INTERACTIONS
Comparative study of the effects of heavy metals on embryonic development of zebrafish
This study aimed to investigate the effects of heavy metals, such as copper, zinc, iron, cobalt, chromium, aluminium, manganese and molybdenum, on zebrafish egg hatching rate and the subsequent survival rate of the larvae. Each metal was used in the various concentrations of0.05 mg/L, 50 mg/L and 500 mg/L to detect the threshold limit of tolerance. The study's results showed significant differences in the hatching and survival rate of larvae between the control group and most of the experimental groups when adding heavy metals in various concentrations. The highest concentration (500 mg/L) of the induced heavy metals tested in this study resulted in total egg or larval mortality within 96 hr and significantly lower egg or larval life expectancy. Among the tested metals, zinc and molybdenum had the most significant impact on hatching time, in contrast to iron that did not differentiate the results from the control group. Copper, cobalt, chromium, aluminium and manganese did affect zebrafish eggs depending on their exposure concentrations, which differentiated the results from the control group. Also, the study's findings demonstrate a significant dependence of the hatched egg heart rate on the metal concentration, and in particular, higher concentrations of metals correspond to higher heart rate. Zinc, Molybdenum and copper was proved to be the most toxic heavy metals causing increased hazard rate to mortality up to 96 hr and shorter life expectancy. Finally, skeletal deformit ies that occasionally observed did not significantly affect the total life expectancy of the hatched eggs.
E. Gouva, C. Nathanailides, I. Skoufos, I. Paschos, F. Athanassopoulou, and I. S. Pappas,Comparative study of the effects of heavy metals on embryonic development of zebrafish, Aquaculture Research, 2020, 51, 3255-3276.
IRON
Molybdenum and iron mutually impact their homeostasis in cucumber (Cucumis sativus) plants
Molybdenum (Mo) and iron (Fe) are essential micronutrients required for crucial enzyme activities in plant metabolism. Here we investigated the existence of a mutual control of Mo and Fe homeostasis in cucumber (Cucumis sativus). Plants were grown under single or combined Mo and Fe starvation. Physiological parameters were measured, the ionomes of tissues and the ionomes and proteomes of root mitochondria were profiled, and the activities of molybdo-enzymes and the synthesis of molybdenum cofactor (Moco) were evaluated. Fe and Mo were found to affect each other's total uptake and distribution within tissues and at the mitochondrial level, with Fe nutritional status dominating over Mo homeostasis and affecting Mo availability for molybdo-enzymes in the form of Moco. Fe starvation triggered Moco biosynthesis and affected the molybdo-enzymes, with its main impact on nitrate reductase and xanthine dehydrogenase, both being involved in nitrogen assimilation and mobilization, and on the mitochondrial amidoxime reducing component. These results, together with the identification of >100 proteins differentially expressed in root mitochondria, highlight the central role of mitochondria in the coordination of Fe and Mo homeostasis and allow us to propose the first model of the molecular interactions connecting Mo and Fe homeostasis.
G. Vigani, D. Di Silvestre, A. M. Agresta, S. Donnini, P. Mauri, C. Gehl, F. Bittner, and I. Murgia,Molybdenum and iron mutually impact their homeostasis in cucumber (Cucumis sativus) plants, New Phytologist, 2017, 213, 1222-1241.
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Effect of molybdenum on other trace elements - iodine, manganese and tungsten, arsenic and selenium
Effect of molybdenum on other trace elements - iodine
The effect of molybdenum on iodine metabolism in rabbits was to cause a decrease in the initial rate of uptake of iodine by the thyroid [Robinson et al., 1965]. More iodine was retained in the plasma of molybdate-fed rabbits. In connection with iodine metabolism it is of interest that in certain areas where goitre is endemic in human beings it was found that the molybdenum/copper ratio in food was greater than in other areas although there was no relationship between the incidence of goitre and the individual concentrations of molybdenum and copper [Tsvetkova, 1969].
Tsvetkova, I. N., Gig. Sanit., 1969, 34, 92.
Robinson, G. A., Riddell, P. E. and McCarter, A., Can. J. Physiol. Pharmacol., 1965, 43, 723.
Effect of molybdenum on other trace elements - manganese and tungsten
Various workers have reported metabolic antagonisms between molybdenum and manganese and molybdenum and tungsten.
Vignoli, L. and Defretin, J. P., Biologie medicale, 1963, 52, 319.
Effect of molybdenum on other trace elements - arsenic and selenium
The sublethal interactive effects of arsenic (As), molybdenum (Mo), and selenium (Se) on Ceriodaphnia dubia using four levels (zero, IC12.5, IC25, and IC50 values) of each metal was performed on C. dubia survival and fecundity. Molybdenum and As in binary combinations were strongly antagonistic in their effects on C. dubia, even at their respective IC50 concentrations. The addition of Se to As-Mo mixtures significantly reduced survival and reproduction. The IC50 concentrations of either Mo or Se significantly reduced fecundity in all binary and tertiary mixtures.
Naddy, R.B., Lapoint, T.W., Klaine, S.J., Toxicity Of Arsenic, Molybdenum And Selenium Combinations To Ceriodaphnia-Dubia, Environmental Toxicology And Chemistry, 1995, 14, 329-336.
