Interrelationships in trace-element metabolism in metal toxicities in <i>Neurospora crassa</i>

Sastry, K. Subramanya; Adiga, P. Radhakantha; Venkatasubramanyam, V.; Sarma, P. S.

doi:10.1042/bj0850486

Cited by 36 publications

(25 citation statements)

References 12 publications

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“…Further studies in the same system showed growth inhibition due to cobalt could be reversed to some extent by iron [63] and cobalt induced iron deficiency resulted in the formation of siderochrome [16],[64]. In S. cerevisiae , even at sub-lethal cobalt concentrations, iron regulon is induced resulting in immediate expression of iron transporter genes to increase intracellular iron content.…”

Section: Discussionmentioning

confidence: 95%

Importance of Mitochondria in Survival of Cryptococcus neoformans Under Low Oxygen Conditions and Tolerance to Cobalt Chloride

et al. 2008

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Cryptococcus neoformans is an environmental fungal pathogen that requires atmospheric levels of oxygen for optimal growth. For the fungus to be able to establish an infection, it must adapt to the low oxygen concentrations in the host environment compared to its natural habitat. In order to investigate the oxygen sensing mechanism in C. neoformans, we screened T-DNA insertional mutants for hypoxia-mimetic cobalt chloride (CoCl2)-sensitive mutants. All the CoCl2-sensitive mutants had a growth defect under low oxygen conditions at 37°C. The majority of mutants are compromised in their mitochondrial function, which is reflected by their reduced rate of respiration. Some of the mutants are also defective in mitochondrial membrane permeability, suggesting the importance of an intact respiratory system for survival under both high concentrations of CoCl2 as well as low oxygen conditions. In addition, the mutants tend to accumulate intracellular reactive oxygen species (ROS), and all mutants show sensitivity to various ROS generating chemicals. Gene expression analysis revealed the involvement of several pathways in response to cobalt chloride. Our findings indicate cobalt chloride sensitivity and/or sensitivity to low oxygen conditions are linked to mitochondrial function, sterol and iron homeostasis, ubiquitination, and the ability of cells to respond to ROS. These findings imply that multiple pathways are involved in oxygen sensing in C. neoformans.

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Section: Discussionmentioning

confidence: 95%

Importance of Mitochondria in Survival of Cryptococcus neoformans Under Low Oxygen Conditions and Tolerance to Cobalt Chloride

et al. 2008

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“…Cations such as Mg 2+ and Ca 2+ can reduce metal inhibition (Gadd and Griffiths 1978;. Magnesium cation may antagonize Ni 2+ uptake into the cell in some microorganisms (Sastry et al 1962;Babich and Stotzky 1983;Nelson and Kennedy 1972;Kumar et al 1992); however, in Saccharomyces cerevisiae, Ni 2+ is actively taken up through a Mg 2+ transport system . Yeast and fungi produce citric acid and fungi produce oxalic acid that can chelate cationic metals and reduce their bioavailability and uptake (Gadd and Griffiths 1978).…”

Section: Accumulationmentioning

confidence: 96%

Essentiality of nickel and homeostatic mechanisms for its regulation in terrestrial organisms

Phipps¹,

Tank²,

Wirtz³

et al. 2002

Environ. Rev.

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Nickel (Ni) is a naturally occurring element with many industrial uses, including in stainless steel, electroplating, pigments, and ceramics. Consequently, Ni may enter the environment from anthropogenic sources, resulting in locally elevated concentrations in soils. However, Ni is a minor essential element, and, therefore, biota have established systems that maintain Ni homeostasis. This paper discusses the role of Ni as an essential element and reviews storage, uptake, and transport systems used to maintain homeostasis within terrestrial biota. The bioaccumulation and distribution of metals in these organisms are also addressed. In all cases, information on Ni essentiality is very limited compared to other essential metals. However, the available data indicate that Ni behaves in a similar manner to other metals. Therefore, inferences specific to Ni may be made from an understanding of metal homeostasis in general. Nevertheless, it is evident that tissue and organ Ni concentrations and requirements vary considerably within and between species, and metal accumulation in various tissues within a single organism differs as well. High rates of Ni deposition around smelters indicate that Ni in acidic soils may reach concentrations that are toxic to plants and soil decomposers. However, with the exception of hyperaccumulator plants, Ni does not biomagnify in the terrestrial food web, suggesting that toxicity to higher trophic levels is unlikely.

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“…A comparison of the influence of Mg2+ and Fe3+ on metal toxicities in the three Ni2+-resistant strains with corresponding effects of these ions in Em (Sivarama Sastry et al, 1962b) and in N. crassa CoR (see above) reveals the differences in metal-ion interactions obtaining in these strains. As in CoR (but not in Em), Fe3+ has no beneficial effect on Ni2+ and Co2+ toxicities in Ni2+-resistant strains.…”

Section: Discussionmentioning

confidence: 99%

“…Toxicities of Co2+, Ni2+ and Zn2+ have been examined in Neurospora crassa Em 5297a (Healy et al, 1955;Sivarama Sastry et al, 1962b) and in the first cobalt-resistant strain (N. crassa COR) isolated previously in this laboratory (Venkateswerlu & Sivarama Sastry, 1973). In the parent wild-type strain (Em), toxicity of Co2+ induces an iron deficiency, and consequent effects on catalase (Healy et al, 1955) and on growth (Sivarama Sastry et al, 1962b) are reversed by supplemented Fe3+, the latter without attendant suppression of Co2+ uptake. In contrast, such Co2+-Fe3+ antagonism does not obtain in N. crassa COR, and the mechanism of resistance involves an alteration in its iron metabolism to insensitivity to Co2+ inhibition.…”

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confidence: 99%

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Interrelationships in trace-element metabolism in metal toxicities in nickel-resistant strains of Neurospora crassa

Mohan¹,

Sastry²

1983

Biochemical Journal

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Three different Ni2+-resistant strains of Neurospora crassa (NiR1, NiR2 and NiR3) have been isolated. All are stable mutants and are fourfold more resistant to Ni2+ than the parent wild-type strain. NiR1 and NiR2 are also sixfold more resistant to Co2+, whereas NiR3 is only twice as resistant to Co2+; the former two are also twofold more resistant to Zn2+, but NiR3 is not. These three strains also differ in sensitivity to Cu2+. Toxicities and concomitant accumulation patterns of Ni2+, Co2+ and Cu2+ have been examined in these strains. NiR1 and NiR2, despite quantitative individual differences, generally accumulate very high amounts of Ni2+ and Co2+, and Mg2+ reverses the toxicities of these two ions by different mechanisms; Ni2+ uptake is suppressed, but not that of Co2+. In NiR3, Mg2+ controls uptake of both Ni2+ and Co2+. Studies indicate that two kinds of Ni2+-resistant strains of N. crassa exist; one kind is resistant because it can tolerate high intracellular concentrations of heavy-metal ions, whereas the other is resistant because it can control metal-ion accumulation.

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Interrelationships in trace-element metabolism in metal toxicities in Neurospora crassa

Cited by 36 publications

References 12 publications

Importance of Mitochondria in Survival of Cryptococcus neoformans Under Low Oxygen Conditions and Tolerance to Cobalt Chloride

Importance of Mitochondria in Survival of Cryptococcus neoformans Under Low Oxygen Conditions and Tolerance to Cobalt Chloride

Essentiality of nickel and homeostatic mechanisms for its regulation in terrestrial organisms

Interrelationships in trace-element metabolism in metal toxicities in nickel-resistant strains of Neurospora crassa

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