embryonic growth and above 10 mmol B/L caused death (p < 0.001). Thus, the safe range of exposure for the rainbow trout was between the adverse effect concentrations of 9 μmol
B/L and 10 mmol B/L. Zebrafish were maintained for 6 mo in ultrapure water containing <0.2 μmol B/L to determine the effect
of low-level exposure. High-level exposure was assessed by exposing zygotes, derived from parents maintained at 46 μmol B/L,
to graded concentrations of boric acid up to a concentration of 75 mmol B/L from fertilization until they were free feeding
(96 h). Fertilization occurred, but zygotes failed to survive when water contained <0.2 umol B/L (p < 0.001). Death occurred at and above 9.2 mmol B/L. Thus, the safe range of B exposure for zebrafish was between the adverse
effect concentrations of 0.2 μmol B/L and 9.2 mmol B/L. The dose-response for both species was thus U-shaped.
Part of this work was previously published in abstract form and presented at Experimental Biology 97, April 6–9, New Orleans,
LA (Eckhert, C. [1997] Embryonic trout growth and boron exposure,FASEB J.
11, A406 [abstract]). 相似文献
4.
EO Ogueji CD Nwani SC Iheanacho CE Mbah CO Okeke A Yaji 《African Journal of Aquatic Science》2018,43(3):293-303
Indiscriminate discharge of pharmaceutical waste into the aquatic ecosystem may pose serious health challenges to aquatic biota. The effect of acute exposure to ibuprofen was evaluated using changes in behaviour and haematological parameters under static bio-assay method in Clarias gariepinus. Test specimens were exposed to acute concentrations of ibuprofen (0.28, 0.33, 0.38, 0.43 and 0.48 mg l?1) for 24, 48, 72 and 96 h durations respectively. Behavioural and phenotypic changes were observed in surviving fish. There were significant (p < 0.05) concentration and duration-dependent increases in erythrocyte (RBC), haemoglobin (Hb), pack cell volume (PCV) and leukocytes (WBC) in treated fish compared to the control. Insignificant decreases (p > 0.05) in mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were observed in treated fish compared to the control. Ibuprofen elicited dose and duration- dependent decrease in neutrophil counts with the decreases being significant (p < 0.05) in the higher doses of 0.43 and 0.48 mg l?1. Ibuprofen did not elicit any significant changes in monocytes, basophils and eosinophils. Changes observed in this study showed that ibuprofen negatively affected the health of the fish and we recommend that discharge of ibuprofen into the aquatic environment should be monitored and controlled. 相似文献
5.
6.
Sarah E. Kobylewski Kimberly A. Henderson Kristin E. Yamada Curtis D. Eckhert 《Biological trace element research》2017,175(2):278-286
We aimed to evaluate the association of exposure to lead with glycated hemoglobin (HbA1c), fasting glucose levels (FGLs), and the likelihood for dysglycemia. We accessed data from Canada Health and Measures Survey. General linear models were used to estimate the association between blood lead concentrations (BPb) and both HbA1c and FGLs, while controlling for confounders. Multivariate logistic regression was used for assessing the relation between BPb and the likelihood for dysglycemia. FGLs in participants with moderate BPb (2.5–5.0 μg/dL) were 1.03 (95 % CI 1.00–1.06) times higher compared with participants with BPb < 2.5 μg/dL. Equivalent figures for those with BPb ≥ 5.0 μg/dL were 1.10 (95 % CI 1.01–1.20) times, relative to the lowest stratum. This association was attenuated using HbA1c to define dysglycemia. Lead exposure was associated with the likelihood for neither FGLs ≥ 1.10 g/L nor HbA1c ≥ 5.7 %. The association between lead exposure and dysglycemia, if any, is likely to be very modest, at least at the population level. 相似文献
7.
Carl R Harrington Sacha Lucchini Karyn P Ridgway Udo Wegmann Tracy J Eaton Jay CD Hinton Michael J Gasson Arjan Narbad 《BMC microbiology》2008,8(1):195
Background
The human gastrointestinal (GI) tract contains a diverse collection of bacteria, most of which are unculturable by conventional microbiological methods. Increasingly molecular profiling techniques are being employed to examine this complex microbial community. The purpose of this study was to develop a microarray technique based on 16S ribosomal gene sequences for rapidly monitoring the microbial population of the GI tract. 相似文献8.
9.
Priscila R Moreira Marcos A Maioli Hyllana CD Medeiros Marieli Guelfi Flávia TV Pereira Fábio E Mingatto 《Biological research》2014,47(1)
Background
The liver is an important organ for its ability to transform xenobiotics, making the liver tissue a prime target for toxic substances. The carotenoid bixin present in annatto is an antioxidant that can protect cells and tissues against the deleterious effects of free radicals. In this study, we evaluated the protective effect of bixin on liver damage induced by carbon tetrachloride (CCl4) in rats.Results
The animals were divided into four groups with six rats in each group. CCl4 (0.125 mL kg-1 body wt.) was injected intraperitoneally, and bixin (5.0 mg kg-1 body wt.) was given by gavage 7 days before the CCl4 injection. Bixin prevented the liver damage caused by CCl4, as noted by the significant decrease in serum aminotransferases release. Bixin protected the liver against the oxidizing effects of CCl4 by preventing a decrease in glutathione reductase activity and the levels of reduced glutathione and NADPH. The peroxidation of membrane lipids and histopathological damage of the liver was significantly prevented by bixin treatment.Conclusion
Therefore, we can conclude that the protective effect of bixin against hepatotoxicity induced by CCl4 is related to the antioxidant activity of the compound. 相似文献10.