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ABSTRACT: The capacity to form microscopic cords (cording) of Mycobacterium species has been related to their virulence. The compounds responsible for cording are unknown, but a recent study has shown that cording could be related to the fine structure of α-mycolic acids. This investigation attributes the need for a proximal cyclopropane in α-mycolic acids for cording in Mycobacterium tuberculosis and Mycobacterium bovis BCG and proposes cyclopropanases as good targets for new chemotherapeutic agents. As other Mycobacterium species in addition to M. tuberculosis and M. bovis form microscopic cords, it would be of major interest to know whether the relationship between proximal cyclopropanation of α-mycolic acids and cording could be extended to non-tuberculous mycobacteria. In this study, we have examined the correlation between the cording and cyclopropanation of α-mycolic acids in two species, Mycobacterium brumae and Mycobacterium fallax. Scanning electron microscopy images showed, for the first time to our knowledge, the fine structure of microscopic cords of M. brumae and M. fallax, confirming that these two species form true cords. Furthermore, NMR analysis performed on the same cording cultures corroborates the absence of cyclopropane rings in their α-mycolic acids. Therefore, we can conclude that the correlation between cording and cyclopropanation of α-mycolic acids cannot be extended to all mycobacteria. As M. brumae and M. fallax grow rapidly and have a simple pattern of mycolic acids (only α-unsaturated mycolic acids), we propose these two species as suitable models for the study of the role of mycolic acids in cording.
Microbiology 04/2012; 158(Pt 6):1615-21. · 3.06 Impact Factor
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ABSTRACT: In low-income countries some infections caused by nontuberculous mycobacteria are misdiagnosed as multidrug-resistant tuberculosis. In most of these settings the observation of microscopic cords is the only technique used to identify Mycobacterium tuberculosis in the laboratory. In this article we definitively demonstrate that Mycobacterium abscessus, an emerging pulmonary pathogen, also forms microscopic cords.
Journal of clinical microbiology 06/2011; 49(6):2293-5. · 4.16 Impact Factor
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ABSTRACT: The aggregation of mycobacterial cells in a definite order, forming microscopic structures that resemble cords, is known as cord formation, or cording, and is considered a virulence factor in the Mycobacterium tuberculosis complex and the species Mycobacterium marinum. In the 1950s, cording was related to a trehalose dimycolate lipid that, consequently, was named the cord factor. However, modern techniques of microbial genetics have revealed that cording can be affected by mutations in genes not directly involved in trehalose dimycolate biosynthesis. Therefore, questions such as "How does mycobacterial cord formation occur?" and "Which molecular factors play a role in cord formation?" remain unanswered. At present, one of the problems in cording studies is the correct interpretation of cording morphology. Using optical microscopy, it is sometimes difficult to distinguish between cording and clumping, which is a general property of mycobacteria due to their hydrophobic surfaces. In this work, we provide a new way to visualize cords in great detail using scanning electron microscopy, and we show the first scanning electron microscopy images of the ultrastructure of mycobacterial cords, making this technique the ideal tool for cording studies. This technique has enabled us to affirm that nonpathogenic mycobacteria also form microscopic cords. Finally, we demonstrate that a strong correlation exists between microscopic cords, rough colonial morphology, and increased persistence of mycobacteria inside macrophages.
Journal of bacteriology 04/2010; 192(7):1751-60. · 3.94 Impact Factor
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ABSTRACT: The leachates from the Garraf landfill located in a protected site (NE Spain) contain several potentially toxic substances such as heavy metals. Here we report the histopathological alterations produced by this pollution in wild specimens of an omnivorous species, the wood mouse, Apodemus sylvaticus, and an insectivorous species, the greater white-toothed shrew, Crocidura russula. Hepatic tissue presented the most severe alterations in both the species, namely cell cycle arrest (apoptosis and necrosis), inflammation, preneoplasic nodules, vacuolation and microsteatosis. The kidneys were altered more in the mice (presenting tubular necrosis and dilatation, inflammation, and cylinders) than in the shrews, suggesting that different metabolic pathways render shrews more tolerant to renal toxicity induced by pollutants. No pollution-related alterations were observed in lung, spleen, pancreas, gonads, oesophagus, intestine, or adrenals. We conclude that the two species could be used in conjunction as bioindicators to assess the effects of environmental pollution at different trophic levels.
Environmental Research 09/2009; 109(8):960-7. · 3.40 Impact Factor
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ABSTRACT: Historically impacted by anthropogenic activities, the nature reserve of Doñana (SW Spain) was affected by an unprecedented spillage of mud and acidic water from the Aznalcóllar pyrite mine in April 1998. Although several studies have addressed the influence of this spill on soils, water, and biota, there is little information on mammals, especially carnivorous species. We measured the concentrations of Fe, Mg, Pb, Hg, Cd, Zn, Cu, Mn, Mo, Co, and Cr in specimens of the greater white-toothed shrew, Crocidura russula, inhabiting the protected area affected by the mine spillage. We also examined other parameters to approach at the physiological effects of pollution. We found an increase in non-essential metals (Pb, Cd, and Hg), and morphometric, histological and genotoxic alterations. Age and gender were two significant factors explaining metal bioaccumulation: adults had higher Hg and Cd levels than juveniles, whereas males bioaccumulated more Pb and Co and less Mo than females. The micronucleus frequencies in blood erythrocytes were significantly higher in specimens from the polluted site than animals from the control site. Shrews from the impacted area also had hepatic alterations, namely increased liver-body ratio, focal necrosis, and signs of apoptosis in hepatocytes. Due to the relevance of small mammals in the diet of endangered species such as carnivorous birds and mammals, the findings of our study are of practical use for the management of the Doñana wildlife reserve and other protected Mediterranean wetlands.
Chemosphere 05/2009; 76(3):387-94. · 3.21 Impact Factor
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ABSTRACT: Although ecotoxicological data on heavy metals are abundant, information on other potentially toxic elements with attributed deficiency and/or toxic disturbances is scarce. Here we quantify zinc, copper, iron, manganese, chromium, molybdenum, strontium, barium, and boron in bones of greater white-toothed shrews, Crocidura russula, inhabiting two protected Mediterranean coastal sites: the Ebro Delta, a wetland impacted by human activities, and the Medas Islands, a reference site. Natural and anthropogenic inputs significantly increase Fe, Mn, Mo, Sr, Ba, and B in specimens from the Ebro Delta, whereas Cu and Cr were higher in Medas' shrews. Principal component analysis allowed complete separation between sites along the first two axes in particular due to B, Sr, and Cu. This study provides metal reference values in bones of insectivores, explores their variability and bioaccumulation patterns in depth, and assesses the potential environmental risk and toxicity for biota exposed to the above elements.
Environmental pollution (Barking, Essex: 1987) 02/2009; 157(4):1243-8. · 3.43 Impact Factor
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ABSTRACT: We assess the bioaccumulation of metals (Pb, Hg, Cd, Fe, Mg, Zn, Cu, Mn, Mo, Cr) and effects of landfill leachates on morphological (RI, relative weights), plasma (GPT, GOT, creatinine), and genotoxic (MNT) parameters in wood mice, Apodemus sylvaticus, inhabiting close the Garraf landfill site (NE Spain). Due to the high age- and sex-dependent variation in wild populations, we also studied the effect of these biotic factors on the parameters studied. Wood mice from the landfill site, sited in a partially protected area, showed more Cd, Fe, Zn, Cu, Mn, Mo, and Cr than specimens from the reference site. Moreover, mice near the landfill registered low RI and high relative renal weight, GPT, and MN frequency, which indicate that the landfill affects the health of wild mice. In contrast to sympatric shrews from a previous study, wood mice showed lower bioaccumulation of metals and lower variation caused by biotic factors. Moreover, the morphological and physiological alterations demonstrated that they were also more sensitive at environmental pollution. Given the contribution of small mammals to ecosystem function and the scarce ecotoxicological data on the effects of landfill pollution on wild terrestrial mammals, we consider that our study can be used to improve the management of this protected area.
Chemosphere 12/2007; 70(1):101-9. · 3.21 Impact Factor
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Alejandro Sánchez-Chardi
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ABSTRACT: In 1998, the protected area of Doñana, an important natural region in SW Europe, was affected with great amount of acidic waters and sludge from a pyrite mine loaded with toxic metals such as thallium (Tl). Since this ecological catastrophe, several studies have addressed the effects of this pollution on the flora and fauna in this protected area. However, in contrast to other non-essential metals, scarce information on Tl was available after this disaster, especially in terrestrial environments. This study reported a 3- and 10-fold increase in Tl in liver and kidneys, respectively, of the greater white-toothed shrew, Crocidura russula, in the polluted site in comparison with reference animals. Kidneys showed the highest concentrations of this metal in the polluted site, whereas both organs analysed have similar concentrations in the reference site. Although no significant age-dependent variation was found, adults had higher concentrations than juveniles. Moreover, females showed higher concentrations than males. These results demonstrate the high entrance and transfer of Tl in terrestrial food-chains. To the best of my knowledge, these data constitute the first measurements of Tl in mammals from the protected area of Doñana and are among the few available for insectivorous mammals.
Science of The Total Environment 10/2007; 383(1-3):237-40. · 3.29 Impact Factor
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ABSTRACT: Here we quantified the bioaccumulation of metals (lead, mercury, cadmium, iron, magnesium, zinc, copper, manganese, molybdenum, and chromium) and assessed several morphological (RI, relative weights) and genotoxic parameters as biomarkers of pollution from the landfill of Garraf (Barcelona, NE Spain). Specimens of Crocidura russula (Insectivora, Mammalia) from the landfill site showed increased Pb, Cd, Mg, Zn, Cu, and Cr concentrations in their tissues. Levels of mercury were below detection limits. Concentrations of Cd, Pb, and Cr varied significantly with age and no differences were found between males and females. While no differences were found in morphological parameters between shrews from the two sites, those from the polluted one showed more micronuclei in blood than those from reference site (1.786+/-0.272 vs. 0.088+/-0.045 per thousand; U=46.000, p<0.001). The considerable amounts of potentially toxic metals (Pb till 59.71 and Cd till 56.57microgg(-1) DW in kidneys) and the genotoxic effects indicate the harmful effect on biota. We consider necessary biomonitoring this landfill sited in a partially protected area.
Chemosphere 07/2007; 68(4):703-11. · 3.21 Impact Factor
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ABSTRACT: Heavy metals accumulation in parallel with the evaluation of physiological and biochemical effects resulting from continued metal exposure were considered here using for the first time the great white-toothed shrew Crocidura russula as an in vivo model. Shrews were originated from an abandoned lead/zinc mining area and from a reference area, both in Alentejo, southern Portugal. Hepatic contents of nickel, copper, zinc, cadmium, mercury and lead were quantified by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Haematological parameters (white blood cells, red blood cells, haemoglobin and haematocrit) were obtained in a Coulter Counter Analyser and biochemical markers of the redox balance (glutathione S-transferase, glutathione peroxidase, and glutathione reductase) activities were measured spectrophotometrically using a Duo-50 spectrophotometer. Compared with control animals, significantly higher concentration of hepatic cadmium (9.29 vs. 1.18 micorg/g dry weight) and nickel (1.56 vs. 0.343 microg/g dry weight) were detected in the shrews collected in the mining area. However, no significant changes were observed on haematological or enzymatic parameters in animals exposed to metal pollution. The obtained results show that shrews are good bioaccumulators of toxic heavy metals, but very tolerant to their effects, revealing an interesting long-term adaptation to polluted environments. In addition, this study provides reference values for haematological parameters and antioxidant enzymes levels in C. russula, which may be relevant for comparative purposes in further studies.
Science of The Total Environment 05/2007; 376(1-3):128-33. · 3.29 Impact Factor
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ABSTRACT: Hepatic and renal concentrations of iron, magnesium, zinc, lead, copper, manganese, mercury, cadmium, molybdenum, chromium, and nickel were quantified in shrews (Crocidura russula) inhabiting a pyrite mine site in Portugal. Several morphological parameters (body weight, residual index, and relative weights) were also examined to clarify the physiological effects of pollution. Shrews from the mine showed increased bioavailability of Fe, Pb, Hg, Cd, Mo, and Ni in comparison with reference specimens. Adult shrews had the highest Cd levels while Cr and Ni concentrations diminished. Intersexual differences were found for Mo and Ni. As a consequence of metal pollution, the relative hepatic weight was higher in shrews from the mine site when compared with reference specimens. These data indicate that C. russula is a good bioindicator of metal pollution. We also evaluated the toxic effects of Pb, Hg, Cd, and Ni, because several shrews from the polluted site showed high concentrations of these metals. To approximate at the real biological impact of abandoned mines, after this first step it is necessary to associate the bioaccumulation levels and morphological effects with other physiological, ecological and genetical biomarkers.
Chemosphere 03/2007; 67(1):121-30. · 3.21 Impact Factor
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ABSTRACT: We quantified bioaccumulation of lead, mercury, and cadmium in bones from 105 greater white-toothed shrews (Crocidura russula) collected at the Ebro Delta, a polluted area, and the Medas Islands, a control site. Lead and mercury levels varied with site, age, and sex, although statistical significances depended on each factor. Globally, shrews from the polluted area exhibited significantly higher concentrations of Pb and Hg. Increment of Pb with age was particularly remarkable in wetland animals and was interpreted in relation to human activities, namely hunting. Unlike males, females from the Ebro Delta maintained low Hg levels, which were associated with gestation and lactation. Cadmium levels did not differ between sites, sexes, or ages. This study provides the first data on heavy metals in mammals from this wetland and suggests that C. russula is a good bioindicator of metal pollution. We concluded that sex and age may represent an important source of variation in the bioaccumulation of these metals in wild populations.
Environmental Pollution 02/2007; 145(1):7-14. · 3.75 Impact Factor
