ELISA of polyclonal antibody to fish MT and study on heavy metal tolerance in fish

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Antibiotic Resistance and Heavy Metals Tolerance in Gram-Negative Bacteria from Diseased American Bullfrog (Rana catesbeiana) Cultured in Malaysia

A total of 140 bacterial isolates have been successfully isolated from various organs of diseased American bullfrog （Rana catesbeiana） cultured in Malaysia. The most frequently isolated bacteria was Edwardsiella spp. （46 isolates） followed by Aeromonas spp. （33 isolates）, Flavobacterium spp. （31 isolates）, and Vibrio spp. （30 isolates）. Majority of the bacterial isolates were found sensitive to furazolidone （85.0%）, chloramphenicol （85.0%）, oxolinic acid （90.0%）, florfenicol （95.0%）, and flumequine （97.5%）. On the other hand, most of the bacterial isolates were resistant to oleandomycin （77.5%） and lincomycin （87.5%）. Nitrofurantoin and flumequine can be inhibited the growth of all of Vibrio spp. whereas all isolates of Edwardsiella spp. were found sensitive to florfenicol and flumequine. Multiple antibiotic resistance （MAR） index were in range of 0.30-0.40, indicating that bacterial isolates from cultured bullfrogs may have received high risk exposure to the tested antibiotics. In addition, 90-100% of the isolates were resistant to copper, cadmium, and chromium. These results provided insight information on tolerance level of bacterial isolates from cultured bullfrogs to 21 antibiotics as well as heavy metals.

Cadmium and copper uptake and accumulation by Sesbania rostrata seedling, a N-fixing annual plant: implications for the mechanism of heavy metal tolerance

Sesbania rostrata,an annual tropical legume,has been found to be tolerant to heavy metals,with an unknown mechanism.It is a promising candidate species for revegetation at mine tailings.In this study,sequential extractions with five buffers and strong acids were used to extract various chemical forms of cadmium and copper in S.rostrata,with or without Cd or Cu treatments,so that the mechanisms of tolerance and detoxification could be inferred.Both metals had low transition rates from roots to the aboveground of S.rostrata.The transition ratio of Cd(4.00%)was higher than that of Cu(1.46%).The proportion of NaCl extracted Cd(mostly in proteinbinding forms)increased drastically in Cd treated plants from being undetectable in untreated plants.This suggests that Cd induced biochemical processes producing proteinlike phytochelatins that served as a major mechanism for the high Cd tolerance of S.rostrata.The case for Cu was quite different,indicating that the mechanism for metal tolerance in S.rostrata is metal-specific.The proportion of water-insoluble Cu(e.g.oxalate and phosphate)in roots increased significantly with Cu treatment,which partially explains the tolerance of S.rostrata to Cu.However,how S.rostrata copes with the high biotic activity of inorganic salts of Cu,which increased in all parts of the plant under Cu stress,is a question for future studies.Sesbania rostrata is among the very few N-fixing plants tolerant to heavy metals.This study provides evidence for the detoxification mechanism of metals in Sesbania rostrata.

Isolation and Physiological Characterization of Synechococcus cedrorum 1191 Strain Tolerant to Heavy Metals and Pesticides

The toxicity of heavy metals (Hg2 + , Zn2 + ) and pesticides has been investigated by comparing the physiological properties in wild and tolerant strains of Synechococcus cedrorum 1191. The differential pattern of growth, absorption spectra of pigments and nutrient uptake was observed in tolerant strain.

Subcellular Distribution and Chemical Forms of Cadmium in the Medicine Food Homology Plant Platycodon grandiflorum(Jacq.)A.DC.

Although Platycodon grandiflorum(Jacq.)A.DC.is a renowned medicine food homology plant,reports of excessive cadmium(Cd)levels are common,which affects its safety for clinical use and food consumption.To enable its Cd levels to be regulated or reduced,it is necessary to first elucidate the mechanism of Cd uptake and accumulation in the plant,in addition to its detoxification mechanisms.This present study used inductively couple plasma-mass-spectrometry to analyze the subcellular distribution and chemical forms of Cd in different tissues of P.grandiflorum.The experimental results showed that Cd was mainly accumulated in the roots[predominantly in the cell wall(50.96%-61.42%)],and it was found primarily in hypomobile and hypotoxic forms.The proportion of Cd in the soluble fraction increased after Cd exposure,and the proportion of insoluble phosphate Cd and oxalate Cd increased in roots and leaves,with a higher increase in oxalate Cd.Therefore,it is likely that root retention mechanisms,cell wall deposition,vacuole sequestration,and the formation of low mobility and low toxicity forms are tolerance strategies for Cd detoxification used by P.grandiflorum.The results of this study provide a theoretical grounding for the study of Cd accumulation and detoxification mechanisms in P.grandiflorum,and they can be used as a reference for developing Cd limits and standards for other medicine food homology plants.

Ectomycorrhizal fungi and dark septate endophyte inoculation improve growth and tolerance of Pinus tabulaeformis under cadmium stress

Forest trees can establish symbiotic associations with dark septate endophytes(DSEs)and ectomycorrhizal fungi(ECMF)simultaneously.However,the combined effects of these two fungi on the growth and cadmium(Cd)tolerance of host plants remain largely unexplored.To address this knowledge gap,a pot experiment was conducted to examine the effects of the interaction between an ECMF strain(Suillus granulatus)and a DSE strain(Pseudopyrenochaeta sp.)on Pinus tabulaeformis under Cd stress,by assessing plant growth and physiological parameters,nutrient uptake,and soil properties.Notably,the colonization rates of both fungal strains were found to increase in response to Cd stress,with the extent of this increase being influenced by the specific fungal species and the Cd level in the soil.Compared to the non-inoculation treatment,single inoculation with fungal strain resulted in enhanced biomass,root development,and nutrient contents in P.tabulaeformis seedlings under Cd stress.Furthermore,a synergistic effect was observed when these seedlings were co-inoculated with S.granulatus and Pseudopyrenochaeta sp.,as indicated by significantly greater measurements in various indicators compared to both the single and non-inoculation treatments.Fungal inoculation effectively regulated the antioxidant defense responses and photosynthesis of P.tabulaeformis seedlings subjected to Cd stress,particularly in the co-inoculation treatment.In addition,fungal inoculation facilitated the Cd accumulation in P.tabulaeformis,suggesting a promising potential for the implementation of bioremediation strategies in the areas contaminated with heavy metals.The findings from this study indicate that the utilization of root symbiotic fungi obtained from stress environments could potentially enhance the growth performance and tolerance of P.tabulaeformis towards heavy metals,and co-inoculation of both fungal groups may result in even more pronounced synergistic effects on the overall fitness of the plant.

Responses of Sesbania rostrata and S. cannabina to Pb, Zn, Cu and Cd toxi-cities

Responses of Sesbania rostrata and S. cannabina to Pb, Zn, Cu and Cd toxicities were assessed by a seed-suspending seedbed(SSS) approach. The results showed that the SSS approach was suitable for testing the tolerance of a plant to the stress of toxic metals. The endpoints include seed germination success, straightened radicle and hypocotyl of the seedlings from the seeds. The measurements could be done easily and accurately. It was found that the elongation of radicle was the most sensitive indicator to the stress of heavy metals among the endpoints. When exposure to lower or medium concentrations of Pb, Zn, and Cd, the development of the lateral roots were favorable. Species of S. rostrata was more tolerant than S. cannabina to the heavy metals, especially to Zn and Cd. The ED 50 of Pb, Zn, Cu and Cd were 32.90, 5.32, 4.40 and 12.00 μg/ml for S. rostrata, respectively, and they were 30.11, 2.87, 4.05 and 4.94 μg/ml respectively for S. cannabina.

Metal accumulation and tolerance in wetland plants

This paper briefly reviews the progress in studies of wetland plants in terms of heavy metal pollution.The current research mainly includes the following areas:(1)metal uptake,translocation,and distributions in wetland plants and toxicological effects on wetland plants,(2)radial oxygen loss(ROL)of wetland plants and its effects on metal mobility in rhizosphere soils,(3)constitutional metal tolerance in wetland plants,and(4)mechanisms of metal tolerance by wetland plants.Although a number of accomplishments have been achieved,many issues still remain unanswered.The future research effort is likely to focus on the ROL of wetland plants affecting metal speciation and bioavailability in rhizosphere soils,and the development of rhizosphere management technologies to facilitate and improve practical applications of phytoremediation of metalpolluted soils.

Advances in fungal-assisted phytoremediation of heavy metals:A review

Trace metals such as manganese(Mn),copper(Cu),zinc(Zn),and iron(Fe)are essential for many biological processes in plant life cycles.However,in excess,they can be toxic and disrupt plant growth processes,which is economically undesirable for crop production.For this reason,processes such as homeostasis and transport control of these trace metals are of constant interest to scientists studying heavily contaminated habitats.Phytoremediation is a promising cleanup technology for soils polluted with heavy metals.However,this technique has some disadvantages,such as the slow growth rate of metal-accumulating plant species,low bioavailability of heavy metals,and long duration of remediation.Microbial-assisted phytoremediation is a promising strategy for hyperaccumulating,detoxifying,or remediating soil contaminants.Arbuscular mycorrhizal fungi(AMF)are found in association with almost all plants,contributing to their healthy performance and providing resistance against environmental stresses.They colonize plant roots and extend their hyphae to the rhizosphere region,assisting in mineral nutrient uptake and regulation of heavy metal acquisition.Endophytic fungi exist in every healthy plant tissue and provide enormous services to their host plants,including growth enhancement by nutrient acquisition,detoxification of heavy metals,secondary metabolite regulation,and enhancement of abiotic/biotic stress tolerance.The aim of the present work is to review the recent literature regarding the role of AMF and endophytic fungi in plant heavy metal tolerance in terms of its regulation in highly contaminated conditions.

Nickel levels in arthropods associated with Ni hyperaccumulator plants from an ultramafic site in New Caledonia

Arthropods （mainly insects） were collected from a forest site that contained at least six species of Ni hyperaccumulators. Whole body Ni analysis was performed for 12 arthropod taxa, two of which were studied at different life cycle stages. We found two Nitolerant insects. The pentatomid heteropteran Utana viridipuncta, feeding on fruits of the Ni hyperaccumulator Hybanthus austrocaledonicus, contained a mean of 2 600 μg Ni/g in nymphs and 750μg Ni/g in adults. The tephritid fly Bactrocera psidii, feeding on pulp of Sebertia acuminata fruits that contained 6 900μg Ni/g, contained 420μg Ni/g as larvae that had evacuated their guts and significantly less （65μg Ni/g） as adults. European honeybees （Apis mellifera） visiting flowers of the Ni hyperaccumulator H. austrocaledonicus contained significantly more Ni （8-fold more） than those collected from flowers of Myodocarpus fraxinifolius, a non-hyperaccumulator. Our results show that some insects feed on Ni hyperaccumulator plants and that their feeding mobilizes Ni into local food webs.

High-nickel insects and nickel hyperaccumulator plants： A review

Insects can vary greatly in whole-body elemental concentrations. Recent investigations of insects associated with Ni hyperaccumulator plants have identified insects with relatively elevated whole-body Ni levels. Evaluation of the limited data available indicates that a whole-body Ni concentration of 500μg Ni/g is exceptional： I propose that an insect species with a mean value of 500μg Ni/g or greater, in either larval/nymphal or adult stages, be considered a ＂high-Ni insect＂. Using the 500μg Ni/g criterion, 15 species ofhigh-Ni insects have been identified to date from studies in Mpumalanga （South Africa）, New Caledonia and California （USA）. The highest mean Ni concentration reported is 3 500 μg Ni/g for nymphs of a South African Stenoscepa species （Orthoptera： Pyrgomorphidae）. The majority of high-Ni insects （66%） are heteropteran herbivores. Studies of high-Ni insect host preference indicate they are monophagous （or nearly so） on a particular Ni hyperaccumulator plant species. Much of the Ni in bodies of these insects is in their guts （up to 66%-75%）, but elevated levels have also been found in Malpighian tubules, suggesting efficient elimination as one strategy for dealing with a high-Ni diet. Tissue levels of Ni are generally much lower than gut concentrations, but up to 1200μg Ni/g has been reported from exuviae, suggesting that molting may be another pathway of Ni elimination. One ecological function of the high Ni concentration of these insects may be to defend them against natural enemies, but to date only one experimental test has supported this ＂elemental defense＂ hypothesis. Community-level studies indicate that high-Ni insects mobilize Ni into food webs but that bioaccumulation of Ni does not occur at either plant-herbivore or herbivorepredator steps. Unsurprisingly, Ni bioaccumulation indices are greater for high-Ni insects compared to other insect species that feed on Ni hyperaccumulator plants. There is some evidence of Ni mobilization into food webs by insect visitors to flowers ofNi hyperaccumulator plants, but no high-Ni insect floral visitors have been reported.

Lygus hesperus （Heteroptera： Miridae） tolerates high concentrations of dietary nickel

Nickel hyperaccumulator plants contain unusually elevated levels of Ni （〉 1 000 μg Ni/g）. Some insect herbivores, including Lygus hesperus （Western tarnished plant bug）, have been observed feeding on the California Ni hyperaccumulator Streptanthus polygaloides. This bug may be able to utilize S. polygaloides as a host either through its feeding behavior or by physiological tolerance of Ni. This experiment determined the Ni tolerance of L hesperus by offering insects artificial diet amended with 0, 0.4, 1, 2, 4.5, 10, 20 and 40 mmol Ni/L and recording survival. Survival varied due to Ni concentration, with diets containing 10 mmol Ni/L and greater resulting in significantly lower survival compared to the control （0 mmol Ni/L） treatment. Insects tolerated diet containing as much as 4.5 mmol Ni/L, a relatively elevated Ni concentration. I conclude that L hesperus can feed on S. polygaloides because it is Ni-tolerant, probably due to physiological mechanisms that provide it with resistance to plant chemical defenses including elemental defenses such as hyperaccumulated Ni.